Precision charge control for isolated free-falling test masses: LISA pathfinder results

The LISA Pathfinder charge management device was responsible for neutralizing the cosmic-ray-induced electric charge that inevitably accumulated on the free-falling test masses at the heart of the experiment. We present measurements made on ground and in flight that quantify the performance of this contactless discharge system which was based on photoemission under UV illumination. In addition, a two-part simulation is described that was developed alongside the hardware. Modeling of the absorbed UV light within the Pathfinder sensor was carried out with the Geant4 software toolkit and a separate Matlab charge transfer model calculated the net photocurrent between the test masses and surrounding housing in the presence of AC and DC electric fields. We confront the results of these models with observations and draw conclusions for the design of discharge systems for future experiments like LISA that will also employ free-falling test masses

Further evaluation of programs for promoting daily activities and indoor orientation and travel in persons with moderate Alzheimer's disease

These two studies extended the assessment of programs recently developed for promoting activity and orientation in persons with moderate Alzheimer’s disease. Specifically, Study I pursued a new evaluation of a program, in which pictorial instructions of activity steps are presented on a computer screen at preset intervals. Study II pursued a new evaluation of a program using music and strobe lights (emitted at the destinations) as spatial cues to support indoor orientation and travel. Six participants were included, three per study. The results of Study I showed that the participants reached high percentages of correct steps in each of the two activities targeted. The results of Study II showed that the participants had high percentages of correct orientation and travel within their day care context. The results of both studies were in line withthe data of previous studies in these areas. The practical implications of these results for helping participants with moderate Alzheimer’s disease manage activity engagement and orientation/travel are discussed

Multifragment Events from Heavy-Ion Collisions: Sources and Excitation Functions

Multifragment events from 35, 40, 45, and 55 MeV/nucleon La139+12C, Al27, Ca40, V51, Cunat, and La139 reactions can be assigned to sources characterized by their velocity. At each bombarding energy, the probabilities of threefold, fourfold and fivefold events increase substantially with decreasing source velocity, but are independent of the target mass. To remove the bombarding-energy dependence, a simple transformation has been applied which gives the excitation energy of the fused system in the simple incomplete-fusion picture. These ‘‘excitation functions’’ appear to independent of both the system and bombarding energy

Multifragment Events from Heavy-Ion Collisions: Sources and Excitation Functions

Multifragment events from 35, 40, 45, and 55 MeV/nucleon La139+12C, Al27, Ca40, V51, Cunat, and La139 reactions can be assigned to sources characterized by their velocity. At each bombarding energy, the probabilities of threefold, fourfold and fivefold events increase substantially with decreasing source velocity, but are independent of the target mass. To remove the bombarding-energy dependence, a simple transformation has been applied which gives the excitation energy of the fused system in the simple incomplete-fusion picture. These ‘‘excitation functions’’ appear to independent of both the system and bombarding energy

Complex fragment production and multifragmentation in 139^{139}La-induced reactions at 35, 40, 45 and 55 MeV/u

Complex fragment emission (Z\u3e3) has been studied in the reactions of 35, 40, 45 and 55 MeV/u139La+X. Charge, angular, and energy distributions were measured inclusively and in coincidence with other complex fragments, and were used to extract source rapidities, velocity distributions, and cross sectins. Multifragment events increase with both bombarding energy and entrance-channel mass asymmetry. The excitation functions for multifragment events rise strongly with excitation energy. These excitation functions are independent of the target-projectile combination and bombarding energy suggesting, the formation of an intermediate nuclear system, whose decay properties depend mainly on its excitation energy and angular momentum

Complex Fragment Production in 139La-induced Reactions at 35, 40, 45, and 55 MeV/nucleon

Complex fragment emission (Z\u3e3) has been studied in the reactions of 35, 40, 45 and 55 MeV/u139La+X. Charge, angular, and energy distributions were measured inclusively and in coincidence with other complex fragments, and were used to extract source rapidities, velocity distributions, and cross sectins. Multifragment events increase with both bombarding energy and entrance-channel mass asymmetry. The excitation functions for multifragment events rise strongly with excitation energy. These excitation functions are independent of the target-projectile combination and bombarding energy suggesting, the formation of an intermediate nuclear system, whose decay properties depend mainly on its excitation energy and angular momentum