# Presentation: 465821

## PHENIX upgrade –Silicon Vertex Tracker

- Outline
- The PHENIX experiment
- SVT overview
- Physics goals
- Technical options
- Plan
- Summary

- K. Tanida (RIKEN)
- for PHENIX collaboration  16/09/03 VERTEX2003

##  12 Countries;  57 Institutions;  460 Participants

**             ****Brookhaven National Laboratory, Upton, NY **
**             ****University of California - Riverside, Riverside, CA**
**             ****University of Colorado, Boulder, CO**
**             ****Columbia University, Nevis Laboratories, Irvington, NY**
**             ****Florida State University, Tallahassee, FL**
**             ****Georgia State University, Atlanta, GA**
**             ****University of Illinois Urbana Champaign, Urbana-Champaign, IL**
**             ****Iowa State University and Ames Laboratory, Ames, IA**
**             ****Los Alamos National Laboratory, Los Alamos, NM**
**             ****Lawrence Livermore National Laboratory, Livermore, CA**
**             ****University of New Mexico, Albuquerque, NM **
**             ****New Mexico State University, Las Cruces, NM**
**             ****Dept. of Chemistry, Stony Brook Univ., Stony Brook, NY**
**             ****Dept. Phys. and Astronomy, Stony Brook Univ., Stony Brook, NY  **
**             ****Oak Ridge National Laboratory, Oak Ridge, TN**
**             ****University of Tennessee, Knoxville, TN  **
**             ****Vanderbilt University, Nashville, TN****	****                                                                                                **

**Brazil        University of São Paulo, São Paulo**
**China        Academia Sinica, Taipei, Taiwan**
**                  ****China Institute of Atomic Energy, Beijing**
**                  ****Peking University, Beijing**
**France      LPC, University de Clermont-Ferrand, Clermont-Ferrand**
**                  ****Dapnia, CEA Saclay, Gif-sur-Yvette**
**                  ****IPN-Orsay, Universite Paris Sud, CNRS-IN2P3, Orsay          **
**                  ****LLR, Ecòle Polytechnique, CNRS-IN2P3, Palaiseau**
**                  ****SUBATECH, Ecòle des Mines at Nantes, Nantes**
**Germany  University of M****ü****nster, M****ü****nster**
**Hungary   Central Research Institute for Physics (KFKI), Budapest**
**                  ****Debrecen University, Debrecen**
**                  ****Eötvös Loránd University (ELTE), Budapest **
**India          Banaras Hindu University, Banaras**
**                  ****Bhabha Atomic Research Centre, Bombay**
**Israel         Weizmann Institute, Rehovot**
**Japan       Center for Nuclear Study, University of Tokyo, Tokyo**
**                  ****Hiroshima University, Higashi-Hiroshima **
**                  ****KEK, Institute for High Energy Physics, Tsukuba **
**                  ****Kyoto University, Kyoto**
**                  ****Nagasaki Institute of Applied Science, Nagasaki**
**                  ****RIKEN, Institute for Physical and Chemical Research, Wako**
**                                               ****RIKEN-BNL Research Center, Upton, NY              **
**                  ****University of Tokyo, Bunkyo-ku, Tokyo**
**                  ****Tokyo Institute of Technology, Tokyo**
**                  ****University of Tsukuba, Tsukuba **
**                  ****Waseda University, Tokyo                    **
**S. Korea   Cyclotron Application Laboratory, KAERI, Seoul**
**                  ****Kangnung National University, Kangnung**
**                  ****Korea University, Seoul **
**                  ****Myong Ji University, Yongin City **
**                  ****System Electronics Laboratory, Seoul Nat. University, Seoul**
**                  ****Yonsei University, Seoul**
**Russia       Institute of High Energy Physics, Protovino **
**                   ****Joint Institute for Nuclear Research, Dubna **
**                   ****Kurchatov Institute, Moscow**
**                   ****PNPI, St. Petersburg Nuclear Physics Institute, St. Petersburg**
**                   ****St. Petersburg State Technical University, St. Petersburg**
**Sweden     Lund University, Lund**

*** ******12 Countries;  57 Institutions;  460 Participants***

## The PHENIX experiment

- PHENIX

- at BNL-RHIC

## PHENIX program overview

- Two physics programs
- Heavy Ion program- up to Au-Au with            200 GeV- search for Quark Gluon Plasma
- RHIC-spin program- polarized proton collision with         500 GeV- study spin structure of proton, especially,   gluon polarization.
- PHENIX focuses on rare probes,e.g., J/, open charm/bottom, photons, etc.,in addition to non-rare probes.

## Heavy Ion program

-  Many measurements    - more than 10 physics talks in the JPS meeting last week
-  Examples include   - single/pair electron/muon   - high pT hadron suppression (jet quenching)   - two-particle correlation   - radial and elliptic flow   - J/    - ...

## RAA for 0 and charged hadron

**PHENIX AuAu 200 GeV**
- 0 data: PRL 91 072301 (2003), nucl-ex/0304022.
- charged hadron (preliminary) : NPA715, 769c (2003).

