1. TOF detector for RIKEN Rare-RI Ring
D. Nagae
Univ. of Tsukuba
Univ. of Tsukuba Y. Abe, A. Ozawa, T. Moriguchi, Y. Ishibashi, Y. Ito,
H. Ooishi, S. Fukuoka, K. Okumura, R. Nishikiori, T. Niwa
Saitama Univ. T. Yamaguchi, T. Suzuki
RIKEN Y. Yamaguchi, H. Suzuki, M. Wakasugi
HIMAC M. Kanazawa, S. Sato

2. Requirement for TOF detector
Good time resolution
dm/m ～ 　　dT/T ∝ Dm/m 　　 dT < 100 ps
2) Energy loss and charge changing of particles should be small
　　 Energy acceptance : ±1 % 　 thin carbon foil (C-foil)
3) Large acceptance aperture
　 large beam size. (Height : ±25 mm, Width : ±50 mm)
　　　large C-foil and Micro Channel Plate (MCP) about 50 ×100 mm2

3. TOF detector for Rare RI-Ring
MCP(50mm×100mm)
C-foil (60 mg/cm2, 50mm×100mm)
D : lateral displacement
me : mass of electron
q : charge
E : magnitude of electric field
B : magnitude of magnetic field
dB / B = 6 %
A. M. Zebelman, et al., NIM 141(1977) 439
J. D. Bowman and R. H. Heffner, NIM 148 (1978) 503
R. H. Kraus Jr. et al., NIM A264 (1988) 327

4. Experiment @ HIMAC HIMAC : SB2 course Primary beam
84Kr , 200 MeV/u C-foil : 174MeV/u)
intensity　6×102～6×104 cps
TOF (Plastic scintillator – MCP)
Setup

5. Result sTOF = 161 ±6 ps Energy acceptance : ±1% Fitting of Gaussian
Resolution of TOF detector
Beam :600 cps
Resolution of Plastic
= 140ps
Count [ / 50 ps]
sTOF = 161 ±6 ps
TOF (Pla – MCP) [ns]
Detection Eff. : 65%
(Preliminary)

6. Offline measurement 1
Setup
Detection Eff. : 9±2 %
(Preliminary)

7. Offline measurement 2 Dependence of incidence position

8. Offline measurement 3 Dependence of electric and magnetic fields
E = 17 V/mm, B = 21 G  E = 60 V/mm, B = 38 G ② ②
①reduce electrode plate
②R to be large ① ①
Before
After

9. Summary Developing TOF detector for RIKEN rare-RI ring
84Kr (200 AMeV)  sTOF = 161±6 ps
a-ray(241Am)  stot = 398±6 ps
Electric and magnetic fields
E = 17 V/mm, B = 21 G  stot = 398±6 ps
E = 60 V/mm, B = 38 G  stot = 161±2 ps
Future
Improvement of Electric and magnetic fields (magnitude, homogeneity)
Improvement of detection efficiency