Transcript Slide 1
Magnetic
field points
into screen
From these observations alone,
what definite conclusions can be made?
a s are positively charged, bs negative.
Positive charged particles headed toward the earth
from space, would tend (at mid-latitudes) to reach
the surface coming down from the
A. North
B. South
C. East
D. West
E. split East and West
The Fantastic Four ®
©1996 Marvel Comics
1900 Charles T. R. Wilson’s ionization chamber
Electroscopes eventually discharge even
when all known causes are removed,
i.e., even when electroscopes are
•sealed airtight
•flushed with dry,
dust-free
filtered air
•far removed from
any samples of
radioactivity
•shielded with
2 inch thick
blocks of lead!
seemed to indicate an unknown radiation with
greater penetrability than x-rays or
radioactive a, b, or rays
Speculating they might be extraterrestrial, Wilson ran
underground tests at night in the Scottish railway, but
observed no change in the discharging rate.
1909 Jesuit priest, Father Thomas Wulf , improved
the ionization chamber with a design planned
specifically for high altitude balloon flights.
A taut wire pair replaced the gold leaf.
This basic design has became the
pocket dosimeter radiation lab
workers carry to record their
total exposure to ionizing radiation.
0
1911-12
Austrian physicist Victor Hess, of the Vienna University,
and 2 assistants, carried Wulf ionization chambers up in
a series of hydrogen balloon flights.
• taking ~hour long readings at several altitudes
• both ascending and descending
• radiation more intense above 150 meters than at sea level
• intensity doubled between 1000 m to 4000 m
• increased continuously through 5000 meters
Dubbed this “high” level
radiation
Höhenstrahlung
Hess lands following a
historic 5,300 meter flight.
August 7, 1912
National Geographic photograph
In 1936, Hess was awarded the Nobel prize for this discovery.
Electroscopes became so robust, data
could be collected remotely (for example
retrieved from unmanned weather balloons)
1924 Walter Bothe and Geiger use multiple
Geiger counters to establish the tracks
followed by electron beams
1928-29 Bothe and Werner Kolhörster
build Geiger telescopes and
announce that cosmic “rays”
contain charged particles
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) conducts
a 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
1933-35 Thomas Johnson (of the Carnegie Institute)
Bruno Rossi (Italy) independently mount
Geiger counter telescope arrays to test for an
east-west asymmetry
predicted by Georges Lemaître (Belgian)
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!
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!
Cosmic ray
strikes a nucleus
within a layer of
photographic
emulsion
50mm
Definite evidence for the celestial generation of Cosmic
Rays came from fortuitous timing of a few high altitude
balloon studies during some spectacular solar flares.
Unusual increase in cosmic ray intensity associated with
an intense solar flare observed
February 28, 1942
the same sunspot associated with this flare erupts again
March 7, 1942
Similarly the
June 4, 1946 solar prominence
is followed by another eruption
July 25, 1946
and the solar flare event of
November 19, 1949
is also captured by airborne cosmic ray instruments
each accompanied by a Sudden Ionospheric Disturbance
which interrupts radio communications on earth
What is the world’s most
abundant element?
CRUSTAL ABUNDANCE OF THE ELEMENTS (by % weight)
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
Oxygen
Average composition of clean, dry air at the Earth's surface
Symb
ol
Molecul
ar
Weight
Molecul
ar
fraction
Fraction
by mass
Nitrogen
Oxygen
Argon
Carbon
dioxide
Neon
Helium
Methane
Krypton
Nitrous oxide
Hydrogen
Ozone
N2
O2
Ar
CO2
28
32
40
44
78.09 %
20.95 %
0.93 %
320 ppm
75.5%
23.2 %
1.3 %
486 ppm
Ne
He
CH4
Kr
N2O
H2
O3
20
4
16
84
44
2
48
18 ppm
5.2 ppm
2.9 ppm
1.1 ppm
0.5 ppm
0.5 ppm
0.01 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
-
Constituent
-
Source: Garrels, MacKenzie and Hunt: Chemical cycles. 1975
Distribution of Elements in the
Human Body (by weight)
Element
Atomic no.
