Upper Limit on the Diffuse Flux of Ultrahigh Energy Tau Neutrinos from the Pierre Auger Observatory

摘要

The surface detector array of the Pierre Auger Observatory is sensitive to Earth-skimming tau neutrinos that interact in Earth's crust. Tau leptons from v_τ charged-current interactions can emerge and decay in the atmosphere to produce a nearly horizontal shower with a significant electromagnetic component. The data collected between 1 January 2004 and 31 August 2007 are used to place an upper limit on the diffuse flux of v_τ at EeV energies. Assuming an E_v~(-2) differential energy spectrum the limit set at 90% C.L. is E_v~2dN_(v_τ)/dE_v < 1.3 × 10~(-7) GeVcm~(-2) s~(-1) sr~(-1) in the energy range 2 × 10~(17) eV < E_v < 2 × 10~(19) eV.