II-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 54 (2021)

RIKEN Accel. Prog. Rep. 54 (2021)

Total absorption γ-spectroscopy study of the beta decay of 100 Sn
J. A. Victoria,∗1 A. Algora,∗1,∗2 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∗17Fig. 1. Parameters employed in the deﬁnition of the ﬁgureof merit for the time distribution of the β particles. Thearea S stands for signal, B for background, b is the highof the background. B is estimated using the backward
correlation time interval [−ts , 0]. Tib stands for implantβ time.
∗1IFIC, CSIC-Univ. of Valencia
MTA ATOMKI∗3 Subatech/Ecole des Mines, CNRS/IN2P3, Université deNantes∗4 School of Physics and Astronomy, University of Edinburgh∗5 RIKEN Nishina Center∗6 INFN Laboratori Nazionali di Legnaro∗7 Department of Physics, Surrey University∗8 Department of Physics, University of Istanbul∗9 Department of Physics, Osaka University∗10 Comisión Chilena de Energía Nuclear (CCHEN)∗11 Department of Physics, University of Hong Kong
∗12 Physics Division, 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 Helmholtzzentrum für Schwerionenforschung GmbH
∗2300Counts

In this report we are presenting the progress on theanalysis of the NP1612-RIBF147 experiment. The goalof this experiment was to study the beta decay of 100 Sn
and neighbouring nuclei using the total absorption technique. In our measurement the total absorption spectrometer DTAS1) was used in combination with the implantation detector AIDA.2) Details of the experimentcan be found in Ref. 3).
One key aspect of the work performed was to improve
the signal to background ratio of the coincident data asmuch as possible. The sorting conditions of the data
and the number of parameters available for the analysis
makes this task daunting without proper quantiﬁcationof the code optimisations. For that reason we introduced
a ﬁgure of merit. The ﬁgure quantiﬁes the improvements

250
200
150
100
50
0−2−1.5−1−0.5

00.5

11.52Time beta - Time implants [s]Fig. 2. Time distribution of the β particles emitted after thedecay of 100 Sn in coincidence with DTAS.

made by the changes in the analysis code looking for thereduction of the accidental correlations associated to thedecay of 100 Sn. In our study we changed several sorting parameters and compared the area of the true correlations (S) with the area of the background (B) (seeFig. 1. for an schematic view). The optimisation consisted in looking for conditions that increase the S to B
ratio. Note that the correlation time window (ts ) is related to the decay half-life of the implanted nucleus ofinterest. Some improvements on the AIDA sorting code
were also necessary.4)
In Fig. 2 we show the present status of the implant-βtime correlation (gated with the condition on the DTASﬁring) after implementing all cleaning conditions for the100Sn. Thanks to the procedures applied, an increaseof the signal to background ratio of the order of 20%
was achieved, improving the DTAS gamma correlated
data. In the near future we will reﬁne the calibrationof the detectors and calculate the response function ofthe setup, which is mandatory for the total absorption
spectrum analysis. Due to technical problems during ourrun we were only able to take data for 4 days from a totalof 10 approved days. The continuation of the experimentis expected to occur in 2021.
References

1) J. L. Tain et al., Nucl. Instrum. Methods Phys. Res. A
803, 36 (2015).
2) C. J. Griﬃn et al., Proc. XIII Nuclei in the Cosmos 1., 97(2014).
3) A. Algora et al., RIKEN Accel. Prog. Rep. 53, 30 (2019).
4) O. B. Hall, private communication.

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