*** 9623957 Singsaas/Penny This Small Business Innovation Research Phase II project addresses the need for improvements in the readout electronics for cryogenic radiation and particle detectors whic are being developed for diverse applications in astrophysics, particle detection, medical imaging, and materials science. Many of these devices use a superconducting quantum interference device (SQUID) for reading out the signal from the detector. The extreme sensitivity of SQUIDs to small changes in current, voltage or magnetic flux are essential for reaching the detection and resolution limits of the new detectors. Existing SQUID systems are often ineffectual or of limited usefulness in exploiting the full potential of these detectors due to limitations of bandwidth and slew rate, which make high count rate detection and pulse shape determination difficult or impossible. Recent work on high-speed SQUID electronics and improved sensors has shown that performance can be greatly improved not only in frequency response and slew rate, but also in stability, reliability and noise level. This will be a significant advance for cryogenic radiation and particle detector readout. The improvements will also aid in enabling laboratory for other industrial, military, and field use applications. SQUID technology to emerge out of the laboratory for other industrial, military, and field use applications. The technology developed here will significantly advance the use of do SQUID systems by providing the capability for measurements over a much wider range of frequencies, as well as in harsh environments where measurements were difficult or impossible to perform previously. Commercial applications benefiting from these advances include eddy current and biomedical instruments, ground-based or airborne magnetic anomaly detection, and airborn gravity gradiometers. ***