alice-lhcc review january 29-30, 2001 thomas c. meyer/ep-ait1 general layout four separate vessels:...

ALICE-LHCC Review January 29-30, 2001

Thomas C. Meyer/EP-AIT 1

General LayoutGeneral Layout

Four separate vessels:– Outer containment vessel– Inner containment vessel– Outer field cage vessel– Inner field cage vessel

Two end plates for readout

Pb Pb

E

E

CO2 Insulation GapDrift Volume

End Plate Central Electrode



Design ObjectivesDesign Objectives

Provide high stability and uniformity for:Gas gain (>104): 0.5%Drift field (400 V/cm): Er/Ez < 10-4

Temperature: T < 0.1 ºCDrift gas purity: 5 ppm O2, 10 ppm H2O

Provide high mechanical precision for:Central electrode: 250 µmReadout plane: 250 µm



Technical ProgressTechnical Progress

The FC prototype has undergone intensive testing during the past two years:– Individual components (electrical, mechanical, gas)– System behavior (FC + NA35 readout chamber,

cosmics & laser runs)

Laboratory results certify the required performance of the FC in terms of field quality.

High radiation test in CERES area:– Check stability under ‘realistic’ conditions– Exposed FC to proton and Pb beams



Test-Setup in CERES ZoneTest-Setup in CERES Zone

CERES Detector

Multiplicity Array

p, Pb beams

FC Prototype



High Intensity: Proton RunsHigh Intensity: Proton Runs Direct exposure to proton beam:

– Locally irradiated area (1-4 cm2) near central electrode:

Stable up to 100 kV

CERES p-beam: 2.5 x 105/cm2 s (3 x 105 with Pb target)ALICE: 360/cm2 s

CERES Detector

Multiplicity Array

p

FC Prototype



High Intensity: Pb-Ion RunsHigh Intensity: Pb-Ion Runs Exposure to secondaries from Pb beam:

– Global irradiation of entire cylinder

Stable to ≤ 60 kV!

CERES Pb-beam: 6000/cm2 s (secondaries)ALICE: 360 /cm2 s

CERES DetectorPb

FC Prototype

MultiplicityArray



Material Tests: HygroscopyMaterial Tests: Hygroscopy Check crucial material of field cage for hygroscopic

behavior:

– Kevlar (skins)– Carbon fiber (skins)– Glass fiber (skins)– Makrolon (rods)

Pre-condition material Choose glass fiber

instead of KevlarDrying

-250

-200

-150

-100

-50

0

50

-250

-200

-150

-100

-50

0

50

0 100 200 300 400 500

TEMPERATURE STABILIZATION : +/- 0.4 CPRECISION OF MEASUREMENT : +/- 10 μm

L/L

[µ

m/m

]

T [min]

Macrolon

Carbon Fiber

Kevlar Fiber

Glass Fiber

Wet



Material Tests: TedlarMaterial Tests: Tedlar Does Tedlar provide an efficient moisture barrier?

– Sandwich sample exposed to water-saturated air at 29 ºC on both sides:

Nomex® Honeycomb

KevlarPrepreg

Tedlar

• Maximum possible water absorption by matrix is 6% of sample weight, i.e. 13.2 g.

• After 18 days of exposure, no weight increase was observed.

• Reverse test is ongoing, i.e. the sandwich is placed in a 100% dry atmosphere.



Problems & Risks: MaterialProblems & Risks: Material

Material tests basically finished.– Kevlar fallback: glass fiber (included in

tender) Slightly cheaper More mass (<10% of total)

– Tedlar fallback: none! Aging tests planned (≥ 1 year)

– Macrolon rods replaced by ceramics? Very expensive (material and machining)



Cooling Tests: Resistor ChainCooling Tests: Resistor Chain

Four internal resistor chains supply the appropriate potentials to the strips.

Their power consumption is 60W each. This leads to temperature gradients

inside TPC of »0.1 °C.

Must cool the voltage divider!



Resistor Chain: ConceptResistor Chain: Concept

Voltage divider is placed inside rod. Liquid coolants to remove waste heat. First test with water successfully

finished, as proof of principle.



Resistor Chain: Test-SetupResistor Chain: Test-SetupThe Thermal Box

Resistor Rod



Resistor Chain: ResultsResistor Chain: Results

flow - temperature

18

18.5

19

19.5

20

20.5

21

0 100 200 300 400 500 600

flow [l/h]

inside 1 IN inside 2 inside 3 inside 4 inside 5 OUT

Achieve negligible temperature gradient inside rod:

Pt 1 Pt 2 Pt 3 Pt 4 Pt 5H2O in

H2O



Resistor Cooling: Next StepsResistor Cooling: Next Steps We have verified that water and silicon fluid FL 200/5 remove

heat equivalent to 60 W, as expected. For HV operation, only non-polar liquids can be used:

The liquid must be compatible with the rod material.

