681 Matching Results

Search Results

Advanced search parameters have been applied.

Direct observation of stochastic domain-wall depinning in magnetic nanowires

Description: The stochastic field-driven depinning of a domain wall pinned at a notch in a magnetic nanowire is directly observed using magnetic X-ray microscopy with high lateral resolution down to 15 nm. The depinning-field distribution in Ni{sub 80}Fe{sub 20} nanowires considerably depends on the wire width and the notch depth. The difference in the multiplicity of domain-wall types generated in the vicinity of a notch is responsible for the observed dependence of the stochastic nature of the domain wall depinning field on the wire width and the notch depth. Thus the random nature of the domain wall depinning process is controllable by an appropriate design of the nanowire.
Date: November 1, 2008
Creator: Im, Mi-Young; Bocklage, Lars; Fischer, Peter & Meier, Guido
Partner: UNT Libraries Government Documents Department

Final Technical Report for the Neutron Detection without Helium-3 Project

Description: This report details the results of the research and development work accomplished for the ‘Neutron Detection without Helium-3’ project conducted during the 2011-2013 fiscal years. The primary focus of the project was to investigate commercially available technologies that might be used in safeguards applications in the relatively near term. Other technologies that are being developed may be more applicable in the future, but were outside the scope of this study.
Date: November 1, 2013
Creator: Ely, James H.; Bliss, Mary; Kouzes, Richard T.; Lintereur, Azaree T.; Robinson, Sean M.; Siciliano, Edward R. et al.
Partner: UNT Libraries Government Documents Department

Nuclear Shapes at High Angular Momentum

Description: Multiplicities as a function of {gamma}-ray energy have been measured for continuum {gamma}-ray spectra produced in argon- and calcium-induced reactions. A peak sometimes occurs in the multiplicity spectrum, indicating a correlation between {gamma}-ray energy and multiplicity (spin). This correlation can be explained by rotational motion of the nucleus, suggesting basically prolate nuclear shapes. Absence of structure in the multiplicity spectrum is interpreted to indicate non-collective motion, and hence spherical or oblate shapes.
Date: December 1, 1977
Creator: Deleplanque, M.A.; Lee, I.Y.; Stephens, F.S.; Diamond, R.M. & Aleonard, M.M.
Partner: UNT Libraries Government Documents Department

MPACT Fast Neutron Multiplicity System Prototype Development

Description: This document serves as both an FY2103 End-of-Year and End-of-Project report on efforts that resulted in the design of a prototype fast neutron multiplicity counter leveraged upon the findings of previous project efforts. The prototype design includes 32 liquid scintillator detectors with cubic volumes 7.62 cm in dimension configured into 4 stacked rings of 8 detectors. Detector signal collection for the system is handled with a pair of Struck Innovative Systeme 16-channel digitizers controlled by in-house developed software with built-in multiplicity analysis algorithms. Initial testing and familiarization of the currently obtained prototype components is underway, however full prototype construction is required for further optimization. Monte Carlo models of the prototype system were performed to estimate die-away and efficiency values. Analysis of these models resulted in the development of a software package capable of determining the effects of nearest-neighbor rejection methods for elimination of detector cross talk. A parameter study was performed using previously developed analytical methods for the estimation of assay mass variance for use as a figure-of-merit for system performance. A software package was developed to automate these calculations and ensure accuracy. The results of the parameter study show that the prototype fast neutron multiplicity counter design is very nearly optimized under the restraints of the parameter space.
Date: September 1, 2013
Creator: Chichester, D. L.; Pozzi, S. A.; Dolan, J. L.; Kinlaw, M. T.; Thompson, S. J.; Kaplan, A. C. et al.
Partner: UNT Libraries Government Documents Department

Strangeness production in minimum-bias events at CDF

Description: In a recently published paper 1 are emphasized, for the soft subsample extracted from the minimum-bias (MB) dataset of p{bar p} collisions, interesting invariances with the c.m. energy of the charged multiplicity and p{sub T} distributions. We present an analogous study on V{sup 0} production.
Date: January 15, 2003
Creator: Moggi, N.
Partner: UNT Libraries Government Documents Department

