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In recent years the search for life-forms at the earliest periods of geological time has been continued not only at the morphological level but also at the molecular level. This has been possible as a result of the increase in the biochemical knowledge and with the advent of analytical techniques that are capable of describing the intimate molecular architecture of individual molecules in acute detail. The fundamental premises upon which this organic geochemical approach rest are the following: that certain molecules, possessing a characteristic structural skeleton, show a reasonable stability to degradation over long periods of geological time; that their structural specificity can be understood in terms of known biosynthetic sequences; and that their formation by any non-biological means is of negligible probability. In this manuscript it is proposed to critically re-examine these premises and to establish criteria whereby one can differentiate molecules derived from biological systems from those that have their origin in non-biological processes. The importance of establishing such criteria lies in the significance these criteria have in determining whether life exists, or has existed, on other planets. Within the very near future it may be possible to provide an initial answer to this question when the first …

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From EMP technical meeting; Kirtland AFB, New Mexico, USA (25 Sep 1973). Under sponsorship of the Advanced Research Projects Agency, the Lawrence Livermore Laboratory conducted an EMP experiment in conjunction with an underground nuclear event. The purpose of the overall study of which this experiment was a part was to document the characteristics of EMP signals generated by various underground nuclear events to provide checks for theoretical models under development. A major goal was to establish how a specific event configuration affects the signals generated. For this experiment, two separate EMP source mechanisms were considered: that due to an asymmetric gamma ray distribution resulting from shielding and configuration constraints in the vicinity of the device and that due to current induced on the line-of-sight pipe. The instrumentation was not ideally located to sort out the two mechanisms because of significant differences between the planned and as-fired configuration. Nevertheless, signals characteristic of the two mechanisms seem to be apparent in the data. An impulsive (10 MHz) component of the signal is probably a result of the asymmetric gamma distribution. A ringing component (1 MHz) has been attributed to currents on the line-of- sight pipe. (auth)

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The workshop is divided into the following subjects: water quality, air quality, biological impact, hazards, environmental impact evaluation, and land use and socio-economic impact. Individual problems in each subject area are evaluated by the following criteria: probability of occurrence, seriousness of consequences, resource applicability, time urgency for new research, and researchability for new research. Recommended approaches to solution are given for each problem. Minority statements are given in some cases. (MHR)

The cylindrically symmetric beam-foil collision produces excitation and alignment of atom and ion levels similar, but not identical, to that resulting at comparable energies from ion-atom or ion-molecule collisions. When the foil is tilted, the macroscopic change acts on the microscopic scale to produce coherent alignment and orientation of the excited levels. The maximum beam energy range bounding this interaction has not yet been defined. The dynamic interaction which produces these effects is currently not predicted by any theory, although the dynamics of the ions subsequent to the collision are well understood. Refinement of current experimental technique can be expected to better define the final foil surface. The beam-tilted-foil collision promises to be useful in the study of ionic structure via quantum beat, radio-frequency and level-crossing spectroscopy techniques, and may provide a useful probe for certain surface interactions. 4 figs, 48 refs.

High purity copper foils were irradiated with 14.8-MeV neutrons from the rotating target neutron source facility at LLL. The average energy of the neutrons was 14.75 +- 0.1 MeV, and the average fluence was 7.0 x 10$sup 16$ n/ cm$sup 2$. After irradiation each foil was heated to the melting point and the released helium was measured by a mass spectrometer of special design. Isochronal heating was carried out on several samples to establish the type and temperature of maximum release. Calculated cross sections from the literature for the (eta,$alpha$) and (eta,eta'$alpha$) nuclear reactions were used, and the predicted amount of helium was consistently about 0.5 of that actually measured. Because there is very little data on helium generation in metals irradiated with high energy neutrons, these results are important and will be related to potential CTR materials. (auth)

In this work, along with a previous paper three possible uses of 14-MeV deuterium--tritium fusion neutrons are investigated: energy production, neutron multiplication, and fissile-fuel breeding. The results presented include neutronic studies of fissioning and nonfissioning thorium systems, tritium breeding systems, various fuel options (UO/sub 2/, UC, UC/sub 2/, etc.), and uranium as well as refractory metal first-wall neutron-multiplying regions. A brief energy balance and an estimate of potential revenues for fusion devices are given to help illustrate the potentials of these designs.

The FORSS Sensitivity Analysis Code System is described in terms of its objectives and present capabilities. An example is made of a problem specified by the Processing Methods Testing Subcommittee of the Code Evaluation Working Group, i.e., the determination of integral parameters, sensitivities to cross- section data, methods and data uncertainties, and required cross-section accuracies for an infinite media of ZPR 6/7 core composition. (auth)

Chemical explosives may become a key element in many of the in situ energy and mineral recovery methods under development. The potential role of explosives in deep rock mining for resource recovery is discussed. Several energy and mineral recovery programs described are an outgrowth of the Plowshare Program and Explosives R and D conducted as part of the AEC/ERDA mission at Lawrence Livermore Laboratory. Several important aspects of the use of explosives in deep rock mining are reviewed. First, the status of knowledge of deep rock fracturing to create permeability underground is discussed. Completely contained blasting has not been a widely applied tool used in the mining industry. It is concluded that data available on deep rock fracture is minimal and that the mechanisms that control the processes must be understood before technical and economic feasibility can be established. The unusual problems in the selection of an explosive or blasting agent for deep rock applications including emphasis on the functioning at depth and safety aspects are also discussed. Finally, a brief review of similar activities within the U.S. is given.

