Non Linear Current Response of a Many-Level Tunneling System: Higher Harmonics Generation

The fully nonlinear response of a many-level tunneling system to a strong alternating field of high frequency $\omega$ is studied in terms of the Schwinger-Keldysh nonequilibrium Green functions. The nonlinear time dependent tunneling current $I(t)$ is calculated exactly and its resonance structure is elucidated. In particular, it is shown that under certain reasonable conditions on the physical parameters, the Fourier component $I_{n}$ is sharply peaked at $n=\frac {\Delta E} {\hbar \omega}$, where $\Delta E$ is the spacing between two levels. This frequency multiplication results from the highly nonlinear process of $n$ photon absorption (or emission) by the tunneling system. It is also conjectured that this effect (which so far is studied mainly in the context of nonlinear optics) might be experimentally feasible.Comment: 28 pages, LaTex, 7 figures are available upon request from [email protected], submitted to Phys.Rev.

The Sudbury Neutrino Observatory

The Sudbury Neutrino Observatory is a second generation water Cherenkov detector designed to determine whether the currently observed solar neutrino deficit is a result of neutrino oscillations. The detector is unique in its use of D2O as a detection medium, permitting it to make a solar model-independent test of the neutrino oscillation hypothesis by comparison of the charged- and neutral-current interaction rates. In this paper the physical properties, construction, and preliminary operation of the Sudbury Neutrino Observatory are described. Data and predicted operating parameters are provided whenever possible.Comment: 58 pages, 12 figures, submitted to Nucl. Inst. Meth. Uses elsart and epsf style files. For additional information about SNO see http://www.sno.phy.queensu.ca . This version has some new reference

Lattice dynamics, thermal expansion and specific heat of a Lennard-Jones solid in the quasi-harmonic approximation

In this paper we present the results of an ab initio calculation of the thermal expansion, the specific heat and the mean-square amplitude of vibration of a Lennard-Jones crystal, carried out in the quasi-harmonic approximation. The dynamical problem is solved for 110 values of the density, and the thermal expansion is obtained from a proper minimization of the Helmholtz free energy F(T, a) (2a is the lattice constant). Particular attention is given to the strong density dependence of the vibrational frequencies and the resultant effects on the thermodynamic quantities

Arizona Zinc and Lead Deposits: Part II

This bulletin, which constitutes the second part of a general report on zinc and lead deposits in Arizona, is limited in scope to twelve districts, as noted on Figure 1 and pages 8, 9. The Arizona Bureau of Mines Bulletin No. 156, Arizona Zinc and Lead Deposits -Part I, published in 1950, dealt with ten districts (see Figure 1 and page 10) . Descriptions of other districts and mines are being prepared for subsequent publication. Appreciative acknowledgment is made to the mining companies, operators, and individuals who have furnished information. 115 p.Documents in the AZGS Document Repository collection are made available by the Arizona Geological Survey (AZGS) and the University Libraries at the University of Arizona. For more information about items in this collection, please contact [email protected]