Ⅱ-1. Nuclear Physics

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

Analysis of proton elastic scattering from 132 Sn and 48 Ca at
300 MeV/nucleon in inverse kinematics∗1Department of Physics, Toho University
RIKEN Nishina Center∗3 Department of Physics, Kyoto University∗4 Cyclotron and Radioisotope Center, Tohoku University∗5 School of Physics, Beihang University∗6 Research Center for Nuclear Physics, Osaka University∗7 Center for Nuclear Study, University of Tokyo∗8 Department of Physics, Tohoku University∗9 Department of Physics, Osaka University∗10 Department of Applied Physics, Miyazaki University∗11 Department of Natural Sciences, Tokyo City University∗245403530252015105060657075808590

recoil angle [degrees]Fig. 1. Angular distribution spectrum for selected elasticscattering events using NaI(TI) calorimeters.

Counts / 0.5[MeV]In this report, we show progress of analysis of proton elastic scattering from 132 Sn at 300 MeV/nucleon
in inverse kinematics. Previously, we already reported
the experimental conditions. We also showed the analyses of the particle identiﬁcations of the RI beams, andthe excitation energy spectra, and the angular distribution of the elastic scattering yields of 132 Sn.1,2) We
have discussed particle identiﬁcation for beam particles,
the excitation energy and of the angular distributionof 132 Sn.1–3) In order to obtain the absolute value ofelastic scattering cross-section of 132 Sn, it is necessary
to determine the target thickness. As calibration data
to determine it, it was necessary to analyze 48 Ca dataobtained in the same environment as the 132 Sn measurement. 48 Ca is a stable nucleus and, like 132 Sn, adouble magic number nucleus. The elastic scattering
diﬀerential cross section of 48 Ca has already been measured with high accuracy at RCNP. We assume thatthe target thickness can be determined by comparing
the cross-section obtained in the analysis with the data
already obtained at RCNP. Herein, we report on theanalysis of 48 Ca. We performed measurement of proton elastic scattering from 48 Ca in inverse kinematics at
300 MeV/nucleon at F12 area. The total beam rate wasup to 300 kcps, and purity of 48 Ca was 15%. By using
missing mass spectroscopy, the excitation energy distribution of 48 Ca was deduced from the measured recoil
proton kinetic energy and scattering angle information.
We identiﬁed elastic events of 48 Ca as shown in Fig. 2.
Figure 2 shows the excitation energy spectrum of theproton scattering from 48 Ca in the recoil angle 77◦ –80◦ .
The excitation energy resolution (in r.m.s.) of 900 keV
was achieved at a scattering angle of 77–80 degrees. Although the resolution is 1.5 times worse than that for
132
Sn, we could separate the excited state and the elastic scattering as shown in Fig. 2. The main excited stateenergy are 3.8 MeV (Jπ ) or 4.5 MeV (Jπ ). We will deduce the elastic scattering diﬀerential cross section ofCounts / 0.5[degrees]

T. Harada,∗1,∗2 J. Zenihiro,∗3,∗2 Y. Matsuda,∗4,∗2 S. Terashima,∗5 H. Sakaguchi,∗6 N. Aoi,∗6,∗2 H. Baba,∗2M. Dozono,∗7,∗2 F. Endo,∗8,∗2 S. Enyo,∗3 Y. Fujikawa,∗3 S. Hanai,∗7 S. Hayakawa,∗7 Y. Hijikata,∗3,∗2J. W. Hwang,∗7 N. Imai,∗7 K. Inaba,∗3 S. Ishida,∗4 T. Isobe,∗2 T. Kawabata,∗9,∗2 S. Kiyotake,∗10 A. Kohda,∗6,∗2H. Kurosawa,∗4 R. Kojima,∗7 R. Maeda,∗4 Y. Maeda,∗10 S. Y. Matsumoto,∗3 R. Matsumura,∗1,∗2 B. Mauss,∗2S. Michimasa,∗7 T. Murakami,∗3,∗2 D. Nishimura,∗11,∗2 T. Nishimura,∗10 K. Nosaka,∗4 S. Ota,∗7 K. Sakanashi,∗3H. Shimizu,∗7 D. Suzuki,∗2 J. Tanaka,∗2 R. Tsunoda,∗7 T. Uesaka,∗2 and K. Yamamoto∗45040

σ : ~ 900keV

3020100−10−5051015202530
Ex [MeV]Fig. 2. Excitation energy spectrum of 48 Ca at recoil angles
in the range of 77◦ –80◦ .
48

Ca by selecting elastic scattering from information on
the excitation energy distribution. We plan to determine
the target thickness by comparing the diﬀerential crosssection obtained by analysis data and the data alreadyobtained at RCNP. Using the determined target thickness, we plan to determine the diﬀerential cross sectionof 132 Sn for the ﬁrst time in the world.

References
1) J. Zenihiro et al., RIKEN Accel. Prog. Rep. 53, 44 (2019).
2) T. Harada et al., RIKEN Accel. Prog. Rep. 54, 18 (2020).
3) T. Harada et al., RIKEN Accel. Prog. Rep. 55, 23 (2021).
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