Recon 12 Description

Here is a compendium of descriptions of RECON 12 from the various subsystems:

Summary of Changes in Tracking between R11 and R12 Su Dong

VXD Hit arbitration was effectively turned off by accident for all R11 production of data and MC. This happened when the tracking framework was upgraded to generate PHCHRG bank for MiniDST. This has been corrected to turn on the VXD hit arbitration for R12 production. The main effect of the VXD hit arbitration is to demote ~2% of the tracks (mostly strange decay and interaction product) mislinked to wrong VXD hits back to CDC alone tracks.
R11 PHCHRG bank 3D impact parameter values (IMPACT3,B3NORM) were filled using obsolete old code in PROD ZXFIND which could not cope with none (0,0) IP, i.e. doesn't work for data, and also has improper error estmate. R12 will use the proper calculations from ZX3HEL routine with correct handling of IP for both the impact parameter and its error estimates.
R11 data reconstruction was done with a crude version of IP constant and the track parameters were recalculated to make the exsiting MiniDST with a post processing after the final IP constants were available. For one period of data (early 94 fall), the event by event IP Z recalculation in the post processing were mysteriously missing/wrong such that the IP Z had a 140 micron additional spread for that period. The R12 recon is done with the final IP constant with no post processing for tracking.

Summary of Other Global Changes between R11 and R12

The MC PHEVCL.CDCSTAT word VETO bit definition for R11 was accidentally flipped so that VETO bit set actually meant READSLD i.e. event is triggered and readout (only relevant for MC of course). We changed this back for R12 with VETO bit set actually mean ``VETO'' i.e. no readout.
To allow more detailed studies of trigger simulation, the R12 MC DST/MDST IEVENTH.TRIGGER word is filled with both the slot and evaluator information. Slots=bit 0-15; Evaluator=bit 16-31; The R11 trigger word only had the slot information.
To allow more detailed accessment of the data trigger information, the data R12 recon included MA_BEL bank in DST output and a decision is still to be made as to whether also including it in MDST.

Summary of Changes in CRID between R11 and R12 Tom Pavel

Improvements to the data include:

new internal TPC alignment
discovered 1 dead and 1 "weak" TPC
discovered 9 dead mirrors
new TPC alignment
new liquid radiator alignment
new individual mirror alignment
studies of the photon yield and Cherenkov angles in individual TPCs, and as a function of theta, phi, and time
a review of the track quality cuts yielding more `good i.d.' tracks from the gas system
fixed a bug in applying crosstalk cut across WSM boundaries

MC upgrades:

now models (run-dependent) dead boxes and photon efficiency vs. TPC and cos theta.
also models bad mirrors as in data
MIP simulation improved
- produce blob of electrons and transport/diffuse each one. Now simulates the length and width of saturated pulses fairly well.
- model photon feedback and delta rays
- loss of hits via crosstalk cut and overlapping with MIP pulse
- reproduces MIPMATCH, GASMESS, GASISO cuts
Allows for MC reprocessing (generate extra hits in MC-gen, toss in "recon" stage to match empirical distributions.

Summary of Changes in KAL between R11 and R12 Eric Vella

The fast electromagnetic shower parametrization used in the standard Monte Carlo was changed to improve the longitudinal shower shape for medium energy EM showers. Both single electrons and the overall energy in Z events showed too small an EM1/(EM1+EM2) ratio in the MC, compared to real data. The depth profile of the parametrized EM showers was shortened to make the showers deposit energy earlier in the calorimeter.

The EM shower simulation is based on the GFLASH parametrization, which describes the shower shape using two parameters, alpha and beta. Shower maximum occurs at a depth (in radiation lengths) given by (alpha-1)/beta. The parameter alpha was changed as follows:

  R11 simulation:  alpha = 2.74 + 0.53 * ln(E/GeV)
  R12 simulation:  alpha = 2.32 + 0.64 * ln(E/GeV)

Note that the new parameter is significantly smaller at low energy, but matches the old parameter for Bhabha electrons, where the simulation was already known to be good.

The shower parameters reside in bank KFSH1P and were set to their new values via file kreretune.ida, in the following lines:

 Poke KFSH1P.emshow(1).alpha(1) = 2.32   ! previous MC prod 2.74
 Poke KFSH1P.emshow(1).alpha(2) = 0.64   ! previous MC prod 0.53

Code Patches to Frozen R12 (version 12.1) after creation Richard Dubois

RECONSHR.EXE;30       7-DEC-1995 07:49:12.13
TRKREC.PREPMORT;5     7-DEC-1995 07:44:03.75
ZX3HEL.MORTFORT;1     7-DEC-1995 17:43:15.60
ZXFILL.PREPMORT;3     7-DEC-1995 15:52:57.48
ZXFINDSHR.EXE;22      7-DEC-1995 17:44:34.28
DEGHLV.CONSTANT;1    25-JAN-1996 11:28:26.04


 Data re-reconstruction was performed using 12.1 PLUS DEV CRID from 12.2
to get the latest tunes. MC CRID re-reconstruction is done with DEV CRID
in 12.2.



R.Dubois 2 Feb 1996