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A liquid hydrogen target, containing 250 l of liquid hydrogen, with a ratio between the working space and the reservoir of 1.5:1, is described. A radiation shield cooled by evaporating gas is used to insulate the target. The diameter of the beam windows is 30 cm. Mean quantity of hydrogen along the beam is 14.35 g cm −2 , the amount of other matter along the beam is 0.75 g cm 2 , and across the beam is 2.75 g cm 2 . Uncertainty in target length is not more than 1.5%, liquid hydrogen evaporation is 5 litres per day, and operating time with refills is 20 days.

Nitrogen dioxide and its related compounds react strongly with ozone, usually resulting in the destruction of the ozone, and life seems to be delicately adjusted to the radiation shield which the stratospheric ozone provides. We have found that atmospheric NO2 occurs in two layers, described here, which have very different properties.

A commercially available vacuum automatic recording balance has been equipped with program control and furnaces so that it may be used for thermogravimetric studies. The complete system has been tested at pressures less than 0.1 mm Hg. Comparatively light‐weight furnaces are used. For convenience of operation, radiation shields take the place of the major part of the insulation.

A review is given of the development and use of kernel methods in solving problems of radiation shield design and radiation transport. Two classes of kernels are identified: empirical and computational. An analysis of the various techniques is made and examples are given. The relevant computer codes in the collection of the Radiation Shielding Information Center are listed and briefly described. It is concluded that kernel methods are valuable for quick estimates, hand calculations, checks of transport computer code results, and engineering parameter studies. However, the method can give underestimates for situations which the applied kernel cannot treat properly.

Air temperatures to altitudes as high as 100,000 feet have been measured with radiosondes carrying a temperature element which was exposed directly to solar radiation. The temperature element was coated with a special white paint which reflected more than 90 per cent of the solar radiation. Air temperatures measured with the white element should not be in error by more than 0.5C except at the highest altitudes. Air temperatures measured with radiosondes using an air duct for radiation shield were higher than temperatures obtained with the white element by 3–6C at 50,000 feet, by 5–10C at 75,000 feet and by as much as 20C at 100,000 feet. The results of a limited number of flights indicate that to altitudes of 100,000 feet, the heat wake of a balloon does not extend as far as 25 feet below the balloon.

An inexpensive, efficient radiation shield, for application in the atmospheric boundary layer, is described. Shield construction is suitable for the deployment of small resistive sensors, with bead thermistors being used here for the acquisition of both dry- and wet-bulb temperatures. Aspiration is not required if the shield is utilized in air flow exceeding 2 m sec−1. Spectral analyses of laboratory and field data show that temperature measurements are representative to within a few hundredths of a Celsius degree for fluctuations with periods as short as 6 sec. Conclusions are based on the simultaneous performance of two shields chosen arbitrarily from among those available in the array.

Construction details and experimental data are given for a total absorption calorimeter used for electron beams of several hundred MeV and for beam power up to 15 kW. In order to obtain high precision, precautions were taken to obtain very high heat insulation, specially by using a temperature controlled radiation shield. The heat loss of the 700 kg copper block corresponds to less than 10 −3 °C/h. Due to design calculations and confirmed by preliminary comparison tests with other beam monitors we consider the absolute accuracy to be 1% or probably better.

A method is given whereby one may graphically determine the radiation heat transfer properties of a number of closely packed radiation shields. The method uses the gray body formula, taking into account variations in total thermal emissivity of the adjacent shields as a function of temperature. Results were used in the construction of a high temperature vacuum furnace. Excellent correlation was found between graphically predicted and calorimetrically measured results.

A system for high-resolution measurement of air temperatures and temperature differences is described. This system is designed for routine field use in conjunction with high-quality data-processing equipment, and is designed to measure temperature differences to within 0.01C and temperature to within 0.05C. Platinum resistance sensing elements are used. Also described is a mechanically-aspirated radiation shield for use with these sensors.

