IAC 2-29-08
Leap Day run
DC setup
This time the Sense wire HV is set to 1500 to start
90/10 ArCo2
| HV settings | ||
| Wire | Volts | current (A) |
| Sense | 1500 | |
| Field | -750 | |
| Guard | 750 | |
DC preamp at 5.6 Volts
Beam Line Configuration
A 1/4 inch diameter collimater is placed in the experimental cell just after a Helium bag inserted in the wall. A 2 cm thick scintillator is place over the beam downstream side of the collimator aligned using a laser. A 3mm diameter collimator is placed just before a 1 kG magnet that is after the DC. The 1 kG magnet placed after the drift chambers deflects charged particles onto a large scintillator paddle.
A logic circuit was set up to allow for the following trigger configurations
- gun AND (Front Scint OR Rear Scint)
- gun AND (Front Scint AND Rear Scint)
Increased beam energy from 10 MeV to 12 MeV due to expected energy loss in front scintillator.
Data was taken with
- Metallica's output is recorded in the odd ADC numbered ntuple entries (ADC1, ADC3,ADC5, ...)
- Plastika's output is recorded in the EVEN ADC numbered ntuple entries (ADC2,ADC4,ADC6,...)
- Wire # 4 is recored in ADC7 for Metalica and 8 for Plastica.
- Wire # 3 is beam upstream
- The DAQ trigger was gun AND (Front Scint OR Rear Scint). The back scintillator output is in the data stream (ADC14 in C-convention, ADC15 in ntuple) so A software coincidence will be used. The rate with ANDing all signals was time prohibitive.
Runs
Run Description
Decided to increase beam current until up to 10% of events in front scintilaltor pass through magnet after drift chamber and hit back scintillator. Ran in OR mode so a software coincidence can be formed based on measurement in ADC15 (ADC14 in C convention).
| Run # | Description |
| 431 | 0" from feedthrough , Sense wire at 1450 Volts, Gun voltage at 1.76 |
| 432 | 0" from feedthrough , Sense wire at 1500 Volts, Metalica (ADC6; C-convention) sees overflows and looks hot on scope compared to Plastika (ADC8: in ntuples),Gun voltage at 1.76 |
| 433 | -1" from feedthrough (beam should miss chamber), Sense wire at 1500 Volts, I see peds in Plastika but not metalica (Metalica is beam upstream of Plastika), The overflows are due to DC voltage/Gain being too high ,Gun voltage at 1.76 |
| 434 | 1" from feedthrough , Sense wire at 1500 Volts, Gun voltage at 1.76 |
| 435 | 2" from feedthrough , Sense wire at 1500 Volts, Gun voltage at 1.76 |
Histograms
Change voltage on DC to values used on last day of January run 90/10 ArCo2
Drift Chamber HV
| HV settings | ||
| Cable # | Volts | Current (ma) |
| Sense | +1450 | |
| Field | -725 | |
| Guard | +725 | |
| Front Scint | -1127 | 30 mV threshold |
| Rear Scint | -1153 | 81 mV Threshold |
| Run # | Scint counts > 70 channels (ADC15) | Scint counts/trigger | Description |
| 436 | 2" (-100k) from feedthrough , Sense wire at 1450 Volts, Gun voltage at 1.76, Less overflows in Metalica ADC | ||
| 437 | 4" (-200k) from feedthrough , Sense wire at 1450 Volts, Gun voltage at 1.76 | ||
| 438 | 1" (-50k) from feedthrough , Sense wire at 1450 Volts, Gun voltage at 1.76, visually inspected position and confirmed it was 1" from feedthrough | ||
| 439 | 0.5" (-25k) from feedthrough , Sense wire at 1450 Volts, Gun voltage at 1.76 | ||
| 440 | 0.25" (-12.5k) from feedthrough , Sense wire at 1450 Volts, Gun voltage at 1.76 | ||
| 441 | 0.0625" (-9.375k) from feedthrough , Sense wire at 1450 Volts, Gun voltage at 1.76 | ||
| 442 | -5" (+240.625k) from feedthrough , Sense wire at 1450 Volts, Gun voltage at 1.76, try to get electrons missing chamber, use ADC14 to cut on electrons hitting back scintillator. ADC7 should be zero if its really an electron. | ||
