Properties of an ionization spectrometer exposed to 10, 20.5, and 28 GeV/c machine accelerated protons

Properties of ionization spectrometer exposed to 10, 20.5, and 28 GeV/c synchrotron accelerated proton

A chemical and biological survey of the lower Potomac River in the vicinity of Piney Point, Maryland

This report presents the results of a survey of benthic organisms in the lower Potomac River estuary in the vicinity of Steuart Petroleum Company\u27s facilities at Piney Point, Maryland (Fig. 1). This survey was conducted to provide baseline data for the assessment of impact of the expansion of pier facilities at Steuart Petroleum. The environmental impact assessment is being made by Enviro Plan, Inc

Comparison of vitrified and unvitrified Eocene woody tissues by TMAH thermochemolysis – implications for the early stages of the formation of vitrinite

Samples of vitrified and unvitrified Eocene woody plant tissues collected from the Fossil Forest site, Geodetic Hills, Axel Heiberg Island, have been characterized by TMAH thermochemolysis. All samples are gymnosperm-derived, are of very low maturity and all share the same post-depositional geologic history. Differences in the distributions of products observed from vitrified and unvitrified samples suggest that vitrification of woody tissue is associated with modification of the lignin C3 side chain, following loss of all or most of the carbohydrate present in the precursor woody tissues. The key driver of vitrification appears to be physical compression of the tissue following biological removal of cellulosic materials

The Gibbs paradox, Black hole entropy and the thermodynamics of isolated horizons

This letter presents a new, solely thermodynamical argument for considering the states of the quantum isolated horizon of a black hole as distinguishable. We claim that only if the states are distinguishable, the thermodynamic entropy is an extensive quantity and can be well-defined. To show this, we make a comparison with a classical ideal gas system whose statistical description makes only sense if an additional 1/N!-factor is included in the state counting in order to cure the Gibbs paradox. The case of the statistical description of a quantum isolated horizon is elaborated, to make the claim evident.Comment: 8 pages, closest to the published version; taken from the author's diploma thesi

Inelastic interaction mean free path of negative pions in tungsten

The inelastic interaction mean free paths lambda of 5, 10, and 15 GeV/c pions were measured by determining the distribution of first interaction locations in a modular tungsten-scintillator ionization spectrometer. In addition to commonly used interaction signatures of a few (2-5) particles in two or three consecutive modules, a chi2 distribution is used to calculate the probability that the first interaction occurred at a specific depth in the spectrometer. This latter technique seems to be more reliable than use of the simpler criteria. No significant dependence of lambda on energy was observed. In tungsten, lambda for pions is 206 plus or minus 6 g/sq cm

Organic compounds in surface sediments and oyster tissues from the Chesapeake Bay

This report contains three parts. In Part I, the methodology to extract and analyze sediment and oyster tissue samples from the Chesapeake Bay is described in detail. Remaining problems are clearly identified. Part II contains the results and their discussion. Part III contains a number of appendices with detailed data. For those readers interested in still more detail, the complete bank of processed data is on computer tapes at this institute and at the Environmental Protection Agency-Chesapeake Bay Program office at Annapolis, Maryland. Also included in Part III we give the results of volatile halogenated organic compounds determined in water collected near the outfalls of several chlorine using facilities as well as from river mouths. The distribution of the total and a few specific organic compounds within the Bay is presented by histograms. Mass spectrometric analyses clearly reveal the fact that one specific class of organic compounds, hydrocarbons, are the most prominent pollutants in the Bay. The application of two different search routines, one concentrating on compounds at levels \u3e50 ppb and the other on temporal changes, allows a quick determination of areas where problems may exist and where additional research may be indicated. Two unusual sediment samples collected during the fall 1979 cruise are discussed separately: Sample 2-19-S which clearly indicates a recent dumping of DDT and polychlorinated biphenyls, and Sample 2-27-S which contained very high concentrations of unsubstituted polynuclear aromatics

The Present State of Organic Xenobiotics in the Chesapeake Bay - A Synthesis Paper

This manuscript discusses the results of the first two and one half years of a three-year study designed to determine the present state of xenobiotic compounds in the Chesapeake Bay. It shows that polynuclear aromatic hydrocarbons are the most frequently encountered compounds and are the most abundant. Concentrations are highest in the Northern Bay with several sources implicated. During this study an apparent dumping of the pesticide, DDT, occurred. Either the quantity disposed of was small enough or the assimulation capacity was large enough that no adverse effects were noted. The detection by us of 6-phenyldodecane in bottom sediments of the Patapsco River and its detection in a nearby industrial outfall by the Monsanto Research Corporation shows that chemicals entering the River can be dispersed throughout the system and can enter the Chesapeake Bay

Helicity, polarization, and Riemann-Silberstein vortices

Riemann-Silberstein (RS) vortices have been defined as surfaces in spacetime where the complex form of a free electromagnetic field given by F=E+iB is null (F.F=0), and they can indeed be interpreted as the collective history swept out by moving vortex lines of the field. Formally, the nullity condition is similar to the definition of "C-lines" associated with a monochromatic electric or magnetic field, which are curves in space where the polarization ellipses degenerate to circles. However, it was noted that RS vortices of monochromatic fields generally oscillate at optical frequencies and are therefore unobservable while electric and magnetic C-lines are steady. Here I show that under the additional assumption of having definite helicity, RS vortices are not only steady but they coincide with both sets of C-lines, electric and magnetic. The two concepts therefore become one for waves of definite frequency and helicity. Since the definition of RS vortices is relativistically invariant while that of C-lines is not, it may be useful to regard the vortices as a wideband generalization of C-lines for waves of definite helicity.Comment: 5 pages, no figures. Submitted to J of Optics A, special issue on Singular Optics; minor changes from v.