X-ray Sensor Joint Workshop - From Soft to Hard X-rays

12 Jan 2026, 08:00 → 16 Jan 2026, 18:00 Europe/Zurich

ML E12 (ETH)

Anna Bergamaschi (PSI - Paul Scherrer Institut), Simone Finizio (PSI - Paul Scherrer Institut), Dominic Greiffenberg (PSI - Paul Scherrer Institut), Marie Ruat (ESRF), Bernd Schmitt (PSI - Paul Scherrer Institut), Matthew Veale (STFC), Jiaguo Zhang (PSI - Paul Scherrer Institut), Marco Stampanoni (PSI - Paul Scherrer Institut), Johanna Miriam Antoch (PSI - Paul Scherrer Institut)

 

This joint workshop brings together experts and users in the fields of soft X-ray detectors and high-Z sensor technologies for a comprehensive five-day event (12 - 16 January 2026).

The first three days will focus on the latest advancements in soft X-ray detection, addressing key challenges and innovations in sensor technologies, detector performance enhancement, and various applications in photon science. 

In the final two days, the workshop will transition to the traditional High-Z Sensor Workshop (HIZPAD), which will delve into the development and application of high-Z detectors for hard X-rays. Presentations will cover the latest developments in high-Z sensor fabrication and characterization, encouraging discussion between the participants.

This joint event will foster collaboration between researchers from diverse fields, encouraging cross-disciplinary exchange and the identification of new opportunities for synergy between soft X-ray and high-Z sensor technologies. 

Registration for the two workshops is separate, and attendees have the option to participate in either one or both workshops.

Flyer_A0_XRaySensors.pdf

Monday 12 January

08:00 → 09:00 Registration

09:00 → 09:15 Soft X-ray Detectors - Welcome and general information

09:00 Welcome

Speakers: Anna Bergamaschi (PSI - Paul Scherrer Institut), Jiaguo Zhang (PSI - Paul Scherrer Institut), Simone Finizio (PSI - Paul Scherrer Institut)

09:15 → 10:30 Flash Talks

09:30 Sensor development at BNL

Speaker: GIOVANNI PINAROLI (BNL)

09:35 X-ray sensor development at SINTEF

Speaker: Marius Mæhlum Halvorsen (SINTEF)

09:40 Development Activities at PAL-XFEL

Recent progress has been made in the development of silicon sensors and advanced detector technologies at PAL-XFEL.

For silicon sensor R&D, the third fabrication run of PIN photodiodes has been completed, incorporating multiple anti-reflection coating (ARC) designs optimized for wavelengths ranging from the vacuum ultraviolet to the visible region. Detailed characterization of devices from the second and third fabrication runs is in progress. In parallel, studies of low gain avalanche detectors (LGADs) are being carried out as part of ongoing R&D efforts.

In the PERCIVAL detector collaboration, re-spin sensors have been fabricated and tested. Calibration activities are underway, and analysis of beam test data is ongoing. At PAL-XFEL, calibration setups are being performed using front-side illumination detectors, while back-side illumination detectors are undergoing laboratory tests such as system integration and power-on procedures. These efforts contribute to the optimization of detector architecture and performance evaluation for FEL applications.

These developments demonstrate continuous progress toward establishing reliable silicon sensors and versatile detector systems for soft X-ray beamlines at PAL-XFEL.

Speaker: HyoJung Hyun (Pohang Accelerator Laboratory)

09:45 Activity and techical capability at FBK

Speaker: Maurizio Boscardin (Fondazione Bruno Kessler)

09:50 XAPPHIRE Pathfinder: R&D towards a High-Rate Unified Detector Platform for Soft- and Hard-X-ray Imaging

Speaker: Prof. Matteo Porro (Europen XFEL GmbH - Ca' Foscari, University of Venice)

09:55 Detector development activities at MAX IV

Speaker: Dr Michele Cascella (MAX IV (Lund University))

10:00 Detector activities at SPring-8/SACLA, and status of NanoTerasu, a new Soft to Tender X-ray synchrotron radiation facility

Speaker: Fabienne Orsini (RIKEN Spring-8)

10:05 Research programs and facilities on X-ray sensors and ASICs at SDICLab-Polimi

The research activities and facilities of the Semiconductor Devices and Integrated Circuits Laboratory (SDICLab) at Politecnico di Milano will be presented. Results and programs on silicon and compound semiconductor sensors together with the design of associated custom front-end electronics and ASICs will be summarized.

Speaker: Giuseppe Bertuccio (Politecnico di Milano, Department of Electronics, Information and Bioengineering, Como, IT; National Institute of Nuclear Physics (INFN), Milan Section, Milan, IT)

10:10 Ultrasoft x-ray NEXAFS with silicon drift detectors at the VLS-PGM Beamline

Speaker: Daniel Correia (VLS-PGM Beamline, Canadian Light Source)

10:15 Soft X-ray sensor developments at DESY

Speaker: David Pennicard (DESY)

10:30 → 11:00 Coffee Break

11:00 → 12:00 Flash Talks

11:00 Challenging Needs for Diagnostics for SOLEIL II

With the upcoming upgrade of the SOLEIL synchrotron planned for 2028, we face the challenge of providing high-performance beam diagnostics for all 29 beamlines, whose energy spectra range from deep infrared to gamma rays. Currently, around 300 diagnostic systems, comprising 15 device types, monitor photon beam position, shape, and intensity at SOLEIL beamlines, with some in operation for over 15 years. To ensure a smooth restart post-upgrade, most diagnostics devices must be modernized and standardized for efficient deployment and management. The upgraded source will introduce significant challenges, including photon flux increases up to 100 times and beam spot sizes of 1 µm, necessitating sub-micron spatial resolution. Conversely, some beamlines will use expanded, lower-flux beams, also requiring precise diagnostics. Often, in situ, real-time measurements of beam characteristics are critical for live beam corrections such as flux control, and sample alignment, while preserving beam coherence—demanding ultra-thin, semi-transparent sensors, especially difficult in the soft X-ray regime. Future diagnostics must thus cover a broad range: energies from soft X-rays to 100 keV, beam sizes from 1 µm to several mm, and significantly higher photon rates. We are currently identifying existing systems and specifying future beam diagnostics needs in preparation for the upgrade.
Our in-house development focuses on soft X-rays and high photon intensities. One promising candidate for handling soft X-ray energies is thin diamond films with NV centres, which have produced encouraging results as a beam imager in Taiwan [1]. Regarding high photon intensities, silicon carbide (SiC) is an interesting sensor material because it is radiation hard and can be manufactured to a high quality [2]. However, manufacturing a very thin sensor with 80% transmission of the soft X-ray beam remains the main challenge for both materials.
We are seeking solutions for very thin sensors (1–3 µm) and welcome other creative ideas for efficient beam diagnostics (shape, position, intensity), particularly in the soft X-ray range.

[1] Y.-H. Yang et al., “Eco-friendly , High-Resolution Fluorescence Diamond-Based Broadband EUV and X-Ray Beam Profiler System,” in 2025 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), May 2025, pp. 1–5. doi: 10.1109/I2MTC62753.2025.11079069.
[2] G. Trovato et al., “SiC free-standing membrane for X-ray intensity monitoring in synchrotron radiation beamlines,” J. Synchrotron Radiat., vol. 32, no. 1, Art. no. 1, Jan. 2025, doi: 10.1107/S1600577524010646.

Speaker: Marie Andrä (SOLEIL synchrotron)

11:05 Development of large area pixel array sensors for STARLIGHT

TARLIGHT (SemiconducTor Array detectoR with Large dynamIc ranGe and cHarge inTegrating readout) is the pixel array detector developed for SHINE (Shanghai HIgh repetitioN rate XFEL and Extreme light facility), which is a hard XFEL facility with high repetition rate up to 1MHz at Shanghai. The detector is modular designed with each module consisting of a 10.5mm×2.77mm sensor bump bonded to 2×8 readout ASICs. The pixels are laid out on a 99μm pitch and 128×128 array per ASIC. Consequently, one module has 256k pixels. We fabricated a pixelated silicon sensor on a 500 μm-thick, high resistivity (> 5 kΩ·cm) n-type and double-sided polished 8-inch silicon wafer at the Institute of Microelectronics of the Chinese Academy of Sciences (IMECAS). To produce this large area sensor, advanced stitching process was employed. The electrical characterizations of the sensors have been investigated. The drain currents of the CCR (Current Collected Ring) is 100nA @ 200V and the breakdown voltage exceeds 300V. In future we plan to organize TCT measurements and study the effects of radiation damages.

Speakers: Qionghua Zhai, Xudong JU (ShanghaiTech University)

11:10 Pixel detectors proposed for the soft x-ray stations of XFEL facilities in Shanghai

X-ray free-electron laser (XFEL) facilities that can provide coherent x-ray pulses with high intensity and short duration are useful tools in diverse scientific applications. There are two XFEL facilities in Shanghai. The Shanghai soft X-ray Free-Electron Laser facility (SXFEL) has been running since 2022, and the Shanghai HIgh repetitioN rate XFEL and Extreme light facility (SHINE) is under construction. High performance pixel detectors for soft x-ray detection are demanded by several end-stations on the two facilities. Currently, both hybrid pixel detector and CMOS detector are proposed for different experimental methods. New techniques that can improve the detector performance in soft x-ray range are anticipated.

Speaker: Jingkai Xia (Pixel detectors proposed for the soft x-ray stations of XFEL facilities in Shanghai)

11:15 X-ray detector development at the High Energy Photon Source (HEPS)

Speaker: Wei Wei (IHEP)

11:20 Towards charge sharing analysis for user operation at the European XFEL

The Heisenberg-RIXS spectrometer (hRIXS) at the Spectroscopy and Coherent Scattering (SCS) instrument of the European XFEL is dedicated to performing resonant inelastic X-ray scattering (RIXS) measurements in the time domain, with time and energy resolution approaching the Heisenberg limit imposed by the uncertainty relations [1, 2]. The spectrometer uses a dispersive element and requires a detector with a position resolution in the order of 5 μm along the spectroscopic dimension capable of detecting photons with an energy below 1 keV. Furthermore a high frame rate capability is necessary, in order to exploit the pulse structure of the European XFEL, which provides pulse trains at 10 Hz in which individual X-ray pulses are delivered at rates of up to 4.5 MHz.
A prototype hybrid detector, developed in a collaboration of the Paul Scherrer Institute (PSI) and Fondazione Bruno Kessler (FBK), features X-ray-sensitive Inverse Low Gain Avalanche Diode (iLGAD) sensors. They are combined with the widely adopted charge-integrating readout application specific integrated circuit (ASIC) JUNGFRAU [3, 4]. The iLGAD sensor is segmented into rectangular pixels with a size of 25×225 μm2 each, offering a high resolution along the dispersion direction. In order to achieve the required spatial resolution, photon hit position finding algorithms which exploit charge sharing events are being investigated, allowing for a position determination with sub-pixel resolution. Currently different approaches for event classification are considered, evaluating their suitability and robustness in an automated data analysis framework, i.e. needing minimal expert intervention, in order to be employed in routine user operation. We will briefly report on the status and appreciate feedback, sharing of experiences and additional ideas regarding this kind of event classification.

