E866 Off-line Analysis Plan

The off-line analysis plan consists of a number of different
levels addressing various needs and with different facilities.

Database - A common database that will serve analysis at all
stages outlined below, including wide-area network and programmed
access, will be used to collect and disseminate geometrical
alignment data and other detector and run data as well as to
keep track of all analysis done on each data sample.

Backend Analysis - Using approximatly 150 SpecMarks of SGI
UNIX workstations at the portakamp, which will be supplied by Fermilab,
we will analyze data in real time. Data will be shipped from the
on-line data acquisition system via ethernet and various monitoring
processes will verify it's integrity including full analysis and
tracking of up to 10% of the events. The analysis will address issues
ranging from raw detector histograms and dead channels, to overall
efficiency for detecting J/Psi events (with low statistics).

Bicycle Online - UNIX farms provided by Fermilab will be used to
analyze about 20% of the data soon after it is taken. This analysis
will check the readability of the raw 8mm data tapes, and will be
used to get initial results for cross sections and ratios. Here
we will also to investigate possible rate-dependent effects
on the cross sections and ratio. This analysis will also serve as
the prototype for the final production analysis, which is expected
to begin soon after data taking is complete.

Production Pass 1 - The same UNIX farms used for the bicycle online
will be used for the production first-pass analysis of the complete
data sample. This production analysis will include the most compute
intensive part of the the offline analysis. This will include track
reconstruction in the drift chambers, traceback to the target region
through the SM12 magnetic field, reconstruction of basic physics
quantities, and writing out the results for events that pass to a
data summary tape (DST). A UNIX farm of about the same power as
was used in the production analysis of the E789 data should be adequate
for this job and for the bicycle online above. This system was a
set of four farm systems with six IBM compute nodes each. We estimate that
such a system can analyze a E866 8mm tape of raw data in about 4 hours.
With the expected number of tapes being about 1000 the full analysis should
take about six months. Previously the 24 compute nodes of the farm were
divided into four smaller farm systems. We hope that with improvements in
the way input and output data flow are handled all the farm compute nodes
can be in one, or at most two, pieces. This will ease the management and
bookeeping of the production process.

Physics Pass 2 - The output of the first pass will be distributed throughout
the collaboration for final analysis to physics results. UNIX computing
resources at Los Alamos, the Fermilab Physics Department, and at all
the other collaborating institutions will be used for this. This type
of analysis will also be applied to the output of the bicycle online
analysis during the data taking. Also during data taking some of the
institions computing resources at large may be located at Fermilab
to provide easy access for the collaborators who are on site taking
shifts. In order to support the physics analysis off-site, we will rely
on our VME based tape copy facility to make copies of the DST tapes for
distribution by Express mail. For smaller sets of data we will also rely
upon distribution over the network. Reliable network connections will also
be important for distribution of programs and databases.