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NACA Zero Power Reactor Facility Hazards Summary

Description: The Lewis Flight Propulsion Laboratory of the National Advisory Committee for Aeronautics proposes to build a zero power research reactor facility which will be located in the laboratory grounds near Clevelaurd, Ohio. The purpose of this report is to inform the Advisory Committee on Reactor Safeguards of the U. S. Atomic Energy Commission in regard to the design of the reactor facility, the cha,acteristics of the site, and the hazards of operation at this location, The purpose of this reactor is to perform critical experiments, to measure reactivity effects, to serve as a neutron source, and to serve as a training tool. The reactor facility is described. This is followed by a discussion of the nuclear characteristics and the control system. Site characteristics are then discussed followed by a discussion of the experiments which may be conducted in the facility. The potential hazards of the facility are then considered, particularly, the maximum credible accident. Finally, the administrative procedure is discussed.
Date: June 24, 1957
Partner: UNT Libraries Government Documents Department

Reactor Physics Primer

Description: Report that describes the reactor physics of the processes used to produce plutonium at Hanford Laboratories. This includes a basic explanation of nuclear physics and the principles of the reactor process.
Date: November 15, 1957
Creator: Lockwood, E. H.
Partner: UNT Libraries Government Documents Department

Spatial Burnout in Water Reactors with Nonuniform Startup Distributions of Uranium and Boron

Description: Spatial burnout calculations have been made of two types of water moderated cylindrical reactor using boron as a burnable poison to increase reactor life. Specific reactors studied were a version of the Submarine Advanced Reactor (sAR) and a supercritical water reactor (SCW) . Burnout characteristics such as reactivity excursion, neutron-flux and heat-generation distributions, and uranium and boron distributions have been determined for core lives corresponding to a burnup of approximately 7 kilograms of fully enriched uranium. All reactivity calculations have been based on the actual nonuniform distribution of absorbers existing during intervals of core life. Spatial burnout of uranium and boron and spatial build-up of fission products and equilibrium xenon have been- considered. Calculations were performed on the NACA nuclear reactor simulator using two-group diff'usion theory. The following reactor burnout characteristics have been demonstrated: 1. A significantly lower excursion in reactivity during core life may be obtained by nonuniform rather than uniform startup distribution of uranium. Results for SCW with uranium distributed to provide constant radial heat generation and a core life corresponding to a uranium burnup of 7 kilograms indicated a maximum excursion in reactivity of 2.5 percent. This compared to a maximum excursion of 4.2 percent obtained for the same core life when w'anium was uniformly distributed at startup. Boron was incorporated uniformly in these cores at startup. 2. It is possible to approach constant radial heat generation during the life of a cylindrical core by means of startup nonuniform radial and axial distributions of uranium and boron. Results for SCW with nonuniform radial distribution of uranium to provide constant radial heat generation at startup and with boron for longevity indicate relatively small departures from the initially constant radial heat generation distribution during core life. Results for SAR with a sinusoidal distribution rather than uniform axial distributions of ...
Date: March 23, 1955
Creator: Fox, Thomas A. & Bogart, Donald
Partner: UNT Libraries Government Documents Department

Hadronic loops and the OZI rule

Description: Arguments based on unitarity indicate that hadronic loop diagrams should produce large violations of the OZI (Okubo-Zweig-Iizuka) rule. The mechanism by which these corrections are evaded has long been a mystery. We have found that there is an exact cancellation of all such loops in a particular (quark model) limit and that, at least for the rho-->omega system which we have studied in detail, the cancellation is maintained in a realistic calculation which takes into account departures from this limit.
Date: August 1, 1991
Creator: Isgur, Nathan
Partner: UNT Libraries Government Documents Department

The Jefferson Lab High Resolution TDC Module

Description: We discuss the design of a high resolution TDC module for use in nuclear physics experiments at Jefferson Lab. Preliminary results on the performance of the prototype module are presented.
Date: November 1, 2002
Creator: Barbosa, F.J.; Jastrzembski, E.; Proffitt, J. & Wilson, J.
Partner: UNT Libraries Government Documents Department

MEASUREMENT OF B(K{sup +} {yields} {pi}{sup +} {nu}{bar {nu}})