D. acosta et al., the cdf collaboration,

Description: We present a measurement of the ratio of top-quark branching fractions R = {Beta}(t {yields} Wb)/{Beta}(t {yields} Wq) using lepton-plus-jets and dilepton data sets with integrated luminosity of {approx}162 pb{sup -1} collected with the Collider Detector at Fermilab during Run II of the Tevatron. The measurement is derived from the relative numbers of t{bar t} events with different multiplicity of identified secondary vertices. We set a lower limit of R > 0.61 at 95% confidence level.
Date: May 27, 2005
Creator: Physics, Top & Collid, Measurement of B (t -> Wb)/B(t -> Wq) at the
Partner: UNT Libraries Government Documents Department

Static Bustle: Patterns Achieved Through Repetitive Processes (Artists Statement)

Description: Static Bustle is a gradute work that explores relationships between visual art and sound through experiments with new and traditional media, including sound, video, digital images prints and fibers. Through strategic processes of layering and repetition, the researcher seamlessly unifies this remarkable range of media into an accessible and cohesive vision. Overall, this research shows visual and sonic pattern achieved through repetitive processes.
Date: May 2015
Creator: Vogt, Jonathan C.
Partner: UNT Libraries

Static Bustle: Patterns Achieved Through Repetitive Processes

Description: Static Bustle is a gradute work that explores relationships between visual art and sound through experiments with new and traditional media, including sound, video, digital images prints and fibers. Through strategic processes of layering and repetition, the researcher seamlessly unifies this remarkable range of media into an accessible and cohesive vision. Overall, this research shows visual and sonic pattern achieved through repetitive processes.
Date: May 2015
Creator: Vogt, Jonathan C.
Partner: UNT Libraries

Unfolding the fission prompt gamma-ray energy and multiplicity distribution measured by DANCE

Description: The nearly energy independence of the {gamma}-ray efficiency and multiplicity response for the DANCE array, the unusual characteristic elucidated in our early technical report (LLNL-TR-452298), gives one a unique opportunity to derive the true prompt {gamma}-ray energy and multiplicity distribution in fission from the measurement. This unfolding procedure for the experimental data will be described in details and examples will be given to demonstrate the feasibility of reconstruction of the true distribution.
Date: October 16, 2010
Creator: Chyzh, A; Wu, C Y; Bredeweg, T; Couture, A; Jandel, M; Ullmann, J et al.
Partner: UNT Libraries Government Documents Department

Fission prompt gamma-ray multiplicity distribution measurements and simulations at DANCE

Description: The nearly energy independence of the DANCE efficiency and multiplicity response to {gamma} rays makes it possible to measure the prompt {gamma}-ray multiplicity distribution in fission. We demonstrate this unique capability of DANCE through the comparison of {gamma}-ray energy and multiplicity distribution between the measurement and numerical simulation for three radioactive sources {sup 22}Na, {sup 60}Co, and {sup 88}Y. The prospect for measuring the {gamma}-ray multiplicity distribution for both spontaneous and neutron-induced fission is discussed.
Date: August 24, 2010
Creator: Chyzh, A; Wu, C Y; Ullmann, J; Jandel, M; Bredeweg, T; Couture, A et al.
Partner: UNT Libraries Government Documents Department

Software Requirements Specification: Multi-scale Epidemiological and Economic Simulation and Analysis (MESA) Scenario Bank

Description: This document builds on the discussion notes from September 21, 2006. It provides a summary of the ideas relating to the scenario bank tables and their associated requirements. Two conceptual groupings were identified for the contents requirements of the scenario bank. The first, called ProjectTemplate, shall consist of <Project, Scenarios, and Miscellaneous Files> groups. The second, ProjectArchive, shall consist of groups of <Project, Scenarios, Results, and Miscellaneous Files>. The figure below illustrates the multiplicity of the associations between the different tables, with color coding used to distinguish between current MESA (brown) and USDA (light green) requirements. Scenario bank tables are shown in black with their general contents specified within the box. The metadata associated with each table is expected to include database key information as well as relevant timestamps. Each File is expected to be a file with an arbitrary format.
Date: November 8, 2006
Creator: Dahlgren, T L; Hazlett, S G; Slone, D M & Smith, S G
Partner: UNT Libraries Government Documents Department

