TIPP 2011, Chicago 1

LED calibration systems for CALICE hadron calorimeter

June 11, 2011

TIPP 2011, Chicago 2

Outline

• Calice prototype• SiPM Motivation (SiPM issues, temeperature drift..)• AHCAL 1m^2 solution

– Electronics solution– performance

• Embeded solution– Electronics solution– Performance

• Quasi-resonant LED driver– Electronics solution– Performance

• Light distribution June 11, 2011

TIPP 2011, Chicago 3

Calice 1m2 prototypeToDo

ECAL

HCAL

TCMT

20mm Fe plates and

scintillators

90 cm

HCAL

3 cm

1 mm

June 11, 2011

TIPP 2011, Chicago 4

SiPM Issues – need for Calibration ToDo

• Obrazek – vysec snimace, Danilov-experimenty??

• Jara vlivy na saturacni prubeh – cas, zpozdeni svetla, cas do nabiti…

June 11, 2011

TIPP 2011, Chicago 5

MUONS

Particle detection

LE

D li

gh

t

June 11, 2011

TIPP 2011, Chicago 6

CMB-TBD

• El. Zapojeni, simulace

June 11, 2011

TIPP 2011, Chicago 7

CMB-results ToDo

• Jara’s calibration plots, SPS, etc.

June 11, 2011

TIPP 2011, Chicago 8

Integrated LED system

LEDs• Developed by DESY and Uni Wuppertal• Each Tile has its through-hole mounted LED• Each LED has its own driver circuitry.

– Operation: The current pulse though the LED is generated by discharging of the Capacitor by a fast transistor

– V-calib signal range: 3–10 V– System tuned for ~8 ns pulses

• Choice of the LED is critical for this driver– Several different LED types were tested (see next

slide)– The technology of the LED is most important

• Only Single-quantum-well LEDs work well (usually UV-LED)

• Other (multi-quantum-well) LEDs have too big capacitance and produce longer optical pulse (with low-intensity “tail”)

• Driver circuitry is now optimized and being manufactured on the new HBU for the technological prototype

June 11, 2011

5 ns

TIPP 2011, Chicago 9

Integrated LED system – Optimization

• Pulse of the Blue LED is much wider (~40 ns), than the UV LED (~5 ns)

• Light pulse width re-measured with a differential driver

– In this mode: LED is reverse biased, then for a short pulse forward biased and directly reverse biased again

– The reverse voltage helps to discharge the LED

– Blue LED stops shining much faster

June 11, 2011

Blue LED

UV LED

Blue LED, differential

TIPP 2011, Chicago 10

Integrated LED system – SPS

• For longer (>30 ns) pulses, both UV and Blue LEDs produce equal optical pulses

• Observation: UV LED have much steeper rise time

• Driver circuitry is now optimized and being manufactured on the new HBU for the technological prototype

• Question: is short pulse necessary?– Answer: Yes, 15 ns pulses and faster

produce decent Single Photon Spectra

• Single Photon Spectrum (SPS)– Short pulse -> improvement of the quality– Nice spectrum with UV-LED– Spectrum is more smeared with blue-LED

• Light yield of the integrated LED

June 11, 2011

Blue LED, 30 ns

Blue LED, 15ns

UV LED, 7ns

TIPP 2011, Chicago 11

Integrated LED system – Light Yield• Measurements with key components

variation• Circuitry was finally tuned to deliver ~2K

(12K???) effective pixels – Light referenced to PMT signal– ~500 pixels were fired (saturation)

• Time behavior of the LED– Without tile: sharp pulse– With tile (and Wavelength shifting fibre)

long tail

June 11, 2011

Resistorvariation

Capacitorvariation

With Tile

25 ns

TIPP 2011, Chicago 12

QMB6-ToDo

June 11, 2011

TIPP 2011, Chicago 13

QMB6-ToDo

June 11, 2011

TIPP 2011, Chicago 14

Notched Fibre

June 11, 2011

• 24-notched fibre at the left figure. Illuminated by a green laser• Light is emitted from the notches• The notch is a special scratch to the fibre, which reflects the light to

the opposite direction• The size of the notch varies from the beginning to the end of the

fibre

First notch Middle notch End position notch

Emission from the fibre (side view)

TIPP 2011, Chicago 15

Optical fibre

• Measurements of the light yield – Through the 3mm hole on the

PCB (FR4 with filled inner layer)

– 3 positions of the notch according to the PCB thru-hole

June 11, 2011

“start” position “middle” position “end” position

TIPP 2011, Chicago 16

Notchet fibers configuration

• 72 zarezova vlakna – vysledky linearity• LED vyzarovaci profil (smolda)• Konfigurace 3*24 zarezu

June 11, 2011

HBU6HBU5HBU4HBU3HBU2HBU1

TIPP 2011, Chicago 17

Development of new Quasi-resonant driver (QMB1)

• QMB1 (1-chanel LED driver):– Fixed

• Topology• Communicating bus (CAN)• CPU (Atmel AVR)• Trigger distribution (LVDS)• Trigger delay canbe tuned by C trimmer

(~10ns)

• Free to adjust: will be discussed at DESY in July calib meeting

– Mounting holes (fixation to support/HBU– Fibre(LED) position

• Set of notched fibers, semiautomat machine under development

– Set: 3*fibre with 24 notches, creating a line of 72 notches.

– 3 sets will be delivered

June 11, 2011