Status of TPC/HBD for PHENIX

Craig Woody BNL

DC Upgrades MeetingFebruary 12, 2002

C.Woody, DC Upgrades Meeting, 2/12/02 2

New Physics to be Addressed with the TPC/HBD

Low mass dilepton pairs• provides tracking through non-uniform residual magnetic field• electron id for pT < 200 MeV by dE/dx and cherenkov• reduces mass in front of detector by requiring fewer layers of silicon for tracking and vertex finding• reduces mass seen by all outer detectors• can be used for both HI and pp running

Heavy flavor (c,b) production• used in conjunction with the vertex detector, reduces requirements on the number of layers of silicon

Jet studies and g-jet correlations• provides 2p tracking over |h| < 0.7• improves momentum resolution ( dpT/pT ~ .02), paricularly at low pT

Rare processes• designed to work at highest HI and pp luminosities

C.Woody, DC Upgrades Meeting, 2/12/02 3

TPC tracking coverage

Df=2p -0.7<|h|<0.7

dpT/pT ~ 0.02

Inner Coil creates a “field free” (∫Bdl=0) region inside the Central Magnet

PHENIX Inner Detector

will be installed

during 2002 shutdown

C.Woody, DC Upgrades Meeting, 2/12/02 4

Field Integral

Momentum resolution in TPC

300 mm single point resolution in x,y,z

(Simulation by N. Smirnoff)dpT/pT=0.02

field from CDR scaled to 0.78 Tm

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 50 100 150 200 250 300 350

R (cm)

Bz

(Tm

)

++ 1.25 Tm

+ 0.73 Tm

+- 0.22 Tm

DC at 220 cm

B dl to drift chamber

PHENIX ± Field Configuration

Z (m)

Tracking in the Central Region in PHENIX

C.Woody, DC Upgrades Meeting, 2/12/02 5

Simulation by J. Heuser

Pixel barrels (50 mm x 425 mm)Strip barrels (100 mm x 5 cm)Pixel disks (50 mm x 200 mm)

e

dca

D eX

primary vertex

ct0 = 125 mm ct± = 317 mm

1.0% X0 per layer

500 mm Be Beam Pipe

1.2<|h|<2.4

|h|<1.2

Proposed Silicon Tracker in PHENIX

C.Woody, DC Upgrades Meeting, 2/12/02 6

Dileptons in High Energy Heavy Ion Collisions R.Rapp, Jaipur Conference

Low Mass Electron Pairs at CERN

C.Woody, DC Upgrades Meeting, 2/12/02 7

Low Mass Electron Pairs at RHIC

Dilepton spectra from central Au-Au collisions at full RHIC energy

R.Rapp, Jaipur Conference

Y. Akiba

C.Woody, DC Upgrades Meeting, 2/12/02 8

Study the electronic and optical properties of gases (CF4, CH4, …)

• Detector design (field cage, readout plane, construct prototype)

Investigate readout detector options (GEM, mMega, MWPC w/pads)

• Design of integrated readout electronics

Monte Carlo simulation studies

R&D Topics

C.Woody, DC Upgrades Meeting, 2/12/02 9

Measurements by Bob Azmoun, Stony Brook

Constructed gas cell with MgF2 windowMgF2 Absorbance (25.40x1.00mm)

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

1050 1150 1250 1350 1450 1550 1650 1750 1850 1950

Wavelength [angstroms]

Ab

so

rban

ce

Absorbance : MgF2 (30.00x2.20mm)

0

0.2

0.4

0.6

1050 1250 1450 1650 1850

Wavelength [angstroms]A

bs

orb

ance

Setup to measure VUV transmission of gases

C.Woody, DC Upgrades Meeting, 2/12/02 10

VUV Spectrometer

Absorbance: CF4

-0.01

0.01

0.03

0.05

0.07

0.09

0.11

0.13

0.15

1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

Wavelength [m x E-10]

Ab

sorb

ance

Gas Transparency Measurements

C.Lu & K.T. McDonald, NIM A343(1994) 135-151.