Energy Dependence of High Moments for Net-proton Distributions

Description: High moments of multiplicity distributions of conserved quantities are predicted to be sensitive to critical fluctuations. To understand the effect of the non-critical physics backgrounds on the proposed observable, we have studied various moments of net-proton distributions with AMPT, Hijing, Therminator and UrQMD models, in which no QCD critical point physics is implemented. It is found that the centrality evolution of various moments of net-proton distributions can be uniformly described by a superposition of emission sources. In addition, in the absence of critical phenomena, some moment products of net-proton distributions, related to the baryon number susceptibilities in Lattice QCD calculations, are predicted to be constant as a function of the collision centrality. We argue that a non-monotonic dependence of the moment products as a function of the beam energy may be used to locate the QCD critical point.
Date: July 7, 2010
Creator: Luo, Xiaofeng; Mohanty, Bedangadas; Ritter, Hans Georg & Xu, Nu
Partner: UNT Libraries Government Documents Department

Growth of Long Range Forward-Backward Multiplicity Correlations with Centrality in Au+Au Collisions at sqrt sNN = 200 GeV

Description: Forward-backward multiplicity correlation strengths have been measured with the STAR detector for Au+Au and p+p collisions at {radical}s{sub NN} = 200 GeV. Strong short and long range correlations (LRC) are seen in central Au+Au collisions. The magnitude of these correlations decrease with decreasing centrality until only short range correlations are observed in peripheral Au+Au collisions. Both the Dual Parton Model (DPM) and the Color Glass Condensate (CGC) predict the existence of the long range correlations. In the DPM the fluctuation in the number of elementary (parton) inelastic collisions produces the LRC. In the CGC longitudinal color flux tubes generate the LRC. The data is in qualitative agreement with the predictions from the DPM and indicates the presence of multiple parton interactions.
Date: July 5, 2010
Creator: Collaboration, STAR & Abelev, Betty
Partner: UNT Libraries Government Documents Department


Description: Both the magnitude and alignment of the transferred angular momentum in the reaction {sup 165}Ho + {sup 165}Ho have been measured as a function of Q value via continuum {gamma}-ray multiplicity and anisotropy techniques. Two regimes are observed: A low-Q-value regime where the aligned angular momentum component dominates over the random components, and a large-Q-value regime where the random components dominate and decrease the spin alignment.
Date: July 1, 1980
Creator: Wozniak, G.J.; McDonald, R.J.; Pacheco, A.J.; Hsu, C.C.; Morrissey, D.J.; Sobotka, L.G. et al.
Partner: UNT Libraries Government Documents Department

Can Handheld Plastic Detectors Do Both Gamma and Neutron Isotopic Identification with Directional Source Location?

Description: This paper demonstrates, through MCNPX simulations, that a compact hexagonal array of detectors can be utilized to do both gamma isotopic identification (ID) along with neutron identification while simultaneously finding the direction of the source relative to the detector array. The detector array itself is composed of seven borated polyvinyl toluene (PVT) hexagonal light pipes approximately 4 inches long and with a 1.25 inch face-to-face thickness assembled in a tight configuration. The gamma ID capability is realized through judicious windowing algorithms as is the neutron spectral unfolding. By having multiple detectors in different relative positions, directional determination of the source can be realized. By further adding multiplicity counters to the neutron counts, fission events can be measured.
Date: April 18, 2008
Creator: Hayes, Robert
Partner: UNT Libraries Government Documents Department

Qualification of SRS's KAMS NMC and GIS Systems

Description: The Savannah River Site's KAMS facility was designed for the receipt and storage of incoming SNM shipments. MC and A requires confirmation and verification on these items. These items normally arrive packaged in a 9975. The KAMS facility has a Neutron Multiplicity Counter (NMC) and a Gamma Isotopic System (GIS) to support these measurements. This report will discuss the qualification of the NMC and GIS for KAMS receipts. The task was made significantly more difficult as the items contain a whole host of materials from Pu metal to mixed Pu/EU and from items relativity free from impurities to items containing significant amounts of impurities as they affect NMC assay. The 9975 container itself has proved to be a challenge for NDA work as it contains at least a 1/2 inches of heavy metal shielding as well as hydrogenous materials.
Date: July 10, 2003
Creator: Hodge, C.
Partner: UNT Libraries Government Documents Department

A New Neutron Multiplicity Counter for the Measurement of Impure Plutonium Metal at Westinghouse Savannah River Site

