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

1. Measure the singles rate as a function of DC high voltage
2. 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.
300px

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 [math]\pm \sqrt{\frac{1.04194}{730}}[/math]	627 [math]\pm \sqrt{\frac{1.04194}{653}}[/math]
300	560 [math]\pm \sqrt{\frac{1.01639}{569}}[/math]	570 [math]\pm \sqrt{\frac{1.01639}{579}}[/math]
310	[math]592 \pm 11[/math]	[math]500 \pm 24[/math]
325	[math]528 \pm 65[/math]	[math]465 \pm 30[/math]	32
350	[math]421 \pm 48[/math]	[math]379 \pm 40[/math]
400	[math]305[/math]	[math]235[/math]	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	90
100	2148	1799	36
100	1885	1758	37
100	2012	1912	91
100	1905	1754	25
150	671	588	14
150	645	596	11
150	634	596	19
150	629	563	13
150	634	550	5
175	361	358	20
175	380	329	14
175	396	329	14
175	391	344	10
200	286	256	25
200	291	232	4
200	291	251	6
225	183	168	4
225	193	180	6
250	122	120	2
300	93	88	2
350	74	60	3

Threshold (mV)	Metalica (Events/hr)	Plastika (Events/hr)	Coincidence (Event/hr)
100	[math]1973 \pm 98[/math]	[math]1827 \pm 71[/math]
150	[math]643 \pm 15[/math]	[math]583 \pm 17[/math]
175	[math]382 \pm 13[/math]	[math]340 \pm 12[/math]
200	[math]289 \pm 2[/math]	[math]246 \pm 10[/math]
225	[math]188 \pm 5[/math]	[math]174 \pm 6[/math]
250	122	120
300	93	88
350	74	60

With preamp and Post amp on

Sense wire #4 from Metalica comes out of VPI post amp channel #10. VPI channel #15 goes into ADC channel #3

Sense wire #4 from Plastika comes out of VPI post amp channel #15. VPI channel #15 goes into ADC channel #6

Voltage on preamp is 6.0 V.

HV settings
Wire	Volts
Sense	1500
Field	-750
Guard	750

Compare Phillips output and VPI postamp output

Noise level of Plastika and Metalica
Plastika

Metalica

Threshold Phillips777(mV)	Metalica (Events/hr)	Plastika (Events/hr)	Threshold VPI PostAmp(mV)	Metalica (Events/hr)	Plastika (Events/hr)
300	143	144	1000	245	160
300	150	145	1000	223	153

Go Back