Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

Total absorption gamma spectroscopy studies around 100 Sn
A. Algora,∗1,∗2 J. A. Victoria,∗1 B. Rubio,∗1 J. L. Tain,∗1 A. Tolosa,∗1 J. Agramunt,∗1 E. Nacher,∗1S. E. A. Orrigo,∗1 V. Guadilla,∗3 G. Kiss,∗2 D. Sohler,∗2 I. Kuti,∗2 T. Davinson,∗4 O. B. Hall,∗4 D. M. Kahl,∗4C. G. Bruno,∗4 C. J. Appleton,∗4 P. J. Woods,∗4 S. Nishimura,∗5 N. Fukuda,∗5 H. Suzuki,∗5 D. S. Ahn,∗5H. Baba,∗5 Y. Shimizu,∗5 H. Takeda,∗5 D. Nishimura,∗5 T. Isobe,∗5 M. Kaneko,∗5 S. Kubono,∗5 H. Sakurai,∗5H. Shimizu,∗5 T. Sumikama,∗5 P. Doornenbal,∗5 M. L. Cortes,∗6 Zs. Podolyak,∗7 W. Gelletly,∗7 E. Ganioglu,∗8Y. Fujita,∗9 F. Molina,∗10 J. Liu,∗11 J. Lee,∗11 K. P. Rykaczewski,∗12 M. Wolinska-Cichocka,∗13 M. Labiche,∗14C. J. Griﬃn,∗15 S. Bae,∗16 J. Ha,∗16 and Y. Litvinov∗17
The region around 100 Sn in the nuclide chart is considered of great interest. There are several reasons for
that: the shell structure of nuclei in the vicinity of theZ = N = 50 doubly-closed shell, the possibility of studying the heaviest accessible particle bound N = Z nucleus 100 Sn, the study of the quenching of the GamowTeller resonance1,2) and the astrophysical relevance of
decays in this region for the rapid proton-capture process (see3,4) and references therein).
Among the studied nuclei in the region, 100 Sn plays akey role. The beta decay of this nucleus and that of nuclei located south east of 100 Sn is dominated by the single particle Gamow-Teller transition of πg9/2 → νg7/2 ,which is expected to be accesible inside the Qβ windowof the decay. This can provide a clear case for studying
the origin of the quenching of the Gamow-Teller strength(B(GT)), a topic that has attracted considerable attention over many years.1,2,5,6)
For these kind of studies it is mandatory to use a technique that provides beta decay data that do not suﬀer
from the Pandemonium eﬀect.7) This is the main motivation of the NP1612-RIBF147 experiment in which weused the total absorption spectrometer DTAS8) developed for DESPEC (FAIR) for measurements in combination with the implantation detector AIDA.9)
The beta decay of 100 Sn has been previously studied using high resolution experiments at GSI and atRIKEN,10,11) showing that it has the largest B(GT)value measured in the nuclide chart. The limited statistics and the probable presence of a low-energy gamma
ray not identiﬁed in previous experiments constrain thereliability of the determination of the excitation energyof the 1+ state in 100 In, the state that should be mainly∗1IFIC, CSIC-Univ. Valencia
MTA ATOMKI∗3 SUBATECH∗4 School of Physics and Astronomy, University of Edinburgh∗5 RIKEN Nishina Center∗6 INFN-Legnaro∗7 Department of Physics, Surrey University∗8 Department of Physics, University of Istanbul∗9 Osaka University∗10 CCHEN∗11 Department of Physics, University of Hong Kong
∗12 Oak Ridge National Laboratory∗13 Heavy Ion Laboratory, Warsaw University∗14 STFC Daresbury Laboratory∗15 Physical Sciences Division, TRIUMF∗16 Dept. of Physics and Astronomy, Seoul National University∗17 GSI∗2- 30 -Fig. 1. Particle ID in BigRIPS from the experiment.

populated in the beta decay of 100 Sn. The excitationenergy of this state, as well as the β end-point energyof this transition is crucial for the determination of theB(GT) value. The high eﬃciency of DTAS and its granularity can contribute to solve this question as shown byMonte Carlo simulations. In this experiment we will
also have access to exotic decays that were not previously studied with the total absorption technique at theMass Separator (MSEP) at GSI because of the limited
production. In Fig. 1 we show the particle identiﬁcation in BigRIPS obtained during our experiment. Dueto technical problems we were able to run only 4 days
from a total of 10 approved days. The continuation ofthe experiment is expected in 2020. The analysis of thepartial set of data is on going.
References

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