RE: p+U reaction

Sorry, I had not understood that you had MORE neutrons exiting the target
than produced inside it.
A likely explanation is the following: in the final statistics of the
FLUKA standard output,
"Number of secondaries generated in inelastic interaction per beam particle"
refers only to neutron with energy> 20 MeV.
Produced low-energy neutrons are accounted for separately in the same part of
the output.

Alberto

On Wed, 21 Jul 2010, Andrzej Wojciechowski wrote:

> Dear Lucia and Alberto
> Very thanks for your help.
> Unfortunately problem is not clear for me yet.
> In my opinion 'Number of secondaries generated in inelastic
> interaction per beam particle" means all produced particles (37.8
> neutrons).
> This number have to be greater or equal than escaped neutrons scored
> by USRBDX card in the boudary between 3 and 4 regions. The USRBDX card
> using current option (not fluence) give the results - 42.8 neutrons.
> (Experimental data 38.8+-5%)
> Why all produced neutrons (37.8) is less than exited neutrons (42.8)?
> Im my opinion all neutron are inelastic in this problem.
> Kind regards
> Andrzej
>
> Dnia 20-07-2010, wto o godzinie 10:51 -0700, Fasso, Alberto pisze:
>> Dear Andrzej and Lucia,
>>
>> the main reason for the difference between neutrons produced and neutrons exiting from the target
>> is that not all produced neutrons can escape, but some interact inside the target, getting absorbed.
>>
>> Alberto
>>
>> ________________________________________
>> From: owner-fluka-discuss_at_mi.infn.it [owner-fluka-discuss_at_mi.infn.it] On Behalf Of Lucia Sarchiapone [Lucia.Sarchiapone_at_lnl.infn.it]
>> Sent: Tuesday, July 20, 2010 4:15 AM
>> To: Andrzej Wojciechowski
>> Cc: fluka-discuss_at_fluka.org
>> Subject: Re: p+U reaction
>>
>> The main difference is due to the fact that the fluence is a quantity
>> that takes into account the direction of the particle with respect to
>> the boundary between the regions. In the manual you can read that the
>> fluence is weighted with the inverse of the cosine of the angle between
>> particle direction and normal to the surface.
>> In principle you can get rid of this weighting factor scoring current
>> instead of fluence, but you will still find some difference because -I
>> guess, and I hope that someone corrects me if I'm wrong - with the
>> USRBDX you are scoring neutrons from all interactions, not just the
>> inelastic ones.
>>
>> Lucia
>>
>> On Jul 19, 2010 02:39 PM, Andrzej Wojciechowski<andrzej_at_cyf.gov.pl>
>> wrote:
>>
>>> Dear Lucia
>>> Do you explain me why the total fluence of neutrons scored with the
>>> USRBDX estimator, crossing the boundary between region R3 and R4
>>> is diferent than the "Number of secondaries generated in inelastic
>>> interaction per beam particle" for neutron?
>>> Kind regard
>>> Andrzej
>>>
>>> Dnia 15-07-2010, czw o godzinie 14:41 +0200, Lucia Sarchiapone pisze:
>>> > Dear Andrzej,
>>> >
>>> > you are probably looking at the total fluence of neutrons scored
>>> > with
>>> > the USRBDX estimator, crossing the boundary between region R3 and
>>> > R4.
>>> > In my opinion if you want to look for the number of neutrons
>>> > generated
>>> > per primary proton you should look at the standard output file
>>> > (*.out).
>>> > In the list called "Number of secondaries generated in inelastic
>>> > interaction per beam particle" you will find that neutrons are
>>> > something
>>> > like 37.8 (depending on the number of primaries you run in the
>>> > simulation). This value is much closer to the experimental one.
>>> > Cheers,
>>> >
>>> > Lucia
>>> >
>>> >
>>> > On Jul 14, 2010 04:27 PM, Andrzej Wojciechowski<andrzej_at_cyf.gov.pl>
>>> > wrote:
>>> >
>>> > > Dear FLUKA users
>>> > > I am traying calculate the total number of neutron produced during
>>> > > reaction p+U-238 (see attachment) (1.22GeV)
>>> > > The experimental result[1] equal to 38.8+-5%,
>>> > > the calculation result egual to 44.0
>>> > > What am I doing badly?
>>> > >
>>> > > Kind regards
>>> > > Andrzej
>>> > >
>>> > > [1] L. Pienkowski,* F. Goldenbaum, D. Hilscher,=C3=A2? and U.
>>> > > Jahnke,
>>> > > Neutron
>>> > > multiplicity distributions for 1.94 to 5 GeV/c proton-,
>>> > > antiproton-,
>>> > > pion-, kaon-,and deuteron-induced spallation reactions on thin and
>>> > > thick
>>> > > targets.PHYSICAL REVIEW C VOLUME 56, NUMBER 4 OCTOBER 1997
>>>
>

-- 
Alberto Fasso`
SLAC-RP, MS 48, 2575 Sand Hill Road, Menlo Park CA 94025
Phone: (1 650) 926 4762   Fax: (1 650) 926 3569
fasso_at_slac.stanford.edu