Prof. Marcelo A. Leigui de Oliveira

CCNH – UFABC

leigui@ufabc.edu.br

Física de Astropartículas – as propriedades e técnicas de detecção dos

Raios Cósmicos de Ultra-Alta Energia.

Universidade Federal de Santa Catarina,

Florianópolis, SC

14 de setembro de 2012

Artistic view of a cosmic rays shower.

Credit: ASPERA/Novapix/L.Bret

• More than 100,000 cosmic rays will hit each of you during this

lecture

What are Cosmic Rays? Cosmic Rays (CR) are high-energy particles of extraterrestrial

origin

Secondary CR (produced by the primaries in the

Earth’s atmosphere) consist of essentially all

elementary particles and nuclei (both stable and

unstable). The most important are

• nucleons, nuclei & nucleides,

• (hard) gammas,

• mesons (p±,p0,K±, …, D±,…),

• charged leptons (e±, m±, t±),

• neutrinos & antineutrinos (ne, nm, nt).

“Classical” CR are nuclei or ionized atoms ranging from a

single proton up to an iron nucleus and beyond, but

being mostly

protons (~90%) and particles (~9%).

Including stable and quasistable particles:

• neutrons,

• antiprotons & (maybe) antinuclei,

• hard gamma rays (l < 10-12 cm),

• electrons & positrons,

• neutrinos & antineutrinos,

• esoteric particles (WIMPs, magnetic monopoles,

mini black holes,...)?

A short history of cosmic ray physics

• 1900 C.T.R. Wilson noticed that electroscopes lose their charges

even if they were very well isolated from the neighbouring sources;

• 1900 C.T.R. Wilson noticed that electroscopes lose their charges

even if they were very well isolated from the neighbouring sources;

• 1900 C.T.R. Wilson noticed that electroscopes lose their charges

even if they were very well isolated from the neighbouring sources;

• 1900 C.T.R. Wilson noticed that electroscopes lose their charges

even if they were very well isolated from the neighbouring sources;

• E. Rutherford hypothesised that most of the ionisation was

due to natural radioactivity;

but much more penetrating than natural radioactivity!

• 1910 T. Wulf who developed the best electrometers of that time, measured a

fall from 22,25 ions/cm3 s (~ sea level) to 15,7 ions/cm3 s, at the top of the Eiffel

Tower (330 m asl) but they should have halved in 80 m;

Victor F. Hess after one of his successful flights in 1912.

•1912 Hess ascended in his balloon to 5 km (in an open ballon without

oxygen!) and measured unambiguously an increase in ionisation (4 times

more discharges at 4880 m): there must be a radiation of cosmic origin

ionizing the atmosphere;

1936 Hess &

Anderson

• 1931 Auguste Piccard took off from Augsburg with a pressurized cabin

to reach a record altitude of 15,785 m. During this flight, Piccard was

able to gather substantial data on the upper atmosphere, as well as

measure cosmic rays. In 1932, launched from Zürich to made a second

record-breaking ascent to 16,200 m. He ultimately made a total of

twenty-seven balloon flights setting a final record of 23,000 m.

• 1931 Auguste Piccard took off from Augsburg with a pressurized cabin

to reach a record altitude of 15,785 m. During this flight, Piccard was

able to gather substantial data on the upper atmosphere, as well as

measure cosmic rays. In 1932, launched from Zürich to made a second

record-breaking ascent to 16,200 m. He ultimately made a total of

twenty-seven balloon flights setting a final record of 23,000 m.

• 1936 G. Pfotzer used three-fold coincidences of GM tubes to measure

intensities up to 28 km

• 1948 J.A. Van Allen used single GM tube aboard a V-2 rocket to

measure intensities up to 161 km.

Back in 1938:

1 eV = 1,6 x 10-19 J ↔ 1J = 6,25 x 1018 eV

1 x 1020 eV = 16 J

Some EAS arrays:

• Volcano Ranch, 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 Auger Observatory, Argentina (2001++).

1994 The AGASA Group in Japan and

the Yakutsk group in Russia each

reported an event with an energy of

2x1020 eV.

Pierre Auger Observatory: taking data

since 2004

Other measurement techniques

Fluorescence and Cherenkov Lights

Emission Propagation

Air Fluorescence Detector

Detection

Cherenkov Light

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Cherenkov Radiation in the Atmosphere

Some air Cherenkov experiments:

• CANGAROO, Australia (1992++);

• CAT, France (1996++);

• CLUE, Canary Islands (1997 - 2000);

• HAGAR Telescope(s), India (2005++);

• HEGRA, Canary Islands (1992-2002);

• HESS, Namibia (HESS-I 2002, HESS-II

2012);

• MAGIC, Canary Islands (2003++);

• VERITAS, USA (2007++);

• CTA project.

HESS I and HESS-II: four 12 m

telescopes and one 28 m telescope

MAGIC: a 17 m telescope VERITAS: four 12 m telescopes

Cherenkov Radiation in the Atmosphere

Cherenkov Radiation in the Atmosphere

Air Fluorescence

AIRFLY Collaboration, Astroparticle Physics, Volume 28, Issue 1, September

2007, Pages 41-57,

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

Some air fluorescence experiments:

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

• Pierre Auger Observatory, 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

3x1020 eV.

