II-9. Instrumentation

RIKEN Accel. Prog. Rep. 54 (2021)

RIKEN Accel. Prog. Rep. 54 (2021)

Development of MCP timing detector for low-energy heavy ionsT. T. Yeung,∗1,∗2 S. Nishimura,∗2 W. Xian,∗1,∗3 and H. Ishiyama∗2Counttizer. The pulse height of the MCP fast ampliﬁer signal was calculated by subtracting the baseline from themaximum of the pulse. The response was sensitive andincreased with the beam energy linearly, as shown inFig. 4. We conﬁrmed that the MCP timing detector
could be a complementary option for a timing detector
instead of MagneTOF and α-TOF.2)
9 MeV
5+300

250

150

00

2000

4000

6000

8000

10000

 !

0∗2∗34000

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12000

Energy (keV)

3500

3 MeV He
3 MeV He (degrader)
3 MeV He (stopper)
0.6 MeV He
9 MeV Au
9 MeV Au (degrader)
3 MeV Au
3 MeV Au (degrader)
2 MeV Au
2 MeV Au (degrader)
2 MeV Au (stopper)2000

 1500 

Department of Physics, The University of Hong Kong
RIKEN Nishina Center
Wako Nuclear Science Center (WNSC), IPNS, KEK

10000

3000

1000

Fig. 1. Schematic of experimental setup, including degraderand MCP timing detector, with voltage settings. Positionof aluminum plate is adjustable. Ion beam, secondary
electrons, and decay particle are shown. Decay is not in
scope of this experiment.
∗1

2000

Fig. 3. MCP eﬃciencies for He and Au against ion energy.

 beam

3 MeV He
3 MeV He (degrader)
3 MeV He (stopper)
0.6 MeV He
9 MeV Au
9 MeV Au (degrader)
3 MeV Au
3 MeV Au (degrader)
2 MeV Au
2 MeV Au (degrader)
2 MeV Au (stopper)

2500



14000

Energy (keV)
5+

0.95

0.85

MCP PH

12000

10.9"# 2893

Fig. 2. Calibrated energy spectrum for 9 MeV Au
with labelled energy and charge state.



6744

Std Dev

12 MeV
7+50
 

20505

Mean

100

0.8

  Entries

3 MeV
1+
4.5 MeV
6 MeV
2+
3+

200

MCP eﬃciency

A prototype microchannel plate (MCP) timing detector was developed for correlated measurement of timeof ﬂight and decay properties by coupling with a multireﬂection time-of-ﬂight mass spectrograph. The detector consists of a silicon PIN photodiode S3590-19 andan MCP F2223-21SH, as shown in Fig. 1. We investigated the performance of the detector using ﬁve typesof beams: 2, 3 and 9 MeV 197 Au and 0.6 and 3 MeV 4 He
at the Pelletron accelerator. Three degrader settings
were available to reduce the beam intensity and provide
various beam energies. The beam was collimated by a0.2-millimeter-wide hole, degraded by a 2-micrometerthick mylar foil, or stopped by a 0.5-millimeter-thickaluminum sheet, as shown in Fig. 1.
Energy calibration of a silicon detector for 197 Au wasconducted by evaluating its dead layer thickness andpulse height defect using the Stopping and Range of Ionsin Matter (srim) code1) and assuming the charge state
assignment for the multi-peak 9 MeV Au5+ spectrum inFig. 2. From the srim results, the entrance window effect and the nuclear collision eﬀect account for 7% and48%, respectively, of 9 MeV Au. By considering botheﬀects, the calculated dead layer thickness of the silicondetector was 0.266 μm and the energy-response function
was obtained.
Based on coincidence of the MCP and silicon detector
signals, the detection eﬃciency of the MCP was evaluated. The MCP eﬃciency for detecting Au is over 90%
down to 2 MeV, as shown in Fig. 3. Pulse height analysis was performed to determine the energy responseof the MCP using the oﬄine data produced by a digi-02000

4000

6000

8000

10000

12000

Energy (keV)

Fig. 4. MCP pulse height for He and Au against ion energy.

References1) J. F. Ziegler et al., Nucl. Instrum. Methods Phys. Res. B268, 1818 (2010).
2) T. Niwase et al., Nucl. Instrum. Methods Phys. Res. A
953, 163198 (2020).
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