## Non-photonic electron

- PHENIX: PRL 88(2002)192303

- consistent with
- PYTHIA estimation
- for c,b  e
-  no suppression?
- uncertainty for photonconversion estimationis quite large

- PYTHIA

## Spin program

- Polarized proton collider Study of spin structure of proton      1/2 = 1/2 + G + L  ( ~ 0.25)
- Gluon polarization  a possible answer to spin crisis.
- How to study? ALL -- double spin asymmetry

- = (parton pol.)2×
-    (aLL in parton     reaction)

## Examples of reaction channels

- Direct photon: g + q   + q- ~10% contribution from other processes       (e.g.qq  )    golden channel for gluon polarization - Need high luminosity (> 100 pb-1).
- Inclusive high-pT hadron production- mix of various processes, q+q, g+g, g+q, ...- feasible at relatively small luminosity (~pb-1)
- Heavy flavor- g + g cc,bb
- W -- spin-flavor structure

## PHENIX detector 

## PHENIX detector (cont.)

- Global detectors (BBC, ZDC, NTC)- cover forward and backward region- triggering, event classification
- Central Arm (|| < 0.35, )- tracking, momentum measurement- RICH, TOF: PID (p,K,,e)- EMcal.: photon, electron energy measurement.
- Muon Arm (1.2 < |h| < 2.4,  ~ 2) - tracking, momentum measurement
- Limited capability for open heavy flavor- c,b  e, inclusive: suffers from severe background   Silicon Vertex Tracker upgrade

## SVT Overview

- Silicon vertex tracker   ****** detection of heavy flavors**

## Strawman design

- Barrel part + endcap part Barrel (|| < 1.2): Central Arm  Endcap (1.2 < || < 2.4): Muon Arm

## Conceptual Mechanical Specs.

- Central Barrel
- 	layer radius			2.5(pixel layer), 6, 8, 10(strip layers) cm
- 	layer length			30 cm
- 	pixel       			50 μm x 425 μm x 1.3M channels
- 	strips	         			80 μm x 3 cm x 370k channels
- 	azimuthal coverage	320 deg

- End Caps (each)
- 	inner radius			3.0 cm
- 	outer radius	    18 cm
- 	disk z pos.(at rin= 3.0cm)	20,26,32,38 cm
- 	pixel size		 	50 μm x 4 mm
- 	total pixels			~2.8M
- 	azimuthal coverage	320 deg

## Electron DCA resolution

- Simulation for single electrons in central barrel
- Full multiple scattering included (X/X0=1%/layer)
- DCA resolution < 50 m at moderate *p**T*
- less than *c*, D0: 125m, D: 317 m

-  Charm,      Bottom ID

## Physics goals

- 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-*p**T* heavy quarks
- spin physics
- gluon polarization in broad *x**Bj* 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

## gluon polarization – x range

-  Gluon fusion gg cc(bb) in polarized pp collision
-  c,b  e() and D  K, K
-  Better S/N  wider x range coverage                        using low pT electrons/muons

## Gluon structure of nuclei

- Using pA  cc(bb)
- broader range in x
-  into predicted shadowing region

- L. Frankfurt,
- M. Strikman
- Eur. Phys. J A5, 293 (99)

- Q = 2 GeV
- Q = 5 GeV
- Q = 10 GeV

## Direct photons

- gluon compton scattering
- SVX:  jet detection on the other side- provides more kinematical information    better S/N, lower pT,     lower x range (0.1 ~ 0.4  0.05 ~ 0.4)

-  jet

## Open heavy quarks in HI program

-  More data on pT spectra of open heavy flavors  - if gluon radiation, energy loss is smaller for heavy quarks
-  Open charm enhancement?  - possible in pre-equilibruim stage via gluon fusion.
-  J/ suppression  - should be discussed on J/ to (open charm) ratio  - we need to know yield ofcc pair via open charm     measurement  - especially important if enhancement is observed.
-  Does charm flow?
-  ...

## Technical options

-   Current choices
- 1st barrel layer- hybrid pixels using ALICE1 chip- modify peripherals (bus, pilot, ...) to match PHENIX   environment
- Outer barrel layers- strips (pixel-strip)- readout: SVX4 chip from FNAL
- endcap- mini-strips or hybrid pixels- readout: planning new chip in collaboration with FNAL.

