A search for the relic neutrinos from all past core-collapse supernovae was conducted using 1496 days of data from the Super-Kamiokande detector. This analysis looked for electron-type antineutrinos that had produced a positron with an energy greater than 18 MeV. In the absence of a signal, 90% C.L. upper limits on the total flux were set for several theoretical models; these limits ranged from 20 to $130{\overline{\nu }}_e{\mathrm{c}\mathrm{m}}^{-2}{\mathrm{s}}^{-1}$. Additionally, an upper bound of $1.2{\overline{\nu }}_e{\mathrm{c}\mathrm{m}}^{-2}{\mathrm{s}}^{-1}$ was set for the supernova relic neutrino flux in the energy region $E_{\nu }>19.3\mathrm{M}\mathrm{e}\mathrm{V}$.

• Received 15 September 2002

DOI:https://doi.org/10.1103/PhysRevLett.90.061101