[fluka-discuss]: USRYield weighted angles and threshold cards

From: Alvin Sashala Naik <alvin.sashala.naik_at_cern.ch>
Date: Thu, 26 Jun 2014 09:19:25 +0000

Dear Fluka users,

I am trying to score the double differential distribution of protons crossing a surface. I require their energy and LET distribution of the protons crossing that given surface. I am using the USRBDX card to score the energy distribution and the USRYield card to score the LET histogram. The input file and the output files from USRBdx (*23_sum.lis) and USRYield (*58_sum.lis) are attached to this mail.

The output of the USRBdx card is pretty much straight forward. It scores all the protons crossing the boundary specified and gives a cumulative fluence of 1 proton/primary. However, in order to make sure what I am getting from the USRYield card is the correct value of the fluence, I am comparing the output of the USRYield to the USRBdx cards by scoring the fluence with respect to energy in both cases, just for testing.

I found that the cumulative fluence given by the USRYield card is different when using either the ‘Weighted angle lab’ or ‘Polar angle lab’ as the 2nd variable while scoring the energy as the 1st variable. When using the ‘Polar angle lab’, the USRYield card is consistent with the fluence given by USRBdx but when using the ‘weighted angle lab’, the fluence given by the USRYield seems to include a factor which is proportional to the energy of the proton.

My questions are:

        1. Firstly, what does that factor represent? How is the calculated fluence related to the weighted angle in USRYield?

        2. Then, when scoring the fluence in both cards, are both cards scoring ALL the protons crossing the defined surface or does USRYield score only and exclusively the inelastic collisions in a volume defined by the selected region? That is, what is the difference between the cumulative score in USRBdx and USRYield for this example?

        3. When imposing ‘polar angle lab’ as the second variable of the USRYield card, does FLUKA convert the polar angle to solid angle automatically and differentiates the cumulative yield by the calculated solid angle afterwards, or is it still differentiated with respect to the polar angle?

Furthermore, another problem I have is that I want to lower the threshold for the scoring of protons down to ‘1e-6 GeV’. I have tried to do that using the PART-THR card but the threshold still remains at 1e-4 GeV for protons as imposed by the ‘Precisio’ DEFAULTS card in the input.

        4. How is it possible to override the default card and impose a lower scoring threshold for protons?

Thanks you in advance for any information on these questions.

Best regards,
Alvin Sashala Naik

Received on Thu Jun 26 2014 - 12:47:40 CEST

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