The U. K. Spallation Neutron Source

1980 ◽  
Vol 290 (1043) ◽  
pp. 657-672 ◽  
Keyword(s):  
Neutron Source ◽  
Amorphous Materials ◽  
Molecular Spectroscopy ◽  
High Energy ◽  
Fast Neutrons ◽  
Spallation Neutron Source ◽  
Crystalline Materials ◽  
Epithermal Neutrons ◽  
Under Construction ◽  
Pulsed Neutron

Pulsed neutron sources offer an attractive route for the realization of effective fluxes greater than those currently available from high flux reactors. The spallation neutron source now under construction at the Rutherford Laboratory will produce intense bursts of fast neutrons through interactions of 800 MeV protons with a heavy metal target. The fast neutrons are slowed down in nearby hydrogenous moderators viewed by some 20 time-of-flight neutron scattering instruments. The spectrum of the moderated neutrons is strongly enhanced in the high velocity region compared with that from a reactor. The new source will be comparable with the best beam reactors for experiments with neutrons of mid-thermal energy, and will provide unrivalled potential for use of the epithermal neutrons. Areas of science that will benefit immediately are the study of liquids and amorphous materials, high energy excitations in crystalline materials, molecular spectroscopy, surface phenomena and kinetic processes, as well as a range of crystallographic applications.

scholarly journals Status of the two-dimensional, multi-wire proportional chamber detector for the China Spallation Neutron Source

2018 ◽  
Vol 48 ◽  
pp. 1860121 ◽  
Author(s):  
Zhiwen Wen ◽  
Huirong Qi
Keyword(s):  
Neutron Source ◽  
Neutron Detector ◽  
Detection Efficiency ◽  
Spallation Neutron Source ◽  
Two Dimensional ◽  
Large Area ◽  
Position Resolution ◽  
Proportional Chamber ◽  
High Detection Efficiency ◽  
Under Construction

The re-designed two-dimensional, multi-wire proportional chamber (MWPC) detector based on the [Formula: see text]He operation gas has been developed for the multifunctional reflection spectrum detection requirements in China Spallation Neutron Source (CSNS), which is under construction in Guangdong province, China. This efficient thermal neutron detector with large area (200 mm [Formula: see text] 200 mm active area), two-dimensional position sensitive (<2 mm of position resolution), high detection efficiency (>65% in the wavelength of 1.8Å) and good n/[Formula: see text] discrimination would meet some requirements in CSNS The neutron detector consists of a MWPC detector and a high-pressure gas vessel. The wire readout structures of the detector and the gas purity device have been optimized based on previous design and testing. The re-designed MWPC detector with an absorber thickness of 10 mm and 8.5 atm operating gas mixture of [Formula: see text]He and C[Formula: see text]H[Formula: see text] was constructed. Using the non-return valve manufactured by Swagelok, the gas purity device was developed to clean the water and remove gas impurities. The effective cycle time can be up to 50 min per sequence. The performance of the position resolution and the two-dimensional imaging accuracy by the traditional center of gravity readout method was studied with an X-ray radiation source and the neutron source. At the end of this year, the detector will be mounted at CSNS and studied using the neutron source.

Detection of Combined n/γ Fission Signatures Induced by an Epithermal Neutron Source

2017 ◽  
Vol 3 (3) ◽  
Author(s):  
A. Ocherashvili ◽  
T. Bogucarska ◽  
A. Beck ◽  
G. Heger ◽  
M. Mosconi ◽  
...  
Keyword(s):  
Neutron Source ◽  
Proper Time ◽  
Pulse Shape Discrimination ◽  
Fast Neutrons ◽  
Nuclear Materials ◽  
Test Assembly ◽  
Fission Neutrons ◽  
Pulsed Neutron ◽  
Prompt Fission ◽  
Multiple Detectors

