TPC/HBD R&D

C.Woody, N.Smirnov, B.Azmoun, M.Sivertz, B.Yu, R.Majka, J. Mitchell, V.Rykov, M.Purschke, C.-Y.Chi

PHENIX Collaboration MeetingNashville, TN

June 11, 2003

C.Woody, Nashville Collaboration Meeting, 6/11/03 2

List of Topics

GEM measurements with Ar/CO2 and CF4

Status of new GEM foils Gas transmission measurements TPC field cage design Tracking Issues with TPC and VTX Electronics for the HBD and TPC R&D plan for next year

C.Woody, Nashville Collaboration Meeting, 6/11/03 3

GEM configuration

Initial tests with GEMs using CF4 did not produce usable signals

Problem was with electric field in transfer gaps

Smaller gap spacing and higher fields (> 2 kV/cm) give much higher gains

C.Woody, Nashville Collaboration Meeting, 6/11/03 4

GEM Measurements with Ar/CO2

Small-Triple GEM Gain in Ar-CO2 deltaV(Foil) = deltaV(TG)

y = 2E-08e0.0704x

y = 2E-08e0.0763x

100

1000

10000

100000

315 335 355 375 395

deltaV(Foil) [V]

Gain

Small-Triple GEM Gain in Ar-CO2 deltaV(TG) = 360V, invariant

y = 1E-07e0.0709x

1000

10000

100000

320 330 340 350 360 370 380 390

deltaV(Foil) [V]

Gain

Small-Triple GEM Gain in Ar-CO2 deltaV(Foil) = 360V, invariant

0

5000

10000

15000

20000

25000

30000

0 100 200 300 400 500 600

deltaV(TG1+TG2+1/2TG3) [V]

Gain

BNL

WIS

Resistive divider Fix VTG

Vary VF

Fix VF

Vary VTG

• We seem to get higher gain at the same voltage than WIS

• At fixed VTG the gain curve is nicely exponential as expected up to ~ 105 where discharging starts to occur

• Varying VTG at fixed VF has a much weaker effect on gain, but shows no plateau up to the maximum V

C.Woody, Nashville Collaboration Meeting, 6/11/03 5

GEM Measurements with CF4

Small-Triple GEM Gain in CF4deltaV(Foil) = 525 V, invariant

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

200 250 300 350 400 450 500 550 600 650

deltaV(TG1 + TG2 + 1/2IG)/3 [V]

Ga

in

Small-Triple GEM Gain in CF4deltaV(TG)=500V, invarint

y = 4E-07e0.0449x

100

1000

10000

100000

1000000

450 475 500 525 550 575 600 625 650

deltaV(Foil) [V]

Ga

in

Small-Triple GEM Gain in CF4deltaV(Foil) = deltaV(Trans. Gap)

y = 2E-07e0.0467x

y = 3E-09e0.0534x

100

1000

10000

100000

1000000

450 470 490 510 530 550 570 590

deltaV(Foil) [V]

Gai

n

Resistive divider

Fix VTG

Vary VF

Fix VF

Vary VTG

• We again seem to get higher gain at the same voltage than WIS

• Both BNL and WIS see saturation in CF4 at gain ~ 105 (before breakdown point)

• VTG again has a much weaker effect on gain and shows no plateau

BNL

WIS

C.Woody, Nashville Collaboration Meeting, 6/11/03 6

New GEM Foils from 3M

Expecting delivery of 50 new 10x10 cm foils at BNL in ~ 2 weeks

Roll-to-roll process Limited to 12” width

3M Microinterconnect Systems Division, Austin, TXIn collaboration with Univ. Chicago (J.Collar)

hep-ex / 0304013 (April 2003)

C.Woody, Nashville Collaboration Meeting, 6/11/03 7

Testing Small 3M Foils

3 stage GEM with three 1” dia. 3M foils

80 mm (55 mm) holes spaced in a hexagonal pattern with 140 mm pitch

Visually looks to be excellent quality

Will compare with CERN foils in Ar/CO2 & CF4

C.Woody, Nashville Collaboration Meeting, 6/11/03 8

VUV Transparency of Potential Radiator Gases

VUV transparency is extremely sensitive to O2 and H2O content

80

85

90

95

100

105

110

1150 1250 1350 1450 1550 1650 1750

Wavelength [Angstroms]Tra

nsm

itta

nc

e [

%]

Ar, [O2]=5.6ppm,[H2O]=2.3ppm

CF4, [O2]=0.6ppm,[H2O]=19.0ppm

Tranmittance of Argon and CF4

Gas system being developed andtested in collaboration with LEGS

B.Azmoun

C.Woody, Nashville Collaboration Meeting, 6/11/03 9

Low O2 and H2O levels are critical for good VUV transparency

Absorbance: Ar

0

0.1

0.2

0.3

0.4

0.5

0.6

1100 1200 1300 1400 1500 1600 1700 1800

Wavelength [Angstroms]

Ab

so

rba

nc

e

Static, 0 hr.

