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Helicity Asymmetry in gamma p -> pi+ n with FROST

Description: The main objective of the FROST experiment at Jefferson Lab is the study of baryon resonances. The polarization observable E for the reaction gamma p to pi+n has been measured as part of this program. A circularly polarized tagged photon beam with energies from 0.35 to 2.35 GeV was incident on a longitudinally polarized frozen-spin butanol target. The final-state pions were detected with the CEBAF Large Acceptance Spectrometer. Preliminary polarization data agree fairly well with present SAID and MAID partial-wave analyses at low photon energies. In most of the covered energy range, however, significant deviations are observed. These discrepancies underline the crucial importance of polarization observables to further constrain these analyses.
Date: April 1, 2012
Creator: Strauch, Steffen
Partner: UNT Libraries Government Documents Department

Political Culture in West and East Germany at the TIme of Reunification: Revisiting the Civic Culture

Description: Studies of political culture have often focused on the impact of political institutions on political culture in a society. The scientific community has accepted the position that institutions shape beliefs and attitudes among the citizens towards the system they live in. This study tests this hypothesis by using survey data collected during the fall of 1990 in the United States, Great Britain, Italy, West, and East Germany.
Date: August 1997
Creator: Baumann, Steffen
Partner: UNT Libraries

Maintenance optimization plan for essential equipment reliability

Description: The Maintenance Optimization Plan (MOP) for Essential Equipment Reliability will furnish Tank Waste Remediation System (TWRS) management with a pro-active, forward-thinking process for maintaining essential structures, systems, and components (ESSC) at the Hanford Site tank farms in their designed condition, and to ensure optimum ESSC availability and reliability.
Date: February 1, 1996
Creator: Steffen, D. H.
Partner: UNT Libraries Government Documents Department

Measurement of the neutron spin structure function at low Q{sup 2}

Description: The spin dependent cross sections, {sigma}{sup T}{sub 1/2} and {sigma}{sup T}{sub 3/2}, and asymmetries, A{sub {parallel}} and A{sub {perp}}, for {sup 3}He have been measured at the Jefferson Lab's Hall A facility. The inclusive scattering process {sup 3}{vec He}({vec e},e)X was performed for initial beam energies ranging from 0.86 to 5.1 GeV, at a scattering angle of 15.5°. Data includes measurements from the quasielastic peak, resonance region, and the deep inelastic regime. An approximation for the extended Gcrasimov-Drell-Hcarn integral is presented at a 4-momentum transfer Q{sup 2} of 0.2-1.0 GeV{sup 2} . Also presented are results on the performance of the polarized {sup 3}He target. Polarization of {sup 3}He vvas achieved by the process of spin-exchange collisions with optically pumped rubidium vapor. The {sup 3}He polarization was monitored using the NMR technique of adiabatic fast passage (AFP). The average target polarization was approximately 35% and was determined to have a systematic uncertainty of roughly ±4% relative.
Date: August 1, 2000
Creator: Jensen, John Steffen
Partner: UNT Libraries Government Documents Department

324 Building safety basis criteria document

Description: The Safety Basis Criteria document describes the proposed format, content, and schedule for the preparation of an updated Safety Analysis Report (SAR) and Operational Safety Requirements document (OSR) for the 324 Building. These updated safety authorization basis documents are intended to cover stabilization and deactivation activities that will prepare the facility for turnover to the Environmental Restoration Contractor for final decommissioning. The purpose of this document is to establish the specific set of criteria needed for technical upgrades to the 324 Facility Safety Authorization Basis, as required by Project Hanford Procedure HNF-PRO-705, Safety Basis Planning, Documentation, Review, and Approval.
Date: June 2, 1999
Creator: STEFFEN, J.M.
Partner: UNT Libraries Government Documents Department


Description: We study pion production from high energy nuclear collisions by means of a simple statistical model. The shapes of the observed spectra exclude that all pions result from freely decaying delta resonances. Rather, they have to participate in kinetic equilibration processes. Finite particle number effects are found to be very important: equilibration does not occur globally but rather in groups of only a few particles. The pion production rates cannot be explained in terms of a chemical equilibrium.
Date: May 1, 1980
Creator: Bohrmann, Steffen & Knoll, Jorn
Partner: UNT Libraries Government Documents Department

Consonantal Assimilation in English

Description: The purpose of this study is to show that the phonetic changes wrought by assimilation in the development of the sound of Modern English are still at work. To do this, historical examples will be placed side by side with others from present-day English. No effort is made to restrict examples to any one dialectical area or time.
Date: 1957
Creator: Harllee, Thomas Steffen
Partner: UNT Libraries

The Terrestrial Biosphere and Global Change: Implications for Natural and Managed Ecosystems

