TRIAC Progress Report - KEK

Secondary 9 Li ions extracted from the ISOL target were accelerated up to 0.85
MeV/nucleon. Figure 3-22 shows the experimental setup for the study of the 9 Li+d
reactions. The beam ions of 9 Li were counted on an event-by-event basis using an MCP
detector with a 0.1 mg/cm 2 Mylar foil. After passing through the MCP detector, the 9 Li
beam bombarded a (CD2)n target of 2.3 mg/cm 2 with an average beam intensity of
approximately 3×10 4 pps. To deduce the excitation functions of 9 Li(d,d), 9 Li(d,t), and
9
Li(d,α) reactions, we utilized a thick target method in inverse kinematics (TTIK),
where the target thickness was chosen to be thick enough to stop most of the incident
9
Li ions in the target. The recoil deuteron, triton, and α particles suffered relatively
small energy losses in the target and detected by a Si detector array (SDA) located
26-cm downstream of the target with its center at 0°. The SDA consisted of 3×3 Si
detectors, each of which was 300-µm thick and had a sensitive area of 28×28 mm 2 .
TOF(ns)
120
115
110 110
105
100
95
90
85
80
75
70
0 2 4 6 8 10 12 14
E (MeV)
Fig.3-23. E-TOF spectrum for recoil particles.
The particle identification was made by using time-of-flight (TOF) information
between the MCP and SDA and energy (E) information of the SDA. Figure 3-23 shows
an example of the measured TOF-E spectrum. There was a background component
below 2 MeV, which was due to accidental α particles from the beta decay of 9 Li. The
timing distribution of the accidental α particles was essentially uniform and their energy
distribution could be easily estimated. Then, the accidental background component was
subtracted from the deuteron, triton, and α spectra. Though analysis is in progress, a
preliminary result of the 9 Li+d spectrum contains no sharp peak but shows
monotonically increasing cross sections toward the low excitation energy side. A
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