Physics

Problem

Given the masses of various atomic particles

m_p = 1.0072 \text{ u}

m_n = 1.0087 \text{ u}

m_e = 0.000548 \text{ u}

m_{\bar{\nu}} = 0

m_d = 2.0141 \text{ u}

, where

p \equiv

proton,

n \equiv

neutron,

e \equiv

electron,

\bar{\nu} \equiv

antineutrino and

d \equiv

deuteron. Which of the following process is allowed by momentum and energy conservation? a.

n + n \to \text{deuterium atom (electron bound to the nucleus)}

p \to n + e^+ + \bar{\nu}

n + p \to d + \gamma

e^+ + e^- \to \gamma