# Presentation: 592886

## Simulated Performance of FVTX

- Outline:
-  Physics –driven requirements for the FVTX detector
-  Simulations that defined detector design and verified performance
-     --Detector design and performance
-     --FVTX tracks match with muon tracks
-  Critical Improvements FVTX provides to physics measurements
-     --Single Muon (open heavy flavor) measurement
-     --Heavy quarkonium measurement
- Many contributors:  Melynda, Hubert, Dave L., Pat, Xiaorong, Anuj, 			Joel...

- X. R. Wang, NMSU

## Physics–driven requirements

- DCA resolution to separate prompt, short-lived decays (B,D) and long-lived decay (π and K) from each other
- Ability to separate charm and beauty
- Low enough occupancy and high enough resolution to perform in AuAu environment
- Ability to match tracks from Muon arm to FVTX for all collisions.
- Excellent accuracy for the primary vertex using FVTX and VTX.

- X. R. Wang, NMSU

## Detector design and performance 

- X. R. Wang, NMSU

## Detector Design and Performance

- 4 layers of tracking: to allow at least 3 hits/track
- Radial extents:  to allow at least 3 hits/track as much as possible in area of muon coverage, constrained by the detector envelope
- Strips are 50 m (r segmentation) x 2-13.5 mm (phi segmentation): to allow good DCA measurement in boost direction, limited by multiple scattering rather than detector resolution,  and limited occupancy in AuAu

- X. R. Wang, NMSU

**Notes:**
This is the sideview  of FVTX. It has

Dca and z resolution. 

## DCA values for different particles

- P.T.

- π

- X. R. Wang, NMSU

## Detector design – Strip width

- DCA versus strip width and momentum
- Strip width is chosen to be 50 m.  start to reach diminishing returns because of multiple scattering contributions

- X. R. Wang, NMSU

## Primary Vertex Determination

- The identification of displaced vertices depends on the accuracy with which the primary vertex can be determined, we are using HIJET together with PISA to determine the primary vertex resolution.

- Z vertex resolution:

- X. R. Wang, NMSU

## Detector occupancy in Central AuAu

- Hits/cm2  per Central AuAu event

- At inner radii, strip size is 0.05mm x 2 mm = 0.1 mm2
- average 0.7% occupancy in highest occupancy areas
- Generally quote 1.5% maximum occupancy to take into account simulation uncertainty
- Low enough to expect track finding to be very doable

- X. R. Wang, NMSU

## FVTX Track Matching with Muon Track 

- X. R. Wang, NMSU

## Matching MuTr and Silicon tracks in Central AuAu (I)

- Issue:  in Central AuAu events, approximately 3 silicon tracks are found that approximately match each MuTr track
- Solutions:
- Look at additional rejection that can be
- 	obtained if we use a Kalman-Filter fit to
- 	MuTr+Silicon hits and choose best χ2
- Simulations:  Mix Central AuAu events with single muons
- Find MuTr reconstructed track
- Find all silicon stubs that are within a 2-d angular window of this track
- Fit each set of potential silicon hits with the MuTr track and store fit results
- Look at distributions for tracks  and check whether they are match
- Select best match (using χ2)

- X. R. Wang, NMSU

## Matching MuTr and Silicon tracks in Central AuAu (II)

- Rejection: Pick track with best 2:  93%, 83%, 75% of the time the correct match is made for total momentum 9 GeV, 6 GeV, 3 GeV particles

- Chi-square (3GeV)

- Chi-square (9GeV)

- X. R. Wang, NMSU

**Notes:**
This 25% unmatched track we will go to inefficiency lost.

## Improvement 	for Single Muon Measurement

- X. R. Wang, NMSU

## Current Limitations on Heavy Quark Measurements

- Single muon measurements limited at low pT by decays and at high pT by punch-throughs
- Single electrons limited at low pT by large contribution from 0, at high pT by PID capabilities
- Both muon and electron measurement can not separate charm and beauty

- pT (GeV/c)

- X. R. Wang, NMSU

## FVTX Contributions—Reduction of long-lived Decay Background

**FVTX Contributions—Reduction of long-lived Decay Background**

- Cutting on DCA<DCAmax (upper limit) to remove long-lived ,K decays.
- Especially important at low pT spectra

**Acceptance Fraction vs p****T**

- 1σ DCA cut at upper end:
- Accept 85% D meson
- Accept 25-50% π decay
- Accept 15-40% K decay.

- X. R. Wang, NMSU

## FVTX Contributions—Reduction of hadron Punch-Throughs

**FVTX Contributions—Reduction of hadron Punch-Throughs**

- Cutting on DCA > DCAmin (lower limit) to remove punch-through hadrons
- It is important at high pT spectra

**Acceptance Fraction vs p****T**

- P.T

- 1σ DCA cut at low end:
- Accept 65% D meson
- Accept 45% B meson
- Accept 30% Punch Throughs

- X. R. Wang, NMSU

**Notes:**
We used the 1 sigma cut for later slide to illuminated how this dca cut remove the back ground. (this cut is not optimized) 

## Signal/Background improvement for D,B measurement

**Signal/Background improved by factor of 10**

- X. R. Wang, NMSU

**Notes:**
A DCA smearing factor of 67 mu is also taking into to account for primary vertex.

## FVTX Contributions—Separation of Charm and Beauty

-  Single muon: Natural separation at
-    high pT (without FVTX)
-  Measure BJ/ψ events and infer
-    beauty differential cross section:
- 	 cut at 1 mm 10-4 rejection of prompt
- 	 J/ ψ s, 40% acceptance of BJ/ ψ)
- 	 (clean measurement)
-  Take advantage of longer decay length
-    for b compared to c trying to
-    understand whether D’s and
-    B’s can be separated by using the
-    different life time.

