HRRL 7-31-09

Default HRRL running Conditions

[math]I_{peak}[/math]	Pulse Width	Rep Rate	Energy
8 mA	100 ns	1 Hz	3 MeV

cable names

CH ID	Description
2223A1	Front Scintillator
2223A2	Rear Scintilaltor
2223A3	ADC Gate From counting house to Experimental Cell
2223A4	TDC start pulse from counting house to experimental cell (PMT front + beam Gate)
2223A5	Coincidenc between front + rear Scint + Gun pulser to scaler channel 8
2223A6	Metalica sense wire 4
2223A7	Delayed rear PMT pulse to ADC
2223A8	Plastica sense wire 4
2223A9	Plastica to scaler channel 4
2223A10	Front scintillator to ADC
2223A11	Metalica scaler channel 1
2223A12	DAQ trigger

DAQ Ntuple names

Ntuple Variable	Description
ADC5	Front Scintilator
ADC1	Metalica sense wire 4
ADC16	Rear Scintilator
ADC13	Plastica sense wire 4
TDC1	Metalica sense wire 4
TDC3	Plastika sense wire 4

ADC + Scaler + TDC + V1495

Run Number	Distance to Metallica's Feedthrough tip (cm)	Metalica scaler counts scaler ch 4	Plastika Scaler Counts scaler ch 1	Rear PMT + Front PMT + Gun Pulse Counts Scaler Ch 8	HV S:F:G	Discriminator (mV)	Metalica counts/PMT+Gun pulse
1263	19		0		1400:-700:980	50

TDC Measurements

TDC Calibration

Second pulse width is 80 ns.

Conclusion

In order to get actual time between the start and the stop pulse, one needs to subtract the width of the second signal. In this case it was 80 ns.

Run Number	Scope Image	TDC Histogram	Calculated Time (ns)	Time measured on the scope ns (between the fall of the first pulse and rise of the second pulse)	Time measured on the scope ns (between the fall of the first pulse and fall of the second pulse)	Pulse width (ns)
1238			169.5	160	80	80
1239			135.7	130	50	80
1240			111.5	110	30	80
1328			122	120	-50	170

Actual Measurements

We had runs for different beam energy (2 && 4 MeV) and collimator size(~0.2 && ~0.8 cm).
Table below shows TDC measurements for all cases for Metalica and Plastika.

Run Number	Beam Energy (MeV)	Collimator size ~ (cm)	HV S:F:G	Discriminator Threshold (mV)	TDC Histogram
1296	2	0.8	1400:-700:980	50
1297, 1298 && 1299	4	0.8	1400:-700:980	50
1304 && 1305	4	0.2	1400:-700:980	50
1306	2	0.8	1400:-700:980	50

Plastika - 120 ns, Metalica - 170 ns.

Example

For Metalica on the TDC histogram mean value is 307, but the time between the pulse of the PMT+RFGate and Metalica is 307-170=137 ns. For Plastika it is 226.4-120=106.4ns. So time difference between this two pulses is around ~30 ns(the same on the scope).

The drift velocity for electrons in drift chambers is ~ 50μm / ns. Media:mestayer.pdf [edit] Calculated result using TDC data

The size of the drift chamber cell is 0.86 cm.

[math]Time = \frac{1000 {\rm ns}}{2^{12}{\rm chan}} \times {\rm chan} ns[/math]

[math]{t_{Drift}}^{maximum} = \frac{CellSize}{v_{Drift}} = \frac{0.86 \times 10^{-2} m}{50 \mu m/ns} = 172 ns[/math]

So the maximum drift time in DCs(Metalica && Plastika) can be 172 ns.

Our data(above example) shows that for Metalica it is ~137+/-100ns and for Plastika it is ~106+/?

VFAT runs

4 MeV beam energy, big collimator.

GEM HV settings: [math]V_{Drift}/V_{GEM}[/math]=3425/3125.

Run Number	Card 1 Threshold	Card 2 Threshold
1300	151	116
1301	153	118
1302	155	120
1303	157	122

GEM HV settings: [math]V_{Drift}/V_{GEM}[/math]=3425/3125.

4 MeV beam energy, small collimator.

Run Number	Card 1 Threshold	Card 2 Threshold
1305	151	124

File:Pb Attenuation Photon.pdf

Experimental Setup