Phys. Rev. C 103, 034601 (2021) - Investigating high-energy proton-induced reactions on spherical nuclei: Implications for the preequilibrium exciton model

Investigating high-energy proton-induced reactions on spherical nuclei: Implications for the preequilibrium exciton model

Morgan B. Fox, Andrew S. Voyles, Jonathan T. Morrell, Lee A. Bernstein, Amanda M. Lewis, Arjan J. Koning, Jon C. Batchelder, Eva R. Birnbaum, Cathy S. Cutler, Dmitri G. Medvedev, Francois M. Nortier, Ellen M. O'Brien, and Christiaan Vermeulen

Phys. Rev. C 103, 034601 – Published 1 March 2021

Abstract

Background: A number of accelerator-based isotope production facilities utilize 100- to 200-MeV proton beams due to the high production rates enabled by high-intensity beam capabilities and the greater diversity of isotope production brought on by the long range of high-energy protons. However, nuclear reaction modeling at these energies can be challenging because of the interplay between different reaction modes and a lack of existing guiding cross-section data.

Purpose: A Tri-lab collaboration has been formed among the Lawrence Berkeley, Los Alamos, and Brookhaven National Laboratories to address these complexities by characterizing charged-particle nuclear reactions relevant to the production of established and novel radioisotopes.

Method: In the inaugural collaboration experiments, stacked-targets of niobium foils were irradiated at the Brookhaven Linac Isotope Producer ( $E_{p} = 200 MeV$ ) and the Los Alamos Isotope Production Facility ( $E_{p} = 100 MeV$ ) to measure ${}^{93}{Nb} (p, x)$ cross sections between 50 and 200 MeV. First measurements of the ${}^{93}{Nb} (p, 4 n) {}^{90}{Mo}$ beam monitor reaction beyond 100 MeV are reported in this work, as part of the broadest energy-spanning dataset for the reaction to date. ${}^{93}{Nb} (p, x)$ production cross sections are additionally reported for 22 other measured residual products. The measured cross-section results were compared with literature data as well as the default calculations of the nuclear model codes TALYS, CoH, EMPIRE, and ALICE.

Results: The default code predictions largely failed to reproduce the measurements, with consistent underestimation of the preequilibrium emission. Therefore, we developed a standardized procedure that determines the reaction model parameters that best reproduce the most prominent reaction channels in a physically justifiable manner. The primary focus of the procedure was to determine the best parametrization for the preequilibrium two-component exciton model via a comparison to the energy-dependent ${}^{93}{Nb} (p, x)$ data, as well as previously published ${}^{139}{La} (p, x)$ cross sections.

Conclusions: This modeling study revealed a trend toward a relative decrease for internal transition rates at intermediate proton energies ( $E_{p} = 20$ –60 MeV) in the current exciton model as compared to the default values. The results of this work are instrumental for the planning, execution, and analysis essential to isotope production.

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Received 14 October 2020
Accepted 16 December 2020

DOI:https://doi.org/10.1103/PhysRevC.103.034601

Physics Subject Headings (PhySH)

H & He induced nuclear reactions Models & methods for nuclear reactions Nuclear reactions Nucleon induced nuclear reactions

Nuclear data analysis & compilation

Nuclear Physics

Authors & Affiliations

Morgan B. Fox ^1,*, Andrew S. Voyles ^1,2,†, Jonathan T. Morrell ¹, Lee A. Bernstein ^1,2, Amanda M. Lewis ¹, Arjan J. Koning ³, Jon C. Batchelder¹, Eva R. Birnbaum⁴, Cathy S. Cutler⁵, Dmitri G. Medvedev ⁵, Francois M. Nortier⁴, Ellen M. O'Brien ⁴, and Christiaan Vermeulen ⁴

¹Department of Nuclear Engineering, University of California, Berkeley, Berkeley, California 94720, USA
²Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
³International Atomic Energy Agency, P. O. Box 100, A-1400 Vienna, Austria
⁴Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
⁵Brookhaven National Laboratory, Upton, New York 11973, USA

^*morganbfox@berkeley.edu
^†asvoyles@lbl.gov

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Vol. 103, Iss. 3 — March 2021

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Physical Review C

covering nuclear physics

Investigating high-energy proton-induced reactions on spherical nuclei: Implications for the preequilibrium exciton model

Morgan B. Fox, Andrew S. Voyles, Jonathan T. Morrell, Lee A. Bernstein, Amanda M. Lewis, Arjan J. Koning, Jon C. Batchelder, Eva R. Birnbaum, Cathy S. Cutler, Dmitri G. Medvedev, Francois M. Nortier, Ellen M. O'Brien, and Christiaan Vermeulen

Phys. Rev. C 103, 034601 – Published 1 March 2021

Abstract

Physics Subject Headings (PhySH)

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Article Text (Subscription Required)

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Physical Review C

covering nuclear physics

Investigating high-energy proton-induced reactions on spherical nuclei: Implications for the preequilibrium exciton model

Morgan B. Fox, Andrew S. Voyles, Jonathan T. Morrell, Lee A. Bernstein, Amanda M. Lewis, Arjan J. Koning, Jon C. Batchelder, Eva R. Birnbaum, Cathy S. Cutler, Dmitri G. Medvedev, Francois M. Nortier, Ellen M. O'Brien, and Christiaan Vermeulen

Phys. Rev. C 103, 034601 – Published 1 March 2021

Abstract

Physics Subject Headings (PhySH)

Authors & Affiliations

Article Text (Subscription Required)

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