Physics & Detection of AstroParticles Introduction Introduction - LUTH

Physics & Detection of AstroParticles

Introduction Introduction

Andreas Zech, LUTH, Observatoire de Paris 2011

Outline Introduction A Tools 1 overview of special relativity 2 standard model of particles (in a nutshell) B High Energy Photons 1 X-ray astronomy 2 γ-ray astronomy C Cosmic Rays & Neutrinos

Detection (detectors, instrumentation, recent projects)

1 low energy cosmic rays 2 (ultra-) high energy cosmic rays 3 neutrino astrophysics D Dark Matter in Astroparticle Physics

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Research Topics (a selection of physics topics in the field)

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What (not) to expect from this course This course is intended to give an introduction into several fields of astrophysics, regrouped as "high energy astrophysics" and/or "astro-particle physics". Such a course cannot be complete. A researcher in a field such as e.g. gamma-ray astrophysics uses methods from many different sources (electro-dynamics, relativity, quantum mechanics, MHD, statistics, electronics ...). We will discuss a selection of physics topics and introduce the most common detection methods and their application in experiments/projects. Suggestions for further reading are given to allow a deeper understanding of the different subjects...

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Particle interactions (1) Interactions of massive particles and photons (both are 'particles') with matter and electromagnetic fields will play a central role in this course. We need to understand them to get an insight into: - the physical mechanisms of particle detectors - the underlying processes in astrophysical objects emitting high energy particles

interactions of high energy photons with matter - photoelectric absorption, spectral absorption and emission lines - (inverse) Compton scattering - electron-positron pair production

e.g. Compton scattering

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Particle interactions (2) interactions of massive high energy particles with matter and e.m. fields - ionization - bremsstrahlung (free-free emission) - Cherenkov radiation - nuclear interactions and spectral lines - (electron-positron) pair creation - synchrotron radiation

e.g. bremsstrahlung

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Some Detector Types in High Energy (Astro)physics –

proportional and Geiger counters

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wire chambers, drift chambers

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spark chambers

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semiconductor devices (e.g. CCDs, photodiodes, silicon strip detectors)

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scintillation detectors

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transition detectors

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photo-multiplier tubes

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e.g. photo-multiplier tube from the Antares experiment

calorimeters

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experiments / projects we will discuss ●

X-ray astronomy –

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Compton Gamma-Ray Observatory

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Suzaku

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Fermi

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VHE gamma-ray astronomy –

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HESS (Cherenkov telescopes) Milagro (air shower array)

cosmic rays –

Chandra satellite

gamma-ray astronomy –

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AMS

ultra-high energy cosmic rays –

HiRes telescopes

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Pierre Auger Observatory

(astro-) neutrinos –

Super-Kamiokande

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Antares, IceCube

dark matter –

Edelweiss (?)

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Bibliography ●

High Energy Astro(particle) physics: ●

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Charles D. Dermer & Govind Menon: High Energy Radiation from Black Holes, Princeton Series in Astrophysics, 2009

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G.B. Rybicki, A.P. Lightman: Radiative Processes in Astrophysics, Wiley-VCH 2004

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Instrumentation in Particle Physics: –

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Particle Detector BriefBook: http://rkb.home.cern.ch/rkb/titleD.html

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Particle Data Group: http://pdg.lbl.gov/2006/reviews

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Donald H. Perkins: Introduction to High Energy Physics , Cambridge University Press 2005

Everything you ever wanted to know about Electrodynamics and Special Relativity (and more): –

Dan Green: The Physics of Particle Detectors , Cambridge University Press 2000

Donald H. Perkins: Particle Astrophysics , Oxford Master Series, 2003

Particle physics:

Radiative Processes –

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Malcolm S. Longair: High Energy Astrophysics I & II, (Second Edition) Cambridge University Press 1992

Astroparticle physics:

J.D.Jackson, Classical Electrodynamics , John Wiley & Sons, Inc.

Details on different experiments: Webpages of NASA, ESA, H.E.S.S., Auger, etc. ...

