PHOTOMULTIPLIER HIGH VOLTAGE POWER SUPPLY SYSTEM FOR THE CMS FORWARD HADRON CALORIMETER Lubomir Dimitrov, Ivan Vankov Nuclear Electronics Laboratory, Institute for Nuclear Research and Nuclear Energy, BAS Serguei Sergeev Fermi National Laboratory, USA/Joint Institute for Nuclear Research, Dubna, Russia I. Vankov NEC’2005, Varna, Sept. 2005

PMT HV PSS for HF I. Vankov NEC’2005, Varna, Sept INTRODUCTION. 2.POWER SUPPLY SYSTEM 3.HV POWER SUPPLY MODULE 4.CRATE CONTROLLER MODULE AND MONITOR AND CONTROL UNIT 5.POWER SUPPLY SYSTEM SOFTWARE 6.BASIC TECHNICAL PARAMETERS 7.CONCLUSIONS

Compact Muon Solenoid (CMS) PMT HV PSS for HF - INTRODUCTION 1 HEHB HF2 HF1 I. Vankov NEC’2005, Varna, Sept. 2005

FORWARD HADRON CALORIMETER (HF) Copper Block Cerenkov Detectors – Embedded Quartz Fibers 1728 Photomultiplyers (PMTs) Type Hamamatsu R7525 (8 dynodes) I. Vankov NEC’2005, Varna, Sept PMT HV PSS for HF - INTRODUCTION 2

PROBLEMS CLASSIC SOLUTION: INDIVIDUAL RESISTOR DIVIDERS – GENERATE ALL PMT DYNODE VOLTAGES, BUT: 1. NEED 1728 HIGH VOLTAGE CHANNELS and m long HV CABLES - VERY EXPENSIVE 2. LARGE SPACE FOR THE 1728 DIVIDERS 3. GREAT POWER LOSSES IN THE DIVIDERS – PRODUCE MUCH HEAT PMT HV PSS for HF - INTRODUCTION 3 I. Vankov NEC’2005, Varna, Sept. 2005

PMT HV PSS for HF - INTRODUCTION 4 SPECIFIC SYSTEM STRUCTURE proposed by Dr. David Winn from Fairfield University 72 READ OUT BOXES (ROBOXES) – 36 for HF1 and 36 for HF2 36 roboxes – divided to 4 group of 9 corresponding to the four HF quadrants IN EACH ROBOX – 3 PRINTED CIRCUIT BOARDS (PCBs) WITH 8 PMTs HAVING VERY SIMILAR GAIN/VOLTAGE I. Vankov NEC’2005, Varna, Sept. 2005

PMT HV PSS for HF - INTRODUCTION 5 PRINTED CIRCUIT BOARD DIAGRAM I. Vankov NEC’2005, Varna, Sept. 2005

PMT HV PSS for HF - INTRODUCTION 6 I. Vankov NEC’2005, Varna, Sept PRINTED CIRCUIT BOARD WITH 8 PMTs ONE RESISTOR DIVIDER FOR THE FIRST 6 DYNODES WITH TOTAL RESISTANCE ABOUT 20 Mohms – MAX. CURRENT < 50 uA THREE SUPPLY VOLTAGES: U K = 2000 V; U D7 = 800 V; U D8 = 400 V RESULTS: STABLE VOLTAGE TO D7 AND D8 VERY LOW POWER LOSSES

PMT HV PSS for HF - INTRODUCTION 6 ONE QUADRANT HV SYSTEM STRUCTURE PS3 PS2 PS1 ROBOX No 1 3 PCs x 8 PMTs Cable No 1 Cable No 2 Cable No 9 9 HV cables L  15 m 1 HV cable L  150 m ROBOX No 2 ROBOX No 9 HV MODULE No 1 U U D7,1 LG U D8,1 U K,1 U U D7,2 LG U D8,2 U K,2 U D7,2 LG U D8,2 U K,2 U D7,1 LG U D8,1 U K,1 U D7,3 LG U D8,3 U K,3 U U D7,3 LG U D8,3 U K,3 9 HV CHANNELS = 1 MODULE 1 CLUSTER SUPPLIES 9 PCBs 3 GROUPS OF 72 PMTs WITH SIMILAR PARAMETERS 1x9 HV WIRES 165 m CABLE 9x9 HV WIRES 15 m CABLES I. Vankov NEC’2005, Varna, Sept. 2005

