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Title: Spin and Parity Assignment of Neutron Resonances using Gamma-ray Multiplicity

Abstract

Decay gamma rays following neutron capture on various isotopes are collected by the Detector for Advanced Neutron Capture Experiments (DANCE) array, which is located at flight path 14 at the Lujan Neutron Scattering Center at Los Alamos National Laboratory. The high segmentation (160 detectors) and close packing of the detector array enable gamma-ray multiplicity measurements. The calorimetric properties of the DANCE array coupled with the neutron time-of-flight technique enables one to gate on a specific resonance of a given isotope in the time-of-flight spectrum and obtain the summed energy spectrum for that isotope. The singles gamma-ray spectrum for each multiplicity can be separated by their DANCE cluster multiplicity. The multiplicity distribution contains the signatures of spin and parity of the capture state. Under suitable circumstances where the difference between spins of the initial (capture) and final (ground) state is large enough, the signatures in the multiplicity distribution can be used in improving the spin assignment of the initial state. The spin assignment is applied with varying degree of success to difference isotopes and description of this application for {sup 95}Mo, {sup 151,153}Eu, and {sup 155,157}Gd is reviewed briefly.

Authors:
 [1];  [2];  [3];  [4]; ; ;  [3];  [5];  [4]; ; ; ;  [6]; ; ; ; ; ; ; more »;  [7]; ;  [8] « less
  1. Stanford University, Palo Alto, CA 94305 (United States)
  2. (Mongolia)
  3. North Carolina State University, Raleigh, NC 27695 (United States)
  4. (United States)
  5. MonAme Scientific Research Center, Ulaanbaatar (Mongolia)
  6. Lawrence Livermore National Laboratory, Livermore, CA 9455 (United States)
  7. Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)
  8. Charles University in Prague, CZ-180 00 Prague 8 (Czech Republic)
Publication Date:
OSTI Identifier:
21293502
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1109; Journal Issue: 1; Conference: 1. Ulaanbaatar conference on nuclear physics and applications, Ulaanbaatar (Mongolia), 8-11 Sep 2008; Other Information: DOI: 10.1063/1.3122240; (c) 2009 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; CAPTURE; EUROPIUM 153; GADOLINIUM 157; GAMMA DECAY; GAMMA RADIATION; GAMMA SPECTRA; GROUND STATES; LANL; MOLYBDENUM 95; MULTIPLICITY; NEUTRON REACTIONS; NEUTRONS; PARITY; RESONANCE; SPIN; TIME-OF-FLIGHT METHOD

