A focusing system which utilizes two f/0.47 doublets in conjunction with ellipsoidal mirrors produces two focusing cones with half angles of 81.5/sup 0/. This system has been used with the LLL Janus laser system to irradiate and implode DT filled glass microshells approximately 80 ..mu..m diameter. The purpose of the system was to provide more uniform heating of the pusher and compression of the fuel than had been obtained with Janus irradiated targets using f/1 lenses. Neutron yields of approximately 10/sup 7/ per event have been obtained and x-ray micrographs indicate tha the heating of the pusher was more uniform. Also the implosions are definitely more spherical than those obtained with the f/1 lenses. Data is also presented which add further confirmation to the importance of absorption by plasma wave resonance for non normal incidence of the laser light with the target.

To determine the feasibility of recovering data actively from x-ray imaging instruments used in the Lawrence Livermore Laboratory Laser Fusion Program, a commercial silicon video sensor was used to detect patterns of soft x-rays (1-8 keV). The sensor is a 2-dimensional frame transfer charge coupled device (CCD), modified to allow direct access of x-rays to the sensitive silicon. The x-ray sensitivity, linearity, and dynamic range of the CCD are discussed.

The need in clinical nuclear medicine for imaging devices with high spatial resolution has been discussed at length for many years. More recently, specialists in cardiology and neurology have restated this need for greater resolution in order to effect earlier or more accurate diagnoses of brain tumors, cerebral and myocardial ischemia and infarcts and septum defects, among others. Our approach to filling this need is to ultimately develop a 3072-element, high-purity germanium camera with a 2-mm spatial resolution, an energy resolution of 2 to 3 percent for /sup 99m/Tc, and a clinically useful area of 123 cm/sup 2/ for imaging the average adult heart, breast or brain. To this end, a 100-element prototype has been constructed and images of rats and mice have been obtained with the use of single and multiple isotopes. A second prototype with 512 elements has also been completed and tested. The 512 elements are derived from an array of electrodes, on the bottom of two germanium crystals, orthogonal to 16 electrodes on the top. The top electrodes are electrically in parallel and have a common electronic readout. The p-contact is palladium over germanium oxide, and the n-side is gold over the lithium diffusion. Cooling for …

Experiments were performed on the Janus laser with ..cap alpha..- spherical illumination system producing very nearly uniform energy deposition on microscopic laser fusion targets. The target performance as measured by the thermonuclear reaction yield was increased by a factor of 2.5 over experiments performed with f/1 lenses. Simple considerations of useful absorbed energy together with ..cap alpha..-particle time-of-flight measurements indicate that the D-T ion temperatures were not increased over those of earlier experiments. The increased neutron yield is thus to first order caused by the greater uniformity of compression achieved. Measurements of absorption as a function of focal overlap of the ellipsoidal mirrors support the hypothesis that resonance absorption plays an important role in these laser fusion experiments.

Following the successful design in 1974 of a 256-channel battery-powered pulse-height analyzer system, we have completed a second-generation analyzer with advanced features, lighter weight, and more rugged construction. The 17-kg analyzer includes a NaI detector and is packaged as a small suitcase; it has high stability and accuracy to allow use over the temperature range from --30 to +70/sup 0/C. The waterproof unit has many features not found on any commercial unit to allow sophisticated analysis by non-electronics oriented personnel. Its 36-button keyboard will allow manipulation of multiple spectra, integrations, and expanded energy scale with readout in keV. If its self-contained SX70 display camera is not sufficient for record keeping, the unit will telemeter all data onto analog tape or send to a remote computer via phone coupler.