Finger Detector test for high intensity
1
0
3
2
5
4
7
6
9
8
11
10
13
12
15
14
Finger detector:
 15 plactic strips of ~14 mm width
 readout with 16 PMT's
Examples of rates supported by the finger detector, measurements made during the
104Sn Coulex experiment with 124Xe beam at 700 MeV/u:
Example 1:
Setting for 104Sn.
 On this run slits at S1 were closed at ±10 mm.
 The average rate on 1 strip was at most ~580 kHz, it was derived from the average
number of hits on 1 channel on the multihit TDC (time window of 5µs).
 The instant rate on 1 strip, derived from the mean value of the time difference
between 2 hits in 1 channel (see fig 1), was at most ~890 kHz
Fig. 1: Time difference between 2 hits if the multihit TDC for 1 channel in ns. The mean
value give the mean instant rate on the strip
Fig. 2: ToF measured with scintillators SC21 and SC41 (left) compared with ToF measured
with Finger and SC41 (right). It looks like if the SC21 was damaged.
Fig 3: Identification plot A/Q vs Z calculated with the finger detector (right). (103000 events
90600 in the plot) compared with the identification plot made with SC21 (left)
Example 2:
Setting for 104Sn.
On this run slits at S1 were opened at ±30 mm.
The average rate on 1 strip was at most ~850 kHz
The instant rate on 1 strip was at most ~1350 kHz
HV on SC21 scintillator was off.
Again the same pictures as example 1:
Fig. 4: Time difference between 2 hits if the multihit TDC for 1 channel in ns. The mean
value give the mean instant rate on the strip
Fig. 5: ToF measured with Finger and SC41 (HV on SC21 was off)
Fig 3: Identification plot A/Q vs Z calculated with the finger detector. (on this run 2 PMT's
so 3 strips were not working properly so the countrate is not correct)