PISA – an experiment for fragment spectroscopy at the Internal Beam of COSY: application of an Axial Ionization Chamber
ABSTRACT The Proton-Induced SpAllation (PISA) experiment performed at the internal beam facility of the COSY storage ring in Jülich, Germany, which is aimed at the precise measurement of double differential cross-sections over a broad range of energies and angles for spallation reactions induced by protons of 200– energy in various targets, is presented. In this paper the emphasis is put on the design, principles of operation and performance of a Bragg Curve Detector (BCD) optimized for internal beam experiments at storage rings. Very clean and distinct product identification (with Z up to ∼14) from reactions, in which a Ni target was bombarded with a circulating proton beam, is obtained. The individual elements are resolved for emission energies higher than . Moreover, due to the detector read-out achieved by coupling a specially designed current sensitive preamplifier directly to a sampling ADC, the shape analysis of the signals from the BCD allows the isotope identification of light particles with A up to ∼11. It is also found that the BCD can be used efficiently as a thin ΔE detector for the telescope consisting of the BCD and a series of silicon detectors.
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ABSTRACT: Thermoset and thermoplastic polyimides have complementary physical/mechanical properties. Whereas thermoset polyimides are brittle and generally easier to process, thermoplastic polyimides are tough but harder to process. It is expected that a combination of these two types of polyimides may help produce polymers more suitable for aerospace applications. Semi-Interpenetrating Polymer Networks (S-IPNs) of thermoset LaRC(Trademark)-RP46 and thermoplastic LARC(Trademark)-IA polyimides were prepared in weight percent ratios ranging from 100:0 to 0: 100. Positron lifetime measurements were made in these samples to correlate their free volume features with physical/mechanical properties. As expected, positronium atoms are not formed in these samples. The second life time component has been used to infer the positron trap dimensions. The "free volume" goes through a minimum at about 50:50 ratio, suggesting that S-IPN samples are not merely solid solutions of the two polymers. These data and related structural properties of the S-IPN samples have been discussed in this paper.02/1998;