The theoretical and practical aspects of the accelerating mode (TM01) in iris-loaded waveguides have been covered extensively in many reports and publications. The pulse shortening observed in linacs and the possible application of an iris-loaded waveguides as the deflecting structure for rf particle separators stimulated the interest in the nature of higher order modes. Some experimental results on higher order modes in iris-loaded waveguides are available in references. Results of studies done at CERN are not yet published; they were however communicated to the authors and represented the basis of work done at Brookhaven. A preliminary account of BNL results was given in reference. The purpose of this report is to describe the model measurements which were necessary to determine the geometry of a brazed or electroformed prototype for a deflecting waveguide. At the same time, a systematic investigation of other than the deflecting mode was done to ensure a nondegenerate field solution at the operating frequency. The measurements are compared with computational results obtained on the IBM 7090 at BNL.

The recently developed "n" on "p" type silicon solar cell has been evaluated for application as a high-level gamma radiation dose rate meter. The solar cell ionization current was found to be a linear function of dose rate in a range 10 2 to 10 7 rads per hour. A degradation rate of approximately one per cent per megarad was measured after stabilization with twenty megarads of cobalt-60 gamma radiation. The system has proven to be stable over long periods of time. Temperature dependence corrections have been found to be .0 per cent per degree centigrade between 0 and 60 degree centigrade.

Most existing electron synchrotrons use betatron start for initial acceleration of the particles. The subsequent synchrotron acceleration is then performed with a nearly constant radio-frequency. Investigation of the effect of turn-on rate and initial energy spread is made mathematically. Several advantages are seen for such a technique. (D.C.W.)

The descriptive parameters of a waveguide with smooth or periodic structure are most easily measured in a waveguide section of suitable length which is transformed into a resonant cavity by placing short circuits at both ends. Measurements of dispersion diagram, phase velocity, group velocity, voltage attenuation coefficient, shunt impedance, field configuration, etc. all involve some form of perturbation technique. The introduction of a perturbing object in a resonant cavity changes the stored electric energy We and magnetic energy Wm by Δwe and ΔWm' resulting in a frequency shift Δf of the resonant frequency f, which is given by the perturbation formula of J. Muller.

The Brookhaven Bubble Chamber Group is developing a Hough-Powell fast analysis system (HPD)1 for bubble chamber photographs. High precision measurements are made with a computer controlled flying spot digitizer. We are currently testing the track selection programs for the system. We have just completed a study of a method for automatic bubble density measurements.

The radiolysis of several polyaromatic compounds which might be used as coolant material in a reactor was investigated using both gamma and reactor radiation. The compounds selected were naphthalene, anthracene, naphthacene, pyrene, phenanthrene, 1, 2 benzanthracene, chrysene, triphenylene, 9, 10 dihydrophenanthrene, phenazine, 7, 8, benzoquinoline and m-phenanthroline, in addition to the uncondensed ring compounds, biphenyl, ortho, meta and para terphenyl and bibenzyl. Gas yields, percentage decomposition, percentage "high boiler" and number average molecular weights were determined. A correlation was found between radiation stability and electron affinity and singlet triplet excitation energies. The most stable compounds were the condensed ring compounds, naphthalene, pyrene, chrysene, phenanthrene and triphenylene.