Electromagnetic Calorimeter for HADES at SIS100 Pavel Tlustý, NPI Řež Motivation Plans Current status Tests Outlook HADES Collaboration Meeting, Sesimbra, May 5-10, 2009 May 8, 2009 Involved groups: Jag. University Krakow INR Moscow NPI Rez …… ?

Motivation - measurements of the respective  º and η meson two gamma decay yields together with the dielectron data for the knowledge of dielectron coctail and normalization at incident heavy ion energies 2-8 AGeV - better electron/pion suppression for large momenta (p>400 MeV/c) as compared to the present situation (at lower momenta the electron/hadron identification will be provided by the RICH and RPC)

Motivation Eur. Phys. J. C 4, (1998) Eur. Phys. J. C 4, (1998)

Side View START HADES & EMC RPC EMC The total area required for a HADES calorimeter amounts to about 8m 2 !! ElectroMagnetic Calorimeter (EMC) will replace the HADES Pre-Shower detector (18º< Θ< 45º).

Detector modules Our proposal is to use lead glass modules from OPAL end cap calorimeter. ~ 900 modules needed, at present (April 2009) 1080 modules moved to GSI. Energy resolution ~ 5%/sqrt(E), E in GeV Lead glass properties: - type: CEREN 25 - chemical composition (SiO2 -39%,PbO – 55%, K2 - 2%, Na20 – 3%) - density: 4.o6 g/cm3 - radiation length (X0): 2.51 cm - refractive index: (at 400 nm) Nucl. Instr. Meth. A290, 76 (1990) Moduledimensions: 42 x 9 x 9 cm

Signal Read-out PMTDiameter of photocathode (mm) XP FEU FEU EMI 9903KB34 PMT - EMI 9903KB (1.5'') from MIRAC (WA98 hadron calorimeter) ~720 PMT's diameter – 38 mm (1.5'') diameter of photocathode – 34 mm Front-end readout – ADC ADD-ON (Shower)+ TRB

Design Number of modules 150x6=900 Mass of one module of lead-glass 14 kg Total mass of cal kg E. Lisowski, TU Krakow

Tests Source – cosmics muons: energy ≈ 2 GeV, energy deposit in module ≈ 200 MeV, Cerenkov light output corresponds to ≈ 400 MeV electrons count rate ≈ 30 particles / hour Measurement of pulse height (ADC) spectra – check of energy resolution various PMTs, configuration with/without lightguide Oct test of various PMTs Apr test of lightguide

Cosmic test setup lead glass module trigger detectors count rate: ~ 30 particles / hour

Cosmic test – various PMTs PMTDiameter of photocathode (mm) energy resolution (%) Number of photoelectrons XP2262 (from FW) FEU FEU EMI 9903KB σ/N mean = 10.6 % or N ph.el > 88 N ph.el. ≈ 1/ σ 2 EMI 9903KB

Assembling of lead glass modules with lightguide and PMT OPAL lead glass module 420 mm length plexiglass lightguide PMT HV divider plexiglas lightguide PMT

Cosmic test – PMT pulses with lightguide without lightguide Light collection with lightguide in average 3 times worse than direct PMT- glass connection New lightguide from lead glass to be tested, better shape? A ≈ 500 mV cosmic muons correspond to ≈ 400 MeV e-

σ/N mean = 10.6 % or N ph.el > 88 with lightguide without lightguide σ/N mean ≈ 40% without lightguide (Oct 2008) Cosmic test – ADC spectra N ph.el. ≈ 1/ σ 2

σ/N mean = 10.6 % our data Cosmic muon ADC spectra K. Gollwitzer, PhD thesis, University of California at Irvine, 1993 Fermilab E760 Central Calorimeter σ/N mean ≈ 7 % OPAL e - 1 GeV N p.e. ≈ 1800  ≈ 5% E760 e - 1 GeV N p.e. ≈ 4250  ≈ 5% E760  ≈ 2 GeV N p.e. ≈ 2082  ≈ 7% module length 50 cm

Tests - plans May – June - Cosmic muons, test of lightguide June – July - Electron MAMI response to 100 – 2000 MeV electrons up to 8 modules, various configurations

PMT Tests PMT EMI 9903KB (1.5'') ~720 PMTs available 500 PMTs tested HV dependence of PMT response: PMT alone at HV=1500 and 1700 V, PMT with a gamma-source 22 Na at HV=1200, 1500, and 1700 V; The results for HV=1500 V: <500 mV 79 pieces of PMTs 16% 500 mV < U < 1500 mV 120 pieces of PMTs 1500 mV < U < 2700 mV 191 pieces of PMTs >2700 mV 110 pieces of PMTs

Summary  motivation: improved dilepton spectroscopy by HADES lepton and photon pairs at the same time  current status detector modules available PMT – 70% available, 70% of them tested tests with cosmics going on simulation in progress - see next talk mechanical construction designed  plans tests on electron beam (and cosmics) fixing the detector module setup building one sector building full calorimeter