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 /

12/2

4/06

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 /

12/2

4/06

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

Sho

rt

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: 1

2/14

/06

/ 12/

4/06

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

12/4/2006ArVGEM = 100VVref = 6.5V4x16nS + 18" RG59New Scope (1Mohm)H2O ppm (W/E) = 4.5/10.6O2 ppm (W/E) = 7.9/6.9Flow=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: 1

2/14

/06

/ 12/

4/06

Lamp Bottom

4/17/07 B.Azmoun, BNL 4

History: 12/04/07 - 10/18/07HBD_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: 1

2/4/

06 /

10/1

8/06

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 - 10/17/06HBD_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: 1

0/18

/06

/ 10/

17/0

6

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]

Ratio

of R

espo

nse

to

Flas

hLam

p: (4

/11/

07 /

12/2

4/07

)

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]

Ratio

of R

espo

nse

to

Flas

hLam

p: (4

/11/

07 /

12/2

4/07

)

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]

Ratio

of R

espo

nse

to

Flas

hLam

p: (4

/11/

07 /

12/2

4/07

)

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]

Rat

io o

f Res

pons

e to

Fl

ashL

amp:

(4/1

1/07

/ 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

Rat

io o

f Res

pons

e to

Fl

ashL

amp:

(4/1

1/07

/ 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

0100020003000400050006000

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=

3500

V(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.