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From: <francesca.belloni_at_libero.it>

Date: Thu, 6 Aug 2015 10:35:05 +0200 (CEST)

Dear Francesco,

thanks a lot for your reply!

Cheers,

Francesca

*>----Messaggio originale----
*

*>Da: Francesco.Cerutti_at_cern.ch
*

*>Data: 05/08/2015 23.39
*

*>A: "francesca.belloni_at_libero.it"<francesca.belloni_at_libero.it>
*

*>Cc: "FLUKA discussion"<fluka-discuss_at_fluka.org>
*

*>Ogg: Re: R: Re: [fluka-discuss]: Neutrons on carbon still
*

*>
*

*>
*

*>> About the last point you mentioned, does it mean that since the charged
*

*>> particles
*

*>> by low energy neutrons are not generated I can not score the energy they
*

*>> deposit in the diamond,please?
*

*>
*

*>You can score energy deposition in the detector, but this is just the
*

*>kerma associated to a neutron of a given group energy interacting in
*

*>natural carbon (taking into account on average the contribution of
*

*>charged products). If the detector size is such that the transport of
*

*>charged products is in fact negligible, then you will get a meaningful
*

*>average value. But anyway an event-by-event study (pulse height spectrum)
*

*>is not possible, so I'm afraid that your goal is out of question.
*

*>
*

*>Ciao
*

*>
*

*>Francesco
*

*>
*

*>**************************************************
*

*>Francesco Cerutti
*

*>CERN-EN/STI
*

*>CH-1211 Geneva 23
*

*>Switzerland
*

*>tel. ++41 22 7678962
*

*>fax ++41 22 7668854
*

*>
*

*>On Wed, 5 Aug 2015, francesca.belloni_at_libero.it wrote:
*

*>
*

*>> Hi,
*

*>>
*

*>> thanks a lot!!!
*

*>>
*

*>> I was so sure I was shooting 18 MeV neutrons that I did not checked that at
*

*>> all...
*

*>> Thanks also for all the explanations.
*

*>> The final goal of the simulations would be to reconstruct the response of
*

the

*>> detector to
*

*>> an incident neutron beam.
*

*>> About the last point you mentioned, does it mean that since the charged
*

*>> particles
*

*>> by low energy neutrons are not generated I can not score the energy they
*

*>> deposit in the diamond,please?
*

*>>
*

*>>
*

*>> Thanks really a lot!
*

*>>
*

*>> Regards,
*

*>> Francesca
*

*>>
*

*>>
*

*>>
*

*>>
*

*>>> ----Messaggio originale----
*

*>>> Da: Francesco.Cerutti_at_cern.ch
*

*>>> Data: 05/08/2015 18.58
*

*>>> A: "francesca.belloni_at_libero.it"<francesca.belloni_at_libero.it>
*

*>>> Cc: "FLUKA discussion"<fluka-discuss_at_fluka.org>
*

*>>> Ogg: Re: [fluka-discuss]: Neutrons on carbon still
*

*>>>
*

*>>>
*

*>>> Hi Francesca,
*

*>>>
*

*>>> you believe to shoot a 18 MeV (kinetic energy) neutron, whereas you are
*

*>>> shooting a 18 MeV/c (momentum) neutron, which - as written in the
*

*>>> quite useful Beam properties section of the output - has a kinetic energy
*

*>>> of 170 keV. So we are in a region (group #144) where one just expects
*

*>>> capture (apart from elastic), indeed yielding 13C (on 12C) and 14C (on the
*

*>>> small fraction of 13C).
*

*>>>
*

*>>> Note also the following:
*

*>>>
*

*>>> - your interpretation of the residual nuclei probabilities is wrong, see
*

*>>> http://www.fluka.org/web_archive/earchive/new-fluka-discuss/6203.html
*

*>>>
*

*>>> - you are in the world apart of low energy neutrons (also at 18 MeV
*

*>>> kinetic energy), based on library data and not on models. This means that
*

*>>> EVAPORAT and COALESCE are totally pointless. And also LAM-BIAS does not
*

*>>> apply (pointless too), as you can realize looking at the (missing) effect
*

*>>> on number (vs weight) of performed low-energy neutron interactions and CPU
*

*>>> time.
*

*>>>
*

*>>> - additionally, as a continuation of the above point, remember that -
*

*>>> apart from very few exceptions - charged particles (including residual
*

*>>> nuclei) by low energy neutrons are not generated explicitly and so cannot
*

*>>> be transported (IONTRANS pointless). You can ask FLUKA to evaluate the
*

*>>> production rates of low energy neutron reaction residues, but these do not
*

