KamLAND Sensitivity to Neutrinos from Pre-Supernova Stars

In the late stages of nuclear burning for massive stars (M>8~M_{\sun}), the production of neutrino-antineutrino pairs through various processes becomes the dominant stellar cooling mechanism. As the star evolves, the energy of these neutrinos increases and in the days preceding the supernova a significant fraction of emitted electron anti-neutrinos exceeds the energy threshold for inverse beta decay on free hydrogen. This is the golden channel for liquid scintillator detectors because the coincidence signature allows for significant reductions in background signals. We find that the kiloton-scale liquid scintillator detector KamLAND can detect these pre-supernova neutrinos from a star with a mass of 25~M_{\sun} at a distance less than 690~pc with 3$\sigma$ significance before the supernova. This limit is dependent on the neutrino mass ordering and background levels. KamLAND takes data continuously and can provide a supernova alert to the community.Comment: 19 pages, 6 figures, 1 tabl

Search for Majorana Neutrinos Near the Inverted Mass Hierarchy Region with KamLAND-Zen

United States. Department of Energy (DE-AC02-05CH11231

Publisher's Note: Search for Majorana Neutrinos Near the Inverted Mass Hierarchy Region with KamLAND-Zen [Phys. Rev. Lett. 117, 082503 (2016)].

This corrects the article DOI: 10.1103/PhysRevLett.117.082503

A SEARCH for ELECTRON ANTINEUTRINOS ASSOCIATED with GRAVITATIONAL-WAVE EVENTS GW150914 and GW151226 USING KAMLAND

We present a search, using KamLAND, a kiloton-scale anti-neutrino detector, for low-energy anti-neutrino events that were coincident with the gravitational-wave (GW) events GW150914 and GW151226, and the candidate event LVT151012. We find no inverse beta-decay neutrino events within ±500 s of either GW signal. This non-detection is used to constrain the electron anti-neutrino fluence and the total integrated luminosity of the astrophysical sources

Search for double-beta decay of 136Xe to excited states of 136Ba with the KamLAND-Zen experiment

A search for double-beta decays of Xe to excited states of Ba has been performed with the first phase data set of the KamLAND-Zen experiment. The 0 , 2 and 2 transitions of 0νββ decay were evaluated in an exposure of 89.5 kg⋅yr of Xe, while the same transitions of 2νββ decay were evaluated in an exposure of 61.8 kg⋅yr. No excess over background was found for all decay modes. The lower half-life limits of the 2 state transitions of 0νββ and 2νββ decay were improved to T1/20ν(0 →2 )>2.6×10 yr and T (0 →2 )>4.6×10 yr (90% C.L.), respectively. We report on the first experimental lower half-life limits for the transitions to the 0 state of Xe for 0νββ and 2νββ decay. They are T (0 →0 )>2.4×1025 yr and T (0 →0 )>8.3×1023 yr (90% C.L.). The transitions to the 2 states are also evaluated for the first time to be T (0 →2 )>2.6×10 yr and T (0 →2 )>9.0×10 yr (90% C.L.). These results are compared to recent theoretical predictions. 136 136 + + + 136 + + + 25 2ν + + 23 + 136 0ν + + 2ν + + + 0ν + + 25 2ν + + 23 1 1 2 1 1 1/2 1 1 1/2 1 1/2 1 2 1/2 2 1/2