# Analog Signals

He3 Tube neutron detectors are 52 cm long and 1.5 cm radius cylinders, 1200 Volts with EG&G (ortec) pre amp Model 142PC (Serial #787)

Although 1200 Volts is applied to the Ortec Preamp, only 350 Volts is established on the "input" port where the Tube is plugged in. If 1250 Volts is applied, then 366 Volts is observed.

For the TENNELEC you need to apply 1650 Volts to get 362 applied to the Tube

The TENNELEC signal output at 1550 Volts has less noise with signal at about 30 mV compared to the output of the ortec. There is a230 mV DC offset on the output

# Output measured by CAEN V785N Peaks sensing ADC

Using a Cf-252 source positions on a shelf below the He-3 tube covered by 2" thick virgin Poly and set to 1250 Volts. Using Ortec pre-amp 142PC serial # 787.

The Timing output of the preamp was sent to an Ortec Timing filter amplifier to be inverted. The Gain was set to x10 and the integrate set to 20 ns.

The Energy output was sent to an Ortec Spectroscopy amplifier model 672. The gain was set to x10 and the shaping time set to 2usec.

Run 6245 has a Cf-252 source place on a shelf approximately 80 cm below the He-3 tube that had been encased in 2" thick virgin poly.

Run 6246 recorded the background observed without the source over a 19 hour period.

The expectation from File:GE ReuterStokes.pdf is

Performed another measurement of the He-3 tube using the Cf-252 source. I used the bipolar output of the ORTEC spec AMP model 672. The He-3 tube is surrounded by a 2" thick layer of virgin poly. The virgin poly is then encased in a 2" layer of lead. The Cf-252 source was placed directly on top of the lead. Below is a measurement recorded in run #6295 taken over a 7 minute period Run #6596 was taken over a three day period.

If I normalize the rate per cm^2 of detector (project the cylinder to a 52 cm x 3 cm rectangle = 156 cm^2)

Cosmic rays produce 10^{3}/cm^2/sec

# Beam Tests

5/16/17: 44 MeV machine was being tuned at 2 MeV so I used the nCorHe3 configuration to look at the He-3 output when there shouldn't be neutrons in the Hall.

Run 6297: Timing AMp =2 Postamp to PADC set to gain of 10

Run 6298: Timing AMp=2 Postamp to PADC set to gain of 50

Run 6299: Timing AMp=adjusting during run Postamp to PADC set to gain of 50

Run 6300: Timing AMp=8 Postamp to PADC set to gain of 50

A CFD threshold of -181 mV will keep the He-3 tube timing amp from firing when the 44 MeV machine is running. The Cf-252 source rate was 200 +/- 40 Hz at this CFD setting.

For TDC (Window is 1500 nsec wide)

FF->Draw("(TDC.TDC1190[1][28]-TDC.TDC1190[1][31])*0.1")

Check Timing with FF->Draw("(TDC.TDC1190[2][31]-TDC.TDC1190[1][31])*0.1")

The above should be about 200 ns

Run 6301, ran in PAA configuration with Cf 252 source on top of detector

## 5/23/17

32 MeV Beam 50 mA current

The He-3 tube is plugged into a scaler that counts all pulses (not just the ones during the beam gate).

 Run# Configuration 6310 710 +/- 20 Hz neutron rate during first 15 minutes, then 870 +/- 20 Hz neutron rate during second 15 minutes, UV broadband pass filter 6311 840 +/- 20 Hz neutron rate during first 15 minutes, then Hz neutron rate during second 15 minutes, 390 nm Filter 6313 390 nm Filter, HV = 1800 ( the HV has changed from run 6311) 6314 320 nm Filter 6315 320 + 330 nm Filter

the He-3 rate definitely increases during the irradiation (probably due to Hall Activity increasing)

## 5/24/17

32 MeV Beam 150 mA current 100 ns wide beam no beam stop, 4 mm thick (12 g) Yttrium in.

The He-3 tube is plugged into a scaler that counts all pulses (not just the ones during the beam gate).

the He-3 rate definitely increases during the irradiation (probably due to Hall Activity increasing)

## 5/25/17

32 MeV Beam 150 mA current 100 ns wide beam no beam stop

The He-3 tube is plugged into a scaler that counts all pulses (not just the ones during the beam gate).