*>>> exist as particles in the simulation. The adopted group-wise treatment
*

*>>> prevents from simulating exclusive reaction channels.
*

*>>>
*

*>>> Ciao
*

*>>>
*

*>>> Francesco
*

*>>>
*

*>>> **************************************************
*

*>>> Francesco Cerutti
*

*>>> CERN-EN/STI
*

*>>> CH-1211 Geneva 23
*

*>>> Switzerland
*

*>>> tel. ++41 22 7678962
*

*>>> fax ++41 22 7668854
*

*>>>
*

*>>> On Wed, 5 Aug 2015, francesca.belloni_at_libero.it wrote:
*

*>>>
*

*>>>> Dear all,
*

*>>>>
*

*>>>> Â Â Â Â Â Â I am still trying to get alphas out of n+diamond_material
*

*>> interaction, but with no
*

*>>>> success.
*

*>>>> So I switched to another code and for a 5 m thick diamond, I get alphas
*

*>> (and other heavy
*

*>>>> ions).
*

*>>>> Then I went back to FLUKA and reduced the input at the minimum: only a
*

*>> diamond 500 cm
*

*>>>> thick and neutrons striking it.
*

*>>>> I asked RESNUCLEI in the diamond region, but I only get C13 and C14, as
*

*>> product of n+natC.
*

*>>>> Could anyone give a look, please?
*

*>>>>
*

*>>>> If I look at the output file everything seems to have been activated
*

*>>>> In my *.inp LOW-NEUT, WHAT(4)=4 asks for a printout ofÂ the information
*

*>> about the residual
*

*>>>> nuclei. This is dumped on the *.out file.
*

*>>>>
*

*>>>> If I look at my *.out file I see that the neutrons I am shooting belong
*

to

*>> the Neutron
*

*>>>> (low energy)
*

*>>>> Xsec group number 5:
*

*>>>>
*

*>>>>
*

*>>>> Neutron group n.:Â Â Â 5Â upper limit 1.8221E-02 GeV,Â average energy 1.7995
*

E-

*>> 02 GeV,
*

*>>>> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â velocity 5.7846E+09 cm/s,Â momentum
*

1.8477

*>> E-01 GeV/c
*

*>>>>
*

*>>>> Â
*

*>>>> Later on, on the same *.out file, there is written that the FLUKA medium
*

*>> number 26
*

*>>>> corresponds to the Xsec medium number 1.
*

*>>>>
*

*>>>>
*

*>>>> Â Â Fluka mediumÂ Â Â Â NameÂ Â Â Â Xsec mediumÂ atomic densityÂ Â Â Â Â Â Â Â Â Id.
*

*>> 1Â Â Â Â Â Â Â Id.
*

*>>>> 2Â Â Â Â Â Â Â Id. 3
*

*>>>> Â Â Â Â numberÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â numberÂ Â Â Â ( at/(cm barn) )
*

