1. LHCb F. Murtas Servizio elettronica G. Corradi D.Tagnani P.Ciambrone HV_GEM per LHCB M1R1 HV power supply Introduction Introduction HV_GEM Technical specification HV_GEM Technical specification I_meter (for OPERA EXP) specifications I_meter (for OPERA EXP) specifications Final crate Final crate Conclusions Conclusions

2. LHCb F. Murtas Servizio elettronica G. Corradi D.Tagnani P.Ciambrone What is an HV_GEM HV_GEM is a new device designed and realized at Frascati specifically for the HV power supply of GEM detectors. This device has been presented at “La Biodola” in May 2006 by Gianni Corradi.

3. LHCb F. Murtas Servizio elettronica G. Corradi D.Tagnani P.Ciambrone Technical Specification Technical Specification One HV_GEM device contains : 7 active HV independent channels with serial architecture 7 active HV independent channels with serial architecture 6 channels with max voltage of 700 V (200  A) 6 channels with max voltage of 700 V (200  A) 1 channel with max voltage of 1200 V (100  A) 1 channel with max voltage of 1200 V (100  A) isolation between HV and ground (max 5 KV) isolation between HV and ground (max 5 KV) Ripple 1 Vpp at maximum load Ripple 1 Vpp at maximum load power supply range 12-15 Volt power supply range 12-15 Volt power consumption 120 mW (1.2 W at maximum current) power consumption 120 mW (1.2 W at maximum current) CAN-BUS controller CAN-BUS controller Read and Write voltages, temperature and PS monitoring Read and Write voltages, temperature and PS monitoring First channel (G3d) readable in current (1  A resolution) First channel (G3d) readable in current (1  A resolution)

4. LHCb F. Murtas Servizio elettronica G. Corradi D.Tagnani P.Ciambrone Scheme of connection Vmax -700V Vmax -500V Vmax -700V Vmax -500V Vmax -700V Vmax -500V Vmax -1200V Gnd Detector Controller R G1 G2 G3

5. LHCb F. Murtas Servizio elettronica G. Corradi D.Tagnani P.Ciambrone HV_GEM Control Panel GEM power supply Drift’s fields Gap’s definitions Voltages monitoring A program in Labview has been also realized for the monitoring and control purposes Two prototypes have been built up to now and they have been already used on GEM chambers in Frascati

6. LHCb F. Murtas Servizio elettronica G. Corradi D.Tagnani P.Ciambrone OPERA I_meter specifications 24 independent channels. Sensitivity 100pA. Precision 1% in the range 1nA to 25µA. Isolation 5KV, no polarity measurement Maximum drop among input-output 1.2 Volt (current independent) The system is controlled by a microprocessor with CAN-BUS interface. This is an evolution of the nano I meter already used by LHCb Muon group in several test beam e construction Test

7. LHCb F. Murtas Servizio elettronica G. Corradi D.Tagnani P.Ciambrone Some component : Current Sensor Floating Area 5kV max Optical fiber digital interface Low voltage floating generator Bus Communication & PWR

8. LHCb F. Murtas Servizio elettronica G. Corradi D.Tagnani P.Ciambrone Some component : CAN-BUS Controller Logarithmic Digital Decoder CPU Serial and CAN.BUS port communications I/O conn. JTAG Communication

9. LHCb F. Murtas Servizio elettronica G. Corradi D.Tagnani P.Ciambrone Very low noise Power supply 100W Fan connector Power 220Vac Isolation transformer Switching Power Passive Filter Power controller +12V +6V Guaranteed isolation between primary and secondary: 3.5kV

10. LHCb F. Murtas Servizio elettronica G. Corradi D.Tagnani P.Ciambrone Engineering example LHCb Eperiment Electronic service LNF Power supply for: Sensor CPU HV_GEM

11. LHCb F. Murtas Servizio elettronica G. Corradi D.Tagnani P.Ciambrone LHCb M1 HV Proposal 24 HV GEM : PS for LHCb M1R1 24 HV Output multiple connectors (or 12) 24 current monitor channels for G3down CAN-BUS communication Setting Voltage 24 x 7 = 168 channels Current limit set by trimmer (10-200  A) Total dimension : standard crate 3U nano I meter 24 HVGEMs modules standard crate 3 U

12. LHCb F. Murtas Servizio elettronica G. Corradi D.Tagnani P.Ciambrone Conclusions it has the same cost respect to “CAEN + passive divider” solution; it has the same cost respect to “CAEN + passive divider” solution; with the HVGEM system we are able to monitor all the 7 floating voltages applied to with the HVGEM system we are able to monitor all the 7 floating voltages applied to each detector; with the passive divider only 3 of them can be monitored; each detector; with the passive divider only 3 of them can be monitored; with the new system we are able to change/adjust the voltage distribution among with the new system we are able to change/adjust the voltage distribution among the three GEM foils of the detector (Vg1, Vg2,Vg3); the three GEM foils of the detector (Vg1, Vg2,Vg3); with the passive divider they are fixed once for ever; with the passive divider they are fixed once for ever; the new system with 24 chs nano-ammeter can be exploited to monitor the the new system with 24 chs nano-ammeter can be exploited to monitor the discharge of the detectors; discharge of the detectors; the system allows to limit the currents drawn by each single GEM foil; the system allows to limit the currents drawn by each single GEM foil; with the passivie divider this is not possible. with the passivie divider this is not possible. the transfer fields (the fields applied on the GEM gaps, between GEM foils) produced the transfer fields (the fields applied on the GEM gaps, between GEM foils) produced inside the detectors by the HVGEM can be kept constant also when gain is changed inside the detectors by the HVGEM can be kept constant also when gain is changed by increasing the voltage applied to GEM foils. This feature is of course not present in the HV divider solution; by increasing the voltage applied to GEM foils. This feature is of course not present in the HV divider solution;