[1] Van den Brink, Jeroen. "Resonant inelastic x-ray scattering on elementary excitations."
Rev. Mod. Phys 83 (2011): 705.
[2] Schlappa, Justine, et al. "The Heisenberg-RIXS instrument at the European XFEL." Synchrotron Radiation 32.1 (2025).
[3] Mozzanica, A., et al. "The JUNGFRAU detector for applications at synchrotron light sources and XFELs." Synchrotron Radiation News 31.6 (2018): 16-20.
[4] Hinger, Viktoria, et al. "Resolving soft X-ray photons with a high-rate hybrid pixel detector." Frontiers in Physics 12 (2024): 1352134

Speaker: Philip Pfäfflein (European XFEL GmbH)

11:25 A Generic Line Profile Model for Pixelated X-ray Detectors Incorporating Charge Sharing and Trapping

Speaker: Abhay Kumar

11:30 Hybrid a-Se/a-Se and its applications

Speaker: Shiva Abbaszadeh

11:35 Calibration of the DEPFET-based DSSC 1-Megapixel Camera'

Speaker: Charles Townsend-Rose (European XFEL)

11:40 Beyond CCDs: Monolithic CMOS image sensors for soft X-ray astronomy

Speaker: Thomas Buggey (The Open University)

11:45 Detection of Low Energy Electrons Using Medipix Detectors

Speaker: Rory McFeely (University of Glasgw)

11:50 Capillary-based Soft X-ray Ptychography for Ultimate 4D Spectro-Microscopy with Versatile Sample Environment

X-ray imaging techniques enabled a significant advancement in the understanding of the physics driving magnetic systems, thanks to the possibility of combining element selectivity, sensitivity to the magnetic and antiferromagnetic ordering, and high spatial and temporal resolutions. Looking forward to the upcoming (fourth) generation of synchrotrons, new frontiers in spectroscopy and microscopy are emerging, most notably the combination of multiple cutting-edge detection schemes in the same experiment. Examples of such “multimodal” experiments are time-resolved nano-tomography and spectro-imaging with simultaneous sensitivity to chemical heterogeneity and vector-spin orientation. Such experiments would not average over any dimension, providing unprecedented insights into real, imperfect functional materials and elucidating how a material’s nanostructure generates functionality. As fourth-generation light sources also promise wavelength-limited spatial resolution, they are often referred to as “ultimate microscopes” (e.g., PETRA-IV). However, developing endstation instruments that realize this potential in practice remains an open challenge.

In this project we aim to create the first coherent, digital soft X-ray ptychography endstation with a highly versatile sample environment (temperature control down to 100 K, magnetic fields up to 1 T, 3D laminography, time-resolved imaging using GHz electrical and femtosecond optical excitation). To this end, we will employ capillary optics that extend the working distance compared to conventional zoneplates from sub-millimeter to several centimeters. The endstation is currently being built and will be located at the PETRA-III P04 beamline. Our scientific goal is to leverage this instrument to integrate chemical-spectroscopic and magnetic contrast with 3D resolution under uniform conditions and thereby examine the correlation between emergent textures and nanoscale material’s defects, for example, in permanent magnets and skyrmion materials.

Speaker: Boris V. Sorokin (1Universität Augsburg, Augsburg, Germany)

12:00 → 13:30 Lunch

13:30 → 14:50 Applications - I

Convener: Simone Finizio (PSI - Paul Scherrer Institut)

13:30 Applications of Soft X-ray Detectors in Coherent Diffractive Imaging

The ability to computationally transform coherent diffraction patterns into high spatial resolution images in coherent diffractive imaging (CDI) experiments at synchrotrons relies on the detection of weak signals of scattered photons. CDI techniques, such as X-ray ptychography, in the soft X-ray regime have been hampered by the challenging photon detection in this energy range. Nonetheless, microspectroscopy with soft X-rays is invaluable for the characterisation of chemical and ferroic properties of materials. The recent development of the iLGAD EIGER 1, which is the first single-photon counting detector in the soft X-ray energy range has improved ptychographic imaging. An overview of recent imaging experiments in condensed matter physics 2 3 4 and other scientific areas that stand to benefit from CDI in the soft X-ray energy range will be provided.

1 F. Baruffaldi et al., Commun. Phys. 8, 321 (2025).
2 T. A. Butcher et al., Adv. Mater. 36, 2311157 (2024).
3 T. A. Butcher et al., Phys. Rev. Appl. 23, L011002 (2025).
4 T. A. Butcher et al., Phys. Rev. B 111, L220409 (2025).

Speaker: Tim A. Butcher (Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy)

13:50 Advancing Soft X-ray Instrumentation for High-Resolution Microscopy and Imaging at SoftiMAX

The SoftiMAX beamline at MAX IV, commissioned in 2020, provides a versatile platform for soft X-ray spectromicroscopy and imaging in the 275–2500 eV range. The Scanning Transmission X-ray Microscopy (STXM) end-station, initially based on the ALS conceptual design with interferometric sample positioning, has since undergone extensive mechanical redesign and software optimisation to improve stability, flexibility, and user operation. Today, SoftiMAX routinely delivers spatial resolution of 20–30 nm with STXM, and sub-10 nm resolution with ptychography. These capabilities enable detailed chemical and structural imaging across a broad range of scientific fields, including materials science, catalysis, and energy research.

Detector development is central to further enhancing SoftiMAX’s imaging performance. Current capabilities rely on a suite of systems tailored to different energy ranges and acquisition needs: the Tuscen Dhyana 95 (275–900 eV, back-illuminated sCMOS), the Andor Zyla 5.5 (500–2500 eV, scintillator-coupled sCMOS), and, most notably, a prototype EIGER LGAD detector for soft X-Ray range (500–2500 eV, 512×512 pixels). The latter was successfully operated at SoftiMAX in combination with the SOPHIE end-station, hosted during a dark period at the Swiss Light Source. Building on this experience, the EIGER is now being commissioned in our new CHIARA end-station, designed to extend high-resolution imaging and ptychography capabilities.

This poster will highlight recent progress and outline how collaborative instrumentation development - particularly next-generation detector integration - strengthen and expand the microscopy and imaging capabilities of SoftiMAX.

Speaker: Igor Beinik (MAX IV, Lund University)

14:10 Plans and Requirements for 2D Soft X-ray Detection at BESSY II

Two scanning transmission x-ray microscopes—MAXYMUS and MYSTIIC—are currently operated at undulator beamlines of BESSY II. Initial demonstrations of soft x-ray ptychography were previously conducted at MAXYMUS, successfully overcoming the resolution limits of conventional soft x-ray optics. However, these efforts were constrained by the limitations of 2D soft x-ray detector technology available at the time.

In this contribution, we present our plans to reestablish soft x-ray ptychography at BESSY II, with particular emphasis on the requirements, challenges, and opportunities associated with next-generation 2D soft x-ray detectors.

Speaker: Sebastian Wintz (Helmholtz-Zentrum Berlin)

14:30 Soft X-ray Coherent Imaging of Magnetic Textures

Soft x-ray imaging is a key method in the field of magnetism, offering exceptional spatial and temporal resolution, quantitative contrast, and the ability to investigate devices under operando conditions. Image contrast arises from strong dichroism at or near the elemental resonances. Coherent imaging is particularly attractive as it promises enhanced resolution and sensitivity. In this technique, raw scattering data is recorded with a camera and numerically converted to a real space image. One of the major challenges in this field is to obtain accurate (noise-free) measurements of the intensity at each pixel, to cope with the enormous dynamic range of the signal, and to not damage the detector with the direct beam. I will discuss these challenges and the opportunities that arise from new detector technologies in this context.

Speaker: Felix Büttner (University of Augsburg)

14:50 → 15:20 Coffee Break

15:20 → 17:00 Sensor fabrication and technologies - II

Convener: Jiaguo Zhang (PSI - Paul Scherrer Institut)

15:20 Probing soft X-rays using Low Gain Avalanche Diodes

Low Gain Avalanche Diodes (LGADs) are state-of-the-art silicon sensors designed with an internal gain in the order of 10, enabling a timing resolution of about 30~ps. Over the past decade, the development of LGADs has been driven by the High-Energy Physics (HEP) community to facilitate the time tagging of minimum ionizing particles for the High-Luminosity upgrade of the Large Hadron Collider (HL-LHC). Although LGADs have been extensively studied in HEP due to their fast timing response, their applications in soft X-ray detection remain unexplored.

Detection of soft X-rays with energies in the range of 0.2-2~keV finds application in various topics such as: pharmaceuticals, material science (magnets, superconductors, quantum materials, etc.), and investigating biological samples since it covers K-edges of carbon and oxygen. Key requirements for detecting soft X-rays include high frame rates, a large dynamic range, and a high signal-to-noise ratio. Hybrid silicon pixel detectors can easily meet these requirements, particularly for X-rays with energies ranging from 2 to 10~keV. However, when probing X-rays in the energy range of 0.2-2~keV, hybrid silicon detectors face limitations due to their quantum efficiency and the noise associated with readout electronics.

LGADs with their internal gain mechanism, fast timing capability, high signal-to-noise ratio, and low noise make them an ideal candidate for soft X-ray detection, but with some caveats. This work presents how the LGADs can be designed to detect soft X-rays and an overview of inverse LGADs technology with an optimized entrance window to enhance the quantum efficiency. Different gain design strategies for inverse LGADs and their impact on the spectral response will also be discussed. Furthermore, ongoing and upcoming developments of inverse LGADs and their potential applications in soft X-ray detection will be presented.

Speaker: Ashish Bisht (Fondazione Bruno Kessler)

15:40 N-on-n iLGAD for soft X-ray detection

The Low Gain Avalanche Diode (LGAD) has emerged as a promising technology for applications in next-generation light sources. Its internal signal amplification (gain ~10) benefits small signals that can be raised above the noise imposed by the front-end electronics.

