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A polarimeter has been built for use with the Submillimetre Common-User Bolometer Array (SCUBA), on the James Clerk Maxwell Telescope (JCMT) in Hawaii. SCUBA is the first of a new generation of highly sensitive submillimetre cameras, and the UK/Japan Polarimeter adds a polarimetric imaging/photometry capability in the wavelength range 350 to 2000 microns. Early science results range from measuring the synchrotron polarization of the black hole candidate Sgr A* to mapping magnetic fields inferred from polarized dust emission in Galactic star-forming clouds. We describe the instrument design, performance, observing techniques and data reduction processes, along with an assessment of the current and future scientific capability., Comment: 10 pages, 7 figures, to appear in Monthly Notices of the Royal Astronomical Society

We describe techniques for testing and characterising semiconductor bolometers, using the bolometer model presented in Sudiwala et. al. [1]. The procedures are illustrated with results from a prototype bolometer for the high frequency instrument (HFI) in the Planck Surveyor cosmic microwave background mission. This is a bolometer using spider-web geometry and a neutron transmutation doped (NTD) germanium thermistor, designed for operation at 100 mK. Details are given of the laboratory facility used to take data at temperatures from 70 mK to 350 mK. This employs an adiabatic demagnetisation refrigerator to cool the detector and optics. The spatial and spectral properties of the optical system are controlled using feedhorns and edge filters. To characterise the bolometer, blanked and optically loaded load curves were measured over a range of temperatures, and the response to modulated radiation was measured as a function of modulation frequency, temperature and bias current. Results for the prototype bolometer show that its behaviour is well represented by an ideal thermal detector down to a temperature of approximately 100 mK. Below this, non-thermal effects such as electron-phonon decoupling or electric field dependent resistance appear to lead to departure from ideal behaviour. The performance was in good agreement with the design goals for the bolometer.

We report on the imaging detector array test and evaluation program for the Spectral and Photometric Imaging REceiver (SPIRE) instrument for the Far InfraRed and Submillimetre Telescope (FIRST) satellite. Three candidate detector array technologies are under evaluation: (i) hexagonally close-packed arrays of 2 Fλ feedhorns with NTD germanium sensors; (ii) filled absorber arrays with 0.5 Fλ square pixels with ion-implanted silicon sensors; and (iii) 0.5 Fλ filled arrays with transition-edge superconducting (TES) sensors. Detector arrays are required for SPIRE bands covering the 200–700 μm range. To meet the SPIRE performance requirements, the detectors must be background limited by the thermal emission from the 80 K low-emissivity FIRST telescope, achieve a speed of response of 20 Hz, and be fabricated in sizes up to 32×32. A novel cryogenic array test facility has been built to enable a range of experiments to be carried out under low background to enable a comprehensive evaluation and calibration programme on prototype detector arrays with a minimum of disruptive warm-up/cool-down cycles. The facility will be used to compare the performance of the different array types prior to array technology selection for SPIRE.

The High-Frequency Instrument (HFI) for the Planck Surveyor mission will measure anisotropies of the Cosmic Microwave Background (CMB) down to scales of 6 arcmin and to an accuracy of ΔT/T=2×10−6. Channels ranging in frequency from 100 to 857 GHz will use 100 mK spider web bolometer detectors with NTD Ge thermistors. The detectors must be photon noise limited and fast enough to preserve signal information at the 1 r.p.m. scan rate of the satellite. The prime low-frequency CMB channels at 143 and 217 GHz are the most technically demanding owing to the lower background limited NEPs. For the 143 GHz channel the requirements are that the time constant τ

Planck is a European Space Agency (ESA) satellite, launched in May 2009, which will map the cosmic microwave background anisotropies in intensity and polarisation with unprecedented detail and sensitivity. It will also provide full-sky maps of astrophysical foregrounds. An accurate knowledge of the telescope beam patterns is an essential element for a correct analysis of the acquired astrophysical data. We present a detailed description of the optical design of the High Frequency Instrument (HFI) together with some of the optical performances measured during the calibration campaigns. We report on the evolution of the knowledge of the pre-launch HFI beam patterns when coupled to ideal telescope elements, and on their significance for the HFI data analysis procedure.

