Ground-Based Evaluation of Dosimeters for NASA High-Altitude Balloon Flight

Results are presented from evaluations of radiation dosimeters prior to a NASA high-altitude balloon flight, the RaD-X mission. Four radiation dosimeters were onboard RaD-X: a Far West Hawk (Version 3), a Teledyne dosimeter (UDOS001), a Liulin dosimeter (MDU 6SA1), and a RaySure dosimeter (Version 3b). The Hawk is a tissue-equivalent proportional counter (TEPC) and the others are solid-state Si sensors. The Hawk served as the "flight standard" and was calibrated for this mission. The Si-based dosimeters were tested to make sure they functioned properly prior to flight, but were not calibrated for the radiation environment in the stratosphere. The dosimeters were exposed to 60Co gamma-rays and 252Cf fission radiation (which includes both neutrons and gamma rays) at the Lawrence Livermore National Laboratory (LLNL). The measurement results were compared with results from standard "benchmark" measurements of the same sources and source-to-detector distances performed contemporaneously by LLNL calibration facility personnel. For 60Co gamma rays, the dosimeter-to-benchmark ratios were 0.84 ± 0.06, 1.07 ± 0.32, 1.31 ± 0.07, and 0.82 ± 0.24 for the TEPC, TID, Liulin, and RaySure, respectively. For 252Cf radiation, the dosimeter-to-benchmark ratios were 0.94 ± 0.15, 0.55 ± 0.18, 0.58 ± 0.08, and 0.33 ± 0.12 for the TEPC, TID, Liulin, and RaySure. Some examples of how the results were used to help interpret the flight data are also presented

Ground-Based Evaluation of Dosimeters for NASA High-Altitude Balloon Flight

Results are presented from evaluations of radiation dosimeters prior to a NASA high-altitude balloon flight, the RaD-X mission. Four radiation dosimeters were onboard RaD-X: a Far West Hawk (Version 3), a Teledyne dosimeter (UDOS001), a Liulin dosimeter (MDU 6SA1), and a RaySure dosimeter (Version 3b). The Hawk is a tissue-equivalent proportional counter (TEPC) and the others are solid-state Si sensors. The Hawk served as the "flight standard" and was calibrated for this mission. The Si-based dosimeters were tested to make sure they functioned properly prior to flight, but were not calibrated for the radiation environment in the stratosphere. The dosimeters were exposed to 60Co gamma-rays and 252Cf fission radiation (which includes both neutrons and gamma rays) at the Lawrence Livermore National Laboratory (LLNL). The measurement results were compared with results from standard "benchmark" measurements of the same sources and source-to-detector distances performed contemporaneously by LLNL calibration facility personnel. For 60Co gamma rays, the dosimeter-to-benchmark ratios were 0.84 ± 0.06, 1.07 ± 0.32, 1.31 ± 0.07, and 0.82 ± 0.24 for the TEPC, TID, Liulin, and RaySure, respectively. For 252Cf radiation, the dosimeter-to-benchmark ratios were 0.94 ± 0.15, 0.55 ± 0.18, 0.58 ± 0.08, and 0.33 ± 0.12 for the TEPC, TID, Liulin, and RaySure. Some examples of how the results were used to help interpret the flight data are also presented

Aggregation dynamics in service overlay networks

This chapter is from the second edition of the Springer Handbook of Atomic, Molecular, and Optical Physics (2006), which is a comprehensive reference source that unifies the entire fields of atomic molecular and optical (AMO) physics, assembling the principal ideas, techniques and results of the field. 92 chapters written by about 120 authors present the principal ideas, techniques and results of the field, together with a guide to the primary research literature (carefully edited to ensure a uniform coverage and style, with extensive cross-references). Along with a summary of key ideas, techniques, and results, many chapters offer diagrams of apparatus, graphs, and tables of data. From atomic spectroscopy to applications in comets, one finds contributions from over 100 authors, all leaders in their respective disciplines. Substantially updated and expanded since the original 1996 edition, it now contains several entirely new chapters covering current areas of great research interest that barely existed in 1996, such as Bose-Einstein condensation, quantum information, and cosmological variations of the fundamental constants