Hello Joe
Unfortunatey I am not able to answer to most of your questions.
FLUKA authors can give more details.
What I can tell you is that we tried to discuss if we can flag eta (or other particle)
production in hadronization.
At present this does not seem at all to be a simple job.
It cannot be excluded that, given this need not considered when designing
the code, in the future we can develop something in this direction.
It's not easy to give a time schedule: at present we have other compelling
priorities for the next release.
Sorry
Giuseppe
On 11/4/13 8:35 AM, Joseph Comfort wrote:
> Dear Giuseppe,
>
> I returned from a collaboration meeting in which there was discussion of the importance of understanding the eta meson background in
> our experiment. With no guidance on how to get the information I want from Fluka (the coordinates of eta production, by what
> mechanism, and how they decay), I dug into the code. It is very intertwined reflecting, I guess, a complex history.
>
> There are several peculiarities.
> 1) In bdpart.f, the properties of etas are given to 2 code numbers, 29 and 31, although 31 appears to be the one that is used (and
> is not a 'user' particle).
> 2) There is an ETA550 for code 31, and also an ETA547 with code 112. Why?
> 3) In hadden.f, the ETA550 is given a mass 0.48 GeV. Why?
> 4) Can etas be produced by photons? There are (gamma,pi0) data. There are also (gamma,eta) data -- some very recent. We think
> most of our BG comes from neutrons, but there are plenty of photons available as well.
>
> I have not yet clearly identified where etas are produced in the code and how the decay mode is selected, but I think I am close.
> We will need to consider production by neutrons, mesons (e.g., pioms), and even photons in materials.
>
> I have set up some simple cases to see if Fluka actually produces etas, specifically with decay into 2 photons (the real BG for
> us). I tried a case for pi- on a liquid hydrogen (LH2) slab. There were plenty of pi0s and also some etas -- the latter at 0.48
> GeV! I also tried 3-GeV/c neutrons on an aluminum slab, but there were no pi0s or etas (in 10^7 events). But we have data that
> shows both, and this is the starting point of our concerns. A total absence in Fluka is disturbing, but maybe it is just a matter
> of cross section.
>
> Any guidance you can provide will be very helpful.
>
> Thank you,
> Joe Comfort
--
INFN Milano
via Celoria 16, 20133 Milano, Italy
tel: +39 02 50317307
fax: +39 02 50317617
Received on Mon Nov 04 2013 - 09:44:21 CET