Bruce H. Kusko

Control of temperature in thin samples during ion beam analysis

Abstract The ability of ion beam analytical techniques such as proton induced X-ray emission (PIXE) to determine elemental content without damaging fragile objects is a key factor in their increasing use in the analysis of art and archaeological objects In this paper, we calculate the expected temperature rise in thin, planar samples with and without radiative, conductive and convective cooling The results show that the primary emphasis must be placed on minimizing energy input to the sample, and that forced convective cooling is by far the most effective method of energy removal in materials such as paper, parchment, and fabrics

Dating Rock Varnishes by the Cation Ratio Method with PIXE, ICP, and the Electron Microprobe

The measurement of rock varnish cation-ratios [(K+Ca)/Ti] and barium is evaluated by analyzing the same varnish scrapings with PIXE, inductively coupled plasma, neutron activation and wavelength dispersive electron microprobe. Results among these different methods are generally similar for ratios, but absolute concentrations differ in part due to uncertainties associated with weighing small samples. Barium concentrations are typically less than 1 % by weight; higher concentrations can be found in varnishes with depressions eroded into the varnish by fungi and lichens, and later infilled with aeolian detritus often including barium sulfate. Since these infilled hollows are known to produce anomalous varnish cation ratios, high barium values can, therefore, be used as an indicator that a sample is inappropriate for cation-ratio dating. The glacial chronology at Pine Creek, California, is revised in light of new data and a better understanding of variables influencing varnish chemistry.

Analyses of inks and papers in historical documents through external beam PIXE techniques

Abstract PIXE analyses of documents can be carried out to high sensitivity in an external beam configuration designed to protect historical materials from damage. Test runs have shown that a properly designed system with high solid angle can operate at less than 1% of the flux necessary to cause any discoloration whatsoever on papers of the 17th and 18th centuries. The composition of these papers is suprisingly complex, yet retains distinct association with the historical period, paper source, and even the individual sheets of paper that are folded and cut to make groups of pages. Early studies are planned on historical forgeries.

Complete elemental analysis of aerosols: PIXE, FAST, LIPM, and mass☆

Abstract Methods are described that allow additional information to be gained on aerosol parameters from samples suitable for PIXE analysis. In particular, these methods yield ways to directly compare the sum of all elemental species with total mass obtained by weighing or β gauging the same sample.

The external pixe milliprobe at davis: laser alignment, pixe calibration, and quality assurance

Abstract An external beam PIXE system has been developed at the Davis cyclotron, which is being used extensively for the analysis of the inks and papers of historical documents. This system has several important features. First, because the system is used in valuable and fragile documents, we have kept the heat loss very small. The amount of beam on the sample is minimized by a close detector geometry and by on-demand beam pulsing. A computer driven beam stop allows beam on the sample only when the data is being acquired. Second, the 1 to 2 mm2 beam spot can be accurately and quickly located at the desired position using a laser alignment system. With this system we can analyze single letters on one side of a page. Third, the beam on sample is internally monitored using the argon present in the 3 cm gap between the exit window and the sample. This is essential for thick targets which stop the beam. Finally, the elemental results are corrected for the decrease of beam energy at the target and for the X-ray attenuation between the target and the detector, and verified by thin standard foils. Similar corrections are made for the finite thickness of the samples. Multiple measurements on the inks of a single page show good consistency, whether done during the same cyclotron run or at another time. Our work indicates that external beam PIXE can be a very safe and accurate tool in historical research.

Forward Alpha Scattering Techniques (FAST) for elements hydrogen through fluorine

Abstract A system for analyzing very light elements, hydrogen through fluorine, has been developed using the scattering of 30 MeV alpha particles at 64° laboratory angle. Through forward alpha scattering techniques (FAST) and PIXE, the total elemental range can be covered, allowing full quantitative non-destructive analysis of a sample and comparison to measurement of total mass. Applications to size segregated atmospheric particles are given.

