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HV_GEM per LHCB M1R1 HV power supply
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Introduction
HV_GEM Technical specification
I_meter (for OPERA EXP) specifications
Final crate
Conclusions
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.
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Technical Specification
One HV_GEM device contains :
• 7 active HV independent channels with serial architecture
• 6 channels with max voltage of 700 V (200 mA)
• 1 channel with max voltage of 1200 V (100 mA)
• isolation between HV and ground (max 5 KV)
• Ripple 1 Vpp at maximum load
• power supply range 12-15 Volt
• power consumption 120 mW (1.2 W at maximum current)
• CAN-BUS controller
• Read and Write voltages, temperature and PS monitoring
• First channel (G3d) readable in current (1 mA resolution)
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Scheme of connection
Vmax -1200V
G1
Vmax -500V
Vmax -700V
G2
Controller
Vmax -700V
G3
R
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Vmax -500V
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Vmax -500V
Vmax -700V
Gnd Detector
HV_GEM Control Panel
A program in Labview has been also realized for the monitoring and control purposes
GEM power supply
Drift’s fields
Gap’s definitions
Voltages monitoring
Two prototypes have been built up to now
and they have been already used on GEM chambers in Frascati
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OPERA I_meter specifications
This is an evolution of the nano I meter already used by
LHCb Muon group in several test beam e construction Test
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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.
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Some component : Current Sensor
Low voltage floating generator
Bus Communication & PWR
Floating Area 5kV max
Optical fiber digital interface
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Some component : CAN-BUS Controller
JTAG Communication
I/O conn.
Logarithmic Digital Decoder
CPU
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Serial and CAN.BUS
port communications
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Very low noise Power supply 100W
Fan connector
Power controller
+12V
+6V
Power 220Vac
Isolation transformer
Switching Power
Passive Filter
Guaranteed isolation between primary and secondary: 3.5kV
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Engineering example
Power supply for:
•Sensor
•CPU
•HV_GEM
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LHCb M1 HV Proposal
• 24 HV GEM : PS for LHCb M1R1
• 24 HV Output multiple connectors (or 12)
• 24 current monitor channels for G3down
24 HVGEMs modules
nano I meter
• CAN-BUS communication
• Setting Voltage 24 x 7 = 168 channels
• Current limit set by trimmer (10-200 mA)
• Total dimension : standard crate 3U
standard crate 3 U
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Conclusions
• 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
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
the three GEM foils of the detector (Vg1, Vg2,Vg3);
with the passive divider they are fixed once for ever;
• the new system with 24 chs nano-ammeter can be exploited to monitor the
discharge of the detectors;
• the system allows to limit the currents drawn by each single GEM foil;
with the passivie divider this is not possible.
• 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
by increasing the voltage applied to GEM foils.
This feature is of course not present in the HV divider solution;
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