HE.5.1.09 Searches for the Cowan Effect–A Peak at 21 hr LST for -e Decay Events.pdf

HE.5.1.09 Searches for the Cowan Effect–A Peak at 21 hr LST for -e Decay Events A.G. Young , P. McGuire , T. Bowen


Department of Physics, University of Arizona, Tucson, AZ 85721, USA  Centerfor Astronomical Adaptive Optics, Steward Observatory, University of Arizona, Tucson, AZ 85721, USA Abstract In several 1960’s experiments Clyde L. Cowan’s group observed  -e-decay events with a sharp, statistically- significant intensity peak near 21 hr LST (denoted the Cowan Effect). The zenith happened to be near 39 deg N and 21 hr RA, close to the direction ( 47 deg N,  21 hr RA) of our galactic spiral arm and of the Sun’s motion in the galaxy. The  -e-decay detectors were omnidirectional, but the response would be strongly peaked at the zenith if the atmosphere highly attenuated the primary particles. If galactic dark matter (DM) includes a nonrotating, strongly-interacting component (SIMPs), it would arrive at Earth as a highly directional ”wind,” peaking at 21 hr LST- -a huge Compton-Getting Effect for DM       . Peaks near 21 hr LST (presently  2 to 3  ) in low and high altitude Arizona experiments and in cosmic ray data from the LSND experiment (plus more new data) will be presented. 1 Introduction: We present the results of a cosmic ray search for dark matter at mountain altitude. For 3 years, we have been studying a sidereal time dependence of the cosmic ray stopping muon rate. Recently, we completed data taking runs with an 820 kg liquid scintillation detector at 2700 m near Tucson, Arizona. Stopping muons were counted in the detector by searching for a muon- electron signal pair with 127mm PMTs, the decay electron following from .6 to 6