Re: cosmic rays

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

On Fri, 27 Sep 2002, john grant wrote:



> How does the fact that the cosmic rays go all the way through the body factor into

> this?

>

> BERNARD L COHEN wrote:

>

> >         All natural radiation strikes an average person's body about

> > 15,000 times per second. Cosmic rays account for less than 1/4 of this, or

> > about 3500 times per second.



	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.



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