B. Azmoun (Stony Brook)

CF4

99.997 purity

C.Woody, DC Upgrades Meeting, 2/12/02 11

Photocathodes

CsI

CVD Diamond

C.Woody, DC Upgrades Meeting, 2/12/02 12

AHV

UV

MgF2 window

CsI or CVD photocathode

Setup to Measure Photocathodes

Need CsI photocathodes

vacuum or gas

C.Woody, DC Upgrades Meeting, 2/12/02 13

TPC Drift Cell

presently being fabricated at MDC

C.Woody, DC Upgrades Meeting, 2/12/02 14

Ordering new GEM foils to be used with TPC Drift Cell

Results with GEM Detector

• Energy resolution < 20% (55Fe) variation over 10x10cm2

(12 points)

• Ar/CO2 gas mixture very stable G~ 2 x 104 typical G ~ 6x104 max no sparks over > 8hrs

• Tested mixtures of Ar+CH4 (95/5 - 50/50)

N. Smirnov (Yale)

C.Woody, DC Upgrades Meeting, 2/12/02 15

Measurement Setup in Instrumentation

Micromega results

55FeFWHM = 26%

5.4 keV

CF4

300 350 400 450 500

Micromegas Voltage (-V)

0.001

0.01

0.1

1

Ch

arg

e (

pC

)

100

1000

10000

Ga

in

Micromegas Mesh, 50 µm spacing, Ar/20%CO2

VW

= -2000 V, 55Fe

Electrical Instability

I.Giomataris,G.Smith,B.Yu

C.Woody, DC Upgrades Meeting, 2/12/02 16

Track density in pp

dNch/dy = 2.6L x s = 2 x 1032 x 60 mb (Ss = 500 GeV) = 12 MHz (min bias)

12 MHz => 12 events/msec => ~50 m.b. events per drift time

12 MHz x 2.6 trks x 1.5 = 47 x 106 trks/sec = ~ 47 trks/msec

Au-Au L ~ 8 x 1027 cm-2s-1

O-O L ~ 1.6 x 1029 cm-2s-1

p-p L ~ 2 x 1032 cm-2s-1 (possibly -> 4 x 1033 cm-2s-1)

Track density in HI

dNch/dy = 150 (min bias)L x s = 8 x 1027 x 7.2 b = 58 kHz

58kHz x 150 trks x 1.5 = 13 x 106 trks/sec = 13 trks/msec

47 trks/msec x 4 msec = 188 trks 188 trks x 35 pts(max)/trk x 12 bytes/pt ~ 80 kB

Rate Issues for TPC

C.Woody, DC Upgrades Meeting, 2/12/02 17

Number of channels

Aplane = p (552 - 202) = 8247 cm2

Apad = 1.0 x 0.2 = 0.2 cm2

Npad = 8247/0.2 = 41,233 x 2 = ~ 80K chs

Readout Speed in PHENIX

Buffer size < 40 beam clock ticks 40 x 100 ns (10 MHz) = 4 msec

(EMCAL pushes this to 6.4 msec)

Readout time < 40 msec (25 KHz in DCM)

800 Kb => 6.4 x 106 bits/40 x 10-6 sec = 1.6 x 1011 bits/sec

= 160 Gbits/sec (20 Gb/sec)=> 160 1Gbit fibers (TEC has 128)

=> 40 DCMs (TEC has 28)

Data Volume

4 msec/20 ns => 200 time samples (8 bits) 80K x 200b ~ 16 Mb

Assume zero suppression of 1/20=> 800 Kb

(actual hit rate gives 80 Kb => 1/200)

Trigger

Expect actual trigger rate in pp to be ~104 Hz at L = 2 x 1032

(trigger rate of interesting events including W,Z,charm is only ~ 103 Hz) If data volume after final zero suppression is 80 Kb, then 80 Kb x 104/sec => 800 Mb/sec => need Level 3 trigger

Data Volume and Readout Speed for TPC

C.Woody, DC Upgrades Meeting, 2/12/02 18

2002 - Completion of Baseline Detector Install North Muon Spectrometer Upgrade TEC to TRD

2003-2004 Silicon strip detectors Prototype silicon pixel detector Prototype HBD (upgradable to TPC) Prototype aerogel detector

2005-2007 Complete silicon pixel detectors Complete TPC/HBD Complete aerogel detector

R&D 2002-2005• presently supported by various institutional funds (LDRDs,RIKEN)• requires ~ 3-4 $M over 3-4 yrs• needs DOE funding to continue

Construction 2004-2007

• Staged approach, with detectors requiring less R&D to be implemented first

• Rough estimate of detector construction costs ~ $10-15M

• NSAC plan shows $80M in RHIC II detector upgrades over 7 years starting in FY05

Time Scale and Cost

C.Woody, DC Upgrades Meeting, 2/12/02 19

Summary

• TPC/HBD/SVT are an integrated part of the upgrade of the central part of the PHENIX detector

• Time scale for HBD/Si strips and TPC/Si pixels are different, driven mainly by electronics development and infrastructure. This leads to a natural upgrade process, assuming one can accommodate infrastructure issues.

• R&D on both TPC and HBD detectors is well under way

Needed for R&D proposal

• Serious simulation effort

• Serious estimate of effort needed in electronics and DAQ