Slide1 l.jpg
This presentation is the property of its rightful owner.
Sponsored Links
1 / 115

High Energy Radiation Phenomena in the Atmosphere PowerPoint PPT Presentation


5th School on Cosmic Rays and Astrophysics, Aug-2012, La Paz, Bolivia.

Download Presentation

High Energy Radiation Phenomena in the Atmosphere

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Slide1 l.jpg

5th School on Cosmic Rays and Astrophysics La Paz, Bolivia August 22nd to 31st , 2012

High Energy Radiation Phenomena in the AtmospherePart I

Prof. Marcelo A. Leiguide Oliveira

CCNH – UFABC

[email protected]


Slide4 l.jpg

Structure of the Atmosphere

  • The atmosphere is a thin layer of gases:

  • 90,0% (h < 10 km);

  • 99,0% (h < 20 km);

  • 99,9% (h < 30 km);

  • etc.


Slide5 l.jpg

Atmospheric layers

Troposphere*: 0 – (7 – 18) km

Stratosphere*: 18 – 50 km

Mesosphere: 50 – 80 km

Thermosphere: 80 – 480 km

Exosphere: > 480 km

* most important for CRs physics


Slide6 l.jpg

Chemical composition of the atmosphere

From Wikipedia


Slide7 l.jpg

  • Basic concepts of energy transport in the atmosphere:

  • Radiation: energy transfer by electromagnetic waves which takes place in vacuum

  • Conduction: transfer of kinetic energy by collisions of molecules

  • Convection: transport of energy by bulk motion of a fluid


Slide8 l.jpg

Electromagnetic waves:

  • oscillating electric and magnetic fields that travel in vacuum in the speed of light: c = 299.792.458 m/s ≈ 3 × 108 m/s

  • the electromagnetic spectrum is continuous and we distinguish

  • different types of waves based on bands of frequency or wavelength

  • within each band different processes may

  • occur, leading to different opacities to the waves


Slide9 l.jpg

Insolation: the amount of solar radiation received at Earth’s surface

The Earth is closest to the Sun on January 3 (perihelion) an farthest from the Sun on July 4 (aphelion)and the revolution axis of the Earth is tilted by 23.5° with respect to the orbital plane, giving rise the seasons, e.g.: winter (summer) in the northern (southern) hemisphere in December.


Slide10 l.jpg

Annual Heat Inbalances and Convections


Slide11 l.jpg

Radiation Balance on Earth

  • The Sun is the major source of energy on Earth

  • The incident energy is partially reflected and partially absorbed in the atmosphere

  • The Earth emits energy by blackbody radiation

  • The radiation is partially scattered by air and aerosol molecules


Slide12 l.jpg

Radiation Balance on Earth

The relevant photons fall into two classes:

Short wavelength (emitted by the Sun): 0.1 < λ < 4.0 µm (ultraviolet, visible and infrared)

Long wavelength (emitted by the Earth’s surface and atmosphere): 4.0 < λ < 100.0 µm (infrared)


Slide13 l.jpg

Blackbody Radiation


Slide14 l.jpg

Blackbody Radiation


Slide15 l.jpg

Blackbody Radiation


Slide16 l.jpg

Blackbody Radiation


Slide17 l.jpg

Blackbody Radiation


Slide18 l.jpg

Blackbody Radiation


Slide19 l.jpg

Blackbody Radiation


Slide20 l.jpg

Stefan-Boltzmann law:

Rate at which objects emit radiation is proportional to the fourth power of the temperature

thus the Sun radiates from its photosphere:

more power than the Earth system.


Slide21 l.jpg

Wien displacement law:


Slide22 l.jpg

Albedo

average Earth’s albedo ≈ 30%


Slide23 l.jpg

Radiation Balance (very simple model)


Slide24 l.jpg

Radiation Balance (very simple model)


Slide25 l.jpg

Radiation Balance + Greenhouse Effect

The atmosphere is our blanket


Slide26 l.jpg

Radiation Balance + Greenhouse Effect


Slide27 l.jpg

Atmospheric Influence on Radiation

  • Upon entering the atmosphere the solar radiation encounters:

  • Gases: atoms and molecules

  • Particles (aerosols): large molecules and dust

  • Clouds: water

and 3 processes may happen:

Scattering

Transmission

Absorption


Slide28 l.jpg

Atmospheric Scattering

This is the process where an atom or a molecule redirects the energy:

if the outgoing energy (wavelength) is the same: Elastic Scattering

if the outgoing energy (wavelength) is different: Inelastic Scattering

and there may be 3 types of scatterings:

Rayleigh Scattering: by atoms and small molecules

Mie Scattering: by large molecules or aerosols

Non-selective Scattering: by clouds


Slide29 l.jpg

Rayleigh Scattering

This is the process caused by atoms or small molecules (size < ):

if the outgoing energy (wavelength) is different: Raman Scattering


Slide30 l.jpg

Rayleigh Scattering

The Rayleigh scattering is nearly isotropic:and is inversely proportional to 4Conclusion: the sky is blue!! … and the sunset is red


Slide31 l.jpg

Mie Scattering

This is the process caused large molecules & aerosols (size > ):

It is not (hardly) dependent on , but on the size of the particles. The radiation is scattered predominantly in the forward direction.


