A Wall-Less Detector for Measuring Energy Deposition Spectra

Glass, W.A.; Braby, L.A.

doi:10.2307/3572663

Cited by 15 publications

(14 citation statements)

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“…Many papers have been written, and at least 11 symposia have been attended by eminent scientists who have devoted their lives to the study of energy deposition in microscopic volumes. However, despite the numerous studies conducted which concern the deposition of energy in microscopic volumes in space, no experimental studies have been found which take into account the deposition of energy in the time and spatial domain.…”

Section: Vlll I Introductionmentioning

confidence: 99%

Time-specific measurements of energy deposition from radiation fields in simulated sub-micron tissue volumes

Famiano¹

1997

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The fallacy of human memory renders it impossible to fully acknowledge those who have assisted in a work without creating invidious distinctions by failing to remember someone who has helped. However, a few individuals out of the many who have contributed to this paper are listed here.Dr. David Hamby has patiently worked with me throughout the course of the research leading to this paper. His deep understanding of the subject and immense patience with inane questions has made the work progress quite efficiently. As well, his sense of humor has kept me out of trouble on more than one occasion. In addition, the tickets to sporting events have provided a great amount of comfort to a cluttered mind. Hopefully, this compliment will not sound condescending, as I consider Dr. Hamby a giant in his field.Dan Hague and Jim Miller, two very good fiends of mine, have helped out tremendously. Dan, by providing me with equipment to complete the project, helped me progress through the stages of this research quite expeditiously, Jim, by allowing me to use his workshop and providing helpful suggestions, as well as allowing me to keep him awake while others slept, helped make a great deal of this research possible.Finally, I mention my gracious, loving wife, Nikki, to whom this work (as all my work) is dedicated. By surviving many nights without me, evenings of little conversation because of mypreoccupation with other things, complaints, and tedious tasks to help me complete this paper, she has shown me a new level of patience, understanding, and compassion. To compile the help she has been to me through the written word would require volumes. Her beauty shall endure long after this paper -or its memory -ceases to exist. vii ... List of Tables vlllABSTRACT A tissue-equivalent spherical proportional counter is used with a modified amplifier system to measure specific energy deposited from a uniform radiation field for short periods of time (-lys to seconds) in order to extrapolate to dose in sub-micron tissue volumes. The energy deposited during these time intervals is compared to biological repair processes occurring withiin the same intervals after the initial energy deposition. The signal is integrated over a variable collection time which is adjusted with a square-wave pulse. Charge fiom particle passages is collected on the anode during the period in which the integrator is triggered, and the signal decays quickly to zero after the integrator feedback switch resets; the process repeats for every "triggering" pulse. Measurements of energy deposited from x rays, "'Cs gamma rays, and electrons from a "SrPY source for various time intervals are taken. Spectral characteristics as a function of charge collection time are observed and frequency plots of specific energy and collection time-interval are presented. In addition, a threshold energy flux is selected for each radiation type at which the formation of radicals (based on current measurements) in mammalian cells equals the rate at which radicals ...

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Section: Vlll I Introductionmentioning

confidence: 99%

Time-specific measurements of energy deposition from radiation fields in simulated sub-micron tissue volumes

Famiano¹

1997

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“…Spectrum of specific energy for a parallel beam of a-particles. The dashed line is recalculated from measurements by Glass and Braby (1969) with a wall-less spherical proportional counter, the solid line was calculated using (9) that all a-particles crossing a circular shell only with thickness R6 and inner diameter 2r (Fig. 2) are causing low energy events with the above density.…”

Section: The Low Energy Componentmentioning

confidence: 99%

“…gl(z) = 2mo exp (-2moz) (1) m 0 is the mass of the target and 2 is a parameter, the value of which will be derived by comparison of the calculated spectra with the experimental spectra of Glass and Braby (1969) determined for 5.3 MeV a-particles by means of their so-called martini counter (Fig. 1).…”

Section: The Low Energy Componentmentioning

confidence: 99%

Specific energy spectra at alpha-contaminated bone surfaces

Polig¹

1983

Radiat Environ Biophys

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Spectra of specific energy f(z) in spherical and disc-shaped targets are determined for plane sources of alpha-particles. The radioactive plane is assumed to be coincident with bone surfaces or 'buried' within bone. Parameters determining energy straggling and the spectrum of delta-rays generated outside the target were determined from published parallel beam experiments with wall-less counters. An analytical procedure for calculating single and multiple event spectra for the sphere is demonstrated. For discs spectra are derived from Monte-Carlo calculations. In discs of 6.5 micrometers radius and 1 micrometer thickness adjacent to bone surfaces the mean specific energy per event is 2967 erg/g, while tht in a sphere of equal volume is 5247 erg/g. The relative variation of specific energy in the disc is about twice as large as in the sphere.

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“…This configuration will be discussed in the following section in connection with the V-efTect. 7 Private communication.…”

Section: V-effectmentioning

confidence: 99%

Event Simultaneity in Cavities: Theory of the Distortions of Energy Deposition in Proportional Counters

Kellerer¹

1971

Radiation Research

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KELLERER, ALBRECHT ]\I. Event Simultaneity in Cavities. Theory of the Distortions of Energy Deposition in Proportional Counters.Radial. Res. 43, 216-233 (1971).The so-called wall effects are distortions of the statistics of energy deposition which occur in proportional counters even if the counting gas and the counter walls have the same atomic composition. The distortions are due to the density difference between walls and counting gas. The3 r consist in the simultaneity of particle passages which in the case of uniform density would occur separatel.y. For heavy particles the delta-ray effect is dominant, but the V-effect can be significant at very high energies of the primary particles. In the case of x-rays, 7-rays, and fast electrons the distortions are due to the reentry, or backscattering, effect. Numerical estimates for the extent of the different processes and the corresponding change of mean event size and of event frequency are given.

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A Wall-Less Detector for Measuring Energy Deposition Spectra

Cited by 15 publications

References 1 publication

Time-specific measurements of energy deposition from radiation fields in simulated sub-micron tissue volumes

Time-specific measurements of energy deposition from radiation fields in simulated sub-micron tissue volumes

Specific energy spectra at alpha-contaminated bone surfaces

Event Simultaneity in Cavities: Theory of the Distortions of Energy Deposition in Proportional Counters

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