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

• …… ?

MotivationMotivation

- 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)

MotivationMotivation

Eur. Phys. J. C 4, 231-247 (1998)

Eur. Phys. J. C 4, 249-257 (1998)

Side View

START

HADES & EMC

RPC

EMC

The total area required for a HADES calorimeter amounts to about 8m2 !!

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: 1.708 (at 400 nm)

Nucl. Instr. Meth. A290, 76 (1990)

Moduledimensions:42 x 9 x 9 cm

Signal Read-out

PMT Diameter of photocathode

(mm)

XP2262 44

FEU-110-1 63

FEU-139 63

EMI 9903KB 34

PMT - EMI 9903KB (1.5'') from MIRAC (WA98 hadron calorimeter) ~720 PMT'sdiameter – 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. 12600 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. 2008 - test of various PMTsApr. 2009 - test of lightguide

Cosmic test setup

lead glass module

trigger detectors

count rate: ~ 30 particles / hour

Cosmic test – various PMTsPMT Diameter of

photocathode

(mm)

energy

resolution (%)

Number of photoelectrons

XP2262

(from FW)

44 14.4 48

FEU-110-1

63 11.9 70

FEU-139 63 9.4 112

EMI 9903KB

34 10.6 88

σ/Nmean= 10.6 %or Nph.el > 88

Nph.el. ≈ 1/ σ2

EMI 9903KB

Assembling of lead glass modules with lightguide and

PMTOPAL lead glass module 420 mm lengthplexiglass lightguidePMTHV divider

plexiglas lightguidePMT

Cosmic test – PMT pulseswith lightguide without lightguide

Light collection with lightguide in average 3 times worse than direct PMT-glass connectionNew lightguide from lead glass to be tested, better shape?

A ≈ 500 mVcosmic muons correspond to ≈ 400 MeV e-

σ/Nmean= 10.6 %or Nph.el > 88

with lightguide without lightguide

σ/Nmean ≈ 40% without lightguide (Oct 2008)

Cosmic test – ADC spectra

Nph.el. ≈ 1/ σ2

σ/Nmean= 10.6 %

our data

Cosmic muon ADC spectra

http://www.e835.to.infn.it/people/gollwitz/thesis/K. Gollwitzer, PhD thesis, University of California at Irvine, 1993

Fermilab E760 Central Calorimeter

σ/Nmean≈ 7 %

OPAL e- 1 GeV Np.e. ≈ 1800 ≈ 5%

E760 e- 1 GeV Np.e. ≈ 4250 ≈ 5%

E760 ≈ 2 GeV Np.e. ≈ 2082 ≈ 7%

module length 50 cm

Tests - plans

May – June - Cosmic muons, test of lightguide

June – July - Electron beam @ 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 22Na 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 PMTs1500 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