In this paper, a method is presented for the detection of special nuclear materials (SNMs) in shielded containers, which is both sensitive and applicable under field conditions. The method uses an external pulsed neutron source to induce fission in SNM and subsequent detection of the fast prompt fission neutrons. The detectors surrounding the container under investigation are liquid scintillation detectors able to distinguish gamma rays from fast neutrons by means of pulse shape discrimination method (PSD). One advantage of these detectors, besides the ability for PSD analysis, is that the analog signal from a detection event is of very short duration (typically few tens of nanoseconds). This allows the use of very short coincidence gates for the detection of the prompt fission neutrons in multiple detectors, while benefiting from a low background coincidence rate, yielding a low detection limit. Another principle advantage of this method derives from the fact that the external neutron source is pulsed. By proper time gating, the interrogation can be conducted by epithermal source neutrons only. These neutrons do not appear in the fast neutron signal following the PSD analysis, thus providing a fundamental method for separating the interrogating source neutrons from the sample response in the form of fast fission neutrons. This paper describes laboratory tests with a configuration of eight detectors in the Pulsed Neutron Interrogation Test Assembly (PUNITA). Both the photon and neutron signature for induced fission is observed, and the methods used to isolate these signatures are described and demonstrated.

Structural studies of amorphous materials using a pulsed neutron source

1974 ◽  
Vol 117 (2) ◽  
pp. 445-454 ◽  
Author(s):  
R.N. Sinclair ◽  
D.A.G. Johnson ◽  
J.C. Dore ◽  
J.H. Clarke ◽  
A.C. Wright
Keyword(s):  
Neutron Source ◽  
Amorphous Materials ◽  
Structural Studies ◽  
Pulsed Neutron ◽  
Pulsed Neutron Source

scholarly journals PDF Analysis on a Laboratory System: Adapting the Experiment to the Material

2014 ◽  
Vol 70 (a1) ◽  
pp. C870-C870
Author(s):  
Céleste Reiss ◽  
Milen Gateshki ◽  
Marco Sommariva
Keyword(s):  
Distribution Function ◽  
Pair Distribution Function ◽  
Amorphous Materials ◽  
Nearest Neighbors ◽  
High Energy ◽  
Experimental Point ◽  
Laboratory System ◽  
Crystalline Materials ◽  
X Ray ◽  
Pdf Analysis

The increased interest in recent years regarding the properties and applications of nanomaterials has also created the need to characterize the structures of these materials. However, due to the lack of long-range atomic ordering, the structures of nanostructured and amorphous materials are not accessible by conventional diffraction methods used to study crystalline materials. One of the most promising techniques to study nanostructures using X-ray diffraction is by using the total scattering (Bragg peaks and diffuse scattering) from the samples and the pair distribution function (PDF) analysis. The pair distribution function provides the probability of finding atoms separated by a certain distance. This function is not direction-dependent; it only looks at the absolute value of the distance between the nearest neighbors, the next nearest neighbors and so on. The method can therefore also be used to analyze non-crystalline materials. From experimental point of view a typical PDF analysis requires the use of intense high-energy X-ray radiation (E ≥ 20 KeV) and a wide 2θ range. After the initial feasibility studies regarding the use of standard laboratory diffraction equipment for PDF analysis [1-3] this application has been further developed to achieve improved data quality and to extend the range of materials, environmental conditions and geometrical configurations that can be used for PDF experiments. Studies performed on different nanocrystalline and amorphous materials of scientific and technological interest, including organic substances, oxides, metallic alloys, etc. have demonstrated that PDF analysis with a laboratory diffractometer can be a valuable tool for structural characterization of nanomaterials. This contribution presents several examples of laboratory PDF studies, in which the experimental conditions have been successfully adapted to match the specific requirements of materials under investigation.

Mercury Target and Its Peripheral Devices for 1 MW Spallation Neutron Source

2004 ◽  
Author(s):  
Katsuhiro Haga ◽  
Masanori Kaminaga ◽  
Hidetaka Kinoshita ◽  
Hiroyuki Kogawa ◽  
Hiroshi Satoh ◽  
...  
Keyword(s):  
Neutron Source ◽  
High Intensity ◽  
Cross Flow ◽  
High Energy ◽  
Proton Accelerator ◽  
Circulation System ◽  
Design Activity ◽  
Spallation Neutron Source ◽  
Present Design ◽  
Facility Construction

The Japan Atomic Energy Research Institute (JAERI) and the High Energy Accelerator Research Organization (KEK) are promoting a plan to construct a 1MW neutron source facility at the Tokai Research Establishment, JAERI, under the Japan Proton Accelerator Research Complex (J-PARC) Project. In the facility, 1 MW pulsed proton beam from a high-intensity proton accelerator will be injected into a mercury target in order to produce high-intensity pulse neutrons for use in the fields of life and material sciences. In order to realize such a high-power neutron source, the design activity of a cross flow type (CFT) mercury target and its peripheral devices has continued and the results is reflected in the ordering specifications of the facility construction. The arrangement of each component and their structure was optimized through experimental and analytical studies. In this paper, the present design of the mercury target components for 1MW spallation neutron source including the target vessel, a mercury circulation system, and a target trolley will be reported.

