Re: [fluka-discuss]: Normalization for the 2nd step of a two-step process

From: Vahan Petrosyan <vahan4033_at_gmail.com>
Date: Sat, 16 Nov 2013 02:27:45 +0400

Hi! everyone I am a begginer in FULK and btw. I want to ask.

1) what does mean "normalization factor 717984/702M to the weight of the
primary" ? why one need it?
      1.1) what mathematical opration or formula it is?

Thanks!

On 11/15/2013 10:35 PM, Mina Nozar wrote:
> Dear Vittorio,
>
> Thank you.
>
> But where (how) exactly do I apply the additional normalization factor
> of (717984/702M)? Is this at post-processing stage of the second step
> or before?
>
> Best wishes,
> Mina
>
> On 13-11-15 08:08 AM, Vittorio Boccone wrote:
>> Hi Mina,
>> I assume you are saving the file with those line (which I extracted
>> from the previous long topic)
>> > WRITE(IODRAW,100) JTRACK,XSCO,YSCO,ZSCO,CXTRCK,CYTRCK,CZTRCK,
>> > & ETRACK-AM(JTRACK),WTRACK
>>
>> WTRACK is indeed the weight of the particle with respect to primary
>> that generated it.
>>
>> You get 717984 particle from the first step out of 702M, to be used
>> as primaries for the second step.
>>
>> For this reason you must apply an additional normalization factor
>> 717984/702M to the weight of the
>> primary which you load in the second step.
>>
>> You then loop over the 700K particle (400M times) in a random way or
>> sequentially. The random seed
>> history is what makes the history of the particle different. You just
>> need to be sure that this 700K
>> are a representative sample of your real distribution.
>>
>> Best regards
>> Vittorio
>>
>> Dr. Vittorio Boccone - University of Geneva
>>
>> o Address:
>> UniGe: Département de physique nucléaire et corpusculaire
>> 24 Quai Ernest-Ansermet, CH-1211 Geneve 4, Switzerland
>> CERN: CERN, CH-1211 Geneve 23, Switzerland
>>
>> o E-mail:
>> dr.vittorio.boccone_at_ieee.org <mailto:dr.vittorio.boccone_at_ieee.org>
>> (professional)
>> vittorio.boccone_at_gmail.com <mailto:vittorio.boccone_at_gmail.com>
>> (private)
>>
>> On 14 Nov 2013, at 23:06, Mina Nozar <nozarm_at_triumf.ca
>> <mailto:nozarm_at_triumf.ca>> wrote:
>>
>>> Hello everyone,
>>>
>>> I am not sure of the normalization in the 2nd step of a two-step
>>> process.
>>>
>>> In the first step:
>>>
>>> I write out particles I am interested in (type and boundary)
>>> crossing via mgdraw.f and USRDUMP. Since I am using importance
>>> biasing in the first step, I write out the weights as well.
>>>
>>> So in the output file I have lines like this:
>>>
>>> Id, x, y, z, cosx, cosy, cosz, kinetic energy, weight
>>> *8 -.2635E+03 0.6864E+02 0.2944E+04 -0.6332783577022189E+00
>>> -0.3722034999484587E+00 -0.6785448226109299E+00 0.6606E-06 0.6400E-05**
>>> **7 -.2635E+03 0.6589E+02 0.2946E+04 -0.4822515648543289E+00
>>> -0.8047950128287192E+00 0.3460323908560768E+00 0.8389E-03 0.2133E-06**
>>> **7 -.2635E+03 0.7252E+02 0.2941E+04 -0.7274812055368878E+00
>>> 0.1436728665088557E+00 -0.6709166885834075E+00 0.1702E-03 0.2133E-06*
>>>
>>> Out of the 702M primaries in the first step, I get 717984 particles
>>> written out.
>>>
>>>
>>> In the second step:
>>>
>>> Using source.f, I read in the above info. and assign the particle
>>> weights:
>>>
>>> *WTFLK(NPFLKA) = Weight(line)
>>> WEIPRI = WEIPRI + WTFLK(NPFLKA)*
>>>
>>> Manual says *WEIPRI* is the total weight of the primary particles.
>>> So is this basically the sum of weights (column 7 above) of
>>> particles that get read in? Does *WEIPRI* get written out somewhere?
>>>
>>> I then set up several runs (450 M events). So I think the way I
>>> understand it, the program loops over the 717984 several times to
>>> get to the 450 M primaries. But does the looping happen in a random
>>> way? Am I correct to think that the sum of column 7 in the input
>>> file IS NOT equal to the *WEIPRI*?
>>>
>>> And my last question is how to normalize information in (per
>>> primary) from the second step, given the above?
>>>
>>>
>>> Thank you very much,
>>> Mina
>>>
>>>
>>>
>>
>
Received on Sat Nov 16 2013 - 00:16:43 CET