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1

Ultra wide band 3-D cross section (RCS) holography  

SciTech Connect

Ultra wide band impulse holography is an exciting new concept for predictive radar cross section (RCS) evaluation employing near-field measurements. Reconstruction of the near-field hologram data maps the target`s scattering areas, and uniquely identifies the ``hot spot`` locations on the target. In addition, the target and calibration sphere`s plane wave angular spectrums are computed (via digital algorithm) and used to generate the target`s far-field RCS values in three dimensions for each frequency component in the impulse. Thin and thick targets are defined in terms of their near-field amplitude variations in range. Range gating and computer holographic techniques are applied to correct these variations. Preliminary experimental results on various targets verify the concept of RCS holography. The unique 3-D presentation (i.e., typically containing 524,288 RCS values for a 1024 {times} 512 sampled aperture for every frequency component) illustrates the efficacy of target recognition in terms of its far-field plane wave angular spectrum image. RCS images can then be viewed at different angles for target recognition, etc.

Collins, H.D.; Hall, T.E.

1992-07-01

2

Ultra wide band 3-D cross section (RCS) holography  

SciTech Connect

Ultra wide band impulse holography is an exciting new concept for predictive radar cross section (RCS) evaluation employing near-field measurements. Reconstruction of the near-field hologram data maps the target's scattering areas, and uniquely identifies the hot spot'' locations on the target. In addition, the target and calibration sphere's plane wave angular spectrums are computed (via digital algorithm) and used to generate the target's far-field RCS values in three dimensions for each frequency component in the impulse. Thin and thick targets are defined in terms of their near-field amplitude variations in range. Range gating and computer holographic techniques are applied to correct these variations. Preliminary experimental results on various targets verify the concept of RCS holography. The unique 3-D presentation (i.e., typically containing 524,288 RCS values for a 1024 {times} 512 sampled aperture for every frequency component) illustrates the efficacy of target recognition in terms of its far-field plane wave angular spectrum image. RCS images can then be viewed at different angles for target recognition, etc.

Collins, H.D.; Hall, T.E.

1992-07-01

3

Radar cross section of insects  

NASA Astrophysics Data System (ADS)

X-band measurements of radar cross section as a function of the angle between insect body axis and the plane of polarization are presented. A finding of particular interest is that in larger insects, maximum cross section occurs when the E-vector is perpendicular to the body axis. A new range of measurements on small insects (aphids, and planthoppers) is also described, and a comprehensive summary of insect cross-section data at X-band is given.

Riley, J. R.

1985-02-01

4

Estimating Radar Cross Section using Bayesian Image Restoration Richard O. Lane  

E-print Network

Estimating Radar Cross Section using Bayesian Image Restoration Richard O. Lane QinetiQ Malvern-dimensional radar cross section (RCS) of a vehicle given a radar image of the vehicle. A Markov chain Monte Carlo, the method may be applied to any type of radar image such as those produced by a synthetic aperture radar

Haddadi, Hamed

5

Radar-cross-section reduction of wind turbines. part 1.  

SciTech Connect

In recent years, increasing deployment of large wind-turbine farms has become an issue of growing concern for the radar community. The large radar cross section (RCS) presented by wind turbines interferes with radar operation, and the Doppler shift caused by blade rotation causes problems identifying and tracking moving targets. Each new wind-turbine farm installation must be carefully evaluated for potential disruption of radar operation for air defense, air traffic control, weather sensing, and other applications. Several approaches currently exist to minimize conflict between wind-turbine farms and radar installations, including procedural adjustments, radar upgrades, and proper choice of low-impact wind-farm sites, but each has problems with limited effectiveness or prohibitive cost. An alternative approach, heretofore not technically feasible, is to reduce the RCS of wind turbines to the extent that they can be installed near existing radar installations. This report summarizes efforts to reduce wind-turbine RCS, with a particular emphasis on the blades. The report begins with a survey of the wind-turbine RCS-reduction literature to establish a baseline for comparison. The following topics are then addressed: electromagnetic model development and validation, novel material development, integration into wind-turbine fabrication processes, integrated-absorber design, and wind-turbine RCS modeling. Related topics of interest, including alternative mitigation techniques (procedural, at-the-radar, etc.), an introduction to RCS and electromagnetic scattering, and RCS-reduction modeling techniques, can be found in a previous report.

Brock, Billy C.; Loui, Hung; McDonald, Jacob J.; Paquette, Joshua A.; Calkins, David A.; Miller, William K.; Allen, Steven E.; Clem, Paul Gilbert; Patitz, Ward E.

2012-03-05

6

Thin AMC Structure for Radar Cross-Section Reduction  

Microsoft Academic Search

A thin artificial magnetic conductor (AMC) structure is designed and breadboarded for radar cross-section (RCS) Reduction applications. The design presented in this paper shows the advantage of geometrical simplicity while simultaneously reducing the overall thickness (for the current design ). The design is very pragmatic and is based on a combination of AMC and perfect electric conductor (PEC) cells in

Maurice Paquay; Juan-Carlos Iriarte; Iñigo Ederra; Ramon Gonzalo; Peter de Maagt

2007-01-01

7

Automation of an RCS (Radar Cross Section) measurement system and its application to investigate the electromagnetic scattering from scale model aircraft canopies  

NASA Astrophysics Data System (ADS)

The purpose of this study was twofold, the first objective was to complete the development of AFIT's Far-Field Radar Range with a fully automated measurement process. The second objective was to use the facility to investigate the scattering of metallic versus transparent aircraft canopies relative to the scattering of the total aircraft. The approach for the investigation was: (1) to measure scale model aircraft to determine the effect of the RCS of the canopy/cockpit area on the RCS of the total aircraft; and (2) to design and measure a test body which would isolate the canopy/cockpit area from the rest of the aircraft. The result of the work on the first task is a software package called AFIT RCS Measurement Software (ARMS). The successful performance of the far-field range was validated by very favorable comparisons with the Wright Research and Development Center's anechoic chamber. The scale model measurements suggest at most a 5 dB difference between the scattering from the two extreme cases. The test body, however, clearly demonstrated differences up to 20 dB at certain frequencies. This study documents the upper and lower bounds of the subject measurements in an indoor measurement range. The Air Force has expressed interest in steering the investigation to examine materials and/or canopy construction.

Owens, Scott A.

1989-12-01

8

RCS analysis of canonical, two-dimensional material-loaded cavities with rectangular and circular cross sections  

Microsoft Academic Search

A rigorous radar cross section (rcs) analysis of canonical, two-dimensional material-loaded cavities with rectangular and\\u000a circular cross sections is carried out using the Wiener-Hopf technique and the Riemann-Hilbert problem technique, respectively.\\u000a Both E and H polarizations are treated. It is shown via numerical examples that the absorbing layer loading inside the cavities\\u000a gives rise to the significant rcs reduction. The

Kazuya Kobayashi; Alexander I. Nosich

1995-01-01

9

Shuttle orbiter radar cross-sectional analysis  

NASA Technical Reports Server (NTRS)

Theoretical and model simulation studies on signal to noise levels and shuttle radar cross section are described. Pre-mission system calibrations, system configuration, and postmission system calibration of the tracking radars are described. Conversion of target range, azimuth, and elevation into radar centered east north vertical position coordinates are evaluated. The location of the impinging rf energy with respect to the target vehicles body axis triad is calculated. Cross section correlation between the two radars is presented.

Cooper, D. W.; James, R.

1979-01-01

10

A new approach to radar cross-section compact range  

NASA Astrophysics Data System (ADS)

A new concept in compact range antenna systems provides increased dynamic range and reflector efficiency of 50 to 70 percent. The technology is based on beam shaping concepts that have been applied to solve chamber coupling problems of present systems. The result is a substantial step forward in the test and design capabilities for ultra low radar cross-section (RCS) testing with available systems for targets up to 40 feet long.

Harrison, T.

1986-06-01

11

Topics for a statistical description of radar cross section  

NASA Astrophysics Data System (ADS)

A comprehensive guide to the statistical description of radar cross section (RCS) is presented. The topics discussed include: definition of field quantities and Maxwell's equations, constitutive relations, boundary conditions and surface currents, Green's functions, diffraction of a plane wave by a perfectly absorbing half-plane, asymptotic approximation methods, and diffraction approximation methods. Also considered are: numerical approximations and numerical methods, RCS measurements, RCS of simple and complex shapes, new method for comparing experimental and theoretical data, elements of detection theory, impedance boundary condition, reflection and transmission, stratified media, gyroelectromagnetic layers, and the inverse problem for biaxial materials. As examples, the 727 at 0.94 GHz and the Firebee at 9.0 GHz are examined.

Maffett, Andrew Lewis

12

High-frequency RCS of open cavities with rectangular and circular cross sections  

NASA Technical Reports Server (NTRS)

The radar cross-section (RCS) analysis of open-ended cavities with rectangular and circular cross sections is carried out using the waveguide modal approach and the shooting-and-bouncing ray (SBR) approach. For a cavity opening on the order of ten wavelengths or larger, the comparison between the two approaches is excellent. It is also observed that at lower frequencies the SBR results deviate from the more accurate modal results. On the other hand, the SBR approach allows for greater flexibility in geometrical modeling, and can be applied to problems where waveguide modes cannot be easily found. SBR results for an offset rectangular cavity and a circular cavity with rounded endplate are presented.

Ling, Hao; Lee, Shung-Wu; Chou, Ri-Chee

1989-01-01

13

Useful Analytical Formulae for Near-Field Monostatic Radar Cross Section Under the Physical Optics: Far-Field Criterion  

Microsoft Academic Search

Radar cross section (RCS) is usually defined in the far-field zone. In this case, RCS is independent of the range of the radar from the object. However, in several scenarios, like for military applications or measurements led in anechoic chambers, the object is located in the near-field zone. From the physical optics (PO) approximation and from some simplifying assumptions, this

Christophe Bourlier; Philippe Pouliguen

2009-01-01

14

JPRS report: Science and technology. China: Radar cross section studies  

NASA Astrophysics Data System (ADS)

s of research in radar cross sections, target scattering, analysis of electromagnetic characteristics of a 3-D dielectric radome by complex astigmatic wave theory, and analysis of target radar cross sections by complex ray expansion are given.

1991-04-01

15

Lunar Radar Cross Section at Low Frequency  

NASA Technical Reports Server (NTRS)

Recent bistatic measurements of the lunar radar cross-section have extended the spectrum to long radio wavelength. We have utilized the HF Active Auroral Research Program (HAARP) radar facility near Gakona, Alaska to transmit high power pulses at 8.075 MHz to the Moon; the echo pulses were received onboard the NASA/WIND spacecraft by the WAVES HF receiver. This lunar radar experiment follows our previous use of earth-based HF radar with satellites to conduct space experiments. The spacecraft was approaching the Moon for a scheduled orbit perturbation when our experiment of 13 September 2001 was conducted. During the two-hour experiment, the radial distance of the satellite from the Moon varied from 28 to 24 Rm, where Rm is in lunar radii.

Rodriguez, P.; Kennedy, E. J.; Kossey, P.; McCarrick, M.; Kaiser, M. L.; Bougeret, J.-L.; Tokarev, Y. V.

2002-01-01

16

Control of radar cross sections of electrically small high temperature superconducting antenna elements using a magnetic field  

NASA Astrophysics Data System (ADS)

The radar cross sections (RCS) of small circular loops made from YBCO high temperature superconductor are calculated as a function of applied magnetic field strength. It is shown that the RCS is reduced as the magnetic field increases, and that the effect is more pronounced as radiation resistance decreases. Two factors contributing to the RCS reductions are identified, firstly an increase in surface resistance with magnetic field, and secondly a detuning effect caused by a change in the loop input reactance. It is suggested that antennas might be made from superconductor as a means of controlling their RCS, rather than for improved efficiency.

Cook, G. G.; Khamas, S. K.

1994-06-01

17

Wideband radar cross section reduction using two-dimensional phase gradient metasurfaces  

NASA Astrophysics Data System (ADS)

Phase gradient metasurface (PGMs) are artificial surfaces that can provide pre-defined in-plane wave-vectors to manipulate the directions of refracted/reflected waves. In this Letter, we propose to achieve wideband radar cross section (RCS) reduction using two-dimensional (2D) PGMs. A 2D PGM was designed using a square combination of 49 split-ring sub-unit cells. The PGM can provide additional wave-vectors along the two in-plane directions simultaneously, leading to either surface wave conversion, deflected reflection, or diffuse reflection. Both the simulation and experiment results verified the wide-band, polarization-independent, high-efficiency RCS reduction induced by the 2D PGM.

Li, Yongfeng; Zhang, Jieqiu; Qu, Shaobo; Wang, Jiafu; Chen, Hongya; Xu, Zhuo; Zhang, Anxue

2014-06-01

18

Wideband radar cross section reduction using two-dimensional phase gradient metasurfaces  

SciTech Connect

Phase gradient metasurface (PGMs) are artificial surfaces that can provide pre-defined in-plane wave-vectors to manipulate the directions of refracted/reflected waves. In this Letter, we propose to achieve wideband radar cross section (RCS) reduction using two-dimensional (2D) PGMs. A 2D PGM was designed using a square combination of 49 split-ring sub-unit cells. The PGM can provide additional wave-vectors along the two in-plane directions simultaneously, leading to either surface wave conversion, deflected reflection, or diffuse reflection. Both the simulation and experiment results verified the wide-band, polarization-independent, high-efficiency RCS reduction induced by the 2D PGM.

Li, Yongfeng; Qu, Shaobo; Wang, Jiafu; Chen, Hongya [College of Science, Air Force Engineering University, Xi'an, Shaanxi 710051 (China); Zhang, Jieqiu [College of Science, Air Force Engineering University, Xi'an, Shaanxi 710051 (China); Electronic Materials Research Laboratory, Key Laboratory of Ministry of Education, Xi'an Jiaotong University, Xi'an, Shaanxi 710049 (China); Xu, Zhuo [Electronic Materials Research Laboratory, Key Laboratory of Ministry of Education, Xi'an Jiaotong University, Xi'an, Shaanxi 710049 (China); Zhang, Anxue [School of Electronics and Information Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049 (China)

2014-06-02

19

A study of radar cross section measurement techniques  

NASA Technical Reports Server (NTRS)

Past, present, and proposed future technologies for the measurement of radar cross section were studied. The purpose was to determine which method(s) could most advantageously be implemented in the large microwave anechoic chamber facility which is operated at the antenna test range site. The progression toward performing radar cross section measurements of space vehicles with which the Orbital Maneuvering Vehicle will be called upon to rendezvous and dock is a natural outgrowth of previous work conducted in recent years of developing a high accuracy range and velocity sensing radar system. The radar system was designed to support the rendezvous and docking of the Orbital Maneuvering Vehicle with various other space vehicles. The measurement of radar cross sections of space vehicles will be necessary in order to plan properly for Orbital Maneuvering Vehicle rendezvous and docking assignments. The methods which were studied include: standard far-field measurements; reflector-type compact range measurements; lens-type compact range measurement; near field/far field transformations; and computer predictive modeling. The feasibility of each approach is examined.

Mcdonald, Malcolm W.

1986-01-01

20

Reduction of the radar cross section of arbitrarily shaped cavity structures  

NASA Technical Reports Server (NTRS)

The problem of the reduction of the radar cross section (RCS) of open-ended cavities was studied. The issues investigated were reduction through lossy coating materials on the inner cavity wall and reduction through shaping of the cavity. A method was presented to calculate the RCS of any arbitrarily shaped structure in order to study the shaping problem. The limitations of this method were also addressed. The modal attenuation was studied in a multilayered coated waveguide. It was shown that by employing two layers of coating, it was possible to achieve an increase in both the magnitude of attenuation and the frequency band of effectiveness. The numerical method used in finding the roots of the characteristic equation breaks down when the coating thickness is very lossy and large in terms of wavelength. A new method of computing the RCS of an arbitrary cavity was applied to study the effects of longitudinal bending on RCS reduction. The ray and modal descriptions for the fields in a parallel plate waveguide were compared. To extend the range of validity of the Shooting and Bouncing Ray (SBR) method, the simple ray picture must be modified to account for the beam blurring.

Chou, R.; Ling, H.; Lee, S. W.

1987-01-01

21

Graphene based tunable fractal Hilbert curve array broadband radar absorbing screen for radar cross section reduction  

SciTech Connect

This paper proposes a new type of graphene based tunable radar absorbing screen. The absorbing screen consists of Hilbert curve metal strip array and chemical vapour deposition (CVD) graphene sheet. The graphene based screen is not only tunable when the chemical potential of the graphene changes, but also has broadband effective absorption. The absorption bandwidth is from 8.9GHz to 18.1GHz, ie., relative bandwidth of more than 68%, at chemical potential of 0eV, which is significantly wider than that if the graphene sheet had not been employed. As the chemical potential varies from 0 to 0.4eV, the central frequency of the screen can be tuned from 13.5GHz to 19.0GHz. In the proposed structure, Hilbert curve metal strip array was designed to provide multiple narrow band resonances, whereas the graphene sheet directly underneath the metal strip array provides tunability and averagely required surface resistance so to significantly extend the screen operation bandwidth by providing broadband impedance matching and absorption. In addition, the thickness of the screen has been optimized to achieve nearly the minimum thickness limitation for a nonmagnetic absorber. The working principle of this absorbing screen is studied in details, and performance under various incident angles is presented. This work extends applications of graphene into tunable microwave radar cross section (RCS) reduction applications.

Huang, Xianjun, E-mail: xianjun.huang@manchester.ac.uk [School of Electrical and Electronic Engineering, University of Manchester, Manchester M13 9PL (United Kingdom); College of Electronic Science and Engineering, National University of Defense Technology, Changsha 410073 (China); Hu, Zhirun [School of Electrical and Electronic Engineering, University of Manchester, Manchester M13 9PL (United Kingdom); Liu, Peiguo [College of Electronic Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

2014-11-15

22

Graphene based tunable fractal Hilbert curve array broadband radar absorbing screen for radar cross section reduction  

NASA Astrophysics Data System (ADS)

This paper proposes a new type of graphene based tunable radar absorbing screen. The absorbing screen consists of Hilbert curve metal strip array and chemical vapour deposition (CVD) graphene sheet. The graphene based screen is not only tunable when the chemical potential of the graphene changes, but also has broadband effective absorption. The absorption bandwidth is from 8.9GHz to 18.1GHz, ie., relative bandwidth of more than 68%, at chemical potential of 0eV, which is significantly wider than that if the graphene sheet had not been employed. As the chemical potential varies from 0 to 0.4eV, the central frequency of the screen can be tuned from 13.5GHz to 19.0GHz. In the proposed structure, Hilbert curve metal strip array was designed to provide multiple narrow band resonances, whereas the graphene sheet directly underneath the metal strip array provides tunability and averagely required surface resistance so to significantly extend the screen operation bandwidth by providing broadband impedance matching and absorption. In addition, the thickness of the screen has been optimized to achieve nearly the minimum thickness limitation for a nonmagnetic absorber. The working principle of this absorbing screen is studied in details, and performance under various incident angles is presented. This work extends applications of graphene into tunable microwave radar cross section (RCS) reduction applications.

Huang, Xianjun; Hu, Zhirun; Liu, Peiguo

2014-11-01

23

Planar near-field scanning for compact range bistatic radar cross-section measurement. Thesis Final Report  

NASA Technical Reports Server (NTRS)

The design, construction, and testing of a low cost, planar scanning system to be used in a compact range environment for bistatic radar cross-section (bistatic RCS) measurement data are discussed. This scanning system is similar to structures used for measuring near-field antenna patterns. A synthetic aperture technique is used for plane wave reception. System testing entailed comparison of measured and theoretical bistatic RCS of a sphere and a right circular cylinder. Bistatic scattering analysis of the ogival target support, target and pedestal interactions, and compact range room was necessary to determine measurement validity.

Tuhela-Reuning, S. R.; Walton, E. K.

1991-01-01

24

A microwave anechoic chamber for radar-cross section measurement  

Microsoft Academic Search

A microwave anechoic chamber has been developed at the Department of Electrical Engineering, University of Malaya, for monostatic and bistatic radar-cross-section measurements. The structure of the chamber is a quarter-section geodesic dome, with a 12 foot radius, and raised three feet above the floor. An antenna railing system is installed inside the chamber. The antennas can be moved along the

B. K. Chung; H. T. Chuah; J. W. Bredow

1997-01-01

25

Comparison of monostatic Doppler and radar cross-section spectra by rotating multiple skew-plated metal fan blades  

Microsoft Academic Search

Comparison of monostatic Doppler and radar cross-section spectra (RCS spectra) for rotating multiple skew-plated metal Tan blades, in the presence of a linearly polarized EM wave, are investigated. The high frequency backscatter of such a slowly rotating and electrically large blade is based on the quasi-stationary method together with PO\\/PTD (physical optics\\/physical theory of diffraction) equivalent currents techniques. Only the

TAI-LIN YANG; SHEAU-SHONG BOR

1992-01-01

26

Bistatic and Multistatic Radar: Surveillance, Countermeasures, and Radar Cross Sections. (Latest citations from the Aerospace Database)  

NASA Technical Reports Server (NTRS)

The bibliography contains citations concerning the design, development, testing, and evaluation of bistatic and multistatic radar used in surveillance and countermeasure technology. Citations discuss radar cross sections, target recognition and characteristics, ghost recognition, motion image compensation, and wavelet analysis. Stealth aircraft design, stealth target tracking, synthetic aperture radar, and space applications are examined.

1998-01-01

27

Bistatic and Multistatic Radar: Surveillance, Countermeasures, and Radar Cross Sections. (Latest Citations from the Aerospace Database)  

NASA Technical Reports Server (NTRS)

The bibliography contains citations concerning the design, development, testing, and evaluation of bistatic and multistatic radar used in surveillance and countermeasure technology. Citations discuss radar cross sections, target recognition and characteristics, ghost recognition, motion image compensation, and wavelet analysis. Stealth aircraft design, stealth target tracking, synthetic aperture radar, and space applications are examined.

1997-01-01

28

Improvements to the finite-difference time-domain method for calculating the radar cross section of a perfectly conducting target  

Microsoft Academic Search

Several improvements to the finite-difference time-domain (FDTD) method for calculating the radar cross section (RCS) of a perfectly conducting target are presented. Sinusoidal and pulsed FDTD excitations are compared to determine an efficient method of finding the frequency response of targets. The maximum cell size, the minimum number of external cells, and a method to eliminate field storage in the

C. M. Furse; S. P. Mathur; O. P. Gandhi

1990-01-01

29

Microwave radar cross sections and Doppler velocities measured in the surf zone  

Microsoft Academic Search

The relationship between microwave imaging radar measurements of fluid velocities in the surf zone and shoaling, breaking, and broken waves is studied with field observations. Normalized radar cross section (NRCS) and Doppler velocity are estimated from microwave measurements at near-grazing angles, and in situ fluid velocities are measured with acoustic Doppler velocimeters (ADVs). Joint histograms of radar cross section and

Gordon Farquharson; Stephen J. Frasier; Britt Raubenheimer; Steve Elgar

2005-01-01

30

Improving on the monostatic radar cross section of targets by employing sea clutter to emulate a bistatic radar  

Microsoft Academic Search

Aircraft that employs radar cross-section reduction techniques typically have a significantly larger bistatic radar cross-section. This paper discusses the possibility of utilising an airborne monostatic radar configuration over an oceanic region to emulate a bistatic radar. This is achieved by employing the reflective nature of the ever-present sea clutter to effectively create a \\

J. Palmer; J. Homer; B. Mojarrabi

2003-01-01

31

RCS of two-dimensional structures consisting of both dielectrics and conductors of arbitrary cross section  

Microsoft Academic Search

The problem of determining the electromagnetic field scattered by two-dimensional structures consisting of both dielectric and conducting cylinders of arbitrary cross section is considered. The conductors may be in the form of strips and the dielectrics may be in the form of the shells. The conductors may be partially or fully covered by dielectric layers, while the dielectrics may be

Ercument Arvas; Tapan K. Sarkar

1989-01-01

32

Radar Cross Section Studies/Compact Range Research  

NASA Technical Reports Server (NTRS)

A summary is given of the achievements of NASA Grant NsG-1613 by Ohio State University from May 1, 1987 to April 30, 1988. The major topics covered are as follows: (1) electromagnetic scattering analysis; (2) indoor scattering measurement systems; (3) RCS control; (4) waveform processing techniques; (5) material scattering and design studies; (6) design and evaluation of design studies; and (7) antenna studies. Major progress has been made in each of these areas as verified by the numerous publications produced.

Burnside, W. D.; Dominek, A. K.; Gupta, I. J.; Newman, E. H.; Pathak, P. H.; Peters, L., Jr.

1988-01-01

33

Radar cross section studies/compact range research  

NASA Technical Reports Server (NTRS)

Achievements in advancing the state-of-the-art in the measurement, control, and analysis of electromagnetic scattering from general aerodynamic targets are summarized. The major topics associated with this study include: (1) electromagnetic scattering analysis; (2) indoor scattering measurement systems; (3) RCS control; (4) waveform processing techniques; (5) material scattering and design studies; (6) design and evaluation of standard targets; and (7) antenna studies. Progress in each of these areas is reported and related publications are listed.

Burnside, W. D.; Dominek, A. K.; Gupta, I. J.; Newman, E. H.; Pathak, P. H.; Peters, L., Jr.

1989-01-01

34

Edge diffraction effects on the RCS analysis of antenna array  

Microsoft Academic Search

Diffraction effects of the edge region within the antenna array aperture have been discussed with the numerical simulation and measurement in the antenna array monostatic Radar Cross Section (RCS) analysis. Research illustrates that the edge of array presents dominant diffraction effects on the antenna mode RCS character evaluation in a wide frequency range, and bistatic RCS character proposes Radar Absorbing

Zhi Xu; Xuequan Yan; Zhenghe Feng; Shuxi Gong; Qizhong Liu

2010-01-01

35

Microwave image understanding and its application to radar cross section management  

NASA Astrophysics Data System (ADS)

The basic scattering properties of a perfectly conducting object are briefly reviewed. In the high frequency region, the scattered field of a complex shaped object can be attributed to a combination of several mechanisms. The advent of high resolution radar enables the consideration of each scattering mechanism separately. The microwave image of a conducting object is interpreted from a new approach, based on the understanding of the scattering mechanism and the image reconstruction algorithm. The connection between various scattering mechanisms and their reconstructed images is then established. Several numerical and experimental examples were included to support this interpretative approach. The algorithm to extrapolate the available data into the mission bands is developed. The term, diaphanization, defined as the technique of reducing RCS and the technique of obscuring an image is introduced. The RCS management is considered not only from a detection perspective, namely the reduction of the target's RCS to elude radar detection, but also from the image point of view where disguising of a target's appearance to impede recognition by an imaging radar is sought. The procedure which employs microwave diversity imaging to diaphanize a target over prescribed spectral and angular windows is given and the robustness of the diversity imaging system to the Gaussian noise is demonstrated. Tradiational techniques for reducing the RCS are applied to RCS magnagement studies.

Li, Hsueh-Jyh

36

Comparing EM Models to RCS Measurements for Building-Penetration Radar  

SciTech Connect

For the DARPA VisiBuilding program, SRI International and Lawrence Livermore National Laboratory are using a variety of electromagnetic (EM) simulation codes and measurement techniques to analyze how radar pulses interact with building structures and materials. Of primary interest is how interior wall and corner reflections are delayed, attenuated, and dispersed by the exterior wall materials. In this paper, we compare microwave frequency-domain radar cross section (RCS) chamber measurements of scale models of simple buildings to finite-element and finite-difference full-wave time-domain and ray-tracing models. The ability to accurately reconstruct the building from these models is compared with the reconstruction from chamber measurements. We observe that careful attention to the spatial sampling in the EM models is essential to achieving good reconstruction at the higher frequencies.

Fasenfest, B; Ueberschaer, R

2007-05-18

37

Backscattering analysis of flat plate and dihedral corner reflectors using PO and comparison with RCS measurements in anechoic chamber  

Microsoft Academic Search

Physical Optics (PO) is used to calculate Radar Cross Section (RCS) of flat plate and dihedral corner reflectors. The numerical results obtained via simulation are used to compare the RCS measured for these targets recovered and non-recovered with Radar Absorbing Materials (RAM). All simulations and experiments are effectuated in a frequency of 10 GHz. Experimental measurements using Radar Cross Section

L. A. Andrade; E. L. Nohara; G. G. Peixoto; M. C. Rezende; I. M. Martin

2003-01-01

38

A NEW MULTI-FREQUENCY VIBRATIONAL GENETIC ALGORITHM IN RADAR CROSS SECTION MINIMIZATION PROBLEMS  

Microsoft Academic Search

Within this study, it is aimed to provide an efficient stochastic algorithm for different optimization problems. For this purpose, as a search method, multi frequency vibrational genetic algorithm (m-VGA) is improved and used to accelerate the genetic algorithm for radar cross section minimization problem. From the results obtained, it is concluded that m-VGA decreased the required time for the minimized

Y. Volkan PEHLIVANOGLU

39

Comparison of monostatic and bistatic bearing estimation performance for low RCS targets  

Microsoft Academic Search

Bistatic radars, specifically forward-scatter radars, are proposed as an alternative to standard monostatic radars against targets whose radar cross sections (RCS) have been reduced by passive means. Forward-scatter radars operate by detecting echoes from a targets forward-scatter RCS, which is insensitive to effects of passive RCS reduction techniques. However, the performance of the forward-scatter radar is compromised when the angular

R. J. Boyle; Wasyl Wasylkiwskyj

1994-01-01

40

Scattering cross section of mesospheric echoes and turbulence parameters from gadanki radar observations  

NASA Astrophysics Data System (ADS)

We present a comprehensive study on radar scattering cross section of mesospheric echoes and mesospheric turbulence parameters based on several days of observations made in connection with two rocket-radar campaigns, one in July 2004 and another in April 2005, meant for studying mesospheric turbulence. Radar scattering cross section was found to have large local time and day-to-day variability and was found to be as low as 4x10-20 m-1 and as high as 6x10-16 m-1 with their median values 5x10-20- 8x10-18 m-1. Echoes connected with the low value of scattering cross section could be detected using a long pulse width when background noise was about one order less than those at other times. Intriguingly, the median value of scattering cross section is found to increase with height. Turbulence parameters are found to vary remarkably from one day to another. In July, the TKE dissipation rate, out scale and inner scale were 0.1-150 mW/kg, 33-1460 m, and 2-50 m, respectively, and their median values were 4.5-50 mW/kg, 295-980 m, and 2-37 m, respectively. In April, these estimates were 0.5-27 mW/kg, 80-615 m, and 5-20 m, respectively, and their median values were 1-11 mW/kg, 130-360 m, and 8-15 m, respectively. These parameters are found to agree quite well with those estimated from rocket-borne observations, which were 4-117 mW/kg, 220-1475 m, and 15-31 m, respectively, in July and 2-36 mW/kg, 170-680 m, and 17-37 m, respectively, in April. Interestingly, the inner and outer scales estimated using both radar and rocket observations are found to be agree exceedingly well with model values. These results are compared in detail with those reported from low, middle and high latitudes including model and discussed in the light of current knowledge on the mesospheric turbulence.

Dharmalingam, Selvaraj; Sinha, H. S. S.; Chandra, Harish; Patra, Amit; Das, Uma

41

A Monostatic Ocean Scattering Cross Section for the Case of Surface Wave Radar Operating from a Floating Barge  

Microsoft Academic Search

An understanding of the parameters affecting the high frequency surface wave radar (HFSWR) cross sections of the ocean surface is essential to employing such formulations in remote sensing models. Available techniques to date have not explicitly included the effect of antenna motion on the ocean clutter spectra derived from HF Doppler radar data. Here, a model, which assumes the incident

John Walsh; Eric Gill; Weimin Huang

2008-01-01

42

Remote Cloud Sensing Intensive Observation Period (RCS-IOP) millimeter-wave radar calibration and data intercomparison  

SciTech Connect

During April 1994, the University of Massachusetts (UMass) and the Pennsylvania State University (Penn State) fielded two millimeter-wave atmospheric radars in the Atmospheric Radiation Measurement Remote Cloud Sensing Intensive Operation Period (RCS-IOP) experiment. The UMass Cloud Profiling Radar System (CPRS) operates simultaneously at 33.12 GHz and 94.92 GHz through a single antenna. The Penn State radar operates at 93.95 GHz and has separate transmitting and receiving antennas. The two systems were separated by approximately 75 meters and simultaneously observed a variety of cloud types at verticle incidence over the course of the experiment. This abstract presents some initial results from our calibration efforts. An absolute calibration of the UMass radar was made from radar measurements of a trihedral corner reflector, which has a known radar cross-section. A relative calibration of between the Penn State and UMass radars is made from the statistical comparison of zenith pointing measurements of low altitude liquid clouds. Attenuation is removed with the aid of radiosonde data, and the difference in the calibration between the UMass and Penn State radars is determined by comparing the ratio of 94-GHz and 95-GHz reflectivity values to a model that accounts for parallax effects of the two antennas used in the Penn State system.

Sekelsky, S.M.; Firda, J.M.; McIntosh, R.E. [Univ. of Massachusetts, Amherst, MA (United States)] [and others

1996-04-01

43

Scattering cross section of mesospheric echoes and turbulence parameters from Gadanki radar observations  

NASA Astrophysics Data System (ADS)

We present a comprehensive study on radar scattering cross section of mesospheric echoes and mesospheric turbulence parameters based on several days of observations made during two rocket-radar campaigns, one in July 2004 and another in April 2005, meant for studying mesospheric turbulence. Radar scattering cross section was found to have large local time and day-to-day variability and was found to be as low as 3.1×10-18 m-1 and as high as 1×10-14 m-1 and the median values were in the range of 4.4×10-18-4.7×10-16 m-1. Echoes connected with the low value of scattering cross section could be detected only when a long pulse width was used. Turbulence parameters were found to vary remarkably with time of the day and also from one day to another. In July, the turbulent kinetic energy (TKE) dissipation rate, outer scale and inner scale were in the range of 0.08-150 mW/kg, 33-1500 m, and 1.9-50 m, respectively, and their median values were in the range of 5-52 mW/kg, 293-977 m, and 2-31 m, respectively. In April, these estimates were in the range of 0.9-69 mW/kg, 38-1081 m, and 4-21 m, respectively, and their median values were in the range of 1-12 mW/kg, 140-378 m, and 8-13 m, respectively. These parameters are found to agree quite well with those estimated from rocket-borne observations, which were in the range of 4-117 mW/kg, 220-1475 m, and 15-31 m, respectively, in July and 2-36 mW/kg, 170-680 m, and 17-37 m, respectively, in April. Interestingly, the inner and outer scales estimated using both radar and rocket observations agree exceedingly well with model values. These results are compared in detail with those reported from low, middle and high latitudes including model and discussed in the light of current knowledge of mesospheric turbulence.

Selvaraj, D.; Patra, A. K.; Chandra, H.; Sinha, H. S. S.; Das, U.

2014-11-01

44

Detection and interpretation of ocean roughness variations across the Gulf Stream inferred from radar cross section observations  

NASA Technical Reports Server (NTRS)

Radar cross section data shows that the Gulf Stream has a higher cross section per unit area (interpreted here as a greater roughness) than the water on the continental shelf. A steep gradient in cross section was often seen at the expected location of the western boundary. There were also longer-scale (10-20 km) gradual fluctuations within the stream of significant magnitude. These roughness variations are correlated with the surface shear stress that the local wind imposes on the sea. Using the available surface-truth information concerning the wind speed and direction, an assumed Gulf Stream velocity profile, and high-resolution ocean-surface temperature data obtained by the VHRR onboard a NOAA-NESS polar-orbiting satellite, the present study demonstrates that the computed surface stress variation bears a striking resemblance to the measured radar cross-section variations.

Weissman, D. E.; Thompson, T. W.

1977-01-01

45

RCS Analysis of Plate Geometries, parts 1 and 2  

NASA Technical Reports Server (NTRS)

High-frequency techniques for Radar Cross Section (RCS) prediction of plate geometries and a physical optics/equivalent currents model for the RCS of trihedral corner reflectors are addressed. In part 1, a Uniform Theory of Diffraction (UTD) model for the principal-plane radar cross section (RCS) of a perfectly conducting, rectangular plate coated on one side with an electrically thin, lossy dielectric is presented. In part 2, the scattering in the interior regions of both square and triangular trihedral corner reflectors are examined.

Balanis, Constantine A.; Polka, Lesley A.; Polycarpou, Anastasis C.

1993-01-01

46

Simultaneous ocean cross-section and rainfall measurements from space with a nadir-pointing radar  

NASA Technical Reports Server (NTRS)

A method to determine simultaneously the rainfall rate and the normalized backscattering cross section of the surface was evaluated. The method is based on the mirror reflected power, p sub m which corresponds to the portion of the incident power scattered from the surface to the precipitation, intercepted by the precipitation, and again returned to the surface where it is scattered a final time back to the antenna. Two approximations are obtained for P sub m depending on whether the field of view at the surface is either much greater or much less than the height of the reflection layer. Since the dependence of P sub m on the backscattering cross section of the surface differs in the two cases, two algorithms are given by which the path averaged rain rate and normalized cross section are deduced. The detectability of P sub m, the relative strength of other contributions to the return power arriving simultaneous with P sub m, and the validity of the approximations used in deriving P sub m are discussed.

Meneghini, R.; Atlas, D.

1984-01-01

47

Radar cross-section measurements and simulation of a tethered satellite. The small expendable deployer system end-mass payload  

NASA Technical Reports Server (NTRS)

The first Small Expendable Deployer System (SEDS-1), a tethered satellite system, was developed by NASA and launched March 29, 1993 as a secondary payload on a United State Air Force (USAF) Delta-2 launch vehicle. The SEDS-1 successfully deployed an instrumented end-mass payload (EMP) on a 20-km nonconducting tether from the second stage of the Delta 2. This paper describes the effort of NASA Langley Research Center's Antenna and Microwave Research Branch to provide assistance to the SEDS Investigators Working Group (IWG) in determining EMP dynamics by analyzing the mission radar skin track data. The radar cross section measurements taken and simulations done for this study are described and comparisons of the measured data with the simulated data for the EMP at 6 GHz are presented.

Cravey, Robin L.; Fralick, Dion T.; Vedeler, Erik

1995-01-01

48

Global and high resolution radar cross section measurements and two-dimensional microwave images of a scaled aircraft model from the type Airbus A 310  

Microsoft Academic Search

The results from radar cross section high resolution measurements of a metallized scaled model of a usual airliner of the Airbus A310 type are presented. The measurements were performed for line polarization states by using a coherent short pulse radar at a frequency of 12.5 GHz. Two dimensional microwave images were generated for varied aspect angles by using inverse synthetic

Karl-Heinz Bethke

1991-01-01

49

Vibrational genetic algorithm enhanced with neural networks in RCS problems  

Microsoft Academic Search

Purpose – The purpose of this paper is to develop a new genetic optimization strategy which provides computationally more efficient and accurate solutions, and to provide practically applicable optimization method in radar cross-section (RCS) minimization problems. Design\\/methodology\\/approach – The problem of RCS minimization for three-dimensional air vehicle is considered. New computationally efficient optimization tool; neural networks (NNs) coupled multi-frequency vibrational

Y. Volkan Pehlivanoglu; Oktay Baysal

2011-01-01

50

Intensity scintillation index and mean apparent radar cross section on monostatic and bistatic paths  

Microsoft Academic Search

An expression is developed for the intensity scintillation index on a two-way (radar) path, in terms of the one-way index and the correlation between scintillations produced on the uplink and downlink. The expression is appropriate for monostatic (fully correlated) and bistatic (totally or partially uncorrelated, or anticorrelated) paths whose links are statistically similar and obey Nakagami m statistics. A companion

E. J. Fremouw; Akira Ishimaru

1992-01-01

51

Assessment of orbital debris size estimation from radar cross-section measurements  

Microsoft Academic Search

MIT Lincoln Laboratory has conducted a measurement program for man-made orbital debris since 1991 in response to NASA's need to characterize the orbital debris population and facilitate manned spaceflight activities. The primary sensors used in that effort are the Haystack and Haystack auxiliary (HAX) radars located at the Lincoln space surveillance complex (LSSC) in Westford, Massachusetts. This paper will describe

R. Lambour; N. Rajan; T. Morgan; I. Kupiec; E. Stansbery

2004-01-01

52

An improved composite surface model for the radar backscattering cross section of the ocean surface 2. Model response to surface roughness variations and the radar imaging of underwater bottom topography  

Microsoft Academic Search

In the companion paper we have presented an improved composite surface model for the calculation of normalized radar backscattering cross sections (NRCS) of the ocean surface. The proposed model accounts for the impact of the full two-dimensional ocean wave spectrum on the radar backscatter and was shown to reproduce measured absolute NRCS values for a variety of radar configurations and

Roland Romeiser; Werner Alpers

1997-01-01

53

Dismount modeling and detection from small aperture moving radar platforms  

Microsoft Academic Search

Future advanced radar systems must detect targets of diminishing radar cross section (RCS) at low radial velocity, in demanding clutter and interference environments. Presently, a deficiency in radar detection performance exists between the capabilities of synthetic aperture radar (SAR) for fixed target indication and space-time adaptive processing (STAP) for ground moving target indication (GMTI) of targets with low ground track

R. K. Hersey; W. L. Melvin; E. Culpepper

2008-01-01

54

Cross-section of coherent radar scattering from nonthermal plasma density fluctuations in the mid-latitude ionosphere  

NASA Astrophysics Data System (ADS)

Methods based on coherent radar scattering yield very important information about nonthermal plasma density fluctuations in the lower ionosphere at different latitudes In particular the information is helpful for better understanding of the nature of the fluctuations A noticeable role in producing the fluctuations below the homopause level belongs to neutral air turbulence The turbulence is especially important in the case when development of plasma instabilities is difficult A convenient value that describes the process of radio wave coherent scattering from plasma density fluctuations is an effective cross-section sigma An analytic formula of sigma for the plasma fluctuations induced by the neutral turbulence is presented in the report The formula is obtained with the use of the 3D fluctuation spectrum predicted by a quasi-neutral fluid theory of the fluctuations Using the formula we estimated values of sigma for a possible radar backscatter experiment in the case of plasma fluctuations near the 100-km altitude in the daytime and nighttime mid-latitude ionosphere the magnetic dip angle of 45° The local values for the length-scale of the vertical plasma-density gradient L N of about 7 km and the average plasma density N e of 2 times10 10 mathrm m -3 plasma frequency f p approx 1 27 MHz were chosen for the daytime ionosphere and L N approx 3 km N e approx 2 times10 9 mathrm m -3 f p approx 0 4 MHz at night The ratio of the ion gyro-frequency to the ion-neutral collision frequency of about 0 035 and the

Kyzyurov, Yu.

55

Radar cross section studies  

NASA Technical Reports Server (NTRS)

The ultimate goal is to generate experimental techniques and computer codes of rather general capability that would enable the aerospace industry to evaluate the scattering properties of aerodynamic shapes. Another goal involves developing an understanding of scattering mechanisms so that modification of the vehicular structure could be introduced within constraints set by aerodynamics. The development of indoor scattering measurement systems with special attention given to the compact range is another goal. There has been considerable progress in advancing state-of-the-art scattering measurements and control and analysis of the electromagnetic scattering from general targets.

Burnside, W. D.; Dominek, A. K.; Gupta, I. J.; Newman, E. H.; Pathak, P. H.; Peters, L., Jr.

1987-01-01

56

Dependence of the Normalized Radar Cross Section of Water Waves on Bragg Wavelength-Wind Speed Sensitivity  

NASA Technical Reports Server (NTRS)

Measurements of the normalized radar cross section (sigma(sup o)) made by the YSCAT ultrawideband scatterometer during an extended deployment on the Canada Centre for Inland Waters(CCIW) Research Tower located at Lake Ontario are analyzed and compared with anemometer wind measurements to study the sensitivity of (sigma(sup o)) to the wind speed as a function of the Bragg wavelength. This paper concentrates on upwind and downwind azimuth angles in the wind speed range of 4.5-12 m/s. While YSCAT collected measurements of sigma(sup o) at a variety of frequencies and incidence angles, this paper focuses on frequencies of 2.0, 3.05, 5.30, 10.02, and 14.0 GHz and incidence angles within the Bragg regime, 30-50 deg. Adopting a power law model to describe the relationship between sigma(sup o) and wind speed, both wind speed exponents and upwind/downwind (u/d) ratios of sigma(sup o) are found using least squares linear regression. The analysis of the wind speed exponents and u/d ratios show that shorter Bragg wavelengths (Lambda less than 4 cm) are the most sensitive to wind speed and direction. Additionally, vertical polarization (V-pol) sigma(sup o) is shown to be more sensitive to wind speed than horizontal polarization (H-pol) sigma(sup o), while the H-pol u/d ratio is larger than the V-pol u/d ratio.

Long, David G.; Collyer, R. Scott; Reed, Ryan; Arnold, David V.

1996-01-01

57

Global and high resolution radar cross section measurements and two-dimensional microwave images of a scaled aircraft model from the type Airbus A 310  

NASA Astrophysics Data System (ADS)

The results from radar cross section high resolution measurements of a metallized scaled model of a usual airliner of the Airbus A310 type are presented. The measurements were performed for line polarization states by using a coherent short pulse radar at a frequency of 12.5 GHz. Two dimensional microwave images were generated for varied aspect angles by using inverse synthetic aperture principles to obtain an exact identification of each scattering center of the model. Polarization dependent back diffusions are particularly visible at the wing edges in the respective reflection images. The fins of airfoils are visible by vertical polarization for aspect angles from side views.

Bethke, Karl-Heinz

1991-06-01

58

Near-Nadiral Normalized Radar Cross Section of the SEA Surface at Ku, Ka, and W-Bands: Comparison of Measurements and Models  

NASA Technical Reports Server (NTRS)

Understanding the relationship between wind speed and direction and the near-nadiral normalized radar cross section (NRCS) of the sea surface is important in many oceanographic and atmospheric remote sensing applications: (1) wind speed retrievals in traditional altimeter systems (2) assistance in calibration and path integrated attenuation processing for atmospheric profiling radars The desired wind speed (and direction in some cases) retrieval requires a clear understanding of the relationship between the relevant geophysical quantities and the observed NRCS Such understanding is available from existing electromagnetic models, but the presence of many such models, as well as implicit descriptions of the sea surface, motivates continued evaluation of model performance.

Majurec, Ninoslav; Johnson, Joel T.; Tanelli, Simone; Durden, Stephen

2012-01-01

59

Observability of the scattering cross-section for strong and weak scattering  

Microsoft Academic Search

Jakeman's random walk model with step number fluctuations describes the amplitude scattered from a rough medium in terms as the coherent summation of (independent) individual scatterers' contributions. For a population following a birth-death-immigration (BDI) model, the resulting statistics are K -distributed and the multiplicative representation of the amplitude as a Gaussian speckle modulated by a Gamma radar cross-section (RCS) is

Patrick Fayard

2010-01-01

60

Recruit an ANA for RCS tests  

NASA Astrophysics Data System (ADS)

For the conduction of valid radar cross-section (RCS) measurements, it is necessary to remove unwanted signals from the test data. However, the absolute accuracy of the measurements is limited because even the most carefully designed anechoic chamber allows some residual energy to reflect from the walls, floor, and ceiling. The present investigation is concerned with an automatic network analyzer (ANA) which makes it possible to eliminate the unwanted signals from the final results on the basis of a careful calibration. The ANA system consists of a network analyzer, a swept signal source, and a test set. Attention is given to hardware choices for RCS measurements, an extension of the dynamic range, an error model, error-correction procedures for RCS measurements, and the conduction of the measurements.

Boyles, J.

