Dear Shirley,
for your purpose a Monte Carlo code is probably not the best tool.
Read instead the famous article of Bruno Rossi and Kenneth Greisen:
Cosmic-ray theory, Rev. Mod. Phys. 13, 240 (1941).
The theory of gamma/electron showers neglecting the ionization is called
Approximation A and is described in Part II, section A (p. 273-288).
The theory with ionization is Approximation B, described in section B
(p. 288-297).
That theory has been further improved by other authors, but Rossi's
Approximations A and B have remained its basic pillars for many years.
Nowadays, the availability of computer programs has made that theory
to be nearly forgotten. But it is a pity: it is a beautiful theory which
can help to better understand electromagnetic showers.
Alberto
On Thu, 6 Mar 2014, Shirley Li wrote:
> Dear Alberto,
> Thank you for your reply!
>
> I'm studying the properties of E&M showers. For example, I have a 10 GeV
> gamma initiated shower, and I plotted the track length of gammas and
> electrons (with USRTRACK card) as a function of energy. And I got a nice
> ~1/E^2 behavior. But, from a simple E&M shower model (1 gamma pair produce
> to 2 e, 1 e Bremsstrahlung to 1 e + 1 gamma, all particles travel one
> interaction length before they split to more particles), the track length
> should go as 1/E. I wanted to see if there is a simple explanation to the
> extra 1/E power. My first guess is ionization of the electrons. That's why
> I wanted to turn the ionization loss off, and to see if I get track length
> scale as 1/E...
>
> Best,
> Shirley
>
>
> On Thu, Mar 6, 2014 at 3:21 AM, Alberto Fasso' <fasso_at_slac.stanford.edu>
> wrote:
> Dear Shirley,
>
> no, it is not possible to turn off electron/positron ionization
> energy loss.
> May I ask for which purpose would you like to have it?
>
> Alberto
>
>
> On Wed, 5 Mar 2014, Shirley Li wrote:
>
> Dear FLUKA users,
> I'm studying electromagnetic showers in water. I'm
> wondering if there is a
> way to turn off electron/positron ionization energy
> loss.
>
> Thank you very much!
> Shirley
>
>
>
>
--
Alberto Fasso`
SLAC-RP, MS 48, 2575 Sand Hill Road, Menlo Park CA 94025
Phone: (1 650) 926 4762 Fax: (1 650) 926 3569
fasso_at_slac.stanford.edu
Received on Wed Mar 12 2014 - 15:58:48 CET