Transcript Slide 1

M.Bhuyan, S.D.Kalmani, N.K.Mondal, S.Pal, Deepak
Samuel, B.Satyanarayana and R.R.Shinde
Gouranga Kole, Chiraag Lala and Kanishka Rawat
Total number of RPCs in ICAL = 3  150  64 = 28,800
Total gas volume = 28,800  184cm  184cm  0.2cm = 195,010 litres
For example:
One volume change/day with 10% gas top-up in a re-circulating scheme
Approximate running gas cost = Rs 30,000/day (R134a from Mafron)
Gas
Avalanche
(%)
Streamer
(%)
Maximum
(%)
Volume
(L)
Density
(g/L)
Weight
(Kg)
Argon
0.0
30.0
30.0
58,503
1.784
104.4
R134a
95.5
62.0
95.5
186,234.6
4.25
791.5
Isobutane
4.3
8.0
8.0
15,600.8
2.51
39.16
SF6
0.2
0.0
0.2
390
6.164
2.40
B.Satyanarayana, TIFR, Mumbai
INO Collaboration Meeting, Madurai
Cost
(Rs/Kg)
January 23-26, 2011
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
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Recycling of gas mixture for reduction of gas cost
and complying with environmental regulations.
Further reduction in the operating cost of ICAL in
the long run without compromising on the detector
efficiency and performance.
Study contamination and formation of radicals in
the gas mixture flowing through the RPCs.
These kind of studies do not seem to have been
performed by other researchers.
B.Satyanarayana, TIFR, Mumbai
INO Collaboration Meeting, Madurai
January 23-26, 2011
One 1m×1m RPC (called AB13) was sealed on
February 5, 2010. Its operating parameters such as
strip rate and current were monitored 24×7, along
with laboratory temperature and relative humidity.
After 130 days of
uninterrupted
operation, the gas
inside RPC was
analyzed using a
Residual Gas Analyzer
(RGA)
B.Satyanarayana, TIFR, Mumbai
INO Collaboration Meeting, Madurai
January 23-26, 2011
B.Satyanarayana, TIFR, Mumbai
INO Collaboration Meeting, Madurai
January 23-26, 2011
B.Satyanarayana, TIFR, Mumbai
INO Collaboration Meeting, Madurai
January 23-26, 2011
B.Satyanarayana, TIFR, Mumbai
INO Collaboration Meeting, Madurai
January 23-26, 2011
40
RGA spectra was collected with
background of Argon.
28
20
33
69
B.Satyanarayana, TIFR, Mumbai
INO Collaboration Meeting, Madurai
January 23-26, 2011
28
Removing the background Argon spectra,
major fragment was at mass no. 28
33
69
83
B.Satyanarayana, TIFR, Mumbai
INO Collaboration Meeting, Madurai
January 23-26, 2011
33
Removing the air background ,
major fragment was at mass no. 33
69
51
B.Satyanarayana, TIFR, Mumbai
83
INO Collaboration Meeting, Madurai
January 23-26, 2011
Major fragments of pure gases
B.Satyanarayana, TIFR, Mumbai
 RGA spectra
contains nearly 50%
air and 3% water
vapour.
 RPC AB13 was
sealed for 130 days.
 Amount of air
accumulated
~1000ml.
 Therefore, the leak
rate ~8ml/day.
INO Collaboration Meeting, Madurai
January 23-26, 2011
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
Stack of 12 1m×1m RPCs
L0, L4 and L11 were used as reference
Other RPCs sealed on April 27, 2010
Summary of the study
Sl.
no
1
2
3
4
5
6
7
8
9
10
11
12
B.Satyanarayana, TIFR, Mumbai
Layer
No
L00
L01
L02
L03
L04
L05
L06
L07
L08
L09
L10
L11
RPC
Name
AB06
AB07
AB10
AB11
AB09
IB02
AB02
AB01
AB03
AB04
AB12
AB08
Sealing
date
-------------27-Apr-10
27-Apr-10
27-Apr-10
-------------27-Apr-10
27-Apr-10
27-Apr-10
27-Apr-10
27-Apr-10
27-Apr-10
--------------
INO Collaboration Meeting, Madurai
Gas flow No of days
restarted
sealed
--------------19-Jul-10
83
19-Jul-10
83
31-May-10
34
--------------19-Jul-10
83
29-May-10
32
29-May-10
32
19-Jul-10
83
29-May-10
32
28-May-10
31
--------------January 23-26, 2011
AB06_+ve
AB06_-ve
Current (nA)
Current (nA)
160
140
120
100
80
60
40
20
0
28-Mar
400
350
300
250
200
150
100
50
0
28-Mar
Reference RPC
12-Apr
27-Apr
12-May
27-May
11-Jun
26-Jun
AB04_+ve
11-Jul
26-Jul
10-Aug
26-Jul
10-Aug
AB04_-ve
A
B
12-Apr
27-Apr
12-May
27-May
A= RPC Sealed for 32 days
B.Satyanarayana, TIFR, Mumbai
11-Jun
26-Jun
11-Jul
B = Gas flow restarted
INO Collaboration Meeting, Madurai
January 23-26, 2011
400
AB07_+ve
350
AB07_-ve
A
B
Current (nA)
300
250
200
150
100
50
0
28-Mar
12-Apr
27-Apr
300
A
27-May
IB02_+ve
11-Jun
26-Jun
11-Jul
26-Jul
10-Aug
26-Jul
10-Aug
IB02_-ve
B
Current (nA)
250
12-May
200
150
100
50
0
28-Mar
12-Apr
27-Apr
B.Satyanarayana, TIFR, Mumbai
12-May
27-May
11-Jun
26-Jun
11-Jul
INO Collaboration Meeting, Madurai
January 23-26, 2011
350
300
L00
L06
L05
A
C
B
Strip Rate (Hz)
250
200
150
100
50
0
21-Feb
23-Mar
22-Apr
A = Sealed (L05, L06)
B.Satyanarayana, TIFR, Mumbai
22-May
21-Jun
21-Jul
B = Flow started (L06)
20-Aug
19-Sep
19-Oct
C = Flow started (L05)
INO Collaboration Meeting, Madurai
January 23-26, 2011
 Pressurise the chamber to 2030mm water column.
