MiniPrototype CosmicRuns
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 (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 (A) |
| Sense | 1500 | 19 |
| Field | -800 | 19 |
| Guard | 800 | 0 |
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.
Drift Chamber turned on with 90/10 ArCO2 and the voltages below
| HV settings | ||
| Wire | Volts | current (A) |
| Sense | 1500 | |
| Field | -800 | |
| Guard | 800 | |
Metalica saw 488 cosmic events while Plastica recorded 494 out of the 739 cosmic events triggered by the scintillator paddles. Assuming counting statistics, I would conclude that the efficiency of Metalica is and 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 (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.
Metalica saw 922 cosmic events while Plastica recorded 927 out of the 1361 cosmic events triggered by the scintillator paddles. Assuming counting statistics, I would conclude that the efficiency of Metalica is and 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 (A) |
| Sense | 1550 | 94 |
| Field | -825 | 93 |
| Guard | 825 | 0 |
Top PMT is at -962 Volts and the Bottom PMT is at -1036 Volts.
The GAS bottle is geting low!
It's on order. The shipment should arrive on Wednesday, 2 Jan 2008. -PLC