Slide32 l.jpg

Rayleigh x Mie Scattering


Slide33 l.jpg

Non-selective Scattering

This is the process caused by water droplets which are translucent and curved, (acting like lenses) bending and reflecting the light:

the size of water droplets is important, since it will influence on the curvature of the water droplets. Light passing though clouds is an excellent example of non-selective scattering


Slide34 l.jpg

Transmission

  • Direct passage of light though the atmosphere:

  • on a sunny day, without pollution and water vapor as much as 80% of sunlight may reach the surface

  • as the pollution, water vapor and the amount of clouds increase, the amount of light reaching the surface can drop to zero.


Slide35 l.jpg

Absorption

Any specie that absorbs solar radiation reducing its intensity while passing through the atmosphere.

Molecular collisions are always occurring and are likely to take place while some of the colliding molecules happens to be in an excited state (due to a previous process) before the reemission. In this case, the excitation is transferred to other kinds of energy: kinetic, rotational, vibrational, ionization …


Slide36 l.jpg

Absorption

Absorptions don’t occur in the same way for all the wavelengths


Slide37 l.jpg

Absorption of UV light by stratospheric ozone


Slide38 l.jpg

Extinction


Slide39 l.jpg

Size parameter


Slide40 l.jpg

Radiation Balance on Earth


Slide41 l.jpg

Recent human activity


Slide42 l.jpg

And what about the cosmic rays?


Slide43 l.jpg

And what about the cosmic rays?


Slide44 l.jpg

5th School on Cosmic Rays and Astrophysics La Paz, Bolivia August 22nd to 31st , 2012

High Energy Radiation Phenomena in the AtmospherePart II

Prof. Marcelo A. Leiguide Oliveira

CCNH – UFABC

[email protected]


Slide45 l.jpg

Electromagnetic Processes

Coulomb scattering


Slide46 l.jpg

Electromagnetic Processes

Ionization loss


Slide47 l.jpg

Electromagnetic Processes

Ionization loss


Slide48 l.jpg

Electromagnetic Processes

Air Fluorescence

Measured fluorescence spectrum in dry air at 800 hPa and 293 K

F Arqueros, F Blanco and J Rosado, New J. Phys. 11 (2009) 065011

AIRFLY Collaboration, Astroparticle Physics, Volume 28, Issue 1, September 2007, Pages 41-57,


Slide49 l.jpg

Electromagnetic Processes

Cherenkov light


Slide50 l.jpg

Electromagnetic Processes

Compton scattering


Slide51 l.jpg

Electromagnetic Processes


Slide52 l.jpg

Electromagnetic Processes

Inverse Compton Effect


Slide53 l.jpg

Electromagnetic Processes

Bremsstrahlung


Slide54 l.jpg

Electromagnetic Processes


Slide55 l.jpg

Electromagnetic Processes


Slide56 l.jpg

Electromagnetic Processes


Slide57 l.jpg

Electromagnetic Processes

Molecular Bremsstrahlung

EAS particles dissipates energy through ionization

A weakly ionized plasma is formed at T ~ 104 K

This plasma cools down very fast (10 ns) though collisions with air molecules

Bremsstrahlung from free electrons (f ~ GHz: microwave band)


Slide58 l.jpg

Electromagnetic Processes

Synchrotron radiation


Slide59 l.jpg

Electromagnetic Processes

Radio emission

EAS produces e± in the shower front (2-3 m thick)

These e±bend in the geomagnetic field (~ 0.3 G), generating synchrotron radiation (geosynchrotron)

Emissions for all e± add up coherently

The radiation can be detected by antennas at f ~ 100 MHz (FM band)


Slide60 l.jpg

Electromagnetic Processes

Pair production


Slide62 l.jpg

Chemical composition of the atmosphere


Slide63 l.jpg

Mass Thickness & Depth


Slide64 l.jpg

Mass Thickness & Depth


Slide72 l.jpg

5th School on Cosmic Rays and Astrophysics La Paz, Bolivia August 22nd to 31st , 2012

High Energy Radiation Phenomena in the AtmospherePart III

Prof. Marcelo A. Leiguide Oliveira

CCNH – UFABC

[email protected]


Slide74 l.jpg

  • Some EAS arrays:

  • • VolcanoRanch, USA (1959-1962);

  • • Haverah Park, UK (1968-1987);

  • • SUGAR, Australia (1968-1979);

  • • Yakutsk, Russia (1969 -1990);

  • • Akeno, Japan (1980 ++);

  • • AGASA, Japan (1986 ++ );

  • • EASTOP , Italy (1989-1999);

  • • CASA/MIA, USA (1990 ++);

  • • Kascade, Germany (1995 ++);

  • Pierre AugerObservatory, Argentina (2001++).

