PAA CoincidenceCounting

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Canberra Model 9615 < 0.04% (integral) over 2usec

Canberra Model 9633 < 0.025% (integral) < 0.9% (differential), +10V range into 1kOhm, 8192 channels (13 bit), 100 usec signal width => 100 pC/chan

CAEN V792 < 0.1% (integral), 200 fC/chan

CAEN digitizer VX1492, 14 bit, 10 Volt range

CAEN V1720:

Coinc Scope pictures

Pics using Spec Amps only and Peak Sensing ADC

Below is a picture of the spec amp ouput which is send to the Peak sensing ADC. The pulse is over 5 usec long indicating that pile up will happen when the detected incident particle rate is 1/5usec = 200 kHz. Pile up can also happen at lower rates so keep the singles counting rate below 10 kHz by moving the source farther away or waiting a few half lives.

Pics using noising inverting amps

Two HpGe detectors were used to detect coincidence gammas from Co-60 on 6/14/2013.

Co-60 will beta decay to Ni-60 giving off two gammas in coincidence having energies of 1173 and 1332.5 keV. The scope pictures below record the pulses from the HpGe detector that are in coincidence. I would have expected the charge output by the HpGe detector to be similar for the two gammas, but there are some that have less than half the charge. The could be the beta particles from the decay reaching one of the detectors in coincidence with one of the gammas.

First Singles Spectrum

Detector 180-3

50 keV Energy resolution from an HpGe detector??

I think the inverting amp is too noisy:

The Signal is about 400 mV and the above noise is 37 mV peak-to-peak and it is syncronized with my integrate gate

The voltage variations of the timing amp output in the region of the integrate gate are about +/- 10 mV

Singles Spectrum (2nd attempt)

Using detector 180-3

HV = -2800 Volts

Run 5446, Co-60 and Na-22 sources are in at the same time, attenuation is 18 db, 1 Mev photon peaks are around 3000 -> 3500 channels in ADC spectrum

Two Co-60 Lines

Mean 2.94555e+03 +/- 7.23197e-01 Sigma 7.61455e+01 +/- 8.86697e-01

Mean 3.63275e+03 +/- 8.39279e-01 Sigma 7.45542e+01 +/- 1.04796e+00

1.2 meV na-22 line

Mean 3.37891e+03 +/- 1.07859e+00 Sigma 6.26450e+01 +/- 1.73063e+00

Run 5447, Na-22 source, attenuation is 18 db, 1 Mev photon peaks are around 3000 -> 3500 channels in ADC spectrum Mean 3.38431e+03 +/- 1.29456e-01 Sigma 1.12914e-01 +/- 2.59220e-02

Run 5448, Na-22 source, attenuation is 14 db, 0.511 Mev photon peaks are around 1000 channels in ADC spectrum

Run 5449, Na-22 source, attenuation is 12 db, 0.511 Mev photon peaks are around 2500 channels in ADC spectrum

Mean 2.60181e+03 +/- 8.10190e-01 Sigma 5.97964e+01 +/- 6.63405e-01

Run 5450, Co-60 source, attenuation is 12 db, 1 Mev photon peaks are around 3000-> overflow channels in ADC spectrum

Run 5451, Co-60 source, attenuation is 13 db, 1 Mev photon peaks are around 2500 -> 3500 channels in ADC spectrum

Low energy 1.2 MeV peak

Mean 2.64173e+03 +/- 1.35816e+00 Sigma 1.03518e+02 +/- 1.49690e+00

High energy 1.3 MeV peak Mean 3.33157e+03 +/- 1.36696e+00 Sigma 1.01444e+02 +/- 1.15611e+00

Run 5452, Na-22 source, attenuation is 13 db, 1 Mev photon peaks are around 2500 -> 3500 channels in ADC spectrum

Mean 3.02266e+03 +/- 1.53757e+00 Sigma 5.26142e+01 +/- 1.61646e+00

Run 5453, NO source, attenuation is 13 db, 1 Mev photon peaks are around 2500 -> 3500 channels in ADC spectrum, run started at 17:18:27 on July 23 ended on July 24 at 15:34:05

Run 5484, Na-22 and Co-60 source, attenuation is 14 db, 1 Mev photon peaks are around 2600 -> 3600 channels in ADC spectrum, Na-22 and Co-60 peaks are separable unlike in detector B

Run 5484, Na-22 source, attenuation is 8 db, 0.5 Mev photon peaks are around 2000 channels in ADC spectrum

Using detector B

HV = +4520 Volts

Run 5466, Na-22 source, attenuation is 17 db, 1 Mev photon peaks are around 2300 channels in ADC spectrum

Run 5470, Co-60 source, attenuation is 17 db, 1 Mev photon peaks are around 2300 channels in ADC spectrum

