An apparatus is described that permits the use of highly ionizing radiations of the Berkeley 60-inch Cyclotron for radiobiological experimentation (ie., deuterons, alpha particles and carbon nuclei).

Progress reports on Accelerator Development Program, High Frequency Program, beam dynamics in strong focusing linear accelerators, spiral beam buncher experiments, dynamical properties of Mark I, mechanical design, and Target Physics Program.

The angular distribution of charged x mesons produced by 300 <x> 30 Mev neutrons on C12 and Be9 have been studied. An analysis of the kinematics for meson production in a nucleon-nucleon collision indicates a fairly well defined center-of-mass system.

The angular distribution of the reaction p + p--w+ + d has been measured with the meson and deuteron detected in coincidence. Measurements were made at 30' and 90' in the center of mass system for an incident proton energy of 338 Mev. Similar measurements were made at 30', 60' and 90' for 332 Mev protons.

Absolute differential cross sections for the reaction p + p - w+ + d were obtained by detecting meson-deuteron coincidences produced by passing the 340-Mev external proton beam of the Berkeley synchro-cyclotron through a liquid hydrogen target.

In the past year, exploratory data have been taken to determine the relative solubilities of hydrogen and deuterium in various solvents in the vicinity of room temperature and atmospheric pressure. This investigation is one phase of a program to determine the feasibility of separating deuterium from hydrogen by means of rectified absorption.

The purpose of this letter is to point out certain discrepancies between previous work on the decay of Rb82 (6.3 hour, B+, K-capture) and studies made recently at the University of California Radiation Laboratory.

Numerous articles have recently been published on nuclear pulse height analyses. This report describes an approach to the problem using existing scaling equipment (scale of 1024) as building blocks in a multi-channel pulse height analyzer.

Presented herein is a philosophy for designing wideband multistage transistor amplifiers. The amplifier is visualized as an integral unit, the interstage networks constituting the elements of the amplifier unit. By designing the amplifier as a unit and adjusting the overall response (gain and bandwidth) with the interstage time constants, an increase in gain-bandwidth product is realized over the iteratively designed amplifiers. The resulting increase in gain-bandwidth product results from absence of the bandwidth shrinkage factor for multistage amplifiers. Formulas are derived for both a two- and three-transistor integrally designed wideband amplifier, in which shunt peaking networks are used for coupling. Experimental amplifiers were constructed following these formulas, and the observed performance agreed quite well with the calculations.

The validity of the nuclear track emulsion technique for fast-neutron dosimetry is examined in the exposure of a human phantom to PuBe neutrons, Semiautomatic track scanning and high-speed data analysis obviate the major disadvantages of emulsion dosimetry, and allow the absolute differential proton track energy spectrum at various locations in the phantom to be obtained without a serious cost in time. From this are calculated the total absorbed local tissue dose due to proton recoils and the local thermal neutron intensity during irradiation.

In previous letters we have reported a Av resonance, called Y*1, observed through the study of the interaction of 1.15-Bev/c K* mesons in hydrogen in the Lawrence Radiation Laboratory 15-in. bubble chamber. We now wish to report the results of the study of the three reactions [formula](1), [formula](2) and [formula](3).

A system for measuring depths of cryogenic liquids is described. The indicating device is a modified differential pressure gage. The level sensing probes are of various types, either permanent or removable. The heat leak to cryogenic liquids may be made negligibly small.

Recently a T=1 resonance in the [Alpha w] system called [Y*1] has been observed with a mass of 1385 Mev. Two types of resonances have been predicted that might relate this observation to other elementary-particle interactions: (1) P 3/2 resonances in the Alpha w and Sigma w systems predicted by global symmetry corresponding to the (3/2, 3/2) resonance of the wN system, (2) a spin-1/2 Y-w resonance resulting from a bound state in the KN system. The position and width of the observed [Y*1] resonance agree with both theories but since the spin and parity have not yet been determined, it is impossible at present to distinguish between the two theoretical interpretations.