## Hybrid pixel layer

- 20 ladders = 160 chips (1.3M pixels)

- ALICE1 readout chip
-  32 x 256 pixels of         425 m (z) x 50 m (r)
-  Size: 13.6 mm x 15.95 mm
-  Binary output
-  Readout speed: 25.6 s/chip @10MHz

-  R&D for modification of pilot chip and bus is ongoing.
-  Mass production will include PHENIX chips (CERN-RIKEN contract)

## Strip layers

-  New sensor prototype v1   - by Zheng Li (BNL instrumentation div.)   - spiral shape: divide one pixel (80 m x 1000 m)      to two regions and connect them  x and u strips   - single sided, yet 2-dimensional

## Strip sensor

- sensor size: 3 cm x 6 cm
- strip size: 3 cm x 80 m

- bonding pads

## prototype v1
2 metal (Al) layers
thickness: 400m and 250m
DC coupling
full depletion at ~80 V
capacitance ~10 pF
leakage current ~10 nA

- 2 metal (Al) layers
- thickness: 400m and 250m
- DC coupling
- full depletion at ~80 V
- capacitance ~10 pF
- leakage current ~10 nA

- Strip sensor (cont.)

## R&D items
charge division
noise level
position resolution
efficiency
test readout with VA2

- charge division
- noise level
- position resolution
- efficiency
- test readout with VA2

- Sensor test board

## KEK-PS T1 beam line
0.5-2.0 GeV/c charged particles
tracking with clusters on 2nd-6th board

- 0.5-2.0 GeV/*c* charged particles
- tracking with clusters on 2nd-6th board

- KEK beam test

## position resolution (after subtracting multiple scattering)
23m-26m
expected: 80m/12=23m

efficiency

- 23m-26m
- expected: 80m/12=23m
- efficiency

| Si number | efficiency |
| --- | --- |
| 2(250um) | 61.45±1.91 |
| 3(400um) | 96.41±2.87 |
| 4(400um) | 98.23±2.88 |
| 5(400um) | 87.29±2.66 |
| 6(250um) | 58.33±1.82 |

| Si number | Residual x(μm) | Residual x(μm) |
| --- | --- | --- |
| 2(250um) | 52.66±0.21 | 50.99±0.20 |
| 3(400um) | 35.73±0.08 | 43.08±0.13 |
| 4(400um) | 43.76±0.13 | 37.53±0.90 |
| 5(400um) | 34.45±0.08 | 43.49±0.13 |
| 6(250um) | 48.66±0.17 | 45.63±0.15 |

- OK for 400 m sensors

- Position resolution & efficiency

## Charge division

-   Not very good at small angle- spiral pitch not fine enough to accomodate diffusion? making 2nd prototype (pitch 13 m  8 m)

## 128-channel Si-strip readoutchip developed by FNAL/LBNL.
Pipelined digitization and readout (42-deep pipeline for analog samples).
4-event LVL1-accept buffering.
On-board zero-suppression available.
Multi-stage pedestal subtraction.
Designed for AC-coupled device (Z. Li  sensors DC-coupled). Two handles:
Frequent storage-cap resets.
Cool sensors to 0 degrees C to reduce leakage current.
Certainly able to do first. May suffice, but may want to cool anyway.
Integration time (~80 ns) much shorter than sensors have been tested at. Possibly worse S/N.
FNAL indicated willingness to do wafer-testing.

- Pipelined digitization and readout (42-deep pipeline for analog samples).
- 4-event LVL1-accept buffering.
- On-board zero-suppression available.
- Multi-stage pedestal subtraction.
- Designed for AC-coupled device (Z. Li  sensors DC-coupled). Two handles:
- Frequent storage-cap resets.
- Cool sensors to 0 degrees C to reduce leakage current.
- Certainly able to do first. May suffice, but may want to cool anyway.
- Integration time (~80 ns) much shorter than sensors have been tested at. Possibly worse S/N.
- FNAL indicated willingness to do wafer-testing.

- SVX4 readout chip

## Endcap mini-strips (preliminary) 

-  50 m radial pitch (z vertex reconstruction)
-  3000 mini-strips
-  3.5 cm < r < 18.5 cm
-  128 towers in phi
-  mini-strips from
-    2.2 mm to 11.6 mm
-  2 rows of strips in one
-  double-tower
-  8 (16) wedges in one lampshade(layer)
-  8 lampshades ( ~ 20 degree tilt)
- R&D for readout chip is planned with FNALgroup (R. Yarema et al.)

**r = 3.5 cm**

**r = 18.5 cm**

**1**

**3000**

- Endcap mini-strips (preliminary)

## Support & cooling

- Mechanical support- preliminary design ongoing at LANL/Hytec- single barrel shape with GFRP was chosen
- Cooling- R&D for cooling pipe embedded print circuit board   (~ 100 m thick) is starting at Soliton R&D company   in Japan in collaboration with RIKEN

## Plan/schedule

-  Barrel  - R&D: 2003-2004  - construction: 2005-2006  - Actual use from 2007.
-  Endcap  - R&D: 2004-2005  - construction: 2006-2007  - Actual use from 2008.

## Summary

- Silicon Vertex Tracker is an important part ofPHENIX upgrade program.
- Physics with SVT include- gluon spin structure function by open charm (bottom)  in polarized proton collision.- various measurement related to charm and bottom  quarks in heavy ion collision.
- Barrel: 1 pixel + 3 strip (stripixel) layersEndcap: mini-strips
- Plan to start data taking in 2007/2008R&D is ongoing.