Run 5471 & 5472, Na-22 and Co-60 sources both in, attenuation is 17 db, 1 Mev photon peaks are around 2300 channels in ADC spectrum

Run 5474, Na-22 source, attenuation is 12 db, 0.5 Mev photon peaks are around 1000 channels in ADC spectrum

The above runs used the same input lines that were used for detector 180-3, Now I put Detector B through its own signal lines and the attenuation needed changes

Run 5477, Na-22 source, attenuation is 9 db, 1 Mev photon peaks are around 3000 channels in ADC spectrum

Run 5478, Co-60 source, attenuation is 9 db, 1 Mev photon peaks are around 3000 channels in ADC spectrum

Run 5480, Na-22 source, attenuation is 3 db, 0.5 Mev photon peaks are around 1500 channels in ADC spectrum

Singles SPectrum 3rd attempt (Peak sensing ADC)

Using the CAEN 785 peak sensing ADC I was able to increase the dynamic range and take positive going pulses.

Below are the first two spectra with sources and almost no discrimination

Detector 180-3

 Run Number Description 5632 Na-22 1 uCi source 5633 Co-60 1 uCi Source 5634 Co-60 1 uCi Source, set threshold on Ortec Const Fraction Timing Disc model 2035A to 20 mV 5635 Co-60 1 uCi Source, set threshold on Ortec Const Fraction Timing Disc model 2035A to 10 mV 5636 Na-22 1 uCi Source, set threshold on Ortec Const Fraction Timing Disc model 2035A to 10 mV

Calibration Fit

Spectrum of 60Co, peaks at 1.17 and 1.33 MeV

Two peaks at 1173.2374 keV and 1332.5015 keV

Na22 Spectrum: 1274.532 keV

Na22 emits: 0.510998928(11) MeV

 Run Number Source Energy (keV) Fit 5636 Na-22 510.998928 1215 5635 Co-60 1173.2374 2709 5636 Na-22 1274.532 2937 5635 Co-60 1332.5015 3068

Fit:

slope = 2.26 +/- 0.003
intercept= 62.45 +/- 2.59
Looks like I have 3 keV resolution or less on detector 180-3
 Run Number Source Energy (keV) Fit 5636 Na-22 510.998928 1215 5635 Co-60 1173.2374 2709 5636 Na-22 1274.532 2937 5635 Co-60 1332.5015 3068

Coincidence Tests

Detector B is in ADC Ch9, TDC18

Detector 180-2 is in ADC CH5, TDC16

5679, Copper Irradiated for 1 hour at 40 Mev, 1 kW

Calibration using Run 5689 and 5691
 Detector Ntuple Channel slope (kev/chan) y-int (chan) B ADC9 1.6624 +/- 0.00344072 39.8968 +/- 3.58784 180-2 ADC5 2.11785 +/- 0.00169804 62.5234 +/- 1.77065
The Canbera Constant Fracting TIming SCA Model 2035A has an unadjustable output width of 600 ns
Apparatus change
move detectors farther away from sample to reduce DAQ rate for 1 uCi source
detectors are about 7" away from the source
 Run Number Description 5700 1uCi Co-60 source serial # 129739, CFD width is 2 nsec, logic unit in OR mode, 2800 Volts on Detector 180-3, 4500 volts on Detector B, rate is about 650 Hz, runtime was 6 min 18 seconds 5701 same as run 5700 but NO source, rate is about 300 Hz, runtime was min seconds 5702 same as run 5700 but NO source and Coincidence is required, rate is about 0 Hz, runtime was 21 hours 54 min 29 seconds, 149 events, TDC window width was 2ns

Proposed Apparatus

We propose to acquire two 14 bit digitizers (flash ADCs), a muli-hit time-to-digital converter, and the associated NIM electronics needed to supplement our current VME based data acquisition system. The availability of precision analog digitizers and pipeline time to digital converters allows the construction of a data acquisition system to record the pulse shape and time information that will allow the reconstruction of individual coincidence events. The most common method used to record photon spectroscopy information does so by accumulating events thereby loosing any temporal information. We propose a coincidence counting system which records the wave form of each coincidence event along with a time stamp. The system will allow a post data taking analysis that can increase the coincidence time constraint beyond the original requirement and ascertain the degree of confidence in identifying the decay under consideration.

Isotopes for CPAA

Au

\$50 flame tests can measure concentrations down to 100 PPM

Photon based exitation

A photon excites Au-196 natural gold to the

neutron knockout

Knock a neutron out of natural gold such that an excited state of Au-196 remains that will undergo electron capture to Pt-196 with a half life of 6 days or 2% of the time it can be left in a meta stable state with two possible half lifes of 8 seconds or 9 hours.

Neutron Separation Energy= Energy needed to liberate a neutron from the Nucleus

=

Au-196 Meta state

The 8 sec metastable state of Au-196 decays through the emission of only one 84.66 keV photon.

