January 30, 2017, Analysis Working Group

Meeting Time and Place

The meeting will be on Monday January 30, 2017 at 2:00 pm EDT. For those people at Jefferson Lab, the meeting will be in room F224-225.

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The collaboration meeting is coming up soon. Those who have been working on studies for the past few months should either give their own talk, or email Paul Mattione a few slides with their current status.
The last analysis launch (ver05) finally finished after 1.5 months. Many files are available on the cache disk, but some may only be available on the tape. This will be the last analysis launch for a while (until the next reconstruction launch, or until there is demand).
The simulation launch was halted because it was taking too long. Instead, it will be launched again soon with EM background disabled, with the goal of generating a dataset that is 30% of the experimental data (in events).

Alex A. presented results from analyzing rho's the 2016 Fall data, showing that the TAGM timing calibration was off (and Sean mentioned there were other issues). This has been fixed, and a new monitoring launch is planned for later this week.
Sean mentioned that the Fall 2016 data should only be analyzed from 22016 and later, as the TOF was not calibrated before this time (HV scans, etc.)
Also, the data showed that the rho beam asymmetry for the new diamond at low energy (3 - 6 GeV) was 3.4 +/ 0.5%, inconsistent with zero.
Simon showed preliminary total cross section measurements for η, ρ, ω, and φ photoproduction to several different decay channels. There appears to be a bump in the cross section near 8.5 GeV in each of the multi-pion decay modes that is not present in the other decay modes, indicating that there may be an issue in modeling the tracking acceptance at these energies. He used his own generated MC, not sim1.1, for these studies, and the t-slope appears to come out roughly the same in data and MC. It is too early to judge whether the flux measurement is accurate or not.

There has been a new survey of the tagger hodoscope. They found small changes in the geometry that result in ~10 MeV shifts of the TAGH counters (not a big shift since counters are wide). However, they also found that at low energies (near 4 GeV) there is a large shift of 30 MeV. This would explain the energy shift seen in the data previously. New calibration constants are being generated and will be added to the database soon.

Mike reported that by using straight-line tracks he has some new alignment offsets for the experimental data. He's trying to check them by using simulated data, and he's currently working on getting the straight-line track fitter to give reasonable results on MC data.
Lubomir showed his tracking efficiency study from J/Psi, treating one of the leptons as missing and searching to see whether it was reconstructed, given a shower in the calorimeter for it to match to. Thus, his efficiency of ~70% combines both the tracking and the track/shower matching efficiencies.

The BCAL group is working on the TDC timing calibration timewalk corrections, and is working on trying to reduce the long tails in the timing spectrum.
Also, in the Fall 2016 run, the BCAL group noticed that the width of the π⁰ was much larger than it was in the Spring, and they are currently trying to determine the cause.
The FCAL group has seen a small change in the width of their π⁰ peak, and a shift down to 130 MeV/c (prior to recalibrating).