High Energy Neutron Dosimetry of a Spallation Neutron Source

2008 ◽  
pp. 488-488-10
Author(s):  
F Hegedüs ◽  
WV Green ◽  
P Stiller ◽  
S Green ◽  
V Herrnberger ◽  
...  
Keyword(s):  
Neutron Source ◽  
High Energy ◽  
Spallation Neutron Source ◽  
Neutron Dosimetry ◽  
High Energy Neutron ◽  
Energy Neutron

scholarly journals Simulating neutron transport in long beamlines at a spallation neutron source using Geant4

2020 ◽  
Vol 22 (2-3) ◽  
pp. 183-189
Author(s):  
Douglas D. DiJulio ◽  
Isak Svensson ◽  
Xiao Xiao Cai ◽  
Joakim Cederkall ◽  
Phillip M. Bentley
Keyword(s):  
Monte Carlo ◽  
Neutron Source ◽  
Variance Reduction ◽  
Neutron Transport ◽  
High Energy ◽  
Low Energy ◽  
Deep Penetration ◽  
Monte Carlo Code ◽  
Spallation Neutron Source ◽  
Unique Challenge

The transport of neutrons in long beamlines at spallation neutron sources presents a unique challenge for Monte-Carlo transport calculations. This is due to the need to accurately model the deep-penetration of high-energy neutrons through meters of thick dense shields close to the source and at the same time to model the transport of low- energy neutrons across distances up to around 150 m in length. Typically, such types of calculations may be carried out with MCNP-based codes or alternatively PHITS. However, in recent years there has been an increased interest in the suitability of Geant4 for such types of calculations. Therefore, we have implemented supermirror physics, a neutron chopper module and the duct-source variance reduction technique for low- energy neutron transport from the PHITS Monte-Carlo code into Geant4. In the current work, we present a series of benchmarks of these extensions with the PHITS software, which demonstrates the suitability of Geant4 for simulating long neutron beamlines at a spallation neutron source, such as the European Spallation Source, currently under construction in Lund, Sweden.

Integration of Proton Beam Collimation Scheme in the Spallation Neutron Source (SNS) Accumulator Ring Including Dose and Activation Estimates

2004 ◽  
Author(s):  
Nicholas Simos ◽  
Hans Ludewig ◽  
D. Raparia ◽  
N. Catalan-Lasheras ◽  
S. Cousineau ◽  
...  
Keyword(s):  
Proton Beam ◽  
Neutron Source ◽  
High Energy ◽  
Ring Structure ◽  
Integration Scheme ◽  
Spallation Neutron Source ◽  
Energy Beam ◽  
Optimization Study ◽  
Ring Section ◽  
Final Proton

This paper details the integration scheme as well as the induced activation by the proton beam clean-up system (collimation) in the accumulator ring section of the Spallation Neutron Source (SNS) accelerator complex. Specifically, the results of the optimization study in terms of satisfying both the optics of the proton beam and the minimization of activation of the accelerator components as well as of the surrounding structure have guided both the design of the components and their integration and are presented in this paper. The resulted collimation scheme is a two-stage clean-up system consisting of proton beam halo intercepting scrapers and appropriate fixed aperture absorbers. The accumulator ring structure consists of the High Energy Beam Transfer (HEBT) line which receives the 1 GeV proton beam from the SNS LINAC accelerator, the accumulator ring itself which compiles the micro-pulses into the final 60 Hz pulse, and the RTBT line that transfers the final proton pulse to the accelerator target. Collimation takes place in all three ring components and along respective straight sections with the exception of the off-momentum particle clean-up in the HEBT line in which off-momentum protons are guided to a stationary absorber outside the transfer line. Given that the activation issues of the collimating structures themselves as well as of the nearby accelerator components (mainly magnets) are similar in all sections of the ring, the activation of components in the ring clean-up system will be discussed in detail in the following sections.

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