Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 48 (2015)

Particle identification for Sn region with SAMURAIJ. Yasuda,∗1 M. Sasano,∗2 R.G.T. Zegers,∗3 H. Baba,∗2 W. Chao ,∗2 M. Dozono,∗2 N. Fukuda,∗2 N. Inabe,∗2T. Isobe,∗2 G. Jhang,∗2,∗13 D. Kamaeda,∗2 T. Kubo,∗2 M. Kurata-Nishimura,∗2 E. Milman,∗2 T. Motobayashi,∗2H. Otsu,∗2 V. Panin, ∗2 W. Powell, ∗2 M. Sako, ∗2 H. Sato,∗2 Y. Shimizu,∗2 L. Stuhl,∗2 H. Suzuki,∗2T. Suwat, ∗2 H. Takeda,∗2 T. Uesaka,∗2 K. Yoneda,∗2 J. Zenihiro,∗2 T. Kobayashi,∗4 T. Sumikama,∗4 T. Tako,∗4T. Nakamura,∗5 Y. Kondo,∗5 Y. Togano,∗5 M. Shikata,∗5 J. Tsubota,∗5 K. Yako,∗6 S. Shimoura,∗6S. Ota,∗6 S. Kawase,∗6 Y. Kubota,∗6 M. Takaki,∗6 S. Michimasa,∗6 K. Kisamori,∗6 C.S. Lee,∗6 H. Tokieda,∗6M. Kobayashi,∗6 S. Koyama,∗7 N. Kobayashi, ∗7 H. Sakai,∗8 T. Wakasa,∗1 S. Sakaguchi,∗1 A. Krasznahorkay,∗9T. Murakami, ∗10 N. Nakatsuka, ∗10 M. Kaneko, ∗10 Y. Matsuda, ∗11 D. Mucher, ∗12 S. Reichert, ∗12 D. Bazin,∗3and J.W. Lee∗13∗1Department of Physics,Kyushu University
RIKEN Nishina Center∗3 NSCL Michigan State University∗4 Department of Physics, Tohoku University∗5 Tokyo Institute of Technology∗6 CNS, University of Tokyo∗7 University of Tokyo∗8 ULIC, RIKEN Nishina Center∗9 MTA, Atomki∗10 Kyoto University∗11 Konan University∗12 Technical University Munich∗13 Department of Physics, Korea University∗2ZZ

from FDC23) drift chamber which was placed after theSAMURAI spectrometer. The obtained ∆E resolutionis σ∆E /∆E = 0.43 ± 0.03(stat.) %.
The rigidity was analyzed by using four drift chambers BDC1,2, FDC1 and FDC23) . The obtained rigidity resolution is R/σR = 1318 ± 27(stat.).
Figure. 1(a) shows the PID spectrum with respect
to atomic number Z and mass to charge ratio A/Q.
The Z resolution is σZ = 0.22 corresponding to 4.6σ
separation for Z=50 and 51. The A/Q resolution isσA/Q = 0.14 % for 132 Sn50+ which corresponds to 5.4σ
separation.
52
52

51.5
51.5
51
51(a)
(a)

Sb
Sb

135
13550+
Sn50+
Sn50
50

1022
1049+
Sn49+
Sn

132
132

132
132

50.550.51010In
In

49.5
49.5

129
129

49
49
48.5
48.5
4848

1147.5
47.5

2000
2000
1800
1800
1600
1600
1400
1400
1200
1200
1000
1000
800
800

2.56
2.56

2.58
2.58

2.6
2.6

2.62
2.62

2.64
2.64(b)
(b)

2.66
2.66

2.68
2.68

2500
2500

2000
2000

σZZ =
= 0.22
0.22
σ

2.7
2.7

2.72
2.72

2.74
2.74

mass toto charge
charge ratio
ratio (A/Q)
(A/Q)
mass

CountsCounts47
47

CountsCounts

We performed the SAMURAI17 experiment1) at
RIKEN RIBF to study Gamow-Teller transition in132
Sn by (p, n) reaction with the WINDS2) and theSAMURAI spectrometer3) . The SAMURAI spectrometer was used for tagging (p, n)-reaction events withthe particle identiﬁcation (PID) of the beam heavyfragments. The PID was performed with the TOF-Bρ∆E method. Here we report the preliminarily resultson the PID.
Here, we used the 132 Sn beam run with empty-target
cell at F13 and selected the non-reacted trigger eventsin order to estimate the resolution of TOF, Bρ and∆E. The beam rigidity was measured by the BigRIPS
with a typical momentum resolution of R/σR ∼ 3000.
The TOF was measured by using the plastic scintillators SBT1,2 and the HODS with ﬂight path lengthL  12.5 m. The HODS consists of 6 plastic scintillation counters with size of 450 mm × 100 mm ×5 mm. The obtained TOF resolution is σt = 62.1 ±2.7(stat.) ps, where the statistical uncertainty is indicated. It should be noted that the non-uniformity ofSBT1 thickness is as large as about 20 % which corresponds to 1 MeV/nucleon energy loss diﬀerence for 200
MeV/nucleon 132 Sn beam. In this analysis we gatedthe central position of SBT1 to estimate the TOF resolution, by using tracking information from BDC1,23)
drift chamber which were placed between SBT1,2 andthe target. In the following the resolution was estimated with the same manners.
The energy loss ∆E was measured by HODS. The∆E is sensitive to the HODS thickness. In this experiment the non-uniformity of HODS thickness is about
10–20% for 6 counters. In order to correct the thickness dependence, we used the tracking information

1500
1500

1000
1000

(c)
(c)

SnSn

(49.5 << ZZ << 50.5)
50.5)
(49.5

σA/Q
= 0.14%0.14%
σ=A/Q
13250+
Sn50+for 132
Sn
for

600
600
400
400

500
500

200
20000
47 47.5
47.5 48
48 48.5
48.5 49
49 49.5
49.5 50
50 50.5
50.5 51
51 51.5
51.5 52
52
47

Z
Z00

2.56 2.58
2.58 2.6
2.6 2.62
2.62 2.64
2.64 2.66
2.66 2.68
2.68 2.7
2.7 2.72
2.72 2.74
2.74
2.56

mass toto charge
charge ratio
ratio (A/Q)
(A/Q)
mass

Fig. 1. (a) A SAMURAI PID spectrum with respect to Z
and A/Q for non-reacted events with empty target cell.
(b) Z distribution for all beam component and (c) A/Qdistribution for Sn isotopes. The resolution of Z andA/Q are σZ = 0.22 and σA/Q = 0.14% for 132 Sn50+ ,respectively.

References
1) M. Sasano et al., : in this report.
2) J. Yasuda et al.,: in this report.
3) T. Kobayashi et al., Nucl. Instr. Meth. B317, 294 (2013).

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