sPHENIX tracking discussion

[Anthony Frawley <afrawley AT fsu.edu>]

Hi All,

We had a discussion in the tracking software meeting this morning about what should be put in the data stream by each of the tracking detectors to forward the needed information to the track reconstruction code. Here is a brief summary of the results:

We picture three stages:

1. An intermediate file is written by each subsystem.
2. An "event builder" picks up the intermediate files and creates an event-based file.
3. The event-based file is read into Fun4All and tracks are reconstructed.

The primary goal today was to define what must be in the intermediate files, stage 1 above. For a discussion of step 2 we need other experts present. The general expectation is that there will be an event header for each assembled event that contains (at least) the GL1 trigger word and the full BCO times for each subsystem. Then the relative time offsets can be put in the hitset key for each subsystem.

For triggered data:

-------------------------

MVTX (Yasser):

GL1 trigger time

Full BCO start time for each strobe

Hitsets for each strobe

(The event header created later will contain the full GL1 and BCO times)

INTT (Joseph B):

GL1 trigger time

Full BCO time

Hitsets for each BCO

7 bit offset from GL1 time and address of hit in the hitset key

(The event header created later will contain the full GL1 and BCO times)

TPC (Jin and Takao):

GL1 trigger word

BCO start of time frame

Hitsets

TPOT (Hugo):

(Just like TPC in triggered mode)

GL1 trigger word

BCO start of time frame

Hitsets (Hugo: one hit will be selected from the time stream and kept).

There may be a need for changes to the hitset key structure by each subsystem. This should be made as a proposal and discussed beforehand, since there is potential for disruption when changing these.

The question was asked "who implements the event header?". We will look at what is available in the Fun4All framework as a starting point.

If I got anything wrong, please comment to the list.

Cheers

Tony