Light Baryon Spectroscopy using the CLAS Spectrometer at Jefferson Laboratory

Baryons are complex systems of confined quarks and gluons and exhibit the characteristic spectra of excited states. The systematics of the baryon excitation spectrum is important to our understanding of the effective degrees of freedom underlying nucleon matter. High-energy electrons and photons are a remarkably clean probe of hadronic matter, providing a microscope for examining the nucleon and the strong nuclear force. Current experimental efforts with the CLAS spectrometer at Jefferson Laboratory utilize highly-polarized frozen-spin targets in combination with polarized photon beams. The status of the recent double-polarization experiments and some preliminary results are discussed in this contribution.Comment: Contribution to the Proceedings of the XIV International Conference on Hadron Spectroscopy, 13-17 June 2011, Munich, German

The Experimental Status of Glueballs

Glueballs and other resonances with large gluonic components are predicted as bound states by Quantum Chromodynamics (QCD). The lightest (scalar) glueball is estimated to have a mass in the range from 1 to 2 GeV/c**2; a pseudoscalar and tensor glueball are expected at higher masses. Many different experiments exploiting a large variety of production mechanisms have presented results in recent years on light mesons with J(PC) = 0(++), 0(-+), and 2(++) quantum numbers. This review looks at the experimental status of glueballs. Good evidence exists for a scalar glueball which is mixed with nearby mesons, but a full understanding is still missing. Evidence for tensor and pseudoscalar glueballs are weak at best. Theoretical expectations of phenomenological models and QCD on the lattice are briefly discussed.Comment: 62 pages, 26 figure

Methods for Evaluating Educational Programs – Does Writing Center Participation Affect Student Achievement?

This paper evaluates the eff ectiveness of the introduction of a Writing Center at a university. The center has the purpose to provide subject-specifi c courses that aim to improve students‘ abilities of scientifi c writing. In order to deal with presumed selfperceptional biases of students in feedback surveys, we use diff erent quantitative evaluation methods and compare the results to corresponding qualitative student surveys. Based on this evaluation, we present and discuss the validity of the approaches to evaluate educational programs. Although almost all students reported the writing courses to be helpful, we fi nd no signifi cant eff ect of course participation on students‘ grades. We attribute the diff erence in the results between quantitative methods and qualitative surveys to the inappropriateness of student course evaluations for assessing the eff ectiveness of educational measures.Performance evaluation; educational programs; student evaluation; empirical methods

Research on failure of equipment when subject to vibration

This report is in the nature of a progress report; it sets forth in some detail the status of the research on the several tasks as of the date of the report. In general, the research was incomplete on that date and no conclusions are presented. The report is written primarily to keep parsonnel of the sponsoring agency apprised of work that has been accomplished. It is not intended for outside distribution or publication. This is the first annual report under a continuing research project whose objective is to gain a better understanding of the failure of equipment when subjected to vibration. This is essential to (1) the attainment of improved practices in design of equipment that is required to withstand vibration and (Z) to the application of more rational procedures for conducting vibration tests in the laboratory. In principle, the laboratory test creates a vibration condition that causes such failure of the equipment as would occur during actual service use. However, a laboratory test cannot reproduce the service condition in all of its details; thus, a good knowledge of the mechanics of failure is necessary to relate laboratory and service conditions in a constructive manner. The research program includes two general aspects that are being pursued concurrently, at least in the initial phase of the research program: 1. Actual electronic and mechanical components of equipment with known susceptibility to failure; e.g., a vacuum tube in the initial task, are subjected to vibration of various defined types. The components are connected in circuits designed to simulate a typical application and the effect of vibration on the operation of the circuits is monitored. An objective of the experiment is to infer from the circuit operation and response of the component an analog that may be used to describe the characteristics of the component that are significant with respect to vibration. Such analogs are then used in further analyses of the component. 2. Concurrent with the above experiments using actual components, a group of analogs having apparent application to known components is selected initially. Additional analogs are added to this group as experimental evaluation of actual components proceeds. The response of each selected analog to various idealized forms of vibration is investigated. Then from the relation between the response of the analog to such vibration and observed performance of the component to which the analog is related. the response of the component and its operational capability under more general types of vibration can be predicted. A representative vacuum tube has been mounted upon a vibration exciter and subjected to both sinusoidal and random vibration. Its performance was Monitored by noting the voltage output (microphonic noise) that could be ascribed to vibration. This report includes records of output voltage as a function of vibration frequency, for further use in attempting to infer an appropriate mechanical analog. Five idealized forms of excitation have been selected for initial investigation: (1) sinusoid, (2) combined sinusoids, (3) scanning or sweeping sinusoid, (4) broad band random with Gaussian distribution and (5) broad band random with magnitude limitation. For each type of excitation, the response of the most common mechanical analog, a damped, single degree of freedom system, has been analyzed. By relating the characteristics of the analog to an actual component and applying appropriate criteria of failure, these responses are of use in predicting the performance capability of the component. For example, consider a structure vulnerable to failure by fatigue; then the distribution of response cycles included in the analysis of the analog response when taken with hypotheses of cumulative damage is applicable to predict the fatigue life. Some experiments on fatigue have been carried out, with the objective of determining whether existing hypotheses of cumulative damage are applicable to the problem being discussed here. A simplified structure having certain characteristics of a typical equipment has been subjected to fatigue tests. Because of certain unanticipated characteristics of the response of the structure, it has become evident that additional experiments are required to interpret the results obtained to date. This phase of the program is continuing. Section 1 of the report includes a detailed discussion of research program, its hypotheses and objectives. A brief summary of the results also is included in Section 1, with references to other sections of the report and to the appendices when complete details are set forth

Gold transport in aqueous versus organic fluids: Experimental data and natural observations for describing ore-forming systems

The common association of carbonaceous matter (CM) with ore deposits is poorly understood. To understand the Au ore + CM association the ability of liquid hydrocarbons to act as an ore fluid was determined experimentally, and via analysis and textural observations of CMrich samples from the AuHg McLaughlin deposit in California, USA. Experimental data suggest that, below ~200 °C hydrocarbon (Au) ore fluids may be more effective transporters of Au than aqueous ore fluids

Atmospheric Modeling of Carbon Dioxide

The project considered the energy balance of the earth and the impact of trace gases on this balance. This issue was investigated through the use of a seven reservoir model of the earth\u27s ecosystem. Simulations based on actual carbon dioxide data were used to predict the concentration of this gas in the lower atmosphere and its impact on Human society. Various strategies to increase the intake of this gas by plants and other sinks were considered