The hydrogen-sulfur correlation, by PIXE plus PESA, and aerosol source identification

Abstract The use of hydrogen-free thin teflon filters for particulate sampling has allowed us to simultaneously measure sulfur (and other elements) by PIXE and hydrogen by PESA. Particulate hydrogen in nonvolatile forms (since all analyses are in vacuum) is an important component of aerosols, totalling typically about 1 3 of all atoms. The hydrogen is measured at the same time as PIXE by placing a surface barrier detector at 30° in the forward direction, allowing the (p, p) kinematic energy shift to safely resolve hydrogen from the unresolved peaks of C, N, O, and heavier elements. The method is absolute and simple, with no important corrections. Sensitivity on 400 μg cm 2 teflon filters is about 5 ng cm 2 H in 100s. This technique was introduced to the National Park Service 31 station network in June. 1984, and immediately proved enormously valuable in separating natural aerosols from anthropogenic aerosols. For example, at Great Smoky NP, the H/S correlation was excellent, > 0.90, while the molar ratio was 10:1 (note: (NH 4 ) 2 SO 4 ) has a ratio 8:1), while at North Cascades NP, there was essentially no correlation and the H S molar ratio was 37:1. In the former, most hydrogen is tied to presumably anthropogenic sulfur species, while at North Cascades NP, the converse is true. Evidence of H 2 SO 4 ) aerosols from Arctic studies will also be shown.

Historical analyses by PIXE

Abstract Particle induced X-ray emission (PIXE) is ideally suited for the elemental analysis of the papers, parchment, and inks of books, manuscripts, and other historical documents. This paper will describe the general kinds of historical and bibliographical issues that can be addressed by PIXE, and it discusses two specific historical applications of the technique: to the Gutenberg Bible and the Calov Bible owned by Johann Sebastian Bach.

Proton milliprobe analyses of the Gutenberg Bible

Abstract The advent of printing with movable type is properly regarded as the most important technological event in modern cultural history, yet its earliest history is shrouded in mystery. The Davis proton milliprobe has enabled scientists and humanist scholars to collaborate in unlocking the secrets of earliest print, focusing on the contribution of Johannes Gutenberg. The 42-line Gutenberg Bible is not only the first book printed by movable type, it is considered by many to be the finest book every printed. Unfortunately very little is known about the materials and techniques used in this first large scale printing operation. In October 1982 we had the unprecedented opportunity to examine page-by-page the inks, papers, illuminations and binding of volume I of the Doheny Gutenberg Bible. A similar study of the Lilly New Testament (most of volume II) was undertaken in March 1983. The results, some wholly unexpected and very exciting, add a large new body of information about this great work, and give us new enlightenment on the day-to-day production of this first and most important printed book. Moreover, the discovery of the uniqueness of the ink in Gutenbergs Bible, combined with our ability to taken minutely detailed and non-destructive elemental “fingerprints” with the milliprobe beam of all man-made papers and inks, gives us a weapon that has never been available before to investigate some of the controversial basic questions in the history of the origins of printing technology.

Regional and local determinations of particulate matter and visibility in the southwestern United States during June and July, 1979

Abstract Data on ambient particulate concentrations by size and elemental composition taken in Arizona and Utah are compared to simultaneous telephotometer measurements of standard visual range. Particulate samples were collected during the VISTTA program from 26 June to 11 July 1979, at Zilnez Mesa, Arizona, and compared to similar 24 h measurements made as part of a long term research program at Zion and Canyonlands National Parks in Utah. Samples were collected with rotating drum Multtday impactors which provide three aerodynamic size ranges; 15μm–3.5μm; 3.5μm–0.5μm, and less than 0.5/jm. Elemental composition of samples was measured using the particle induced X-ray emission (PIXE) system at the Crocker Nuclear Laboratory. Measurements of visibility were made at Canyonlands National Park and Zilnez Mesa using both multiwavelength telephotometers and nephelometers. Results indicate that the particulate matter in each size range behaves to a large degree independently of the other size ranges, but that correlations are often observed between sites. On 29 June, an episode of elevated sulfur concentrations, > 1 μm m −3 of S, was observed at all three sites. Decreased visibilities were recorded for the episode period at both Canyonlands and Zilnez Mesa. Sulfur episodes on 22–24 June and 20–21 July measured at Zion and Canyonlands also correlated well with reduced visibility at Canyonlands. Episodes of reduced visibilities also occurred during periods of stable sulfur values. The strongest of these, on 1718 June, as well as a weaker one, 4–7 June, correlated well with fine soils in the 0.5–3.5 μm size range. The conclusion is that reduced visibility is associated with regional episodes of both increased sulfur and increased fine soils, with best correlations occurring in both cases for sizes somewhat greater than 0.5μm dia.