An Introduction to Thermal Physics · Problem 7.66

Quantum Statistics — Daniel Schroeder

Physics — Statistical Mechanics · bose-einstein-condensation

Problem

Consider a collection of 10,000 atoms of rubidium-87, confined inside a box of volume (10−5 m)3(10^{-5}\text{ m})^3. (a) Calculate ϵ0\epsilon_0, the energy of the ground state. (Express your answer in both joules and electron-volts.) (b) Calculate the condensation temperature, and compare kTckT_c to ϵ0\epsilon_0. (c) Suppose that T=0.9TcT = 0.9T_c. How many atoms are in the ground state? How close is the chemical potential to the ground-state energy? How many atoms are in each of the (threefold-degenerate) first excited states? (d) Repeat parts (b) and (c) for the case of 10610^6 atoms, confined to the same volume. Discuss the conditions under which the number of atoms in the ground state will be much greater than the number in the first excited state.

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