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RE: Cosmic ray muons
Maybe the following will help:
The median energy for muons at sea level is about 2 GeV (NCRP 94).
The stopping power of 2 GeV muons in water is approximately 2 MeV per cm
(Turner 1995).
In water, as opposed to air, the average energy required to produce an ion
pair (one ionized atom) is 22 eV.
Paul Frame
Professional Training Programs
Oak Ridge Associated Universities
-----Original Message-----
From: john grant [mailto:grantjoh@pacbell.net]
Sent: Tuesday, November 27, 2001 12:07 PM
To: Radsafe
Subject: Re: Cosmic ray muons
I think that I did not ask my question correctly. I am wondering how many
atoms in our bodies are ionized when a high energy muon travels through us.
Is it necessary that ion pairs be formed? I thought it is just a matter of
an
electron being knocked loose from an atom.
The end result I am hunting for is a comparison of a years worth of cosmic
ray
muons hitting the thyroid gland and an equivalent amount of iodine 131 being
absorbed in the thyroid.
John Grant
"Jacobus, John (OD/ORS)" wrote:
> John,
> The muon has a rest mass of 107 MeV, and interacts weakly with nucleons.
> When it decays after 2 microseconds, it decays into an electron, neutrino,
> and antineutrino as occurs in beta decay. Assuming that the maximum decay
> energy is transferred to the electron, the energy would be 206 MeV. If
the
> ionizaiton energy is 33 eV, there could be over 6.2 E6 primary ion pairs
> formed.
>
> The range of a 206 MeV electron is 103.5 g/cm^2, or 103.5 cm in water.
>
> -- John
> John Jacobus, MS
> Certified Health Physicist
> 3050 Traymore Lane
> Bowie, MD 20715-2024
>
> E-mail: jenday1@email.msn.com (H)
>
> -----Original Message-----
> From: john grant [mailto:grantjoh@pacbell.net]
> Sent: Saturday, November 24, 2001 11:57 AM
> To: Radsafe
> Subject: Cosmic ray muons
>
> When a cosmic ray muon travels through a 6 foot tall person how many atoms
> will
> it ionize?
>
> John Grant
>
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