Electron spin resonance (ESR) dating and thermal ionization mass spectrometric 230 Th/ 234 U dating was conducted on six teeth from the prehistoric site of Amud Cave. By combining the ESR and 230 Th/ 234 U analyses, we obtained burial ages for teeth in various layers of the site. Layer B 1 /6-7, from which the Amud I Neanderthal skeleton was recovered, is dated to 53 Ϯ 8 ka. Layer B 2 /8, which yielded other important human remains including the Amud 7 skeleton, gives a mean burial age of 61 Ϯ 9 ka. One tooth from the lowest layer (B 4 ) yielded a date of 70 Ϯ 11 ka, but another tooth from this layer gave an 113 Ϯ 18 ka. Despite this discrepancy, these ages agree with previously published TL ages on heated flints for the corresponding layers. This agreement between ESR on tooth enamel and TL on burned flint is also seen at all other sites studied with both methods in Israel. ᭧

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Amorphous GaN films have been deposited onto various substrates by ion-assisted deposition. The films were deposited at room temperature using nitrogen ion energies in the range 40-900 eV. Rutherford backscattering spectroscopy and nuclear reaction analysis show that the Ga:N atomic ratio is approximately one for films grown with ion energy near 500 eV; these films have the highest transparency. Films grown with ion energies below 300 eV are Ga rich, and show reduced transparency across the visible. Raman spectroscopy, x-ray diffraction, and transmission electron microscopy confirm the amorphous nature of the films. Annealing studies on a-GaN establish that the films begin to crystallise at a temperature of about 700°C. To investigate the local bonding environment of the Ga or N atoms, we have measured the extended x-ray absorption fine structure (EXAFS) of the transparent GaN films. The EXAFS results indicate that the films are dominated by heteropolar tetrahedral bonding, with a low density of homopolar bonds.

The ( Ru 1-x Nb x) Sr 2( Eu 1.5 Ce 0.5) Cu 2 O z(0 ≤ x ≤ 0.5) compounds have been synthesized and characterized by X-ray diffraction, electric transport, and magnetic susceptibility measurements. We find that there is no significant change in the superconducting transition temperature when Nb is substituted for Ru up to x = 0.5. Unlike RuSr 2( Eu 1.5 Ce 0.5) Cu 2 O z, bulk Meissner effect is observed in the field-cooled magnetization measurements of the Nb doped samples. The experimental results are discussed in conjunction with a reduction of the internal field caused by the Nb substitution for Ru, based on the spontaneous vortex phase interpretation.