Pico Tech - Am Spectrums

Radiation Detection / Theremino Mca / Theremino Mca Spectrums / Theremino Pmt Adapter


Something strange about Am241 spectrum

I don't understand (yet) how the lower peak of Am241 appear and why.
Am241 supposed to have the lower peaks at 26.34KeV (only 2.4%) and 13.92KeV (13.03%).
But the lower peak appears often around 29KeV...

Maybe because I don't know yet how to calibrate Theremino Mca.

All these are done with Rap-47 + Theremino Pmt Adapter (made by Alessio !) + Theremino Mca

What do you think about these?

Please let me know at http://tech.groups.yahoo.com/group/GammaSpectrometry/message/12491
or nkom A-T pico.dreamhosters d-o-t com

EDIT:

Alain showed the thread about this matter.
http://tech.groups.yahoo.com/group/GeigerCounterEnthusiasts/message/53728

So, it might be because of Np

EDIT 2:

I started to think about the possibility of XRF from Iodine (in detector), etc.
See the end of the page for the extensive list of possibilities.

See Xrf Spectrums and Xrf Spectrums Part Two


At beginning:

Am241 Smoke detector with metal (alminium? tin?) cover
Lower peak at 28 to 29 KeV (instead of 26 or 14KeV)


When I put the Am241 source (taken out from the smoke detector) direct on the detector.

Lower peak seems to have 2 peaks of 18KeV and 29KeV (more or less)
And there seems to be 2 peaks at 110 and 120KeV


When I place the Am241 source at 2cm from the detector, I get big 18 KeV (hiding the trace of 29KeV peak)


It's about the same when I place the source at 5cm


When I put Am241 source behind metal (tin?) cookie container rid at 2cm, I get about the same result as the smoke detector (with the metal cover)


When I put Am241 source behind thick glass. There seems to be slight change of the 59KeV peak (showing at a few KeV lower). These tests are all done with same setting at same location within several minutes that temperature drift and other factors shouldn't cause this.


When I put the Am241 source facing back (away from the Rap-47 detector)


When I put the Am241 source facing back (away from the Rap-47 detector) and placing metal plate (tin?) against it.
Metal plate --- Am241 facing metal plate --- Rap-47


When I put the Am241 source facing side at 90 degree angle at 2cm


When I put the Am241 source facing side at 90 degree angle at 5cm




2nd trial with slightly different base line test setting

It doesn't look like placing something over the Am241 source at 45 degree angle change a lot.

Now, I have to take out more Am241 buttons from smoke detectors to check lower energy calibration and resolution.


Am241 source at 5cm facing side at 90 degree angle


http://pico.dreamhosters.com/img/HISTOGRAM_2013_05_16_09_39_16-Rap47-Am241-5cm.txt


Am241 source at 2cm facing side at 90 degree angle


Am241 source at 2cm facing side at 90 degree angle with tin plate at 45 degree angle


http://pico.dreamhosters.com/img/HISTOGRAM_2013_05_16_09_53_24-Rap47-Am241-2cm-90deg-tin.txt


Am241 source at 2cm facing side at 90 degree angle with aluminum at 45 degree angle


http://pico.dreamhosters.com/img/HISTOGRAM_2013_05_16_09_54_40-Rap47-Am241-2cm-90deg-al.txt


Am241 source at 2cm facing side at 90 degree angle with thick glass at 45 degree angle


http://pico.dreamhosters.com/img/HISTOGRAM_2013_05_16_09_55_57-Rap47-Am241-2cm-90deg-glass.txt


Am241 source at 2cm facing side at 90 degree angle with stainless steel at 45 degree angle


http://pico.dreamhosters.com/img/HISTOGRAM_2013_05_16_09_57_55-Rap47-Am241-2cm-90deg-Fr.txt



I did more testing, but these are for learning different base line test setting.
So, I put then in another page: Theremino Mca Base Line Test


After Base line test trials. I broke up some more smoke detectors and tried XRF, to know the accuracy of my setup.

Xrf Spectrums


Alain showed the thread about this matter.
http://tech.groups.yahoo.com/group/GeigerCounterEnthusiasts/message/53728

Np237 at 29.37KeV causing the peak we see?


(Spectrum provided by Tom)
http://anti-proton.com/Am241_spectrum.png


17.7KeV seems to be from Np237 Xray (Pa + U Xray?).


