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Title: Optimization of the SNS neutron beam current

Abstract

The proposed Spallation Neutron Source (SNS) facility will consist of two parts: (a) a high-energy (1-GeV) and high-powered (1-MW) proton accelerator (linac) and accumulator ring and (b) a target station that converts the protons to low-energy (<2 eV) neutrons and delivers them to the neutron-scattering instruments. It will be a 60-Hz facility delivering 6 {times} 10{sup 15} protons each second in 60-{micro}s pulses with a linac length of 490 m and an accumulator ring circumference of 220 m. Work is now under way to optimize the neutron beam current. Both the intensity and the time pulse characteristics are important with different requirements for different instruments. The effect of varying the reflector material, the moderator poison location, and the moderator dimensions has been considered. In addition, the impact on the current when a premoderator or a composite moderator is used has been assessed. Two reflector materials were picked to be studied in detail: beryllium and lead. A beryllium reflector gave a greater thermal neutron current but a wider pulse width, with the peak currents about the same. A simple figure of merit (FOM) (intensity/pulse width squared) favored the lead reflector.

Authors:
 [1]
  1. Oak Ridge National Lab., TN (United States)
Publication Date:
OSTI Identifier:
298354
Report Number(s):
CONF-981106-
Journal ID: TANSAO; ISSN 0003-018X; TRN: 99:001985
Resource Type:
Journal Article
Resource Relation:
Journal Name: Transactions of the American Nuclear Society; Journal Volume: 79; Conference: American Nuclear Society winter meeting, Washington, DC (United States), 15-19 Nov 1998; Other Information: PBD: 1998
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; 07 ISOTOPE AND RADIATION SOURCE TECHNOLOGY; ACCELERATOR FACILITIES; NEUTRON SOURCES; NEUTRON BEAMS; BEAM CURRENTS; OPTIMIZATION; MODERATORS; MEASURING INSTRUMENTS; NEUTRON REFLECTORS; NEUTRON SPECTRA

Citation Formats

Charlton, L.A.. Optimization of the SNS neutron beam current. United States: N. p., 1998. Web.
Charlton, L.A.. Optimization of the SNS neutron beam current. United States.
Charlton, L.A.. Thu . "Optimization of the SNS neutron beam current". United States. doi:.
@article{osti_298354,
title = {Optimization of the SNS neutron beam current},
author = {Charlton, L.A.},
abstractNote = {The proposed Spallation Neutron Source (SNS) facility will consist of two parts: (a) a high-energy (1-GeV) and high-powered (1-MW) proton accelerator (linac) and accumulator ring and (b) a target station that converts the protons to low-energy (<2 eV) neutrons and delivers them to the neutron-scattering instruments. It will be a 60-Hz facility delivering 6 {times} 10{sup 15} protons each second in 60-{micro}s pulses with a linac length of 490 m and an accumulator ring circumference of 220 m. Work is now under way to optimize the neutron beam current. Both the intensity and the time pulse characteristics are important with different requirements for different instruments. The effect of varying the reflector material, the moderator poison location, and the moderator dimensions has been considered. In addition, the impact on the current when a premoderator or a composite moderator is used has been assessed. Two reflector materials were picked to be studied in detail: beryllium and lead. A beryllium reflector gave a greater thermal neutron current but a wider pulse width, with the peak currents about the same. A simple figure of merit (FOM) (intensity/pulse width squared) favored the lead reflector.},
doi = {},
journal = {Transactions of the American Nuclear Society},
number = ,
volume = 79,
place = {United States},
year = {Thu Dec 31 00:00:00 EST 1998},
month = {Thu Dec 31 00:00:00 EST 1998}
}
  • In order to address the optimization in a pulsed operation, a systematic computational analysis has been made in comparison with operational experiences in superconducting radio-frequency (SRF) cavities at the Spallation Neutron Source (SNS). From the analysis it appears that the SNS SRF cavities can be operated at temperatures higher than 2.1 K, a fact resulting from both the pulsed nature of the superconducting cavities, the specific configuration of the existing cryogenic plant and the operating frequency.
  • The extended Q-range small angle neutron scattering (EQ-SANS) diffractometer at the Spallation Neutron Source has recently been completed. Initial commissioning has shown that it has achieved its high intensity, low background, and wide dynamic range design goals. One of the key components that enable these performances is its neutron optics, which are extensively optimized using analytical and Monte Carlo methods. The EQ-SANS optics consist of a curved multichannel beam bender and sections of straight neutron guides on both ends of the bender. The bender and the guide are made of float glass coated with supermirror multilayers. The function of themore » optics is to ensure low instrument background by avoiding the direct line of sight of the neutron moderator at downstream locations, while transporting thermal and cold neutrons to the sample with maximum efficiency. In this work, the optimization of the EQ-SANS optics is presented.« less
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