In an experimental program recently completed at the 184-inch synchrocyclotron in Berkeley, data were obtained on elastic {pi}{sup +}-p scattering at a laboratory energy of 310 Mev. Quantities measured were the differential cross section, the total cross section, and the polarization of the recoil protons as a function of center-of-mass angle. We have analyzed the data in terms of S, P, and D waves and have obtained only one acceptable solution. The resultant set of phase shifts is of the Fermi type. The D-wave phase shifts are small but definitely needed to obtain an adequate fit to the data. Owing to the relatively high accuracy of the cross-section data and the inclusion of the results of the polarization experiment, the errors on the small phase shifts have been reduced to less than 1{sup 0}. The differential cross-section and polarization data are given in Tables I and II.

When particle physics is a closed subject which has been condensed into a text book, the material will surely be organized by concepts and not according to what fact was learned on what accelerator. But short of that day facilities must be designed, planned, and developed, and experiments must be executed on one of a number of available accelerators; and a very necessary point of view is to ask what physics can be done with one facility, in contrast to another. It is in this spirit that, in this note, we look at electron colliding beam devices. In the first section we discuss the physics that can be done with colliding electron beams. After some general remarks we review the experiments already performed, and then turn to experiments planned for the future. The physics that can be done with any accelerator is a strong function of the physics of the accelerator. Every reader of this Journal knows what determines the energy of an accelerator, but the physics that determines the beam intensity, quality, and pulse length is perhaps not so well known. In fact, we plan to devote a future Comment to the physics that limits the performance of conventional …

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The discovery of neutral currents in neutrino interactions has made necessary the recalculation of the neutrino flow during stellar collapse. Neutral currents cause a coherent scattering cross section of complex nuclei proportional to the square of the atomic weight. This allows neutrinos to escape easily from the hot, dense center where only free baryons exist. The neutrinos then interact strongly in the outer region of high atomic weight and, under certain circumstances, produce a supernovae-like explosion in the outer reaches of the star, leaving a neutron star behind. For an explosion to occur, the scattering in the envelope of heavy nuclei must be greater than the scattering of the free baryons in the core. In particular, with Friedman's interpretation of Weinberg's theory, the cross section ratio is insufficient to produce an explosion. Other theories state that suppressing the free baryon cross section does lead to an explosion. (auth)

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Helium in very low concentration (less than 1 atomic ppB) has been introduced into type 304 stainless steel by radioactive decay of dissolved tritium. Release of this helium during subsequent annealing was monitored with a high sensitivity mass spectrometric gas analyzer. With isochronal annealing, helium is released in two temperature ranges, one near 300$sup 0$C and the other between 800$sup 0$C and the melting point. The latter release is interpreted as attributable to helium gas bubbles. The release near 300$sup 0$C was studied isothermally between 150 and 300$sup 0$C and is analyzed in terms of two stages of exponential decay. The fast and slow release stages have relaxation times near 10$sup 2$ and 10$sup 3$ s, respectively, and the fast release accounts for roughly 85 percent of the total release at low temperature. From an analysis of the temperature dependence of the release rate, it is concluded that volume diffusion is the controlling mechanism for the outgassing. (auth)

All major plasma diagnostic measurements from the 2XIIB experiment are recorded, digitized, and stored by the computer data acquisition system. The raw data is then examined, correlated, reduced, and useful portions are quickly retrieved which direct the future conduct of the plasma experiment. This is done in real time and on line while the data is current. The immediate availability of this pertinent data has accelerated the rate at which the 2XII personnel have been able to gain knowledge in the study of plasma containment and fusion interaction. The up time of the experiment is being used much more effectively than ever before. This paper describes the hardware configuration of our data system in relation to various plasma parameters measured, the advantages of powerful software routines to reduce and correlate the data, the present plans for expansion of the system, and the problems we have had to overcome in certain areas to meet our original goals. (auth)

The uniformity of wire characteristics is vital to the reliable long- time operation of the titanium alloy wire. Of particular importance is the diameter, total emissivity, and alloy mix. The getter wire must be operated at a minimum rate while the life is determined by the maximum rate. At a particular current the difference between the maximum and minimum rate is determined by variations in wire characteristics. Small percentage variations in these characteristics can result in large variations in gettering rate. (auth)