1985-03-01

61

Spectral Two-Step Preconditioning of Multilevel Fast Multipole Algorithm for the Fast Monostatic RCS Calculation  

Microsoft Academic Search

A new spectral two-step preconditioning of multilevel fast multipole algorithm (MLFMA) is proposed to solve large dense linear systems with multiple right-hand sides arising in monostatic radar cross section (RCS) calculations. The first system is solved with a deflated generalized minimal residual (GMRES) method and the eigenvector information is generated at the same time. Based on this eigenvector information, a

Ping-Liang Rui; Ru-Shan Chen; Dao-Xiang Wang; Edward Kai-Ning Yung

2007-01-01

62

An efficient algorithm for near field RCS of electrically large dynamic targets  

Microsoft Academic Search

Taking into account the influences of near burst fuze, an algorithm, termed the improved equivalent edge currents method(IEEC), is proposed to calculate radar cross section (RCS) of complex targets. Based on the triangle surface element model fitting target configuration and solving occlusion blanking problem by depth buffer theory, the IEEC can calculate reasonably physics optical field and edge diffraction field,

Jing Li; Xiangjun Li

2011-01-01

63

Meteor uxes and visual magnitudes from EISCAT radar event rates: a comparison with cross-section based magnitude estimates  

E-print Network

Meteor ¯uxes and visual magnitudes from EISCAT radar event rates: a comparison with cross also in meteor studies. The time resolution of the radar can be reduced to a few milliseconds, sucient to resolve the passage of individual meteors through the narrow ISR beam. Methods for group and phase

Paris-Sud XI, Université de

64

Radar Ku- and Ka-band backscattering cross sections from typical clouds over the Xi'an of China  

NASA Astrophysics Data System (ADS)

Introduction of satellite services using higher frequency bands such as Ku- and Ka-band requires the characterization of tropospheric propagation factors that are normally considered negligible at lower frequency bands. Clouds scattering and attenuation are considered one such factor. Clouds are present during a large fraction of an average year and cloud scattering and attenuation, together with gaseous absorption, will determine the system performance under non-rainy conditions. In this paper, macro- and micro-physical properties of clouds over Xi'an region are discussed based on meteorologic observation data. The theory and mechanism of backscattering for clouds are analyzed. According to statistics parameters of the clouds over Xi'an region, the quantity calculations of the backscattering cross sections for various reflection mechanism of cloud are dealt with. The results calculated show that the major contributions for the backscattering cross section come possibly from clear-air and humidity turbulence and also from distributions of cloud particles, especially, at higher frequencies. These quantification calculation results on the basis of Xi'an typical clouds properties confirm previous results and it is significance for satellite communication systems, particularly, low availability satellite links and active and passive remote sensing, etc.

Yang, Ruike; Wu, Zhensen; Chen, Yinliang

2002-02-01

65

Recent developments in radar absorbing paints and the Zinc oxide tetrapod whisker  

Microsoft Academic Search

Recent advancements in the field of material science have created several novel materials whose electromagnetic (EM) properties make them ideal candidates for use as radar absorbing materials (RAM). The new types of RAM materials can be applied as very thin layers of paints and still maintain their absorption effectiveness making them ideal for radar cross section (RCS) reduction on aircraft,

Byron T. Caudle; George T. Flowers; Michael E. Baginski; Stuart M. Wentworth; Sadasiva M. Rao

2009-01-01

66

NEUTRON CROSS SECTIONS  

Microsoft Academic Search

The material in the first edition of BNL-325 and its addendum, the ; supplement, and new data received up to May, 1958 are included. Thermal cross ; sections, resonance parameters, and cross section curves are given. (M.H.R.)

Donald J. Hughes; R. B. Schwartz

1958-01-01

67

Adaptive power-managed FMCW emitter detection performance against low-RCS ships  

Microsoft Academic Search

The design of a modern 9.3 GHz homodyne triangular-FMCW emitter for detection of low radar cross section (RCS) ships is described. Both searchand track-mode processing are described including a description of transmit and receive waveforms. Tradeoffs in emitter design are examined as a function of the modulation bandwidth. To predict target detection capability, clutter and target models are developed as

P. E. Pace

2001-01-01

68

Scattering Cross Section of Sound Waves by the Modal Element Method  

NASA Technical Reports Server (NTRS)

#he modal element method has been employed to determine the scattered field from a plane acoustic wave impinging on a two dimensional body. In the modal element method, the scattering body is represented by finite elements, which are coupled to an eigenfunction expansion representing the acoustic pressure in the infinite computational domain surrounding the body. The present paper extends the previous work by developing the algorithm necessary to calculate the acoustics scattering cross section by the modal element method. The scattering cross section is the acoustical equivalent to the Radar Cross Section (RCS) in electromagnetic theory. Since the scattering cross section is evaluated at infinite distance from the body, an asymptotic approximation is used in conjunction with the standard modal element method. For validation, the scattering cross section of the rigid circular cylinder is computed for the frequency range 0.1 is less than or equal to ka is less than or equal to 100. Results show excellent agreement with the analytic solution.

Baumeister, Kenneth J.; Kreider, Kevin L.

1994-01-01

69

Jet inclusive cross sections  

SciTech Connect

Minijet production in jet inclusive cross sections at hadron colliders, with large rapidity intervals between the tagged jets, is evaluated by using the BFKL pomeron. We describe the jet inclusive cross section for an arbitrary number of tagged jets, and show that it behaves like a system of coupled pomerons.

Del Duca, V.

1992-11-01

70

Plasma and Electromagnetic Simulations of Meteor Head Echo Radar Reflections  

NASA Astrophysics Data System (ADS)

Recently, meteor head echo detections from high powered large aperture radars (HPLA) have brought new measurements to bear on the study of sporadic interplanetary meteors. These same observations have demonstrated an ability to observe smaller meteoroids without some of the geometrical restrictions of specular radar techniques. Yet incorporating data from various radar reflection types and from different radars into a single consistent model has proven challenging. We believe this arises due to poorly understood radio scattering characteristics of the meteor plasma, especially in light of recent work showing that plasma turbulence and instability greatly influences meteor trail properties at every stage of evolution. In order to overcome some of the unknown relationships between meteoroid characteristics (such as mass and velocity) and the resulting head echo radar cross-sections (RCS), we present our results on meteor plasma simulations of head echo plasmas using particle in cell (PIC) ions, which show that electric fields strongly influence early stage meteor plasma evolution, by accelerating ions away from the meteoroid body at speeds as large as several kilometers per second. We also present the results of finite difference time domain electromagnetic simulations (FDTD), which can calculate the radar cross-section of the simulated meteor plasma electron distributions. These simulations have shown that the radar cross-section depends in a complex manner on a number of parameters. In this paper we demonstrate that for a given head echo plasma the RCS as a function of radar frequency peaks at sqrt (2*peak plasma frequency) and then decays linearly on a dB scale with increasing radar frequency. We also demonstrate that for a fixed radar frequency, the RCS increases linearly on a dB scale with increasing head echo plasma frequency. These simulations and resulting characterization of the head echo radar cross-section will both help relate HPLA radar observations to meteoroid properties and aid in determining a particular radar facility’s ability to observe various meteoroid populations.

Dyrud, Lars; Wilson, Derek; Boerve, Steiner; Trulsen, Jan; Pecseli, Hans; Close, Sigrid; Chen, Chen; Lee, Yoonjae

2008-06-01

71

Geologic Cross Sections  

NSDL National Science Digital Library

For this project, students must select a several hundred kilometer long section of Earth's surface, ideally crossing one or more major plate boundaries and research all major tectonic events to construct a cross section. Students should also take into account other factors like age of the ocean floor, average elevation and gravity anomalies across their area. The purpose is to demonstrate the geologic/tectonic history of their cross section and present it in a clear, concise summary.

Sharon Browning

72

Application of Model Based Parameter Estimation for RCS Frequency Response Calculations Using Method of Moments  

NASA Technical Reports Server (NTRS)

An implementation of the Model Based Parameter Estimation (MBPE) technique is presented for obtaining the frequency response of the Radar Cross Section (RCS) of arbitrarily shaped, three-dimensional perfect electric conductor (PEC) bodies. An Electric Field Integral Equation (EFTE) is solved using the Method of Moments (MoM) to compute the RCS. The electric current is expanded in a rational function and the coefficients of the rational function are obtained using the frequency derivatives of the EFIE. Using the rational function, the electric current on the PEC body is obtained over a frequency band. Using the electric current at different frequencies, RCS of the PEC body is obtained over a wide frequency band. Numerical results for a square plate, a cube, and a sphere are presented over a bandwidth. Good agreement between MBPE and the exact solution over the bandwidth is observed.

Reddy, C. J.

1998-01-01

73

Application of AWE for RCS Frequency Response Calculations Using Method of Moments  

NASA Technical Reports Server (NTRS)

An implementation of the Asymptotic Waveform Evaluation (AWE) technique is presented for obtaining the frequency response of the Radar Cross Section (RCS) of arbitrarily shaped, three-dimensional perfect electric conductor (PEC) bodies. An Electric Field Integral Equation (EFIE) is solved using the Method of Moments (MoM) to compute the RCS. The electric current, thus obtained, is expanded in a Taylor series around the frequency of interest. The coefficients of the Taylor series (called 'moments') are obtained using the frequency derivatives of the EFIE. Using the moments, the electric current on the PEC body is obtained over a frequency band. Using the electric current at different frequencies, RCS of the PEC body is obtained over a wide frequency band. Numerical results for a square plate, a cube, and a sphere are presented over a bandwidth. A good agreement between AWE and the exact solution over the bandwidth is observed.

Reddy, C. J.; Deshpande, M. D.

1996-01-01

74

Meteor fluxes and visual magnitudes from EISCAT radar event rates: a comparison with cross-section based magnitude estimates and optical data  

Microsoft Academic Search

Incoherent scatter radars (ISR) are versatile instruments for continuous monitoring of ionisation processes in the Earth’s atmosphere. EISCAT, The European Incoherent Scatter facility has proven effective also in meteor studies. The time resolution of the radar can be reduced to a few milliseconds, sufficient to resolve the passage of individual meteors through the narrow ISR beam. Methods for group and

A. Pellinen-Wannberg; A. Westman; G. Wannberg; K. Kaila

1998-01-01

75

Balanced Cross Sections and Retrodeformation  

NSDL National Science Digital Library

In this exercise, students investigate the use of balanced cross sections and retrodeformation to study faults that do not break the surface and their application to tectonics, folding, and earthquake hazards. Introductory materials explain how to construct geologic cross-sections, the idea of balance in a cross-section, and the concept of retrodeformability, whether or not the structures seen in a cross section can be 'undeformed' into their original positions. Using the Kink Method, students will construct a cross-section and test a balanced cross section to see if it is retrodeformable. Instructions, a blank cross section with data, study questions, and a bibliography are provided.

Nicholas Pinter

76

DSI3D - RCS user manual  

SciTech Connect

The DSI3D-RCS code is designed to numerically evaluate radar cross sections on complex objects by solving Maxwell`s curl equations in the time-domain and in three space dimensions. The code has been designed to run on the new parallel processing computers as well as on conventional serial computers. The DSI3D-RCS code is unique for the following reasons: Allows the use of unstructured non-orthogonal grids, allows a variety of cell or element types, reduces to be the Finite Difference Time Domain (FDTD) method when orthogonal grids are used, preserves charge or divergence locally (and globally), is conditionally stable, is selectively non-dissipative, and is accurate for non-orthogonal grids. This method is derived using a Discrete Surface Integration (DSI) technique. As formulated, the DSI technique can be used with essentially arbitrary unstructured grids composed of convex polyhedral cells. This implementation of the DSI algorithm allows the use of unstructured grids that are composed of combinations of non-orthogonal the use of unstructured grids that are composed of combinations of non-orthogonal hexahedrons, tetrahedrons, triangular prisms and pyramids. This algorithm reduces to the conventional FDTD method when applied on a structured orthogonal hexahedral grid.

Madsen, N.; Steich, D.; Cook, G. [and others

1995-08-23

77

Cross Section Flyer  

NSDL National Science Digital Library

In this activity, students use slider bars to move a cross section of a cone, cylinder, prism, or pyramid. This activity allows students to explore conic sections and the 3-dimensional shapes from which they are derived. This activity includes supplemental materials, including background information about the topics covered, a description of how to use the application, and exploration questions for use with the java applet.

2011-03-16

78

Improvement on RCS reduction using flat lossy focusing reflectors.  

PubMed

In this paper, we propose a planar non-periodic subwavelength resistive grating (SWRG). The phase front of the scattered fields can be completely manipulated through non-periodic design of the grating while high absorptivity is preserved. The SWRG has an interesting property similar to a resistive concave reflecting lens. Scattered wave is focused in the near-field region, and spread out in the far-field. This feature of non-periodic resistive grating can improve the original radar cross section (RCS) reduction up to 22.86 dB in the boresight direction comparing to the periodic counterpart. Non-periodic design of SWRG could have a substantial impact on stealth technology, aerospace engineering, and microwave anechoic chamber. PMID:24514847

Chin, Cheng-Yuan; Jou, Christina F

2013-12-30

79

The total charm cross section  

SciTech Connect

We assess the theoretical uncertainties on the total charm cross section. We discuss the importance of the quark mass, the scale choice and the parton densities on the estimate of the uncertainty. We conclude that the uncertainty on the total charm cross section is difficult to quantify.

Vogt, R

2007-09-14

80

XCOM: Photon Cross Sections Database  

National Institute of Standards and Technology Data Gateway

SRD 8 XCOM: Photon Cross Sections Database (Web, free access)   A web database is provided which can be used to calculate photon cross sections for scattering, photoelectric absorption and pair production, as well as total attenuation coefficients, for any element, compound or mixture (Z <= 100) at energies from 1 keV to 100 GeV.

81

The Radar Image Generation (RIG) model  

NASA Technical Reports Server (NTRS)

RIG is a modeling system which creates synthetic aperture radar (SAR) and inverse SAR images from 3-D faceted data bases. RIG is based on a physical optics model and includes the effects of multiple reflections. Both conducting and dielectric surfaces can be modeled; each surface is labeled with a material code which is an index into a data base of electromagnetic properties. The inputs to the program include the radar processing parameters, the target orientation, the sensor velocity, and (for inverse SAR) the target angle rates. The current version of RIG can be run on any workstation, however, it is not a real-time model. We are considering several approaches to enable the program to generate realtime radar imagery. In addition to its image generation function, RIG can also generate radar cross-section (RCS) plots as well as range and doppler radar return profiles.

Stenger, Anthony J.

1993-01-01

82

Cross Section of Sagittal Otolith  

USGS Multimedia Gallery

Cross section of a sagittal otolith from a juvenile Chinook salmon 79 days after emergence. The letters represent: H = hatch, E = emergence, FF = first feed, FW = freshwater residence, TDCK = tidal delta check, and D = tidal delta residence (40x objective)....

83

Radar monitoring of a wake vortex: Electromagnetic reflection of wake turbulence in clear air  

NASA Astrophysics Data System (ADS)

This article deals with X-band radar trial campaigns in 2006 and 2007 at Orly Airport, and in June 2008 at Paris-CDG Airport. An X-band Doppler radar has been deployed to assess short range (inferior to 2000 m) wake vortex monitoring capabilities in all weather conditions (dry and wet conditions). Recorded data have been correlated with electromagnetic and fluid mechanical models of wake turbulences for better and more accurate understanding of roll-up radar cross section (RCS) and Doppler signature.

Barbaresco, Frédéric; Meier, Uwe

2010-01-01

84

Design and applications of a versatile HF radar calibration target in low Earth orbit  

NASA Astrophysics Data System (ADS)

High frequency (HF) radars are used to detect ionospheric irregularities, meteor trails, and moving targets. The Precision Expandable Radar Calibration Sphere (PERCS) is a simple radar target in space to help determine the operational parameters of ground HF radars. PERCS will have a known radar cross section that is independent of observation direction within 0.5 dB. The PERCS satellite can be launched in a stowed configuration that has about 1 m in diameter. After launch, the PERCS will expand to a diameter of almost 10 m. Upon expansion, a stable wire frame is formed to act as a radar scatter target in the form of a polyhedral sphere. The simplest version of the sphere has 60 vertices (V60) that are joined to 90 rigid segments. Each segment is hinged so that the PERCS can be folded into a compact package for launch. Analysis of the V60 wire frame with a 10 m diameter shows that the radar cross section (RCS) is nearly independent of viewing angle up to 30 MHz. Another design with 240 vertices produces even better performance. Radar systems will be calibrated using the radar echo data and the precise knowledge of the target RCS, position, and velocity. The PERCS can reflect radar signals from natural targets such as field aligned and current driven irregularities not presently accessible from ground-based radars. The wire frame structure has several advantages over a metalized spheroid "balloon" with (1) much less drag, (2) larger radar cross section, and (3) lower fabrication cost.

Bernhardt, Paul A.; Siefring, Carl L.; Thomason, Joe F.; Rodriquez, Serafin P.; Nicholas, Andrew C.; Koss, Steven M.; Nurnberger, Mike; Hoberman, Chuck; Davis, Matthew; Hysell, David L.; Kelley, Michael C.

2008-02-01

85

High-frequency techniques for RCS prediction of plate geometries and a physical optics/equivalent currents model for the RCS of trihedral corner reflectors  

NASA Technical Reports Server (NTRS)

Part 1 of this report continues the investigation, initiated in previous reports, of scattering from rectangular plates coated with lossy dielectrics. The hard polarization coefficients given in the last report are incorporated into a model, which includes second- and third-order diffractions, for the coated plate. Computed results from this model are examined and compared to measured data. A breakdown of the contribution of each of the higher-order terms to the total radar cross section (RCS) is given. The effectiveness of the uniform theory of diffraction (UTD) model in accounting for the coating effect is investigated by examining a Physical Optics (PO) model which incorporates the equivalent surface impedance approximation used in the UTD model. The PO, UTD, and experimental results are compared. Part 2 of this report presents a RCS model, based on PO and the Method of Equivalent Currents (MEC), for a trihedral corner reflector. PO is used to account for the reflected fields, while MEC is used for the diffracted fields. Single, double, and triple reflections and first-order diffractions are included in the model. A detailed derivation of the E(sub theta)-polarization, monostatic RCS is included. Computed results are compared with finite-difference time-domain (FDTD) results for validation. The PO/MEC model of this report compares very well with the FDTD model, and it is a much faster model in terms of computational speed.

Balanis, Constantine A.; Polka, Lesley A.; Polycarpou, Anastasis C.

1993-01-01

86

Early Mesoderm Development Cross Section  

NSDL National Science Digital Library

In the context of a cross section between the amniotic cavity and yolk sac, this FlashTM animation depicts mesoderm formation and differentiation into somites, dermatomes, myotomes, sclerotomes, notochord and coelom. Simultaneous development of neural tube, gut and vitelline duct is also displayed.

PhD Jack D Thatcher (West Virginia School of Osteopathic Medicine Structural Biology)

2011-07-07

87

Photoneutron cross sections for Au  

SciTech Connect

Photoneutron cross sections were measured for Au in the entire energy range of the ({gamma},n) channel based on a direct neutron-counting technique with quasimonochromatic {gamma} rays produced in inverse Compton-scattering of laser photons with relativistic electrons. We present results of the measurement in comparison with the past data.

Itoh, O.; Utsunomiya, H.; Akimune, H.; Yamagata, T.; Kondo, T.; Kamata, M. [Department of Physics, Konan University, Okamoto 8-9-1, Higashinada, Kobe 658-8501 (Japan); Toyokawa, H. [National Institute of Advanced Industrial Science and Technology, Tsukuba 305-8568 (Japan); Harada, H.; Kitatani, F. [Japan Atomic Energy Agency, Tokai-mura, Naka, Ibaraki 319-1195 (Japan); Goko, S. [Japan Atomic Energy Agency, Tokai-mura, Naka, Ibaraki 319-1195 (Japan); Faculty of Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Nair, C. [Institut fuer Strahlenphysik, Forschungszentrum Dresden-Rossendorf, D-01314 Dresden (Germany); Nuclear Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Lui, Y.-W. [Cyclotron Institute, Texas A and M University, College Station, Texas 77843 (United States)

2011-10-28

88

LUMEN Cross-Section Tutorial  

NSDL National Science Digital Library

The Loyola University Medical Education Network (LUMEN) presents this anatomy tutorial. The site is divided up into categories of cross-sectional images of the human body: Head and Neck, Upper Limb, male and female Thorax, Abdomen, male and female Pelvis, and Lower Limb. By clicking on each section, users select a cross-section of that part of the anatomy, and by clicking on each number, can find out the specific name of that area. Users can also choose to see an illustration of the area (by choosing â??Imageâ?), or an image from a CAT scan (by choosing â??CTâ?). This is an excellent resource for students in any health care or allied medical field, including nursing or nursesâ?? aides, patient care assistants, and diagnostic imaging technicians.

McNulty, John A.

89

Electron-Impact Ionization Cross Section Database  

National Institute of Standards and Technology Data Gateway

SRD 107 Electron-Impact Ionization Cross Section Database (Web, free access)   This is a database primarily of total ionization cross sections of molecules by electron impact. The database also includes cross sections for a small number of atoms and energy distributions of ejected electrons for H, He, and H2. The cross sections were calculated using the Binary-Encounter-Bethe (BEB) model, which combines the Mott cross section with the high-incident energy behavior of the Bethe cross section. Selected experimental data are included.

90

A physical optics/equivalent currents model for the RCS of trihedral corner reflectors  

NASA Technical Reports Server (NTRS)

The scattering in the interior regions of both square and triangular trihedral corner reflectors is examined. The theoretical model presented combines geometrical and physical optics (GO and PO), used to account for reflection terms, with equivalent edge currents (EEC), used to account for first-order diffractions from the edges. First-order, second-order, and third-order reflection terms are included. Calculating the first-order reflection terms involves integrating over the entire surface of the illuminated plate. Calculating the second- and third-order reflection terms, however, is much more difficult because the illuminated area is an arbitrary polygon whose shape is dependent upon the incident angles. The method for determining the area of integration is detailed. Extensive comparisons between the high-frequency model, Finite-Difference Time-Domain (FDTD) and experimental data are used for validation of the radar cross section (RCS) of both square and triangular trihedral reflectors.

Balanis, Constantine A.; Polycarpou, Anastasis C.

1993-01-01

91

Estimating reflectivity values from wind turbines for analyzing the potential impact on weather radar services  

NASA Astrophysics Data System (ADS)

The World Meteorological Organization (WMO) has repeatedly expressed concern over the increasing number of impact cases of wind turbine farms on weather radars. Since nowadays signal processing techniques to mitigate Wind Turbine Clutter (WTC) are scarce, the most practical approach to this issue is the assessment of the potential interference from a wind farm before it is installed. To do so, and in order to obtain a WTC reflectivity model, it is crucial to estimate the Radar Cross Section (RCS) of the wind turbines to be built, which represents the power percentage of the radar signal that is backscattered to the radar receiver. This paper first characterizes the RCS of wind turbines in the weather radar frequency bands by means of computer simulations based on the Physical Optics theory, and then proposes a simplified model to estimate wind turbine RCS values. This model is of great help in the evaluation of the potential impact of a certain wind farm on the weather radar operation.

Angulo, I.; Grande, O.; Jenn, D.; Guerra, D.; de la Vega, D.

2015-02-01

92

Absorption cross section in Lifshitz black hole  

E-print Network

We derive the absorption cross section of a minimally coupled scalar in the Lifshitz black hole obtained from the new massive gravity. The absorption cross section reduces to the horizon area in the low energy and massless limit of s-wave mode propagation, indicating that the Lifshitz black hole also satisfies the universality of low energy absorption cross section for black holes.

Taeyoon Moon; Yun Soo Myung

2012-10-05

93

COMMUNICATIONS Determination of absolute photoionization cross sections  

E-print Network

product branching ratios in scattering experiments, absolute photo- ionization cross sections are requiredCOMMUNICATIONS Determination of absolute photoionization cross sections for vinyl and propargyl cross sections for vinyl and propargyl radicals at 10 eV of 11.1 2.2 and 8.3 1.6 Mb, respectively. From

Neumark, Daniel M.

94

Airborne laser acquisition of cross-section data  

NASA Technical Reports Server (NTRS)

The feasibility of obtaining cross-section data from airborne remote sensing systems is investigated. Eleven test profiles in the Wolf River Basin, near Memphis, Tennessee, are selected. Each profile is characterized using conventional ground survey methods; under 'leaves-off' conditions, photogrammetric, airborne laser, and airborne radar data are obtained. Results indicate that valley profiles can be accurately characterized with an airborne laser system.

Collins, J. G.; Krabill, W. B.

1980-01-01

95

SNL RML recommended dosimetry cross section compendium  

SciTech Connect

A compendium of dosimetry cross sections is presented for use in the characterization of fission reactor spectrum and fluence. The contents of this cross section library are based upon the ENDF/B-VI and IRDF-90 cross section libraries and are recommended as a replacement for the DOSCROS84 multigroup library that is widely used by the dosimetry community. Documentation is provided on the rationale for the choice of the cross sections selected for inclusion in this library and on the uncertainty and variation in cross sections presented by state-of-the-art evaluations.

Griffin, P.J.; Kelly, J.G.; Luera, T.F. [Sandia National Labs., Albuquerque, NM (United States)] [Sandia National Labs., Albuquerque, NM (United States); VanDenburg, J. [Science and Engineering Associates, Inc., Albuquerque, NM (United States)] [Science and Engineering Associates, Inc., Albuquerque, NM (United States)

1993-11-01

96

Detecting and Mitigating Wind Turbine Clutter for Airspace Radar Systems  

PubMed Central

It is well recognized that a wind turbine has a large radar cross-section (RCS) and, due to the movement of the blades, the wind turbine will generate a Doppler frequency shift. This scattering behavior may cause severe interferences on existing radar systems including static ground-based radars and spaceborne or airborne radars. To resolve this problem, efficient techniques or algorithms should be developed to mitigate the effects of wind farms on radars. Herein, one transponder-based mitigation technique is presented. The transponder is not a new concept, which has been proposed for calibrating high-resolution imaging radars. It modulates the radar signal in a manner that the retransmitted signals can be separated from the scene echoes. As wind farms often occupy only a small area, mitigation processing in the whole radar operation will be redundant and cost inefficient. Hence, this paper uses a transponder to determine whether the radar is impacted by the wind farms. If so, the effects of wind farms are then mitigated with subsequent Kalman filtering or plot target extraction algorithms. Taking airborne synthetic aperture radar (SAR) and pulse Doppler radar as the examples, this paper provides the corresponding system configuration and processing algorithms. The effectiveness of the mitigation technique is validated by numerical simulation results. PMID:24385880

2013-01-01

97

Detecting and mitigating wind turbine clutter for airspace radar systems.  

PubMed

It is well recognized that a wind turbine has a large radar cross-section (RCS) and, due to the movement of the blades, the wind turbine will generate a Doppler frequency shift. This scattering behavior may cause severe interferences on existing radar systems including static ground-based radars and spaceborne or airborne radars. To resolve this problem, efficient techniques or algorithms should be developed to mitigate the effects of wind farms on radars. Herein, one transponder-based mitigation technique is presented. The transponder is not a new concept, which has been proposed for calibrating high-resolution imaging radars. It modulates the radar signal in a manner that the retransmitted signals can be separated from the scene echoes. As wind farms often occupy only a small area, mitigation processing in the whole radar operation will be redundant and cost inefficient. Hence, this paper uses a transponder to determine whether the radar is impacted by the wind farms. If so, the effects of wind farms are then mitigated with subsequent Kalman filtering or plot target extraction algorithms. Taking airborne synthetic aperture radar (SAR) and pulse Doppler radar as the examples, this paper provides the corresponding system configuration and processing algorithms. The effectiveness of the mitigation technique is validated by numerical simulation results. PMID:24385880

Wang, Wen-Qin

2013-01-01

98

(Fast neutron cross section measurements)  

SciTech Connect

In the 14 MeV Neutron Laboratory, we have continued the development of a facility that is now the only one of its kind in operation in the United States. We have refined the klystron bunching system described in last year's report to the point that 1.2 nanosecond pulses have been directly measured. We have tested the pulse shape discrimination capability of our primary NE 213 neutron detector. We have converted the RF sweeper section of the beamline to a frequency of 1 MHz to replace the function of the high voltage pulser described in last year's report which proved to be difficult to maintain and unreliable in its operation. We have also overcome several other significant experimental difficulties, including a major problem with a vacuum leak in the main accelerator column. We have completed additional testing to prove the remainder of the generation and measurement systems, but overcoming some of these experimental difficulties has delayed the start of actual data taking. We are now in a position to begin our first series of ring geometry elastic scattering measurements, and these will be underway before the end of the current contract year. As part of our longer term planning, we are continuing the conceptual analysis of several schemes to improve the intensity of our current pulsed beam. These include the provision of a duoplasmatron ion source and/or the provision of preacceleration bunching. Additional details are given later in this report. A series of measurements were carried out at the Tandem Dynamatron Facility involving the irradiation of a series of yttrium foils and the determination of activation cross sections using absolute counting techniques. The experimental work has been completed, and final analysis of the cross section data will be completed within several months.

Not Available

1991-01-01

99

High-frequency techniques for RCS prediction of plate geometries  

NASA Technical Reports Server (NTRS)

The principal-plane scattering from perfectly conducting and coated strips and rectangular plates is examined. Previous reports have detailed Geometrical Theory of Diffraction/Uniform Theory of Diffraction (GTD/UTD) solutions for these geometries. The GTD/UTD solution for the perfectly conducting plate yields monostatic radar cross section (RCS) results that are nearly identical to measurements and results obtained using the Moment Method (MM) and the Extended Physical Theory of Diffraction (EPTD). This was demonstrated in previous reports. The previous analysis is extended to bistatic cases. GTD/UTD results for the principal-plane scattering from a perfectly conducting, infinite strip are compared to MM and EPTD data. A comprehensive overview of the advantages and disadvantages of the GTD/UTD and of the EPTD and a detailed analysis of the results from both methods are provided. Several previous reports also presented preliminary discussions and results for a GTD/UTD model of the RCS of a coated, rectangular plate. Several approximations for accounting for the finite coating thickness, plane-wave incidence, and far-field observation were discussed. Here, these approximations are replaced by a revised wedge diffraction coefficient that implicitly accounts for a coating on a perfect conductor, plane-wave incidence, and far-field observation. This coefficient is computationally more efficient than the previous diffraction coefficient because the number of Maliuzhinets functions that must be calculated using numerical integration is reduced by a factor of 2. The derivation and the revised coefficient are presented in detail for the hard polarization case. Computations and experimental data are also included. The soft polarization case is currently under investigation.

Balanis, Constantine A.; Polka, Lesley A.

1992-01-01

100

45. Neutrino Cross Section Measurements 1 45. Neutrino Cross Section Measurements  

E-print Network

comprehensive discussion of neutrino interaction cross sections, including neutrino-electron scattering.1. Inclusive Scattering Over the years, many experiments have measured the total cross section for neutrino (µ45. Neutrino Cross Section Measurements 1 45. Neutrino Cross Section Measurements Written in April

101

Ku-Band rendezvous radar performance computer simulation model  

NASA Technical Reports Server (NTRS)

All work performed on the Ku-band rendezvous radar performance computer simulation model program since the release of the preliminary final report is summarized. Developments on the program fall into three distinct categories: (1) modifications to the existing Ku-band radar tracking performance computer model; (2) the addition of a highly accurate, nonrealtime search and acquisition performance computer model to the total software package developed on this program; and (3) development of radar cross section (RCS) computation models for three additional satellites. All changes in the tracking model involved improvements in the automatic gain control (AGC) and the radar signal strength (RSS) computer models. Although the search and acquisition computer models were developed under the auspices of the Hughes Aircraft Company Ku-Band Integrated Radar and Communications Subsystem program office, they have been supplied to NASA as part of the Ku-band radar performance comuter model package. Their purpose is to predict Ku-band acquisition performance for specific satellite targets on specific missions. The RCS models were developed for three satellites: the Long Duration Exposure Facility (LDEF) spacecraft, the Solar Maximum Mission (SMM) spacecraft, and the Space Telescopes.

Magnusson, H. G.; Goff, M. F.

1984-01-01

102

[Fast neutron cross section measurements  

SciTech Connect

From its inception, the Nuclear Data Project at the University of Michigan has concentrated on two major objectives: (1) to carry out carefully controlled nuclear measurements of the highest possible reliability in support of the national nuclear data program, and (2) to provide an educational opportunity for students with interests in experimental nuclear science. The project has undergone a successful transition from a primary dependence on our photoneutron laboratory to one in which our current research is entirely based on a unique pulsed 14 MeV fast neutron facility. The new experimental facility is unique in its ability to provide nanosecond bursts of 14 MeV neutrons under conditions that are clean'' and as scatter-free as possible, and is the only one of its type currently in operation in the United States. It has been designed and put into operation primarily by graduate students, and has met or exceeded all of its important initial performance goals. We have reached the point of its routine operation, and most of the data are now in hand that will serve as the basis for the first two doctoral dissertations to be written by participating graduate students. Our initial results on double differential neutron cross sections will be presented at the May 1993 Fusion Reactor Technology Workshop. We are pleased to report that, after investing several years in equipment assembly and optimization, the project has now entered its data production'' phase.

Knoll, G.F.

1992-10-26

103

Photon-Nucleus Total Cross Sections  

Microsoft Academic Search

Quantitative predictions for the energy and A dependence of the cross sections for nuclear photoabsorption and inelastic electron-nucleus scattering are given. In general, the nucleons do not contribute equally to the total photon-nucleus cross section when coherent contributions of photoproduced hadrons are taken into account. At low energies (Egamma~1 BeV), the cross sections are proportional to nuclear number A, but

Stanley J. Brodsky; Jon Pumplin

1969-01-01

104

Annular-Cross-Section CFE Chamber  

NASA Technical Reports Server (NTRS)

Proposed continuous-flow-electrophoresis (CFE) chamber of annular cross section offers advantages over conventional CFE chamber, and wedge-cross-section chamber described in "Increasing Sensitivity in Continuous-Flow Electrophoresis" (MFS-26176). In comparison with wedge-shaped chamber, chamber of annular cross section virtually eliminates such wall effects as electro-osmosis and transverse gradients of velocity. Sensitivity enhanced by incorporating gradient maker and radial (collateral) flow.

Sharnez, Rizwan; Sammons, David W.

1994-01-01

105

The Primitive Streak, Cross Section  

NSDL National Science Digital Library

This FlashTM animation is the third of a seven part series that presents the primitive streak from different angles. This installment displays the cross section, which is conducive to observing invagination. Epiblast cells ingress through the middle of the germ disc, to differentiate into either endoderm or mesenchymal mesoderm. The endoderm proliferates to drive the hypoblast into the extraembryonic endoderm of the yolk sac. The mesenchyme spreads between the epiblast and endoderm. Although not drawn to scale, the progressive thickening from lateral to paraxial mesoderm is depicted. To open the animation using Internet Explorer follow these steps. (1.) Click the link for the animation. (2.) A dialog box may pop up that begins with the statement "Windows cannot open this file:" If this box does not appear proceed to step four. If it does choose "Select the program from a list," then click OK. (3.) Another dialog box will pop up that lists different programs. Make sure "Internet Explorer" is selected, then click OK. (4.) Internet Explorer will pop up. Beneath the toolbars at the top of the window a yellow bar will appear that reads "To help protect your security, Internet Explorer has restricted this webpage from running scripts or Active X controls that could access your computer. Click here for options..." Pass the cursor over this yellow bar and click the right mouse button. (5.) A dialog box will pop up. Left click the option "Allow Blocked Content." (6.) Another dialog box will appear labeled "Security Warning" asking you to confirm that you want to run the content. Click "Yes." (7.) The Flash animation will appear in the Internet Explorer Window. (8.) Instructions for navigating the lesson are provided by the first frame of the animation.

PhD Jack D Thatcher (West Virginia School of Osteopathic Medicine Structural Biology)

2011-06-23

106

Classify human motions using micro-Doppler radar  

NASA Astrophysics Data System (ADS)

In this paper, human motion model and RCS (radar cross section) simulation of radar returns from human are investigated. Micro-Doppler signatures [1-6] induced by human motions are studied. It shows that the time-frequency representation of micro-Doppler signature provides distinctive time-varying features for human motions. Motion of different body part has different micro-Doppler signature. Thus, micro-Doppler can be a promising method for classifying human activities. Measurement data using an experimental X-band micro-Doppler radar were collected and the results are compared with the corresponding simulation results. The classification of human motions based on micro-Doppler signatures is also discussed.

Yang, Yinan; Zhang, Wenxue; Lu, Chao

2008-03-01

107

Absolute partial photoionization cross sections of ozone.  

SciTech Connect

Despite the current concerns about ozone, absolute partial photoionization cross sections for this molecule in the vacuum ultraviolet (valence) region have been unavailable. By eclectic re-evaluation of old/new data and plausible assumptions, such cross sections have been assembled to fill this void.

Berkowitz, J.; Chemistry

2008-04-01

108

Reconstructing Cell Complexes From Cross-sections  

E-print Network

Reconstructing Cell Complexes From Cross-sections Scott E. Dillard1,2 , Dan Thoma1 and Bernd Hamann segmentations take the form of cell com- plexes. We present a method to infer a 3D cell complex from of a series structures found in nature. Given a prescribed matching of 2D cells in adjacent cross-sections we produce a 3

Hamann, Bernd

109

Optimization research for ash dam cross section  

Microsoft Academic Search

This paper presents a new approach for the optimization analysis of ash dam slope stability calculation by using lattice method. A further study for the optimization design of ash dam cross section using exhaustion method is also provided. The numerical result analysis indicates that using combined optimization method of lattice and exhaustion to design ash dam cross section can achieve

Shouyi Li; Jihua Zhao; Yaolong Chen; Jusheng Yang

2005-01-01

110

Silicon Detector System for Cross Section Measurements  

NASA Technical Reports Server (NTRS)

In order to estimate the radiation shielding effectiveness of materials it is necessary to know cosmic ray particles are broken up as they pass though these materials. The breakup of cosmic ray particles is characterized by the nuclear fragmentation cross sections, i.e. an effective geometrical cross section assigned to each target nucleus that represents its apparent size for fragmenting the incident particle. The values of these cross sections depend on the details of nuclear physics and cannot be calculated from first principles owing to the many-body nature of the interactions. The only way to determine them is to measure them. Once a sufficient number of cross sections have been measured, the systematic nature of the interactions allows other cross-sections to be estimated. The number of cross sections that contribute to the estimation of shielding effectiveness is very large 10,000. Fortunately most make minor contributions. These can be estimated from nuclear systematics. Only those who's uncertainties make significant contributions to the error in the shielding effectiveness estimations need to be measured. In the past it has proven difficult to measure light fragment production cross sections from the interactions of heavy cosmic rays owing to the size of the detectors used. We have developed a highly pixilated silicon (Si) detector system that can individually identify these light fragments while making efficient use of costly accelerator time. This system is an outgrowth of detector technology developed under a CDDF and a Code S sponsored cosmic ray experiment.

2003-01-01

111

Nucleon-Nucleon Total Cross Section  

NASA Technical Reports Server (NTRS)

The total proton-proton and neutron-proton cross sections currently used in the transport code HZETRN show significant disagreement with experiment in the GeV and EeV energy ranges. The GeV range is near the region of maximum cosmic ray intensity. It is therefore important to correct these cross sections, so that predictions of space radiation environments will be accurate. Parameterizations of nucleon-nucleon total cross sections are developed which are accurate over the entire energy range of the cosmic ray spectrum.

Norbury, John W.

2008-01-01

112

Absorption cross section in de Sitter space  

E-print Network

We study the wave equation for a minimally coupled massive scalar in three-dimensional de Sitter space. We compute the absorption cross section to investigate its cosmological horizon in the southern diamond. Although the absorption cross section is not defined exactly, we can be determined it from the fact that the low-energy $s(j=0)$-wave absorption cross section for a massless scalar is given by the area of the cosmological horizon. On the other hand, the low-temperature limit of $j\

Y. S. Myung

2003-02-10

113

790 IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION,VOL. 42, NO. 6, JUNE 1994 Spectral Iterative Algorithm for RCS Computation in  

E-print Network

as with experimental data, for two-dimensional and three-dimensional cavities with rectangular cross section. I signatures. For RCS analysis of complex targets, duct structures such as jet engine intakes can often

Lozano, Angel

114

Absorption cross section of canonical acoustic holes  

SciTech Connect

We compute numerically the absorption cross section of a canonical acoustic hole for sound waves with arbitrary frequencies. Our outputs are in full agreement with the expected low- and high-frequency limits.

Crispino, Luis C. B.; Oliveira, Ednilton S.; Matsas, George E. A. [Faculdade de Fisica, Universidade Federal do Para, 66075-110, Belem (Brazil); Instituto de Fisica Teorica, Universidade Estadual Paulista, Rua Pamplona 145, 01405-900, Sao Paulo, SP (Brazil)

2007-11-15

115

Status of neutron dosimetry cross sections  

SciTech Connect

Several new cross section libraries, such as ENDF/B-VI(release 2), IRDF-90,JEF-2.2, and JENDL-3 Dosimetry, have recently been made available to the dosimetry community. the Sandia National Laboratories (SNL) Radiation Metrology Laboratory (RML) has worked with these libraries since pre-release versions were available. this paper summarizes the results of the intercomparison and testing of dosimetry cross sections. As a result of this analysis, a compendium of the best dosimetry cross sections was assembled from the available libraries for use within the SNL RML. this library, referred to as the SNLRML Library, contains 66 general dosimetry sensors and 3 special dosimeters unique to the RML sensor inventory. The SNLRML cross sections have been put into a format compatible with commonly used spectrum determination codes.

Griffin, P.J.; Kelly, J.G.

1992-12-31

116

Bibliography of photoabsorption cross-section data  

NASA Technical Reports Server (NTRS)

This bibliography contains only references which report a measured or calculated photoabsorption cross section (relative or normalized) in regions of continuous absorption. The bibliography is current as of January 1, 1970.

Hudson, R. D.; Kieffer, L. J.

1970-01-01

117

Cross section measurements with monoenergetic muon neutrinos  

E-print Network

The monoenergetic 236 MeV muon neutrino from charged kaon decay at rest (K[superscript +] ? ?[superscript +]?[subscript ?]) can be used to produce a novel set of cross section measurements. Applicable for short- and ...

Spitz, Joshua B.

118

International Evaluation of Neutron Cross Section Standards  

SciTech Connect

Neutron cross section standards are the basis for the determination of most neutron cross sections. They are used for both measurements and evaluations of neutron cross sections. Not many cross sections can be obtained absolutely - most cross sections are measured relative to the cross section standards and converted using evaluations of the standards. The previous complete evaluation of the neutron cross section standards was finished in 1987 and disseminated as the NEANDC/INDC and ENDF/B-VI standards. R-matrix model fits for the light elements and non-model least-squares fits for all the cross sections in the evaluation were the basis of the combined fits for all of the data. Some important reactions and constants are not standards, but they assist greatly in the determination of the standard cross sections and reduce their uncertainties - these data were also included in the combined fits. The largest experimental database used in the evaluation was prepared by Poenitz and included about 400 sets of experimental data with covariance matrices of uncertainties that account for all cross-energy, cross-reaction and cross-material correlations. For the evaluation GMA, a least-squares code developed by Poenitz, was used to fit all types of cross sections (absolute and shape), their ratios, spectrum-averaged cross sections and thermal constants in one full analysis. But, the uncertainties derived in this manner, and especially those obtained in the R-matrix model fits, have been judged to be too low and unrealistic. These uncertainties were substantially increased prior to their release in the recommended data files of 1987. Modified percentage uncertainties were reassigned by the United States Cross Section Evaluation Working Group's Standards Subcommittee for a wide range of energies, and no covariance (or correlation) matrices were supplied at that time. The need to re-evaluate the cross section standards is based on the appearance of a significant amount of precise experimental data and improved developments in the methodology of analysis and evaluation. Initial efforts to produce a new evaluation were made by the United States Cross Section Evaluation Working Group which formed a Task Force. It was realized that international cooperation would be needed to produce the evaluation. The Working Party on International Evaluation Cooperation of the Nuclear Energy Agency Nuclear Science Committee formed a Subgroup, and the International Atomic Energy Agency formed a Coordinated Research Project (CRP). These groups worked cooperatively to improve the evaluation process. The major effort in producing the evaluation was through the CRP. The evaluations of the neutron cross section standards were finalized in October 2005. Previous difficulties experienced with a data evaluation problem known as 'Peelle's Pertinent Puzzle' create biases in the fit of correlated data, and they have been addressed to reduce this phenomenon. The new evaluations of the cross section standards also include covariance matrices of the uncertainties that contain fully justifiable values. The product of this international effort has been adopted as the neutron standards for ENDF/B-VII.0.

Carlson, A.D. [National Institute of Standards and Technology, 100 Bureau Drive, Stop 8463, Gaithersburg, MD 20899-8463 (United States)], E-Mail: allan.carlson@nist.gov; Pronyaev, V.G. [Institute of Physics and Power Engineering, Bondarenko Sq. 1, 249 033 Obninsk, Kaluga Region (Russian Federation); Smith, D.L. [Argonne National Laboratory, 1710 Avenida del Mundo 1506, Coronado, CA 92118 (United States); Larson, N.M. [Bldg 5700, Rm 308, MS 6371, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6371 (United States); Chen, Zhenpeng [Physics Department, Tsinghua University, Beijing 100084 China (China); Hale, G.M. [Los Alamos National Laboratory, Group T-16, MS B-243, Los Alamos NM 87545 (United States); Hambsch, F.-J. [Neutron Physics Unit, EC-JRC-Institute for Reference Materials and Measurements, Retieseweg B-2440 Geel (Belgium); Gai, E.V. [Institute of Physics and Power Engineering, Bondarenko Sq. 1, 249 033 Obninsk, Kaluga Region (Russian Federation); Oh, Soo-Youl [HANARO Center, Korea Atomic Energy Research Institute, P.O. Box 105, Yuseong, Daejeon 305-600 (Korea, Republic of); Badikov, S.A. [Central Research Institute of Management, Economics and Information, Dmitrovskoe sh.2, Moscow 127434 (Russian Federation); Kawano, T. [Los Alamos National Laboratory, Group T-16, MS B-243, Los Alamos NM 87545 (United States); Hofmann, H.M. [Institut fuer Theoretische Physik III, 02.534/B2, Universitaet Erlangen-Nuernberg, Staudtstrasse 7, D-91058 Erlangen (Germany); Vonach, H.; Tagesen, S. [Institut fuer Isotopenforschung und Kernphysik der Universitaet Wien, Waehringerstrasse 17, A-1090 Vienna (Austria)

2009-12-15

119

International Evaluation of Neutron Cross Section Standards  

NASA Astrophysics Data System (ADS)

Neutron cross section standards are the basis for the determination of most neutron cross sections. They are used for both measurements and evaluations of neutron cross sections. Not many cross sections can be obtained absolutely - most cross sections are measured relative to the cross section standards and converted using evaluations of the standards. The previous complete evaluation of the neutron cross section standards was finished in 1987 and disseminated as the NEANDC/INDC and ENDF/B-VI standards. R-matrix model fits for the light elements and non-model least-squares fits for all the cross sections in the evaluation were the basis of the combined fits for all of the data. Some important reactions and constants are not standards, but they assist greatly in the determination of the standard cross sections and reduce their uncertainties - these data were also included in the combined fits. The largest experimental database used in the evaluation was prepared by Poenitz and included about 400 sets of experimental data with covariance matrices of uncertainties that account for all cross-energy, cross-reaction and cross-material correlations. For the evaluation GMA, a least-squares code developed by Poenitz, was used to fit all types of cross sections (absolute and shape), their ratios, spectrum-averaged cross sections and thermal constants in one full analysis. But, the uncertainties derived in this manner, and especially those obtained in the R-matrix model fits, have been judged to be too low and unrealistic. These uncertainties were substantially increased prior to their release in the recommended data files of 1987. Modified percentage uncertainties were reassigned by the United States Cross Section Evaluation Working Group's Standards Subcommittee for a wide range of energies, and no covariance (or correlation) matrices were supplied at that time. The need to re-evaluate the cross section standards is based on the appearance of a significant amount of precise experimental data and improved developments in the methodology of analysis and evaluation. Initial efforts to produce a new evaluation were made by the United States Cross Section Evaluation Working Group which formed a Task Force. It was realized that international cooperation would be needed to produce the evaluation. The Working Party on International Evaluation Cooperation of the Nuclear Energy Agency Nuclear Science Committee formed a Subgroup, and the International Atomic Energy Agency formed a Coordinated Research Project (CRP). These groups worked cooperatively to improve the evaluation process. The major effort in producing the evaluation was through the CRP. The evaluations of the neutron cross section standards were finalized in October 2005. Previous difficulties experienced with a data evaluation problem known as "Peelle's Pertinent Puzzle" create biases in the fit of correlated data, and they have been addressed to reduce this phenomenon. The new evaluations of the cross section standards also include covariance matrices of the uncertainties that contain fully justifiable values. The product of this international effort has been adopted as the neutron standards for ENDF/B-VII.0.