The 9.6 hour metastable state has high intensity gamma lines at 147.81 keV and 188.27 keV. The 147.81 and the 188.27 are in coincidence.

Pt-196 decay EC decay

with a half life of 6 days.

The Pt-196 has a 355.73 dominant (100% relative intensity) gamma line that goes to the 256.2 state giving off a 97.3 keV photon

Filling Ln2

 Date Detector 8/7/13 B I filled Detector B for 20 minutes with the valve open 1/2 turn and the detector completely warm. 8/8/13 B Detector B was still cold after 26 hours, I filled it at 1/2 turn flow rate for 15 minutes

Configuring setup for Gold

We need to measure photon energies ranging from 80 to 200 keV. There is a lot of background at the low energies so we should try to install shielding and increase the Ortec amplification to the Co-60 lines so they are at the upper limit of the ADC.

Increased amplification and decrease CFD lower threshold so the PADC range covered photon energies between 100 and 1300 keV.

Calibration

Calibration using Co-60 and Na-22 in Run 5707
 Detector Ntuple Channel slope (kev/chan) y-int (chan) B ADC9 2.62335 +/- 0.00292256 33.551 +/- 3.04752 180-2 ADC5 2.82207 +/- 0 62.1537 +/- 0

Calibration runs

 Source Energies (keV, in order of decreasing intensity) Mn-54 834.848 Cd-109 88.0336 Eu-152 121.7817,1408.006, 1112.069, 1085.869, 244.6975 Ba-133 356.0134, 80.9971, 302.8510, 276.3997 Co-57 122.06065, 136.47356, Cs-137 661.657 Co-60 1332.501, 1173.237 Na-22 1274.53

 Run # Source(s) 5708 Na-22, Co-60, CS-137, Co-57, Ba-133, Eu-152, Cd-109, Mn-54 5709 Cd-109, Mn-54, The 834 line from Mn-54 is clear but no the 88 keV line from Cd-109 5710 Ba-133, has a nice strong line at 81 keV 5711 Co-57, The 122 line is clear in Det B but not detector 180-2, I dont see the 136 line in either detector 5712 Eu-152, very clear line at 122 keV 5713 Eu-152,Ba-133, & Co-57
Calibration using Co-60, Na-22 , Ba-133, Co-60
 Detector Ntuple Channel slope (kev/chan) y-int (chan) B ADC9 2.61747 +/- 0.00179257 39.8 +/- 1.19887 180-2 ADC5 2.82182 +/- 0 62.3096

I would use Ba-133, EU-152, & Co-57 to calibrate for the 147 & 188 keV lines in Gold.

Det B has better resolution than 180-2 at lower energies

Coincidence

Eu-152 has concidence lines for

117 & 109

120 & 109

Ba-133 has coincidence lines for 361 & 83

Coincidence lines for Ba-133

1. 276 && 306 keV lines http://www.nndc.bnl.gov/nsr/nsrlink.jsp?1995JU02
3. Ba-132 383 && 515 http://www.nndc.bnl.gov/nsr/nsrlink.jsp?1975GI11

Coincidence lines for Eu-152

1. Eu-151 244 & 344 keV http://www.nndc.bnl.gov/nsr/nsrlink.jsp?1977DR04

 Run Description 5715 Coincidences for Ba-133 & Eu-152 10 uCi sources The CFD widths were 10 nsec making the coincidence window 20 nsec. running time 13 hrs , 10 min, 30 sec. Rate was 4 Hz 5716 Coincidences for Ba-133 10 uCi source. The CFD widths were 10 nsec making the coincidence window 20 nsec. running time 7 hrs , 33 min, 14sec. Rate was 1 Hz 5718 Logic Unit in OR mode for Ba-133 10 uCi source. The CFD widths were 10 nsec making the coincidence window 20 nsec. running time 2 min, 5 sec. Rate was 4 kHz r5718-5716_Ba133Analysis 5719 Logic Unit in OR mode for Eu-152 10 uCi source. The CFD widths were 10 nsec making the coincidence window 20 nsec. running time 3min, 54 sec. Rate was 5 kHz 5720 Logic Unit in AND mode for Eu-152 10 uCi source. The CFD widths were 10 nsec making the coincidence window 20 nsec. running time 22 hrs, 31 min, 19 sec. Rate was 2.3 Hz

