Quantum imaging of spin states in optical lattices

We investigate imaging of the spatial spin distribution of atoms in optical lattices using non-resonant light scattering. We demonstrate how scattering spatially correlated light from the atoms can result in spin state images with enhanced spatial resolution. Furthermore, we show how using spatially correlated light can lead to direct measurement of the spatial correlations of the atomic spin distribution

Formation Times of Meteorites and Lunar Samples

This article summarizes research since the last detailed reviews of meteorite ages by Anders [1963] and Reynolds [1967]. Only crystallization ages based on parent-daughter isotopic relationships resulting from the decay of naturally occurring radioactive nuclei will be discussed. The basic principles and techniques for age determinations are discussed in many of the papers cited and, along with summaries of scientific results, in several recent books [Dalrymple and Lanphere, 1969; Doe 1970; Hamilton, 1965; Schaeffer and Zahringer, 1966; Faul, 1966]. However, developments in the field have made some of the material in the books obsolete

Lunar science: The Apollo Legacy

A general review of lunar science is presented, utilizing two themes: a summary of fundamental problems relating to the composition, structure, and history of the moon and a discussion of some surprising, unanticipated results obtained from Apollo lunar science. (1) The moon has a crust of approximately 60-km thickness, probably composed of feldspar-rich rocks. Such rocks are exposed at the surface in the light-colored lunar highlands. Many highlands rocks are complex impact breccias, perhaps produced by large basin-forming impacts. Most highlands rocks have ages of ∼3.9 × 10^9 yr; the record of igneous activity at older times is obscured by the intense bombardment. The impact rate decreased sharply at 3.8–3.9 × 10^9 yr ago. The impact basins were filled by flows of Fe- and, locally, Ti-rich volcanic rocks creating the dark mare regions and providing the strong visual color contrast of the moon, as viewed from earth. Crustal formation has produced enrichments in many elements, e.g., Ba, Sr, rare earths, and U, analogous to terrestrial crustal rocks. Compared with these elements, relatively volatile elements like Na, K, Rb, and Pb are highly depleted in the source regions for lunar surface rocks. These source regions were also separated from a metal phase, probably before being incorporated into the moon. The physical properties of the lunar mantle are compatible with mixtures of olvine and pyroxene, although Ca- and Al-rich compositions cannot be ruled out. Deeper regions, below ∼1000 km, are probably partially molten. (2) Lunar rocks cooled in the presence of a magnetic field very much stronger than the one that exists today, owing either to dynamo action in an ancient molten core or to an external magnetization of the moon. Lunar soil properties cannot be explained strictly by broken-up local rocks. Distant impacts throw in exotic material from other parts of the moon. About 1% of the soil appears to be of meteoritic origin. Vertical mixing by impacts is important; essentially all material sampled from lunar cores shows evidence of surface residence. The surface layers of lunar material exposed to space contain a chemical record of implanted solar material (rare gases, H) and constituents of a lunar atmosphere (^(40)Ar, Pb). Large isotopic fractionation effects for O, Si, S, and K are present. Physical properties of the surface layers are dominated by radiation damage effects. Lunar rocks have impact craters (≤1 cm) produced by microgram-sized interplanetary particles. The contemporary micrometeorite flux may be much higher than is indicated by the microcrater densities, indicating time variations in the flux. Particle track studies on the returned Surveyor camera filter first showed that the Fe nuclei were preferentially enhanced in solar flares

Measurement of the lunar neutron density profile

An in situ measurement of the lunar neutron density from 20 to 400 g/sq cm depth between the lunar surface was made by the Apollo 17 Lunar Neutron Probe Experiment using particle tracks produced by the B10(n, alpha)Li7 reaction. Both the absolute magnitude and depth profile of the neutron density are in good agreement with past theoretical calculations. The effect of cadmium absorption on the neutron density and in the relative Sm149 to Gd157 capture rates obtained experimentally implies that the true lunar Gd157 capture rate is about one half of that calculated theoretically

Solar composition from the Genesis Discovery Mission

Science results from the Genesis Mission illustrate the major advantages of sample return missions. (i) Important results not otherwise obtainable except by analysis in terrestrial laboratories: the isotopic compositions of O, N, and noble gases differ in the Sun from other inner solar system objects. The N isotopic composition is the same as that of Jupiter. Genesis has resolved discrepancies in the noble gas data from solar wind implanted in lunar soils. (ii) The most advanced analytical instruments have been applied to Genesis samples, including some developed specifically for the mission. (iii) The N isotope result has been replicated with four different instruments

Interpretation of Solar System Abundances Around the N = 50 Neutron Shell

New measurements [l] of CI chondrites for Ni-Ru show a high degree of smoothness of the odd-A solar system abundance curve (SSAC) through the region of the N = 50 closed neutron shell. The resolved s- and r-process peaks at the N = 82 and 126 neutron shells [2] are not apparent for the N = 50 region. Our data confirm the necessity for a single element 89Y SSAC peak, presumably of s-process origin. If the total SSAC is smooth but made of contributions from more than one nucleosynthesis process, then at least the major contributing processes must also have smooth abundance curves. Within errors, a smooths-process abundance (N,) curve can be drawn using N, from Beer and co-workers. For A= 75-85 there are strong "non-s" contributions which could be flat or show a shallow maximum at mass 79-81. (N-N,; suppressed scale). This maximum would be analogous to the "r-process" peaks at A = 129 or 195. The reason that the two-peak structure for N = 50 is not apparent in the total abundance curve is that the lower mass peak is relatively broad, leading to unresolved sand non-speaks in the total SSAC. The rise in the N-N, curve below mass 75 is probably an error in the theoretical N,, so the "non-s" peak is better defined than at first glance. Below mass 69 it is hard to separate the contributions of n-capture nucleosynthesis from the high-mass tail of the iron group nuclei, the origin of which is not well understood

Nucleosynthesis in the early history of the solar system

Nucleosynthesis in early history of solar syste

Origin of Thorium/Uranium Variations in Carbonaceous Chondrites

Thorium-, U-, and Pb-isotopic analyses of a wide variety of planetary materials show that Th/U ratio (by weight) varies from 3.5 to 4.2. It is generally believed that chondritic meteorites contain refractory lithophile elements in a relative proportions close to solar, i.e., CI chondrites [1]. Surprisingly, a number of analyses of different types of carbonaceous chondrites show a large (at least a factor of 3) scatter in Th/U measurements [2]. The widest spread in Th/U is observed in the most primitive materials, CI-type chondrites. Cosmochronological models rely on the precise knowledge of the average solar system Th/U, therefore it is important to achieve a better understanding of the actinide chemistry in chondrites, e.g., what causes the variations in Th/U ratio

Apatite Control of Choncritic Actinide Chemistry?

The solar system Th/U is regarded as about 3.7, and ratios close to this are directly measured in a wide variety of planetary materials. Consequently, given that chondritic composition is regarded as solar for refractory lithophile elements, it is surprising that some ordinary chondrites show high ratios (6-6.5). We set out to understand the origin and implications of these anomalies, first by establishing that we had samples of the anomalous material using high accuracy isotope dilution, ICPMS measurements ofTh/U. Our three samples of Glatton (L6) were not anomalous (Th/U from 3.71 to 3.84), but for 12, typically gram-sized, samples of Harleton (L6) we find a range of Th/U from 2.5 to 6, a greater range of Th/U in one meteorite than in all previous ordinary chondrite analyses. Moreover, Fig. 1 shows (l) the Th/U variations linearly correlate with 11 U, suggesting two component mixing; (2) other literature analyses follow the Harleton trend