Carlson, A. D.; Pronyaev, V. G.; Smith, D. L.; Larson, N. M.; Chen, Zhenpeng; Hale, G. M.; Hambsch, F.-J.; Gai, E. V.; Oh, Soo-Youl; Badikov, S. A.; Kawano, T.; Hofmann, H. M.; Vonach, H.; Tagesen, S.

2009-12-01

120

A nuclear cross section data handbook  

SciTech Connect

Isotopic information, reaction data, data availability, heating numbers, and evaluation information are given for 129 neutron cross-section evaluations, which are the source of the default cross sections for the Monte Carlo code MCNP. Additionally, pie diagrams for each nuclide displaying the percent contribution of a given reaction to the total cross section are given at 14 MeV, 1 MeV, and thermal energy. Other information about the evaluations and their availability in continuous-energy, discrete-reaction, and multigroup forms is provided. The evaluations come from ENDF/B-V, ENDL85, and the Los Alamos Applied Nuclear Science Group T-2. Graphs of all neutron and photon production cross-section reactions for these nuclides have been categorized and plotted. 21 refs., 5 tabs.

Fisher, H.O.M.

1989-12-01

121

Absorption cross section of RN black hole  

E-print Network

The behavior of a charged scalar field in the RN black hole space time is studied using WKB approximation. In the present work it is assumed that matter waves can get reflected from the event horizon. Using this effect, the Hawking temperature and the absorption cross section for RN black hole placed in a charged scalar field are calculated. The absorption cross section $\\sigma _{abs}$ is found to be inversely proportional to square of the Hawking temperature of the black hole.

Sini R.; V. C. Kuriakose

2007-08-23

122

Ultraviolet absorption cross sections of hydrogen peroxide  

NASA Technical Reports Server (NTRS)

Absorption cross-sections of hydrogen peroxide vapor and of neutral aqueous solutions of hydrogen peroxide were measured in the wavelength range from 195 to 350 nm at 296 K. The spectrophotometric procedure is described, and the reported cross-sections are compared with values obtained by other researchers. Photodissociation coefficients of atmospheric H2O2 were calculated for direct absorption of unscattered solar radiation, and the vertical distributions of these coefficients are shown for various solar zenith angles.

Lin, C. L.; Rohatgi, N. K.; Demore, W. B.

1978-01-01

123

Evaluation methods for neutron cross section standards  

SciTech Connect

Methods used to evaluate the neutron cross section standards are reviewed and their relative merits, assessed. These include phase-shift analysis, R-matrix fit, and a number of other methods by Poenitz, Bhat, Kon'shin and the Bayesian or generalized least-squares procedures. The problems involved in adopting these methods for future cross section standards evaluations are considered, and the prospects for their use, discussed. 115 references, 5 figures, 3 tables.

Bhat, M.R.

1980-01-01

124

Rising Total Hadron-Hadron Cross Sections  

E-print Network

A historical summary is made on the measurements concerning the rising total hadron-hadron cross sections at high energies. The first part of this paper concerns the total cross section measurements performed at the Brookhaven, Serpukhov and Fermilab fixed target accelerators; then the measurements at the CERN Intersecting Storage Rings (ISR), and at the CERN and at the Tevatron Fermilab proton-antiproton colliders; finally the cosmic ray measurements at even higher energies. A short discussion on Conclusions and Perspectives follows.

Giorgio Giacomelli

2007-12-06

125

Multicore fiber with rectangular cross-section.  

PubMed

We have fabricated, to our knowledge, the first rectangular cross-section multicore fiber with eight cores arranged in a line. We have shown that the rectangular cross-section remains practically unchanged during the fiber-drawing process. The heterogeneous version of the proposed fiber design could be beneficial for crosstalk reduction because of the low influence of fiber bends on crosstalk between neighboring cores. PMID:24686702

Egorova, O N; Semjonov, S L; Senatorov, A K; Salganskii, M Y; Koklyushkin, A V; Nazarov, V N; Korolev, A E; Kuksenkov, D V; Li, Ming-Jun; Dianov, E M

2014-04-01

126

Asymptotic cross sections for composite projectile reactions  

E-print Network

ASYMPTOTIC CROSS SECTIONS FOR COMPOSITE PROJECTILE REACTIONS A Thesis by ANDREA MAROLT PIMENTA NEVES Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER... Asymptotic Cross Sections for Composite Projectile Reactions. (August 1995) Andrea Marolt Pimenta Neves B. S. Mary Washington College Chair of Advisory Committee: Dr. John F. Reading The First Born Approximation has been used to compute excitation...

Neves, Andrea Marolt Pimenta

1995-01-01

127

Predicting the Total Charm Cross Section  

SciTech Connect

We discuss the energy dependence of the total charm cross section and some of its theoretical uncertainties including the quark mass, scale choice and the parton densities. Extracting the total charm cross section from data is a non-trivial task. To go from a finite number of measured D mesons in a particular decay channel to the total c{bar c} cross section one must: divide by the branching ratio for that channel; correct for the luminosity, {sigma}{sub D} = N{sub D}/Lt; extrapolate to full phase space from the finite detector acceptance; divide by two to get the pair cross section from the single Ds; and multiply by a correction factor to account for unmeasured charm hadrons. Early fixed-target data were at rather low p{sub T}, making the charm quark mass the most relevant scale. At proton and ion colliders, although the RHIC experiments can access the full pT range and thus the total cross section, the data reach rather high p{sub T}, p{sub T} >> m, making p{sub T} (m{sub T}) the most relevant scale. Here we focus on the total cross section calculation where the quark mass is the only relevant scale.

Vogt, R

2008-05-29

128

Medical radar considerations for detecting and monitoring Crohn's disease  

NASA Astrophysics Data System (ADS)

Crohn's disease is a condition that causes inflammation and associated complications along any section of the digestive tract. Over the years, numerous radiological and endoscopic methods as well as the use of ultrasound have been developed to examine and diagnose inflammatory bowel disorders such as Crohn's disease. While such techniques have much merit, an alternative medical solution that is safe, non-invasive, and inexpensive is proposed in this paper. Reflections from electromagnetic signals transmitted by an ultra-wide band (UWB) radar allow for not only range (or extent) information but also spectral analysis of a given target of interest. Moreover, the radar cross-section (RCS) of an object measures how detectable the electromagnetic return energy of such an object is to the radar. In the preliminary phase of research, we investigate how disparities in the dielectric properties of diseased versus non-diseased portions of the intestines can aid in the detection of Crohn's disease. RCS analysis from finite-difference time-domain (FDTD) method simulations using a simple 3D model of the intestines are presented. The ultimate goal of our research is to design a UWB radar system using a suitable waveform to detect and monitor Crohn's disease.

Smith, Sonny; Narayanan, Ram M.; Messaris, Evangelos

2014-05-01

129

Lidar Bacscatter Cross-Section Radar Bacscatter Cross-Section Mixed Phase  

E-print Network

of Okhotsk Lake Lake Great Bear Great Slave Sea Baltic Black Sea Sea Bering Strait Chukchi average minimum extent of sea ice neL a amyloK nadlA yuyliV nokuY aneL reviR yesineY Lake Lake Ladoga Onega agloV vi Great Bear Great Slave Sea Baltic Black Sea Sea Bering Strait Chukchi average minimum extent of sea ice

Eloranta, Edwin W.

130

30 CFR 779.25 - Cross sections, maps, and plans.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Cross sections, maps, and plans. 779.25 Section 779...RESOURCES § 779.25 Cross sections, maps, and plans. (a) The application shall include cross sections, maps, and plans showing— (1)...

2010-07-01

131

30 CFR 783.25 - Cross sections, maps, and plans.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Cross sections, maps, and plans. 783.25 Section 783...RESOURCES § 783.25 Cross sections, maps, and plans. (a) The application shall include cross sections, maps, and plans showing— (1)...

2010-07-01

132

30 CFR 779.25 - Cross sections, maps, and plans.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Cross sections, maps, and plans. 779.25 Section 779...RESOURCES § 779.25 Cross sections, maps, and plans. (a) The application shall include cross sections, maps, and plans showing— (1)...

2012-07-01

133

30 CFR 779.25 - Cross sections, maps, and plans.  

Code of Federal Regulations, 2014 CFR

...2014-07-01 false Cross sections, maps, and plans. 779.25 Section 779...RESOURCES § 779.25 Cross sections, maps, and plans. (a) The application shall include cross sections, maps, and plans showing— (1)...

2014-07-01

134

30 CFR 779.25 - Cross sections, maps, and plans.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Cross sections, maps, and plans. 779.25 Section 779...RESOURCES § 779.25 Cross sections, maps, and plans. (a) The application shall include cross sections, maps, and plans showing— (1)...

2013-07-01

135

30 CFR 783.25 - Cross sections, maps, and plans.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Cross sections, maps, and plans. 783.25 Section 783...RESOURCES § 783.25 Cross sections, maps, and plans. (a) The application shall include cross sections, maps, and plans showing— (1)...

2011-07-01

136

NNLO jet cross sections by subtraction  

NASA Astrophysics Data System (ADS)

We report on the computation of a class of integrals that appear when integrating the so-called iterated singly-unresolved approximate cross section of the NNLO subtraction scheme of Refs. [G. Somogyi, Z. Trócsányi, and V. Del Duca, JHEP 06, 024 (2005), arXiv:hep-ph/0502226; G. Somogyi and Z. Trócsányi, (2006), arXiv:hep-ph/0609041; G. Somogyi, Z. Trócsányi, and V. Del Duca, JHEP 01, 070 (2007), arXiv:hep-ph/0609042; G. Somogyi and Z. Trócsányi, JHEP 01, 052 (2007), arXiv:hep-ph/0609043] over the factorised phase space of unresolved partons. The integrated approximate cross section itself can be written as the product of an insertion operator (in colour space) times the Born cross section. We give selected results for the insertion operator for processes with two and three hard partons in the final state.

Somogyi, G.; Bolzoni, P.; Trócsányi, Z.

2010-08-01

137

Absorption cross sections of stratospheric molecules  

NASA Technical Reports Server (NTRS)

Two classes of molecular species must be considered in a calculation of photochemical rates in the stratosphere. The first class consists of molecular oxygen and ozone, while the second class contains the remainder of the minor constituents. If accurate values of the transmitted fluxes are required at large optical depths, the cross sections for molecular oxygen and ozone must be known to within a few per cent at least. On the other hand, the photochemical rates for the minor species are given simply by the relevant cross sections. A review of published cross sections is presented, giving attention to molecular oxygen, ozone, nitric oxide, nitrogen dioxide, nitrous oxide, nitric acid, ammonia, water vapor, hydrogen peroxide, carbon monoxide, carbon dioxide, and sulfur dioxide.

Hudson, R. D.

1974-01-01

138

Top differential cross section measurements (Tevatron)  

SciTech Connect

Differential cross sections in the top quark sector measured at the Fermilab Tevatron collider are presented. CDF used 2.7 fb{sup -1} of data and measured the differential cross section as a function of the invariant mass of the t{bar t} system. The measurement shows good agreement with the standard model and furthermore is used to derive limits on the ratio {kappa}/M{sub Pl} for gravitons which decay to top quarks in the Randall-Sundrum model. D0 used 1.0 fb{sup -1} of data to measure the differential cross section as a function of the transverse momentum of the top-quark. The measurement shows a good agreement to the next-to-leading order perturbative QCD prediction and various other standard model predictions.

Jung, Andreas W.

2012-01-01

139

The cross section for double Compton scattering  

NASA Technical Reports Server (NTRS)

Employing elementary methods in nonrelativistic quantum electrodynamics, the cross section for gamma sub 0 + e yields e + gamma + gamma is computed for arbitrary energy in the spectrum of the outgoing photons. The final result is given, differential in the energy of one of these photons, for the case where the incident photon is unpolarized and has energy E sub 0 much less than mc-squared, a polarization sum and angular integration being performed for the final-state photons. The cross section has a simple algebraic form resulting from contributions from the sum of squared direct and exchange amplitudes; interference terms from these amplitudes do not contribute to the angular-integrated cross section.

Gould, R. J.

1984-01-01

140

Inverse synthetic aperture radar imagery of a man with a rocket propelled grenade launcher  

NASA Astrophysics Data System (ADS)

As the Army moves toward more lightly armored Future Combat System (FCS) vehicles, enemy personnel will present an increasing threat to U.S. soldiers. In particular, they face a very real threat from adversaries using shoulder-launched, rocket propelled grenade (RPG). The Army Research Laboratory has utilized its Aberdeen Proving Ground (APG) turntable facility to collect very high resolution, fully polarimetric Ka band radar data at low depression angles of a man holding an RPG. In this paper, we examine the resulting low resolution and high resolution range profiles; and based on the observed radar cross section (RCS) value, we attempt to determine the utility of Ka band radar for detecting enemy personnel carrying RPG launchers.

Tran, Chi N.; Innocenti, Roberto; Kirose, Getachew; Ranney, Kenneth I.; Smith, Gregory

2004-08-01

141

Covariance Evaluation Methodology for Neutron Cross Sections  

SciTech Connect

We present the NNDC-BNL methodology for estimating neutron cross section covariances in thermal, resolved resonance, unresolved resonance and fast neutron regions. The three key elements of the methodology are Atlas of Neutron Resonances, nuclear reaction code EMPIRE, and the Bayesian code implementing Kalman filter concept. The covariance data processing, visualization and distribution capabilities are integral components of the NNDC methodology. We illustrate its application on examples including relatively detailed evaluation of covariances for two individual nuclei and massive production of simple covariance estimates for 307 materials. Certain peculiarities regarding evaluation of covariances for resolved resonances and the consistency between resonance parameter uncertainties and thermal cross section uncertainties are also discussed.

Herman,M.; Arcilla, R.; Mattoon, C.M.; Mughabghab, S.F.; Oblozinsky, P.; Pigni, M.; Pritychenko, b.; Songzoni, A.A.

2008-09-01

142

Universal Parameterization of Absorption Cross Sections  

NASA Technical Reports Server (NTRS)

Our prior nuclear absorption cross sections model is extended for light systems (A less than or equal to 4) where either both projectile and target are light particles or one is a light particle and the other is a medium or heavy nucleus. The agreement with experiment is excellent for these cases as well. Present work in combination with our original model provides a comprehensive picture of absorption cross sections for light, medium, and heavy systems, a very valuable input for radiation protection studies.

Tripathi, R. K.; Cucinotta, Francis A.; Wilson, John W.

1999-01-01

143

Measurement of differential atomic collision cross sections.  

NASA Technical Reports Server (NTRS)

An apparatus for the study of differential angular scattering of atomic projectiles by gas targets is described. The design facilitates system alignment and provides for accurate reproducible location of components. The performance of the instrument is studied for scattering of H+ at 5-25 keV energies by helium and argon targets. Differential cross sections for elastic scattering and charge transfer are presented as well as total charge transfer cross sections. The coefficients for secondary electron ejection by impact of H and H+ on a metal surface are compared.

Fitzwilson, R. L.; Thomas, E. W.

1971-01-01

144

Precise neutron inelastic cross section measurements  

SciTech Connect

The design of a new generation of nuclear reactors requires the development of a very precise neutron cross section database. Ongoing experiments performed at dedicated facilities aim to the measurement of such cross sections with an unprecedented uncertainty of the order of 5% or even smaller. We give an overview of such a facility: the Gamma Array for Inelastic Neutron Scattering (GAINS) installed at the GELINA neutron source of IRMM, Belgium. Some of the most challenging difficulties of the experimental approach are emphasized and recent results are shown.

Negret, Alexandru [Horia Hulubei National Institute for Physics and Nuclear Engineering, Reactorului 30, 077125 Bucharest-Magurele (Romania)

2012-11-20

145

Neutron Capture Cross Section of ^239Pu  

NASA Astrophysics Data System (ADS)

The ^239Pu(n,?) cross section has been measured at the Los Alamos Neutron Science Center (LANSCE). The Detector for Advanced Neutron Capture Experiments (DANCE) provided a highly segmented 4? measurement of the energy and multiplicity distributions for emitted ?-rays, while a PPAC detected coincidence fission fragments. The simultaneous measurement of (n,?) and (n,f) events resulting from a single sample allowed the (n,?) cross section to be measured as a ratio to fission with reduced systematic uncertainty. Results from the current analysis will be presented.

Mosby, S.; Arnold, C.; Bredeweg, T. A.; Chyzh, A.; Couture, A.; Gostic, J. M.; Henderson, R. A.; Jandel, M.; Kwan, E.; O'Donnell, J. M.; Rusev, G.; Ullmann, J. L.; Wu, C.-Y.

2012-10-01

146

New Parameterization of Neutron Absorption Cross Sections  

NASA Technical Reports Server (NTRS)

Recent parameterization of absorption cross sections for any system of charged ion collisions, including proton-nucleus collisions, is extended for neutron-nucleus collisions valid from approx. 1 MeV to a few GeV, thus providing a comprehensive picture of absorption cross sections for any system of collision pairs (charged or uncharged). The parameters are associated with the physics of the problem. At lower energies, optical potential at the surface is important, and the Pauli operator plays an increasingly important role at intermediate energies. The agreement between the calculated and experimental data is better than earlier published results.

Tripathi, Ram K.; Wilson, John W.; Cucinotta, Francis A.

1997-01-01

147

Infrared absorption cross sections of alternative CFCs  

NASA Technical Reports Server (NTRS)

Absorption cross sections have obtained in the infrared atmospheric window, between 600 and 1500 cm(exp -1), for 10 alternative hydrohalocarbons: HCFC-22, HCFC-123, HCFC-124, HCFC-141b, HCFC-142b, HCFC-225ca, HCFC-225cb, HFC-125, HFC-134a, and HFC-152a. The measurements were made at three temperatures (287K, 270K and 253K) with a Fourier transform spectrometer operating at 0.03 cm(exp -1) apodized resolution. Integrated cross sections are also derived for use in radiative models to calculate the global warming potentials.

Clerbaux, Cathy; Colin, Reginald; Simon, Paul C.

1994-01-01

148

Cross sections of neutron-induced reactions  

SciTech Connect

We study the properties of the neutron-nucleus total and reaction cross sections for several nuclei. We have applied an analytical model, the nuclear Ramsauer model, justified it from the nuclear reaction theory approach, and extracted the values of 12 parameters used in the model. The given parametrization has an advantage as phenomenological optical model potentials are limited up to 150-200 MeV. The present model provides good estimates of the total cross sections for several nuclei particularly at high energies.

Mukhopadhyay, Tapan; Lahiri, Joydev; Basu, D. N. [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata 700064 (India)

2010-10-15

149

Neutron Capture Cross Section of 239Pu  

NASA Astrophysics Data System (ADS)

The 239Pu(n,?) cross section has been measured over the energy range 10 eV - 10 keV using the Detector for Advanced Neutron Capture Experiments (DANCE) as part of a campaign to produce precision (n,?) measurements on 239Pu in the keV region. Fission coincidences were measured with a PPAC and used to characterize the prompt fission ?-ray spectrum in this region. The resulting spectra will be used to better characterize the fission component of another experiment with a thicker target to extend the (n,?) cross section measurement well into the keV region.

Mosby, S.; Arnold, C.; Bredeweg, T. A.; Couture, A.; Jandel, M.; O'Donnell, J. M.; Rusev, G.; Ullmann, J. L.; Chyzh, A.; Henderson, R.; Kwan, E.; Wu, C. Y.

2014-09-01

150

Optical Model and Cross Section Uncertainties  

SciTech Connect

Distinct minima and maxima in the neutron total cross section uncertainties were observed in model calculations using spherical optical potential. We found this oscillating structure to be a general feature of quantum mechanical wave scattering. Specifically, we analyzed neutron interaction with 56Fe from 1 keV up to 65 MeV, and investigated physical origin of the minima.We discuss their potential importance for practical applications as well as the implications for the uncertainties in total and absorption cross sections.

Herman,M.W.; Pigni, M.T.; Dietrich, F.S.; Oblozinsky, P.

2009-10-05

151

Inclusive cross section ratios at x > 1  

NASA Astrophysics Data System (ADS)

We study the ratios of inclusive electron scattering cross sections between nuclei and the deuteron, for values of the scaling variable x > 1 and for large momentum transfers. Employing microscopic nuclear spectral functions and describing the recoil-nucleon final state interaction using correlated Glauber theory, we find good agreement with experiment.

Benhar, O.; Fabrocini, A.; Fantoni, S.; Sick, I.

1995-02-01

152

Cross Sections From Scalar Field Theory  

NASA Technical Reports Server (NTRS)

A one pion exchange scalar model is used to calculate differential and total cross sections for pion production through nucleon- nucleon collisions. The collisions involve intermediate delta particle production and decay to nucleons and a pion. The model provides the basic theoretical framework for scalar field theory and can be applied to particle production processes where the effects of spin can be neglected.

Norbury, John W.; Dick, Frank; Norman, Ryan B.; Nasto, Rachel

2008-01-01

153

Transport cross sections for collisions between particles  

NASA Astrophysics Data System (ADS)

A computer program is described for calculating transport cross sections for collisions governed by tabulated interaction potentials between structureless particles. This program takes special care to treat multiple orbiting, where two or more sets of orbiting impact parameters and orbiting separations occur at the same energy. The program also takes into account situations where the long-range potential is repulsive.

Viehland, Larry A.; Chang, Yongbin

2010-10-01

154

Windows in direct dissociative recombination cross sections  

NASA Technical Reports Server (NTRS)

Model potential curves are used to show that large windows are present in direct dissociative-recombination cross sections from excited molecular-ion vibrational levels. The windows are due to the overlap of vibrational wave functions of the repulsive neutral states with the nodes of the ion vibrational wave function.

Guberman, Steven L.

1986-01-01

155

Dijet cross sections in photoproduction at HERA  

Microsoft Academic Search

Dijet production by almost real photons has been studied at HERA with the ZEUS detector. Jets have been identified using the cone algorithm. A cut on x?OBS, the fraction of the photon energy participating in the production of the two jets of highest transverse energy, is used to define cross sections sensitive to the parton distributions in the proton and

S. Bhadra; M. L. Cardy; C.-P. Fagerstroem; W. R. Frisken; K. M. Furutani; M. Khakzad; W. B. Schmidke; R. L. Talaga; H. Zhang; R. Ayad; G. Bari; M. Basile; L. Bellagamba; D. Boscherini; A. Bruni; G. Bruni; P. Bruni; G. Cara Romeo; G. Castellini; M. Chiarini; L. Cifarelli; F. Cindolo; A. Contin; M. Corradi; I. Gialas; P. Giusti; G. Iacobucci; G. Laurenti; G. Levi; A. Margotti; T. Massam; R. Nania; C. Nemoz; F. Palmonari; A. Polini; G. Sartorelli; R. Timellini; Y. Zamora Garcia; A. Zichichi; A. Bargende; J. Crittenden; K. Desch; B. Diekmann; T. Doeker; M. Eckert; L. Feld; A. Frey; M. Geerts; G. Geitz; M. Grothe; T. Haas; H. Hartmann; D. Haun; K. Heinloth; E. Hilger; H.-P. Jakob; U. F. Katz; S. M. Mari; A. Mass; S. Mengel; J. Mollen; E. Paul; Ch. Rembser; R. Schattevoy; D. Schramm; J. Stamm; R. Wedemeyer; S. Campbell-Robson; A. Cassidy; N. Dyce; B. Foster; S. George; R. Gilmore; G. P. Heath; H. F. Heath; T. J. Llewellyn; C. J. S. Morgado; D. J. P. Norman; J. A. O'Mara; R. J. Tapper; S. S. Wilson; R. Yoshida; R. R. Rau; M. Arneodo; L. Iannotti; M. Schioppa; G. Susinno; A. Bernstein; A. Caldwell; N. Cartiglia; J. A. Parsons; S. Ritz; F. Sciulli; P. B. Straub; L. Wai; S. Yang; Q. Zhu; P. Borzemski; J. Chwastowski; A. Eskreys; K. Piotrzkowski; M. Zachara; L. Zawiejski; L. Adamczyk; B. Bednarek; K. Jelen; D. Kisielewska; T. Kowalski; E. Rulikowska-Zarebska; L. Suszycki; J. Zajac; A. Kotanski; M. Przybycien; L. A. T. Bauerdick; U. Behrens; H. Beier; J. K. Bienlein; C. Coldewey; O. Deppe; K. Desler; G. Drews; M. Flasinski; D. J. Gilkinson; C. Glasman; P. Göttlicher; J. Große-Knetter; B. Gutjahr; W. Hain; D. Hasell; H. Heßling; H. Hultschig; Y. Iga; P. Joos; M. Kasemann; R. Klanner; W. Koch; L. Köpke; U. Kötz; H. Kowalski; J. Labs; A. Ladage; B. Löhr; M. Löwe; D. Lüke; O. Manczak; J. S. T. Ng; S. Nickel; D. Notz; K. Ohrenberg; M. Roco; M. Rohde; J. Roldán; U. Schneekloth; W. Schulz; F. Selonke; E. Stiliaris; B. Surrow; T. Voß; D. Westphal; G. Wolf; C. Youngman; J. F. Zhou; H. J. Grabosch; A. Kharchilava; A. Leich; M. Mattingly; A. Meyer; S. Schlenstedt; N. Wulff; G. Barbagli; P. Pelfer; G. Anzivino; G. Maccarrone; S. de Pasquale; L. Votano; A. Bamberger; S. Eisenhardt; A. Freidhof; S. Söldner-Rembold; J. Schroeder; T. Trefzger; N. H. Brook; P. J. Bussey; A. T. Doyle; J. I. Fleck; D. H. Saxon; M. L. Utley; A. S. Wilson; A. Dannemann; U. Holm; D. Horstmann; T. Neumann; R. Sinkus; K. Wick; E. Badura; B. D. Burow; L. Hagge; E. Lohrmann; J. Mainusch; J. Milewski; M. Nakahata; N. Pavel; G. Poelz; W. Schott; F. Zetsche; T. C. Bacon; I. Butterworth; E. Gallo; V. L. Harris; B. Y. H. Hung; K. R. Long; D. B. Miller; P. P. O. Morawitz; A. Prinias; J. K. Sedgbeer; A. F. Whitfield; U. Mallik; E. McCliment; M. Z. Wang; S. M. Wang; J. T. Wu; Y. Zhang; P. Cloth; D. Filges; S. H. An; S. M. Hong; S. W. Nam; S. K. Park; M. H. Suh; S. H. Yon; R. Imlay; S. Kartik; H.-J. Kim; R. R. McNeil; W. Metcalf; V. K. Nadendla; F. Barreiro; G. Cases; R. Graciani; J. M. Hernández; L. Hervás; L. Labarga; J. del Peso; J. Puga; J. Terron; J. F. de Trocóniz; G. R. Smith; F. Corriveau; D. S. Hanna; J. Hartmann; L. W. Hung; J. N. Lim; C. G. Matthews; P. M. Patel; L. E. Sinclair; D. G. Stairs; M. St. Laurent; R. Ullmann; G. Zacek; V. Bashkirov; B. A. Dolgoshein; A. Stifutkin; G. L. Bashindzhagyan; P. F. Ermolov; L. K. Gladilin; Y. A. Golubkov; V. D. Kobrin; V. A. Kuzmin; A. S. Proskuryakov; A. A. Savin; L. M. Shcheglova; A. N. Solomin; N. P. Zotov; M. Botje; F. Chlebana; A. Dake; J. Engelen; M. de Kamps; P. Kooijman; A. Kruse; H. Tiecke; W. Verkerke; M. Vreeswijk; L. Wiggers; E. de Wolf; R. van Woudenberg; D. Acosta; B. Bylsma; L. S. Durkin; K. Honscheid; C. Li; T. Y. Ling; K. W. McLean; W. N. Murray; I. H. Park; T. A. Romanowski; R. Seidlein; D. S. Bailey; G. A. Blair; A. Byrne; R. J. Cashmore; A. M. Cooper-Sarkar; D. Daniels; R. C. E. Devenish; N. Harnew; M. Lancaster; P. E. Luffman; L. Lindemann; J. D. McFall; C. Nath; V. A. Noyes; A. Quadt; H. Uijterwaal; R. Walczak; F. F. Wilson; T. Yip; G. Abbiendi; A. Bertolin; R. Brugnera; R. Carlin; F. Dal Corso; M. de Giorgi; U. Dosselli; S. Limentani; M. Morandin; M. Posocco; L. Stanco; R. Stroili; C. Voci; J. Bulmahn; J. M. Butterworth; R. G. Feild; B. Y. Oh; J. J. Whitmore; G. D'Agostini; G. Marini; A. Nigro; E. Tassi; J. C. Hart; N. A. McCubbin; K. Prytz; T. P. Shah; T. L. Short; E. Barberis; T. Dubbs; C. Heusch; M. van Hook; B. Hubbard; W. Lockman; J. T. Rahn; H. F.-W. Sadrozinski; A. Seiden; J. Biltzinger; R. J. Seifert; A. H. Walenta; G. Zech; H. Abramowicz; G. Briskin; S. Dagan; A. Levy; T. Hasegawa; M. Hazumi; T. Ishii; M. Kuze; S. Mine; Y. Nagasawa; M. Nakao; I. Suzuki; K. Tokushuku; S. Yamada; Y. Yamazaki; M. Chiba; R. Hamatsu; T. Hirose; K. Homma; S. Kitamura; Y. Nakamitsu; K. Yamauchi; R. Cirio; M. Costa; M. I. Ferrero; L. Lamberti; S. Maselli; C. Peroni

1995-01-01

156

Testing (Validating?) Cross Sections with ICSBEP Benchmarks  

SciTech Connect

We discuss how to use critical benchmarks from the International Handbook of Evaluated Criticality Safety Benchmark Experiments to determine the applicability of specific cross sections to the end-user's problem of interest. Particular attention is paid to making sure the selected suite of benchmarks includes the user's range of applicability (ROA).

Kahler, Albert C. III [Los Alamos National Laboratory

2012-06-28

157

Neutron scattering lengths and cross sections  

Microsoft Academic Search

The application of thermal neutron scattering to the study of the structure and dynamics of condensed matter requires a knowledge of the scattering lengths and the corresponding scattering and absorption cross sections of the elements. Ln some cases, values for the individual isotopes are needed as well. This information is required to obtain an absolute normalization ofthe scatteredneutron distributions, tocalculate

Varley F. Sears

1992-01-01

158

Stratigraphic Cross Section of Northeast Texas  

NSDL National Science Digital Library

Cretaceous sedimentary rocks of Northeast Texas provide important clues about paleogeography, paleotectonics, and sea level fluctuation. This website describes several of these rock units and the geologic information they supply. An unpublished report with a thorough discussion, map, cross section, and numerous references is provided. Specific topics include Cretaceous stratigraphy, lithostratigraphic and biostratigraphic correlation, ammonites, Western Interior Seaway, Skull Creek Seaway, paleogeography, and paleotectonics.

Minor Keith

159

Photoelectric absorption cross sections with variable abundances  

NASA Technical Reports Server (NTRS)

Polynomial fit coefficients have been obtained for the energy dependences of the photoelectric absorption cross sections of 17 astrophysically important elements. These results allow the calculation of X-ray absorption in the energy range 0.03-10 keV in material with noncosmic abundances.

Balucinska-Church, Monika; Mccammon, Dan

1992-01-01

160

Optical absorption cross sections of Si nanocrystals  

Microsoft Academic Search

Using the photoluminescence Auger saturation phenomenon, we deduce the values of the absorption cross section of silicon nanocrystals in a wide range of energies. The very large variation of their values versus energy of the absorbed light is attributed to the enhanced optical transition oscillator strength but reduced density of electronic states towards higher confinement energies. The overall spectral behavior

D. Kovalev; J. Diener; H. Heckler; G. Polisski; N. Künzner; F. Koch

2000-01-01

161

GMM estimation with cross sectional dependence  

Microsoft Academic Search

This paper presents a spatial model of dependence among agents using a metric of economic distance. Measurements of this economic distance provide cross-sectional data with a structure similar to that provided by the time index in time-series data. Generalized method of moments estimators using such dependent data are shown to be consistent and asymptotically normal. This paper presents a class

T. G. Conley

1999-01-01

162

Cross section for charmonium absorption by nucleons  

E-print Network

. Including both two-body and three-body final states, we find that with a cutoff parameter of 1 GeV at interaction vertices involving charm hadrons, the J/psi-N absorption cross section is at most 5 mb and is consistent with that extracted from J...

Liu, W.; Ko, Che Ming; Lin, ZW.

2002-01-01

163

Cross sections relevant to gamma ray astronomy  

NASA Technical Reports Server (NTRS)

Gamma-ray production cross sections were measured for protons and alpha particles incident on targets consisting of nuclei of high cosmic abundance: C-12, N-14, O-16, Ne-20, Mg-24, Si-28 and Fe-56. Solid or gaseous targets were bombarded by monoenergetic beams of protons and alpha particles, and gamma rays were detected by two Ge(Li) detectors. The proton energy for each target was varied from threshold to about 24 MeV (lab); for alphas the range was from threshold to about 27 MeV. For most transitions, it was possible to measure the total cross section by placing the detectors at 30.5 deg and 109.9 deg where the fourth-order Legendre polynomial is zero. For the case of the 16O (E sub gamma = 6.13 MeV, multipolarity E3) cross sections, yields were measured at four angles. Absolute cross sections were obtained by integrating the beam current and by measuring target thicknesses and detector efficiencies. The Ge(Li) detector resolution was a few keV (although the peak widths were greater, due to Doppler broadening).

Dyer, P.; Bodansky, D.; Maxson, D. R.

1978-01-01

164

Cross-sectional area of the mandible  

Microsoft Academic Search

Purpose: The anatomy of the mandible was examined by measuring the cross-sectional area (CSA) of multiple regions of 10 fully dentulous hemimandibles to provide a better understanding of regional structural differences that may have implications regarding biomechanical strength, surgical reconstruction, and fracture site frequency.Materials and Methods: Fifteen cuts from the condyle to the symphysis were made of each hemimandible (n

Warren Schubert; Brian J Kobienia; Richard A Pollock

1997-01-01

165

Tables of nuclear cross sections for galactic cosmic rays: Absorption cross sections  

NASA Technical Reports Server (NTRS)

A simple but comprehensive theory of nuclear reactions is presented. Extensive tables of nucleon, deuteron, and heavy-ion absorption cross sections over a broad range of energies are generated for use in cosmic ray shielding studies. Numerous comparisons of the calculated values with available experimental data show agreement to within 3 percent for energies above 80 MeV/nucleon and within approximately 10 percent for energies as low as 30 MeV/nucleon. These tables represent the culmination of the development of the absorption cross section formalism and supersede the preliminary absorption cross sections published previously in NASA TN D-8107, NASA TP-2138, and NASA TM-84636.

Townsend, L. W.; Wilson, J. W.

1985-01-01

166

Absolute np and pp Cross Section Determinations Aimed At Improving The Standard For Cross Section Measurements  

SciTech Connect

Purpose of present research is a keeping improvement of the standard for cross section measurements of neutron-induced reactions. The cross sections for np and pp scattering below 1 GeV are determined based on partial-wave analyses (PWAs) of nucleon-nucleon scattering data. These cross sections are compared with the most recent ENDF/B-VII.0 and JENDL-4.0 data files, and the Nijmegen PWA. Also a comparison of evaluated data with recent experimental data was made to check a quality of evaluation. Excellent agreement was found between the new experimental data and our PWA predictions.

Laptev, A. B.; Haight, R. C.; Tovesson, F. [Los Alamos National Laboratory, Los Alamos NM 87545 (United States); Arndt, R. A.; Briscoe, W. J.; Paris, M. W.; Strakovsky, I. I.; Workman, R. L. [George Washington University, Washington DC 20052 (United States)

2011-06-01

167

Absolute np and pp cross section determinations aimed at improving the standard for cross section measurements  

SciTech Connect

Purpose of present research is a keeping improvement of the standard for cross section measurements of neutron-induced reactions. The cross sections for np and pp scattering below 1000 MeV are determined based on partial-wave analyses (PW As) of nucleon-nucleon scattering data. These cross sections are compared with the most recent ENDF/B-V11.0 and JENDL-4.0 data files, and the Nijmegen PWA. Also a comparison of evaluated data with recent experimental data was made to check a quality of evaluation. Excellent agreement was found between the new experimental data and our PWA predictions.

Laptev, Alexander B [Los Alamos National Laboratory; Haight, Robert C [Los Alamos National Laboratory; Tovesson, Fredrik [Los Alamos National Laboratory; Arndt, Richard A [GWU; Briscoe, William J [GWU; Paris, Mark W [GWU; Strakovsky, Igor I [GWU; Workman, Ron L [GWU

2010-01-01

168

Modeling the Meteoroid Input Function at Mid-Latitude Using Meteor Observations by the MU Radar  

NASA Technical Reports Server (NTRS)

The Meteoroid Input Function (MIF) model has been developed with the purpose of understanding the temporal and spatial variability of the meteoroid impact in the atmosphere. This model includes the assessment of potential observational biases, namely through the use of empirical measurements to characterize the minimum detectable radar cross-section (RCS) for the particular High Power Large Aperture (HPLA) radar utilized. This RCS sensitivity threshold allows for the characterization of the radar system s ability to detect particles at a given mass and velocity. The MIF has been shown to accurately predict the meteor detection rate of several HPLA radar systems, including the Arecibo Observatory (AO) and the Poker Flat Incoherent Scatter Radar (PFISR), as well as the seasonal and diurnal variations of the meteor flux at various geographic locations. In this paper, the MIF model is used to predict several properties of the meteors observed by the Middle and Upper atmosphere (MU) radar, including the distributions of meteor areal density, speed, and radiant location. This study offers new insight into the accuracy of the MIF, as it addresses the ability of the model to predict meteor observations at middle geographic latitudes and for a radar operating frequency in the low VHF band. Furthermore, the interferometry capability of the MU radar allows for the assessment of the model s ability to capture information about the fundamental input parameters of meteoroid source and speed. This paper demonstrates that the MIF is applicable to a wide range of HPLA radar instruments and increases the confidence of using the MIF as a global model, and it shows that the model accurately considers the speed and sporadic source distributions for the portion of the meteoroid population observable by MU.

Pifko, Steven; Janches, Diego; Close, Sigrid; Sparks, Jonathan; Nakamura, Takuji; Nesvorny, David

2012-01-01

169

Photonuclear Reaction Cross Sections for Gallium Isotopes  

E-print Network

The photon induced reactions which are named as photonuclear reactions have a great importance in many field of nuclear, radiation physics and related fields. Since we have planned to perform photonuclear reaction on gallium target with bremmstrahlung photons from clinical linear accelerator in the future, the cross-sections of neutron (photo-neutron ({\\gamma},xn)) and proton (photo-proton ({\\gamma},xn)) productions after photon activation have been calculated by using TALYS 1.2 computer code in this study. The target nucleus has been considered gallium which has two stable isotopes, 69Ga and 71Ga. According to the results, we have seen that the calculations are in harmony in the limited literature values. Furthermore, the pre-equilibrium and compound process contributions to the total cross-section have been investigated.

Serkan Akkoyun; Tuncay Bayram

2014-09-08

170

Electron capture cross sections for stellar nucleosynthesis  

E-print Network

In the first stage of this work, we perform detailed calculations for the cross sections of the electron capture on nuclei under laboratory conditions. Towards this aim we exploit the advantages of a refined version of the proton-neutron quasi-particle random-phase approximation (pn-QRPA) and carry out state-by-state evaluations of the rates of exclusive processes that lead to any of the accessible transitions within the chosen model space. In the second stage of our present study, we translate the above mentioned $e^-$-capture cross sections to the stellar environment ones by inserting the temperature dependence through a Maxwell-Boltzmann distribution describing the stellar electron gas. As a concrete nuclear target we use the $^{66}Zn$ isotope, which belongs to the iron group nuclei and plays prominent role in stellar nucleosynthesis at core collapse supernovae environment.

P. G. Giannaka; T. S. Kosmas

2015-02-25

171

Electron capture cross sections for stellar nucleosynthesis  

E-print Network

In the first stage of this work, we perform detailed calculations for the cross sections of the electron capture on nuclei under laboratory conditions. Towards this aim we exploit the advantages of a refined version of the proton-neutron quasi-particle random-phase approximation (pn-QRPA) and carry out state-by-state evaluations of the rates of exclusive processes that lead to any of the accessible transitions within the chosen model space. In the second stage of our present study, we translate the above mentioned $e^-$-capture cross sections to the stellar environment ones by inserting the temperature dependence through a Maxwell-Boltzmann distribution describing the stellar electron gas. As a concrete nuclear target we use the $^{66}Zn$ isotope, which belongs to the iron group nuclei and plays prominent role in stellar nucleosynthesis at core collapse supernovae environment.

Giannaka, P G

2015-01-01

172

Universal Parameterization of Absorption Cross Sections  

NASA Technical Reports Server (NTRS)

This paper presents a simple universal parameterization of total reaction cross sections for any system of colliding nuclei that is valid for the entire energy range from a few AMeV to a few AGeV. The universal picture presented here treats proton-nucleus collision as a special case of nucleus-nucleus collision, where the projectile has charge and mass number of one. The parameters are associated with the physics of the collision system. In general terms, Coulomb interaction modifies cross sections at lower energies, and the effects of Pauli blocking are important at higher energies. The agreement between the calculated and experimental data is better than all earlier published results.

Tripathi, R. K.; Cucinotta, Francis A.; Wilson, John W.

1997-01-01

173

Accurate universal parameterization of absorption cross sections  

NASA Technical Reports Server (NTRS)

We present a simple universal parameterization of total reaction cross sections for any system of colliding nuclei valid for the entire energy range from a few A MeV to a few A GeV. The universal picture presented here treats the proton-nucleus collision as a special case of the nucleus-nucleus collision, where the projectile has charge and mass number one. The parameters are associated with the physics of the collision system. In general terms Coulomb interaction modifies cross sections at lower energies and the effects of Pauli blocking are important at higher energies. The agreement between the calculated and experimental data is better than all earlier published results.

Tripathi, R. K.; Cucinotta, F. A.; Wilson, J. W.

1996-01-01

174

Inclusive jet cross section at the Tevatron  

SciTech Connect

The authors report preliminary measurements of the central inclusive jet cross section at 1.8 TeV by the D0 and the CDF collaborations at the p{anti p} Fermilab collider. They are based on an integrated luminosity of 92 and 87 pb-1, respectively. The cross sections are measured as a function of jet transverse energy in the pseudorapidity interval 0.1 < 1,711 < 0.7 (CDF), and the two pseudorapidity ranges 1,711 < 0.5 and 0.1 < Inj < 0.7 (D0). D0 reports good agreement with the Next-to-Leading Order QCD predictions currently available. CDF observes an excess above 200 GeV, which can be accommodated with a modification in the gluon distribution function at high x.

NONE

1998-01-01

175

Inclusive jet cross section at CDF  

SciTech Connect

This contribution reports on preliminary measurements of the inclusive jet production cross section in p{bar p} collisions at {radical}s = 1.96 TeV using data collected with CDF corresponding to an integrated luminosity of 385 pb{sup -1}. Two analyzes are presented: one uses the longitudinally invariant k{sub T} algorithm to reconstruct the jets, the other uses the midpoint algorithm. Both are limited to jets with rapidity in the range 0.1 < |y{sup jet}| < 0.7. The measured cross sections are in good agreement with next-to-leading order perturbative QCD predictions after including the non-perturbative corrections necessary to account for underlying event and hadronization effects.

Lefevre, R.; Martinez, M.; /Barcelona, IFAE

2005-01-01

176

Electron-collision cross sections for iodine  

SciTech Connect

We present results from a joint experimental and theoretical study of elastic electron scattering from atomic iodine. The experimental results were obtained by subtracting known cross sections from the measured data obtained with a pyrolyzed mixed beam containing a variety of atomic and molecular species. The calculations were performed using both a fully relativistic Dirac B-spline R-matrix (close-coupling) method and an optical model potential approach. Given the difficulty of the problem, the agreement between the two sets of theoretical predictions and the experimental data for the angle-differential and the angle-integrated elastic cross sections at 40 eV and 50 eV is satisfactory.

Zatsarinny, O.; Bartschat, K. [Department of Physics and Astronomy, Drake University, Des Moines, Iowa 50311 (United States); Garcia, G. [Instituto de Fisica Fundamental, Consejo Superior de Investigaciones Cientificas, Madrid E-28006 (Spain); Blanco, F. [Departamento de Fisica Atomica, Molecular y Nuclear, Universidad Complutense de Madrid, Madrid E-28040 (Spain); Hargreaves, L.R.; Jones, D.B.; Murrie, R.; Brunton, J.R. [ARC Centre for Antimatter-Matter Studies, School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Brunger, M.J. [ARC Centre for Antimatter-Matter Studies, School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, 50603, Kuala Lumpur (Malaysia); Hoshino, M. [Department of Materials and Life Sciences, Sophia University, Chiyoda ku, Tokyo 102-8554 (Japan); Buckman, S.J. [ARC Centre for Antimatter-Matter Studies, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia)

2011-04-15

177

Neutron total cross section of 40Ca and cross section difference of 44Ca  

Microsoft Academic Search

We have used a 100-MeV electron linac and neutron time-of-flight facility to measure the neutron total cross section of 40Ca and the cross section difference of 44Ca- 40Ca for incident neutron energies of 6-60 MeV. Optical model calculations of 40Ca sigmaT have been made and compared to the data. Modifications of a global set of optical model parameters necessary to

H. S. Camarda; T. W. Phillips; R. M. White

1986-01-01

178

Production of microwave plasma in narrow cross sectional tubes: Effect of the shape of cross section  

Microsoft Academic Search

A microwave plasma is produced in a conducting tube with a cross section smaller than the cutoff value. Waves of 2.45 GHz are launched perpendicularly to the multicusp magnetic field formed by permanent magnets surrounding the tube. Circular and square cross sectional tubes are tested. Overdense plasmas with a density of (0.8-2.0)×1011 cm-3 are obtained in the range of 10-4

Sudeep Bhattacharjee; Hiroshi Amemiya

1999-01-01

179

Non-circular cross-section stellarators  

Microsoft Academic Search

The magnetic surfaces and rotational transform of a stellarator with low poloidal-field wave number and elliptical minor cross-section have been computed numerically by utilizing a predictor-corrector code. The surfaces exhibit stagnation points the positions of which are related to the aspect ratio of the ellipse and the ?-number of the configuration. The rotational transform is less than in an equivalent

J. L. Shohet; D. T. Anderson; J. A. Tataronis

1976-01-01

180

{sup 231}Pa photofission cross section  

SciTech Connect

The measurements of the {sup 231}Pa yield and cross section photofission in the energy range 7-9 MeV are presented. These measurements are a continuation of similar measurements performed for the {gamma}-ray energy range 4.8-7 MeV. The entire collection of experimental data which combine the results obtained in the present work and in Ref. 1 was analyzed.

Soldatov, A.S.; Rudnikov, V.E.; Smirenkin, G.N.

1995-12-01

181

Ultrasonic cross-sectional imaging apparatus  

SciTech Connect

An ultrasonic cross-sectional imaging apparatus comprising an ultrasonic probe, memory means and display means. The probe emits ultrasonic waves in non-interlaced fashion and receives echo data in non-interlaced fashion. The non-interlaced echo data are written into the memory means, read out therefrom in interlaced fashion and displayed by the display means as an image in interlaced fashion.

Yoshikawa, N.

