Speaker
Description
The $\beta$-decay of $^{70}$Kr can be used to test the predictions of different theoretical models. First of all, the effects of $T=0$ pn-pairing can be investigated through the study of the decay rates [1]. Furthermore the theoretical strength distributions of the $\beta$-decay of $^{70}$Kr show clear differences depending on the shape of the ground state, hence assumptions on the shape of the ground state can be tested [2]. Finally $^{70}$Kr might lay on the rp-process path and accordingly its half-life might play a role in rp-process network calculations [3]. Despite its importance, the knowledge on the $\beta$-decay of this isotope is rather limited. The half-life is known only with 15% accuracy, and only one $\gamma$-transition was identified to date [4,5].
To make the tests of these models possible, we've conducted an experiment at RIKEN-RIBF. The nucleus of interest was produced using a $^{78}$Kr primary beam with a kinetic energy of 345 MeV/nucleon and intensity of about 300 pnA. The fragments were separated by BigRIPS using in-flight method, then were stopped in the WAS3ABi active silicon detector [6]. The $\beta$-delayed $\gamma$-rays were detected by the EURICA cluster array surrounding the implantation station [7].
The experiment significantly increased our knowledge on the structure of the daughter nucleus populated in the $\beta$-decay. A precise half-life value, with an uncertainty in the order of 2%, have been derived from time correlations of the $\beta$-particles and the decay-curves of the observed $\gamma$-transitions. Furthermore, after the identification of several new $\gamma$-transitions, a detailed level scheme -- including about 20 transitions -- have been derived [8]. The experimental approach, as well as the new half-life value and the level scheme, will be presented, along with an insight on the theoretical interpretations of the experimental results.
[1] A. L. Goodman, Phys. Rev. C 60, 014311 (1999)
[2] P. Sarriguren, Phys. Rev. C 83, 025801 (2011)
[3] H. Schatz, et al., Phys. Rev. Lett. 86, 3471 (2001)
[4] M. Oinonen, et al., Phys. Rev. C 61, 035801 (2000)
[5] G. de Angelis et al., Eur. Phys. J. A 12, 51 (2001)
[6] S. Nishimura, Prog. Theor. Exp. Phys. 03C006 (2012)
[7] P.-A. Söderström, et al., Nucl. Instrum. Meth. B 317, 649 (2013)
[8] A. Vitéz-Sveiczer et al., Acta Phys. Pol. B 51, 587 (2020)
| Field of your work | Experiental nuclear physics |
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