Teilchenastrophysik in der Schule oder Lichtblitze in der
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Transcript Teilchenastrophysik in der Schule oder Lichtblitze in der
Cosmic rays in a thermos flask
1.European Physics Education Conference
Bad Honnef
Thomas Trefzger
Universität Mainz
Motivation
Mystic experiments in school
Introduction to special relativity
Introduction to (astro-)particle physics
Minor complexity
Cosmic radiation
Interaction of high
energetic primary
particles (85%
protons, 14% alpha
particles) with
nuclei of the
atmosphere
Surface of the
earth: a few
hundred charged
particles per qm per
second
Mostly muons
The muon
Group of leptons
mass (muon) ~200 x mass of the electron
Mean lifetime 2.2 microseconds
Decay of the muon:
e e
e e
Decay of the muon
Radioactive decay law
N t N0 exp( t ) mit 2.2s
Muons should not reach the surface of the earth
6
s v t 0.9999 c 2.2 10 s 660m
1 muon
per second
Special Relativity
time dilation (observer at earth)
v=0.9999c: muon lives longer:
1
v2
1 2
c
71
1.6 10 4 sec
Length contraction, 20km
(observer moves along with the muon)
s
1
s 282 m
Experiment set-up
Praxis der
Naturwissenschaften 4/51
Cherenkov radiation
First Experiment
Measurement without water
-> no signal
Measurement with water
-> signals
Existence of something which gives a
reaction in the thermos flask
Applied Statistics
Rate of muons (15 min),
10 second intervals
0
10
20
Events/10 s
Applied Statistics
Rate of muons (40 hours),
10 second intervals
0
10
20
Events/10s
Second experiment
Koincidence with two thermos flasks
Third experiment
Measurement at different places
Life after death
Fourth experiment: Lifetime
e e
e e
Lifetime– it is relative !
logarithmic
linear
Number of events vs. microseconds
0
Microseconds
5
0
Microseconds
5
What can we learn ?
Cosmic radiation is omnipresent and
can be detected
Frequency of occurence, penetration
rate, angular rate dependence
Statistical aspects, randomness of
events
Didactic Potential
Exotic particles in school
Statistical aspects
Aspects of special relativity
Ongoing research
Elementary particles as part of our
world
Computer in measurement control
and analysis
Jugend forscht 2004 – state winner