Gusev K., JINR , Gerda meeting Spectrometric performance of Kurchatov Institute detectors

Gusev K., JINR , Gerda meeting Detector 1Detector 2Detector 3Detector 4Detector 5 Full mass, kG Depletion voltage, V Bias voltage, V (recommended) FWHM, keV at 1332 keV (specifications) FWHM, keV at full HdMo Set-up Test at February 2005 FWHM, keV at 1332 keV New measurements Bias voltage, V FWHM, keV at 1332 keV

Gusev K., JINR , Gerda meeting Detector 1 Problems: Detector not reaches the recommended voltage Detector has comparatively poor energy resolution Detector had a big cross-talk Reasons: Detector has big leakage current (even at 3700 V, I > A in my estimation) Preamplifier electronics are not work correctly Possible solutions: Change the preamplifier Measure V-I characteristic of detector and choose the optimal voltage Pump and maybe heat

Gusev K., JINR , Gerda meeting “Wandering” = contact or electronic problems Detector 2 Strange instability of peaks (doubling effect) Now this effect is absent Leakage current at operation voltage is normal

Gusev K., JINR , Gerda meeting Detector 3 Detector has poor energy resolution FWHM = 3.0 keV Possible reason – big current (> A) Possible solution is similar to detector 1

Gusev K., JINR , Gerda meeting Detector 4 No problems!

Gusev K., JINR , Gerda meeting Detector 5 Poor resolution (FWHM = 3.05 keV), but leakage current is good Need further investigations

Gusev K., JINR , Gerda meeting Conclusions All detectors are prepared for work, all crystals are good but their spectrometric performance are not ideal (especially for detectors 1, 3 and 5) For achieving the best performance of KI detectors we need:  Good measurement conditions;  Enough time for determination of various detector parameters (at least V-I characteristics);  Precision pulse generator;  Devices for pump and heat processes. We have to make all available procedures before any other activities (such as repacking, etc.)