RE: muon-induced neutron yield calculation

From: Vasilis Vlachoudis <>
Date: Thu, 8 Aug 2013 15:19:35 +0000

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

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?

Yung-Shun Yeh
Received on Thu Aug 08 2013 - 20:07:53 CEST

This archive was generated by hypermail 2.3.0 : Thu Aug 08 2013 - 20:08:25 CEST