Re: [fluka-discuss]: Cross section of neutrons

From: Srinidhi Bheesette <srinidhi.bheesette_at_cern.ch>
Date: Fri, 3 Mar 2017 13:10:36 +1300

Hi Luigi,

Thanks for your additional feedback on the issue.

   1. Will have a read through it.
   2. USRTRACK: The value is expressed in GeV per cm2 per energy unit per
   primary right? This means I have to multiply it with this value with the
   width of my detector (1.4cm *1.4cm) to get the unnormalized-to-area value,
   is this right?

Thanks.

Cheers,
Shri

(Srinidhi Bheesette)

On 1 March 2017 at 22:38, Luigi Salvatore Esposito <
luigi.salvatore.esposito_at_cern.ch> wrote:

> Dear Srinidhi,
> to complement the answer by Andrew:
> 1. to understand how the statistical uncertainty is evaluated in FLUKA,
> refer to these slides
> <https://indico.cern.ch/event/540415/contributions/2194806/attachments/1285749/1912258/09_Statistics_and_sampling_2015.pdf> from
> last FLUKA course (in particular page 32 and following)
> 2. the volume in the USRTRACK seems to be not
> correct: 1.4cm*1.4cm*0.0055cm = 0.01078 cm3
> Best regards, luigi
>
> On 1 Mar 2017, at 05:38, Srinidhi Bheesette <srinidhi.bheesette_at_cern.ch>
> wrote:
>
> Hi Andrew,
>
> Thanks for the feedback:
>
> 1. I am sorry I forgot to mention it my mail. I am using a python script
> to run these simulation for 500000 times. (I could have specified this in
> the START card). But I did not understand why I need to run these with 5
> independent random number seeds?
>
> 2. Is this URSTRACK card right?
> <image.png>
>
>
> I wish to score the energy deposited by protons on the SENSOR region with
> a dim (1.4cm*1.4cm*0.0055cm)
>
> 3. Sure, will post the plot with error bars shortly.
>
> Thanks and hoping to her from you soon.
>
> Cheers,
> Shri
>
> (Srinidhi Bheesette)
>
> On 1 March 2017 at 15:26, Andrew Davis <andrew.davis_at_wisc.edu> wrote:
> Hi Srinidhi
>
> There are a number of issues assuming that your input deck is
> representative
>
> 1) Your START card only contains a single history to run, from a single
> run of 1 primary you cannot make any assertions regarding the results of
> your calculation since you have a large statistical uncertainty. You should
> likely run several million histories with (at least) 5 independent random
> number seeds using the already established tools to perform the averaging.
> 2) You used a USRBIN score (with 1 bin for x-y-z) to determine the energy
> deposition, you might as well use a USRTRACK score, not an issue really,
> but I may’ve chosen a USRTRACK instead
> 3) Your plot doesn’t include any statistical error, its hard judge the
> accuracy of a Monte Carlo calculation without any mention of the
> statistical error.
>
> Thanks
>
> Andy
>
> On Feb 28, 2017, at 4:57 PM, Srinidhi Bheesette <
> srinidhi.bheesette_at_cern.ch> wrote:
>
> Hi all,
>
> I have simulated a pixel detector (just a silicon sensor layer) in FLUKA
> and bombarding it with point neutron source at different energies from
> 1-25.5MHz with a step size of 0.5MHz. I run a single simulation.
>
> I then score the energy deposited in the detector (one value for one run)
> and then plot a graph of the energy deposited on the x-axis the source
> energy on the y-axis shown below:
>
> <image.png>
>
> The energy seems to increase till 20MeV but then start fluctuating from
> 20.5 to 25.5MeV and also a spike at 17MeV
>
> Am I missing some cards in my input file (attached) for activating some
> feature for neutron energies after 20MeV?
>
> Please help.
>
> Cheers,
> Shri
>
> (Srinidhi Bheesette)
> <sensor-22.5MeV.inp>
>
>
>
>
>


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Received on Fri Mar 03 2017 - 02:42:16 CET

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