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Title: Near-barrier photofission in Th 232 and U 238

Abstract

Here a study of photofission of $$^{232}\mathrm{Th}$$ and $$^{238}\mathrm{U}$$ was performed by using quasimonoenergetic, linearly polarized $${\gamma}$$-ray beams from the High Intensity $${\gamma}$$-ray Source at Triangle Universities Nuclear Laboratory. The prompt-photofission neutron polarization asymmetries, neutron multiplicities, and the photofission cross sections were measured in the near-barrier energy range of 4.3 to 6.0 MeV. This data set constitutes the lowest energy measurements of those observables to date using quasimonoenergetic photons. Large polarization asymmetries are observed in both nuclei, consistent with the $E1$ excitation as observed by another measurement of this kind made in a higher-energy range. Previous experimental evidence of a deep third minimum in the $$^{238}\mathrm{U}$$ fission barrier has been identified as an accelerator-induced background.

Authors:
 [1];  [2]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Nuclear and Chemical Sciences Division; Triangle Universities Nuclear Lab., Durham, NC (United States); Univ. of North Carolina, Chapel Hill, NC (United States). Dept. of Physics and Astronomy
  2. Triangle Universities Nuclear Lab., Durham, NC (United States); Univ. of North Carolina, Chapel Hill, NC (United States). Dept. of Physics and Astronomy
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Universities Nuclear Lab., Durham, NC (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
OSTI Identifier:
1489469
Alternate Identifier(s):
OSTI ID: 1482760
Report Number(s):
LLNL-JRNL-754505
Journal ID: ISSN 2469-9985; 941284
Grant/Contract Number:  
AC52-07NA27344; FG02-97ER41033; FG02-97ER41041
Resource Type:
Accepted Manuscript
Journal Name:
Physical Review C
Additional Journal Information:
Journal Volume: 98; Journal Issue: 5; Journal ID: ISSN 2469-9985
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; fission; photonuclear reactions; polarization phenomena

Citation Formats

Silano, J. A., and Karwowski, H. J. Near-barrier photofission in Th232 and U238. United States: N. p., 2018. Web. doi:10.1103/PhysRevC.98.054609.
Silano, J. A., & Karwowski, H. J. Near-barrier photofission in Th232 and U238. United States. doi:10.1103/PhysRevC.98.054609.
Silano, J. A., and Karwowski, H. J. Mon . "Near-barrier photofission in Th232 and U238". United States. doi:10.1103/PhysRevC.98.054609. https://www.osti.gov/servlets/purl/1489469.
@article{osti_1489469,
title = {Near-barrier photofission in Th232 and U238},
author = {Silano, J. A. and Karwowski, H. J.},
abstractNote = {Here a study of photofission of $^{232}\mathrm{Th}$ and $^{238}\mathrm{U}$ was performed by using quasimonoenergetic, linearly polarized ${\gamma}$-ray beams from the High Intensity ${\gamma}$-ray Source at Triangle Universities Nuclear Laboratory. The prompt-photofission neutron polarization asymmetries, neutron multiplicities, and the photofission cross sections were measured in the near-barrier energy range of 4.3 to 6.0 MeV. This data set constitutes the lowest energy measurements of those observables to date using quasimonoenergetic photons. Large polarization asymmetries are observed in both nuclei, consistent with the $E1$ excitation as observed by another measurement of this kind made in a higher-energy range. Previous experimental evidence of a deep third minimum in the $^{238}\mathrm{U}$ fission barrier has been identified as an accelerator-induced background.},
doi = {10.1103/PhysRevC.98.054609},
journal = {Physical Review C},
number = 5,
volume = 98,
place = {United States},
year = {2018},
month = {11}
}

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Works referenced in this record:

Intermediate structure in the photoneutron and photofission cross sections in 238U and 232Th
journal, May 1972


Giant resonance for the actinide nuclei: Photoneutron and photofission cross sections for U 235 , U 236 , U 238 , and Th 232
journal, April 1980


Photofission cross sections of 232Th and 236U from threshold to 8 MeV
journal, May 1973


High resolution fission probabilities for 229, 230, 232Th(d pf) and 233, 236U(d, pf) reactions
journal, February 1988


Photofission of 232Th near threshold
journal, October 1986


EMPIRE: Nuclear Reaction Model Code System for Data Evaluation
journal, December 2007


On the existence of triple-humped fission barriers in 231,233Th
journal, February 1984


Photofission of 232Th, 282U and 235U near threshold using a variable energy beam of γ-rays
journal, January 1972


Photofission cross sections of 238U and 235U from 5.0 MeV to 8.0 MeV
journal, September 1973


Photon flux monitor for a mono-energetic gamma ray source
journal, July 2009

  • Pywell, R. E.; Mavrichi, O.; Wurtz, W. A.
  • Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 606, Issue 3
  • DOI: 10.1016/j.nima.2009.04.014