The Telescope Array The Pierre Auger Fluorescence Detector

FD: 24 (+3) fluorescence

telescopes (30° x 30° FOV):

Fluorescence track reconstruction

- monocular mode

- stereo mode

issues:

- atmospheric transmission

- fluorescence yield

- Cherenkov subtraction

• Horizontal attenuation

monitors (range ~ 60 km)

• Steerable LIDARs

• Laser Shots (Central Laser

Facility): light scattering

• Infrared Monitors (clouds)

•Cross-checks

FD: 24 (+3) fluorescence

telescopes (30° x 30° FOV):

• longitudinal development

2tan 0

0ip

ic

RTt

The Shower Detector Plane

Cherenkov subtraction

FD: 24 (+3) fluorescence

telescopes (30° x 30° FOV):

• longitudinal development

Cherenkov subtraction

Gaisser-Hillas

fit

FD: 24 (+3) fluorescence

telescopes (30° x 30° FOV):

• longitudinal development

Cherenkov subtraction

Gaisser-Hillas

fit Energy

FD: 24 (+3) fluorescence

telescopes (30° x 30° FOV):

• longitudinal development

Cherenkov subtraction

Gaisser-Hillas

fit Energy

FD: 24 (+3) fluorescence

telescopes (30° x 30° FOV):

• longitudinal development

•10% duty cycle

• almost calorimetric measurement

20 May 2007 E ~ 1019 eV

1.1/

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2

17

38

ndf

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eVsyststata

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FD

S38 (1000) vs. E(FD)

661 hybrid events

J. Abraham et al, Phys. Rev. Lett. 101, (2008)

061101.

hybrid SD only FD only

Angular

resolution

0.6° 1-2° 3-5°

Aperture independent of

E, mass, models

independent of

E, mass, models

dependent of E,

mass, models

and spectral

slope

Energy independent of

mass, models

dependent of

mass, models

independent of

mass, models

Molecular Bremsstrahlung

1. EAS particles dissipates energy through ionization

2. A weakly ionized plasma is formed at T ~ 104 K

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

molecules

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

Coherent Radio Emission

1. EAS produces e± in the shower front

(2-3 m thick)

2. These e± bend in the geomagnetic field

(~ 0.3 G), generating synchrotron

radiation (geosynchrotron)

3. Emissions for all e± add up coherently

4. The radiation can be detected by

antennas at f ~ 100 MHz (FM band)

RESULTS FROM PIERRE AUGER OBSERVATORY

CMB:

A. A. Penzias and R. Wilson, Astroph. J., 142 (1965) 419

K. Greisen, Phys. Rev. Lett., 16 (1966) 748

G. T. Zatsepin, V. A. Kuz'min, Pis'ma Zh. Eksp. Theor. Fiz. 4

(1966) 53

The GZK Cutoff

Science (Nov/2007)

(a) Photon shower (b) Proton shower (c) Iron shower

And what about the climate changes?

And what about the climate changes?

And what about the climate changes?

Muons telescope

Water Cherenkov Tank

Water Cherenkov Tank

Light pollution in Brazil:

Prof. Marcelo A. Leigui de Oliveira

CCNH – UFABC

leigui@ufabc.edu.br

Obrigado!

Universidade Federal de Santa Catarina,

Florianópolis, SC

14 de setembro de 2012

Prof. Marcelo A. Leigui de Oliveira

CCNH – UFABC

leigui@ufabc.edu.br

Backup Slides

Universidade Federal de Santa Catarina,

Florianópolis, SC

14 de setembro de 2012

Chemical composition of the atmosphere

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Mass Thickness & Depth

Atmospheric layers

1. Troposphere*: 0 – (7 – 18) km

2. Stratosphere*: 18 – 50 km

3. Mesosphere: 50 – 80 km

4. Thermosphere: 80 – 480 km

5. Exosphere: > 480 km

* most important for CRs physics

Chemical composition of the atmosphere (without water), per volume

ppmv: parts per million by volume

Gas Volume

Nitrogen (N2) 780.840 ppmv (78,084%)

Oxygen (O2) 209.460 ppmv (20,946%)

Argon (Ar) 9.340 ppmv (0,9340%)

Carbon dioxide (CO2) 390 ppmv (0,0390%)

Neon (Ne) 18,18 ppmv (0,001818%)

Helium (He) 5,24 ppmv (0,000524%)

Methane (CH4) 1,79 ppmv (0,000179%)

Krypton (Kr) 1,14 ppmv (0,000114%)

Hydrogen (H2) 0,55 ppmv (0,000055%)

Nitrous oxide (N2O) 0,3 ppmv (0,00003%)

Carbon monoxide (CO) 0,1 ppmv (0,00001%)

Xenon (Xe) 0,09 ppmv (9x10−6%)

Ozone (O3) 0,0 a 0,07 ppmv (0% a 7x10−6%)

Nitrogen dioxyde (NO2) 0,02 ppmv (2x10−6%)

Iodine (I) 0,01 ppmv (10−6%)

Ammonia (NH3) Traces

Gases not included (dry air):

Water vapor (H2O)

~0.40% throughout the atmosphere,

usually between 1%-4% in the

surface

From Wikipedia

Chemical composition of the atmosphere

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

Radiation Balance on Earth

Electromagnetic Processes

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