1981-03-24

182

How to Calculate Colourful Cross Sections Efficiently  

SciTech Connect

Different methods for the calculation of cross sections with many QCD particles are compared. To this end, CSW vertex rules, Berends-Giele recursion and Feynman-diagram based techniques are implemented as well as various methods for the treatment of colours and phase space integration. We find that typically there is only a small window of jet multiplicities, where the CSW technique has efficiencies comparable or better than both of the other two methods.

Gleisberg, Tanju; Hoeche, Stefan; Krauss, Frank

2008-09-03

183

How to calculate colourful cross sections efficiently  

E-print Network

Different methods for the calculation of cross sections with many QCD particles are compared. To this end, CSW vertex rules, Berends-Giele recursion and Feynman-diagram based techniques are implemented as well as various methods for the treatment of colours and phase space integration. We find that typically there is only a small window of jet multiplicities, where the CSW technique has efficiencies comparable or better than both of the other two methods.

Gleisberg, Tanju; Krauss, Frank

2008-01-01

184

How to calculate colourful cross sections efficiently  

E-print Network

Different methods for the calculation of cross sections with many QCD particles are compared. To this end, CSW vertex rules, Berends-Giele recursion and Feynman-diagram based techniques are implemented as well as various methods for the treatment of colours and phase space integration. We find that typically there is only a small window of jet multiplicities, where the CSW technique has efficiencies comparable or better than both of the other two methods.

Tanju Gleisberg; Stefan Hoeche; Frank Krauss

2008-08-27

185

Radar Cross Section Measurements of Frequency Selective Terahertz Retroreflectors  

E-print Network

was measured at 100 GHz, 160 GHz, and 350 GHz. A frequency selective surface was applied to the retroreflectors-section, retroreflector, frequency selective surfaces, terahertz, novel structures, narrow-band, band-pass filter trackers for GPS satellites [4]. A frequency selective surface (FSS) is a periodic structure serving

Massachusetts at Lowell, University of

186

Cross sections for electron scattering from magnesium  

SciTech Connect

A B-spline R-matrix (close-coupling) method has been used to perform a systematic study of angle-differential cross sections for electron scattering from neutral magnesium. The calculations cover elastic scattering and excitation of the five excited states (3s3p) {sup 3,1}P{sup o}, (3s3d) {sup 1}D, (3s4s) {sup 1}S, and (3s4p) {sup 1}P{sup o}. A multiconfiguration Hartree-Fock method with nonorthogonal orbitals was employed for an accurate representation of the target wave functions. The close-coupling expansion for the collision problem included 37 bound states of neutral magnesium. Angle-differential cross sections are presented for incident electron energies from 10 to 100 eV. These results, as well as the corresponding angle-integrated cross sections, are compared with various experimental data and predictions from other close-coupling and distorted-wave calculations. In spite of a few remaining discrepancies, the overall agreement between our results and the experimental data is very satisfactory.

Zatsarinny, Oleg; Bartschat, Klaus; Gedeon, Sergey; Gedeon, Viktor; Lazur, Vladimir; Nagy, Elizabeth [Department of Physics and Astronomy, Drake University, Des Moines, Iowa 50311 (United States); Department of Theoretical Physics, Uzhgorod State University, Uzhgorod 88000 (Ukraine)

2009-05-15

187

Radio science issues surrounding HF/VHF/UHF radar meteor studies  

NASA Astrophysics Data System (ADS)

Classical meteor radars depend on coherent (Fresnel) scattering from a meteor trail oriented perpendicular to the radar wave vector at closest approach to the radar. Meteor trails viewed in this manner are described as ``classical'' radar meteors with under/over-dense trails. While meteor ``head-echoes'' are rarely seen with classical low-power, wide-beam HF meteor radars, they are essentially always seen by large aperture (narrow-beam), high-power VHF/UHF radars. We discuss the expected radar scattering cross-sections (RCSs) of head-versus trail-echoes and how equilibrium concepts such as plasma frequency are of limited use in describing the results. Particular attention is given to the frequency dependence of the RCS and how the frequency dependence may yield considerable new information regarding the plasma distribution in the ``coma'' surrounding the meteoroid. As the head-echo is directly associated with the meteoroid, instantaneous (single-pulse) Doppler observations are possible. In the case of classical trail-echoes, the time evolution of the RCS as a function of frequency may provide new information on the plasma diffusion rate and thus on atmospheric density and temperature. Information from the time evolution of the trail must however be considered in light of new results showing that the trail rapidly B-field-aligns in a manner apparently driven by plasma instabilities that develop in 10-100ms after trail deposition. It is in the context of instability-driven B-field alignment of the trails that we discuss anomalous trail-echoes. The anomalous trail-echo is a range-spread chaotic (non-classical) trail-echo derived from a meteor that travels at an arbitrary angle relative to the radar wave vector. We present theoretical simulations illustrating these concepts.

Mathews, J. D.

2004-02-01

188

Statistics of cross sections of Voronoi tessellations  

NASA Astrophysics Data System (ADS)

In this paper, we investigate relationships between the volumes of cells of three-dimensional Voronoi tessellations and the lengths and areas of sections obtained by intersecting the tessellation with a randomly oriented plane. Here, in order to obtain analytical results, Voronoi cells are approximated to spheres. First, the probability density function for the lengths of the radii of the sections is derived and it is shown that it is related to the Meijer G function; its properties are discussed and comparisons are made with the numerical results. Next, the probability density function for the areas of cross sections is computed and compared with the results of numerical simulations.

Ferraro, M.; Zaninetti, L.

2011-10-01

189

NIST XCOM: Photon Cross Sections Database  

NSDL National Science Digital Library

This web program, funded in part by the National Institute of Standards and Technology (U.S.) is used to calculate photon cross sections for scattering, photoelectric absorption and pair production, as well as total attenuation coefficients, in any element, compound or mixture, at energies from 1 keV to 100 GeV. The contents section of the site contains an introduction, database for elements, interpolation and combination, instructions on how to run the XCOM program, and references. The site allows you to download a copy of XCOM (v. 3.1) for personal use.

190

Cross section measurements with monoenergetic muon neutrinos  

NASA Astrophysics Data System (ADS)

The monoenergetic 236 MeV muon neutrino from charged kaon decay at rest (K+??+??) can be used to produce a novel set of cross section measurements. Applicable for short- and long-baseline accelerator-based neutrino oscillation experiments, among others, such measurements would provide a "standard candle" for the energy reconstruction and interaction kinematics relevant for charged current neutrino events near this energy. This neutrino can also be exercised as a unique known-energy, purely weak interacting probe of the nucleus. A number of experiments are set to come online in the next few years that will be able to collect and characterize thousands of these events.

Spitz, J.

2014-04-01

191

Absolute photoneutron cross sections of Sm isotopes  

NASA Astrophysics Data System (ADS)

Photoneutron cross sections for seven samarium isotopes, 144Sm , 147Sm , 148Sm , 149Sm , 150Sm , 152Sm and 154Sm , have been investigated near neutron emission threshold using quasimonochromatic laser-Compton scattering ?-rays produced at the synchrotron radiation facility NewSUBARU. The results are important for nuclear astrophysics calculations and also for probing ?-ray strength functions in the vicinity of neutron threshold. Here we describe the neutron detection system and we discuss the related data analysis and the necessary method improvements for adapting the current experimental method to the working parameters of the future Gamma Beam System of Extreme Light Infrastructure - Nuclear Physics facility.

Gheorghe, I.; Utsunomiya, H.; Filipescu, D.; Glodariu, T.; Nyhus, H.-T.; Renstro/m, T.; Tesileanu, O.; Shima, T.; Takahisa, K.; Miyamoto, S.

2015-02-01

192

Top Production Cross Sections at D0  

SciTech Connect

We report on measurements of the ttbar production cross section at a center-of-mass energy of 1.96 TeV at the D0 experiment during Run II of the Fermilab Tevatron collider. We use candidate events in lepton+jets and dilepton final states. In the most sensitive channel (lepton+jets channel), a neural network algorithm that uses lifetime information to identify b-quark jets is used to distinguish signal from background processes. We also present measurements of single top quark production at D0 using several multivariate techniques to separate signal from background.

Kvita, Jiri

2009-07-01

193

Signal analysis by means of time-frequency (Wigner-type) distributions -- Applications to sonar and radar echoes  

SciTech Connect

Time series data have been traditionally analyzed in either the time or the frequency domains. For signals with a time-varying frequency content, the combined time-frequency (TF) representations, based on the Cohen class of (generalized) Wigner distributions (WD`s) offer a powerful analysis tool. Using them, it is possible to: (1) trace the time-evolution of the resonance features usually present in a standard sonar cross section (SCS), or in a radar cross section (RCS) and (2) extract target information that may be difficult to even notice in an ordinary SCS or RCS. After a brief review of the fundamental properties of the WD, the authors discuss ways to reduce or suppress the cross term interference that appears in the WD of multicomponent systems. These points are illustrated with a variety of three-dimensional (3-D) plots of Wigner and pseudo-Wigner distributions (PWD), in which the strength of the distribution is depicted as the height of a Wigner surface with height scales measured by various color shades or pseudocolors. The authors also review studies they have made of the echoes returned by conducting or dielectric targets in the atmosphere, when they are illuminated by broadband radar pings. A TF domain analysis of these impulse radar returns demonstrates their superior informative content. These plots allow the identification of targets in an easier and clearer fashion than by the conventional RCS of narrowband systems. The authors show computed and measured plots of WD and PWD of various types of aircraft to illustrate the classification advantages of the approach at any aspect angle. They also show analogous results for metallic objects buried underground, in dielectric media, at various depths.

Gaunaurd, G. [Naval Surface Warfare Center, Silver Spring, MD (United States). Carderock Div.] [Naval Surface Warfare Center, Silver Spring, MD (United States). Carderock Div.; Strifors, H.C. [National Defense Research Establishment, Stockholm (Sweden)] [National Defense Research Establishment, Stockholm (Sweden)

1996-09-01

194

Total and ionization cross sections of electron scattering by fluorocarbons  

NASA Astrophysics Data System (ADS)

Electron impact total cross sections (50-2000 eV) and total ionization cross sections (threshold to 2000 eV) are calculated for typical plasma etching molecules CF4, C2F4, C2F6, C3F8 and CF3I and the CFx (x = 1-3) radicals. The total elastic and inelastic cross sections are determined in the spherical complex potential formalism. The sum of the two gives the total cross section and the total inelastic cross section is used to calculate the total ionization cross sections. The present total and ionization cross sections are found to be consistent with other theories and experimental measurements, where they exist. Our total cross section results for CFx (x = 1-3) radicals presented here are first estimates on these species.

Antony, B. K.; Joshipura, K. N.; Mason, N. J.

2005-02-01

195

Single-level resonance parameters fit nuclear cross-sections  

NASA Technical Reports Server (NTRS)

Least squares analyses of experimental differential cross-section data for the U-235 nucleus have yielded single level Breit-Wigner resonance parameters that fit, simultaneously, three nuclear cross sections of capture, fission, and total.

Drawbaugh, D. W.; Gibson, G.; Miller, M.; Page, S. L.

1970-01-01

196

EXPLAINING DISCREPANCIES BETWEEN LONGITUDINAL AND CROSS-SECTIONAL MODELS  

EPA Science Inventory

Discrepancies between estimates obtained from longitudinal studies analyzed cross-sectionally and longitudinally pose questions about the validity of cross-sectional estimates of change. n some cases these discrepancies are the result of period effects, cohort effects, or selecti...

197

Measurement of actinide neutron cross sections  

SciTech Connect

The maintenance of strong scientific expertise is criticalto the U.S. nuclear attribution community. It is particularly importantto train students in actinide chemistry and physics. Neutroncross-section data are vital components to strategies for detectingexplosives and fissile materials, and these measurements requireexpertise in chemical separations, actinide target preparation, nuclearspectroscopy, and analytical chemistry. At the University of California,Berkeley and the Lawrence Berkeley National Laboratory we have trainedstudents in actinide chemistry for many years. LBNL is a leader innuclear data and has published the Table of Isotopes for over 60 years.Recently, LBNL led an international collaboration to measure thermalneutron capture radiative cross sections and prepared the EvaluatedGamma-ray Activation File (EGAF) in collaboration with the IAEA. Thisfile of 35,000 prompt and delayed gamma ray cross-sections for allelements from Z=1-92 is essential for the neutron interrogation ofnuclear materials. LBNL has also developed new, high flux neutrongenerators and recently opened a 1010 n/s D+D neutron generatorexperimental facility.

Firestone, Richard B.; Nitsche, Heino; Leung, Ka-Ngo; Perry, DaleL.; English, Gerald

2003-06-15

198

Neutronic Cross Section Calculations on Fluorine Nucleus  

NASA Astrophysics Data System (ADS)

Certain light nuclei such as Lithium (Li), Beryllium (Be), Fluorine (F) (which are known as FL?BE) and its molten salt compounds (LiF, BeF2 and NaF) can serve as a coolant which can be used at high temperatures without reaching a high vapor pressure. These molten salt compounds are also a good neutron moderator. In this study, cross sections of neutron induced reactions have been calculated for fluorine target nucleus. The new calculations on the excitation functions of 19F( n, 2n), 19F( n, p), 19F( n, xn), 19F( n, xp) have been made. In these calculations, the pre-equilibrium and equilibrium effects have been investigated. The pre-equilibrium calculations involve the full exciton model and the cascade exciton model. The equilibrium effects are calculated according to the Weisskopf-Ewing model. Also in the present work, the ( n, 2n) and ( n, p) reaction cross sections have calculated by using evaluated empirical formulas developed by Tel et al. at 14-15 MeV energy. The multiple pre-equilibrium mean free path constant from internal transition have been investigated for 19F nucleus. The obtained results have been discussed and compared with the available experimental data.

Kara, A.; Tel, E.

2013-06-01

199

Electron Elastic-Scattering Cross-Section Database  

National Institute of Standards and Technology Data Gateway

SRD 64 NIST Electron Elastic-Scattering Cross-Section Database (PC database, no charge)   This database provides values of differential elastic-scattering cross sections, corresponding total elastic-scattering cross sections, phase shifts, and transport cross sections for elements with atomic numbers from 1 to 96 and for electron energies between 50 eV and 20,000 eV (in steps of 1 eV).

200

Total cross sections for electron scattering by oxides of iron  

Microsoft Academic Search

Total (elastic + inelastic) cross sections for electron impact on FeO, Fe2O3 and Fe3O4 have been calculated in the energy range 20–5000 eV by employing the additivity rule which expresses the total cross section of a molecule as an incoherent sum over the total cross sections of the constituent atoms of the molecule. The electron-atom cross sections have been obtained

K. L. Baluja; Anju Agrawal

1995-01-01

201

Evaluation of {sup 238}U inelastic scattering cross section  

SciTech Connect

A coupled-channels model is adopted for evaluation of {sup 238}U direct inelastic scattering cross sections to the excited levels which belong to the vibrational bands, as well as the ground state rotational band. A band-coupling-strength {beta} is determined from the experimental inelastic scattering cross section data. Experimental double differential cross sections (DDX) are also taken into account. The calculated level excitation cross sections and the calculated DDX reproduce consistently the available experimental data.

Kawano, Toshihiko; Fujikawa, Noboru; Yoshida, Kiyohiko; Kanda, Yukinori [Kyushu Univ., Fukuoka (Japan)

1994-12-31

202

Electron production in proton collisions: total cross sections  

Microsoft Academic Search

Existing data on the ionization of neutral atoms and molecules by proton impact are reviewed, and electron production cross-section data are collected. The three major experimental methods are discussed and possible sources of error identified. Some theoretical cross sections are discussed, and well-established methods of relating them to measured cross sections are reviewed. A mathematical equation is fitted to the

M. E. Rudd; Y. K Kim; D. H. Madison; J. W. Gallagher

1985-01-01

203

Viscous Flow through Pipes of Various Cross-Sections  

ERIC Educational Resources Information Center

An interesting variety of pipe cross-sectional shapes can be generated, for which the Navier-Stokes equations can be solved exactly. The simplest cases include the known solutions for elliptical and equilateral triangle cross-sections. Students can find pipe cross-sections from solutions of Laplace's equation in two dimensions, and then plot the…

Lekner, John

2007-01-01

204

Measurement of the lidar cross sections of cube corner arrays for laser ranging of satellites  

NASA Technical Reports Server (NTRS)

The satellite coordinate system necessary to describe the location and orientation of each cube corner in the array is discussed. The method of optical testing is described along with the gain function, and computational methods for deriving the gain function and experimental values for it. The velocity aberration is derived as a function of satellite orbit, a complete method for cross section evaluation is described, and finally the radar equation is described.

Minott, P. O.

1974-01-01

205

Calculation of Low-Energy Electron-Atom Transport Cross Sections from Total Cross-Section Measurements  

Microsoft Academic Search

Modified effective-range theory (MERT) is used to determine the cross sections necessary for calculation of electron-atom transport coefficients. Two means of obtaining the transport cross sections are given: (1) direct integration of the weighted MERT differential cross section, and (2) inserting MERT phase shifts in a partial-wave formula for the transport cross sections. Both of these approaches are applied to

R. L. Fox

1968-01-01

206

Graphs of the cross sections in the recommended Monte Carlo cross-section library at the Los Alamos Scientific Laboratory  

SciTech Connect

Graphs of all neutron cross sections and photon production cross sections on the Recommended Monte Carlo Cross Section (RMCCS) library have been plotted along with local neutron heating numbers. Values for anti ..nu.., the average number of neutrons per fission, are also given.

Soran, P.D.; Seamon, R.E.

1980-05-01

207

Stellar (n,?) Cross Section of 62Ni  

NASA Astrophysics Data System (ADS)

The 62Ni(n,?)63Ni(t1/2=100±2 yr) reaction plays an important role in the control of the flow path of the slow neutron-capture (s) nucleosynthesis process. We have measured for the first time the total cross section of this reaction for a quasi-Maxwellian (kT=25 keV) neutron flux. The measurement was performed by fast-neutron activation, combined with accelerator mass spectrometry to detect directly the 63Ni product nuclei. The experimental value of 28.4±2.8 mb, fairly consistent with a recent calculation, affects the calculated net yield of 62Ni itself and the whole distribution of nuclei with 62

Nassar, H.; Paul, M.; Ahmad, I.; Berkovits, D.; Bettan, M.; Collon, P.; Dababneh, S.; Ghelberg, S.; Greene, J. P.; Heger, A.; Heil, M.; Henderson, D. J.; Jiang, C. L.; Käppeler, F.; Koivisto, H.; O'Brien, S.; Pardo, R. C.; Patronis, N.; Pennington, T.; Plag, R.; Rehm, K. E.; Reifarth, R.; Scott, R.; Sinha, S.; Tang, X.; Vondrasek, R.

2005-03-01

208

Neutron scattering cross sections of iron  

SciTech Connect

Neutrons have been scattered on a sample of natural iron at 12 incident energies in the range between 9.4 MeV and 15.2 MeV. Differential cross sections measured at 30 to 40 angles (from 13 to 160 deg) were determined for the elastic scattering, for the inelastic scattering to the first excited state in {sup 56}Fe (Q = -0.847 MeV) and for pseudolevel energy bins (0.5 to 1.0 MeV) at excitation energies up to 5.5 MeV. At higher excitation energies the scattering spectrum is contaminated by scattered breakup neutrons from the source. The results of this work are compared with data from the literature.

Schmidt, D.; Mannhart, W.; Nolte, R. [PTB Braunschweig, Bundesallee (Germany)

1994-12-31

209

High-frequency techniques for RCS prediction of plate geometries and a physical optics/equivalent currents model for the RCS of trihedral corner reflectors, parts 1 and 2  

NASA Technical Reports Server (NTRS)

Formulations for scattering from the coated plate and the coated dihedral corner reflector are included. A coated plate model based upon the Uniform Theory of Diffraction (UTD) for impedance wedges was presented in the last report. In order to resolve inaccuracies and discontinuities in the predicted patterns using the UTD-based model, an improved model that uses more accurate diffraction coefficients is presented. A Physical Optics (PO) model for the coated dihedral corner reflector is presented as an intermediary step in developing a high-frequency model for this structure. The PO model is based upon the reflection coefficients for a metal-backed lossy material. Preliminary PO results for the dihedral corner reflector suggest that, in addition to being much faster computationally, this model may be more accurate than existing moment method (MM) models. An improved Physical Optics (PO)/Equivalent Currents model for modeling the Radar Cross Section (RCS) of both square and triangular, perfectly conducting, trihedral corner reflectors is presented. The new model uses the PO approximation at each reflection for the first- and second-order reflection terms. For the third-order reflection terms, a Geometrical Optics (GO) approximation is used for the first reflection; and PO approximations are used for the remaining reflections. The previously reported model used GO for all reflections except the terminating reflection. Using PO for most of the reflections results in a computationally slower model because many integrations must be performed numerically, but the advantage is that the predicted RCS using the new model is much more accurate. Comparisons between the two PO models, Finite-Difference Time-Domain (FDTD) and experimental data are presented for validation of the new model.

Balanis, Constantine A.; Polka, Lesley A.; Polycarpou, Anastasis C.

1994-01-01

210

Microscopic optical-model calculations of neutron total cross sections and cross section differences  

NASA Astrophysics Data System (ADS)

Using the microscopic optical model of Jeukenne, Lejeune, and Mahaux we have calculated the absolute neutron total cross sections and cross section differences of 140Ce, 139Ce, 141Ce, 142Ce, and 40Ca, 44Ca from 6-60 MeV and have made comparisons with experimental data. Except for 142Ce, reasonable agreement with the mass 140 data was achieved with proton densities ?p of the nuclei determined by ?- data and neutron densities determined by the relationship ?n=(N/Z)?p which implies ?rnp =1/2 -1/2=0. Satisfactory agreement with the 142Ce data was obtained by choosing a ?n for 142Ce with ?rnp=0.05 fm and by a 10% increase in the strength of the 142Ce imaginary potential. Similar choices of ?rnp and imaginary potential strength were made for 44Ca in trying to fit the 44Ca data. Previous phenomenological analyses carried out for this data are in qualitative agreement with our results, which imply that the addition of a few neutrons to a nucleus with a closed neutron shell yields a nucleus with a slightly thicker neutron skin and a larger neutron reaction cross section when compared to their closed shell isotopes.

Camarda, H. S.; Dietrich, F. S.; Phillips, T. W.

1989-05-01

211

Analysis of the Radar Reflectivity of Aircraft Vortex Wakes  

NASA Technical Reports Server (NTRS)

Radar has been proposed as a way to track wake vortices to reduce aircraft spacing and tests have revealed radar echoes from aircraft wakes in clear air. The results are always interpreted qualitatively using Tatarski's theory of weak scattering by isotropic atmospheric turbulence. The goal of the present work was to predict the value of the radar cross-section (RCS) using simpler models. This is accomplished in two steps. First, the refractive index is obtained. Since the structure of the aircraft wakes is different from atmospheric turbulence, three simple mechanisms specific to vortex wakes are considered: (1) Radial density gradient in a two-dimensional vortex, (2) three-dimensional fluctuations in the vortex cores, and (3) Adiabatic transport of the atmospheric fluid in a two-dimensional oval surrounding the pair of vortices. The index of refraction is obtained more precisely for the two-dimensional mechanisms than for the three-dimensional ones. In the second step, knowing the index of refraction, a scattering analysis is performed. Tatarski's weak scattering approximation is kept but the usual assumptions of a far-field and a uniform incident wave are dropped. Neither assumption is generally valid for a wake that is coherent across the radar beam. For analytical insight, a simpler approximation that invokes, in addition to weak scattering, the far-field and wide cylindrical beam assumptions, is also developed and compared with the more general analysis. The predicted RCS values for the oval surround the vortices (mechanism C) agree with the experiments of Bilson conducted over a wide range of frequencies. However, the predictions have a cut-off away from normal incidence which is not present in the measurements. Estimates suggest that this is due to turbulence in the baroclinic vorticity generated at the boundary of the oval. The reflectivity of a vortex itself (mechanism A) is comparable to that of the oval (mechanism C) but cuts-off at frequencies lower than those considered in all the experiments to date. The RCS of a vortex happens to peak at the frequency (about 49 MHz) where atmospheric radars (known as ST radars) operate and so the present prediction could be verified in the future. Finally , we suggest that hot engine exhaust could increase RCE by 40 db and reveal vortex circulation, provided its mixing with the surroundings is prevented in the laminarising flow of the vortices.

Shariff, Karim; Wray, Alan; Yan, Jerry (Technical Monitor)

2000-01-01

212

[Fast neutron cross section measurements]. Progress report  

SciTech Connect

From its inception, the Nuclear Data Project at the University of Michigan has concentrated on two major objectives: (1) to carry out carefully controlled nuclear measurements of the highest possible reliability in support of the national nuclear data program, and (2) to provide an educational opportunity for students with interests in experimental nuclear science. The project has undergone a successful transition from a primary dependence on our photoneutron laboratory to one in which our current research is entirely based on a unique pulsed 14 MeV fast neutron facility. The new experimental facility is unique in its ability to provide nanosecond bursts of 14 MeV neutrons under conditions that are ``clean`` and as scatter-free as possible, and is the only one of its type currently in operation in the United States. It has been designed and put into operation primarily by graduate students, and has met or exceeded all of its important initial performance goals. We have reached the point of its routine operation, and most of the data are now in hand that will serve as the basis for the first two doctoral dissertations to be written by participating graduate students. Our initial results on double differential neutron cross sections will be presented at the May 1993 Fusion Reactor Technology Workshop. We are pleased to report that, after investing several years in equipment assembly and optimization, the project has now entered its ``data production`` phase.

Knoll, G.F.

1992-10-26

213

Cross-Sectional Properties of Coronal Loops  

NASA Astrophysics Data System (ADS)

In this work we assess if coronal loop cross sections observed in EUV images are symmetrical or asymmetrical in nature. To do this, we identified individual loop structures observed in EUV images taken with the EUVI instruments on the STEREO satellites. To image loops from two unique angles, we chose loops clearly discernible in both EUVI imagers during the period when the satellites were separated by approximately 90 degrees, allowing us to make observations of individual loops from two unique vantage points. Preference was given to loops which could be clearly identified in both satellites, especially those which were not crossed by other bright structures or loops, so reasonable background subtractions could be made. Once identified, the images were co-aligned and straightened, using a spline routine, for comparison. In total we identified 11 clearly discernible loops and derived the standard deviation and widths for both perspectives of the loop. It was found that within instrumental errors the loops can be considered circular in nature.

West, Matthew; Zhukov, Andrei; Klimchuk, James

214

Abdominal sarcoidosis: cross-sectional imaging findings.  

PubMed

Sarcoidosis is a multisystem inflammatory disease of unknown etiology. The lungs and the lymphoid system are the most commonly involved organs. Extrapulmonary involvement is reported in 30% of patients, and the abdomen is the most common extrapulmonary site with a frequency of 50%-70%. Although intra-abdominal sarcoidosis is usually asymptomatic, its presence may affect the prognosis and treatment options. The lesions are less characteristic and may mimick neoplastic or infectious diseases such as lymphoma, diffuse metastasis, and granulomatous inflammation. The liver and spleen are the most common abdominal sites of involvement. Sarcoidosis of the gastrointestinal system, pancreas, and kidneys are extremely rare. Adenopathy which is most commonly found in the porta hepatis, exudative ascites, and multiple granulomatous nodules studding the peritoneum are the reported manifestations of abdominal sarcoidosis. Since abdominal sarcoidosis is less common and long-standing, unrecognized disease can result in significant morbidity and mortality. Imaging contributes to diagnosis and management of intra-abdominal sarcoidosis. In this report we reviewed the cross-sectional imaging findings of hepatobiliary, gastrointestinal, and genitourinary sarcoidosis. PMID:25512071

Gezer, Naciye Sinem; Ba?ara, I??l; Altay, Canan; Harman, Mustafa; Rocher, Laurence; Karabulut, Nevzat; Seçil, Mustafa

2015-01-01

215

Inclusive two jet triply differential cross section  

SciTech Connect

We study the inclusive two jet triply differential cross section {ital d}{sup 3}{sigma}/{ital dE}{sub {ital T}}{ital d}{eta}{sub 1}{ital d}{eta}{sub 2} at Fermilab energies. Different {eta}{sub 1} and {eta}{sub 2} pseudorapidity regions are directly related to both the parton level matrix elements and the parton densities at leading order. We present the next-to-leading order [{ital O}({alpha}{sub {ital s}}{sup 3})] corrections and show that the shape of the distribution at fixed transverse energy {ital E}{sub {ital T}} is a particularly powerful tool for constraining the parton distributions at small to moderate {ital x} values. We investigate the renormalization and/or factorization scale uncertainty present in the normalization and shape of the distribution at next-to-leading order. We discuss specific slices of the distribution, the same-side/opposite-side ratio, and the signed pseudorapidity distribution in detail and compare them with preliminary experimental data.

Giele, W.T. [Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, Illinois 60510 (United States)] [Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, Illinois 60510 (United States); Glover, E.W.N. [Physics Department, University of Durham, Durham DH1 3LE (United Kingdom)] [Physics Department, University of Durham, Durham DH1 3LE (United Kingdom); Kosower, D.A. [Service de Physique Theorique, Centre d`Etudes de Saclay, F-91191 Gif-sur-Yvette cedex (France)] [Service de Physique Theorique, Centre d`Etudes de Saclay, F-91191 Gif-sur-Yvette cedex (France)

1995-08-01

216

Electron collisions with CO: Elastic and vibrational excitation cross sections  

SciTech Connect

Absolute differential elastic and vibrational excitation cross sections up to v=11 were measured for CO in scattering angle ranges extending to 180 deg. at energies between 0.2 and 5 eV (and an elastic measurement at 10 eV). The lowest angles were 0 deg. for inelastic scattering and between 5 deg. and 20 deg. for elastic scattering, depending on energy. Integral cross sections were derived by integrating under the angular distributions and compared with previous beam and swarm measurements. The sum of the integral cross sections agrees very well with the available transmission measurements of the grand total cross section, thus validating the present measurements. The present elastic differential and integral cross sections are in excellent agreement with the best available measurement [Gibson et al., J. Phys. B 29, 3197 (1996)], but the v=1 inelastic cross section is about 25% higher. This could have consequences for simulations of cometary and planetary atmospheres.

Allan, M. [Department of Chemistry, University of Fribourg, chemin du Musee 9, CH-1700 Fribourg (Switzerland)

2010-04-15

217

Electron ionization cross sections for the PH3 molecule  

NASA Astrophysics Data System (ADS)

The partial single, double differential cross-sections with their total (sum of partial cross sections) of the phosphine (PH3) by direct and dissociative electron ionization have been evaluated by using modified Jain-Khare semi-empirical approach. To the best of my knowledge, no other data (experimental and/or theoretical) of differential cross sections is available till now for comparison. Partial and total integral ionization cross sections were also evaluated for PH3. Integral ionization cross-sections show good agreement with available experimental/or theoretical data. Ionization rate coefficients corresponding to partial ionization cross-sections have also been calculated by the Maxwell-Boltzmann distribution of energy.

Kumar, Rajeev

2014-08-01

218

Experimental verification of theoretical cross sections for FIB PIXE  

NASA Astrophysics Data System (ADS)

X-ray production cross sections were found for films of Cr, Cu, Ge, Ag, W and Au, using incident H + and Be + ions at energies from 300 keV to 3.5 MeV. These experimental cross section results were compared with the cross section results obtained using software which calculates inner shell ionization and X-ray production cross sections. The software uses the ECPSSR-UA approach to finding X-ray production cross sections. This program was found to be useful for predicting cross sections for H + and Be + ions at the energies in this study. The software was then used to predict results for Li +, Be + and B + ions at 280 keV, energies available in the Arizona State University focused ion beam laboratory.

Streib, Kenneth L.; Alford, Terry L.; Mayer, James W.

2006-08-01

219

Partial Photoneutron Cross Sections for 207,208Pb  

NASA Astrophysics Data System (ADS)

Using linearly-polarized laser-Compton scattering ?-rays, partial E1 and M1 photoneutron cross sections along with total cross sections were determined for 207,208Pb at four energies near neutron threshold by measuring anisotropies in photoneutron emission. Separately, total photoneutron cross sections were measured for 207,208Pb with a high-efficiency 4? neutron detector. The partial cross section measurement provides direct evidence for the presence of pygmy dipole resonance (PDR) in 207,208Pb in the vicinity of neutron threshold. The strength of PDR amounts to 0.32%-0.42% of the Thomas-Reiche-Kuhn sum rule. Several ?N2 units of B(M1)? strength were observed in 207,208Pb just above neutron threshold, which correspond to M1 cross sections less than 10% of the total photoneutron cross sections.

Kondo, T.; Utsunomiya, H.; Goriely, S.; Iwamoto, C.; Akimune, H.; Yamagata, T.; Toyokawa, H.; Harada, H.; Kitatani, F.; Lui, Y.-W.; Hilaire, S.; Koning, A. J.

2014-05-01

220

Total and partial photoneutron cross sections for Pb isotopes  

NASA Astrophysics Data System (ADS)

Using quasimonochromatic laser-Compton scattering ? rays, total photoneutron cross sections were measured for 206,207,208Pb near neutron threshold with a high-efficiency 4? neutron detector. Partial E1 and M1 photoneutron cross sections along with total cross sections were determined for 207,208Pb at four energies near threshold by measuring anisotropies in photoneutron emission with linearly polarized ? rays. The E1 strength dominates over the M1 strength in the neutron channel where E1 photoneutron cross sections show extra strength of the pygmy dipole resonance in 207,208Pb near the neutron threshold corresponding to 0.32%-0.42% of the Thomas-Reiche-Kuhn sum rule. Several ?N2 units of B(M1)? strength were observed in 207,208Pb just above neutron threshold, which correspond to an M1 cross section less than 10% of the total photoneutron cross section.

Kondo, T.; Utsunomiya, H.; Goriely, S.; Daoutidis, I.; Iwamoto, C.; Akimune, H.; Okamoto, A.; Yamagata, T.; Kamata, M.; Itoh, O.; Toyokawa, H.; Lui, Y.-W.; Harada, H.; Kitatani, F.; Hilaire, S.; Koning, A. J.

2012-07-01

221

Determining the Uncertainty on the Total Heavy Flavor Cross Section  

SciTech Connect

We assess the theoretical uncertainties on the total heavy quark cross section. We discuss the importance of the quark mass, the scale choice, the number of light flavors and the parton densities on the estimate of the uncertainty. At first glance, the uncertainty bands on the total charm cross sections obtained by integrating the FONLL inclusive cross section and by integrating the partonic total cross sections appear to be incompatible. We explain how this apparent difference arises and describe how the two results can be reconciled. The small charm quark mass amplifies the effect of varying the other parameters in the calculation, making the uncertainty on the total charm cross section difficult to quantify. On the other hand, the bottom quark total cross section is under much better theoretical control and differences between the two approaches are small.

Vogt, R

2008-07-22

222

High E{sub T} jet cross sections at CDF  

SciTech Connect

The inclusive jet cross section for {ital p}{ital {anti p}} collisions at {radical}s = 1.8 TeV as measured by the CDF collaboration will be presented. Preliminary CDF measurements of the {Sigma} E{sub T} cross section at {radical}s = 1.8 TeV and the central inclusive jet cross section at {radical}s = 0.630 TeV will also be shown.

Flaugher, B.; CDF Collaboration

1996-08-01

223

Projectile and Lab Frame Differential Cross Sections for Electromagnetic Dissociation  

NASA Technical Reports Server (NTRS)

Differential cross sections for electromagnetic dissociation in nuclear collisions are calculated for the first time. In order to be useful for three - dimensional transport codes, these cross sections have been calculated in both the projectile and lab frames. The formulas for these cross sections are such that they can be immediately used in space radiation transport codes. Only a limited amount of data exists, but the comparison between theory and experiment is good.

Norbury, John W.; Adamczyk, Anne; Dick, Frank

2008-01-01

224

The total cross section for electron scattering by atomic hydrogen  

Microsoft Academic Search

An accurate total cross section for electron scattering by H(1s) in the intermediate energy regime of 1.0-3.7 Ryd is constructed by the addition of the best cross sections for elastic scattering, bound-state excitation, and ionization that are currently available. The theoretical cross sections arising from intermediate energy R-matrix (IERM) calculations are used for elastic scattering and n = 2 excitation.

T. T. Scholz; H. R. J. Walters; P. G. Burke

1990-01-01

225

Total cross sections for electron scattering by He  

Microsoft Academic Search

A set of total cross sections for scattering of electrons by He has been evaluated over the energy range of zero to 3000 eV by means of the analysis of experiments and theories on total cross sections for elastic scattering, ionisation and excitation, and on differential cross sections for elastic and inelastic scattering. Between 0 and 19.8 eV, where no

F. J. de Heer; R. H. J. Jansen

1977-01-01

226

Cross-sections for electron impact ionization of O2  

NASA Technical Reports Server (NTRS)

Using a crossed electron beam-molecular beam collision geometry and the relative flow technique measurements have been made to generate a uniform set of electron impact ionization cross-section data for O2 for electron impact energies from threshold to 1000 eV. Present values of total, partial and dissociative ionization cross-sections are compared with previously published data. Cross-sections for the formation of O2(+) from O2 have been measured for the first time.

Krishnakumar, E.; Srivastava, S. K.

1992-01-01

227

Cross sections for the dissociative attachment of electrons to NO  

NASA Technical Reports Server (NTRS)

Cross sections for the production of O(-) by electron attachment to NO are reported. It is found that the maximum value of the cross section is about 52 percent higher than the measurement of Rapp and Briglia (1965). Cross sections for the process of polar dissociation, e + NO yields N(+) + O(_), have also been measured, and the threshold energy for this process has been obtained.

Krishnakumar, E.; Srivastava, S. K.

1988-01-01

228

Nonlinear acoustic waves in channels with variable cross sections  

E-print Network

The point symmetry group is studied for the generalized Webster-type equation describing non-linear acoustic waves in lossy channels with variable cross sections. It is shown that, for certain types of cross section profiles, the admitted symmetry group is extended and the invariant solutions corresponding to these profiles are obtained. Approximate analytic solutions to the generalized Webster equation are derived for channels with smoothly varying cross sections and arbitrary initial conditions.

Vladimir F. Kovalev; Oleg V. Rudenko

2012-11-02

229

Drell-Yan Cross Section in the Jet Calculus Scheme  

E-print Network

We calculate factorized cross sections for lepton pair production mediated by a virtual photon in hadron-hadron collisions using the jet calculus scheme, in which a kinematical constraint due to parton radiation is taken into account. This method guarantees a proper phase space boundary for subtraction terms. Some properties of the calculated cross sections are examined. We also discuss matching between the hard scattering cross sections and parton showers at the next-to-leading logarithmic (NLL) order of quantum chromodynamics (QCD).

Hidekazu Tanaka; Hirokazu Kobayashi

2009-05-02

230

Next-to-leading order cross sections for tagged reactions  

NASA Astrophysics Data System (ADS)

We extend the phase space slicing method of Giele, Glover and Kosower for performing next-to-leading order jet cross section calculations in two important ways: we show how to include fragmentation functions and how to include massive particles. These extensions allow the application of this method not just to jet cross sections but also to cross sections in which a particular final state particle, including a D or B meson, is tagged.

Keller, Stéphane; Laenen, Eric

1999-06-01

231

Neutron-capture Cross Sections from Indirect Measurements  

SciTech Connect

Cross sections for compound-nuclear reactions play an important role in models of astrophysical environments and simulations of the nuclear fuel cycle. Providing reliable cross section data remains a formidable task, and direct measurements have to be complemented by theoretical predictions and indirect methods. The surrogate nuclear reactions method provides an indirect approach for determining cross sections for reactions on unstable isotopes, which are difficult or impossible to measure otherwise. Current implementations of the method provide useful cross sections for (n,f) reactions, but need to be improved upon for applications to capture reactions.

Escher, J E; Burke, J T; Dietrich, F S; Ressler, J J; Scielzo, N D; Thompson, I J

2011-10-18

232

New Geant4 cross section models for PIXE simulation  

NASA Astrophysics Data System (ADS)

We have implemented in the Geant4 simulation toolkit a set of new ionisation cross sections for the simulation of particle induced X-ray emission (PIXE), based upon theoretical and semi-empirical models. The set provides a model based on the so-called ECPSSR theory for the computation of K-shell ionisation cross sections for proton and alpha particle impact. A second model is based upon semi-empirical expressions proposed by Orlic for the calculation of L i-subshells ionisation cross sections for proton impact. Our developments are compared to ionisation cross sections already existing in the Geant4 toolkit and to experimental data.

Ben Abdelouahed, H.; Incerti, S.; Mantero, A.

2009-01-01

233

Positive Scattering Cross Sections using Constrained Least Squares  

SciTech Connect

A method which creates a positive Legendre expansion from truncated Legendre cross section libraries is presented. The cross section moments of order two and greater are modified by a constrained least squares algorithm, subject to the constraints that the zeroth and first moments remain constant, and that the standard discrete ordinate scattering matrix is positive. A method using the maximum entropy representation of the cross section which reduces the error of these modified moments is also presented. These methods are implemented in PARTISN, and numerical results from a transport calculation using highly anisotropic scattering cross sections with the exponential discontinuous spatial scheme is presented.

Dahl, J.A.; Ganapol, B.D.; Morel, J.E.

1999-09-27

234

X-ray incoherent scattering total cross sections and energy-absorption cross sections by means of simple calculation routines  

Microsoft Academic Search

Simple but accurate expressions for the total cross sections and energy-absorption cross sections for inelastic scattering of x rays from atomic, molecular, and condensed matter are developed. The starting point is the relativistic impulse approximation for Compton scattering of x rays. This gives the inelastic-scattering cross-section differential with respect to energy and solid-angle interval. Integration over energy of this expression

R. Ribberfors

1983-01-01

235

A database of 660 peptide ion cross sections: Use of intrinsic size parameters for bona fide predictions of cross sections  

Microsoft Academic Search

An ion trap\\/ion mobility\\/time-of-flight mass spectrometry technique has been used to measure collision cross sections for\\u000a 660 peptide ions generated by tryptic digestion of 34 common proteins. Measured cross sections have been compiled into a database\\u000a that contains peptide molecular weight and sequence information. The database is used to generate average intrinsic contributions\\u000a to cross section (size parameters) for different

Stephen J. Valentine; Anne E. Counterman; David E. Clemmer

1999-01-01

236

Cross Sections for Inner-Shell Ionization by Electron Impact  

SciTech Connect

An analysis is presented of measured and calculated cross sections for inner-shell ionization by electron impact. We describe the essentials of classical and semiclassical models and of quantum approximations for computing ionization cross sections. The emphasis is on the recent formulation of the distorted-wave Born approximation by Bote and Salvat [Phys. Rev. A 77, 042701 (2008)] that has been used to generate an extensive database of cross sections for the ionization of the K shell and the L and M subshells of all elements from hydrogen to einsteinium (Z = 1 to Z = 99) by electrons and positrons with kinetic energies up to 1 GeV. We describe a systematic method for evaluating cross sections for emission of x rays and Auger electrons based on atomic transition probabilities from the Evaluated Atomic Data Library of Perkins et al. [Lawrence Livermore National Laboratory, UCRL-ID-50400, 1991]. We made an extensive comparison of measured K-shell, L-subshell, and M-subshell ionization cross sections and of L? x-ray production cross sections with the corresponding calculated cross sections. We identified elements for which there were at least three (for K shells) or two (for L and M subshells) mutually consistent sets of cross-section measurements and for which the cross sections varied with energy as expected by theory. The overall average root-mean-square deviation between the measured and calculated cross sections was 10.9% and the overall average deviation was ?2.5%. This degree of agreement between measured and calculated ionization and x-ray production cross sections was considered to be very satisfactory given the difficulties of these measurements.

Llovet, Xavier, E-mail: xavier@ccit.ub.edu [Centres Científics i Tecnològics, Universitat de Barcelona, Lluís Solé i Sabarís 1-3, 08028 Barcelona (Spain)] [Centres Científics i Tecnològics, Universitat de Barcelona, Lluís Solé i Sabarís 1-3, 08028 Barcelona (Spain); Powell, Cedric J. [Materials Measurement Science Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8370 (United States)] [Materials Measurement Science Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8370 (United States); Salvat, Francesc [Facultat de Física (ECM and ICC), Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain)] [Facultat de Física (ECM and ICC), Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain); Jablonski, Aleksander [Institute of Physical Chemistry, Polish Academy of Sciences, ul. Kasprzaka 44/52, 01-224 Warsaw (Poland)] [Institute of Physical Chemistry, Polish Academy of Sciences, ul. Kasprzaka 44/52, 01-224 Warsaw (Poland)

2014-03-15

237

Total cross sections for positrons scattered elastically from helium based on new measurements of total ionization cross sections  

NASA Technical Reports Server (NTRS)

An improved technique is presented for employing the 2.3m spectrometer to measure total ionization cross sections, Q sub ion, for positrons incident on He. The new ionization cross section agree with the values reported earlier. Estimates are also presented of total elastic scattering cross section, Q sub el, obtained by subtracting from total scattering cross sections, Q sub tot, reported in the literature, the Q sub ion and Q sub Ps (total positronium formation cross sections) and total excitation cross sections, Q sub ex, published by another researcher. The Q sub ion and Q sub el measured with the 3m high resolution time-of-flight spectrometer for 54.9eV positrons are in accord with the results from the 2.3m spectrometer. The ionization cross sections are in fair agreement with theory tending for the most part to be higher, especially at 76.3 and 88.5eV. The elastic cross section agree quite well with theory to the vicinity of 50eV, but at 60eV and above the experimental elastic cross sections climb to and remain at about 0.30 pi a sub o sq while the theoretical values steadily decrease.

Diana, L. M.; Chaplin, R. L.; Brooks, D. L.; Adams, J. T.; Reyna, L. K.

1990-01-01

238

Accuracy of the O(+)-O collision cross-section deduced from ionosphere-thermosphere observations  

NASA Technical Reports Server (NTRS)

Aeronomic observations applied to the empirical derivation of the ion-neutral collision cross-section -- a basic parameter governing the mutual interaction between the neutral and plasma components in the Earth's upper atmosphere -- have given values considerably larger than those derived from theory. The empirical scheme uses the plasma velocities obtained with the Incoherent Scatter Radar and the neutral winds obtained with the Fabry-Perot Interferometer. It is shown here that such an analysis overestimates the collision cross-section due to the effects of errors in the observables. The effect may be sufficiently large to bring about agreement with theory, and calls for a re-analysis of the aeronomic data using methods which minimize the bias caused by measurement errors.

Reddy, C. A.; Hoegy, W. R.; Pesnell, W. D.; Mayr, H. G.; Hines, C. O.

1994-01-01

239

Learning of Cross-Sectional Anatomy Using Clay Models  

ERIC Educational Resources Information Center

We incorporated clay modeling into gross anatomy and neuro-anatomy courses to help students understand cross-sectional anatomy. By making clay models, cutting them and comparing cut surfaces to CT and MR images, students learned how cross-sectional two-dimensional images were created from three-dimensional structure of human organs. Most students…

Oh, Chang-Seok; Kim, Ji-Young; Choe, Yeon Hyeon

2009-01-01

240

Cross Sections for Electron Collisions with Carbon Monoxide  

NASA Astrophysics Data System (ADS)

Cross section data are collected and reviewed for electron collisions with carbon monoxide. Collision processes included are total scattering, elastic scattering, momentum transfer, excitations of rotational, vibrational and electronic states, ionization, and dissociation. For each process, recommended values of the cross sections are presented, when possible. The literature has been surveyed through to the end of 2013.

Itikawa, Yukikazu

2015-03-01

241

Random Phase Approximation and neutrino-nucleus cross sections  

E-print Network

The Random Phase Approximation theory is used to calculate the total cross sections of electron neutrinos on $^{12}$C nucleus. The role of the excitation of the discrete spectrum is discussed. A comparison with electron scattering and muon capture data is presented. The cross section of electron neutrinos coming from muon decay at rest is calculated.

