Dear Pravin,
it seems that the sequence of attached images corresponds pretty well to
the sequence of cases studied. From no biasing to strong biasing, the
neutron spectrum is converging faster (as already mentioned by Alberto!).
Its only a matter of time (more number of primaries) for the cases 1 and 2
to reach the neutron spectrum as expected by the case 3.
Regards,
-Nikhil
On Fri, Jun 21, 2013 at 7:12 AM, <pkrai_at_barc.gov.in> wrote:
>
>
> I have a doubt regarding USRBDX result,
>
> I have run three cases for Photonuclear reaction,
> 1) With No LAM Bias card
> 2) With hadronic inelastic interaction length in LAM Bias card =0.03
> 3) With hadronic inelastic interaction length in LAM Bias card =0.0003
>
> I am attaching usrbdx result of one way scoring of current for three cases.
> for case 1) integrated neutron/pr=1.9914856e-5
> for case 2) integrated neutron/pr=1.9187546e-5
> for case 3) integrated neutron/pr=1.9493287e-5
> Approximately similar.
>
> But neutron distribution are totally different for these three cases.
>
> why is the difference? I am sending you three distribution files.
>
>
>
>
>
>
> > The distribution will always be the same. Biasing, if it is done
> > correctly, doesn't change the result but converges faster to it.
> > Your problem is, if you overdo it, you will flood the stack with too
> > many particles and in the end you will not gain in efficiency as you
> > should.
> >
> > But try it, and see what happens!
> >
> > Alberto
> >
> >
> > On Wed, 5 Jun 2013, pkrai_at_barc.gov.in wrote:
> >
> >> But in my case photonuclear target is Beryllium.
> >> In this case there is a reaction 9Be(r,n)8Be.The threshold energy for
> >> this
> >> photonuclear reaction is 1.666 MeV.And cross-section for this reaction
> >> is
> >> ~2 milibarn in the energy range below 10MeV.
> >>
> >> so If I keep the reduction factor of the hadronic inelastic interaction
> >> length around 0.0003 or 0.03 or 0.0, will the result will be same or
> >> different?(that means I will get same neutron ditribution or not?)
> >>
> >> Pravin Rai
> >>
> >>
> >>> If the energy of primary electron and photon is about 10 MeV,
> >>> there will be practically no photonuclear interaction! Or very little.
> >>> The threshold is generally close to 8 MeV and even above threshold the
> >>> cross
> >>> sections are very small. Secondary photons have certainly not enough
> >>> energy
> >>> to interact.
> >>> Therefore, I don't think that 0.0003 will over predict.
> >>>
> >>> Alberto
> >>>
> >>> On Wed, 5 Jun 2013, pkrai_at_barc.gov.in wrote:
> >>>
> >>>>
> >>>>
> >>>> I have a question regarding LAM-BIAS,
> >>>>
> >>>>
> >>>> It is written in the manual that,Biasing of the hadronic inelastic
> >>>> interaction length can be applied also to photons (provided option
> >>>> PHOTONUC is also requested) and For photons, a typical reduction
> >>>> factor
> >>>> of
> >>>> the hadronic inelastic interaction length is the order of 0.01-0.05
> >>>> for
> >>>> a
> >>>> shower initiated by 1 GeV photons or electrons, and of 0.1-0.5
> >>>> for one at 10 TeV.
> >>>>
> >>>> But what about if the energy of primary electron and photon is about
> >>>> 10
> >>>> MeV? By what amount I have to keep the reduction factor of the
> >>>> hadronic
> >>>> inelastic interaction length?
> >>>>
> >>>> In my case I have kept it around 0.0003, is it ok? or it will over
> >>>> predict?
> >>>>
> >>>>
> >>>> From,
> >>>> PRAVIN RAI
> >>>
> >>>
> >>
> >>
> >>
> >
> > --
> > Alberto Fass
> >
>
Received on Tue Jun 25 2013 - 22:59:42 CEST