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).

Studies of ionic entropies in methanol and ammonia have led to the suggestion that ionic entropies in water are abnormally high. An explanation of this hypothesis may be given in terms of entropies of solvation and the high degree of hydrogen bonding in water. When an ion enters water, more disorder is created than when it enters another, less hydrogen-bonded, solvent.

Radioactive decay data are used to calculate the atomic masses of the heavy isotopes, A> 203. The four radioactive families are then connected by means of neutron binding energies known from reactions on various isotopes. Finally all the masses are collectively adjusted for the best fit with mass spectrographic information available in this region. The masses so calculated are presented. Differences between masses of isotopes are estimated to have an of (plus/minus) 0.00020 mas units or about 200 Kev; the position of the masses taken collectively is in doubt by about 1.5 Mev.

Summary of progress on various research projects conducted during January, 1952.

The study was undertaken with the objective of observing the distribution in the rat of organic compounds of phosphorus labelled with the P32 isotope as tracer. The fate of several of these compounds was studied in animals bearing tumors. The distribution of inorganic phosphate in animal tissues is well known but was included in this work for comparison with the organic phosphorus compounds.

The question has arisen of how the beam in A-12 as a long resonant cavity might effect the frequency of operation and the field distribution. This study is published to make available the calculation of the direct beam effect as an illustration of general methods of attacking perturbing effects in resonant cavities.

The thermal decomposition of the higher oxides of praseodymium and americium have been investigated.

Five isotopes of bismuth occur in nature. Using particle accelerators providing helium ions up to 40 Mev in energy and deuterons up to 20 Mev in energy, it was possible to produce and identify two artificial radioactive isotopes. With the advent of the 184-inch Berkeley syncho-cyclotron and its hundreds of Mev energies, it was possible to form highly neutron-deficient bismuth isotopes extending more than ten mass units below stable Bi(209).

Equations are derived for the rates of heating of objects in induction furnaces and for the maximum temperatures attainable. The equations are primarily useful in designing conducting crucibles, shells, and cylinders so as to increase the power input and decrease heat losses. A very brief treatment is given of the factors which influence the current in the induction coil. The performances of various induction furnaces are compared.

The general method of controlling the radio frequency for the full scale Bevatron will be the same as that used on the 1/4 scale machine. The details of course will be modified to meet the requirements of greater range, higher output voltage and closer tracking tolerances. In addition, there is the added complication introduced by the current ripple.

Calculations presented were done to determine what maximum temperature gradients and stresses would be in typical designs of flat thorium plates, 100 mils thick and coolled on both sides by NaK.

Calculations indicative of the power loss for 75 in.radius gap splitters are given.

Recent underground nuclear tests conducted by the U.S. Atomic Energy Commission have yielded data on the effects of contained nuclear explosions in four rock mediums: tuff, alluvium, rock salt, and granite. This report presents and compares data obtained primarily through exploratory mining and drilling into the postshot environment of 35 such events.

In any underground nuclear explosion, the shock front that propagates from the shot point carries with it energy from the explosion, and distributes this energy by doing work on the surrounding material. In the process, the material undergoes changes in both its physical and mechanical states. If enough energy is deposited in the material, it will vaporize or melt thus changing its physical state, or cause it to crush or crack. During the past few years, special computer codes have been developed for predicting the close-in phenomena of underground nuclear explosions using the laws of physics, and the knowledge of the properties of the materials in which the detonations occur. As a consequence, a better understanding of experimental observations and measurements has evolved.

The effects of explosion-induced ground motion must be evaluated in planning and executing any nuclear excavation project. For some projects ground use intensity may dictate the use of less-than-optimum yields to minimize damaging effects. In remote areas, weighing the alternatives of outright purchase of some property or use of smaller yields may be required. The cost of indemnifying owners against damage must be considered in any case. Discussions of the effects of ground motion on three broad types of facilities - engineered structures, residential buildings, and equipment required for the support of nuclear excavation operations - are presented. A method of predicting the response of single- and multi-storied buildings, the response spectrum technique, is discussed, with emphasis on the application of explosion-induced spectra.

A fraction of the energy released by the underground detonation of nuclear explosives is locally deposited as residual thermal energy. An accurate prediction of this usable fraction of the energy released is necessary to evaluate the feasibility of several of the proposed projects in the Plowshare Program. This paper will present a summary of the available data on residual thermal energy from nuclear detonations in three different geological media: tuff, halite, and granodiorite.

The angle errors of a rotary table can be accurately measured by stepping off the angles with an optical caliper and computing table error from (1) the error readings at each angle measured and (2) the cumulative caliper error that will be evident when the circle is closed at 360', eliminating the necessity of adjusting the caliper to the exact setting.

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.

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.

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.

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.

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 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.