Test of Electromagnetic Calorimeter modules for HADES, Mainz Sep.2009

Test of Electromagnetic Calorimeter modules for HADES, Mainz Sep.2009

A. Krása, F. Křížek, J. Pietraszko, Y. Sobolev, J. Stanislav, A. Reshetin,

P. Tlustý• purpose: measure the energy resolution of detector modules with various configurations in g beam at energy 0-1500 MeV • test conditions and setup• results

Test conditions

2 days of measurement:1) Ee- = 855 MeV, Ig = 25 kHz2) Ee- = 1508 MeV, Ig = 5 kHz

Beam: - detectors were positioned in the secondary gamma beam with continuous energy distribution from 0 to primary electron beam energy, with intensity exponentially falling with increasing energy - unless stated otherwise, the detectors were hit in the centre of their front side, and the beam proceeded along their longitudinal axis - beam diameter at detector position – 6 mm diameter

Trigger: OR of signals from 8 selected scintillators in electron tagger – giving events with 8 known gamma energies in range from 0 to energy of the electron beam

Detector modules number lightguide,

wrappingglass wrapping PMT

1 lead glass, mylar mylar EMI9903KB

2 lead glass, paper paper EMI9903KB

3 NO mylar EMI9903KB

4 NO paper EMI9903KB

5 NO mylar HAMAMATSU1949

EMI9903KB: 1.5” tube from MIRAC (WA98)H1949: 2.5” tube from HADES Tofino

Lead glass dimensions: 9.2 x 9.2 x 42 cm

Setup

Trigger: OR of signals from 8 selected scintillators in electron tagger – giving events with 8 known gamma energies in range from 0 to energy of the electron beam

Beam: detectors were positioned in the secondary gamma beam with continuous energy (intensity exponentially falling with increasing energy)

Setup

Left up: test setupLeft down: crewRight: detail with detectors, movable table and beam halo (looking in beam direction)

Results slide

No.1) Example of ADC spectra for Ee- = 1508 MeV, module No.1 72) Energy resolution for run Ee- = 855 MeV 83) Energy resolution for run Ee- = 1508 MeV 94) Energy resolution for run Ee- = 855, 1508 MeV and cosmics for modules No.1-5 10-145) Energy resolution as a function of HV 156) Energy resolution as a function of beam position 167) Energy resolution as a function of beam intensity 17

Measured g spectra ALL E= 1399MeV E= 1210MeV

E= 1021MeV E= 831MeV E= 676MeV

E= 261MeV E= 452MeV E= 72.1MeV

Ee=1508 MeV, g energy spread <= 1%, det. module No.1

ADC channel

coun

ts

Resolution vs. Energy Ee= 855 MeV

resolution ~ k . 1/sqrt(E)

Resolution vs. Energy Ee= 1508 MeV


Resolution vs. Energy Module No.1


LE: Ee= 855 MeVHE: Ee= 1508 MeVcosmics: cosmics muons

Resolution vs. HV Ee= 1508 MeV, module No.1


Resolution vs. beam position

reading only module No.1

reading modules No.1+2

Ee= 855 MeV, module No.1

No.1 No.2

01234

Res. vs. amp. gain and beam intensity

Ee= 1508 MeV, module No.5


a) change of AMP gain – no influenceb) decrease of g beam int. from 25kHz to 5kHz – improvement of resolution by 9%

amplifier saturation

Test of Electromagnetic Calorimeter modules for HADES, Mainz Sep.2009

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