File : user_evnt.F (RECON)

c
c change to the lambda subdirectory
c

call hcdir('//PAWC/LMON',' ')

call pe_sbarrow()

c
c change back to top directory
c

call hcdir('//PAWC',' ')
call hcdir('//LUN1',' ')

The above code handles the processing of the lambdas by calling the procedure pe_sbarrow(). This procedure name is essentially an abbreviation for "process event (Steve Barrow's code)." Involved with this code is the procedure "pl_1520_sbarrow()" which is more specific code for the lambdas. Again, the abbreviation as such is for "process lambda 1520 particles (Steve Barrow's code)." The processed lambda events are also entered into histograms, which are 'booked' in a process called bh_sbarrow() in the same code as processevent. The abbreviation in this case stands for "book histograms (Steve Barrow's software)." This section of Barrow's code is called in the user_init.F file of RECON.

File : user_init.F (RECON)

c
c lambda 1520 analysis.
c

call hcdir('//LUN1',' ')
call hmdir('LMON',' ')
call hcdir('//PAWC',' ')
call hmdir('LMON','S')

call bh_sbarrow()

c
c go back to the top directory.
c

call hcdir('//PAWC',' ')
call hcdir('//LUN1',' ')

The links in the previous section of my text both link to the full 'C' code used (authored by Steve Barrow) in the incorporation. Once this was accomplished, and all the bugs were worked out of the code, the software was run with the following input files:

CELEG : ftn15
GSIM : gsimbat.csh , gsimbat.ffread
RECON : recon.tcl

Although many difficulties were encountered, involving mistkaes obvious and otherwise, some decent results were obtained towards the end of the summer. These results can be examined in the form of histograms and actual events as viewed by CED, an event display program for the CLAS. Below are some links to these data that will give some indication as to the general goals of the research, both in terms of the software and the overall physics-oriented goals.


PAW Histograms:

Lambda (lmon) Histogram:

M versus phi, proton tracks (lmon 2)

Track (trkmon) Histograms:

Number of Tracks (trkmon 100)
W (GeV), S1 (trkmon 105)
Q2 - W, S1, Run 1 (trkmon 109)


The above histograms give a general overview of some of the resulting data from the integration of the Fortran and 'C' codes. In histogram lmon 2, one can see, although not very clearly, some less than informative results from the lambda analysis. The results in this category were somewhat outside the scope of research this summer, in that I didn't have much of a chance to manipulate the software for specifically lambda event processing.

Histogram trkmon 100 gives a typical output of the number of tracks seen in a particular event. As can be observed, the software was modified to the point that approximately 50% of the events contained tracks (~500/1000.) Histogram trkmon 105 gives some information about the W (GeV) values detected in the events with tracks, and a distinct peak at ~2 GeV can be clearly seen. This peak corresponds to the lambda (1520) particle (actually a lambda and a kaon.) This histogram represents the first sector only of the CLAS detector, but is representative of the data obtained in the other sectors as well. The last histogram, trkmon 109, is a Q^2 versus W relationship for the lambda events, again, for the first sector only. However, this is also fairly representative of the data in the other sectors as well.

The actual events can be viewed with CED, and several events can be observed with the links below. The curvature of the tracks, therein, is the result of the toroidal magnets in the CLAS that bend the tracks of charged particles, which assists in their identification.

Event Simulation: Some Example Events

Event Example 1
Event Example 2
Event Example 3


These above event examples illustrate some very clear, clean tracks and some typical results in the CLAS detector. The first two examples depict some usual two track events, whereas the third example shows a 'funkier' event with three tracks.

This essentially covers the general purpose and results of this summer's research work. The software in the waning moments of my summer experience is in a 'decent' condition, with (likely) most of the bugs worked out. Although, surely, there are a few more slight problems that need to be solved, the work has been generally successful, despite a somewhat slow rate of progress. The next section on my research page provides a brief overview of the relevant information for a general (and minimal) understanding of the background information.

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