SINTEF, in collaboration with SLAC Linear Accelerator Laboratory, has developed and fabricated an inverse LGAD device tailored for soft X-ray detection. The device is fabricated on an n-type bulk, featuring a gain structure with a shallow entrance window on one side of the substrate and the readout electrodes on the opposite side. This configuration allows fine segmentation with 100% fill factor and enables shallowly generated electrons to undergo charge multiplication as they traverse the gain layer. Preliminary tests have demonstrated a gain of 7.

In this talk, we will present the development, design, fabrication, and characterisation of this new LGAD technology.

Speaker: Marius Mæhlum Halvorsen (SINTEF)

16:00 Monolithic Array of Reach THrough Avalanche photo diodes - qualification of the first prototype production

In order to achieve a pixel diode inherent signal amplification, Low Gain Avalanche Photo Diodes LGADs have come into focus of pixel detector developments. Our novel Concept for a Monolithic Array of Reach THrough Avalanche photo diodes, addresses one of the main issues of conventional LGADs, the inhomogeneity in the gap Region between pixels. The goal is to provides a 100\% fill factor and homogeneous gain over the complete sensor area. This is realized by an n-doped field drop layer between the n+ pixel structure and an unstructured p-doped multiplication layer. The field drop layer suppresses electric field peaks at the pixel edges and leads to a fairly homogeneous amplification over the sensor area. The functionality and first insights into the functionality of the MARTHA sensors have already been demonstrated. We are currently working on qualifying the homogeneity over the wafer area and further qualification of our prototype production.

Speaker: Alexander Bähr (Max Planck Semiconductor Laboratory)

16:20 Development of a Deep Junction LGAD for Soft X-rays

Recent developments in X-ray technology have highlighted a significant gap between the advancements in X-ray facility capabilities and the corresponding limitations in detector technologies, especially in the soft X-ray energy range (200 eV to 2 keV). While hybrid pixel detectors are the standard for higher-energy X-ray applications (2–20 keV), their implementation in the soft X-ray regime remains underexplored despite their high frame rates, dynamic range, and excellent signal-to-noise ratios. Low Gain Avalanche Diodes (LGADs), characterized by moderate internal gains in the range of 5–10, have emerged as a promising solution for addressing the signal-to-noise ratio limitations inherent in soft X-ray detection. However, several challenges remain in optimizing LGAD technology for this lower energy range. This work introduces an innovative sensor architecture, the Deep Junction LGAD (DJ-LGAD), which incorporates a specialized charge-absorbing region and a gain layer to enable efficient signal amplification. We present the detailed design of the device, along with the results of simulations and preliminary experimental data. Additionally, we discuss the various challenges encountered during the fabrication process and underscore the potential of DJ-LGADs as a promising solution for advancing next-generation soft X-ray detection technologies.

Speaker: Francesca Capocasa (Brookhaven National Laboratory)

16:40 N-type LGADs for Particle and Photon Detection

Low-Gain Avalanche Diodes (LGADs) are typically fabricated on p-type substrates, following an n–p⁺–p junction configuration, where a boron-doped layer forms the gain region.
This architecture is considered optimal for timing and particle-tracking applications since the primary charge carriers initiating the avalanche process are electrons, which feature higher drift velocity and ionization coefficient compared to holes. However, for the detection of low-penetrating particles, such as soft X-rays, the conventional p-on-n configuration becomes less efficient. In these cases, most carriers are generated close to the front junction (n-type region) or within the high-field gain layer, resulting in reduced gain and possibly lower signal-to-noise ratio (SNR).
To overcome these limitations and improve the detection efficiency of low-energy photons and particles, LGADs on n-type substrates (N-LGADs) have been recently proposed. This inverted doping configuration, compared to standard LGADs, is expected to deliver higher gain and SNR for low-penetrating radiation, particularly for X-rays below 1 keV.
The fabricated N-LGADs employ 55 µm-thick n-type epitaxial substrates, with the front junction formed by boron ion implantation. Several junction depths and doping profiles have been implemented to investigate QE and Gain vs interaction depth as a function of junction design. Electrical characterization (I-V, C-V, and gain measurements) will be presented for the different splits, along with optical characterization in the 380–950 nm wavelength range. The latter enables the determination of Gain and QE as a function of the charge generation depth, providing a comprehensive comparison among the various device configurations.

Speaker: Giovanni Paternoster (Fondazione Bruno Kessler)

Tuesday 13 January

09:00 → 10:00 Sensor and detector characterization - I

09:00 Development of 2nd generation of PERCVIAL Sensor and System for upgraded soft X-ray imaging

PERCIVAL, the Pixellated Energy-resolving CMOS Imager Versatile and Large, is a 2-megapixel multi-gain X-ray detector designed for photon science experiments at Free Electron Laser (FEL) and synchrotron facilities.
Cross-talk effects and non-uniformity of dark images limited the performance of the first generation of the sensor, limiting noise performance, frame rate, and dynamic gain performance as well as fully usable imaging area. 2nd version of the sensor ('respin') overcomes these issues, and together with upgraded DAQ hard-and firmware we are now approaching speed and full dynamic gain range of the original design.
In this contribution, we report on characterization of the Respin PERCIVAL chip and its new system. We demonstrate that the chip can be operated up to a frame rate of 285 Hz for the full-frame and 1 kHz for the Region of Interest (ROI) operation. We also show the first results of the testing Respin chip with synchrotron radiation at PETRA-DESY facility.

Speaker: Mohammadtaghi Hajheidari

09:20 Beyond CCDs: CMOS image sensors for soft X-ray Astronomy and Beyond

Historically, charge-coupled devices (CCDs) have been the detector of choice for soft X-ray astronomy, successfully deployed on numerous missions over several decades, including XMM-Newton, Swift XRT, Suzaku, Chandra, and the upcoming European Space Agency (ESA) SMILE mission. While highly successful over many years, CCDs are particularly susceptible to radiation damage and must be operated at cold temperatures, typically at or below -100 °C.
For the upcoming ESA M7 candidate soft X-ray astronomy mission, THESEUS, it was determined that the focal plane of the soft X-ray imager (SXI) could only be cooled to approximately -40 °C, rendering CCDs unsuitable and necessitating alternative detector technologies. A competing technology, CMOS image sensors (CIS) have already proven effective for optical instruments, as seen in ESA’s flagship JUICE JANUS instrument. However, as of 2019, CIS technology lacked the full depletion and efficient charge collection required for high-performance X-ray spectroscopy, prompting further development.
In response, ESA engaged the Centre for Electronic Imaging (CEI) and Teledyne e2v (Te2v) to develop the world’s first bespoke X-ray-optimised monolithic CIS. Between 2019 and 2024, the CIS221-X sensor was designed as a test structure, manufactured, and characterised. This 2 × 2 cm2 device has 40 m pixels and achieves noise <2.5 e-rms, with low dark current and image lag <0.1% providing an energy resolution (FWHM) of 126 eV at 5.9 keV at -40 °C operating in excess of 30 frames per second. Variants include an on-chip optical blocking filter (OBF). The soft X-ray quantum efficiency has been characterised at PTB over the 0.1-1.5 keV range for both with/without OBF variants. This test device meets all the Theseus SXI focal plane requirements except detector size. Testing has also been conducted at higher temperatures achieving 128 eV FWHM resolution for 1500 eV X-rays at 0 °C. This talk will present the world-leading performance of the current sensor and the development of the next-generation full-scale 3-sides buttable detector the CIS321 having 4.5 × 9 cm2 detection area and capable of operation at 20 fps. The Theseus SXI focal plane array will comprise 2x4 of these sensors totalling an area of 18x18 cm2 which will lead to one of the largest X-ray arrays ever flown.

Speaker: Thomas Buggey (The Open University)

09:40 BSI sCMOS Sensors for Soft X-ray Applications at SOLEIL: Experience and Performance

Soft X-ray detection at modern synchrotron and free-electron laser facilities presents key challenges, particularly in achieving high quantum efficiency (QE) at low photon energies, maintaining low noise and high dynamic range, supporting fast frame rates, and ensuring radiation hardness under intense photon flux. Conventional detectors such as back-illuminated CCDs or micro-channel plates (MCPs) often fall short in simultaneously addressing these requirements.
Recent advances in commercial back-side illuminated scientific CMOS (BSI sCMOS) detectors provide a viable and cost-effective alternative. In particular, GSENSE BSI sensors (e.g. GSENSE400BSI) combine high QE up to ~90% in the soft-Xray range, readout noise below 2e- rms, large full-well capacity of ~80 ke- and frame rates up to several tens of Hz - features that are critical for synchrotron applications [1, 2].
At SOLEIL, we have integrated and vacuum-adapted several GSENSE-based BSI sCMOS cameras with different sizes and geometries tailored to beamline requirements. These detectors have demonstrated excellent performance in demanding experiments, including Fourier Transform Holography (FTH), soft X-ray Ptychography, and Resonant Inelastic X-ray Scattering (RIXS). This presentation will provide an overview of the architectures and geometries of GSENSE-based BSI sCMOS detectors, their measured characteristics and achieved performance. In addition, we will share our practical experience and lessons learned from using these detectors over several years in diverse soft X-ray experiments. Perspectives on new cameras under development, as well as longer-term needs for soft X-ray detection will also be discussed.

[1] Desjardins et al., AIP Conf. Proc. 2054, 060066 (2019)
[2] Desjardins et al., J. Synchrotron Rad. 27, 1579 (2020)

Speaker: Arkadiusz Dawiec (SOLEIL Synchrotron)

10:00 → 10:30 Coffee Break

10:30 → 11:50 Applications - II

Convener: Simone Finizio (PSI - Paul Scherrer Institut)

10:30 Laser Induced XUV Spectroscopy for Oxidation Fingerprinting of Functional Materials

Direct solid microanalysis via laser microsampling offers key benefits: (i) flexibility across various matrices, (ii) minimal sample preparation, and (iii) high spatial resolution down to the diffraction limit, with ppm-level detection. Established techniques, such as Laser-Induced Breakdown Spectroscopy (LIBS) and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS), have proven effective but face challenges in fingerprinting of material stoichiometry. Our group has pioneered a innovative solution using extreme ultraviolet (XUV) detection for LIBS. Laser-Induced XUV Spectroscopy (LIXS) resolves the XUV emissions from laser plasma, improving detection of low-Z elements and matrix independence. Further, we recently shown how it can extract information on the oxidation of materials. The basic idea is that the oxidation select the unoccupied shells, while electronic recombination in the laser-produced plasma maps these unoccupied shells. Crucial is the role of the detector, especially to expand the bandwidth and sensitivity.

