JAEA-Conf 2011-002 - 日本原子力研究開発機構

Fig.2. Schematic drawing of the stacked scintillator spectrometer used in our measurements
Signals were processed in a standard electronic setup of NIM modules, such as
discriminators and coincidence circuitry. The output charges from PMTs were digitized with
CAMAC ADC and the digital data were recorded event-by-event on the hard disk of a PC for
subsequent off-line analyses.
We also measured background events using an empty target frame for the following two
reasons. One reason is due to beam halo which could distort energy distributions, the other is
to eliminate the events caused by nuclear reactions in the beam monitor.
3. Off-line analysis
Double differential cross sections were determined through off-line analysis. The recorded
pulse heights of signals were converted into particle energy using the Bethe-Bloch equation
[2] and Birks equation [3] taking into account the nonlinearity between light output and
energy deposition. Particle identification was carried out by using PI technique [4]. The
particle identification quantity, PI, is given by,
PI E
b
total
JAEA-Conf 2011-002
b EE (
1)
total
where Etotal is the total energy deposited in the spectrometer, the ΔE is the amount of energy
deposited in the transmission detector and b is the parameter whose value was employed to
be 1.73 to obtain best separation. Fig. 3 shows the example of a two-dimensional plot of PI
versus particle energy for the oxygen induced reactions on the carbon target at 5 degrees. The
thick belt lying at around PI = 200 corresponds to proton good events, which stopped in the
crystal through the electronic interaction. On the other hand, the belt lying at around PI =
300 corresponds to deuteron events.