MiniPrototype SinglesCosmicRuns 2008
Goal
Use singles Cosmic events to measure rate differences between Metalica and Plastica
Apparatus
- Plastica and Metalica are stacked on top of each other. High Voltage and ionization gas are connected in parallel.
- A discriminator is connector to the amplified output (an on board preamp and the VPI Post amp) of sense wire 4.
- The discriminator output is connected to a VME scaler.
Proposed Tests
- Measure the singles rate as a function of DC high voltage
- Measure the singles rate as a function of Discriminator Threshold
9-05-2008
The DC high voltage is on. The DC outputs of Plastika and Metalica from sense wire 4 are connected to the Model 777 Octal Variable Gain Amplifier.
HV settings | ||
Wire | Volts | |
Sense | 1450 | |
Field | -725 | |
Guard | 725 |
Scope picture below shows the Noise level on the DC measured in infinite persist time mode.
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Scope pictures representing the cosmic signals from Plastika and Metalica(Amplifier is connected)
- Plastika
- Metalica
Rate -vs- Discriminator Threshold
Gas is ArCo2 . 75/25 mixture
HV settings | ||
Wire | Volts | |
Sense | 1700 | |
Field | -850 | |
Guard | 850 |
Threshold (mV) | Metalica (Events/hr) | Plastika (Events/hr) | Coincidence |
300 | 701 | 627 | |
300 | 560 | 570 | |
310 | |||
325 | 32 | ||
350 | |||
400 | 31 |
Gas is ArCo2 . 90/10 mixture
HV settings | ||
Wire | Volts | |
Sense | 1450 | |
Field | -725 | |
Guard | 725 |
The scope picture below was taken to illustrate the noise levels on the DC signals after amplification just before disrimination. Previous measurements suggested that the sense wire signal noise had an RMS of about 10 mV. The phillips amplifier doubles this noise RMS. The amplitude of the noise is about 30 mV.
Threshold (mV) | Metalica (Events/hr) | Plastika (Events/hr) | Coincidence (Event/hr) |
100 | 1915 | 1912 | 27(90) |
100 | 2148 | 1799 | 13(36) |
100 | 1885 | 1758 | 13(37) |
100 | 2012 | 1912 | 32(91) |
100 | 1905 | 1754 | 8(25) |
150 | 671 | 588 | 8(14) |
150 | 645 | 596 | 11(11) |
150 | 634 | 596 | 19(19) |
150 | 629 | 563 | 13(13) |
150 | 634 | 550 | 5(5) |
175 | 361 | 358 | 27(20) |
175 | 380 | 329 | 14(14) |
175 | 396 | 329 | 15(14) |
175 | 391 | 344 | 10(10) |
200 | 286 | 256 | 28(25)? |
200 | 291 | 232 | 6(4) |
200 | 291 | 251 | 7(6) |
225 | 183 | 168 | 5(4) |
225 | 193 | 180 | 6(6) |
250 | 122 | 120 | 34(2) |
300 | 93 | 88 | 20(2) |
350 | 74 | 60 | 27(3) |
Threshold (mV) | Metalica (Events/hr) | Plastika (Events/hr) | Coincidence (Event/hr) |
100 | |||
150 | |||
175 | |||
200 | |||
225 | |||
250 | 122 | 120 | |
300 | 93 | 88 | |
350 | 74 | 60 | 27(3) |