Measuring longitudinal beam parameters in the low energy section of the Oak Ridge Spallation Neutron Source accelerator

The structural and chemical versatility of functional molecular materials, such as molecular magnets and metal-organic frameworks (MOFs), underlie important technological, industrial, and environmental applications. The extensive structural complexities now well-documented for these systems are likely to be associated with unprecedented pressure-induced behavior compared with the traditional solid state materials more commonly explored under high pressure conditions.1 Furthermore, the typically open (low density, often porous) nature of these materials is likely to induce such phenomena at more moderate pressures, such as may be routinely encountered in practical applications.2,3 Here we report pressure-induced spin-state switching in the Prussian Blue analogue, FePt(CN)6, including in situ Synchrotron (17-BM, Advanced Photon Source) and Neutron (SNAP, Spallation Neutron Source) powder diffraction studies. Work done at Argonne and use of the Advanced Photon Source (APS) was supported by the U.S. Department of Energy under Contract No. DE-AC02-06CH11357. Research at Oak Ridge National Laboratory's Spallation Neutron Source (SNS) was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U. S. Department of Energy.

Download Full-text

The Macromolecular Neutron Diffractometer MaNDi at the Spallation Neutron Source

Journal of Applied Crystallography ◽

10.1107/s1600576715011243 ◽

2015 ◽

Vol 48 (4) ◽

pp. 1302-1306 ◽

Cited By ~ 48

Author(s):

Leighton Coates ◽

Matthew J. Cuneo ◽

Matthew J. Frost ◽

Junhong He ◽

Kevin L. Weiss ◽

...

Keyword(s):

Data Collection ◽

Single Crystals ◽

Neutron Source ◽

Diffraction Data ◽

National Laboratory ◽

Spallation Neutron Source ◽

Oak Ridge ◽

Neutron Diffractometer ◽

Macromolecular Systems ◽

Neutron Time

The Macromolecular Neutron Diffractometer (MaNDi) is located on beamline 11B of the Spallation Neutron Source at Oak Ridge National Laboratory. The instrument is a neutron time-of-flight wavelength-resolved Laue diffractometer optimized to collect diffraction data from single crystals. The instrument has been designed to provide flexibility in several instrumental parameters, such as beam divergence and wavelength bandwidth, to allow data collection from a range of macromolecular systems.

Download Full-text

Simulation of the low energy H− injector into the National Spallation Neutron Source radio frequency quadrupole accelerator

Review of Scientific Instruments ◽

10.1063/1.1148743 ◽

1998 ◽

Vol 69 (2) ◽

pp. 965-967 ◽

Cited By ~ 3

Author(s):

M. A. Leitner ◽

D. C. Wutte ◽

K. N. Leung

Keyword(s):

Radio Frequency ◽

Neutron Source ◽

Low Energy ◽

Spallation Neutron Source ◽

Radio Frequency Quadrupole

Download Full-text

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

Journal of Neutron Research ◽

10.3233/jnr-190134 ◽

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.

Download Full-text

High-resolution neutron time-of-flight measurements for light water at the Spallation Neutron Source (SNS), Oak Ridge National Laboratory

EPJ Web of Conferences ◽

10.1051/epjconf/202023914005 ◽

2020 ◽

Vol 239 ◽

pp. 14005

Author(s):

Luiz Leal ◽

Vaibhav Jaiswal ◽

Alexander I. Kolesnikov

Keyword(s):

Experimental Data ◽

Neutron Source ◽

National Laboratory ◽

Operating Conditions ◽

Spallation Neutron Source ◽

Light Water ◽

Oak Ridge ◽

Oak Ridge National Laboratory ◽

Thermal Scattering ◽

Reactor Operating

Series of light water inelastic neutron scattering experiments have been made at the Oak Ridge National Laboratory (ORNL), Spallation Neutron Source (SNS) covering temperatures ranging from 295 K to 600 K and pressures of 1 bar and 150 bar. The temperatures and pressures ranges correspond to that of pressurized light water reactors. The inelastic scattering measurements will help the development of light water thermal scattering kernels, also known as S (α,β) thermal scattering law (TSL), in a consistent fashion given the amount and the quality of the measured data. Light water thermal scattering evaluations available in existing nuclear data libraries have certain limitations and pitfalls. This paper introduces the state of the art of the light water thermal scattering cross-section data not only for room temperature but as well as for reactor operating temperatures, i.e. 550 - 600 K. During the past few years there has been a renewed interest in re-investigating the existing TSL models and utilize the recent experimental data or perform molecular dynamics simulations. It should be pointed out that no single TSL evaluation is based entirely on experimental data and one has to rely on TSL models or a combination of both. New TOF measurement of light water at the SNS, with a detailed description of the experimental setup, measurement conditions, and the associated foreseen results is presented in this paper. The analysis of the experimental data would help in validating the existing approach based on old experimental data or based on molecular dynamic simulations using classical water models, knowledge of which is very important to generate TSL libraries at reactor operating conditions.

Download Full-text

Value engineering study final report on -- Spallation Neutron Source, Oak Ridge, Tennessee

10.2172/764588 ◽

1999 ◽

Author(s):

Keyword(s):

Neutron Source ◽

Value Engineering ◽

Final Report ◽

Spallation Neutron Source ◽

Oak Ridge ◽

Engineering Study

Download Full-text

The macromolecular neutron diffractometer (MaNDi) at the Spallation Neutron Source, Oak Ridge: enhanced optics design, high-resolution neutron detectors and simulated diffraction

Journal of Applied Crystallography ◽

10.1107/s0021889810008587 ◽

2010 ◽

Vol 43 (3) ◽

pp. 570-577 ◽

Cited By ~ 47

Author(s):

L. Coates ◽

A. D. Stoica ◽

C. Hoffmann ◽

J. Richards ◽

R. Cooper

Keyword(s):

High Resolution ◽

Neutron Source ◽

National Laboratory ◽

High Energy ◽

Neutron Guide ◽

Spallation Neutron Source ◽

Neutron Detectors ◽

Spectral Window ◽

Oak Ridge ◽

Neutron Diffractometer

The macromolecular neutron diffractometer MaNDi is currently under construction at the first target station of the Spallation Neutron Source at Oak Ridge National Laboratory. This instrument will collect neutron diffraction data from small single crystals (0.1–1 mm3) with lattice constants between 100 and 300 Å, as well as data from less well ordered systems such as fibers. A focusing neutron guide has been designed to filter the high-energy neutron component of the spectrum and to provide a narrow beam with a wide spectral window and angular divergence almost insensitive to neutron wavelength. The system includes a final interchangeable section of neutron guide and two slits, which enable tuning of the horizontal and vertical beam divergence between 0.12 and 0.80° (full width at half-maximum) at the sample position. This allows the trading of intensity for resolution, depending on the scientific requirements. Efforts to enhance and develop suitable high-resolution neutron detectors at an affordable price are also discussed. Finally, the parameters of the neutron guide and detectors were used to simulate diffraction from a large unit cell.

Download Full-text