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Thomas Trefzger Universität Mainz

Cosmic rays in a thermos flask 1.European Physics Education Conference Bad Honnef. Thomas Trefzger Universität Mainz. Motivation . Mystic experiments in school

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Thomas Trefzger Universität Mainz

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  1. Cosmic rays in a thermos flask 1.European Physics Education Conference Bad Honnef Thomas Trefzger Universität Mainz

  2. Motivation • Mystic experiments in school • Introduction to special relativity • Introduction to (astro-)particle physics • Minor complexity

  3. 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

  4. The muon • Group of leptons • mass (muon) ~200 x mass of the electron • Mean lifetime 2.2 microseconds • Decay of the muon:

  5. Decay of the muon Radioactive decay law Muons should not reach the surface of the earth 1 muon per second

  6. Special Relativity • time dilation (observer at earth) v=0.9999c: muon lives longer: • Length contraction, 20km (observer moves along with the muon)

  7. Experiment set-up Praxis der Naturwissen- schaften 4/51

  8. Cherenkov radiation

  9. First Experiment Measurement without water -> no signal Measurement with water -> signals Existence of something which gives a reaction in the thermos flask

  10. Applied Statistics • Rate of muons (15 min), 10 second intervals 0 10 20 Events/10 s

  11. Applied Statistics • Rate of muons (40 hours), 10 second intervals 0 10 20 Events/10s

  12. Second experiment • Koincidence with two thermos flasks

  13. Third experiment • Measurement at different places

  14. Life after death • Fourth experiment: Lifetime

  15. Lifetime– it is relative ! Number of events vs. microseconds linear logarithmic 0 5 0 5 Microseconds Microseconds

  16. 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

  17. 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

  18. Jugend forscht 2004 – state winner

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