The LPTR (Livermore Pool Type Reactor) safety system had several undesirable features in its original equipment (vintage 1956). A single trip bus, electron tube construction, and trip failure in the case of a shorted magnet actuator, are some of the problems encountered in the original equipment. The continued use of this old equipment resulted in high maintenance costs, excessive magnet actuator replacement, difficult set-up procedures for operations, and the requirement that the reactor be shut down to make safety level trip tests. This paper describes the solution of the stated problems.

Performance of laser fusion targets depends critically on the characteristics of the incident beam. The spatial distribution and temporal behavior of the light incident on the target varies significantly with power, with choice of beam spatial profile and with location of spatial filters. On each ARGUS shot we photograph planes in the incident beams which are equivalent to the target plane. Array cameras record the time integrated energy distributions and streak cameras record the temporal behavior. Computer reduction of the photographic data provides detailed spatial energy distributions, and instantaneous power on target vs. time. Target performance correlates with the observed beam characteristics.

A description is given of the design and application of a simple e-beam generator for the repetitive pulse pumping of gas lasers. The circuit uses a low inductance Marx and series tuned pulse forming elements.

Recent experiments at the LLL 2.0 terawatt laser irradiation facility Argus have been conducted on glass microshells filled with equimolar DT gas. A variety of microshell dimensions and laser pulse widths have been used with the best results producing in excess of 10/sup 8/ fusion reactions. Numerical simulation of selected experiments using the LASNEX computer code confirm the measured performance. Peak DT ion temperatures of about 5 keV and densities of .2 gm/cm/sup 3/ are calculated and are in agreement with that from neutron time-of-flight and alpha particle spectral measurements together with x-ray diagnostics. Laser light absorption is about 20% efficient. General characteristics of ''exploding pusher'' targets will be discussed.

Considerable need has arisen for the development of well-calibrated x-ray detectors capable of detecting photons with energies between 100 and 1000 electron-volts. This energy region is of significant interest since the x-ray emission from high-temperature (kT approximately 1.0 keV), laser-produced plasmas is predominantly in this range. A high-intensity, subkilovolt x-ray calibration source was developed which utilizes proton-induced inner-shell atomic fluorescence of low-Z elements. The high photon yields and low bremsstrahlung background associated with this phenomenon are ideally suited to provide an intense, nearly monoenergetic x-ray calibration source for detector development applications. The proton accelerator is a 3 mA, 300 kV Cockroft-Walton using a conventional rf hydrogen ion source. Seven remotely-selectable liquid-cooled targets capable of heat dissipation of 5 kW/cm/sup 2/ are used to provide characteristic x-rays with energies between 100 and 1000 eV. Source strengths are of the order of 10/sup 13/ to 10/sup 14/ photons/sec. A description of the facility is presented. Typical x-ray spectra (B-K, C-K, Ti-L, Fe-L and Cu-L) and flux values will be shown. Problems such as spectral contamination due to carbon buildup on the target and to backscattered particles are discussed.

In order to view the thermonuclear burn generated by laser driven implosions of D-T filled microspheres ten to twenty micron diameter gold and tantalum pinholes have been built to image 3.52 MeV alpha particles. KODAK Pathe LR115 Cellulose Nitrate is used as a detector behind an 8.3 x 10/sup -3/ gm/cm/sup 2/ tantalum filter. The 3.52 MeV alpha particles reach the emulsion with approximately 0.9 MeV energy and are absorbed in the first three microns. High energy x-rays and electrons are also imaged, but their greater penetration allows discrimination.

As laser capabilities increase, implosions will be performed to achieve high densities. Criteria are discussed for formation of a low-density corona, preheated supersonically, which increases the tolerance of high convergence implosions to non-uniform illumination by utilizing thermal smoothing. We compare optimized double shell target designs without and with atmosphere production. Two significant penalties are incurred with atmosphere production using 1 ..mu..m laser light. First, a large initial shock at the ablation surface limits the pulse shaping flexibility, and degrades implosion performance. Second, the mass and heat capacity of the atmosphere reduce the energy delivered to the ablation surface and the driving pressures obtained for a given input energy. Improvement is possible using 2 ..mu..m light for the initial phase of the implosion. We present results of 2-D simulations which evaluate combined symmetry and stability requirements. At l = 8, the improvement produced in the example is a factor of 10, giving tolerance of 10 percent.

Reduction of input power requirements for laser and charged particle fusion targets has been predicted by implosion calculations that simulate ignition of only a small fraction of the DT fuel instead of the total mass. Once ignition is reached in this localized region, the burn can propagate through the rest of the fuel mass. An approach that achieves this ignition by use of preheat and self-generated magnetic fields is described here, with the result of lower input requirements, i.e., 30 TW and 100 kJ, to achieve breakeven.