1. 2 3 4 5 6 7 8 Performance of the RICH detectors of LHCb Antonis Papanestis STFC - RAL for the LHCb Collaboration

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Performance of the RICH detectors of LHCb

Antonis PapanestisSTFC - RAL

for the LHCb Collaboration

Outline

Detector description: See previous talk by Davide

Perego.

Cherenkov angle resolution Alignment Corrections for the

magnetic field distortions. Particle identification

PID algorithm. Small selection of physics

results that depend on particle ID.

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Monte Carlo simulation of the invariant mass for B->hh decays

Cherenkov angle resolution (i)

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Typical run

σ= 1.62 mrad σ= 0.68 mrad

Cherenkov angle resolution (ii)

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Resolution distribution of all 2010 runsVery good stability in time

1.63 mrad

0.68 mrad

Resolution in time

RICH1

RICH2

Using isolated rings

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Cherenkov angle vs momentum in RICH1

PID algorithm

Global event likelihood algorithm. Likelihood function includes

expected contributions from signal plus background for every pixel.

Signal photons come from the track that generated the ring, background can be noise or Cherenkov light from other tracks.

The whole event is considered as a whole.

Performs better than methods that treat every track separately, especially at high occupancies with overlapping rings.

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Pure particle samples

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†Nucl. Inst. & Meth. A 555 (2005) 356-369

σ=3.0 MeVσ=1.5 MeV

σ=1.0 MeV

PID performance

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Improvement expected at the next reprocessing

K/ p/

RICH physics potential

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Physics analysis (i)

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Measurement of direct CP violation in charmless charged two-body B decays at LHCb (LHCb-CONF-2011-011)

KB

B KKB

Without PID dominated by:

with kinematic cuts onlyhhB

Physics Analysis (ii)

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Measurement of the relative yields of the decay modes B0→D−π+ ,B0 → D−K+ , B0s → D−

s π + , and determination of fs/fd for 7 TeV pp collisions (LHCb-CONF-2011-013)

DBd DKBd

No combinatorial background

Philips Digital Photon Counting(PDPC)Dr. York HämischSenior DirectorPhilips Corporate Technologies

SiPM’s: from analog to digital, from laboratory to application

YH ©Philips Digital Photon Counting, February 2011

Philips Digital Photon Counting

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Digital Silicon Photomultipliers (dSiPM) -The next solid state (digital) revolution?

Transistor Television

X-Ray imaging

Digital Camera

Digital Photon Counting



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PDPC: short history

2004 Research project: “Novel technologies for future PET systems”

2005 Dr.Thomas Frach invented the digital SiPM

2006 Research project: “Integrated digital light sensor”; first test chip with promising results (inkubator)

2006 Disentanglement of Philips Semiconductors – now NXP

2007 Start of the PDPC venture

2008 Proof of concept

2009 Technology launch at IEEE NSS-MIC sensor V1.0

2010 PDPC separate unit of Philips Corporate Technologies

2011 Introduction of PDPC-TEK (Technology Evaluation Kit) and sensor version 2.0



Initial Motivation: A better detector for Positron- Emission-Tomography (PET) with TOF and DOI

Graphics courtesy of Spanoudaki & Levin, Stanford,in: Phys. Med. Biol. (56) 2011

TOF – time-of-flight

DOI – depth of interaction



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From single APD to multiple SPAD’s:Single Geiger-mode APD

Geiger-mode APD Array (SPAD’s):“Silicon Photomultiplier”

B. Dolgoshein, V. Saveliev, V. GolovineFirst idea: Russia, early 80‘s

• fully analog• poor timing• high bias voltage, but

below breakdown

• single photon resolution• binary, but still analog• better timing• low bias voltage, above breakdown



(S)APD in Geiger-ModeE

xt.

Vo

ltag

eC

urr

ent

Time

VBD

Meta-stable

Breakdown

Quenching



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SiPM-SPAD’s: sensitivity vs. dynamic range

Photographs courtesy of Spanoudaki & Levin, StanfordSensors, 10, 2010



Digital Photon Counting: the concept

Intrinsically, the SiPM is a digital device:

A single cell (SPAD) breaks down or not.

