22445170
Polarized, high-density, gaseous 3He targets.
121991652
Measurement of the relativistic Doppler effect using 8.6-MeV capture $gamma$ rays
122285344
A Heavy Water Detector to Resolve the Solar Neutrino Problem
Abstract The observation of the following three reactions: ν e d→ppe; ν x e→ ν x e ; and ν x d→ ν x pn (where ν x is any left- handed neutrino) in a heavy water Cerenkov detector which is being designed, allows the solar 8 B v e flux, spectrum and direction to be measured. In addition, the total solar 8 Bν c neutrino flux, direction and integral spectrum, independent of neutrino flavor, may be determined to provide several independent methods to resolve the solar neutrino problem.
119657975
Solar neutrinos, SNO and SNOLAB
The Sudbury Neutrino Observatory is a 1000 tonne heavy water Cherenkov detector situated 2 km underground in INCO's Creighton mine near Sudbury, Ontario, Canada. In the first two phases of the project reported to date, the charged current reaction on deuterium has been used to measure the flux and energy spectrum of solar electron neutrinos and the neutral current reaction has been used to measure the total flux of active neutrinos. Clear evidence of neutrino flavour change has been observed and the total active flux is found to be in agreement with solar model calculations. The experimental third phase with an array of neutron detectors is in progress. The expansion of the underground laboratory to create an international facility known as SNOLAB will be completed in 2007. A number of international experiments for the future detection of lower energy solar neutrinos, geo-neutrinos, dark matter and double beta decay are described.
117853216
Core-Excited High-Spin Isomers in 212Rn
We have observed isomeric states in /sup 212/Rn with very high angular momenta (up to J/sup ..pi../ = 30/sup +/). The four isomers of highest spin contain core-excited neutron configurations, the spins of which are strongly aligned with those of the valence protons. The isomerism appears to result from a lowering of the excitation energies by 1 to 2 MeV compared to a sum of the unperturbed values for the constituent configurations.
122471417
Radiative decay of the second excited state of C-12
The branching ratio GAMMA/sub rad//GAMMA for the electromagnetic decay of the 7.655 MeV second excited state of $sup 12$C has been measured by detecting the $sup 12$C (0.0 MeV) recoils in coincidence with $alpha$ particles from the $sup 13$C($sup 3$He,$alpha$$sub 2$)$sup 12$C (7.65 MeV) reaction at E3)=4.00 MeV. Coincidence events were identified by means of time-of-flight, energy, and kinematic constraints. Thus, of all the $sup 12$C nuclei formed in the second excited state, only those decaying to the $sup 12$C ground state by either $gamma$-ray or positron-electron pair emission were selected. Hence the experiment provides a direct measurement of GAMMA/sub rad//GAMMA, where GAMMA/sub rad/=GAMMA/sub $gamma$ + e+-/, and gives GAMMA/sub rad//GAMMA= (4.15 +- 0.34) x 10$sup -4$, which is in good agreement with other recent measurements, and suggests that the previously accepted value of GAMMA/sub rad//GAMMA= (2.9 +- 0.3) times 10$sup -4$ may be too low. The significance of this result is discussed with respect to helium burning rates in stars.
9782765
Gauge singlet scalars as cold dark matter.
We consider a very simple extension of the standard model in which one or more gauge singlet scalars S-i couples to the standard model via an interaction of the form lambda(S)S(i)(dagger)S(i)H(dagger)H, where H is the standard model Higgs doublet. The thermal relic density of S scalars is calculated as a function of the coupling lambda(S) and the S scalar mass ms. The regions of the (m(S),lambda(S)) parameter space which can be probed by present and future experiments designed to detect scattering of S dark matter particles from Ge nuclei, and to observe upward-moving muons and contained events in neutrino detectors due to high-energy neutrinos from annihilations of S dark matter particles in the Sun and the Earth, are discussed. Present experimental bounds place only very weak constraints on the possibility of thermal relic S scalar dark matter. The next generation of cryogenic Ge detectors and of large area (10(4) m(2)) neutrino detectors will be able to investigate most of the parameter space corresponding to thermal relic S scalar dark matter up to m(S) approximate to 50 GeV, while a 1 km(2) detector would in general be able to detect thermal relic S scalar dark matter up to m(S) approximate to 100 GeV and would be able to detect up to m(S) approximate to 500 GeV or more if the Higgs boson is lighter than 100 GeV.
42466564
CP violation for electroweak baryogenesis from mixing of standard model and heavy vector quarks.
It is known that the CP violation in the minimal standard model is insufficient to explain the observed baryon asymmetry of the Universe in the context of electroweak baryogenesis. In this paper we consider the possibility that the additional CP violation required could originate in the mixing of the standard model quarks and heavy vector quark pairs. We consider the baryon asymmetry in the context of the spontaneous baryogenesis scenario. It is shown that, in general, the CP-violating phase entering the mass matrix of the standard model and heavy vector quarks must be space dependent in order to produce a baryon asymmetry, suggesting that the additional CP violation must be spontaneous in nature. This is true for the case of the simplest models which mix the standard model and heavy vector quarks. We derive a charge potential term for the model by diagonalizing the quark mass matrix in the presence of the electroweak bubble wall, which turns out to be quite different from the fermionic hypercharge potentials usually considered in spontaneous baryogenesis models, and obtain the rate of baryon number generation within the wall. We find, for the particular example where the standard model quarks mix with weak-isodoublet heavy vector quarks via the expectation value of a gauge singlet scalar, that we, can account for the observed baryon asymmetry with conservative estimates for the uncertain parameters of electroweak baryogenesis, provided that the heavy vector quarks are not heavier than a few hundred GeV and that the coupling of the standard model quarks to the heavy vector quarks and gauge singlet scalars is not much smaller than order of 1, corresponding to a mixing angle of the heavy vector quarks and standard model quarks not much smaller than order of 10(-1).