The original manual control system for the 12 neutral beam injectors on the 2XIIB Machine is being integrated with a computer control system. This, in turn, is a part of a multiple computer network comprised of the three computers which are involved in the operation and instrumentation of the 2XIIB experiment. The computer control system simplifies neutral beam operation and centralizes it to a single operating position. A special purpose console utilizes computer generated graphics and interactive function entry buttons to optimize the human/ machine interface. Through the facilities of the computer network, a high level control function will be implemented for the use of the experimenter in a remotely located experiment diagnositcs area. In addition to controlling the injectors in normal operation, the computer system provides automatic conditioning of the injectors, bringing rebuilt units back to full energy output with minimum loss of useful life. The computer system also provides detail archive data recording. (auth)

A test stand is in operation at LLL for the purpose of developing techniques and obtaining design information which will be used to develop efficient neutral beams. The knowledge gained will be used in the design of a 200 kV neutral beam test stand scheduled for operation in CY 77. (auth)

A high-efficiency detector system developed especially for medical imaging has three specially cut Ge(Li) coaxial detectors (total volume 249 cm$sup 3$). At 122 keV, the peak efficiency is 93 percent of that of a 7.6 x 7.6 cm NaI (Tl) detector. Degradation of the paralleled energy resolution is avoided and resolution is improved by 35 percent over that of conventional output-summing techniques by gating the detector outputs. In effect this multiplexes them to a single line output. (auth)

Theoretical energy band structure calculations have been utilized to investigate several high-Z materials for potential use as ambient temperature radiation detectors. Using the pseudopotential technique, the band structure for HgI$sub 2$ has been determined and the effective masses of the holes and electrons have been estimated. Theoretical mobilities of the electrons and holes as a function of temperature have been computed for HgI$sub 2$ and CdTe and are compared to experimental data. (auth)

The focus lens design for the 20-beam SHIVA laser fusion facility involves considerations of uniform and normal pellet illumination. The resulting requirements dictate tailored beam intensity profiles and vacuum-loaded thin lenses.

An attempt is made to discuss systematics of new particles and their spectroscopy in a simple manner. The main emphasis is on charm and SU(4), weak decays of charmed mesons, hadronic masses, and charmonium. (SDF)

Two types of MOS detector arrays were used to sense directly patterns of soft x-rays, in the Lawrence Livermore Laboratory experimental laser-fusion program. A linear self-scanning photodiode array (SSPA) is used in a wave-length-dispersive spectrometer. A frame transfer charge-coupled device (CCD) facilitates the use of an x-ray microscope. Measurements and calculations of the x-ray sensitivity of these devices are presented. Their linearity and dynamic range are discussed, as well as data recovery systems for each detector. Experiences in using these devices to detect pulses of x-rays in laser-fusion experiments are described.

The continuum ..gamma..-ray spectrum following neutron emission in a (HI,xn) reaction consists of a high-energy tail, the statistical cascade, and a lower-energy bump, the yrast cascade, which contains most of the intensity and consists mostly of stretched E2 transitions. Thus, a good approximation to the average angular momentum carried by the ..gamma..-rays is 2N/sub ..gamma../-bar. Under favourable conditions, effective moments of inertia can be deduced for states up to the top of the ..gamma..-ray cascade. The maximum angular momentum in the cascades is probably limited by ..cap alpha..-emission for nuclei with A < 150 and by fission for those with A > 150. 17 figures.

The techniques of stepwise laser excitation were applied to obtain Ryberg series in the lanthanides and in uranium. The methods employed circumvent many of the experimental difficulties inherent in conventional absorption spectrosopy of these heavy atoms with very complex spectra. The Rydberg series observed have allowed the determination of accurate ionization limits. The values in eV are: Ce, 5.5387(4);Nd, 5.5250(6); Sm, 5.6437(10); Eu, 5.6704(3); Gd, 6.1502(6); Tb, 5.8639(6); Dy, 5.9390(6); Ho, 6.0216(6); Er 6.1077(6); U, 6.1941(5). A comparison of the f/sup n/s/sup 2/-f/sup n/s ionization limits as a function of n with theoretical calculations is made.

The absorption of intense laser light is found to be reduced when targets are irradiated by 1.06 ..mu..m light with long pulse widths (150-400 psec) and large focal spots (100-250 ..mu..m). Estimates of Brillouin scatter which account for the finite heat capacity of the underdense plasma predict this reduction. Spectra of the back reflected light show red shifts indicative of Brillouin scattering.