[APEX] APEX Update and Requests for Help

Tue Nov 1 18:00:03 EDT 2011

Dear APEX collaboration,

Please read this email carefully.  It is long, but contains several
important announcements and requests for help.  The full text of this email
can also be found at:

http://ntoro.stanford.edu/APEX/wiki/index.php/APEX_update_November_2011

We have successfully completed the first stage of the APEX experiment: a
successful test run leading to the approval of the full experiment and the
acceptance of the PRL on the test run science results.  We are now
preparing for the full experiment.

While APEX has not yet been scheduled, we would like to be ready to run
anytime and as soon JLab's schedule allows.  However, there are a few
things to do before we can run, and we want to take care of these over the
next 2--3 months.  Below, we detail the near-term plans and several
hardware and software projects for which we would greatly welcome help.
These contributions will be very important to the smooth running of the
experiment.  We especially encourage contributions from collaborators who
anticipate having little or no availability for shifts, as significant help
with these projects will count toward authorship on APEX papers.  Please
read these and let us know where you can help out.

*1. Rights and Responsibilities of APEX Collaboration Members*

We will define more clearly the rights and responsibilities as an APEX
collaboration member, and what is required to be on future APEX
publications.  There will be around 600 shifts to fill, and we will likely
ask that anybody who wants to be on a future APEX publication will need to
complete at least 10.  However, significant contribution to the preparation
of the experiment (see below) will decrease or remove the required number
of shifts.

*2. Where we need your help*

The level of expertise needed for the projects below vary, but most are
appropriate for a post-doc, or for students with active leadership from a
senior scientist.  Please contact any of the spokespeople if you would like
to lead or join any of these efforts.  We anticipate that most will require
roughly one month worth of work.

I) Target Lifter Mechanism: test Waterfall Lifter, investigate options from
other halls, and target GUI

II) VDC analysis/reconstruction

The APEX run will produce electron singles rates of about 5 MHz.  At these
singles rates, the existing reconstruction software has an efficiency of
50-60%; we are seeking expertise in modifying the VDC analysis algorithms
to optimize the efficiency of this reconstruction.  Data is available to
test the analysis code.

III) Online software and GUI

A standard Online GUI is needed to test performance during the test-run
(previous Hall A GUIs can be used as a starting point).

IV) Optics calibration

APEX optics calibration will be done using both the sieve-slit method and
new scintillating fiber detectors (SciFi, see also below) upstream of the
HRS's.  We are seeking experts to coordinate with the target group on the
design of the Optics Target, helping to devise an optics run-plan, and
updating baseline optics calibration software (needed to ensure data
quality in optics calibration runs) to use the SciFi detector signals.

V) Beamline and target alignment

The target alignment and calibration of the GUI needs to be formulated.
Beam line commissioning procedures on the level of MCC requirements need to
be formulated, written, and approved.

VI) Detector electronics

We are looking for a point-person with Hall A experience to take charge of
preparing and testing electronics for the HRSs, including HV units and
spare DAQ modules as 1877S TDCs.  Buffered readout DAQ configuration needs
to be organized and tested.  Once the schedule is known, we plan to start
installation of the S0 counters and VDC electronics, which will require an
additional 5--6 man-weeks.

VII) Target

The SLAC target was designed exclusively for the test-run configuration of
a 2 GeV beam.  We need to finalize the full target, for three different
beam configurations, and consider alternate designs for the optics target
in light of high rates in SciFi detectors.

VIII) Trigger Development

The production trigger scheme will be as for the APEX test run, but
detailed schematics for the trigger system will need to be revised.

*3. Radiation safety review*

The PAC has asked for a review of the neutron radiation damage on the
electronics that might be incurred from running APEX.  We are working with
RadCon and JLab management to complete this review by December 15, 2011.

*4. Possible Theses for graduate students*

The full APEX run consists of four different beam energies and settings.
Using this data, we imagine that between 2--4 theses could be written on
the main APEX science result (an A' search) -- the final publication would
of course be on the whole data set from all four settings.  A high
statistics QED trident sample could also allow for other theses to, for
example, investigate higher order QED effects.  Other suggestions for
theses topics are welcome.  If you have interested graduate students,
especially with some proficiency in GEANT or ROOT, please let us know.

*5. Talks at Conferences or Seminars *

If you want to give a talk on APEX results at a conference or seminar,
please let us know.  Preference will be given to collaborators that have
made major contributions.  We will define more clearly your rights and
responsibilities for giving presentations.

We hope that you will be able to help us on some of the above items.
Please let us know if you have any questions, comments, or suggestions.

Kind regards,

Rouven Essig, Philip Schuster, Natalia Toro, Bogdan Wojtsekhowski

(APEX spokespeople)
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mailman.jlab.org/pipermail/apex/attachments/20111101/78019bb9/attachment-0002.html>