When we do that, we only trap krypton-81. While in the trap, a krypton atom scatters millions of photons per second from the laser beams, and appears as a bright dot. A photon detector records the arrival and departure of individual atoms. In the current experiment, one krypton-81 atom is detected every 15 minutes or so. Although the Argonne team has only worked with krypton atoms so far, ATTA should apply to some other isotopes for applications in a range of scientific disciplines.
Neutrinos are ghostly subatomic particles produced by thermonuclear reactions in the sun's core.
They only rarely interact with matter and most pass unhindered through the earth. Physicists using huge underground neutrino detectors are finding fewer particles than expected of the type predicted by current theories of how the sun produces energy. Ancient, deeply buried rocks are shielded from to cosmic rays that would produce spurious results. By measuring the amount of lead-205 in these ancient rocks, scientists may be able to get an accurate measure of the sun's past activity. If more neutrinos were produced in the distant past, it may signal that the sun's core is currently in a relatively dormant phase, accounting for the dearth of neutrinos.