Search found 7 matches

by GEOelectronics
09 May 2019, 05:00
Forum: Spectrum
Topic: Introduction and Rain Spectrum
Replies: 3
Views: 2414

Re: Introduction and Rain Spectrum

Hi Massimo. You mentioned having no lead shield, if there were a lead shield I would guess X-Rays from the stable lead in it causing the ~77 peak. This is common as the stable lead is being excited by random cosmic rays, emitting it's characteristic X-Ray into the probe. We solve that by a copper li...
by GEOelectronics
09 May 2019, 04:54
Forum: Spectrum
Topic: Greetings from Victoria, BC Canada + Cs137 spectrum with odd peak
Replies: 14
Views: 7594

Re: Greetings from Victoria, BC Canada + Cs137 spectrum with odd peak

Nice catch Conor. George Dowell Well the problem seems to be solved now. I tried upping the voltage slightly to 845V and the parasitic peak dissipated quickly. So, it appears that the theremino PMT adapter has a stability problem at its lowest setting of 800V. Measuring the output at the lowest volt...
by GEOelectronics
09 May 2019, 04:16
Forum: General discussion
Topic: Radiodating using NaI(Tl)
Replies: 11
Views: 8368

Re: Radiodating using NaI(Tl)

First question: Geologic radiometric dating or organic radiometric dating? Organic can be definitely be ruled out (C-14) because sodium iodide (Tl) can't measure stable carbon C-12 to radioactive C-14 ratio. George Dowell Hi All, I had a query this week from a Phd candidate asking me if it is possib...
by GEOelectronics
09 May 2019, 04:00
Forum: Spectrum
Topic: Zn-65 Spectrum Mystery
Replies: 9
Views: 5627

Re: Zn-65 Spectrum Mystery

"The following spectrum and counting rate vs. time plot was collected immediately after removing the Zn-65 source (and placing it in a lead pig and locating it 30 feet away!): " To test Steve's theory, set up same outfit, use Co-60 until the counts reach same level (about 10k counts it loo...
by GEOelectronics
09 May 2019, 03:52
Forum: Spectrum
Topic: Zn-65 Spectrum Mystery
Replies: 9
Views: 5627

Re: Zn-65 Spectrum Mystery

"Zn-65 decays to Cu-65 which is, to the best of my knowledge, stable and doesn't produce any gamma rays." Actually, Cu-65 emits a Gamma Ray 1.115 MeV and a plethora of X-Rays, but only does it once. Zn-65 emits only a Positron, no gamma rays or X-Rays. Alpha and Beta (all forms) are decay ...
by GEOelectronics
09 May 2019, 03:46
Forum: Spectrum
Topic: Zn-65 Spectrum Mystery
Replies: 9
Views: 5627

Re: Zn-65 Spectrum Mystery

OK now I've read the other posts and will add this: Zn-65 decays by "EC" or Electron Capture. True that IS one form of beta decay, but not the common one. EC causes an orbital electron to enter the nucleus, where it interacts with a proton, changing that proton to a neutron. This of course...
by GEOelectronics
09 May 2019, 03:19
Forum: Spectrum
Topic: Zn-65 Spectrum Mystery
Replies: 9
Views: 5627

Re: Zn-65 Spectrum Mystery

I'll reply to: "(2) Does anybody know what the "mystery peak" around 500 keV is due to?" before reading other's response. I believe it is exactly 511 keV, formed by positron annihilation. George Dowell Sorry for the long post, but I'm hoping that someone here will be able to tell...