Astrophysical and Cosmological Neutrinos

Introduction The connection between neutrinos and astrophysics and cosmology is one of the traditional pillars of astroparticle physics. On the one hand side the intrinsic properties of neutrinos are dicult to measure; the \heavenly laboratories" provide invaluable complementary information [1, 2, 3]. On the other hand side neutrinos dominate the dynamics of the radiation dominated universe and of core-collapse supernovae and are important cooling agents even for ordinary stars. Knowing the intrinsic neutrino properties is crucial for our understanding of various astrophysical and cosmological phenomena. Yet the focus of neutrino astrophysics and cosmology is changing in the light of what is beginning to be the established wisdom. Pure laboratory experiments will soon overtake solar and atmospheric neutrinos at measuring the mixing parameters. While precision cosmology continues to provide the most restrictive limit on neutrino masses, the importance of astrophysics and cosmology a

Radiative cooling of fullerene anions in a storage ring

Thermionic emission from hot fullerene anions, C$_{N}^{-}$, has been measured in an electrostatic storage ring for even N values from 36 to 96. The decay is quenched by radiative cooling and hence the observations give information on the intensity of thermal radiation from fullerenes. The experiments are analysed by comparison with a simulation which includes the quantisation of photon energy and the statistics of emission. Experiments with heating of the molecules with a laser beam confirm the interpretation of the observations in terms of radiative cooling and give an independent estimate of the cooling rate for C$_{60}^{-}$. The measured cooling rates agree in general within a factor of two with the prediction from a classical dielectric model of a thermal radiation intensity of $\sim 300$ eV/s for C60 at 1 400 K, scaling approximately with the 6th power of the temperature and with the number of atoms in the molecule

Metrology of the hydrogen and deuterium atoms: Determination of the Rydberg constant and Lamb shifts

Abstract. We present a detailed description of several experiments which have been previously reported in several letters: the determination of the 1S Lamb shift in hydrogen by a comparison of the frequencies of the 1S{3S and 2S{6S or 2S{6D two-photon transitions, and the measurement of the 2S{8S/D and 2S{12D optical frequencies. Following a complete study of the lineshape of the two-photon transitions, we provide the updated values of these frequencies which have been used in the 1998 adjustment of the fundamental constants. From an analysis taking into account these results and several other precise measurements by other authors, we show that the optical frequency measurements have superseded the microwave determination of the 2S Lamb shift and we deduce optimized values for the Rydberg constant, R1 = 109 737.315 685 50(84) cm−1 (relative uncertainty of 7:7 10−12) and for the 1S and 2S Lamb shifts L(1S) = 8 172.840(22) MHz and L(2S{2P) = 1 057.8450(29) MHz (respectively, 8 183.970(22) MHz and 1 059.2341(29) MHz for deuterium). These are now the most accurate values available. PACS. 06.20.Jr Determination of fundamental constants { 21.10.Ft Charge distribution { 31.30.Jv Relativistic and quantum electrodynamic eects in atoms and molecules

Molecular flow and wall collision age distributions

The use of storage cells has become a standard technique for internal gas targets in conjunction with high energy storage rings. In case of spin-polarized hydrogen and deuterium gas targets the interaction of the injected atoms with the walls of the storage cell can lead to depolarization and recombination. Thus the number of wall collisions of the atoms in the target gas is important for modeling the processes of spin relaxation and recombination. It is shown in this article that the diffusion process of rarefied gases in long tubes or storage cells can be described with the help of the one-dimensional diffusion equation. Mathematical methods are presented that allow one to calculate collision age distributions (CAD) and their moments analytically. These methods provide a better understanding of the different aspects of diffusion than Monte Carlo calculations. Additionally it is shown that measurements of the atomic density or polarization of a gas sample taken from the center of the tube allow one to determine the possible range of the corresponding density weighted average values along the tube. The calculations are applied to the storage cell geometry of the HERMES internal polarized hydrogen and deuterium gas target