[en] It is shown that, if the prediction of quantum effects of enclosed electromagnetic fluxes is eliminated from theory by the use of discontinuos wave functions, that leads to the prediction of observable effects depending on the amount of flux external to the system under consideration, a circumstance which is contrary to observation. It is concluded that in a simply connected space the wave functions representing the state of the charged particles in the Aharonov-Bohm experiment are single valued and continuos

[en] In this paper we discuss the relevance of electron-nuclear double transitions for the problem of the amplification of gamma rays. We consider the electron-nuclear coupled system of ¹⁵¹Eu in a CaF₂ lattice, in the presence of a strong static magnetic field. We analyze the possibility of pumping this electron-nuclear coupled system from the ground atomic electron Zeeman level to a higher electron level with the aid of a microwave magnetic field, while the nucleus is simultaneously undergoing a gamma-ray transition to the nuclear ground state. It is shown that an overall inversion condition can be satisfied even in the absence of inversion of the nuclear populations, provided that the ratio of the electron populations in the excited and ground electron Zeeman states has a sufficiently small value

[en] The neutron yields observed in inertial confinement fusion experiments for higher convergence ratios are about two orders of magnitude smaller than the neutron yields predicted by one-dimensional models, the discrepancy being attributed to the development of instabilities. We consider the possibility that ignition and a moderate gain could be achieved with existing laser facilities if the laser driver energy is used to produce only the radial compression of the fuel capsule to high densities but relatively low temperatures, while the ignition of the fusion reactions in the compressed fuel capsule will be effected by a synchronized hypervelocity impact. A positively-charged incident projectile can be accelerated to velocities of 3.5x10⁶ m s^-1, resulting in ignition temperatures of about 4 keV, by a conventional low-β linac having a length of 13 km if deuterium-tritium densities of 570 g cm^-3 could be obtained by laser-driven compression. (orig.)

[en] Recent concerns about the gauge dependence of transition amplitudes describing the changes of state of quantized systems interacting with electromagnetic radiations have led to the development of invariant schemes for the expression of the time-dependent quantities involved. It is shown in this work that such schemes are not uniquely specified by the requirement for gauge invariance. Moreover, they simply exchange a dependence upon the gauge of the electromagnetic potentials for a previously unrecognized dependence upon the representation of basis states describing initial and final states of the process that is equivalent to a dependence upon gauge. However, general expressions are developed in this work which show that resonant transitions which correspond to physically observable processes involving the pure or mixed absorption and emission of N photons are gauge invariant regardless of the multipolarity of the transition moments and independent of the representation of the basis states of the system. A preferred representation is introduced which is shown to accommodate the physical effects generally encountered

[en] This paper reports the examination of the general problem of multiphoton processes which might occur at the nuclear level when one of the photons belongs to an intense radiation field of optical frequencies. Transition probabilities are reported which relate the rates for γ-ray transitions induced by the optical radiation to the Breit-Wigner cross sections for the absorption or emission of single γ photons. In emission the induced processes of both anti-Stokes Raman scattering and two-photon emission are considered and both are found to lead to the generation of tunable γ radiation. Transition probabilities are calculated to be large enough to support the production of usable spectral sources that could be tuned over a range of γ-ray energies approximately 10³ times greater than can be realized by conventional Moessbauer techniques. Analogous possibilities for the detection of nuclear reactions induced by intense optical fields also have been evaluated in this work

[en] Recent calculations have shown that multiphoton transitions in a nucleus that involve a γ-ray photon could be induced by intense fields of optical radiation. The effect of such transitions was predicted to be a shift of the γ-ray energy by the addition or subtraction of the energy of the optical photon. A literature search has shown that such optical sidebands have been observed in certain instances on the ⁵⁷Fe Moessbauer line at 14 keV and not satisfactorily explained by conventional models. This work reports the formulation and evaluation of the multiphoton model for the values of experimental variables appropriate to those experiments. Using no fitted parameters, remarkable agreement was obtained between the predictions of the multiphoton theory and the previously reported results

[en] We have studied the center-of-mass collisions of two equimolar deuterium-tritium clusters of radius r, concentration n, and incident velocity v, and have assumed that as a result of the impact of the two clusters a region of hot plasma is created, of temperature T. Theoretical curves are given for the power and spectral intensity of the bremsstrahlung radiation generated at the impact of the deuterium-tritium clusters, as a function of their radius, mean energy per particle and concentration of particles in the cluster, for different values of the gain parameter G and of the compression parameter F. In order to estimate the importance of the radiative processes, we have compared the energy radiated during the time of inertial confinement with the initial energy of the region of impact. We have also investigated the problem of the spectral distribution of the radiation emitted in the region of impact. The radius of the incident clusters and the required initial energy have been represented as functions of the temperature T for different values of the parameters F, G. (author)

[en] Theoretical curves are given for the power and spectral intensity of the bremsstrahlung radiation generated by the collision of deuterium-tritium clusters, as a function of their radius, mean energy per particle and concentration of particles in the cluster, for different values of the gain parameter G and of the compression parameter F. In order to estimate the importance of the radiative processes, the energy radiated during the time of inertial confinement is compared with the initial energy of the region of impact. We also investigate the spectral distribution of the radiation emitted in the region of impact, both in the low-energy region and for photon energies which are comparable or larger than the plasma temperature T. Then we study the fusion gain for the collision of two clusters, for DT, DD, D³He, p⁶Li and p¹1B fusion processes, assuming that the particle concentration is that corresponding to the normal, uncompressed state of the clusters. The gain G is calculated as a function of T for several values of the cluster radius. Moreover, the radius of the clusters for which the gain has the value G=1 is represented as a function of the plasma temperature T, and we determine the incident energy required in the center-of-mass system to obtain a gain G=1 at a temperature T by cluster impact, for the aforementioned fusion processes. The requirement on the incident energy for a gain G=1 by uncompressed cluster impact is of about 1 MJ for the DT reaction, and is very much larger for the other fusion processes. (author)

[en] It is shown that transitions between the 2s and 2p states of the A_2π atoms consisting of pairs of π⁺,π^- mesons can be induced by the scattering of an incident relativistic beam of A_2π atoms by a thin magnetic layer. We calculate the transition probability as a function of the thickness of the magnetic layer. For a relativistic factor γ=(1-v²/c²)^-1/2=20 of the incident A_2π atoms and a magnetic field B=2 T we find a probability of the 2s→2p transition of 0.0013. copyright 1996 The American Physical Society

[en] This paper reports an analytic estimate of the cross section for the absorption of a γ-ray photon when the nuclear recoil is compensated by the simultaneous absorption of an optical photon from the radiation field of a high-power laser. A multiphonon transition model is developed and cross sections of the order of 1 fm² are obtained when nearly resonant intermediate states of nuclear excitation are assumed to lie within a few tens of eV of the transition energy