Giampaolo Co'

2006-05-22

242

Temperature dependence of the HNO3 UV absorption cross sections  

NASA Technical Reports Server (NTRS)

The temperature dependence of the HNO3 absorption cross sections between 240 and 360 K over the wavelength range 195 to 350 nm has been measured using a diode array spectrometer. Absorption cross sections were determined using both (1) absolute pressure measurements at 298 K and (2) a dual absorption cell arrangement in which the absorption spectrum at various temperatures is measured relative to the room temperature absorption spectrum. The HNO3 absorption spectrum showed a temperature dependence which is weak at short wavelengths but stronger at longer wavelengths which are important for photolysis in the lower stratosphere. The 298 K absorption cross sections were found to be larger than the values currently recommended for atmospheric modeling (DeMore et al., 1992). Our absorption cross section data are critically compared with the previous measurements of both room temperature and temperature-dependent absorption cross sections. Temperature-dependent absorption cross sections of HNO3 are recommended for use in atmospheric modeling. These temperature dependent HNO3 absorption cross sections were used in a two-dimensional dynamical-photochemical model to demonstrate the effects of the revised absorption cross sections on loss rate of HNO3 and the abundance of NO2 in the stratosphere.

Burkholder, James B.; Talukdar, Ranajit K.; Ravishankara, A. R.; Solomon, Susan

1993-01-01

243

The two-jet cross section at high Q2  

NASA Astrophysics Data System (ADS)

We discuss the reliability of NLO QCD predictions for the two-jet cross section at high Q2. If the standard cone algorithm is used in the lab frame, the cross section is divergent. If instead the kicons/Journals/Common/perp" ALT="perp" ALIGN="MIDDLE"/> algorithm is used, the NLO corrections and scale dependence are small.

Pötter, B.; Seymour, M. H.

1999-07-01

244

A New Technique To Investigate Total Reaction Cross Sections  

NASA Astrophysics Data System (ADS)

We analyze the total reaction cross sections of several systems, especially weakly bound systems, by the use of a recently developed technique. We show a systematic behavior for the different systems, with larger reaction cross sections for systems with halo nuclei as projectiles.

Shorto, J. M. B.; Gomes, P. R. S.; Lubian, J.; Canto, L. F.; Chamon, L. C.

2010-08-01

245

Single Event Upset cross sections at various data rates  

Microsoft Academic Search

We present data which show that Single Event Upset (SEU) cross section varies linearly with frequency for most devices tested. We show that the SEU cross section can increase dramatically away from a linear relationship when the test setup is not optimized, or when testing near the maximum operating frequency. We also observe non-linear behavior in some complex circuit topologies.

R. A. Reed; M. A. Carts; P. W. Marshall; C. J. Marshall; S. Buchner; M. La Macchia; B. Mathes; D. McMorrow

1996-01-01

246

Analysis of cross sections using various nuclear potential  

SciTech Connect

The relevant astrophysical reaction rates which are derived from the reaction cross sections are necessary input to the reaction network. In this work, we analyse several theoretical models of the nuclear potential which give better prediction of the cross sections for some selected reactions.

Aziz, Azni Abdul [Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia); Kulliyah of Science, International Islamic University Malaysia, 25200 Kuantan (Malaysia); Quantum Science Center, Faculty of Science, University of Malaya, 50603 Kuala Lump (Malaysia); Kassim, Hasan Abu [Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia); Quantum Science Center, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Institute of Space Science, Universiti Kebangsaan Malaysia, 43600 Bangi, Se (Malaysia); Yusof, Norhasliza [Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia); Quantum Science Center, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Muhammad Zamrun, F. [Quantum Science Center, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Jurusan Fisika FMIPA, Universitas Haluoleo Kendari, Sulawesi Tenggara, J3232 (Indonesia)

2014-05-02

247

Electron impact ionization cross sections of phosphorus and arsenic molecules  

E-print Network

77 Electron impact ionization cross sections of phosphorus and arsenic molecules G. Monnom, Ph'ionisation dissociative obtenues par bombardement électronique des molécules d'arsenic As4 et As2 et de phosphore P4 et P2 ionization total cross sections of arsenic As4 and As2 molecules and phosphorus P4 and P2 molecules

Paris-Sud XI, Université de

248

A New Technique To Investigate Total Reaction Cross Sections  

SciTech Connect

We analyze the total reaction cross sections of several systems, especially weakly bound systems, by the use of a recently developed technique. We show a systematic behavior for the different systems, with larger reaction cross sections for systems with halo nuclei as projectiles.

Shorto, J. M. B.; Gomes, P. R. S.; Lubian, J. [Instituto de Fisica, Universidade Federal Fluminense, Av. Litoranea s/n, Niteroi, 24210-340 (Brazil); Canto, L. F. [Instituto de Fisica, Universidade Federal do Rio de Janeiro, CP 68528, Rio de Janeiro, 21941-972 (Brazil); Chamon, L. C. [Instituto de Fisica, Universidade de Sao Paulo, C.P. 66318, Sao Paulo, 05315-970 (Brazil)

2010-08-04

249

Absorption cross section and absorption coefficient of the ?-? annihilation  

Microsoft Academic Search

The two-photon annihilation (?-? annihilation) is an important absorption mechanism in the theory of radiative transfer of gamma ?-ray astronomy. The expression of the annihilation cross section given by QED theory in the frame of momentum center is changed into the laboratory reference frame by the use of the skill of relativistic transformation. The new expression of cross section is

J. J. Ling; D. B. Liu; L. Chen

2002-01-01

250

The cross sectional anatomy of ventricular septal defects: a reappraisal  

Microsoft Academic Search

The cross sectional echocardiographic description of holes in the ventricular septum has been unsatisfactory, chiefly because there are so many classifications of this defect. The accurate description of the anatomy of individual defects, from cross sectional images, is more important than attempts to fit them into a preconceived classification. One hundred specimens of hearts with a ventricular septal defect were

E J Baker; M P Leung; R H Anderson; D R Fischer; J R Zuberbuhler

1988-01-01

251

Date: June 11, 2004 Priority Cross-sections  

E-print Network

Date: June 11, 2004 Priority Cross-sections Joint Nordic Analyses of Important Cross significance for the Nordic elec- tricity market. The present report "Priority Cross-sections" concludes to a technical and socio-economic analysis. The analysis aims to understand the transports in the Nordel system

252

Emission Cross Sections for Neutral Xenon Impacted by Xe+  

E-print Network

Emission Cross Sections for Neutral Xenon Impacted by Xe+ and Xe2+ by Jason D. Sommerville A Thesis Emission cross sections for Neutral Xenon Impacted by Xe+ and Xe2+ by Jason D. Sommerville is hereby for eleven transitions from the 5p5 6p configuration to the 5p5 6s configuration of neutral xenon occur- ring

King, Lyon B.

253

Meteor head echo radar data: Mass-velocity selection effects  

NASA Astrophysics Data System (ADS)

High-power, large-aperture (HPLA) radars detect the plasma that forms in the vicinity of a meteoroid and moves approximately at its velocity; reflections from these plasmas are called head echoes. For over a decade, HPLA radars have been detecting head echoes with peak velocity distributions >50 km/s. These results have created some controversy within the field of meteor physics because previous data, including spacecraft impact cratering studies, optical and specular meteor data, indicate that the peak of the velocity distribution to a set limiting mass should be <20 km/s [Love, S.G., Brownlee, D.E., 1993. Science 262, 550-553]. Thus the question of whether HPLA radars are preferentially detecting high-velocity meteors arises. In this paper we attempt to address this question by examining both modeled and measured head echo data using the ALTAIR radar, collected during the Leonid 1998 and 1999 showers. These data comprise meteors originating primarily from the North Apex sporadic meteor source. First, we use our scattering theory to convert measured radar-cross-section (RCS) to electron line density and mass, as well as to convert modeled electron line density and mass to RCS. We subsequently compare the dependence between mass, velocity, mean-free-path, RCS and line density using both the measured and modeled data by performing a multiple, linear regression fit. We find a strong correlation between derived mass and velocity and show that line density is approximately proportional to mass times velocity3.1. Next, we determine the cumulative mass index using subsets of our data and use this mass index, along with the results of our regression fit, to weight the velocity distribution. Our results show that while there does indeed exist a bias in the measured head echo velocity distribution, it is smaller than those calculated using traditional specular trail data due to the different scattering mechanism, and also includes a bias against the low-mass, very high-velocity meteoroids.

Close, S.; Brown, P.; Campbell-Brown, M.; Oppenheim, M.; Colestock, P.

2007-02-01

254

Fission cross section measurements of actinides at LANSCE  

SciTech Connect

Fission cross sections of a range of actinides have been measured at the Los Alamos Neutron Science Center (LANSCE) in support of nuclear energy applications. By combining measurement at two LANSCE facilities, Lujan Center and the Weapons Neutron Research center (WNR), differential cross sections can be measured from sub-thermal energies up to 200 MeV. Incident neutron energies are determined using the time-of-flight method, and parallel-plate ionization chambers are used to measure fission cross sections relative to the {sup 235}U standard. Recent measurements include the {sup 233,238}U, {sup 239,242}Pu and {sup 243}Am neutron-induced fission cross sections. In this paper preliminary results for cross section data of {sup 243}Am and {sup 233}U will be presented.

Tovesson, Fredrik [Los Alamos National Laboratory; Laptev, Alexander B [Los Alamos National Laboratory; Hill, Tony S [INL

2010-01-01

255

Temperature-dependent absorption cross sections for hydrogen peroxide vapor  

NASA Technical Reports Server (NTRS)

Relative absorption cross sections for hydrogen peroxide vapor were measured over the temperature ranges 285-381 K for lambda = 230 nm-295 nm and 300-381 K for lambda = 193 nm-350 nm. The well established 298 K cross sections at 202.6 and 228.8 nm were used as an absolute calibration. A significant temperature dependence was observed at the important tropospheric photolysis wavelengths lambda over 300 nm. Measured cross sections were extrapolated to lower temperatures, using a simple model which attributes the observed temperature dependence to enhanced absorption by molecules possessing one quantum of O-O stretch vibrational excitation. Upper tropospheric photodissociation rates calculated using the extrapolated cross sections are about 25 percent lower than those calculated using currently recommended 298 K cross sections.

Nicovich, J. M.; Wine, P. H.

1988-01-01

256

Fission Cross Section Measurements of Actinides at LANSCE  

SciTech Connect

Fission cross sections of a range of actinides have been measured at the Los Alamos Neutron Science Center (LANSCE) in support of nuclear energy applications. By combining measurement at two LANSCE facilities, Lujan Center and the Weapons Neutron Research center (WNR), differential cross sections can be measured from sub-thermal energies up to 200 MeV. Incident neutron energies are determined using the time-of-flight method, and parallel-plate ionization chambers are used to measure fission cross sections relative to the 235U standard. Recent measurements include the 233, 238U, 239-242Pu, and 243Am neutron-induced fission cross sections. In this paper preliminary results for fission cross sections of 243Am and 233U will be presented.

F. Tovesson; A. B. Laptev; T. S. Hill

2011-08-01

257

Application of AWE Along with a Combined FEM/MoM Technique to Compute RCS of a Cavity-Backed Aperture in an Infinite Ground Plane Over a Frequency Range  

NASA Technical Reports Server (NTRS)

A hybrid Finite Element Method (FEM)/Method of Moments (MoM) technique in conjunction with the Asymptotic Waveform Evaluation (AWE) technique is applied to obtain radar cross section (RCS) of a cavity-backed aperture in an infinite ground plane over a frequency range. The hybrid FEM/MoM technique when applied to the cavity-backed aperture results in an integro-differential equation with electric field as the unknown variable, the electric field obtained from the solution of the integro-differential equation is expanded in Taylor series. The coefficients of the Taylor series are obtained using the frequency derivatives of the integro-differential equation formed by the hybrid FEM/MoM technique. The series is then matched via the Pade approximation to a rational polynomial, which can be used to extrapolate the electric field over a frequency range. The RCS of the cavity-backed aperture is calculated using the electric field at different frequencies. Numerical results for a rectangular cavity, a circular cavity, and a material filled cavity are presented over a frequency range. Good agreement between AWE and the exact solution over the frequency range is obtained.

Reddy, C.J.; Deshpande, M.D.

1997-01-01

258

Cross Section Sensitivity and Propagated Errors in HZE Exposures  

NASA Technical Reports Server (NTRS)

It has long been recognized that galactic cosmic rays are of such high energy that they tend to pass through available shielding materials resulting in exposure of astronauts and equipment within space vehicles and habitats. Any protection provided by shielding materials result not so much from stopping such particles but by changing their physical character in interaction with shielding material nuclei forming, hopefully, less dangerous species. Clearly, the fidelity of the nuclear cross-sections is essential to correct specification of shield design and sensitivity to cross-section error is important in guiding experimental validation of cross-section models and database. We examine the Boltzmann transport equation which is used to calculate dose equivalent during solar minimum, with units (cSv/yr), associated with various depths of shielding materials. The dose equivalent is a weighted sum of contributions from neutrons, protons, light ions, medium ions and heavy ions. We investigate the sensitivity of dose equivalent calculations due to errors in nuclear fragmentation cross-sections. We do this error analysis for all possible projectile-fragment combinations (14,365 such combinations) to estimate the sensitivity of the shielding calculations to errors in the nuclear fragmentation cross-sections. Numerical differentiation with respect to the cross-sections will be evaluated in a broad class of materials including polyethylene, aluminum and copper. We will identify the most important cross-sections for further experimental study and evaluate their impact on propagated errors in shielding estimates.

Heinbockel, John H.; Wilson, John W.; Blatnig, Steve R.; Qualls, Garry D.; Badavi, Francis F.; Cucinotta, Francis A.

2005-01-01

259

Electron impact rotationally elastic total cross section for formamide  

NASA Astrophysics Data System (ADS)

This paper reports computational results of the total cross sections for electron impact on formamide (HCONH2) over a wide range of energies from 0.01 eV to 5 keV. Total cross sections over such a wide range are reported for the first time as the earlier reported data is up to maximum of 12 eV. Below ionization threshold of the target, we performed ab initio calculations using UK molecular R-Matrix code within static, exchange plus polarization (SEP), and close coupling approximations. Twenty eight target states are included in close coupling formalism. Total 350 channels and 2410 configuration state functions are included in the calculations. We observe a ?* shape resonance at 3.41 eV and a ?* resonance at 15.3 eV as against similar resonances reported at 3.77 eV and 14.9 eV, respectively, by Goumans et al. [J. Chem. Theory Comput. 5, 217 (2009)] using SEP model. The cross sections at higher energies are evaluated using the spherical complex optical potential formalism. The two methods are found to be consistent with a smooth cross over at 18 eV. The vertical excitation energies, electronic excitation cross sections, differential cross sections, momentum transfer, and total cross sections are computed. In absence of experimental data, we compared our computed total cross sections with available other theoretical results.

Vinodkumar, Minaxi; Limbachiya, Chetan; Desai, Hardik; Vinodkumar, P. C.

2014-09-01

260

Thermal neutron capture cross sections of the palladium isotopes  

SciTech Connect

Precise thermal neutron capture {gamma}-ray cross sections {sigma}{sub {gamma}} were measured for all elements with Z=1-83,90, and 92, for He and Pm, at the Budapest Reactor. These data were evaluated with additional information from the literature to generate the Evaluated Gamma-ray Activation File (EGAF). Isotopic radiative neutron cross sections can be deduced from the total transition cross section feeding the ground state, {sigma}{sub 0}={sigma}{sigma}{sub {gamma}}(GS) if the decay scheme is complete. The EGAF file contains partial {gamma}-ray cross sections for all stable palladium isotopes. None of these decay schemes are complete, although in each case transitions de-exciting low-lying levels are known. We have performed Monte Carlo simulations of the palladium thermal neutron capture decay schemes using the computer code DICEBOX. The simulated populations of low low-lying levels are normalized to the measured {sigma}{sub {gamma}} values from EGAF and the total radiative neutron cross section {sigma}{sub 0} is obtained. The {sigma}{sub 0} values derived for the palladium isotopes agree well with previous measurements and were in several cases more precise. Complementary use of {gamma}-ray cross-section data and Monte Carlo calculations has proven effective in determining both the palladium total radiative cross sections and new nuclear structure information.

Krticka, M. [Charles University in Prague, Faculty of Mathematics and Physics, V Holesovickach 2, CZ-180 00 Prague 8 (Czech Republic); North Carolina State University, Raleigh, NC 27695 (United States); Firestone, R. B. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); McNabb, D. P.; Sleaford, B.; Agvaanluvsan, U. [Lawrence Livermore National Laboratory, L-414, 7000 East Avenue, Livermore, CA 94551 (United States); Belgya, T.; Revay, Z. S. [Institute of Isotope and Surface Chemistry, H-1525, Budapest (Hungary)

2008-05-15

261

Cross sections for electron scattering by atomic potassium  

SciTech Connect

Electron elastic and collisional excitation cross sections from the ground state of potassium are calculated using the noniterative integral-equation method of Henry, Rountree, and Smith (Comput. Phys. Commun. 23, 233 (1981)) in the electron energy range 4{le}{ital E}{le}200 eV. Configuration-interaction target wave functions that take account of correlation and polarization effects are used to represent the ground state and the six lowest excited states 4{ital p} {sup 2}{ital P}{degree}, 5{ital s} {sup 2}{ital S}, 3{ital d} {sup 2}{ital D}, 5{ital p} {sup 2}{ital P}{degree}, 4{ital d} {sup 2}{ital D}, and 6{ital s} {sup 2}{ital S}. Elastic and discrete excitation cross sections are obtained in a seven-state close-coupling (7CC) approximation. The 7CC elastic and excitation cross sections are compared and contrasted. Near threshold the elastic cross section dominates the resonance, 4{ital s} {sup 2}{ital S}{r arrow}4{ital p} {sup 2}{ital P}{degree}, and the sum of the other remaining excitation cross sections. Comparison of our total cross sections with some available experimental and theoretical data is also effected. The discrepancy between the recent measurement of the total cross section by Kwan {ital et} {ital al}. (Phys. Rev. A 44, 1620 (1991)) on the one hand and other measurements near threshold on the other hand is explained.

Msezane, A.Z.; Awuah, P.; Hiamang, S. (Department of Physics, Clark Atlanta University, Atlanta, Georgia 30314 (United States) Center for Theoretical Studies of Physical Systems, Clark Atlanta University, Atlanta, Georgia 30314 (United States)); Allotey, F.K.A. (University of Science and Technology, Kumasi (Ghana))

1992-12-01

262

Cross-Sectional Drawing Techniques And The Artist  

NASA Astrophysics Data System (ADS)

Although Democritus, a Greek pholosopher of the fifth century B.C. described the use of cross-sections in analyzing a solid form, this method was not extensively developed in art until the Renaissance. The earliest treatise documenting the integration of the cross-section and linear perspective is Piero della Francesca's De prospective pingendi (c. 1480), in which a drawing of the human head is mathematically conceived and plotted by means of cross-section contours. Piero's method anticipates contemporary biostereometric techniques and current theories of visual perception. Outside of theoretical treatises the complete cross-section rarely occurs in art, though certain pictorial elements such as the religious halo can be interpreted as cross-sections. The chan-ging representation of the halo in art of the Medieval, Renaissance and Baroque periods parallels the development of the artist's concepts and techniques for representing form and space. During the Renaissance and Baroque periods the widespread use of contour hatching, a drawing technique based on the cross-section, indicates that the cross-section concept has played a greater role in pictorial representation than has generally been recognized.

Berry, William A.

1980-07-01

263

Electron impact rotationally elastic total cross section for formamide  

SciTech Connect

This paper reports computational results of the total cross sections for electron impact on formamide (HCONH{sub 2}) over a wide range of energies from 0.01?eV to 5?keV. Total cross sections over such a wide range are reported for the first time as the earlier reported data is up to maximum of 12?eV. Below ionization threshold of the target, we performed ab initio calculations using UK molecular R-Matrix code within static, exchange plus polarization (SEP), and close coupling approximations. Twenty eight target states are included in close coupling formalism. Total 350 channels and 2410 configuration state functions are included in the calculations. We observe a ?* shape resonance at 3.41?eV and a ?* resonance at 15.3?eV as against similar resonances reported at 3.77?eV and 14.9?eV, respectively, by Goumans et al. [J. Chem. Theory Comput. 5, 217 (2009)] using SEP model. The cross sections at higher energies are evaluated using the spherical complex optical potential formalism. The two methods are found to be consistent with a smooth cross over at 18?eV. The vertical excitation energies, electronic excitation cross sections, differential cross sections, momentum transfer, and total cross sections are computed. In absence of experimental data, we compared our computed total cross sections with available other theoretical results.

Vinodkumar, Minaxi, E-mail: minaxivinod@yahoo.co.in [V P and R P T P Science College, Vallabh Vidyanagar 388120 (India); Limbachiya, Chetan, E-mail: chetanlimbachiya2@yahoo.com [Department of Applied Physics, The M.S. University of Baroda, Vadodara 390001 (India); Desai, Hardik, E-mail: hardikdesai.phy@gmail.com; Vinodkumar, P. C., E-mail: p.c.vinodkumar@gmail.com [Department of Physics, Sardar Patel University, Vallabh Vidyanagar 388120 (India)

2014-09-28

264

CSM RCS Design Considerations and Failure Modes  

NASA Technical Reports Server (NTRS)

Objectives include: a) Define major Command and Service Module (CSM) design considerations; b) List Command Module (CM) RCS failures and lessons learned; and c) List Service Module (SM) RCS failures and lessons learned.

Interbartolo, Michael

2009-01-01

265

Antimicrobial Peptides Activate the Rcs Regulon through the Outer Membrane Lipoprotein RcsF?  

PubMed Central

Salmonella enterica species are exposed to envelope stresses due to their environmental and infectious lifestyles. Such stresses include amphipathic cationic antimicrobial peptides (CAMPs), and resistance to these peptides is an important property for microbial virulence for animals. Bacterial mechanisms used to sense and respond to CAMP-induced envelope stress include the RcsFCDB phosphorelay, which contributes to survival from polymyxin B exposure. The Rcs phosphorelay includes two inner membrane (IM) proteins, RcsC and RcsD; the response regulator RcsB; the accessory coregulator RcsA; and an outer membrane bound lipoprotein, RcsF. Transcriptional activation of the Rcs regulon occurred within minutes of exposure to CAMP and during the first detectable signs of CAMP-induced membrane disorder. Rcs transcriptional activation by CAMPs required RcsF and preservation of its two internal disulfide linkages. The rerouting of RcsF to the inner membrane or its synthesis as an unanchored periplasmic protein resulted in constitutive activation of the Rcs regulon and RcsCD-dependent phosphorylation. These findings suggest that RcsFCDB activation in response to CAMP-induced membrane disorder is a result of a change in structure or availability of RcsF to the IM signaling constituents of the Rcs phosphorelay. PMID:20675476

Farris, Carol; Sanowar, Sarah; Bader, Martin W.; Pfuetzner, Richard; Miller, Samuel I.

2010-01-01

266

Cross sections for electron scattering from ?-tetrahydrofurfuryl alcohol  

NASA Astrophysics Data System (ADS)

We report on measurements of integral cross sections (ICSs) for electron impact excitation of a series of Rydberg electronic-states in ?-tetrahydrofurfuryl alcohol. The energy range of these experiments was 20-50 eV. There are currently no other results against which we can directly compare those measured data. We also report results from our independent atom model with screened additivity rule correction computations, namely for the total cross section, elastic ICS, inelastic ICS (all discrete electronic states and neutral dissociation) and the total ionisation ICS. Where possible, our calculated cross sections are compared to the limited available data of each scattering process.

Duque, H. V.; Chiari, L.; Jones, D. B.; Thorn, P. A.; Pettifer, Z.; da Silva, G. B.; Limão-Vieira, P.; Duflot, D.; Hubin-Franskin, M.-J.; Delwiche, J.; Blanco, F.; García, G.; Lopes, M. C. A.; Ratnavelu, K.; White, R. D.; Brunger, M. J.

2014-07-01

267

Aerodynamic Research on Fuselages with Rectangular Cross Section  

NASA Technical Reports Server (NTRS)

The influence of the deflected flow caused by the fuselage (especially by unsymmetrical attitudes) on the lift and the rolling moment due to sideslip has been discussed for infinitely long fuselages with circular and elliptical cross section. The aim of this work is to add rectangular cross sections and, primarily, to give a principle by which one can get practically usable contours through simple conformal mapping. In a few examples, the velocity field in the wing region and the induced flow produced are calculated and are compared with corresponding results from elliptical and strictly rectangular cross sections.

Maruhn, K.

1958-01-01

268

Comparison of fission and capture cross sections of minor actinides  

E-print Network

The fission and capture cross sections of minor actinides given in JENDL-3.3 are compared with other evaluated data and experimental data. The comparison was made for 32 nuclides of Th-227, 228, 229, 230, 233, 234, Pa-231, 232, 233, U-232, 234, 236, 237, Np-236, 237, 238, Pu-236, 237, 238, 242, 244, Am-241, 242, 242m, 243, Cm-242, 243, 244, 245, 246, 247 and 248. Given in the present report are figures of these cross sections and tables of cross sections at 0.0253 eV and resonance integrals.

Nakagawa, T

2003-01-01

269

Actinide Neutron-Induced Fission Cross Section Measurements At LANSCE  

NASA Astrophysics Data System (ADS)

Fission cross sections of a range of actinides have been measured at the Los Alamos Neutron Science Center (LANSCE) in support of nuclear energy applications in a wide energy range from sub thermal energies up to 200 MeV. Parallel-plate ionization chambers are used to measure fission cross sections ratios relative to the 235U standard while incident neutron energies are determined using the time-of-flight method. Recent measurements include the 233,238U, 239-242Pu and 243Am neutron-induced fission cross sections. Obtained data are presented in comparison with existing evaluations and previous data.

Tovesson, F.; Laptev, A. B.; Hill, T. S.

2011-06-01

270

Inclusive and pion production neutrino-nucleus cross sections  

NASA Astrophysics Data System (ADS)

We analyze the experimental data on the inclusive double-differential cross section by neutrinos charged current, measured by T2K, with the same model which was successful for the MiniBooNE quasielastic cross sections. As in our previous analysis the multinucleon component is needed in order to reproduce the data. For the total cross section, our evaluation is smaller than the SciBooNE data above 1 GeV. This indicates the opening of a new channel not included in our evaluation, presumably the two-pion-emission channel. We also check that our description holds for the exclusive single-pion-production channel by confronting our evaluation with the MiniBooNE double-differential cross section for a single charged pion and the Q2 distribution. Both are compatible with the data.

Martini, M.; Ericson, M.

2014-08-01

271

Measurement of Heavy Quark cross-sections at CDF  

SciTech Connect

Abstract: The measurement of heavy quark cross-sections provides important tests of the QCD theory. This paper reviews recent measurements of single b-quark and correlated b-quark cross-sections at CDF. Two new measurements of the single b-quark production at CDF agree with the first result from CDF Run II. This clarifies the experimental situation and confirms the recent agreement of theoretical prediction with data. A new measurement of the correlated b{bar b} cross-section with dimuon events at CDF is presented. It agrees with theory and it does not confirm the anomalously large b{bar b} cross-section seen in Run I by CDF and D0 in dimuon events.

Annovi, Alberto; /Frascati

2007-09-01

272

12. CLOSEUP VIEW OF CROSS SECTION OF SPILLWAY FIFTY FEET ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

12. CLOSE-UP VIEW OF CROSS SECTION OF SPILLWAY FIFTY FEET FROM LAKESHORE, SHOWING REMAINS OF SPILLWAY TIMBERS, LOOKING WEST - Three Bears Lake & Dams, North of Marias Pass, East Glacier Park, Glacier County, MT

273

Meson-exchange Currents and Quasielastic Neutrino Cross Sections  

E-print Network

We illustrate and discuss the role of meson-exchange currents in quasielastic neutrino-nucleus scattering induced by charged currents, comparing the results with the recent MiniBooNE data for differential and integrated cross sections.

M. B. Barbaro; J. E. Amaro; J. A. Caballero; T. W. Donnelly; J. M. Udias; C. F. Williamson

2011-10-21

274

4. DETAIL VIEW OF CROSS SECTION OF STRUCTURE, SHOWING EXTERIOR ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

4. DETAIL VIEW OF CROSS SECTION OF STRUCTURE, SHOWING EXTERIOR FACINGS LINED WITH RUBBLE BACKING AND EARTH INFILL, LOOKING EAST - Rock Wall, North side of Battle Creek Canyon, Shingletown, Shasta County, CA

275

Absolute cross sections for dissociative electron attachment to HCCCN  

NASA Astrophysics Data System (ADS)

New absolute cross sections for dissociative electron attachment to HCCCN (cyanoacetylene or propiolonitrile) in the range of 0–10 eV electron energy are presented here, which have been determined from a new analysis of previously reported data (Graupner et al 2006 New J. Phys. 8 117). The highest cross sections are observed for the formation of CN? at 5.3 eV and CCCN? at 5.1 eV; approximately 0.06 Å2 and 0.05 Å2 respectively. As part of the re-analysis, it was necessary to determine absolute cross sections for electron-impact ionization of HCCCN with the binary-encounter Bethe method. These electron-impact ionization absolute cross sections for HCCCN are also presented here; the maximum value was found to be ˜6.6 Å2 at ˜80 eV.

Gilmore, TD; Field, TA

2015-02-01

276

Precision measurement of the 238Pu(n,?) cross section  

NASA Astrophysics Data System (ADS)

The neutron-capture cross section for 238Pu was measured by using the detector for advanced neutron-capture experiments (DANCE) array, which is a highly segmented and highly efficient 4? ?-ray calorimeter. The neutron-capture events were recognized by the total ?-ray energy deposited in DANCE, which is equal to the reaction Q value plus the incident neutron energy. The absolute neutron-capture cross section was derived as a function of incident neutron energy from thermal to about 30 keV. The measured cross section for incident neutron energy below 18 eV was performed for the first time by using the direct method and does not support the most recently adopted changes in endf/b-vii.1 where the neutron-capture cross section was lowered by as much as a factor of ˜3 in the neighborhood of 0.3 eV from those evaluated in endf/b-vii.0.

Chyzh, A.; Wu, C. Y.; Kwan, E.; Henderson, R. A.; Gostic, J. M.; Bredeweg, T. A.; Couture, A.; Haight, R. C.; Lee, H. Y.; O'Donnell, J. M.; Ullmann, J. L.

2013-10-01

277

Giant dipole resonance parameters with uncertainties from photonuclear cross sections  

SciTech Connect

Updated values and corresponding uncertainties of isovector giant dipole resonance (IVGDR or GDR) model parameters are presented that are obtained by the least-squares fitting of theoretical photoabsorption cross sections to experimental data. The theoretical photoabsorption cross section is taken as a sum of the components corresponding to excitation of the GDR and quasideuteron contribution to the experimental photoabsorption cross section. The present compilation covers experimental data as of January 2010. - Highlights: {yields} Experimental {sigma} ({gamma}, abs) or a sum of partial cross sections are taken as input to the fitting. {yields} Data include contributions from photoproton reactions. {yields} Standard (SLO) or modified (SMLO) Lorentzian approaches are used for formulating GDR models. {yields} Spherical or axially deformed nuclear shapes are used in GDR least-squares fit. {yields} Values and uncertainties of the SLO and SMLO GDR model parameters are tabulated.

Plujko, V.A. [Taras Shevchenko National University, Kyiv (Ukraine); Institute for Nuclear Research, Kyiv (Ukraine); Capote, R., E-mail: R.CapoteNoy@iaea.org [NAPC-Nuclear Data Section, International Atomic Energy Agency, P.O. Box 100, A-1400,Vienna (Austria); Gorbachenko, O.M. [Taras Shevchenko National University, Kyiv (Ukraine)

2011-09-15

278

Black Hole Cross Section at the Large Hadron Collider  

E-print Network

Black hole production at the Large Hadron Collider (LHC) was first discussed in 1999. Since then, much work has been performed in predicting the black hole cross section. In light of the start up of the LHC, it is now timely to review the state of these calculations. We review the uncertainties in estimating the black hole cross section in higher dimensions. One would like to make this estimate as precise as possible since the predicted values, or lower limits, obtain for the fundamental Planck scale and number of extra dimensions from experiments will depend directly on the accuracy of the cross section. Based on the current knowledge of the cross section, we give a range of lower limits on the fundamental Planck scale that could be obtained at LHC energies.

Douglas M. Gingrich

2006-12-22

279

Hadronic cross sections, elastic slope and physical bounds  

SciTech Connect

An almost model-independent parametrization for the ratio of the total hadronic cross section to elastic slope is discussed. Its applicability in studies of asymptotia and analyses of extensive air shower in cosmic-ray physics is also outlined.

Fagundes, D. A.; Menon, M. J. [Instituto de Fisica Gleb Wataghin, Universidade Estadual de Campinas, UNICAMP, 13083-859 Campinas SP (Brazil)

2013-03-25

280

8. VIEW OF CROSS SECTION OF THE EASTERNMOST WALL SEGMENT ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

8. VIEW OF CROSS SECTION OF THE EASTERNMOST WALL SEGMENT THAT SHOWS THE TRENCHING AND 1960 PIPELINE CORRIDOR BETWEEN THE WALL SEGMENTS, LOOKING WEST-NORTHWEST - Rock Wall, North side of Battle Creek Canyon, Shingletown, Shasta County, CA

281

Absorption cross sections of the ClO dimer  

NASA Technical Reports Server (NTRS)

The absorption cross sections of the ClO dimer, ClOOCl, are important to the photochemistry of ozone depletion in the Antarctic. In this work, new measurements were made of the dimer cross sections at 195 K. the results yield somewhat lower values in the long wavelength region, compared to those currently recommended in the NASA data evaluation (JPL 94-26). The corresponding solar photodissociation rates in the Antarctic are reduced by about 40%.

Huder, K. J.; DeMore, W. B.

1995-01-01

282

Total cross sections for electron scattering by molecular hydrogen  

Microsoft Academic Search

Total cross sections for electron scattering by H2 are obtained for impact energies ranging from 25 to 750 eV. The method used is a linearisation of the Ramsauer-type experiment, which enables good angular and energy resolution; the accuracy obtained in the total cross sections is better than 4%. The authors compare their results with existing experimental data of other groups

B. van Wingerden; R. W. Wagenaar; F. J. de Heer

1980-01-01

283

Continuum effects in electron-helium total cross sections  

Microsoft Academic Search

It is shown that total cross sections for the excitation of target states with large spectroscopic factors may be calculated accurately by representing the states by their leading independent-particle configurations. With this approximation coupled-channels calculations agree only qualitatively with experimental total cross sections for the first five states of helium. R-matrix calculations using configuration interaction show better qualitative agreement. The

I. E. McCarthy; K. Ratnavelu; A. M. Weigold

1988-01-01

284

Total cross sections for positron and electron scattering from pyrimidine  

Microsoft Academic Search

In this paper we report original measurements of total cross sections for positron scattering from the important biomolecule pyrimidine. The energy range of these measurements was 0.3-45 eV, while the energy resolution was ~260 meV. In addition, we report theoretical results, calculated within the independent atom-screened additivity rule (IAM-SCAR) formalism, for the corresponding electron impact total cross sections. In that

A. Zecca; L. Chiari; G. García; F. Blanco; E. Trainotti; M. J. Brunger

2010-01-01

285

Inclusive jet differential cross sections in photoproduction at HERA  

Microsoft Academic Search

Inclusive jet differential cross sections for the reaction ep ? jet + X at Q2 below 4 GeV2 have been measured with the ZEUS detector at HERA using an integrated luminosity of 0.55 pb?1. These cross sections are given in the kinematic region 0.2 < y < 0.85, for jet pseudorapidities in the ep-laboratory range ?1 < ?jet < 2

S. Bhadra; W. R. Frisken; K. M. Furutani; B. Musgrave; J. Repond; J. Schlereth; R. Stanek; R. L. Talaga; J. Thron; F. Arzarello; R. Ayad; G. Bari; M. Basile; L. Bellagamba; D. Boscherini; A. Bruni; G. Bruni; P. Bruni; G. Cara Romeo; G. Castellini; M. Chiarini; L. Cifarelli; F. Cindolo; F. Ciralli; A. Contin; S. D'Auria; F. Frasconi; I. Gialas; P. Giusti; G. Iacobucci; G. Laurenti; G. Levi; A. Margotti; T. Massam; R. Nania; C. Nemoz; F. Palmonari; A. Polini; G. Sartorelli; R. Timellini; Y. Zamora Garcia; A. Zichichi; A. Bargende; J. Crittenden; K. Desch; B. Diekmann; T. Doeker; M. Eckart; L. Feld; A. Frey; M. Geerts; G. Geitz; M. Grothe; H. Hartmann; D. Haun; K. Heinloth; E. Hilger; H.-P. Jakob; U. F. Katz; S. M. Mari; A. Mass; S. Mengel; J. Mollen; E. Paul; Ch. Rembser; R. Schattevoy; J.-L. Schneider; D. Schramm; J. Stamm; R. Wedemeyer; S. Campbell-Robson; A. Cassidy; N. Dyce; B. Foster; S. George; R. Gilmore; G. P. Heath; H. F. Heath; T. J. Llewellyn; C. J. S. Morgado; D. J. P. Norman; J. A. O'Mara; R. J. Tapper; S. S. Wilson; R. Yoshida; R. R. Rau; M. Arneodo; L. Iannotti; M. Schioppa; G. Susinno; A. Bernstein; A. Caldwell; J. A. Parsons; S. Ritz; F. Sciulli; P. B. Straub; L. Wai; S. Yang; P. Borzemski; J. Chwastowski; A. Eskreys; K. Piotrzkowski; M. Zachara; L. Zawiejski; L. Adamczyk; B. Bednarek; K. Eskreys; K. Jelen; D. Kisielewska; T. Kowalski; E. Rulikowska-Zarebska; L. Suszycki; J. Zajac; T. Kedzierski; A. Kotanski; M. Przybycien; L. A. T. Bauerdick; U. Behrens; J. K. Bienlein; S. Böttcher; C. Coldewey; G. Drews; M. Flasinski; D. J. Gilkinson; P. Göttlicher; B. Gutjahr; T. Haas; W. Hain; D. Hasell; H. Heßling; H. Hultschig; Y. Iga; P. Joos; M. Kasemann; R. Klanner; W. Koch; L. Köpke; U. Kötz; H. Kowalski; W. Kröger; J. Krüger; J. Labs; A. Ladage; B. Löhr; M. Löwe; D. Lüke; O. Manczak; J. S. T. Ng; S. Nickel; D. Notz; K. Ohrenberg; M. Roco; M. Rohde; J. Roldán; U. Schneekloth; W. Schulz; F. Selonke; E. Stiliaris; T. Voß; D. Westphal; G. Wolf; C. Youngman; H. J. Grabosch; A. Leich; A. Meyer; C. Rethfeldt; S. Schlenstedt; G. Barbagli; P. Pelfer; G. Anzivino; G. Maccarrone; S. de Pasquale; S. Qian; L. Votano; A. Bamberger; A. Freidhof; T. Poser; S. Söldner-Rembold; J. Schroeder; G. Theisen; T. Trefzger; N. H. Brook; P. J. Bussey; A. T. Doyle; I. Fleck; V. A. Jamieson; D. H. Saxon; M. L. Utley; A. S. Wilson; A. Dannemann; U. Holm; D. Horstmann; H. Kammerlocher; B. Krebs; T. Neumann; R. Sinkus; K. Wick; E. Badura; B. D. Burow; A. Fürtjes; L. Hagge; E. Lohrmann; J. Mainusch; J. Milewski; M. Nakahata; N. Pavel; G. Poelz; W. Schott; J. Terron; F. Zetsche; T. C. Bacon; R. Beuselinck; I. Butterworth; E. Gallo; V. L. Harris; B. H. Hung; K. R. Long; D. B. Miller; P. P. O. Morawitz; A. Prinias; J. K. Sedgbeer; A. F. Whitfield; U. Mallik; E. McCliment; M. Z. Wang; S. M. Wang; J. T. Wu; Y. Zhang; P. Cloth; D. Filges; S. H. An; S. M. Hong; S. W. Nam; S. K. Park; M. H. Suh; S. H. Yon; R. Imlay; S. Kartik; H.-J. Kim; R. R. McNeil; W. Metcalf; V. K. Nadendla; F. Barreiro; G. Cases; R. Graciani; J. M. Hernández; L. Hervás; L. Labarga; J. del Peso; J. Puga; J. F. de Trocóniz; F. Ikraiam; J. K. Mayer; G. R. Smith; F. Corriveau; D. S. Hanna; J. Hartmann; L. W. Hung; J. N. Lim; C. G. Matthews; P. M. Patel; L. E. Sinclair; D. G. Stairs; M. St. Laurent; R. Ullmann; G. Zacek; V. Bashkirov; B. A. Dolgoshein; A. Stifutkin; G. L. Bashindzhagyan; P. F. Ermolov; L. K. Gladilin; Y. A. Golubkov; V. D. Kobrin; V. A. Kuzmin; A. S. Proskuryakov; A. A. Savin; L. M. Shcheglova; A. N. Solomin; N. P. Zotov; S. Bentvelsen; M. Botje; F. Chlebana; A. Dake; J. Engelen; P. de Jong; M. de Kamps; P. Kooijman; A. Kruse; V. O'dell; A. Tenner; H. Tiecke; W. Verkerke; M. Vreeswijk; L. Wiggers; E. de Wolf; R. van Woudenberg; D. Acosta; B. Bylsma; L. S. Durkin; K. Honscheid; C. Li; T. Y. Ling; K. W. McLean; W. N. Murray; I. H. Park; T. A. Romanowski; R. Seidlein; D. S. Bailey; G. A. Blair; A. Byrne; R. J. Cashmore; A. M. Cooper-Sarkar; D. Daniels; R. C. E. Devenish; N. Harnew; M. Lancaster; P. E. Luffman; L. Lindemann; J. McFall; C. Nath; A. Quadt; H. Uijterwaal; R. Walczak; F. F. Wilson; T. Yip; G. Abbiendi; A. Bertolin; R. Brugnera; R. Carlin; F. dal Corso; M. de Giorgi; U. Dosselli; S. Limentani; M. Morandin; M. Posocco; L. Stanco; R. Stroili; C. Voci; J. Bulmahn; J. M. Butterworth; R. G. Feild; B. Y. Oh; J. J. Whitmore; G. D'Agostini; M. Iori; G. Marini; M. Mattioli; A. Nigro; E. Tassi; J. C. Hart; N. A. McCubbin; K. Prytz; T. P. Shah; T. L. Short; E. Barberis; N. Cartiglia; T. Dubbs; C. Heusch; M. van Hook; B. Hubbard; W. Lockman; J. T. Rahn; H. F.-W. Sadrozinski; A. Seiden; J. Biltzinger; R. J. Seifert; A. H. Walenta; G. Zech; H. Abramowicz; G. Briskin; S. Dagan; A. Levy; T. Hasegawa; M. Hazumi; T. Ishii; M. Kuze; S. Mine; Y. Nagasawa; T. Nagira; M. Nakao; I. Suzuki; K. Tokushuku; S. Yamada

1995-01-01

286

The PhotoIonization Cross Section of Lithium  

Microsoft Academic Search

The photo-ionization cross section of lithium is calculated using Hartree-Fock wave functions. Good agreement is obtained between the dipole length and dipole velocity formulae for the cross section over the wavelength range considered, 2300 Å-1800 Å. The mean value at the spectral head is found to be 1.16 × 10-18 cm2, considerably smaller than either of the previous theoretical estimates

A L Stewart

1954-01-01

287

Photoabsorption Cross Section for Silicon Doped with Indium  

Microsoft Academic Search

The photo-ionization cross section for indium as an acceptor in a silicon lattice has been deduced from optical transmission coupled with wide-range Hall-effect measurements. The normalized energy dependence observed in our samples agrees well with results previously reported, but the cross section we report has a maximum value of sigma=3.3×10-17 cm2 at hnu=0.3 eV. This is several times smaller than

R. A. Messenger; J. S. Blakemore

1971-01-01

288

New Geant4 cross section models for PIXE simulation  

Microsoft Academic Search

We have implemented in the Geant4 simulation toolkit a set of new ionisation cross sections for the simulation of particle induced X-ray emission (PIXE), based upon theoretical and semi-empirical models. The set provides a model based on the so-called ECPSSR theory for the computation of K-shell ionisation cross sections for proton and alpha particle impact. A second model is based

H. Ben Abdelouahed; S. Incerti; A. Mantero

2009-01-01

289

Total cross section and elastic scattering from TEVATRON to LHC  

E-print Network

A review of measurements of the total cross section in ppbar collisions at the TEVATRON and an outlook on the expected performance for similar determinations at the LHC is given. The experimental method is based on the optical theorem to determine the total cross section independent of the machine luminosity. It consists of the extrapolation of the t-spectrum for elastic scattering to t-->0 with a simultaneous measurement of the total inelastic rate.

H. Stenzel

2009-07-17

290

Absolute Total np and pp Cross Section Determinations  

E-print Network

Absolute total cross sections for np and pp scattering below 1000 MeV are determined based on partial-wave analyses of NN scattering data. These cross sections are compared with most recent ENDF/B and JENDL data files, and the Nijmegen partial-wave analysis. Systematic deviations from the ENDF/B and JENDL evaluations are found to exist in the low-energy region.

R. A. Arndt; W. J. Briscoe; A. B. Laptev; I. I. Strakovsky; R. L. Workman

2009-01-05

291

Hadronic Cross sections: from cyclotrons to colliders to cosmic rays  

E-print Network

We present evidence for the saturation of the Froissart bound at high energy for {\\em all hadronic} total cross sections at high energies, and use this to unify $pp$ (and $\\bar p p$) total cross sections over the energy range from cyclotrons to colliders to ultra-high energy cosmic rays, an energy span from $\\sqrt s = 4$ GeV to 80 TeV.

Martin M. Block

2010-09-02

292

Electron-Impact Excitation Cross Sections for Metal Vapors  

NASA Astrophysics Data System (ADS)

Two simple scaling methods to generate integrated cross sections from plane-wave Born cross sections for dipole-allowed excitations of metal vapors by electron impact(Y.-K. Kim, Phys. Rev. A, 64), in print. are shown to produce cross sections comparable in accuracy to those obtained by more sophisticated collision theories, such as the convergent close-coupling method. The scaled cross sections ?_BE and ?f are: ?_BE=?_PW×[T/(T+B+E)], ?_f=?_PWsc×(f_mc/f_sc), where ?_PW=unscaled plane-wave Born cross section, T=incident electron energy, B=binding energy of the target electron, E=excitation energy, f_mc and f_sc are the dipole f-values calculated from multiconfiguration wave functions and single-configuration wave functions, respectively. The two scalings can be used consecutively. The scaled cross section for the 4s-4p excitation of Cu is in excellent agreement with the experiment by Ismail and Teubner.(M. Ismail and P. J. O. Teubner, J. Phys. B 28) 4149 (1995) Many examples of resonance transitions of atoms, including Ag, Au, and Hg, will be presented.

Kim, Yong-Ki

2001-10-01

293

Krypton charge exchange cross sections for Hall effect thruster models  

NASA Astrophysics Data System (ADS)

Following discharge from a Hall effect thruster, charge exchange occurs between ions and un-ionized propellant atoms. The low-energy cations produced can disturb operation of onboard instrumentation or the thruster itself. Charge-exchange cross sections for both singly and doubly charged propellant atoms are required to model these interactions. While xenon is the most common propellant currently used in Hall effect thrusters, other propellants are being considered, in particular, krypton. We present here guided-ion beam measurements and comparisons to semiclassical calculations for Kr+ + Kr and Kr2+ + Kr cross sections. The measurements of symmetric Kr+ + Kr charge exchange are in good agreement with both the calculations including spin-orbit effects and previous measurements. For the symmetric Kr2+ + Kr reaction, we present cross section measurements for center-of-mass energies between 1 eV and 300 eV, which spans energies not previously examined experimentally. These cross section measurements compare well with a simple one-electron transfer model. Finally, cross sections for the asymmetric Kr2+ + Kr ? Kr+ + Kr+ reaction show an onset near 12 eV, reaching cross sections near constant value of 1.6 Å2 with an exception near 70-80 eV.

