INSTRUMENTATION & DETECTORS for HIGH ENERGY PHYSICS I

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28th June-4th July 2017 Isabelle Wingerter-Seez (LAPP-CNRS) - CERN Summer Students Program

INSTRUMENTATION

&

DETECTORS for

HIGH ENERGY PHYSICS I

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28th June-4th July 2017 Isabelle Wingerter-Seez (LAPP-CNRS) - CERN Summer Students Program

TODAY

INTRODUCTION

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28th June-4th July 2017

WHAT IS A PARTICLE DETECTOR ?

An apparatus able to

detect the passage of a particle and/or localise it

and/or measure its momentum or energy and/or identify its nature

and/or measure its time of arrival

…..

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WHY DO WE NEED PARTICLE DETECTORS ?

An astronomer uses a telescope A biologist uses a microscope

We (a lot of us at least) use a camera to take a snapshot of reality

Particle physicists invent, build and operate detectors to record the products of initial particles interactions:

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Initial state

KNOWN Interaction

?

Final state UNKNOWN

DETECTOR

to record the final state for physicists to interpret the nature of

the interaction

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WHAT ARE WE LOOKING FOR ?

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ELEMENTARY PARTICLES and FORCES

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PARTICLES

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PARTICLES

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H,

+ the ones we have not yet observed

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KNOWN PARTICLES

HOW CAN A PARTICLE DETECTOR

DISTINGUISH

THE PARTICLES WE KNOW

MEASURE PROPERTIES of PHYSICS PROCESSES

IDENTIFY THE EXISTENCE   OF A NEW PARTICLE

?

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H,

+ the ones we have not yet observed

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ELEMENTARY PARTICLES MASS

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Mass of elementary particles in not

predicted by the Standard Model of

Particle Physics.

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PARTICLES MASSES

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Tables of masses for known particles

(here baryons - 3 quarks)

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PROPERTIES of PARTICULES

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Ta b l e s o f d e c a y modes for known particles

(here for lepton τ)

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LIMITED SIZE DETECTOR

Among these 180 listed particles,

27 have a long enough lifetime

such that, for GeV energies, they travel more than one micrometer

Among these 27,

14 have c.τ <0.5 mm and leave a very short track in the detector

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THE 13 PARTICLES A DETECTOR MUST BE ABLE TO MEASURE AND IDENTIFY

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UNITS in HEP & International System

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HOW to MEASURE PARTICLE PROPERTIES

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EXAMPLES of INTERACTIONS

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Ionisation Production de paires e ⁺ e ^-

Diffusion

Compton

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RADIATION LENGTH

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E ₀

1X ₀

0,37 E ₀

1

3

2 The radiation length is a “universal” distance, very useful to describe electromagnetic showers (electrons & photons)

X 0 is the distance after which the incident electron has radiated (1-1/e) 63% of

its incident energy, via Bremsstrahlung.

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TOTAL ENERGY LOSS by ELECTRONS

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µ ⁺ in COPPER

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PROTON-PROTON INTERACTIONS

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x

y

θ z φ

p _T p

proton 1 proton 2

η=-ln tan(θ/2) p p1 +p p2 =0

√s=E p1 +E p2 → √s dure =E parton1 +E parton2

M 12 =√[2E 1 .E 2 (1-cosα 12 )]

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PROTON-PROTON INTERACTIONS

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x

y

θ z φ

p _T p

proton 1 proton 2

η=-ln tan(θ/2) p p1 +p p2 =0

√s=E p1 +E p2 → √s dure =E parton1 +E parton2

M 12 =√[2E 1 .E 2 (1-cosα 12 )]

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DETECTOR at LHC - Challenge

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40 millions beam crossing/s

1 billion collisions/s

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DETECTOR: PRINCIPLE

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DETECTORS: TRACKING

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1X 0 >30X 0 2X 0 ~ qques X 0

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MAGNETIC ANALYSIS

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MAGNETIC ANALYSIS

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Charged particle of momentum p in a magnetic field B

If the field is constant and we neglect the presence of matter, the momentum is constant with time, the trajectory is helical.

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What can you say

about this event ?

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ATLAS TRACKING SYSTEM

Detector SCT 60 m

²

- 6 M channels

Barrel 4 cylindres at R=300, 373, 447 & 520 mm Forward 9 disks on each side

~4000 modules

Cell width 80 µm ⟹ σ

^pos

= 23 µm 8 points per trace

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B

Pixels detector 1.7 m

²

- 80 M de canaux

1744 pixel modules avec 46080 pixels/mod.

