Experiment 896:
A search for short-lived composite strange matter.
The E896 experiment is a search for the H0 dibaryon that may be produced in Au-Au collisions at 11 GeV/nucleon. The H0 is the lightest example
of strange matter, a neutral particle consisting of 6 quarks; specifically 2 up, 2 down, and 2 strange particles. We investigate production from the AuAu
system because we know that a typical central collision produces more than 20 hyperons in a very limited phase space, thereby opening a coalescence
channel for the production of the H. We are searching for evidence of this new type of particle by analyzing weak decays into charged daughter products
(e.g. H0-> S + p) in a large multi-plane drift chamber. For our analysis, the neutral decay vertex must be within the drift chamber fiducial volume.
E896 completed its first data taking run in May 1998. Over 100 million central Au-Au events were recorded during that period. Using arguments outlined in
the original proposal, this data set is expected to yield one million Kshort, one million L, 10,000 di-L, and theoretically (based on L coalescence) 50 H0
particles. Analysis is currently underway to cull the events containing those particles from the data set. At this time a first pass through all the data has
been completed. A filter program tuned to identify V’s produced by L decays was implemented during this pass. This first pass filter, which should also be
sensitive to H0 decay products, was determined to be running with a 10% efficiency. The resultant set of 200K "V-rich" events is currently being scrutinized
using different track reconstruction codes for clear evidence of the H0 particle’s existence. Meanwhile, attempts to increase the efficiency of the filtering
codes is progressing, as is the development of code for a second pass through the data to determine the values of several calibration constants needed for
the analysis of the different detectors used in the experiment. This second pass is expected to begin in late September, with a possible third data pass using
improved filters anticipated during the coming winter.
|
