Transcript First results from the cosmic ray stand at LNF

First results from the
cosmic ray stand at LNF
System set-up
 The system is
designed to house 6
chambers a time;
 3 scintillators acquired
on both ends;
 The trigger is given by
the AND of the 6 PMs
 Time jitter of each
scintillator side of about
5 ns
 The trigger time RMS is about 10 ns
Davide Pinci
DAQ set-up
 The DAQ is based on a 128 ch VME
TDC and a multiplexer and will be able
to acquire up to 600 channels;
 The MuX will be ready by the end of
the year;
 This summer we had problem with the
128 ch TDC and we used a 64 ch
TDC;
 Now the 128 ch TDC is fixed and we
can acquire 192 ch (by using 2 TDCs);
Davide Pinci
Studies on chamber 12
 Very good gain uniformity in gap A and B. We
espect good efficiency and the time
performance of the bi-gap AB
 Bent panel gives not uniform current in gap C
and D. What is the efficiency and the time
performance of the bi-gap CD
 We equipped the central region of C012 with
4 ASDQ boards (64 channels with thr 250 mV)
and we studied the performance of the single
gaps and of the bi-gap AB and CD.
Region equipped
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Standard trigger
Electronics channel broken
Bi-gap AB
 We checked the
electrical connections of
the pads and
channel used for
TDC trigger time
Bi-gap CD
 We decided to use a
scintillator finger in order
to optimize the trigger
time performance.
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Trigger with finger
rms 4 ns
Bigap AB
time/0.8 (ns)
rms 4 ns
Bigap CD
time/0.8 (ns)
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Scintillator finger
Results: mono-gaps
Efficiency in 20 ns
Total efficiency
Efficiency in 20 ns
Total efficiency (%)
105
100
95
90
85
90
85
80
75
70
65
80
60
75
55
70
50
Gap
Gap
Gap
Gap
45
65
Gap
Gap
Gap
Gap
60
55
50
A
B
C
D
40
35
30
A
B
C
D
25
20
45
15
40
2600
95
2620
2640
2660
2680
2700
2720
2740
2760
2780
2800
Voltage (V)
2820
10
2600 2620
2640
2660
2680 2700
2720 2740
2760
2780
2800 2820
Voltage (V)
As expected gap C has higher time resolution and gap D the lower one
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Bi-Gap efficiency (%)
Results: double-gaps
100
95
90
85
80
75
Total efficiency AB
Total efficiency CD
Efficiency in 20 ns AB
Efficiency in 20 ns CD
70
65
60
2500
2550
2600
2650
2700
2750
2800
Voltage (V)
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The efficiency and
time performance of
the bi-gap AB and CD
are the same starting
from a HV value
between 2.60 kV and
2.65 kV.
Study of “hospital” effect
 In order to study the effect of a wire pad in hospital we made a
HV scan while keeping a wire pad to 2500 V;
No hospitals
100
95
Efficiency (%)
90
1 WP in hospital
85
80
Total
Total with H
20 ns
20 ns with H
75
70
65
60
2500
2550
2600
2650
2700
2750
2800
Voltage (V)
 For voltage above 2600 V the time
performance is the same
We plan to study the effect of hospital with lower voltage (2200 V and 2000 V)
Davide Pinci
Conclusion
 The cosmic ray stand at LNF is now working and can acquire two MWPC
fully equipped with CARIOCA (192 ch);
 When MuX will be ready the system will be able to acquire up to 6
chambers a time;
 The system can be very usefull to check chambers which appear
“strange” after the source scan;
 We studied a C012 and we found that at 2.60-2.65 kV a doublegap with
a bent panel inside has the performance as a normal doublegap;
 We also found the minor effect one WP in hospital has on the time
efficiency of a bi-gap;
 Other studies can be performed:
 long term tests
 dateiled study of “hospital effect” on the time performance
 room pressure and temperature effect
 ...
Davide Pinci