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MDC4 Reconstruction

MDC4 Reconstruction. Good news Relatively stable/smooth operation of software Things which were expected to break did not New stuff put in recently performed well Bad news We still lack a detailed look at things Some issues remain to be resolved But it is doable

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MDC4 Reconstruction

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  1. MDC4 Reconstruction • Good news • Relatively stable/smooth operation of software • Things which were expected to break did not • New stuff put in recently performed well • Bad news • We still lack a detailed look at things • Some issues remain to be resolved • But it is doable • Calibrations cannot be tested here but knowledge accumulates S. Margetis

  2. New Reconstruction Software • (Beyond detector level) • TPC-SVT matcher (EST) in place • It works nicely (even with only 3-SVT layers) • Needs some tuning (secondaries) • Primary (pseudo) Kalman fit • Used for first time on large production in MDC4 !! • Looks similar to year-1, as expected • Open issues still remain but all doable S. Margetis

  3. New Reconstruction Software (2) • EVR upgrades • Better efficiency/better vertex at low multiplicity • Some minor issues should be discussed/resolved • “global” handshaking • Needed careful coordination • Still needs work on alignment (transforms?) with data • Stability is near but not here! S. Margetis

  4. EVR updates (by L.Ray) • Bottom line is • Details in /protected/reco/ray/evr_testresults_April2001.html • New low multiplicity efficiency is factor of 2 up but it still misses a lot of good events • We might have to re-install LMV even if it overdoes it • Peripheral group needs these events • Heavy Ion users should use carefully events with <20 primaries • Use of beam position knowledge keeps x,y reco sigmas almost flat over all multiplicities • This is an optional switch S. Margetis

  5. EVR updates (2) • For MDC4 resolution is as expected ~50um • Issues (EVR is the messenger, do not shoot him!) • S-shape of reconstructed vertex z-position • This is a recent feature • It shows up in simulations, not ‘calibration’ • Not clear origin but closing down • LMV reinstallation S. Margetis

  6. New Primary Fit (A. Saulys, W. Deng) • First time in large production in MDC4 • Identical so far for year-1/year-2 • Kalman propagation to vertex neighborhood • Constrained fit to vertex • ‘GEANT’-look up of material/energy loss • Not yet implemented for global tracks in year-2 • But in the works together with use of dE/dx info S. Margetis

  7. New Primary Fit (2) • It is not a miracle performer but • It does a better job than the one before • Energy loss seems to be corrected • Chi2 peaks around 0.9 for data at best • It peaks around 0.7 for TRS simulations • Momentum resolution trends as expected. S. Margetis

  8. New Primary Fit (3) • Issues • TRS/Data chi2 needs to be resolved • Hit error systematics might have to be revisited again after all calibrations are done • Use dE/dx info in both years (coming) • Extend ‘GEANT’ trick to account for SVT in global S. Margetis

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