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Update on HBD Monte Carlo

Update on HBD Monte Carlo. I. Ravinovich for Weizmann group. What has been done. Improved pattern recognition algorithm Fix at the PISA level the problem with missing tracks hitting the G10 frames New version of the event display – many thanks to Susumu Oda from CNS, Tokyo

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Update on HBD Monte Carlo

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  1. Update on HBD Monte Carlo I. Ravinovich for Weizmann group I. Ravinovich

  2. What has been done • Improved pattern recognition algorithm • Fix at the PISA level the problem with missing tracks hitting the G10 frames • New version of the event display – many thanks to Susumu Oda from CNS, Tokyo • New set of PISA hits files using central (< 2 fm) HIJING events, up to now ~70K events • Reconstruct pure HIJING and HIJING merged with f->e+e- events • Efficiency versus rejection study I. Ravinovich

  3. Pattern recognition • Pad threshold > 1.6 fC (1 p.e.) • Pad size a=16.7 mm • Number of pads 1368 • Remove 1 pad clusters • Split the cluster if there is more than one local maximum • Cluster charge > 32 fC (20 p.e.) • Calculate the center of gravity • Prepare the list of the clusters for global tracking code • Project DC track to HBD • Search for the closest partner • Add HBD hits to the node ‘PHCentralTrack’ (nDST) I. Ravinovich

  4. Why do we call it HBD? I. Ravinovich

  5. Combinatorial background • Rejection consists of 4 steps: • Central Arm electron ID • 3s momentum dependent matching to HBD • Pile-up rejection – double amplitude cut (96 fC, 60 p.e.) • Close hit cut – 200 mrad • Rejection has been studied in 5 mass windows • Above mee > 200 MeV/c2 the rejection factor > 100 I. Ravinovich

  6. Signal from f->e+e- • 4 steps as explained in previous slide • All variables shown are relative to the Central Arm • After matching signal drops to 0.74 which means we loose 14% tracks: • ~9% losses are due to cluster size and amplitude cuts. These are mainly tracks hitting G10 frames, can be treated differently and recovered • ~1% losses: tracks which do not enter HBD but bent into the Central Arms • ~4% losses are not yet understood, needs further investigation • After double amplitude cut the signal drops to 0.56. There is room to improve this number too • After close hit cut the signal drops to 0.42, very close to what we have written in the proposal • Rejection factor is above 300 I. Ravinovich

  7. Next steps • Better understanding of the losses • Improve the efficiency where this is possible • Run with decreased QE • Run sample HIJING events without HBD to quantify the background coming from HBD materials • Build the prototype … • Build the detector … I. Ravinovich

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