86 research outputs found
Cold Crystal Reflector Filter Concept
In this paper the theoretical concept of a cold crystal reflector filter will
be presented. The aim of this concept is to balance the shortcoming of the
traditional cold polycrystalline reflector filter, which lies in the
significant reduction of the neutron flux right above (in energy space) or
right below (wavelength space) the first Bragg edge
A next-generation inverse-geometry spallation-driven ultracold neutron source
The physics model of a next-generation spallation-driven high-current
ultracold neutron (UCN) source capable of delivering an extracted UCN rate of
around an-order-of-magnitude higher than the strongest proposed sources, and
around three-orders-of-magnitude higher than existing sources, is presented.
This UCN-current-optimized source would dramatically improve cutting-edge UCN
measurements that are currently statistically limited. A novel "Inverse
Geometry" design is used with 40 L of superfluid He (He-II), which acts as
a converter of cold neutrons (CNs) to UCNs, cooled with state-of-the-art
sub-cooled cryogenic technology to 1.6 K. Our design is optimized for a
100 W maximum heat load constraint on the He-II and its vessel. In our
geometry, the spallation target is wrapped symmetrically around the UCN
converter to permit raster scanning the proton beam over a relatively large
volume of tungsten spallation target to reduce the demand on the cooling
requirements, which makes it reasonable to assume that water edge-cooling only
is sufficient. Our design is refined in several steps to reach
s under our other restriction of 1 MW maximum
available proton beam power. We then study effects of the He-II scattering
kernel as well as reductions in due to pressurization to reach
s. Finally, we provide a design for the UCN
extraction system that takes into account the required He-II heat transport
properties and implementation of a He-II containment foil that allows UCN
transmission. We estimate a total useful UCN current from our source of
s from a 18 cm diameter guide 5 m from the source.
Under a conservative "no return" approximation, this rate can produce an
extracted density of cm in 1000~L external experimental
volumes with a Ni (335 neV) cut-off potential.Comment: Submitted to Journal of Applied Physic
Development of High Intensity Neutron Source at the European Spallation Source
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 \AA ), Very Cold
(10-40 \AA ), and Ultra Cold (several 100 \AA ) 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.Comment: 12 pages, 4 figures, proceeding of the 23rd meeting of the
International Collaboration on Advanced Neutron Sources (ICANS XXIII) 13th -
18th October 2019 in Chattanooga, Tennesse
Neutronic design for ESS-Bilbao neutron source
The European Spallation Source-Bilbao (ESS-Bilbao) project plans to build an accelerator facility compliant with the ESS-AB requirements which will be able to drive several experimental stations for research purposes involving intense proton beams with currents up to 75 mA, 50 MeV of final energy, 1.5 ms of pulse length and up to 50 Hz repetition rate. The accelerator will also drive a compact neutron source which will provide useful neutron beams to carry out experiments on moderator optimization, neutron optics devices and general neutron instrumentation as well as preparation work for experiments to be carried out by neutron beam users at the large facilities. © 2012 Elsevier B.V.This work has been possible thanks to the support of the computing infrastructure of the i2BASQUE academic network.Peer Reviewe
- …