Radiobiological shot noise explains Three Mile Island biodosimetry indicating nearly 1,000 mSv exposures.

The 1979 accident at the Three Mile Island nuclear power station in Pennsylvania released about 22 million Curies of xenon-133 into the environment. Because physical dosimetry indicated exposures to the nearby population of less than about 2 mSv, discernible impacts to the health of the exposed population are not generally believed to have resulted. However, there is contrary evidence, including especially the results of biodosimetry via cytogenetic analysis using the FISH method. This report examines the discrepancy between the results of physical dosimetry and biodosimetry, which among the small number of persons examined indicated exposures between 600 and 900 mSv. The paradox reveals a fundamental error in the health physics body of knowledge: the definition of the energy imparted to tissue, ε, fails to properly account for the temporal distribution of ionization products resulting from dilute contamination with an internally incorporated beta-emitting radionuclide. Application of a century-old result describing "shot noise" in an electronic system repairs the deficiency. The Xe-133 concentration in the tissue of those individuals exposed to the most intense portion of the radioactive plume released from the TMI facility is shown to have been on the order of 0.1 µCi/l, persisting for multiple hours. Shot noise reference doses in the range from 820 to 1,700 mSv follow, a result which is consistent with biodosimetric analysis. The finding should motivate a comprehensive re-evaluation of the conventional understanding of the 1979 accident at the Three Mile Island nuclear power station, especially regarding its impact upon the population of the surrounding area.

Shot Noise Explains the Petkau 22Na+ Result for Rupture of a Model Phospholipid Membrane.

The action of free radicals is believed responsible for much or most biological injury resulting from exposure to ionizing radiation. These molecules in solution possess short lifetimes on the order of nanoseconds to microseconds. As a result, the dose-which measures the energy dissipated in tissue due to radiolysis-should not be considered a reliable indicator of the free radical concentration, nor of the chemical effects that follow from it. Rather, the chemical state of affected tissue is properly represented only by the dissipated power, which describes the distribution of energy with time. The present report demonstrates the validity of this assertion using data contained in a report describing a benchtop experiment published in 1972. The experiment used the visible rupture of a model phospholipid membrane as a means to quantify the degree of chemical insult caused by ionizing radiation. The experiment found that beta doses in the range from 1-10 rad were equivalent to x-ray rupture doses of 3,500 rad. This report demonstrates that the experimental results are convincingly explained by reference to the properly calculated time-averaged dissipated power due to beta decay. The theoretical explanation is derived by analogy to a well-understood result from electronic systems known as shot noise. If the result described in this report is demonstrated to extrapolate from the benchtop to living systems, then it is likely that exposure to beta radiation via internal incorporation is far more hazardous than commonly believed. The finding could be revolutionary in the field of health physics.

Lynx x-ray microcalorimeter.

Lynx is an x-ray telescope, one of four large satellite mission concepts currently being studied by NASA to be a flagship mission. One of Lynx's three instruments is an imaging spectrometer called the Lynx x-ray microcalorimeter (LXM), an x-ray microcalorimeter behind an x-ray optic with an angular resolution of 0.5 arc sec and ∼2 m2 of area at 1 keV. The LXM will provide unparalleled diagnostics of distant extended structures and, in particular, will allow the detailed study of the role of cosmic feedback in the evolution of the Universe. We discuss the baseline design of LXM and some parallel approaches for some of the key technologies. The baseline sensor technology uses transition-edge sensors, but we also consider an alternative approach using metallic magnetic calorimeters. We discuss the requirements for the instrument, the pixel layout, and the baseline readout design, which uses microwave superconducting quantum interference devices and high-electron mobility transistor amplifiers and the cryogenic cooling requirements and strategy for meeting these requirements. For each of these technologies, we discuss the current technology readiness level and our strategy for advancing them to be ready for flight. We also describe the current system design, including the block diagram, and our estimate for the mass, power, and data rate of the instrument.