1OSU 9/7/03

Radioactive Source Tests at OSU

Our source tests are made using three Cs137 sources10C sources (~15 years old, t1/2 Cs137=30.2yrs)Cs137 gives off:

e’s (0.51MeV/94%, 1.2MeV/6%)’s (0.662 MeV/85%)

We did two types of sources tests“scan” test (V=5700V) moved the 3 sources sources (by hand) ~1 cm/sec“long term” test (V=5500V) let a source sit in same location on tube for > 8hrs

Set HV and monitor the current using CAEN system

Tests were performed on large cell tubes 10,12,13

All source tests were done using ZEUS gas mix

2OSU 9/7/03

Sources test setup

Cs source

Cs source

A Cs source

The bar holding the 3sources was moved by hand along the wire ~1 cm/s

3OSU 9/7/03

Cs137 Scan Tests

Each wire was scanned with a source.Initial Study found: 16 wires “ok” 8 wires suspect

types of Problems: 1) I increases in a few regions of wire

tube 10, wires 2, 62) I > 1A over the length of the wire

tube 10, wires 3, 4, tube 12 wire 4

3) I jumps up to > 1A over a region of the wire tube 12 wires 5, 7, tube 13 wire 2happens near the HV end of the tube

OK=low current, I<~1A uniform along wire

All 8 wires looked OK after a second scan ! Cycled HV, waited a few minutes and scanned

V=5700V

EXAMPLES on FOLLOWING PAGES

NOTE: on scan plots “400” is the voltage input end of tube

4OSU 9/7/03

Scan tests

Tube 10, Wire 6 (second pass)

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Cu

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Tube 10, Wire 6

Tube 10, Wire 6

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Tube 10, Wire 6

Tube 10 wire 6“Problem #1”

First scan Second scan

“400” is the voltage input end

“hot” regions

5OSU 9/7/03

Scan Tests

Tube 10, Wire 4

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10-Current

Tube 10, Wire 4 (second pass)

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Cu

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Tube 10, Wire 4

Tube 10 wire 4“Problem #2”

First scan I>1A Second scan I<200nA

“400” is the voltage input end

1A

6OSU 9/7/03

Scan test

Tube 12, Wire 5

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Cu

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Tube 12, Wire 5

Tube 12, Wire 5 (second pass0

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Cu

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Tube 12, Wire 5

First scan: I jumps >1A Second scan: I<1A

Tube 12 Wire 5“Problem # 3”

“400” is the voltage input end

7OSU 9/7/03

9/8 Scan Test

Tube 10 Wire 2 (9/8)

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1 12 23 34 45 56 67 78 89 100 111 122 133 144 155 166 177 188 199 210 221 232 243 254 265 276 287 298 309 320 331

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Tube 10 Wire 3 (9/8)

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1 13 25 37 49 61 73 85 97 109 121 133 145 157 169 181 193 205 217 229 241 253 265 277 289 301 313 325 337 349 361

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Tube 10 Wire 4 (9/8)

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1 13 25 37 49 61 73 85 97 109 121 133 145 157 169 181 193 205 217 229 241 253 265 277 289 301 313 325 337 349

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Cu

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Series1

Tube 10 Wire 6 (9/8)

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1 13 25 37 49 61 73 85 97 109 121 133 145 157 169 181 193 205 217 229 241 253 265 277 289 301 313 325 337 349

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Cu

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8OSU 9/7/03

9/8 Scan Test

Tube 12, Wire 1 (9/8)

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1 13 25 37 49 61 73 85 97 109 121 133 145 157 169 181 193 205 217 229 241 253 265 277 289 301 313 325 337 349

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Cu

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Series1

Tube 12 Wire 4 (9/8)

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1 12 23 34 45 56 67 78 89 100 111 122 133 144 155 166 177 188 199 210 221 232 243 254 265 276 287 298 309 320 331

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Tube 12 Wire 5 (9/8)

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1 13 25 37 49 61 73 85 97 109 121 133 145 157 169 181 193 205 217 229 241 253 265 277 289 301 313 325 337 349 361

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Tube 12 Wire 7 (9/8)

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1 13 25 37 49 61 73 85 97 109 121 133 145 157 169 181 193 205 217 229 241 253 265 277 289 301 313 325 337 349

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Cu

rre

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9OSU 9/7/03

9/8 Scan Test

Tube 13 Wire 1 (9/8)

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1 13 25 37 49 61 73 85 97 109 121 133 145 157 169 181 193 205 217 229 241 253 265 277 289 301 313 325 337 349

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Cu

rre

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Series1

Tube 13 Wire 2 (9/8)

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1 12 23 34 45 56 67 78 89 100 111 122 133 144 155 166 177 188 199 210 221 232 243 254 265 276 287 298 309 320 331

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Tube 13 Wire 5 (9/8)

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1 13 25 37 49 61 73 85 97 109 121 133 145 157 169 181 193 205 217 229 241 253 265 277 289 301 313 325 337 349 361

Series1

Tube 13 Wire 6 (9/8)

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1 13 25 37 49 61 73 85 97 109 121 133 145 157 169 181 193 205 217 229 241 253 265 277 289 301 313 325 337 349

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Cu

rre

nt(

nA

)Series1

10OSU 9/7/03

Lateral Scan (3 tubes)Lateral Scan

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1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64 67 70 73 76 79 82 85 88

Tube 12 D

Tube 12 C

Tube 12 B

Tube 12 A

Tube 13 D

Tube 13 C

Tube 13 B

Tube 13 A

Tube 10 D

Tube 10 C

Tube 10 B

Tube 10 A

11OSU 9/7/03

“Long Term” Source Test

We let a source sit in one spot on tube for > 8hrs and monitored the currentLowered voltage to 5500V so current in a cell would typically be 200-300nAWe have sampled 12 spots so far

4 spots on each tube, ~L/5, 2L/5, 3L/5, 4L/5

Current is very stable in each region

HOWEVER…..

12OSU 9/7/03

Source Induced Current !

If I put a source on the purple dot the current rises from<100nA to > 3A in 30-60 seconds !! The effect is reproducible with HV > 5700VCould this be a problem with the wire termination or resistor pc board??