New experimental techniques: recent developments in ... · Gas detectors working principle Depending on ΔV (and the type of the gas) the detector will work in ionisation mode, proportional

Ecole Doctorale de Physique et Chimie Physique - Mai 2010 1

New experimental techniques:recent developments in particle detectors

Rita De MasiIPHC-Strasbourg


Outline of the course

• Interaction of particles with matter.• Micro-pattern gas detectors.• New generation semiconductor detectors.• Transition radiation detectors.• Cherenkov detectors and RICH.• Nuclear emulsions.• Calorimeters and bolometers.• Two examples of detector systems:

• CMS @ LHC• COMPASS @ SPS


Outline

• Interaction of particles with matter.• Charged particles• The special case of electrons and positrons• Photons• Neutrons• Neutrinos• What are detectors good for?


Interaction of particles with matter

Why:• particle detection• radiation shielding• effects on living organism

Interactions:• electromagnetic• strong• weak


Interaction of particles with matter

Why:• particle detection• radiation shielding• effects on living organism

Interactions:• electromagnetic ⇒ all charged particles, photons (neutrons)• strong ⇒ hadrons (protons, neutrons, …)• weak ⇒ in particular neutrinos!


Charged particles (but electrons)

• collisions with e-

• ionisation of atoms• loss of energy

approximate mean rate energy loss by Bethe-Bloch formula~1% accuracy for mips, otherwise corrections needed

• straggling

- dE = Kz2 Z 1 1 ln 2me c2 β2 γ2 Tmax - β2 - δdx A β2 2 I2 2

β = v/cγ2 = 1/ (1-β2)MeV g-1 cm2


Mean energy loss

From Particle Data Book


Fluctuations in energy loss


Material dependence



Energy loss at low energies

Bragg peak 0

the heavier the projectile, the sharper the peak

application in nuclear radiation therapy


Multiple scattering

θplane = 13.6 MeV z √(x/X0) [1 + 0.038 ln(x/X0)]β c p


Electrons and positrons



Photons

I = I0 e-σnx


Neutrons

• Indirect detection • Nuclear reaction -> detection of secondary particles• Scattering ->Scattered nucleus further ionises• I = I0 e-σnx


What’s about neutrinos?

• Neutrinos interact only by weak interaction!• Detection of the particles produced in its interaction.

νμ μ

W

e νe


Bibliography

• Particle Data Book, http://pdg.lbl.gov/2009/reviews/rpp2009-rev-passage-particles-matter.pdf• W. Leo, Techniques for Nuclear and Particle Physics Experiments, Springer-Verlag• Typically any first chapter of text books on detectors


What are detectors good for?


What are detectors good for?


Micro-pattern gas detectors



Outline

• Problematic• Working principle

• Gas Electron Multiplier (GEM)• Micro-Mesh Gaseous Structure (Micromegas)

• Applications


Gas detectors working principle

Depending on ΔV (and the type of the gas) the detector will work in ionisation mode, proportional mode, Geiger-Müllermode, breakdown.

Wire chambers, drift tubes, resistive plate chambers, time proportional chambers, …

Gas volume

charged particle

+ -- +

- +- +

- +

+ -

+ -+ -

+

-

ΔVCharges migrate to the electrodes

⇓signal


ProblematicFirst gas detector in 1908!

Largely used in particle, nuclear and astro-particle physics, as well as for imaging, material science, security inspection.

Advantages:• Large surface (and limited price) • Very low material budget• Lot of know-how

Disadvantages:• Limited granularity (O(100μm))• Electrical discharges• Aging• Rate limitations• Custom made (and very laborious)


Micro-pattern detectors

• Photolithography technology• Multiplication stage in small region of space• Independent of read-out pattern


Gas Electron Multiplier

F. Sauli et al., NIM A386(1997) 531

50 μm thick kapton foil, copper clad on each side and perforated by high surface density (50-100/mm2) of bi-conical channels.