*>>>>
*

*>>>> Â Â Â Â Â Â Â Â 1Â Â Â Â Â Â Â BLCKHOLEÂ Â Â Â Â Â Â Â 0Â Â Â Â Â Â Â Â 0.0000
*

*>> E+00Â Â Â Â Â Â Â Â Â Â Â Â Â Â 0Â Â Â Â Â Â Â Â Â Â Â
*

*>>>> 0Â Â Â Â Â Â Â Â Â Â Â 0
*

*>>>>
*

*>>>> Â Â Â Â Â Â Â Â 2Â Â Â Â Â Â Â VACUUMÂ Â Â Â Â Â Â 1000Â Â Â Â Â Â Â Â 0.0000
*

*>> E+00Â Â Â Â Â Â Â Â Â Â Â Â Â Â 0Â Â Â Â Â Â Â Â Â Â Â
*

*>>>> 0Â Â Â Â Â Â Â Â Â Â Â 0
*

*>>>>
*

*>>>> Â Â Â Â Â Â Â 26Â Â Â Â Â Â Â DIAMONDÂ Â Â Â Â Â Â Â Â 1Â Â Â Â Â Â Â Â 1.7649E-
*

*>> 01Â Â Â Â Â Â Â Â Â Â Â Â Â Â 6Â Â Â Â Â Â Â Â Â Â
*

*>>>> -2Â Â Â Â Â Â Â Â Â 296
*

*>>>>
*

*>>>>
*

*>>>> Going down again in the *.out file there is written:
*

*>>>>
*

*>>>> Â Residual nuclei informations for mediumÂ Â Â 1
*

*>>>>
*

*>>>> Â Group:Â Â Â 1Â Â AÂ Â Â Â ZÂ Â Â Prob
*

*>>>>
*

*>>>> Â Â Â Â Â Â Â Â Â Â Â Â Â 12Â Â Â Â 6Â Â Â 7.54E-01
*

*>>>> Â Â Â Â Â Â Â Â Â Â Â Â Â 11Â Â Â Â 5Â Â Â 9.09E-01
*

*>>>> Â Â Â Â Â Â Â Â Â Â Â Â Â 13Â Â Â Â 6Â Â Â 9.09E-01
*

*>>>> Â Â Â Â Â Â Â Â Â Â Â Â Â 12Â Â Â Â 5Â Â Â 9.36E-01
*

*>>>> Â Â Â Â Â Â Â Â Â Â Â Â Â Â 9Â Â Â Â 4Â Â Â 1.00E+00
*

*>>>> Â Â Â Â Â Â Â Â Â Â Â Â Â 14Â Â Â Â 6Â Â Â 1.00E+00
*

*>>>> Â Â Â Â Â Â Â Â Â Â Â Â Â Â 1Â Â Â Â 1Â Â Â 7.44E-02
*

*>>>> Â Â Â Â Â Â Â Â Â Â Â Â Â Â 2Â Â Â Â 1Â Â Â 1.07E-01
*

*>>>> Â Â Â Â Â Â Â Â Â Â Â Â Â Â 4Â Â Â Â 2Â Â Â 6.44E-02
*

*>>>> [..]
*

*>>>>
*

*>>>> Â Group:Â Â Â 5Â Â AÂ Â Â Â ZÂ Â Â Prob
*

*>>>> Â Â Â Â Â Â Â Â Â Â Â Â Â 12Â Â Â Â 6Â Â Â 7.87E-01
*

*>>>> Â Â Â Â Â Â Â Â Â Â Â Â Â 11Â Â Â Â 5Â Â Â 9.11E-01
*

*>>>> Â Â Â Â Â Â Â Â Â Â Â Â Â 13Â Â Â Â 6Â Â Â 9.12E-01
*

*>>>> Â Â Â Â Â Â Â Â Â Â Â Â Â 12Â Â Â Â 5Â Â Â 9.48E-01
*

*>>>> Â Â Â Â Â Â Â Â Â Â Â Â Â Â 9Â Â Â Â 4Â Â Â 1.00E+00
*

*>>>> Â Â Â Â Â Â Â Â Â Â Â Â Â 14Â Â Â Â 6Â Â Â 1.00E+00
*

*>>>> Â Â Â Â Â Â Â Â Â Â Â Â Â Â 1Â Â Â Â 1Â Â Â 4.18E-02
*

*>>>> Â Â Â Â Â Â Â Â Â Â Â Â Â Â 2Â Â Â Â 1Â Â Â 1.18E-01
*

*>>>> Â Â Â Â Â Â Â Â Â Â Â Â Â Â 4Â Â Â Â 2Â Â Â 5.25E-02
*

*>>>>
*

*>>>>
*

*>>>> Therefore it means that in FLUKA the neutrons I am shooting have a
*

certain

*>> probability
*

*>>>> (different from 0.0)Â to interact with the diamond and give alphas,Â Be-
*

*>> 9,Â B-11 and B-12.
*

*>>>>
*

*>>>> I thought it could have been a problem of statistics (I shoot 9E+7
*

neutrons

*>> on a material
*

*>>>> where lam-bias=-0.001) . But looking at those probabilities, it seems
*

it's

*>> more likely to
*

*>>>> get B-12 than C-13Â (IF i am understanding the table correctly...which is
*

*>> not sure).
*

*>>>>
*

*>>>> But I get C-13 and C-14 only.
*

*>>>>
*

*>>>>
*

*>>>> What am I missing,please?
*

*>>>>
*

*>>>> Thanks,
*

*>>>>
*

*>>>> regards,
*

*>>>>
*

*>>>> Francesca
*

*>>>>
*

*>>>>
*

*>>>>
*

*>>
*

*>>
*

*>>
*

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Received on Thu Aug 06 2015 - 12:02:00 CEST

Date: Thu, 6 Aug 2015 10:35:05 +0200 (CEST)

Dear Francesco,

thanks a lot for your reply!

Cheers,

Francesca

the

to

E-

1.8477

certain

neutrons

it's

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Received on Thu Aug 06 2015 - 12:02:00 CEST

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