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Simulation issue

Simulation issue. Y. Akiba. Main goals stated in LOI. Measurement of charm and beauty using DCA in barrel c  e + X D  K p , K pp , etc b  e + X B  J/ y  ee Measurement of Jets in barrel Reconstruction of “jets” from charged tracks in barrel

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Simulation issue

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  1. Simulation issue Y. Akiba

  2. Main goals stated in LOI • Measurement of charm and beauty using DCA in barrel • c e + X • D  Kp, Kpp, etc • b  e + X • B  J/y  ee • Measurement of Jets in barrel • Reconstruction of “jets” from charged tracks in barrel • Measurement of charm and beauty using DCA in end-cap • c m+ X • b  m + X • B  J/y  mm • Physics goals • Au+Au: Probing hot dense matter using heavy quarks • d+Au: Measurement of gluon shadowing in small x • p+p: Measurement of DG(x) in wide x range

  3. Strawman Design • 1.5% X/X0 per layer • b) 1st layer as close to beam-pipe as possible • c) rely on PHENIX central + muon arms for PID, momentum • d) 4 layers => accurate, redundant DCA

  4. Critical Questions • How much conversion background the Si detector will generate to the central arm? • Effects on LVL1 trigger on p+p • “thick converter” data in RUN-3 may give the answer • Effects on offline analysis • RICH occupancy • Single electron background • Di-electron background • How well “external tracks” can be connected to the tracks in SVT • Central arm track to SVT barrel • Muon arm track to SVT end-cap • Purity of charm/beauty candidates with DCA cuts • purity has a major impact how well DG(x) can be measured • How effective DCA cuts for a given beam spot size • Present beam spot size of RHIC sx ~ sy ~ 500m. This is larger or comparable to ct of D0(123m), D+(315m), B0(462m), and B+(502m). • Beam size in RHIC-II will be smaller (s ~ 150 m?) These questions should be answered at least by very realistic simulation

  5. Background issue • Effective radiation length in present PHENIX: • 0.8%(Dalitz)+0.3%(beam pipe)+1%(MVD) = 2.1% • 1.1 % without MVD (a possible configuration in RUN-4) • Effective radiation length with SVT • 0.8%(Dalitz)+0.3%(beam pipe)+4×1.5%(Si)+0.3%(?)(Enclosure)=7.4% • 1.4 to 1.8 % if conversion electron in the SVT is removed by requiring a hit in the inner-most layer of the SVT. • Here I assume that Si sensor part is placed in the inner half of the Si layer. • Unique association of electron track and SVT track is required • If the conversion in the SVT are not removed by offiline  • Combinatorial background of di-electron pairs will increase by a factor of > 10. This will makes low mass measurement impossible, and this will seriously compromise the measurement of J/Y and y(2S) in the most central collision. • The background can conflict another upgrade plan (TPC+HBD) This question of the conversion background should be clarified in CDR

  6. Example: impact on J/Y • RUN-2 Au+Au (0-20%) (7/mb of data) • Background: ~40 counts • Signal: < 10 (90%CL) • Expected signal is 10% to 70% of the upper limit. See left plot • Au+AuJ/Yee in RUN-4 • ~300 /ub in RUN-4 • Combinatorial Background can be reduced by 50% with narrower mass cut  Background: ~ 900 (with narrow mass cut) Signal: <40 (QGP suppression) ~270 (statistical model) • PHENIX very likely wants to continue J/Y measurement beyond RUN-4. If conversion from SVT is not removed, this measurement becomes very difficult. • It is important to demonstrate that the background from SVT does not compromise the J/Y measurement

  7. What are needed to be done • Realistic implementation of SVT geometry and material in PISA • Implementation of SVT response chain in PISA • Efficiency • Noise level • Local track reconstruction code for simulated SVT • Global tracking (SVT track  DC track (PHENIX reco track)) • New simulation reconstruction code should be implemented as a new classes of PHENIX reconstruction code • Simulation study of • Full Hijing event or parameterized Au+Au event • p+p event • with realistic vertex distribution (sr ~ 500 m, sz ~ 30 cm) • Study of • Reconstruction efficiency • Di-electron background (after SVT tracking) • DCA resolution • Purity of charm/beauty track candidate • “Jet” reconstruction in SVT

  8. passive components 290µm 150 to 200µm PIXELS DETECTOR READOUT CHIP 150 to 200µm cooling carbon fiber support More detaled list • Structures like shown in the right should be implemented in PISA • New “GHIT” from SVT (one each for Si pixel, Si strip, and Si end cap) • New class in response chain that produces new (calibrated) “HIT” from “GHIT” and relation table between them for Si pixel, Si strip, and Si end-cap • Geometry objects that describes SVT geometry in reco chain • SVT barrel local tracking class (barrel HIT  barrel track) • Barrel track  central arm track global tracking class • SVT end cap local tracking class (end cap HIT  end cap track) • End cap track  muon track global tracking class • All code should be implemented in the current framework of PISA and PHENIX reconstruction/analysis chain

  9. Very rough estimates of man-power and time • Man power need for software development • PISA geometry implementation: 1 to 2 man month (dedicated) • PISA response chain: 1 to 2 man month (dedicated) • SVT local tracking and Global tracking • Barrel + central tracks: 2-3 man months minimum • End-cap + muon arm track: 2-3 man months minimum • Need volunteer for the work: • 1-2 person for PISA geometry + response chain • 1-2 person each for tracking for (barrel+central) and (end-cap+muon) • 1 Coordinator of the effort • If we start strong effort on the simulation/reconstruction project, the first version of software can be available by end of summer • Simulation production RUN (>1 month, in Fall 2003?) • 100K Au+Au central events (10 min/event?)  1 weeks x 100 CPU • 100K Au+Au min. bias events (3 min/event?)  a few days x 100 CPU • 1M p+p charm/beauty events • Real time can be longer by factor 2 to 3 • Analysis of fully simulated events (>1 months. Fall to winter 2003)

  10. Summary • There are several, unanswered, critical questions on SVT • Performance in central Au+Au collisions • Conversion background and its influence to electron pair measurement • Compatibility with TPC/HBD project • They needed to be answered (at least) by a very realistic simulation and reconstruction of the simulated data. • This is a major effort, and requires > half year of concentrated effort of several dedicated people. • Need to start now to get result by the end of year.

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