1927-28 Jacob Clay from Genoa to the Dutch colony of Java

•ionization intensity drops ~6% •minimum at magnetic equator

1929 Bothe & Kolhörster •suggest Clay’s Lattitude Effect was due to •deflection by earth’s magnetic field•primaries are charged

• inspired by the Norwegian mathematician Carl Størmer’s calculations explaining colleague Kristian Birkland’s theory of the aurora

• Birkland experimented with electron beams and a phosphorous-painted globe of lodestone

1930-33 Arthur Compton (University of Chicago) conductsa worldwide sea- and mountain-level lattitude survey of cosmic ray intensities and confirms the Latitude Effect.

The 4 curves correspond to 4 seasons. Physical Review 52 [1937]:p.808

Størmer’s “cutoff energies”: only the fastest cosmics reach sea level near the equator less energetic particles are observable at mid-latitudes unrestricted energies in the polar regions

1933-35 Thomas Johnson (of the Carnegie Institute) and Bruno Rossi (Italy) independently mount

Geiger counter telescope arrays to test for the

east-west asymmetry predicted by Georges Lemaître (Belgian)

Positive charged particles headed toward the earthfrom space, would tend (at mid-latitudes) to reach the surface coming down from the

A. NorthB. SouthC. EastD. WestE. split East and West

Although cosmic rays do come “from all directions”,

at high altitudes near the equator the intensity is higher coming from

the West than from the East!

1939 Johnson speculates primaries may be protons!

Electroscopes become so robust, datacan be collected remotely (for example

retreived from unmanned weather balloons)

November 11, 1935

Explorer II, a 113,000 cubic foot

helium balloon ascends to a record 22,066 m while collecting atmospheric and cosmic ray data.

Definite evidence for the celestial generation of CosmicRays came from fortuitous timing of a few high altitude balloon studies during some spectacular solar flares.

Unusual increase in Cosmic ray intensity associated withan intense solar flare observed

February 28, 1942the same sunspot associated with this flare erupts again

March 7, 1942Similarly the

June 4, 1946 solar prominence

is followed by another eruptionJuly 25, 1946

and the solar flare event ofNovember 19, 1949

is also captured by airborne cosmic ray instrumentseach accompanied by a Sudden Ionospheric Disturbance

which interrupts radio communications on earth

During the June 1946 prominence, ultraviolet radiation and x-rays arrived

A. shortly before B. simultaneous to C. shortly after

the visual observation of the flare.

Why?

During the June 1946 prominence, charged particles causingradio blackouts arrived

A. hours before B. minutes before

C. simultaneous toD. minutes after

E. hours later

the visual observation of the flare.

Particles causing radio blackouts arrived about 3

hours later.

Why?

Range of human hearing:

20 Hz – 20,000 Hz

SensitivityThreshold for hearing: 110-12 Watt/m2

•Increase of pressure on eardrum0.00003 Pascals (N/m2) abovenormal atmospheric pressure: 1 atm = 101,300 Pa

•vibrating air molecules displaced by an amplitude of ~110-10 m 1/10 the diameter of an air molecule!

Threshold for pain: 1 Watt/m2

•29 Pa above atmospheric pressure•Amplitude of vibrations 110-5 m

Not perceived as 1012 times “as loud”

Moonlight ~ foot-candle110

working conditions 40-50 ft-candles

outdoors at noon 10,000 ft-candles (sunlight)

The human eye also responds logarithmically

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truly exponential graphs

become straight linesin a logarithmic plot!

What is the world’s most abundant element?

Oxygen O 46.6

Silicon Si 27.7

Aluminum Al 8.1

Iron Fe 5.0

Calcium Ca 3.6

Sodium Na 2.8

Potassium K 2.6

Magnesium Mg 2.1

Subtotal 98.5

Titanium Ti 0.4

Hydrogen H 0.1

Phosphorus P 0.1

Manganese Mn 0.1

Sulfur S 0.05

Carbon C 0.03

Total 99.3

CRUSTAL ABUNDANCE OF THE ELEMENTS (by % weight)

Average composition of clean, dry air at the Earth's surface

ConstituentSymbol

Molecular Weight

Molecular fraction

Fraction by mass

Nitrogen Oxygen Argon Carbon dioxide Neon Helium Methane Krypton Nitrous oxide

Hydrogen Ozone

N2 O2 Ar CO2

Ne He CH4 Kr N2O H2 O3

28 32 40 44

20 4 16 84 44 2 48

78.09 % 20.95 % 0.93 % 320 ppm

18 ppm 5.2 ppm 2.9 ppm 1.1 ppm 0.5 ppm 0.5 ppm 0.01 ppm

75.5% 23.2 % 1.3 % 486 ppm

12 ppm 0.7 ppm 1.6 ppm 3.2 ppm 0.8 ppm 0.03 ppm 0.02 ppm

Water, moisture

H2O 18 - -

Source: Garrels, MacKenzie and Hunt: Chemical cycles. 1975

Distribution of Elements in the Human Body (by weight)

