july 28, 2003- mechanical design of the cell - m. konno, univ. of tsukuba 1 1.introduction...

July 28, 2003 - Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba

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1. IntroductionRequirements

2. Details description Design parameters, Cell Design AerogelPMTBox & LidLED Calibration System etc…

3. Performance – KEK test beam, Run3 prototype4. Summary

Mechanical Design Review of the Cell

Aerogel Upgrade Review


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Requirements- Refractive index : n=1.01 – P threshold- Light yield : >10 p.e. – Resolving power- Uniformity of the light yield : Needed. – Easy handling - Occupancy in AuAu collisions : <10% – S/N

1. Introduction

PID in high p-> Cherenkov radiation

Low refractive index-> Silica aerogel


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1-1 Aerogel Location : W1 Sector

(South side)


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RED: AerogelYELLOW: Integration sphereGREEN: PMT

1-2 Detectors Overlook

z (beam) d

irecti

on

azimuthal angle vertex

particle track

- 4.6m from vertex- Coverage ; 3.9 m along z

15 deg. in phi

160 segments


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Basic Design Parameters

- Single Cell Box Design- Integration Cube Type (Aerogel;12cm, Integration;9cm)- Cell size : 11 x 23 cm2

- Cerenkov radiator : Silica Aerogel (SP-12M, Matsushita)- Refractive index : n=1.0114 +/- 0.0008- PMT : R6233-01HA (Hamamatsu)- Integration Cube for Uniformity of the light yield- Reflector : DRP Reflector (Goretex)- Radiation Lengths

2. Details description


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2-0 Cell Design

Reflector (Goretex)

Aerogel

PMT

- Aluminum Box- 0.8mmt- Black Epoxy Joint of the plates Light protection

Integration Cube

- Photo-detection with 2 PMTs- Aerogel part (12cm)- Integration Cube (air, 9cm)- Inner surface covered with Reflector

Efficient light collection ; Reflector Uniformity of the light yield ; Integration Cube


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2-1 Silica Aerogel

Silica Aerogel• SP-12M (Matsushita, Japan)

• Refractive index : 1.0114 +/- 0.0008

• Size : 112.5 x 112.5 x 11.0 mm^3

• Density : 40 mg/cm^3

• Transparent

(64% @ 400nm, 88% @ 550nm for 10mmt )

• Hydrophobic

• Long term stability proved by KEK-Belle.


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PMT R6233-01HA (Hamamatsu)- 3-inch diameter large- Gain : >10^7 at –1500V high gain (Single p.e. peak observed)- Q.E. : 30 % high Q.E.-Dark Current : 2nA low noise

at –1500V(wo/ PreAmp)

1 pe

0 pe

2 pe

2-3 PMT

- Calibrated with LED pulser- Typically ~ 8 p.e. for β=1


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2-3 PMT Base

HV divider with modification- High Gain compared to the standard (*1)- Thinner material

- Less space- Less power (330 mW@1500V) than the standard (*2)

Note *1 : “2-2-1-1-1-1-1-1” => “1-1-1-1-1-1-1-1”

Note *2 : 330k-ohm => 680k-ohm


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2-3 PMT Base (Heating test)

Due to heat dissipation from the divider resistance,the temperature inside the box increased by only ~3 degree.

No-ventilatedHV = -1.5kV

Gas flow is not necessary particularly for cooling.

Measurement

Calculation

Heat calculation is consistent with the measurement. (see Apped-A of CDR)


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2-3 PMT Base (HV test)

-3.2kV for 10 hours

- Electric non-conductance

Measurement items

No smoke, No heat, No electric sparks

- Long-sustained stability

- Idling current

PMT Base is well-working and stable.


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2-4 Mu-metal shield (Probing and Test)

B-field at the place where the aerogel counters will be installed ; 2~8 Gauss.

Uniform field

Thickness & Size of the mu-metal shield has been optimized using Helmholz Coil.


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2-4 Mu-metal shield (Test Results)

Enough Shielding Solution ;0.5mm thick, 80mm long.

- 0.2mm-thick shield is not enough even with 120 mm long.- 40mm-long shield is not enough even with 0.5mm thick.

Normalized ADCTDC Sigma Number of p.e.


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2-5 Reflector (Selection)

Reflector #peAttenuation　

Length [cm]

Goretex 11.78 6.5±0.3

Lumirror 10.2 6.9±0.4

Tetratex 9.8 6.3±0.4

Tyvek （ Double ） 9.1 5.8±0.2

AluminizedMylar

5.3 4.4±0.2

BlackPaper 2.0 2.6±0.1

Distance from PMT

Goretex is the best.

(n=1.017)


15Wavelength [nm]

5000x SEM of DRP®

Reflector

2-5 Reflector (Properties)

-DRP Reflector (“Goretex”)- High diffuse and reflective- PTFE (0.5mmt)- Reflectance > 99%


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2-6 Box (Drawing)


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2-6 Box (Details)

ReV.C


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2-6 Box (Production)

According to the drawings, Boxes have been produced in Dubna.


