ECAL and HCAL technical status 1Yu. Guz 2015/09/02

ECAL LED instability issue – I 2Yu. Guz 2015/09/02 It happens that the ECAL LEDs get unstable and die. now at unacceptably high rate – not infant mortality in the Outer zone only Aug 12: 8 dead LEDs replaced; Sep – other 14 replaced to other type LEDs The LEDs become unstable before they die.

ECAL LED instability issue – II 3Yu. Guz 2015/09/02 The reason is understood: this is an unfortunately wrong choice of the LED model done in the chosen LED type (Multicomp Mega Bright OVL-5523) have very good light yield but low (lower than usual) reverse breakdown voltage (8-12 V) (easy to measure with a KEITHLEY source meter). the design of the LED driver is such that between pulses the reverse voltage of up to ~15 V can be applied to the LED  the lower is required flash magnitude, the higher is reverse voltage  therefore the Outer area suffers most now working on selecting a proper LED CREE LC503FBL1 is a good candidate:  also good brightness  also cheap: ~ 0.15 euro/pc  selection is necessary: only 60% have U BREAK >20V, minimum is ~12 V total number of LEDs is 456 (however we can choose to replace LEDs only in the Outer zone – 168) used 01-Sep for the replacement: the light yield is similar to the old LEDs (next slide). stability etc to be studied LED driver (simplified)

ECAL LED instability issue – III 4Yu. Guz 2015/09/02 LED picture after the replacement of September similar light yield (even higher in some cases) two more dead LEDs since 02-Sep.

HCAL technical status – I 5Yu. Guz 2015/09/02 One dead cell

HCAL technical status – II : dark currents 6Yu. Guz 2015/09/02 >10 nA: 158 PMTs >50 nA: 57 PMTs >100 nA: 24 PMTs The PMT degradation continues: in 2015 all the PMTs with dark current >50 nA were replaced to new ones. Order of 150 PMTs would need replacement in the winter shutdown (of course for some of them the replacement can be postponed to the 2016/2017 shutdown).

HCAL technical status – II : dark currents 7Yu. Guz 2015/09/02 No degradation is seen in PMTs replaced in 2011 and 2014 (total of 183 PMTs were replaced).

HCAL technical status – III: Cs calibration system 8Yu. Guz 2015/09/02 The previous calibration was performed on 17-Jun-2015 evening after the test, the side A Geiger counter was found not working Geiger counter is the sensor used by the safety signalization, which is very important The Geiger HV mezzanine of the Garage module had to be replaced 1-Sep-2015: the replacement was done, the signalization is operational again the source run has been performed 02-Sep-2015

HCAL Cs calibration – I 9Yu. Guz 2015/09/02 The calibration was performed on 02-Sep-2015 evening; the PHYSICS recipe updated 03-Sep

HCAL Cs calibration – II 10Yu. Guz 2015/09/02 The calibration was performed on 02-Sep-2015 evening; the PHYSICS recipe updated 03-Sep

HCAL Cs calibration – III 11Yu. Guz 2015/09/02 It seems that now ageing takes place even without high radiation doses

HCAL Cs calibration – IV 12Yu. Guz 2015/09/02 For the completeness – same ageing plot, but as a function of time.