Re: cosmic rays

[BERNARD L COHEN <blc+@PITT.EDU>]

On Mon, 30 Sep 2002, john grant wrote:



>

>

> BERNARD L COHEN wrote:



> >         These numbers aree estimated from the doses. For total radiation,

> > I use 80 mrem per year = 80 mrad per year. I take the average energy of

> > gamma rays in natural radiation deposited in the body to be 0.6 MeV, and

> > the average mass of the body to be 70 Kg. Using the definition 1 mrad = 1

> > E-5 joules deposited per Kg, it is straightforward to calculate the number

> > of gamma rays.

> >         I didn't do any deep thinking about the difference between cosmic

> > rays and other natural radiation, but just assumed that the number of

> > gamma rays was proportional to the dose. My apologies if a more accurate

> > treatment was required.

>

> A 0.6 MeV gamma would likely travel one inch or less in the body.

> A high energy muon would travel more than 60 inches in a standing person.



	0.6 MeV is the energy I assumed to be absorbed in the body.

I explained how my rough calculation was done. Anyone is free to

modify it as he pleases.

	 I believe that the principal exposure from cosmic

rays is from the secondary gamma rays they produce. If I am wrong about

this, I apologize and would be interested in being corrected..The

calculations I refer to were done at least 15 years ago so I don't

remember much about their details.



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