The following report focuses on the study of electrostatic classification of submicron aerosols, with emphasis on particles below 0.1 micron. During the period this work was concerned with detailed studies of the ARF charger, the Whitby ionizer used as a charger or neutralizer, and the high-volume classifier.

Abstract: "This program is a study of the basic variables that affect electrostatic classification of heterogeneous aerosols of submicron size,especially below 0.1[mu]. The variables of interest are particle size, concentration, composition, shape, and initial charge. During this period research was concerned with classifying particles as small as 0.01[mu]. This research included work on an aerosol generator for monodispersed 0.015-[mu] gold particles. The performance of the charger was further improved by studying its basic electrical characteristics. Tests with the electrostatic classifier showed very clearly the interference due to the stabilizer material associated with polystyrene latex suspensions. These suspensions are used to produce monodispersed aerosols for calibration."

Introduction: "This study is concerned with the classification of submicron aerosols by electrostatic means. The controlled charging of the particles without undue aerosol losses is of principal interest. We are investigating means of eliminating the interference due to the deposition of small and large particles in the same area. The sampler is to be developed to classify atmospheric dust particles at a rate approaching 1 cfm. During the period covered by this report, work was concerned with the charger and with bringing the high-volume classifier into routing operation. Further tests were made on the classification of atmospheric dust."

Introduction: "This program is a study of the basic variables that affects electrostatic classification of heterogeneous aerosols of submicron size, especially below 0.1 micron. The variables of concern are particle size, concentration, composition, shape, and initial charge. During this period optimum charger design was studied. The results will serve as a basis for a systematic study of particle charging. A number of improvements were incorporated into the classifier flow system and electrical circuits. The technique for photographing deposits in the electron microscope was also improved, and sample photographs are included."

Introduction: "This project is a study of eletrostatic classification of submicron aerosols with emphasis on particles below 0.1[mu]. Previous work has shown that classification of particles between 0.1 to 1.0[mu] is feasible by this process. Further improvements along this line include the elimination of interference from initial aerosol charge and increase in sampling rate. The effect of heavy deposits on collection have to be established. More information is desired on the charging regime below 0.1[mu]. Also the overlap of the smallest particles with the larger ones has to be eliminated. It is also of interest to study the possibility of measuring the current due to the precipitating particles. This would make it possible to automate the device. During this period project work was initiated again. There was some delay in finalizing the contract and the laboratory work was not started until early in March."

Introduction: "This program is a study of the basic variables that affect electrostatic classifications of heterogeneous aerosols of submicron size, especially below 0.1 micron. The variables of interest are particle size, concentration, composition, shape, an initial charge. During this period emphasis was placed on studying and controlling initial charge. A new technique was developed for collecting light and electron microscope samples. Further improvements of the charging device were studied."

Introduction: "This project is a study of electrostatic classification of submicron aerosols, with emphasis on particles smaller than 0.1 micron. The overlap of the smallest particles with the larger ones is of principal concern. Also, a faster sampling rate is desired, i.e., heavier deposits in a shorter time are necessary. During the period covered by this report, work was concerned with studies of charging by corona and diffusion, neutralization of initial charge, and classification of various types if aerosols."

Introduction: "One of the major objectives of this study is to develop a routine charger that has no aerosol losses. Also, the interference due to deposition of small and large particles in the same area must be overcome. During this period efforts were concentrated on the former problem, which is the key to practical application of this device."

From introduction: "This study is concerned with the basic variables that affect the electrostatic classification of heterogeneous aerosols in the submicron range, especially below 0.1 micron. The variables of interest are particle size, concentration, composition, dielectric constant, shape, and initial charge as they relate to rate of charging and therefore to the point of deposition in the classifier."

From abstract: "This report describes work done on ARF Project C 216 from January 5, 1962 to September 15, 1962. The objectives of the program include evolution of an analytical research program to evaluate effects of environment contributed contamination on precise devices"

From abstract: "This report describes and evaluates the variables affecting contamination of precise devices...In the present report these variables are discussed in more detail and the basis for their inclusion in the listing are given. The relative importance of the several parameters will be discussed in another report."

A report about 3 tasks which are undergone in this project. These tasks pertain to preparing computer codes for calculations of wave transmission in layered composites of materials, the performance of gas shock impingement experiments, and analyzing previously obtained experimental data using a liquid driven shock tube.

Report discussing the progress made on various research programs at the Armour Research Foundation during the period from May to June 1962.

