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[PAST EVENT] Physics AMO Seminar
March 20, 2013
3pm - 4pm
Abstract:
Electroweak unification offers a beautiful model for the weak interaction in terms of exchange of heavy partners of the photon, but precise enough low-energy experiments can still test its features and search for additional physics. At TRIUMF, we use laser trapping and cooling techniques to study beta-decaying isotopes. The pressure of laser light traps the radioactive atoms in a 1 mm-sized cloud. The nucleus produced in the decay has very low kinetic energy, and would stop in ten atomic layers of material. But it freely escapes the trap, and we can measure its momentum. When we do this in coincidence with the emitted electron, we can deduce the (otherwise invisible) neutrino momentum. Recently we completed an experimental upgrade, and measured electron and recoil decay asymmetries with respect to the nuclear spin of 37K, a decay similar in many ways to that of the neutron. The asymmetries are sensitive to the chirality of the emitted electron and neutrino, and our eventual goal is to provide a rigorous test of the Standard Model assumption that the emitted neutrino is always left-handed.
Electroweak unification offers a beautiful model for the weak interaction in terms of exchange of heavy partners of the photon, but precise enough low-energy experiments can still test its features and search for additional physics. At TRIUMF, we use laser trapping and cooling techniques to study beta-decaying isotopes. The pressure of laser light traps the radioactive atoms in a 1 mm-sized cloud. The nucleus produced in the decay has very low kinetic energy, and would stop in ten atomic layers of material. But it freely escapes the trap, and we can measure its momentum. When we do this in coincidence with the emitted electron, we can deduce the (otherwise invisible) neutrino momentum. Recently we completed an experimental upgrade, and measured electron and recoil decay asymmetries with respect to the nuclear spin of 37K, a decay similar in many ways to that of the neutron. The asymmetries are sensitive to the chirality of the emitted electron and neutrino, and our eventual goal is to provide a rigorous test of the Standard Model assumption that the emitted neutrino is always left-handed.