31 x 31 cm2


Gas Electron Multiplier

Field lines

Ε ~ 100 kV/cm ΔV ~ 500V

tiny proportional chamber


GEM detectors

charged particle

+ -- +

- +- +

- +

+ -

+ -+ -


Triple GEMTriple GEM

reduced gain/foil ⇓

negligible discharge probability



Characteristics of GEM detectors

• spatial resolution 50 μm• gain 105 → single electron detection• ion feedback suppression• efficiency ~ 100%• rate capability 1MHz/mm2

• minor dependence from drift field• highly radiation tolerant• flexible detector shapes and read-out patterns


GEM applications

• Detectors for HEP (also in TPC and RICH detectors)• Dark matter search• Neutron detectors• Plasma monitoring• Photomultiplier• Muon tomography• Medical imaging• Irradiation monitoring during cancer treatment• …


GEM applications



GEM applications



MICROMEsh GAseous Structure

Y. Giomataris et al., NIM A376(1996) 29


MicroMeGaS characteristics

• spatial resolution 12 μm• ion feedback suppression• efficiency ~ 100%• rate capability 109 particles/mm2/s • highly radiation tolerant• flexible detector shapes and read-out patterns


A MicroMeGaS application: Gossip/GridPix

• low drift field (100-700 V/mm)• High amplification field (~10kV/mm) to induce gas avalanche• Micromegas holes centred on pads pixel chip• Avalanche broadened by diffusion to 15-20 μm


Others MicroMeGaS applications

• High energy physics• Neutron beam profile monitoring• …• Potentially similar to GEM


The future?

Electron emission foil with vacuum Micro-Channel Plate

electron emission foil

Minimum Ionising Particle (MIP)

H. van der Graaf, VCI 2010


Bibliography

• http://gdd.web.cern.ch/GDD/ GEM• http://vci.hephy.at/2010 slides and proceedings• http://mpgd.web.cern.ch micropattern gas detectors

http://gdd.web.cern.ch/GDD/

http://vci.hephy.at/2010

http://mpgd.web.cern.ch/


Semiconductor detectors



Outline

• Working principle and radiation damage• Hybrid detectors • Monolithic detectors

• CCD• DEPFET• MAPS

• Integration techniques• Bonding• 3D

• 3D detectors• APD• Diamond


Semiconductor detectors working principle

semiconductor

charged particle

+ -- +

- +- +

- +

+ -

+ -+ -only 3.7 eV to create an e--h pair

(~30 eV for gas )

~ 80 e- created in 1μm O(1

00 μ

m)

they may recombine with thermally generated free charge carriers


Semiconductor detectors working principle

• p-n junction inversely biased for detection• free charge carriers are removed from sensitive volume• signal is collected and processed

semiconductor

charged particle

+ -- +

- +- +

- +

+ -

+ -+ -

O(1

00 μ

m)

n+

p++

-

ΔV


Semiconductors

• Silicon (Si) → most commonly used• Germanium (Ge) → x-ray, infrared, but require cooling• Compound (GaAs, CdTl, SiC, …)


Advantages of semiconductor detectorsSemiconductor detectors crucial for charm discovery!

• High granularity (O(1μm))• High density ⇒ thin (O(100μm))• High rate capability• Rigidity• Electronic can be integrated on the substrate

Some disadvantage:• Cost• Material budget• Radiation damage


Radiation damage

• ionising and non-ionising radiation• surface and bulk damage• Frenkel pair• NIEL

charged particle

vacancy + interstitial


Impact on the detector performances

Valence band

Conduction band

• New energetic levels in the forbidden gap• Leakage current• Charge recombination• Collection time

⇓

decrease of signal-to-noise ratio

can be improved with time, temperature, material engineering, sensor design, …


Working principle

semiconductor

charged particle

+ -- +

- +- +

- +

+ -

+ -+ -

O(1

00 μ

m)

n+

p++

-

ΔV


Strip and pixel detectors

p/n side segmented ⇒ position sensitive device

2nn2

Strip• less channels (2n)• multiple hit ambiguity• double sided segmentation possible, but complex• material budget• better suited for large areas

Pixel• more channels (n2)• no multiple hit ambiguity• 1 sensor gives 2 spatial coordinates• vertex detectors


Hybrid pixel detectors

Used in almost all LHC experiments, X-rays imaging, space radiation detector,…


An example: a Medipix2 detector

http://medipix.web.cern.ch/MEDIPIX

MEDIPIX2 readout chip (series developed for mammography first, for LHC later…)• 1.4 x 1.4 mm2 active area• 55 μm pitch• counting rate 1MHz• noise free• coupled to photon sensitive devices (GaAs, …) for low dose imaging• sensitivity to single photons

MEDIPIX FILM


Monolithic detectors

• Sensing volume and electronics on the same substrate• Thickness, simpler, only one technology


Charge-Coupled Device (CCD)

