Alberto Pullia INFN - Milano University of Milano Department of Physics 14th AGATA Week January 22-24, 2014, Madrid, Spain January 23, 2014 Status of the AGATA preamplifiers

All of them could be repaired. They have been sent back to IKP on Jan 14th 2014 Milano Preamp Repair In detail these problems have been found Output transistor of first stage and/or opamp of second stage (buffer) burnt out Cause: This is most probably related to the accidental detector warm up Bad connection of two devices (U4 to U5) Cause: trace or footprint or soldering point defective. Wearing effect? Unclear. Broken capacitance, resistor or via Cause: Wearing effect On December 15th 2013 I received 21 Milano preamps from IKP Cologne

Progr Preamp Series Preamp #ProblemFixModified * 1192chs, burnt trans Q5 and opamp U1devices changednot feasible ch, bad trace comp (U4) to OR (U5)wire connection addednot feasible chs, bad resistor in LDO (Ry6)resistor changednot feasible ch, burnt trans (Q5)device changednot feasible 51552chs, trans Q5 and opamp U1devices changednot feasible chs, burnt PS capacitor (Cx1) and 2012 modification missing * capacitor changedyes ch, bad trace comp (U4) to OR (U5) and 2012 modification missing * wire connection addedyes ch, bad trace comp (U4) to OR (U5) and 2012 modification missing * wire connection addedyes ch, bad trace comp (U4) to OR (U5) and 2012 modification missing * wire connection addedyes ch, bad trace comp (U4) to OR (U5) and 2012 modification missing * wire connection addedyes chs, bad trace comp (U4) to OR (U5) and 2012 modification missing * wire connection addedyes 1248.bdefective via in P/Z stagewire connection addedpreviously set b2012 modification missing * -yes b2012 modification missing * -yes b2012 modification missing * -yes b2012 modification missing * -yes b2012 modification missing * -yes b2012 modification missing * -yes b2 chs, bad trace 12V and burnt opamps wire connection added, devices changed previously set b2012 modification missing * -yes b2012 modification missing * -yes * Config 1 (Series 1,2 and 3 only) and config 2 (all Series except 1) Summary Table

Dual-Core Preamps occasionally show 66mV/MeV instead of 100mV/MeV Cause:1kohm resistor for gain change from 200mV/MeV to 100mV/MeV installed twice (issue found by G. Pascovici) Dual-Core Preamps occasionally show 66mV/MeV instead of 100mV/MeV Cause:1kohm resistor for gain change from 200mV/MeV to 100mV/MeV installed twice (issue found by G. Pascovici) Dual-Core Preamp Gain We should introduce a new policy here Any change in preamplifiers MUST be communicated to me and/or George so that we can evaluate the change and track the modifications. No exception. Nominal value for gains: 100mV/MeV±10% (low range ch) (from original 200mV/MeV) 55mV/MeV±10% (high range ch) (from original 50mV/MeV)

Conversion factor calibration for ATC5; ADC1 Detector/ Channel High gain “ 100mV/MeV ” (10MeV_Range) Low gain “ 55 mV/MeV ” (18MeV_range) Deviation respect to the by design values: 100mV/MeV and 55 mV/MeV ATC5/A_004* % / +14.0% ATC5/B_ % / -4.5% ATC5/C_ % / -3.6% ADC1/B_ % / +6.7% ADC1/C_ *** % / -4.5% * Within a limit of +/- 1.5 %, the conversion factors are almost independent of the warm part of the preamplifiers ** Detector ATC5/A shows still instabilities (leakage current fluctuation), after reopening it the detector group will change also the feedback components (namely, the 1 pF capacitor and 1 GOhm resistor) *** In detector ADC1/C_006 we found on the Core CSP_“High gain” channel two 1KOhm soldered in parallel…this is indeed, a quite unpleasant human error! In this way, the gain of that stage was changed from 2 to 1.5 and correspondingly, the calibration factor changed from 100 mV/MeV to 66.6 mV/MeV ! Such “in situ” changes have to be registered in a notebook, if not reported to the detector group In November 2013 the conversion factor of a few Dual Core Preamps has been measured by G. IKP