Packet 1: Tossup 13

Interactions are turned on adiabatically in a model of this material that “renormalizes” effective mass and describes how the Fermi surface is distorted. Feynman’s 1955 paper on the “Application (-5[1])of Quantum Mechanics to” this material used Onsager’s model of a 2D system of point vortices. Lee, (15[1])Osheroff, (15[1])and Richardson (15[1])found that a fermionic (15[1])type of this material (-5[1])has distinct A and B phases when isentropically (-5[1])compressing it in a device named for Isaak (*) Pomeranchuk. (-5[2])Maxons (10[1])and rotons (10[2])are quasiparticle (10[3]-5[1])excitations (10[2])in this substance introduced by (10[1])Landau, (-5[1])whose two-fluid (-5[1])model describes a type of this material (10[1]-5[1])that exhibits second sound below the lambda point (10[1])and (-5[1])becomes a superfluid. (10[1]-5[2])For 10 points, name this extremely cold material (10[1])made of (-5[1])the “3” or “4” isotopes of a (10[1])noble gas. (10[1])■END■ (10[7]0[4])

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