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Title: Nuclear Resonance Fluorescence Excitations Near 2 MeV in 235U and 239Pu

Abstract

A search for nuclear resonance fluorescence excitations in {sup 235}U and {sup 239}Pu within the energy range of 1.0- to 2.5-MeV was performed using a 4-MeV continuous bremsstrahlung source at the High Voltage Research Laboratory at the Massachusetts Institute of Technology. Measurements utilizing high purity Ge detectors at backward angles identified 9 photopeaks in {sup 235}U and 12 photopeaks in {sup 239}Pu in this energy range. These resonances provide unique signatures that allow the materials to be non-intrusively detected in a variety of environments including fuel cells, waste drums, vehicles and containers. The presence and properties of these states may prove useful in understanding the mechanisms for mixing low-lying collective dipole excitations with other states at low excitations in heavy nuclei.

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
943829
Report Number(s):
UCRL-JRNL-227017
TRN: US200902%%435
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review C, vol. 78, no. 4, October 8, 2008, pp. 041601; Journal Volume: 78; Journal Issue: 4
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; BREMSSTRAHLUNG; CONTAINERS; DIPOLES; ENERGY RANGE; FUEL CELLS; HEAVY NUCLEI; HIGH-PURITY GE DETECTORS; RESONANCE FLUORESCENCE; WASTES

