| 1. The Astronomical Unit (A.U.) is 1.50x1011m; this is the mean radius of the Earth's orbit around the Sun. Calculate the travel-time for neutrinos to reach the Earth given that their velocity is 3x108m/s (i.e. the speed of light). |
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2. a) Using the graph to the left, determine the velocity of 20MeV solar protons. b) What is the travel-time of these protons from the Sun to the Earth?
3. a) Using the graph to the left, determine the velocity of 80MeV solar protons.
4. A typical solar proton event usually lasts several hours. Based on your calculations in questions (2) and (3), what might one conclude concerning the period of greatest danger to unprotected astronauts in Earth orbit. What factors might mitigate this conclusion? |
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5. Intense solar proton events are usually associated with large solar flares. Is it possible for the proton event to begin (i.e. would protons begin arriving at the Earth) before the solar flare is seen? Why or why not? 6. The maximum recommended absorbed dose is 5.0 mSv·a-1 (less for children and expectant moms). At Guarapari Beach, Brazil radioactive sand produces a background of 800 mSv·a-1. How many days could one stay at the beach before exceeding their maximum recommenced dose? 7. The maximum recommended absorbed dose is 5.0 mSv·a-1 (less for children and expectant moms). At Kerala Beach, India radioactive sand produces a background of 35 mSv·a-1. How many weeks could one stay at the beach before exceeding their maximum recommenced dose? 8. The maximum recommended absorbed dose is 5.0 mSv·a-1 (less for children and expectant moms). The permanently evacuated City of Pripyat, (near Chernobyl) Ukraine, has been contaminated with a fallout which produces a background of 5.0 mSv·a-1. How many weeks could one live there before exceeding the maximum recommenced dose? |
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