PID detector and EMC for HIEPAF 邵明，唐泽波 核探测与核电子学国家重点实验室 中国科学技术大学近代物理系

MDC PXD/SSD PID-barrel PID-endcap EMC Coil York/Muon IP 3~6 cm 10 cm 15 cm 85 cm 105 cm 135 cm 185 cm 245 cm 120 cm140 cm190 cm240 cm300 cm 20 

PID Detector

PID detector Key features Enable  /K (and K/p) 3-4  separation up to 2GeV/c Suitable for high luminosity run – fast detector Radiation hard, especially in the endcap region Compact – reduce costs of the outer detectors Modest material budget - <0.5X 0

PID at low momentum Specific energy loss (dE/dx) in the gaseous tracking detector (MDC) can be used for low momentum PID Better dE/dx resolution for longer track length Example: ~6% at BESIII MDC (track length ~0.7m)  clean  /K/p ID for p<0.8/1.1 GeV/c

Time of Flight?  /  =  T/T =  m 2 /2p 2  T =L/c  *  m 2 /2p 2 ~ L/c *  m 2 /2p 2 For  /K/p at p=2GeV/c,  T ~ 0.1ns*L(m) = 100/270 ps at L~1m. So for 3   /K/p separation an overall TOF time resolution ~20/50ps is needed. TOF alone can not identify  /K to p=2GeV/c

Cherenkov detector Cherenkov radiation: Radiation if particle velocity larger than speed of light in medium Commonly used in HEP experiment to identify particles at high momentum Two catalogs – Threshold Cherenkov – simple to build – Imaging Cherenkov: RICH(large momentum range)/DIRC/TOP(most compact)

Baseline Design PID by RICH at 0.8<p<2GeV/c, no TOF Proximity RICH, similar to ALICE HMPID design, but with PHENIX HBD (CsI coated GEM) readout n~1.3 (liquid C 6 F 14 ), UV detection Already proven Immune to B field  same structure at both the endcap and the barrel ALICE HMPID PHENIX HBD

Relevant formulae and figures Take n=1.13/1.3 and N photon =10  ~60/38 mrad single photon resolution is needed for 3   /K separation at p=2GeV/c  correspond to ~20/14mm photon sensor size (with proximity gap T=10cm)

Expected performance Cherenkov angle vs. track momentum in p-Pb data ALICE HMPID Liquid C 6 F 14 radiator 175nm Proximity gap = 80mm readout pad size 8mm  8.4mm 3   /K/p separation up to p=3/5 GeV/c

Alternative Design No TOF, PID by RICH only Similar to BELLE-II ARICH design, Aerogel + Position Sensitive Photon Detector n~1.13 (Below threshold for proton at p<2GeV/c) Already proven at the BELLE-II endcap, how about the barrel part? Need R&D Proximity focusing

BELLE-II ARICH performance double aerogel, n 0 =1.055,1.065 Proximity gap = 200mm  c =336mrad   =15.8mrad N det = 11.4 >5.5 σ  /K separation at 4 GeV/c BELLE-II ARICH ~ 5mm photon sensor size

Radiator index choice No K/p separation at GeV/c n>1.1 to separate K/p Aerogel is a choice in this index range  only , K , K, p  /K MDC K/p MDC

Electromagnetic Calorimeter

MDC PXD/SSD PID-barrel PID-endcap EMC Coil York/Muon IP 3~6 cm 10 cm 15 cm 85 cm 105 cm 135 cm 185 cm 245 cm 120 cm140 cm190 cm240 cm300 cm 20  Crystal + Photosensor

EMC Requirements Good energy resolution Good position/angular resolution Good timing resolution if possible BaBar CsI(Tl) + PIN

Challenging at high luminosity era Radiation damage – Decrease light yield – A function of run time High photon background rate – Produce pile-up – Degrade energy and angular resolution Babar, NIM A479 (2002) krad 1.2 krad Behavior of the light emitted by a crystal due the radiative Bhabha photons

Requirement at high luminosity era Short decay time Radiation hard High signal-to-background ratio

