Re: Positron fluence

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