We describe the Arcminute Cosmology Bolometer Array Receiver (ACBAR); a multifrequency millimeter-wave receiver designed for observations of the Cosmic Microwave Background (CMB) and the Sunyaev-Zel'dovich effect in clusters of galaxies. The ACBAR focal plane consists of a 16-pixel, background-limited, 240 mK bolometer array that can be configured to observe simultaneously at 150, 220, 280, and 350 GHz. With 4-5' FWHM Gaussian beam sizes and a 3 degree azimuth chop, ACBAR is sensitive to a wide range of angular scales. ACBAR was installed on the 2 m Viper telescope at the South Pole in January 2001. We describe the design of the instrument and its performance during the 2001 and 2002 observing seasons., Comment: 59 pages, 16 figures -- updated to reflect version published in ApJS

We have integrated a 4 K mechanical cryocooler with a three stage 4 He/ 3 He/ 3 He sorption refrigerator to achieve cooling down to 0.25 K. The cryocooler consists of two Gifford-MacMahon stages which cool 4He to below its inversion temperature for use in a Joule-Thomson expansion stage. This in turn provides cooling below the critical temperature of 4He. The sorption refrigerator is specified to achieve a heatlift of 3 microwatts at 0.25 K for 12 hours. This cryogenic system will be used for cooling of the bolometric detectors and optics in the Polatron, a ground-based receiver for measurement of the polarisation of the cosmic microwave background radiation at a frequency of 90 GHz. Cooling of sensitive detectors by mechanical cryocoolers can lead to sensitivity degradation due to a combination of microphonic pickup, electromagnetic interference and thermal dissipative heating. We describe the design features incorporated at system level to mitigate these effects. The Polatron also serves as a testbed for technologies to be used on the High Frequency Instrument on the ESA/NASA Planck satellite to measure the temperature anisotropies and polarisation of the cosmic microwave background radiation.

During Pleistocene pluvial precipitation was sufficient for the maintenance of groundwater supported lakes and for the accumulation of playa lakes in wind-scoured depressions during the early Holocene pluvial. At places where ground water reaches near to the surface, wells (birs) have been dug and maintained in historic times. These birs have been used as sampling sites for water analyses, including carbon-14 levels, carbon and oxygen stable isotope ratios, tritium concentrations, and chemical data.All the waters from birs analyzed to date produced apparent radiocarbon ages ranging from late historic to early Holocene, and tritium analyses on some of these indicate no recharge during the Atomic age.Sources of error for the radiocarbon analyses, including exchange with atmospheric CO2, respiration by plant roots, and contact with carbonates of considerably older age, were evaluated. None of these factors have such an extreme impact on the measurements as to render the result invalid. Two trends revealed by these data are an increase in apparent age from northwest to southwest and with subsequent extractions at the same site where the hand-dug well was bailed out and sampled four times within two days.We conclude that recharge of shallow ground water occurred in early Holocene time, and some recharge of deeper aquifers may have occurred where infiltration paths permitted. Some recharge occurred in late Holocene (post pluvial) time, but the net trend has been toward hyper-aridity that characterizes the area today.

Auger sputter profiles of thin AI films on InP are presented and shown to be susceptible to an unusual type of ion beam induced interfacial distortion. It is found that recoil implantation and atomic mixing produce a differential broadening of the In and P at the interface which can seriously affect the integrity of the Auger profile. Energy shifts in the AI Auger peak indicate that this distortion is associated with AIP formation to a depth dictated by the ion beam energy and species. Experimental requirements for the reduction of interfacial distortion are discussed. We also consider the influence of the ion beam on the topography and morphology of the InP surface in relation to interfacial distortion.

Recent research sheds new light on the period from 12,000 to 11,500 b.p., which is critical for undertstanding the origin of Clovis culture. Based on evidence available today, it appears likely that, late in the Pleistocene, caucasoid bands, bearing an Upper Paleolithic tool kit, migrated eastward from Central Asia to eastern Siberia and, eventually, across Beringia. On the way, they intermixed with sinodont peoples of northeast Asia in such a way that sinodonty became genetically dominant, but the tool kit was little changed. Between 13,000 and 12,000 b.p., one or more bands moved southward from Alaska through an ever-widening corridor between the retreating glaciers. It was after they passed beyond the remains of the ice barrier that a talented flint knapper invented the fluted projectile point. Whether or not they encountered other people already here remains to be determined.

From 1966 to 1979, the University of Missouri, the University of Arizona, and the Illinois State Museum conducted extensive interdisciplinary investigations of Late Pleistocene peat deposits associated with springs, some extinct, in the Pomme de Terre River Valley of the Ozark Highland, Missouri (fig 1). Most of the sites are now beneath the waters of the Harry S Truman reservoir. Archaeologic investigations in the area produced a remarkably long sequence of cultural change and development during the Holocene but produced no evidence of human presence in the area prior to 11,000 years ago despite diligent excavation of favorable bone-bearing deposits.

