Medium-energy physics

Recent Progress in Vapor Cell Atomic Magnetometry
I will report recent progress on vapor cell atomic magnetometers and co-magnetometers. The first part of the talk describes a Rb scalar gradiometer using two multipass optical cells. We use a pump-probe measurement scheme to suppress spin-exchange relaxation and reach sub-femtotesla magnetic field sensitivity. It approaches, for the first time, the fundamental limit set by Rb-Rb collisions. The second part of the talk reports recent progress in the development of a new co-magnetometer using He-3 and Xe-129 nuclear spins.
Underground helium travels to the Earth’s surface via aquifers, new study saysDecember 5, 2014

Before it can put the party in party balloons, helium is carried from deep within the Earth’s crust to the surface via aquifers, according to new research published this week in Nature Geosciences.