RE: [fluka-discuss]: Best way to generate decay-like unidirectional electrons

From: Joachim Vollaire <joachim.vollaire_at_cern.ch>
Date: Sun, 15 Sep 2013 20:44:39 +0000

Hi Francesco

The most elegant and efficient (thus require some little time investment on your side) is definitely option 3 but the energy could be specified using the input file and isotope/HI-PROPE card (don't touch the energy assignment part of the routine).
  
What you need to modify via the source routine is the direction cosine to ensure that the decay radiation goes into a beam like direction

(this part of the input)
* Cosines (tx,ty,tz)
      TXFLK (NPFLKA) = UBEAM
      TYFLK (NPFLKA) = VBEAM
      TZFLK (NPFLKA) = WBEAM

To ensure it is working properly, it is always good to make a sanity check using a scoring volume/surface (usrtrack/usrbdx) and an energy dependant spectrum without any interaction....

Hoping it will work
Cheers
Joachim


-----Original Message-----
From: owner-fluka-discuss_at_mi.infn.it [mailto:owner-fluka-discuss_at_mi.infn.it] On Behalf Of Francesco Collamati
Sent: 13 September 2013 12:48
To: fluka-discuss_at_fluka.org
Subject: [fluka-discuss]: Best way to generate decay-like unidirectional electrons

Dear Fluka experts, I write to you not exactly for a question, but I would say for an advice!
I would like to simulate a pencil beam (thus unidirectional) of electrons having the energy spectrum of Ittrium-90 decay (endpoint ~2.3MeV).
I thought a few ways to do it, but I would ask to you which one (of this, or of others!) is the smarter in term of CPU usage:
- Use Isotope Card, that is properly producing electrons, but in the whole solid angle. Then I can kill all the particles not in the right direction via som,e biasing technique, or using a very small sphere of "blackhole" with a small hole.
- I saw in Flair that in Beam card there is under DeltaP a choice named "function", that however seems not to be selectable. Is it deprecated?
- Use a user routine to create particles in my direction, but I would need an algorithm to generate electrons from Ittrium decay..

So, am I forgetting a smarter way to do this?
Consider that I am going to use this simulation for simple small cases. So if option number 1 (the simplest for me to setup) is let's say just 50% slower than option number 3...!
Thanks for your attention

p.s. I am using the last fluka and flairs..

Francesco Collamati
Received on Sun Sep 15 2013 - 23:34:52 CEST