Isotopes formed in the bombardment of {sub 33}As{sup 75} with 190 Mev deuterons range in atomic number up to 24 (or more) mass units lighter than As{sup 75}. Identification of these isotopes was based on chemical behavior and half-life determination. Relative yields have been calculated and show that 80% of the observed reactions produce isotopes within 8 mass units of As{sup 75}. Three new isotopes have been observed: 9.5 d. Se{sup 72} (K), 44 m, Se{sup 71} ({beta}{sup +}), and 52 m, As{sup 71} ({beta}{sup +}).

From 19th International Union of Pure and Applied Chemistry Congress, London. A systematic introduction is presented to the subject of the variation with pH of the polarographic half-wave potential, which is probably the most readily measured electrochemical energetic parameter of organic compounds. Emphasis is placed on (a) the types of relationships observed for both reversible and irreversible electrode processes, (b) the mathematical formulation of these relationships, (c) the structural, mechanistic, kinetic, and environmental factors influencing such relationships, and (d) the presumptive physical causes for such relationships, e.g., the effect of pH on the electrochemical kinetics. Although the discussion is primarily concerned with behavior in aqueous solution, the conclusions drawn are equally valid for nonaqueous media in which hydrogen ion or some other Lewis acid can play a significant role. The half-wave potential for an organic electrode process may be independent of pH, or may vary lineanly or sigmoidally; other types of relationships observed are likely to be combinations of such effects. These variations may be due (a) to direct participation of hydrogen ion in the transition state involving the electroactive site in the organic molecule and the electron source, e.g., polarization of the bond to be broken, (b) to control …

The program KRUDE, which solves the slowing down and adjoint equations for a mixture of resonance and nonresonance isotopes in an infinite homogeneous medium, was used to evaluate some resonance capture approximations (variational and successive) that use linear combinations of narrow and wide resonance fluxes. Results obtained for resonance capture in the 291-ev resonance of Zr/sup 91/ and the 192-ev resonance of U/sup 238/ are compared, and three methods for including Doppler effects in the variational method are considered. (D.C.W.)

The nuclear age, which has been with us slightly more than 20 years, has brought with it an unusual awareness of a relatively new toxic agent--ionizing radiation. In fact, a new science, health physics, was created to give special attention to this problem. As a consequence and in spite of the unparalleled hazards associated with ionizing radiation, this new nuclear industry is growing rapidly into a benevolent giant bringing a better way of life while at the Same time maintaining radiation damage at an insignificant level. Although i n the past few decades we have learned much more about the hazards associated with ionizing radiation than those associated with some of the common industrial hazards and although maximum permissible exposure levels for the radionuclides have been established with greater reliability and confidence than have the levels for many chemical agents with which man has been familiar for many centuries, there still remains a considerable uncertainty in many of the basic assumptions and in the parameters used in the calculation of maximum permissible body burden and maximum permissible concentration of the various radionuclides in food, water and air. There is need to determine the uptake, distribution and elimination of a variety …

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Thermoluminescence dosimetry is the principal means of measuring ambient $gamma$ radiation at the Lawrence Livermore Laboratory. These dosimeters are used at 12 perimeter locations and 41 locations in the off-site vicinity of the Laboratory, and are exchanged quarterly. Control dosimeters are stored in a 75- mm-thick lead shield located out-of-doors to duplicate temperature cycling of field dosimeters. Effect of dosimeter response to radiation in the shield is determined each quarter. Calibration irradiations are made midway through the exposure cycle to compensate for signal fading. Terrestrial exposure rates calculated from the activities of naturally occurring uranium, thorium, and potassium in Livermore Valley soils vary from 3 to 7 $mu$R/hr. Local inferred exposure rates from cosmic radiation are approximately 4 $mu$R/hr. TLD measurements are in good agreement with these data. Off-site and site perimeter data are compared, and differences related to Laboratory operations are discussed. (auth)

A radiological survey of Bikini and Eneu Islands of the Bikini Atoll was conducted during June 1975 to assess the potential radiation doses that may be received by the returning Bikinians. Bikini Atoll was one of the U.S. nuclear weapons testing sites in the Pacific. An integral part of the survey included measurements of the gamma-ray exposure rates at 1 m above the ground with portable NaI instruments at nearly 2700 locations on the two islands. For comparison purposes, similar measurements were made with a pressurized ion chamber at approximately 200 locations, and with LiF and CaF$sub 2$:Dy thermoluminescent dosimeters (TLDs) at 80 locations. The results indicate that the NaI scintillators overresponded because of their nonlinear energy characteristics. The responses of the LiF dosimeters and the pressurized ion chamber agreed to within 13 percent. Attenuation studies with LiF TLDs indicated that roughly 25 percent of the total free air exposure rate at 1 m was due to beta radiation. (auth)

Albedo neutron dosimeters have proven to be effective as a method of measuring the dose from low-energy neutrons that other types of personnel neutron dosimeters do not detect. Many albedo neutron dosimeters have been designed, and some are being used extensively. All albedo neutron dosimeters are energy- dependent, becoming less sensitive as the energy of the neutrons is increased. In this paper the energy dependence and the effect it has on the evaluation of the dose are discussed. Numerous measurements are shown which were made under field conditions at five reactors, two accelerators, a radiochemistry facility, two plutonium facilities, a low-scatter neutron irradiation facility, three storage vaults, and at the N.B.S. low-energy neutron beams. These measurements show the limits imposed by the energy dependence on the evaluation of the dose determined by albedo neutron dosimeters. In most cases evaluation of an individual's dose occurring in a single facility can be reasonably accurate, but it must be known in which facility the person was exposed. Procedures using the incident thermal neutron response of TLDs located on top of the dosimeter to correct for the energy dependence are discussed; and errors caused by wearing a dosimeter improperly are evaluated. (auth)

The equilibrium constant, K/sub HDO/, for the reaction H/sub 2/O + D/sub 2/O = 2HDO can be expressed as an intensity ratio, I, measured mass spectrometrically, times a sensitivity ratio, S, measured in mass spectrometric calibration experiments. The latter is difficult to measure and previously was assumed to be unity. The 2.4 percent discrepancy between K's from theoretical calculations and direct mass spectrometric measurements might be explained by another value of S. An indirect measurement of S using a pulsed-molecular beam quadrupole mass filter that has a unique three-chamber, three-leak gas inlet system is reported. The results show the sensitivities are probably equal and therefore S = 1. Systematic errors were found in the procedure, however, which precluded an unambiguous test of the theory.

The absolute sensitivity for several different types of radiation detectors has been measured using x-rays in the energy range of 280 eV to 100 keV. The photons in this energy range are produced using three separate x-ray-generating facilities. The detectors include a silicon semiconductor, two photoelectric diode detectors employing aluminum and gold photocathodes, and three detectors incorporating plastic scintillators and photodiodes. The plastic scintillators were MEL-150C, Pilot B, and NE102.

The low momentum beam described is to be a unique source of antiprotons as well as kaons. The discussion covers (1) choice of production angle; (2) secondary beams; (3) the use of sector dipole magnets for minimizing aberrations; (4) beam bending magnets; (5) beam separators; and (6) beam acceptance. (PMA)