Development of high intensity neutron source at the European Spallation Source

Abstract

The European Spallation Source being constructed in Lund, Sweden will provide the user community with a neutron source of unprecedented brightness. By 2025, a suite of 15 instruments will be served by a high-brightness moderator system placed above the spallation target. The ESS infrastructure, consisting of the proton linac, the target station, and the instrument halls, allows for implementation of a second source below the spallation target. We propose to develop a second neutron source with a high-intensity moderator able to (1) deliver a larger total cold neutron flux, (2) provide high intensities at longer wavelengths in the spectral regions of Cold (4–10 Å), Very Cold (10–40 Å), and Ultra Cold (several 100 Å) neutrons, as opposed to Thermal and Cold neutrons delivered by the top moderator. Offering both unprecedented brilliance, flux, and spectral range in a single facility, this upgrade will make ESS the most versatile neutron source in the world and will further strengthen the leadership of Europe in neutron science. The new source will boost several areas of condensed matter research such as imaging and spin-echo, and will provide outstanding opportunities in fundamental physics investigations of the laws of nature at a precision unattainable anywhere else. At the heart of the proposed system is a volumetric liquid deuterium moderator. Based on proven technology, its performance will be optimized in a detailed engineering study. This moderator will be complemented by secondary sources to provide intense beams of Very- and Ultra-Cold Neutrons.

Small-angle scattering for beginners

“…Comparable progress has taken place in the field of neutron facilities, which developed at a fast pace all through the second half of the 20th century, based on both nuclear reactors and spallation sources (Rush, 2015). A major event in the field is the current development of the European Spallation Source, anticipated to become the most brilliant neutron source worldwide (Santoro et al, 2020;Andersen et al, 2020). The increasing number of facilities and brilliance of the sources has been accompanied by qualitative improvements in the instrumentation, with better optics, detectors, instrument control, data analysis tools etc.…”

Status of the Design of an Annihilation Detector to Observe Neutron-Antineutron Conversions at the European Spallation Source

“…NNBAR would exploit the so-called Large Beam Port (LBP), which corresponds to three normal-sized beam ports. It would also benefit from a cold liquid deuterium moderator [21] and high reflectivity neutron optics. The propagation length of neutrons at NNBAR would be around 200 m. The HIBEAM annihilation detector would be of a smaller scale than the NNBAR detector, exploiting the cold neutron beam available at a beamline of the ANNI design [13].…”

Computing and Detector Simulation Framework for the HIBEAM/NNBAR Experimental Program at the ESS

“…2. Several moderator designs and configurations are currently being tested in order to provide the highest possible flux; this is a key output of the Horizon2020 HighNESS program [3]. The source yields from MCNP6 are then fed into the neutron raytracing code McStas [11], thus allowing one to simulate and optimize the performance of various reflector geometries.…”

“…Rucio facilitates data storage, management, and processing in a heterogeneous distributed environment. This will be particularly important for the second stage NNBAR experiment, as the scientific data of the experiment is to be shared between the participating institutes 3 . Moreover, there is plenty of experience within the NNBAR collaboration using Rucio, given that several members of NNBAR are either active or former members of ATLAS, including both co-spokespersons.…”

“…A high precision phase would follow with a dedicated high-flux beamline at the already appropriated Large Beam Port. The HIBEAM/NNBAR experiment has an active collaboration [1], and is currently focused on research for a Conceptual Design Report (CDR) to be published by the end of 2023 as a part of a EU Horizon2020 infrastructure design program [3]. The HIBEAM/NNBAR program will ultimately give a sensitivity increase of three orders of magnitude compared with previous neutron transformation searches [1,4,5].…”