GEM and Mini Prototype DC Cosmics Run

12-22-08

Insert image showing geometry of the apparatus, distances, scintillator locations, 
paddle sizes, and the solid angle when two scintillators are in coincidence.

Setting Electronics

Using The Stanford Pulse Generator, Model DG535, four identical pulses were injected into the GEM(I mean output),, two PMTs and DC(first Metalica and then Plastika).

12-23-08

Mini DCs and GEM detectors are sandwiched between the two PMTs. The top scintillator is operated at 1050 Volts and bottom one-1000 Volts.

HV settings on GEM detector: [math]V_{Drift}=3300[/math] Volts and [math]V_{GEM}=3000[/math] Volts
HV settings on DCs: Sense=1450 Volts, Field=-725 Volts && Guard=724 Volts.

The coincidence pulse from two PMTs is used as a trigger and gate for GEM and DCs.

The PreAmp voltage on DCs is set to 6.4 Volts, the pulse form DC is amplified using PostAmplifier(amplification is on maximum). The TDC output of the amplified pulse is discriminated using the Leading Edge Discriminator and putted to the NIM-ECL converter, which than goes to the TDC(VME). The ADC output of the PostAmp was used for ADC(VME).

1-5-08

The GEM ADC measurements from the last cosmic run do not show a GEM signal while the DC has a clear ADC signal. Is the Gate correct?

I only saw one GEM signal from Trig out when triggereing the scope on the bottom scintillator. It looked like

Some drift chamber signals start hat before the gate suggesting there is too much delay on the gate line.

I observed more DC signals from channel 7 than GEM trigger signals when I triggred the scope on the bottom scintilator. Could the GEM gain/efficiency be substantially lower than the DC? When running with HRRL electrons we should probably set the HV for each detector so they have the same rate.

Changed integrate gate from 150 ns to 300ns

Increased GEM HV 25 volts from 3325/2925 to 3350/2950