121147087
The Angular Correlation of Scattered Annihilation Radiation
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.
118400125
The Discovery of the Parity Violation in Weak Interactions and Its Recent Developments
This address was presented by Chien-ShiungWu as the Nishina Memorial Lecture at the University of Tokyo, March 31, 1983
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.
7640052
Spin determination and calculation of nuclear superdeformed bands in A~190 region.
Using the two-parameter expression for rotational spectra, {ital E}({ital I})={ital a}( {radical}1+{ital bI}({ital I}+1) {minus}1), derived from the Bohr Hamiltonian, the spins of 22 superdeformed bands observed in the {ital A}{similar to}190 region were determined. The calculated transition energies depend sensitively on the prescribed spins. The agreement between the calculated and observed transition energies is incredibly well when a correct spin assignment is made. The kinematic and dynamic moments of inertia were extracted from the observed transition energies and their variation with rotational frequency was investigated.
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.
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.
117599682
Quantum fluctuations of the stress tensor
14403021
Fluctuations of the Hawking flux
The fluctuations of the flux radiated by an evaporating black hole will be discussed. Two approaches to this problem will be adopted. In the first, the squared flux operator is defined by normal ordering. In this case, both the mean flux and the mean squared flux are well defined local quantites. It is shown that the flux undergoes large fluctuations on a time scale of the order of the black hole's mass. Thus the semiclassical theory of gravity, in which a classical gravitational field is coupled to the expectation value of the stress tensor, breaks down below this time scale. In the second approach, one does not attempt to give meaning to the squared flux as a local quantity, but only as a time-averaged quantity. In both approaches, the mean squared mass minus the square of the mean mass grows linearly in time, but four times as fast in the second approach as in the first.
119211117
Trapping effects on inflation
We develop a Lagrangian approach based on the influence functional method so as to derive self-consistently the Langevin equation for the inflaton field in the presence of trapping points along the inflaton trajectory. The Langevin equation exhibits the backreaction and the fluctuation-dissipation relation of the trapping. The fluctuation is induced by a multiplicative colored noise that can be identified as the the particle number density fluctuations and the dissipation is a new effect that may play a role in the trapping with a strong coupling. In the weak coupling regime, we calculate the power spectrum of the noise-driven inflaton fluctuations for a single trapping point and studied its variation with the trapping location. We also consider a case with closely spaced trapping points and find that the resulting power spectrum is blue.
119279483
Gravity Waves from Quantum Stress Tensor Fluctuations in Inflation
We consider the effects of the quantum stress tensor fluctuations of a conformal field in generating gravity waves in inflationary models. We find a non-scale invariant, non-Gaussian contribution which depends upon the total expansion factor between an initial time and the end of inflation. This spectrum of gravity wave perturbations is an illustration of a negative power spectrum, which is possible in quantum field theory. We discuss possible choices for the initial conditions. If the initial time is taken to be sufficiently early, the fluctuating gravity waves are potentially observable both in the CMB radiation and in gravity wave detectors, and could offer a probe of transplanckian physics. The fact that they have not yet been observed might be used to constrain the duration and energy scale of inflation.