Air-jet milling of grinding materials

The principles of air-jet milling of fine powders and the influence of air pressure and milling intensity are discussed. Impact, abrasion, and resultant grain shape are also considered

Variations of the Selective Extinction Across the Galactic Bulge - Implications for the Galactic Bar

We propose a new method to investigate the coefficient of the selective extinction, based on two band photometry. This method uses red clump stars as a means to construct the reddening curve. We apply this method to the OGLE color-magnitude diagrams to investigate the variations of the selective extinction towards various parts of the Galactic bulge. We find that $A_{_V}/E_{_{V-I}}$ coefficient is within the errors the same for $l=\pm 5\deg$ OGLE fields. Therefore, the difference of $\sim 0.37\;mag$ in the extinction adjusted apparent magnitude of the red clump stars in these fields (Stanek et al.~1994, 1995) cannot be assigned to a large-scale gradient of the selective extinction coefficient. This strengthens the implication of this difference as indicator of the presence of the bar in our Galaxy. However using present data we cannot entirely exclude the possibility of $\sim 0.2\;mag/mag$ variations of the selective extinction coefficient on the large scales across the bulge.Comment: submitted to ApJ Letters, 10 pages, gziped PostScript with figures included; also available through WWW at http://www.astro.princeton.edu/~library/prep.htm

The Role of Phase Space in Complex Fragment Emission from Low to Intermediate Energies

The experimental emission probabilities of complex fragments by low energy compound nuclei and their dependence upon energy and atomic number are compared to the transition state rates. Intermediate-mass-fragment multiplicity distributions for a variety of reactions at intermediate energies are shown to be binomial and thus reducible at all measured transverse energies. From these distributions a single binary event probability can be extracted which has a thermal dependence. A strong thermal signature is also found in the charge distributions. The n-fold charge distributions are reducible to the 1-fold charge distributions through a simple scaling dictated by fold number and charge conservation.Comment: 15 pages, TeX type, psfig, also available at http://csa5.lbl.gov/moretto/ps/brazil.ps, to appear in Proceedings of the 1st International Conference on Nuclear Dynamics at Long and Short Distances, April 8-12, 1996, Angra dos Reis, Brazi