Here is a quick summary of the last collaboration meeting, held
at JLAB January 8-10, 1998. I do this with the idea of keeping
those who missed the meeting up-to-date and producing a record of
what happened. As always, I run the risk of superimposing my
own interpretation on top of the events. In most cases, that is
not the intended goal. The next collaboration meeting is tentatively
set for June 4-6, 1998. We will consider new proposals; they must
be submitted to the appropriate Physics Working Group coordinator
a few weeks in advance for proper reading. I apologize for the length
of this message, but there were many important discussions at the
meeting that I felt needed to be recounted.
As always, the meeting showed many accomplishments. Perhaps, there
is more to be proud of this time because we have finished our first
production run period. The e1 run group took data for ep->eX at 1.6 and 2.4
GeV energies. I estimate that this represents about 5% of the total e1
running. In order to do this run, we significantly upgraded the apparatus
and our ability to monitor it. At the beginning of the run, roughly
98% of the about 40,000 total CLAS readout channels were installed
and at least partially calibrated. We also had significant low-level
monitoring capabilities available for shift personnel to quickly note when
a phototube had died or a drift chamber ADB crate tripped. We also had pagers
held by someone from each technical group at all times; if a problem developed
with a system, e.g. cryotarget, only one number needed to be called most of
the time. The electronic log book was heavily used for the first time. It
was a great success because almost everyone used it and people all over the
site and elsewhere could see via the web. For the first time, a shift expert
training session was held, run by Arne Freyberger. Those who attended learned
from technical experts how to use and monitor each technical system. This
session will be done again before the next run; it will be shorter and there
will be ways to get hands-on experience. Finally, there was a hall closeup
checklist that helped make sure no important step was forgotten in the rush
of the last few days. All these were important steps towards our large
goal of becoming a successful data taking organization. I am not aware
of significant problems with the direction in which we are moving, just with
the slowness of getting there.
There were a number of contributions discussing the understanding
of each detector system and some aspects of the December e1 data.
Rather than give a long discussion, let me say that significant progress
was made, but a lot of analysis remains. At the highest level, we have
qualitative understanding of the elastic and inclusive electron
scattering cross sections. Events for ep->ep, eppi^0, epeta, enpi+
have been positively identified by a few people. The problems in the
data are not felt to be bad enough to preclude eventual publication.
Major problems were 2 missing and 1 severely leaking Cerenkov detector
and a crippling set of broken wires in Region 1, sector 2, and a limit
of ~400 Hz in the possible DAQ rate. Data taking efficiency was 19% in
the CALCOM phase of data taking, 52% for 1.6 GeV and 38% for 2.4 GeV
according the shift summary sheets our shift leaders fill out. We had
a heavy loss of time at the beginning of each segment. At the first energy,
the problems were with both CLAS and the beam, resulting in a loss of
about 4 days. At the second energy, we lost 2.5 days to beam problems
alone. Out of a 19 day run, these down times are significant.
The next half year will have e1, gamma commissioning, g1, g5, and g6
run groups taking data. It will be a very busy time. To make sure
we use the time most efficiently, we will start cosmic ray running
with the full detector system and final electronics and DAQ on February
1.
We had presentations and discussions for online and offline software.
Much has been accomplished, but much more work remains before we have
full use of the detector capabilities. Since the collaboration has
emphasized hardware construction and installation until recently, this
is to be expected. Nevertheless, we must successfully inject new
manpower into these efforts.
CLAS Collaboration Business
---------------------------
There were 4 new candidates considered for membership by the Membership
committee. They are Marco Battaglieri (INFN-Genova), Allena Opper (Ohio
U.), Laird Kramer (Fla. Int.), and Dave Tedeschi (So. Car.). All were
unanimously recommended for full membership. A vote of the full
collaboration will be held at the next collaboration meeting.
Any limited members must be officially approved by the Coordination
Committee after the names are submitted by the experiment spokesman.
I think it is appropriate for the run group coordinators to monitor
and maintain the lists of limited members. Spokesmen should send
their proposed limited members to their run group coordinator and to
the CLAS Chairman.
