Not scoring dose correctly

From: Joel DeWitt <>
Date: Tue, 7 Oct 2008 15:58:12 -0500


Before getting to my question about dose scoring, I would like to pass
on some information regarding my earlier post
 It seems the Weaver range-energy code and FLUKA agree--within
2-3%--on the LET in water for the depth range of 0-30 g/cm2 of
aluminum. Before I had just looked at the LET in some baseline
materials (not water), and without any change in energy due to
shielding. The placement of the primary ionization peak for 30 g/cm2
obtained from FLUKA in my earlier post remains a mystery, as do our
experimental results.

As a check on my understanding of dose scoring using USRBIN and the
generalized particle DOSE (in GeV/g), I did a short run by dosing a
box of water with 1 nGy using 230 MeV protons. A back-of-the-envelope
calculation gave an estimate of about 9,751 protons to deliver this
test dose. I get instead a dose of about 0.25 pGy. The energy has to
go somewhere, which means I'm not doing this correctly.

Kind regards,
Joel DeWitt
Oklahoma State University

Received on Wed Oct 08 2008 - 13:06:39 CEST

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