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 macro nu(e) cm(-2) s(-1). Additionally, an upper bound of 1.2 macro nu(e) cm(-2) s(-1) was set for the supernova relic neutrino flux in the energy region E(nu)>19.3 MeV.

Reference [15] should read as follows:[15] S. M. Bilenky and B.

We present high-resolution Compton scattering spectra from Li single crystals together with corresponding highly accurate local-density-approximation (LDA) based computations.The data are analyzed to obtain Fermi surface radii along the three principal symmetry directions; the maximum measured anisotropy is found to be (4.6~1.0)%. Comparisons between the measured and computed spectra clearly reveal departures from the conventional one-particle LDA picture of the ground state momentum density of the electron gas. This study establishes the potential of Compton scattering as a tool for investigating Fermiology-related issues in materials. PACS numbers: 61.80.Ed, 41.60.Ap, 71.25.Hc, 71.45.Gm It is well known that in a Compton scattering experiment one measures the momentum distribution [1](2) J(p~) = n(p) dp~dpy,where n(p) is the ground state electron momentum density, 2 n(p) = g W;(r) exp(ip . r) dr in terms of the electron wave functions 'Ir;(r). The summation in (2) extends over all occupied states. Therefore, the Compton profile J(p, ) contains fingerprints of Fermi surface (FS) breaks in the underlying 3D momentum distribution n(p). The size of the FS discontinuity in the momentum density and its possible renormalization due to electron-electron correlations is a fundamental property of the ground state electronic structure, inaccessible to other k-resolved spectroscopies such as angle-resolved photoemission, the de Haasevan Alphen effect (dHvA), and positron annihilation [2]. This unique capability of the Compton technique for exploring Fermiology-related issues has, however, been difficult to exploit to date because the momentum resolution available using y-ray sources is not adequate for this purpose. The advent of high intensity, high energy, well polarized synchrotron sources removes this limitation and offers new opportunities for developing Compton scattering as a tool for investigating spectral properties of the electron gas at and near the Fermi energy in wide classes of materials [3].With this motivation, we present in this Letter a highresolution synchrotron-based Compton study of Li single crystals [4], and identify, for the first time, Fermi surface signatures in the data. The presence of a 2D integral in Eq. (1) implies that the structure associated with FS cross-ings will generally be more apparent in the derivatives of J(p, ), rather than J(p, ) itself. Accordingly, parallel highly accurate computations of the Compton profiles (CP's) within the band theory framework are reported; we are not aware of a previous calculation of CP's in the literature where the line shape in the derivative spectra has been properly computed. Comparisons between the measured and computed Compton spectra clearly reveal departures from the simple one-particle local-densityapproximation (LDA) based picture of the momentum density.It is noteworthy that the Compton experiment essentially measures a ground state property of the electron gas [5] in contrast with techniques such as dHvA and angle-resolved photoemission. Als...

Antihydrogen, a positron bound to an antiproton, is the simplest antiatom. Its counterpart—hydrogen—is one of the most precisely investigated and best understood systems in physics research. High-resolution comparisons of both systems provide sensitive tests of CPT symmetry, which is the most fundamental symmetry in the Standard Model of elementary particle physics. Any measured difference would point to CPT violation and thus to new physics. Here we report the development of an antihydrogen source using a cusp trap for in-flight spectroscopy. A total of 80 antihydrogen atoms are unambiguously detected 2.7 m downstream of the production region, where perturbing residual magnetic fields are small. This is a major step towards precision spectroscopy of the ground-state hyperfine splitting of antihydrogen using Rabi-like beam spectroscopy.

We report here the first successful synthesis of cold antihydrogen atoms employing a cusp trap, which consists of a superconducting anti-Helmholtz coil and a stack of multiple ring electrodes. This success opens a new path to make a stringent test of the CPT symmetry via high precision microwave spectroscopy of ground-state hyperfine transitions of antihydrogen atoms.