Development and Performance of the High Voltage Distribution System for the ALICE TRD A. Markouizos, P. Mantzaridis, P. Mitseas, A. Petridis, S. Potirakis, M. Tsilis, M. Vassiliou University of Athens HEP 2008, Ancient Olympia

1.Introduction 2.HVDS Overview 3.HVDS Commissioning 4.Performance Tests  Magnetic field test  Test on the TRD-SMI / SMII 5.Summary Outline XXVI Workshop on Recent Developments in HEP M. Vassiliou

TRD XXVI Workshop on Recent Developments in HEP M. Vassiliou

4 TRD Introduction 540 individual modules: 18 azimuthal sectors-supermodules Each supermodule contains: 5 detector stacks of 6 module layers each Each module consists of: ALICE TRD XXVI Workshop on Recent Developments in HEP M. Vassiliou radiator drift chamber readout electronics

TRD Supermodule XXVI Workshop on Recent Developments in HEP M. Vassiliou

HVDS Description  A Master/Slave power supply distribution system has been designed and constructed in order to provide the required anode (1.9kV) and drift voltage (-2.5kV) to the ALICE TRD readout chambers.  The system can switch on and off, monitor (at the nA level), protect, and regulate (leverage of 1000 Volts) each channel from a common ceiling voltage. XXVI Workshop on Recent Developments in HEP M. Vassiliou

HVDS Overview High Voltage Distribution System: Simple design Reduced complexity Reduced number of components Very low current circuits: Meet ALICE TRD requirements Provide high resolving power (nA), fast response, Short circuit protection Two Enfolded Voltage stabilizing Systems: Shunt regulator Provides load regulation Reduces output ripple Software regulation Gives long term stability XXVI Workshop on Recent Developments in HEP M. Vassiliou

 Architecture Similar to ALICE TRD layout Card Channel 01 Channel 02 Channel 03 Channel 04 Channel 05 Channel 06 μCpu Crate 01 Module 01 Module 02 Module 03 DCS Board Card 01 Card 02 Card HVDS Architecture XXVI Workshop on Recent Developments in HEP M. Vassiliou

HVDS Specifications Both Systems: Output Channels180 ramp-up rate1-30 V/s ramp-down rate1-100 V/s HV stability<0.1% /24h Achieved HV stability~0.002%/24h Ripple rejection~40 dB Current accuracy<0.2% Achieved Current accuracy~0.03% response time< 50 ms Anode System: Dynamical range900 – 1900 V Max. current7 uA Drift System: Dynamical range1450 – 2500 V Max. current270 uA

HVD Card Block Diagram 1.Six shunt regulators 2.DACs for the regulator reference voltage 3.Six measurement circuits, each consisting of an ADC with the appropriate signal conditioning circuits for voltage and current measurement. 4.Six floating auxiliary power supplies. 5.The micro-controller and the CPLD 6.The CAN BUS interface (controller and line driver) 7.RS232 interface 8.A digital temperature sensor 9.IP Switches that set the card ID on the CAN BUS XXVI Workshop on Recent Developments in HEP M. Vassiliou

Software Regulation: HV Stability ~0.002%/24h Includes protections: Temperature, Current, and Voltage Generates alarm signals Response Time <50ms Performs Self Diagnostics: Hardware Monitoring, Hardware Error Detection 2 Control Interfaces: CAN Interface (PVSS & Final Set-up) RS232 Interface (Development, Debugging, Tests) Control Software: Embedded Software XXVI Workshop on Recent Developments in HEP M. Vassiliou

DCS: SM HV Control Panel XXVI Workshop on Recent Developments in HEP M. Vassiliou

Set: status voltage max (min)_voltage max_current period Monitor: voltage current Open panels ramping alarm history Warnings – Alarms Local Archiving DCS: HVDS Channel FSM Panel XXVI Workshop on Recent Developments in HEP M. Vassiliou

2 Anode + 2 Drift Crates delivered and tested at CERN: 30 Anode + 30 Drift HVD Cards Output HV Channels to power 6 TRD Supermodules HVDS Commissioning I XXVI Workshop on Recent Developments in HEP M. Vassiliou

Each crate contains: HVDS Commissioning II 1 Backplane 15 HVD cards 1 DCS Board  adapted on 1 DCS Auxiliary Card 8 Auxiliary Power Supply Cards  provide AC power to the isolated channels of the HVDS Cards 4 LV Power Supplies (Schroff PSM112 for ±12V and PSG105 for +5V) XXVI Workshop on Recent Developments in HEP M. Vassiliou

