Proposal for IHEP participation in CBM ECAL Yuri Kharlov Institute for High Energy Physics Protvino 5 November 2004 CBM-Russia meeting

Outline Scintillator sampling calorimeters manufactured in IHEP IHEP plastic scintillator facility Simulations and data analysis 5 November 2004 CBM-Russia meeting

Scintillator calorimeters IHEP has a long history of electromagnetic and hadron calorimetry contributed to many of HEP-experiments. Different types of e.m. calorimeters were manufactured in IHEP: Cherenkov calorimeters (lead glass) Scintillator sampling calorimeters Scintillating crystal calorimeters (PbWO4) Scintillator sampling calorimeters: 1985: invention of the molding technology 1988: first “shashlyk” R&D with INR 1992: PHENIX ECAL (BNL, RHIC) 1993-1995: HERA-B ECAL (DESY, with ITEP) 1994: DELPHI STIC (CERN, LEP) 2000: COMPAS HCAL (CERN, SpS) 2001: ATLAS HCAL (CERN, LHC) 2004: LHCb HCAL (CERN, LHC) 2000-200?: KOPIO (BNL, AGS) 5 November 2004 CBM-Russia meeting

E.M. calorimeter in PHENIX PHENIX Tech. Note 236, 06/96 R&D: 1994 Typical sampling lead-scintillator calorimeter of 15,552 channels 66 sampling layers DE/E=8% at 1 GeV Time resolution = 100 ps 36 fibers of WLS-doped polysterene penetrate the modules Modules are assembled into 6x6-array supermodules 5 November 2004 CBM-Russia meeting

E.M. calorimeter STIC in DEPLHI NIM A 425 (1999) 106 Small angle Tile Calorimeter for luminosity monitoring 47 Pb(3mm)-Sci(3mm) layers 2 Si strip detectors inserted after 7 and 13 sampling layers to measure shower development 1600 WLS fibers (0.79 fiber/cm2) DE/E=3% at 45 GeV Df=1.5 Dr=0.3-1 mm 5 November 2004 CBM-Russia meeting

E.M. calorimeter in KOPIO First prototype for KOPIO (INR, Troitsk): 240  (0.35 mm lead + 1.5 mm scint.) Energy resolution 4%E(GeV). (for 1 GeV/c positron) Contributions to the energy resolution: E865 E923 KOPIO prototype To achieve the energy resolution of 3%E(GeV) the sampling, photo-statistics and light collection uniformity have to be improved Test beam results and the simulation model is described in NIM A 531 (2004) 476 Economy: adequate performance for ~1/10 cost of crystals 5 November 2004 CBM-Russia meeting

KOPIO: 3%/E CALOR 2004, Perugia, Italy, March 29-April 2, 2004 Lateral segmentation 110110 mm2 Scintillator thickness 1.5 mm Gap between scintillator tiles 0.300 mm Lead absorber thickness 0.275 mm Number of the absorber layers (Lead / Scint) 300 WLS fibers per module 72  1.6 m = 115 m Fiber spacing 9.3 mm Holes diameter in Scintillator / Lead 1.3 mm / 1.4 mm Diameter of WLS fiber (Y11-200MS) 1.0 mm Fiber bundle diameter 14.0 mm External wrapping (TYVEK paper) 150  Effective Xo 34.0 mm Effective RM 59.8 mm Effective density 2.75 g/cm3 Active depth 540 mm (15.9 Xo) Total depth (without Photodetector) 650 mm Total weight 18.0 kG 5 November 2004 CBM-Russia meeting

KOPIO: Calorimeter module The design innovations: New scintillator tile (BASF143E + 1.8%pTP + 0.04%POPOP produced by IHEP) with improved optical transparency and improved surface quality. The light yield is now ~ 60 photons per 1 MeV of incident photon energy. Nonuniformity of light response across the module is <2.3% for a point-like light source, and < 0.5% if averaged over the photon shower.. New mechanical design of a module has four special "LEGO type" locks for scintillator’s tiles. These locks fix the position of the scintillator tiles with the 300-m gaps, providing a sufficient room for the 275 m lead tiles without optical contact between lead and scintillator. The new mechanical structure permits removing of 600 paper tiles between scintillator and lead, reduces the diameter of fiber’s hole to 1.3 mm, and removes the compressing steel tape. The effective radiation length X0 was decreased from 3.9 cm to 3.4 cm. The hole/crack and other insensitive areas were reduced from 2.5 % up to 1.6 %. The module’s mechanical properties such as dimensional tolerances and constructive stiffness were significantly improved. New photodetector Avalanche Photo Diode (630-70-74-510 produced by Advanced Photonix Inc.) with high quantum efficiency (~93%), good photo cathode uniformity (nonuniformity  3%) and good short- and long-term stability. A typical APD gain is 200, an excess noise factor is ~ 2.4. The effective light yield of a module became ~24 photoelectrons per 1 MeV of the incident photon energy resulting in negligible photo statistic contribution to the energy resolution of the calorimeter. 5 November 2004 CBM-Russia meeting

