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Full-Text Articles in Physics
Track Physics Model Of Radiation Effects, Robert Katz
Track Physics Model Of Radiation Effects, Robert Katz
Robert Katz Publications
Radiation effects induced by heavy ions in many materials with diverse end points are well described by the conceptual structure and equations of track physics, first developed for heavy ion tracks in nuclear emulsions. The model describes scintillators, biological cell inactivation and mutation, radiation chemistry, latent tracks in insulators, the response of resists to heavy ions, and other systems. A detector is taken to be composed of small targets whose response to ionizing radiation is principally to secondary electrons. The response is calibrated through determination of the probability of target (in)activation as a function of the absorbed dose of γ …
A Track Physics Model Of Radiation Action, Robert Katz
A Track Physics Model Of Radiation Action, Robert Katz
Robert Katz Publications
A model of radiation action by energetic heavy ions, inspired by a study of particle tracks in electron sensitive emulsion, has been successfully applied to many radiation effects in condensed matter, yielding quantitative descriptions and occasional predictions. Radiation effects are attributed primarily to secondary electrons. Each detector is imagined to be a collection of targets whose radiosensitivity is represented parametrically. We avoid a mechanistic description of detector response so as to retain the global character of the model. Attention is focused on the structure of particle tracks, on the radial deposition of dose about an ion’s path by “δ-rays,” and …
Rbe Vs. Dose For Low Doses Of High-Let Radiations, Robert Katz, F. A. Cucinotta
Rbe Vs. Dose For Low Doses Of High-Let Radiations, Robert Katz, F. A. Cucinotta
Robert Katz Publications
(LET) radiations varies with cellular radiosensitivity parameters and the radiation environment. Of special interest is that the RBE varies as the dose of high-LET radiation to the power (1/m - 1) where /m is the “target number” parameter, which varies from 2-4 in different cell lines. This applies to neutrons as well as to heavy ions at sufficiently low doses such that cells are not activated in the γ-kill mode; that is, the tracks of single heavy ions are sufficiently far apart so that there are few cases of inter-track inactivation.
Comment On “Microdosimetry And Katz’S Track Structure Theory” By Marco Zaider, Robert Katz
Comment On “Microdosimetry And Katz’S Track Structure Theory” By Marco Zaider, Robert Katz
Robert Katz Publications
To test radiobiological models one needs data from X- or γ-ray and HZE track segment irradiations of the widest possible dynamic range in dose, LET, end points, and test objects (enzymes, viruses, bacteria, cells, tissues, organs, and organisms). Some data are currently available. There are excellent data on the inactivation of dry enzymes and viruses which should serve as a test of every biophysical model. On many occasions Zaider has asserted the superiority of microdosimetric over track structure models, asserting that “radial dose distributions (on which track structure theory is based) are generally poor substitutes for exact microdosimetric distributions.” I …
Biological Effectiveness Of High-Energy Protons: Target Fragmentation, Francis A. Cucinotta, Robert Katz, John W. Wilson, Lawrence W. Townsend, Judy Shinn, Ferenc Hajnal
Biological Effectiveness Of High-Energy Protons: Target Fragmentation, Francis A. Cucinotta, Robert Katz, John W. Wilson, Lawrence W. Townsend, Judy Shinn, Ferenc Hajnal
Robert Katz Publications
High-energy protons traversing tissue produce local sources of high-linear-energy-transfer (LET) ions through nuclear fragmentation. We examine the contribution of these target fragments to the biological effectiveness of high-energy protons using the cellular track model. The effects of secondary ions are treated in terms of the production collision density using energy-dependent parameters from a high-energy fragmentation model. Calculations for mammalian cell cultures show that at high dose, at which intertrack effects become important, protons deliver damage similar to that produced by γ rays, and with fragmentation the relative biological effectiveness (RBE) of protons increases moderately from unity. At low dose, where …
Radiation Risk Predictions For Space Station Freedom Orbits, Francis A. Cucinotta, William Atwell, Mark Weyland, Alva C. Hardy, John W. Wilson, Lawrence W. Townsend, Judy L. Shinn, Robert Katz
Radiation Risk Predictions For Space Station Freedom Orbits, Francis A. Cucinotta, William Atwell, Mark Weyland, Alva C. Hardy, John W. Wilson, Lawrence W. Townsend, Judy L. Shinn, Robert Katz
Robert Katz Publications
Risk-assessment calculations are presented for the preliminary proposed solar minimum and solar maximum orbits for Space Station Freedom (SSF). Integral linear energy transfer (LET) fluence spectra are calculated for the trapped-proton and galactic cosmic ray (GCR) environments. Organ-dose calculations are discussed using the Computerized Anatomical Man model. The cellular track model of Katz is applied to calculate cell survival, transformation, and mutation rates for various aluminum shields. Comparisons between relative biological effectiveness (RBE) and quality factors (QF) for SSF orbits are made, and fluence-dependent effects are discussed.
