Synthesis of Bulk Amounts of Double-Walled Carbon Nanotubes

65196 By accurately measuring average beam currents in a nuclear physics accelerator facility, particle loss mechanisms can be diagnosed. A non-intercepting detector for beam current measurements, with ultra-high precision and ultra-large dynamic range, is needed for this application. This project will develop a non-intercepting beam-current detector, based on a frequency-modulated digital SQUID, with quantum mechanical accuracy and 109 dynamic range, capable of detecting a 10 nA current variation following a 10 A bunch current pulse, without any subranging. Ultimately, a modular, digital, and programmable current detector for use in a wide variety of beam diagnostic applications will be developed. In Phase I, improvements will be made to an existing frequency-modulated digital SQUID design to integrate the beam current detector with superconducting circuits for ultra-high precision and ultra-high dynamic range. An ultra-low-noise front end will be developed. The system requirements, hardware modularization, low-noise pickup coil design, room-temperature interface hardware, digital coding, and signal reconstruction hardware, will also be examined. Commercial Applications And Other Benefits as described by awardee: The digital beam-current detector should provide unprecendented dynamic range, superb sensitivity, and ultra-high precision, while producing digital outputs that can be processed with simpler, inexpensive electronics. It should not only satisfy beam current detection requirements, but also enable other future measurements, such as direct measurement of polarization for nuclear physics and gate current noise diagnosis for the semiconductor industry. The detector could also be used to measure magnetic field, and could replace present-day analog SQUID magnetometers used for biomagnetic measurements, by offering superior performance at a lower cost.