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Title: Neutron Capture and Transmission Measurements and Resonance Parameter Analysis of Samarium

Abstract

The purpose of the present work is to accurately measure the neutron cross sections of samarium. The most significant isotope is {sup 149}Sm, which has a large neutron absorption cross section at thermal energies and is a {sup 235}U fission product with a 1% yield. Its cross sections are thus of concern to reactor neutronics. Neutron capture and transmission measurements were performed by the time-of-flight technique at the Rensselaer Polytechnic institute (RPI) LINAC facility using metallic and liquid Sm samples. The capture measurements were made at the 25 meter flight station with a multiplicity-type capture detector, and the transmission total cross-section measurements were performed at 15- and 25-meter flight stations with {sup 6}Li glass scintillation detectors. Resonance parameters were determined by a combined analysis of six experiments (three capture and three transmission) using the multi-level R-matrix Bayesian code SAMMY version M2. The significant features of this work are as follows. Dilute samples of samarium nitrate in deuterated water (D{sub 2}O) were prepared to measure the strong resonances at 0.1 and 8 eV without saturation. Disk-shaped spectroscopic quartz cells were obtained with parallel inner surfaces to provide a uniform thickness of solution. The diluent feature of the SAMMY program was usedmore » to analyze these data. The SAMMY program also includes multiple scattering corrections to capture yield data and resolution functions specific to the RPI facility. Resonance parameters for all stable isotopes of samarium were deduced for all resonances up to 30 eV. Thermal capture cross-section and capture resonance integral calculations were made using the resultant resonance parameters and were compared to results obtained using resonance parameters from ENDF/B-VI updated through release 3. Extending the definition of the capture resonance integral to include the strong 0.1 eV resonance in {sup 149}Sm, present measurements agree within estimated uncertainties with EnDF/B-VI release 3. The thermal capture cross-section was calculated from the present measurements of the resonance parameters and also agrees with ENDF within estimated uncertainties. The present measurements reduce the statistical uncertainties in resonance parameters compared to prior measurements.« less

Authors:
; ; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Lockheed Martin Corporation, Schenectady, NY 12301 (US)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
821312
Report Number(s):
LM-01K066
TRN: US0400703
DOE Contract Number:  
AC12-00SN39357
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: 16 Jul 2001
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; 42 ENGINEERING; CAPTURE; CROSS SECTIONS; FISSION PRODUCTS; LINEAR ACCELERATORS; MULTIPLE SCATTERING; NEUTRON REACTIONS; NEUTRONS; R MATRIX; RESONANCE; RESONANCE INTEGRALS; SAMARIUM; SAMARIUM NITRATES; SCINTILLATION COUNTERS; SOLVENTS; STABLE ISOTOPES; TOTAL CROSS SECTIONS

Citation Formats

Leinweber, G, Burke, J A, Knox, H D, Drindak, N J, Mesh, D W, Haines, W T, Ballad, R V, Block, R C, Slovacek, R E, Werner, C J, Trbovich, M J, Barry, D P, and Sato, T. Neutron Capture and Transmission Measurements and Resonance Parameter Analysis of Samarium. United States: N. p., 2001. Web. doi:10.2172/821312.
Leinweber, G, Burke, J A, Knox, H D, Drindak, N J, Mesh, D W, Haines, W T, Ballad, R V, Block, R C, Slovacek, R E, Werner, C J, Trbovich, M J, Barry, D P, & Sato, T. Neutron Capture and Transmission Measurements and Resonance Parameter Analysis of Samarium. United States. doi:10.2172/821312.
Leinweber, G, Burke, J A, Knox, H D, Drindak, N J, Mesh, D W, Haines, W T, Ballad, R V, Block, R C, Slovacek, R E, Werner, C J, Trbovich, M J, Barry, D P, and Sato, T. Mon . "Neutron Capture and Transmission Measurements and Resonance Parameter Analysis of Samarium". United States. doi:10.2172/821312. https://www.osti.gov/servlets/purl/821312.
@article{osti_821312,
title = {Neutron Capture and Transmission Measurements and Resonance Parameter Analysis of Samarium},
author = {Leinweber, G and Burke, J A and Knox, H D and Drindak, N J and Mesh, D W and Haines, W T and Ballad, R V and Block, R C and Slovacek, R E and Werner, C J and Trbovich, M J and Barry, D P and Sato, T},
abstractNote = {The purpose of the present work is to accurately measure the neutron cross sections of samarium. The most significant isotope is {sup 149}Sm, which has a large neutron absorption cross section at thermal energies and is a {sup 235}U fission product with a 1% yield. Its cross sections are thus of concern to reactor neutronics. Neutron capture and transmission measurements were performed by the time-of-flight technique at the Rensselaer Polytechnic institute (RPI) LINAC facility using metallic and liquid Sm samples. The capture measurements were made at the 25 meter flight station with a multiplicity-type capture detector, and the transmission total cross-section measurements were performed at 15- and 25-meter flight stations with {sup 6}Li glass scintillation detectors. Resonance parameters were determined by a combined analysis of six experiments (three capture and three transmission) using the multi-level R-matrix Bayesian code SAMMY version M2. The significant features of this work are as follows. Dilute samples of samarium nitrate in deuterated water (D{sub 2}O) were prepared to measure the strong resonances at 0.1 and 8 eV without saturation. Disk-shaped spectroscopic quartz cells were obtained with parallel inner surfaces to provide a uniform thickness of solution. The diluent feature of the SAMMY program was used to analyze these data. The SAMMY program also includes multiple scattering corrections to capture yield data and resolution functions specific to the RPI facility. Resonance parameters for all stable isotopes of samarium were deduced for all resonances up to 30 eV. Thermal capture cross-section and capture resonance integral calculations were made using the resultant resonance parameters and were compared to results obtained using resonance parameters from ENDF/B-VI updated through release 3. Extending the definition of the capture resonance integral to include the strong 0.1 eV resonance in {sup 149}Sm, present measurements agree within estimated uncertainties with EnDF/B-VI release 3. The thermal capture cross-section was calculated from the present measurements of the resonance parameters and also agrees with ENDF within estimated uncertainties. The present measurements reduce the statistical uncertainties in resonance parameters compared to prior measurements.},
doi = {10.2172/821312},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2001},
month = {7}
}