From abstract: "This document constitutes ARF Report No. 1207-6, and is a quarterly report on research on the preparation of high specific activity radioisotopes".

"The magnetic properties of color centers were studied to obtain information regarding electron traps in insulators. Experiments designed to determine the equation governing the recovery of resonance after saturation were carried out. Relatively large samples were prepared by the method of additive coloration. KCl and RbCl crystals were used. Resonance saturation as a function of concentration was investigated and no significant dependence found. Measurements of the unsaturated susceptibility were made at liquid nitrogen and liquid helium temperatures. The bleaching of the F-center to form the B-band produced a different resonance. The equipment for observing the saturation and recovery of a portion of the resonance at 4 deg K is described. A theoretical examination was made of the interaction between the vibration of the ions around a negative-ion vacancy in an alkali halide and an electron trapped at that site. (M.C.G.)."

The following quarterly report covers the period from May 16 to August 15, 1962. This report summarizes the progress being made on the study of the saturation and recovery of the hole which can be burned into the magnetic resonance band associated with the F-center in KCl.

The following quarterly progress report covers the period of August 15 to November 15, 1962. It summarizes three activities of the group. The first part is the optical study of the absorption band associated with the F-center in RbCl. The second part discusses some elementary calculations of the spin-lattice relaxation times, the primary purpose of this step is to indicate the nature of the theoretical problem faced and show the large gap between the value calculated theoretically and measured experimentally. The last section includes more data on the shape and recovery of the hole in a EPR band associated with the F-center in KCl.

The following quarterly progress report covers the period from November 16, 1962 to February 15, 1963. This report summarizes three activities that study the ratio of the maximum absorption of the K band to the maximum absorption of the F band has been made in additively colored and [gamma]-irradiated rubidium chloride.

The following quarterly report covers the period during February 16 to May 15, 1963. This report is divided into sections covering the separate activities during this period, studying the thermal behavior of the F-center in RbCl.

Abstract: "The electron paramagnetic resonance (EPR) of color centers in additively colored KCl crystals is measured to observe the effects of optical bleaching at room temperature. Earlier measurements on the F-center are confirmed and the susceptibility is measured at 78 and 300 deg K over five decades of power, including the very low power region. The width and the saturation properties of the individual multiplets are studied in detail and the technique of making EPR measurements on inhomogeneously broadened lines is discussed. A calculation is presented which shows that a slight departure from a Lorentzian multiplet shape can account for the saturation data. The bleached crystals show a resonance which has a width of 35 gauss and a different rate of saturation than the F- center. This resonance is associated with the B-band which appears in the optical absorption."

The following report includes a description of apparatus and techniques for the observation of the behavior of blast shield segments and materials when impulsively loaded, some preliminary dynamic stress-strain data, and some observations of compression wave propagation in porous media.

From abstract: "Transformation kinetics of binary U -Nb and ternary U-Nb-base alloys were investigated. Additions included zirconium, chromium, titanium, silicon, nickel, nnthenium, and vanadium. Encapsulated samples were given a homogenizstion anneal at 1000 or 1100/sup o/C, water-quenched from 906/sup o/C to retain the phase, and reheated to temperatures between 360 and 600/sup o/C. The metastability of the phase was examined by metallographic, hardness, resistometric, dilatometric and x-ray-diffraction techniques. The U -Nb system is characterized by a monotectoid decomposition of the high temperature allotrope at about 645/sup o/C to form alpha and ₂, a niobium-rich cubic structure. Decomposition in U-Nb and in most U-Nb-X alloys occurred by a continuous precipithtion of alpha from the body-centered cubic phase with a resultant enrichment in niobium of until the equilibrium ₂ composition was reached. In the U-Nb-Ti and U-Nb-V systems, alpha and /sub 2/ were coprecipitated. Annealing at 550 and 600/sup o/C produced decomposition products which, in most materials, originated at the grain boundaries; a fine precipitate which initiated throughout the matrix was observed at lower annealing temperatures. Increasing the niobium content resulted in greatly increased stability. The following elements added to a U-Nb base were found to retard transformation of the phase: zirconium, …

This is the final report on the progress, "A Wide-Range Neutron Detector and Monitoring Instrument," ARF 1118-6. This report covers activities from May 8, 1958 to May 8, 1959. This report describes the basic design principles of a proportional counter that has been constructed whose cathode diameter increases towards one end.

From introduction: "A detector system with the advantages of a liquid counter, but without the severe requirements on sample preparations, has been devised and is the basis of the present experimental investigation."