sPHENIX tracking discussion

[Anthony Frawley <afrawley AT fsu.edu>]

Hi All,

In pp running we will want to keep track of bunch crossing number for every track. At the least, we need to know if the track was in an event that is fully contained in the TPC.

We could either:

a) add a signed int to the track object.

b) add a signed int to the vertex object.

In case b), the bunch crossing would have to be kept in a map on the node tree for all tracks, so that the final vertexer could look it up and add it to the vertex object.

Case b) would use less disk space. But it would possibly be more of a pain for analyzers to have to look up which vertex a track belongs to, and get the bunch crossing from that.

On the other hand, perhaps all analyses will proceed vertex by vertex anyway, in which case, b) would be convenient enough.

For context, a pp event with 7 microseconds additional readout time will have ~ 15-20 vertices from events fully contained in the TPC. These will be distributed over ~ 70 bunch crossings.

Thoughts?

Tony