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Study of Astrophysical s-Process Neutron Capture Reactions at the High-Intensity SARAF-LiLiT Neutron Source.
- Source :
- EPJ Web of Conferences; 4/6/2020, Vol. 232, p1-6, 6p
- Publication Year :
- 2020
-
Abstract
- We report on recent experiments at the Soreq Applied Research Accelerator Facility Liquid-Lithium Target (SARAF-LiLiT) laboratory dedicated to the study of s-process neutron capture reactions. The kW-power proton beam at 1.92 MeV (1-2 mA) from SARAF Phase I yields high-intensity 30 keV quasi-Maxwellian neutrons (3-5×10<superscript>10</superscript> n/s). The high neutron intensity enables Maxwellian averaged cross sections (MACS) measurements of low-abundance or radioactive targets. Neutron capture reactions on the important s-process branching points <superscript>147</superscript>Pm and <superscript>171</superscript>Tm were investigated by activation in the LiLiT neutron beam and γ-measurements of their decay products. MACS values at 30 keV extracted from the experimental spectrum-averaged cross sections are obtained and will be discussed. The Kr region, at the border between the so-called weak and strong s-process was also investigated. Atom Trap Trace Analysis (ATTA) was used for the first time for the measurement of a nuclear reaction cross section. After activation in the quasi-Maxwellian neutron flux at SARAF-LiLiT, isotopic ratios were determined for <superscript>81</superscript>Kr(230 ky)/<superscript>80</superscript>Kr and <superscript>85g</superscript>Kr(10.8 y)/<superscript>84</superscript>Kr. The latter ratio was confirmed both by low-level β counting and γ spectrometry. The shorter-lived capture products <superscript>79,85m,87</superscript>Kr were detected by γ -spectrometry and the corresponding neutron-capture MACS of the respective target nuclei <superscript>78,84,86</superscript>Kr were determined. The MACS of the <superscript>80</superscript>Kr(n, γ)<superscript>81</superscript>Kr and <superscript>84</superscript>Kr(n, γ)<superscript>85g</superscript>Kr reactions are still under study. The partial MACS leading to <superscript>85m</superscript>Kr(4.5 h) measured in this experiment has interesting implications since this state decays preferentially by γ decay (79%) to <superscript>85</superscript>Rb on a faster time scale than does <superscript>85g</superscript>Kr and behaves thus as an s-process branching point. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 21016275
- Volume :
- 232
- Database :
- Complementary Index
- Journal :
- EPJ Web of Conferences
- Publication Type :
- Conference
- Accession number :
- 142850389
- Full Text :
- https://doi.org/10.1051/epjconf/202023201003