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
10
9
8
7
6
5
4
3
2
1
0
10
9
8
7
6
5
4
3
2
1
0
300000
200000
100000
0
10
9
8
7
6
5
4
3
2
1
0
300000
200000
100000
0
10
9
8
7
6
5
4
3
2
1
0
300000
200000
100000
0
10
9
8
7
6
5
4
3
2
1
0
300000
200000
100000
0
10
9
8
7
6
5
4
3
2
1
0
100000
10000
1000
100
10
1
0.1
0.01
1
10
100
1000
10000
100000
1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950
0
5000
10000
15000
20000
25000
12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849500 1 2 3 4 5
0 1 2 3 4 5
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
Top Related