Re: increase in probability of particle production in N-N collisions

From: Francesco Cerutti <Francesco.Cerutti_at_cern.ch>
Date: Mon, 22 Feb 2010 11:48:29 +0100

Dear Anna,

I would like to add an obvious remark to the answer of Giuseppe, who
already pointed out that your results, if taken from ANY built-in scoring,
are already normalized *per incident beam particle* (i.e. Au ion).

If I'm not mistaking, you said that you are going to compare these results
with those that were obtained in the past loading as source particles the
Au+Au reaction products. Obviously the latter ones are then normalized
either *per nuclear interaction* (if all the secondaries generated in a
Au+Au reaction were loaded in the SAME history) or, in the worse case,
*per reaction product* (if each reaction product was loaded as an
independent primary).

Ciao

Francesco

**************************************************
Francesco Cerutti
CERN-EN/STI
CH-1211 Geneva 23
Switzerland
tel. ++41 22 7678962
fax ++41 22 7668854

On Fri, 19 Feb 2010, Giuseppe Battistoni wrote:

> Dear Anna
> If I understand correctly your question: as long as you make use of the
> standard scoring of FLUKA
> (usrbin, usrbdx, etc.), all the weighting due in case of biasing is performed
> automatically and you do not need any
> additional normalization.
> Best regards
> Giuseppe
>
> Kiseleva, Anna wrote:
>> Hello Giuseppe.
>>
>> I tried such LAM-BIAS:
>>
>> *...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
>> .
>> LAM-BIAS 0.0 0.001 GOLD 4-HELIUM AOMEGAC0 0.0INEPRI
>>
>> It works. I collect now big statistics in order to compare new data with
>> old. The question: do I need additionally to normalize new data which I will
>> get with LAM-BIAS in order to have the same doses as for data without
>> LAM-BIAS?
>>
>> Best regards
>> Anna
>>
>>
>>
>> -----Original Message-----
>> From: owner-fluka-discuss_at_mi.infn.it on behalf of Giuseppe Battistoni
>> Sent: Mon 01-Feb-10 11:32 PM
>> To: Kiseleva, Anna
>> Cc: fluka-discuss_at_fluka.org
>> Subject: RE: increase in probability of particle production in N-N
>> collisions
>> Dear Anna
>> I had not time to enter in full detail in your problem. However there is
>> the suspicion that everything is due to the fact that you have a very thin
>> target. Therefore it is natural that only a very very small fraction of
>> primary interacts. By means of a MonteCarlo like FLUKA you can solve the
>> problem by using "biasing". In particular you can artificially
>> increase the probability of interaction and this will be compensated by
>> a proper weight through all the process, including the scoring.
>> Therefore I suggest in your case to try such a biasing. It can be introduced
>> with the LAM-BIAS command with the SDUM=INEPRI.
>> In that case the inelastic nuclear interaction length will be
>> reduced by a factor specificed by |WHAT(2)| (the actual value
>> is your choice!), With INEPRI this is applied only to primary particles
>> Let us know in case
>> Giuseppe Please try this and let us know.
>>
>>
>> Please read carefully the manual for the use of LAM-BIAS.
>>
>>
>> On Mon, 25 Jan 2010, Kiseleva, Anna wrote:
>>
>>
>>> Hello Giuseppe.
>>> The problem, wich I have now is following.
>>> My colleague, Denis Bertini, started the FLUKA calculation for CBM, but as
>>> a input for FLUKA he used UrQMD generated particles (SOURCE). The example
>>> of the simulation results you can see eDencity.jpg. I use the same input
>>> (oldCBM.inp), but new FLUKA version and without external generator. I have
>>> 877000 beam particles (Au ions), but I can not reproduce the picture
>>> eDencity.jpg (see Energy.gif). I don't see any errors in input (I use
>>> FLAIR), but the picture is strange.
>>> Best regards
>>> Anna
>>>
>>> ________________________________
>>>
>>> From: Giuseppe Battistoni [mailto:Giuseppe.Battistoni_at_mi.infn.it]
>>> Sent: Mon 25-Jan-10 1:04 PM
>>> To: Kiseleva, Anna
>>> Cc: fluka-discuss_at_fluka.org
>>> Subject: Re: increase in probability of particle production in N-N
>>> collisions
>>>
>>>
>>>
>>> Hello Anna
>>> Your result looks strange, but maybe we have not fully understood
>>> something.
>>> 1) Are you simulating collisions against a fixed Au target?
>>> 2) Which secondary particles are you looking for?
>>> 3) What is the threshold of secondaries that you are requiring?
>>> Even in fixed target collisions secondary particles are always expected
>>> in your case, if we
>>> interpret that such energy is energy/nucleon.
>>> If instead. you have given 25 GeV as total energy of
>>> the Au nucleus, then what you report is possible (E/nucleon about
>>> 25/197 = 126.9 MeV/nucleon)
>>> Can you send us your input file?
>>> Best regards
>>> Giuseppe Battistoni
>>>
>>>
>>> Kiseleva, Anna wrote:
>>>
>>>> Dear FLUKA experts,
>>>> I work in GSI in CBM group. I started to use FLUKA for radiation
>>>> study.=20
>>>> Our basic energy is 25 AGeV Au+Au collisions. I have one question.=20
>>>> If I understand correctly, for such system only 1% of the
>>>> interactions=20
>>>> will produce the secondary particles.=20
>>>> It means, I need high statistics of the events for my study.=20
>>>> Is there possibility to increase the probability to produce the=20
>>>> secondary particles? I tried to find self, but without success.
>>>> =20
>>>> Best regards
>>>> Anna Kiseleva
>>>> =20
>>>> ---------------------------------------------------------------=20
>>>> Dr. Anna Kiseleva=20
>>>> =20
>>>> B=FCro: C27 2.020
>>>> Tel.: +49-(0)6159-711304=20
>>>> FAX.: +49-(0)6159-713622=20
>>>> E-mail: A.Kiseleva_at_gsi.de=20
>>>> =20
>>>> CBM
>>>> Gesellschaft fur Schwerionenforschung mbH=20
>>>> Planckstrasse 1,=20
>>>> D-64291 Darmstadt=20
>>>> ---------------------------------------------------------------
>>>>
>>>
>>>
>>>
>
>
>
Received on Mon Feb 22 2010 - 21:54:12 CET

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