(Spectrum provided by Alain)
http://xa.yimg.com/kq/groups/10603698/sn/1112386343/name/Am241_Xray_.jpg


(Another Spectrum provided by Alain)
https://xa.yimg.com/kq/groups/16117819/or/361361187/name/Am-241_0_40kev.jpg


(Spectrum posted by Geo)
https://xa.yimg.com/kq/groups/16117819/or/1745417430/name/Pd-from-Am-241-Pellet-See-La-and-Lb-lines.jpg
https://groups.yahoo.com/neo/groups/GammaSpectrometry/conversations/messages/19122

https://groups.yahoo.com/neo/groups/GammaSpectrometry/conversations/messages/19118

Explanations:
http://www.madehow.com/Volume-2/Smoke-Detector.html#ixzz2GrfWHZko

So, we may see X-ray Ag 22.16 KeV, Au 9.71 and 11.44KeV,
in addition to Np237 29.37KeV, 17.74KeV, 13.95KeV.


http://labs.physics.berkeley.edu/mediawiki/images/f/fd/COMimage02.jpg


http://www.amptek.com/xr100cr_b.png

Am241 spectrum with CZT detector

http://www.amptek.com/anczt2_q.png

On line gamma ray catalog (including info about Xray peaks)
http://web.archive.org/web/20121010022027/http://www.inl.gov/gammaray/catalogs/ge/catalog_ge.shtml

Am241
http://web.archive.org/web/20121010022027/http://www.inl.gov/gammaray/catalogs/ge/pdf/am241.pdf
http://web.archive.org/web/20121010022027/http://www.inl.gov/gammaray/catalogs/ge/pdf/am241_new.pdf

Np237
http://web.archive.org/web/20121010022027/http://www.inl.gov/gammaray/catalogs/ge/pdf/np237_new.pdf

Pa233
http://web.archive.org/web/20121010022027/http://www.inl.gov/gammaray/catalogs/ge/pdf/pa233_new.pdf

U233
http://web.archive.org/web/20121010022027/http://www.inl.gov/gammaray/catalogs/ge/pdf/u233_new.pdf


Are we seeing XRF peaks of detector?

I realized XRF peaks of Iodine (28.3Kev, 28.6KeV, 32.3KeV) may create a peak around 29KeV.

Also, Cs (30.625KeV and 30.972KeV) are pretty close to the 29KeV peak we see, for those who using CsI (Tl) probe like Rap-47.

And my XRF experiments show that Iodine "lights up" very well with XRF.

So, 29KeV peak can be the mixture of Np237 and Iodine (Cesium) XRF.

If we have to think about the XRF, we may have to think about the materials used for smoke detector button, such as Au, Ag, and possible Fe, Cr, etc (making up the button enclosure).


Possible peaks we are seeing

Gamma peaks

Am241 A 432.70 Y

13.92/1.304E+01 (13.04%)

26.34/2.400E 00 (2.4%)

59.53/3.570E 01 (35.7%)

Np237 A 2.14MY

11.37/1.152E+00

13.27/1.920E+01 (19.2%)

16.63/2.528E+01 (16.63%)

29.37/1.292E+01 (12.92%)

86.52/1.260E+01 (12.6%)

92.27/1.590E+00 (1.59%)

94.72/7.647E-01 (0.76%)

95.86/2.575E+00 (2.575%)


XRF peaks

1,0,Am,La2,14411.90,14411.90
1,0,Am,La1,14617.20,14617.20
1,0,Am,Lb2,17676.50,17676.50
1,0,Am,Lb1,18852.00,18852.00
1,0,Am,Lg1,22065.20,22065.20

Am241 daughter
1,0,Np,La2,13759.70,13759.70
1,0,Np,La1,13944.10,13944.10
1,0,Np,Lb2,16840.00,16840.00
1,0,Np,Lb1,17750.20,17750.20
1,0,Np,Lg1,20784.80,20784.80

Np237 daughter
1,0,Pa,Ma1,3082.30,3082.30
1,0,Pa,La2,13122.20,13122.20
1,0,Pa,La1,13290.70,13290.70
1,0,Pa,Lb2,16024.00,16024.00
1,0,Pa,Lb1,16702.00,16702.00
1,0,Pa,Lg1,19568.00,19568.00
1,0,Pa,Ka2,92287.00,92287.00
1,0,Pa,Ka1,95868.00,95868.00
1,0,Pa,Kb1,108427.00,108427.00