Speaker: Dr Davide Bleiner (OST University & University of Zurich)

10:50 Laser-driven resonant soft-X-ray scattering using the MOENCH detector for probing picosecond dynamics of nanometre-scale order

X-ray scattering has been an indispensable tool in advancing our understanding of matter, from the first evidence of the crystal lattice to recent discoveries of nuclei’s fastest dynamics. In addition to the lattice, ultrafast resonant elastic scattering of soft X-rays provides a sensitive probe of charge, spin, and orbital order with unparalleled nanometre spatial and femto- to picosecond temporal resolution. However, the full potential of this technique remains largely unexploited due to its high demand on the X-ray source. Only a selected number of instruments at large-scale facilities can deliver the required short-pulsed and wavelength-tunable radiation, rendering laboratory-scale experiments elusive so far. Here, we demonstrate time-resolved X-ray scattering with spectroscopic contrast at a laboratory-based instrument using the soft-X-ray radiation emitted from a laser-driven plasma source. Specifically, we investigate the photo-induced response of magnetic domains emerging in a ferrimagnetic FeGd heterostructure with 9 ps temporal resolution. Leveraging the latest hybrid-pixel MOENCH detector with its low-noise, high repetition rate, and single-photon-counting capabilities in the soft X-ray range, we can track the reorganisation of the domain network on pico- to nanosecond time scales in great detail. This instrumental development and experimental demonstration break new ground for studying material dynamics in a wide range of laterally ordered systems in a flexible laboratory environment.

Speaker: Daniel Schick (Max Born Institute)

11:10 Recent progress in scattering and imaging experiments at the DiProI CDI end-station of the FERMI seeded FEL.

F. Capotondi(1), F. Bencivenga(1), D. De Angelis(1), G. De Ninno(1),(2),b, D. Fainozzi(1), F. Guzzi(1), M. Ippoliti(1), G. Kourousias(1), M. Manfredda(1), I.P. Nikolov(1), M. Pancaldi(1), E. Pedersoli(1), P. Rebernik Ribič(1), A. Simoncig(1), C. Spezzani(1), Adriana Valerio(1), M. Zangrando(1)
Michael Schneider(3), Clemens Von Korff Schmising(3), Bastian Pfau(3)
Eric Malm(4)
(1) FERMI FEL, Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Trieste 34149, Italy.
(2) Laboratory of Quantum Optics, University of Nova Gorica, Nova Gorica, Slovenia.
(3) Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max-Born-Straße 2A, 12489 Berlin, Germany
(4) MAX IV Laboratory, Lund University, 22100 Lund, Sweden

• flavio.capotondi@elettra.eu

The advent of free-electron lasers (FELs) has revolutionized high-resolution imaging by enabling coherent diffraction imaging (CDI) techniques that leverage the intense, ultrafast, and coherent X-ray pulses generated by FEL sources [1-4]. This lensless approach facilitates the reconstruction of complex morphological, electronic, and chemical information at the nanoscale, making it particularly effective for studying dynamic processes such as phase transitions [5], nanoscale spin transport [6], and structural deformations in real time [7]. Recent advancements in multicolor FEL emission [8] have further expanded the capabilities of CDI by enabling simultaneous probing of morphology and spectroscopic properties [9]. In this presentation we will report about the recent progress in time resolved scattering and imaging experiments performed at DiProI end-station [10]. In particular, we will present results on: (a) the possibility of illuminating the samples from two different viewing angles to provide stereoscopic vision of the investigated object [3]; (b) the potential to achieve high-resolution ptychographic imaging at a free-electron laser (FEL) using orbital angular momentum (OAM) in diffraction-based imaging techniques [4]; and (c) the exploration of multicolor imaging, which offers insights across a broad spectrum of elemental edges. In the final part of the presentation, we will discuss the potential extension of these developed approaches from extreme ultraviolet (XUV) to soft X-ray applications, as well as the requirements for bidimensional detectors.

References:
[1] Chapman, H.N. et al., (2006). Nature Physics 2 (12), 839-843.
[2] Seibert, M.M. et al., (2011). Nature 470 (7332), 78-81.
[3] Fainozzi, D. et al., (2023). Optica 10 (8), 1053-1058.
[4] Pancaldi, M. et al., (2024. Optica 11 (3), 403-411.
[5] Johnson, A.S. et al., (2023. Nature Physics 19, 215–220.
[6] von Korff Schmising, C. et al., (2014). Physical review letters 112 (21), 217203
[7] Karl, R.M. et al., (2018). Science advances 4 (10), eaau4295.
[8] Allaria, E. et al., (2013). Nature Communications 4 (1), 1-7
[9] Willems, F. et al., (2017). Structural Dynamics, Vol. 4 - 1, 014301.
[10] Capotondi F., et al. Review of Scientific Instruments, 84 - 5, 051301 (2013).

Speaker: Dr Flavio Capotondi (Elettra Sincrotrone Trieste)

11:30 Towards time-resolved soft X-ray ptychography imaging

The investigation of magnetization dynamics at the nanoscale is one of the key aspects for the technological applications of magnetic systems. Synchrotron-based microscopy techniques, in particular scanning transmission X-ray microscopy (STXM), have been highly successful in the imaging of such processes by combining time-resolved imaging with dichroic contrast mechanisms such as the XMCD and XLD effects. However, the current limitation of STXM lies in the achievable spatial resolution, limited by the optics used to focus the X-ray beam to about 10-20 nm. Coherent diffractive imaging techniques such as X-ray ptychography imaging would allow us to overcome these limitations in the spatial resolution, but require a different approach in acquiring the time-resolved images, as the bandwidth of the currently-available 2D detectors lies well below the several hundred MHz bunch repetition rates of synchrotron lightsources.
In this presentation, we will show our current progress in the development of time-resolved soft X-ray ptychography and future outlooks upon the release of the next generation of 2D counting X-ray detectors.

Speaker: Simone Finizio (PSI - Paul Scherrer Institut)

11:50 → 13:25 Lunch

13:25 → 14:45 Detector Systems - I

Convener: Bernd Schmitt (PSI - Paul Scherrer Institut)

13:25 Recent progress in high resolution photon counting detectors with Microchannel Plates

Detectors with Microchannel Plates have found niche applications in soft X-ray UV photon detection, where event counting with high spatial and timing resolution is needed. Different types of readouts for these detectors have been developed over the last several decades. The Timepix readout ASIC placed directly below the MCP in the vacuum is one of the possible readout options. The capability of pixelated Timepix readout to detect many simultaneous events substantially increases the count rate capabilities of these devices to GHz levels. In this talk, we review the possible readout configurations for the MCP detectors, present the recent developments of this photon counting technology and present the results obtained with an MCP detector coupled to a quad Timepix/ Timepix3 and a single-chip Timepix4 readouts. The spatial resolution of this detector can routinely reach ~6 µm values (the size of the MCP pores). This resolution is achieved in real time through the event centroiding. Optimization of detector characteristics needs to be performed to achieve such a high spatial resolution. The timing resolution is ~2 ns with Timepix3 readout and is expected to be ~200 ps with the latest generation Timepix4 readout. A couple of application examples of these detectors at Resonance Inelastic X-ray Scattering (RIXS) and X-ray Photon Correlation Spectroscopy (XPCS) experiments demonstrate the unique capabilities of such devices for certain synchrotron-based techniques. These MCP/Timepix detectors could be very attractive for applications where the photon/electron/ion/neutron counting is required with high spatial and temporal resolution, such as Time of Flight experiments in energy-resolving neutron imaging at spallation neutron sources, fluorescence lifetime imaging and, if adapted for the electron detection, experiments in photoelectron spectroscopy.

Speaker: Anton Tremsin (University of California at Berkeley)

13:45 Single Photon Counting at 700 eV using LGADs

Hybrid pixel, single-photon counting detectors have been instrumental in advancing measurement techniques at synchrotron facilities. They enable fine slicing of the rotation angle and shutterless data acquisition for protein crystallography. Fast and efficient detectors are also essential for many modern techniques such as ptychography.
Although incredibly successful for hard X-rays, the large in-pixel capacitance resulting from the bump bonds represents an intrinsic barrier to low-energy detection, with most modern systems being limited to around 3–5 keV. LGAD sensor technology addresses this issue by amplifying the signal on the sensor side and is therefore not affected by capacitance in the same way.
In this talk, we will share our experience, from a detector developer's view, operating the first 512×512-pixel Eiger detector with an LGAD sensor for soft X-ray ptychography imaging. Scientific results from SLS and MAX-IV down to a photon energy of 500 eV are complemented with characterization data and an outlook toward next-generation systems which we will build around the new Matterhorn readout chip. It has the same pixel geometry, but is specifically designed for 4th generation synchrotrons supporting count rates up to several MHz/s/pixel and a frame rate of 10 kHz continuous. The chip will be available in 2026 and we plan to build the first single photon counting systems using improved LGAD sensors by 2027.
Hybrid pixel, single-photon counting detectors have been instrumental in advancing measurement techniques at synchrotron facilities. They enable fine slicing of the rotation angle and shutterless data acquisition for protein crystallography. Fast and efficient detectors are also essential for many modern techniques such as ptychography.
Although incredibly successful for hard X-rays, the large in-pixel capacitance resulting from the bump bonds represents an intrinsic barrier to low-energy detection, with most modern systems being limited to around 3–5 keV. LGAD sensor technology addresses this issue by amplifying the signal on the sensor side and is therefore not affected by capacitance in the same way.
In this talk, we will share our experience, from a detector developer's view, operating the first 512×512-pixel Eiger detector with an LGAD sensor for soft X-ray ptychography imaging. Scientific results from SLS and MAX-IV down to a photon energy of 500 eV are complemented with characterization data and an outlook toward next-generation systems which we will build around the new Matterhorn readout chip. It has the same pixel geometry, but is specifically designed for 4th generation synchrotrons supporting count rates up to several MHz/s/pixel and a frame rate of 10 kHz continuous. The chip will be available in 2026 and we plan to build the first single photon counting systems using improved LGAD sensors by 2027.

Speaker: Lars Erik Fröjd (PSI - Paul Scherrer Institut)

14:05 Developments towards Soft and Tender X-rays at Dectris

During the last two decades, Hybrid Photon-Counting (HPC) pixel detectors have significantly improved a large number of techniques performed at synchrotron light sources, and in many cases enabled new ones, due to their high frame-rate, dynamic range and stable operations. The impact of HPC detectors has however been limited mainly to the Tender and Hard X-ray range, while the Soft X-ray regime is not fully accessible yet. Dectris has been pushing the lower energy limit, mainly with the detectors of the PILATUS series, reaching thresholds as low as 1.6 keV [1].
This contribution will present the current efforts that are being made within Dectris in the pursuit of enabling the detection of lower energies, with photon-counting detectors. This goal is being addressed in different ways, including optimizing the current detector designs, exploring new sensor types with internal multiplication (LGADs), and developing a new high-energy resolution dedicated ASIC. Characterization results for various prototype systems obtained in-house, as well as during beamtime at synchrotrons, will be shown.
References:
[1] Wernecke, Jan, et al. "Characterization of an in-vacuum PILATUS 1M detector." Synchrotron Radiation 21.3 (2014): 529-536.

