Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 50 (2017)

Production cross-section measurement for radioactive isotopes
produced from 124Xe beam at 345 MeV/nucleon by BigRIPS
separator
H. Suzuki,∗1 N. Fukuda,∗1 H. Takeda,∗1 Y. Shimizu,∗1 D.S. Ahn,∗1 T. Sumikama,∗1 D. Murai,∗1,∗2J. Amano,∗1,∗2 N. Inabe,∗1 K. Yoshida,∗1 K. Kusaka,∗1 Y. Yanagisawa,∗1 M. Ohtake,∗1 Z. Korkulu,∗1T. Komatsubara,∗1 H. Sato,∗1 and T. Kubo∗1
One was the 91 Rh setting, in which the Bρ setting
is optimized for 91 Rh, for producing RIs with atomic
numbers Z = 41−48, and the other was the 80 Y settingfor Z = 35−42. The particle identiﬁcation of the RIs
was based on the TOF-Bρ-ΔE method in the second
stage of the BigRIPS.2)
The production cross-sections were deduced fromthe measured production rates and the transmission efﬁciency in the separator, which was simulated with thecalculation code LISE++ .3) In the simulation, exponential tails of the momentum distribution of the RIs
in the low-momentum regions fell oﬀ slower than themomentum distribution observed in the experiment;
therefore, we adjusted the parameter “coef”, which
controls the slope of the distribution tail. In the 91 Rh
setting, “coef” was set to 1.9, which was obtained fromthe momentum distribution of 99 Rh in our ﬁrst 124 Xebeam experiment.4) In the 80 Y setting, “coef” = 2.4
reproduced the distribution of RIs fairly well. The parameter “coef” may depend on the region of the RI
beams. The parameters for the angular distribution
were not changed from the original values in the code.
The measured production cross-sections of the RIs
are shown in Fig. 1. In these ﬁgures, the solid anddashed lines show the cross sections predicted fromthe empirical formulas EPAX3.1a5) and EPAX2.15,6)
respectively. EPAX3.1a reproduces the measured crosssections with a wide range of Z better than EPAX2.15;
however, some isotopes show systematic discrepancies
around the very proton-rich region and the high-Zregion. These discrepancies are also observed in theproton-rich RIs produced from the 345-MeV/nucleon78Kr beam.8)

We have measured the production yields and theproduction cross-sections for a variety of protonrich radioactive isotopes (RIs) produced from a 345MeV/nucleon 124 Xe beam using the BigRIPS separator.1) The RI beams were produced by projectile fragmentation of the 124 Xe beam on a 4-mm Be target.
Two BigRIPS settings were conducted in this work.

102(a)

Production cross section (mb)

100
10-2
10-4

Se

Kr

Sr

10-6ZrMoRu

Pd

10-8Cd

Sn-10

10Te

10-12(b)Production cross section (mb)

100
10-2
10-4

BrRb-610YNbTc-81010-10Rh

this work124Xe-beam first exp.4)
100Sn exp.7)73Sr exp.

10-1265707580AgInSbEPAX3.1aEPAX2.15

859095100105110

Mass numberFig. 1. Production cross-sections of RIs produced in the124
Xe + Be reaction at 345 MeV/nucleon with predictions of EPAX parametrizations. (a) Results for even-Zisotopes. (b) Results for odd-Z isotopes. The ﬁlled andopen symbols indicate that the distribution peaks ofRIs were located inside the slit opening at each focus
and outside at some foci, respectively. Solid and dashedlines show the values predicted using EPAX3.1a5) andEPAX2.156) formulas, respectively.
∗1∗2

RIKEN Nishina Center
Department of Physics, Rikkyo University- 87 -References
1) T. Kubo, Nucl. Instrum. Meth. Phys. Res. B 204, 97(2003).
2) N. Fukuda et al., Nucl. Instrum. Meth. Phys. Res. B
317, 323 (2013).
3) O. B. Tarasov and D. Bazin:
LISE++ site,
http://lise.nscl.msu.edu, Michigan State University.
4) H. Suzuki et al., Nucl. Instrum. Meth. Phys. Res. B
317, 756 (2013).
5) K. Sümmer, Phys. Rev. C 86, 014601 (2012).
6) K. Sümmer and B. Blank, Phys. Rev. C 61, 034607(2000).
7) I. Celikovic et al., Phys. Rev. Lett. 116, 162501 (2016).
8) H. Suzuki et al., RIKEN Accel. Prog. Rep. 49, 68(2017).