PubMed Health⌕ Search

Biomedical subjects

V P Pease

Publications and source records attributed to V P Pease.

10 recordsLinked to original sources
PubMed1978

Visual phenomena induced by relativistic carbon ions with and without Cerenkov radiation.

Exposing the human eye to individual carbon ions (6C+) moving at relativistic speeds results in visual phenomena that include point flashes, streaks, and larger diffuse flashes. The diffuse flashes have previously been observed by astronauts in space but not in laboratory experiments with particles of high atomic number and energy. They are observed only when the nucleus moves fast enough to generate Cerenkov radiation.

Carbon↗
PubMed1977

Comparison of the light-flash phenomena observed in space and in laboratory experiments.

Astronauts on Apollo and Skylab missions have reported observing a variety of visual phenomena when their eyes were closed and adapted to darkness. These observations were studied under controlled conditions during a number of sessions on board Apollo and Skylab spacecraft and the data available to date on these so-called light flashes are in the form of descriptions of the phenomena and frequency of occurrence. Similar visual phenomena have been demonstrated in a number of laboratories by exposing the eyes of human subjects to beams of neutrons, alpha particles, pions and protons. More than one physical mechanism is involved in the laboratory and space phenomena. No direct comparison of the laboratory and space observations has been made by observers who have experienced both. However, the range of visual phenomena observed in the laboratory is consistent with the Apollo and Skylab observations. Measured detection efficiencies can be used to estimate the frequencies with which various phenomena would be observed if that subject was exposed to cosmic rays in space.

Cosmic Radiation↗
PubMed1976

Muon-induced visual sensations.

The visual phenomena induced by the passage of a pulse of extremely relativistic muons through the vitreous humor have been studied at the Alternating Gradient Synchrotron at Brookhaven National Laboratory. The visual phenomena include flashes that range from small crescents of light in the peripheral field of view to large clouds of light that fill the entire field of view as well as bright flashes with dark centers. Three subjects have been exposed to date. Arguments are given to show that the physical mechanism behind these flashes is Cerenkov radiation. Standard psychophysical techniques are used to determine the threshold for muoninduced visual sensations for one subject. Comparison is made with his pion treshold measured under the same condition.

Elementary Particles↗
PubMed1976

Role of Cerenkov radiation in the eye-flashes observed by Apollo astronauts.

Visual phenomena in the form of colorless flashes of light were observed by astronauts in deep space when their eyes were closed and adapted to darkness. We describe in this paper laboratory experiments and calculations which indicate that many of these flashes are the result of visible light generated within the astronauts' eyeball in the form of Cerenkov radiation when a relativistic HZE particle traverses it. The sensitivity to Cerenkov radiation measured for three subjects exposed to pulses of pions and muons and the visual phenomena observed were found to be consistent with the reports of flashes observed at rates as high as 2 per minute on Apollo missions 11 through 17.

Cosmic Radiation↗
PubMed1975

Visual sensations induced by Cerenkov radiation.

Pulses of relativistic singly charged particles entering the eyeball induce a variety of visual phenomena by means of Cerenkov radiation generated during their passage through the vitreous. These phenomena are similar in appearance to many of the visual sensations experienced by Apollo astronauts exposed to the cosmic rays in deep space.

Dark Adaptation↗
PubMed1972

Visual sensations induced by relativistic nitrogen nuclei.

The ability of the human eye to detect nitrogen nuclei that enter the retina at speeds just above the Cerenkov threshold has been confirmed in an experiment at the Princeton Particle Accelerator. A system for beam transport and subject alignment delivered individual nitrogen nuclei onto a spot 3 millimeters in diameter on the retina at a visual angle of 7 degrees on the temporal side of the fovea. The beam particles entered the retina within 25 degrees of normal and induced visual sensations that had the appearance of streaks for three out of four subjects.

Dark Adaptation↗