1. Gusev K., JINR 27.06.2005, Gerda meeting Spectrometric performance of Kurchatov Institute detectors

2. Gusev K., JINR 27.06.2005, Gerda meeting Detector 1Detector 2Detector 3Detector 4Detector 5 Full mass, kG 0.982.9062.4462.42.781 Depletion voltage, V 3000320029001900 Bias voltage, V (recommended) 4000 35002500 FWHM, keV at 1332 keV (specifications) 1.981.911.972.06 FWHM, keV at full HdMo Set-up 2.222.432.712.142.55 Test at February 2005 FWHM, keV at 1332 keV 2.72.272.532.352.75 New measurements Bias voltage, V 37004000 35002500 FWHM, keV at 1332 keV 2.882.53.02.763.05

3. Gusev K., JINR 27.06.2005, 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 > 10 -10 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

4. Gusev K., JINR 27.06.2005, 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

5. Gusev K., JINR 27.06.2005, Gerda meeting Detector 3 Detector has poor energy resolution FWHM = 3.0 keV Possible reason – big current (> 10 -10 A) Possible solution is similar to detector 1

6. Gusev K., JINR 27.06.2005, Gerda meeting Detector 4 No problems!

7. Gusev K., JINR 27.06.2005, Gerda meeting Detector 5 Poor resolution (FWHM = 3.05 keV), but leakage current is good Need further investigations

8. Gusev K., JINR 27.06.2005, 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.)