C. Milner

The observation of $\ensuremath{\Lambda}$-hypernuclear levels in $_{\ensuremath{\Lambda}}^{12}\mathrm{C}$ by associated production through the (${\ensuremath{\pi}}^{+}, {K}^{+}$) reaction is reported. The $_{\ensuremath{\Lambda}}^{12}\mathrm{C}$ excitation-energy spectra were recorded at laboratory scattering angles of 5.6\ifmmode^\circ\else\textdegree\fi{}, 10.3\ifmmode^\circ\else\textdegree\fi{}, and 15.2\ifmmode^\circ\else\textdegree\fi{}. They show two major peaks---one attributed to the ground state, and one about 11 MeV higher. These results are compared to the strangeness-exchanging (${K}^{\ensuremath{-}}, {\ensuremath{\pi}}^{\ensuremath{-}}$) reaction. The measured cross sections are compared to relativistic distorted-wave Born-approximation calculations.

As part of a program to develop a silicon strip central tracking detector system for the Superconducting Super Collider (SSC), the effects of radiation damage in silicon detectors and their associated front-end readout electronics are being studied. The authors report on the results of neutron and proton irradiations at the Los Alamos National Laboratory and gamma -ray irradiations at UC Santa Cruz. Individual components on single-sided AC-coupled silicon strip detectors and on test structures were tested. Circuits fabricated in a radiation-hard CMOS process and individual transistors fabricated using dielectric isolation bipolar technology were also studied. Bulk damage to the silicon itself is seen as the limiting factor in the lifetime of a detector system. In particular, it is the acceptor site creation in the active volume of the silicon detector that will limit the lifetime to approximately 10 yr for the innermost detectors.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

As part of a program to develop a silicon tracking device for the Superconducting Super Collider (SSC), radiation-hard CMOS transistors and p-i-n diodes have been exposed to the 800-MeV LAMPF (Los Alamos Meson Physics Facility) proton beam. The fluences accumulated in one week corresponded to the expected radiation levels of about ten SSC years. The leakage current constants for p-i-n diodes and threshold voltage shifts for CMOS transistors are determined under different biasing conditions. The results are presented and examined in detail.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Two changes in the circuit arrangement of a potentiometer as used for resistance measurements were found to reduce considerably troubles due to "residual E.M.F." The changes were: (1) breaking both battery circuits, instead of the galvanometer circuit, to test for balance; (2) making reduction of the battery potential by a fixed potential divider follow, instead of precede, that by the potentiometer box itself. Some points of practical significance are discussed.

Abstract The experiments of Kapitza (1929) showed that the increase of electrical resistance produced in a metal by a magnetic field H is not proportional to H2, as was previously supposed. In the new experimental range made available by his method (Kapitza 1927) of producing very strong fields up to 300 kilogauss, Kapitza found that the increase of resistance tended towards a linear variation with the field strength. The result may be expressed in the formula ΔR/R0 = b (H - Hk), for H ≫ Hk, where R0 is the resistance at 0° C. This gives the asymptote to the experimental curve: but if experiments are made at field strengths up to a maximum Hm, and Hm ≫ Hk, then over a large part of the experimental range the curve obtained is practically identical with the asymptote. If the linear part of the curve is then extrapolated back to meet the axis of H, its intercept on that axis gives the parameter Hk, and the slope of the line gives the parameter b. If, however, the maximum field used is only of the order of Hk, the linear variation is only reached outside the experimental range; and some formula must be employed, in effect, to extrapolate to the region where the linear law holds, before the position of the asymptote and the values of the parameters can be derived. It is obvious that the values so obtained will vary according to the particular formula adopted.