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Organisation du cours ●

~40h de cours; 20h de TD et "journal club"

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polycopies seront disponibles sur internet (mises à jour régulièrement)

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TD sous forme d'exercices (petits calculs)

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"journal club": lecture de papiers scientifiques, présentations des papiers (un par étudiant(e)), questions et discussion (en groupe)

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Au lieu d'un examen: Rédaction d'un rapport sur un sujet dans l'astrophysique des hautes énergies sous la forme d'un court papier scientifique (projet de bibliographie). Des détails seront donnés plus tard. Notes: –

60% : TD (exercices, présentations)

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40% : rapport

Possibilité d'avoir (quelques) cours en anglais (aussi présentations, rapports) !

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Introduction to High Energy Astro(particle) physics

© ASDC A. Zech, Physics & Detection of AstroParticles, Intro

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What is "High Energy Astrophysics" ? There is not a really precise definition of "High Energy Astrophysics". Two characteristics are: - In "High Energy" observations, the particle character of light (= photons) becomes significant. => instruments resemble detectors from particle physics experiments - "High Energy" radiation and particles are often connected to non-thermal sources (this is not true in general for X-rays). => observation of highly energetic particle accelerators (shocks, accretion, ...) There is also no clear difference between "High Energy Astrophysics" and "Astroparticle Physics". We will discuss observation of X-rays and Gamma-rays (electromagnetic radiation), but also of cosmic rays and neutrinos (massive particles). Certain aspects of dark matter (and gravitational waves) fall into the domain of Astroparticle physics. We will discuss dark matter briefly in this course. A. Zech, Physics & Detection of AstroParticles, Intro

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Thermal radiation Thermal radiation is the transfer of heat from a material by means of electromagnetic radiation and depends on the material's characteristic emissivity and temperature. Thermal radiation results from the movement of charged particles (protons and electrons) in a material. Thermal radiation is responsible for much of the radiation observed in the radio/IR/optical/UV and up to the X-ray band. Black-body radiation is thermal radiation from an idealized object, a black body in thermal equilibrium. Black bodies absorb all radiation that falls onto them (no reflection or transmission, emissivity=1) and re-emit radiation in a continuous spectrum, depending only on their temperature. Celestial objects can often be described as black bodies (stars, gas clouds, CMB, etc. ). The black-body emission spectrum is described by Planck's law:

2 h 3 1 I  = ⋅ h c² e kT −1 Planck's law: I(ν)dν : thermal emission of a «black body» (erg cm-2 s-1 sr-1 in interval between ν and dν)

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Non-thermal radiation In high-energy astrophysics, we often deal with non-thermal radiation. This is e.m. emission from particles with kinetic energy not due to heat, but due to some acceleration process. Charged particles can for example be accelerated by shock fronts inside a plasma, by electromagnetic fields, magnetic reconnection etc. Non-thermal radiation is often characterized by a power-law distribution of the emitted light. A typical example would be the synchrotron emission from AGNs that is seen from the radio to the X-ray range.

synchrotron emission from M87

T. Berghöfer et al., ApJ 535, 615 (2000)

Even though certain emission processes, like synchrotron radiation, are often linked to nonthermal radiation, the "non-thermal" aspect is really determined by the underlying particles' distribution and not by the emission process. A. Zech, Physics & Detection of AstroParticles, Intro

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High energy vs. low energy astronomy high energy astronomy (X-ray, γ-ray) astroparticle physics

UV

optical

IR

radio

h > kT

energy of radiation is much smaller than T of sky, telescope or detector.

energy of radiation is much larger than T of sky, telescope or detector. description of radiation as particles (photons); wave properties negligible

description of radiation as electromagnetic waves

=> angular resolution of telescopes determined by geometric optics

=> angular resolution of telescopes determined by diffraction optics

=> sensitivity of telescopes limited by statistics of source photons and background photons (or cosmic rays)

=> important thermal/optical background from sky, telescope and detector limits the sensitivity

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The electromagnetic and cosmic ray spectrum Solar c.r.

energy:

eV

meV

eV

keV

Galactic c.r. MeV

GeV

TeV

Galactic c.r.

energy:

TeV

Extra-galactic c.r. (?) ------> | PeV

EeV

ZeV

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astrophysical sources in different wavebands ●

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radio (3MHz – 30 GHz / 100m – 1cm) –

thermal bremsstrahlung from ionised hydrogen

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neutral hydrogen (21 cm line)

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synchrotron radiation from relativistic plasma (interstellar magnetic field, radio lobes of active galaxies, quasars, pulsars...)

