[G12] Minutes from 4/7/2010 meeting

[Craig Bookwalter]

Hi folks,

Minutes from today's meeting are found at the following link:

http://clasweb.jlab.org/rungroups/g12/wiki/index.php/07Apr10#Minutes

and pasted below:

07Apr10
>From G12_wiki
[edit]
Agenda

    * Update on flux/sync
          o Gflux and tripfixer results
          o Good vs Bad scaler intervals
    * Momentum corrections
          o Heghine
    * Analyses status:
          o eta pi- Delta++ Diane
          o pi+ pi+ pi- Craig
          o Cascades Johann (plots from last week with more statistics - 55%)
          o Kaons Will/Mike
          o K+ K- Mukesh[[1]]
          o KKpi Miles
          o Deltas/X Paul

    * Other business

[edit]
Minutes

    * Attending: Johann, Dennis, Carlos, Mike P. x 2, Will, Heghine,
Valery, Diane, Craig, Paul E., Lei, Sasha O.,
    * Diane updated us on gflux -- she's run on all the files in the g12
run period, but has not run tripfixer on these yet. We are currently
sitting at 10x g6c statistics from 4.8 GeV and up.
    * Craig reports that the guy at CMU has provided him with Mike
Williams' phase-space events. Craig gets the feeling that asking this
guy to do MC weighted with Mike's PWA results will take a long time
just based on his experience level. Paul suggests that we try and
generate omega events with a proper t-channel distribution and then
weight them according to the real Dalitz distribution. Paul will call
Curtis and ask for help with generating the weighted MC.
    * Sasha showed a couple plots illustrating how many events are
acquiring during scaler intervals marked as good or bad by tripfixer.
He concludes that 8% of all good events are in bad scaler intervals.
The group feels that this 8% is not worth recovering.
    * Heghine shows some plots from the e6 momentum corrections. The
proton and pi+ are moving toward their nominal masses but not the pi-.
She will add the results of the fit to these plots. Also, she will try
fitting a line to her 2D plots to see just how flat the corrected
masses are as a function of momentum.
    * Craig and Johann report that the first set of parameters for the g11
momentum corrections have been created. There's a nontrivial number of
bins whose fits resulted in outlandish values, most likely due to
statistics (Craig is using 10 runs around 56855, but he's going to try
using even more statistics). It is also likely that since the g11
angular range is different than g12, the g11 binning is not
appropriate. Changing the binning structure would reduce the amount of
code we're able to reuse to almost nil, so Johann and Craig will not
correct events falling into these bins.
    * Diane showed some 2D mass plots from her analysis. Unfortunately she
has a lot of N* activity in the p pi- system. The t-slope in the
region of the a2 is 1.398. Dennis suggests a t-cut is necessary--he
would like to see how the N*s respond to selections on t. She's
getting about 0.3% acceptance -- this seems like a reasonable number.
There's some question as to the acceptance of CLAS for photons.
    * Johann shows some plots updated from last week with more statistics.
No excited states. Interesting structure in in the K+K+ missing mass
vs the K+K+pi- missing mass -- neutral ground-state cascade is
present, but we're not sure where it's coming from.
    * Carlos shows some plots from pKK showing some K* production. When
applying Diane's cuts for pKK2g events, he sees a strong pi0 but not
etas. He thinks this is because all of the beam energy goes to
producing the K's, and there is little momentum left to boost the eta
into the EC. He does see a lot of etas in the missing mass spectrum,
however, so they are present.
    * Mukesh shows some plots that are similar to Carlo's. He sees the eta
and pi0 in the missing mass off pKK. We suggest he cut only on the
event vertex and not the individual track vertices. But overall he's
looking good. Sees something at 1680 in the phi-eta plot. Dennis would
like to know the ratio of the overlap to the bands of the K*K* Dalitz
plot. If they are coherently adding, the overlap can be up to 4x
greater than the band; if it's incoherent, it can only be 2x