It works like a switch:

no breakdown: „0“ – no photonbreakdown: „1“ – single photon

Therefore, while the APD is a linear amplifier for the input optical signal with limited gain, the SPAD is a trigger device so the gain concept is meaningless.(source: Wikipedia)



Digital Photon Counting: realization

analog SiPM

www.hamamatsu.com

Summing all cell outputs leads to an analog output signal and limited performance

TDC andphoton counter

Digital output of• Number of photons• Time-stamp

Digital Cells

digital SiPM (dSiPM)

Integrated readout electronics is the key element to superior detector performance



Analog vs. Digital SiPM

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Digital SiPM: Principle












Digital SiPM: architecture and pixel diagram

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Single pixel

Die (2 x 2pixel)

(smart) tile (8x8 pixel)



Digital SiPM array (tile 2.0)advanced integration

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FPGA/Flash:

• tile firmware• data collection/concentration• Skew correction• Saturation correction• configuration• temperature measurement • dark count maps

200 MHz ref. clock

Power (1.2V, 1.8V, 2.5V, 3.3V, 30V)

SPI interface

Serial Dataoutput(x2)



Digital SiPM: Typical acquisition sequence (example)



PDPC dSiPM: intrinsic timing resolution

PDPC array

USB

Coincidencedetection

PDPC array

Clock,Config,Data

Clock,Config,

Data

PCFPGA board FPGA board

electronic trigger

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psec-laser

-100 -80 -60 -40 -20 0 20 40 60 80 1000

10000

20000

30000

40000

50000

60000

70000

Co

un

ts (

arb

. u

.)

Timestamp difference (ps)

(44 ± 1) ps FWHM

-120 -80 -40 0 40 80 1200

10000

20000

30000

Co

un

ts

Timestamp difference (ps)

Timing jitter: 44 ps FWHM 59 ps FWHM



PDPC: scintillator coincidence setup

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Recently achieved 120 ps FWHM using LSO:Ca

(Schaart et.al., TU Delft,submitted to IEEE-MIC)



PDPC dSiPM: Dark count mapWorst cells are switched off

• Dark counts per second at 20°C and 3.3V excess voltage

• ~ 95% good diodes (dark count rate close to average)

• Typical dark count rate at 20°C and 3.3V excess voltage: ~150Hz / diode

• Dark count rate drops to ~1-2Hz per diode at -40°C



PDPC dSiPM: slow scan imaging mode



PDPC dSiPM: crosstalk reduction by trenches



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Comparison of light detectors – which one is going to win?

Table courtesy of Spanoudaki & Levin, Stanfordin: Sensors, 10, 2010

PDPCdSiPM

meaninglessfirst photon

25-75< 350.33No

mm²-m²Currently: ~25



A digital light sensor might beuseful beyond PET

?

?

ClinicalPET

imaging

Pre-clinical

PET&SPECT

PET/MR

ClinicalSPECTimaging

SpectralCT

Focus Nuclear Imaging

Adjacent opportunities

Low dose CT

Other Medical Imaging Analytical Instrumentation

High Energy Physics

Night Vision / Surveillance / Security

DNA Sequencing

Microscopy

Microarrays

Antineutrino Detection

Particle Accelerators

Automotive Night Vision

LIDAR

Facility/Homeland

Security

Cherenkov Detectors

?

LoC

Medical Imaging

Intra-operativeprobes



4343

Key parameters of light detectors

λ

sens.

res.

speed

timingdyn. range

size

priceKey parameters:

1. Wavelength2. Sensitivity3. Spatial resolution4. Speed5. Timing6. Dynamic range7. Size8. Price



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What does the ideal spider web for HEP look like?

Key parameters:

1. Wavelength2. Sensitivity3. Spatial resolution4. Speed5. Timing6. Dynamic range7. Size8. Price

λ

sens.

res.

speed

timingdyn. range

size

price



www.philips.com/digitalphotoncounting

[email protected]

Thank you for your attention!

•Makoto Tabata•Japan Aerospace Exploration Agency (JAXA)•TIPP 2011 in Chicago

Recent Progress in Silica Aerogel Cherenkov Radiator

Makoto TabataJapan Aerospace Exploration Agency (JAXA)

TIPP 2011 in Chicago

Recent Progress in Silica Aerogel Cherenkov

Radiator

Silica Aerogel

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Silica aerogel is a 3D structural solid of SiO2 particles.

