124955664
Experimental Test of Parity Conservation in Beta Decay
120646099
MUONIC ATOMS. I. DYNAMIC HYPERFINE STRUCTURE IN THE SPECTRA OF DEFORMED NUCLEI.
121100619
NEW HIGH ACCURACY MEASUREMENT OF THE PIONIC MASS
The pionic x-ray energies of the 4f-3d transition in ..pi..-P and the 5f-4d transition in ..pi..-Ti were measured with a bent-crystal spectrometer at the Nevis synchrocyclotron; and a new value of the pionic mass is deduced to be 139567.5 +- 0.9 keV, leading to an improved value for the ..mu..-neutrino mass of m..nu../sub ..mu..//sup 2/=0.102 +- 0.119 MeV/sup 2/; m..nu../sub ..mu../<0.52 MeV, at 90% confidence level.
5308245
Yrast-yrare interaction strength.
An accurate particle-number-conserving calculation shows that in a single-{ital j} ({ital j}=13/2) model the yrast-yrare interaction {ital V} is always strong and no periodic oscillation of {ital V} with Fermi energy {lambda} is obtained. However, in a two-{ital j} model or realistic nuclei sharp backcrossings do occur for appropriate single-particle level distribution and oscillation of {ital V} with increasing {lambda} is found. The occupation-number distribution for the high-{ital j} shell plays a key role in understanding the backcrossing properties.
29674729
Relation between the kinematic and dynamic moments of inertia in superdeformed nuclei.
The relation between the kinematic and dynamic moments of inertia, {ital scrJ}{sup (1)} and {ital scrJ}{sup (2)}, was analyzed for the normally deformed and superdeformed rotational bands. According to the {ital ab} expression for rotational spectrum, {ital E}({ital I})={ital a}( {radical}1+{ital bI}({ital I}+1) {minus}1), the ratio {ital R}= {radical}({ital scrJ}{sup (1)}){sup 3}/{ital scrJ}{sup (2)} should be {ital I} independent. Extensive analyses for the normally deformed rotational bands in the rare-earth and actinide nuclei show that the {ital R}'s do remain {ital I} independent. The same relation holds well for the superdeformed bands observed in the {ital A}{similar to}190 region, and seems also to hold for those in the {ital A}{similar to}150 region, if spin assignments are made correctly. The {ital I} independence of {ital R} provides an additional support to the spin assignments.
120538673
A streamer chamber used in a search for double beta decay
Abstract A 53 cm dia., 8 cm deep helium-filled streamer chamber is described. At a field strength of 6.2 kV/cm, streamers extend over the entire space between the plates of the chamber and the particle track is shown by bright, narrow regions in the streamers. The mechanism of electrical breakdown in this mode of operation and other modes was investigated. The streamer theory of Raether correctly predicts breakdown-time and dead-space. Penning effect by impurities in the chamber gas appears to influence discharge development significantly at the low field strengths used in track-projecting chambers but not at the high field strengths used in streamer chambers.
119488774
Quantum fluctuations of radiation pressure
Quantum fluctuations of electromagnetic radiation pressure are discussed. We use an approach based on the quantum stress tensor to calculate the fluctuations in velocity and position of a mirror subjected to electromagnetic radiation. Our approach reveals that radiation pressure fluctuations in the case of a coherent state are due to a cross term between vacuum and state dependent terms in a stress tensor operator product. Thus observation of these fluctuations would entail experimental confirmation of this cross term. We first analyze the pressure fluctuations on a single, perfectly reflecting mirror, and then study the case of an interferometer. This involves a study of the effects of multiple bounces in one arm, as well as the correlations of the pressure fluctuations between arms of the interferometer. In all cases, our results are consistent with those previously obtained by Caves using different methods. We argue that the agreement between the different methods supports the reality of the cross term and justifies the methods used in its evaluation.
13893354
Fluctuations of the retarded Van der Waals force
The retarded van der Waals force between a polarizable particle and a perfectly conducting plate is reexamined. The expression for this force given by Casimir and Polder represents a mean force, but there are large fluctuations around this mean value on short time scales that are of the same order of magnitude as the mean force itself. However, these fluctuations occur on time scales which are typically of the order of the light travel time between the atom and the plate. As a consequence, they will not be observed in an experiment that measures the force averaged over a much longer time. In the large time limit, the magnitude of the mean-squared velocity of a test particle due to this fluctuating van der Waals force approaches a constant, and is similar to a Brownian motion of a test particle in a thermal bath with an effective temperature. However, the fluctuations are not isotropic in this case, and the shift in the mean-square velocity components can even be negative. We interpret this negative shift to correspond to a reduction in the velocity spread of a wave packet. The force fluctuations discussed in this paper are a special case of the more general problem of stress tensor fluctuations. These are of interest in a variety of areas of physics, including gravity theory. Thus the effects of van der Waals force fluctuations serve as a useful model for better understanding quantum effects in gravity theory.
119193600
Quantum stress tensor fluctuation effects in inflationary cosmology
We review several related investigations of the effects of the quantum stress tensor of a conformal field in inflationary cosmology. Particular attention will be paid to the effects of quantum stress tensor fluctuations as a source of density and tensor perturbations in inflationary models. These effects can possibly depend upon the total expansion factor during inflation, and hence be much larger than one might otherwise expect. They have the potential to contribute a non-scale invariant and non-Gaussian component to the primordial spectrum of perturbations, and might be observable.
119479826
Possible constraints on the duration of inflationary expansion from quantum stress tensor fluctuations
We discuss the effect of quantum stress tensor fluctuations in de Sitter spacetime upon the expansion of a congruence of timelike geodesics. We treat a model in which the expansion fluctuations begin on a given hypersurface in de Sitter spacetime, and find that this effect tends to grow, in contrast to the situation in flat spacetime. This growth potentially leads to observable consequences in inflationary cosmology in the form of density perturbations which depend upon the duration of the inflationary period. In the context of our model, the effect may be used to place upper bounds on this duration.
119162976
Smearing effect due to the spread of a probe particle on the Brownian motion near a perfectly reflecting boundary
Quantum fluctuations of electromagnetic vacuum are investigated in a half-space bounded by a perfectly reflecting plate by introducing a probe described by a charged wave-packet distribution in time-direction. The wave-packet distribution of the probe enables one to investigate the smearing effect upon the measured vacuum fluctuations caused by the quantum nature of the probe particle. It is shown that the wave-packet spread of the probe particle significantly influences the measured velocity dispersion of the probe. In particular, the asymptotic late-time behavior of its $z$-component, $ $, for the wave-packet case is quite different from the test point-particle case ($z$ is the coordinate normal to the plate). The result for the wave-packet is $ \sim 1/\t^2$ in the late time ($\t$ is the measuring time), in stead of the reported late-time behavior $ \sim 1/z^2$ for a point-particle probe. This result can be quite significant for further investigations on the measurement of vacuum fluctuations.