ACCUMULATION OF HIGH INTENSITY BEAM AND FIRST OBSERVATIONS OF INSTABILITIES IN THE SNS ACCUMULATOR RING

The Spallation Neutron Source storage ring, designed to accumulate up to 1.5e14 protons per pulse, was commissioned in January of 2006. During the run, over 1.e14 protons were accumulated in the ring in the natural chromaticity state without any sign of instabilities. The first beam instabilities were observed for a high intensity coasting beam with zero chromaticity. Preliminary analysis of data indicates instabilities related to extraction kicker impedances, resistive wall impedances, and electron-proton instability. Here we review the background theory and design philosophy of the ring, as it relates to instabilities, and compare the precommissioning predictions with the experimental measurements

Basal Ganglia and Behaviour: Behavioural Effects of Deep Brain Stimulation in Experimental Neurological and Psychiatric Disorders

The use of deep brain stimulation (DBS) to control severely disabling neurological and psychiatric conditions is an exciting and fast emerging area of neuroscience. Deep brain stimulation has generally the same clinical effects as a lesion with respect to the improvement of clinical disability, but has more advantages such as its adjustability and reversibility. To this day, fundamental knowledge regarding the application of electrical currents to deep brain structures is far from complete. Despite improving key symptoms in movement disorders, DBS can be associated with the occurrence of a variety of changes in cognitive and limbic functions both in humans and animals. Furthermore, in psychiatric disorders, DBS is primarily used to evoke cognitive and limbic changes to reduce the psychiatric disability. Preclinical DBS experiments have been carried out to investigate the mechanisms underlying the clinical effects of DBS for at least three (interrelated) reasons: to increase our scientific knowledge, to optimize/refine the technology, or to prevent/reduce side effects. In this review, we will discuss the behavioural effects of DBS in experimental neurological and psychiatric disorders