Neutron Beam Characterization at the Intense Pulsed Neutron Source PDF Download
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Languages : en
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The Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory is a spallation neutron source dedicated to materials research. Its three cryogenic methane moderators provide twelve neutron beams to fourteen neutron scattering instruments and test facilities. The moderators at IPNS are of cryogenic methane (CH[sub 4]); one of liquid methane at 100 K, and two of solid methane at 30 K. These moderators produce intense beams of both cold and thermal neutrons. The moderators are each of a different physical configuration in order to tailor their performance for the instruments and facilities that operate on the neutron beams. As part of the ongoing operation of IPNS, as well as new enhancements to the target, moderator, and reflector systems, we have performed experiments characterizing the energy and time distribution of neutrons in the various beams. These measurements provide absolutely normalized energy spectra using foil activation techniques joined with time-of-flight measurements, and energy-dependent time distributions using a time-focused crystal analyzer. The IPNS accelerator system delivers 14[micro]A of 450 MeV protons, in 100 ns pulses at 30 Hz, to a target composed of water-cooled depleted uranium disks. The solid methane ''H'' moderator is 100 by 100 by 45 mm in size, centerline poisoned with 0.25 mg/mm[sup 2] gadolinium, and decoupled from the graphite reflector with 0.5 mm of cadmium. The liquid methane ''F'' moderator, which is viewed from both faces, is also 100 by 100 by 45 mm in size, gadolinium poisoned 16 mm below each of the two viewed surfaces, and decoupled from the graphite reflector with cadmium. The solid methane ''C'' moderator has a re-entrant ''grooved'' geometry. The moderator is 100 by 100 by 80 mm overall, with 40 mm deep 12 mm wide horizontal grooves in the viewed surface. These grooves cover 50% of the viewed surface area. The ''C'' moderator is unpoisoned, but is decoupled from the graphite reflector with 0.5 mm of cadmium.
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Languages : en
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Book Description
The Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory is a spallation neutron source dedicated to materials research. Its three cryogenic methane moderators provide twelve neutron beams to fourteen neutron scattering instruments and test facilities. The moderators at IPNS are of cryogenic methane (CH[sub 4]); one of liquid methane at 100 K, and two of solid methane at 30 K. These moderators produce intense beams of both cold and thermal neutrons. The moderators are each of a different physical configuration in order to tailor their performance for the instruments and facilities that operate on the neutron beams. As part of the ongoing operation of IPNS, as well as new enhancements to the target, moderator, and reflector systems, we have performed experiments characterizing the energy and time distribution of neutrons in the various beams. These measurements provide absolutely normalized energy spectra using foil activation techniques joined with time-of-flight measurements, and energy-dependent time distributions using a time-focused crystal analyzer. The IPNS accelerator system delivers 14[micro]A of 450 MeV protons, in 100 ns pulses at 30 Hz, to a target composed of water-cooled depleted uranium disks. The solid methane ''H'' moderator is 100 by 100 by 45 mm in size, centerline poisoned with 0.25 mg/mm[sup 2] gadolinium, and decoupled from the graphite reflector with 0.5 mm of cadmium. The liquid methane ''F'' moderator, which is viewed from both faces, is also 100 by 100 by 45 mm in size, gadolinium poisoned 16 mm below each of the two viewed surfaces, and decoupled from the graphite reflector with cadmium. The solid methane ''C'' moderator has a re-entrant ''grooved'' geometry. The moderator is 100 by 100 by 80 mm overall, with 40 mm deep 12 mm wide horizontal grooves in the viewed surface. These grooves cover 50% of the viewed surface area. The ''C'' moderator is unpoisoned, but is decoupled from the graphite reflector with 0.5 mm of cadmium.
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Languages : en
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The Intense Pulsed Neutron Source (IPNS) neutron scattering facility (NSF) has been investigated for its applicability to neutron activation analysis. A polyethylene insert has been added to the vertical hole VT3 which enhances the thermal neutron flux by a factor of two. The neutron spectral distribution at this position has been measured by the multiple-foil technique which utilized 28 activation reactions and the STAYSL computer code. The validity of this spectral measurement was tested by two irradiations of National Bureau of Standards SRM-1571 (orchard leaves), SRM-1575 (pine needles), and SRM-1645 (river sediment). The average thermal neutron flux for these irradiations normalized to 10 .mu.amp proton beam is 4.0 x 1011 n/cm2-s. Concentrations of nine trace elements in each of these SRMs have been determined by gamma-ray spectrometry. Agreement of measured values to certified values is demonstrated to be within experiment error.