Buried lake sediments and tufa strandlines of Holocene age provide evidence of a former lake in the Selima Oasis depression, northwest Sudan, near the hyperarid core of the eastern Sahara Desert. A 1.6 m section through laminated lake muds and precipitates has been analysed in detail, and 30 radiocarbon dates, geochemical, sedimentological, diatom and pollen analyses indicate that the unit dated from approximately 8.4 ka BP to

Field investigations in southern Egypt have yielded Acheulian artifacts in situ in authigenic carbonate deposits (CaCO(3)-cemented alluvium) along the edges of nowaggraded paleovalleys (Wadi Arid and Wadi Safsaf). Uranium-series dating of 25 carbonate samples from various localities as far apart as 70 kilometers indicates that widespread carbonate deposition occurred about 45, 141 and 212 ka (thousand years ago). Most of the carbonate appears to have been precipitated from groundwater, which suggests that these three episodes of deposition may be related to late Pleistocene humid climates that facilitated human settlement in this now hyperarid region. Carbonate cements from sediments containing Acheulian artifacts provide a minimum age of 212 ka for early occupation of the paleovalleys.

Haynes, C. Vance, Jr., and George A. Agogino. Geochronology of Sandia Cave. Smithsonian Contributions to Anthropology, number 32, 32 pages, 7 figures, 2 tables, 1986.—Excavations in Sandia Cave, New Mexico, in the late 1930s provided the first recognized stratigraphic evidence for a preFolsom culture in North America. This, the Sandia complex, is represented by diagnostic projectile points found in a loose deposit underlying a limonite ocher deposit which, in turn, underlies a cave breccia containing Folsom artifacts and reportedly sealed by an overlying dripstone. Our investigations in the 1960s revealed that the Sandia deposit (unit X) is in fact, a rodent deposit created by bioturbation of the limonite ocher (unit C) and contains material derived from most of the other deposits. A second dripstone (unit D) is recognized as being much older (preoccupation) than the post-Folsom dripstone, instead of being a contemporary facies as originally reported. Its absence from the deposits near the mouth of the cave is believed to be due to removal during the mining of the yellow ocher by Paleo-Indians. Paleoclimatic interpretations of the stratigraphic units include (1) a warm moist period for the derivation of the ocher by leaching from a pedalferic paleosol formed during a previous cool moist period, (2) desiccation of the ocher during a dry climate, (3) formation of the lower dripstone during a cool moist period, (4) gypsum precipitation (unit E) due to either a dry period or opening of the cave or both, and (5) accumulation of dust and debris (units F and H) under dry conditions alternating with dripstones (units G and I) and breccia cementation under wet conditions. From 14,000 B.P. on, the cave interior was accessible to man and animals. Accumulation of dust and debris (unit F) occurred during a dry period during which a portion of the lower dripstone was removed, presumably by Paleo-Indians in order to extract ocher. During the sbusequent moist period the artifact-bearing debris became cemented by cave drip where not protected by the lower dripstone. Under recent climatic conditions another loose debris layer (unit J) has accumulated during the middle and late Holocene and has always been connected to the lower loose-debris deposit (unit X). We conclude that Sandia points are definitely less than 14,000 years old and suggest they may be specialized Clovis or Folsom artifacts used for mining ocher. However, we cannot preclude a pre-Clovis age or even postFolsom. Undisturbed cave strata provide valuable paleoenvironmental data, but redeposition and bioturbation is the rule rather than the exception for most, if not all, cave deposits that were once unconsolidated debris. OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is recorded in the Institution's annual report, Smithsonian Year. SERIES COVER DESIGN: North American Indian design of mounted horsemen on animal skin. Library of Congress Cataloging in Publication Data Haynes, C. Vance (Caleb Vance), 1928Geochronology of Sandia Cave. (Smithsonian contributions to anthropology ; no. 32) Bibliography: p. Supt. of Docs, no.: SI 1.33:32 1. Sandia Cave (N.M.) 2. Paleo-Indians—New Mexico. 3. New Mexico—Antiquities. I. Agogino, George. II. Title. III. Series. GN1.S54 no. 32 [E78.N65] 3 0 1 s [978.9'01] 85-600237

