Statistical methods were employed to measure relative values of electron loading and spark-over voltage for a large number of unoutgassed electrode materials. Test voltages up to 110 KV were employed in vacuum of the order of 10<sup>-7 mm Hg. All metals showed a square root dependence between spark-over voltage and spacing.

At high excitation energies, competition of proton and c-particle emission with neutron emission becomes important. For low excitation, the competition between Y-emission, neutron emission, and fission should be taken into account. To aid in the evaluation of this competition an experiment has been performed to measure the number and energy spectrum of the protons and c-particles emitted in the high energy bombardment of uranium with protons, deuterons, and c-particles.

This is an extension of the results reported in UCRL-2203, where bore diameter is determined in a linear accelerator.

Quarterly progress on the metabolic properties of various materials, radiation chemistry, biological studies of radiation effects, health chemistry, health physics.

It has been observed that energetic gaseous ions mark their region of impingement on certain metals in color. Under identical conditions of bombardment, multicharged ions of the same gas mark their impact areas with different colors. The colors are sensitive to the type and energy of the ion as well as to the metal bombarded. These colors may result from reflections from thin films formed by reactions at the target. Because the colors indicate that thicker films are produced with increased ion energy, ion penetration depth as predicted by theory is compared with the depth indicated by the colors observed.

Individual Samarkand wildtype D. melanogaster males were permitted to choose between either two white-eyed or two red-eyed females or between a red-eyed and a white-eyed female. Observations of the flies were made over a period of about two hours and premating periods, intermating periods and the durations of copulations were recorded.

The development of high-energy charged particle accelerators such as the Bevatron and of improved nuclear-event detection devices such as the Berkeley 72-in. hydrogen bubble chamber has greatly increased the need for high-speed data reduction of nuclear events. Full exploitation of the potential of the 72-in. bubble chamber demands a very high-speed analysis system. This paper describes an approach to such a system.

The statistical behavior of measured track quantities, gap density, gap length coefficient, and lacunarity is studied. The transformations which give the expectation values of track quantities on inclined tracks are then found.

Apparent [Sigma] hyperon decay events in a large emulsion stack of 240 9" x 12" pellicles have been classified into those judged to have occurred at rest and those in flight. Of 36 decay events at rest, 21 secondaries were observed to be protons of about 1675 microns range. Of the events decaying in flight, 23 were decays into protons and 46 were decays into near-minimum secondaries. Attempts have been made to trace the tracks of 35 of the lightly ionizing secondaries; the results of this effort are summarized in a table.

The problem of photosynthesis is the problem of defining the way in which green plants are able to convert electromagnetic energy into chemical potential in the form of reduced carbon, usually as carbohydrate, and molecular oxygen. The use of tracer carbon, as carbon-14, has made possible considerable progress in the mapping of the routes taken by the carbon atom from CO2 into plant substances. The techniques of separation and identification that have made this progress possible lie largely in the region of chromatography and radioautography involving fractional-gamma amounts of material. A number of proposals have been made about the photochemical act itself. These proposals have led to the development of direct physical tests of their validity, and some results of these will be described.

Under the stimulus of electronic materials development - particularly thin-film studies - and the need for space environmental simulation chambers, a very rapid increase in the availability of industrial-sized vacuum components and systems operable in the ultrahigh vacuum range has taken place in the last three years. It is the purpose of this paper to explore the design considerations of ultrahigh vacuum systems for metallurgical applications.

To properly assess the "sensitivity" of explosives systems under impact conditions we must obtain detailed information on these mechanisms by which explosives are ignited by impact. It is necessary to know which impact conditions represent the greatest hazard to explosive materials, as well as to know for a given impact condition the relative responses of explosives of interest. I should like to describe to you a program sponsored jointly by the Department of Defense and the Atomic Energy Commission to attain this type of information. A wide variety of impact experiments have been conducted using geometrical arrangements of explosive, plastic, and metal which are relatively simple compared to complete ordnance systems. All of these tests have employed billets of explosive fabricated by standard production techniques, and the billets have been sufficiently large that ignition, once started, has something of the same opportunity to grow or decay as in full scale ordnance assemblies. From these relatively simple tests there has accrued much new useful information on the behavior of explosives under impact. With this new information providing a base from which to work, it is hoped that theoretical calculations on impact phenomena will in the future make a bigger contribution to …

In the course of modern physics research, the need frequently arises for storage of large quantities of electrical energy which can be periodically discharged at high peak power into a load. Until recently, the homopolar machine has been an intriguing device having considerable academic interest but little practical value. In recent years, successful machines have been developed to utilize liquid-metal brush systems. The liquid-metal brush overcomes all the problems associated with current collection power loss, frictional loss, and limiting peripheral velocity. Consequently, these machines are now worth serious consideration where high-current dc generation is required. The main purpose in setting up a homopolar generator test program was to establish the limits to which an essentially standard commercially available generator of this type could be pushed.

