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.

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 study is primarily concerned with obtaining an order-of-magnitude estimate of the electromagnetic fields to be expected from a high-altitude nuclear bomb explosion; and it is not intended to be a complete analysis."