As illustrated below, a person is located 100 cm from a ²¹⁰Po-B (Polonium-Boron) point source (E_n = 2.5 MeV) that is shielded by 10 cm of water. The source has an emission rate of 2x10⁷ n/sec. What is the first collision dose rate (in mrad/hr) to the person from fast neutrons, assuming that all neutrons interacting in the water shield are removed from the neutron flux at 100 cm? Hints: ignore attenuation in the air; only consider neutron interactions with hydrogen atoms in the body; use the following cross-section/coefficient in your calculations.

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