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 ~ k . 1/sqrt(E)

Resolution vs. Energy Module No.1

resolution ~ k . 1/sqrt(E)

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

Resolution vs. Energy Module No.2

resolution ~ k . 1/sqrt(E)

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

Resolution vs. Energy Module No.3

resolution ~ k . 1/sqrt(E)

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

Resolution vs. Energy Module No.4

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

resolution ~ k . 1/sqrt(E)

Resolution vs. Energy Module No.5

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

resolution ~ k . 1/sqrt(E)

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

resolution ~ k . 1/sqrt(E)

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

resolution ~ k . 1/sqrt(E)

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

amplifier saturation