The run plan committee met and Bernhard Mecking proposed a fallback
plan for potential (not actual at this time) problems in bringing up the
polarized target in July. The run plan committee was in unanimous agreement.
If the delay is less than about 1 month, we will either go into dectector
repairs or extend one of the photon beam experiments, g1 and g6. Many run
groups have ways to use low current polarized beam, but only e1 has approved
time. If the delays are longer than about 1 month, the e1 run group will run
their experiment with polarized beam and unpolarized target. No objections
were expressed by the collaboratin. This fallback scenario will be reported
to Larry Cardman.
The roles of Experimental Coordinator (ECO) and Chief of Operations (COP)
were discussed. Not all of the audience remembered the 1994 discussion, so
a brief discussion might be useful. According to the Charter, major
decisions during individual runs are largely made by these folks. The
COP has final say in how the equipment is used- he sets up shift training,
makes sure the equipment is operated in a safe manner, and makes sure the
run plan established by the ECO can be executed with CLAS as it exists at
the time. The COP is chosen by the Program Manager with significant advice
from the run group. The ECO is chosen by the spokesmen of each run group
subject to endorsement by the Coordinating Committee. Every JLab experiment
must have a run coordinator. The duties of this person are very similar
to that of the ECO, so we use the 2 terms interchangably.) The ECO represents
the interests of the run group during the run to avoid the problem of
too many incoherent voices speaking for the run group. The ECO gathers
information by himself and from the spokesmen and makes a run plan that
best reflects the goals of the approved experiments in light of the
existing capabilities of CLAS. Both represent Hall B at the daily Operations
group meetings and the Wednesday Scheduling meeting. Thus, COP and ECO
need to work closely together to be successful. We are just starting to
have experience, but I am not aware of any reason to change the roles
of these positions. If there are problems, please tell me.
They must also interact effectively with the CLAS staff headed by the
Program Manager. We have established a new Technical Coordinating
Committee where the Program Manager, ECO, and COP meet with the appropriate
technical leaders to establish an overall plan for action. Unfortunately,
the operation of CLAS is too complicated to have many small meetings to
establish correct priorities among many competing interests.
The Charter amendments regarding publication policy were discussed extensively
at the September, 1997 collaboration meeting. A vote was held this meeting.
Any full member can vote by sending email to Jim O'Brien before January 17.
We discussed the idea of getting the many maintenance jobs of CLAS done.
These can also be excellent hardware and software experiences for future
students. The technical construction and installation is largely complete
and the jobs are becoming those of hardware maintenance and repair and
software maintenance, documentation, and running of jobs. As a start, **each
technical group is asked to send to me** a list of jobs for which they
require a worker. For each, give a brief exposition of the duties and the
skills expected for the worker. A straw poll gave overwhelming agreement
to the proposal that every group be asked to cover tasks from a list. It
is likely that the list will be held by the Coordinating committee. Mac
Mestayer is the chairman of the ad hoc committee charged with suggesting
procedures; they will make a recommendation at the next collaboration meeting.
There were volunteers for this committee; Mac will choose a small, hard
working committee from these volunteers to do the work.
We discussed the role CLAS should play in the JLAB Users' Group Workshop
studying upgrades to the present halls and possibilities for a new Hall D.
The dates will be June 14-18 and each Hall is expected to make presentations
for desired upgrades to enable better usage of beam energies of 8 GeV
and higher. Carlos Salgado offered to coordinate the effort, but all are
invited to participate. There was discussion of having a second coordinator,
I will pursue this possibility. This group will also make presentations at
the next collaboration meeting to decide what will be presented at the
workshop. Obviously, nothing can be presented as the collaboration viewpoint
without collaboration agreement.
The discussion of the next collaboration meeting ended with the choice
of June 4-6, 1998 at Jefferson Lab. That is just after the Italian
N* workshop and just before the Confinement workshop and 8+ GeV
workshop which will be held at the lab the 2 following weeks. We
will consider new proposals at that meeting and we should have interesting
reports on the initial photon beam experiments and preparations for running
with polarized target.