[G12] Analysis of eta-pi photoproduction on the proton

[Andrea Celentano]

Dear g12 colleagues,
I write you to inform that, after a long time passed after my PhD thesis 
defense, that included a (preliminary) analysis of the gamma p -> p pi0 
eta reaction from CLAS-g12 data, I decided to resume this analysis, 
starting from scratch and following closely the g12 procedures 
highlighted in the official g12 note. In the analysis, I am identifying 
pi0 and eta via the gamma-gamma decay.
This will be a low-priority project for me, but I’d like to come to an 
end of it - from what I saw in the thesis, this channel is very 
promising. Now, given the huge improvements in g12 analysis that the g12 
group did, I think it will be simpler to come to an end of the 
analysis.I’d like to inform you - just to double check if there is 
anyone else looking at this reaction.
I have just started the analysis, and I am in the phase of selecting a 
good sample of exclusive p pi0 eta events. Meanwhile, I also started MC 
generation. At some point in the next future, I’d like to show some 
progresses in one of the bi-weekly meetings, in order to get your 
feedback from this.

I already have a simple question regarding MC. I followed closely the 
procedures highlighted in the g12 note to generate a phase-space MC 
sample (I followed the procedures highlighted for "proton, pi+, pi-", 
not those for "electrons and positrons"). In the real data, if I plot 
the invariant mass of a photon pair, I see a pi0 peak at around 135 MeV. 
However, If I do the same for MC events, I see a peak at about 116 MeV. 
I also plotted the reconstructed photon energy over the generated photon 
energy, and I see a peak at around 0.87. It looks the simulation of EC 
response in MC is not completely correct. (I confirm that the peak for 
generated events is at 135 MeV)
Is it because, using the EC, I should follow the procedure highlighted 
for "electrons and positrons" (involving run number 10 and requiring 
setenv CLAS_CALDB_RUNINDEX calib_user.RunIndexg12_mk?)

I also have a question regarding the TOF knockout procedure. In the 
note, the relevant method to use is: clas::g12::pass_g12_TOFKO(int 
sector, int scid, bool all_ko = 0), that requires to know the counter 
ID. For a charged particle, from the PART bank I can retrieve the entry 
in the TBID bank, and from this to the SCRC bank, that, however, 
contains information regarding TOF clusters. From this bank, I don't see 
a pointer to the SCR bank - containing individual paddles data.

Thanks,

Bests,
Andrea

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