SLD Primer

Welcome to SLD! This primer is intended to point you in the right directions for getting started on analyzing SLD data.

If the information you want isn't here, and you find out how to do it, please write it up and send it to me, and I'll add it to the Primer.

Contents

Introduction

The organization of this primer is based on the OPAL Primer (version 2.0 1/94) from S.L.Lloyd.

It is intended to give the new SLD collaborator enough pointers to allow him to start analyzing SLD data. The descriptions of code and utilities are usually available to everyone with the standard SLD environment as supplied by DUCS, both at SLAC and home institutions. Descriptions of availability of data will be restricted to SLAC.

Computers for SLD Analysis

SLD computing at SLAC is available on 4 platforms: DEC VAX and Alpha VMS; IBM VM and IBM RS6000 UNIX. The full SLD environment is supported on VMS and VM, while UNIX use is restricted to CERN's PAW.

The DEC hardware consists of Alphas, VAXstation 4000s and a VAX 9000. See the VMS usage guide for details.

The SLAC IBM 9000 represents the VM component, while UNIX work is done on ancient IBM RS6000 320's in SLD's control, currently the Ravel, Dali and Bach workstations. Disk space for PAW ntuples is available (on a sign-up basis) on a local disk on Ravel (/nfs/ravel/u1 partition).

Account access to these machines is available by filling out a new user form, getting it signed by one of Richard Dubois, Terry Schalk, or Karen Heidenreich and returning it to the SCS Service Desk.

Analysis Environment & Tools

Analysis of SLD data revolves around our (home-grown) data manager, Jazelle (SLAC report 263, similar in concept to CERN's Zebra), and event processor/presentation utility, IDA (viz CERN's PAW).

IDA gives an integrated environment for event processing, with or without its interpretive IDAL language, event display, Jazelle browsing and histogram (via SLAC's Handypak - SLAC report 234) manipulation.

SLAC's Mortran is used as a Fortran pre-processor for compiled code, which have filetype PREPMORT.

The single event display is callable from IDA and can be used for 2-d and 3-d viewing of events. It uses SLAC's UG package for underlying graphics.

There is a useful set of examples on SLACVM which form a self-guided tutorial. Try HELP EXAMPLES.

The analysis environments differ on each platform:

VMS

For line mode use, the IDA command will get you going. On an X-capable terminal, MIDAS is much nicer for interactive work. Both make use of shareables, which are pre-linked executables for each major subset of the code.

To get started in the SLD environment, copy DUCSROOT:[UTIL]LOGIN.COM to your home directory. This will set you up with SLD logicals, news and so on.

VM

The SANE job prep system handles turning your wishes into executable desires. It is used both for interactive and batch jobs, with interactive using WJOB for a full screen interface. Use HELP SANE and HELP WJOB on VM.

To get started in the SLD environment, contact Karen Heidenreich to set up your PROFILE EXEC and other standard EXECs.

UNIX

The general SLD offline system currently only runs on VMS and VM. Use of UNIX is restricted to CERN's PAW. Ntuples are converted from Jazzdata files created either on VMS or VM, as described in the SLD PAW description.

Physics Utilities

The following utility packages are available for physics analysis:

Each of these processors has a parameter bank (of name processor-name with 'P' appended) containing the modifiable parameters for the utility.

Access to SLD Data

Data comes in several varieties (all of it in Jazelle format):

Raw Data from the Detector

See ACQ DATACAT for a correspondence of data run numbers to tapes. For example, ACQ23271 would give you the tape for run 23271. This datacat contains the latest data. See ACQ*.DATACAT in DUCSDATACAT for older data.

These ACQ tapes are copied to IBM format and are listed in RAW.DATACAT. During the run, these tapes are cycled out of the silo; at any given time, only about 3 weeks' worth of ACQ and RAW tapes are available.

Policy for Getting Access to Raw Tapes on the Racks

If you need to have raw tapes put back in the silo, the technique for doing that is: These tapes will be in the silo for a restricted period of time to be negotiated with Karen based on pressure for silo slots.

Output from the Pass1 Process

Pass1 filters off the wheat from the raw trigger chaff. 1/30th of the triggers survived the '93 Pass1. Several calibration streams were also emitted from Pass1.

The physics filters' output for the '93 data can be found in DUCSDATACAT:HAD.DATACAT.

The '92 energy-filter dataset can be found as TAUSEL in TAU DATACAT on TONYJ 191 on SLACVM.

Pass2 output

Pass2 is a reconstruction of all the physics filter output from Pass1. See RECON.DATACAT for a list of tapes. Note that this is not a physics-ready version of the reconstruction.

Versions of Reconstructed Data

Re-reconstructions of the data are performed with frozen copies of the production code. These are also performed on all events passing the PASS1 physics filters.

The most recent versions of the reconstruction are: 

   data		code version	DST datacat     	miniDST datacats
   ---------    ------------    -----------  ---------------------------------
   
   '92           11.1		REC92        MDSTV3 (tape)  diskmdst2(VMS disk)
   '93		 11.1		REC93        MDSTV3 (tape)  diskmdst2(VMS disk)

Monte Carlo Simulations

MC simulations created on the SLD farm at SLAC are described by .TASK files in SLACVX::[SLDMCM].

There is no current MC corresponding to the most recent reconstruction of '92 data.

Most recent MC for the '93 data can be found on the MC processing page. There is a .DATACAT file for each .TASK. The miniDST on tape for the MC300K_* datasets can be found in DUCSDATACAT:MDSTV3.DATACAT. The VMS disk datacat is in diskmdst2. The other datasets have not been skimmed to make a miniDST.

Exporting SLD Data

Export of data is the responsibility of the exporter, ie SLD does not operate a data export service.

The currently most popular (though despised) method of export is on 8mm tape. The practicalities of this mode of copy is under scrutiny as of this writing.

An alternative for those blessed with a cartridge silo is to copy the tapes directly in the SLAC silo to user-supplied cartridges which are sent offsite.

SLD Information

Organization

SLD is ably led by its two co-spokesmen, Marty Breidenbach and Charlie Baltay. SLD's Administrative Assistant, Barbara Barrera, makes it all happen.

Day-to-day operation of the experiment is in the hands of the SLD Commissioner, a rotating post turned over approximately yearly. The current commissioner is Terry Schalk, whose term began in mid-August, 1994.

The spokesmen solicit advice from their Advisory Group, composed of

Physics analysis is coordinated by three working groups: Heavy Flavours, Electroweak and QCD.

Heavy Flavours

Led by Rafe Schindler and Su Dong, this group has weekly meetings on Thursdays at 2pm in the SLAC Group A conference in CLA.

Electroweak

Led by Peter Rowson and Morris Swartz, this group has weekly meetings on Wednesdays at 4:30pm in the SLAC Group A conference in CLA.

QCD

Led by Phil Burrows and Dave Muller, this group has weekly meetings on Fridays at 10am in the SLAC Group C conference in CLA.

There is a coordinating committee for the PWG's which also includes the spokesmen, the working group leaders and Richard Dubois, Tony Johnson and Uriel Nauenberg.

This group allocates talks and seminars, adjudicates contention for the MC Farm and generally oversees the operation of the physics analysis.

Software Support

Software support at SLAC comes primarily from the Software Group .

We have created a list of maintainers for various areas in the offline. You can refer queries to them.

R.Dubois 8 May 1994