Pa233 daughter
1,0,U,Ma1,3170.80,3170.80
1,0,U,La2,13438.80,13438.80
1,0,U,La1,13614.70,13614.70
1,0,U,Lb2,16428.30,16428.30
1,0,U,Lb1,17220.00,17220.00
1,0,U,Lg1,20167.10,20167.10
1,0,U,Ka2,94665.00,94665.00
1,0,U,Ka1,98439.00,98439.00
1,0,U,Kb1,111300.00,111300.00


Button

Silver
1,0,Ag,La2,2978.21,2978.21
1,0,Ag,La1,2984.31,2984.31
1,0,Ag,Lb1,3150.94,3150.94
1,0,Ag,Lb2,3347.81,3347.81
1,0,Ag,Lg1,3519.59,3519.59
1,0,Ag,Ka2,21990.30,21990.30
1,0,Ag,Ka1,22162.92,22162.92
1,0,Ag,Kb1,24942.40,24942.40

Gold
1,0,Au,Ma1,2122.90,2122.90
1,0,Au,La2,9628.00,9628.00
1,0,Au,La1,9713.30,9713.30
1,0,Au,Lb1,11442.30,11442.30
1,0,Au,Lb2,11584.70,11584.70
1,0,Au,Lg1,13381.70,13381.70
1,0,Au,Ka2,66989.50,66989.50
1,0,Au,Ka1,68803.70,68803.70
1,0,Au,Kb1,77984.00,77984.00

Steel?
1,0,Fe,La2,705.00,705.00
1,0,Fe,La1,705.00,705.00
1,0,Fe,Lb1,718.50,718.50
1,0,Fe,Ka2,6390.84,6390.84
1,0,Fe,Ka1,6403.84,6403.84
1,0,Fe,Kb1,7057.98,7057.98

Nickel?
1,0,Ni,La2,851.50,851.50
1,0,Ni,La1,851.50,851.50
1,0,Ni,Lb1,868.80,868.80
1,0,Ni,Ka2,7460.89,7460.89
1,0,Ni,Ka1,7478.15,7478.15
1,0,Ni,Kb1,8264.66,8264.66

What else?


For NaI(Tl) Detector:

1,0,Na,Ka1,1040.98,1040.98
1,0,Na,Ka2,1040.98,1040.98
1,0,Na,Kb1,1071.10,1071.10

For CsI(Tl) detectors:

1,0,Cs,La2,4272.20,4272.20
1,0,Cs,La1,4286.50,4286.50
1,0,Cs,Lb1,4619.80,4619.80
1,0,Cs,Lb2,4935.90,4935.90
1,0,Cs,Lg1,5280.40,5280.40
1,0,Cs,Ka2,30625.10,30625.10
1,0,Cs,Ka1,30972.80,30972.80
1,0,Cs,Kb1,34986.90,34986.90

For both

Iodine is bright under XRF
1,0,I,La1,3937.65,3937.65
1,0,I,Lb1,4220.72,4220.72
1,0,I,Lb2,4507.50,4507.50
1,0,I,Lg1,4800.90,4800.90
1,0,I,Ka2,28317.20,28317.20
1,0,I,Ka1,28612.00,28612.00
1,0,I,Kb1,32294.70,32294.70

1,0,Tl,Ma1,2270.60,2270.60
1,0,Tl,La2,10172.80,10172.80
1,0,Tl,La1,10268.50,10268.50
1,0,Tl,Lb1,12213.30,12213.30
1,0,Tl,Lb2,12271.50,12271.50
1,0,Tl,Lg1,14291.50,14291.50
1,0,Tl,Ka2,70831.90,70831.90
1,0,Tl,Ka1,72871.50,72871.50
1,0,Tl,Kb1,82576.00,82576.00


Recap: From lower to higher, possible peaks

17KeV peak

In between

29KeV peak

Main peak

Others


For definite answer, I guess we need HPGE or something with very high resolution, and/or we need to cross check smoke detector spectrum against pure Am241 source disk (to eliminate XRF from Ag, Au, etc, at least).


Last modified : Sun Oct 4 11:03:52 2015 Maintained by nkom AT pico.dreamhosters.com