Hause, Michael L.; Prince, Benjamin D.; Bemish, Raymond J.

2013-04-01

294

A genetic algorithm to reduce stream channel cross section data  

USGS Publications Warehouse

A genetic algorithm (GA) was used to reduce cross section data for a hypothetical example consisting of 41 data points and for 10 cross sections on the Kootenai River. The number of data points for the Kootenai River cross sections ranged from about 500 to more than 2,500. The GA was applied to reduce the number of data points to a manageable dataset because most models and other software require fewer than 100 data points for management, manipulation, and analysis. Results indicated that the program successfully reduced the data. Fitness values from the genetic algorithm were lower (better) than those in a previous study that used standard procedures of reducing the cross section data. On average, fitnesses were 29 percent lower, and several were about 50 percent lower. Results also showed that cross sections produced by the genetic algorithm were representative of the original section and that near-optimal results could be obtained in a single run, even for large problems. Other data also can be reduced in a method similar to that for cross section data.

Berenbrock, C.

2006-01-01

295

Krypton charge exchange cross sections for Hall effect thruster models  

SciTech Connect

Following discharge from a Hall effect thruster, charge exchange occurs between ions and un-ionized propellant atoms. The low-energy cations produced can disturb operation of onboard instrumentation or the thruster itself. Charge-exchange cross sections for both singly and doubly charged propellant atoms are required to model these interactions. While xenon is the most common propellant currently used in Hall effect thrusters, other propellants are being considered, in particular, krypton. We present here guided-ion beam measurements and comparisons to semiclassical calculations for Kr{sup +} + Kr and Kr{sup 2+} + Kr cross sections. The measurements of symmetric Kr{sup +} + Kr charge exchange are in good agreement with both the calculations including spin-orbit effects and previous measurements. For the symmetric Kr{sup 2+} + Kr reaction, we present cross section measurements for center-of-mass energies between 1 eV and 300 eV, which spans energies not previously examined experimentally. These cross section measurements compare well with a simple one-electron transfer model. Finally, cross sections for the asymmetric Kr{sup 2+} + Kr {yields} Kr{sup +} + Kr{sup +} reaction show an onset near 12 eV, reaching cross sections near constant value of 1.6 A{sup 2} with an exception near 70-80 eV.

Hause, Michael L. [Institute for Scientific Research, Boston College, Chestnut Hill, Massachusetts 02159 (United States); Prince, Benjamin D.; Bemish, Raymond J. [Air Force Research Laboratory, Space Vehicles Directorate, Kirtland AFB, New Mexico 87117 (United States)

2013-04-28

296

Joint strength in RCS frames  

E-print Network

As part of a National Science Foundation (NSF) program ics. on composite and hybrid systems at Texas A&M University, the objective of this thesis is to investigate the joint strength in reinforced column-steel beam (RCS) special moment frames...

Kirby, Cynthia Dawn

1998-01-01

297

Orbiter OMS and RCS technology  

NASA Technical Reports Server (NTRS)

Orbiter Orbital Maneuver Subsystem (OMS) and Reaction Control Subsystem (RCS) tankage has proved to be highly successful in shuttle flights on-orbit propellant transfer tests were done. Tank qualification tests along with flight demonstrations were carried out future uses of storable propellants are cited.

Boudreaux, R. A.

1982-01-01

298

Inclined Bodies of Various Cross Sections at Supersonic Speeds  

NASA Technical Reports Server (NTRS)

To aid in assessing effects of cross-sectional shape on body aerodynamics, the forces and moments have been measured for bodies with circular, elliptic, square, and triangular cross sections at Mach numbers 1.98 and 3.88. Results for bodies with noncircular cross sections have been compared with results for bodies of revolution having the same axial distribution of cross-sectional area (and, thus, the same equivalent fineness ratio). Comparisons have been made for bodies of fineness ratios 6 and 10 at angles of attack from 0 deg to about 20 deg and for Reynolds numbers, based on body length, of 4.0 x 10(exp 6) and 6.7 x 10(exp 6). The results of this investigation show that distinct aerodynamic advantages can be obtained by using bodies with noncircular cross sections. At certain angles of bank, bodies with elliptic, square, and triangular cross sections develop considerably greater lift and lift-drag ratios than equivalent bodies of revolution. For bodies with elliptic cross sections, lift and pitching-moment coefficients can be correlated with corresponding coefficients for equivalent circular bodies. It has been found that the ratios of lift and pitching-moment coefficients for an elliptic body to those for an equivalent circular body are practically constant with change in both angle of attack and Mach number. These lift and moment ratios are given very accurately by slender-body theory. As a result of this agreement, the method of NACA Rep. 1048 for computing forces and moments for bodies of revolution has been simply extended to bodies with elliptic cross sections. For the cases considered (elliptic bodies of fineness ratios 6 and 10 having cross-sectional axis ratios of 1.5 and 2), agreement of theory with experiment is very good. As a supplement to the force and moment results, visual studies of the flow over bodies have been made by use of the vapor-screen, sublimation, and white-lead techniques. Photographs from these studies are included in the report.

Jorgensen, Leland H.

1958-01-01

299

Modelling interaction cross sections for intermediate and low energy ions.  

PubMed

When charged particles slow in tissue they undergo electron capture and loss processes that can have profound effects on subsequent interaction cross sections. Although a large amount of data exists for the interaction of bare charged particles with atoms and molecules, few experiments have been reported for these 'dressed' particles. Projectile electrons contribute to an impact-parameter-dependent screening of the projectile charge that precludes straightforward scaling of energy loss cross sections from those of bare charged particles. The objective of this work is to develop an analytical model for the energy-loss-dependent effects of screening on differential ionisation cross sections that can be used in track structure calculations for high LET ions. As a first step a model of differential ionisation cross sections for bare ions has been combined with a simple screening model to explore cross sections for intermediate and low energy dressed ions in collisions with atomic and molecular gas targets. The model is described briefly and preliminary results compared to measured ejected electron energy spectra. PMID:12194359

Toburen, L H; Shinpaugh, J L; Justiniano, E L B

2002-01-01

300

Electromagnetic Dissociation Cross Sections using Weisskopf-Ewing Theory  

NASA Technical Reports Server (NTRS)

It is important that accurate estimates of crew exposure to radiation are obtained for future long-term space missions. Presently, several space radiation transport codes exist to predict the radiation environment, all of which take as input particle interaction cross sections that describe the nuclear interactions between the particles and the shielding material. The space radiation transport code HZETRN uses the nuclear fragmentation model NUCFRG2 to calculate Electromagnetic Dissociation (EMD) cross sections. Currently, NUCFRG2 employs energy independent branching ratios to calculate these cross sections. Using Weisskopf-Ewing (WE) theory to calculate branching ratios, however, is more advantageous than the method currently employed in NUCFRG2. The WE theory can calculate not only neutron and proton emission, as in the energy independent branching ratio formalism used in NUCFRG2, but also deuteron, triton, helion, and alpha particle emission. These particles can contribute significantly to total exposure estimates. In this work, photonuclear cross sections are calculated using WE theory and the energy independent branching ratios used in NUCFRG2 and then compared to experimental data. It is found that the WE theory gives comparable, but mainly better agreement with data than the energy independent branching ratio. Furthermore, EMD cross sections for single neutron, proton, and alpha particle removal are calculated using WE theory and an energy independent branching ratio used in NUCFRG2 and compared to experimental data.

Adamczyk, Anne M.; Norbury, John W.

2011-01-01

301

Role of channel and floodplain cross-section geometry in the basin response  

Microsoft Academic Search

Cross section geometry affects the relative contribution of dispersion mechanismNon-linearity in the response varies depending on the cross section geometryNetwork and hillslope effects on dispersion vary with cross section geometry

A. I. Mejia; S. M. Reed

2011-01-01

302

Analysis of Ku-band cross section at low incidence angles  

NASA Technical Reports Server (NTRS)

This study is using airborne Ku-band data to address questions which have implications for both model function development and for advancing our physical understanding of the sea surface. Concurrent measurements of ocean directional spectra, significant wave height, and mean surface roughness are made using the capabilities of the radar ocean wave spectrometer (ROWS). The NASA/GSFC's ROWS is a 15 GHz pulse compressed radar which is a radar sensor designed to measure the direction of the long wave components using spectral analysis of the tilt induced reflectively modulation. The ROWS are modified to cycle at 50 Hz for the scanning spectrometer antenna and a wide beamwidth nadir altimeter mode. This change allows the sensor to simultaneously measure directional wave spectra, wave height, mean square slope parameter, and small scale surface roughness. The surface stress caused by the wind is widely believed to be the predominant quantity related to the Ku-band radar cross section for a wide range of incidence angles. The complete coverage in the quasi specular region provided by one sensor is essential to understand the uncertainties between the scattering model and what is happening on the surface. For this presentation, special attention is devoted to sort out some measurement of the anisotropy associated with the band of high frequencies. Using the other geophysical parameters, comparisons are then made with the classic spectral form currentlyused to describe the wind impact on the sea surface.

Chapron, B.; Vandemark, D.

1993-01-01

303

Total electron scattering and electronic state excitations cross sections for O2, CO, and CH4  

NASA Technical Reports Server (NTRS)

Available electron collision cross section data concerning total and elastic scattering, vibrational excitation, and ionization for O2, CO, and CH4 have been critically reviewed, and a set of cross sections for modeling of planetary atmospheric behavior is recommended. Utilizing these recommended cross sections, we derived total electronic state excitation cross sections and upper limits for dissociation cross sections, which in the case of CH4 should very closely equal the actual dissociation cross section.

Kanik, I.; Trajmar, S.; Nickel, J. C.

1993-01-01

304

Measurement of the W + jet cross section at CDF  

SciTech Connect

A measurement of W {yields} ev + n-jet cross sections in p{bar p} collisions at {radical}s = 1.96 TeV using the Collider Detector at Fermilab in Run II is presented. The measurement is based on an integrated luminosity of 320 pb{sup -1}, and includes events with jet multiplicity from {ge} 1 to {ge} 4. In each jet multiplicity sample the differential and cumulative cross sections with respect to the transverse energy of the n{sup th}-leading jet are measured. For W + {ge} 2 jets the differential cross section with respect to the 2-leading jets invariant mass m{sub j{sub 1}j{sub 2}} and angular separation {Delta}R{sub j{sub 1}j{sub 2}} is also reported. The data are compared to predictions from Monte Carlo simulations.

Messina, Andrea; /Michigan State U.

2006-10-01

305

Inelastic cross sections for positron scattering from atomic hydrogen  

SciTech Connect

Positronium formation (Ps) cross sections for positrons impinging on atomic hydrogen were measured in the impact energy range from 13eV to 255eV at the High Intensity Positron (HIP) beam at Brookhaven National Laboratory (BNL). The Ps-formation cross section was found to rise rapidly from the threshold at 6.8eV to a maximum value of (2.98 {plus_minus} 0.18) {times} 10{sup {minus}16} cm{sup 2} for {approx} 15eV positrons. By 75eV it drops below the detection limit of 0.17 {times} 10{sup {minus}16} cm{sup 2} which is the present level of statistical uncertainty. The experiment was modified to enable the measurement of doubly differential scattering cross sections.

Weber, M.; Hofmann, A.; Raith, W.; Sperber, W. [Bielefeld Univ. (Germany). Fakultaet fuer Physik; Jacobsen, F.; Lynn, K.G. [Brookhaven National Lab., Upton, NY (United States)

1994-12-31

306

Recent positron-atom cross section measurements and calculations  

NASA Astrophysics Data System (ADS)

We review recent cross section results for low-energy positron scattering from atomic targets. A comparison of the latest measurements and calculations for positron collisions with the noble gases and a brief update of the newest studies on other atoms is presented. In particular, we provide an overview of the cross sections for elastic scattering, positronium formation, direct and total ionisation, as well as total scattering, at energies typically between about 0.1 and a few hundred eV. We discuss the differences in the current experimental data sets and compare those results to the available theoretical models. Recommended data sets for the total cross section are also reported for each noble gas. A summary of the recent developments in the scattering from other atoms, such as atomic hydrogen, the alkali and alkaline-earth metals, and two-electron systems is finally provided.

Chiari, Luca; Zecca, Antonio

2014-10-01

307

pi+- p differential cross sections at low energies  

SciTech Connect

Differential cross sections for pi- p and pi+ p elastic scattering were measured at five energies between 19.9 and 43.3 MeV. The use of the CHAOS magnetic spectrometer at TRIUMF, supplemented by a range telescope for muon background suppression, provided simultaneous coverage of a large part of the full angular range, thus allowing very precise relative cross section measurements. The absolute normalization was determined with a typical accuracy of 5 %. This was verified in a simultaneous measurement of muon proton elastic scattering. The measured cross sections show some deviations from phase shift analysis predictions, in particular at large angles and low energies. From the new data we determine the real part of the isospin forward scattering amplitude.

H. Denz; P. Amaudruz; J.T. Brack; J. Breitschopf; P. Camerini; J.L. Clark; H. Clement; L. Felawka; E. Fragiacomo; E.F. Gibson; N. Grion; G.J. Hofman; B. Jamieson; E.L. Mathie; R. Meier; G. Moloney; D. Ottewell; O. Patarakin; J.D. Patterson; M.M. Pavan; S. Piano; K. Raywood; R.A. Ristinen; R. Rui; M.E. Sevior; G.R. Smith; J. Stahov; R. Tacik; G.J. Wagner; F. von Wrochem; D.M. Yeomans

2005-12-03

308

A new method for the calculation of photodissociation cross sections  

NASA Technical Reports Server (NTRS)

A time-independent quantum mechanical approach to the calculation of photodissociation cross sections is developed. The method is based on the use of a discrete variable representation and the application of absorbing boundary conditions. Both total photodissociation cross sections and partial cross sections (hence product state distributions) are obtained using the same basic technique, but the calculation is particularly efficient when only the former quantity is required. The method is applied to the photodissociation of HCl(+) for which accurate potential energy curves and dipole moment functions are available, to the photodissociation of ClCN which is a direct process, involving a single excited electrosonic state, and to the photodissociation of ICN, which involves several strongly coupled excited electronic states.

Seideman, Tamar

1993-01-01

309

Dosimetry and cross section measurements at RTNS II  

SciTech Connect

Numerous measurements have been conducted at TRNS-II in order to map the neutron field for materials irradiations, to measure activation cross sections, and to measure helium production cross sections. Experiments of up to two weeks duration irradiated large numbers of activation dosimetry and helium samples both close to the source and throughout the target room. Many other samples have been irradiated in piggy-back positions over periods lasting many months. All of these experiments fall into four main classes, namely, fluence-mapping, activation dosimetry, the production of long-lived isotopes, and helium generation measurements. Radiometric dosimetry and activation cross section measurements were performed at Argonne National Laboratory; helium production was measured at Rockwell International Corporation. This paper briefly summarizes the principal results of our measurements at RTNS-II; references are given for more detailed publications. 14 refs., 4 figs.

Greenwood, L.R.; Kneff, D.W.

1987-01-01

310

Lanl Neutron-Induced Fission Cross Section Measurement Program  

NASA Astrophysics Data System (ADS)

A well established program of neutron-induced fission cross section measurement at Los Alamos Neutron Science Center (LANSCE) is supporting the Fuel Cycle Research program (FC R&D). Combining measurements at two LANSCE facilities, the Lujan Center and the Weapons Neutron Research facility (WNR), cover neutron energies over 10 orders of magnitude: from sub-thermal up to 200 MeV. A parallel-plate fission ionization chamber was used as a fission fragment detector. The 235U(n,f) standard was used as the reference. Fission cross sections have been measured for multiple actinides. The new data presented here completes the suite of long-lived Uranium isotopes that were investigated with this experimental approach. The cross section data are presented in comparison with existing evaluations and previous measurements.

Laptev, A. B.; Tovesson, F.; Hill, T. S.

2014-09-01

311

pi+- p differential cross sections at low energies  

E-print Network

Differential cross sections for pi- p and pi+ p elastic scattering were measured at five energies between 19.9 and 43.3 MeV. The use of the CHAOS magnetic spectrometer at TRIUMF, supplemented by a range telescope for muon background suppression, provided simultaneous coverage of a large part of the full angular range, thus allowing very precise relative cross section measurements. The absolute normalisation was determined with a typical accuracy of 5 %. This was verified in a simultaneous measurement of muon proton elastic scattering. The measured cross sections show some deviations from phase shift analysis predictions, in particular at large angles and low energies. From the new data we determine the real part of the isospin forward scattering amplitude.

H. Denz; P. Amaudruz; J. T. Brack; J. Breitschopf; P. Camerini; J. L. Clark; H. Clement; L. Felawka; E. Fragiacomo; E. F. Gibson; N. Grion; G. J. Hofman; B. Jamieson; E. L. Mathie; R. Meier; G. Moloney; D. Ottewell; O. Patarakin; J. D. Patterson; M. M. Pavan; S. Piano; K. Raywood; R. A. Ristinen; R. Rui; M. E. Sevior; G. R. Smith; J. Stahov; R. Tacik; G. J. Wagner; F. von Wrochem; D. M. Yeomans

2005-12-03

312

Differential Cross Sections for Proton-Proton Elastic Scattering  

NASA Technical Reports Server (NTRS)

Proton-proton elastic scattering is investigated within the framework of the one pion exchange model in an attempt to model nucleon-nucleon interactions spanning the large range of energies important to cosmic ray shielding. A quantum field theoretic calculation is used to compute both differential and total cross sections. A scalar theory is then presented and compared to the one pion exchange model. The theoretical cross sections are compared to proton-proton scattering data to determine the validity of the models.

Norman, Ryan B.; Dick, Frank; Norbury, John W.; Blattnig, Steve R.

2009-01-01

313

Neutron capture cross section standards for BNL 325, Fourth Edition  

SciTech Connect

This report evaluates the experimental data and recommends values for the thermal neutron cross sections and resonance integrals for the neutron capture reactions: /sup 55/Mn(n,..gamma..), /sup 59/Co(n,..gamma..) and /sup 197/Au(n,..gamma..). The failure of lithium and boron as standards due to the natural variation of the absorption cross sections of these elements is discussed. The Westcott convention, which describes the neutron spectrum as a thermal Maxwellian distribution with an epithermal component, is also discussed.

Holden, N.E.

1981-01-01

314

Measurements of multiphoton action cross sections for multiphoton microscopy  

PubMed Central

We report quantitative measurements of two-, three-, and four-photon excitation action cross sections of several commonly used fluorophores and fluorescent proteins at three different excitation wavelengths of 800 nm, 1300 nm, and 1680 nm. The measured cross section values are consistent with simple quantum mechanic estimations. These values indicate that the optimum repetition rate for deep tissue 3-photon microscopy is approximately 1 to 2 MHz. We further demonstrate that it is feasible to perform 4-photon fluorescence microscopy of GFP labeled microglia in mouse brain in vivo at 1700 nm. 4-photon excitation increases the accessibility of fluorophores at the long wavelength spectral window of 1700 nm. PMID:25360361

Cheng, Li-Chung; Horton, Nicholas G.; Wang, Ke; Chen, Shean-Jen; Xu, Chris

2014-01-01

315

Neutron removal cross section as a measure of neutron skin  

NASA Astrophysics Data System (ADS)

We study the relation between neutron removal cross section (?-N) and neutron skin thickness for finite neutron-rich nuclei using the statistical abrasion ablation model. Different sizes of neutron skin are obtained by adjusting the diffuseness parameter of neutrons in the Fermi distribution. It is demonstrated that there is a good linear correlation between ?-N and the neutron skin thickness for neutron-rich nuclei. Further analysis suggests that the relative increase of neutron removal cross section could be used as a quantitative measure for neutron skin thickness in neutron-rich nuclei.

Fang, D. Q.; Ma, Y. G.; Cai, X. Z.; Tian, W. D.; Wang, H. W.

2010-04-01

316

Total cross section of electron scattering by fluorocarbon molecules  

NASA Astrophysics Data System (ADS)

A compact linear electron transmission apparatus was used for the measurement of the total electron scattering cross section at 4-500 eV. Total cross sections of chlorofluorocarbon (CCl2F2), hydrochlorofluorocarbon (CHClF2), perfluoropropane (C3F8), perfluoro-n-pentane (C5F12), perfluoro-n-hexane (C6F14) and perfluoro-n-octane (C8F18) were obtained experimentally and compared with the values obtained from a theoretical calculation and semi-empirical model calculation.

Yamada, T.; Ushiroda, S.; Kondo, Y.

2008-12-01

317

Impact dynamics of granular jets with noncircular cross sections  

NASA Astrophysics Data System (ADS)

Using high-speed photography, we investigate two distinct regimes of the impact dynamics of granular jets with noncircular cross sections. In the steady-state regime, we observe the formation of thin granular sheets with anisotropic shapes and show that the degree of anisotropy increases with the aspect ratio of the jet's cross section. Our results illustrate the liquidlike behavior of granular materials during impact and demonstrate that a collective hydrodynamic flow emerges from strongly interacting discrete particles. We discuss the analogy between our experiments and those from the Relativistic Heavy Ion Collider, where similar anisotropic ejecta from a quark-gluon plasma have been observed in heavy-ion impact.

Cheng, Xiang; Gordillo, Leonardo; Zhang, Wendy W.; Jaeger, Heinrich M.; Nagel, Sidney R.

2014-04-01

318

Neutron removal cross section as a measure of neutron skin  

E-print Network

We study the relation between neutron removal cross section ($\\sigma_{-N}$) and neutron skin thickness for finite neutron rich nuclei using the statistical abrasion ablation (SAA) model. Different sizes of neutron skin are obtained by adjusting the diffuseness parameter of neutrons in the Fermi distribution. It is demonstrated that there is a good linear correlation between $\\sigma_{-N}$ and the neutron skin thickness for neutron rich nuclei. Further analysis suggests that the relative increase of neutron removal cross section could be used as a quantitative measure for the neutron skin thickness in neutron rich nuclei.

D. Q. Fang; Y. G. Ma; X. Z. Cai; W. D. Tian; H. W. Wang

2010-04-20

319

Inelastic cross sections from gamma-ray measurements  

SciTech Connect

Measurements of gamma rays following neutron induced reactions have been studied with the Germanium Array for Neutron-induced Excitations (GEANIE) at the Los Alamos Neutron Science Center (LANSCE) for many years. Gamma-ray excitation functions and coincidence studies provide insight into nuclear reaction mechanisms as well as expanding our knowledge of energy levels and gamma-rays. Samples studied with Ge detectors at LANSCE range from Be to Pu. Fe, Cr and Ti have been considered for use as reference cross sections. An overview of the measurements and efforts to create a reliable neutron-induced gamma-ray reference cross section will be presented.

Nelson, Ronald Owen [Los Alamos National Laboratory

2010-12-06

320

Cross sections and spectra for charged-particle induced reactions  

SciTech Connect

Using calculational methods based on R-matrix theory, we have obtained cross sections and spectra for a number of charged-particle reactions, including those initiated by d+t, t+t, and t+{sup 6}Li. The three-body resonance model used to calculate the spectra resembles the sequential-decay model, but it sometimes gives different results. Contributions from resonances involving the detected particle can produce the broad structure underlying the narrow peaks in the spectra that is often attributed to ``three-body phase space.`` We will show examples of calculated cross sections and spectra, compared to the measured data.

Hale, G.M.; Talley, T.L.

1994-06-01

321

Cross section measurements for studies on nuclear transmutation and nucleosynthesis  

SciTech Connect

Neutron cross section measurements with a new {gamma}-ray detection system have started at the Tokyo Institute of Technology for studies on the nuclear transmutation of long-lived fission product nuclides and transuranic nuclides and on the nucleosynthesis in stars and in the primordial universe. The first results about the capture cross sections and/or capture {gamma}-ray spectra of {sup 1}H, {sup 10,11}B, {sup 19}F, {sup 149}Sm, and {sup 161,162,163}Dy are presented and discussed.

Igashira, Masayuki; Masuda, Koji; Nagai, Yasuki; Kitazawa, Hideo [Tokyo Institute of Technology (Japan)

1994-12-31

322

Neutrino versus antineutrino cross sections and CP violation  

NASA Astrophysics Data System (ADS)

We discuss the nuclear interactions of neutrinos versus those of antineutrinos, a relevant comparison for CP violation experiments in the neutrino sector. We consider the MiniBooNE quasielastic-like double-differential neutrino and antineutrino cross sections that are dependent on the energy profiles of the neutrino fluxes and hence specific to the MiniBooNE setup. We combine them introducing their sum (? +? ¯) and their difference (? -? ¯) . We show that the last combination gives general information on the multinucleon content of the axial-vector interference term. Our theoretical model reproduces well the two cross-section combinations, confirming the need for a sizable multinucleon component.

Ericson, M.; Martini, M.

2015-03-01

323

Singly differential cross sections with exchange for Ps-fragmentation  

E-print Network

Ps ionization in Ps-atom scattering is of fundamental importance. The singly differential cross sections (SDCS) provides more accurate information to test a theory than integrated or total ionization cross section since the averaging over one parameter is not required. We evaluate the SDCS for Ps-ionization with respect to the longitudinal energy distribution of the break-up positron and electron in Ps-H and Ps-He scattering and compare them with the recently available experimental and theoretical data.

Hasi Ray

2008-08-28

324

Transition to chaotic scattering: signatures in the differential cross section.  

PubMed

We show that bifurcations in chaotic scattering manifest themselves through the appearance of an infinitely fine-scale structure of singularities in the cross section. These "rainbow singularities" are created in a cascade, which is closely related to the bifurcation cascade undergone by the set of trapped orbits (the chaotic saddle). This cascade provides a signature in the differential cross section of the complex pattern of bifurcations of orbits underlying the transition to chaotic scattering. We show that there is a power law with a universal coefficient governing the sequence of births of rainbow singularities and we verify this prediction by numerical simulations. PMID:18999505

Schelin, Adriane B; de Moura, Alessandro P S; Grebogi, Celso

2008-10-01

325

PCS a code system for generating production cross section libraries  

SciTech Connect

This document outlines the use of the PCS Code System. It summarizes the execution process for generating FORMAT2000 production cross section files from FORMAT2000 reaction cross section files. It also describes the process of assembling the ASCII versions of the high energy production files made from ENDL and Mark Chadwick`s calculations. Descriptions of the function of each code along with its input and output and use are given. {ital This document is under construction. Please submit entries, suggestions, questions, and corrections to} {bold (ljc@llnl.gov)} 3 tabs.

Cox, L.J.

1997-04-01

326

Iterative cross section sequence graph for handwritten character segmentation.  

PubMed

The iterative cross section sequence graph (ICSSG) is an algorithm for handwritten character segmentation. It expands the cross section sequence graph concept by applying it iteratively at equally spaced thresholds. The iterative thresholding reduces the effect of information loss associated with image binarization. ICSSG preserves the characters' skeletal structure by preventing the interference of pixels that causes flooding of adjacent characters' segments. Improving the structural quality of the characters' skeleton facilitates better feature extraction and classification, which improves the overall performance of optical character recognition (OCR). Experimental results showed significant improvements in OCR recognition rates compared to other well-established segmentation algorithms. PMID:17688219

Dawoud, Amer

2007-08-01

327

A radar-echo model for Mars  

NASA Technical Reports Server (NTRS)

Researchers developed a radar-echo model for Mars based on 12.6 cm continuous wave radio transmissions backscattered from the planet. The model broadly matches the variations in depolarized and polarized total radar cross sections with longitude observed by Goldstone in 1986 along 7 degrees S. and yields echo spectra that are generally similiar to the observed spectra. Radar map units in the model include an extensive cratered uplands unit with weak depolarized echo cross sections, average thermal inertias, moderate normal refelectivities, and moderate rms slopes; the volcanic units of Tharsis, Elysium, and Amazonis regions with strong depolarized echo cross sections, low thermal inertia, low normal reflectivities, and large rms slopes; and the northern planes units with moderate to strong depolarized echo cross sections, moderate to very high thermal inertias, moderate to large normal reflectivities, and moderate rms slopes. The relevance of the model to the interpretation of radar echoes from Mars is discussed.

Thompson, T. W.; Moore, H. J.

1990-01-01

328

Calculating the cross-sectional passage of a conical valve  

Microsoft Academic Search

To design a self-regulating expansion refrigerator and to predict its characteristics, the authors find a relationship for the cross-sectional area of the conical valve passage which governs the cryogenic agent's flow rate, as a function of the lift of the shutoff device. A design drawing is provided of the passage section of a conical valve. The proposed equations are recommended

Yu. I. Landa

1987-01-01

329

Skin Diseases: Cross-section of human skin  

MedlinePLUS

Skip Navigation Bar Home Current Issue Past Issues Skin Diseases Cross-section of human skin Past Issues / Fall 2008 Table of Contents For ... Logical Images, Inc. I n the areas of skin health and skin diseases, the NIH's National Institute ...

330

Complex Correlation Calculation of e-H Total Cross Sections  

NASA Technical Reports Server (NTRS)

Calculation of e - H total and elastic partial wave cross sections is being carried out using the complex correlation variational T-matrix method. In this preliminary study, elastic partial wave phase shifts are calculated with the correlation functions which are confined to be real. In that case the method reduces to the conventional optical potential approach with projection operators.

Bhatia, A. K.; Temkin, Aaron; Fisher, Richard R. (Technical Monitor)

2001-01-01

331

Stellar neutron capture cross sections of the Lu isotopes  

SciTech Connect

The neutron capture cross sections of {sup 175}Lu and {sup 176}Lu have been measured in the energy range 3-225 keV at the Karlsruhe 3.7 MV Van de Graaff accelerator. Neutrons were produced via the {sup 7}Li(p,n){sup 7}Be reaction by bombarding metallic Li targets with a pulsed proton beam, and capture events were registered with the Karlsruhe 4{pi} barium fluoride detector. The cross sections were determined relative to the gold standard using isotopically enriched as well as natural lutetium oxide samples. Overall uncertainties of {approx}1% could be achieved in the final cross section ratios to the gold standard, about a factor of 5 smaller than in previous works. Maxwellian averaged neutron capture cross sections were calculated for thermal energies between kT = 8 and 100 keV. These values are systematically larger by {approx}7% than those reported in recent evaluations. These results are of crucial importance for the assessment of the s-process branchings at A 175/176.

Wisshak, K.; Voss, F.; Kaeppeler, F.; Kazakov, L. [Forschungszentrum Karlsruhe, Institut fuer Kernphysik, Postfach 3640, D-76021 Karlsruhe (Germany); Institute for Physics and Power Engineering, Obninsk, Kaluga-Region (Russian Federation)

2006-01-15

332

Service building. Cross section thru dry dock nos. 4 & ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Service building. Cross section thru dry dock nos. 4 & 5 showing service bldg & 20-75-150 ton cranes (dry dock associates, May 23, 1941). In files of Cushman & Wakefield, building no. 501, Philadelphia Naval Business Center. - Naval Base Philadelphia-Philadelphia Naval Shipyard, Service Building, Dry Docks No. 4 & 5, League Island, Philadelphia, Philadelphia County, PA

333

Measurements of the fission cross section of {sup 237}Np  

SciTech Connect

Measurements have been made of the fission cross section of {sup 237}Np below 2 MeV neutron energy in order to improve the data base of this important cross section. The data were obtained with a white neutron source at the Los Alamos Neutron Scattering Center at Los Alamos National Laboratory. The measurements were made with ionization chambers containing {sup 237}Np deposits located at the end of a 60-m flight path. The fission cross section data are relative to the {sup 235}U(n,f) standard at the higher energies. At the lower energies, the {sup 10}B(n,{alpha}) standard was used to determine the energy dependence of the neutron fluence and the normalization was based on the very accurate 7.8 to 11.0 eV resonance integral for {sup 235}U(n,f). The results of this work indicate that the ENDF/B-VI evaluation of the {sup 237}Np(n,f) cross section is about a factor of three low in the 5 eV to 5 keV energy region but only about 3% lower than this work near 1 MeV neutron energy.

Carlson, A.D. [National Institute of Standards and Technology, Gaithersburg, MD (United States); Parker, W.E. [Lawrence Livermore National Lab., CA (United States); Lisowski, P.W.; Morgan, G.L.; Seestrom, S. [Los Alamos National Lab., NM (United States); Hill, N.W. [Oak Ridge National Lab., TN (United States); Meggers, K. [Univ. of Kiel, Geesthacht (Germany)

1994-12-31

334

Experiments on internal strain in lava dome cross sections  

Microsoft Academic Search

Simple experiments have been conducted to study the strain evolution in lava dome cross sections. A viscous fluid is injected vertically from a reservoir into a feeding conduit. Silicone putty is used as analogue magma. Two-dimensional experiments allow the assessment of the internal strain within the dome. Particle paths are symmetrical on either side of a central line passing through

C. Buisson; O. Merle

2002-01-01

335

Top quark cross-section measurements at the Tevatron  

SciTech Connect

Run II of the Tevatron collider at Fermilab is well under way and data samples larger than those of Run I are at hand. In this contribution the author summarizes the current status of cross-section measurements for top-quark pair (t{bar t}) production at the CDF and D0 experiments.

Wolfgang Wagner

2003-12-11

336

Cross section measurements via residual nuclear decays: Analysis methods  

NASA Astrophysics Data System (ADS)

We develop an approach to calculating the pure cross section of the ground state of artificial radioactive nuclides that subtracts the effect of an excited state on the ground state. We apply a formalism to obtaining pure cross sections by subtracting the effect of excited states in the reactions Te122(n,2n)Te121g and Te128(n,2n)Te127g, induced by neutrons of about 14 MeV. The cross sections are measured by an activation relative to the Nb93(n,2n)Nb92m reaction and are compared with results that take into account the effect of the excited state. Measurements are carried out by ? detection using a coaxial high-purity germanium (HPGe) detector. As samples, spectroscopically pure Te powder is used. The fast neutrons are produced by the H3(d,n)He4 reaction. The neutron energies in these measurements are determined using the method of cross-section ratios between the Zr90(n,2n)Zr89m+g and Nb93(n,2n)Nb92m reactions.

Zhou, Fengqun; Gao, Lei; Kong, Xiangzhong; Luo, Junhua; Li, Kuohu; Song, Yueli; Zhang, Fang

2009-11-01

337

Measurement of the Z??? cross section with the ATLAS detector  

E-print Network

The Z??? cross section is measured with the ATLAS experiment at the LHC in four different final states determined by the decay modes of the ? leptons: muon-hadron, electron-hadron, electron-muon, and muon-muon. The analysis ...

Taylor, Frank E.

338

Propagation of sound waves in tubes of noncircular cross section  

NASA Technical Reports Server (NTRS)

Plane-acoustic-wave propagation in small tubes with a cross section in the shape of a flattened oval is described. Theoretical descriptions of a plane wave propagating in a tube with circular cross section and between a pair of infinite parallel plates, including viscous and thermal damping, are expressed in similar form. For a wide range of useful duct sizes, the propagation constant (whose real and imaginary parts are the amplitude attenuation rate and the wave number, respectively) is very nearly the same function of frequency for both cases if the radius of the circular tube is the same as the distance between the parallel plates. This suggests that either a circular-cross-section model or a flat-plate model can be used to calculate wave propagation in flat-oval tubing, or any other shape tubing, if its size is expressed in terms of an equivalent radius, given by g = 2 x (cross-sectional area)/(length of perimeter). Measurements of the frequency response of two sections of flat-oval tubing agree with calculations based on this idea. Flat-plate formulas are derived, the use of transmission-line matrices for calculations of plane waves in compound systems of ducts is described, and examples of computer programs written to carry out the calculations are shown.

Richards, W. B.

1986-01-01

339

Photoelectric K-Absorption Cross Section of Beryllium  

Microsoft Academic Search

The continuous photoelectric absorption cross section of Be has been measured for photon energies extending from the K edge energy, at 110 eV, to 180 eV. The measurements were carried out by the application of technical improvements which included a more precise electronic method for determining the surface density of absorbers and auxiliary equipment for transfering samples into the spectrograph

T. J. Peterson; E. J. McGuire; D. H. Tomboulian

1963-01-01

340

Charge Transfer Cross Sections for Dysprosium and Cerium  

Microsoft Academic Search

Symmetric charge transfer cross sections between singly ionized ions and their parent atoms were measured for dysprosium and cerium in the impact energy range of 100 2000 eV. The primary ion beam was extracted from a laser ion source in which the atoms were ionized by laser resonant photo-ionization. The slow ions produced in the charge transfer reaction and the

Koji Tamura; Hajime Adachi; TakemasaShibata TakemasaShibata

1999-01-01

341

Calculations of PhotoIonization Cross Sections for Lithium Atoms  

Microsoft Academic Search

Photo-ionization cross sections for the ground and the n <= 5 excited states of lithium atoms are calculated in the photoelectron energy ranging from threshold to 0.5 Rydberg. The wavefunctions for both the bound and continuum states are obtained by solving the Schrodinger equation numerically in a symplectic scheme. Our results are in excellent agreement with the recent experimental measurements

Yue-Ying Qi; Yong Wu; Jian-Guo Wang; Pei-Zhu Ding

2008-01-01

342

Skin effect in toroidal conductors with circular cross-section  

Microsoft Academic Search

Purpose – The paper deals with the current density distributions in toroidal conductors of circular cross-section. Design\\/methodology\\/approach – A review of the analytical solutions existing in the literature only for the case of very thin skin depth is presented. Findings – Results are given for different aspect ratios of torus. The accuracy of these analytical solutions is verified by comparison

A. Aliferov; S. Lupi

2008-01-01

343

Scattering from chiral cylinders of circular cross-sections  

Microsoft Academic Search

A semi-analytical solution is presented to the problem of electromagnetic scattering from a collection of parallel chiral cylinders of circular cross-section. The cylinders are illuminated by either a TEz or a TMz incident plane wave. The solution procedure is useful in predicting the scattering properties of arbitrary shaped two-dimensional scatterers composed of dielectric, conducting, and chiral media.

A. Z. Elsherbeni; M. Al Sarkawy; S. F. Mahmoud

2003-01-01

344

Scattering by a dielectric cylinder of arbitrary cross section shape  

Microsoft Academic Search

The theory and equations are developed for the scattering pattern of a dielectric cylinder of arbitrary cross section shape. The harmonic incident wave is assumed to have its electric vector parallel with the axis of the cylinder, and the field intensities are assumed to be independent of distance along the axis. Solutions are readily obtained for inhomogeneous cylinders when the

JACK H. RICHMOND

1965-01-01

345

Multiply Reflected Gaussian Beams in a Circular Cross Section  

Microsoft Academic Search

A well-collimated beam reflected repeatedly within a circular cross section undergoes periodic focusing and defocusing. This behavior is of interest for tracking of beams around a type of acoustic surface wave disk delay line, and it also relates to beam monitoring after oblique injection into the endface of a multimode optical fiber. The problem is analyzed by considering first the

Sang-Yung Shin; LEOPOLD B. FELSEN

1978-01-01

346

NEODYMIUM NEUTRON CROSS SECTION MEASUREMENTS D. P. Barry1  

E-print Network

NEODYMIUM NEUTRON CROSS SECTION MEASUREMENTS D. P. Barry1 , M. J. Trbovich1 , Y. Danon1 , R. C at the Rensselaer Polytechnic Institute LINAC using metallic neodymium samples. The capture measurements were made for all naturally occurring neodymium isotopes lie within the energy range of 1.0­ 500 eV. The resulting

Danon, Yaron

347

Predictions of diffractive cross sections in proton-proton collisions  

SciTech Connect

We review our pre-LHC predictions of the total, elastic, total-inelastic, and diffractive components of proton-proton cross sections at high energies, expressed in the form of unitarized expressions based on a special parton-model approach to diffraction employing inclusive proton parton distribution functions and QCD color factors and compare with recent LHC results.

Goulianos, Konstantin [Rockefeller University, 1230 York Avenue, New York, NY 10065 (United States)

2013-04-15

348

Econometric Analysis of Cross Section and Panel Data  

Microsoft Academic Search

This graduate text provides an intuitive but rigorous treatment of contemporary methods used in microeconometric research. The book makes clear that applied microeconometrics is about the estimation of marginal and treatment effects, and that parametric estimation is simply a means to this end. It also clarifies the distinction between causality and statistical association. The book focuses specifically on cross section

Jeffrey M. Wooldridge

2002-01-01

349

Estimating the Raman cross sections of single carbon nanotubes  

E-print Network

Estimating the Raman cross sections of single carbon nanotubes Johanna E. Bohn, Pablo G. Etchegoin's) of individual carbon nanotubes is measured for 633 and 785 nm laser excitations, respectively. This is shown measurements of individual nanotubes at 633 nm ex- citation. We find typical values of differential cross

Maruyama, Shigeo

350

Cross Section; Half Longitudinal Section Showing Middle Wall Reinforced with ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Cross Section; Half Longitudinal Section Showing Middle Wall Reinforced with Arch; Part Long Section Showing Inside of External Side Wall; East Entrance; Part Side South External; Part Reflected Plan of Soffite of Floor; Part Reflected Plan of Soffite of Roof - Blenheim Covered Bridge, Spanning Schoharie River, North Blenheim, Schoharie County, NY

351

10. Historic American Buildings Survey CROSS SECTION ST. PATRICK'S ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

10. Historic American Buildings Survey CROSS SECTION - ST. PATRICK'S R. C. CHURCH c. 1839 - JAMES GALLIER, ARCHITECT, IN COLLECTION OF THE LOUISIANA STATE MUSEUM, JACKSON SQUARE, NEW ORLEANS, LA. - St. Patrick's Roman Catholic Church, 724 Camp Street, New Orleans, Orleans Parish, LA

352

Accurate momentum transfer cross section for the attractive Yukawa potential  

SciTech Connect

Accurate expression for the momentum transfer cross section for the attractive Yukawa potential is proposed. This simple analytic expression agrees with the numerical results better than to within ±2% in the regime relevant for ion-particle collisions in complex (dusty) plasmas.

Khrapak, S. A., E-mail: Sergey.Khrapak@dlr.de [Forschungsgruppe Komplexe Plasmen, Deutsches Zentrum für Luft- und Raumfahrt, Oberpfaffenhofen (Germany)

2014-04-15

353

Nuclear Science and Technology, November 2000. NEUTRON CROSS SECTION EVALUATIONS  

E-print Network

and the corresponding nuclear waste management it is necessary to know nuclear data on spectra and reaction crossNuclear Science and Technology, November 2000. 1 NEUTRON CROSS SECTION EVALUATIONS FOR 238 U UP and Power Engineering, 249020 Obninsk, Russia A.Ventura ENEA, Nuclear Data Center and INFN, Bologna Section

354

Benchmark experiments to test plutonium and stainless steel cross sections  

Microsoft Academic Search

Neutronics calculations of physical systems containing fissionable material in various configurations are often necessary to assess criticality safety and economic parameters. Criticality safety of the material must be assured for all configurations in the fuel fabrication, spent fuel reprocessing, and transportation processes. Integral criticality experiments are utilized to evaluate neutron cross sections, test theoretical methods, and validate calculational procedures. The

U. P. Jenquin; S. R. Bierman

1978-01-01

355

Benchmark experiments to test plutonium and stainless steel cross sections  

SciTech Connect

Neutronics calculations of physical systems containing fissionable material in various configurations are often necessary to assess criticality safety and economic parameters. Criticality safety of the material must be assured for all configurations in the fuel fabrication, spent fuel reprocessing, and transportation processes. Integral criticality experiments are utilized to evaluate neutron cross sections, test theoretical methods, and validate calculational procedures. The Nuclear Regulatory Commission (NRC) commissioned Battelle, Pacific Northwest Laboratory (PNL) to ascertain the accuracy of the neutron cross sections for the isotopes of plutonium and the constituents of stainless steel and determine if improvements can be made in application to criticality safety analysis. NRC's particular area of interest is in the transportation of light--water reactor spent fuel assemblies. The project was divided into two tasks. The first task was to define a set of integral experimental measurements (benchmarks). The second task is to use these benchmarks in neutronics calculations such that the accuracy of ENDF/B-IV plutonium and stainless steel cross sections can be assessed. The results of the second task should help to identify deficiencies in the neutron cross sections. The results of the first task are given.

Jenquin, U.P.; Bierman, S.R.

1978-06-01

356

ENDF/B-6 neutron cross section measurement standards  

NASA Astrophysics Data System (ADS)

The document provides information on the neutron cross section standards placed in the ENDF/B-VI library. The H(n,n), (3)He(n,p), and C(n,n) cross sections were each obtained from well established R-matrix analysis techniques. The additional standards, i.e., the (6)Li(n,t), (10)B(n,alpha 1), Au(n,gamma), and (235)U(n,f) cross sections were obtained with a new method. The new method involves combining the results of a simultaneous evaluation and R-matrix analyses. Contained herein is a discussion of the development of the method, a description of the evaluation process, some information on the various experiments used in the analyses, comparisons of the R-matrix, simultaneous evaluation and combination results, and comparisons to ENDF/B-V. Tables of numerical data are given for each of the cross section standards. Also, the new ENDF/B-VI evaluation for the spontaneous fission neutron spectrum for (252)Cf is given.

Carlson, A. D.; Poenitz, W. P.; Hale, G. M.; Peelle, R. W.; Dodder, D. C.

1993-05-01

357

K-shell ECPSSR cross sections for analytical applications  

Microsoft Academic Search

Methods for the ECPSSR cross section calculation are examined. Direct integration procedures of the electronic form factor and the methods using the tabulated universal functions are reviewed and compared. A simple yet accurate direct integration procedure is proposed. Different approximations for the energy loss correction are shown to differ up to few percent in the low velocity region.

Z. Smit

1989-01-01

358

Neutron capture cross section of {sup 241}Am  

SciTech Connect

The neutron capture cross section of {sup 241}Am for incident neutrons from 0.02 eV to 320 keV has been measured with the detector for advanced neutron capture experiments (DANCE) at the Los Alamos Neutron Science Center. The thermal neutron capture cross section was determined to be 665{+-}33 b. Our result is in good agreement with other recent measurements. Resonance parameters for E{sub n}<12 eV were obtained using an R-matrix fit to the measured cross section. The results are compared with values from the ENDF/B-VII.0, Mughabghab, JENDL-3.3, and JEFF-3.1 evaluations. {gamma}{sub n} neutron widths for the first three resonances are systematically larger by 5-15% than the ENDF/B-VII.0 values. The resonance integral above 0.5 eV was determined to be 1553{+-}7 b. Cross sections in the resolved and unresolved energy regions above 12 eV were calculated using the Hauser-Feshbach theory incorporating the width-fluctuation correction of Moldauer. The calculated results agree well with the measured data, and the extracted averaged resonance parameters in the unresolved resonance region are consistent with those for the resolved resonances.

Jandel, M.; Bredeweg, T. A.; Bond, E. M.; Chadwick, M. B.; Clement, R. R.; Couture, A.; O'Donnell, J. M.; Haight, R. C.; Kawano, T.; Reifarth, R.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Wouters, J. M. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Agvaanluvsan, U.; Parker, W. E.; Wu, C. Y.; Becker, J. A. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

2008-09-15

359

Gluon Distributions and Fits using Dipole Cross-Sections  

E-print Network

I investigate the relationship between the gluon distribution obtained using a dipole model fit to low-x data on F_2(x,Q^2) and standard gluons obtained from global fits with the collinear factorization theorem at fixed order. I stress the necessity to do fits of this type carefully, and in particular to include the contribution from heavy flavours to the inclusive structure function. I find that the dipole cross-section must be rather steeper than the gluon distribution, which at least partially explains why dipole model fits produce dipole cross-sections growing quite strongly at small x, while DGLAP based fits have valence-like, or even negative, small-x gluons as inputs. However, I also find that the gluon distributions obtained from the dipole fits are much too small to match onto the conventional DGLAP gluons at high Q^2, i.e. approx 50 GeV^2, where the two approaches should coincide. The main reason for this discrepancy is found to be the large approximations made in converting the dipole cross-sections into structure functions using formulae which are designed only for asymptotically small x. The shortcomings in this step affect the accuracy of the extracted dipole cross-sections in terms of size and shape, and hence also in terms of interpretation, at all scales.

