[Lowq] Minutes of the eg6 meeting on August 31

[Stepan Stepanyan]

  Dear all,

On behalf of eg6 group I want to thank Hovanes for his valuable
contribution to the setup and running of the eg6 experiment and
for his leadership in the data calibration till now. Lets wish him a
good luck and success in his new position as Hall D staff.
I hope he will find time to contribute to the eg6 in the future.

Stepan

On 8/31/10 11:44 AM, Hovanes Egiyan wrote:
>
>
>   Minutes of the August 31 meeting
>
>
>       From Lowqwiki
>
> Present: Bayram, Dave, Stepan, Hovanes
>
> On the phone: Raphael, Raffaella, Will
>
> Notes by Hovanes.
>
>
>     Contents
>
> [hide <javascript:toggleToc()>]
>
>     * 1 Announcements
>       <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Minutes_of_the_August_31_meeting#Announcements>
>     * 2 EC timing
>       <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Minutes_of_the_August_31_meeting#EC_timing>
>     * 3 Solenoid
>       <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Minutes_of_the_August_31_meeting#Solenoid>
>     * 4 Hodoscope
>       <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Minutes_of_the_August_31_meeting#Hodoscope>
>
> [edit 
> <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php?title=Minutes_of_the_August_31_meeting&action=edit&section=1>]
>
>
>     Announcements
>
>     * Hovanes will start working for Hall D this fall and will not be
>       able to continue performing the dutie of the analysis
>       coordinator. Stepan agreed to be the eg6 analysis coordinator.
>
>
> [edit 
> <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php?title=Minutes_of_the_August_31_meeting&action=edit&section=2>]
>
>
>     EC timing
>
>     * Bayram looked at 6 GeV cooked data and he came to concluion that
>       they do not need more calibrations, at least for the next
>       cooking pass.
>     * There was a small issue with 1.2 GeV timing when he looked at
>       run 61441
>       <http://clasweb.jlab.org/rungroups/lowq/wiki/images/9/93/EC_TIMING_61441.pdf>.
>       There was ~100ps offset for EC time with respect to SC time
>       although the start times from both EC and SC were at zero.
>     * An attempt to calibrate EC timing with 1.2 GeV data itself was
>       not successful because because there were no hits in large areas
>       of EC because of the CLAS configuration for low energy runs.
>     * It was decided to keep only two calibration points for EC timing.
>
>
>
> [edit 
> <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php?title=Minutes_of_the_August_31_meeting&action=edit&section=3>]
>
>
>     Solenoid
>
>     * Hovanes compared the 3 solenoid field maps
>       <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Solenoid_update_31Aug2010>:
>
>
>        1. The DC tracking FPACK map
>        2. Solenoid field map currently being used in *gem* package
>        3. Field map sent by Eric
>
>     * His conclusion is that there is a bug in the tracking code when
>       reading the field map. It creates 0.5cm offset in Z and
>       R-directions.
>     * This needs to be checked by cooking data. It would be good to
>       check e1dvcs data on proton with and without "fixing" the bug
>       and see if there is improvement in the elastic event angle and
>       vertex matching.
>     * We need a map with known current at the power supply and clearly
>       identified format (preferably FPACK file similar to what is
>       being used in DC tracking now).
>
> [edit 
> <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php?title=Minutes_of_the_August_31_meeting&action=edit&section=4>]
>
>
>     Hodoscope
>
>     * Wiil studied the ADC spectra for pedestals and production runs
>       <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Aug31_hodo>.
>     * The ADC spectrum for the eg6 pedestal runs is drastically
>       different from what Mikhail Yurov had from previous CLAS periods.
>     * It seems like the HV were off during the pedestal runs.
>       Therefore this particular run is useless even for pedestals
>       extractions.
>     * Stepan suggested to look at the plot of energy (ADC) vs timing
>       (TDC) and use cuts on these plane to select out-of-time hits to
>       get the pedestal and the single photoelectron peak.
>     * Dave performed studies to identify ?^0 in IC/SH
>       <http://www.jlab.org/%7Ejenkins/eg6/31aug10/31aug10.html>.
>     * Dave looked at the time difference between hits in IC and CLAS.
>       He sees two peaks, and he interprets the peak at -2ns as the
>       events with correct timing and places cut around it.
>     * He also uses energy corrections provided by F.-X. and looks at
>       2-? pairs.
>     * Looking at the occupancy of the hodoscope he also see the
>       missing segment due to HV channel being off.
>     * Dave also uses cuts on the energy versus time plots to select
>       in-time events in hodoscope. When he does it he sees that ~8% of
>       pions produce hits in the hodoscope, which is more or less
>       consistent with what Mikhail Yurov found (~5%).
>
>
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