Speaker: Filippo Baruffaldi (Dectris AG)

14:25 FASXCAM - High Frame Rate MAPS Detector for Soft X-rays

FASXCAM is a monolithic active pixel sensor (MAPS) tailored for high-rate radiation imaging and advanced dosimetry. It was developed and prototypes manufactured using XFAB 180nm SOI technology. The device integrates two identical 32×64 pixel arrays with 60×60 µm² pixels, coupled to parallel 8-bit SAR ADCs for column-wise digitization and detection energy range 2.9 to 21.6 keV. The architecture enables data throughput up to 400 MHz and frame rates approaching 15k FPS, allowing low latency visualization of radiation interactions with minimal dead time. The sensor supports both frame and rolling shutter operation, ensuring flexibility in experimental timing, and incorporates both internal and optional external voltage reference to improve robustness against power fluctuations.
Beyond high-speed imaging, FASXCAM offers features crucial for precision metrology and system integration: on-chip temperature sensing, external charge injection for calibration, configurable analog test outputs, global hit detection circuitry signaling interaction via logic output signal and dual configuration scheme (global and pixel-wise). These functions establish FASXCAM as a versatile platform for radiation detection in research and applied settings. Potential applications include beam diagnostics, fast X-ray imaging, space radiation monitoring, and compact dosimetry systems requiring both spatial resolution and reliable energy measurement.

Speaker: Monika Kuncová (Czech Technical University in Prague)

14:45 → 15:15 Coffee Break

15:15 → 15:55 Tender X-rays

15:15 Multi-energy SXR detector to study fusion plasmas

A DECTRIS PILATUS3 100K detector is being used to sample the SXR emission from magnetically-confined fusion plasmas at different energies. The detector is equipped with a pixelated silicon sensor and it features single counting and CMOS readout ASICs. Lower energy thresholds at pixel level were calibrated via a custom procedure by exposing the detector to a series of fluorescence targets and scanning the detector characteristic responsivity (“S-curve”) across the 64 possible energy threshold values for each pixel; this novel capability is explored by fine-tuning the voltage of a 6-bit digital-analog converter after the charge-sensitive amplifier for each of the ~100k pixels. Thanks to this pixel-level calibration, the lower energy threshold of each pixel can be set independently in the range 2-20 keV, allowing the measurement of the x-ray emission with spatial, temporal and energy resolution simultaneously. Through meticulous selection of the lower energy thresholds it is possible to separate signal from line emission from the continuum, in order to simultaneously investigate multiple plasma properties. The energy-resolved measurements in a spectral region dominated by strong tungsten lines are used to infer impurity concentrations. The variation of emissivity with photon energy in a spectral region free from line radiation is utilized to infer plasma electron temperature, plasma centroid position, and radiated power density.

Speaker: Tullio Barbui (Princeton Plasma Physics Laboratory)

15:35 Photon-Counting Pixel Detector Designs for ITER X-Ray Crystal Spectroscopy System

Controlled nuclear fusion is considered the ultimate energy source for humanity. Magnetic-confinement tokamaks are representative facilities such as the International Thermonuclear Experimental Reactor (ITER), the Experimental Advanced Superconducting Tokamak (EAST), etc. ITER is expected to start operation around 2035 and become the first magnetic-confinement fusion reactor to achieve self-heating and Q=10. To effectively monitor the state of the plasma, ITER's diagnostic system requires efficient detection of various particles, including neutrons, gamma rays, and X-rays, to ensure the safe operation of the facility.

The X-Ray Crystal Spectroscopy (XRCS) system is a critical component of ITER's diagnostic system, responsible for monitoring plasma impurity levels and the condition of the first wall materials. The detector must achieve single-photon sensitivity for Xe and W spectral lines (about 3~9 keV), with a large panel. While hybrid photon-counting detectors are commercially available, they are typically optimized for the 6~20 keV energy range. Additionally, the front panels are often tightly integrated with backend electronics, making them unsuitable for operation in ITER's high neutron flux environment.

The Centre de Physique des Particules de Marseille (CPPM) and the Institute of High Energy Physics (IHEP) of the Chinese Academy of Sciences are collaborating to develop a photon-counting detector capable of single-photon resolution at 3 keV for ITER's XRCS system. In this talk we will present studies based on two different technology paths, focusing respectively on the front-end level and the system level.

A new MAPS design is based on a CIS process and aims to utilize stitching technology to achieve a large-area, low-dead-zone detector panel. The detector features a logical pixel size of 100 μm × 100 μm. Two front-end structures were achieved to address the size discrepancy between logical pixels and diodes: The CSA front-end structure with an analog-sum scheme has a good energy linearity and an ENC less than 40 e-; While the ALPIDE-like front-end structure with a digital-sum scheme achieves an ENC of less than 11 e-.

Meanwhile, tests on the system level based on the BPIX detector were carried out. To ensure the suitability for the ITER application environment, the performances of the detector are studied across several key areas: All components are vacuum compatible; The detector should have magnetic field resistance since the magnetic field is expected to be approximately 0.2 T at the mounting location. Furthermore, the detector will work in an environment with a fast neutron flux of about 10^4 n/s·cm². In this talk, we will show the test results of those items.

Speaker: Mujin Li (IHEP)

15:55 → 16:55 Sensor and detector characterization - II

Convener: Anna Bergamaschi (PSI - Paul Scherrer Institut)

15:55 Characterization of inverse LGAD Sensors in the Soft X-ray Energy Range

At the Paul Scherrer Institute (PSI), we are developing inverse Low-Gain Avalanche Diode (iLGAD) sensors with a thin entrance window (TEW) in collaboration with Fondazione Bruno Kessler (FBK). The TEW design is used to enhance the charge-collection efficiency near the sensor surface. In our latest batch, the quantum efficiency (QE) exceeds 85% at 250 eV, which is comparable to state-of-the-art detectors for soft X-rays. Furthermore, compared with conventional sensors, LGADs incorporate an internal gain layer that provides moderate amplification, thereby significantly improving the detector’s signal-to-noise ratio (SNR) by a factor of at least five in the soft X-ray energy range.
In this presentation, we will report recent beam-test results obtained at the MAX IV synchrotron using soft X-rays from 390 eV to 2500 eV. The iLGAD sensors were bump-bonded to the MÖNCH and JUNGFRAU charge-integrating readout chips, featuring pixel sizes of 25 μm and 75 μm, respectively. The results demonstrate that single-photon detection can be achieved at 400 eV with an SNR exceeding five. The dependence of the SNR on photon energy and temperature will also be presented.
We further studied the iLGAD spectral response, which exhibits a characteristic double-peak structure, corresponding to hole-initiated and electron-initiated multiplication peaks arising from photon absorption before and after the gain layer. To better understand this behavior, we applied an empirical model to fit the spectra, allowing us to extract the fractions of photons absorbed before and after the gain layer. These fractions are used to estimate the thicknesses of the n⁺ and gain layers, and the extracted values show good agreement with process-simulation results.
Finally, we will present the improvements and testing program for the next batch of iLGAD sensors, which are expected to become available in early 2026.

Speaker: Shuqi Li (PSI - Paul Scherrer Institut)

16:15 Performance of LGAD-based X-/Gamma-ray Detection Systems with SIRIO Ultra-Low Noise Charge Sensitive Preamplifier

We present the performance of two X/Gamma-ray detection systems based on Low-Gain Avalanche Diodes (LGADs) with a wide range of multiplication gains: the first LGAD is characterized by a very-low gain range (M_s=1.2-1.9), while the second one by a high-gain range (M_s=10.2-19.3). To allow the evaluation of the ultimate energy-resolution limits of the LGAD sensors, the read-out is performed with a state-of-the-art ultra-low noise Charge Sensitive Amplifier (CSA) realized in CMOS technology. Detectors' performances were evaluated using 241Am and 55Fe radiation sources, allowing for a consistent study of the spectral resolution over a wide range of photon energies, from E_ph=5.9 keV to E_ph=59.5 keV. The different noise components contributing to the overall spectral performances of the detection systems have been determined, disentangling the contribution of the equivalent noise charge (ENC) as measured on an artificial test pulse, from the excess widening of the spectral lines, associated with the multiplication gain statistics and a spatial gain inhomogeneity. The Excess Noise (EN) of the spectral lines is shown to increase linearly from E_ph=5.9 keV to E_ph=59.5 keV. EN has also been found to increase linearly with M_s with a slope proportional to √E_ph as expected from the theory of the statistical noise in avalanche structures. A empirical model for the excess noise of the spectral lines dependence on E_ph and M_s has been developed including both the noise due to multiplication gain statistics and the gain inhomogeneity.

Speakers: Filippo Mele (Politecnico di Milano), Gabriele Giacomini (Brookhaven National Laboratory), Giuseppe Bertuccio (Politecnico di Milano, Department of Electronics, Information and Bioengineering, Como, IT; National Institute of Nuclear Physics (INFN), Milan Section, Milan, IT), Iurii A. Eremeev (Politecnico di Milano, Department of Electronics, Information and Bioengineering, Como, IT), Wei Chen (Brookhaven National Laboratory, Instrumentation Division, Upton, NY)

16:35 RIXS Detector Using JUNGFRAU with Rectangular Pixels

The development of hybrid pixel detectors combining the JUNGFRAU charge-integrating ASIC with inverse Low-Gain Avalanche Diode (iLGAD) sensors continues to advance toward high-performance soft X-ray Resonant Inelastic X-ray Scattering (RIXS) experiments. The project aims to achieve both high frame rates (2 kHz continuous and up to 250 kHz in burst mode with the most recent ASIC version JUNGFRAU 1.2) and super-resolution on the micrometer scale in one dimension by employing rectangular pixels that enable charge-sharing-based position interpolation.

In this contribution, we present a comprehensive overview of the development status of an iLGAD-based JUNGFRAU detector for low-energy RIXS. We summarize results from laboratory characterizations that investigate the detector’s performance, including sensor leakage, noise, and spatial resolution. Various prototype configurations, featuring single- and multi-chip assemblies with several different rectangular pixel geometries, have been evaluated in pilot beamline experiments at the Swiss Light Source, SwissFEL, and European XFEL.

