A) You are standing in a square room, 5 m on a side, with four radiation sources

Question

A) You are standing in a square room, 5 m on a side, with four radiation sources, one in each corner (a in northwest, B - in northeast, y in southwest, n in southeast). Each source has the same activity (particles/rays per second), is isotropic (emits in all directions equally), and has a particle/ray energy of 1 MeV. Indicate where in the room you would be safest to stand (be quantitative) and why you selected this location. B) A 5 MeV gamma ray bream is incident on a 9 cm slab of lead. Take u/p as 0.0426 cm2g 1, p as 11.34 g cm-3, and the buildup factor, B, as 2.1. Compute Vlo at the far side of the slab C) A 0.5 MeV gamma ray bream is incident on a 100 cm "slab" of water. Take /p as 0.0706 cm2g-1 , as 1.00 g cm-3 , and the buildup factor, B, as 18. Compute l/10 at the far side of the slab D) In which case, part B or part C, would more photons with an energy of 511 keV be expected to exit the far side of slab (assume the same number of photons come from source)? Provide a clear argument why this is so. (An argument is not just writing down a basic nuclear physics term explain what is happening and how photons at this energy are generated.)

Explanation / Answer

the safest place in the room would be where you will receive the lowest amount of radiation from the radioactive sources.

As energy of all particles is same, one must choose a place close to radiation whose range in air is very small.

This will inturn mean that we stand far from high range source.

Alpha have range of 3-5cm in air.

Hence standing near Alpha source will have least exposure to radioactivity.

Neutrons become slow(thermal) before decaying/being absorbed which is unlikely in air.

While Gamma have most range, one should stand at atmost distance from Gamma source.

Beta particles have range of Around 20cm in air.

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