CoolantDensity[kg/cm3]

Viscosity[m2/s]

Heat Capacity[J/kg °C]

Flow[l/h]

H2O 998 .00114 4190 516

Silicon Fl 200/5 913 .000055 1632 1450

Shell Diala 882 .00042 1850 1320

C5F12 1630 .00046 1050 1260

C6F14 1680 .00067 1050 1220



Problems & Risks: ChargingProblems & Risks: Charging

Understand field cage charging under high radiation load:– Examine field cage in laboratory:

Bleed 300 MBe of 83Kr into field cage gas to simulate charged particle flux.

Separate tests for drift and insulation volume.

– Increase number of guard rings.– Eventually repeat beam test.



Problems & Risks: CoolingProblems & Risks: Cooling

The resistor rod is a high risk item...– Choose liquid that is safe for apparatus.

No chemical decomposition, dissolution etc.

– Run circuit below atmospheric pressure. Absolutely no leaks, cracks, capillary effects!

– Tight quality control.– If all fails, use gas as coolant:

Double walled cooling circuit; Needs additional, extensive testing.



Stability Study: Why?Stability Study: Why?

ITS Induced Forces

-500

0

500

1000

1500

2000

2500

3000

1 2 3 4 5 6 7 8 9 10 11

Load Cases for TPC

Series1

Series2

Series3

Series4

C1

C2

C3

C4

Weights [N]:120020004000

2 RailsITS + Vac. Ch.Services

C1 C2 C3 C4ITS

TPC Inner Vessels

ITS and beam pipe are supported by TPC.TPC moves (!) out for ITS interventions.

Deformations must not harm TPC and ITS.



FEA: Critical AreaFEA: Critical Area

Nomex® HoneycombKevlar®

Fiber

Tedlar®

Tedlar®

Aluminum

Aluminum

Transition from solid Al flange to laminar composite structure

Aluminum

Carbon-Fiber-Nomex-Composite

1.2 MPa

8.4 MPa4.8 MPa

10.8 MPa

Equivalent shear stress (van Mises) indicates

critical zone



FEA: ResultsFEA: Results Buckling:

– No buckling modes induced until load is increased by a factor of ~ 60.

Stresses:– The critical zone is the transition from flange to

cylinder (“ovalization” under load).– Maximum shear stress in glue joint is

≤ 3 MPa (factor of 6 from failure).– Interlaminar shear stress in composite matrix is ~ 5

kPa (6% risk of delamination)



Problems & Risks: StabilityProblems & Risks: Stability

Flexible joint for central drum?:

Removes load from critical zone Engineering design underway Lower cost than original version

ITS attached here

.

Aluminum

Bellows

Central SectionConical Section

Critical zone



Problems Related to ContractingProblems Related to Contracting Cylinders:

– Only five offers received

– Lowest offer still 3 x higher than budget

End Plates:– Lowest bid exceeds budget by factor of 5

– Splitting of production processes Separate raw material, welding and machining

– Design changes

Alternative scenarios require new tenders– Could lead to delays and increased risks

– Avoid market surveys (6 months delay)



Future ActivitiesFuture Activities R&D and prototyping continues during

construction in 2001:– Entire infrastructure of field cage

Central electrode (3 options) Strips & Rods (4 different types) Gas distribution Alignment

– Tooling and assembly techniques Prepare DELPHI support frame Test facilities (gas, survey, HV, LV, readout)



Project ScheduleProject ScheduleR & D Design & Prototyping Construction & Assembly Physics

Program Chronology of the TPC Project:

We are here!

ID Task Name1 The TPC Field Cage Project

2 R&D and Prototyping

160 TDR

161 Design

178 Issue of contract

179 Fabrication & Construction

181 Inspection & Certification

188 Assembly & Equipment of Field Cage

201 Pre-installation in Zone 2

210 Installation in Underground Area

219 TPC Ready

220

R&D and Prototyping

TDR

Design

Issue of contract

Fabrication & Construction

Inspection & Certification

Assembly & Equipment of Field Cage

Pre-installation in Zone 2

Installation in Underground Area

TPC Ready

1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 41998 1999 2000 2001 2002 2003 2004 2005 2006 2007



Field Cage: SummaryField Cage: Summary Performance

– All technical issues have been studied, certifying the viability of the chosen field cage principle.

Reliability– No serious risks have been identified, except..

charging at high particle flux (tests underway)

Schedule is very tight due to increased in-house production load.

alice-lhcc review january 29-30, 2001 thomas c. meyer/ep-ait1 general layout four separate vessels:...

Documents

meyerepaitresistor chain

meyerepaitmaterial tests

meyerepaithigh intensity

meyerepaitproblems risks

drift field

high radiation test

materialmaterial tests

proton beam