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.
126195733
Double beta decay‐an experimental review
In this review, a brief discussion on the experimental objectives and theoretical conceptions of the neutrinos was introduced. Two different types of experimental methods and their results were presented and discussed.
118741981
Delta I=1 staggering in odd superdeformed nuclei
The {Delta}I=1 staggering in odd superdeformed nuclei in the A{approximately}190 region is systematically investigated. Most of the signature partners in this region show large-amplitude staggerings. The behavior is analyzed and parametrized in the conventional collective model. The spins of the signature partner pairs are assigned in a modified ab expression. {copyright} {ital 1997} {ital The American Physical Society}
120789384
Magnetic dipole hyperfine structure in muonic atoms
Abstract The nuclear finite-size effect in the M1 hyperfine structure of muonic atoms of 93 Nb and 139 La has been studied experimentally. Systematic differences of the finite-size effect between nuclei in which the spin and the orbital angular momentum of the odd proton are parallel or anti-parallel are discussed.
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.
121147087
The Angular Correlation of Scattered Annihilation Radiation
119426946
Fluctuations of quantum radiation pressure in dissipative fluid
Abstract Using the generalized Langevin equations involving the stress tensor approach, we study the dynamics of a perfectly reflecting mirror which is exposed to the electromagnetic radiation pressure by a laser beam in a fluid at finite temperature. Based on the fluctuation–dissipation theorem, the minimum uncertainty of the mirror's position measurement from both quantum and thermal noises effects including the photon counting error in the laser interferometer is obtained in the small time limit as compared with the “standard quantum limit”. The result of the large time behavior of fluctuations of the mirror's velocity in a dissipative environment can be applied to the laser interferometer of the ground-based gravitational wave detector.
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.
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.
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.
119118161
Quantum noise in the mirror-field system: A field theoretic approach
Abstract We revisit the quantum noise problem in the mirror–field system by a field-theoretic approach. Here a perfectly reflecting mirror is illuminated by a single-mode coherent state of the massless scalar field. The associated radiation pressure is described by a surface integral of the stress-tensor of the field. The read-out field is measured by a monopole detector, from which the effective distance between the detector and mirror can be obtained. In the slow-motion limit of the mirror, this field-theoretic approach allows to identify various sources of quantum noise that all in all leads to uncertainty of the read-out measurement. In addition to well-known sources from shot noise and radiation pressure fluctuations, a new source of noise is found from field fluctuations modified by the mirror’s displacement. Correlation between different sources of noise can be established in the read-out measurement as the consequence of interference between the incident field and the field reflected off the mirror. In the case of negative correlation, we found that the uncertainty can be lowered than the value predicted by the standard quantum limit. Since the particle-number approach is often used in quantum optics, we compared results obtained by both approaches and examine its validity. We also derive a Langevin equation that describes the stochastic dynamics of the mirror. The underlying fluctuation–dissipation relation is briefly mentioned. Finally we discuss the backreaction induced by the radiation pressure. It will alter the mean displacement of the mirror, but we argue this backreaction can be ignored for a slowly moving mirror.