The shuttle imaging radar (SIR-A) carried on the space shuttle Columbia in November 1981 penetrated the extremely dry Selima Sand Sheet, dunes, and drift sand of the eastern Sahara, revealing previously unknown buried valleys, geologic structures, and possible Stone Age occupation sites. Radar responses from bedrock and gravel surfaces beneath windblown sand several centimeters to possibly meters thick delineate sand- and alluvium-filled valleys, some nearly as wide as the Nile Valley and perhaps as old as middle Tertiary. The now-vanished major river systems that carved these large valleys probably accomplished most of the erosional stripping of this extraordinarily flat, hyperarid region. Underfit and incised dry wadis, many superimposed on the large valleys, represent erosion by intermittent running water, probably during Quaternary pluvials. Stone Age artifacts associated with soils in the alluvium suggest that areas near the wadis may have been sites of early human occupation. The presence of old drainage networks beneath the sand sheet provides a geologic explanation for the locations of many playas and present-day oases which have been centers of episodic human habitation. Radar penetration of dry sand and soils varies with the wavelength of the incident signals (24 centimeters for the SIR-A system), incidence angle, and the electrical properties of the materials, which are largely determined by moisture content. The calculated depth of radar penetration of dry sand and granules, based on laboratory measurements of the electrical properties of samples from the Selima Sand Sheet, is at least 5 meters. Recent (September 1982) field studies in Egypt verified SIR-A signal penetration depths of at least 1 meter in the Selima Sand Sheet and in drift sand and 2 or more meters in sand dunes.

Recent discoveries of fossil-bearing Holocene lake sediments from the eastern Sahara have brought further confirmation and detail to earlier indirect evidence that a major pluvial episode occurred between 9,500 and 4,500 yr BP1–3. The botanical results, mainly palynological, show that savanna and desert grassland occupied regions that today are plantless hyperarid deserts. We present here the first evidence from the entire Saharan region of a latitudinal zonation of Holocene vegetation, extending across a 500-km wide belt in north-west Sudan. We have completed detailed pollen analyses of three of the several sites discovered so far, and the salient features from two, the northernmost and the southernmost, are presented here to demonstrate a steep gradient of past vegetative cover.

The complete plasma oxidation of a metal layer on a semiconductor substrate offers a versatile way of forming metal oxide layers at temperatures as low as 60°C {1}. The experimental procedures have been detailed previously {1,2}. The method avoids the possibility of contamination from the electrolyte and dissolution during growth which can occur with ‘wet’ anodisation.

The view that human populations may not have arrived in the Western Hemisphere before about 12,000 radiocarbon yr BP1,2 has been challenged by claims of much greater antiquity for a small number of archaeological sites and human skeleton samples. One such site is the Homo sapiens sapiens cairn burial excavated in 1971 from the Yuha desert, Imperial County, California3–5. Radiocarbon analysis of caliche coating one of the bones of the skeleton yielded a radiocarbon age of 21,500±1,000 yr BP4, while radiocarbon and uranium series analyses of caliche coating a cairn boulder yielded ages of 22,125±400 and 19,000±3,000 yr BP, respectively5. The late Pleistocene age assignment to the Yuha burial has been challenged by comparing the cultural context of the burial with other cairn burials in the same region6, on the basis of the site's geomorphological context and from radiocarbon analyses of soil caliches.7,8 In rebuttal, arguments in defence of the original age assignment have been presented9,10 as well as an amino acid racemization analysis on the Yuha skeleton indicating an age of 23,600±2,600 yr BP11. The tandem accelerator mass spectrometer at the University of Arizona has now been used to measure the ratio of 14C/13C in several organic and inorganic fractions of post-cranial bone from the Yuha H. sapiens sapiens skeleton. Isotope ratios from six chemical fractions all yielded radiocarbon ages for the skeleton of less than 4,000 yr BP. These results indicate that the Yuha skeleton is of Holocene age, in agreement with the cultural context of the burial, and in disagreement with the previously assigned Pleistocene age of 19,000–23,000 yr.

The usual procedure for preparation of CO (sub 2) from the oxalic-acid standard--wet oxidation by means of potassium permanganate in acid solution--suffers from difficulty in determining end point of the reaction. The method of preparation at the University of Arizona laboratory was reviewed to learn the factors responsible for fractionation. It was clear that fractionation progresses steadily throughout the wet oxidation of oxalic acid and that color change and cessation of bubbling are not adequate criteria for determining the end point. Freeze-thaw operations are layer processes occurring at cold-trap walls and may preserve serial fractionation through several cold-trap operations. It is necessary to monitor continually the delta C-13 values of the standard gas. Dry combustion affords an effective alternative to wet oxidation, but it also has problems.