PMT HV PSS for HF – CRATE DIAGRAM 4 HV POWER SUPPLY MODULES 3 HV CLUSTERS A, B, C CRATE CONTROLLER MODULE RS 485 – CRATE LOCAL BUS MONITOR AND CONTROL UNIT 7 LEDs – SYSTEM STATUS 4 LIMITS – U klim, I lim1, I lim2, I lim3 CRATE POWER SUPPLY +5 V, +8 V, -8 V, +40 V I. Vankov NEC’2005, Varna, Sept. 2005

PMT HV PSS for HF – CRATE PHOTO I. Vankov NEC’2005, Varna, Sept. 2005

PMT HV PSS for HF – HV MODULE 1 A1, B1, C1 – 0 to 2000 V A2, B2, C2 – 0 to 800 V A3, B3, C3 – 0 to 400 V FLOATING OUTPUTS ONE CHANNEL: DAC – HV SET VALUE DC-DC CONVERTER 2 CMPs – U and I LOCAL CONTROL MUX+12 bits ADC INTERLOCK LED CONTROL I. Vankov NEC’2005, Varna, Sept. 2005

PMT HV PSS for HF – HV MODULE 2 I. Vankov NEC’2005, Varna, Sept. 2005

RS485 INTERFACE WITH HOST COMPUTER CRATE LOCAL BUS + CUSTOM PROTOCOL 7 LEDS – STATUS OF THE SYSTEM 4 POTENTIOMETERS – U and I LIMIT VALUES A NEW FIRMWARE HAS BEEN DEVELOPED WHICH IS NOW CAPABLE TO CONTROL BOTH HCAL AND HF PS SYSTEM RECOGNIZING THE DIFFERENT TYPE OF MODULES BY THEIR UNIQUE ID NUMBER. PMT HV PSS for HF – CONTROL & DISPLAY Fig. 8. Crate controller module with the monitor and control unit block diagram. CPU CONTROL LOGIC MONITOR AND CONTROL UNIT POWER ON CHANNEL ON VOLTAGE PROT CURRENT PROT OVER HEAT INTERLOCK POWER FAILURE A[13..15] A[8..12] D[0..7] RxD TxD A[13..15] A[0..7] D[0..7] CNTRL[0..3] KILL TxD RxD INTERFACE RS485 OUT RS485 IN ST MD[0..3] CLK D-WR D-RD RES U Klim I I I MEMORY CNTR[0..3] D[0..7] A[0..12] S[0] MD[0..3] CLK D-WR RES D-RD KILL lim1 lim2 lim3 I. Vankov NEC’2005, Varna, Sept. 2005

PMT HV PSS for HF – SOFTWARE VERY SIMILAR TO THE HPD POWER SUPPLY SYSTEM MAIN MONITOR WINDOW NINE CHANNELS STATUS LIMIT VALUES VOLTAGE UP/DOWN RATES CRATE PS VOLTAGES MODULE STATUS I. Vankov NEC’2005, Varna, Sept. 2005

HV PSS for HF - PARAMETERS I. Vankov NEC’2005, Varna, Sept PARAMETER CHANNELS A1,B1,C1 CHANNELS A2,B2,C2 CHANNELS A3,B3,C3 Max. operating voltage, V Voltage adjustment step, V Ramp rate, V/s Voltage ripple, mVp-p Voltage monitoring inaccuracy, % Long term instability, % Max. output current, mA Current monitoring inaccuracy, % Special – < 0,1 0,8 < 1 Floating output – < 0,1 0,8 < 1 Floating output – < 0,1 0,8 < 1 Floating Output

HV PSS for HF CONCLUSIONS HV SYSTEM FOR HF PHOTODETECTORS OF 2 CRATES WITH 4 HV MODULES DESIGNED AND PRODUCED LONG TERM TEST CONFIRMED THE BASIC SYSTEM PARAMETERS AND ITS RELIABILITY I. Vankov NEC’2005, Varna, Sept. 2005