A furnace is described for use with the electron diffraction camera for the study of chemical and physical reactions occurring on surfaces up to 1000°C. The specimens are mounted in the body of a 25 Cr‐12 Ni alloy block which is surrounded by a series of radiation shields. The metal block is heated internally by a tungsten‐wire heating element mounted on a BeO core and operates in a hydrogen atmosphere. The several motions necessary for manipulation of the specimens are accomplished through a Wilson seal. Temperatures of 1000°C are achieved with a heat input of the order of 450 to 500 watts in forty minutes. The use of the furnace is illustrated.

The designer of radiation shields is interested in an optimum selection and arrangement of shielding materials with respect to some optimization parameters as expenses, weight, thickness etc. This becomes very difficult because of the complicated nature of the attenuation process and the complex linkage between the shielding characteristics in the various materials. The problems of such calculations are so complicated that generally a complete solution is not possible. Since the beginning of shielding theory, many efforts have been made to derive simplified calculations for this purpose with which at least a first approximation of the optimum conditions can be achieved. All previous studies concerning this matter are collected and discussed with respect to their applicability.

The pressures of carbon monoxide in equilibrium with a Cr23C6-Cr2O3-Cr mixture and with a Cr7C3-Cr2O3-Cr23C6 mixture have been measured in the temperature range 1100 to 1300 K using the torsion-effusion technique. From the equilibrium data, the following equation for ΔGof of Cr23C6 (in cal per mole) has been calculated: ΔGf° (±1200) = −77,000 - 18.3T (1150 to 1300 K) Combining the results of this study at temperatures between 1100 and 1300 K with those of Kelleyet al.,3 at temperatures between 1500 and 1720 K, the following equation for ΔGof of Cr7C3 (in cal per mole) has been determined: ΔGf° (±400) = −35,200 - 8.7T (1100 to 1720 K) ) The above equation for ΔGof of Cr7C3 has been used to re-evaluate the equilibrium data of Kelleyet al.,3 and the following equation for ΔGof of Cr3C2 (in cal per mole) has been obtained: ΔGf° (±400) = −16,400 - 4.4T (1300 to 1500 K) CHROMIUM reacts with carbon to form three carbides:1,2 Cr23C6, Cr7C3, and Cr3C2. The chromium carbides are of considerable technical importance because of their precipitation behavior in certain high-chromium steels and superalloys. A precise knowledge of their thermodynamic properties is essential for the understanding and the prediction of their chemical behavior in various environments.

A small, rugged glass Dewar using a liquid nitrogen cooled metal shield is described. This Dewar is relatively inexpensive to construct and to modify, stores helium with only a moderate loss rate, and can be adapted for a wide variety of low temperature experiments. Two other Dewars, in which vapor‐cooled radiation shields replace liquid nitrogen cooled shields, also are described. Helium loss rates show that a liter of liquid helium will keep these Dewars at 4°K for about 5 to 10 hr.

Manufacturing procedures are Manufacturing procedures are given for a series of high-density sintered tungsten-nickel-copper and tungsten-nickel-iron alloys covering a density range of ∼17 g/cm3 to > 18·5 g/cm3.Physical and mechanical property data for these alloys are given and the effect of sintering variables on these properties is discussed.Reference is made to equipment and techniques employed in the manufacture of radiation shields to meet the most stringent demands brought about over the years by the increased strength of radiation sources and the widening scope for the application of artificial radioactive elements.

A cryogenic hydrogen target is described in which the hydrogen is in the form of a self-supporting cylinder of solid hydrogen, 1 cm diameter and 5 cm high. With large holes cut through the radiation shields to permit the unhindered passage of charged particle beams, useful target lifetimes of about three hours have been achieved.

A high temperature vacuum furnace is described which has been in almost continuous use during the past four years in the production from powders of sintered compacts of titanium and titanium alloys. The success which has attended its use has suggested that information regarding its design and operation might be of value to others working in the field of vacuum metallurgy. Although vacuum furnaces are technologically applicable to industry, economically they are applied only where other alternatives do not present themselves. This is mainly due to the present high cost of installation and operation. The main contributory factor to high cost, particularly with large furnaces, is degassing refractories. The problem is to reduce the amount of refractories which degas to a minimum. Two methods of doing this are discussed—one employs heat resistant alloy or metal within an insulated heated chamber—the other employs a refractory heater surrounded by an insulated radiation shield to protect the inner side of the insulated furnace wall. The furnace described herein was built to the latter design.