Silicon Vertex Tracker (VTX) for PHENIX Experiment at RHIC Y. Akiba (RIKEN) for PHENIX collaboration Detector Advisory Committee Meeting November 22, 2003

VTX proposal l 65 authors from 14 institutes l 4 institutes outside of present PHENIX l Main part (VTX barrel) About 100 pages 52 figures 8 tables l Appendix (EndCap extension) about 20 pages 16 figures

Pixel barrels (50  m x 425  m) Strip barrels (80  m x 3 cm) Endcap (extension) (50  m x 2 mm) 1 - 2% X 0 per layer barrel resolution < 50  m endcap resolution < 150  m 1.2<|  |< 2.4 |  |< 1.2 Silicon Vertex Tracker in PHENIX

Physics Beyond Reach of Current PHENIX l Detailed study of the hot and dense matter formed in Au+Au collision l Precise measurement of charm production Charm enhancement in pre-thermal stage Reference for J/  measurement l Beauty measurement in Au+Au collisions l Flavor dependence of QCD energy loss in hot matter l Thermal di-lepton pair (charm background) l High p T charged particle (pT > 10 GeV/c)  G measurement in broad x range in polarized p+p collision l Charm/beauty production  +jet measurement l Gluon shadowing in broad x range l by heavy quark production Measurements complement and enhance the present physics program fully exploit existing rare event capabilities of PHENIX Provide key measurements so far inaccessible at PHENIX:

Open Charm and Beauty l Physics interest in charm and beauty in Heavy Ion Collisions l Charm enhancement in pre-thermal stage l Do heavy quarks lose energy in quark matter? critical base line for J/  and Y production & dilepton continuum l Spin Physics with charm/beauty l Gluon polarization in wide l PHENIX measured charm via inclusive electron (PRL88 (2002) ) l Indirect measurement l can not distinguish charm and beauty for p T > 2.5 GeV/c beauty charm Charm and beauty separation aim of future PHENIX program

Physics from precise charm measurements Is there pre-thermal charm production? Precise charm measurement is required to detect small enhancement Does charm flow? Does charm suffer energy loss? Charm measurement in pT>3 GeV/c is required to see energy loss effect Thermal dileptons from the QGP Di-leptons from charm decay must be identified and subtracted to detect the thermal di-leptons from the QGP in 1-3 GeV region These measurements are not possible or very limited without the VTX

D Detection of decay vertex will allow a clean identifications of charm and bottom decays m c   GeV  m D D ± B B ± Need secondary vertex resolution < 50  m Beauty and high p T charm will require high luminosity Direct Observation of Open Charm and Beauty Detection options: Beauty and low p T charm through displaced e and/or  Beauty via displaced J/  High p T charm through D   K Au e D X J/  B X  K e e

Charm measurements with the VTX l Precision DCA (Distance of Closest Approach) measurement by the VTX strongly suppress background from Dalitz and the conversion l More than factor 10 improvements of S/B. l In low pT region, electron spectrum after the DCA cuts is dominated by charm decay l Robust charm measurement at low pT l c  e / b  e separation from the difference of decay length  Extends c  e measurement beyonds pT>2.5 GeV/c  Measurement of energy loss of charm lc  e by barrel+central arm

Direct measurement of D  K  Simulation of D  K  (p T >2 GeV/c) with VTX l 1 % radiation length per layer After a DCAcuts, 7  significance is achieved for central Au+Au collision DCA of primary tracks DCA of D  K  Signal significance (S/B 1/2 ) of D  K  DCA cuts 7  DCA(cm)

beauty measurement with VTX l In high pT (pT>3 GeV/c), the electron spectrum is dominated by beauty decay l Clear separation of b from c using the difference of decay length l b measurement in 1 50% of b  e yield l Accurate beauty measurement is not possible without the VTX lb  e by VTX + central arm

Spin Physics with VTX l Measurement of Gluon polarization by Heavy flavor production c, b  e,  + displaced vertex B  displaced J/  D  K  at high pt l VTX measurement of displaced vertex Improved S/B  higher sensitivity to  G(x) Much broader x coverage VTX significantly increases the x coverage of  G(x) measurement

Gamma+Jets l In p+p or p+A collisions, the VTX works as a stand alone, large solid angle tracker l The VTX is used to detect the recoil jets in the direct photon events. l PYTHIA simulation with the VTX acceptance l RMS resolution of initial parton x is ~20% with the VTX Without the VTXWith the VTX RMS resolution of x 1

Measurement of gluon shadowing with VTX l Heavy-flavor measurement in p+A Single lepton and J/  with displaced vertex l Heavy-flavor production via g+g  q+  q l Extracting gluon structure function nuclei, shadowing l vertex detector provides broader range in x into predicted shadowing region (x ~ ) coverage w. the VTX

Expected Signal yield in RUN8 Many of these measurements are not possible or very marginal without the VTX NO marginal limited

Barrel VTX detector Summary of the parameters of the VTX Barrel detector (GEANT model)

Pixel detector l Use pixel detector technology developed for ALICE and NA60 l RIKEN/ALICE collaboration Pixel size: 50  x 450  l ALICE1LHCb read-out chip l 32 x 256 ch / chip l Configuration of PHENIX VTX pixel layer l 1 sensor chip (4x128x32 pixels) is read-out by 4 ALICE chips l 2 sensor chip / half ladder l 2 half ladder / 1 ladder l 20 ladders/ pixel layer l 1.2 % radiation length l R=2.5 cm Readout Bus Detector readout chip Support/cooling Half ladder Pixel detector

