Bremsstrahlung from tritium

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Hans-Jörg
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Joined: 30 Apr 2017, 16:25
Location: Germany/Saarland
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Bremsstrahlung from tritium

Post by Hans-Jörg » 22 Jul 2018, 20:47

Hello

Some years ago I bought a trigalight marker. With a reflector made from an alu sheet, I used it as a very faint torch. When completely dark, one can see things in a distance of about ten centimeter. This marker contains a tiny glass tube filled with tritium and coated in the inner side with a phosphor. This tiny tube is about 6 mm long and has a diameter of about 1 mm. The tube is hold in a stable glass tube with metal end pieces. It is about 8 mm in diameter and about 18 mm long (in total). The amount of tritium is not exactly told by the manufacturer, only ‘less than 1 GBq’, because 1 GBq is the limit for devices sold without special permission.
Tritium has a half-life of 12.32 a, a maximum beta energy of 18.6 keV with a max. intensity at 5.7 keV. So I did not expect much signal when measuring it, but there was a very clear peak at the low end of the spectrum. As I cannot calibrate exactly at that low energy, the energy of the peak (5 keV) is a bit uncertain.

My system: 2’X2’ NaI(Tl), GS-1100A, shield 20-40 mm Pb, 2mm Sn, 2mm Cu
Trigalight.pdf
(150.88 KiB) Downloaded 172 times
Background.pdf
(167.07 KiB) Downloaded 152 times

Greetings from Germany,

Hans-Jörg
Hans-Jörg

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Steven Sesselmann
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Re: Bremsstrahlung from tritium

Post by Steven Sesselmann » 23 Jul 2018, 10:46

Hans-Jorg,

Yes, I can see the little peak you are referring to, but the spectrum is quite hairy so confidence is low.

The ability of your detector to see the 5KeV peak will depend on the attenuation of the detector housing. To get a good spectrum at 5KeV you ideally need a low energy probe with a beryllium window.

The tall peak all the way to the left in your spectrum is most likely electronic noise.

Steven

Hans-Jörg
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Joined: 30 Apr 2017, 16:25
Location: Germany/Saarland
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Re: Bremsstrahlung from tritium

Post by Hans-Jörg » 23 Jul 2018, 18:22

Steven,

maybe the 5keV are not correct, but the peak at the left will only be there with the marker inside the shield. This is why I made a background spectrum with same settings. I set the left treshold to a value excluding the noise.

Hans-Jörg
Hans-Jörg

pietkuip
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Location: Växjö, Sweden
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Re: Bremsstrahlung from tritium

Post by pietkuip » 27 Oct 2018, 19:13

I took a spectrum with a Si-diode detector for the x-rays and found zinc K-alpha and K-beta:
viewtopic.php?t=35#p267
Pieter Kuiper, Växjö (Sweden)
Course lab: 3 mCi neutron source; five 3" NaI(Tl) detectors, CdZnTe detector (Amptek); lead bricks, two GDM 20

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