Re: [fluka-discuss]: Re: Problem with transporting neutrons

From: Mina Nozar <nozarm_at_triumf.ca>
Date: Thu, 26 Feb 2015 18:23:11 -0800

Hello Nikanysio,

I didn't have time to run your input file for large number of primaries
(which is what you need, given the dimensions of your setup). I made
some changes and am able to see distributions.

Good luck,
Mina

On 15-02-24 11:04 PM, NKANYISO ROBERT Mantengu wrote:
> Hi Mina
>
> Last time my reaction was Li(p,n)Be but now its proton on Be.
> You should be looking at Fig. (b)
> Cal. Be mean calculated Be fluence spectrum.
> Yes, the calculated result from FLUKA simulation.
>
> I had a misunderstanding, thats why I made a mistake of changing the
> number of bins in omega from 1 to 10.
> Yeah the Be measured spectra was done for 66 MeV then I was forced to
> reduce the energy, and the detectors were placed 7.7m away from the
> target at 0 and 16 degrees.
> When I try to plot to see the distribution I get an error
>
> Regards
> N.R Mantengu
>
>
> On Wed, Feb 25, 2015 at 12:49 AM, Mina Nozar <nozarm_at_triumf.ca
> <mailto:nozarm_at_triumf.ca>> wrote:
>
> Hello Nkanyiso,
>
> I am sending this to the forum as well since others might be able
> to offer more help.
>
> I have few questions and suggestions:
>
> What exactly is your reaction? Is it protons on Be or protons on
> Li? The reaction you included in your first message was Li(p,n)Be
> which means protons on Li. Do you have protons on Be?
>
> Which figure in your plot should I be looking at? Fig. (b)? What
> does Cal. Be mean? Is this results from your FLUKA imulated
> simulations?
>
>
> Why did you change number of bins in omega to 10 from 1? It seems
> to me your are interested in single differential fluence (i.e.
> fluence as a function of energy) so why the 10 bins in omega?
>
> In the new example, you have reduced the beam energy from 200 MeV
> to 66 MeV, and the target from a 1x1x1 cm cube to a sphere with a
> radius of 2.5 cm. Your 0 deg detector is now around 770 cm away
> from the target when in the first example, it was around 10 cm away.
>
> Your beam is annular and less than 1 cm in diameter. Your second
> detector is off axis by 212 cm in X. In the previous example,
> your off-axis detector was off axis by ony 3 cm. When you look
> at beam part and/or proton distribution, what do you see?
>
> Note that in your USRBIN cards, you don't need to go from -900 to
> 900 cm in Z. And X and Y don't have any meaning when What(1) is
> set to R-Phi_Z.
>
>
> Best wishes,
> Mina
>
>
>
> On 15-02-24 07:46 AM, NKANYISO ROBERT Mantengu wrote:
>> Hi mina I hope you are doing good.
>>
>> I'm sorry for asking you in person, but but i have a problem now
>> when I locate the detector at 7.7m.
>> I only get the peak at low-energies, I don't know if the problem
>> is with thickness but i have the measured spectra for 10mm Be,
>> with 66MeV proton beam
>>
>> Here I have attached the input file together with the picture of
>> the measured spectra for Be
>>
>> Regards
>> N.R Mantengu
>>
>> On Fri, Feb 20, 2015 at 6:30 PM, NKANYISO ROBERT Mantengu
>> <3477531_at_myuwc.ac.za <mailto:3477531_at_myuwc.ac.za>> wrote:
>>
>> Thank you very much Mina
>>
>> Regards
>> Nkanyiso
>>
>> On Fri, Feb 20, 2015 at 6:21 PM, <nozarm_at_triumf.ca
>> <mailto:nozarm_at_triumf.ca>> wrote:
>>
>> Hello Nkanyiso,
>>
>> I made some changes to your input file and ran it.
>> Changes:
>>
>> 0) Your reactions is Li(p,n)Be. So Protons on Li. You
>> had Be for the
>> material of your target. I changed it to Li.
>>
>> 1) Annular beam (R_in = 0.7 cm, R_out = 1.2 cm) to (R_in
>> = 0, R_out = 0.5)
>> I did this to get more statistics since your target is a
>> 1x1x1 cm cube.
>> Is this really the setup you did your measurement? i.e.
>> annular beam with
>> R_in = 0.7 cm, R_out = 1.2 cm on a 1x1x1 cm cube?
>>
>> 2) Changed number of bins for omega in the USRBDX cards
>> from 10 to 1.
>>
>> 3) Added two USRBIN estimators to looks at Beam particle
>> and Neutron
>> spacial distributions. (My recommendation is "ALWAYS
>> look at where your
>> beam distribution to make sure you have set up your beam
>> correctly").
>>
>> 4) Added two USRTRACK estimators to look at the Neutron
>> fluence
>> distributions in the two detectors.
>>
>> 5) Took out the unnecessary EMF card.
>>
>> 6) Added a flair project to look at a few plots of the
>> produced
>> distributions.
>>
>>
>> I ran the project for 150M primaries to get reasonable
>> statistics. I am
>> looking at the distributions from home so can't quite
>> compare with the
>> measurements. Take a look and see for yourself and
>> report back.
>>
>> Best wishes,
>> Mina
>>
>>
>> > Sorry I have captured the wrong picture for measured
>> spectrum
>> >
>> > Here in the right one
>> >
>> > Regards
>> > N.R Mantengu
>> >
>> > On Wed, Feb 18, 2015 at 6:05 PM, NKANYISO ROBERT Mantengu <
>> > 3477531_at_myuwc.ac.za <mailto:3477531_at_myuwc.ac.za>> wrote:
>> >
>> >> Dear Fluka experts,
>> >> Can someone help me out here I'm transporting neutron
>> fluence using
>> >> USRBDX
>> >> card, but the spectra that I get doesn't seam to be
>> consistent with the
>> >> measured one.
>> >>
>> >> Here is the input file and the spectra
>> >> any comment or advice will be appreciated.
>> >>
>> >> #Sorry for the units in the calculated spectra, but
>> its Energy in GeV on
>> >> X
>> >> axis and its fluence in part/GeV/cm^2 on Y axis
>> >>
>> >> Regards
>> >> N.R Mantengu
>> >>
>> >
>>
>>
>>
>
>





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Received on Fri Feb 27 2015 - 04:42:49 CET

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