• Invented in the sixties• Nobel price in 2009• Shift register• High quantum efficiency (70%)• Light detector (found in cameras)• Application in astrophysics, medical imaging, …• Moderate speed• Need trigger to determine position• Sensitive to radiation damage• Needs cooling

Signal treatment


CCD in high energy physics: the SLD vertex detector

• completed in 1996• ~ 3 x 108 pixels• 96 CCD • 80 x 1.6 cm2 sensitive area each• liquid nitrogen cooling• 20 μm pitch• σIP =14 μm for high energy particles• enhancement of heavy quarks measurement performances

• J. Brau, Design and performances of the new CCD vertex detector at SLD and implications for the next linear collider, Nucl.Inst.Meth.A 418-1 (1998) 52• C.Damerell, Charge-coupled devices as particle tracking detectors, Rev.Sci.Intrum. 69 (1998) 1549


DEPleted Field Effect Transistor (DEPFET)

• developed in ’90s• in-pixel detection and amplification• depleted volume• low capacitance -> low noise• low power consumption• collect-read-clear• tracker and X-rays imager

J. Kemmer and G. Lutz, Experimental confirmation of a new semiconductor detector principle, Nucl.Inst.Meth.A 288 (1990) 92


Monolithic Active Pixel Sensor (MAPS)

• CMOS technology• alternative to CCD in commercial application (cameras, video recorder, …)• in-pixel signal treatment



MAPS sensing principleSignal collection

• Charges generated in epitaxial layer → ~1000 e- for MIP.• Charge carriers propagate thermally.• In-pixel charge to signal conversion.

Advantages• High granularity (< 10 μm pitch).• Thickness ( <50μm).• Integrated signal processing.• Standard process (cost, prototyping, …)

Issues• Undepleted volume limitations .

• radiation tolerance.• intrinsic speed.

• Small signal O(100e-)/pixel.• In-pixel μ-circuits with NMOS transistors only.


Basic performances• Room temperature operation.

• Noise ~10-15e-.

• Signal to noise ratio ~ 15-30.

• Detection efficiency ~100% @ fake hit rate O(10-4 -10-5).

• Radiation tol. > 1MRad and 1013neq/cm2 with 10μm pitch (2x1012neq/cm2 with 20μm pitch).

• Spatial resolution 1-5 μm (pitch and charge-encoding dependent).

• Macroscopic sensors (Ex. MIMOSA-5: 1.7 x 1.7 mm2, 106 pixels).

• Used in beam telescopes and VTX demonstrators.

http://www.iphc.in2p3.fr/-CMOS-ILC-.html


An example of sensor: Mimosa-26

• Active area ~2 cm2.

• 0.35 μm technology.

• Binary output (3.5 - 4 μm spatial resolution).

• In-pixel CDS + preamp.

• Column level discrimination.

• Power dissipated ~280 mW/cm2 (rolling shutter).

• Integration time ~100μs.

21.5 mm

13.7

mm

Pixel array: 576 x 1152, pitch: 18.4 µmActive area: ~10.6 x 21.2 mm2

1152 column-level discriminatorsZero suppression logic

Memory IP blocks

Fast full scale sensors: ~10kFrame/scolumn parallel architecture + integrated zero-suppression


MIMOSA-26 beam test

• TAPI = IPHC-Strasbourg BT for MIMOSA development.

• Test @ CERN-SPS (120 GeV π- beam).

• 6 MIMOSA-26 sensors running simultaneously at 80 MHz.

• 3 x 106 triggers.

ε = 99.5 ± 0.1 (stat.) ± 0.3 (prel.) %@ fake hit rate O(10-4)

xz

y


A vertex detector for the International Linear Collider

Sensor requirements• Single point resolution ~ 3μm.• Material budget 0.16/0.11% X0/layer.• Integration time 25 – 100 μs.• 16/15 mm inner radius.• Radiation tolerance ~0.3MRad, few 1011neq/cm2.• O(103) hit pixels/cm2/10 μs on the inner layer.• Averaged power dissipated << 100 W.

Accelerator a (μm) b (μm GeV)LEP 25 70

SLD 8 33

LHC 12 70

RHIC-II 13 19

ILC < 5 < 10

a depends on the intrinsic resolution and inner radius

b depends on material budget

σ IP = a ⊕ b/psin3/2θ


Other HEP applications

CBM @ FAIR Micro vertex detector

STAR @ RHIC pixel detector

Beam telescopes, interest from ALICE @ sLHC, …


Other (non HEP) applications

ebCMOS:• IPHC-IPNL-PHOTONIS.• Single (visible) photon detection.• Fluorescence microscopes.