Au+sand in Crucibles

 Run Description 5721 Logic Unit in OR mode for Au+Sand sample #5 (Target ID 130028). The CFD widths were 10 nsec making the coincidence window 20 nsec. running time 37 min, 59 sec. Rate was 544 Hz 5722 Logic Unit in AND mode for Au+Sand sample #5 (Target ID 130028). The CFD widths were 10 nsec making the coincidence window 20 nsec. running time 16 hours 44 min, 43 sec. Rate was 0.01 Hz, Det B (ADC9) warmed up and tripped during the night, the detetor's dewar will not last more than 30 hours, fill it every 24 hours. 5725 Logic Unit in AND mode for Sand+crucible blank sample (Target ID 130033). The CFD widths were 10 nsec making the coincidence window 20 nsec. running time 16 hours 13 min, 30 sec. Rate was 0.1 Hz 5726 Logic Unit in OR mode for Sand+crucible blank sample (Target ID 130033). The CFD widths were 10 nsec making the coincidence window 20 nsec. running time 30 min, 47 sec. Rate was 563 Hz 5727 Logic Unit in OR mode for Au+Sand sample #5 (Target ID 130028). The CFD widths were 10 nsec making the coincidence window 20 nsec. running time min, sec. Rate was Hz 5728 Logic Unit in AND mode for Au+Sand sample #5 (Target ID 130028). The CFD widths were 10 nsec making the coincidence window 20 nsec. running time 19 hours, 52 min, 41 sec. Rate was 0.09 Hz 5729 Logic Unit in AND mode No SAMPLE. The CFD widths were 10 nsec making the coincidence window 20 nsec. running time 1 hours, 41 min, 5 sec. Rate was 0.07 Hz 5730 Logic Unit in AND mode No SAMPLE. The CFD widths were 10 nsec making the coincidence window 20 nsec. running time hours, min, sec. Rate was 0.07 Hz

I see a coincidence line at 1274 +/- 4 keV and 511 +/- 1 keV 70 days after irradiating the Gold+Sand and the blank sample.

The excited state of Ne-22 lasts only 3.6 ps before emitting the 1275 gamma so you can see the 1275 in coincidence with the 511. Since the Ne-22 is in an excited state the photon direction is not correlated with the positron emission. Na-22 has a 2.6 year half life.

I notice the photon energy observed in the coincidence measurement is 4 keV lower than the singles.
In the Ba-133 runs #5716 and #5718 I see the 355 line shift down by 1 keV in the coincidence measurements.
The 511 peak shifts down by 1keV in the coincidence measurements of run 5722 compares to the singles run # 5721
It seems my energy measurement accuracy is +/- 2 keV at best.

Will the Na-22 line be useful for normalizing?

I had to choose between a low irradiation dose and being able to measure the spectrum 3 hours after irradiation, or a very high dose and measuring the spectrum after 55 hours (~6, 9 hour half lives).

A chose to first measure after the low irradiation dose. We waited 45 minutes after the 1 hour irradiation before entering the hall to retrieve the samples.

120 Hz, 42 MeV, 50 uA, 8 microsecond pulse width.

Gold+Sand+Crucible samples were irradiated for 1 hour.

Samples were located outside the hot cell at the rear near the mirror. The were about 6" away from beam center.

Removed from cell at 3:14

Sample Target ID numbers were changed

Gold + Sand + crucible = Sample # 5 = Target ID #130028 =130097

Sand + Crucible = Blank = Target ID #130033 =130096

Samples stored in source room bin A-48

 Run Description 5731 Logic Unit in OR mode for Au+Sand+crucible blank sample (Target ID 130097). The CFD widths were 10 nsec making the coincidence window 20 nsec. running time 37 min, 44 sec. Rate was 660 Hz ( 100 Hz more than before Irrdiation), I see lines at 853 & 1370 keV that were not in background run 5721, 511 keV photon events have a higher rate if you compare the relative 511 rates between run 5731 and run 5721. 5732 Logic Unit in OR mode for Sand+crucible blank sample (Target ID 130096). The CFD widths were 10 nsec making the coincidence window 20 nsec. running time min, sec. Rate was 619 Hz ( 100 Hz more than before Irrdiation),The 853 and 1370 lines also appear in the blank sample (Aluminum in the crucible?) 5734 Logic Unit in AND mode for Au+Sand+crucible blank sample (Target ID 130097). The Discriminator widths were changed from 10 ns to 400 nsec making the coincidence window 800 nsec(The CFD width to the TDC is 20 nsec and not adjustable). running time 25 hours 17 min, 57 sec. Rate was 1.4 Hz

Run 5734 shows two lines at 586 & 612 keV

ntuple->Draw("(ADC9-39.8)/2.61747 >>(4096,0,4096)","abs(TDC16-TDC18)<400")


Na-22 Coincidence?

 Run Description 5697 Coincidences for Na-22 source serial #129742 were observed, a 511 and a 1271(4?) were observed in coincidence. This confirms the Na-22 signal seen in the Sand+Gold samples. The 1271 peak is shiftwed from the 1274 peak shown in run 5698. The CFD widths were 2 nsec making the coincidence window 4 nsec. running time 3hrs , 6 min, 30 sec. Rate was 0.3 Hz 5698 singles for Na-22 source serial # were measured. rate was 2 kHz