July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba 1 1.Introduction Requirements 2.Details description Design parameters, Cell Design Aerogel PMT Box & Lid LED Calibration System etc… 3.Performance – KEK test beam, Run3 prototype 4.Summary Mechanical Design Review of the Cell Aerogel Upgrade Review

July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba 2 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

July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba Aerogel Location : W1 Sector ( South side )

July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba 4 RED: Aerogel YELLOW: Integration sphere GREEN: PMT 1-2 Detectors Overlook z (beam) direction azimuthal angle vertex particle track - 4.6m from vertex - Coverage ; 3.9 m along z 15 deg. in phi 160 segments

July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba 5 Basic Design Parameters - Single Cell Box Design - Integration Cube Type (Aerogel;12cm, Integration;9cm) - Cell size : 11 x 23 cm 2 - Cerenkov radiator : Silica Aerogel (SP-12M, Matsushita) - Refractive index : n= / PMT : R HA (Hamamatsu) - Integration Cube for Uniformity of the light yield - Reflector : DRP Reflector (Goretex) - Radiation Lengths 2. Details description

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

July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba Silica Aerogel Silica Aerogel SP-12M (Matsushita, Japan) Refractive index : / Size : x x 11.0 mm^3 Density : 40 mg/cm^3 Transparent 400nm, 550nm for 10mmt ) Hydrophobic Long term stability proved by KEK-Belle.

July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba 8 PMT R HA (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

July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba PMT Base HV divider with modification - High Gain compared to the standard (*1) - Thinner material - Less space - Less power (330 than the standard (*2) Note *1 : “ ” => “ ” Note *2 : 330k-ohm => 680k-ohm

July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba PMT Base (Heating test) Due to heat dissipation from the divider resistance, the temperature inside the box increased by only ~3 degree. No-ventilated HV = -1.5kV Gas flow is not necessary particularly for cooling. Measurement Calculation Heat calculation is consistent with the measurement. (see Apped-A of CDR)

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

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

July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba Mu-metal shield (Test Results) Enough Shielding Solution ; 0.5mm thick, 80mm long mm-thick shield is not enough even with 120 mm long. - 40mm-long shield is not enough even with 0.5mm thick. Normalized ADC TDC Sigma Number of p.e.

July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba Reflector (Selection) Reflector # pe Attenuation Length [cm] Goretex ±0.3 Lumirror ±0.4 Tetratex9.86.3±0.4 Tyvek （ Double ） ±0.2 Aluminized Mylar ±0.2 BlackPaper2.02.6±0.1 Distance from PMT Goretex is the best. (n=1.017)

July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba 15 Wavelength [nm] 5000x SEM of DRP® Reflector 2-5 Reflector (Properties) -DRP Reflector (“Goretex”) - High diffuse and reflective - PTFE (0.5mmt) - Reflectance > 99%

July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba Box (Drawing)

July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba Box (Details) ReV.C

July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba Box (Production) According to the drawings, Boxes have been produced in Dubna.

July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba Box (Shipping to BNL)

July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba Box (Lid with PMTs) (Run3 prototype)

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

July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba LED Calibration System Numbers - 1 PPG - 3 Drivers - 20 Dividers LEDs

July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba 23 ADC TDC （ ~ 10 p. e. ） PMT ｓｉｇｎａｌ Gate Information of charge Information of time (Blue LED source) 2-8 LED Calibration System (Test Result)

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

July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba Table of Radiation Lengths Material Thickness [cm] Radiation Length [cm] Radiation Length [%] Aerogel Aluminum Goretex G Mylar Mu-metal PMT Glass PMT Base Total Overall Lrad ~ 19.2% PISA

July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba 26 Particle selection by TOF (2GeV/c, positive) 3. Performance – KEK test beam - Clear separation of protons and pions observed. - Amount of photons other than Areogel Cherenkov is small. Pions ~6.6 p.e./PMT Protons ~0.4 p.e./PMT π K p d (n=1.0114)

July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba 27 It is Cherenkov Emission. Light yield vs Momentum (n=1.017)Light Yield vs Refractive index PHENIX Aerogel n= Cherenkov emission in Aerogel

July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba 28 X Beam (0,0) 15cm PMT1PMT2 Y Y X Beam (0,0) 11.5cm 21cm PMT1 PMT2 Y X Beam (0,0) 22cm 12cm PMT1PMT2 Aerogel PMT BEAM Air 12cm Aerogel PMT BEAM 12cm 3-2 Cell geometry (n=1.017)

July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba 29 λ ａｂｓ λ ｓｃｔ BEAM beam data simulation 3-3 Optical Simulation - Understanding -

July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba 30 Y X Beam (0,0) 23cm 11cm PMT2PMT1 3-4 Integration Cube Type – Final prototype - Positional Uniformity of the light yield Gap between aerogel tiles (Aerogel;12cm, Integration;9cm) (n=1.0114)

July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba 31 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)

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

July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba 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 Hit TDC ADC

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

July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba 35 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)

July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba 36 Coincidence probability : 56 % (=111/199) LED Physics (coincidence) Physics (uncorrelated) TDC97 TDC99 TDC cnts199 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.

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

July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba 38 *1 ; Voltage distr. ( ) Appendix - PMT (Parameters) Sp

July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba 39 Appendix - PMT Base

July 28, Mechanical Design of the Cell - M. Konno, Univ. of Tsukuba 40 Appendix - Connectors & Cables Connectors (Nylon) - Signal transmission - HV Supply - LED for Calibration Cables - RG174/U (PMT Base -> PreAmp) - HV Cable - UL-E (LAN cable, cat.5) Flammability ratings ; UL 91V-0 UL 94V-0