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Activities During 4/11/07 IR Access
HBD Working Group Meeting 4/17/07
B.Azmoun, T.Hemmick, J.Kamin, S.Stoll, C.Woody Brookhaven National Lab / SUNY SB
4/17/07 B.Azmoun, BNL 2
4/11 Access: Flash Lamp TestsHBD_E Phtocathode Response: 4/11/07
0.00.20.40.60.81.01.21.41.6
ES0 ES1 ES2 ES3 ES4 ES5 EN0 EN1 EN2 EN3 EN4 EN5
Module
Rat
io:
4/11
/07
/ 12/
24/0
6
Lamp Top
Lamp Bottom
HBD_W Phtocathode Response: 4/11/07
0.00.20.40.60.81.01.21.41.6
WS0 WS1 WS2 WS3 WS4 WS5 WN0 WN1 WN2 WN3 WN4 WN5
Module
Rat
io:
4/11
/07
/ 12/
24/0
6
Lamp Top
Lamp Bottom
4/11/2007CF4VGEM = 100VVref = 6.5V2x16nSNew Scope (1Mohm)H2O ppm (W/E) = 3.3/6.2O2 ppm (W/E) = 4.0/2.7Flow (W/E)=3.75/4slpm
12/24/2006CF4VGEM = 100VVref = 6.5V2x16nS New Scope (1Mohm)H2O ppm (W/E) = 16.7/8.9O2 ppm (W/E) = ?Flow=2slpm
QE Degradation between 4/11/07 – 12/24/06 (is it real???)• Consistency between Lamp Up/Down Results are Reproducible (+/- 10?)• We know lamp orientation is same on 4/11 - 12/14, at least in E-Lamp Bot. measurement.• In cases where the rel. QE is above 1.0 may be explained by the variability in the measurement and/or lower ppm levels on 4/11• Look for Correlations that could explain these alarming results
G-M
Sh
ort
4/17/07 B.Azmoun, BNL 3
History of Flash Lamp Tests: 12/14/06 – 12/04/06
HBD_E Phtocathode Response: 12/14/07
0.00.20.40.60.81.01.21.41.6
ES0 ES1 ES2 ES3 ES4 ES5 EN0 EN1 EN2 EN3 EN4 EN5
Module
Rat
io:
12/1
4/06
/ 12
/4/0
6
Lamp Bottom
12/14/2006ArVGEM = 100VVref = 5.5V --> Correction: 6.5V/5.5V--> 1.352x16nS --> Correction: 4x16nS/2x16nS--> 0.65New Scope (1Mohm)H2O ppm (W/E) = 16.7/8.9O2 ppm (W/E) = ?Flow=2slpm
12/4/2006Ar
VGEM = 100V
Vref = 6.5V
4x16nS + 18" RG59
New Scope (1Mohm)
H2O ppm (W/E) = 4.5/10.6
O2 ppm (W/E) = 7.9/6.9
Flow=2slpm
Results are consistent btw 12/14 and 12/4 No QE degradation• Before CF4 Flow• Before HV ON
HBD_W Phtocathode Response: 12/14/07
0.00.20.40.60.81.01.21.41.6
WS0 WS1 WS2 WS3 WS4 WS5 WN0 WN1 WN2 WN3 WN4 WN5
Module
Rat
io:
12/1
4/06
/ 12
/4/0
6
Lamp Bottom
4/17/07 B.Azmoun, BNL 4
History: 12/04/07 - 10/18/07
HBD_E Phtocathode Response: 12/4/07
0.0
0.5
1.0
1.5
ES0 ES1 ES2 ES3 ES4 ES5 EN0 EN1 EN2 EN3 EN4 EN5
Module
Rat
io:
12/4
/06
/ 10/
18/0
6
Lamp Top
Lamp Bottom
12/4/2006 (BNL)ArAssumed:VGEM = 100VVref = 6.5V4x16nS + 18" RG59New Scope (1Mohm) -->Few % diff. btw old&newH2O ppm (W/E) = 4.5/10.6O2 ppm (W/E) = 7.9/6.9Flow=2slpm
10/18/2006 (SUNY SB)ArVGEM = 100VVref = 6.5V4x16nS + 18" RG59Old Scope (1Mohm)H2O ppm (E)~20.5 O2 ppm (E)~3.1 Flow~6slpm ???
