Re: muon-induced neutron yield calculation

From: Yung-Shun Yeh <>
Date: Mon, 12 Aug 2013 23:30:23 +0800

Dear Vasilis and FLUKA experts,

Thanks for the guidance.

I modify the mgdraw.f by following your instruction.

       if (ktrack .eq. 0) then
          tktrck = ETRACK-AM(JTRACK)
       else if (jtrack .eq. 8 .and. ktrack .gt. 0) then
* Randomly distribute the neutron energy in the group <20MeV
          ALOGEA = LOG (GMSTOR(IDXSEC+KTRACK+1)) ! Lower bin boundary
          ALOGEB = LOG (GMSTOR(IDXSEC+KTRACK)) ! Higher bin boundary

However, I failed at the compiling stage.

tmp/ccyQQgZ5.o: In function `__g77_masterfun_mgdraw':
/home/adair/FlkPhDWork/mgdraw.f:325: undefined reference to `gmstor_'
/home/adair/FlkPhDWork/mgdraw.f:326: undefined reference to `gmstor_'

Could you tell me which include I should add? Thanks.

mgdraw.f does not recognize variable "idxsec", too. After I add the include
file "(LOWNEU)", it passed the compilation. Is it the correct file to be
included? Thanks.

Attached are the relevant user-defined codes. The third thanks :)

Yung-Shun Yeh

On Thu, Aug 8, 2013 at 11:19 PM, Vasilis Vlachoudis <> wrote:

> Hi Yung-Shun Yeh
> If JTRACK=8 (neutron)
> you can check with the KTRACK the neutron group it is.
> 0 means no-group, therefore Energy > 20MeV
> Once a neutron has a group assigned to it (KTRACK>0) then it doesn't
> have anymore a discrete energy.
> So one option is to randomly sample an energy in the interval from lower
> to higher energy. The best would be to do it isolethargically
> with the following code:
> * Randomly distribute the neutron energy in the group <20MeV
> ALOGEA = LOG (GMSTOR(IDXSEC+KTRACK+1)) ! Lower bin boundary
> ALOGEB = LOG (GMSTOR(IDXSEC+KTRACK)) ! Higher bin boundary
> Cheers
> Vasilis
> ------------------------------
> *From:* []
> on behalf of Yung-Shun Yeh []
> *Sent:* 07 August 2013 04:56
> *To:* fluka-discuss
> *Subject:* Re: muon-induced neutron yield calculation
> Dear FLUKA experts,
> Sorry I forgot to attache the figure and input card. Thanks in advance.
> Best regards,
> Yung-Shun Yeh
> On Tue, Aug 6, 2013 at 12:23 PM, Yung-Shun Yeh <>wrote:
>> Dear FLUKA experts,
>> I am studying the cosmic-ray muon induced neutron in underground
>> laboratory, and would like to ask you how to retrieve neutron information
>> using mgdraw.f user-defined function.
>> To calculate the detection efficiencies of muon-induced neutron, I try
>> to generate a set of neutron samples according the mean muon energy in our
>> laboratory. I would like to reproduce the results in PhysRevD.64.013012.
>> The simulation setup is that mono-energy energetic muon beam injects into
>> the liquid scintillator. The liquid scintillator is C10H22 filled in a
>> cylinder with height 4500cm and radius 500cm. I use mgdraw.f to
>> retrieve the properties of neutron produced during the muon propagating. For
>> neutron-indcued neutron case, highest energy neutron is treated as parent
>> particle, and avoided double count.
>> I plot the neutron energy spectra. For high energy neutron(>20MeV), the
>> neutron spectrum looks well comparing with the paper, but for low energy
>> part below 10MeV, there are two spikes around 9MeV and 0.4MeV, which I
>> think abnormal ones. The PRD paper did not show the low energy behavior, so
>> I am unable to do a comparison. Please see the figure. The x axis is in GeV.
>> I read the manual, and learnt for low energy neutron with energy<20MeV,
>> FLUKA deals with neutrons as group algorithm, but mgdraw.f deals with
>> neutrons particle by particle. I also noticed in the previous discussion,
>> it is not suggested to use mgdraw.f to get information of low energy
>> neutrons.
>> My question is: how do I modify mgdraw.f to get correct information of
>> low energy neutron? Or is there a alternative way?
>> Regards,
>> Yung-Shun Yeh

Received on Tue Aug 13 2013 - 14:04:09 CEST

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