Element Atomic no. Percentage Role

oxygen 8 65.0cellular respiration, component of water

carbon 6 18.5 basis of organic molecules

hydrogen 1 9.5component of water & most organic molecules, electron carrier

nitrogen 7 3.3component of all proteins and nucleic acids

calcium 20 1.5component of bones and teeth, triggers muscle contraction

phosphorus 15 1.0component of nucleic acids, important in energy transfer

potassium 19 0.4min positive ion inside cells, important in nerve function

sulfur 16 0.3 component of most proteins

sodium 11 0.2main positive ion outside cells, important in nerve function

chlorine 17 0.2 main negative ion outside cells

magnesium 12 0.1essential component of many energy-transferring enzymes

iron 26 traceessential component of hemoglobin in the blood

copper 29 trace component of many enzymes

molybdenum 42 trace component of many enzymes

zinc 30 trace component of some enzymes

iodine 53 trace component of thyroid hormone

Solar system massesSun 1.981030 kgJupiter 1.901027 kgEarth 5.981024 kg

Absorption “lines”

• First discovered in spectrum

of Sun (by an imaging scientist

named Fraunhofer)• Called “lines” because they

appear as dark lines super-

imposed on the rainbow of the

visible spectrum

Sun’s Fraunhofer absorption lines

(wavelengths listed in Angstroms; 1 A = 0.1 nm)

The Solar Spectrum

Emission line spectra

Insert various emission line spectra here

Emission line images

Planetary nebula NGC 6543

Green: oxygen; red: hydrogen(blue: X-rays)

Orion Nebula

The optical emission line spectrum of a young star

The Nuclear pp cycle

4 protons 4He + 6+ 2e

26.7 MeV

July 1969 Apollo 11 astronauts trap cosmic ray particles on exposed aluminum foil, returned to earth for analysis of its elemental & isotopic composition. With no atmosphere or magnetic field of its own, the moon’s surface is exposed to a constant barrage of particles.

December 1972 Apollo 17’s lunar surface cosmic ray experiment measured the flux of low energy particles in space (foil detectors brought back to Earth for analysis.

October 26, 1973 IMP-8 launched. Continues today measuring cosmic rays, Earth’s magnetic field, and the near-Earth solar wind from a near-circular, 12-day orbit (half the distance to the moon). October 1975 to the present GOES (Geostationary Orbiting Environmental Satellite) Early warning system monitoring the sun's for flares. 1977 The Voyager 1 and 2 spacecraft are launched. Each will explore acceleration processes of charged particles to cosmic ray energies.

Hydrogen (H) 1 1.00 640

Helium (He) 2 6.8 10-2 94

Lithium, beryllium, boron 2.6 10-9 1.5

Carbon, Nitrogen, Oxygen 1.2 10-3 6

Iron (Fe) 26 3.4 10-5 0.24

All heavier atoms 1.9 10-6 0.13

ElementAtomic

Number (Z)

Solar SystemComposition

(relative number of atoms)

PrimaryCosmic Ray

Flux(particles/m-2 sec)

50m

Cosmic ray strikes a nucleuswithin a layer of

photographicemulsion

Primary cosmic ray

Mostly photons, electrons and muons at Earth’s surface

A 1019 eV Extensive Air Shower

100 billion particles

at sea level

89% photons10% electrons~1% muons

12 km

6 km6 km

The Cosmic Ray Energy Spectrum

(1 particle per m2-sec)

(1 particle per m2-year)

(1 particle per km2-year)

Cosmic Ray Flux

Energy (eV)

Refrigerator cold CO2 bubble (887 mph)

0.02 eV

Room temperature nitrogen N2 (1160 mph)

0.03 eV

Atoms in sun’s MILLION DEGREE surface0.50 eV

Energy given to each single electron whenaccelerated by AA battery 1.5 eV

Electrons accelerated by your televisionpicture tube (traveling ~1/3 speed of light)

30,000 eV

Fermi National Lab’s high energy protons 1,000,000,000,000 eV

Superball bounced over your house 4 x 1017 eV

Pitched baseball 4 x 1020 eV

Slammed hockey puck 1 x 1021 eV

Recall: 1 joule = 6.2 x 1018 eV

The highest energy Cosmic Rays areSUBATOMIC particles carrying theenergy of MACROSCOPIC objects!

4 x 1021 eV = 60 joules

The Cosmic Ray Energy Spectrum

FERMILAB’s protonsFERMILAB’s protons

Bounced Superball

Bounced Superball

Pitched baseballPitched baseball

Hockey PuckHockey Puck

Energy (eV)

Two possible sources of cosmic rays

Colliding galaxies

Active galacticnucleus

GZK Cutoff

1966 - K. Greisen - G.T.Zatsepin & V.A.Kuz’min

showed the recently discovered cosmic microwave background radiation (CMBR)effectively makes the universe opaque tosufficiently high energy cosmic particles.

GZK Cutoff

For example:

p *+0 p

++ n

and similar resonances yield attenuation lengths mere 10s of Mega parsecs for cosmic ray protons with E>1019 eV.

Center of (our) Virgo supercluster is approximately 20 Mpc away

All E>1019 eV primaries must originate within 100 Mpc of the earth

1966 - K. Greisen - G.T.Zatsepin & V.A.Kuz’min

p

Energy [eV]

ICRC2001 news

AGASA: 717

HiRes: 7 2

events above 1020eV

AGASA