High precision half-life measurement of $$^{95}\hbox {Ru}$$ 95 Ru , $$^{95}\hbox {Tc}$$ 95 Tc and $$^{95m}\hbo
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Regular Article - Experimental Physics
High precision half-life measurement of 95 Ru, 95 Tc and 95m Tc with γ -spectroscopy T. N. Szegedi1,2 , Á. Tóth1 , G. G. Kiss2,a , Gy. Gyürky2 1 2
University of Debrecen, Debrecen 4026, Hungary Institute of Nuclear Research, Debrecen 4032, Hungary
Received: 28 April 2020 / Accepted: 26 June 2020 © The Author(s) 2020 Communicated by Anu Kankainen
Abstract The precise knowledge of the half-life of the reaction product is of crucial importance for a nuclear reaction cross section measurement carried out with the activation technique. The cross section of the 92 Mo(α,n)95 Ru reaction was measured recently using this experimental approach. The preliminary results indicated that the literature half-life of 95 Ru, derived about half a century ago, is overestimated. Therefore, the half-lives of 95 Ru and its daughter isotope 95 Tc and 95m Tc have been measured with high precision using γ -spectroscopy. The results are t1/2 = 1.6033 ± 0.0044 h for 95 Ru, t1/2 = 19.258 ± 0.026 h for 95 Tc and t1/2 = 61.96 ± 0.24 d for 95m Tc. The precision of the half-life values has been increased, consequently the recently measured 92 Mo(α,n)95 Ru activation cross section will become more precise.
1 Introduction The bulk of the isotopes heavier than iron are synthesized via neutron capture reactions in the so-called s and r processes [1, 2]. However, on the proton-rich side of the valley of stability there are – depending on the astrophysical model – 30–35 mostly even-even proton-rich species. These, so-called, pnuclei cannot be synthesized by neutron capture reactions, since they are separated by unstable short-lived nuclei from the path of both the s and r processes [3]. According to our knowledge, in the production of these isotopes, (γ ,n), (γ ,p) and (γ ,α) photodisintegration reactions play key role and the process takes place either in type IA supernovae or in Type II (core collapse) supernovae [3,4]. The astrophysical modeling of this nucleosynthesis scenario requires an extended reaction network calculation, the necessary cross sections are taken from the statistical model. a e-mail:
[email protected] (corresponding author)
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The predictions of the statistical model can be tested and its input parameters – such as optical model potentials, level densities and γ -ray strength functions – can be optimized by measuring the cross sections of charged-particle induced reactions, the inverses of the relevant photodisintegrations. Such cross section measurements are often carried out using the activation technique [5]. The application of this experimental approach requires precise information on the decay properties of the reaction product(s). Accordingly, the halflife (t1/2 ) of the resulted isotope and the intensities of the γ -rays emitted after the β-decay have to be known to derive the number of created reaction product nuclei. To constrain the parameters of the α-nucleus optical potential, a new measurement for the 92 Mo(α,n)95 Ru reaction cross section is in prog
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