Results of an experiment to measure muonic transition energies in separated lead isotopes are presented. The main results are as follows: 1. Muonic spectra of the four lead isotopes $^{204}\mathrm{Pb}$, $^{206}\mathrm{Pb}$, $^{207}\mathrm{Pb}$, and $^{208}\mathrm{Pb}$ were studied with high resolution. No anomalous splitting or broadening of the lines was detected. The effect of the natural linewidth could, however, be observed. 2. An anomaly was found in the $3d$ fine structure splitting whose measured value turned out to be larger than the calculated value by nearly 300 eV (or 10 standard deviations) in all four isotopes. 3. Except for this anomaly, the lower levels of muonic lead can be described adequately with the help of a two-parameter Fermi distribution of the nuclear charge. There is no evidence in the x-ray data for a central depression in the nuclear density. 4. We determine the nuclear polarization in the ground state of all four isotopes of lead and find values ranging from -7.3 \ifmmode\pm\else\textpm\fi{} 2.2 to -10.1 \ifmmode\pm\else\textpm\fi{} 1.1 keV, which are somewhat higher than, but not inconsistent with, the best theoretical predictions of -6.8 \ifmmode\pm\else\textpm\fi{} 2.0 keV. This analysis is made possible by our ability to measure the weak transitions involving the $2s$ level. 5. We find a slight and regular increase in nuclear density, going from $^{204}\mathrm{Pb}$ to $^{208}\mathrm{Pb}$. The skin-thickness parameter $t$ appears, however, to be practically the same in all four isotopes measured.RADIOACTIVITY $^{204}\mathrm{Pb}$, $^{206}\mathrm{Pb}$, $^{207}\mathrm{Pb}$, $^{208}\mathrm{Pb}$; muonic atoms, measured transition energies, levels up to $6f$; observed natural linewidth of $L$ lines; observed anomalous $\mathrm{fs}$ splitting of $3d$; deduced Fermi parameters; deduced nuclear polarization of ground state.
The availability of intense x-rays from synchrotron radiation sources permits the elemental analysis of samples in new ways. An x-ray microprobs using these sources allows the analysis of much smaller samples with greatly improved elemental sensitivity. In addition to the higher x-ray intensity obtained at synchrotron sources, the development of high efficiency x-ray reflectors using multilayer coated optical mirrors permits the achievement of spot sizes of less than 10 μm x 10 μm with enough x-ray intensity to simultaneously measure femtogram quantities of many elements in less than one minute. Since samples to be studied in an x-ray microprobe do not have to be placed in a vacuum, almost any sample can be conveniently analyzed. With an x-ray microprobe it is possible to obtain elemental distributions of elements in one, two or even three dimensions.
The intense synchrotron radiation produced at electron storage rings provides a new source of X-rays highly suited to iodine K-edge digital subtraction angiography. The high intensity and small angular divergence permit the radiation to be monochromatized by Bragg diffraction and made available in beams of small vertical size, of arbitrary horizontal width, and of tunable energy. The use of such beams provides maximum sensitivity to intra-arterial iodine and virtually eliminates image contrast due to non-vascular body structures. The sensitivity of this method to iodine offers the prospect of visualizing arteries by peripheral venous injection.
Differential cross sections for $\mathrm{dp}$ elastic scattering from 60\ifmmode^\circ\else\textdegree\fi{} to 175\ifmmode^\circ\else\textdegree\fi{} center of momentum (c.m.) were measured at 3.43, 4.50, 5.75, and 6.60 $\frac{\mathrm{GeV}}{c}$ incident deuteron momentum. The measurements were made with a two-arm magnetic spectrometer, making use of multiwire proportional chamber detectors. The deuterons were accelerated at the Bevatron of the Lawrence Berkeley Laboratory. Data are compared with predictions of the baryon-pickup model and the one-pion-exchange model. The backward dip at 180\ifmmode^\circ\else\textdegree\fi{} c.m. for 4.5 $\frac{\mathrm{GeV}}{c}$, predicted by Craigie and Wilkin using the one-pion-exchange model, is not observed, but reasonable fits to the momentum variation and angular distributions are found. When the data are plotted against the variable $\ensuremath{\Delta}$ of the baryon-pickup model, the $s$ dependence is greatly reduced.
The authors have performed studies on multicrystalline silicon used for solar cells in the as-grown state and after a series of processing and gettering steps. The principal goal of this work is to determine the rate limiting step for metal impurity gettering from multicrystalline silicon with an emphasis on the release of impurities from structural defects. Synchrotron-based x-ray fluorescence mapping was used to monitor the release process. Copper and nickel impurities were found to reside primarily at dislocations in the as-grown state of the material. Short annealing treatments rapidly dissolved the impurity agglomerates. Based on these results and modeling of the dissolution process, copper and nickel is in the form of small agglomerates (< 10 nm) clustered together over micron-scale regions in the as-grown material. Aluminum gettering further disintegrated the agglomerates to below the sensitivity of the system, 2--5 nm in radii. No significant barrier to release of copper or nickel from dislocations was observed.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTResonant Raman scattering as a source of increased background in synchrotron excited x-ray fluorescenceJoseph M. Jaklevic, Robert D. Giauque, and Albert C. ThompsonCite this: Anal. Chem. 1988, 60, 5, 482–484Publication Date (Print):March 1, 1988Publication History Published online1 May 2002Published inissue 1 March 1988https://pubs.acs.org/doi/10.1021/ac00156a022https://doi.org/10.1021/ac00156a022research-articleACS PublicationsRequest reuse permissionsArticle Views81Altmetric-Citations16LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
A rotating slit system has been designed and tested which can effectively translate a fan-shaped X-ray beam at the same average speed and in the same direction of travel as a patient moving continuously during a line-scan dual-energy medical imaging procedure. The slit has been shown to eliminate the artifacts due to bone in logarithmically subtracted images obtained with monochromatic X-ray beams derived from synchrotron radiation, where one beam is just above and the other just below the K-edge of iodine. Images of iodine-containing phantoms and in vivo canine images after intravenous iodine injection show vessel detail without artifacts due to bone. Corresponding images taken without the rotating slit have severe artifacts.