R. S. Thorne

2005-01-14

360

Cross-sectional survey of users of Internet depression communities  

Microsoft Academic Search

BACKGROUND: Internet-based depression communities provide a forum for individuals to communicate and share information and ideas. There has been little research into the health status and other characteristics of users of these communities. METHODS: Online cross-sectional survey of Internet depression communities to identify depressive morbidity among users of Internet depression communities in six European countries; to investigate whether users were

John Powell; Noel McCarthy; Gunther Eysenbach

2003-01-01

361

45. Cross Section through the Power House, from Construction Drawing ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

45. Cross Section through the Power House, from Construction Drawing 2042-F-23, entitled General Arrangement of Power Plant, Sections. (Original drawing, in the possession of Wyre Dick and Company, Livingston, New Jersey.) - Central Railroad of New Jersey, Engine Terminal, Jersey City, Hudson County, NJ

362

44. Cross section of the Blacksmith Shop from Construction Drawing ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

44. Cross section of the Blacksmith Shop from Construction Drawing 2042-F-15, entitled Machine and Blacksmith Shop; Plan, Elevations, and Sections. (Original drawing, in the possession of Wyre Dick and Company, Livingston, New Jersey.) - Central Railroad of New Jersey, Engine Terminal, Jersey City, Hudson County, NJ

363

GP registrar well-being: a cross-sectional survey  

Microsoft Academic Search

OBJECTIVES: To investigate the major stressors affecting GP registrars, how those at risk can be best identified and the most useful methods of managing or reducing their stress. DESIGN, SETTING AND PARTICIPANTS: Cross-sectional postal questionnaire of all GP registrars in one large regional training provider's catchment area. MAIN OUTCOME MEASURES: The Depression, Anxiety and Stress Scale (DASS), a specifically developed

Peter Schattner; Dennis Mazalin; Ciaran Pier; Jo Wainer; Mee Yoke Ling

2010-01-01

364

44. CROSS SECTION OF GRAND CANAL (not to scale, but ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

44. CROSS SECTION OF GRAND CANAL (not to scale, but representative of all six canals) Plan Sheet D-29976, Venice Canals Rehabilitation, Sheet No. 7 of 26 (delineated by T. Wu and E. Lee, March 1991) - Venice Canals, Community of Venice, Los Angeles, Los Angeles County, CA

365

Commentary: Mediation Analysis, Causal Process, and Cross-Sectional Data  

ERIC Educational Resources Information Center

Maxwell, Cole, and Mitchell (2011) extended the work of Maxwell and Cole (2007), which raised important questions about whether mediation analyses based on cross-sectional data can shed light on longitudinal mediation process. The latest article considers longitudinal processes that can only be partially explained by an intervening variable, and…

Shrout, Patrick E.

2011-01-01

366

Soda Lake Well Lithology Data and Geologic Cross-Sections  

SciTech Connect

Comprehensive catalogue of drill?hole data in spreadsheet, shapefile, and Geosoft database formats. Includes XYZ locations of well heads, year drilled, type of well, operator, total depths, well path data (deviations), lithology logs, and temperature data. Plus, 13 cross?sections in Adobe Illustrator format.

Faulds, James E.

2013-12-31

367

Soda Lake Well Lithology Data and Geologic Cross-Sections  

DOE Data Explorer

Comprehensive catalogue of drill?hole data in spreadsheet, shapefile, and Geosoft database formats. Includes XYZ locations of well heads, year drilled, type of well, operator, total depths, well path data (deviations), lithology logs, and temperature data. Plus, 13 cross?sections in Adobe Illustrator format.

Faulds, James E.

368

Rapidity gap survival probability and total cross sections  

E-print Network

We discuss recent calculations of the survival probability of the large rapidity gaps in exclusive processes of the type pp --> p+A+p at high energies. Absorptive or screening effects are important, and one consequence is that the total cross section at the LHC is predicted to be only about 90 mb.

A. D. Martin; V. A. Khoze; M. G. Ryskin

2008-10-20

369

Rapidity gap survival probability and total cross sections  

Microsoft Academic Search

We discuss recent calculations of the survival probability of the large\\u000arapidity gaps in exclusive processes of the type pp --> p+A+p at high energies.\\u000aAbsorptive or screening effects are important, and one consequence is that the\\u000atotal cross section at the LHC is predicted to be only about 90 mb.

A. D. Martin; V. A. Khoze; M. G. Ryskin

2008-01-01

370

Applications of cross sections for electron-molecule collision processes  

SciTech Connect

The role of electron-molecule collision cross sections is discussed for the study of the ionospheric and auroral processes in planetary atmospheres and of discharge-pumped lasers. These two areas emphasize the importance of further theoretical and experimental studies concerning electron-impact processes. 13 refs., 3 figs., 2 tabs. (WRF)

Cartwright, D.C.

1985-01-01

371

RZ calculations for self shielded multigroup cross sections  

SciTech Connect

A collision probability method has been implemented for RZ geometries. The method accounts for white albedo, specular and translation boundary condition on the top and bottom surfaces of the geometry and for a white albedo condition on the outer radial surface. We have applied the RZ CP method to the calculation of multigroup self shielded cross sections for Gadolinia absorbers in BWRs. (authors)

Li, M.; Sanchez, R.; Zmijarevic, I.; Stankovski, Z. [Commissariat a l'Energie Atomique CEA, Direction de l'Energie Nucleaire, DEN/DM2S/SERMA/LENR, 91191 Gif-sur-Yvette Cedex (France)

2006-07-01

372

EXPERIMENTAL PROTOCOL FOR DETERMINING ABSORPTION CROSS SECTIONS OF ORGANIC COMPOUNDS  

EPA Science Inventory

An experimental protocol for the determination of gas phase absorption cross-sections, and calculation of maximum photolysis rates, has been developed and is described in detail. Utilization of this protocol will provide a basis for evaluating the possible relative importance of ...

373

Thermal neutron capture cross sections of the potassium isotopes  

NASA Astrophysics Data System (ADS)

Precise thermal neutron capture ?-ray cross sections ?? for 39,40,41K were measured on a natural potassium target with the guided neutron beam at the Budapest Reactor. The cross sections were internally standardized using a stoichiometric KCl target with well-known 35Cl(n,?) ?-ray cross sections [Révay and Molnár, Radiochimica ActaRAACAP0033-823010.1524/ract.91.6.361.20027 91, 361 (2003); Molnár, Révay, and Belgya, Nucl. Instrum. Meth. Phys. Res. BNIMBEU0168-583X10.1016/S0168-583X(03)01529-5 213, 32 (2004)]. These data were combined with ?-ray intensities from von Egidy [von Egidy, Daniel, Hungerford, Schmidt, Lieb, Krusche, Kerr, Barreau, Borner, Brissot , J. Phys. G. Nucl. Phys.JPHGBM0305-461610.1088/0305-4616/10/2/013 10, 221 (1984)] and Krusche [Krusche, Lieb, Ziegler, Daniel, von Egidy, Rascher, Barreau, Borner, and Warner, Nucl. Phys. ANUPABL0375-947410.1016/0375-9474(84)90506-2 417, 231 (1984); Krusche, Winter, Lieb, Hungerford, Schmidt, von Egidy, Scheerer, Kerr, and Borner, Nucl. Phys. ANUPABL0375-947410.1016/0375-9474(85)90429-4 439, 219 (1985)] to generate nearly complete capture ?-ray level schemes. Total radiative neutron cross sections were deduced from the total ?-ray cross section feeding the ground state, ?0=???(GS) after correction for unobserved statistical ?-ray feeding from levels near the neutron capture energy. The corrections were performed with Monte Carlo simulations of the potassium thermal neutron capture decay schemes using the computer code dicebox where the simulated populations of low-lying levels are normalized to the measured cross section depopulating those levels. Comparisons of the simulated and experimental level feeding intensities have led to proposed new spins and parities for selected levels in the potassium isotopes where direct reactions are not a significant contribution. We determined the total radiative neutron cross sections ?0(39K)=2.28±0.04 b, ?0(40K)=90±7 b, and ?0(41K)=1.62±0.03 b from the prompt ?-ray data and the ?-ray transition probability P?(1524.66)=0.164(4) in the ?- decay of 42K in a low-background counting experiment.

Firestone, R. B.; Krti?ka, M.; Révay, Zs.; Szentmiklosi, L.; Belgya, T.

2013-02-01

374

Stellar neutron capture cross sections of Pr and Dy isotopes  

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of 141Pr,160Dy,161Dy,162Dy,163Dy, and 164Dy have been measured in the energy range from 3 to 225 keV at the Karlsruhe 3.75 MV Van de Graaff accelerator. Neutrons were produced via the 7Li(p,n)7Be reaction by bombarding metallic Li targets with a pulsed proton beam. Capture events were registered with the Karlsruhe 4? Barium Fluoride Detector. The cross sections were determined relative to the gold standard. For the first time the correction for undetected capture events was completely obtained from experimental information, using capture cascades derived from measurements with an analog-to-digital converter system. The cross section ratios could be determined with an overall uncertainty of 1-1.5 %, an average improvement compared to previous measurements by a factor 4. Maxwellian averaged neutron capture cross sections were calculated for thermal energies between kT=8 keV and 100 keV. For most of the isotopes there is reasonable agreement with recent evaluations, but discrepancies of ~20% were obtained for 160Dy and 164Dy. The experimental data were complemented by statistical model calculations in order to describe the cross section enhancements in the stellar environment. The astrophysical implications of the present data include the quest for the origin of 160Dy, the decomposition of the Dy abundances in the respective s- and r-process contributions, branchings of the s-process chain at the terrestrially stable isotopes 157Gd and 163Dy, and the isotopically anomalous dysprosium in meteoritic inclusions.

Voss, F.; Wisshak, K.; Arlandini, C.; Käppeler, F.; Kazakov, L.; Rauscher, T.

1999-02-01

375

A practical millimeter-wave radar calibration target  

Microsoft Academic Search

A simple rectangular-plate millimeter-wave radar calibration target gives RCS values ranging from hundreds to thousands of square meters. This enable tests over extended ranges and with equipment having modest output power. Precise mechanical alignment mechanisms and an optical sight are mandatory, due to the narrow beamwidth. Absorber collars provide an easy way of adjusting the actual RCS according to specific

J. Ruoskanen; P. Eskeffnen; H. Heikkila; P. Kuosmanen; T. Kiuru

2004-01-01

376

Incoherent-scattering cross sections in low- and medium-Z elements derived from the measured total attenuation cross sections in compounds  

Microsoft Academic Search

The whole-atom integral incoherent-scattering cross sections have been obtained from the total attenuation cross sections in elements whose atomic number (Z) ranges from 1 to 56, at photon energies 279.2, 514, 661.6, and 1115.5 keV. The total attenuation cross sections in elements were derived with the aid of mixture rule from total attenuation cross sections in 26 solid chemical compounds,

T. K. Umesh; C. Ranganathaiah; Ramakrishna Gowda; K. S. Puttaswamy; B. Sanjeevaiah

1981-01-01

377

Differential cross sections for ejection of electrons from argon by protons  

Microsoft Academic Search

Measured cross sections for ejection of electrons from argon gas by protons of 5 keV to 5 MeV energy are given as a function of the angle and energy of ejection. These doubly differential cross sections are integrated to obtain cross sections differential in either angle or energy, total electron production cross sections, and mean energies of ejection.

M. E. Rudd; L. H. Toburen; N. Stolterfoht

1979-01-01

378

162 IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, VOL. 33, NO. 1, JANUARY 1995 Behavior of the Ocean Radar Cross-  

E-print Network

of the Ocean Radar Cross- Section at Low Incidence, Observed in the Vicinity of the Gulf Stream Danikle Hauser to examine the behaviour of the radar cross-sectionU' versus incidence @ and azimuth 4. Although, considerableeffort has been devoted 0to the understanding of the behaviour of radar signal backscattered from

Miami, University of

379

Total cross sections for positron scattering from argon atoms at intermediate energies  

Microsoft Academic Search

A model complex potential is employed to obtain integrated elastic cross sections, absorption cross sections, and total cross sections for positron scattering from argon atoms in 100-800 eV energy range. The total cross sections are found to be in good agreement with the experimental data for E>=300 eV and lower than the corresponding electron cross sections over the whole energy

S. P. Khare; Ashok Kumar; Kusum Lata

1986-01-01

380

Total Electron Scattering and Electronic State Excitations Cross Sections for O_2, CO, and CH_4  

NASA Technical Reports Server (NTRS)

Available electron collision cross section data concerning total and elastic scattering, vibrationalexcitation, and ionization for O_2, CO, and CH_4 have been critically reviewed, and a set of crosssections for modeling of planetary atmospheric behavior is recommended. Utilizing theserecommended cross sections, we derived total electronic state excitation cross sections and upperlimits for dissociation cross sections, which in the case of CH_4 should very closely equal the actualdissociation cross section.

Kanik, I.; Trajmar, S.; Nickel, J. C.

1993-01-01

381

A Special-Purpose Digital Radar Simulation and Performance Prediction Model  

Microsoft Academic Search

A special-purpose radar model has been developed to provide interim capability in the evaluation of Army radar performance. This irterim model is designed to be used pending development of the radar scoring facility and will be replaced by the empirical prediction model developed from the radar scoring facility. The radar model has three basic sections: (1) cross section and signal

Merle E. Parmer

1968-01-01

382

Accurate Development of Thermal Neutron Scattering Cross Section Libraries  

SciTech Connect

The objective of this project is to develop a holistic (fundamental and accurate) approach for generating thermal neutron scattering cross section libraries for a collection of important enutron moderators and reflectors. The primary components of this approach are the physcial accuracy and completeness of the generated data libraries. Consequently, for the first time, thermal neutron scattering cross section data libraries will be generated that are based on accurate theoretical models, that are carefully benchmarked against experimental and computational data, and that contain complete covariance information that can be used in propagating the data uncertainties through the various components of the nuclear design and execution process. To achieve this objective, computational and experimental investigations will be performed on a carefully selected subset of materials that play a key role in all stages of the nuclear fuel cycle.

Hawari, Ayman; Dunn, Michael

2014-06-10

383

State-selective cross sections of multiple photoionization in Ne  

SciTech Connect

Valence double photoionization of Ne atom has been investigated by multielectron spectroscopy. Complete information on energy correlation between ejected electrons allows the identification of Ne{sup 2+} final states and their formation mechanism. In addition to simultaneous two-electron emission from the valence shells, indirect processes mediated by singly charged excited states have been observed. We have first obtained direct double-photoionization cross sections state-selectively in a wide photon energy region, by evaluating the contributions of the indirect processes. We have also applied the coincidence spectroscopy to three-electron emission from the valence shells. Even in the three-electron emission, the coincidence analysis enables to observe individual Ne{sup 3+} final states related to the triple-photoionization process and to obtain the state-selective cross sections.

Kaneyasu, T.; Hikosaka, Y.; Shigemasa, E.; Penent, F.; Lablanquie, P.; Aoto, T.; Ito, K. [UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585 (Japan); LCP-MR, Universite Pierre et Marie Curie-Paris 6 and CNRS (UMR 7614), 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France); Photon Factory, Institute of Materials Structure Science, Oho, Tsukuba 305-0801 (Japan)

2007-07-15

384

Simultaneous Evaluation of Fission Cross Sections for Cm Isotopes  

NASA Astrophysics Data System (ADS)

Fission Cross Sections for a complete set of Cm-isotopes, 240-250Cm, have been calculated in the incident energy range from above resonance region to 20 MeV. This work aims at providing the fission cross sections with consistent set of model parameters for Cm isotopes, as a part of a complete evaluation including covariance files for several minor actinides which play a great role in the Advanced Fuel Cycle (AFC) design and applications as well as the design of new generation of nuclear reactors (GEN-IV). This was accomplished by means of computational analyses carried out with the nuclear model code EMPIRE-2.19 which is the modular system of nuclear reaction codes. A Fission model of this work took into account transmission derived in the WKB approximation within an optical model through a double-humped fission barrier.

Kim, H. I.; Gil, C.-S.; Lee, Y.-O.

2010-03-01

385

Generalized x-ray scattering cross section from nonequilibrium plasmas.  

PubMed

We propose a modified x-ray form factor that describes the scattering cross section in warm dense matter valid for both the plasma and the solid (crystalline) state. Our model accounts for the effect of lattice correlations on the electron-electron dynamic structure, as well as provides a smooth transition between the solid and the plasma scattering cross sections. In addition, we generalize the expression of the dynamic structure in the case of a two-temperature system (with different electron and ion temperatures). This work provides a unified description of the x-ray scattering processes in warm and dense matter, as the one encountered in inertial confinement fusion, laboratory astrophysics, material science, and high-energy density physics and it can be used to verify temperature relaxation mechanisms in such environments. PMID:17025545

Gregori, G; Glenzer, S H; Landen, O L

2006-08-01

386

Evaluation of Neutron Resonance Cross Section Data at GELINA  

NASA Astrophysics Data System (ADS)

Over the last decade, the EC-JRC-IRMM, in collaboration with other institutes such as INRNE Sofia (BG), INFN Bologna (IT), ORNL (USA), CEA Cadarache (FR) and CEA Saclay (FR), has made an intense effort to improve the quality of neutron-induced cross section data in the resonance region. These improvements relate to both the infrastructure of the facility and the measurement setup, and the data reduction and analysis procedures. As a result total and reaction cross section data in the resonance region with uncertainties better than 0.5 % and 2 %, respectively, can be produced together with evaluated data files for both the resolved and unresolved resonance region. The methodology to produce full ENDF compatible files, including covariances, is illustrated by the production of resolved resonance parameter files for 241Am, Cd and W and an evaluation for 197Au in the unresolved resonance region.

Schillebeeckx, P.; Becker, B.; Capote, R.; Emiliani, F.; Guber, K.; Heyse, J.; Kauwenberghs, K.; Kopecky, S.; Lampoudis, C.; Massimi, C.; Mondelaers, W.; Moxon, M.; Noguere, G.; Plompen, A. J. M.; Pronyaev, V.; Siegler, P.; Sirakov, I.; Trkov, A.; Volev, K.; Zerovnik, G.

2014-05-01

387

Total Electron Scattering Cross Sections for Simple Perfluorocarbons  

NASA Astrophysics Data System (ADS)

Total electron scattering cross sections for CF4, C2F6 and C3F8 have been measured in the energy range between 1.25 eV and 3000 eV using a compact linear transmission apparatus. Electrons scattered into a narrow forward angular range that should be counted in the scattered one were estimated utilizing measured quantities. The present results for CF4 agree well with available data at low and high energies, while some discrepancies were seen at intermediate energies. Measured results for C2F6 and C3F8 were shown at high energies for the first time. Upper bound of the elastic cross sections for these molecules were estimated at electron energies higher than 20 eV.

Nishimura, Hiroyuki; Nishimura, Fumio; Nakamura, Yoshiharu; Okuda, Keisuke

2003-05-01

388

Boron nitride nanotubes with quadrangular cross sections: Density functional studies  

NASA Astrophysics Data System (ADS)

Density functional theory (DFT) calculations have been performed to investigate the availabilities and properties of boron nitride nanotubes (BNNTs) with quadrangular cross sections. To achieve the purposes, the original structure of a representative BNNT was individually decorated by the carbon and silicon atoms to make the C-BNNT and Si-BNNT models. The sp3 hybridizations were set for the C and Si atoms to make possible the formation of the quadrangular cross sections for the BNNTs. The optimized results indicated that the investigated models could be stabilized; however, they showed different properties. The atomic scale properties based on computations of quadrupole coupling constants (CQ) also approved different properties for the C-BNNT and Si-BNNT models. Moreover, the CQ parameters indicated that the properties of C-BNNT could be considered similar to the original BNNT; however, more discrepancies were observed for the Si-BNNT.

Mirzaei, Mahmoud; Yousefi, Mohammad

2012-10-01

389

On the Wong cross section and fusion oscillations  

E-print Network

We re-examine the well-known Wong formula for heavy-ion fusion cross sections. Although this celebrated formula yields almost exact results for single-channel calculations for relatively heavy systems such as $^{16}$O+$^{144}$Sm, it tends to overestimate the cross section for light systems such as $^{12}$C+$^{12}$C. We generalise the formula to take account of the energy dependence of the barrier parameters and show that the energy-dependent version gives results practically indistinguishable from a full quantal calculation. We then examine the deviations arising from the discrete nature of the intervening angular momenta, whose effect can lead to an oscillatory contribution to the excitation function. We recall some compact, analytic expressions for these oscillations, and highlight the important physical parameters that give rise to them. Oscillations in symmetric systems are discussed, as are systems where the target and projectile identities can be exchanged via a strong transfer channel.

N. Rowley; K. Hagino

2015-03-26

390

Elastic breakup cross sections of well-bound nucleons  

E-print Network

The 9Be(28Mg,27Na) one-proton removal reaction with a large proton separation energy of Sp(28Mg)=16.79 MeV is studied at intermediate beam energy. Coincidences of the bound 27Na residues with protons and other light charged particles are measured. These data are analyzed to determine the percentage contributions to the proton removal cross section from the elastic and inelastic nucleon removal mechanisms. These deduced contributions are compared with the eikonal reaction model predictions and with the previously measured data for reactions involving the re- moval of more weakly-bound protons from lighter nuclei. The role of transitions of the proton between different bound single-particle configurations upon the elastic breakup cross section is also quantified in this well-bound case. The measured and calculated elastic breakup fractions are found to be in good agreement.

K. Wimmer; D. Bazin; A. Gade; J. A. Tostevin; T. Baugher; Z. Chajecki; D. Coupland; M. A. Famiano; T. K. Ghosh; G. F. Grinyer M. E. Howard; M. Kilburn; W. G. Lynch; B. Manning; K. Meierbachtol; P. Quarterman; A. Ratkiewicz; A. Sanetullaev; R. H. Showalter; S. R. Stroberg; M. B. Tsang; D. Weisshaar; J. Winkelbauer; R. Winkler; M. Youngs

2014-12-07

391

Neutron Capture Cross Sections of 236U and 234U  

SciTech Connect

Accurate neutron capture cross sections of the actinide elements at neutron energies up to 1 MeV are needed to better interpret archived nuclear test data, for post-detonation nuclear attribution, and the Advanced Fuel Cycle Initiative. The Detector for Advance Neutron Capture Experiments, DANCE, has unique capabilities that allow the differentiation of capture gamma rays from fission gamma rays and background gamma rays from scattered neutrons captured by barium isotopes in the barium fluoride scintillators. The DANCE array has a high granularity, 160 scintillators, high efficiency, and nearly 4-{pi} solid angle. Through the use of cuts in cluster multiplicity and calorimetric energy the capture gamma-rays are differentiated from other sources of gamma rays. The preliminary results for the capture cross sections of 236U are in agreement with the ENDF/B-VI evaluation. The preliminary results for 234U lower are than ENDF/B-VI evaluation and are closer to older evaluations.

Rundberg, R. S.; Bredeweg, T. A.; Bond, E. M.; Haight, R. C.; Hunt, L. F.; O'Donnell, J. M.; Schwantes, J. M.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Wouters, J. M. [Los Alamos National Laboratory (United States); Kronenberg, A. [Oak Ridge National Laboratory (United States)

2006-03-13

392

Absolute measurements of chlorine Cl+ cation single photoionization cross section  

NASA Astrophysics Data System (ADS)

The photoionization of Cl+ leading to Cl2+ was measured in the photon energy range of 19.5-28.0 eV. A spectrum with a photon energy resolution of 15 meV normalized to absolute cross-section measurements is presented. The measurements were carried out by merging a Cl+ ion beam with a photon beam of highly monochromatic synchrotron radiation at the Advanced Light Source at Lawrence Berkeley National Laboratory. The measured photoionization of Cl+ consists of several autoionization resonances surperimposed on the direct photoionization signal. Most of the prominent resonances are assigned to members of Rydberg series originating from the singlet ground state and from metastable triplet levels within the ground-state configuration of Cl+. The direct ionization cross section is no larger than 12 Mb.

Hernández, E. M.; Juárez, A. M.; Kilcoyne, A. L. D.; Aguilar, A.; Hernández, L.; Antillón, A.; Macaluso, D.; Morales-Mori, A.; González-Magaña, O.; Hanstorp, D.; Covington, A. M.; Davis, V.; Calabrese, D.; Hinojosa, G.

2015-01-01

393

Calculation of the cross section for top quark production  

SciTech Connect

The authors summarize calculations of the cross section for top quark production at hadron colliders within the context of perturbative quantum chromodynamics, including resummation of the effects of initial-state soft gluon radiation to all orders in the strong coupling strength. In their approach they resume the universal leading-logarithm contributions, and they restrict the calculation to the region of phase space that is demonstrably perturbative. They compare the approach with other methods. They present predictions of the physical cross section as a function of the top quark mass in proton-antiproton reactions at center-of-mass energies of 1.8 and 2.0 TeV, and they discuss estimated uncertainties.

Berger, E.L.; Contopanagos, H. [Argonne National Lab., IL (United States). High Energy Physics Div.

1996-06-21

394

Improved neutron capture cross section of Pu239  

NASA Astrophysics Data System (ADS)

The 239Pu(n ,?) cross section has been measured over the energy range 10 eV to 1 keV using the Detector for Advanced Neutron Capture Experiments (DANCE) at the Los Alamos Neutron Science Center as part of a campaign to produce precision (n ,?) measurements on 239Pu. Fission coincidences were measured with a parallel-plate avalanche counter and used to measure the prompt fission ?-ray spectrum in this region to accurately characterize background. The resulting (n ,?) cross section is generally in agreement with current evaluations. The experimental method utilizes much more detailed information than past measurements on 239Pu and can be used to extend the measurement to higher incident neutron energies.

Mosby, S.; Bredeweg, T. A.; Chyzh, A.; Couture, A.; Henderson, R.; Jandel, M.; Kwan, E.; O'Donnell, J. M.; Ullmann, J.; Wu, C. Y.

2014-03-01

395

Impact dynamics of granular jets with noncircular cross sections.  

PubMed

Using high-speed photography, we investigate two distinct regimes of the impact dynamics of granular jets with noncircular cross sections. In the steady-state regime, we observe the formation of thin granular sheets with anisotropic shapes and show that the degree of anisotropy increases with the aspect ratio of the jet's cross section. Our results illustrate the liquidlike behavior of granular materials during impact and demonstrate that a collective hydrodynamic flow emerges from strongly interacting discrete particles. We discuss the analogy between our experiments and those from the Relativistic Heavy Ion Collider, where similar anisotropic ejecta from a quark-gluon plasma have been observed in heavy-ion impact. PMID:24827235

Cheng, Xiang; Gordillo, Leonardo; Zhang, Wendy W; Jaeger, Heinrich M; Nagel, Sidney R

2014-04-01

396

German Radar Observation Shuttle Experiment (ROSE)  

NASA Technical Reports Server (NTRS)

The success of radar sensors in several different application areas of interest depends on the knowledge of the backscatter of radar waves from the targets of interest, the variance of these interaction mechanisms with respect to changing measurement parameters, and the determination of the influence of he measuring systems on the results. The incidence-angle dependency of the radar cross section of different natural targets is derived. Problems involved by the combination of data gained with different sensors, e.g., MSS-, TM-, SPOTand SAR-images are analyzed. Radar cross-section values gained with ground-based radar spectrometers and spaceborne radar imaging, and non-imaging scatterometers and spaceborne radar images from the same areal target are correlated. The penetration of L-band radar waves into vegetated and nonvegetated surfaces is analyzed.

Sleber, A. J.; Hartl, P.; Haydn, R.; Hildebrandt, G.; Konecny, G.; Muehlfeld, R.

1984-01-01

397

ACTIVIA: Calculation of Isotope Production Cross-sections and Yields  

E-print Network

We present a C++ computer package, ACTIVIA, that can calculate target-product cross-sections and the production and decay yields of isotopes from cosmic ray activation using data tables and semi-empirical formulae. We describe the structure and user interface of the computer code as well as provide comparisons between the calculations and experimental results. We also outline suggestions on how the code can be improved and extended for other applications.

J. J. Back; Y. A. Ramachers

2008-01-15

398

Differential collision cross-sections for atomic oxygen  

NASA Technical Reports Server (NTRS)

Differential collision cross-sections of O on N2 and other gases were measured to understand vehicle-environmental contamination effects in orbit. The following subject areas are also covered: groundbased scientific observations of rocket releases during NICARE-1; data compression study for the UVI; science priorities for UV imaging in the mid-1990's; and assessment of optimizations possible in UV imaging systems.

Torr, Douglas G.

1991-01-01

399

Neutron Cross-Section Measurements on Structural Materials at ORELA  

SciTech Connect

Neutron capture experiments, using isotopically enriched and natural samples of chromium and titanium, were performed on flight paths 6 and 7 at the 40 m flight station of ORELA. The experimental data were acquired using a pair of deuterated benzene detectors employing the now well-established pulse-height-weighting technique. These data were complemented by new total cross-section measurements where no useful previous data were available.

Guber, Klaus H [ORNL] [ORNL; Koehler, Paul [ORNL] [ORNL; Wiarda, Dorothea [ORNL] [ORNL; Harvey, John A [ORNL] [ORNL

2011-01-01

400

Total electron scattering cross sections. I - He, Ne, Ar, Xe  

NASA Technical Reports Server (NTRS)

The apparatus and experimental procedures used to obtain total electron scattering cross sections are described, and results are presented for He, Ne, Ar and Xe in the 4-300 eV incident energy range, together with statistical errors. The results are generally found to be in good agreement with previous data except at low impact energies. Serious discrepancies remain in Xe below 20 eV impact energy.

Nickel, J. C.; Imre, K.; Register, D. F.; Trajmar, S.

1985-01-01

401

Top quark pair production cross section at the Tevatron  

SciTech Connect

Top quark pair production cross section has been measured at the Tevatron by CDF and D0 collaborations using different channels and methods, in order to test standard model predictions, and to search for new physics hints affecting the t{bar t} production mechanism or decay. Measurements are carried out with an integrated luminosity of 1.0 to 2.0 fb{sup -1}, and are found to be consistent with standard model expectations.

Cortiana, Giorgio; /INFN, Padua /Padua U.

2008-04-01

402

Stellar neutron capture cross sections of the Gd isotopes  

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of 152Gd, 154Gd, 155Gd, 156Gd, 157Gd, and 158Gd were measured in the energy range from 3 to 225 keV at the Karlsruhe 3.75 MV Van de Graaff accelerator. Neutrons were produced via the 7Li(p,n)7Be reaction by bombarding metallic Li targets with a pulsed proton beam. Capture events were registered with the Karlsruhe 4? Barium Fluoride Detector, which was improved by replacing crystals with high ? background and by introducing a pierced crystal at zero degrees with respect to the beam axis. These changes resulted in a significantly increased efficiency for capture events. The main experimental problem was that the samples of the two s isotopes 152Gd and 154Gd showed only relatively low enrichment. Nevertheless, the spectroscopic quality of the BaF2 detector allowed evaluation of the corresponding corrections for isotopic impurities reliably. The cross section ratios could be determined with an overall uncertainty of typically 1%, an improvement by factors of five to ten compared to existing data. Severe discrepancies were found with respect to previous results. Maxwellian averaged neutron capture cross sections were calculated for thermal energies between kT=10 keV and 100 keV. The new stellar cross sections were used for an updated analysis of the s-process reaction flow in the mass region between samarium and gadolinium, which is characterized by branchings at 151Sm, 154Eu, and 155Eu. With the classical approach, the s-process temperature could be constrained corresponding to a range of thermal energies between kT=28 and 33 keV. The 152Gd production in low mass stars was found to depend strongly on the neutron freeze-out at the end of the helium shell burning episodes.

Wisshak, K.; Voss, F.; Käppeler, F.; Guber, K.; Kazakov, L.; Kornilov, N.; Uhl, M.; Reffo, G.

1995-11-01

403

Stellar neutron capture cross sections of the Gd isotopes.  

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of 152Gd, 154Gd, 155Gd, 156Gd, 157Gd, and 158Gd were measured in the energy range from 3 to 225 keV at the Karlsruhe 3.75 MV Van de Graaff accelerator. Neutrons were produced via the 7Li(p, n)7Be reaction by bombarding metallic Li targets with a pulsed proton beam. Capture events were registered with the Karlsruhe 4? Barium Fluoride Detector The main experimental problem was that the samples of the two s-only isotopes 152Gd and 154Gd showed only relatively low enrichment, but the spectroscopic quality of the BaF2 detector allowed to determine the resulting corrections for isotopic impurities reliably. The cross section ratios could be determined with an overall uncertainty of typically 1%, an improvement by factors of five to ten compared to existing data. Severe discrepancies were found with respect to previous results. Maxwellian averaged neutron capture cross sections were calculated for thermal energies between kT = 10 keV and 100 keV. The new stellar cross sections were used for an updated analysis of the s-process reaction flow in the mass region between samarium and gadolinium, which is characterized by branchings at 151Sm, 154Eu, and 155Eu. With the classical approach, the s-process temperature could be constrained corresponding to a range of thermal energies between kT - 28 keV and 33 keV. The 152Gd production in low mass stars was found to depend strongly on the neutron freeze-out at the end of the helium shell burning episodes.

Wisshak, K.; Voss, F.; Käppeler, F.; Guber, K.; Kazakov, L.; Kornilov, N.; Uhl, M.; Reffo, G.

1995-05-01

404

The PhotoIonization Cross Section of Methane  

Microsoft Academic Search

The photo-ionization cross section of methane is calculated using self-consistent wave functions. The value at the spectral head (105 850 cm-1) is found to be 9.4×10-17 cm2. An approximate general formula is employed to obtain results in a wave number range up to 200 000 cm-1 and the associated oscillator strength is computed. It is pointed out that exchange effects

A. Dalgarno

1952-01-01

405

PhotoIonization Cross Section of Beryllium near Threshold  

Microsoft Academic Search

The 1P continuum wave functions of beryllium with energies from 0 to ~3.5 eV above the 2s threshold are calculated with the inclusion of auto-ionizing lines by configuration interaction. These functions are then combined with a ten-configuration ground-state function to compute the photo-ionization cross section which is found to be dominated by auto-ionization from the 2pns and the 2pnd series.

P. L. Altick

1968-01-01

406

Neutron-Induced Cross Sections Measurements of Calcium  

SciTech Connect

To support the US Department of Energy Nuclear Criticality Safety Program neutron induced cross section experiments were performed at the Geel Electron Linear Accelerator of the Institute for Reference Material and Measurements of the Joint Research Centers, European Union. Neutron capture and transmission measurements were carried out using a metallic calcium sample. The obtained data will be used for a new calcium evaluation, which will be submitted with its covariances to the ENDBF/B nuclear data base.

Guber, Klaus H [ORNL; Kopecky, S. [EC-JRC-IRMM, Geel, Belgium; Schillebeeckx, P. [EC-JRC-IRMM, Geel, Belgium; Kauwenberghs, K. [EC-JRC-IRMM, Geel, Belgium; Siegler, P. [EC-JRC-IRMM, Geel, Belgium

2013-01-01

407

29. Photograph of a line drawing. 'CROSS SECTION AND PLAN ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

29. Photograph of a line drawing. 'CROSS SECTION AND PLAN LAYOUT OF PART I, SECTION 8, BUILDINGS NO. D-1 TO D-10 INCL., NITRATION, MANUFACTURING AREA, PLANT B AS OF 4-24-44.' From the U.S. Army Corps of Engineers. Industrial Facilities Inventory, Holston Ordnance Works, Kingsport, Tennessee. Plant B, Parts II, III. (Nashville, TN: Office of the District Engineer, 1944). - Holston Army Ammunition Plant, RDX-and-Composition-B Manufacturing Line 9, Kingsport, Sullivan County, TN

408

35. Photograph of a line drawing. 'CROSS SECTION OF PART ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

35. Photograph of a line drawing. 'CROSS SECTION OF PART III, SECTION 1, EQUIPMENT LAYOUT, BUILDINGS E-1 TO E-10 INCL., WASHING, MANUFACTURING AREA, PLANT 'B'.' From the U.S. Army Corps of Engineers. Industrial Facilities Inventory, Holston Ordnance Works, Kingsport, Tennessee. Plant B, Parts II, III. (Nashville, TN: Office of the District Engineer, 1944). - Holston Army Ammunition Plant, RDX-and-Composition-B Manufacturing Line 9, Kingsport, Sullivan County, TN

409

30. Photograph of a line drawing. 'CROSS SECTION OF PART ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

30. Photograph of a line drawing. 'CROSS SECTION OF PART III, SECTION 1, EQUIPMENT LAYOUT, BUILDINGS D-1 TO D-10 INCL., NITRATION, MANUFACTURING AREA, PLANT 'B'.' From U.S. Army Corps of Engineers. Industrial Facilities Inventory, Holston Ordnance Works, Kingsport, Tennessee. Plant B, Parts II, III. (Nashville, TN: Office of the District Engineer, 1944). - Holston Army Ammunition Plant, RDX-and-Composition-B Manufacturing Line 9, Kingsport, Sullivan County, TN

410

34. Photograph of a line drawing. 'CROSS SECTION AND PLAN ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

34. Photograph of a line drawing. 'CROSS SECTION AND PLAN LAYOUT OF PART I, SECTION B, BUILDINGS NO. E-1 TO E-10 INCL., WASHING, MANUFACTURING AREA, PLANT B AS OF 4-24-44.' From the U.S. Army Corps of Engineers. Industrial Facilities Inventory, Holston Ordnance Works, Kingsport, Tennessee. Plant B, Parts II, III. (Nashville, TN: Office of the District Engineer, 1944). - Holston Army Ammunition Plant, RDX-and-Composition-B Manufacturing Line 9, Kingsport, Sullivan County, TN

411

42. Photograph of a line drawing. 'CROSS SECTION AND PLAN ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

42. Photograph of a line drawing. 'CROSS SECTION AND PLAN LAYOUT OF PART I, SECTION 8, BUILDINGS NO. H-1 TO H-10 INCL., GRINDING, MANUFACTURING AREA, PLANT B AS OF 4-24-44.' From the U.S. Army Corps of Engineers. Industrial Facilities Inventory, Holston Ordnance Works, Kingsport, Tennessee. Plant B, Parts II, III. (NashVille, TN: Office of the District Engineer, 1944). - Holston Army Ammunition Plant, RDX-and-Composition-B Manufacturing Line 9, Kingsport, Sullivan County, TN

412

Induced-emission cross sections in neodymium laser glasses  

Microsoft Academic Search

A method for calculating induced-emission cross sections in neodymium laser glasses, based on simple absorbance measurements, has been demonstrated. Absorption and emission transition probabilities of four silicate-base neodymium laser glasses have been characterized in terms of the Judd-Ofelt (JO) model of crystal-field-induced electric-dipole transitions. Absolute absorption intensities in 3669A, ED-2, LSG-91H, and S33 glasses were measured and used to determine

WILLIAM F. KRUPKE

1974-01-01

413

Structure Function Measurements and Polarised Cross Section Measurements from HERA  

E-print Network

Recent measurements of inclusive and semi-inclusive measurements from the HERA collaborations are presented. The measurements include neutral current structure functions $F_2$, $F_L$ and $xF_3$; the charged current cross section including first measurements of the dependence on electron polarisation; and measurements of the heavy quark structure functions $F_2^{c\\bar{c}}$ and $F_2^{b\\bar{b}}$.

Andrew Mehta

2004-11-10

414

Cross-section of : Inhomogeneous Big Bang nucleosynthesis  

Microsoft Academic Search

The cross-section of 8 Li( $\\\\alpha $ ,n) 11 B has been measured at $E_{\\\\rm cm}$ = 1.25 MeV to be $\\\\sigma (E) = 500$ mb using novel techniques, i.e. a 8 Li radioactive ion beam produced at the tandem in Catania in combination with a 4 He gas cell and a $4\\\\pi $ neutron detector. The value is in

S. Cherubini; P. Figuera; A. Musumarra; C. Agodi; R. Alba; L. Calabretta; L. Cosentino; A. Del Zoppo; A. Di Pietro; M. La Cognata; L. Lamia; L. Pappalardo; M. G. Pellegriti; R. G. Pizzone; A. Rinollo; C. Rolfs; S. Romano; C. Spitaleri; F. Strieder; S. Tudisco; A. Tumino

2004-01-01

415

Negative ion detachment cross sections. Interim progress report  

SciTech Connect

The authors have measured absolute cross sections for electron detachment and charge exchange for collision of O and S with atomic hydrogen, have investigated the sputtering and photodesorption of negative ions from gas covered surfaces, and have begun an investigation of photon-induced field emission of electrons from exotic structures. Brief descriptions of these activities as well as future plans for these projects are given below.

Champion, R.L.; Doverspike, L.D.

1992-10-01

416

Neutron-induced Cross Section Measurements of Calcium  

NASA Astrophysics Data System (ADS)

To support the US Department of Energy Nuclear Criticality Safety Program, neutron-induced cross section experiments were performed at the Geel Electron Linear Accelerator of the Institute for Reference Material and Measurements of the Joint Research Centers, European Union. Neutron capture and transmission measurements were carried out using a metallic calcium sample. The measured data will be used for a new calcium evaluation, which will be submitted with covariances to the ENDF/B nuclear data library.

Guber, K.; Kopecky, S.; Schillebeeckx, P.; Kauwenberghs, K.; Siegler, P.

2014-05-01

417

Workshop on a Cross Section of Archean Crust  

NASA Technical Reports Server (NTRS)

Various topics relevant to crustal genesis, especially the relationship between Archean low - and high-grade terrains, were discussed. The central Superior Province of the Canadian Shield was studied. Here a 120 km-wide transition from subgreenschist facies rocks of the Michipicoten greenstone belt to granulite facies rocks of the Kapuskasing structural zone represents an oblique cross section through some 20 km of crust, uplifted along a northwest-dipping thrust fault.

Ashwal, L. D. (editor); Card, K. D. (editor)

1983-01-01

418

Humeral cross-sectional shape in suspensory primates and sloths.  

PubMed

Studies on the cross-sectional geometry of long bones in African apes have documented that shape ratios derived from second moments of area about principle axes (e.g., Imax /Imin ) are often correlated with habitual locomotor behaviors. For example, humeral cross-sections tend to appear more circular in more arboreal and forelimb suspensory chimpanzees compared with terrestrial quadrupedal gorillas. These data support the hypothesis that cross-sections that are more circular in shape are adapted for multidirectional loading regimes and bending moments encountered when using acrobatic locomotor behaviors. Whether a more circular humerus reflects greater use of forelimb suspension in other primates and nonprimate mammals is unknown. In this study, cross-sections at or near midshaft of the humerus were obtained from anthropoid primates that differ in their use of forelimb suspension, as well as from two genera of suspensory sloths. Imax /Imin ratios were compared within and between groups, and correlations were made with behavioral data. In broad comparisons, observed differences in morphology follow predicted patterns. Humeri of suspensory sloths are circular. Humeri of the more suspensory hominoids tend to be more circular than those of quadrupedal taxa. Humeri of the suspensory atelines are similar to hominoids, while those of Cebus are more like nonsuspensory cercopithecoids. There is, however, considerable overlap between taxa and within finer comparisons variation between species are not in the predicted direction. Thus, although Imax /Imin ratios of the humerus are informative for characterizing generalized locomotor modes (i.e., forelimb suspensory vs. quadrupedal), additional structural information is needed for more fine-grained assessments of locomotion. PMID:23408647

Patel, Biren A; Ruff, Christopher B; Simons, Erin L R; Organ, Jason M

2013-04-01

419

Analysis of charged-current neutrino-nucleus cross section  

SciTech Connect

A study of the cross section for chaged-current quasielastic (CCQE) scattering on nuclei has been performed using a description of nuclear dynamics based on the Relativistic Fermi Gas model (RFG). The role played by different parametrizations for the weak nucleon form factors is analyzed taking into account the relevance of the axial mass value. The results obtained are compared with the recent data for neutrinos measured by the MiniBooNE Collaboration.

Megias, G.; Caballero, J. A. [Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Sevilla, 41080 Sevilla (Spain)

2013-06-10

420

Measuring the JPsi-Nucleon dissociation cross section with PANDA  

E-print Network

With the PANDA detector at the HESR at FAIR it will be possible to study the production and absorption of charmed hadrons in nuclear targets. Of special interest in this context is the determination of the JPsi-nucleon dissociation cross section. This can be determined with measurements of the JPsi yield in antiproton-nucleus reactions using different target materials. The experiment is described and numerical simulations are presented.

Paul Bühler

2011-09-18

421

Cross-section curvature effect in plasmonic ring lasers  

NASA Astrophysics Data System (ADS)

Nanolasers have shown their potential in optical communication and information storage, due to their tiny footprint, potential high modulation rate and light spot under diffraction limit. In recent years, many structures use metal as whole or part of the cavity to achieve light confinement at subwavelength scale. In this paper, we propose and compare two novel types of hybrid plasmonic lasers, both with an ultrathin insulator layer sandwiched by a ring shape semiconductor and planar silver layer. The lasers differ in their cross-section curvature on the interface of metal and insulator. Finite difference time domain (FDTD) method is used to calculate and optimize these two ring laser structures. The resonant wavelength is set around 490 nm. The ultrathin thickness of the insulator layer makes photonic modes hybridize with surface plasmon plaritons (SPPs) at Ag-insulator interface, which confines the light field strongly in the ultrathin layer. The SPPs carry high momentum and high effective refractive index to TM mode. Whispering gallery mode is achieved according to strong feedback at the ring boundary by total internal reflection. The ring lasers have relatively high Q factors, approaching 100, at 250 nm radius and mode confinement around ?2/360. The mode volume can be shrunk to 0.1(?/n)3 and 0.01(?/n)3 respectively, which leads to Purcell factors around 70 for square cross-section and 380 for circle cross-section. We discuss the curvature effects on the mode volume and on the quality factor which accounts for the high Purcell factor for the circle cross-section.

Shi, Feifei; Liu, Xudong; Gong, Xin; Zhang, Zhaoyu

2013-09-01

422

Neutrino and Antineutrino Cross sections at MiniBooNE  

SciTech Connect

The MiniBooNE experiment has reported a number of high statistics neutrino and anti-neutrino cross sections -among which are the charged current quasi-elastic (CCQE) and neutral current elastic (NCE) neutrino scattering on mineral oil (CH2). Recently a study of the neutrino contamination of the anti-neutrino beam has concluded and the analysis of the anti-neutrino CCQE and NCE scattering is ongoing.

Dharmapalan, Ranjan; /Alabama U.

2011-10-01

423

Quality of pharmacies in Pakistan: a cross-sectional survey  

Microsoft Academic Search

Objective. To estimate the proportion of pharmacies meeting licensing requirements and to identify factors associated with these pharmacies in urban Rawalpindi, Pakistan. Design. Cross-sectional questionnaire survey conducted during July-September 2001, of 311 pharmacies selected from a drug company list of 506. Setting. Free-standing licensed and unlicensed pharmacies in urban Rawalpindi. Study participants. A pharmacist or (if unavailable) the most experienced

ZAHID A. BUTT; ANWAR H. GILANI; DEBRA NANAN; ABDUL L. SHEIKH; FRANK WHITE

2005-01-01

424

Inclusive jet cross-section measurement at CDF  

SciTech Connect

The CDF Collaboration has measured the inclusive jet cross section using 1992-93 collider data at 1.8 TeV. The CDF measurement is in very good agreement with NLO QCD predictions for transverse energies (E{sub T}) below 200 GeV. However, it is systematically higher than NLO QCD predictions for E{sub T} above 200 GeV.

Norniella, Olga; /Barcelona, IFAE

2007-05-01

425

Top Quark Production Cross Section at the Tevatron  

SciTech Connect

An overview of the preliminary results of the top quark pair production cross section measurements at a center-of-mass energy of 1.96 TeV carried out by the CDF and D0 collaborations is presented. The data samples used for the analyses are collected in the current Tevatron run and correspond to an integrated luminosity from 360 pb{sup -1} up to 760 pb{sup -1}.

Shabalina, E.; /Chicago U.

