PePPO NaI PositronDetector 4 JLab

Detector setup for a NaI positron detector for PePPO

NaI detector

The PMT is powered by a HV supply which should have a DC ripple less than 200 mV peak-to-peak at 3kV/3mA. A DC ripple will change the gain of the PMT and cause the energy resolution to deteriorate.

The Linearity of the detector system is another way to reduce the energy resolution. The measured PMT output should be linear with the input signal when the gain is constant. This linearity can be measured using 2 radiation sources.

Input HV: +1085 V

Input Current: 2.362 mA

Running CODA: Running CODA

Measurements Using V792 QDC

Run 1979

Start Time : March 23:12:30:26

End Time: March 23: 13:10:47

Elapsed time: 2421 seconds

Run 1980

Remove Na-22 source from top of NaI crystal.

Start Time : March 23:13:11:23

End Time: March 23: 15:56:40

Elapsed Time:6317 seconds

Let's lower the gain of the Phillips 777 amplifier so the 511 peak is around channel 500. This way the 1 MeV photons may come on scale.

Run 1982

Overnight Cosmic Run

Start Time : March 23: 16:01:47

End Time: March 24: 09:41:31

Elapsed Time:63558 seconds

Run 1983

Start a run using Co-60

Start Time : March 24: 09:46:25

End Time: March 24: 10:14:24

Elapsed Time: 1679 seconds

The 1.x MeV gammas appear near channel 1200.

I'll do a long Na-22 run and think about upping the amplifier gain again to put the Co-60 peak around channel 3000.

The Co-60 source trigger rate is about 750 Hz and the Na-22 trigger rate was about 450 Hz.

Run 1984

Start a run using Na-22

Start Time : March 24: 10:16:49

End Time: March 24: 11:02:38

Elapsed Time: seconds

Run 1987

Increase gain of Phillips 777 amplifier which 
I am using on the PMT output,  We may want to adjust 
the dynode gain/discriminator to fill in the lower 
energy part of the spectrum.

Start a run using Na-22

Start Time : March 24: 11:34:35

End Time: March 24: 1 Elapsed Time: seconds

I was expecting to see a photon of energy 1.17 and one with 1.33 MeV in the above specturm. Assuming that my ability to resolve the two peaks is due to noise I will assume both are in the peak at channel [math]3158 \pm 1[/math]. Since the intensity of the above two lines are almost the same I will do a simple average.

[math]\bar{E_{\gamma}} =\frac{1.17 + 1.33}{2} =1.25 [/math] MeV

The above measurement indicates that a 1.25 MeV photon appears at channel [math]3158\pm 1[/math] in the current apparatus.

Run 1988

Start a run using Na-22

Start Time : March 24: 11:34:35

End Time: March 24: 16:21:31

Elapsed Time: 17216 seconds

The above measurement indicates that a 0.511 MeV photon appears at channel [math]1839 \pm 0.1[/math] in the current apparatus.

Run 1989

Start a run using Co-60

Start Time : March 24: 16:23:30

End Time: March 24: 16:57:00

Elapsed Time: 2010 seconds

The above measurement indicates that a 1.25 MeV photon appears at channel [math]3256 \pm 0.8[/math] previously it was at [math]3158\pm 1[/math] in the current apparatus.

The 98 channel difference is beyond the fit statistic.

Taking the average of the two give 3207 Channels.

Energy Calibration using run 1987-1989

Summary of Apparatus Specs

JLab PMT at +1185 Volts, 2.6 mA.

Dynode is inverted by Ortec 474 timing filter amplifier set to unity gain. The Ortec output is put through a Lecroy Model 4608C discriminator set to -44.8 mV.

Anode is amplified by a Phillips 777 fast Amp. Gained measured to be XXXXX

Doing a Linear fit using the two points

1.25 MeV ,3207 Channels

0.511 MeV , 1839 Channles

gives

Channels = 893.06 + 1851.2 MeV

The energy distributions measured do not appear to have the expected structure. There is a 1.3 MeV energy gamma from the Na-22 source which was expected but only hinted at. Its intensity is 10% but it should start to show up on long runs.

The next goal will be to lower the dynode discriminator threshold so we trigger on lower energy events. Does the Compton edge become more obvious for Na-22?

I think my trigger threshold on the dynode is cutting things off at 200 keV.