Citation Formats

Agvaanluvsan, U., MonAme Scientific Research Center, Ulaanbaatar, Mitchell, G. E., Triangle Universities Nuclear Laboratory, Durham, NC 27708, Baramsai, B., Chyzh, A., Walker, C., Dashdorj, D., North Carolina State University, Raleigh, NC 27695, Becker, J. A., Parker, W. E., Sleaford, B., Wu, C. Y., Bredeweg, T. A., Couture, A., Haight, R. C., Jandel, M., Rundberg, R. S., Ullmann, J. L., Vieira, D. J., Wouters, J. M., Krticka, M., and Becvar, F. Spin and Parity Assignment of Neutron Resonances using Gamma-ray Multiplicity. United States: N. p., 2009. Web. doi:10.1063/1.3122240.
Agvaanluvsan, U., MonAme Scientific Research Center, Ulaanbaatar, Mitchell, G. E., Triangle Universities Nuclear Laboratory, Durham, NC 27708, Baramsai, B., Chyzh, A., Walker, C., Dashdorj, D., North Carolina State University, Raleigh, NC 27695, Becker, J. A., Parker, W. E., Sleaford, B., Wu, C. Y., Bredeweg, T. A., Couture, A., Haight, R. C., Jandel, M., Rundberg, R. S., Ullmann, J. L., Vieira, D. J., Wouters, J. M., Krticka, M., & Becvar, F. Spin and Parity Assignment of Neutron Resonances using Gamma-ray Multiplicity. United States. doi:10.1063/1.3122240.
Agvaanluvsan, U., MonAme Scientific Research Center, Ulaanbaatar, Mitchell, G. E., Triangle Universities Nuclear Laboratory, Durham, NC 27708, Baramsai, B., Chyzh, A., Walker, C., Dashdorj, D., North Carolina State University, Raleigh, NC 27695, Becker, J. A., Parker, W. E., Sleaford, B., Wu, C. Y., Bredeweg, T. A., Couture, A., Haight, R. C., Jandel, M., Rundberg, R. S., Ullmann, J. L., Vieira, D. J., Wouters, J. M., Krticka, M., and Becvar, F. 2009. "Spin and Parity Assignment of Neutron Resonances using Gamma-ray Multiplicity". United States. doi:10.1063/1.3122240.
@article{osti_21293502,
title = {Spin and Parity Assignment of Neutron Resonances using Gamma-ray Multiplicity},
author = {Agvaanluvsan, U. and MonAme Scientific Research Center, Ulaanbaatar and Mitchell, G. E. and Triangle Universities Nuclear Laboratory, Durham, NC 27708 and Baramsai, B. and Chyzh, A. and Walker, C. and Dashdorj, D. and North Carolina State University, Raleigh, NC 27695 and Becker, J. A. and Parker, W. E. and Sleaford, B. and Wu, C. Y. and Bredeweg, T. A. and Couture, A. and Haight, R. C. and Jandel, M. and Rundberg, R. S. and Ullmann, J. L. and Vieira, D. J. and Wouters, J. M. and Krticka, M. and Becvar, F.},
abstractNote = {Decay gamma rays following neutron capture on various isotopes are collected by the Detector for Advanced Neutron Capture Experiments (DANCE) array, which is located at flight path 14 at the Lujan Neutron Scattering Center at Los Alamos National Laboratory. The high segmentation (160 detectors) and close packing of the detector array enable gamma-ray multiplicity measurements. The calorimetric properties of the DANCE array coupled with the neutron time-of-flight technique enables one to gate on a specific resonance of a given isotope in the time-of-flight spectrum and obtain the summed energy spectrum for that isotope. The singles gamma-ray spectrum for each multiplicity can be separated by their DANCE cluster multiplicity. The multiplicity distribution contains the signatures of spin and parity of the capture state. Under suitable circumstances where the difference between spins of the initial (capture) and final (ground) state is large enough, the signatures in the multiplicity distribution can be used in improving the spin assignment of the initial state. The spin assignment is applied with varying degree of success to difference isotopes and description of this application for {sup 95}Mo, {sup 151,153}Eu, and {sup 155,157}Gd is reviewed briefly.},
doi = {10.1063/1.3122240},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1109,
place = {United States},
year = 2009,
month = 3
}
  • The multiplicity of -ray emission following neutron capture at isolated resonances carries valuable information on the resonance spin. Several methods utilizing this information have been developed. The latest method was recently introduced for analyzing the data from time-of-flight measurements with 4 -calorimetric detection systems. The present paper describes a generalization of this method. The goal is the separation of the -emission yields belonging to the two neutron capturing state spins of isolated (or even unresolved) s-wave neutron resonances on targets with non-zero spin. The formalism for performing this separation is described and then tested on artificially generated data. This newmore » method was applied to the -multiplicity data obtained for the 147Sm(n, )148Sm reaction using the DANCE detector system at the LANSCE facility at Los Alamos National Laboratory. The analyzing power of the upgraded method is supported by combined dicebox and geant4 simulations of the fluctuation properties of the multiplicity distributions.« less
  • We have applied the low-level population method to the determination of the spins of 19 p-waves of {sup 238}U including the sample of 16 resonances studies by the TRIPLE collaboration in a search for parity violation (PV) effects. Knowing the spins, we have derived a more precise estimate of the root-mean-squared PV matrix element. M = 0.58 {sup +0.39}{sub -0.22} meV. We have also assigned the spins to 23 s-waves and 21 p-waves of {sup 113}Cd: out of this last group 3 have spin J{sup {pi}} = 0- and 10 spin J{sup {pi}} = 1-. Such a sample of 13more » resonances liable to present PV effects makes this nuclide a very interesting candidate for this type of studies.« less