Thin foils suitable for transmission electron microscopy have been prepared from bulk specimens of Cu-12.0% Al alloy quenched from 800' C to produce martensite. The martensitic structure consists of long lenticular plates which are twinned on 20-50A scale. The twin planes in the martensite are shown to be [formula]. There is evidence that this structure is ordered as expected for a transformation from an ordered parent lattice. Experiments using a high temperature stage show that the decomposition of the martensite on tempering can be followed directly, but the martensitic transformation did not recur on cooling.

The structure and operation of cyclotrons are discussed. Factors limiting cyclotron size and energy are given. Improvements to the basic continuous-wave cyclotron are described, including frequency modulation, strong focusing, and variable-energy facilities.

The problem of crystal structure of the martensitic B1 phase of the eutectic alloy in the Cu-Al system still requires a more accurate clarification (Hun ger and Dienst 1960, Tarora 1949). Martensitic phases in general are formed through small thrust (shear) deformations of the original lattice. On this basis the results of Hunger and Dienst (1960) are doubtful, since the lattice constants found by them have required a considerable reclassification. From the known lattice constants of the B1 phase (Tarora, 1949) and the orientation relationships of the B1 phase (Wassermann, 1934) one has expected a hexagonal lattice for the martensitic phase with [formula].

Based on the assumption that the noise contribution of a semiconductor detector is due solely to the bulk properties of the semiconductor, equations are presented which indicate the theoretical limits of noise in detector-amplifier combinations. These equations show that an optimum amplifier time constant and detector bias voltage exist for which condition the minimum noise is independent of the semiconductor resistivity. The optimum performance of a detector-amplifier system is shown to depend only upon detector area, input capacity (less detector capacity), semiconductor minority carrier lifetime, and the transconductance of the amplifier input tube. A new detector structure including a guard-ring electrode as an integral part of the detector structure is described which largely eliminates noise due to surface leakage. Experimental results for detector leakage and energy resolution are presented which agree well with theory.

Recent experience in instrumentation of several nuclear-physics experiments has demonstrated the feasibility of automating the data-acquisition phases of the experiment. Electronic circuits are employed wherever the rate of data flow would be slowed by the use of human operations. Information is selected, temporarily stored, and then recorded in a form suitable for immediate entry into a computer. Experimenters thus freed from the tedious aspects of data collection can devote their time to studying the results of the experiments. Potentially useful nuclear events are first selected by the fast-logic part of the instrumentation. Circuits performing simple logical functions are packaged in modular form for easy grouping into particular coincidence, gating, and mixing configurations. Circuits with slower response times are used for temporary storage and recording operations. Automatic test routines are used to initially align the equipment as well as provide continuous calibration during the experiments. Some of the high-speed circuits are described as well as the methods used to incorporate them into a large counting system.

This revised version contains material published in the two years since the original report was issued in January 1960. The report covers the history of the discovery of fission, fission theory, and the probability of fission. It discusses the distribution of mass in fission, the distribution of nuclear charge in fission, kinetic energy of fission fragments, and the role of neutrons and gamma rays in fission.

This report was prepared at the request of the Subcommittee on Radiochemistry of the Committee on Nuclear Science of the National Research Council as a contribution to a proposed master file on the radiochemistry of all the elements. All known material on the radiochemistry of thorium is included in this report.

With the increasing availability of accelerators capable of producing beams of heavy ions it has become useful to know the cross section for a heavy ion to form a compound nucleus by interaction with a target nucleus. The results of calculations based on two simple models are presented here in order to give some idea of the magnitude of this cross section as a function of the energy of the bombarding particle.

A method is presented for measuring the average energy of the neutrons from a source. The attenuation of the neutrons by polyethylene is measured by the use of a long counter in good geometry. The attenuation length is a sensitive function of the neutron energy. The average neutron energies from several (o, n) sources have been measured and agree well with values obtained by other techniques.

Since 1940 ten transuranium elements have been discovered. This lecture describes the history of these elements and the methods used in their discovery.

The increasing exponential function e-at [a > 0] characterizes such natural events as gas discharges, neutron multiplication, and the transistor avalanche phenomenon. This report describes an instrument for measuring the rate of rise, a, of an increasing electrical exponential signal.