From: Giuseppe Battistoni <Giuseppe.Battistoni@mi.infn.it>

Date: Thu Jun 19 2008 - 09:26:11 CEST

Received on Thu Jun 19 09:33:34 2008

Date: Thu Jun 19 2008 - 09:26:11 CEST

Dear Prasanta,

Your consideration is not exact:

if you have a gamma of energy E0 which then undergoes a pair-production

process, the distribution of kinetic energy of the positron (or of

the electron) ranges from 0 to (E0 - 2*me), while (E0 - 2*me)/2 is the

average kin. energy of the positron (or of the electron). In other words,

the sum of kinetic energy of e+ and e- is E0 - 2*me and each member

of the pair access the whole range (and the other is of course balancing

the first).

Now, if you have an electron beam of 2.5 GeV, you can really produce

a photon of energy close to the electron one which then can produce a

positron (of course the probability is small) up to the maximum value.

We have not your input file, but we made the exercise of sending

electrons of 2.5 GeV onto a lead target (of course the thickness is

surely different from yours) and the correct resulting

spectrum of gamma, e- and e+ resulting after the target

is attached to this mail. You should get a similar result.

Best regards

Anna Ferrari & Giuseppe Battistoni

On Wed, 18 Jun 2008 pksahani@cat.ernet.in wrote:

*> Dear Fluka Users,
*

*> I am a new FLUKA user.I used very simple geometry to calculate the
*

*> electron ,photon and positron fluence after a lead target.I incident
*

*> 2.5GeV electron pencil beam on lead target and by using the USRBDX
*

*> card i score the fluence after the target. I got very nice spectra
*

*> for e- and photon from 0 to Maximum (2.5GeV) as expected . But the
*

*> e+ spectrum also shows a distribution from 0 to 2.5GeV. But i think
*

*> the positron production is only through pair production , if so then
*

*> it must go from 0 to 1.25GeV[(2.5GeV-1.02MeV)/2 ]. Then how in FLUKA
*

*> simulation I got the spectrum upto 2.5GeV.
*

*> So please help me in this regard.
*

*>
*

*> Thank You
*

*>
*

*> With Regards
*

*> Prasanta Kumar Sahani
*

*> Scientific Officer-C
*

*> Raja Ramanna Centre for Advanced Technology
*

*> Indore-452013
*

*> INDIA
*

*>
*

- APPLICATION/pdf attachment: test.pdf

*
This archive was generated by hypermail 2.1.8
: Thu Jun 19 2008 - 09:33:34 CEST
*