From: Vasilis Vlachoudis (Vasilis.Vlachoudis@cern.ch)
Date: Mon Mar 05 2007 - 10:50:10 CET
Hi Sunil,
the mdstck is used to manage the stack of particles produced after an
interaction. In elastic collisions there are no secondaries produced
unless you have a recoil on the target nucleus e.g. if it is a hydrogen
atom.
Cheers
Vasilis
-----Original Message-----
From: Sunil C [mailto:sunilc@barc.gov.in]
Sent: Monday, 05 March 2007 09:37
To: Vasilis Vlachoudis
Subject: Re: Scoring number of elastic collissions
Hi
I am sorry to bother you again. I posted the query to the list but none
replied. So I still would like to know if have a way to score the
elastic collisions from the low energy neutron group.
Going back to the manual CERN-2005 -10 page number 310 the MDSTACK can
be used to analyze or write the secondaries to a file. Do you think this
would work? or is there any other variable that can be tapped. I am
trying to compare the number with a MCNP calculation.
Best Regards
Sunil
Vasilis Vlachoudis wrote:
> Dear Sunil,
>
> you have to be careful with the low energy neutrons (En<19.6 MeV), the
> routine that I've send doesn't apply to them. It only works down to
19.6
> MeV, and not below when the neutrons are treated with the group
> approach. Is true that you can activate point-wise treatment for some
> elements [LOW-NEUT, what(6) card] like Hydrogen, but then the event
flag
> for scoring the elastic scattering is no longer the LELEVT, but rather
> the LLENSC for both elastic and inelastic. Otherwise, the stuprf for
> these neutrons will be called only when there is an event that
generates
> a secondary particle in the stack i.e. proton recoil.
>
> Best Regards
> Vasilis
>
> -----Original Message-----
> From: Sunil C [mailto:sunilc@barc.gov.in]
> Sent: Friday, 02 March 2007 08:03
> To: Vasilis Vlachoudis
> Subject: Re: Scoring number of elastic collissions
>
> Hi
>
> Thanks a lot
> If let us say the medium is hydrogen in which i need to count, the
> energy of neutron is within the low energy group say 1 MeV then is it
> possible to do so by switching off the inelastic collision, switch on
> all elastic collisions by threshold card and not transporting the
> protons so that it does not escape the region. These can be counted
with
>
> USRBIn card. The number of protons will be more or less equal to the
> fluence in the region. I may be wrong also because if not transported
> the whole energy is deposited in the region. But these will not give
the
>
> number of collissions.
>
> Just a train of thought
>
> Best Regards
> Sunil
>
> Vasilis Vlachoudis wrote:
>
>> Hi Sunil,
>>
>>
>>
>> I would do something like the following:
>>
>> I will use the stuprf.f routine to increase the particle variable
>> ISPARK (1,NPFLKA) for every elastic event, like:
>>
>> IF ( LELEVT ) THEN
>>
>> * Increment number of elastic scatterings
>>
>> ISPARK (1,NPFLKA) = ISPARK (1,NPFLKA) + 1
>>
>> END IF
>>
>> And then use the USERDUMP with a modified MGDRAW routine to dump the
>> ISPARK variable which at this level should become ISPUSR(1), based on
>> the coditions: 1:falls below threshold, or 2. exists the system
>>
>> * Write Neutrons
>>
>> IF (JTRACK.EQ.8) THEN
>>
>> IF (ICODE.EQ.31 .OR. ICODE.EQ.12) THEN
>>
>> * Stopping or below threshold (POSITIVE) Unit:50
>>
>> WRITE (90, *) ISPUSR(1)
>>
>> ELSE IF(ICODE.EQ.14 .OR. ICODE.EQ.23 .OR. ICODE.EQ.32) THEN
>>
>> * Escapping from the geometry (NEGATIVE)
>>
>> WRITE (90, *) -ISPUSR(1)
>>
>> END IF
>>
>> END IF
>>
>>
>>
>> Of course you have to activate the call to userdump and set the
proper
>>
>
>
>> cuts with the low-bias to stop the group treatment of the low-energy
>> neutrons
>>
>> like:
>>
>> LOW-BIAS 1.0 73.0 1 100
>>
>> USERDUMP 100.0 40.0 5.0
>> userdump
>>
>> OPEN 90.0
>> UNKNOWN
>>
>> neutcount
>>
>>
>>
>>
>>
>> In the routine I am using the sign on the number of scatterings to
>> discriminate if they fall below the threshold or they escape the
>>
> system.
>
>>
>>
>> Cheers
>>
>> Vasilis
>>
>>
>>
>
------------------------------------------------------------------------
>
>> *From:* owner-fluka-discuss@fisica.unimi.it
>> [mailto:owner-fluka-discuss@fisica.unimi.it] *On Behalf Of *Sunil C
>> *Sent:* Thursday, 01 March 2007 14:00
>> *To:* fluka-discuss@fluka.org
>> *Subject:* Scoring number of elastic collissions
>>
>>
>>
>> Hi All
>>
>> I would like to count the number of elastic collissions a fast
neutron
>>
>
>
>> undergoes before reaching the thermal energy. I see that this
>> information is scored in the MDSTACK. How do i extract these
>>
> information?
>
>>
>>
>> Best Regards
>>
>> Sunil
>>
>>
>
>
>
>
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