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From: <pkrai_at_barc.gov.in>

Date: Fri, 21 Jun 2013 10:42:42 +0530

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 Mon Jun 24 2013 - 09:52:05 CEST

Date: Fri, 21 Jun 2013 10:42:42 +0530

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.

- image/pjpeg attachment: case-1.jpg

- image/pjpeg attachment: case-2.jpg

- image/pjpeg attachment: case-3.jpg

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