[G12] Analysis of the p+gamma -> p+pi0+eta reaction in CLAS, g12 dataset

[Craig Bookwalter]

Hi Andrea,
  I'm sorry that I was unable to attend the meeting this morning, for you
have done some very interesting things with this channel. Forgive me if
I am asking you to repeat in writing things that you may have mentioned
already.

I am impressed by the plots shown in

http://wiki.ge.infn.it/g3wiki/index.php/SummaryPiEta#Pi0-eta_event_yield_after_cuts

especially the high energy bins. The axis label here is W--this must be
the eta pi0 mass, no? I am impressed by the prominent peaks at 1.3 and 1.6
GeV, and I'm looking forward to seeing these decomposed into partial
waves.

There are other methods you might try to improve your gamma pair
assignments to pi0 and eta. You could, for each gamma pair, boost into the
gamma-gamma rest frame and look at the angle between the two gammas. For
the correct gamma pair, this angle should be 180 degrees. Also, you could
look at the energy balance between pairs of gammas -- the energy should be
shared approximately equally between the two photons. If I was doing this
now, I would try all of these in MC and compare my answers to the MC truth
information to see which method is the most efficient.

Also, are there plans to perform kinematic fits to constrain the selected
pairs to the eta and pi0 masses? I'm not sure of the state of the
apparatus for doing such fits, but as the position resolution of the EC is
somewhat coarse (and thus your angular resolution) it could have a big
impact on the results of a PWA, both in CLAS6 and in CLAS12.

Finally, is it true that the CLAS12 version of this analysis will benefit
from the IC? If so, is the goal to show that this analysis can bear fruit
even without the IC?

Looking forward to seeing more!


--cb


> Dear all,
> I'd like to show you some results I obtained from the analysis of the
> reaction:
> p + gamma -> p + pi0 + eta
> measured with CLAS, during the g12 run period.
>
> I analyzed this reaction as a "by-product" of my PhD thesis. The
> objective of my PhD thesis is to simulate the above reaction in CLAS12,
> in the MesonEx experiment. To do so, I'm using a given amplitude to
> generate MonteCarlo events, that are then projected in CLAS12. The
> obtained pseudo-events are then analyzed trough PWA technique, to
> actually demonstrate the feasibility of the measure.
>
> The amplitude I'm using was developed in the Regge theory framework.
> However, it contains some free parameters that needs to be fixed. I did
> this by analyzing the above reaction, to obtain the values of the
> parameters, or at least their relative strength. Also, I used the
> reaction as a benchmark to test my event selection algorithm in a real
> experimental situation.
>
> You can find the results I obtained in the local Genova wiki page:
>
>
>
>   http://wiki.ge.infn.it/g3wiki/index.php/SummaryPiEta
>
> username: clas
> password: the usual clas password.
>
> I organized the page to show you the most important analysis points,
> providing you the links to pages with the details.
> (I used the wiki as a "personal logbook" to trace the analysis I did, so
> you're welcome to surf it, even if there could be some points not
> completely clear).
>
> Any comment / suggestion / critics is welcome!
>
> I'd also like to discuss my results during one of the g12 meetings.
> Since the current meeting time (2pm) is not so convenient for me (its
> 8pm in Italy), could we move the meeting time just for this occasion,
> preferably
> during JLab time mornings (before 12am JLab time?) Let me know if this
> can work for you.
>
> Thanks in advance
>
> Andrea Celentano
>
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