Run 1990

Overnight Cosmic run

Start Time : March 24: 17:22:38

End Time: March 25: 09:14:44

Elapsed Time: seconds

Gain

Amplifier gain measurement for runs 1987-1989 using a 1.5 Volt battery

Changed integrate pulse width to 43 nsec

Run 1992: Battery going directly into ADC appear near channel 523

Run 1993: had battery through amp but forgot to plug in ADC, I'll take another run so interpretation is simple.

Run 1994: 1.5 Volt battery going into amplifier then ADC appears near channel 2190

so gain is 2188/523 = 4.18

Maybe I can increase the HV on the PMT to run without an amplifier and reduce my noise.

run 1995 Co-60 no amp

No Amplifier

Start a run using Co-60

Start Time : March 25: 09:46:23

End Time: March 25: 10:23:45

Elapsed Time: seconds

run 1996 Na-22 no amp

No Amplifier

Start a run using Na-22

Start Time : March 25: 10:26:43

End Time: March 25: 14:42:19

Elapsed Time: seconds

run 1997 Na-22 no amp

Increase HV on PMT from 1185 to 1250 Volts

Start a run using Na-22

Start Time : March 25: 14:43:55

End Time: March 25: 14:58:04

Elapsed Time: seconds

run 1998 Co-60 no amp

Increase HV on PMT from 1185 to 1250 Volts

Start a run using Co-60

Start Time : March 25: 15:09:30

End Time: March 25:

Elapsed Time: seconds

Rate was 5kHz and the ROC crashed

Move source farther away to lower rate

run 2000 Co-60 no amp

Increase HV on PMT from 1185 to 1250 Volts, 2.74 mA

Source moved 7.5 cm away from NaI to lower counting rate.

Start a run using Co-60

Start Time : March 25: 15:20:29

End Time: March 25: 15:26:54

Elapsed Time: seconds

run 2001 Na-22 no amp

Increase HV on PMT from 1185 to 1250 Volts, 2.74 mA

Source moved 7.5 cm away from NaI to lower counting rate.

Start a run using Na-22

Start Time : March 25: 15:28:13

End Time: March 25: 15:33:00

Elapsed Time: seconds

run 2002 Na-22 no amp

Increase HV on PMT from 1250 to 1350 Volts, 2.96 mA

Source moved 7.5 cm away from NaI to lower counting rate.

Start a run using Na-22

Start Time : March 25: 15:34:50

End Time: March 25: 15:38:54

Elapsed Time: seconds

run 2003 Co-60 no amp

Increase HV on PMT from 1250 to 1350 Volts, 2.96 mA

Source moved 7.5 cm away from NaI to lower counting rate.

Start a run using Co-60

Start Time : March 25:

End Time: March 25:

Elapsed Time: seconds

run 2004 Na-22 no amp

Increase HV on PMT from 1350 to 1430 Volts, 3.1 mA

Source moved 7.5 cm away from NaI to lower counting rate.

Start a run using Na-22

Start Time : March 25: 15:46:23

End Time: March 25: 15:52:06

Elapsed Time: seconds

Looks like I was running at too low of a HV, that is why the spectra did not make sense above, I now see 2 peaks for Co-60 that are close together. What were those high energy peaks? Lets check the counting rate.

run 2005 Co-60 no amp

Increase HV on PMT from 1350 to 1430 Volts, 3.1 mA

Source moved 10.1 cm away from NaI to lower counting rate.

Start a run using Co-60

Start Time : March 25: 15:53:05

End Time: March 25: 16:03:24

Elapsed Time: 559 seconds

run 2006 Na-22 no amp

Increase HV on PMT from 1350 to 1430 Volts, 3.1 mA

Source moved 10.1 cm away from NaI to lower counting rate.

Start a run using Na-22

Start Time : March 25: 16:04:16

End Time: March 25: 16:24:04

Elapsed Time: 1188 seconds

Channel = -540.15 + 1279.2 HeV

It looks like we should run the JLab tube at 1430 volts if we don't use an amplifier (tube is rated to 1500 Volts)

You see 4 peaks.

The Na-22 peaks at 511 keV and 1275 keV. A gaussian fit yields a sigma 36.5 for the 511 keV peak and 57 for the 1275 keV peak. The Co-60 source has two peaks. One at 1173 keV which has a sigma of 64.1 and one at 1332.5 which has a sigma of 61.23

[math]\frac{\sigma}{mean}[/math] = 7%, 4.4 %, 5.4 %, ,4.5%

The energy resolution at 511 keV is probably skewed because the discriminator threshold is low.

