RE: [fluka-discuss]: USRBDX and USRYIELD

From: <hayley.smith_at_stfc.ac.uk>
Date: Fri, 22 Aug 2014 12:57:41 +0000

Thank you very much for your help Stefan, it has been much appreciated - I am now able to run the deck without it crashing.

As a follow up, you say it is important to input values for all WHATs. In this case, are you able to advise what value I should put for WHAT (6) of the first USRYIELD card? It says in the manual 'normalisation factor'. Would this be the same as WHAT (4) in the continuation card?

Also, I am confused by the output I get from the USRYIELD and USRBDX cards.
  
I would have thought that to score the angular distribution using USRYIELD that the maximum angle would be Pi/2. However when I do this I get strange results. The result seems more sensible for a maximum angle of 2Pi, but still I would have expected the peak of the angular distribution to be around 0, rather than around 2Pi? Am I misinterpreting my results?

With the USRBDX scoring solid angle I understand why the maximum angle for this would be 2Pi. However, the results I obtain for angular distribution for a single energy bin are just as confusing to me...

I have read extensively through the manual and previous posts but have not been able to find any information.
I understand that a difference between USRBDX and USRYIELD is that USRBDX calculates the angle with respect to the normal, and USRYIELD calculates the angle with respect to the beam direction (in my case). Maybe this is a source of my confusion?

Are you able to explain:
Why the result of USRYIELD with a maximum angle of 2Pi is centred around 2Pi?
Why using a maximum angle of Pi/2 in USRYIELD in this case is seemingly incorrect?
Why I am struggling to get a meaningful result from USRBDX (or why/how I am misinterpreting the results)?

My input file and three screenshots showing the resulting graphs I describe are attached.
Any help is very much appreciated,
Hayley





-----Original Message-----
From: Stefan Roesler [mailto:sroesler_at_mail.cern.ch]
Sent: 20 August 2014 09:42
To: Smith, Hayley (STFC,RAL,ISIS)
Cc: fluka-discuss_at_fluka.org
Subject: Re: [fluka-discuss]: USRBDX and USRYIELD

Dear Hayley

I recommend to enter input values for all What's in scoring cards. Some have default values, some don't.

For example in your case WHAT(4) of the USRYIELD continuation card (upper limit of the second quantity) has no default (!) which causes the code to crash (normalization with an undefined value..)

Furthermore, when the upper energy limit in USRBDX and USRYIELD is not defined, the code uses the beam energy. However, when scoring BEAMPART the energy of the particle to be scored is exactly at the bin limit, and depending on the internal rounding the particle might be scored or not.
Thus, I suggest you define an upper energy limit that is slightly above the beam energy.

Cheers
Stefan


On Mon, 18 Aug 2014, hayley.smith_at_stfc.ac.uk wrote:

>
> Dear All
>
>  
>
> I am trying to look at the scattering of a 800 MeV proton beam through
> a carbon target.  (At present the beam distribution and target
> geometry are very much simplified).
>
> I have tried to score the angular distribution of the proton beam in
> two ways, using USRBDX and using USRYIELD.
>
>  
>
> I thought USRYIELD would be the most appropriate since I read various
> threads on the forum, and this one in particular seemed to be doing a
> very similar thing to me,
> http://www.fluka.org/web_archive/earchive/new-fluka-discuss/0568.html
>
>  
>
> However, when I try to create a USRYIELD card with a single energy bin
> the progress status for the run always ends after the first cycle with
> ?Finished with ERRORS? and  nothing stands out to me from the .log,
> .out or .err files.
>
>  
>
> When I don?t use a USRYIELD card the USRBDX card outputs results,
> however I am unsure how to interpret them in terms of beam scattering or divergence.
>
> The relevant files are attached for your information.
>
>  
>
> Is anyone able to advise me on how best to score the beam divergence
> through the target?
>
> Is my approach correct?  What is causing the run to finish with errors
> (that I can?t seem to find in the output files)?
>
>  
>
> Thanks, any assistance is much appreciated,
>
> Hayley
>
>  
>
>  
>
> Hayley Smith
>
>  
>
> Accelerator Physicist
>
> ISIS Facility
>
> Rutherford Appleton Laboratory
>
> Harwell Oxford
>
> OX11 0QX
>
>  
>
> 01235 445524
>
> hayley.smith_at_stfc.ac.uk
>
>  
>
>  
>
>  
>
>  
>
>
> --
> Scanned by iCritical.
>
>
>
>

-- Scanned by iCritical.



Received on Fri Aug 22 2014 - 16:35:07 CEST