Speaker
Description
P. E. Koehler1, A. Stamatopoulos1, E. Bond2, T. A. Bredeweg2, A. Couture1, B. DiGiovine1, M. E. Fassbender2, A. C. Hayes-Sterbenz3, G. Keksis2, A. Matyskin2, K. Parsons4, G. Rusev2, J. Ullmann1, C. Vermeulen2
- Physics division, Los Alamos National Laboratory, 87545, NM, USA
- Chemistry division, Los Alamos National Laboratory, 87545, NM, USA
- Theory Division, Los Alamos National Laboratory, 87545, NM, USA
- X-Computational Physics division, Los Alamos National Laboratory, 87545, NM, USA
Combined measurement and analysis of neutron total and capture cross sections results in more accurate cross sections and resonance parameters for applications and for testing and improving theory. The results are even more valuable when the apparatus is capable of enhanced resonance spin and parity determination. Furthermore, the ability to make these measurements on very small samples extends the capability to a wider range of nuclides. The new Device for Indirect Capture Experiments on Radionuclides (DICER) [1] at the Los Alamos Neutron Science Center (LANSCE) is being developed to make neutron transmission measurements on very samples. The current 1-mm-diameter collimation system typically requires samples in the mg range although samples as small as about 1 g are possible in exceptional circumstances. Typical neutron transmission measurements requires samples in the grams to tens of grams or more range. DICER will soon be upgraded to a 0.1-mm-diameter collimation system, allowing routine measurements on samples in the 100 g range. DICER features a unique, innovative binocular collimator system which enables simultaneous sample-in and sample-out measurements, thereby minimizing both the sample size and measurement time. The Detector for Advanced Neutron Capture Experiments (DANCE) at LANSCE has for years measured neutron capture cross sections for samples in the mg range. DANCE also has been shown to be an excellent neutron resonance “spin meter” [3, 4]. In addition to spin and parity, each neutron resonance has both a neutron and a gamma width; hence, both neutron capture and total cross sections are needed to fully determine all the parameters for as many resonances as possible. Because they have a wider range of resonance spins as well as typically large cross sections, odd-A nuclides in particular represent a fertile testing ground [3, 5] for theory as well as a challenge for applications [6, 7]. The combined power of DICER and DANCE will be demonstrated via new data and combined resonance analysis on 147,149Sm and 191,193Ir.
[1] A. Stamatopoulos et al., submitted to Nucl. Instrum. Meth. A (2021).
[2[ A. Stamatopoulos et al., submitted to this conference.
[3] P. E. Koehler et al., Phys. Rev. Lett. 108, 142502 (2012).
[4] S. A. Sheets et al., Phys. Rev. C 76, 064317 (2007).
[5] P. E. Koehler et al., in Compound-Nuclear Reactions, CNR*18, editedby J. Escher, Y. Alhassid, L. A. Bernstein, D. Brown, C. Frohlich, P. Talou, and W. Younes (Springer 2021) p. 187.
[5] L. C. Leal, H. Derrien, M. E. Dunn, and D. E. Mueller, “Assessment of Fission Product Cross-Section Data for Burnup Credit Applications”, ORNL/TM-2005/65.
[6] N. Leclaire, I. Duhamel, and M. Monestier, in Criticality safety – Pushing Boundaries by modernizing and Integration Data, Methods, and Regulations, edited by C. Associates (American Nuclear Society, 2017), p. 15.