Simulations:resolution, occupancy, …,

for the barrel

Silicon upgrade workshop in Nashville

June 9, 2003

Yuji Goto (RIKEN/RBRC)

June 9, 2003 Yuji Goto (RIKEN/RBRC) 2

Physics goals of silicon vertex detector

• heavy-ion physics– modification of gluon structure in nuclei

• gluon shadowing

– properties of earliest, densest stage of Au+Au• charm enhancement• charm baseline for J/ suppression• energy-loss of high-pT heavy quarks

• spin physics– gluon polarization in broad xBj range

• prompt photon + jet production: gluon Compton process• heavy flavor production: gluon fusion process

– flavor contents of quark polarization• weak boson production

– transversity• particle correlation

June 9, 2003 Yuji Goto (RIKEN/RBRC) 3

Strawman

Channels Occupancy(central Au+Au)

barrel 1st: pixels 1.3 M <1%

barrel 2nd: strips 92 K 12%

barrel 3rd strips 123 K 7%

barrel 4th strips 154 K 5%

endcaps; pixels 2.8 M <3%

June 9, 2003 Yuji Goto (RIKEN/RBRC) 4

XBj coverage before and after …

• figure for the LoI presentation in March … s = 200 GeV, full luminosity 320 pb-1

– S/N > 1– statistics: #event > 100-1000

photon+jet

cce(displaced)X

J/ee

bbe/+displacedccDX

xG(x)

GS95

BJ/X

prompt photoncceX

bbeX

baselineupgrade barrel

cc(displaced)X

J/BJ/X

xG(x)

GS95

bbeX

baselineupgrade endcap

bbe/+displaced

June 9, 2003 Yuji Goto (RIKEN/RBRC) 5

Photon+jet measurement

• S/N will improve … ?– S/N > 1 for pT > 5 GeV/c after isolation cut

– xgluon = 2pT / s > 0.05

• jet-axis resolution ?– kinematic reconstruction– how much advantage ?

• improvement of isolation cut ?

inclusive

inclusive

+ leading hadron

xg calculated by xg=2pT/s

xg calculated by kinematic reconstruction

June 9, 2003 Yuji Goto (RIKEN/RBRC) 6

Single-electron measurement

• mid-rapidity sources of electron …– remove Dalitz via vertex cut

– charm pT(e) < 3 GeV/c

– beauty pT(e) > 3 GeV/c

SumDalitzCharmBeauty

pT(e) (GeV/c)1 2 3 4 5 6 7

by Vladimir Rykov

June 9, 2003 Yuji Goto (RIKEN/RBRC) 7

Electron DCA resolution

– 50mm x 425mm pixels, full multiple scattering

– DCA resolution (electrons) < 50 mm at moderate pT

– less than c, D0: 125mm, D: 317 mm

collision vertex

e-track

dca

by Johann Heuser

June 9, 2003 Yuji Goto (RIKEN/RBRC) 8

cceX

• S/N will improve by displaced vertex identification …– baseline: pT = 2-4 GeV/c xgluon = 0.05-0.1

– upgrade: pT = 1-4 GeV/c xgluon = 0.01-0.1

by Wei Xie

June 9, 2003 Yuji Goto (RIKEN/RBRC) 9

ccDX

– pT > 4 GeV/c xgluon > 0.1

– triggering ?

D+K- (BR 9%)c

D0K p+p 30k/year

Au+Au 10K/year

by Iowa group

June 9, 2003 Yuji Goto (RIKEN/RBRC) 10

bbe/+displaced-vertex

• statistics will improve …– 30 times larger statistics

– baseline: xgluon = 0.04-0.15

– upgrade: xgluon = 0.02-0.3

• triggering is necessary …

ecc ebb

ehcc ehbb

hbb hcc

June 9, 2003 Yuji Goto (RIKEN/RBRC) 11

BJ/+X

• J/ee– baseline: xgluon = 0.02-0.06

• BJ/ee– upgrade: xgluon = 0.03-0.1 or narrower

J/ BJ/

June 9, 2003 Yuji Goto (RIKEN/RBRC) 12

More studies to do …

• resolution, occupancy, …– how much occupancy in the heavy-ion environment

realistically ?– how to survive it pattern recognition, tracking, …– matching to central arms– jet-axis resolution ?

• S/N, statistics, how to pin-down xgluon, …

• others …– triggering s = 500 GeV– other channels: bbeX, …