Pixel Readout (ALICE PILOT module) l Use a variant of ALICE PILOT module to read-out the pixel data and the data by optical fiber link l 10 MHz read-out, 25.6 usec per chip, using the ALICE chip set l Some modification may be needed for digital PILOT (  R&D) Analog PILOT (control, etc) digital PILOT (read pixel data) Optical link driver chip (GOL) Optical package data clock & control Read out Bus From pixel Optical I/O PILOT module

Pixel at Work (NA60) l The Pixel detector is used for target spectrometer of NA60 experiment at SPS l A part of RIKEN and StonyBrook group participates in NA60 to gain experience of using the pixel detector in a real experiment l The pixel detector worked very well in the recent In+In run of NA60 l The success of NA60 run demonstrates the capabilities of the pixel technology: l High efficiency l Low noise hit rate l It worked in extremely high radiation environment (>M rad during the run)

beam test of pixel detector (ALICE) l Beam time; Oct-22 – Nov-08 l Indium ion beam on to Sn target l RIKEN group participate in the ALICE beam test l 5 single chip + 1 ladder in beam test l Ladder is read by “almost real” PILOT MCM and “almost real” pixel read-out bus for ALICE l Success to read data with full readout chain Pixel ladder + Pixel Bus + MCM ( Digital Pilot chip + GOL ) Beam test set up for ALICE pixel

Barrel strips detector l Outer 3 layers use Si strip detector technology l Use a novel, single sided, two dimensional read-out sensor developed by Z. Li of BNL Inst. Division 80  x 3 cm strip l X/U stereo read-out l 384 x 2 x 2 per sensor chip (64.6 mm x 30.7 mm) l V1 prototype was tested by RIKEN group V2 prototype 400  and 300  thick is being made. (Will be delivered in this year) l 4 sensor chips / ladder l R2 (R=6cm)10 ladders l R3 (R=8cm) 14 ladders l R3 (R=10cm) 18 ladders Sensor structure (ver1) One strip sensor chip 64.6mm 30.7mm

Strips detector read-out l Use SVX4 chip developed by FNAL/LBNL for the Tevatron SVTX upgrade l 128 ch/chip 50  pitch read-out l 42-deep pipe line l On-board 0-suppression l Designed for AC coupled device. (Z.Li sensors DC- coupled) l Frequent storage-cap reset l AC/DC conversion by RC chip in the pitch adaptor l Recently, Tevatron SVTX upgrade project was cancelled. Three are already sufficient SVX4s produced. We are in negotiation with FNAL to purchase these chips. SVX4 chip Read-out scheme: 2 Read-Out Cards (ROCs) mounted on each sensor. Each ROC has 6 SVX4s

Silicon Vertex Tracker R&D Beam test at KEK by RIKEN/Kyoto  =52  =35  =45  =35  =49  Source test at RIKEN

Mechanical structure and cooling Different structures were considered  Choose single-barrel shape. Material: GFRP Cooling Radiation length: <1% per layer Design of support structure by HYTEC Cooling of the barrel FEM analysis Gravity deformation Distortion from thermal strains

Remaining R&D l Pixel Detector l Pixel readout bus Design and prototyping by Sep 2004 l PILOT module Modification of digital pilot chip to meet PHENIX specification Technology choice (modified ASIC or FPGA) by April 2004 l Pixel FEM First prototype by Sep 2004 l Strip detector l Full chain test of SVX4 read-out of the strip sensor Use the second proto-type of the strip sensor Test completed by April 2004 l the SVX4 read-out card The first prototype cycle completed by July 2004 l Integration l Specifications of mechanical design l Mechanical design study R&D support from RIKEN and DOE. Request DOE R&D fund of ~$280K

Budget l Contribution from RIKEN $3M for man-power, etc (~ $1M) l Total DOE costs: $5.6M in FY05-07 Direct: $3.7M Overhead:$0.3M Contingency$1.6M (~40%) Profile for the DOE costs Q1 Q2 Q3 Q4 FY2005 Q1 Q2 Q3 Q4 FY2006 Q1 Q2 Q3 Q4 FY2007 $0.5M/Q

schedule l Start construction in FY05 l Construct in FY05-07 l Part of the VTX will be built and installed for RUN7 l Complete detector installed in RUN

Summary l Physics with the VTX detector l Au+Au Precise measurement of charm production Energy loss of charm at high pt Beauty production l Polarized p+p  G(x) measurement in wide x range (polarized proton) l p+A (d+A) Gluon shadowing in wide x range l Proposed Silicon vertex detector l 1 pixel layer l 3 strips layers l R&D in past 2 years l Cost and Schedule l Ready for start of construction in FY05 l $3M contribution from RIKEN l $5.6M of total cost for the DOE in FY05-07 l Install the full detector in RUN8 (FY08)

backups

Silicon strip detector R&D l Prototype v.2 l p + line: 7  m  5  m l gap: 6  m  3  m l turn: 3 turns  5 turns l delivery: December l Test readout board l SVX4 readout chip by FNAL/Berkeley collaboration l I/F board to PHENIX DAQ by ORNL l PHENIX DAQ emulation on PC CDF hybrid SVX4 CDF hybrid I/F board FPGA I/O FIFO cable USB PC LabView GUI v.2 prototype sensor pitch adapter

Silicon strip detector R&D l Laser test bench l at BNL instrumentation l to study basic properties of the sensor l to find optimum operation parameters