On The Normalized Yield (Events/Rad/Dalton) Of Biological Molecules Irradiated With Energetic Heavy Ions, Robert Katz
On The Normalized Yield (Events/Rad/Dalton) Of Biological Molecules Irradiated With Energetic Heavy Ions, Robert Katz
Robert Katz Publications
When irradiated with electrons or γ-rays, a number of biological molecules display an approximately linear relationship between the reciprocal of the D37 dose and molecular weight. This is conventionally plotted as a relation between target molecular weight and true molecular weight, where the target molecular weight Mt is given as: Mt × (D37) = α (1) where α is approximately 1010 Da-rad/eV of the energy assumed to be “deposited in the target” in a single “hit” for expression of the end-point. We emphasize that D37 is expressed in rads for we will later …
Cross Sections For Single And Double Strand Breaks In Sv-40 Virus In Eo Buffer After Heavy Ion Irradiation: Experiment And Theory, Robert Katz, S. Wesely
Cross Sections For Single And Double Strand Breaks In Sv-40 Virus In Eo Buffer After Heavy Ion Irradiation: Experiment And Theory, Robert Katz, S. Wesely
Robert Katz Publications
Measured cross sections after heavy ion bombardment, for both single and double strand breaks of SV-40 virus in EO buffer (which emphasizes indirect effects), are consistent with the theory of Butts and Katz for 1-hit detectors.
Cellular Track Model Of Biological Damage To Mammalian Cell Cultures From Galactic Cosmic Rays, Francis A. Cucinotta, Robert Katz, John W. Wilson, Lawrence W. Townsend, John E. Nealy, Judy L. Shinn
Cellular Track Model Of Biological Damage To Mammalian Cell Cultures From Galactic Cosmic Rays, Francis A. Cucinotta, Robert Katz, John W. Wilson, Lawrence W. Townsend, John E. Nealy, Judy L. Shinn
Robert Katz Publications
The quality factor (QF) as defined in International Commission on Radiological Protection report no. 26 (ICRP 26, ref. 1) or in International Commission on Radiation Units and Measurements report no. 40 (ICRU 40, ref. 2) is not expected to be a valid method for assessing the biological risk for deep space missions where the high-energy heavy ion (HZE) particles of the galactic cosmic rays (GCR) are of major concern. No human data for cancer induction from the HZE particles exist, and information on biological effectiveness is expected to be taken from experiments with animals and cultured cells (ref. 3). Experiments …
Radial Distribution Of Dose, Robert Katz, Matesh N. Varma
Radial Distribution Of Dose, Robert Katz, Matesh N. Varma
Robert Katz Publications
The radial distribution of dose about the path of a heavy ion, principally from delta rays, is one of the central contributions of atomic physics to the systematization of high LET radiation effects in condensed matter, whether the detection arises in chemical, physical, or biological systems. In addition to the radial distribution of dose, we require knowledge of the response of the system to X-rays or gamma-rays or to beams of energetic electrons such that the electron slowing-down spectra from these radiations can approximate the slowing-down spectra from delta rays even at different radial distances from the ion's path. A …