Hall D meeting Wed Sep 15

[Elton Smith <elton@jlab.org>]

Hall D meeting Wed Sep 15
-------------------------

Comments on the collaobration meeting.

List of tasks which need to be completed by the review:

See
http://www.jlab.org/ccc/mail_archives/HALLD/halld-jlab/msg00607.html

http://www.jlab.org/ccc/mail_archives/HALLD/halld-jlab/msg00609.html

From my own notes, items of interest
------------------------------------


0 FDC
- Need a physics justification.
- Describe motivation of choice of technology (e.g. wires and cathode
strips)
* Material in beam. Need initial estimate for total thickness and a
proposed scheme for how to mitigate this.
* Consider pattern recognition issues as the motivation for design.
- Understand why cathode strip signal seems to be narrower than anode
signal.

o Solenoid
- For the review, we need a general intro into the magnet before detailed
breakdown of refurbishment effort.

o Target
* Obtain a nominal target diameter based on minimum t to target proton.
- Develop nominal design based on Hall B target.

o DAQ
- Clear design requirements need to be presented at the detector review
- Estimates of work division between GlueX and JLab DAQ group should be
  developed.

o Trigger
- Backward veto in trigger?

o Infrastructure
- Fringe fields of magnet a the position of the tof pmts and LGD pmts.
  - Paul will appoach this in a two step process: a) include bulk size and
    weight of cellular wall into model to obtain fields at TOF pmts,
    b) create a model for small section of cellular wall and create an
    external field to match original estimate. Use the distorted field in
    the wall to provide better estimate of field at location of LGD tubes.
- Study Bcal insertion mechanism options in more detail (George with Ravi
  and Paul)
- Finalize positions and sizes of all detectors (Curtis and Zisis may be
  close to this already) and disseminate this info.
- Obtain a total rack count for electronics and review power budget (Paul
  Smith to look at estimates by Chris)

o Electronics
- Pipeline issues: Fallen between the cracks?

o Preparations for Review
- Allison and Larry to address committee
- Larry will be the formal (JLab) contact to review committee. Elton will
  be the conduit between the collaboration and Larry.
- Alex will give the PID and LGD talks
- Split DAQ and Electronics into two talks
- David Lawrence will give the software talk

---------------------------------------------------------------------------

From Paul Smith's notes concerning items we need to address:

DAQ

Ed Jastrzembski will develop a next generation Trigger Supervisor which
supports "blocked" event readout as well as an experiment-wide clock
distribution system.  The distributed clock will be 62.5 MHz; crates
will generate local clocks phase-locked to this distributed clock.

Ed, could you produce a short description of your thoughts on this
clock distribution system?  Is it fiber optics?  I assume a global
"reset" will be distributed as well?  The FADCs need this to
synchronize all channels.  How about special triggers for calibration,
etc?  Are the F1 TDCs capable of using this clock as a reference?

The current and near future work by the DAQ group assume a VME64X
"form-factor", but other "form-factors" such as VXS, VXI, ATCA, cPCI,
PXI, etc are not being ruled out for GlueX.

------------------

Trigger

We want the ability to use the Start Counter in the level 1 trigger.
Other detectors such as the backward veto may also be part of the level
1 trigger.  Dave Doughty will make the CNU student's thesis on trigger
simulations available.  Dave is requesting NSF money to continue the
level 1 energy sum prototype work, especially the high speed serial
links.

---------------------



From Paul's summary talk:

Fernando Barbosa will be working on a prototype FADC which could be
used in the existing JLab experiments and would be suitable for the
GlueX central and forward drift chambers.  Paul Smith will be working
on a prototype FADC for the GlueX calorimeters which will include the
energy sum needed for the level 1 trigger.  Paul and Fernando will
communicate and try to keep the FADCs as similar as possible.  If it is
possible to converge on one design for all GlueX FADCs (for example by
stuffing different front end components) this will be done.

Here is my table of institutions responsible various electronics
subsystems with names added.   Please let me know of any mistakes
and/or additions:

Vertex tracking		deleted
Calorimeter FADCs	IU			Paul Smith
Tracking FADCs		JLab		Fernando Barbosa
TDCs				JLab		Fernando Barbosa
CF discriminators	Alberta		Jim Pinfold
Drift chamber amps	Alberta		Jim Pinfold
Level 1 Trigger		CNU			Dave Doughty
Clock distribution	JLab		Ed Jastrzembski
Power & grounding	JLab		Chris Cuevas
Tagger				CUA			Dan Sober
Goniometer			Glasgow		Jim Kellie
Active Collimator	UConn		Richard Jones
Track count			????
Calibration			????
Pipeline issues		????

Alex will continue to communicate with ORNL regarding their involvement
in GlueX electronics.

I've asked Zisis to add an electronics forum to the GlueX portal.  My
hope is that this will be the starting place for links to documents on
GlueX electronics designs.  I will put this email there when the forum
is available.  I encourage people to place minutes of any meetings
where GlueX electronics are discussed there as well.  If this forum
doesn't work out, we could consider a listserv for electronics
discussions.





Elton Smith
Jefferson Lab
elton@jlab.org
(757) 269-7625