Description: A new neutron multiplicity counter has been designed, fabricated, characterized, and installed for use in the assay of impure plutonium metal buttons from the FB-Line at the Westinghouse Savannah River Site (WSRS). This instrument incorporates the performance characteristics of the Pyrochemical or In-plant Multiplicity Counter with the package size of the Plutonium Scrap Multiplicity Counter. In addition, state-of-the art features such as the de-randomizer circuit and separate ring outputs have been added. The counter consists of 113, 71 cm active length 3He tubes in a polyethylene moderator. Its efficiency for 252Cf is 57.8 percent, the highest of any multiplicity counter to date. Its die-away time is 50.4 ms and its deadtime is 50 ns. In this paper we will present the characterization data for the counter and the results of preliminary metal measurements at WSRS. We will also discuss the new challenges the impure metal buttons from FB-Line are presenting to the multiplicity counting technique.
Date: July 1, 1998
Creator: Baker, L.B.; Faison, D.M.; Langner, D.G.; Sweet, M.R.; Salazar, S.D. & Kroncke, K.E.
Partner: UNT Libraries Government Documents Department

Interpreting multiplicity-gated fragment distributions from heavy-ion collisions

Description: In recent years, multifragmentation of nuclear systems has been extensively studied, and many efforts have been made to clarify the underlying physics. However, no clear consensus exists on the mechanism for multifragmentation. Is the emission of intermediate mass fragments (IMF: 3 {le} Z {le} 20) a dynamical process (brought on by the occurrence of instabilities of one form or another) or a statistical process (i.e. the decay probabilities are proportional to a suitably defined exit channel phase space)? Historically the charge (mass) distribution has played and still plays a very important role in characterizing multifragmentation. Since this subject`s inception, the near power-law shape of the charge and mass distributions was considered an indication of criticality for the hot nuclear fluid produced in light ion and heavy ion collisions. Here, the authors have studied different aspects of the charge distributions. The implications of the experimental evidence presented here are potentially far reaching. On the one hand, the thermal features observed in the n-fragment emission probabilities for the {sup 36}Ar + {sup 197}Au reaction extend consistently to the charge distributions and strengthen the hypothesis of the important role of phase space in describing multifragmentation. On the other hand, they have investigated charge correlation functions of multi-fragment decays to search for the enhanced production of nearly equal-sized fragments predicted in several theoretical works.
Date: February 1, 1997
Creator: Phair, L.; Moretto, L.G.; Rubehn, T.; Wozniak, G.J.; Beaulieu, L.; Tso, K. et al.
Partner: UNT Libraries Government Documents Department

The azimuthal decorrelation of jets widely separated in rapidity

Description: We study the azimuthal decorrelation between jets with pseudorapidity separation up to six units. The data were accumulated using the D0 detector during the 1994-1995 collider run of the Fermilab Tevatron at {radical}s = 1.8 TeV. The data are compared to two parton shower Monte Carlos (HERWIG and PYTHIA) and an analytical prediction using the leading logarithmic BFKL resummation. The final state jets as predicted by the parton showering Monte Carlos describe the data over the entire pseudorapidity range studied. The prediction based on the leading logarithmic BFKL resummation shows more decorrelation than the data as the rapidity interval increases.
Date: November 1, 1997
Creator: Abbott, B.
Partner: UNT Libraries Government Documents Department

Theory of neutron emission in fission

Description: A survey of theoretical representations of two of the observables in neutron emission in fission is given, namely, the prompt fission neutron spectrum N(E) and the average prompt neutron multiplicity {bar {nu}}{sub p}. Early representations of the two observables are presented and their deficiencies are discussed. This is followed by summaries and some examples of recent theoretical models for the calculation of these quantities. Emphasis is placed upon the predictability and accuracy of the recent models. In particular, the dependencies of N(E) and {bar {nu}}{sub p} upon the fissioning nucleus and its excitation energy are treated in detail for the Los Alamos model. Recent work in the calculation of the prompt fission neutron spectrum matrix N(E, E{sub n}), where E{sub n} is the energy of the neutron inducing fission, is then discussed. Concluding remarks address the current status of the ability to calculate these observables with confidence, the direction of future theoretical efforts, and limitations to current (and future) approaches. This paper is an extension of a similar paper presented at the International Centre for Theoretical Physics in 1996.
Date: August 1998
Creator: Madland, D. G.
Partner: UNT Libraries Government Documents Department

Utilization of Baeten's Dead-Time Correction Formalism for Multiplicity Counting

Description: We evaluate a dead-time correction formalism for double and triple coincidences in multiplicity counting. We will describe the accuracy by which S (singles), D (doubles), and T (triples) (and consequently, the mass, multiplication, and alpha) of fissile material samples can be determined using this formalism.
Date: July 12, 1999
Creator: Gavron, A.
Partner: UNT Libraries Government Documents Department