Comparison of PC response at SUNY SB and BNL• Clear correlation btw sectors along phi impliessome systematic error like a difference in lamp Orientation in the two measurements
4/17/07 B.Azmoun, BNL 5
History: 10/18/06 - 10/17/06
HBD_E Phtocathode Response: 10/18/07
0.00.20.40.60.81.01.21.41.6
ES0 ES1 ES2 ES3 ES4 ES5 EN0 EN1 EN2 EN3 EN4 EN5
Module
Rat
io:
10/1
8/06
/ 10
/17/
06
Lamp Top
Lamp Bottom
10/18/2006 (SUNY SB)ArVGEM = 100VVref = 6.5V4x16nS + 18" RG59Old Scope (1Mohm)H2O ppm (E) ~20.5O2 ppm (E) ~3.1 Flow~6lpm ???
10/17/2006 (SUNY SB)ArVGEM = 100VVref = 6.5V4x16nS + 18" RG59Old Scope (1Mohm)H2O ppm (E) = 20.5O2 ppm (E) = 3.1Flow~6lpm ???
The consistency in results here (where nothing has presumably changed in 2 days) makes a statement about the stability/reproducibility of the lamp intensity this is the best we can do since we don’t have a lamp monitor.
4/17/07 B.Azmoun, BNL 6
Correlations: GEM Resistor Values
Top Resist. Value Vs Reduction in QE
0.000
0.500
1.000
1.500
2.000
0 20 40 60 80
Resist. Value [Mohm]
Rati
o o
f R
esp
on
se t
o
Fla
sh
Lam
p:
(4/1
1/0
7 /
12/2
4/0
7)
Lamp_Bot.
Lamp_top
Mid Resist. Value Vs Reduction in QE
0.000
0.500
1.000
1.500
2.000
0 5 10 15 20 25
Resist. Value [Mohm]
Rati
o o
f R
esp
on
se t
o
Fla
sh
Lam
p:
(4/1
1/0
7 /
12/2
4/0
7)
Lamp_Bot.
Lamp_top
Bot. Resist. Value Vs Reduction in QE
0.000
0.500
1.000
1.500
2.000
0 10 20 30
Resist. Value [Mohm]
Rati
o o
f R
esp
on
se t
o
Fla
sh
Lam
p:
(4/1
1/0
7 /
12/2
4/0
7)
Lamp_Bot.
Lamp_top
0 = inf.
Hypothesis: Larger resistor values compensate for (extra) corona current, which may damage the CsI.
The top GEM, likely the most important, shows little correspondence btw Resistor values and Flash lamp response (higher resis. values even correspond to a ratio ~1.0)
4/17/07 B.Azmoun, BNL 7
CsI Thickness
CsI Thickness Vs Lamp Response
0.0000.2000.4000.6000.8001.0001.2001.4001.600
300 310 320 330 340 350 360 370 380
CsI Thckness [nm]
Ra
tio
of
Re
sp
on
se
to
F
las
hL
am
p:
(4/1
1/0
7 /
12
/24
/07
)
Lamp Top
Lamp Bottom
Hypothesis: Thinner CsI layers are damaged more readily by harmful mechanism responsible for diminished response of PC’s.
There is no obvious correspondence btw CsI thickness and Flash Lamp Response
4/17/07 B.Azmoun, BNL 8
Abs. # of Trips
Abs. # Trips Vs Lamp Response
0.0000.2000.4000.6000.8001.0001.2001.4001.600
0 200 400 600 800 1000 1200
Abs. # of Trips on Each Module
Ra
tio
of
Re
sp
on
se
to
F
las
hL
am
p:
(4/1
1/0
7 /
12
/24
/07
)
Lamp Top
Lamp Bottom
Hypothesis: Damage incurred by the PC’s is proportional to the absolute number of trips sustained by the GEM module.
There is no obvious correspondence btw the abs. # of trips and Flash Lamp Response
4/17/07 B.Azmoun, BNL 9
Enhanced Gain through Photon Feedback?
Module Gain Vs Reduction in QE
0
1000
2000
3000
4000
5000
6000
0.000 0.200 0.400 0.600 0.800 1.000 1.200
Ratio of Response to Flash lamp: (4/11/07 / 12/24/06)
Abs
. Gai
n @
Vin
=350
0V(M
IPs)
W_Lamp Bot.
W_Lamp Top
E_Lamp Bot.
E_Lamp Top
Hypothesis: Photon Feedback is responsible for the enhanced gain observed for many HBD modules, and thus should correlate with PC QE.
There is no obvious correspondence btw the gain of the HBD modules and Flash Lamp Response
Gotta keep looking…any ideas?
4/17/07 B.Azmoun, BNL 11
Gas Trans. w/ HBD in Bypass Mode
As suspected, the heightened H2O/O2 levels observed in the return gas from the HBD is coming from the HBD itself.