pucker, Phys. Rev. Lett. 16, 746 (1966).A number of experimental studies have been made of the momentum dependence of the total cross section for the reaction ir'p -AK° in the region of incident pion momentum extending from threshold up to and beyond that corresponding to the thresholds for H°K° and Z"if + production. 1 " 8 These studies have sought to clarify the mechanism for AK production near threshold, to search for new resonances, and to find evidence for the predicted cusplike behavior of the total cross section in the region of the UK thresholds. A limitation in previously published studies has been imposed by the uncertainty in the incident pion momentum, typically ±2%, which places a lower limit on the characteristic width of detectable structure of ~20 MeV/c. In the present experiment, the width of detectable structure in the momentum dependence of the total cross section for AK production is reduced to ±1 MeV/c by the use of a spark-chamber spectrometer in the incident pion beam. This apparatus, described elsewhere, 9 permits determination of the momentum of individual incident pions with a relative precision better than ±0.1 %, and with an absolute calibration obtained from kinematic event fitting near the A°K° and H°K° thresholds.

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The potential for latch-up, a pnpn self-sustaining low impedance state, is inherent in standard bulk CMOS-integrated circuit structures. Under normal bias, the parasitic C CR is in its blocking state but, if subjected to a large voltage spike or if exposed to an ionizing environment, triggering may occur. This may result in device burnout or loss of state. The problem has been extensively studied for space and weapons applications. Prevention of latch-up has been achieved in conservative design (~9 nm p-well depths) by the use of minority lifetime control methods such as gold doping and neutron irradiation and by modifying the base transport factor with buried layers. The push toward VLSI densities will enhance parasitic action sufficiently so that the problem will become of more universal concern. Th;s paper will survey latch-up control methods presently employed for weapons and SECOND DRAFT, 7/13/79-2space applications on present (-9 M"> p-well) CMOS and will indicate the extent of their applicability to VLSI designs.

A new design for radiation-sensing field-effect transistors (RADFETs) is presented, involving the use of very thick silicon nitride layers deposited on top of a high-quality thermal silicon dioxide. In contrast to previous RADFET fabrication procedures, no attempt was made to introduce hole traps into the thermal oxide. Instead the trapping layer at the nitride oxide interface was used to store the positive charge which forms the basis for operation of the RADFET. Data is presented which shows hole transport in the thermal oxide. Models explaining the field dependence of the response and the saturation behavior of the dual dielectric device are given. These RADFETs are more stable than any previously described in the literature and have a sensitivity of 86 μV/rad dose at room temperature.

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