Crystal comparison

Pros and Cons of BSO Pros: Relative fast Radiation hard Emission spectrum peak at 480 nm Small X0 (60% CsI)  more compact Small Moliere Radius (60% CsI)  finer segmentation Low raw material cost (~PWO and 50% BGO, much less than LYSO) Cons: LY smaller than CsI(Tl) and LYSO (however, ~ PWOII at C) Dose rate dependent LY, fast recovery time  LY Calibration system needed Not mature (large size available, mass production not proven)

BSO performance 9 crystals from SICCAS, 2x2x20 cm 3 Measured with XP2262 Caltech

Energy resolution contribution Not only light yield matters 100 p.e./MeV  100 MeV Noise is important at not very high energy CMS PWO E -1 E -1/2

Noise term Energy E photons ElectronsElectronics Crystal Light Yield LY Photosensor Gain G Noise at the readou chain dV dE ~ dV/G/LY/E High gain and high light yield  Smaller equivalent noise energy  Better resolution, especially at low and moderate energy

Photosensors PIN Photodiode Mature Large noise/signal Large Area APD Relatively Mature Large noise/signal Vacuum photopentode New, under developing Low noise, low gain (~10-100) Sensitive to magnetic field Multi-Pixel Photon Counter (MPPC/SiPM) New, under developing High gain (~10 6 ), low ENE, simplify electronics Insensitive to magnetic field Good timing resolution

MPPC/SiPM test Hamamatsu S C 3 x 3 mm 2 Crystal 3 x 3 x 15 mm 2

 ray spectrum MeV MeV MeV

Linearity and resolution BGO

Energy resolution BGO CsI(Tl) A few % resolution achieved at ~1 MeV  ~ 1.26/sqrt(N pe ), still room to improve BGO CsI(Tl)

BGO CsI(Tl) Energy resolution comparison BaBar Cs(Tl)+PIN SuperB LYSO+APD Belle2 pure CsI+PP +SiPM PANDA 0 C+APD

0.511 MeV  energy resolution BGO+SiPM S:13% 8.5% BGO + SiPM: 13%*2.354 = 31% CsI(Tl)+SiPM: 6%*2.354= 14% LYSO+SiPM: 5%*2.354= 12% LSO/LYSO + PMT: 11-21% LSO/LYSO + APD: 26-43% Gate: 1000 ns L.O. = 190 p.e./MeV 2.5 x 2.5 x 20 cm x 0.3 x 1.5 cm 3 SuperB TDR

SiPM/MPPC products sensL 4 x 4 channel array 3 x 3 mm 2 each channel 4774 cells per channel ~ €120 Hamamatsu 4 x 4 channel array 3 x 3 mm 2 each channel 3600 cells per channel ~ ￥ 1500

Summary PID detector – RICH only, no TOF – C 6 F 10 as radiator + CsI-GEM – Aerogel as radiator + HAPD/MPPC Calorimeter – Fast crystal with reasonable LY is needed (BSO, or PWO?) – Photosensor with high gain to overcome LY decrease – MPPC/SiPM significantly suppress the noise term BGO+SiPM : MeV CsI(Tl)+SiPM : MeV Thanks!

Cost? ITP, Beijing, Feb. 19, Zebo Tang, USTC L L SuperB (Italy) Forward EMC cost estimation BSO crystal price expected to be ½ of BGO, ~PWO Cost of Crystal + photosensor + LY calibration system LYSO : Pure CsI : BGO : PWO : BSO 8.1 : 3.1 : (4-5.4) : ( ) : ( ) or 4.0 Pure CsI readout by APD PP 3x price of APD SuperB TDR, 2013

Relevant formula Threshold: Emission angle: Photon yield:

Threshold Cherenkov + TOF Design A threshold Cherenkov detector (  /K), plus a TOF Similar to BELLE ACC design n~1.03, TOF resolution ~90ps Technically simple But need more space to accommodate more materials Plastic scintillator + PMT or MRPC can be used for TOF Threshold Cherenkov detector module

Expected performance n = 1.030,  /K separation GeV/c n = 1.010,  /K separation GeV/c BELLE ACC