Description: The experimental measurement of K{sup +} {yields} {pi}{sup +} {nu}{bar {nu}} is reviewed. New results from experiment E787 at BNL are presented: with data from 1995-97 the branching ratio has been measured to be B(K{sup +} {yields} {pi}{sup +} {nu}{bar {nu}}) = (1.5{sub {minus}1.2}{sup +3.4}) x 10{sup {minus}10}. The future prospects for additional data in this mode are examined.
Date: May 22, 2000
Creator: KETTELL,S.H.
Partner: UNT Libraries Government Documents Department

Measurement of single-target spin asymmetries in the electroproduction of negative pions in the semi-inclusive deep inelastic reaction n{up_arrow}(e,e'{pi}{sup -})X on a transversely polarized {sup 3}He target

Description: The experiment E06010 measured the target single spin asymmetry (SSA) in the semiinclusive deep inelastic (SIDIS) n{up_arrow}(e, e'{pi}{sup -})X reaction with a transversely polarized {sup 3}He target as an e#11;ective neutron target. This is the very #12;rst independent measurement of the neutron SSA, following the measurements at HERMES and COMPASS on the proton and the deuteron. The experiment acquired data in Hall A at Je#11;erson Laboratory with a continuous electron beam of energy 5.9 GeV, probing the valence quark region, with x = 0.13 {rt_arrow} 0.41, at Q{sup 2} = 1.31 {rt_arrow} 3.1 GeV{sup 2}. The two contributing mechanisms to the measured asymmetry, viz, the Collins effect and the Sivers effect can be realized through the variation of the asymmetry as a function of the Collins and Sivers angles. The neutron Collins and Sivers moments, associated with the azimuthal angular modulations, are extracted from the measured asymmetry for the very #12;first time and are presented in this thesis. The kinematics of this experiment is comparable to the HERMES proton measurement. However, the COMPASS measurements on deuteron and proton are in the low-x region. The results of this experiment are crucial as the first step toward the extraction of quark transversity and Sivers distribution functions in SIDIS. With the existing results on proton and deuteron, these new results on neutron will provide powerful constraints on the transversity and Sivers distributions of both the u and d-quarks in the valence region.
Date: June 1, 2010
Creator: Dutta, Chiranjib
Partner: UNT Libraries Government Documents Department

Photodisintegration of Light Nuclei with CLAS

Description: We report preliminary results of photodisintegration of deuteron and {sup 3}He measured with CLAS at Jefferson Lab. We have extracted the beam-spin asymmetry for the {vector {gamma}}d {yields} pn reaction at photon energies from 1.1 GeV to 2.3 GeV and proton center-of-mass (c.m.) angles between 35{degrees}#14; and 135{degrees}#14;. Our data show interesting evolution of the angular dependence of the observable as the photon energy increases. The energy dependence of the beam-spin asymmetry at 90#14; shows a change of slope at photon energy of 1.6 GeV. A comparison of our data with model calculations suggests that a fully non-perturbative treatment of the underlying dynamics may be able to describe the data better than a model based on hard scattering. We have observed onset of dimensional scaling in the cross section of two-body photodisintegration of {sup 3}He at remarkably low energy and momentum transfer, which suggests that partonic degrees of freedom may be relevant for the description of nuclei at energies lower than previously considered.
Date: August 1, 2013
Creator: Ilieva, Yordanka Yordanova & Zachariou, Nicholas
Partner: UNT Libraries Government Documents Department

Nuclear electromagnetic charge and current operators in Chiral EFT

Description: We describe our method for deriving the nuclear electromagnetic charge and current operators in chiral perturbation theory, based on time-ordered perturbation theory. We then discuss possible strategies for fixing the relevant low-energy constants, from the magnetic moments of the deuteron and of the trinucleons, and from the radiative np capture cross sections, and identify a scheme which, partly relying on {Delta} resonance saturation, leads to a reasonable pattern of convergence of the chiral expansion.
Date: August 1, 2013
Creator: Girlanda, Luca; Marcucci, Laura Elisa; Pastore, Saori; Piarulli, Maria; Schiavilla, Rocco & Viviani, Michele
Partner: UNT Libraries Government Documents Department

Meausrement of the Neutron Radius of {sup 208}Pb Through Parity Violation in Electron Scattering

