The phrase "harvest moon" recently took on a new meaning as a University of Iowa astrophysicist and his UI colleagues used the moon in an attempt to harvest evidence of elusive cosmic particles called ultra high energy (UHE) neutrinos in the most sensitive such radio search ever attempted.

The results of the project -- conducted by professor Robert Mutel, associate professor Kenneth Gayley and National Research Council post-doctoral fellow Theodore Jaeger, all of the UI Department of Physics and Astronomy -- have just been published in the December 2010 issue of the journal Astroparticle Physics. What the researchers hoped to detect was the tell-tale signatures of neutrinos, elementary particles of neutral charge, in order to learn more about the fundamental building blocks of matter.

Although they didn't detect neutrino-generated pulses, they did succeed in setting new, lower limits on the cosmic UHE neutrino flux. These limits provide important constraints on models of neutrino generation from a variety of cosmic neutrino generation models. In particular, the lower limit eliminates some Z-burst models which had predicted UHE neutrinos originating from the halo of the Milky Way galaxy. In addition, the pulse detection scheme and a new analysis of the moon as a neutrino target developed by the UI team will guide future moon-based radio searches with the next generation of radio telescope arrays.

Ref: Jaeger, T., Mutel, R., Gayley, K. 2010, Project RESUN, a Radio EVLA Search for UHE Neutrinos, Astroparticle Physics, 34, 293.