Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Beta-delayed proton emission in the decay of 71 Kr
A. Vitéz-Sveiczer,∗1,∗2,∗3 A. Algora,∗1,∗2 G. Kiss,∗2,∗4 B. Rubio,∗1 A. Morales,∗1 P. Sarriguren,∗5 P. Van Isacker,∗6G. de Angelis,∗7 F. Recchia,∗8,∗9 S. Nishimura,∗4 J. Agramunt,∗1 V. Guadilla,∗1 A. Montaner-Pizá,∗1 S. Orrigo,∗1Á. Horváth,∗10 D. Napoli,∗7 S. Lenzi,∗8,∗9 A. Boso,∗8,∗9 V. Phong,∗4,∗11 J. Wu,∗4 P. Söderström,∗4T. Sumikama,∗4 H. Suzuki,∗4 H. Takeda,∗4 D. Ahn,∗4 H. Baba,∗4 P. Doornebal,∗4 N. Fukuda,∗4 N. Inabe,∗4T. Isobe,∗4 T. Kubo,∗4 S. Kubono,∗4 H. Sakurai,∗4 Y. Shimizu,∗4 C. Sidong,∗4 B. Blank,∗12 P. Ascher,∗12M. Gerbaux,∗12 T. Goigoux,∗12 J. Giovinazzo,∗12 S. Grévy,∗12 T. Kurtukián Nieto,∗12 C. Magron,∗12W. Gelletly,1,∗13 Z. Dombrádi,∗2 Y. Fujita,∗14,∗15 M. Tanaka,∗15,∗4 P. Aguilera,∗16 F. Molina,∗16 J. Eberth,∗17F. Diel,∗17 D. Lubos,∗18 C. Borcea,∗19 E. Ganioglu,∗20 D. Nishimura,∗21 H. Oikawa,∗22 Y. Takei,∗22 S. Yagi,∗22W. Korten,∗23 G. de France,∗6 P. Davies,∗24 J. Liu,∗25 J. Lee,∗25 T. Lokotko,∗25 I. Kojouharov,∗26 N. Kurz,∗26
H. Shaﬀner,∗26 and A. Petrovici∗19
We present preliminary results of our study of βdelayed proton emission detected in the β-decay of71
Kr. These results were obtained in the frameworkof the experiment NP1112-RIBF93. In our experimenta 40 particle nA 78 Kr primary beam provided by RI
Beam Factory (RIBF) impinged on a 5-mm thick Be
target to produce 9.8 million 71 Kr implants—after optimization to separate 71 Kr secondary beams—in theWAS3ABi active stopper.1) The WAS3ABi detector
was surrounded by the EURICA γ-ray spectrometer.2)
Beta-delayed protons were distinguished from βparticles in the same way as in our earlier work on 70 Kr,
using an energy threshold of 1400 keV measured inWAS3ABi,3) resulting in the deposited energy spectrum
shown in Fig. 1. The number of protons was divided
by the number of implants in order to calculate the βdelayed proton emission probability εp = 2.49(10)% inagreement with the value of εlit
p = 3.1(4)% found in
the literature.4) In our analysis the dead time of thedetector system was also accounted for, while a 100%detection eﬃciency was assumed for single protons.
A half-life value of T1/2 = 94.1(4) ms was derived

Fig. 1. Intensity distribution as a function of the depositedenergy of the β-delayed proton events in the DSSSD.
The high energy tail of β-particles was extrapolated by
an exponential function, shown in grey.

from the time correlations between protons and implants using an exponential ﬁt shown in Fig. 2, in agreement with the results obtained from implant-β timecorrelations (T1/2 = 94.5(2) ms) and from the decay
curve of β-delayed γ-transitions in the daughter nucleus(T1/2 = 95.5(24) ms).

∗1Instituto de Fisica Corpuscular
Institute for Nuclear Research (Atomki)∗3 PhD School of Physics, University of Debrecen∗4 RIKEN Nishina Center∗5 Instituto de Estructura de la Materia∗6 Grand Accélérateur National d’Ions Lourds∗7 INFN, Laboratori Nazionali di Legnaro∗8 INFN, Sezione di Padova∗9 Dipartimento di Fisica dell Universitá degli Studi di Padova∗10 Department of Physics, Eötvös Loránd University∗11 Faculty of Physics, VNU Hanoi University of Science∗12 Centre d Etudes Nucléaires de Bordeaux-Gradignan∗13 Department of Physics, University of Surrey∗14 Research Center for Nuclear Physics, Osaka University∗15 Department of Physics, Osaka University∗16 Comisión Chilena de Energı́a Nuclear∗17 Institute of Nuclear Physics, University of Cologne∗18 Physik Department E12, Technische Universität München∗19 National Institute for Physics, Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering∗20 Department of Physics, Istanbul University∗21 Department of Natural Sciences, Tokyo City University∗22 Department of Physics, Tokyo University of Science∗23 CEA Saclay, IRFU, Gif-sur-Yvette∗24 Department of Physics, University of York
∗25 Department of Physics, University of Hong Kong
∗26 GSI Helmholtzzentrum für Schwerionenforschung GmbH∗2- 20 -Fig. 2. Time correlations between β-delayed proton eventsand 71 Kr implants. The total ﬁt represents an exponential function plus a linear background.

The theoretical interpretation of the experimental
data is ongoing.
References
1) S. Nishimura, Prog. Theor. Exp. Phys. 2012, 03C006 (2012).
2) P. -A. Söderström et al., Nucl. Instrum. Methods Phys. Res.
B 317, 649 (2013).
3) A. Vitéz-Sveiczer et al., Phys. Lett. B 830, 137123 (2022).
4) S. Waniganeththi et al., Phys. Rev. C 106, 044317 (2022).