Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 48 (2015)

Production cross section measurements for fragments of 70 Zn beam

We measured the production yields and production cross sections of radioactive isotopes (RIs) inthe neutron-rich region with the atomic number Z =16 ∼ 24 produced from an 70 Zn beam at an energyof 345 MeV/nucleon by using the BigRIPS separator1) . Neutron-rich RIs were produced through projectile fragmentation on a 10-mm Be target, and theparticle identification (PID) of RIs was performed using the TOF-Bρ-∆E method. The energy loss (∆E)
was measured using an ion chamber at F7. The timeof-flight (TOF) between F3 and F7 was measured using
plastic scintillators and the trajectory was measured
at F3, F5, and F7 by using Parallel Plate Avalanche
Counters(PPACs).
The Bρ of BigRIPS was set to the rigidity corresponding to the center of the momentum distributionof 56 Ca, and the PID was confirmed by the isomers of56
Sc and 59 Ti. The experimental conditions for 56 Ca
setting are listed in Table 1. Figure 1 is a PID plot
showing the relation between the atomic number (Z)and mass-to-charge ratio (A/Q). Background eventswere eliminated by the correlations among phase-space
profiles by using the PPAC, pulse-height, and timing signals from the plastic scintillators; reaction loss
events in the ionization chamber; pile-up events using
plastic scintillators and the ionization chamber; particle trajectories between two different foci; and charge
state change at F5.

Atomic number Z

D. S. Ahn,∗1 H. Suzuki,∗1 N. Fukuda,∗1 H. Takeda,∗1 Y. Shimizu,∗1 D. Murai,∗1,∗2 K. Yoshida,∗1D. Kameda,∗1 H. Sato,∗1 Y. Sato,∗1 Y. Yanagisawa,∗1 K. Kusaka,∗1 M. Ohtake,∗1 N. Inabe,∗1 and T. Kubo∗1261032422102

2056Ca1810161412
2.5

2.55

2.6

2.65

2.7

2.75

2.8

2.85

2.9

2.95

31

mass-to-charge ratio A/QFig. 1. Particle identification plot of atomic number Z versus mass-to-charge ratio A/Q for projectile fragmentation in the reaction of 70 Zn + Be at an energy of 345
MeV/nucleon.

ment with the EPAX parameterizations. The production cross sections are consistent with EPAX2.15 forZ < 20 and with EPAX3.1a for Z > 20.

Table 1. Experimental conditions.
Center particle
TargetF1 degrader
F5 degrader
Bρ01
Momentum acceptance

56Ca
Be 10 mm
Al 3 mm
Al 5 mm
7.349 Tm
± 3%

The production cross sections were obtained using
the transmission efficiency calculated using LISE++
code3) and production yields. In Figure 2, the redcircles represent the experimental result of RIs produced from the 70 Zn beam. The solid and dashedlines in Fig. 2 represent the production cross sections
calculated with empirical formulae EPAX3.1a4) andEPAX2.155) , respectively. EPAX3 is proposed as theuniversal empirical formula, and it shows better agreement with experimental data for the most neutron-richfragments than EPAX2 does. Overall, our experimental measurements of cross sections are in good agree∗1∗2

RIKEN Nishina Center
Department of Physics, Rikkyo UniversityFig. 2. Production cross section for fragments of the 70 Zn
beam. The solid and dashed lines represent EPAX parameterizations, and the red circles represent experimental results.

References
1) T. Kubo et al.: 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 et al.: http://lise.nscl.msu.edu
4) K. Sümmer: Phys. Rev. C 86, 014601 (2012).
5) K. Sümmer and B. Blank: Phys. Rev. C 61, 034607(2000).

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