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.
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
- Np237 13.95KeV
17KeV peak
- U XRF 16.4KeV
- Pa XRF 16.7KeV
- U XRF 17.2KeV
- Am XRF 17.6KeV
- Np237 17.74KeV
- Am XRF 18.85KeV
In between
- Ag XRF 22.16KeV
29KeV peak
- I XRF 28.3KeV, 28.6KeV (for NaI and CsI detectors)
- Np237 29.37KeV
- Cs XRF 30.6KeV, 30.9KeV (for CsI detectors)
Main peak
- Am241 59.53KeV
Others
- Np237 86.48KeV, 92.29KeV, 95.87KeV
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).