IAC 2-29-08

DC setup

This time the Sense wire HV is set to 1500 to start

90/10 ArCo2

HV settings
Wire	Volts	current ([math]\mu[/math]A)
Sense	1500
Field	-750
Guard	750

DC preamp at 5.6 Volts

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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 1 kG magnet placed after the drift chambers deflects charged particles onto a large scintillator paddle. A coincidence is required between the two scintillators.

Increased beam energy from 10 MeV to 12 MeV due to expected energy loss in front scintillator.

Runs

A

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

B

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	1456
Field	729
Guard	731

Run #	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
448	Beam turned off, Pedestal run, Sense wire at 1450 Volts, Translator Power supply Off