Static, 1 hr.

Flow, 0 hr., gauge valveopen

Flow, 20 min., gaugevalve closed

Flow, 1 hr.

Flow, 24 hrs.

Flow, 65 hrs.

Flow, 65 hrs., inc. rate

Flow, 65 hrs., flow meterremoved

Flow, 70hrs., f-mremoved

Static, following flow

(Simple gas flow system)

Absorbance of Ar ( P~700 Torr)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1100 1200 1300 1400 1500 1600 1700 1800

Wavelength [Angstroms]

Ab

so

rba

nc

e

Static (Brfore Flowing), Wait= 0min.

Flow, 0 Hr.

Flow, 1 Hr.

Flow, 2 Hr.

Flow, 3 Hrs.

Static (After Flowing), Wait = 0min.

Older Measurement: No Flowsystem: Static, Wait = 0 min.

Flow Rate: ~100 cc/min

Ref.: Zaidel’ & Shreider, VUV Spectroscopy

Water Vapor. Oxygen.

C.Woody, Nashville Collaboration Meeting, 6/11/03 10

Absolute Quantum Efficiency of CsI photocathodes

0.1

1

10

100

1140 1200 1260 1320 1380 1440 1500 1560 1620 1680 1740 1800

Wavelength [Angstroms]Q

ua

ntu

m E

ffic

ien

cy

(%)

Smpl. 1: Al, 0.54 microns

Smpl. 2

Smpl. 1: Cu+Ni+Au, 0.66 microns

Smpl. 2

CsI PMT

Comparison of our CsI photocathodes with a calibrated CsI PMT

Good quality CsI photocathodesare now being made at Stony Brook

Stack with Au coated GEM foil for depositing

CsI photocathode

VUV Spectrometer

C.Woody, Nashville Collaboration Meeting, 6/11/03 11

TPC Field Cage Design

Question: How uniform can we make the drift field and how large are the electric field distortions near the edges and

in the vicinity of the HBD ?

Autocad geometry MAXWELLNot so easy….

Also try 2D calculation using GARFIELD

N.Smirnov

C.Woody, Nashville Collaboration Meeting, 6/11/03 12

Drift Field Distortions

N.SmirnovGARFIELD MAXWELL

EZ / <EZ> ER / <ER>

R

Drift field distortions are generally < 1%

C.Woody, Nashville Collaboration Meeting, 6/11/03 13

Electric Field Distortions Near the HBD

30 cm

mini TPC field cage wires

3 mm 5 cm

-36 kV 0 V

0 V

+ 75 V

wire plane with 5 mm step

N.Smirnov

Initial indications are that the electric field distortions in the region of the

HBD are small, but we need to do more calculations

ED, V/cm

ER, V/cm

C.Woody, Nashville Collaboration Meeting, 6/11/03 14

Tracking Issues

Need to begin serious simulation work on pattern recognition, track finding

and track fitting using tracking information from all PHENIX detectors

(present and future - VTX and TPC)

V. Rykov

++ Configuration B = 9 KG

Momentum resolution for various combinations of the VTX and TPC

TPC would be used for tracking not only in the electron pair measurement in conjunction with the HBD, but also as an additional tracking detector in

normal field running.

Helps in rejecting false high PT tracks and provides good stand alone

tracking for tracks presently outside the PHENIX acceptance (useful for jet

measurements)

C.Woody, Nashville Collaboration Meeting, 6/11/03 15

Is this PHENIX or STAR ?

J.Mitchell’s event display of the PHENIX TPC for a central Au-Au event

(PISA simulation)

Investigating TPC pattern recognition

software from LBL (LC) and

STAR (Level 3)

C.Woody, Nashville Collaboration Meeting, 6/11/03 16

Readout Electronics

Currently reading out GEM TPC with 100 MHz FADC(SIS 3300 8 channel, 12 bit VME module)

pDAQ courtesy of M.Purschke

FADC readout (10 ns bins) Digital scope trace

55Fe source with 10x10 cm2 triple GEM

C.Woody, Nashville Collaboration Meeting, 6/11/03 17

Future HBD/TPC readout electronics developmentTry and utilize existing or soon to be available components

HBD needs only modest (~ few ns) time resolutionPerhaps can use FADC to provide time information

32 ch preamp/shaper for APD readout0.18 mm CMOS, 125 mW per chip

Final ASIC 4.3 x 1.6 mm2

65 MHz FADC available soon

18

TPC and HBD electronics

R&D:

1) can use the same type of electronics for both HBD and TPC ???

