Re: Gamma Camera


"west" <westley@xxxxxxxxxxxxxxx> writes:

> "Craig Markwardt" <craigmnet@xxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
> news:on7jc1nkq5.fsf@xxxxxxxxxxxxxxxxxxxxxxx
> >
> > "west" <westley@xxxxxxxxxxxxxxx> writes:
> > > I have access to several types of used Nuclear Medicine gamma cameras. I've
> > > often entertained the idea to convert one for astro-gamma imaging. I'm not
> > > much of an astronomer but am somewhat knowledgeable with gamma cameras. The
> > > main problem that has always stopped me from pursuing this idea, is the fact
> > > that the large sodium-iodine crystal can fracture if there's an ambient
> > > temperature change of >6 degrees F in < 1 hour. Outdoor temperature
> > > fluctuations ... (well I'm sure you understand).
> > > I apologize if this is not the correct NG for my question. Perhaps I can be
> > > directed to a more appropriate one? Thank you.
> >
> > Your main problem will be that extraterrestrial gamma rays do not
> > penetrate the atmosphere to sea level. That's why most gamma-ray (and
> > X-ray) instruments are launched into space, or at least lofted by high
> > altitude balloon.
....
> Thanks for the reply, Craig. Understood. It has always been a struggle to
> accurately subtract background radiation from the total, which at times can
> be significant . This has always been known as "background cosmic
> radiation." Do you know what type of radiation this is?

I wasn't actually talking about subtracting background. What I meant
was that gamma-rays from space cannot penetrate the atmosphere deeply
enough to reach sea level. Other radiation like cosmic rays don't
usually penetrate either; they interact in the upper atmosphere, but
they produce high energy particle showers which can reach sea
level. [*] That is usually what is meant by "cosmic rays" on earth.
The sun, supernova remnants, active galaxies are all sources of cosmic
rays.

Craig

[*] - internet search term "cosmic ray shower"

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Craig B. Markwardt, Ph.D. EMAIL: craigmnet@xxxxxxxxxxxxxxxxxxxxxxxxxx
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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Relevant Pages

  • Re: Gamma Camera
    ... >> much of an astronomer but am somewhat knowledgeable with gamma cameras. ... > Craig B. Markwardt, Ph.D. ... accurately subtract background radiation from the total, ...
    (sci.astro)
  • Re: Gamma Camera
    ... > I have access to several types of used Nuclear Medicine gamma cameras. ... > often entertained the idea to convert one for astro-gamma imaging. ... > much of an astronomer but am somewhat knowledgeable with gamma cameras. ... Craig B. Markwardt, Ph.D. ...
    (sci.astro)