Bulletin of the American Physical Society
2007 APS April Meeting
Volume 52, Number 3
Saturday–Tuesday, April 14–17, 2007; Jacksonville, Florida
Session H2: Neutrinos I |
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Sponsoring Units: DPF DNP Chair: Hamish Robertson, University of Washington Room: Hyatt Regency Jacksonville Riverfront Grand 1 |
Sunday, April 15, 2007 8:30AM - 9:06AM |
H2.00001: The Beginning of the End of an Era: Analysis after the shutdown of the Sudbury Neutrino Observatory Invited Speaker: The Sudbury Neutrino Observatory (SNO) took its final data on November 28, 2006 completing the third, and final, phase of the experiment. SNO measured the total solar $^8$B neutrino flux from the neutral-current interaction of solar neutrinos with 1000 tonnes of D$_2$O. The neutral-current disintegration of deuterium was detected in three different ways. The first phase examined the neutron capture signal on the D$_2$O, the second examined the neutron capture signal on NaCl that was added to the detector, and the third examined the neutron capture signal on an array of $^3$He proportional counters deployed in the detector. This third method provides a measurement that is independent of the previous methods that utilized the detection of Cherenkov light with the PMT array. Results from the first two phases will be highlighted. The operation and stability of the array of $^3$He proportional counters will be discussed. In addition, the status of the analysis of this final phase will be presented. The current plan for future analyses will also be discussed. [Preview Abstract] |
Sunday, April 15, 2007 9:06AM - 9:42AM |
H2.00002: Results from Super Kamiokande Invited Speaker: I will present results from the Super-Kamiokande(SK) experiment from both the atmospheric and low energy neutrino analyses. These analyses are based on the entire SK-I and SK-II data sets, which were taken 1996-2001 and 2003-2005, respectively. For atmospheric neutrinos we have tested exotic modes and find that the SK zenith angle and L/E analyses strongly constrain sterile neutrino models as well as decoherence scenarios. The solar neutrino oscillation analyses have been updated with the SK-II data and the results are consistent with previous results by SK and SNO. Although minimal SUSY-SU(5) models have already been ruled out by $p\rightarrow e^{+}\pi^{0}$ and $p\rightarrow K^{+}\bar{\nu}$ modes, it is important to test GUTs with $\Delta$(B-L) violating processes, since violation of (B-L) makes neutrino-less double beta decay possible. I will report on the preliminary limit by SK of one such mode, $n-\bar{n}$ oscillations. A core-collapse supernova releases most of its gravitational energy in the form of neutrinos. These neutrinos thus carry information about the history of star formation in the early universe. We have set a limit on the relic neutrino flux using SK-II and found that it is consistent with that of SK-I. In addition, there is no evidence for a supernova burst in the SK-I and SK-II data period so we have derived a burst rate limit for our galaxy. Finally, I will discuss the status of SK-III, the recent upgrade from the half PMT coverage of SK-II, to full coverage. Data taking has been running smoothly since its start last June, and I will discuss preparations for the 2009 start of the T2K beam. [Preview Abstract] |
Sunday, April 15, 2007 9:42AM - 10:18AM |
H2.00003: The KamLAND Experiment: Measuring Terrestrial and Solar Neutrinos Invited Speaker: Since the 1950's, physicists have used nuclear reactors to study the properties of antineutrinos. In 1956, one of the first such experiments, Project Poltergeist, proved the existence of antineutrinos. The initial experiments were only a few meters away from the reactor core, the source of electron antineutrinos. Over the years the experiments steadily increased their baselines, with the goal to test and ultimately establish neutrino disappearance. That goal was reached in 2002, when the KamLAND Collaboration, using a one kton liquid scintillator detector, reported the first observation of electron antineutrino disappearance from 53 Japanese reactors at an effective baseline of $\sim$180 km. KamLAND has since observed distortions in the antineutrino energy spectrum, a telltale sign of neutrino oscillation. The experiment has also measured a key neutrino oscillation parameter, the solar mass-splitting, to unprecedented levels. Reactors, however, are not the only source of antineutrinos on Earth. Radioactive decays in the Earth also produce antineutrinos and the heat released in that process may be the driving force for mantle convection, which is responsible for terrestrial phenomena such as plate tectonics. KamLAND is sensitive to geologically produced electron antineutrinos from the $^{238}$U and $^{232}$Th decay chains. Earth composition models predict that these are responsible for the majority of the radiogenic heat; detection of geoneutrinos from these two decays allows the models to be directly tested for the first time. I will discuss how KamLAND's measurements have further solidified the case for neutrino oscillation and the exciting recent investigation of geoneutrinos. I will conclude with an outlook on the next, low-background phase of the experiment that aims to measure the flux of solar $^{7}$Be neutrinos. [Preview Abstract] |
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