A single neutron inside a nucleus is modelled in two crude ways

PHYSICS · Multi-part · Fermi University Physics · Quantum Mechanics · Symmetry, angular momentum and spin · Central potentials and canonical three-dimensional systems

Quantum Mechanics: From the Photon to the Hydrogen Atom, Ch The Schrödinger equation in three dimensions and central potentials

Problem

A single neutron inside a nucleus is modelled in two crude ways. Model A is a cubic box of side 6.06.0 fm with impenetrable walls (V=0V = 0 inside, infinite outside). Model B is an isotropic three-dimensional harmonic oscillator, V=12mnω2(x2+y2+z2)V = \tfrac12 m_n\omega^2(x^2+y^2+z^2), with ℏω=10\hbar\omega = 10 MeV. Ignore spin and all interactions with the other nucleons. ((a)) For model A, find the energy of the level with nx2+ny2+nz2=11n_x^2+n_y^2+n_z^2 = 11, in MeV, and the number of states it contains. ((b)) For model B, find the energy of the N=3N = 3 shell, in MeV, and the number of states it contains. ((c)) One state of that N=3N = 3 shell has the angular factor Y33(θ,ϕ)Y_3^{3}(\theta,\phi). Give the eigenvalues of L^2\hat L^2 and L^z\hat L_z for it, as multiples of ℏ2\hbar^2 and of ℏ\hbar respectively. Take ℏ2/2mn=20.7\hbar^2/2m_n = 20.7 MeV fm2^2.

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