Alpha Particle Recoil Research Articles

Alpha-recoil track dating of Quaternary volcanics

Like fission-track dating, alpha-recoil track (ART) dating is based on the accumulation of nuclear particles that are released by natural radioactivity and produce etchable tracks in solids. ARTs are formed during the alpha-decay of uranium and thorium as well as of their daughter nuclei. When emitting an alpha-particle, the heavy remaining nucleus recoils 30–40 nm, leaving behind a trail of radiation damage. Through etching the ART tracks become visible with interference phase-contrast microscopy. Under the presupposition that all tracks are preserved since the formation of a sample their total number is a measure for the sample's age. The technique has already been proposed more than three decades ago [Huang, W.H., Walker, R.M., 1967. Fossil alpha-particle recoil tracks: a new method of age determination. Science 155, 1103–1106.], but due to inherent difficulties, it was hardly applied or made any substantial progress since then. The present paper describes a methodology by which reliable ART ages of dark mica can be obtained. The technique is applicable to tiny (∼0.5 mm) single mica flakes in the 10 2 to 10 6 years age-range. It is tested on Quaternary volcanics from the Eifel region, Germany. Alpha-recoil dating has a great potential for Quaternary chronometry and tephrochronology.

Modelling indoor exposure to natural radioactive nuclides

Radon enters buildings from several sources, principally building materials and the soil or rock that underlie or surround building foundations. The basic processes determining indoor concentrations are radioactive transmutations, attachment to aerosol particles, detachment by alpha particle recoil, plate-out on furniture and walls, and exchange with the outdoor air by natural or mechanical ventilation.

Consequences of Pauli effects in 6Li and the reaction 6Li(e,e'd)4He.

The reaction $^{6}\mathrm{Li}$(e,e'd${)}^{4}$He, carried out with quasifree kinematics, is ideally suited for mapping out the $^{6}\ensuremath{\rightarrow}\mathit{\ensuremath{\alpha}}+\mathrm{d}$ momentum distribution in the region where Pauli effects from the underlying ${S}_{1/2}$ \ensuremath{\alpha}N interaction are manifest. Data for the $^{6}\ensuremath{\rightarrow}\mathit{\ensuremath{\alpha}}+\mathrm{d}$ momentum distribution in the range of alpha-particle recoil momenta of 0.0 to 1.4 ${\mathrm{fm}}^{\mathrm{\ensuremath{-}}1}$ are important to understanding three-body models of $^{6}\mathrm{Li}$ in general and the ${S}_{1/2}$ \ensuremath{\alpha}N interaction in particular. In anticipation of $^{6}\mathrm{Li}$(e,e'd${)}^{4}$He coincidence measurements, the cross section is calculated with three-body models of $^{6}\mathrm{Li}$ under the assumptions of one-photon exchange and deuteron-pole dominance. The required kinematical conditions that make the theory applicable are emphasized.

The occurrence and behavior of radium in saline formation water of the U.S. Gulf Coast region

Radium has been measured in deep saline formation waters produced from a variety of U.S. Gulf Coast subsurface environments, including oil reservoirs, gas reservoirs and water-producing geopressured aquifers. A strong positive correlation has been found between formation-water salinity and Ra activity, resulting from the interaction of formation water with aquifer matrix. Ra isotopes enter the fluid phase after being produced by the decay of parent elements U and Th, which are located at sites on and within the solid matrix. Processes that are belived to be primarily responsible for transferring Ra from matrix to formation water are chemical leaching and alpha-particle recoil. Factors controlling the observed salinity—Ra relationship may be one or a combination of the following factors: (a) ion exchange; (b) increased solubility of matrix silica surrounding Ra atoms, coupled with a salinity-controlled rate of reequilibration of silica between solution and quartz grains; and (c) the equilibration of Ra in solution with detrial barite within the aquifer. No difference was found in the brine-Ra relation in water produced from oil or gas wells and water produced from wells penetrating only water-bearing aquifers, although the relation was more highly correlated for water-bearing aquifers than hydrocarbon-containing reservoirs.

234U and 238U concentration in brine from geopressured aquifers of the northern Gulf of Mexico basin

The 234U and 238U concentration in brine from six Gulf Coast geopressured aquifers has been determined. The results reveal very low uranium concentrations (from 0.003 to 0.03 μg/l) and uranium activity ratios slightly greater than unity (from 1.06 to 1.62). Reducing conditions within the aquifers are responsible for the low uranium concentrations. The uranium activity ratios observed are well below those calculated using theoretical considerations of alpha-particle recoil effects. This can be explained by interference with alpha-recoil nuclides entering the liquid phase as a result of quartz overgrowths on sand grains and high-temperature re-equilibration that tends to minimize the effects of the alpha-recoil process. The fact that the uranium activity ratios of the brines are slightly greater than unity instead of the equilibrium value of 1.000 indicates that either the alpha particle recoil blocking and re-equlibration effects are not complete or that another process is operative that enriches the fluid in excess 234U by selectively removing uranium from radiation induced damage sites in the mineral (sand grain) matrix.

Monte Carlo calculation of recoil spectra in 4He proportional counters

Monte Carlo techniques have been used to calculate alpha particle recoil spectra in 4He proportional counters, for incident neutron energies from 0.4 MeV to 14.0 MeV. Wall and end effects are treated explicitly. Effects of local counter inhomogeneities and external electronics are simulated by using a Gaussian distribution of the detector response in discrete energy groups. Calculated results are compared with measured recoil spectra.

Fission Track and Alpha-Particle Recoil Track Dating

During the past few years, considerable attention has been given to the possibility of dating by fission tracks and alpha-particle recoil tracks. In this paper, it was described the principle and application for Quaternary period. Ages of a few obsidians and old man made glasses were measured by the fission track method. The volcanic glass which was extracted from the deep sea core (V-20-130), was determined of its age and it was compared with the paleomagnetic result.According to the experimental result of this method, the difficulty and the usefulness wcre discussed