Conclusions

It looks like we should run the JLab tube at 1430 volts if we don't use an amplifier (tube is rated to 1500 Volts) .

Readout

F250

JLab's F250 flash ADC will be used to measure the NaI output

ADdress is

Address
Pin	Switch	bit
A12	on/closed	0
A13	on	0
A14	on	0
A15	on	0
A16	on	0
A17	off/open	1
A18	off	1
A19	off	1
A20	on	0
A21	off	1
A22	off	1
A23	off	1

Module address = 0xee0000 = 111011100000000000000000 d

If I want 0xaa0000 = 101010100000000000000000 d

Setting FADC to bb address

If I want set 0xbb in hexadecimal, the binary will be 10111011

On the board:

on  = closed = 0
off = open   = 1

Address
Pin	Switch	bit
A12	on/closed	0
A13	on	0
A14	on	0
A15	on	0
A16	off	1
A17	off/open	1
A18	on	0
A19	off	1
A20	off	1
A21	off	1
A22	on	0
A23	off	1

I set it like above, but it didn't work at first. Then Dr. Forest turned roc1 off, and pushed the FADC in to the slot. He said it might be that the FADC did not sit well on the slot, so we need to push it.

I turned roc1 on, but it won't connect. It gives error says

telnet: connect to address 10.1.1.2: No route to host

I restarted roc1 several times, finally it worked. Was the error due to roc1 was not started?

Following is the message I got then

Starting FADC

Connect to roc1

telnet roc1
Trying 10.1.1.2...
Connected to roc1.
Escape character is '^]'.

Load FADC Libraray

-> ld < fadcLib.o
Undefined symbol: sysVmeDmaSend (binding 1 type 0)
Undefined symbol: sysVmeDmaDone (binding 1 type 0)
ld error: Module contains undefined symbol(s) and may be unusable.
value = 0 = 0x0

Initialize FADC

Recall that Address of ADC was set to be 0xbb0000

-> faInit (0xbb0000)
Initialized FADC 0  Slot # 4 at address 0x90bb0000 
faInit: Enabling FADC Internal Clock, and Software Triggers (Soft Sync Reset)
value = 0 = 0x0

I think the address I set worked. But why it initialized at 0x90bb0000, instead of 0xbb0000? Is it because software set it 32 bit address?

Check Status

-> faStatus(0)

Software Triggering

https://wiki.iac.isu.edu/index.php/JLab_F250ADC#Software_Trigger

Hardware Triggering

https://wiki.iac.isu.edu/index.php/JLab_F250ADC#Hardware_Trigger

Na-22 source

North American Scientific Model CAL2600

Activity = 9.803 \muCi on 5/1/05

Serial Number 64236

Na-22 beta decays giving off a 215 keV KE beta and a 1.275 MeV photon.

http://atom.kaeri.re.kr/cgi-bin/decay?Na-22%20EC

Co-60 source

North American Scientific Model CAL2600

Activity = 9.641 \muCi on 5/1/05

Serial Number 64120

Co-60: decays to Ni giving 2 dominant gamma lines at 1.173237( 4) and 1.332501( 5) MeV. The Average Beta energy is 95 keV.

Co-60DecayChain.png

http://atom.kaeri.re.kr/cgi-bin/decay?Co-60%20B-

Detectors Documentations

SCIONIX HOLLAND

This is a Crystal with base.

Ruggedized Detectors:

http://www.helgesonsa.es/m02/firmas/SCIONIX/pages/pdf/Ruggedized%20Detector.pdf

File:SCIONIX HOLLAND.pdf

LaCl 3:Ce Scintillation Crystals:

http://www.helgesonsa.es/m02/firmas/SCIONIX/pages/pdf/LaCl3%20literature.pdf

File:SCIONIX HOLLAND Crystal info.pdf

Rexon Components Inc

Voltage range: 0 - 2000 V DC (positive)

B76D01 PMT Pinouts

This is a Crystal, and there is a base from same company.

Rexon PB200 Base

Base: http://www.rexon.com/POWER%20SUPPLY2.htm

File:Rexon Base RB200datasheet.pdf

File:Rexon Base RB200.pdf

File:Rexon Base RB-200 PMT Base Manual.pdf

PMT:

File:Rexon PMT.pdf

size: 3" diameter

Saint-Gobain crystals & detectors ltd

This is just a base.

