166 research outputs found
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An Induction Linac Driver For A 0.44 MJ Heavy-Ion Direct Drive Target
The conceptual design of a heavy ion fusion driver system is described, including all major components. Particular issues emerging from this exercise are identified and discussed. The most important conclusion of our study is that due to stringent requirements on ion pulse phase space, we are unable to find a credible accelerator design that meets the requirements of the example target. Either the target design must be modified to accept larger ion ranges and larger focal spot sizes, or we must consider other target options
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Estimates of energy fluence at the focal plane in beams undergoing neutralized drift compression
The authors estimate the energy fluence (energy per unit area) at the focal plane of a beam undergoing neutralized drift compression and neutralized solenoidal final focus, as is being carried out in the Neutralized Drift Compression Experiment (NDCX) at LBNL. In these experiments, in order to reach high beam intensity, the beam is compressed longitudinally by ramping the beam velocity (i.e. introducing a velocity tilt) over the course of the pulse, and the beam is transversely focused in a high field solenoid just before the target. To remove the effects of space charge, the beam drifts in a plasma. The tilt introduces chromatic aberrations, with different slices of the original beam having different radii at the focal plane. The fluence can be calculated by summing the contribution from the various slices. They develop analytic formulae for the energy fluence for beams that have current profiles that are initially constant in time. They compare with envelope and particle-in-cell calculations. The expressions derived are useful for predicting how the fluence scales with accelerator and beam parameters
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Development of Li+ alumino-silicate ion source
To uniformly heat targets to electron-volt temperatures for the study of warm dense matter, one strategy is to deposit most of the ion energy at the peak of energy loss (dE/dx) with a low (E< 5 MeV) kinetic energy beam and a thin target[1]. Lower mass ions have a peak dE/dx at a lower kinetic energy. To this end, a small lithium (Li+) alumino-silicate source has been fabricated, and its emission limit has been measured. These surface ionization sources are heated to 1000-1150 C where they preferentially emit singly ionized alkali ions. Alumino-silicates sources of K+ and Cs+ have been used extensively in beam experiments, but there are additional challenges for the preparation of high-quality Li+ sources: There are tighter tolerances in preparing and sintering the alumino-silicate to the substrate to produce an emitter that gives uniform ion emission, sufficient current density and low beam emittance. We report on recent measurements ofhigh ( up to 35 mA/cm2) current density from a Li+ source. Ion species identification of possible contaminants is being verified with a Wien (E x B) filter, and via time-of-flight
Density functional theories and self-energy approaches
A purpose-designed microarray platform (Stressgenes, Phase 1) was utilised to investigate the changes in gene expression within the liver of rainbow trout during exposure to a prolonged period of confinement. Tissue and blood samples were collected from trout at intervals up to 648 h after transfer to a standardised confinement stressor, together with matched samples from undisturbed control fish. Plasma ACTH, cortisol, glucose and lactate were analysed to confirm that the neuroendocrine response to confinement was consistent with previous findings and to provide a phenotypic context to assist interpretation of gene expression data. Liver samples for suppression subtractive hybridisation (SSH) library construction were selected from within the experimental groups comprising “early” stress (2–48 h) and “late” stress (96–504 h). In order to reduce redundancy within the four SSH libraries and yield a higher number of unique clones an additional subtraction was carried out. After printing of the arrays a series of 55 hybridisations were executed to cover 6 time points. At 2 h, 6 h, 24 h, 168 h and 504 h 5 individual confined fish and 5 individual control fish were used with control fish only at 0 h. A preliminary list of 314 clones considered differentially regulated over the complete time course was generated by a combination of data analysis approaches and the most significant gene expression changes were found to occur during the 24 h to 168 h time period with a general approach to control levels by 504 h. Few changes in expression were apparent over the first 6 h. The list of genes whose expression was significantly altered comprised predominantly genes belonging to the biological process category (response to stimulus) and one cellular component category (extracellular region) and were dominated by so-called acute phase proteins. Analysis of the gene expression profile in liver tissue during confinement revealed a number of significant clusters. The major patterns comprised genes that were up-regulated at 24 h and beyond, the primary examples being haptoglobin, β-fibrinogen and EST10729. Two representative genes from each of the six k-means clusters were validated by qPCR. Correlations between microarray and qPCR expression patterns were significant for most of the genes tested. qPCR analysis revealed that haptoglobin expression was up-regulated approximately 8-fold at 24 h and over 13-fold by 168 h.This project was part funded by the European Commission (Q5RS-2001-02211), Enterprise Ireland and the Natural Environment Research Council of the United Kingdom
The present and future of QCD
This White Paper presents an overview of the current status and future perspective of QCD research, based on the community inputs and scientific conclusions from the 2022 Hot and Cold QCD Town Meeting. We present the progress made in the last decade toward a deep understanding of both the fundamental structure of the sub-atomic matter of nucleon and nucleus in cold QCD, and the hot QCD matter in heavy ion collisions. We identify key questions of QCD research and plausible paths to obtaining answers to those questions in the near future, hence defining priorities of our research over the coming decades
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