Dμ—A new concept in industrial low-energy electron dosimetry

Irradiation with low-energy electrons (100–300 keV) results in dose gradients across the thickness of the dosimeters that are typically used for dose measurement at these energies. This leads to different doses being measured with different thickness dosimeters irradiated at the same electron beam, resulting in difficulties in providing traceable dose measurements using reference dosimeters. In order to overcome these problems a new concept is introduced of correcting all measured doses to the average dose in the first micrometer—D_μ. We have applied this concept to dose measurements with dosimeters of different thickness at two electron accelerators operating over a range of energies. The uncertainties of the dose measurements were evaluated, and it was shown that the dose in terms of D_μ was the same at each energy for all dosimeters within the measurement uncertainty. Using the concept of D_μ it is therefore possible to calibrate and measure doses from low-energy electron irradiations with measurement traceability to national standards.     

A phase-stepped grating technique for frequency shifting in laser Doppler velocimetry

We demonstrate a novel approach to the moving grating technique for removal of velocity ambiguity in a laser Doppler velocimeter. The method replaces the continuous motion of a moving grating with a grating which can be positioned or switched to three distinct phase positions. Advantages of this approach are its potential for compact implementation and high stability of the velocity offset.     

3Acrylamido-3-methylbutyltrimethylammonium Chloride: A New Cationic Monomer

The monomer 3-acrylamido-3-methylbutyltrimethylammonium chloride was synthesized by two routes which differed in the first reaction of the synthetic sequence. Dimethylamino-methylation of isobutylene or dime thy lamination of isoprene gave intermediate amino-olefins which could be reacted with acrylonitrile in a Ritter reaction to yield 3-aerylamido-3-methylbutyldimethylamine. Subsequent quaternization with methyl chloride gave the subject monomer. The purity of the monomers from the two routes was found to differ greatly; however, extensively purified monomer was not necessary for high molecular weight polymer formation.     

Processing and properties of polysulfone hollow fibre membranes for gas separation filled with sub‐micron carbon fibres

Polysulfone hollow fibre membranes, of the type produced previously with enhanced gas separation properties, were filled with vapour grown carbon fibres (VGCF) of sub‐micron diameter. The effect of filler content on mechanical and gas permeation characteristics was studied. Hollow fibre membranes filled with up to 2.8 vol. % of VGCF were produced using forced convection dry jet/wet spinning. Fibre stiffness increased with increasing VGCF filler content. The fibres with the highest concentration of filler were about 30% more stiff than unfilled membranes. The addition of VGCF lead to a rise in permeability and some decrease in selectivity.     

Nuclear orbiting and anomalies in nuclear reactions

In this paper, we report our measurements of back-angle oxygen and carbon particle yields from ¹⁶O+⁸⁹Y, ¹²C+⁹³Nb reactions forming the same compound nucleus ¹⁰⁵Ag at the same excitation energy and spin distribution. We find anomalously large oxygen yield and entrance channel dependence at high excitation energies from ¹⁶O+⁸⁹Y reaction implying formation of a dinuclear orbiting complex. Possible connection between nuclear orbiting and fast fission is also discussed.     

3-Acrylamido-3-methylbutyltrimethylammoniumchlorid,ein neues kationisches Monomeres

Ohne Zusammenfassung     

Strain gages for long-term high-temperature strain measurement

The capabilities of resistance and capacitance strain gages for use in the temperature range of 1100–1400°F for durations up to 10,000 h are reviewed. Characteristics are given in summary and tabular form along with a list of references. Resistance strain gages offer some capability under these conditions, but the newer capacitance gages show promise for both laboratory and field use at high temperatures.     

Transient response of a central crack to a tensile pulse

This experimental investigation studies the opening displacement of a central electromachined slot in a thin aluminum plate subjected to an elastic tensile pulse. The tensile pulse was generated by an impact apparatus, and in-plane displacements were measured by interferometric technique. Comparison with existing analytical and finite-element solutions was good for short times.