Description: From the perspective of terrestrial ecosystems, the most important component of global change over the next three or four decades will likely be land-use/cover change. It is driven largely by the need to feed the expanding human population, expected to increase by almost one billion (109) people per decade for the next three decades at least. Much of this increase will occur in developing countries in the low-latitude regions of the world. To meet the associated food demand, crop yields will need to increase, consistently, by over 2% every year through this period. Despite advances in technology, increasing food production must lead to intensification of agriculture in areas which are already cropped, and conversion of forests and grasslands into cropping systems. Much of the latter will occur in semi-arid regions and on lands which are marginally suitable for cultivation, increasing the risk of soil erosion, accelerated water use, and further land degradation.
Date: 1997
Creator: Walker, Brian & Steffen, WIll
Partner: UNT Libraries

The CHASE laboratory search for chameleon dark energy

Description: A scalar field is a favorite candidate for the particle responsible for dark energy. However, few theoretical means exist that can simultaneously explain the observed acceleration of the Universe and evade tests of gravity. The chameleon mechanism, whereby the properties of a particle depend upon the local environment, is one possible avenue. We present the results of the Chameleon Afterglow Search (CHASE) experiment, a laboratory probe for chameleon dark energy. CHASE marks a significant improvement other searches for chameleons both in terms of its sensitivity to the photon/chameleon coupling as well as its sensitivity to the classes of chameleon dark energy models and standard power-law models. Since chameleon dark energy is virtually indistinguishable from a cosmological constant, CHASE tests dark energy models in a manner not accessible to astronomical surveys.
Date: November 1, 2010
Creator: Steffen, Jason H.
Partner: UNT Libraries Government Documents Department

A statistical mechanics model for free-for-all airplane passenger boarding

Description: I discuss a model for free-for-all passenger boarding which is employed by some discount air carriers. The model is based on the principles of statistical mechanics where each seat in the aircraft has an associated energy which reflects the preferences of travelers. As each passenger enters the airplane they select their seats using Boltzmann statistics, proceed to that location, load their luggage, sit down, and the partition function seen by remaining passengers is modified to reflect this fact. I discuss the various model parameters and make qualitative comparisons of this passenger boarding model with those that involve assigned seats. The model can be used to predict the probability that certain seats will be occupied at different times during the boarding process. These results might provide a useful description of this boarding method. The model is a relatively unusual application of undergraduate level physics and describes a situation familiar to many students and faculty.
Date: August 1, 2008
Creator: Steffen, Jason H. & /Fermilab
Partner: UNT Libraries Government Documents Department

Optimal boarding method for airline passengers

Description: Using a Markov Chain Monte Carlo optimization algorithm and a computer simulation, I find the passenger ordering which minimizes the time required to board the passengers onto an airplane. The model that I employ assumes that the time that a passenger requires to load his or her luggage is the dominant contribution to the time needed to completely fill the aircraft. The optimal boarding strategy may reduce the time required to board and airplane by over a factor of four and possibly more depending upon the dimensions of the aircraft. I explore some features of the optimal boarding method and discuss practical modifications to the optimal. Finally, I mention some of the benefits that could come from implementing an improved passenger boarding scheme.
Date: February 1, 2008
Creator: Steffen, Jason H. & /Fermilab
Partner: UNT Libraries Government Documents Department


Description: To describe pion absorption in nuclei, we introduce a model which assumes that the incident pion is absorbed by the row of target nucleons along the beam direction. The momentum distribution of these nucleons after absorbing the pion is assumed to be determined by the phase space. The experimental data on the inclusive proton cross section are well reproduced.
Date: June 1, 1980
Creator: Ko, Che Ming & Bohrmann, Steffen
Partner: UNT Libraries Government Documents Department

The GammeV suite of experimental searches for axion-like particles

Description: We report on the design and results of the GammeV search for axion-like particles and for chameleon particles. We also discuss plans for an improved experiment to search for chameleon particles, one which is sensitive to both cosmological and power-law chameleon models. Plans for an improved axion-like particle search using coupled resonant cavities are also presented. This experiment will be more sensitive to axion-like particles than stellar astrophysical models or current helioscope experiments.
Date: August 1, 2009
Creator: Steffen, Jason H. & Upadhye, Amol
Partner: UNT Libraries Government Documents Department

Higher order corrections to energy levels of muonic atoms

Description: In order to facilitate the analysis of muonic x-ray spectra, the results of numerical computations of all higher order quantum electrodynamical corrections to the energy levels of muonic atoms are presented in tabular and graphical form. These corrections include the vacuum polarization corrections caused by emission and reabsorption of virtual electron pairs to all orders, including ''double-bubble'' and ''cracked-egg'' diagrams. An estimate of the Delbruecke scattering-type correction is presented. The Lamb-shift (second- and fourth-order vertex) corrections have been calculated including the correction for the anomalous magnetic moment of the muon. The relativistic nuclear motion (or recoil) correction as well as the correction caused by the screening of the atomic electrons is presented in graphs. For the sake of completeness a graph of the nuclear polarization as computed on the basis of Chen's approach has been included. All calculations were made with a two-parameter Fermi distribution of the nuclear charge density. 7 figures, 23 references. (auth)
Date: August 1, 1975
Creator: Rinker, G.A. Jr. & Steffen, R.M.
Partner: UNT Libraries Government Documents Department