Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 49 (2016)

Performance test of the silicon tracker for the heavy-ion-proton
experiments at SAMURAI∗1∗2∗3∗4∗5∗6∗7A
Cluster sum [MeV]

132Xe secondary beamB(dE) ~ 1.4%
ToF [a.u.]

Cluster sum [MeV]

CProtons@ 230 MeV

Deposited energy [keV]

Measured dE [MeV]DCounts

An essential component of the future setup of theheavy-ion-proton (HI-p) experiments1) at SAMURAI
will be an array of GLAST-type2) single-sided silicon
strip detectors (SSDs) situated downstream of the target. These detectors will be used for precise tracking and identification of outgoing protons and heavyresidues. Each detector is 325 µm thick and has dimensions of 87.6 × 87.6 mm2 with a readout-pitch sizeof 864 µm. A key feature of the SSDs is their wide dynamic range, which allows for simultaneous detectionof protons and heavy ions, which deposit to a single
SSD energy ranging from ∼100 keV up to several hundreds MeV, respectively. This feature is achieved via
custom-designed ASIC dual-gain preamplifiers providing low-gain (LG) and high-gain (HG) readouts coupled to the high-density processing circuit HINP3) .
A performance test with the SSDs and their newelectronics was conducted at the HIMAC facility inJapan, using beams of protons with energies between
150 and 230 MeV as well as heavy-ion beams 12 C, 84 Kr,
and 132 Xe (primary and secondary) at a few hundreds
MeV/u. Only 32 central strips out of the 128 strips ofa single sensor were fully instrumented by the newly
designed ASIC preamplifiers, and only those channels
were read-out during the experiment.
The results of the performance test are summarized
in Fig. 1. Using the secondary beam, obtained byfragmentation of the primary 132 Xe at an energy of
200 MeV/u (see PID plot in Fig. 1(A,B)), the response of the LG readout was investigated for a wide
range of nuclear charge Z. A good linearity of theLG readout was observed (Fig. 1(D)) along with adeposited-energy dE resolution of σ(dE/E) ≈ 1.4%,
which is close to the designed value. The cross-talk ratio between a fired and a neighbouring strip is found tobe ∼1% after the add-back analysis combining HG andLG data. Saturation of the LG readout was observed
at dE  650 MeV, although the reconstruction of evenlarger dE was possible owing to a certain amount ofinterstrip hits in which dE is divided between the adjacent strips.
The performance of the HG readout was tested with
12C and proton beams. Good linearity of the HG dynamic range was confirmed. The required detection

CountsV. Panin,∗1 M. Kurokawa,∗1 K. Yoneda,∗1 H. Baba,∗1 J. C. Blackmon,∗2 Z. Elekes,∗3 Z. Halász,∗3 D. H. Kim,∗4T. Motobayashi,∗1 H. Otsu,∗1 B. C. Rasco∗2 A. Saastamoinen,∗5 L. G. Sobotka,∗6 L. Trache,∗7 and T. Uesaka∗1Linearity check

Calculated dE [MeV]Fig. 1. Performance results of the silicon tracker in the HIMAC test experiment. Figure A: particle identification(PID) of the secondary beam from 132 Xe at 200 MeV/u,
where dE measured by the SSD (cluster sum after theadd-back) is plotted against the time of flight (ToF).
Figure B: dE response of the SSD with the indicatedresolution σ(dE) for the selected species in Figure A
and the multiple-gauss fit (red line). Figure C: dE response of the HG readout with respect to 230 MeVprotons and Landau fit (red line). Figure D: comparison of the measured and calculated dE response in theSSD (symbols) with a linear fit (red line).

threshold of dE  100 keV for protons can be achieved
with the present configuration. The total detection efficiency of protons was found to be above 97%. Thus,
it is confirmed that the combined dynamic range of thedetector spans from ∼100 keV to ∼650 MeV, which inperspective would allow the simultaneous detection ofprotons and Z ≈ 50 heavy ions at RIBF energies.
The design and production of the missing preamplifier circuits is currently in progress and is expected tobe completed in 2016. Hence, a sufficient amount ofdual-gain readouts will be provided for all four silicon
trackers (i.e., 4 × 128 = 512 strips) intended for theactual HI-p experiments.
References
1) V. Panin et al.: RIKEN Accel. Prog. Rep., Vol 48(2015), 53.
2) R. Bellazzini et al.: Nucl. Instr. Meth. Phys. Res. A,Vol. 512 (2003), 136-142.
3) G. L. Engel et al.: Nucl. Instr. Meth. Phys. Res. A, Vol,573 (2007), 418-426.

RIKEN Nishina Center
Louisiana State University
Institute for Nuclear Research, MTA Atomki
Ewha Womans University
Cyclotron Institute, Texas A&M University
Washington University
IFIN-HH- 164 -