E895 Meeting Minutes at LBNL

taken by Dieter Best

May 27th 1997

• Attending: Gulshan Rai (GR), Nathan Stone (NS), Dieter Best (DB), Heng Liu (HL), James Symons (JS), Mark Gilkes (MG), Sergey Panitkin (SP), Grazyna Odyniec (GO), Daniel Cebra (DC), Bill Caskey (BC)

• Davis
  • reports about problems running eosgx on their HPs, not enough memory, bus error.
  • wants to run on VMS too, DC takes care of that.
  • Recommendationfor Davis: get newest TAS3 code.
• NS
  • We have problems running with the 2D hit finder too, work on that.
  • The dE/dx resolution for the new track finder (btf) using the 1D hit finder is much better. No pictures or quantitative statement yet.
• DB on status of track finder
  • btf has been released (release 1.0) and is in CVS.
  • btf_sw are in CVS.
  • Using the 1D hit finder, with the hit removal efficiency is higher, npts/track is higher, time consumption much smaller than with jtf.
  • No decent FSIM or even DSIM studies with btf (question from GO).
  • The method used in btf is the same as in jtf, Kalman Filter.
• DB on status of vertex finder software
  • What is vertex finding:
    • Find primary vertex (PV)
    • find decays (V0s)
  • Why vertex finding:
    • include PV in trk fit results in sqrt(2) better p resolution
    • physcis of Lambda, K0s, gamma, pi0, Xi-, Omega-, phi mesons ..
  • Status of our VF software:
    • PV not satisfactory
    • V0 software from Marvin does not work in our environment
    • No Xi-, Omega- software
    • Neural network of Marvin not touched yet.
  • Solution:
    • forget old software
    • new software IS available
  • Advantages of this solution:
    • A lot of work and time to fix and understand the old software
    • Marvin says, use NN, but so far as I can tell, not the best has been done with the classic methods.
    • Used already my V0 software to find the Lambdas, since old software doesn't work in TAS3.
    • Used PV software to get better PV, since PV on dsts was not good enough.
    • It is possible to determine vertex in pass2
    • refitting of tracks with vertex possible with track information only, not hit information necessary. Therefore no vertexing necessary in pass1, remove PV finder in pass1, pass1 only hit and track finding.
    • Refitting of tracks to PV in pass1 bad for those who want to look for decays, this old battle whether refitting should be done in pass1 or not is over, since now a doftware is available which can make refitting without hit information. No need to track data twice, namely with and without refitting.