- _Charm/beauty separation still difficult, but a few possibilities:_

- X. R. Wang, NMSU

## Improvement 	for Heavy Quarkonium Measurement

- X. R. Wang, NMSU

## FVTX Contributions —Improvement for J/ measurement

- Background removal (60%)
- improvement in J/ mass
-    resolution
-       120MeV – 80MeV
- Note:
- Pure J/ signal using all silicon hits (barrel and forward).

- Without FVTX

- With FVTX

- X. R. Wang, NMSU

## J/ Measurement Improvement with FVTX

- AuAu Central (upper)
- AuAu MinBias (bottom)
- without and with FVTX :
- mass resolution improvement
-  background rejection
- Baseline S:B from real data
- Note: similar plots can be made for upsilons

- X. R. Wang, NMSU

## Possibility for ’ Measurement with FVTX

- pp without and with FVTX
- mass resolution  improvement
- background rejection
- S/B: run5pp , RHIC II luminosity, 10 Weeks

- X. R. Wang, NMSU

## Expected future simulation work

- Finish optimizing detector geometry with simulations (strip and plane orientation, etc. )
- Incorporate FVTX hits with other upgrade detector (VTX, RPC, NCC) hit to determine performance of to integrated systems:
- background rejections, improvement in momentum resolutions...
- More simulation to estimate physics quantities (RAA, flow...)
- More complete study of physics rates with efficiency hits taken into account.

- X. R. Wang, NMSU

## Summary

- Detector Performance:
- --Geometrical layout gives ≥3 hits per track, most of the time
-    Occupancies 1.5%
- --50 μm strips give good DCA resolution and desired segregation of
-    prompt tracks, short lived decays, and long-lived decays
- --Simulations with expected material retain good DCA resolution
- --have sufficient segmentation to achieve clean match from muon track
-    to FVTX in central AuAu collisions.
- For single muon measurements:
- -- make clear separation of light hadrons and muons from open heavy
-     flavor
- -- improve open heavy flavor signal/background by factor of 10
- For heavy quarkonium measurements:
- -- reduction of backgrounds by at least factor of 2
- -- improved mass resolution
- -- simulation with RHIC II luminosity already show the possibility to
-    measure other heavy onium state and their resonance.
- -- promising to do clean measurement for B->J/ψ.
- -- continuum measurement (separate DY and cc).

- X. R. Wang, NMSU

## Backup 

- X. R. Wang, NMSU

## FVTX Contributions—Reduction of hadron Punch-Throughs

**FVTX Contributions—Reduction of hadron Punch-Throughs**

- Cutting on DCA > DCAmin (lower limit) to remove punch-through hadrons
- It is important at high pT spectra

**Acceptance Fraction vs p****T**

- P.T

- 1σ DCA cut at low end:
- Accept >70% D meson
- Accept >50% B meson
- Accept <30% Punch Througths

- X. R. Wang, NMSU

## FVTX Contributions—Reduction of long-lived Decay Background

**FVTX Contributions—Reduction of long-lived Decay Background**

- Cutting on DCA<DCAmax (upper limit) to remove long-lived ,K decays.
- Especially important at low pT spectra

**Acceptance Fraction vs p****T**

- 1σ DCA cut at upper end:
- Accept 70-80% D meson
- Accept 20-30% π decay
- Accept 2-5% K decay

- X. R. Wang, NMSU

## FVTX Contributions—Reduction of hadron Punch-Throughs

- Cutting on DCA > DCAmin (lower limit) to remove punch-through hadrons
- It is important at high pT spectra

**To measure D meson:**
**Acceptance Fraction**
**Vs pT**

- X. R. Wang, NMSU

## Detector acceptance

- Number of Forward Silicon, Barrel Pixel, and Barrel Strips
-  hit versus theta and z vertex position

- FVTX matches and extend the capability of Muon Arm

- X. R. Wang, NMSU

## FVTX Contributions—Removal of Backgrounds

- Signal:Background in central south arm events ~1:20
- Combinatorial background from 3 possible combinations of hadron decay muon and punch-through

- Mass (GeV)

- Two combinations which include a decay can potentially be separated from prompt J/s:  ~60% at J/ mass

- X. R. Wang, NMSU

## DCA value for difference particles

- For D measurement: (1σ)
- σpt <DCA< σD
- For B measurement: (1σ)
- σpt <DCA< σB

- X. R. Wang, NMSU

## Explore performance with different strip orientations

- Strip clustering, strip size and threshold cuts for the cone geometry
- Flat endcap simulaition

- X. R. Wang, NMSU

- X. R. Wang, NMSU