In the course of one third of centure (since 1984) the IBR-2 reactor has been and still is one of the most intense high-flux source of thermal neutrons in the world for the investigations on extracted beams, providing for the peak density of the neutron flux on the surface of moderators 6x10^15 n/cm^2/s and for the time average neutron flux up to 10^13 n/сm^2/s. However, service life of the...
The ultracold neutron (UCN) source at the Paul Scherrer Institute (PSI) has been in regular operation for the last years for up to 8 months each year. It is serving UCN to three beam ports with a priority on maximizing the UCN intensity for the neutron electric dipole moment experiment (nEDM) at PSI which was data taking with world-record sensitivity.
The UCN output has been significantly...
Accelerator driven neutron sources with high brilliance neutron provision present an alternative to classical neutron sources of fission reactors and spallation sources to provide scientist with neutrons to probe structure and dynamics of matter.
The Jülich Centre for Neutron Science has started a project to develop, design and demonstrate compact accelerator driven high-brilliance neutron...
Facilities providing bright thermal neutron beams are of primary importance for various research topics such as condensed matter experiments, neutron-imaging or medical applications. Currently these are mainly spallation sources and nuclear reactors. However, these later facilities are aging and the political context does not favor the building of new ones. This is the case in CEA-Saclay...
The concept of a next-generation spallation-driven ultracold neutron (UCN) source capable of delivering an integrated flux of about 1E9/s is presented. A novel "inverse geometry" design is used with 40 liters of superfluid 4He (He-II) as converter cooled with state-of-the-art sub-cooled cryogenic technology to ∼1.6 K. Our design is optimized for a 100 W maximum thermal heat load constraint on...
After modernization in 2011, the IBR-2 pulsed reactor at the Joint Institute for Nuclear Research has been successfully used by researchers from dozens of countries to carry out experiments on extracted neutron beams in solid-state physics. However, the capability of reactor operation is limited by the life-time from 2032 to 2035.Iin order to maintenance this area of research, it is necessary...
In 2020 the ISIS Target Reflector and Moderator assembly (TRAM) at target station 1 (TS1) will be replaced with a new design incorporating lessons learnt from the design of the ISIS 2nd target station with a particular focus on maintainability. The new TRAM will be made up of a 10 plate Tantalum clad Tungsten target, 2 water moderators in the upper part,2 cryogenic moderators (liquid Methane...
The introduction of the concept of supermirror in 1967 [1] and its technological realization [2] laid the foundation for increasing the efficiency of the transport of neutrons and of polarization analysis techniques due to the large increase of the maximal angle reflection by a factor of m when compared with the angle of total reflection of Ni. A complete guide system based on supermirror...
A mirror system for neutron transport with high brilliance transfer from a source or a divergent beam to an instrument is presented. The assembly of nested short elliptical (or very short flat) mirrors located halfway between two common focal points M and M' images cold neutrons by single reflections from an area around M onto an area of similar size at M'. An absorber on the straight line MM'...
In the recent past and at the present time, new ideas and concepts have emerged for new types of neutron sources and moderators. A short list of such ideas includes small scale accelerators [1], dimensionally reduced hydrogen moderators with much increased brightness [2,3,4], and liquid ammonia as a new moderator material [5]. In this contribution we look at the scientific requirements for...
Recent technical improvements in the accelerator and target technology coupled with the concept of compact moderator open the possibility to conceive efficient neutron source for imaging and neutron scattering base on low energy accelerators. This is the concept of the Compact Accelerator driven Neutron Sources (CANS). Low power tests and McStas simulations show that instruments installed on...
In Lund, Sweden, the European Spallation Source (ESS) is currently under construction. In order to cope with the expected high neutron fluxes at ESS and reduce the dependence on Helium-3 gas, which future availability is uncertain, alternative neutron detector technologies are being developed. Here we present an overview of a new generation of neutron detectors for neutron scattering based...
The multi-purpose Physics Neutron Diffractometer will be built at the China Spallation Neutron Source in the coming year. It is a time of flight diffractometer dedicated to the study of complex crystalline materials and the disordered materials by pair distribution function (PDF) technique. The MP diffractometer will be able to determine the PDF of the materials from atomic to nanometer scale....
The target development for compact accelerator driven neutron sources (CANS) for low energy and high current ion beams started to gain more attention with the upcoming high-brilliance neutron source (HBS) project and the SONATE project. It is in a similar state where the development for fission and spallation targets has been decades ago, namely fast changing and still with a large...
This work is dedicated to neutron imaging of two-phase liquid metal systems with relevance to theoretical and applied magnetohydrodynamics, as well as computational fluid dynamics. Specifically, argon bubble flow in liquid gallium in with and without the presence of external magnetic field is studied using high frame rate neutron beam transmission signal recordings obtained at the NEUTRA...
Moderator performance is impacted by the choice of moderator materials, the moderator size and temperature, position with regard to the neutron production zone, the moderator environment including pre-moderator and reflector material choices and sizing. The neutron production zone is defined by the proton beam characteristics such as beam energy, beam footprint and profile, beam power and...
Fully deuterated clathrate hydrates are a promising class of materials for diffuse neutron reflection and for moderation to much lower energies than current cold neutron sources. These inclusion compounds are available with a variety of weakly neutron absorbing guest molecules. Due to their large unit cells they offer better diffusion properties than common reflector materials within a much...
Abstract
Cold neutrons with wavelengths over 4 Å emitted by high-current neutron sources have been employed in physical research since the 1980s. The cold-neutron flux is enhanced by using neutron moderators cooled to low temperatures. In these, neutrons are retarded when passing through different substances such as water, heavy water, ice, paraffin, beryllium, liquid hydrogen, liquid and...
Nanodiamond Particles (NDP) are new candidates for neutron reflection. They have a large scattering and low absorption cross-section for low-energy neutrons. Very Cold Neutrons (VCN) are reflected in NDP with large scattering angles while Cold Neutrons (CN) have a quasi-specular reflection at small incident angles. A new scattering process has been added in Geant4 in order to examine the...
The ongoing refurbishment/optimization of the ISIS Target Station 1 (TS-1) target, reflector and moderators (TRaM) assembly is based on ISIS instrument scientists performance metric. The request coming from this metric is very simple: the degradation of TS-1 instruments time resolutions is completely unacceptable. This is understandable if we keep in mind that the short pulse (less than...
Neutron scattering techniques and neutron applications in general are powerful and well established tools for research in science and technology. However the tremendous potential of neutrons as a probe of matter or as a research object by itself is limited by the relatively low flux intensity of the neutron sources, as compared with photon sources. In addition, the different processes...