KOPIO: light yield in scintillator Scintillator: PS+Fluor1+Fluor2, Manufacturer Light yield (% of Anthracene) Attenuation Length (cm) Light yield of MIP, p.e. per tile Simulated light collection efficiency PSM115+1.5%pTP+0.04%POPOP, TECHNOPLAST, 1998 53  6 4.0  0.3 4.4  0.3, 100% 0.134  0.013, BASF158K+1.5%pTP+0.04%POPOP, IHEP, 2001 56  6 4.9  0.4 5.6  0.3, (127  10)% 0.170  0.017, (127  13)% BASF165H+1.5%pTP+0.04%POPOP, 6.1  0.5 6.4  0.3 (145  10)% 0.191  0.019, (143  14)% BASF143E+1.5%pTP+0.04%POPOP, IHEP, 2002 54  6 6.8  0.5 7.1  0.3, (161  10)% 0.215  0.021, (160  16)% Light yield variation over tile’s samples 5 November 2004 CBM-Russia meeting

KOPIO: light collection in the tile Tile (face view) 5 November 2004 CBM-Russia meeting

KOPIO: energy resolution Energy resolution for 220-370 MeV photons: 5 November 2004 CBM-Russia meeting

KOPIO: time resolution Time difference in two modules was measured 5 November 2004 CBM-Russia meeting

KOPIO: photon detection inefficiency Simple estimate of Inefficiency (due to holes): Effect of holes is negligible if incident angle > 5 mrad 5 November 2004 CBM-Russia meeting

Calorimeter readout Readout systems (photo-multipliers and high-voltage system) were provided by IHEP for PHENIX (16 000 channels), HERA-B (6000 channels); LHCb (6500 ECAL+1800 HCAL channels); IHEP together with MELZ is working on modernization of the photo-multipliers PMT115M with low rate effect. First prototypes with stability 1% at I=20mA were produced. 5 November 2004 CBM-Russia meeting

Plastic scintillator facility in IHEP http://www1. ihep The research and development program of plastic  scintillators started in IHEP more than 20 years ago. The works were concentreted in the following directions: the production of polysterene scintillators using the process of styrene polymerization in blocks; the extrusion of bulk-polymerized scintillators from blocks; the production of molded scintillators by the injection molded technique. Scintillators manufactured be methods 1 and 2 were tested and used in domestic experiments at IHEP as well as some experiments abroad With the help of method 3, large volumes of scintillators for several experiments in IHEP (~3 tons) and for hadron calorimeters Hcal1 and Hcal2 of experiment in COMPASS (~2 tons) were manufactured. During the last decade the demand on molded scintillators for various projects (PHENIX, HERA-B, ATLAS, LHC-b) have inceased up to several tens of tons per year. Production time scale: 15 tons of scintillators (>750,000 plates) for KOPIO could be manufactures in 1.5 years. 5 November 2004 CBM-Russia meeting

Plastic scintillator facility in IHEP   Plastic scintillator facility in IHEP Injected mold machime in automatic processing of the tiles. Injected mold scintillator production facility 3x3 module for KOPIO Plates for KOPIO 5 November 2004 CBM-Russia meeting

ECAL simulations and data analysis IHEP group has experience in e.m. calorimeters simulations and data analysis, particularly in heavy-ion experiments (PHENIX, STAR, ALICE) which should be similar to CBM in complexity. Calibration Shower shape measurements Shower reconstruction Particle identification (photons, electrons, hadrons) Physics analysis 5 November 2004 CBM-Russia meeting

ECAL calibration Before calibration After calibration Calibration by wide electron beam with minimization of the mean quadratic deviation Before calibration After calibration 5 November 2004 CBM-Russia meeting

Shower shape measurement (PbWO4 calorimeter) 5 November 2004 CBM-Russia meeting

Particle identification PID in ECAL based on: Shower shape TOF Charge track matching Good identification of photons, electrons, charged and neutral hadrons, (anti)nucleons. GEANT3 simulation for PHOS, ALICE  e- p- anti-n 5 November 2004 CBM-Russia meeting

p0 spectrum and background subtraction (Pb-Pb at 5.5 ATeV) 5 November 2004 CBM-Russia meeting

IHEP contribution to CBM ECAL Participating together with other member institutes in Defining physics motivation for ECAL in CBM; Conceptual desing of ECAL; R&D: Detailed simulation to optimize ECAL parameters; Beam-tests of the prototypes in IHEP and GSI; ECAL readout (PMT+HV system); Monitoring system; Data analysis; Full responsibility for manufacturing of the ECAL modules (Pb-Sci sampling). 5 November 2004 CBM-Russia meeting