We will discuss key findings regarding operation stability, response uniformity, and achieved spatial resolution, and outline the next steps in the presentation. A major focus will be the forthcoming iLGAD sensor R&D batch, currently in fabrication and expected by mid-2026, which is designed to deliver significantly improved quantum efficiency, critical for RIXS experiments due to the required small X-ray incidence angle, and enhanced signal-to-noise ratio at low photon energies. These new iLGAD sensors are expected to further extend the detector’s sensitivity and applicability for demanding soft X-ray RIXS experiments.

Speaker: Viktoria Hinger (PSI - Paul Scherrer Institut)

18:00 → 21:30 Social Dinner

Wednesday 14 January

09:00 → 10:00 Applications - III

Convener: Simone Finizio (PSI - Paul Scherrer Institut)

09:00 Soft X-ray Detection for TR-RIXS at the Furka Endstation of SwissFEL

Time-resolved resonant inelastic x-ray scattering (TR-RIXS) provides unique insight into the dynamics of elementary excitations in quantum materials. At the L-edges of 3d transition metals, located in the soft x-ray regime, the intrinsically low cross-section places stringent demands on detector performance. High quantum efficiency is essential to maximize signal yield, while the energy resolution of the spectrometer relies on spatial dispersion, necessitating detectors with excellent spatial resolution and single-photon sensitivity. Moreover, the pulsed nature of the free-electron laser (FEL) radiation requires fast readout time. At the Furka endstation of SwissFEL, TR-RIXS experiments are carried out with a CMOS imager and an in-house developed Jungfrau LGAD sensor, while an in-vacuum Jungfrau detector is employed for time-resolved diffraction. In this contribution, I will present the challenges of soft x-ray detection at an FEL from a user perspective, focusing on achieving high time- and energy- resolution TR-RIXS capabilities.

Speaker: Eugenio Paris (PSI - Paul Scherrer Institut)

09:20 Detectors for resonant soft X-ray scattering: current capabilities and future directions

Resonant soft X-ray scattering (RSoXS) combines the chemical sensitivity of X-ray absorption spectroscopy and the nanometer-scale spatial resolution of small-angle scattering to elucidate the structure of various soft materials. The ability of RSoXS to map both the composition and molecular orientations in these materials without chemical labeling offers unique insights that are less readily accessible by other characterization techniques. These insights are promising in the development of next-generation materials for nanolithography, ion/electron transport, and drug delivery. Realizing the full potential of RSoXS requires high-performance detection.

The National Institute of Standards and Technology owns an RSoXS measurement station at the Spectroscopy Soft and Tender beamline suite at Brookhaven National Laboratory. This station currently uses a 16MP soft X-ray sensitized charge-coupled device (CCD) camera. The large sensor area along with low noise have allowed wide angular ranges to be captured in minimal frames, enabling the construction of real-space structure maps across a large range of length scales. Combining multiple images at the same beam conditions have further enhanced signal-to-noise sensitivity, unlocking the detection of weak molecular orientation anisotropy in dilute liquid solutions and amorphous polymers. These detection capabilities have expanded the scope of materials that can benefit from RSoXS characterization.

Continued advancements in RSoXS require upgraded detector technologies. As the type of samples interrogated by RSoXS become more diverse, it is increasingly important to minimize X-ray dose such that the samples experience minimal radiation damage. In the near term, increased dynamic range with high linearity along with reduced noise and high quantum efficiencies across the full soft X-ray energy range (100 eV to 2000 eV) can aid the quantification of sample structures at multiple length scales with reduced X-ray exposure. Ideally, if the upper end of the dynamic range were sufficiently robust to withstand direct beam and not require a beamstop, the opportunity to analyze total scattered intensity could be realized. As flyscanning developments enable higher-throughput energy scans, detector readout times must be decreased to reduce measurement time overhead. Electronic gating of the sensor can eliminate the need for a physical shutter to block photons during the readout time to further simplify the measurement workflow. In the longer term, quantitative analysis of RSoXS data can benefit from sensors with energy sensitivity that can discriminate fluorescence from scattered X-rays and polarization sensitivity that can deconstruct the radiation emitted by the sample.

Speaker: Priyanka Ketkar (National Institute of Standards and Technology)

09:40 Soft X-ray phase nano-microscopy of micrometre-thick magnets

The development and optimisation of magnetic materials in various applications, including clean energy generation and spintronics, depend on an understanding of their nanoscale magnetisation configurations. However, until recently, nanoscale magnetic imaging was limited to thin film or surface investigations, with thicker magnetic systems greater than a few hundred nanometres limited to rare-earth materials [1]. As a result, investigations of extended non-rare earth magnets were not possible.
Here, we overcome this limitation by using pre-edge phase magnetic imaging with soft X-ray ptychography, providing nanoscale imaging of extended magnetic systems of arbitrary composition. Using X-ray ptychography, we gain access to the prominent pre-absorption edge phase X-ray Magnetic Circular Dichroism (XMCD) signal, which we use to demonstrate imaging of the magnetic configuration of samples upto 1.7 μm in thickness, an order of magnitude larger than typically measured with conventional soft X-ray absorption based techniques.
The prospect of combining pre-edge phase XMCD with 3D magnetic vector imaging [2,3] is particularly exciting, as it enables the direct mapping of the magnetisation vector field of buried magnetisation textures in a variety of extended samples. These advances enable nanoscale imaging of a broad range of samples, including thick chiral helimagnets with novel topological states and naturally-occurring magnetite micro-magnets that until now, have not been possible to measure.

[1] Donnelly, C. et al., (2016) Phys. Rev. B, 94 (064421).
[2] Donnelly, C. et al., (2017) Nature, 547 (328-331).
[3] Di Pietro Martínez, M. et al., (2023) Phys. Rev. B, 107 (094425).
[4] Neethirajan, J. et al., (2024) Phys. Rev. X, 14 (031028).

Speaker: Jeffrey Neethirajan (MPI-CPFS)

10:00 → 10:30 Coffee Break

10:30 → 11:30 Detector Systems - II

Convener: Bernd Schmitt (PSI - Paul Scherrer Institut)

10:30 Development of a Front-End Stage for Future XFEL Detectors

New X-Ray pixel detectors are required to satisfy the challenging requirements from X-ray Free Electron Laser (XFEL) sources, such as high frame rates, wide dynamic range, and low noise for single-photon sensitivity.
The European XFEL is capable of emitting ultrashort X-ray flashes 27,000 times per second, delivering brilliance that is a billion times greater than conventional X-ray sources.
The new generation of detectors for the Eu-XFEL should feature both a high dynamic range, enabling discrimination of up to $10^4$ photons, and single-photon resolution at low energies such as 1keV.
A new front-end (FE) solution has been studied to satisfy XFEL requirements. The proposed FE includes a Charge Sensitive Amplifier (CSA) with active gain switching, a transconductor, and a trapezoidal filter.
Single-photon capability at low energies can be achieved by employing a filter, based on the Flip-Capacitor filter concept, to minimize the electronic noise.
Moreover, to fulfill the high input photon dynamic range requirement, an active gain switching (AGC) approach is adopted.
The CSA features three feedback capacitances to implement three different gain settings. Based on the input charge, the three gains correspond to different operating ranges. In the first range, the system can detect from 1 to 50 photons with single-photon resolution, in the second range detects up to 800 photons, and in the third range, it detects up to $10^4$ photons at 1keV.
The AGC circuit sets dynamically the proper gain to prevent output saturation, leading to noise minimization, and can be implemented in two ways.
In the standard approach, each time the CSA output exceeds a fixed threshold, typically set close to the power supply, a feedback capacitance is added in parallel.
A more interesting approach, particularly in the field of X-ray detection, is the "predictive" gain switching technique, which dynamically determines the proper gain based on the time instant “t” at which the input signal crosses a predefined threshold.
The time instant “t” depends on the input charge Qin; the higher Qin, the faster the CSA response, and the smaller the time instant “t”. If the signal exceeds the threshold at a time instant “t” greater than both “t1” and “t2”, which define two timing windows, the CSA operates in its standard configuration with the lowest feedback capacitance. If “t” is between “t1” and “t2”, the middle gain is selected. Finally, if “t” is lower than both “t1” and “t2”, the CSA switches to the lowest gain setting.
The predictive AGC circuit features several advantages: it involves only one gain transition among multiple gains, the threshold value can be independently set, and so does not need to be close to the power supply, and the gain decision is taken within a time much shorter than the integration time.
The adopted filter features a current as input, so to couple with the CSA, a voltage-to-current converter is required. The conversion must be as linear as possible, which is quite challenging due to the wide dynamic range of the CSA output signal. To prevent the filter output from being saturated, an equivalent resistance of 310 kΩ should be achieved.
Moreover, a DC programming loop is implemented between the filter and the transconductor to cancel the residual output current caused by offset and mismatch.
The implemented filter is based on the Flip-Capacitor Filter (FCF) idea and features a trapezoidal weighting function with a flat top duration of 50 ns. It performs a double integration using a single amplifier.
The filter is included only in the first operating range to be able to achieve the single photon resolution at 1keV.
An estimation of the equivalent noise charge (ENC) has been carried out through Cadence simulations considering the filter for the first operating range.
Multiple transient noise simulations were performed to estimate the rms output voltage at the filter output. The simulated rms voltage noise values are 1.85 mV, 2.1 mV, and 2.8mV for integration times of 50 ns, 100 ns, and 150 ns, respectively. Corresponding ENC values are 35 e−, 40 e−, and 52 e−, assuming a total detector input capacitance, Cin, of 300 fF.
The ENC values, for higher input charge (second and third range), have been estimated by reporting at the input the output rms voltage noise of the CSA signal, as the FCF is not used when the AGC is active, and are 155 e− for the second range and 1044 e− for the third range.
The proposed FE has been optimized for soft X-rays, achieving single-photon resolution at 1 keV, while maintaining a high input photon dynamic range (up to $10^4$ photons) by implementing the predictive gain switching technique. A first prototype has been designed in 65 nm CMOS technology. Preliminary measurements on the first prototype will be reported at the conference.