1994 The AGASA Group in Japan and the Yakutsk group in Russia each reported an event with an energy of 2x1020eV.

Pierre Auger Observatory: taking data since 2004


Slide80 l.jpg

Cherenkov Radiation in the Atmosphere


Slide81 l.jpg

  • Some air Cherenkov experiments:

  • CANGAROO, Australia (1992++);

  • CAT, France (1996++);

  • CLUE, CanaryIslands (1997 - 2000);

  • HAGAR Telescope(s), India (2005++);

  • HEGRA, CanaryIslands (1992-2002);

  • HESS, Namibia (HESS-I 2002, HESS-II 2012);

  • MAGIC, CanaryIslands (2003++);

  • VERITAS, USA (2007++);

  • CTA project.

HESS I and HESS-II: four 12 m telescopes andone 28 m telescope

MAGIC: a 17 m telescope

VERITAS: four 12 m telescopes


Slide82 l.jpg

Cherenkov Radiation in the Atmosphere


Slide83 l.jpg

Cherenkov Radiation in the Atmosphere


Slide84 l.jpg

Air Fluorescence Detector

Propagation

Emission

Detection

Fluorescence Radiation


Slide85 l.jpg

  • Some airfluorescenceexperiments:

  • • Fly’seye/Hires, USA (1981/1999 ++);

  • Pierre AugerObservatory, Argentina (2001++);

  • ASHRA, Hawaii (2002++);

  • Telescope Array (TA), USA (2006++);

  • EUSO, ISS (2016)

1991 The Fly's Eye cosmic ray research group in the USA observed a cosmic ray event with an energy of 3x1020eV.

The Telescope Array

The Pierre Auger Fluorescence Detector


Slide86 l.jpg

  • Fluorescence track reconstruction

  • monocular mode

  • stereo mode

    issues:

  • - atmospheric transmission

  • - fluorescence yield

  • - Cherenkov subtraction


Slide87 l.jpg

  • Horizontal attenuation monitors (range ~ 60 km)

  • Steerable LIDARs

  • Laser Shots (Central Laser Facility): light scattering

  • Infrared Monitors (clouds)

  • Cross-checks


Slide88 l.jpg

  • The fluorescence yield depends on the:

  • wavelength: 34 transitions between 295 and 430 nm (2P and 1N systems)

  • pressure

  • temperature


Slide89 l.jpg

this event: intial viewing angle 15°, i.e. large direct Cherenkov contribution

iterative procedure, converges in < 4 steps; energy here ~ 2x1018 eV


Slide92 l.jpg

20 May 2007 E ~ 1019eV


Slide93 l.jpg

FD: 24 (+3) fluorescence

telescopes (30° x 30° FOV):


Slide94 l.jpg

  • FD: 24 (+3) fluorescence

  • telescopes (30° x 30° FOV):

  • longitudinal development


Slide95 l.jpg

TheShower Detector Plane


Slide96 l.jpg

TheShower Detector Plane


Slide97 l.jpg

TheShower Detector Plane


Slide98 l.jpg

  • FD: 24 (+3) fluorescence

  • telescopes (30° x 30° FOV):

  • longitudinal development


Slide99 l.jpg

  • FD: 24 (+3) fluorescence

  • telescopes (30° x 30° FOV):

  • longitudinal development


Slide100 l.jpg

  • FD: 24 (+3) fluorescence

  • telescopes (30° x 30° FOV):

  • longitudinal development


Slide101 l.jpg

  • FD: 24 (+3) fluorescence

  • telescopes (30° x 30° FOV):

  • longitudinal development

  • 10% dutycycle

  • almostcalorimetricmeasurement


Slide102 l.jpg

S38 (1000)vs. E(FD)

661 hybrid events

J. Abraham etal, Phys. Rev. Lett. 101, (2008) 061101.


Slide104 l.jpg

Flux calculation:

J. Abraham etal, Phys. Lett. B 685 (2010) 239-246.


Slide105 l.jpg

A bit of propaganda:


Slide113 l.jpg

Light pollution in Brazil:


Slide115 l.jpg

MuchasGracias!

Prof. Marcelo A. Leiguide Oliveira

CCNH – UFABC

[email protected]


  • Login