<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mmultiscripts><mml:mi>Tm</mml:mi><mml:mprescripts/><mml:none/><mml:mn>169</mml:mn></mml:mmultiscripts><mml:mo>(</mml:mo><mml:mi>n</mml:mi><mml:mo>,</mml:mo><mml:mi>γ</mml:mi><mml
Radiative neutron capture on thulium, which is a monoisotopic element, plays a role in different applications such as nuclear astrophysics or nuclear burning environments. Considerable discrepancies—reaching 20%—exist between evaluations in the unresolved-resonance region. Furthermore, experimental data on statistical <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mi>γ</a:mi></a:math> decay in odd-odd rare-earth nuclei is scarce. There are still open questions about the systematics of the so-called scissors mode in the <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:mrow><b:mi>M</b:mi><b:mn>1</b:mn></b:mrow></b:math> photon strength function, especially in odd-odd nuclei. This work is focused on two main topics—deriving experimental <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"><c:mrow><c:mmultiscripts><c:mi>Tm</c:mi><c:mprescripts/><c:none/><c:mn>169</c:mn></c:mmultiscripts><c:mo>(</c:mo><c:mi>n</c:mi><c:mo>,</c:mo><c:mi>γ</c:mi><c:mo>)</c:mo></c:mrow></c:math> cross section and studying statistical <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"><d:mi>γ</d:mi></d:math> decay of <e:math xmlns:e="http://www.w3.org/1998/Math/MathML"><e:mmultiscripts><e:mi>Tm</e:mi><e:mprescripts/><e:none/><e:mn>170</e:mn></e:mmultiscripts></e:math>, in particular properties of the scissors mode. The capture experiments to obtain experimental cross section were performed at the Los Alamos Neutron Science Center using the time-of-flight technique and employing the Detector for Advanced Neutron Capture Experiments. Measured coincident <f:math xmlns:f="http://www.w3.org/1998/Math/MathML"><f:mi>γ</f:mi></f:math>-ray spectra were also compared with statistical simulations using the code to test different models of level density and photon strength functions. The capture cross section was determined from 1.8 eV to 0.97 MeV, the broadest neutron-energy range ever measured for this isotope. Several new resonances have been observed. The statistical <g:math xmlns:g="http://www.w3.org/1998/Math/MathML"><g:mi>γ</g:mi></g:math> decay of <h:math xmlns:h="http://www.w3.org/1998/Math/MathML"><h:mmultiscripts><h:mi>Tm</h:mi><h:mprescripts/><h:none/><h:mn>170</h:mn></h:mmultiscripts></h:math> cannot be reproduced without a scissors mode resonance centered at <i:math xmlns:i="http://www.w3.org/1998/Math/MathML"><i:mrow><i:mo>≈</i:mo><i:mn>3.3</i:mn><i:mspace width="0.28em"/><i:mi>MeV</i:mi></i:mrow></i:math>. The measured cross section in the unresolved-resonance region is generally lower than the latest evaluations. The derived <k:math xmlns:k="http://www.w3.org/1998/Math/MathML"><k:mmultiscripts><k:mi>Tm</k:mi><k:mprescripts/><k:none/><k:mn>169</k:mn></k:mmultiscripts><k:mo> </k:mo><k:mi>s</k:mi></k:math>-process abundance is expected to increase by a factor of 1.26, while the changes of the abundances of elements heavier than <l:math xmlns:l="http://www.w3.org/1998/Math/MathML"><l:mmultiscripts><l:mi>Tm</l:mi><l:mprescripts/><l:none/><l:mn>169</l:mn></l:mmultiscripts></l:math> are in the order of 0.2%. The scissors mode properties in <m:math xmlns:m="http://www.w3.org/1998/Math/MathML"><m:mmultiscripts><m:mi>Tm</m:mi><m:mprescripts/><m:none/><m:mn>170</m:mn></m:mmultiscripts></m:math> are similar to those deduced in previous analyses of neighboring nuclei <n:math xmlns:n="http://www.w3.org/1998/Math/MathML"><n:mmultiscripts><n:mi>Er</n:mi><n:mprescripts/><n:none/><n:mn>168</n:mn></n:mmultiscripts></n:math> and <o:math xmlns:o="http://www.w3.org/1998/Math/MathML"><o:mmultiscripts><o:mi>Ho</o:mi><o:mprescripts/><o:none/><o:mn>166</o:mn></o:mmultiscripts></o:math>.
Authors
- C. Fry (ORCID: https://orcid.org/0000-0002-8342-601X)
- R. Reifarth (ORCID: https://orcid.org/0000-0002-3855-5816)
- Keegan Kelly (ORCID: https://orcid.org/0000-0002-2845-9644)
- C. J. Prokop (ORCID: https://orcid.org/0000-0001-9641-8070)
- S. Valenta (ORCID: https://orcid.org/0000-0003-2479-1380)
- Esther Leal Cidoncha (ORCID: https://orcid.org/0000-0002-7030-4259)
- J. L. Ullmann (ORCID: https://orcid.org/0000-0002-0778-4405)
- Toshihiko Kawano (ORCID: https://orcid.org/0000-0001-7463-4899)
- M. Krtička (ORCID: https://orcid.org/0000-0002-0083-8327)
- A. Couture (ORCID: https://orcid.org/0000-0002-0861-3616)
- G. Rusev (ORCID: https://orcid.org/0000-0001-7563-1518)
- F. Gunsing (ORCID: https://orcid.org/0000-0002-6582-3855)
- K. Horčičková (ORCID: https://orcid.org/0009-0001-6750-3572)
- Karl J. Friston
Institutions
- Los Alamos National Laboratory (US)
- Charles University (CZ)
- Commissariat à l'Énergie Atomique et aux Énergies Alternatives (FR)
- Université Paris-Saclay (FR)
- CEA Paris-Saclay (FR)
- Institut de Recherche sur les Lois Fondamentales de l'Univers (FR)
Publication Details
- Journal
- Physical review. C
- Published
- 2025-05-28
- DOI
- https://doi.org/10.1103/5sjr-vyjv
- Citations
- 2
- Primary Topic
- Particle physics theoretical and experimental studies
- Type
- article
- Field-Weighted Citation Impact
- 3.74