X-rays :• Direct illumination below 10 keV• Converter above 10keV (Columnar CsI crystals from Hammamatsu)

• Dosimetry, surgery camera, telescope for hadron therapy, …


Integration techniques: bonding

Connect the sensor to its readout electronics• wire bonding• bump bonding


Further developments: 3D IT

Benefits:• Increase integrated processing.• 100% sensitive area.• Select best process per layer task.

To be assessed:• Material budget?• Power dissipation?

Example• Tier1: charge collection.• Tier2: analog signal processing.• Tier3: digital signal processing.• Tier4: data transfer.

R. Yarema, ILC Vertex 2008, Menaggio (IT)


3D sensors

• Increase tolerance to non-ionising radiation• lower depletion voltage• thicker detectors• fast signal• smaller trapping probability• higher capacitance• more complicated fabrication

Parker, Nucl.Instr.Meth. A, 395(1997) 328


Avalanche Photo Diodes (APD)

semiconductor

charged particle

+ -- +

- +- +

- +

+ -

+ -+ -

O(1

00 μ

m)

n+

p++

-

ΔV

ΔV~ 100 V → ~ 1000 Vcharge multiplication

• only e- create secondary charge• single photon detection• proportional mode

• sensitive to voltage and temperature changes• amplification needed• low single photon efficiency

• Geiger mode• high efficiency• low fluxes


Silicon Photomultiplier (SiPM)

• matrix of APDs on a common substrate• output proportional to the number of photons• compact and robust• high quantum efficiency• large gain• fast• can be operated in a magnetic field• calorimeters, medical applications, air-shower Cherenkov telescopes


Diamond detectors

• no doping• low signal• low leakage current • low capacitance• high thermal conductivity• very fast• radiation hard • expensive• RD42 collaboration• ATLAS Beam Conditions Monitor


More bibliography

General• G. Lutz, Semiconductor radiation detector , Springer (1999)• H.G. Moser, Silicon detector systems in high energy physics, Progress in Particle and Nuclear Physics 63 (2009) 186-237Radiation DamageM. Moll, Radiation damage in silicon particle detectors, PhD Thesis (1999)

and several talk at the VCI 2010 conference…


Cherenkov and transition radiation detectors



Outline

• Cherenkov and transition radiation• Working principle• Applications


Cherenkov light

• discovered in 1934 (Nobel prize in 1958)• charged particle in medium radiates if v > c/n• cos ( θ ) = 1/(βn) β = v/c• threshold effect• no energy loss θ


Where do you see Cherenkov light

• nuclear reactors• cosmic rays → air-shower Cherenkov telescopes• labelled bio-molecules


Cherenkov detectors

• exploit the Cherenkov effect to identify particles• v > c/n• two particles with same momentum but different mass will have different velocity


Ring Imaging CHerenkov (RICH) detectors

separate particles as function of θ


Where are the RICHes?

• nuclear and particles experiments• astroparticles• neutrino physics

SuperKamiokande50000 tons of water


Transition radiation

• predicted by Ginsburg and Frank in 1945 (J.Phys. 9 (1945) 353)• particle traversing a boundary of two media with different dielectric properties• no energy loss• ultra-relativistic particles emit TR in the X-band• radiated energy is proportional to the particle’s energy• particle identification at high energy• average number of photons emitted at boundary ~ 1/137


ATLAS Transition Radiation Tracker (TRT)

• LHC experiment aimed at Higgs boson discovery and physics beyond the Standard Model• straw tubes in radiator• 420000 channels








ALICE TRD

• LHC experiment• quark-gluon plasma


TRACER• direct measurements of heavy cosmic ray nuclei (O to Fe) @ 1013 -1014 eV• 4 plastic fibre radiators + double layer of proportional tubes• balloon experiment

http://tracer.uchicago.edu


Alpha Magnetic Spectrometer (AMS)• search for dark matter and anti-matter• to be launched end of 2010 towards ISS

http://www.ams02.org


Bolometers



Definition

• Measurement of electromagnetic radiation via temperature changes• Absorber + heat sink• Optimal for sub-millimetre astronomy (200μm – 1 mm)• Need to be cooled down (tens – hundreds of mK)• Slow• No particle discrimination• Excellent energy resolution (~ 10 eV @ few KeV)

