Feb 20, 2009 CALICE meeting, Daegu, Korea

QRL in Magnetic Field 1

QRLed Driver QRLed Driver inin

Magnetic FieldMagnetic Field

Jaroslav ZalesakJaroslav ZalesakInstitute of Physics of the ASCR, PragueInstitute of Physics of the ASCR, Prague

Feb 20, 2009 CALICE meeting, Daegu, Korea

QRL in Magnetic Field 2

QRLD board (ASCR Prague):„Quasi Resonant LEDDriver Board“, 6 LEDs / 1 PCB

Notched fibers Each illuminates 12 tiles

Calibration Option 2:Calibration Option 2: LED driverLED driver

CALIB moduleOption I

• Non-linearity correction, MIP calibration, Correction temperature variations• Two appr.: electrical or optical signal distribution - One LED / one tile or central driver plus fibres

UV LEDs – short light pulses

HBU

Feb 20, 2009 CALICE meeting, Daegu, Korea

QRL in Magnetic Field 3

QRQR--LED driverLED driver• Option with optical fiber distribution• Electronics: multi-channel prototype complete• Optical system: uniformity again competitive• Multichannel LED driver

• 1 PCB with the communication module µC, power regulator, 6 channels of QRLed driver

• Communication module to PC via CAN bus or I2C• Controlling the amplitude and monitoring temperature

and voltages • LED pulse width ~ 5 ns fixed, tunable amplitude up to

50-100 MIPs is controlled by the V-calib signal • 2 LEDs can be monitored by a PIN photodiode

QRLED 1

T-calib

V-calib

Power regulator

QRLED 6

LED 1

LED 6

+12V

FIBRES

µCAT91SAM7X256

Feb 20, 2009 CALICE meeting, Daegu, Korea

QRL in Magnetic Field 4

Magnetic Field Test SetupMagnetic Field Test Setup• week ago tests in mag. field• one week period at solenoid• DESY site up to 4 T available

• QRL PCB fixed to movable rod• different positions to measure• 3 LEDs / channels →• 3 optical fibers outside meas. area, LV supply and CANbus

wires from r/o area

Feb 20, 2009 CALICE meeting, Daegu, Korea

QRL in Magnetic Field 5

Data ReadoutData Readout• 3 r/o Photo detector channels:

2 APDs @ low-gain 1 PIN diode + amplifiers

• 1 Temp sensor @ APD (automatically in r/o only at the end)• LV + HV supplies

• Slow control based on LabView• via CAN bus several LV/Temp control points from PCB recorded• Auto-implemented data transfer from scope (3+1 ch. Ampl)• Independent S/C for Magnet

Feb 20, 2009 CALICE meeting, Daegu, Korea

QRL in Magnetic Field 6

Magnetic Field Scan #1 - ‘middle’Magnetic Field Scan #1 - ‘middle’

• 1st PCB position in the middle solenoid parallel to line of magnetforce, horizontally placed, homogeneous Mag. Field

• about 2hours scan 6.5 up/down magnet + 7min stable B• Variations in response @ (in) visible level (PIN x APD T- uncorr.)

Feb 20, 2009 CALICE meeting, Daegu, Korea

QRL in Magnetic Field 7

Magnetic Field Scan #2 - ‘slantways’Magnetic Field Scan #2 - ‘slantways’

• 2nd PCB position in the middle solenoid, placed on oblique surface ‘slantways’ ~25° angle, homogeneous Mag. Field• Variations in response @ (in) visible level (PIN x APD T- uncorr.)• Overall scan ±0.5% difference (a bit more APDs), maybe B steps

Feb 20, 2009 CALICE meeting, Daegu, Korea

QRL in Magnetic Field 8

Magnetic Field Scan #3 – ‘outer’Magnetic Field Scan #3 – ‘outer’

• 3rd PCB position at the end of solenoid – ‘outer’ position, horizontally placed, no-homogeneous Mag. Field• response seems to rise contrary previous measurements for highest magnetic field B.

Feb 20, 2009 CALICE meeting, Daegu, Korea

QRL in Magnetic Field 9

Magnetic Field – Long-termMagnetic Field – Long-term

• Over 8 hours long-term behavior in constant 4T magnetic field• Almost (Temp ~0.1%) constant conditions• Variations in response invisible• Amplitudes < 0.5%; PIN diodes ~0.5% noise level, APD less

Feb 20, 2009 CALICE meeting, Daegu, Korea

QRL in Magnetic Field 10

Temperature dependenceTemperature dependence

• Only, at the end of data measurement period automatically APD temperature sensor in r/o implemented• Correction formulas determined to be applied to data• 2(?,gain/pos. sensor) diff APD dependence, NO PIN dependence

Feb 20, 2009 CALICE meeting, Daegu, Korea

QRL in Magnetic Field 11

Conclusion IConclusion I

Calibration system – option II: electronic part QR LED driver reasonably works incl. Slow control interfaces

can be implemented into EUDET AHCAL prototype

Characteristics and function described in public paper EUDET report 2008-7

Optical part – notched fibres in preparation → promising results

Prague AHCAL groupPrague AHCAL group

Feb 20, 2009 CALICE meeting, Daegu, Korea

QRL in Magnetic Field 12

Conclusion II, OutlookConclusion II, Outlook Calibration system – QR LED driver in Magnetic field tests: works very well meas. system sensitive to < 0.5% variations in response

During constant magnetic field (standard operation conditions) the measurements are stable (w/o reference to PD temp.)

Expecting one more measurement period more precise orientations of PCB in mag. field to avoid temperature dependence

P.S. Thanks to DESY staff to allow to make such measurement

Note: these days we have obtained one new notched fiber, which seems to fulfill our request on uniformity (light output ± 10%)

Feb 20, 2009 CALICE meeting, Daegu, Korea

QRL in Magnetic Field 13

Backup slidesBackup slides

Feb 20, 2009 CALICE meeting, Daegu, Korea

QRL in Magnetic Field 14

Option 2: Option 2: Optical systemOptical system• Idea: use one fiber for one row of tiles (72)• Problems:

• uniformity of distributed light• enough intensity of distributed light• concentration of LED light into one fiber

• Two fibres:• Side-emitting - exponential fall of intensity• Notched fibre - better uniformity of distributed

light - need to mechanize production - R&D

• No optical cross talk seen (< 1-2 %) @ different amplitudes

2 MIPs2 MIPs

10 MIPs10 MIPs

25 MIPs25 MIPs

Notched fiber:Notched fiber:

Feb 20, 2009 CALICE meeting, Daegu, Korea

QRL in Magnetic Field 15

Calibration systemCalibration system• Non-linearity correction, MIP calibration, Correction temperature variations• Use gain monitoring, adjust voltage → see G. Eigen’s talk

• Many procedures developed during last year’s analysis, but not finally proven yet

• Stability of saturation still an issue -> need dynamic range• Two appr.: electrical or optical signal distribution - One LED / one tile or central driver plus fibres

• Differences inside the active gap, but same external interfaces

Option 2: Option 2: LED driverLED driver• Electronics: multi-channel prototype complete• Optical system: uniformity again competitive

• Integration into active layer still an open issue

• Multichannel LED driver• 1 PCB with the communication module µC, power

regulator, 6 channels of QRLed driver• Communication module to PC via CAN bus or I2C• Controlling the amplitude and monitoring temperature

and voltages • LED pulse width ~ 5 ns fixed, tunable amplitude up to

50-100 MIPs is controlled by the V-calib signal • 2 LEDs can be monitored by a PIN photodiode