Scanning electron microscope image 10 mg/cc silica aerogel (magnification: x 100,000)

• porous (>99% air)low bulk densitythermal insulator

• transparentΟ(10) nm SiO2 particlesRayleigh scattering

• feel like styrofoam

30 mg/ccsilica aerogel

100 nm

1st method: Single-step method2nd method: Two-step method world standard3rd method: KEK method our original

1.Wet-gel synthesis (sol-gel step) We have various preparation recipes for chemicals.

2.Aging3.Hydrophobic treatment our original4.CO2 supercritical drying 1 month in total

Conventional Production Method

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CO2 autoclave

extract liquid component of wet-

gel through supercritical drying

Wet-gel

Hydrophobic

Refractive index (density) can be controlled in the sol-gel step.

1.Wet-gel synthesis (1st density control)2.Aging3.Pin-drying (2nd density control)

4.Hydrophobic treatment5.CO2 supercritical drying

Pin-drying Production Method

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1.00

1.05

1.10

1.15

1.20

1.25

1.30

0.5 0.6 0.7 0.8 0.9 1.0

length contraction

refr

activ

e in

dex

n0 = 1.06

shrink

original non-shrink aerogel

Semi-sealed container with some pin-holes

several weeks

Pin-drying (PD) method is 4th method to produce aerogelwith high refractive index. need additional time

for the pin-drying process

methanol solvent

Partial evaporation of solventpin-

hole

Reproducibility in PD Method

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1.10

1.15

1.20

1.25

1.30

20% 30% 40% 50%

wet-gel weight

refr

activ

e in

dex

Target n = 1.25 (20 tiles)Target n = 1.20 (10 tiles)

Target n = 1.12 (10 tiles)0.01

0.01

0.005

Target refractive index is well-controlledby monitoring wet-gel weight.

40 tiles were produced forn = 1.25, 1.20 and 1.12.

(Wet-gels were synthesizedfor n0 = 1.06 usingmethanol solvent.)

Refractive index fluctuations were evaluated at each

target index.

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70

1.00 1.05 1.10 1.15 1.20 1.25 1.30

refractive index

tran

smis

sion

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th [m

m]

Conventional (Ethanol)

Conventional (Methanol)

Conventional (DMF)

PD (Methanol)

Expansion of High Index Range in 2005

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Original (non-shrink) aerogeln = 1.06 (methanol)

Ultra-high refractive index (n > 1.10) aerogels with sufficienttransparency (Λ > 20 mm) were developed.

Entirely newrefractive index range

Methanol solvent

0

10

20

30

40

50

60

70

1.00 1.05 1.10 1.15 1.20 1.25 1.30

refractive index

tran

smis

sion

leng

th [m

m]

Conventional (Ethanol)Conventional (Methanol)Conventional (DMF)PD (Methanol)PD (DMF)

Improvement of Transparency in 2008

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Original (non-shrink) aerogeln = 1.066 (DMF)

The transmission length was improved in n > 1.10.

It takes long pin-drying process because DMF is difficult to evaporate.

DMF solvent

0

10

20

30

40

50

60

70

1.00 1.05 1.10 1.15 1.20 1.25 1.30

refractive index

tran

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Conventional (Ethanol)Conventional (Methanol)Conventional (DMF)PD (Methanol)PD (DMF)

The Most Transparent Sample in 2008

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Original (non-shrink) aerogeln = 1.049 (DMF)

The highest transparency (Λ > 50 mm) was obtained in n ~ 1.06.

DMF solvent

1.003 < n < 1.26 available

• n = 1.05 + 1.06, 2 cm thick each (total 4 cm thick)

Np.e. = 10.6 (conventional) 13.6 (improved)60% ring acceptance

• 1.10 < n < 1.231 cm thick each Np.e. = 5-10 (new data)50% ring acceptance

Photoelectron Yield

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0

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1.00 1.05 1.10 1.15 1.20 1.25refractive index

Np.

e./t

rack

MethanolDMFClear Cherenkov

rings were observed.

Standard method

PD method

TransparencyDMF > Methanol

Sufficient photoelectrons were detected.

1 cm thick

Documents

1. 2 3 4 5 6 7 8 Performance of the RICH detectors of LHCb Antonis Papanestis STFC - RAL for the LHCb Collaboration