Search

Neutron and He-6 momentum distributions from He-8 break-up reactions in a C target have been measured at 240 MeV/u. The two-neutron removal cross section was found to be sigma(-2n) = 0.27 +/- 0.03 b. The nature of the momentum distributions is interpreted in some simple reaction scenarios.

7 pages, 3 figures, 1 table., Transverse and longitudinal momentum distributions of 9Li fragments from 11Li break-up reactions in C, Al and Pb targets have been measured at 280 MeV/u. The two-neutron removal cross-section was measured to be σ(−2n) = 0.26 ± 0.02 b for the carbon target, σ(−2n) = 0.47 ± 0.08 b for the aluminum target and σ(−2n) = 1.9 ± 0.4 b for the lead target. No significant difference is observed between the narrow widths (FWHM ≈ 47 MeV/c) of the transverse and longitudinal momentum distributions of the 9Li fragments. The physical implications of this are discussed., This work was supported by the German Federal Minister for Research and Technology (BMFT) under Contracts 06 DA 641 I, 06 BO 103 and 06 MZ 106 and by GSI via Hochschulzusammenarbeitsvereinbarungen under Contracts DA RICK, BO FRE, F ELE, Mz KRD and partly supported by the Polish Committee of Scientific Research under Contract PB 1158/P3/92/02 and CICYT under contract AEN92-078%CO2-02 (MJGB).

Neutron angular distributions from violent break-up reactions of Li-11 and Be-11 have been measured at 28 MeV/u and 280 MeV/u and at 41 MeV/u and 460 MeV/u, respectively. The derived neutron momentum distributions show a narrow component in transverse momentum that is within uncertainties independent of beam energy and target charge. This component is suggested to be simply related to the momentum distribution of the loosely bound halo neutron(s) in the projectiles.

Collective flow of nuclear matter is one important aspect of the research performed at heavy ion accelerator laboratories. The phenomenon was predicted on the basis of hydrodynamical calculations [1], and experimental evidence was first presented for the systems 93 Nb + 93 Nb and 197 Au + 197 Au in the projectile energy range between 150 and 1050 MeV/u [2]. The comparison to microscopic calculations shows that nuclear matter is compressed to about two to three times the ground state density and that a substantial fraction of the kinetic energy in the entrance channel is converted into compressional energy [3]. In these calculations, the relation between density and compressional energy depends on the parameterization of the nucleon-nucleon inter-action. The values of its parameters will hopefully be restricted by a comparison of the calculations to experimental data, and thus one can obtain information on the nucleon-nucleon interaction within the nuclear medium which is not accessible from other sources.

The γ rays emitted in the radiative fusion reaction 90 Zr+ 90 Zr→ 180 Hg+ xy were measured. No indication was found for a specific direct capture process associated with a high-energy γ ray. The shape of the observed γ spectrum is compatible with a statistical deexcitation of the compound nucleus.

The occurrence of postoperative cystitis is still of sufficient frequency to warrant a discussion and presentation of some of the newer thoughts and methods for the prevention of this condition. A troublesome postoperative cystitis, either temporary or permanent, has often spoiled an otherwise excellent surgical result. Heretofore a postoperative cystitis has been considered by many authors solely as a cystitis due to catheterization. While this view is largely correct, it is our purpose to show that preventable, abnormal anatomic conditions of the bladder, dependent on the surgical procedure itself, are in many cases the real predisposing etiologic factors in the production of the complication, and that the catheter per se is for the most part merely the exciting cause. All authors agree that for the production of a cystitis it is necessary to have, besides the bacterial infection, one or more of the following predisposing factors, i, e., retention, trauma