Soils of Day County South Dakota

The soil map, in the folder attached to the back cover of this bulletin, has been divided into two sections, the eastern half and the western half. These maps show the distribution of different soils that occur in the county. In the text, recommendations as to the use, management, and conservation are made in an attempt to answer the major questions of the farmers and others interested in the soils of Day County

UV observations of the galaxy cluster Abell 1795 with the optical monitor on XMM-Newton

We present the results of an analysis of broad band UV observations of the central regions of Abell 1795 observed with the optical monitor on XMM-Newton. As have been found with other UV observations of the central regions of clusters of galaxies, we find evidence for star formation. However, we also find evidence for absorption in the cD galaxy on a more extended scale than has been seen with optical imaging. We also report the first UV observation of part of the filamentary structure seen in H$\alpha$, X-rays and very deep U band imaging. The part of the filament we see is very blue with UV colours consistent with a very early (O/B) stellar population. This is the first direct evidence of a dominant population of early type stars at the centre of Abell 1795 and implies very recent star formation at the centre of this clusterComment: 6 pages, 3 figures accepted by A&A Letter

X-ray Spectroscopy of the Cluster of Galaxies Abell 1795 with XMM-Newton

The initial results from XMM-Newton observations of the rich cluster of galaxies Abell 1795 are presented. The spatially-resolved X-ray spectra taken by the European Photon Imaging Cameras (EPIC) show a temperature drop at a radius of $\sim 200$ kpc from the cluster center, indicating that the ICM is cooling. Both the EPIC and the Reflection Grating Spectrometers (RGS) spectra extracted from the cluster center can be described by an isothermal model with a temperature of $\sim 4$ keV. The volume emission measure of any cool component ($<1$ keV) is less than a few % of the hot component at the cluster center. A strong OVIII Lyman-alpha line was detected with the RGS from the cluster core. The O abundance and its ratio to Fe at the cluster center is 0.2--0.5 and 0.5--1.5 times the solar value, respectively.Comment: Accepted: A&A Letters, 2001, 6 page

The WELL Detector

We introduce the WELL detector, a new type of position-sensitive gas proportional counter produced using advanced printed circuit board (PCB) technology. The WELL is based on a thin kapton foil, copp erclad on both sides. Charge amplifying micro-wells are etched into the first metal and kapton layers. These end on a micro-strip pattern which is defined on the second metal plane. The array of micr o-strips is used for read-out to obtain 1-D positional information. First results from our systematic assessment of this device are reported

The Micro-Groove Detector

We introduce the Micro-Groove Detector (MGD), a new type of position-sensitive gas proportional counter produced using advanced printed circuit board (PCB) technology. The MGD is based on a thin kapt on foil, clad with gold-plated copper on both sides. An array of micro-strips at a typical pitch of 200um is defined on the top metal layer. Using as a protection mask the metal left after the patter ning, charge amplifying micro-grooves are etched into the kapton layer. These end on a second micro-strip pattern which is defined on the bottom metal plane. The two arrays of micro-strips can have a n arbitrary relative orientation and so can be used for read-out to obtain 2-D positional information. First results from our systematic assessment of this device are reported: gas gain > 15000, rat e capability above 10^6mm-2s-1, energy resolution 22% at 5.4 keV, no significant charging or aging effects up to 5mC/cm, full primary charge collection efficiency even at high drift fields

A Two-Stage, High Gain Micro-strip Detector

A two stage position-sensitive gas proportional counter has been constructed by tightly coupling a Gas Electron Multiplier (GEM) with a Micro-Groove Detector (MGD). The GEM was used as the first amplifying stage and was optimised to transmit close to 100~\% of the primary charge even at very high drift fields (10~kV/cm). Very narrow GEM--MGD seperations (0--600~$\mu$m) were used so that the active volume of the detector is still very thin (3--3.6~mm) and the required drift field could be maintaine d using an acceptable drift voltage (around 4000~V). Very high combined gains (up to 3~$\times$10$^5$) were obtained with this system. The detector was found to be spark-free in the presence of HIPs (alpha particles) up to gains in excess of 10,000

X-ray Sources in the Hubble Deep Field Detected by Chandra

We present first results from an X-ray study of the Hubble Deep Field North (HDF-N) and its environs obtained using 166 ks of data collected by the Advanced CCD Imaging Spectrometer (ACIS) on board the Chandra X-ray Observatory. This is the deepest X-ray observation ever reported, and in the HDF-N itself we detect six X-ray sources down to a 0.5--8 keV flux limit of 4E-16 erg cm^-2 s^-1. Comparing these sources with objects seen in multiwavelength HDF-N studies shows positional coincidences with the extremely red object NICMOS J123651.74 +621221.4, an active galactic nucleus (AGN), three elliptical galaxies, and one nearby spiral galaxy. The X-ray emission from the ellipticals is consistent with that expected from a hot interstellar medium, and the spiral galaxy emission may arise from a `super-Eddington' X-ray binary or ultraluminous supernova remnant. Four of the X-ray sources have been detected at radio wavelengths. We also place X-ray upper limits on AGN candidates found in the HDF-N, and we present the tightest constraints yet on X-ray emission from the SCUBA submillimeter source population. None of the 10 high-significance submillimeter sources reported in the HDF-N and its vicinity is detected with Chandra ACIS. These sources appear to be dominated by star formation or have AGN with Compton-thick tori and little circumnuclear X-ray scattering.Comment: 11 pages, ApJ, in press, also available from http://www.astro.psu.edu/users/niel/hdf/hdf-chandra.htm

Substrate-less, spark-free micro-strip gas counters

Abstract We review recent work involving micro-strip gas counters with "advanced passivated" cathode strips. We present results from tests of a new variation of the MSGC, the planar micro-gap counter (PMGC), with very small ( ∼10 μ m) anode–cathode gap. Gains of up to 3×10 4 were achieved and gain variations due to charging effects were less than 10% using an ordinary (uncoated) boro-silicate glass substrate. The PMGC showed no reduction in gain when subjected to an X-ray flux of 4×10 5 Hz/mm 2 and survived exposure to alpha particles equivalent to 75 days' running at LHC with no signs of strip damage

The XMM-Newton Ω\Omega Project

The abundance of high-redshift galaxy clusters depends sensitively on the matter density \OmM and, to a lesser extent, on the cosmological constant $\Lambda$. Measurements of this abundance therefore constrain these fundamental cosmological parameters, and in a manner independent and complementary to other methods, such as observations of the cosmic microwave background and distance measurements. Cluster abundance is best measured by the X-ray temperature function, as opposed to luminosity, because temperature and mass are tightly correlated, as demonstrated by numerical simulations. Taking advantage of the sensitivity of XMM-Newton, our Guaranteed Time program aims at measuring the temperature of the highest redshift (z>0.4) SHARC clusters, with the ultimate goal of constraining both \OmM and $\Lambda$.Comment: To appear in the Proceedings of the XXI Moriond Conference: Galaxy Clusters and the High Redshift Universe Observed in X-rays, edited by D. Neumann, F. Durret, & J. Tran Thanh Va