Speaker: Adele Ciavarella-Ciavarella (Politecnico di Milano)

10:50 Soft X-ray Imaging at up to 4.5 Mega-frames/s with the DSSC Camera: MiniSDD and Ultra-Low Noise DEPFET Sensors

The DSSC camera system was developed for soft X-ray photon science applications in the 0.25–6 keV energy range at the European XFEL in Germany. Two sensor implementations are available: a 1-megapixel camera with MiniSDD sensors, delivered in 2019, and a recently completed version equipped with DEPFET active pixels. The first DSSC camera, based on MiniSDD pixels, has been successfully used for scientific experiments at two instruments. It is composed of 1024×1024 silicon pixels, with 256 ASICs enabling full parallel readout, including analog filtering, digitization, and data storage. The system achieves a peak frame rate of 4.5 MHz. It delivers noise levels of ~60 electrons rms. at 4.5 MHz and 40 electrons at 2.25 MHz, though its linear response limits the dynamic range. To achieve both high dynamic range (~10⁴ photons/pixel/pulse) and single-photon sensitivity, the second version employs DEPFET active pixels, which provide a calibrated non-linear response at the sensor level and enable ultra-low noise soft X-ray imaging. The readout ASICs and camera-head electronics are compatible with both types of sensors. We will present the system architecture, key features, and beamline results from both versions. Several user experiments have been conducted with the MiniSDD camera, demonstrating its versatility under diverse experimental constraints. A highlight is the first single-shot acquisition of a diffraction pattern from a photoactive protein at 2.5 keV and 2.2 MHz. We will also present the first complete experimental characterization of the DEPFET camera, performed with a pulsed lab X-ray source and during two dedicated beamtimes at the European XFEL. Single 1.48 keV photons were resolved with S/N > 50 at 1.125 MHz. Average noise was ~7 e⁻ rms, with best sensors reaching ~4 e⁻, and a dynamic range one order of magnitude higher than the MiniSDD camera was achieved.

Speaker: Prof. Matteo Porro (Europen XFEL GmbH - Ca' Foscari, University of Venice)

11:10 Inverse LGAD sensors for RIXS spectroscopy at the European XFEL

The Spectroscopy and Coherent Scattering (SCS) instrument at the European XFEL is equipped with the Heisenberg-RIXS spectrometer (hRIXS), capable of performing resonant inelastic X-ray scattering (RIXS) measurements in the time domain, with time and energy resolution approaching the Heisenberg limit imposed by the uncertainty relations [1, 2]. The unique pulse delivery structure of the European XFEL allows for bursts of pulses within a bunch train to be delivered up to MHz rates, which is beyond the frame rate capability of most detectors. Combining this with the additional requirements of high spatial resolution and large sensitive area, finding a detector capable of fully exploiting the potential of the hRIXS spectrometer becomes a significant challenge. A detector sensitive to photon energies below 1 keV and simultaneously capable of resolving intra-train pulses would greatly benefit pump-probe laser experiments, by enabling the use of alternating pumped and unpumped pulses for more reliable data normalization.
In recent years, a collaboration between the Paul Scherrer Institute (PSI) and Fondazione Bruno Kessler (FBK) has materialized into the first prototypes of X-ray-sensitive inverse Low Gain Avalanche Diodes (iLGADs) sensors compatible with the readout chips of the widely adopted charge-integrating detectors developed by PSI, such as the JUNGFRAU [3, 4]. The JUNGFRAU 1.0 ASIC, which is already widely employed across several of the European XFEL experimental stations, is capable of storing up to 16 images in analogue memory cells, offering a maximum acquisition rate of ~150 kHz in between readout cycles. Four ASICs each of 256×256 pixel with75 μm pitch have been bump-bonded to to an iLGAD sensor segmented into narrow rectangular pixels of 25x225 μm2, thus increasing spatial resolution along the energy dispersion axis.
This detector prototype has been extensively characterized and calibrated and its performance will be summarized here. Moreover, the main results of a recent beamtime with the hRIXS spectrometer will be presented highlighting the spatial resolution achieved using reference solid samples, and comparing it to the previously used commercial cameras. Finally, we present the RIXS spectra acquired at multi-kHz rates in combination with pump-probe laser excitation.

[1] Van den Brink, Jeroen. "Resonant inelastic x-ray scattering on elementary excitations."
Rev. Mod. Phys 83 (2011): 705.
[2] Schlappa, Justine, et al. "The Heisenberg-RIXS instrument at the European XFEL." Synchrotron Radiation 32.1 (2025).
[3] Mozzanica, A., et al. "The JUNGFRAU detector for applications at synchrotron light sources and XFELs." Synchrotron Radiation News 31.6 (2018): 16-20.
[4] Hinger, Viktoria, et al. "Resolving soft X-ray photons with a high-rate hybrid pixel detector." Frontiers in Physics 12 (2024): 1352134

Speaker: Marco Ramilli (European XFEL GmbH)

11:30 → 11:45 Closing remarks

11:45 → 13:00 Lunch

13:00 → 18:30 Visit to PSI and DECTRIS

Thursday 15 January

09:00 → 09:45 HiZPAD - Soft opening: Registration + Coffee/Gipfeli

09:45 → 10:00 HiZPAD - Welcome

Conveners: Dominic Greiffenberg (PSI - Paul Scherrer Institut), Marie Ruat (ESRF), Matthew. C. Veale (UKRI Science & Technology Facilities Council, Rutherford Appleton Laboratory)

10:00 → 12:00 HiZPAD - CdZnTe: I

10:00 Keynote: CdZnTe for applications at light sources

Speaker: Garbiella Carini (Brookhaven National Lab (BNL))

11:00 CdZnTe development from a crystal grower perspective

Speaker: Michael Fiederle (University of Freiburg, FMF)

11:30 Progress in the Preparation and Characterization of High-Flux CZT detectors

We have recently realized advanced CZT linear array detectors featuring sub-keV energy resolution, fabricated using high-flux HF-CZT material. These devices, specifically optimized for energy-resolved X-ray imaging, achieve a spatial resolution of 500 μm and an energy resolution better than 0.7 keV FWHM at 60 keV, enabling highly accurate spectral discrimination.
In this study, we report comprehensive X-ray imaging performance results, focusing on how the detectors’ superior spectroscopic response enhances the identification of foreign contaminants. We examine in detail the impact of charge-sharing phenomena and of energy-selective acquisition strategies on improvements in contrast-to-noise ratio (CNR). Furthermore, we introduce and evaluate a novel energy-resolved imaging methodology, referred to as window-based energy selection, demonstrating its effectiveness in detecting both low-density and high-density contaminants.
This work is conducted within the framework of national Italian research initiatives aimed at developing next-generation X-ray scanning systems for contaminant detection in the food industry.

Speakers: Andrea Zappettini (IMEM-CNR), Leonardo Abbene (University of Palermo)

12:00 → 13:15 Lunch

13:15 → 15:00 HiZPAD - CdZnTe: II

13:15 Characterization of Redlen high-flux CdZnTe

The Keck-PAD was developed at Cornell as a burst rate imager capable of recording images from successive electron bunches (154 ns period) from the Advanced Photon Source (APS) [1]. Both Si and hole-collecting Schottky CdTe have been successfully bonded to this ASIC and used with this frame rate. The facility upgrades at the APS will lower the bunch period to 77 ns, which will require modifications to the Keck-PAD electronics as well as necessitating a high-energy sensor material which has a shorter charge collection time. For the target energy of 40 keV for this project, simulations have shown that electron collecting CdTe should allow > 90% charge collection within 35 ns. We have obtained 750μm thick electron-collecting Schottky CdTe from Acrorad and bonded it to two different charge-integrating ASICs developed at Cornell (CU-APS-PAD “MM-PAD-2.1” [2] and the Keck-PAD). Carrier mobility has been investigated using the detector response to single x-ray bunches at the Cornell High Energy Synchrotron Source and to a pulsed optical laser. The material has also been characterized for other detector properties such as polarization, resolution and uniformity. The tests indicate that the collection time will meet the requirements for 77ns imaging.

[1] J. Becker, M.W. Tate, K.S. Shanks, H.T. Philipp, J.T. Weiss, P. Purohit, D. Chamberlain and S.M. Gruner, Sub-microsecond x-ray imaging using hole-collecting Schottky type CdTe with charge-integrating pixel array detectors, JINST 12 (2017) P06022.

[2] D. Gadkari, K.S. Shanks, H. Hu, H.T. Philipp, M.W. Tate, J. Thom-Levy, and S.M. Gruner, Characterization of 128x128 MM-PAD-2.1 ASIC: A Fast Framing Hard X-Ray Detector with High Dynamic Range, JINST 17 (2022) P03003.

Speaker: Lena Ann Franklin (Cornell University)

13:45 Collaborative charactierzation of Redlen CdZnTe

In a collaborative effort, various European research facilities led by STFC (DESY, EuXFEL, ESRF and PSI) have acquired different types of Redlen CdZnTe sensors (pixelated and planar electrodes) to characterize them in a collaborative fashion using the particular strengths of each facility. This presentation will give an overview of the research results from each facility, ranging from ToF measurements to afterglow behavior.

Speakers: Debora Magalhaes (DESY), Jonathan Mulvey (Paul Scherrer Institut), Matthew. C. Veale (UKRI Science & Technology Facilities Council, Rutherford Appleton Laboratory), Dr Steffen Palutke (Deutsches Elektronen-Synchrotron (DESY))

15:00 → 15:45 Coffee Break

15:45 → 17:45 HiZPAD - Applications

15:45 Keynote: High-Z requirements and developments with Timepix4

Timepix4 is a versatile readout chip developed by the Medipix4 collaboration led by CERN. It can operate both in a photon-counting mode, and in an event-driven mode which provides timestamping and energy information from each hit. We present on potential applications combining Timepix4's distinctive capabilities with high-Z sensors, the resulting sensor requirements, and characterisation results.

Speaker: David Pennicard (DESY)

16:45 In-laboratory protocol for the quantitative assessment of the time-dependent response of detectors equipped with high-Z sensors under high-energy X-ray irradiation

SPring-8 is a large-scale 3rd-generation synchrotron facility, exploiting several high-energy beamlines up to 115 keV. Direct photon-counting detectors, equipped with Cadmium Telluride sensors, are widely used in this context. However, some limitations have been identified during beamline tests, such as a non-uniform time-dependent response during irradiation and a persistent signal after irradiation, which make the use of CdTe sensors challenging for certain applications. To systematically and quantitatively study the time-dependent response of detectors equipped with high-Z sensors, a specific protocol has been developed in our laboratory, using photons with energies up to 49 keV. This protocol will be presented at the workshop, along with a concrete example of results obtained from the study of the persistent signal observed in CdTe sensors after irradiation, as well as the associated decay time.