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2-6 Box (Shipping to BNL)


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2-6 Box (Lid with PMTs)

(Run3 prototype)


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2-6 Box (Inner Box)

- Mylar film for Support - Goretex sheet lined- Silica Aerogel loaded

Inner Box loaded into Aluminum Box

- Aerogel is Very fragile- Careful handling needed


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2-8 LED Calibration System

Numbers- 1 PPG- 3 Drivers- 20 Dividers- 160 LEDs


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ADC

TDC

（ ~ 10 p. e.）PMT ｓｉｇｎａｌ

Gate

Information of chargeInformation of charge

Information of timeInformation of time

(Blue LED source)

2-8 LED Calibration System (Test Result)


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2-9 Gas Flow

Requirements- Gas delivery system- Clean gas- Light tight and air tight- Low flow rate

Purposes- Purging outgas -- While Aerogel is hydrophobic,

some chemical vapor might damage it.- Non-flammability -- For safety. Aerogel is very expensive.- Cooling -- Indeed, temperature rise can be ignored (~3 deg).

Gas connector with black color (Light protection needed)


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2-10 Table of Radiation Lengths

MaterialThickness

[cm]

Radiation

Length [cm]

Radiation

Length [%]

Aerogel 12.0 539.6 2.24

Aluminum 0.08 8.9 0.89

Goretex 0.05 15.8 0.32

G10 0.20 16.4 1.22

Mylar 0.01 31.1 0.03

Mu-metal 0.05 1.5 3.33

PMT Glass 0.20 12.4 1.61

PMT Base 0.20 16.4 1.22

Total - - 10.89

Overall Lrad ~ 19.2%

PISA


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Particle selection by TOF(2GeV/c, positive)

3. Performance – KEK test beam

- Clear separation of protons and pions observed.- Amount of photons other than Are

ogel Cherenkov is small.

Pions~6.6 p.e./PMT

Protons~0.4 p.e./PMT

π

Kp d

(n=1.0114)


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It is Cherenkov Emission.

2

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2max1

1p

pm

nNN

Light yield vs Momentum (n=1.017) Light Yield vs Refractive index

PHENIX Aerogel n=1.0114

3-1 Cherenkov emission in Aerogel


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X

Beam

(0,0)

15cm

15cmPMT1PMT2

Y

Y

X

Beam

(0,0)

11.5cm

21cm

PMT1

PMT2

Y

X

Beam

(0,0)

22cm

12cmPMT1PMT2

Aerogel

PMT PMT

BEAM

Air12cm

12cm

12cm

AerogelPMT PMT

BEAM

12cm

12cm

3-2 Cell geometry

(n=1.017)


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λａ

ｂｓ

λ ｓｃｔ

BEAM

beam datasimulation

3-3 Optical Simulation - Understanding -


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Y

X

Beam

(0,0)

23cm

11cmPMT2PMT1

3-4 Integration Cube Type – Final prototype -

Positional Uniformity

of the light yield

Gap between aerogel tiles

(Aerogel;12cm, Integration;9cm)

(n=1.0114)


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• Not significant difference observed.

• Easy to stack with the Integration Cube Type.

3-5 Counter orientation

•~10% diff. Between upstream/downstream, •Due to diffusive nature of aerogel

PMTs upstream

PMTs downstream

(n=1.0114)

(Aerogel;12cm, Integration;9cm)


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3-6 Timing information

Scope image

- Propagation time : ~ 7 ns (t=0 is defined as the time of PMT hits.)- Max. 2 ns difference observed between PMT1 and PMT2.


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3-7 Background Rejection (1)

By using the timing and amplitude of signals, events in hitting PMT can be distinguished.

Not only with the tracking, PMT hit is self detectable.

(By One PMT)

~7 ns

Aerogel Hit

PMT Glass Window HitTDCADC


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3-7 Background Rejection (2)Hit PMT (blue)Opposite PMT (yellow)

By using the timing and amplitude of signals, events in hitting PMT can be distinguished.

Not only with the tracking, PMT hit is self detectable.

(By Pair PMTs of the same box)


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Boxes – built in DUBNA, Russia (JINR, A.Litvinenko)

Aerogel, PMT’s, Bases – Tsukuba

Final Assembly – M.Lenz at BNL

3-8 Run 3 – prototype test (1)


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Coincidence probability : 56 % (=111/199)

LED

Physics (coincidence)

Physics (uncorrelated) TDC97

TDC99 TDC99

TDC97111 cnts 199 cnts

197 cnts

3-8 Run 3 – prototype test (2)

• Aerogel Cherenkov Counter works well.

• Waiting for pp production to see track association with other tracking detector.


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4. Summary

Integration Cube Type (Aeroegl;12cm, Integration;9cm)

We use the Mu-metal shield which is 0.5mm thickness and 80mm length.

As reflector, Goretex is the best choice.

LED is used to Calibrate PMTs in the counter.

Gas flow is not necessary particularly for cooling, but might prevent chemical vapor from damaging aerogel.

The overall radiation length of the ACC is about 19.2% by PISA simulation.

We have very uniform response of the light yield with Integration Cube Type.

By using the timing and amplitude of signals, events in hitting PMT can be

distinguished.


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*1 ; Voltage distr. (1-1-1-1-1-1-1-1)

Appendix - PMT (Parameters)

Sp


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Appendix - PMT Base


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Appendix - Connectors & Cables

Connectors (Nylon)- Signal transmission- HV Supply- LED for Calibration

Cables- RG174/U (PMT Base -> PreAmp)- HV Cable- UL-E108898 (LAN cable, cat.5)

Flammability ratings ; UL 91V-0 UL 94V-0

july 28, 2003- mechanical design of the cell - m. konno, univ. of tsukuba 1 1.introduction...

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