[Hallc] [EXTERNAL] invitation to participate in Pion-LT experiment

[Garth Huber]

Dear all,

We would like to invite you and your group to join the Pion-LT experiment
(E12-19-006) running in Hall C this fall.  Apologies if you already
received this message through other means.

The Pion-LT experiment is a "12 GeV flagship experiment" that will
acquire the definitive p(e,e'pi+)n L/T-separation data set that will remain
important for decades to come.  The motivations of the experiment are two-fold:
1) study the hard-soft factorization regime.
    Validation of understanding of pi+ hard exclusive reaction towards 3D hadron
    imaging.  The key to this validation is precision longitudinal-transverse
    separated data.  If sigma_L becomes large, leading twist GPDs can be studied
    in JLab kinematics, while a large sigma_T could enable transversity GPD
    studies.  We will also measure exclusive pi-/pi+ ratios from 2H target,
    yielding additional insight into hard-soft factorization at modest Q^2.
2) determine the pion form factor (Fpi) to high Q^2.
    We will indirectly measure Fpi using the "pion cloud" of the proton via
    p(e,e'pi+)n.  The pion form factor is the clearest test case for studies of
    QCD's transition from non-perturbative to perturbative regions, and Hall C
    is the only facility worldwide that can perform this measurement.  We will
    acquire high quality data up to Q^2=6.0 GeV^2, with an extension to Q^2=8.5
    GeV^2 (with larger errors).

For more information, please see our recent Collaboration presentation:
   https://urldefense.proofpoint.com/v2/url?u=http-3A__lichen.phys.uregina.ca_index-5Ffiles_talks_fpi12-5Fhallc-5F21jul-5Fs.pdf&d=DwICaQ&c=CJqEzB1piLOyyvZjb8YUQw&r=QxP5KTzkAiDxkNbQw9W17g&m=zGnhYdbKDWhIA_kIqaGccFCpNLusK4T-LZwiuHRsDLU&s=MSXQ3pPceRLiiTxu4RsJgVFk9eGvTu8VD78TWZLDOm8&e= 
or the Pion-LT website:
   https://redmine.jlab.org/projects/hall-c/wiki/

The low epsilon portion of E12-19-006 is scheduled to start on 22 August and is
expected to run until the end of the year.  The high epsilon portion of the
experiment is scheduled for fall 2022.

We really need your assistance to make the experiment a success!!
We would like co-authors to take shifts in both the 2021 and 2022 runs, if
possible.  For fall 2021, there are 756 person-shifts needed @ 2 workers/shift,
so we would like co-authors to take 10 shifts, with a remaining ~5 shifts in
2022.

We hope that COVID-19 travel restrictions will continue to be relaxed during
the autumn, to enable non-local collaborators to participate in the experiment.
If you would like to contribute, but the restrictions preclude your travel to
JLab, please contact us for alternate arrangements.

The shift schedule can be found here:
https://misportal.jlab.org/mis/apps/physics/shiftSchedule/index.cfm?experimentRunId=HALLC-PIONLT

Thanks and best wishes,
Dave Gaskell (gaskelld at jlab.org)
Tanja Horn   (hornt at jlab.org)
Garth Huber  (huberg at uregina.ca)

-- 
Dr. Garth Huber, Dept. of Physics, Univ. of Regina, Regina, SK S4S0A2, Canada.
tel: 1-306-585-4240. fax: 1-306-585-5659.