Tory 11-A, the first experimental reactor in the Pluto nuclear ramjet program, will be tested in late 1960 at the Nevada Test Site of the Atomic Energy Commission. The fundamental objective of Tory II-A is to demonstrate that a high power density, high-temperature, air-cooled reactor can be successfully designed, constructed, and operated. This application places requirements on the reactor control system which are considerably more stringent than those found in previous reactor systems, both from the standpoint of radiation environment and system performance. To fulfill the system requirements a high-performance reactor control system has been designed and built; control actuation hardware has been developed which can withstand the high-radiation environment of Tory LI-A. This actuation system features radiation-tolerant electrohydraulic components: actuators, servo-valves, solenoid valves, feedback transducers, accumulators and associated hydraulic components. To provide high reliability against undesired shutdowns while carrying out high power level transients, the Tory 11-A control philosophy includes a new concept in reactor safety: reliance on a nonlocking, fast-reset safety system during accident situations. The fast-reset system acts so as to hold the programmed power level rather than initiating an irreversible "scram" action. A reactor "scram", if tolerated, could produce thermal shocks which would seriously damage the …

The Astron, a thermo-nuclear fusion research machine, requires the injection of high-energy electron at 5 MEV emery level +- 1/2 %, 200 amperes, 60 pulses per second, 0.3 usec pulse width. The accelerator will work by the induction principle with approximately 500 magnetic cores, each 1/2 inch thick lined up on centers. Each core will be pulsed by a single primary turn and the electrons forming the secondary will experience a voltage acceleration equivalent to the primary voltage upon passing by each core. The coupling in this arrangement has been tested and it is very nearly unity.

Introduction. The von Neumann stability criterion is used to analyze the stability of three types of difference schemes for partial differential equations. It is shown that, contrary to the usual rule of thumb, there exist symmetric implicit schemes for a class of equations which are unstable for every mesh-ratio but that this cannot occur if (a) there are fewer than three "space" variables or (b) the difference expression is used to approximate the mixed derivative.

The most important component required for the Astron experimental facility is a high energy, high current, pulsed electron accelerator. A thin cylindrical layer of high energy electrons trapped within an axially symmetric magnetic field is the key feature of the Astron thermonuclear device. The trapping magnetic field is constant in time. Therefore, it is not possible to inject electrons and trap the electrons in this field unless during the injection phase a part of the electron energy is absorbed by some friction process. This is accomplished by means of eddy currents generated on suitable passive circuits by the current of the injected electron bunch. This method has ben described elsewhere. However, in order to achieve an effective loss mechanism the current of the injected electron beam must be over one hundred amps. Such high current beams are difficult to handle except if the electron energy is high enough so that the electrostatic repulsive force is compensated to great extent by attractive magnetive forces. Hence the electron energy required is 5 Mev or higher. Other requirements on the electron layer yield the same result.

A buncher and pre-accelerator for A-12 is described that has 360 degree acceptance and could handle a current of one ampere from a low voltage source.

Early in the design of the Mark I accelerator it was decided to install magnetic lenses in the drift tubes. A number of model magnets were constructed and tested to determine the best design for these lenses. This report includes only the results of the tests on the final models of the magnets that are designed for Mark I.

Isotopes of americium and curium with mass numbers less than 242 have been produced by cyclotron bombardment techniques, and several of their nuclear properties have been investigated. The partial alpha half-lives of Am(239), Cm(241), and Cm(240) and the partial half-life for spontaneous fission of Cm(240) were measured. The alpha decay daughter of Cm(238) was found and evidence for the discovery of Am(237) (an -1 hour electron capture activity) and Cm(239) (an -10 hour electron capture activity) has been presented. An Appendix indicating the conditions for separation of the plus three actinides by selective elution from ion exchange resin with citric acid has been included.

The free streaming of neutrons in a cylindrical cavity is investigated. Using experimental data for the flux distribution along the walls, the direct beam hole loss and leakage into the target from the lattice is estimated for the MTA system.

Quarterly summary report of studies conducted through the University of California Radiation Laboratory. Some results reported in the report may be of a preliminary or incomplete nature.

In the past it was felt that the easiest way to treat a three group equation for a MTA lattice was to solve it without certain terms. This iterative procedure converged rapidly for a medium with depleted uranium fuel, and in fact, a second iteration was not needed.

The following report is a quarterly report done by the Physics Division of the University of California's Radiation Laboratory, covering the period of February 1, 1948 to May 1, 1948. This report discusses general physics research and the development and operation of the accelerator.