(by fitting ADC samples to get T0)

2) TPC FEE issue:

Heat load and high channels count

=> custom ASIC or commercial ADC+ FPGA

In the next few months we will

construct a possible commercial ADC + FPGA for the TPC readout solution base on Analog Device 4 channel 8 bit ADC (chips scale BGA serial ADC)

This is to understand power + readout + packing density issues

This will also serve as preliminary study for the HBD readout…

TPC FEE: Samples signal every 25ns for 140 samples. need L1 delay buffer (160 samples) +

5 events buffers (700 samples)HBD FEE: Need to measure charge and time

(~ several ns) L1 delay buffer + 5 events buffers.

C.-Y.Chi, Nevis

19

For TPC FEE :60K to carry out TPC FEE study + 20 K (M&S)

1) study commercial IC solution2) study the issues regard to custom ASIC

a) follow ALICE path – buy ADC core + custom Logicsb) fully custom ASIC ( need to use commercial library)

3) building prototype modules ( commercial solution) or custom ASIC prototype

For HBD FEE:40 K on salary + 20K (M&S) - Part of works on done from TPC FEE R&D

1) prototype readout For DCM:

80K on salary + 20K (M&S)R&D on DCMwork out readout method for prototype detectors readout

Assumptions:

we need to 1) readout HBD prototype end of next year

2) readout various prototype detector 1.5 years from now

R&D Requests From Nevis

C.-Y.Chi, Nevis

C.Woody, Nashville Collaboration Meeting, 6/11/03 20

TPC Prototype - Starting Next Year

• Full size module• Tests field cage design• Tests materials to be used in actual construction • Allows testing with cosmic rays• Provides structure on which to design and study readout plane• Provides excellent test bench for readout electronics

C.Woody, Nashville Collaboration Meeting, 6/11/03 21

R&D Plan

FY2003• Complete TPC drift cell and begin comprehensive gas studies • Test new 3M GEM foils• Continue to improve TPC field cage calculation• Begin TPC prototype design• Measure CsI quantum efficiencies w/GEMs + radiator gases• Measure CF4 Cherenkov efficiency + scintillation (NSLS)• Begin design of HBD & TPC readout electronics• Funds: $25K labor + $30K equipment

FY2004• Build and test TPC & HBD prototypes • Hopefully complete design of HBD readout electronics and continue design of TPC electronics.• Start engineering design of TPC/HBD detector system• Funds: $200K HBD + $200K TPC

C.Woody, Nashville Collaboration Meeting, 6/11/03 22

Extra Slides

C.Woody, Nashville Collaboration Meeting, 6/11/03 23

HBD Budget

HBD Construction Costs Total Total + C FY04 FY04+C FY05 FY05+C FY06 FY06+C

Working Prototype 200 200 200 200

UV detector 250 375 100 150 150 225Design (6 Man Months) 25CsI photocathodes 5016 mesh frames 15GEMs 16x3 13016 PCB on honeycomb 20Connectors, resistors capacitors 10

Radiator and support structure 150 225 50 75 100 150

Gas system 150 225 50 75 100 150

Electronics 500 750 150 225 350 525Engineering 250Prototype chip run 100Final chip run 100FEMs + DCMs 50

Total detector costs 1250 1775 200 200 350 525 700 1050Contingency 50 %

C.Woody, Nashville Collaboration Meeting, 6/11/03 24

R&D Proposal Budget RequestCategory Description FY03 ($K) FY04($K) FY05($K)

Salaries Post Doc 45 45 45(incl. fringe) Electrical Engineer (1.0-1.25 FTE) 100 125 125

Electrical Tech (0.25 FTE) 20 20 20Mechanical Engineer (0.25 FTE) 25 25 25Mechanical Designer (0.25 FTE) 20 20 20Mechanical Tech (0.25 FTE) 20 20 20

Supplies Lab equipment 30 20 15Electronics ASIC fabrication 30 60 75

Test equipment 15 25 15Total 305 360 360Total (incl 40% overhead) 427 504 504

PHENIX Institutional Involvement

• HBD BNL, WIS, Stony Brook• TPC BNL (Physics, Instrumentation), Tokyo, FIT• Electronics BNL Instrumentation, Columbia (Nevis)

Related R&D Efforts

• STAR (joint effort)• LEGS TPC• TPC w/GEM readout for NLC/TESLA

C.Woody, Nashville Collaboration Meeting, 6/11/03 25

Upgrade Budget and Timeline

C.Woody, Nashville Collaboration Meeting, 6/11/03 26

Possible Support Structure for HBD/TPC/VTX

H.Van Hecke