 Look for the leak.
 Locate the leaks using gas sniffer.
 Plug the leaks with glue.
 Redo the above till all the leaks
are plugged.
B.Satyanarayana, TIFR, Mumbai
INO Collaboration Meeting, Madurai
January 23-26, 2011
Layer RPC Id
Test
L rate
(Days) (mm/hr)
I end I begin
I
I rate
R end R begin
R
R rate
(nA)
(nA)
(nA)
(nA/day)
(Hz)
(Hz)
(Hz)
(Hz/day)
0
AB06
(Ref)
TBD
-
-
-
-
-
-
-
-
1
AB07
83
TBD
241
38
203
2.4
416
15
401
4.8
2
AB10
83
1.3
190
19
171
2.1
505
30
475
5.7
3
AB11
34
12
262
47
215
6.3
377
81
296
8.7
4
AB09
1
72
-
-
-
-
-
-
-
-
5
IB02
83
TBD
120
68
52
0.6
100
40
60
0.7
6
AB02
32
TBD
302
69
233
7.3
377
37
340
10.6
7
AB01
32
TBD
266
67
199
6.2
344
45
299
9.3
8
AB03
83
TBD
182
21
161
1.9
256
52
204
2.5
9
AB04
32
TBD
355
55
300
9.4
1067
70
997
31.2
10
AB12
31
10
492
46
446
14.4
934
31
903
29.1
11
AB08
(Ref)
12
-
-
-
-
-
-
-
-
B.Satyanarayana, TIFR, Mumbai
INO Collaboration Meeting, Madurai
January 23-26, 2011

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Different rate of change of strip rate and current
with time may be attributed to different leak rate for
different RPCs.
With proper sealing condition, the detector can run
for at least one month, once filled, reducing the cost
by factor of 30.
The gas can be recovered efficiently with more
contaminants by reusing the same gas for longer
period of time.
All the RPC parameters have come back to their
earlier values after reflowing fresh gas through
RPCs.
B.Satyanarayana, TIFR, Mumbai
INO Collaboration Meeting, Madurai
January 23-26, 2011
Efficiency (%)
100
95
90
85
EFF_X0
EFF_X4
80
EFF_X11
75
70
23-Mar
22-Apr
22-May
21-Jun
21-Jul
20-Aug
19-Sep
Multiplicity
3
2
MULT_X0
MULT_X4
MULT_X11
1
0
23-Mar
22-Apr
B.Satyanarayana, TIFR, Mumbai
22-May
21-Jun
21-Jul
20-Aug
INO Collaboration Meeting, Madurai
19-Sep
January 23-26, 2011
Efficiency (%)
100
95
EFF_X3
EFF_X6
EFF_X7
EFF_X9
90
85
80
23-Mar
22-Apr
22-May
21-Jun
21-Jul
20-Aug
19-Sep
Multiplicity
3
MULT_X3
2
MULT_X6
MULT_X7
MULT_X9
1
0
23-Mar
22-Apr
B.Satyanarayana, TIFR, Mumbai
22-May
21-Jun
21-Jul
20-Aug
INO Collaboration Meeting, Madurai
19-Sep
January 23-26, 2011
Efficiency (%)
100
95
EFF_X2
90
EFF_X5
EFF_X8
EFF_X1
85
80
75
70
23-Mar
22-Apr
22-May
21-Jun
21-Jul
20-Aug
19-Sep
Multiplicity
3
MULT_X2
MULT_X5
MULT_X8
MULT_X1
2
1
0
23-Mar
22-Apr
B.Satyanarayana, TIFR, Mumbai
22-May
21-Jun
21-Jul
20-Aug
INO Collaboration Meeting, Madurai
19-Sep
January 23-26, 2011
B.Satyanarayana, TIFR, Mumbai
INO Collaboration Meeting, Madurai
January 23-26, 2011