| 443 | -3" (+140.625k) from feedthrough , Sense wire at 1450 Volts, Gun voltage at 1.76 | ||
| 444 | -2" (+90.625k) from feedthrough , Sense wire at 1450 Volts, Gun voltage at 1.76 | ||
| 445 | -0.5" (+15.625k) from feedthrough , Sense wire at 1450 Volts, Gun voltage at 1.76 | ||
| 446 | -0.25" (+3.125k) from feedthrough , Sense wire at 1450 Volts, Gun voltage at 1.76 | ||
| 447 | Beam turned off, Pedestal run, Sense wire at 1450 Volts, Translator Power supply On, Preamp Power supply at 5.6 V, trigger: gun OR either scintillator | ||
| 448 | Beam turned off, Pedestal run, Sense wire at 1450 Volts, Translator Power supply Off | ||
| 449 | Beam turned off, Pedestal run, Sense wire at 1450 Volts, Translator Power supply Off, DC preamp off | ||
| 450 | Beam turned off, Pedestal run, Sense wire at 1450 Volts, Translator Power supply Off, DC pramp off, Now just trigger on gun pulse, DC HV off |
| Run # | r436 | r437 | r438 | r439 | r440 | r441 | r442 | r443 | r444 | r445 | r446 |
| Distance(inch) | 2" | 4" | 1" | 0.5" | 0.25" | 0.0625" | -5" | -3" | -2" | -0.5 | -0.25" |
| ADC15 |   |
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| ADC3 Mean Value | ADC4 Mean Value | ADC5 Mean Value | ADC6 Mean Value | ADC7 Mean Value | ADC8 Mean Value | ADC9 Mean Value | ADC10 Mean Value | ADC11 Mean Value | ADC12 Mean Value | |
| Distance(inch) | ||||||||||
| 2" | 311.7+/-8.9 (607.4) | 452.4+/-8.8 | 457.6+/-11.4 (781.3) | 986.4+/-4.0 (996.6) | 314.8+/-7.5 (582.8) | 342.6+/-8.7 (602.8) | ? | 336.7+/-7.4 (613.6) | 344.9+/-9.4 (634.8) | 477.3+/-10.1 (773.6) |
| 4" | 459.2+/-16.0 (848) | 619+/-14.4 (1033) | 667.2+/-18.4 (1109) | 1029+/-4.8 (1037) | 413+/-10.9 (764.3) | 490.5+/-13.7 (896.3) | ? | 451.3+/-12.6 (803.9) | 502.5+/-14.3 (891.4) | 647.7+/-15.9 (1040) |
| 1" | 477.6+/-17.9 (933.1) | 617.9+/-14.0 (997) | 666.5+/-17.5 (1049) | 1116+/-6.3 (1122) | 448.1+/-11.8 (834.2) | 509.4+/-16.1 (912.8) | ? | 478.8+/-12.8 (837.5) | 501+/-16.4 (930) | 644.7+/-16.1 (1065) |
| 0.5" | 501.5+/-17.2 (9483) | 655.2+/-16.0 (1045) | 641.2+/-18.2 (1085) | 1079+/-5.0 (1082) | 465.5+/-11.8 (844.3) | 542.7+/-17.1 (936.2) | ? | 481.1+/-13.6 (834.2) | 536.9+/-14.7 (918.2) | 662+/-16.5 (1070) |
| 0.25" | 437.6+/-15.0 (849.3) | 587.1+/-14.0 (1012) | 653.5+/-17.9 (1074) | 1011+/-4.6 (1021) | 409.6+/-11.8 (770.6) | 481.9+/-15.1 (864.1) | ? | 450.3+/-13.1 (773.3) | 478.3+/-16.7 (886.7) | 598.2+/-16.0 (1005) |
| 0.0625" | 474.9+/-23.9 (838.8) | 628+/-26.6 (999.2) | 609.1+/-28.9 (1036) | 1021+/-8.2 (1032) | 451.3+/-15.5 (771.1) | 477.7+/-21.4 (902.2) | ? | 467.3+/-24.4 (817.7) | 497+/-24.5 (875.5) | 656.4+/-30.7 (1076) |
| -5" | 138.3+/-9.5 (470.4) | 302.2+/-4.9 (592.1) | 295.9+/-5.6 (606.9) | 788.6+/-3.8 (786.1) | 235.7+/-3.6 (468) | 201.6+/-4.8 (464) | ? | 197.7+/-3.6 (435.8) | 156.1+/-12.6 (497) | 319.3+/-5.0 (606.2) |
| -3" | 67.38+/-14.25 (551.5) | 310.8+/-3.7 (637.5) | 334.1+/-4.6 (692.6) | 732.5+/-1.6 (733.8) | 248.3+/-2.8 (547.7) | 184.4+/-4.8 (535.3) | ? | 187+/-3.5 (497.6) | 210+/-3.9 (564.8) | 332.5+/-3.7 (660.2) |
| -2" | 99.18+/-20.43 (669.9) | 373.5+/-5.7 (763.3) | 415+/-6.6 (830.2) | 750.6+/-2.0 (753.8) | 299.6+/-4.2 (661.4) | 238+/-6.6 (657.7) | ? | 219.9+/-5.2 (580.2) | 235.5+/-7.4 (672.6) | 400.9+/-5.2 (772) |
| -0.5" | 137.7+/-16.5 (695.5) | 400.8+/-5.2 (810) | 455.6+/-6.4 (896.7) | 760.9+/-1.9 (763) | 308.9+/-4.0 (681.5) | 259.9+/-6.5 (699.5) | ? | 238.1+/-5.7 (627.6) | 266.6+/-6.8 (710.8) | 431.2+/-5.2 (829.6) |
| -0.25" | 215+/-16.3 (776.2) | 436.2+/-6.2 (871.1) | 498.3+/-7.5 (966) | 772.7+/-2.1 (777.7) | 349.5+/-5.2 (766.4) | 304.8+/-7.9 (762.1) | ? | 276.8+/-6.3 (674.6) | 309.7+/-8.0 (781.6) | 489.2+/-6.4 (920.7) |
