ABSTRACT
An experiment demonstrating the production of double-Lambda hypernuclei in (K(-),K(+)) reactions on (9)Be was carried out at the D6 line in the BNL alternating-gradient synchrotron. The technique was the observation of pions produced in sequential mesonic weak decay, each pion associated with one unit of strangeness change. The results indicate the production of a significant number of the double hypernucleus (4)(double Lambda)H and the twin hypernuclei (4)(Lambda)H and (3)(Lambda)H. The relevant decay chains are discussed and a simple model of the production mechanism is presented. An implication of this experiment is that the existence of an S = -2 dibaryon more than a few MeV below the double Lambda mass is unlikely.
ABSTRACT
PURPOSE: To examine the effect of a two-phase approach to light-curing, beginning with a period of low-intensity light followed by one of high intensity. MATERIALS AND METHODS: Five different tests were performed in this investigation comparing variable irradiation with continuous irradiation of a resin composite. The tests were surface hardness, adhesion, shrinkage, viscosity, and residual monomer concentration/degree of polymerization. In each test, all specimens were fabricated with Pertaca resin composite. RESULTS: The two-step light-curing approach, using different intensity distributions during polymerization, does not affect shrinkage, surface hardness, or residual monomer concentrations compared with the conventional continuous curing approach if the total irradiation dose is high enough to achieve complete polymerization. Adhesion values may be improved with the two-step approach over the continuous approach. The study supported the theory that material flow is higher using the two-step approach, which reduces contraction stresses in the cavity during polymerization and preserves marginal integrity.