Each cell : 50x400 µm

²

⟹ σ

^pos

=14/115 µm

Barrel R= 33.6, 50.5, 88.5 & 122.5 mm

Forward R coverage 9-15 cm

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TRACKING DETECTOR: CMS pixel module

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10 µm

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TRACKING DETECTOR: ATLAS pixel module

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CONNECTION SENSOR-ELECTRONICS

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Connection between the silicium sensor and the reluctancies chip readout Very high density ~15 wires/mm

Connection via ultrasounds of wires of thickness ~20µm

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TRACKING DETECTOR: new PIXEL layer installed in 2014 at R=3.3 cm

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Barrel 4 cylinders at R=300, 373, 447 & 520 mm (r-φ & z precision coordinates)

Endcap 9 disks on each side

~4000 modules

Each strip has 80 µm pitch ⟹ σ ^pos = 23 µm 8 points per track

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PILE-UP of COLLISIONS

Multi-collisions per beam crossing

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10 ¹¹ protons/bunch 10 ¹¹ protons/bunch

Ability to separate individual collisions - 40 MHz

Χ 10-20..50

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TRACKING DETECTOR

Measure charged particles momentum Uniform magnetic field

High position resolution ⟶ high momentum resolution

Close to the beams

⟶ high particle density

⟶ small cell size

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DETECTOR: CALORIMETERS

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INTERACTIONS vs INCOMING PARTICLES

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C A L O R I M E T E R S A R E DESTRUCTIVE

PARTICLES DO NOT COME OUT of THE CALORIMETER

E L E C T R O N S , P H O T O N S , HADRONS

A R E A B S O R B E D b y t h e CALORIMETERS

ONLY MUONS and NEUTRINOS

ESCAPE

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EXAMPLES of INTERACTIONS

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Ionisation Production de paires e ⁺ e ^-

Diffusion

Compton

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ELECTROMAGNETIC SHOWER

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e ^- / e ⁺ E _e <E _c e ^- / e ⁺ E _e >E _c

photon

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The CAVERN has a FINITE SIZE

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CALORIMETERS measure PARTICLE ENERGY

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Module 400 crystals

75k channels

ΔE/E ~ 3-5%/√E ⊕ 150 MeV/E ⊕ 0.5%

~ 30 cm

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CONSTRUCTION of the CMS CALORIMETER

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Submodule 2x5 crystals

Supermodule 1700 crytsals

Total 36 Supermodules

Module

400 crystals

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CONSTRUCTION du CALORIMETRE de CMS

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Jul 2007

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DETECTEURS: SPECTROMETRE à MUONS

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MUONS

µ is the brother of the electron with m µ =200 x me Electromagnetic interaction: 1/m ²

µ interact with matter 40000 times less than electrons

They essentially do not notice the presence of the calorimeter Detection with the muon spectrometer

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AIR CORE TOROID

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Text

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MUON SPECTROMETER

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Magnetic field: air core toroïd

44 m 25 m

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MUON SPECTROMETER

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MUON SPECTROMETER

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+ straight tracks

sagitta

→ ~40µm B

~5 m

Specific to ATLAS : Air core Toroïd

Minimise matter encounter by muons WHY ???

p T <100 GeV δp T /p T ~2%

p T ~1 TeV δp T /p ^T ~10%

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MUON CHAMBERS in ATLAS

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TOROID + MUON CHAMBERS

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DETECTOR MISSING TRANSVERSE ENERGY

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ENERGY BALANCE

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DETECTOR: INTRODUCTION QUIZZ

What is a detector ?

What does a detector measure ?

How is a detector designed ?

Compare a digital camera with the ATLAS detector

Would you join an experiment where the calorimeter is in front of the tracking system ?

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CREDIT and BIBLIOGRAPHY

A lot of material in these lectures are from:

Daniel Fournier @ EDIT2011 Marco Delmastro @ ESIPAP 2014 Weiner Raigler @ AEPSHEP2013

Hans Christian Schultz-Coulon’s lectures Carsten Niebuhr’s lectures [1][2][3]

Georg Streinbrueck’s lecture Pippa Wells @ EDIT2011

Jérôme Baudot @ ESIPAP2014

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INSTRUMENTATION & DETECTORS for HIGH ENERGY PHYSICS I