 Run# Configuration 6346 320 nm Pass filter 6347 320 nm Pass filter, changed pulse width between 100 and 800 ns 6348 320 nm Pass filter, change amplitude 6353 320 nm Pass filter plus UV filter PMT small aperture in the hole, change beam current from 100 to 200 to check normalization 6354 320 nm Pass filter, plus UV filter PMT small aperture in the hole 6355 320 & 330 nm Pass filter, plus UV filter PMT small aperature in the hole 6356 390 nm Pass filter, plus UV filter PMT small aperture in the hole, 6357 390 nm Pass filter, plus UV filter PMT small aperture in the hole, No change 6358 390+320 nm Pass filter, plus UV filter PMT small aperture in the hole, 6359 390 nm Pass filter, plus UV filter PMT small aperture in the hole, Reproducibility check 6360 390 nm Pass filter, plus UV filter PMT small aperture in the hole, increase current from 150 to 200 mA 6361 390 nm Pass filter, plus UV filter PMT small aperture in the hole, current 150 mA, mister ON 6362 390 nm Pass filter, plus UV filter PMT small aperture in the hole, current 150 mA, mister OFF

## PMT linearity test

PMT[5] = PMT in the cell looking at the mirror

Suspect PMT was linearly responding to beam current at 50 ns widths and 75 mA peak, 32 MeV

 Run# Current (nV*sec) PMT[5](PADC chann #) PMT[5] Fstop 6377 3.8 6378 8.5 1600 Cut wide pulse current in half and shortened pulse to 50 ns, pulse very hard to measure at 50 ns 6379 2.2 837 current changed during run 6380 3.5 1200 6381 4.3 704 Position 1=open, at position 3, diameter = 26 mm 6382 4.5 190 Position 1=open, at position 6 diameter=3.5 mm 6383 4.7 1214 Position 1=open, at position 1 diameter = 31 mm 6384 1237 Position 1=open, at position 1, double width to 100 ns 6385 1237 Position 1=open, at position 1, double width to 200 ns (ADC overflow!)

## Current calibration

Changed beam current using width of the beam

 Run# Charge PADC Chann# Configuration 6337 uC 3625 26 current calibration, 1.47 uV*sec in 50 Ohms, 2.2 usec, x10 attenuator 6338 0.1588 2098 6 current calibration, 794 nV*sec in 50 Ohms, 1.1 usec, x10 attenuator 6339 0.058 1093 4.7 current calibration, 429 nV*sec in 50 Ohms, 550 nsec, x10 attenuator 6340 0.0378 504 4 current calibration, 189 nV*sec in 50 Ohms, 225 nsec, x10 attenuator 6341 0.0208 342 3 current calibration, 104 nV*sec in 50 Ohms, 125 nsec, x10 attenuator

slope=8.53252e-05 +/- 6.47968e-06 y-intercept=-0.0189951 +/- 0.0141188

Micro-Coulombs (uC)

 Run# Charge PADC Chann# Configuration 6366 uC 1351 14 current calibration, 330 \pm 5 uV*sec in 1 Meg Ohms, 2.2 usec, 6367 792 9 current calibration, 190 \pm 5 nV*sec in 1 M Ohms, 2.2usec 6368 496 5 current calibration, 106 \pm 3 nV*sec in 1 M Ohms, 2.2usec 6371 1066 10 current calibration, 265 \pm 4 nV*sec in 1 M Ohms, 2.2usec

## 5/26/17

32 MeV Beam 150 mA current

UV wide band filter on cell PMT, Aperature wide open

 Run# Cell PMT [5] FC [7] 6389 3142 1509 6390 2231 908 6391 1191 447 6392 708 287 (have full current near end) 6393 2642 1147 6394 1605 580 6395 1889 696 (changed current near end of run) 6396 698 279 6397 390 183 (changed current near end of run)

filters on cell PMT, NO Aperature, Mixed field (taken during irradiation)

 Run# Cell PMT [5] FC [7] [5]/[7] comment 6401 3503 1743 2.0 320 nm filer 6402 110 1614 0.07 330 + 320 nm filters 6403 2972 1519 1.956 390 nm Filter