Author: Chun Keung Loong
Publisher: World Scientific
ISBN: 9814544035
Category : Science
Languages : en
Pages : 245
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Book Description
The applications of the use of cold neutrons for condensed matter research at accelerator-based spallation sources are less well-known than that of the use of cold neutrons at reactor sources. This book represents the outcome of the first international workshop on “Materials Research Using Cold Neutrons at Pulsed Sources”. It consists of overviews of the present status and future trends in research opportunities using cold neutrons, as well as topical papers focusing on the areas of small-angle neutron scattering, reflectivity and spectroscopic studies of a rich variety of materials, from adsorbed molecules to thin films to coal to metallic glasses. These papers will benefit researchers who are interested in the characterization of microscopic properties of advanced materials.
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Category :
Languages : en
Pages : 9
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Book Description
The three moderators at the Intense Pulsed Neutron Source are of cryogenic methane (CH4): one of liquid methane at 100 K, and two of solid methane at 30 K. These moderators produce intense beams of both cold and thermal neutrons. The moderators are each of a different physical configuration in order to tailor their performance for the fourteen instruments and test facilities that operate on the twelve neutron beams. IPNS has started a program to enhance the effectiveness of its target/moderator/reflector system. This program involves both Monte Carlo computer modeling of the system and measuring the characteristics of the neutron beams. The measurements reported here provide absolute spectra using foil activation techniques joined with time-of-flight measurements performed with thin beam monitor detectors installed at the neutron scattering instruments. We also outline a codified procedure which we believe will be useful at other pulsed neutron sources to perform equivalent measurements. (auth).
Author: J. M. Carpenter
Publisher: Cambridge University Press
ISBN: 0521857813
Category : Science
Languages : en
Pages : 539
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Book Description
This book provides a comprehensive and up-to-date introduction to the fundamental theory and applications of slow-neutron scattering.
![Characterization of Sup 3 He Area Sensitive Proportional Counters at IPNS for SANS Applications. [Intense Pulsed Neutron Source (IPNS), Small Angle Neutron Scattering (SANS)]. PDF](https://books.google.com/books/content/images/frontcover/HNmIAQAACAAJ?fife=w80-h100)
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Category :
Languages : en
Pages : 12
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Book Description
The Small Angle Diffractometer (SAD) at the Intense Pulsed Neutron Source (IPNS) utilizes a 20 x 20 cm2 Borkowski-Kopp type 3He position sensitive detector (PSD) which has reliably performed small-angle neutron scattering experiments for more than a decade. The pulsed-source based SAD employs a small, but fixed, sample-to-detector distance and a pulsed polychromatic neutron beam. The neutron energies are resolved through time-of-flight (TOF) measurements so that a much wider range of momentum transfer is probed in a single measurement compared to the range of spectrometers using monochromatic incident beams. However, the pulsed source requires a short sample-to-detector distance so that the detector covers a large solid angle, but with lower angular resolution, and this situation puts stringent demands on the spatial resolution of the detector. Previously, nonlinearities in the position encoding of detected neutrons required that the outer channels of the detector, representing 40% of the detector area, be discarded. This paper presents a technique to characterize both the position encoding and the position resolution of the entire detector so that the whole detector can be used for SANS measurements.
Author: Christopher R. Gould
Publisher: World Scientific
ISBN: 9810246676
Category : Science
Languages : en
Pages : 268
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Book Description
Low energy neutron beams are used to address many questions in nuclear physics, particle physics and astrophysics. The scientific issues include elucidating the nature of time reversal noninvariance; understanding the origin of the baryon asymmetry in the Universe; describing the weak interaction between quarks and between nucleons; understanding the origin of the elements in stellar and big bang nucleosynthesis.This book summarizes how spallation neutron sources work and discuss the advantages of pulsed beams in reducing systematic errors in precision measurements. It also describes recent breakthroughs in ultracold neutron production, together with the physics that will be addressed by the new generation of intense neutron sources.
Author: Eugene Tochilin
Publisher:
ISBN:
Category : Cyclotrons
Languages : en
Pages : 34
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Author: International Atomic Energy Agency
Publisher: IAEA Tecdoc
ISBN: 9789201089151
Category : Science
Languages : en
Pages : 0
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Book Description
Annotation This publication aims to expand the knowledge and understanding of material behaviour in terms of their characterization and qualification under extreme conditions for nuclear energy technologies, and also to contribute to the enhancement of utilization and applications of research reactor and accelerator based neutron sources.
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Category :
Languages : en
Pages : 33
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Book Description
We investigate the potential for neutron generation using the 1 MeV RHEPP-1 intense pulsed ion beam facility at Sandia National Laboratories for a number of emerging applications. Among these are interrogation of cargo for detection of special nuclear materials (SNM). Ions from single-stage sources driven by pulsed power represent a potential source of significant neutron bursts. While a number of applications require higher ion energies (e.g. tens of MeV) than that provided by RHEPP-1, its ability to generate deuterium beams allow for neutron generation at and below 1 MeV. This report details the successful generation and characterization of deuterium ion beams, and their use in generating up to 3 x 101° neutrons into 4[pi] per 5kA ion pulse.
