PSI @ IBIC'25: three updates on beam instrumentation and feedback activities at PSI

Monday 3 Nov 2025, 16:00 → 17:00 Europe/Zurich

We will repeat our presentations given at the International Beam Instrumentation Conference (IBIC 2025) to keep our internal colleagues up to date as well. See below for the individual titles and abstracts.

1. Talk: Minimally Invasive Nano-Fabricated Wire Scanner for FEL Operations

Francesca Addesa

At the Paul Scherrer Institute (PSI), a minimally invasive wire scanner with sub-micrometer spatial resolution has been developed with a twofold objective: enabling real-time monitoring of the SwissFEL (Free Electron Laser) electron beam transverse size during lasing operation while also paving the way for a new generation of customizable wire scanners. These scanners are designed to be suitable for low and ultra-low emittance beams highly demanded by FEL developments and advanced acceleration concepts. Building on previous experience, nanotechnology has been further explored, utilizing photolithography to fabricate low-stress silicon nitride (Si₃N₄) wires suspended on a C-shaped silicon fork. Each fork hosts two perpendicular wires, allowing for the reconstruction of the beam profile in both the x and y directions. The wires are 2,4 and 6 µm wide and only 200 nm thick, and their length is tailored to match the SwissFEL beam clearance. Several prototypes have been successfully produced and installed at SwissFEL. This work presents the wire scanner's design and fabrication process, along with initial beam measurements at SwissFEL under lasing operations at 10 pC. 

2. Talk: Commissioning and First Operation of SLS 2.0, the Upgrade of the Swiss Light Source

Boris Keil

After more than 20 years of successful operation, the storage ring of the Swiss Light Source (SLS) has recently been replaced with a new diffraction-limited storage ring (DLSR) called SLS 2.0. After a dark time of 15 months from October 2023 until December 2024, SLS 2.0 now provides more than 40 times higher brilliance for hard X-ray users, thanks to an innovative compact 7-bend achromat magnet lattice with reverse bending magnets that fits into the old SLS 1.0 tunnel. In this contribution, we give an overview of the commissioning of the new storage ring and first user operation experience, highlighting key differences between SLS 1.0 and 2.0, as well as the role and usage of different beam instrumentation systems during the commissioning process from the operations perspective. Moreover, we present the status of beam-based feedbacks systems, and the resulting beam stability and performance that has been achieve so far during first user operation.

3. Talk: Characterization of sub-femto-second pulse duration of low-charge electron bunches using a Bunch-Compressor-Monitor at SwissFEL

Gian Luca Orlandi

The absolute characterization of the electron pulse duration- bunch length - in the ultra-short and low- charge (3-10 pC) operation mode of SwissFEL is relevant to a deeper understanding of the spectral structure and broad-band distribution of the resultant Free-Electron-Laser (FEL) pulse. Under this operation mode of SwissFEL, the output signals of the Bunch-Compressor-Monitor (BCM) in operation after the final magnetic chicane (ECOL) of the hard x-ray undulator line of SwissFEL (Aramis) can be suitably processed to obtain an absolute characterization of the electron bunch-length [1]. This is possible in the ECOL-BCM thanks to the simultaneous detection of the Edge-Synchrotron radiation pulse in two different and partially overlapping spectral bands by means of a pyro-detector and an optical fiber spectrometer. Experimental results on the absolute characterization of the electron bunch-length at the ultra-short and low-charge operation mode of SwissFEL will be presented together with details on the formal method applied for processing the two output signals of the ECOL-BCM.