MiniPrototype CosmicRuns

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Cosmic Coincidences

setup

Setup a cosmic coincidence experiment with two crossed scintillators that have the proto-type drift chambers sandwhiched between them.

Built 4 100 ns long delay cables. 2 for the PMTs and one for sense wire 7 on each of the drift chambers.


The top PMT is in channel 7 of the QDC and channel 16 of the scaler.

The Bottom PMT is on channel 8 of the QDC and channel 7 of the scaler.

Coincidence counts are recorded in channel 2 of the scaler.

Runs

Drift Chamber is off

Run 182: Ran with coincidence module in "OR" mode so if either paddle triggered the ADC was read out

Run 183: Switched coincidence module to "AND" mode and ran overnight.

12/23/07

Drift Chamber turned on with 90/10 ArCO2 and the voltages below

HV settings
Wire Volts current ([math]\mu[/math]A)
Sense 1500 19
Field -800 19
Guard 800 0

Run 204: Scope was plugged into DC output (split signal)

12/24/07

Run 206: Unplugged scope and started this run


Drift Chamber turned on with 90/10 ArCO2 and the voltages below

HV settings
Wire Volts current ([math]\mu[/math]A)
Sense 1500 19
Field -800 19
Guard 800 0


Run206 12-25-07.jpg

I had a bad ribbon cable on plastica. Ignore the results for Plastica. It was just a good pedestal measurement.


It looks like Metalica saw 2/3 of the cosmics seen by the Scintilaltors.

12/27/07

Run 207:

Scope picture of a Cosmic Coincidence event triggered by and AND between the top and bottom scintillator.

CosmicCoincidence 12-27-07 MetalicaCh1.jpg

Drift Chamber turned on with 90/10 ArCO2 and the voltages below

HV settings
Wire Volts current ([math]\mu[/math]A)
Sense 1500
Field -800
Guard 800

CosmicCoincidence r207.jpg


Metalica saw 488 cosmic events while Plastica recorded 494 out of the 739 cosmic events triggered by the scintillator paddles. Assuming [math]\sqrt{N}[/math] counting statistics, I would conclude that the efficiency of Metalica is [math](66 \pm 4)\%[/math] and [math](67 \pm 4)\%[/math] for Plastica when the scintillator paddle is 0.5 cm from the endplate.

12/28/07

Run 208:

Increased Gate width from 200 ns to 1000 ns after realizing that the drift chamber pulses could be that wide. I also removed the 100 ns decay line on sense wire #4 of both chambers. The PMT pulses still have a 100 ns delay line in.


Drift Chamber turned on with 90/10 ArCO2 and the voltages below

HV settings
Wire Volts current ([math]\mu[/math]A)
Sense 1500
Field -800
Guard 800


I saw the ADC peak move up from channel 160 to channel 650 after increasing the gate width. Increase gate width by a factor of 5 and the peak moved up by about a factor of 4.

CosmicCoincidence r208.jpg


Metalica saw 922 cosmic events while Plastica recorded 927 out of the 1361 cosmic events triggered by the scintillator paddles. Assuming [math]\sqrt{N}[/math] counting statistics, I would conclude that the efficiency of Metalica is [math](68 \pm 4)\%[/math] and [math](68 \pm 4)\%[/math] for Plastica when the scintillator paddle is 0.5 cm from the endplate.

12/30/07

Run 209:

I increase the HV on both Drift chamber by 50 Volts (25 Volts on guard and Field wires).

Drift Chamber turned on with 90/10 ArCO2 and the voltages below

HV settings
Wire Volts current ([math]\mu[/math]A)
Sense 1550 94
Field -825 93
Guard 825 0

The GAS bottle is geting low!

It's on order. The shipment should arrive on Wednesday, 2 Jan 2008.


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