Description: In contrast to the nuclear charge densities, which have been accurately measured with electron scattering, the knowledge of neutron densities still lack precision. Previous model-dependent hadron experiments suggest the difference between the neutron radius, R{sub n}, of a heavy nucleus and the proton radius, R{sub p}, to be in the order of several percent. To accurately obtain the difference, R{sub n}-R{sub p}, which is essentially a neutron skin, the Jefferson Lab Lead ({sup 208}Pb) Radius Experiment (PREX) measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from {sup 208}Pb at an energy of 1.06 GeV and a scattering angle of 5{degrees}#14;. Since Z{sup 0} boson couples mainly to neutrons, this asymmetry provides a clean measurement of R{sub n} with respect to R{sub p}. PREX was conducted at the Jefferson lab experimental Hall A, from March to June 2010. The experiment collected a final data sample of 2x#2;10{sup 7} helicity-window quadruplets. The measured parity-violating electroweak asymmetry A{sub PV} = 0.656 {+-}#6; 0.060 (stat) {+-}#6; 0.014 (syst) ppm corresponds to a difference between the radii of the neutron and proton distributions, R{sub n}-R{sub p} = 0.33{sup +0.16}{sub -0.18} fm and provides the #12;first electroweak observation of the neutron skin as expected in a heavy, neutron-rich nucleus. The value of the neutron radius of {sup 208}Pb has important implications for models of nuclear structure and their application in atomic physics and astrophysics such as atomic parity non-conservation (PNC) and neutron stars.
Date: May 31, 2013
Creator: Saenboonruang, Kiadtisak
Partner: UNT Libraries Government Documents Department

Study of the (e,e'p) quasi-elastic reaction in complex nuclei: theory and experiment

Description: Experimental coincidence cross section and transverse-longitudinal asymmetry A{sub TL} have been obtained for the quasielastic (e,e'p) reaction in {sup 16}O, {sup 12}C, and {sup 208}Pb in constant q-ω kinematics in the missing momentum range -350 < p{sub miss} < 350 MeV/c. In these experiments, performed in experimental Hall A of the Thomas Jefferson National Accelerator Facility (JLAB), the beam energy and the momentum and angle of the scattered electrons were kept fixed, while the angle between the proton momentum and the momentum transfer q was varied in order to map out the missing momentum distribution. The experimental cross section and A{sub TL} asymmetry have been compared with Monte Carlo simulations based on Distorted Wave Impulse Approximation (DWIA) calculations with both relativistic and non-relativistic spinor structure. The spectroscopic factors obtained for both models are in agreement with previous experimental values, while A{sub TL} measurements favor the relativistic DWIA calculation. This thesis describes the details of the experimental setup, the calibration of the spectrometers, the techniques used in the data analysis to derive the final cross sections and the A{sub TL}, the ingredients of the theoretical calculations employed and the comparison of the results with the simulations based on these theoretical models.
Date: March 1, 2010
Creator: Herraiz, Joaquin Lopez
Partner: UNT Libraries Government Documents Department

GFMC calculations of electromagnetic moments and M1 transitions in A {<=} 9 nuclei

Description: We present recent Green’s function Monte Carlo calculations of magnetic moments and M1 transitions in A{<=}#20;9 nuclei, which include corrections arising from two-body meson-exchange electromagnetic currents. Two-body effects provide significant corrections to the calculated observables, bringing them in excellent agreement with the experimental data. In particular, we find that two body corrections are especially large in the A = 9, T = 3/2 systems, in which they account for up to ~#24; 20% (~#24; 40%) of the total predicted value for the {sup 9}Li ({sup 9}C) magnetic moment.
Date: August 1, 2013
Creator: Pastore, Saori; Pieper, Steven C.; Schiavilla, Rocco & Wiringa, Robert Bruce
Partner: UNT Libraries Government Documents Department

Caught in the Act

Description: Representing the Center for Defect Physics (CDP), this document is one of the entries in the Ten Hundred and One Word Challenge. As part of the challenge, the 46 Energy Frontier Research Centers were invited to represent their science in images, cartoons, photos, words and original paintings, but any descriptions or words could only use the 1000 most commonly used words in the English language, with the addition of one word important to each of the EFRCs and the mission of DOE: energy. The mission of the CDP is to enhance our fundamental understanding of defects, defect interactions, and defect dynamics that determine the performance of structural materials in extreme environments.
Date: July 18, 2013
Creator: Stocks, G. Malcolm; Morris, James; Sproles, Andrew; Henson, Priscilla & Graham, Kathy
Partner: UNT Libraries Government Documents Department