Speaker: Fabienne Orsini (RIKEN Spring-8)

17:15 Development of Multi-Energy Hard X-ray Cameras for Thermal and Non-Thermal Plasmas

Soft and hard x-ray diagnostics are foundational tools in high-temperature plasma and fusion research, enabling measurements of magnetohydrodynamic (MHD) stability, energy confinement, impurity transport, runaway electron dynamics, radiated power, plasma–wall interactions, and disruptions. To significantly expand diagnostic capability, a novel multi-energy hard x-ray camera has been developed and calibrated by DECTRIS and PPPL, and deployed at WEST (CEA, France). This system features independently adjustable energy thresholds for each “smart” pixel, enabling unprecedented mapping flexibility on a 2D sensor. The high quantum efficiency of highZ detectors extends x-ray studies of radiative plasmas up to photon energies of 10–50 keV for GaAs and 10–100
keV for CdTe. The use of versatile CdTe multi-energy systems provides a major improvement in throughput and signal-to-noise ratio, enabling adequate spatial and temporal resolution (Δr/a≈1–5% and Δt≈0.5–50 ms, depending on signal to noise ratio [SNR]). For future burning plasmas with electron temperatures of 10–30 keV, a multi-energy CdTe sensor can sample the energy dependence of the thermal continuum to measure (a) the electron temperature (Te) and (b) the plasma effective charge (Zeff). At higher photon energies (30–100 keV), several non-Maxwellian features can be resolved, including (c) interactions of fast electrons with tungsten plasma-facing components (PFCs), (d) inference of RF-driven currents, (e) anisotropic emission from fast RFdriven electrons, and (f) the time evolution of runaway electrons (RE). Finally, integration with real-time control paves the way for non-magnetic equilibrium reconstructions and fast-acting RE alarms, pointing to a broader diagnostic paradigm for future fusion devices.

Speaker: Luis F. Delgado-Aparicio (Princeton Plasma Physics Laboratory (PPPL))

18:30 → 22:00 Social Dinner

Friday 16 January

09:00 → 11:00 HiZPAD - Perovskites

09:00 Keynote: Perovskites for X-ray detection

Speaker: Dr Sergii Yakunin (ETH Zurich)

10:00 Inorganic perovskites (CsPbBr₃) as high-Z sensor materials for hybrid detectors

I would also like to take this opportunity to propose a contribution for the workshop, based on a project we have been developing at the Brazilian Synchrotron Light Laboratory. Our work focuses on inorganic perovskites (CsPbBr₃) as high-Z sensor materials for hybrid detectors. We recently published our first results [1], covering material synthesis, characterization, and detection simulations. We have also had an approved contribution to the Allpix-Squared simulation framework by adding CsPbBr₃ as an active material [2].
For the workshop, we would like to present our hybridization attempts and share our ongoing efforts to experimentally probe the detection behavior of these sensors.
References:
[1] Campanelli, R. B., et al. "Evaluation and synthesis of perovskite crystals as high-Z sensors for hybrid pixel detectors." Scientific Reports 14.1 (2024): 27430.
[2] https://gitlab.cern.ch/allpix-squared/allpix-squared/-/commit/42af0d779df43e8cec62f7ab6434d6be0fdae147

Speaker: Raul Back Campanelli (Brazilian Synchrotron Light Laboratory - LNLS)

10:30 Single-Step Synthesis of Cs3Bi2I9 Nanocrystals for Scalable Direct X-Ray Detectors

Lead-free perovskite-inspired materials have emerged as promising candidates for direct X-ray detection. Herein, we report a scalable, single-step synthesis of Cs3Bi2I9 nanocrystals (NCs) with a high effective atomic number (Z value) directly from their precursor powders through an ultrasonication approach. By precisely controlling the precursor ratio and ligands, we achieve uniform and highly crystalline hexagonal NCs, as confirmed from high-angle annular darkfield scanning transmission electron microscopy (HAADF-STEM). The large-scale synthesis of the NCs allowed for the production of 0.78 cm² pellets used in the fabrication of X-ray detection devices, which exhibit a high bulk resistivity of 1 × 10¹¹ Ω cm and a low dark current density of 3.3 nA cm⁻² under an applied bias of 50 V (357 Vcm⁻¹ electric field). These polycrystalline devices achieve a limit detection of 108 nGyair s-1, an order of magnitude improved over the commercial standard for medical imaging, along with stable current during 25 min of continuous X-ray exposure when tested with an X-ray source with a peak energy of 35 keVp. Finally, we demonstrate the scale-up of these detectors by producing thick films 9 cm2 in area, achieving comparable performance to the detectors based on pellets.

Speaker: Joydip Ghosh (Inorganic Chemistry Laboratory, University of Oxford, Oxford OX1 3QR, U. K.)

11:00 → 12:00 HiZPAD - Postersession

12:00 → 13:00 Lunch

13:00 → 14:30 HiZPAD - Other High-Z sensor materials: I

13:00 Edge-On CZT and Amorphous Selenium Detectors for High-Resolution gamma-ray and X-ray Imaging

This talk will present recent advances in high-Z and wide-bandgap photoconductor detectors developed at the Radiological Instrumentation Laboratory, UC Santa Cruz. I will discuss: Edge-on cadmium zinc telluride (CZT) detector architectures enabling depth-of-interaction sensing, high energy resolution, and scalability for photon-counting CT, SPECT, and Compton imaging. Thick amorphous selenium (a-Se) and Se-Te-Ge alloy photoconductors designed for avalanche gain, low lag, and improved charge transport, offering new opportunities for high-resolution soft and hard X-ray detection.

Speaker: Shiva Abbaszadeh (University of California, Santa Cruz)

13:30 Integration of TlBr film sensor to TimePix-3 for Direct X-ray Imaging

Synchrotron science push to higher photon energy requires detector coupled to high-Z sensor overcoming the limitations of the traditionally used silicon detector.  Integrating these detector materials with the imaging readout circuit poses a challenge for the integration particularly for small pixel sizes and large pixel count arrays. Consequently, alternate sensor materials and methodologies to couple semiconductors to read out chips may prove attractive. This work reports on the development of single- and poly-crystalline thallium bromide (TlBr) layers coupled to the Timepix-3 pixelated readout chip. TlBr thanks to its high intrinsic resistivity and high density represents an intriguing and novel sensor solution for Hard X-ray hybrid detector systems.

Speaker: Giovanni Pinaroli (Brookhaven National Laboratory (BNL))

14:00 Latest update on TlBr activities

Latest update on TlBr activities from Spring8

Speaker: Hidenori Toyokawa (Japan Synchrotron Radiation Research Institute)

14:30 → 15:00 Coffee Break

15:00 → 16:30 HiZPAD - Other High-Z sensor materials: II

15:00 Germanium Sensors: Progress and Present Status

High-purity germanium (HPGe) remains the gold-standard sensor material for hard X-ray detection, offering superior energy resolution and detection efficiency. However, its widespread use is limited by the need for cryogenic cooling to suppress dark current. The NSLS-II Detector Group at Brookhaven National Laboratory has developed a series of monolithic, multi-element germanium detectors based on sensor arrays where pixel isolation is achieved through trenching, a process developed at Forschungszentrum Jülich, and read out using custom application-specific integrated circuits (ASICs) designed at BNL. The devices include both strip and pixel array detectors, with element counts ranging from 64 to 382, deployed for various synchrotron diffraction experiments under both monochromatic and energy-dispersive conditions. Compact, high-performance readout systems have been realized using modern FPGA system-on-chip technology, integrating multi-core processors with large gate arrays for real-time data handling. This work will discuss the technical implementation of these systems and present some recent results. Recent developments in novel germanium sensor geometries, including drift detectors and hybrid imaging platform, will also be discussed.

Speaker: Abdul Rumaiz (Brookhaven National Laboratory)

15:30 On the performance of a Silicon ROIC with PbS QD’s deposition for direct conversion x-ray detection

Speakers: Chun-Min Zhang (CSEM), Nadim Maamari (CSEM)

16:00 Evaluation of Different Thicknesses of Chromium Compensated Gallium Arsenide Sensors Using Photon Counting Readout Electronics

Gallium arsenide is extensively studied for about seven decades as an excellent material for semiconductor lasers, LEDs, and microwave electronics. GaAs has noticeable advantages over silicon and Cd(Zn)Te for radiation detectors. Particularly GaAs has higher electron mobility compared to Si and Cd(Zn)Te; higher average atomic number compared to Si; and lower probability and energy of the fluorescence photons compared to the Cd(Zn)Te [1].These advantages result in a fast charge
collection and a better uniformity compared to Cd(Zn)Te. High absorption efficiency up to 80 keV is required in medical computed tomography and security applications that can be achieved with 2 mm thick GaAs sensors. Other applications for the GaAs are foreseen in mammography, small animal imaging, electron microscopy, synchrotrons, XFELs and non-destructive testing of composite materials.
Advafab has developed chromium compensation of commercially available 3” n-type GaAs wafers to produce high resistivity and high flux tolerant GaAs sensors supported by [2]. In the process wafers are annealed in quartz reactor; processed by lapping and polishing; and lithographically patterned, metallized, and diced. Earlier we have demonstrated a wafer-level processing of 500 um thick GaAs sensors using designs compatible with different type of readout ASICs. Recently we have been able to
fabricate thicker, up to 2 mm thick, GaAs sensors to match the absorption efficiency of 750 um thick Cd(Zn)Te sensors. High resistive GaAs sensor wafers with thicknesses of 1-, 1.5- and 2-mm were fabricated. High photon-flux operation was evaluated using a medical CT X-ray tube in an open-beam configuration. It will be shown that 2 mm thick GaAs sensors with a 330 μm pitch tolerate and operate stably in extreme X-ray fluxes of up to 1.100 Mcnt/s/mm2.

[1] A.Owens, A.Peacock, Compound semiconductor radiation detectors, Nucl. Instr. and Methods A
531 (2004) 18–37
[2] This project has received co-funding from Business Finland under grant agreement 5700/31/2024.

Speakers: B. Wang (School of Biomedical Engineering, Shanghai, Tech University, Shanghai, China), D. Nalyvaiko (Advafab), E. Soharova (ADVACAM s.r.o.), H. Li (School of Biomedical Engineering, Shanghai, Tech University, Shanghai, China), Jan Jakubek (ADVACAM s.r.o.), Juha Kalliopuska (Advafab), N. Masuda (Advafab), P. Spisek (ADVACAM s.r.o.), Sami Vähänen (Advafab), T. Zhong (School of Biomedical Engineering, Shanghai, Tech University, Shanghai, China), V. A. Gnatyuk (Advafab), X. Lai (School of Biomedical Engineering, Shanghai, Tech University, Shanghai, China)

16:30 → 16:50 HiZPAD - Closing remarks

Conveners: Dominic Greiffenberg (PSI - Paul Scherrer Institut), Marie Ruat (ESRF), Matthew. C. Veale (UKRI Science & Technology Facilities Council, Rutherford Appleton Laboratory)