119697750
Gravitationally induced electric fields in conductors.
An estimate for the gravitationally induced electric field is presented that is based on a statistical model for the electrons in a metal in which their long-range electrostatic interaction with a differentially compressed lattice of positive ions is taken into account. The field is in the upward direction and is estimated to be of the order of magnitude $E\ensuremath{\approx}\frac{\mathrm{Mg}}{e}$, where $M$ is the atomic mass, $e$ is the electronic charge, and $g$ is the acceleration due to gravity. For copper, $E\ensuremath{\approx}{10}^{\ensuremath{-}7}$ V/m. An earlier estimate by Schiff and Barnhill gives a field in the downward direction equal to $\frac{\mathrm{mg}}{e}$, where $m$ is the mass of the electron. The difference between our result and theirs is due to different treatments of the effect of lattice compressibility.
123416974
Theory of pulsar magnetospheres
There is a wide range of fundamental physical problems directly related to how pulsars function. Some of these are independent of the specific pulsar mechanism. Others relate directly to the physics of the pulsar and already shed some light on the properties of matter at high density (\ensuremath{\sim}${10}^{15}$ g/cc) and in strong magnetic fields (\ensuremath{\sim}${10}^{12}$ G). Pulsars are assumed to be rotating neutron stars surrounded by strong magnetic fields and energetic particles. It is somewhere within this "magnetosphere" that the pulsar action is expected to take place. Currently there has been considerable difficulty in formulating an entirely self-consistent theory of the magnetospheric behavior and there may be rapid revisions in the near future, which is all the more surprising since many of the issues involve "elementary" problems in electromagnetism. One interesting discovery is that charge-separated plasmas apparently can support stable static discontinuities.
118960042
The state of pulsar theory
Abstract I summarize the status of pulsar theory, now 35 years after their discovery. Although progress has been made in understanding the relevant processes involved, there are several widely held misconceptions that are inhibiting further advances. These include the idea that plasma “must” be accelerated from the magnetic polar caps (the basis for the “Hollow Cone Model”) and the idea that winds would be driven away by centrifugal forces, with large amplitude electromagnetic waves playing no role whatsoever. However, recent theoretical work is converging on a picture that closely resembles the latest HST and Chandra images, providing hope for the future. No less than three groups have recently confirmed the early Krause-Polstorff–Michel simulations showing that the fundamental plasma distribution around a rotating neutron star consists of two polar domes and an equatorial torus of trapped nonneutral plasma of opposite sign charges. Unless a lot of new physics can be added, this distribution renders the Goldreich–Julian model irrelevant (i.e., along with most of the theoretical publications over the last 33 years).
123629832
Intense Coherent Submillimeter Radiation in Electron Storage Rings
Energetic electron bunches in storage rings produce pulsed bursts of incoherent synchrotron radiation. It is pointed out that they should also produce a roughly comparable power output of coherent radio-frequency radiation. Thus electron storage rings, in addition to their intended purpose and their secondary use as intense sources of x rays, might additionally serve as pulsar simulators, producing a similar spectrum of coherent emission, the properties and modification of which could be studied in the laboratory. A spontaneous bunching of electrons (artificially bunched here) might be evidenced as ''superbunching.''
121467224
PARITY NONCONSERVATION IN NUCLEI
BS>The influence of the known weak interactions on the parity of nuclear states is discussed. Derivation of a parity nonconserving interaction rests on the assumption of a current-current hypothesis for the weak interactions. Consequently, observation of parity impurity effects would be an important confirmation of this hypothesis. A simple approximate method of treating the nuclear parity impurity is developed and applied in an effort to find experimental situations favorable to observation of effects due to such impurity. Parity-forbidden alpha decay from excited states of light nuclei and certain electromagnetic transitions in the heavy nuclei appear to be promising. Special attention was paid to the internal conversion electrons from the 123kev transition nn Lu/sup 173/ whose polarization is estimated to be about 0.4%. An effect on polarized neutrons analogous to optical rotation is also discussed. (auth)
116765099
Critique of a recent statistical interpretation of low energy 40Ca(alpha,alpha) elastic scattering
120326165
Airy structure in inelastic light-ion and light heavy-ion scattering
We suggest that the transparency displayed by some light heavy-ion systems, such as {sup 16}O+{sup 16}O, {sup 16}O+{sup 12}C, or {sup 12}C+{sup 12}C, which manifests itself by the emergence of Airy structure in the elastic scattering angular distributions and excitation functions, could also have observable consequences in some inelastic channels. Indeed benchmark calculations for the {alpha}+{sup 40}Ca light-ion system, where a similar mechanism dominates elastic scattering at low energy, reveals the persistence in inelastic scattering of the interference mechanism between the barrier-wave and internal-wave components of the scattering amplitude which underlies the Airy structure in the elastic channel. These calculations seem to point to new phase rules between the elastic and inelastic angular distributions.
118496663
Gravitating superconducting strings with timelike or spacelike currents
We construct gravitating superconducting string solutions of the $U(1{)}_{\mathrm{local}}\ifmmode\times\else\texttimes\fi{}U(1{)}_{\mathrm{global}}$ model by solving the coupled system of Einstein and matter field equations numerically. We study the properties of these solutions in dependence on the symmetry breaking to Planck mass ratio. Using the macroscopic stability conditions formulated by Carter, we observe that the coupling to gravity allows for a new stable region that is not present in the flat space-time limit. We match the asymptotic metric to the Kasner metric and show that the relations between the Kasner coefficients and the energy per unit length and tension suggested previously are well fulfilled for symmetry breaking scale much smaller than the Planck mass. We also study the solutions to the geodesic equation in this space-time. While geodesics in the exterior space-time of standard cosmic strings are just straight lines, test particles experience a force in a general Kasner space-time, and as such, bound orbits are possible.
120998788
Airy minima in the scattering of weakly bound light heavy ions
We reanalyze the existing {sup 6}Li + {sup 12}C elastic scattering angular distributions for incident energies ranging from a few MeV to 318 MeV within the frame of the optical model. Despite the important breakup effects expected in the scattering of such a fragile projectile, the system is found to display a surprising transparency. Indeed the barrier-wave/internal-wave decomposition of the elastic scattering amplitude reveals that a substantial part of the incident flux that penetrates the nuclear interior reemerges in the elastic channel, and typical refractive effects, like Airy minima, are clearly identified in the angular distributions. Coupled channel calculations performed on {sup 12}C({sup 6}Li,{sup 6}Li'){sup 12}C{sup *}(J{sup {pi}}=2{sup +},E{sub x}=4.44 MeV) angular distributions extending through the whole angular range confirm the existence of an important internal-wave contribution in the backward hemisphere. A similar transparency is observed in other systems of this mass region, such as {sup 7}Li + {sup 12}C or {sup 6}Li + {sup 16}O. Finally, we examine recent {sup 6}He + {sup 12}C elastic scattering data obtained at 18 MeV by Milin et al. [Nucl. Phys. A730, 285 (2004)] and extending up to {theta}{sub c.m.}{approx_equal}85 deg., and we suggest additional measurements that could ascertain whether some transparency persistsmore » in the scattering of this radioactive projectile.« less
124193977
High-spin states in Ne-20 reached by O-16 (alpha, alpha) O-16 elastic scattering