Performance and occupancies in Performance and occupancies in a CCD vertex detector with a CCD vertex detector with

endcapsendcaps

Toshinori Abe and John JarosToshinori Abe and John Jaros

04/21/0404/21/04

IntroductionIntroduction

Motivation: Motivation:

Extend barrel tracking philosophy forwardExtend barrel tracking philosophy forward1.1. Better vertexing at forward regionBetter vertexing at forward region

2.2. Extrapolate tracks to forward disks for Extrapolate tracks to forward disks for momentum measurement and reliable momentum measurement and reliable extrapolation to the calorimetry.extrapolation to the calorimetry.

3.3. Pattern Recognize in 5 Layers of CCDPattern Recognize in 5 Layers of CCD

4.4. Global Pattern Recognition to followGlobal Pattern Recognition to follow

Current working issueCurrent working issue

We need to make sure the feasibility of this We need to make sure the feasibility of this idea. idea.

At this point, we are working on the At this point, we are working on the following issues.following issues.

1.1. Endplate layout Endplate layout

2.2. PerformancePerformance

3.3. Occupancies and radiation damageOccupancies and radiation damage

Endplate layoutEndplate layout

-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

5cm 15cm 25cm0cm

5cm

15cm

0cm

Design conceptDesign concept

Extend 5 layer tracking over max Extend 5 layer tracking over max CoverageCoverage 5 CCD layers 5 CCD layers .97.97 (vs. .90 TDR VXD) (vs. .90 TDR VXD) 4 CCD layers 4 CCD layers .98.98 (vs. .93 TDR VXD) (vs. .93 TDR VXD)

Minimize CCD area/costMinimize CCD area/cost Shorten Barrel CCDs to Shorten Barrel CCDs to 12.5 cm 12.5 cm (vs. 25.0cm)(vs. 25.0cm)

Thin the CCD barrel endplate Thin the CCD barrel endplate a single a single 300 300 mm Si disk for self supporting Si disk for self supporting

Performance studyPerformance study

Full detector simulation for reality.Full detector simulation for reality. Generate single muon track for 2GeV, 20GeV, and Generate single muon track for 2GeV, 20GeV, and

200GeV as a function of cos200GeV as a function of cos.. Do Kalmann filter fit.Do Kalmann filter fit. Study momentum resolution, impact parameter resolution, Study momentum resolution, impact parameter resolution,

and dip angle resolution.and dip angle resolution.

Momentum and dip angle resolution Momentum and dip angle resolution

Almost same performance.

2GeV

20GeV

200GeV

Impact parameter resolutionImpact parameter resolution

Better performance at the forward region.

2GeV

20GeV

200GeV

XY RZ

Tracking performance with endplateTracking performance with endplate

Momentum and dip angle resolutions are Momentum and dip angle resolutions are same as previous design. same as previous design. These resolutions are dominated by lever These resolutions are dominated by lever arm than VXD.arm than VXD.

Impact parameter resolutions are Impact parameter resolutions are significantly improvedsignificantly improved both of low and high both of low and high momentum region.momentum region.Do we get better heavy flavor jet tagging Do we get better heavy flavor jet tagging at forward region than before?at forward region than before?

B-tag performanceB-tag performance

Z0q q-bar

@Ecm~91GeV Topological vertexing

+ PT corrected mass tag (no optimization)

Better b-tag performance at the forward region

Occupancy study setupOccupancy study setup

One big question for endplate vertex detector is One big question for endplate vertex detector is occupancy (and S/N ratio).occupancy (and S/N ratio).

We study it taking account to the following signal We study it taking account to the following signal and backgrounds at and backgrounds at √√s=500GeV:s=500GeV:

1.1. ee++ee-- t t-bar (Pandora Pythia) t t-bar (Pandora Pythia)2.2. Photons (Takashi)Photons (Takashi)3.3. ee++ee-- pairs (Takashi) pairs (Takashi)4.4. (*)(*)(*) (*) hadrons (Tim) hadrons (Tim)(Backgrounds are overlaying per a train.)(Backgrounds are overlaying per a train.)

We use full detector simulation with NLC beam We use full detector simulation with NLC beam condition (192 bunches per train).condition (192 bunches per train).

Endplate occupanciesEndplate occupancies

Occupancies vs. ROccupancies vs. R

10-3 at inner radius

Occupancy with endplateOccupancy with endplate

Good news:Good news:Occupancy rate (~10Occupancy rate (~10-5-5 and and 1010-3 -3 at inner radiusat inner radius) is not ) is not terrible. terrible. (Thanks to very fine granularity of CCD)(Thanks to very fine granularity of CCD)

Bad news:Bad news:S/N ratio is very small. S/N ratio is very small. (Small number of signal tracks and most of backgrounds (Small number of signal tracks and most of backgrounds are eare e++ee-- pairs which are real tracks.) pairs which are real tracks.) How difficult detector understanding?How difficult detector understanding?

How cost track finding?How cost track finding?How pollute signal tracks?How pollute signal tracks?

Radiation damage per monthRadiation damage per month

About ~5Gy/month at inner radius

How severe is it? How severe is it?

I have collected opinions by two vertex I have collected opinions by two vertex detector experts.detector experts.

1.1. First opinion : John First opinion : John Green light. Green light.2.2. Second opinion : Chris Second opinion : Chris Grey… Grey…

(should be careful about machine environment, (should be careful about machine environment, clock time, etc…)clock time, etc…)

Currently we can not say 5Gy/month Currently we can not say 5Gy/month indicates green, yellow, or red light. indicates green, yellow, or red light. We need more opinion about it.We need more opinion about it.

SummarySummary

We just start a study of vertex detector with We just start a study of vertex detector with endcaps.endcaps.

The endcaps significantly contribute to The endcaps significantly contribute to improve impact parameter resolution and b-improve impact parameter resolution and b-tag performance at forward region.tag performance at forward region.

The occupancy is not a problem but S/N The occupancy is not a problem but S/N ratio. (Is time stamp needed?)ratio. (Is time stamp needed?)

We are looking forward to hear expert’s We are looking forward to hear expert’s opinion about radiation damage.opinion about radiation damage.