Radiation-Hardened Performance-Optimized I2L LSI
Experimental data and theoretical calculations are presented on the effects of neutron irradiation on I2L circuits. It is shown that neutron-induced degradation of I2L gate performance can be theoretically predicted with reasonable accuracy. Operation of custom designed I2L 32-bit serial shift registers to a neutron fluence level of 1 × 1014n/cm2 is demonstrated. Shift register data are also given from total dose gamma and transient upset radiation experiments with thresholds exceeding 3 × 106rads(Si) and 2 × 109rads(Si)/s, respectively.
Stable-Damage Comparisons for Neutron-Irradiated Silicon
Measurements of minority-carrier lifetime degradation have been made for neutron-irradiated silicon which permit the following stable-damage comparisons to be drawn: a) test vehicle (device vs. bulk material); b) material type (n-type vs. p-type); c) dopant density (data obtained for various resistivities); d) neutron energy (14-MeV vs. reactor); e) measurement technique (transient vs. steady-state); f) operating condition (data obtained over a wide injection-level range). Primary results of this study are the following: a) the 14-MeV-to-reactor stable damage ratio is insensitive to injection level for a given resistivity; b) measurements of the stable damage ratio were made for bulk silicon and solar cells of various resistivities and nearly all of the values obtained were in the range 2.3 ± 0.4; c) neutron damage constants for solar cells and bulk material of a particular resistivity are in reasonable agreement if comparison is made at the same injection ratio, provided that the ratio employed is high enough so that such comparisons are not affected by bulk trapping.
Proposed beam diagnostics instrumentation for the LANSCE refurbishment project
Presently, the Los Alamos National Laboratory is in the process of planning a refurbishment of various subsystems within its Los Alamos Neutron Science Center accelerator facility. A part of this LANSCE facility refurbishment will include some replacement of and improvement to existing older beam-diagnostics instrumentation. While plans are still being discussed, some instrumentation that is under improvement or replacement consideration are beam phase and position measurements within the 805-MHz side-coupled cavity linac, slow wire profile measurements, typically known as wire scanners, and possibly additional installation of fast ionization-chamber loss monitors. This paper will briefly describe the requirements for these beam measurements, what we have done thus far to answer these requirements, and some of the technical issues related to the implementation of the instrumentation.