Percentage
Role
oxygen
8
65.0
cellular respiration,
component of water
carbon
6
18.5
basis of organic molecules
hydrogen
1
9.5
component of water & most o
rganic molecules, electron carrier
nitrogen
7
3.3
component of all proteins
and nucleic acids
calcium
20
1.5
component of bones and teeth,
triggers muscle contraction
phosphorus
15
1.0
component of nucleic acids,
important in energy transfer
potassium
19
0.4
min positive ion inside cells,
important in nerve function
sulfur
16
0.3
component of most proteins
sodium
11
0.2
main positive ion outside cells,
important in nerve function
chlorine
17
0.2
main negative ion outside cells
magnesium
12
0.1
essential component of many
energy-transferring enzymes
iron
26
trace
essential 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 masses
Sun
1.981030 kg
Jupiter 1.901027 kg
Earth
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 superimposed 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
Green: oxygen;
red: hydrogen
(blue: X-rays)
Planetary nebula NGC 6543
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.
March 3, 1972
Pioneer 10 launched -on its flyby mission, studies
Jupiter's magnetic field and radiation belts.
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)
An early warning system which monitors the Sun's surface
for flares.
1977 The Voyager 1 and 2 spacecraft are launched. Each
will explore acceleration processes of charged particles
to cosmic ray energies.
August 31, 1991
Yohkoh spacecraft launched - Japan/USA/England solar
probe - studied high-energy radiation from solar flares.
July 1992
SAMPEX (Solar Anomalous and
Magnetospheric Particle Explorer)
in polar orbit. By sampling interplanetary & magnetospheric particles,
contributes to our understanding of
nucleosynthesis and the acceleration
of charged particles.
July 1992
IMAX (Isotope Matter-Antimatter eXperiment) balloonborne superconducting magnetic spectrometer measured
the galactic cosmic ray abundances of protons, anti-protons,
hydrogen, and helium isotopes.
August 25, 1997
Advanced Composition Explorer (ACE)
was launched!
Element
Atomic
Number (Z)
Primary
Solar System
Cosmic Ray
Composition
Flux
(relative number
of atoms) (particles/m-2 sec)
Hydrogen (H)
1
1.00
640
Helium (He)
2
6.8 10-2
94
2.6 10-9
1.5
Lithium, beryllium, boron
Carbon, Nitrogen, Oxygen 1.2 10-3
Iron
(Fe)
All heavier atoms
26
6
3.4 10-5
0.24
1.9 10-6
0.13
Cosmic ray
strikes a nucleus
within a layer of
photographic
emulsion
50mm
A 1019 eV Extensive Air Shower
100 billion
particles
at sea level
12 km
6 km
6 km
89% photons
10% electrons
~1% muons
The Cosmic Ray Energy Spectrum
Cosmic Ray Flux
(1 particle per m2-sec)
(1 particle per
m2-year)
(1 particle per
km2-year)
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 surface
0.50 eV
Energy given to each single electron when
accelerated by AA battery
1.5 eV
Electrons accelerated by your television
picture tube (traveling ~1/3 speed of light)
30,000 eV
Fermi National Lab’s high energy protons
1,000,000,000,000 eV
Recall: 1 joule = 6.2 x 1018 eV
Superball bounced over your house
4 x 1017 eV
Pitched baseball
4 x 1020 eV
Slammed hockey puck
1 x 1021 eV
The highest energy Cosmic Rays are
SUBATOMIC particles carrying the
energy of MACROSCOPIC objects!
4 x 1021 eV = 60 joules
The Cosmic Ray Energy Spectrum
FERMILAB’s protons
Bounced
Superball
Pitched baseball
Hockey Puck
Energy (eV)
Two possible sources of cosmic rays
Colliding
galaxies
Active
galactic
nucleus
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 to
sufficiently high energy cosmic particles.
GZK Cutoff
1966 - K. Greisen
- G.T.Zatsepin & V.A.Kuz’min
p
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
AGASA
Energy [eV]
ICRC2001 news
AGASA: 717
HiRes:
7 2
events above 1020eV