High Sensitivity Search forν¯e's from the Sun and Other Sources at KamLAND

K. Eguchi, S. Enomoto, K. Furuno, H. Ikeda, K. Ikeda, K. Inoue, K. Ishihara, T. Iwamoto, T. Kawashima, Y. Kishimoto, M. Koga, Y. Koseki (+78 others)
2004 Physical Review Letters  
Data corresponding to a KamLAND detector exposure of 0.28 kton-year has been used to search for $\bar{\nu}_e$'s in the energy range 8.3 MeV $<$ E$_{\bar{\nu}_e}$ $<$ 14.8 MeV. No candidates were found for an expected background of $1.1{\pm}0.4$ events. This result can be used to obtain a limit on $\bar{\nu}_{e}$ fluxes of any origin. Assuming that all $\bar{\nu}_e$ flux has its origin in the Sun and has the characteristic $^8$B solar $\nu_e$ energy spectrum, we obtain an upper limit of 3.7
more » ... r limit of 3.7 \times 10$^2$ cm$^{-2}$ s$^{-1}$ (90% C.L.) on the $\bar{\nu}_e$ flux. We interpret this limit, corresponding to $2.8{\times}10^{-4}$ of the Standard Solar Model $^8$B $\nu_e$ flux, in the framework of spin--flavor precession and neutrino decay models.
doi:10.1103/physrevlett.92.071301 pmid:14995837 fatcat:3b5lodv64fbd7pu4xekzpeb7ky