Version 1.0
March 1, 1994
Mike Strauss



This memo describes the new mini-DST created for SLD data analysis. While designing the mini-DST, the committee had two primary goals. (1) To get all Data and M.C. on VAX disks. To do this, we have tried to keep the data to about 10 kbytes per event, and the Monte Carlo to about 20 kbytes per event. (2) To keep enough information in the DST to allow most members of the collaboration to do physics analysis from the mini-DST. The purpose of the mini-DST is not for checking reconstruction, recalculating particle energies, momentums, or particle types. It is to do physics analysis.

We appreciate all of the input we have received from the various physics working groups and various individuals in designing this mini-DST. A flow chart of the new mini-DST is shown in Figure 1. This figure also shows the relationship of the mini- DST to the Monte Carlo Banks and to some of the original DST. Currently, no CRID banks have been designed into the mini-DST.

Structure of the Mini-DST

The mini-DST structure retains the structure of the original DST (see figure). In all cases we have given new names to banks which replace old banks. In some cases, new banks were created because the old banks were inadequate or poorly designed for physics analysis. In other cases, new banks were developed because the old banks contained more information than was necessary for physics analysis.

A brief description of the new mini-DST banks is given below. For each bank, we have indicate its function, and how it differs from the original DST bank which it replaces. See the actual templates for more detailed descriptions of its contents.


This bank serves as a header for the mini-DST. It replaces PHHEAD and contains only pointers.


Contains information about the global event classification. It partially replaces PHCLASS (see Section 3 below for more information on event shapes and PHCLASS).


Contains information about the initial beam polarization and energy. Replaces PHBEAM.


Particle summary bank. Contains four momentum, starting position, and charge for all particles. This bank along with PHPOINT replaces PHPART. One bank per particle. PHPSUM may be an excellent bank to use as a micro-DST or as a starting point for a micro-DST since it contains crucial information regarding the particle and since it has only one extraneous pointer per bank.


Pointers to other banks containing information on this particle. (See PHPSUM).


Contains information about the charged tracks compiled from ZXTRKS, PHDC, and PHDCV. Replaces PHTRK, PHDC, and PHDCV. One bank per charged track.


Replaces PHKAL. Only has specific information from entire cluster and electromagnetic layers. Specific information from hadronic layers is no longer stored. One bank per Kalorimeter cluster.


Relational table relating PHKLUS clusters with PHCHRG tracks.


Electron identification for PHCHRG banks. One bank per charged track.


Muon identification for PHCHRG banks. One bank for each identified muon.

Using the Mini-DST

The Mini-DST on disk or tape consists of all the banks in Figure 1 categorized as "Monte Carlo banks," and those not included in any specified section in that figure. It does not include the banks in the section labeled "Original Track DST." Those banks are on the original DST and cannot be retrieved from the Mini-DST. To do physics analysis, one uses the unspecified banks and the "Monte Carlo" banks in Figure 1.

The other category of banks delineated in Figure 1 are "Jet/Shape Finding" banks. These banks are not on the Mini-DST, but are created by the user when the user wants to find jets. To do so, one must poke the appropriate parameters in JETFNDP. One may also set the CUTFLAG bit of the STATUS word in PHCHRG, PHKLUS or PHPSUM, depending on the input to the jet finder. The CUTFLAG bit is set if one does not want to use a specific bank. For instance, when finding jets using PHCHRG banks, one may decide not to use PHCHRG(1). If so, one would set the CUTFLAG bit of PHCHRG(1).STATUS on. All PHCHRG banks would be used by the jet finder, except PHCHRG(1). Whenever one calls JETFND (the jet finder), after making the appropriate pokes to JETFNDP, the output banks PHJETA, PHJET, and PHJTPT will be created. These are user specific banks based on the cuts and inputs defined by the user. Similarly, the processor used for calculating event shapes including sphericity or thrust is PHSHAP. To use PHSHAP, one sets the appropriate STATUS bits in the particle banks, and pokes the appropriate parameters in PHSHAPP. The output of PHSHAP is a newly created bank, PHCLASS. Like the jet finding banks, these are banks specific to the set of user defined cuts and parameters.