Citation Formats

Bertozzi, W, Caggiano, J A, Hensley, W K, Johnson, M S, Korbly, S E, Ledoux, R J, McNabb, D P, Norman, E B, Park, W H, and Warren, G A. Nuclear Resonance Fluorescence Excitations Near 2 MeV in 235U and 239Pu. United States: N. p., 2006. Web.
Bertozzi, W, Caggiano, J A, Hensley, W K, Johnson, M S, Korbly, S E, Ledoux, R J, McNabb, D P, Norman, E B, Park, W H, & Warren, G A. Nuclear Resonance Fluorescence Excitations Near 2 MeV in 235U and 239Pu. United States.
Bertozzi, W, Caggiano, J A, Hensley, W K, Johnson, M S, Korbly, S E, Ledoux, R J, McNabb, D P, Norman, E B, Park, W H, and Warren, G A. Wed . "Nuclear Resonance Fluorescence Excitations Near 2 MeV in 235U and 239Pu". United States. doi:. https://www.osti.gov/servlets/purl/943829.
@article{osti_943829,
title = {Nuclear Resonance Fluorescence Excitations Near 2 MeV in 235U and 239Pu},
author = {Bertozzi, W and Caggiano, J A and Hensley, W K and Johnson, M S and Korbly, S E and Ledoux, R J and McNabb, D P and Norman, E B and Park, W H and Warren, G A},
abstractNote = {A search for nuclear resonance fluorescence excitations in {sup 235}U and {sup 239}Pu within the energy range of 1.0- to 2.5-MeV was performed using a 4-MeV continuous bremsstrahlung source at the High Voltage Research Laboratory at the Massachusetts Institute of Technology. Measurements utilizing high purity Ge detectors at backward angles identified 9 photopeaks in {sup 235}U and 12 photopeaks in {sup 239}Pu in this energy range. These resonances provide unique signatures that allow the materials to be non-intrusively detected in a variety of environments including fuel cells, waste drums, vehicles and containers. The presence and properties of these states may prove useful in understanding the mechanisms for mixing low-lying collective dipole excitations with other states at low excitations in heavy nuclei.},
doi = {},
journal = {Physical Review C, vol. 78, no. 4, October 8, 2008, pp. 041601},
number = 4,
volume = 78,
place = {United States},
year = {Wed Dec 27 00:00:00 EST 2006},
month = {Wed Dec 27 00:00:00 EST 2006}
}
  • A search for nuclear resonance fluorescence excitations in {sup 235}U and {sup 239}Pu within the energy range of 1.0- to 2.5-MeV was performed using a 4-MeV continuous bremsstrahlung source at the High Voltage Research Laboratory at the Massachusetts Institute of Technology. Measurements utilizing high purity Ge detectors at backward angles identified nine photopeaks in {sup 235}U and 12 photopeaks in {sup 239}Pu in this energy range. These resonances provide unique signatures that allow the materials to be nonintrusively detected in a variety of environments including fuel cells, waste drums, vehicles, and containers. The presence and properties of these states maymore » prove useful in understanding the mechanisms for mixing low-lying collective dipole excitations with other states at low excitations in heavy nuclei.« less
  • Nuclear resonance fluorescence is a physical process that provides an isotope-specific signature that could be used for the identification and characterization of materials. The technique involves the detection of prompt discrete-energy photons emitted from a sample that is exposed to MeV-energy photons. Potential applications of the technique range from detection of high explosives to characterization of special nuclear materials such as 235U. Pacific Northwest National Laboratory and Passport Systems have collaborated to conduct a pair of measurements to search for a nuclear resonance fluorescence response of 235U above 3 MeV and of 238U above 5 MeV using an 8 gmore » sample of highly enriched uranium and a 90 g sample of depleted uranium. No new signatures were observed. The minimum detectable integrated cross section for 235U is presented.« less
  • A search for nuclear resonance fluorescence excitations in U and Pu within the energy range of 1.0- to 2.5-MeV was performed using a 4-MeV, continuous, bremsstrahlung source at the High Voltage Research Laboratory at the Massachusetts Institute of Technology. Measurements utilizing high purity Ge detectors at back angles identified 9 photopeaks in U-235 and 13 photopeaks in Pu-239 in this energy range, most likely dipole excitations. These resonances provide unique signatures that allow the materials to be non-intrusively detected in a variety of environments including fuel cells, waste drums, vehicles and containers. The presence and properties of these states maymore » prove useful in understanding the nuclear structure of even - odd nuclei.« less
  • Investigations of the space parity nonconserving (PNC) asymmetry of 233U, 235U, and 239Pu fission fragment emission and parity conserving (PC) interference effects of left-right and forward-backward asymmetries were carried out on the neutron beams of the reactor IBR-30 (JINR, Dubna) over the range of neutron energies from 0.02 eV to about 100 eV. All experimental results obtained have been found to be in a good mutual accordance within the frames of modern theoretical conceptions about the mechanisms of PNC and PC effects forming in fission process induced by slow neutrons. In case of the P-even interference effects of asymmetry themore » evident mutual well-marked irregularities in their neutron energy dependencies up to about 100 eV were observed. It is connected with the interference of s, p-resonances at fission compound stage according to modern theory. As a remarkable result of the PNC effect measurements the resonance behavior of the PNC asymmetry coefficients in the low neutron energy region (En < 2 eV) was observed. Unfortunately, the statistical accuracy of the PNC effect measurements is not enough for observation of these resonance effects in other cases of more high energies. Results of simultaneous analysis of all three asymmetry effects for all three nuclei are presented. The satisfactory combined description of the experimental points is received. As a result of theoretical evaluation of these data main parameters and the estimates of nuclear matrix elements of the weak interaction for some p-resonances in the low energy range were extracted.« less
  • Abstract–Nuclear resonance fluorescence is a physical process that provides an isotope-specific signature that could be used for the identification and characterization of materials. The technique involves the detection of prompt discrete-energy photons emitted from a sample that is exposed to photons in the MeV energy range. Potential applications of the technique range from detection of high explosives to characterization of special nuclear materials such as 235U. Pacific Northwest National Laboratory and Passport Systems have collaborated to conduct a a pair of measurements to search for a nuclear resonance fluorescence response of 235U above 3 MeV and of 238U above 5more » MeV using an 8 g sample of highly enriched uranium and a 90 g sample of depleted uranium. No new signatures were observed. The minimum detectable integrated cross section for 235U is presented.« less