Results on the cross-section of238U-fission induced by low-energy monoenergetic γ-rays
journal, July 1966

  • Manfredini, A.; Muchnik, M.; Fiore, L.
  • Il Nuovo Cimento B Series 10, Vol. 44, Issue 1
  • DOI: 10.1007/BF02710442

Characterization of an INVS model IV neutron counter for high precision () cross-section measurements
journal, August 2011

  • Arnold, C. W.; Clegg, T. B.; Karwowski, H. J.
  • Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 647, Issue 1
  • DOI: 10.1016/j.nima.2011.01.177

Exploring the multihumped fission barrier of 238 U via sub-barrier photofission
journal, April 2013


Perspectives for photofission studies with highly brilliant, monochromatic γ –ray beams
journal, January 2012


Fragment kinetic energies in MeV neutron-induced fission of 232Th
journal, August 1971


Resonant tunneling through the triple-humped fission barrier of 236U
journal, June 2005


A study of the differential cross section in subbarrier photofission of238U
journal, December 1978

  • Lindgren, L. J.; Sandell, A.
  • Zeitschrift für Physik A Atoms and Nuclei, Vol. 285, Issue 4
  • DOI: 10.1007/BF01813242

Analysis of the cross section for 232Th photofission in the subbarrier energy region
journal, June 2009


Investigation of the fission fragment properties of the reaction 238U(n,f) at incident neutron energies up to 5.8 MeV
journal, January 2000


Event identification in 3He proportional counters using risetime discrimination
journal, July 2013

  • Langford, T. J.; Bass, C. D.; Beise, E. J.
  • Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 717, p. 51-57
  • DOI: 10.1016/j.nima.2013.03.062

ENDF/B-VII.1 Nuclear Data for Science and Technology: Cross Sections, Covariances, Fission Product Yields and Decay Data
journal, December 2011


Eight-dimensional calculations of the third barrier in 232 Th
journal, April 2013


Subbarrier Fission Resonances in Th Isotopes
journal, June 1972


Experimental Determination of Photofission Neutron Multiplicities for 235 U, 236 U, 238 U, and 232 Th Using Monoenergetic Photons
journal, February 1980

  • Caldwell, J. T.; Dowdy, E. J.; Alvarez, R. A.
  • Nuclear Science and Engineering, Vol. 73, Issue 2
  • DOI: 10.13182/NSE80-A18695

A high-resolution measurement of the photofission spectrum of 232Th near threshold
journal, October 1982


Calculation of fission observables through event-by-event simulation
journal, August 2009


Prompt neutron polarization asymmetries in photofission of Th 232 , U 233 , 235 , 238 , Np 237 , and Pu 239 , 240
journal, March 2014


The TUNL-FELL inverse Compton γ-ray source as a nuclear physics facility
journal, August 1996

  • Scott Carman, T.; Litveninko, Vladimir; Madey, John
  • Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 378, Issue 1-2
  • DOI: 10.1016/0168-9002(95)01486-1

The double-humped fission barrier
journal, October 1980


First measurement of the near-threshold 2 H ( γ , n ) p analyzing power using a free-electron laser based γ -ray source
journal, May 2000


Measurement of prompt neutron polarization asymmetries in photofission of 235 , 238 U, 239 Pu, and 232 Th
journal, January 2012


A third minimum in the fission barrier
journal, October 1989


Third minima in thorium and uranium isotopes in a self-consistent theory
journal, May 2013


Multidimensionally constrained relativistic mean-field study of triple-humped barriers in actinides
journal, January 2015


Photofission cross section of Th 232
journal, October 1986


On the excitation energy of the ground state in the third minimum of U
journal, August 1999


Geant4—a simulation toolkit
journal, July 2003

  • Agostinelli, S.; Allison, J.; Amako, K.
  • Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 506, Issue 3
  • DOI: 10.1016/S0168-9002(03)01368-8

Hyperdeformed sub-barrier fission resonances observed in U 232
journal, July 2009


Distribution of spacings of nuclear energy levels of mixed spin and parity
journal, June 1967


Very low energy photofission of U 238
journal, September 1975


Distributions of Fission Neutron Numbers
journal, November 1957


Subthreshold photofission of U 235 and Th 232
journal, March 1978


Research opportunities at the upgraded HIγS facility
journal, January 2009

  • Weller, Henry R.; Ahmed, Mohammad W.; Gao, Haiyan
  • Progress in Particle and Nuclear Physics, Vol. 62, Issue 1
  • DOI: 10.1016/j.ppnp.2008.07.001

Polarization Measurements on Nuclear Gamma Rays
journal, July 1959


Low-energy photodisintegration of the deuteron and Big-Bang nucleosynthesis
journal, November 2003


U 238 and Th 232 Photofission and Photoneutron Emission near Threshold
journal, August 1975