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(sub-)millimeter (30 GHz – 3 THz /10 – 0.1 mm) ●

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thermal bremsstrahlung from ionised hydrogen

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observation of molecular lines

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Cosmic Microwave Background

infrared (3 THz – 30 THz / 0.1 mm – 1 μm) –

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optical (30 THz – 1 PHz / 1 μm – 300 nm) –

planets, stars, galaxies ...

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emission and absorption features

ultraviolet (1 PHz – 30 PHz / 300 – 10 nm) –

thermal radiation, non-thermal radiation from active galaxies and quasars

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resonance lines of ions, atoms

X-ray (30 PHz – 30 EHz / 10 nm – 10 fm) –

supernova remnants, AGN, pulsars, binaries

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thermal bremsstrahlung in galaxy clusters

γ-ray (> 30 EHz / < 10 fm / E > 100 keV) –

thermal emission from stars, galaxies, AGN...

non-thermal processes (bremsstrahlung, inverse Compton, decay of pions...)

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radioactive elements (line emission)

emission from dust grains

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e+e- annihilation line (511 keV)

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SN remnants, AGN, pulsars, γ-ray bursts

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Atmospheric Absorption of Electromagnetic Radiation

image taken from NASA A. Zech, Physics & Detection of AstroParticles, Intro

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Observation in different wavebands ●

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radio (3MHz – 30 GHz / 100m – 1cm) –

at low frequencies reflection of radio waves in plasma (ionosphere, interplanetary, interstellar)

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radio antennas, arrays of antennas

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ozone & molecular absorption in atmosphere -> satellites

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at short wavelengths, photoelectric absorption by Lyman continuum of neutral hydrogen (interstellar gas)

at short wavelengths, absorption in atmosphere (water vapour, molecules) -> high, dry sites

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X-ray (30 PHz – 30 EHz / 10 nm – 10 fm) –

atmosphere is opaque to X-rays -> satellites

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grazing incidence optics, particle physics type detectors

infrared (3 THz – 30 THz / 0.1 mm – 1 μm) –

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ultraviolet (1 PHz – 30 PHz / 300 – 10 nm)

(sub-)millimeter (30 GHz – 3 THz / 1cm – 0.1 mm) –

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large thermal background, absorption in atmosphere -> high, dry sites for certain wavebands, balloons, aircraft, satellite

optical (30 THz – 1 PHz / 1 μm – 300 nm) –

at short wavelengths, absorption by ozone in upper atmosphere; scattering (Rayleigh & Mie)

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telescopes, CCDs ...

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γ-ray (> 30 EHz / < 10 fm / E > 100 keV) –

photoelectric absorption, Compton scattering, pair production -> satellites

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particle physics type detectors

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E > 100 GeV : indirect detection (air shower)

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A bit of history of High Energy Astrophysics ●

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Until ~1945 astronomy was restricted to optical astronomy. Advances in electronics, radio techniques and computers led then to radio astronomy and the study of highly energetic sources (radio galaxies, AGN, pulsars...)

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First rocket flights with X-ray detectors in 1962 and 1963. Detection of Crab nebula, M87...

First evidence of γ-ray line emission found in balloon observations in the early 1970s.

Ground based cosmic ray detectors observe indirectly cosmic rays of much higher energies than was possible with balloon flights. One of the first ground arrays was Volcano Ranch in the 1960s. The air fluorescence technique has helped to improve the energy resolution significantly.

First dedicated X-ray satellite UHURU in 1970s maps the X-ray sky. γ-ray emission from the Galactic plane was first discovered in 1967 by the OSO III satellite.

Ground based Air Cherenkov telescopes allow today the indirect observation of TeV γ-rays. (e.g. Whipple in 1980s)

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Detection of solar neutrinos (Cl37) and of neutrinos from the SN1987A supernova in 1987 (Kamiokande) laid the foundation for neutrino astronomie. This is today still a field in its infancy.

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