Synthesis of a new class of highly fluorinated aliphatic diisocyanates

Synthesis is basis for preparation of polyurethanes that are compatible with liquid oxygen. The two step process preparation from fluorocarbon diacid fluorides is explained in text

Cryogenic loss monitors with FPGA TDC signal processing

Radiation hard helium gas ionization chambers capable of operating in vacuum at temperatures ranging from 5K to 350K have been designed, fabricated and tested and will be used inside the cryostats at Fermilab's Superconducting Radiofrequency beam test facility. The chamber vessels are made of stainless steel and all materials used including seals are known to be radiation hard and suitable for operation at 5K. The chambers are designed to measure radiation up to 30 kRad/hr with sensitivity of approximately 1.9 pA/(Rad/hr). The signal current is measured with a recycling integrator current-to-frequency converter to achieve a required measurement capability for low current and a wide dynamic range. A novel scheme of using an FPGA-based time-to-digital converter (TDC) to measure time intervals between pulses output from the recycling integrator is employed to ensure a fast beam loss response along with a current measurement resolution better than 10-bit. This paper will describe the results obtained and highlight the processing techniques used.Comment: 7 pp. 2nd International Conference on Technology and Instrumentation in Particle Physics 2011: TIPP 2011. 9-14 Jun 2011. Chicago, Illinoi

Dwarf nova oscillations and quasi-periodic oscillations in cataclysmic variables - VII. OY Carinae and oscillations in dwarf novae in quiescence

We have observed dwarf nova oscillations (DNOs) in OY Car during outburst, down through decline and beyond; its behaviour is similar to what we have previously seen in VW Hyi, making it only the second dwarf nova to have DNOs late in outburst that continue well into quiescence. There are also occasional examples of DNOs in deep quiescence, well away from outburst - they have properties similar to those during outburst, indicating similar physical causes and structures. We discuss the occurrence of DNOs in other dwarf novae and conclude that DNOs during quiescence are more common than often supposed and exhibit properties similar to those seen in outburst.Comment: Accepted for publication in MNRAS; paper contains 11 figures and 2 tables. This paper has become paper VII in the serie

The new AM CVn star in Hydra

High speed photometry of the new AM CVn star in Hya (previously known as SN2003aw), spectroscopically identified by Chornock & Filippenko, shows it to have a superhump period of 2041.5 +/- 0.3 s. We find a range of brightness from V ~ 16.5 to 20.3, presumably caused by variations in the rate of mass transfer. In the intermediate state the system cycles in brightness with a period of ~ 16 h and range >= 0.4 mag. There are sidebands to the principal frequencies in the Fourier transform which have constant frequency difference from the superhump harmonics.Comment: 5 pages, 6 figures. Accepted for publication in MNRA