Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 48 (2015)

Performance evaluation of GET readout electronics for heavy ion
collision experiments at RIBF
G. Jhang,∗1,∗2 T. Isobe,∗2 M. Kurata-Nishimura,∗2 T. Murakami,∗3 M. B. Tsang,∗4 S. Hasegawa,∗5 K. Hosomi,∗5S. Hwang,∗5 H. Sugimura,∗5 J. Brzychczyk,∗6 B. Hong,∗1 P. Lasko,∗6 J. Lukasik,∗7 W. G. Lynch,∗4P. Pawlowski,∗7 Z. Sosin,∗6 and S. Tangwancharoen∗4 for the SπRIT Collaboration∗1∗2∗3∗4∗5∗6∗7

Department of Physics, Korea University
RIKEN Nishina Center
Department of Physics, Kyoto University
National Superconducting Cyclotron Laboratory and Department of physics and Astronomy, Michigan State University
Advanced Science Research Center, Japan Atomic Energy
AgencyJagiellonian University
Institute of Nuclear Physics PAN

layer numbers, where one layer means a row of 96 pads
perpendicular to the beam axis and the BRAHMSTPC has 12 layers. To obtain the resolution we selected three successive layers and calculated the diﬀerence between the hit position on the middle layer andthe average position of hits on the ﬁrst and the thirdlayers assuming that the resolution of each pad is thesame as δx. For example, x = 0 means the resolution is calculated with the layer number 0, 1, and 2by accumulating x1 − (x0 + x2 )/2 values for all events.
By the error propagation the RMS value of the distribution,σ, and the resolution, δx, have the relation:√σ = 3/2δx.
0.45
0.4Resolution (mm)

GET(Generic Electronics for TPCs)1) will be usedas the front-end readout electronics for the newly constructed SπRIT-TPC(SAMURAI pion Reconstruction
Ion-Tracker Time Projection Chamber)2) . The GETelectronics has been recently developed by the GET
collaboration for the particle and nuclear physics experiments and its performance is yet to be evaluated.
We performed a test experiment at the Heavy Ion Medical Accelerator in Chiba(HIMAC) facility using theBRAHMS-TPC(TPM1)3) to evaluate the performanceof the GET electronics. The TPC has the multi-wire
conﬁguration similar to the SπRIT-TPC: anode wires
for signal multiplication, gating grid wires to reducethe background noise.
We used 300 AMeV 132 Xe beam with 500 mg/cm2
CsI target surrounded with the multiplicity trigger array of 60 scintillator plastics. To evaluate the resolution in both wire and drift directions, in the ﬁrst setup
the BRAHMS-TPC(TPM1) was placed at 60 degrees
oﬀ the beam axis and we took data with diﬀerent sampling rate of 5, 10, 25, 50, 100 and 200 MHz and shaping time of 70, 232, 502 and 1014 ns. Due to breakdownof the µ-TCA power supply, only one AsAd board(256channels) is used in this conﬁguration.
In the second setup the BRAHMS-TPC(TPM1) waslocated at 0 deg. We replaced the broken power supply
and took data with three AsAd boards(768 channels)
controlled by a full CoBo(Control Board for 4 AsAdboards). We tested the gating grid drivers with beam
intensities varying from 102 to 105 pps. We placed
ﬁve 3 mm thick Al plates in front of the TPC to stop
the beam and heavy fragments so that only the lightcharged particles with Z < 3 can reach the TPC at theintensity 104 and 106 pps. Finally, with beam intensity
104 and 105 pps we took data under the SπRIT-TPC
experimental condition: sampling rate of 25 MHz,shaping time of 232 ns, 256 time buckets(10.24 µs),
and zero suppression mode.
Figure 1 shows the preliminary result in the ﬁrst
setup. The resolution is presented as a function of the0.35

Drift0.3

Wire0.25
0.2
02468
Used Layer (x = [x, x+1, x+2])

10Fig. 1. Resolution of the wire and drift direction as a function of the layer number x, which is the first layer number among three layers.
Table 1. Resolution from two collaborations
Collaboration
BRAHMS
SπRITDirection
wire (µm) drift (µm)
310427
217±10401±22Comparison between the result from both collaborations is summarized in Table 1. Our result is better
because the GET electronics is 12 bit ADC while theBRAHMS collaboration used 10 bit ADC.
Further analyses in the second setup are ongoing.
References
1) E. Pollacco et al.: Physics Procedia 37 (2012) 1799.
2) R. Shane et al.: Nucl. Instr. and Meth. A 784 (2015)
512.
3) M. Adamczyk et al.: Nucl. Instr. and Meth. A 499(2003) 437.

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