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Internal Target System and Induced Radioactivity at the AGS
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When the Brookhaven AGS started operation in the summer of 1960 very little experience with targeting in strong focusing proton synchrotrons was available. While it was evident that targeting techniques would differ markedly from those used in weak focusing machines, only actual running experience would set the proper parameters for a truly satisfactory targeting system. It was, therefore, an advantage that temporary targeting devices were used initially. Work on a more permanent system was not started until the summer of 1961, and the first component of the system installed in January 1962. While further refinements are still continuing the essential features of this targeting system have now sufficiently proven themselves in actual operation to remain unchanged. This system in its present form is the subject of the first portion of this paper.
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Measured Vibrational Frequency Distributions of Ni, V, Ti, and Ti.67-Zr.33
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The BNL cold neutron facility has been used to obtain inelastic scattering cross section data from three first-row transition elements, titanium, vanadium, and nickel, and a random binary alloy Ti.67-Zr.33. From the data, we have computed vibrational frequency distributions exhibit peaks corresponding to major critical points. A comparison of the distributions from the different samples leads to the following conclusions: 1) The shape of the frequency distributions of the b.c.c. metal (V) and f.c.c. metal (Ni) are remarkably similar, the relative positions of the critical points being the same for both; 2) The frequency distribution of the h.c.p. metal (Ti), which has two atoms per primitive cell, shows structure corresponding to acoustical and "optical" modes of vibration; 3) The titanium-zirconium alloy has the h.c.p. structure, and its experimental frequency distribution is similar to that of titanium, except at low frequencies where alloying with the heavier mass zirconium atoms tends to smear out the peaks corresponding to acoustical modes. Measured frequency distributions were obtained for the titanium-zirconium alloy slightly above and below the critical temperature for the phase transition to b.c.c. structure. The frequency distributions in the two phases are different, the most striking feature being a shift of the high frequency critical points to lower values in the high temperature (b.c.c) phase.
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Measurements of Neutron Resonance Parameters
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The subject of this paper is the experimental and technical aspects of the measurements of nuclear resonance parameters. I will confine my remarks to those reactions induced by low energy neutrons, i.e. neutrons of less than approximately 100 kilovolts. The bulk of these measurements have been performed by neutron time-of-flight techniques, and I will direct my attention to these techniques. The first half of this discussion will concern the apparatus with which these measurements are made; the second part will be a discussion of the various experiments by which these parameters are measured, with an emphasis in both areas of discussion on relatively recent developments in the field.