PHYSICS · Multi-part · Fermi University Physics · Particle Physics & Quantum Fields · Symmetry, groups and the quark model · Symmetry, groups and the quark model
Symmetry and Flavour, Ch Parity, charge conjugation and time reversal as operators, and the CPT theorem
Problem
In the Goldhaber, Grodzins and Sunyar experiment, the 0− isomer 152Eum captures an atomic electron and forms the 1− level of 152Sm∗ plus an electron neutrino; the excited samarium nucleus then emits a 961keV photon to the 0+ ground state. Resonant scattering in samarium selects only those photons emitted opposite to the neutrino's direction along the common recoil axis, and their circular polarisation is measured by transmission through magnetised iron. The measured result was h(νe)=−1 (left-handed), giving left-circularly polarised photons in the selected sample.
((a)) Suppose instead that the electron neutrino had turned out to be right-handed, h(νe)=+1. Predict the circular polarisation (handedness) that would then have been measured for the resonantly scattered photons, using the same angular-momentum bookkeeping along the 0−→1−→0+ chain.
((b)) State whether the steps of the experiment (electron capture geometry, resonant scattering selection, iron polarimeter) would need to change in this hypothetical case, or only the sign of the result.