PAA CoincidenceCounting

ADC non-linearity

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

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

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

CAEN digitizer VX1492, 14 bit, 10 Volt range

Coinc Scope pictures

First pict with ADC gate

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 B

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

Co60: http://ie.lbl.gov/toi/nuclide.asp?iZA=270060

Two peaks at 1173.2374 keV and 1332.5015 keV

Na22 Spectrum: 1274.532 keV

Na22: http://ie.lbl.gov/toi/nuclide.asp?iZA=110022

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

Run Number	Description
5644	Na-22 1 uCi Source, set threshold on Ortec Const Fraction Timing Disc model 2035A to 10 mV
5645	Co-60 1 uCi Source, set threshold on Ortec Const Fraction Timing Disc model 2035A to 10 mV
5667	First Coincidence run, a coincidence is required in the logic unit, the coincidence window is about 1usec wide (probably a lot of accidentals), source is Co-60 1 uCi, , I have increased the CFD lower threshold to remove, via hardware, photon energies below 800 keV(Detector 180-3 CFD lower threshold was 200 and detector B was 150, the rate was about 6 Hz, run time was 14 minutes 22 seconds
5668	Now the logic unit is switched to OR mode, everything else is the same as run 5667, the rate was about 1 kHz, run time was 14 minutes 25 seconds
5669	Now the logic unit is switched to OR mode, and the CFD lower threshold is reduce to about 100 keV (10 on the CFD lower threshold pot) , everything else is the same as run 5667, the rate was about 3 kHz, run time was 10 minutes, The ROC crashed probably due to the 3 kHz rate.
5670	Now the logic unit is switched to AND mode, and the CFD lower threshold is reduce to about 100 keV (10 on the CFD lower threshold pot) , everything else is the same as run 5667, the rate was about 100 Hz, run time was 13 minutes 56 seconds
5671	same as run 5670 but now there is a 100 uCi Co-60 source, the rate was about 10 Hz, run time was 1 minutes, I think there is a lot of pile up so ignore this run
5672	same as run 5670 but now there is NO source, the rate was about 2 Hz, run time was 20 hours 6 minutes, The coincidence window of 1 usec seems to be way to wide.
5673	same as run 5667 but now the coincidence window is reduced from 1 usec to 10 ns, the rate was about 9 Hz, run time was 11 minutes, 32 seconds.
5674	same as run 5667 but now the Logic unit is in OR mode and the CFD output pulse width is 5 ns using a leading edge discriminator, the rate was about 3 kHz, run time was 1 minutes, 27 seconds.
5675	same as run 5673 but now the CFD output pulse width is 200 ns using a leading edge discriminator, the rate was about 70 Hz, run time was 8 minutes, 25 seconds.
5676	same as run 5674 but now the source is 100 nCi instead of 1 uCi, the CFD output pulse width is 2 ns using a leading edge discriminator, the rate was about 700 Hz, run time was minutes, seconds.
5685	same as run 5676 but the logic module is in AND mode, the CFD output pulse width is 100 ns using a leading edge discriminator, the rate was about 10 Hz, run time was 14 minutes, 1 seconds.
5686	same as run 5676 but the logic module is in OR mode, the CFD output pulse width is 100 ns using a leading edge discriminator, run time was 4 minutes, seconds. Something wrong with the readout, I see 4 peaks for Co-60 when there were only 2 in other runs (Maybe deadtime is too high and I am getting pile up?)
5687	same as run 5685 but source is Na-22 1 uCi, the CFD output pulse width is 100 ns using a leading edge discriminator, the rate was about Hz, run time was 4 minutes, seconds.
5688	same as run 5687 but increase low energy discrimination from 10 to 15, the CFD output pulse width is 100 ns using a leading edge discriminator, the rate was about Hz, run time was minutes, seconds.
5689	same as run 5687 but increase low energy discrimination from 15 to 30, the CFD output pulse width is 100 ns using a leading edge discriminator, the rate was about Hz, run time was minutes, seconds.
5691	same as run 5689 but source is now 1 uCi Co-60, the rate was about 2680 Hz, run time was minutes, seconds.
5692	same as run 5691 but Logic unit is in AND mode now, the rate was about 50 Hz, run time was 5 minutes, 54seconds. refill Det B with LN2
5693	same as run 5692 , the rate was about 50 Hz, run time was 3hours 14 minutes, 56 seconds. first run after filling Det B with LN2
5694	same as run 5692 but now the time window is < 2 ns, the rate was about 0.2 Hz, run time was 17 hours 41 minutes, 46 seconds. This run suggests a 12 nsec delay is needed for TDC16 (Detector 180-2). I will use the CFD for Detector 180-2 to delay the signal by 12 nsec.

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

CPAA_r5691-5693

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

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.

[math]{197 \atop\; }Au (\gamma,n){196 \atop \; }Au[/math]

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.

Pt-196 decay EC decay

[math]{196 \atop \; }Au \rightarrow {196 \atop \; }Pt^* [/math] 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

proton knockout

[math]{197 \atop\; }Au-79 (\gamma,p){196 \atop \; }Pt-78[/math]

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
2. Ba-132 83 && 360 http://www.nndc.bnl.gov/nsr/nsrlink.jsp?1996KU01 http://www.nndc.bnl.gov/nsr/nsrlink.jsp?2002GA01
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
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

Pre-Irradiation Measurements

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.
5723	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 hours min, sec. Rate was Hz

I see a coincidence line at 1274 +/- 4 keV and 511 +/- 1 keV 70 days after irradiation.

[math]{22\atop 11 }Na \rightarrow {22 \atop 10 }Ne^* + \beta + \nu_e \rightarrow {22 \atop 10 }Ne + \gamma (1275 keV)[/math]

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 I should look for lines within intervals of +/- 2 keV

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. Is this accidental? 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

NUCID = 67Zn A = 67 Z = 30 N = 37

(1270,511)

NUCID = 72As A = 72 Z = 33 N = 39

(1273,510)

NUCID = 32P A = 32 Z = 15 N = 17

(1269, 512)

NUCID = 61Cu A = 61 Z = 29 N = 32

(1268,510)

NUCID = 34S A = 34 Z = 16 N = 18

(1274,509)

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