PA-14

http://www.detectors.saint-gobain.com/uploadedFiles/SGdetectors/Documents/Electronics/Voltage-Divider-Legacy-design.pdf

File:Saint-Gobian PA-14.pdf

Standard Features of Model P-14 Plug-on Voltage Divider

• Aluminum housing

• Positive (+) high voltage operation

• BNC bulkhead connector for signal output

• SHV bulkhead connector for high-voltage supply input

• 800 to 1200 VDC (may be higher or lower depending upon the specific PMT) at <1 mA typical operating power requirements

• Gain potentiometer

• Focus potentiometer

Additional features for model PA-14 plug-on voltage divider/preamplifier

• Standard hard-wired preamplifier power cable terminating in a 9-pin connector (pin 6 for -24VDC, pin 1 common ground)

• Optional BNC (in place of standard 9-pin) connector for preamplifier power input; -24V at 21mA operating power requirements.

Preamplifier specifications

• Noise: Less than 50 microvolts RMS referred to input

• Input: Directly coupled via 1μF capacitor from photomultiplier tube anode to charge integrating preamplifier input circuit, positive pulse output.

• Conversion Gain: 100mV/picocoulomb

• Rise Time: 100 nanoseconds

• Decay Time: 10 microseconds (internally adjustable at the factory)

• Gain Stability: 0.25%/C from 0° to 50°C

• Linearity: 0.25% (preamplifier only)

• Power Requirements: -24V +10% @21mA

Canberra Industries Inc.

This is just a base.

It is not clear from the PMT base we have what model is it, the data got scratched off. The comparison to information given on their website, it seems that the model is: 2007P.

http://www.canberra.com/pdf/Products/Model-2007-2007P-SS-CSP0071.pdf

File:Canberra 2007P.pdf

Ortec Base Images

Detectors Test

We got some other PMT from IAC. We applied Rexon base on these PMT, and tested them.

We put Co-60 source with S/N 67415. I think this source has activity less than 1 micro Currie (may be around 900 nano Currie).

I Applied 700 V to Rexon base. 1440 IAC

IAC IA-1377 SN6002-8292-I_blue_at700V_Co60Source67415_and_JLab_green_at1440V_Detectors

Saint_Gobain

 Model  Crystal Size   PMT Size
 3MW3/3   3” x 3”          3”

Positrons#Experiments

May Tests

You should turn on the JLab PMT to the HV we used last time (1420?) and take date with the Co-60 and Na-22 sources.
A replay program is in the directory below.
/home/daq/CODA/CODAreader/UsingROOTnEVIO/FADC/Mode1_Raw
Mode1_Raw >hsimple -fr2092.dat

JLab NaI Detector

Cosmic ray scope images:

Cosmic ray images from Flash-ADC output

Building Our Own Base

Our Modified PMT Base Design

Parts List

Element	Quantity	Price ($)	Link
14Pin Tube Socket for CRT/PMT		$11.90	[1]
14 PIN TUBE SOCKET FOR PMT		$11.95	[2]

Test Result

HV: 700 V

400 px

JLab NaI Detectors 511keV-peak VS HV Fits

Detector 1

Run #	HV	Mean    Mean_Er Sig	Sig_Er

1091	760	2112.78	1.57153	394.982	1.59193
1090	800	5842.02	2.23718	473.406	1.99162
1089	840	11180.3	3.2137	645.147	2.95208
1084	880	18905.3	5.32698	893.547	4.67192
1085	920	28622.6	6.68983	1107.65	5.72712
1062	960	39273.3	9.70502	1493.64	8.39144
1064	1000	48548.2	19.8958	2571.11	22.5537
1066	1040	53929	47.0277	7263.09	57.3275

Detector 2

Run #	HV	Mean    Mean_Er Sig	Sig_Er

1103	860	5107.38	1.12936	264.643	0.78483
1100	920	6537.05	1.42168	343.966	1.3294
1099	960	8495.89	1.72529	385.842	1.61172
1098	1000	10968.3	2.13744	440.855	1.90317
1096	1040	14183.2	2.68414	523.829	2.42337
1095	1080	18221.8	3.37783	644.152	3.02526
1093	1120	23066.9	4.07353	793.69	3.57796
1092	1160	29333.1	5.49684	1006.06	4.82086
1067	1200	36885.2	7.45106	1197.1	6.37567
1068	1240	45086.7	8.28584	1340.93	7.17047
1070	1280	52989	10.2242	1.76201	8.96842
1073	1300	56191.4	15.0161	2336.5	14.4031
1074	1320	59118.8	18.4745	2917.3	17.1648

Positrons