ADC output -vs- distance Plots
- Metalica's output is shown in BLACK and Plastika in RED.
- Wire #2
- Wire #3
- Wire #4
- Wire # 6
Observations
A BIASED fit to Wire #4
A dependence of the DC's measured charge as a function of position was NOT observed; the slopes are consistent with zero. Plastika outputs 50 ADC channels (100 fC / channel) more than Metalica. Is this because it was behind Metalica?
A Landau fit to the charge distributions of Wire 4 for Metalica and Plastika, when the beam is 4 inches away from the feed through, gave a sigma of 122 for Metalica and a sigma of 160 for Plastika. The sigma of Landau fits to Plastika's ADC spectrum were always 30% larger than Metalica as you can see from the histograms above. The exception is at the 2" measurement position in which the sigmas differed by 10%.
Media:Wire_position_ADC3_xmgrace.txt
Media:Wire_position_ADC4_xmgrace.txt
Media:Wire_position_ADC5_xmgrace.txt
Media:Wire_position_ADC6_xmgrace.txt
Media:Wire_position_ADC7_xmgrace.txt
Media:Wire_position_ADC8_xmgrace.txt
Media:Wire_position_ADC10_xmgrace.txt
Media:Wire_position_ADC11_xmgrace.txt
Media:Wire_position_ADC12_xmgrace.txt
Gain change
The histograms below represent a comparison between two runs with different Drift chamber HV settings.
| ADC # | r434_r438 HV = 1500 | r435_r436 HV = + 1450 |
| 15 |  |
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| 4 |  |
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| 5 |  |
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| 6 |  |
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| 7 |  |
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| 8 |  |
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| 10 |  |
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| 11 |  |
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| 12 |  |
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The histograms below have following cut: ADC15>70 and ADC15<100.
| ADC # | r434_r438(ADC15>70 && ADC15<100) | r435_r436(ADC15>70 && ADC15<100) |
| 4 |  |
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| 5 |  |
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| 6 |  |
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| 7 |  |
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| 8 |  |
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| 10 |  |
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| 11 |  |
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| 12 |  |
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Rear Scint Pedestal
| Run # | Scint Histogram | Wire #4 | Description |
| 447 |  |
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Beam turned off, Pedestal run, Sense wire at 1450 Volts, Translator Power supply On, Preamp Power supply at 5.6 V, trigger: gun OR either scintillator |
| 448 |  |
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Beam turned off, Pedestal run, Sense wire at 1450 Volts, Translator Power supply Off |
| 449 |  |
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Beam turned off, Pedestal run, Sense wire at 1450 Volts, Translator Power supply Off, DC preamp off |
| 450 |  |
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Beam turned off, Pedestal run, Sense wire at 1450 Volts, Translator Power supply Off, DC preamp off, Now just trigger on gun pulse, DC HV off |
- Observations
- The pedestal for the last scintilator is below channel 70. There seems to be a lot of noise around channel 150.
- turning the DC amplifier off increases the noise on the line (no more differential amplification).