From: <pksahani@cat.ernet.in>

Date: Thu Jun 19 2008 - 11:25:55 CEST

Date: Thu Jun 19 2008 - 11:25:55 CEST

Dear Battistoni,

Thank you very much for your answer. yes, I also got similar Spectra

for e-,e+, and positron as the one you have sent.Now I am satisfied

with the spectrum.

Thank You once again.

With regards

Prasanta Kumar Sahani

Scientific Officer-C

Raja Ramanna Centre for Advanced Technology

Indore-452013

INDIA

*> 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
*

*>>
*

*>
*

*>
*

*>
*

*>
*

Received on Thu Jun 19 14:40:01 2008

*
This archive was generated by hypermail 2.1.8
: Thu Jun 19 2008 - 14:40:16 CEST
*