Re: [Phys-L] geiger counter

[bernard cleyet <bernard@cleyet.org>]

                                                    ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………...i’ve included phys-l so member(s) may correct any error(s)


interleaved:

> On Mar 8, 2023, at 13:02, Anthony Lapinski <alapinski@pds.org> wrote:
>
> Responding (again) offlist.
>
> Still searching for geiger counters. I found some that detect alpha, beta, and gamma rays, and some also can detect x-rays. So for my purposes (everyday objects - Fiestaware, smoke detectors, lantern mantles, uranium glass, radium watches, etc.), are these all alpha emitters? If so, then a geiger counter which does not detect alpha rays will not detect anything from these items?

U has has a long chain of progeny (formerly, non-PC, daughters).  As a result all are emitted. (Alpha Beta and Gamma and XRF (X-ray Fluorescences). I suspect no Alphas will be detected as the glaze is not pure U.  Well some U will be on the surface.  I’ll check this soonly and report back.  

Geiger counters do not detect Gammas directly (except possibly v low energy ones, e.g.  the 14 keV one from I-57, which excites the Kalpha x-ray at ~ 6 keV .  These can be detected directly, I think due to the photo effect. The higher energy photons emit electrons from the case.  This, I presume, is the reason the shell is steel instead of Al.  This can be verified by using a semi-collimated photon beam and compare the counting rate through the window and turned Pi/2 through the shell.  (I must do this, also). G-M manufacturers also manufacture tubes with metal girdles that linearized the gamma sensitivity.  

Included here: 

https://en.wikipedia.org/wiki/Geiger–Müller_tube <https://en.wikipedia.org/wiki/Geiger%E2%80%93M%C3%BCller_tube> 

More:

K-40 emits positrons, rarely,  gammas, and betas.  (140 ppm in nature, thus we are a radiation source). https://en.wikipedia.org/wiki/Potassium-40  
Thorium. also natural (Th-232) has 11/9 progeny It has one branch.  So it emits all three. 

https://en.wikipedia.org/wiki/Thorium-232    

Radium is a “daughter of all three U-235/238 and Th.       https://en.wikipedia.org/wiki/Uranium-238 and https://en.wikipedia.org/wiki/Uranium-235  

Americium emits gammas in addition to the useful alphas.   

> Also, how useful is an x-ray detector for basic classroom purposes?
>
> I do like the EG Geiger kits.  I wish they had a case/housing to protect the components.


The kit using a large G-M box includes a case.  yes it clicks and flashes. Will the case obscure the flash? Wrong drill hole(s).  

http://cdn.goldmine-elec.com/datasheet/C8092Measurements.pdf

     http://cdn.goldmine-elec.com/datasheet/C8092V1.pdf. 


bc