PHYSICS APPLICATIONS

L3 MC and Data Processing

L3 uses GEANT. They maintain their own copy, which they keep frozen for up to a year at a time. They try to not get more than a year behind the current CERN version.

It takes about 3 months after taking the data for them to derive the constants. Reconstruction is done on Apollo DN10000 workstations connected to their IBM 3090 by a channel-VME interface. The recon output is streamed three ways RECON: DST:miniDST at 200:20:3 kB/evt.

Data quality monitoring is handled by a single person at a time during the run. The feedback from reconstruction takes about 2 days to get back to the experiment.

About 1/2 of the group uses PAW for analysis. The COMIS facility is thought to be slow and too buggy to depend on for final analyses, which are performed with compiled code.

They do not have a very good handle on how they use their disk space (cf D0 in our FNAL trip report).

ALEPH Event Display Graphics - Hans Drevermann

We discussed his 2d event display package, DALI. Notable features are the 'v-plot' for showing 3d effects of tracking information in a 2d plot and a novel method for mapping 3d structures like projective towers of a luminosity monitor onto 2d. He has also studied optimal use of colours and colour combinations, and compression of scale dimensions. These are all reported in lectures he gave at a recent CERN summer school on computing.

He suggested we try using a plot of phi vs theta for looking at CRID data. A ring from the liquid would appear as a vertical line.

CERN CN Applications

GEANT version 3.17 is expected to be 2x faster than its predecessor due to improvements in the geometry optimization, which will become automatic in that version.

They are looking into shareables for UNIX plus dynamic loading. This is intended for people, once they are happy with their COMIS macro file, to compile them, link them in interactively and run the faster, compiled code on their ntuples. This is being developed for HP so far.

Tony Osborne wanted to make it clear to us that CERN CN is not an infinite source of manpower and, that if we wanted features, etc from them, we would be expected to contribute by collaborating on projects.