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.United States. Department of Energy (Grant DE-FG03-00ER41138)United States. Department of Energy (Grant DE-AC02- 05CH11231)United States. Department of Energy (Grant DE-FG02-01ER41166

Capture and decay of electroweak WIMPonium

The spectrum of Weakly-Interacting-Massive-Particle (WIMP) dark matter generically possesses bound states when the WIMP mass becomes sufficiently large relative to the mass of the electroweak gauge bosons. The presence of these bound states enhances the annihilation rate via resonances in the Sommerfeld enhancement, but they can also be produced directly with the emission of a low-energy photon. In this work we compute the rate for SU(2) triplet dark matter (the wino) to bind into WIMPonium - which is possible via single-photon emission for wino masses above 5 TeV for relative velocity v < O(10-2) - and study the subsequent decays of these bound states. We present results with applications beyond the wino case, e.g. for dark matter inhabiting a nonabelian dark sector; these include analytic capture and transition rates for general dark sectors in the limit of vanishing force carrier mass, efficient numerical routines for calculating positive and negative-energy eigenstates of a Hamiltonian containing interactions with both massive and massless force carriers, and a study of the scaling of bound state formation in the short-range Hulth&apos;{e}n potential. In the specific case of the wino, we find that the rate for bound state formation is suppressed relative to direct annihilation, and so provides only a small correction to the overall annihilation rate. The soft photons radiated by the capture process and by bound state transitions could permit measurement of the dark matter's quantum numbers; for wino-like dark matter, such photons are rare, but might be observable by a future ground-based gamma-ray telescope combining large effective area and a low energy threshold

Detection of core-collapse supernovae through joint analysis of LIGO gravitational wave and KamLAND neutrino data

Thesis: S.B., Massachusetts Institute of Technology, Department of Physics, 2016.Cataloged from PDF version of thesis.Includes bibliographical references (pages 45-47).Introduction: Core collapse supernova are one of the most intriguing astrophysical phenomena. The dying stage of a supergiant star, they occur when the star collapses into a protoneutron star, causing a shock wave and a gamma ray burst. High energy neutrinos are released in this process and offer the possibility of detecting these elusive cataclysms. The number of neutrinos emitted is large but at best only a few will be detected. With a multi-messenger search, we can combine the neutrino signal with another clue to the presence of a supernova: gravitational waves. During the proto-neutron star stage, a fast-rotating star can produce gravitational waves via its asymmetric and rapidly shifting mass. By combining the signals from neutrinos and gravitational waves, we can attempt to detect supernova signals that are too faint to detect alone. Joint searches have already been attempted by several neutrino experiments with high-energy thresholds, including ANTARES and IceCube. This thesis explores the possibility of a joint search with a new set of neutrino data. KamLAND (Kamioka Liquid scintillator Anti-Neutrino Detector) is a large particle detector located in Kamioka, Japan. KamLAND is well-shielded, with an low (~ 1 MeV) energy threshold and has more than ten years of data to explore, making it a good candidate for a joint search. A recent search of KamLAND's data for clustered events indicative of supernova found no clear clusters. A new search is needed to identify single-neutrino events that may have originated in supernovae. A joint search will help KamLAND more carefully examine the possible sources of its single-neutrino events. The gravitational wave data comes from LIGO (Laser Interferometer Gravitational wave Observatory). Located in Hanford, WA and Livingston, LA, LIGO consists of two four-kilometer interferometer arms. Analysis of LIGO data from 2005 to 2010 did not produce any clear gravitational wave events, leading to a need for a more sensitive search. A multimessenger search in conjunction with KamLAND provides this opportunity. We can examine both KamLAND and LIGO's data in order to search for possible supernova signals observed by both experiments. Because a joint data-sharing agreement has not been reached between KamLAND and LIGO, this thesis looks at the potential of a joint analysis and the opportunity for such a study to produce promising results.by Emmett E.E. Krupczak.S.B