HVDS Commissioning III XXVI Workshop on Recent Developments in HEP M. Vassiliou

HVDS Commissioning: HVD Card Image XXVI Workshop on Recent Developments in HEP M. Vassiliou

Tests performed in the MNP22 Facility at CERN. HV set at -2.4 kV (Drift), 1.8 kV (Anode) B increased from 0 to 220 Gauss Two crate configurations Successful over current test Performance Tests : Magnetic Field Test XXVI Workshop on Recent Developments in HEP M. Vassiliou

Results: Drift -2.4 kV magnet onmagnet off σ < 15 mV Magnetic Field Test XXVI Workshop on Recent Developments in HEP M. Vassiliou

Results: Anode 1.8 kV magnet onmagnet off σ < 15 mV Magnetic Field Test XXVI Workshop on Recent Developments in HEP M. Vassiliou

Test on the TRD-SM I XXVI Workshop on Recent Developments in HEP M. Vassiliou

Performance Tests Long Term Voltage Stability Test ΔV (FWHM) < 30 mV ΔV / V < 1.6 E-5 HV set at 1900 V XXVI Workshop on Recent Developments in HEP M. Vassiliou

Test on the TRD-SM I 6 anode channels HV set at 1450 V HVD System XXVI Workshop on Recent Developments in HEP M. Vassiliou

Test on the TRD-SM I Cosmic Data took at CERN “After finalising the assembly of the super module, its performance was tested with cosmics tracks. Three scintillators were arranged so that high multiplicity cosmics events could be recorded with a rate of about two per minute. The drift chambers were filled with an Ar, CO2 (15%) mixture and high voltage was applied by a Master/ Slave distribution system specifically developed at the University of Athens, Greece (drift voltage 1450V, anode voltage 1450 V). “ C. Adler et al. “Construction of the First ALICE TRD Super Module”, GSI Scientific Report 2006 Figure 1: Cosmics tracklets in the six layers of stack three of the super module. The tracklets can be connected to form tracks. A simple reconstruction (clusterization) was applied. We show a projection of the found clusters onto the plane perpendicular to the z-axis (beam axis). XXVI Workshop on Recent Developments in HEP M. Vassiliou

HVD system connected with the SM-II Anode 1.45 kV Drift -1.5 kV, -1.9 kV Successful overcurrent test Test on the TRD-SM II XXVI Workshop on Recent Developments in HEP M. Vassiliou

Results σ < 15 mV Drift 1900 V Test on the TRD-SM II XXVI Workshop on Recent Developments in HEP M. Vassiliou Anode 1450 V

Summary  A High Voltage Distribution System for the ALICE TRD has been designed and constructed. Four HVDS Crates have been delivered.  The system consists of the hardware, the embedded software and the control software at the supervisory level.  Many tests performed at CERN verified that the system fulfils all the specifications set by the detector designers. XXVI Workshop on Recent Developments in HEP M. Vassiliou

References [1] P. Mantzaridis, A. Markouizos, P. Mitseas, A. Petridis†, S. Potirakis, M. Tsilis, M. Vassiliou, “A High Voltage Distribution System for the ALICE Transition Radiation Detector”, ALICE-INT , [2] A. Markouizos, P. Mantzaridis, P. Mitseas, A. Petridis, S. Potirakis, M. Tsilis, M. Vassiliou, “The ALICE TRD – HV Distribution System”, Proc. of the Workshop on the DCS for the TRD, CERN, November 2007 [3] A. Markouizos, P. Mantzaridis, P. Mitseas, A. Petridis, S. Potirakis, M. Tsilis, M. Vassiliou, “Performance Tests of the TRD – HVDS” ALICE DCS Workshop, CERN, October 2007, fId= fId=21162 [4] A. Markouizos, P. Mantzaridis, P. Mitseas, A. Petridis, S. Potirakis, M. Tsilis, M. Vassiliou, “Integration of the HV Distribution System to the First TRD Supermodule”, Proc. of the Workshop on the DCS for the TRD, Heidelberg, January [5] C. Adler et al. “Construction of the First ALICE TRD Super Module”, GSI Scientific Report ENTS-METHODS-39.pdf ENTS-METHODS-39.pdf [6] A. Petridis, S. Potirakis, M. Tsilis, M. Vassiliou, “The TRD HV Distribution System”, ALICE - DCS Workshop, CERN, March 2005, XXVI Workshop on Recent Developments in HEP M. Vassiliou

Thank you! XXVI Workshop on Recent Developments in HEP M. Vassiliou

HVDS Crate Structure

TRD Principles