ΔT


Bolometers in nuclear and particle physics

• low energy rare events (a few KeV)• WIMP search• low energy neutrino interactions (double β-decay)• very rare nuclear decays


Scintillating bolometers in WIMP searches: CRESST

• scintillating material @ low temperature• light vs. heat discrimination technique• CaWO4

• feeble scintillating nuclear recoil (WIMP)• electron recoil (large β and γ background)• Gran Sasso laboratories (under ~ 1400 Km rock)• 10 Kg detector (33 modules)• Tungsten superconducting thermometers

http://www.cresst.de


A semiconductor bolometer: EDELWEISS

http://www.edelweiss2.in2p3.fr

• Germanium crystals @ low temperature• ionisation vs. heat discrimination technique• Laboratories @ Modane (under Frejus mountain)• 30 Kg detector


Nuclear emulsions



Working principle

emulsion of silver salts (AgBr)

ionising particle• exposing• developing• observing

+ -+ -+ -- +

- +


Applications

• discovery of cosmic rays (1910)• discovery of pions (1947)• astrophysics• medical radiography• photography


Characteristics

• 3-D spatial information• high granularity ~ 300 hits/mm ⇒ short lived particles• high spatial resolution <1μm

• continuously sensitive • offline analysis ⇒ low cross section experiments

neutrino physicsmicro-autoradiography


OPERA experiment

http://operaweb.lngs.it

• νμ → ντ oscillations• neutrino beam from CERN to Gran Sasso (O(1000 Km))• emulsion cloud chamber (ECC)


Scanning

http://iopscience.iop.org/1742-6596/41/1/023/pdf/jpconf6_41_023.pdf

2 cm2/h → 20 cm2/h


The COMPASS experiment



Physics goals

• nucleon spin structure• gluon polarisation• helicity and transverse parton distribution functions• generalised parton distributions

• hadron spectroscopy• pion/kaon polarisability• glueballs• hybrids• double charmed baryons


N

SPSLHC

Jura

mounta

insLac Léman

COMPASS


SM1SM1

SM2SM2

66LiD or LiD or NHNH33 TargetTarget

160

160 Ge

VGeVμμ

RICH

ECal & HCal

μ filter

SiliconMicromegas

SciFi

GEMs

Drift chambers

StrawsMWPC

50 m

μ filter

• fixed (polarised) target experiment• polarised muon/hadron beams (~ 160 GeV)• ~ 108 particles/s• taking data since 2001

The experiment


The beam reconstruction

SM1SM1

SM2SM2

66LiD or LiD or NHNH33 TargetTarget

160

160 Ge

VGeVμμ

RICH

ECal & HCal

μ filter

SiliconMicromegas

SciFi

GEMs

Drift chambers

StrawsMWPC

50 m

μ filter

350 ps time resolution14 μm spatial resolution


The target

solenoid 2.5Tdipole magnet 0.5Tacceptance ± 180 mrad

3He – 4He dilutionrefrigerator (T~50mK)

μ

6LiD or NH350/90% polarization40/16% dilution factor


The tracking system

SM1SM1

SM2SM2

Micromegas

GEMs

Drift chambers

Straws

MWPC

50 m

Stage 1 (Large Angle Spectrometer)•1Tm•Δp/p ~ 1%•5-50GeVStage 2 (Small Angle Spectrometer)•5.2 Tm•Δp/p ~1%•30-100GeV


The particle identification

RICH

ECal & HCal

μ filter

μ filter

μ→ μ filterπ, K, p separation → RICHe, γ → ECAlhadrons → HCal


The data acquisition system (DAQ)

∼200000 detector channelsup to 100kHz trigger rate40kByte/event → up to 4000MByte/s

SPS duty cycle

4.8s 12 s


Event reconstruction

trackingvertexingPIDcomplete event


Data analysis


The CMS experiment



Main physics goals

• Higgs boson• Extradimensions• Dark matter• SUSY• …


N

SPSLHC

Jura

mounta

insLac Léman

CMS


The detector

proton-proton collider (7+7 TeV)


The detector


One typical event


The GRID 5

• 5 petaBytes/year of data (1015!!!!)• similar to the WEB, but also sharing computing power and storage capacity• presently 200 sites (20000 computers)• simulation of drugs against avian flu and malaria•…

Documents

New experimental techniques: recent developments in ... · Gas detectors working principle Depending on ΔV (and the type of the gas) the detector will work in ionisation mode, proportional