Integrated Light 2MASS IR Photometry of Galactic Globular Clusters

We have mosaiced 2MASS images to derive surface brightness profiles in JHK for 104 Galactic globular clusters. We fit these with King profiles, and show that the core radii are identical to within the errors for each of these IR colors, and are identical to the core radii at V in essentially all cases. We derive integrated light colors V-J, V-H, V-K_s, J-H and J-K_s for these globular clusters. Each color shows a reasonably tight relation between the dereddened colors and metallicity. Fits to these are given for each color. The IR--IR colors have very small errors due largely to the all-sky photometric calibration of the 2MASS survey, while the V-IR colors have substantially larger uncertainties. We find fairly good agreement with measurements of integrated light colors for a smaller sample of Galactic globular clusters by Aaronson, Malkan & Kleinmann from 1977. Our results provide a calibration for the integrated light of distant single burst old stellar populations from very low to Solar metallicities. A comparison of our dereddened measured colors with predictions from several models of the integrated light of single burst old populations shows good agreement in the low metallicity domain for V-K_s colors, but an offset at a fixed [Fe/H] of ~0.1 mag in J-K_s, which we ascribe to photometric system transformation issues. Some of the models fail to reproduce the behavior of the integrated light colors of the Galactic globular clusters near Solar metallicity.Comment: Accepted for publication in the A

Quantum properties of the Dirac field on BTZ black hole backgrounds

We consider a Dirac field on a $(1 + 2)$-dimensional uncharged BTZ black hole background. We first find out the Dirac Hamiltonian, and study its self-adjointness properties. We find that, in analogy to the Kerr-Newman-AdS Dirac Hamiltonian in $(1+3)$ dimensions, essential self-adjointness on $C_0^{\infty}(r_+,\infty)^2$ of the reduced (radial) Hamiltonian is implemented only if a suitable relation between the mass $\mu$ of the Dirac field and the cosmological radius $l$ holds true. The very presence of a boundary-like behaviour of $r=\infty$ is at the root of this problem. Also, we determine in a complete way qualitative spectral properties for the non-extremal case, for which we can infer the absence of quantum bound states for the Dirac field. Next, we investigate the possibility of a quantum loss of angular momentum for the $(1 + 2)$-dimensional uncharged BTZ black hole. Unlike the corresponding stationary four-dimensional solutions, the formal treatment of the level crossing mechanism is much simpler. We find that, even in the extremal case, no level crossing takes place. Therefore, no quantum loss of angular momentum via particle pair production is allowed.Comment: 19 pages; IOP styl

The activation energy for GaAs/AlGaAs interdiffusion

Copyright 1997 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. This article appeared in Journal of Applied Physics 82, 4842 (1997) and may be found at

Generalization of the NpNnN_pN_n Scheme and the Structure of the Valence Space

The $N_pN_n$ scheme, which has been extensively applied to even-even nuclei, is found to be a very good benchmark for odd-even, even-odd, and doubly-odd nuclei as well. There are no apparent shifts in the correlations for these four classes of nuclei. The compact correlations highlight the deviant behavior of the Z=78 nuclei, are used to deduce effective valence proton numbers near Z=64, and to study the evolution of the Z=64 subshell gap.Comment: 10 pages, 4 figure