2006-05-01

426

Stopping cross section measurements of Ti thin films  

Microsoft Academic Search

The stopping cross section for 4He projectiles of Ti thin films have been measured with the backscattering method using a multi-compound marker layer deposited between the test film and the substrate. Problems derived from the non-uniformity of the marker layer as well as corrugations of the films under test have been solved with the help of a computer code to

J. Räisänen; E. Rauhala

1998-01-01

427

Retrodeformable cross sections and Oak Ridge fault, Ventura basin, California  

Microsoft Academic Search

A retrodeformable (balanced) cross section is constructed such that stratified rocks are restored to their undeformed state without loss or gain of bed length or bed thickness. Ductile strata may be area-balanced if original thickness is known. Near Ventura, folds in Pliocene-Pleistocene turbidites and Miocene-early Pliocene shales (Rincon, Monterey, Sisquoc) overlie an unfolded competent Paleogene sequence. The basal decollement of

R. S. Yeats; G. F. Huftile

1988-01-01

428

Dielectronic-Recombination Cross-Sections of Hydrogenlike Argon  

E-print Network

PHYSICAL REVIEW A VOLUME 44, NUMBER 11 1 DECEMBER 1991 Dielectronic-recombination cross sections of hytlrogenlike argon D. R. DeWitt, D. Schneider, M. W. Clark, and M. H. Chen Latvrenee Livermore National Laboratory, University of California.... These trapped ions then undergo further ionization and other electron-ion 7185 1991 The American Physical Society DeWITT, SCHNEIDER, CLARK, CHEN, AND CHURCH interactions. In order to study dielectronic recombination in highly charged ions, the drift tubes...

Dewitt, D. R.; Schneider, D.; Clark, M. W.; Chen, M. H.; Church, David A.

1991-01-01

429

Cross-section data for selected Puerto Rico streams  

USGS Publications Warehouse

The data presented are for delineating the inundation which could be expected by floods of selected magnitudes in Puerto Rico. These cross section data can be used in Flood Insurance Administration studies and in other studies related to the planning, development, and management of flood plains. The data were collected by the Caribbean District of the Water Resources Division of the U.S. Geological Survey in cooperation with the Puerto Rico Department of Natural Resources. (Woodard-USGS)

Colon-Dieppa, Eloy; Gonzalez, Ralph

1978-01-01

430

Radial Eigenmodes for a Toroidal Waveguide with Rectangular Cross Section  

SciTech Connect

In applying mode expansion to solve the CSR impedance for a section of toroidal vacuum chamber with rectangular cross section, we identify the eigenvalue problem for the radial eigenmodes which is different from that for cylindrical structures. In this paper, we present the general expressions of the radial eigenmodes, and discuss the properties of the eigenvalues on the basis of the Sturm-Liouville theory.

Rui Li

2012-07-01

431

Study of Exotic Nuclear Structures via Total Reaction Cross Sections  

NASA Astrophysics Data System (ADS)

Nuclear radius is one of the most basic physical quantities to study unknown exotic nuclei. A number of radii for unstable nuclei were studied through measurements of interaction cross sections (?I) at high energies, using the Glauber-type calculation (Optical-Limit approximation (OLA) of Glauber theory) to investigate halo and skin structures of exotic nuclei. On the other hand, it was indicated that reaction cross sections (?R) at intermediate energies (from several tens to hundreds of MeV/nucleon) were more sensitive to dilute nucleon density distribution owing to large nucleon-nucleon total cross sections (?NN) compared to high-energy region. Recently, we developed a new method to deduce nucleon density distributions from the energy dependences of ? R, through the precise measurements of ? R for various nuclei and some modifications of Glauber-type calculation. Using this method, we studied nucleon density distributions of light nuclei by measuring ? R for those nuclei at HIMAC (Heavy ion Medical Accelerator in CHIBA), NIRS (National Institute of Radiological Sciences). And very recently, we deduced nuclear radii of neutron-rich Ne isotopes (^28-32Ne) which are in the island-of-inversion region by measuring ?I using BigRIPS at RIBF (RI Beam Factory) to study nuclear structures of those isotopes using our method. In this workshop, results of nucleon density distributions obtained at HIMAC and results of the studies of Ne isotopes at RIBF will be introduced and discussed.

Takechi, Maya

2009-10-01

432

CMB Constraints On The Thermal WIMP Annihilation Cross Section  

E-print Network

A thermal relic, often referred to as a weakly interacting massive particle (WIMP),is a particle produced during the early evolution of the Universe whose relic abundance (e.g., at present) depends only on its mass and its thermally averaged annihilation cross section (annihilation rate factor) sigma*v_ann. Late time WIMP annihilation has the potential to affect the cosmic microwave background (CMB) power spectrum. Current observational constraints on the absence of such effects provide bounds on the mass and the annihilation cross section of relic particles that may, but need not be dark matter candidates. For a WIMP that is a dark matter candidate, the CMB constraint sets an upper bound to the annihilation cross section, leading to a lower bound to their mass that depends on whether or not the WIMP is its own antiparticle. For a self-conjugate WIMP, m_min = 50f GeV, where f is an electromagnetic energy efficiency factor. For a non self-conjugate WIMP, the minimum mass is a factor of two larger. For a WIMP t...

Steigman, Gary

2015-01-01

433

Towards Reliable Cross Sections for National Security Applications  

SciTech Connect

Stockpile stewardship requires the description of weapons performance without resorting to underground nuclear testing. In the earlier tests, selected isotopes were used as detectors, and recovered after irradiation. Aspects of nuclear device performance were inferred by comparing the measured isotopic ratios to those predicted from simulations. The reaction flows that produce the final isotopic distributions proceed through regions of the nuclear chart that include unstable nuclei. Presently, improved nuclear data input is required to reanalyze prior tests and to certify the stockpile's reliability and safety. Many important cross sections are unknown, as is shown in the example of the Yttrium reaction network (Figure 1). The relevant reactions include (n,2n), (n,n'), (n,gamma), (n,p) and other charged-particle emitting reactions. The cross sections have to be calculated or inferred from indirect measurements. In both cases, reliable optical models that are valid a few nucleons away from stability are needed. The UNEDF Nuclear Reaction activities address this need by combining nuclear-structure input from UNEDF structure calculations with modern reaction theory and large-scale computational capabilities to develop microscopic nucleon-nucleus optical potentials that can be extrapolated to unstable nuclei. In addition, the reaction calculation tools and optical models developed in this context are proving valuable for planning and interpreting indirect (surrogate) measurements of the required cross sections.

Escher, J E; Dietrich, F S; Nobre, G A; Thompson, I J

2011-02-24

434

Three Dimensional Cross-Sectional Properties From Bone Densitometry  

NASA Technical Reports Server (NTRS)

Bone densitometry has previously been used to obtain cross-sectional properties of bone in a single scan plane. Using three non-coplanar scans, we have extended the method to obtain the principal area Moments of inertia and orientations of the principal axes at each cross-section along the length of the scan. Various 5 aluminum phantoms were used to examine scanner characteristics to develop the highest accuracy possible for in vitro non-invasive analysis of mass distribution. Factors considered included X-ray photon energy, initial scan orientation, the included angle of the 3 scans, and Imin/Imax ratios. Principal moments of inertia were accurate to within 3.1% and principal angles were within 1 deg. of the expected value for phantoms scanned with included angles of 60 deg. and 90 deg. at the higher X-ray photon energy. Low standard deviations in error also 10 indicate high precision of calculated measurements with these included angles. Accuracy and precision decreased slightly when the included angle was reduced to 30 deg. The method was then successfully applied to a pair of excised cadaveric tibiae. The accuracy and insensitivity of the algorithms to cross-sectional shape and changing isotropy (Imin/Imax) values when various included angles are used make this technique viable for future in vivo studies.

Cleek, Tammy M.; Whalen, Robert T.; Dalton, Bonnie P. (Technical Monitor)

2001-01-01

435

Froissart Bound on Inelastic Cross Section Without Unknown Constants  

E-print Network

Assuming that axiomatic local field theory results hold for hadron scattering, Andr\\'e Martin and S. M. Roy recently obtained absolute bounds on the D-wave below threshold for pion-pion scattering and thereby determined the scale of the logarithm in the Froissart bound on total cross sections in terms of pion mass only. Previously, Martin proved a rigorous upper bound on the inelastic cross-section $\\sigma_{inel}$ which is one-fourth of the corresponding upper bound on $\\sigma_{tot}$, and Wu, Martin,Roy and Singh improved the bound by adding the constraint of a given $\\sigma_{tot}$. Here we use unitarity and analyticity to determine, without any high energy approximation, upper bounds on energy averaged inelastic cross sections in terms of low energy data in the crossed channel. These are Froissart-type bounds without any unknown coefficient or unknown scale factors and can be tested experimentally. Alternatively, their asymptotic forms,together with the Martin-Roy absolute bounds on pion-pion D-waves below t...

Martin, André

2015-01-01

436

Summary of the Workshop on Neutron Cross Section Covariances  

SciTech Connect

A Workshop on Neutron Cross Section Covariances was held from June 24-27, 2008, in Port Jefferson, New York. This Workshop was organized by the National Nuclear Data Center, Brookhaven National Laboratory, to provide a forum for reporting on the status of the growing field of neutron cross section covariances for applications and for discussing future directions of the work in this field. The Workshop focused on the following four major topical areas: covariance methodology, recent covariance evaluations, covariance applications, and user perspectives. Attention was given to the entire spectrum of neutron cross section covariance concerns ranging from light nuclei to the actinides, and from the thermal energy region to 20 MeV. The papers presented at this conference explored topics ranging from fundamental nuclear physics concerns to very specific applications in advanced reactor design and nuclear criticality safety. This paper provides a summary of this workshop. Brief comments on the highlights of each Workshop contribution are provided. In addition, a perspective on the achievements and shortcomings of the Workshop as well as on the future direction of research in this field is offered.

Smith, Donald L. [Argonne National Laboratory, 1710 Avenida del Mundo, Coronado, California 92118-3073 (United States)], E-mail: Donald.L.Smith@anl.gov

2008-12-15

437

Hydraulic geometry of river cross sections; theory of minimum variance  

USGS Publications Warehouse

This study deals with the rates at which mean velocity, mean depth, and water-surface width increase with water discharge at a cross section on an alluvial stream. Such relations often follow power laws, the exponents in which are called hydraulic exponents. The Langbein (1964) minimum-variance theory is examined in regard to its validity and its ability to predict observed hydraulic exponents. The variables used with the theory were velocity, depth, width, bed shear stress, friction factor, slope (energy gradient), and stream power. Slope is often constant, in which case only velocity, depth, width, shear and friction factor need be considered. The theory was tested against a wide range of field data from various geographic areas of the United States. The original theory was intended to produce only the average hydraulic exponents for a group of cross sections in a similar type of geologic or hydraulic environment. The theory does predict these average exponents with a reasonable degree of accuracy. An attempt to forecast the exponents at any selected cross section was moderately successful. Empirical equations are more accurate than the minimum variance, Gauckler-Manning, or Chezy methods. Predictions of the exponent of width are most reliable, the exponent of depth fair, and the exponent of mean velocity poor. (Woodard-USGS)

Williams, Garnett P.

1978-01-01

438

Cross section of 36S(n,?)37S  

NASA Astrophysics Data System (ADS)

At the Karlsruhe pulsed 3.75 MV Van de Graaff accelerator the 36S(n,?)37S(5.05 min) cross section was measured by the fast cyclic activation technique via the 3.103 MeV ?-ray line of the 37S decay. Samples of elemental sulfur enriched in 36S by 5.933% were irradiated between two gold foils which served as capture standards. The capture cross section was measured at neutron energies 25, 151, 176, and 218 keV, respectively. The 36S(n,?)37S cross section in the thermonuclear and thermal energy range has been calculated using the direct-capture (DC) model combined with the folding procedure used for the determination of the potentials. The nonresonant experimental data for this reaction can be reproduced excellently using this method. The input parameters of the DC calculation (masses, Q values, nuclear density distributions, spectroscopic factors, spin-parity assignments, and excitation energies of the low-lying states of the residual nucleus) have been taken from the available experimental data.

Beer, H.; Sedyshev, P. V.; Popov, Yu. P.; Balogh, W.; Herndl, H.; Oberhummer, H.

1995-12-01

439

Edge-diffraction effects in RCS predictions and their importance in systems analysis  

NASA Astrophysics Data System (ADS)

In developing RCS prediction codes a variety of physical effects such as the edge diffraction effect have to be considered with the consequence that the computer effort increases considerably. This fact limits the field of application of such codes, especially if the RCS data serve as input parameters for system simulators which very often need these data for a high number of observation angles and/or frequencies. Vice versa the issues of a system analysis can be used to estimate the relevance of physical effects under system viewpoints and to rank them according to their magnitude. This paper tries to evaluate the importance of RCS predictions containing an edge diffracted field for systems analysis. A double dihedral with a strong depolarizing behavior and a generic airplane design containing many arbitrarily oriented edges are used as test structures. Data of the scattered field are generated by the RCS computer code SIGMA with and without including edge diffraction effects. These data are submitted to the code DORA to determine radar range and radar detectibility and to a SAR simulator code to generate SAR imagery. In both cases special scenarios are assumed. The essential features of the computer codes in their current state are described, the results are presented and discussed under systems viewpoints.

Friess, W. F.; Klement, D.; Ruppel, M.; Stein, Volker

1996-06-01

440

Measurement of molecular stopping cross sections of vaporous sulfur compounds and calculation of the atomic stopping cross section of sulfur  

NASA Astrophysics Data System (ADS)

The molecular stopping cross sections of hydrogen sulfide, methyl sulfide, methyl disulfide, carbon disulfide, ethylene sulfide, proplene sulfide, trimethylene sulfide, thiophene, and sulfur hexafluoride have beem measured for 0.3-2.0 MeV He+ ions. It is shown that the bond order correlation for the third period element sulfur is qualitatively in agreement with its second row counterpart, oxygen, but that the stopping cross-section dependence on bond order is considerably less (?5% in sulfur compared to ?17% in oxygen). In the energy region where the stopping contribution of the valence electrons is largest, the atomic stopping cross sections of sulfur for double-bonded, ring-structured, and single-bonded compounds decrease in the order eDB(S)?eRING(S)?eSB(S), a trend consistent with that observed for oxygen and carbon. The experimental results suggest a minimum d-orbital involvement in SF6 and reveal a lower peak energy Epeak and width d when S exists in the compound than when C, O, or F are present.

Olson, H. G.; Powers, D.

1981-02-01

441

From ZZ to ZH : How Low Can These Cross Sections Go or Everybody, Let's Cross Section Limbo!  

SciTech Connect

We report on two searches performed at the D0 detector at the Fermi National Laboratory. The first is a search for Z di-boson production with a theoretical cross section of 1.4 pb. The search was performed on 2.6 fb{sup -1} of data and contributed to the first observation of ZZ production at a hadron collider. The second is a search for a low mass Standard Model Higgs in 4.2 fb{sup -1} of data. The Higgs boson is produced in association with a Z boson where the Higgs decays hadronically and the Z decays to two leptons. The ZZ search was performed in both the di-electron and di-muon channels. For the ZH search, we will focus on the muonic decays where we expanded the traditional coverage by considering events in which one of the two muons fails the selection requirement, and is instead reconstructed as an isolated track. We consider Higgs masses between 100 and 150 GeV, with theoretical cross sections ranging from 0.17 to 0.042 pb, and set upper limits on the ZH production cross-section at 95% confidence level.

Strauss, Emanuel Alexandre; /SUNY, Stony Brook

2009-08-01

442

Hadronic Production of psi(2S) Cross section and Polarization  

SciTech Connect

The hadronic production cross section and the polarization of {psi}(2S) meson are measured by using the data from p{bar p} collisions at {radical}s = 1.96 TeV collected by the Collider Detector at Fermilab. The datasets used correspond to integrated luminosity of 1.1 fb{sup -1} and 800 pb{sup -1}, respectively. The decay {psi}(2S) {yields} {mu}{sup +}{mu}{sup -} is used to reconstruct {psi}(2S) mesons in the rapidity range |y({psi}(2S))| < 0.6. The coverage of the p{sub T} range is 2.0 GeV/c {le} p{sub T} ({psi}(2S)) < 30 GeV/c for the cross section analysis and pT {ge} 5 GeV/c for the polarization analysis. For events with p{sub T} ({psi}(2S)) > 2 GeV/c the integrated inclusive cross section multiplied by the branching ratio for dimuon decay is 3.17 {+-} 0.04 {+-} 0.28 nb . This result agrees with the CDF Run I measurement considering the increased center-of-mass energy from 1.8 TeV to 1.96 TeV. The polarization of the promptly produced {psi}(2S) mesons is found to be increasingly longitudinal as p{sub T} increases from 5 GeV/c to 30 GeV/c. The result is compared to contemporary theory models.

Chung, Kwangzoo; /Carnegie Mellon U.

2008-05-01

443

Constant cross section of loops in the solar corona  

NASA Astrophysics Data System (ADS)

Context. The corona of the Sun is dominated by emission from loop-like structures. When observed in X-ray or extreme ultraviolet emission, these million K hot coronal loops show a more or less constant cross section. Aims: In this study we show how the interplay of heating, radiative cooling, and heat conduction in an expanding magnetic structure can explain the observed constant cross section. Methods: We employ a three-dimensional magnetohydrodynamics (3D MHD) model of the corona. The heating of the coronal plasma is the result of braiding of the magnetic field lines through footpoint motions and subsequent dissipation of the induced currents. From the model we synthesize the coronal emission, which is directly comparable to observations from, e.g., the Atmospheric Imaging Assembly on the Solar Dynamics Observatory (AIA/SDO). Results: We find that the synthesized observation of a coronal loop seen in the 3D data cube does match actually observed loops in count rate and that the cross section is roughly constant, as observed. The magnetic field in the loop is expanding and the plasma density is concentrated in this expanding loop; however, the temperature is not constant perpendicular to the plasma loop. The higher temperature in the upper outer parts of the loop is so high that this part of the loop is outside the contribution function of the respective emission line(s). In effect, the upper part of the plasma loop is not bright and thus the loop actually seen in coronal emission appears to have a constant width. Conclusions: From this we can conclude that the underlying field-line-braiding heating mechanism provides the proper spatial and temporal distribution of the energy input into the corona - at least on the observable scales. Movies associated to Figs. 1 and 2 are available in electronic form at http://www.aanda.org

Peter, H.; Bingert, S.

2012-12-01

444

Propionaldehyde infrared cross-sections and band strengths  

NASA Astrophysics Data System (ADS)

The use of oxygenated biofuels reduces the greenhouse gas emissions; however, they also result in increased toxic aldehyde by-products, mainly formaldehyde, acetaldehyde, acrolein, and propionaldehyde. These aldehydes are carcinogenic and/or toxic and therefore it is important to understand their formation and destruction pathways in combustion and atmospheric systems. Accurate information about their infrared cross-sections and integrated strengths are crucially needed for development of quantitative detection schemes and modeling tools. Critical to the development of such diagnostics are accurate characterization of the absorption features of these species. In this study, the gas phase infrared spectra of propionaldehyde (also called propanal, CH3-CH2-CHO), a saturated three carbon aldehyde found in the exhaust emissions of biodiesel or diesel fuels, was studied using high resolution Fourier Transform Infrared (FTIR) spectroscopy over the wavenumber range of 750-3300 cm-1 and at room temperature 295 K. The absorption cross sections of propionaldehyde were recorded at resolutions of 0.08 and 0.096 cm-1 and at seven different pressures (4-33 Torr). The calculated band-strengths were reported and the integrated band intensity results were compared with values taken from the Pacific Northwest National Laboratory (PNNL) database (showing less than 2% discrepancy). The peak positions of the 19 different vibrational bands of propionaldehyde were also compared with previous studies taken at a lower resolution of 1 cm-1. To the best of our knowledge, the current FTIR measurements provide the first highest resolution infrared cross section data for propionaldehyde.

Köro?lu, Batikan; Loparo, Zachary; Nath, Janardan; Peale, Robert E.; Vasu, Subith S.

2015-02-01

445

Noncircular Cross Sections Could Enhance Mixing in Sprays  

NASA Technical Reports Server (NTRS)

A computational study has shown that by injecting drops in jets of gas having square, elliptical, triangular, or other noncircular injection cross sections, it should be possible to increase (relative to comparable situations having circular cross section) the entrainment and dispersion of liquid drops. This finding has practical significance for a variety of applications in which it is desirable to increase dispersion of drops. For example, in chemical-process sprays, increased dispersion leads to increases in chemical- reaction rates; in diesel engines, increasing the dispersion of drops of sprayed fuel reduces the production of soot; and in household and paint sprays, increasing the dispersion of drops makes it possible to cover larger surfaces. It has been known for some years that single-phase fluid jets that enter flow fields through noncircular inlets entrain more fluid than do comparable jets entering through circular inlets. The computational study reported here was directed in part toward determining whether and how this superior mixing characteristic of noncircular single phase jets translates to a similar benefit in cases of two-phase jets (that is, sprays). The study involved direct numerical simulations of single- and two-phase free jets with circular, elliptical, rectangular, square, and triangular inlet cross sections. The two-phase jets consisted of gas laden with liquid drops randomly injected at the inlets. To address the more interesting case of evaporating drops, the carrier gas in the jets was specified to be initially unvitiated by the vapor of the liquid chemical species and the initial temperature of the drops was chosen to be smaller than that of the gas. The mathematical model used in the study was constructed from the conservation equations for the two-phase flow and included complete couplings of mass, momentum, and energy based on thermodynamically self-consistent specification of the enthalpy, internal energy, and latent heat of vaporization of the vapor.

Bellan, Josette; Abdel-Hameed, Hesham

2003-01-01

446

Mass Spectra and Ion Collision Cross Sections of Hemoglobin  

NASA Astrophysics Data System (ADS)

Mass spectra of commercially obtained hemoglobin (Hb) show higher levels of monomer and dimer ions, heme-deficient dimer ions, and apo-monomer ions than hemoglobin freshly prepared from blood. This has previously been attributed to oxidation of commercial Hb. Further, it has been reported that that dimer ions from commercial bovine Hb have lower collision cross sections than low charge state monomer ions. To investigate these effects further, we have recorded mass spectra of fresh human Hb, commercial human and bovine Hb, fresh human Hb oxidized with H2O2, lyophilized fresh human Hb, fresh human Hb both lyophilized and chemically oxidized, and commercial human Hb oxidized with H2O2. Masses of ?-monomer ions of all hemoglobins agree with the masses expected from the sequences within 3 Da or better. Mass spectra of the ? chains of commercial Hb and oxidized fresh human Hb show a peak or shoulder on the high mass side, consistent with oxidation of the protein. Both commercial proteins and oxidized fresh human Hb produce heme-deficient dimers with masses 32 Da greater than expected and higher levels of monomer and dimer ions than fresh Hb. Lyophilization or oxidation of Hb both produce higher levels of monomer and dimer ions in mass spectra. Fresh human Hb, commercial human Hb, commercial bovine Hb, and oxidized commercial human Hb all give dimer ions with cross sections greater than monomer ions. Thus, neither oxidation of Hb or the difference in sequence between human and bovine Hb make substantial differences to cross sections of ions.

Kang, Yang; Terrier, Peran; Douglas, D. J.

2011-02-01

447

Iodine Molecules Differential Absorption Cross section Lidar Studies  

NASA Astrophysics Data System (ADS)

Lidar monitoring of the gaseous molecules in atmosphere can be used for concentration measurements of the toxic pollutants in air of the urban and industrial regions. Such a concentration study in the multi-components gaseous mixture by lidar technique is a complex problem in atmospheric pollution monitoring. The differential absorption lidar (DA-lidar) is the most preferable for the detection of iodine molecules at very low concentration levels. The iodine molecules absorption cross section in the laboratory lidar studies and lidar equation simulation in this lidar variant corresponds with earlier data.

Privalov, V. E.; Shemanin, V. G.; Voronina, E. I.

2010-01-01

448

3He Spin-Dependent Cross Sections and Sum Rules  

SciTech Connect

We present a measurement of the spin-dependent cross sections for the \\vec{^3He}(\\vec{e},e')X} reaction in the quasielastic and resonance regions at four-momentum transfer 0.1 < Q^2< 0.9 GeV^2. The spin-structure functions have been extracted and used to evaluate the nuclear Burkhardt--Cottingham and extended GDH sum rules for the first time. Impulse approximation and exact three-body Faddeev calculations are also compared to the data in the quasielastic region.

Slifer, Karl; Amaryan, Moscov; Amaryan, Moskov; Auerbach, Leonard; Averett, Todd; Berthot, J.; Bertin, Pierre; Bertozzi, William; Black, Tim; Brash, Edward; Brown, D.; Burtin, Etienne; Calarco, John; Cates, Gordon; Chai, Zhengwei; Chen, Jian-Ping; Choi, Seonho; Chudakov, Eugene; Ciofi, Claudio; Cisbani, Evaristo; De Jager, Cornelis; Deur, Alexandre; DiSalvo, R.; Dieterich, Sonja; Djawotho, Pibero; Finn, John; Fissum, Kevin; Fonvieille, Helene; Frullani, Salvatore; Gao, Haiyan; Gao, Juncai; Garibaldi, Franco; Gasparian, Ashot; Gilad, Shalev; Gilman, Ronald; Glamazdin, Oleksandr; Glashausser, Charles; Glockle, W.; Golak, J.; Goldberg, Emma; Gomez, Javier; Gorbenko, Viktor; Hansen, Jens-Ole; Hersman, F.; Holmes, Richard; Huber, Garth; Hughes, Emlyn; Humensky, Thomas; Incerti, Sebastien; Iodice, Mauro; Jensen, S.; Jiang, Xiaodong; Jones, C.; Jones, G.; Jones, Mark; Jutier, Christophe; Kamada, H.; Ketikyan, Armen; Kominis, Ioannis; Korsch, Wolfgang; Kramer, Kevin; Kumar, Krishna; Kumbartzki, Gerfried; Kuss, Michael; Lakuriqi, Enkeleida; Laveissiere, Geraud; LeRose, John; Liang, Meihua; Liyanage, Nilanga; Lolos, George; Malov, Sergey; Marroncle, Jacques; McCormick, Kathy; McKeown, Robert; Meziani, Zein-Eddine; Michaels, Robert; Mitchell, Joseph; Nogga, Andreas; Pace, Emanuele; Papandreou, Zisis; Pavlin, Tina; Petratos, Gerassimos; Pripstein, David; Prout, David; Ransome, Ronald; Roblin, Yves; Rowntree, David; Rvachev, Marat; Sabatie, Franck; Saha, Arunava; Salme, Giovanni; SCOPETTA, S.; Skibinski, R.; Souder, Paul; Saito, Teijiro; Strauch, Steffen; Suleiman, Riad; Takahashi, Kazunori; Todor, Luminita; Tsubota, Hiroaki; Ueno, Hiroaki; Urciuoli, Guido; van der Meer, Rob; Vernin, Pascal; Voskanyan, Hakob; Witala, Henryk; Wojtsekhowski, Bogdan; Xiong, Feng; Xu, Wang; Yang, Jae-Choon; Zhang, Bin; Zolnierczuk, Piotr

2008-07-01

449

Neutron cross section standards evaluations for ENDF/B-VI  

SciTech Connect

The neutron cross section standards are now being evaluated as the initial phase in the development of the new ENDF/B-VI file. These standards evaluations are following a somewhat different process compared with that used for earlier versions of ENDF. The primary effort is concentrated on a simultaneous evaluation using a generalized least squares program, R-matrix evaluations, and a procedure for combining the results of these evaluations. The ENDF/B-VI standards evaluation procedure is outlined, and preliminary simultaneous evaluation and R-matrix results are presented. 16 refs., 7 figs.

Carlson, A.D.; Poenitz, W.P.; Hale, G.M.; Peelle, R.W.

1985-01-01

450

Equivalent radii of antennas with noncircular cross section  

E-print Network

+ ? ) Q f g y ('gCRLL) J ? goej 3 - 34C + gz. I +2 -( ? ? )j c". ). ) & I. I )4 ? 2, I?cia b b (-&, b) fo, b) (C, b) (-a-c, o) (-c, o) Co, o) fc, o) (s?cl 0) Fig. 12. Cross Section of M-shaped Antenna From equations (43), (44), (58) and (67..., I (Z) ~(~). e - ~ C ~ F, + -' 4. . ) +9. Fo~ = eo~P2-C s PH 6. z, = 5~PIZ )-S~PH . Substituting I (Z) for I (Z) on the right side of equation (IZ) a first- 0 o~der approximation can be obtained. ?&, ~ [z(r . , ~*) ;'(~. ? . ~?*&j where...

Su, Charles Wen-Hsun

1960-01-01

451

Doubly differential cross sections for galactic heavy-ion fragmentation  

NASA Technical Reports Server (NTRS)

An abrasion-ablation T-matrix formulation is applied to the calculation of double differential-cross sections in projectile fragmentation of 2.1 GeV/nucleon O-16 on Be-9 and 86 MeV/nucleon C-12 on C-12 and Ag-108. An exponential parameterization of the ablation T-matrix is used and the total width of the intermediate states is taken as a parameter. Fitted values of the total width to experimental results are used to predict the lifetime of the ablation stage and indicate a decay time on the order of 10 to the -19th power sec.

Cucinotta, Francis A.; Norbury, John W.; Khandelwal, Govind S.; Townsend, Lawrence W.

1987-01-01

452

Ab initio method for calculating total cross sections  

NASA Technical Reports Server (NTRS)

A method for calculating total cross sections without formally including nonelastic channels is presented. The idea is to use a one channel T-matrix variational principle with a complex correlation function. The derived T matrix is therefore not unitary. Elastic scattering is calculated from T-parallel-squared, but total scattering is derived from the imaginary part of T using the optical theorem. The method is applied to the spherically symmetric model of electron-hydrogen scattering. No spurious structure arises; results for sigma(el) and sigma(total) are in excellent agreement with calculations of Callaway and Oza (1984). The method has wide potential applicability.

Bhatia, A. K.; Schneider, B. I.; Temkin, A.

1993-01-01

453

Status of multigroup cross-section data for shielding applications  

SciTech Connect

Multigroup cross-section libraries for shielding applications in formats for direct use in discrete ordinates or Monte Carlo codes have long been a part of the Data Library Collection (DLC) of the Radiation Shielding Information Center (RSIC). In recent years libraries in more flexible and comprehensive formats, which allow the user to derive his own problem-dependent sets, have been added to the collection. The current status of both types is described, as well as projections for adding data libraries based on ENDF/B-V.

Roussin, R.W.; Maskewitz, B.F.; Trubey, D.K.

1983-01-01

454

3He Spin-Dependent Cross Sections and Sum Rules  

E-print Network

We present a measurement of the spin-dependent cross sections for the \\vec{^3He}(\\vec{e},e')X} reaction in the quasielastic and resonance regions at four-momentum transfer 0.1 < Q^2< 0.9 GeV^2. The spin-structure functions have been extracted and used to evaluate the nuclear Burkhardt--Cottingham and extended GDH sum rules for the first time. Impulse approximation and exact three-body Faddeev calculations are also compared to the data in the quasielastic region.

E94010 Collaboration; K. Slifer; M. Amarian; L. Auerbach; T. Averett; J. Berthot; P. Bertin; B. Bertozzi; T. Black; E. Brash; D. Brown; E. Burtin; J. Calarco; G. Cates; Z. Chai; J. -P. Chen; Seonho Choi; E. Chudakov; C. Ciofi degli Atti; E. Cisbani; C. W. de Jager; A. Deur; R. DiSalvo; S. Dieterich; P. Djawotho; M. Finn; K. Fissum; H. Fonvieille; S. Frullani; H. Gao; J. Gao; F. Garibaldi; A. Gasparian; S. Gilad; R. Gilman; A. Glamazdin; C. Glashausser; W. Glockle; J. Golak; E. Goldberg; J. Gomez; V. Gorbenko; J. -O. Hansen; B. Hersman; R. Holmes; G. M. Huber; E. Hughes; B. Humensky; S. Incerti; M. Iodice; S. Jensen; X. Jiang; C. Jones; G. Jones; M. Jones; C. Jutier; H. Kamada; A. Ketikyan; I. Kominis; W. Korsch; K. Kramer; K. Kumar; G. Kumbartzki; M. Kuss; E. Lakuriqi; G. Laveissiere; J. J. Lerose; M. Liang; N. Liyanage; G. Lolos; S. Malov; J. Marroncle; K. McCormick; R. D. McKeown; Z. -E. Meziani; R. Michaels; J. Mitchell; A. Nogga; E. Pace; Z. Papandreou; T. Pavlin; G. G. Petratos; D. Pripstein; D. Prout; R. Ransome; Y. Roblin; D. Rowntree; M. Rvachev; F. Sabatie; A. Saha; G. Salme; S. Scopetta; R. Skibinski; P. Souder; T. Saito; S. Strauch; R. Suleiman; K. Takahashi; S. Teijiro; L. Todor; H. Tsubota; H. Ueno; G. Urciuoli; R. Van der Meer; P. Vernin; H. Voskanian; H. Witala; B. Wojtsekhowski; F. Xiong; W. Xu; J. -C. Yang; B. Zhang; P. Zolnierczuk

2008-07-11

455

SCAMPI: A code package for cross-section processing  

SciTech Connect

The SCAMPI code package consists of a set of SCALE and AMPX modules that have been assembled to facilitate user needs for preparation of problem-specific, multigroup cross-section libraries. The function of each module contained in the SCANTI code package is discussed, along with illustrations of their use in practical analyses. Ideas are presented for future work that can enable one-step processing from a fine-group, problem-independent library to a broad-group, problem-specific library ready for a shielding analysis.

Parks, C.V.; Petrie, L.M.; Bowman, S.M.; Broadhead, B.L.; Greene, N.M.; White, J.E.

1996-04-01

456

Photon plus Jet Cross Sections at the Tevatron  

E-print Network

Photon plus jet production has been studied by the D0 and CDF experiments in Run II of the Fermilab Tevatron Collider at a center of mass energy of sqrt{s}=1.96 TeV. Measurements of the inclusive photon plus jet, di-photon and photon plus b jet cross section are presented. They are based on integrated luminosities between 0.2 fb^-1 and 1.1 fb^-1. The results are compared to perturbative QCD calculations in various approximations.

Lars Sonnenschein

2008-04-03

457

Fitting Formulae for Cross Sections of Tidal Capture Binary Formation  

E-print Network

Tidal captures can produce objects that are observationally and dynamically important in dense stellar systems. Recent discoveries of compact young clusters in and out of the Galaxy have prompted the studies of dynamics of star clusters with a large range in stellar masses. The tidal interactions between high and low mass stars are found to be rather frequent in such clusters. In this Research Note, we present fitting formulae for the cross sections of tidal capture binary formation between two stars with a large mass ratio. We present the cases between two main-sequence stars, and between a degenerate star and a main-sequence star.

Sungsoo S. Kim; Hyung Mok Lee

1999-05-11

458

Fission cross section calculations of actinides with EMPIRE code  

SciTech Connect

The cross sections of the neutron induced reactions on {sup 233,234,236}U, {sup 237}Np, {sup 238,242}Pu, {sup 241,243}Am, {sup 242,246}Cm carried out in the energy range 1 keV-20 MeV with EMPIRE code are presented, emphasizing the fission channel. Beside a consistent, accurate set of evaluations, the paper contains arguments supporting the choice of the reaction models and input parameters. A special attention is paid to the fission parameters and their uncertainties.

Sin, M.; Oblozinsky, P.; Herman,M.; Capote,R.

2010-04-30

459

Two jet production and triple differential cross sections  

SciTech Connect

Large samples of data with jets at high pseudorapidities have been collected at the Fermilab Tevatron {ital p{bar p}} collider at {radical}{ital s}=1.8 TeV. Both the DO/ and CDF experiments have used the dijet cross sections, {ital d}{sup 3}{sigma}/{ital dE}{sub {ital Td}}{eta}{sub 1}{ital d}{eta}{sub 2}, to make detailed tests of perturbative QCD. These data sets will eventually place constraints on the gluon distribution functions. Results presented here are from data taken during 1992{endash}1993. {copyright} {ital 1996 American Institute of Physics.}

Nang, F. [Department of Physics, Brown University, Providence, Rhode Island 02912 (United States)

1996-02-01

460

Variation of Properties Throughout Cross Section of Two Extruded Shapes  

NASA Technical Reports Server (NTRS)

Tensile and compressive properties were determined of specimens cut from the fins and the main bodies of two different extruded shapes of 24S-T aluminum alloy. The specimens from the fins as compared with those from the main body of the section showed: tensile strengths from 5000 to 10,000 pounds per square inch lower; tensile yield strengths and compressive yield strengths 4000 to 9000 pounds per square inch lower. The compressive yield strength values for any given location in the cross sections were about 1000 to 6000 pounds per square inch lower than the tensile strength values for the same location.

Howell, F M

1941-01-01

461

Dielectronic Recombination Cross-Sections of Fluorinelike Xenon  

E-print Network

PHYSICAL REVIEW A VOLUME 47, NUMBER 3 MARCH 1993 Dielectronic recombination cross sections of Snorinelike xenon D. R. DeWitt, D. Schneider, M. H. Chen, and M. B. Schneider Laturence Li uermore National Laboratory, Uniuersity of California.... E. Marrs, M. A. Levine, C. L. Bennett, M. H. Chen, J. R. Henderson, M. B. Schneider, and J. H. Scofield, Phys. Rev. Lett. 62, 2104 (1989). [4] R. Ali, C. P. Bhalla, C. L. Cocke, M. Schulz, and M. Stockli, Phys. Rev. A 44, 223 (1991);R. Ali, C. P...

Dewitt, D. R.; Schneider, D.; Chen, M. H.; Schneider, M. B.; Church, David A.; Weinberg, G.; Sakurai, M.

1993-01-01

462

The longitudinal cross section of vector meson electroproduction  

E-print Network

We analyze electroproduction of light vector mesons (V=rho, phi and omega) at small Bjorken-x in the handbag approach in which the process factorizes into general parton distributions and partonic subprocesses. The latter are calculated in the modified perturbative approach where the transverse momenta of the quark and antiquark forming the vector meson are retained and Sudakov suppressions are taken into account. Modeling the generalized parton distributions through double distributions and using simple Gaussian wavefunctions for the vector mesons, we compute the longitudinal cross sections at large photon virtualities. The results are in fair agreement with the findings of recent experiments performed at HERA and HERMES.

S. V. Goloskokov; P. Kroll

2006-11-22

463

He3 Spin-Dependent Cross Sections and Sum Rules  

NASA Astrophysics Data System (ADS)

We present a measurement of the spin-dependent cross sections for the He?3(e?,e')X reaction in the quasielastic and resonance regions at a four-momentum transfer 0.1?Q2?0.9GeV2. The spin-structure functions have been extracted and used to evaluate the nuclear Burkhardt-Cottingham and extended Gerasimov-Drell-Hearn sum rules for the first time. The data are also compared to an impulse approximation calculation and an exact three-body Faddeev calculation in the quasielastic region.

Slifer, K.; Amarian, M.; Auerbach, L.; Averett, T.; Berthot, J.; Bertin, P.; Bertozzi, B.; Black, T.; Brash, E.; Brown, D.; Burtin, E.; Calarco, J.; Cates, G.; Chai, Z.; Chen, J.-P.; Choi, Seonho; Chudakov, E.; Ciofi Degli Atti, C.; Cisbani, E.; de Jager, C. W.; Deur, A.; Disalvo, R.; Dieterich, S.; Djawotho, P.; Finn, M.; Fissum, K.; Fonvieille, H.; Frullani, S.; Gao, H.; Gao, J.; Garibaldi, F.; Gasparian, A.; Gilad, S.; Gilman, R.; Glamazdin, A.; Glashausser, C.; Glöckle, W.; Golak, J.; Goldberg, E.; Gomez, J.; Gorbenko, V.; Hansen, J.-O.; Hersman, B.; Holmes, R.; Huber, G. M.; Hughes, E.; Humensky, B.; Incerti, S.; Iodice, M.; Jensen, S.; Jiang, X.; Jones, C.; Jones, G.; Jones, M.; Jutier, C.; Kamada, H.; Ketikyan, A.; Kominis, I.; Korsch, W.; Kramer, K.; Kumar, K.; Kumbartzki, G.; Kuss, M.; Lakuriqi, E.; Laveissiere, G.; Lerose, J. J.; Liang, M.; Liyanage, N.; Lolos, G.; Malov, S.; Marroncle, J.; McCormick, K.; McKeown, R. D.; Meziani, Z.-E.; Michaels, R.; Mitchell, J.; Nogga, A.; Pace, E.; Papandreou, Z.; Pavlin, T.; Petratos, G. G.; Pripstein, D.; Prout, D.; Ransome, R.; Roblin, Y.; Rowntree, D.; Rvachev, M.; Sabatié, F.; Saha, A.; Salmè, G.; Scopetta, S.; Skibi?ski, R.; Souder, P.; Saito, T.; Strauch, S.; Suleiman, R.; Takahashi, K.; Teijiro, S.; Todor, L.; Tsubota, H.; Ueno, H.; Urciuoli, G.; van der Meer, R.; Vernin, P.; Voskanian, H.; Wita?a, H.; Wojtsekhowski, B.; Xiong, F.; Xu, W.; Yang, J.-C.; Zhang, B.; Zolnierczuk, P.

2008-07-01

464

Electron Scattering Cross Sections in cs Using AN Mot  

NASA Astrophysics Data System (ADS)

A magneto-optical trap utilizing infrared diode lasers is being used to trap Cs atoms for the convenient measurement of electron collision cross sections using the methods pioneered by the Wisconsin group [ R S Schappe et al, Phys Rev Lett 76, 4328, 1996]. Full details of trap parameters and performance will be given as well as initial measurements using the pulsed e-beam system. * Research supported by the Natural Sciences and Engineering Research Council (NSERC), Canadian Institute for Photonic Innovation, (CIPI) and Canadian Foundation for Innovation (CFI).

Macaskill, J. A.; Domyslawska, J.; Sak, M.; Kedzierski, W.; McConkey, W. J.

2001-05-01

465

Resolution function of nonsinusoidal radar signals. I - Range-velocity resolution with rectangular pulses  

Microsoft Academic Search

A generalization of a previously published ambiguity function that applies to radar known as large-relative-bandwidth radar, carrier-free radar, impulse radar, or nonsinusoidal radar is discussed. This radar has recently attracted attention because of its ability to penetrate absorbing materials used in the stealth technology. Another good application is the detection of moving targets with a small radar cross section by

Nasser J. Mohamed

1990-01-01

466

Resolution function of nonsinusoidal radar signals. I. Range-velocity resolution with rectangular pulses  

Microsoft Academic Search

A generalization of a previously published ambiguity function that applies to radar known as large-relative-bandwidth radar, carrier-free radar, impulse radar, or nonsinusoidal radar is discussed. This radar has attracted attention because of its ability to penetrate absorbing materials used in the stealth technology. Another good application is the detection of moving targets with a small radar cross section by a

N. J. Mohamed

1990-01-01

467

Total Cross Sections for Inelastic Scattering of Charged Particles by Atoms and Molecules. III. Accurate Bethe Cross Section for Ionization of Helium  

Microsoft Academic Search

The Bethe cross section sigmai for ionization of He by fast charged particles is accurately evaluated by a subtraction sigmai=sigmatot-sigmaex, where sigmatot is the total inelastic scattering cross section and sigmaex is the sum of all discrete-excitation cross sections. Our earlier work has given a highly precise value of sigmatot, and recent results on discrete excitations enables one to determine

Mitio Inokuti; Young-Ki Kim

1969-01-01

468

Angular distributions and total cross sections for D⁻ formation from interaction of Dâ \\/sup +\\/ with cesium. [Differential cross sections, 1. 0 to 5. 0 KeV  

Microsoft Academic Search

Absolute differential cross sections for the production of D⁻ and D° + Dâ° have been determined for single and double electron-capture collisions into dissociative states by 1.0- to 5.0-keV Dâ \\/sup +\\/ in Cs vapor. Integrations of the differential cross sections over the angles yield the total cross sections for the production of D⁻ and D° + Dâ°. A theory

C. Cisneros; I. Alvarez; C. F. Barnett; J. A. Ray; A. Russek

1976-01-01

469

Multiple electron loss cross sections for heavy ions incident on various atomic and molecular gases. [Differential and total cross sections, charge exchange, 20 MeV  

Microsoft Academic Search

Differential cross sections for charge change resulting from the scattering of 20 MeV ¹²⁷I\\/sup 5 +\\/ and 20 MeV ³⁵Cl\\/sup 4 +\\/ ions from thin gaseous targets were measured. Total cross sections for multiple electron loss were determined by integration of the differential charge state yields over angle. Cross sections will be presented for ¹²⁷I\\/sup 5 +\\/ ions and ³⁵Cl\\/sup

1978-01-01

470

Angular distributions and total cross sections for D⁻ formation from interaction of D\\/sup +\\/ and D° with cesium. [Differential cross sections  

Microsoft Academic Search

Absolute differential scattering cross sections have been determined for single and double electron-capture collisions of 0.5- to 2.5-keV D\\/sup +\\/ and D° in Cs vapor. Integration of the differential cross section over the scattering angles yielded the total electron-capture cross sections. Angular distributions were peaked in the forward direction, and the angular width increased as the particle energy decreased. Cross

C. Cisneros; I. Alvarez; C. F. Barnett; J. A. Ray

1976-01-01

471

Charge exchange and ionization cross sections of H{sup +}+H collision in dense quantum plasmas  

SciTech Connect

The plasma screening effects of dense quantum plasmas on H{sup +}+H charge exchange and ionization cross sections are calculated by the classical trajectory Monte Carlo method. For charge exchange cross sections, it is found that the screening effects reduce cross sections slightly in weak screening conditions. However, cross sections are reduced substantially in strong screening conditions. For ionization cross sections, with the increase of screening effects, cross sections for low energies increase more rapidly than those for high energies. When the screening effects are strong enough, it is found that ionization cross sections decrease with the increase of incident H{sup +} energy. In addition, the cross sections have been compared with those in weakly coupled plasmas. It is found that in weak screening conditions, plasma screening effects in the two plasmas are approximately the same, while in strong screening conditions, screening effects of dense quantum plasmas are stronger than those of weakly coupled plasmas.

Zhang, Ling-yu; Qi, Xin; Zhao, Xiao-ying; Meng, Dong-yuan; Xiao, Guo-qing [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, Gansu 730000, China and University of Chinese Academy of Sciences, Beijing 100049 (China)] [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, Gansu 730000, China and University of Chinese Academy of Sciences, Beijing 100049 (China); Duan, Wen-shan [Joint Laboratory of Atomic and Molecular Physics of NWNU and IMP CAS, Northwest Normal University, Lanzhou, Gansu 730070 (China)] [Joint Laboratory of Atomic and Molecular Physics of NWNU and IMP CAS, Northwest Normal University, Lanzhou, Gansu 730070 (China); Yang, Lei [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, Gansu 730000, China and University of Chinese Academy of Sciences, Beijing 100049 (China) [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, Gansu 730000, China and University of Chinese Academy of Sciences, Beijing 100049 (China); Department of Physics, Lanzhou University, Lanzhou 730000 (China)

2013-11-15

472

Momentum transfer cross sections for the heavy noble gases  

NASA Astrophysics Data System (ADS)

We have used our relativistic optical potential method [1] to calculate the momentum transfer cross sections for Ar, Kr and Xe from threshold to 1000 eV. The target ground state as well as the open excited and ionization channels used in the optical potential have been calculated using the MCDF program [2]. We have included 17 excitation channels for Ar, 26 for Kr and 15 for Xe. In the ionization channels, ionization of the outer p, s and d shells were included for Kr and Xe while for Ar all electrons were allowed to be ionized. Comparisons with previous calculations and experimental measurements will be included. We also include analytic fits to our cross sections to aid in plasma modelling studies. [4pt] [1] S. Chen, R. P. McEachran and A. D. Stauffer, J. Phys. B 41 025201 (2008) [0pt] [2] I. P. Grant, B. J. McKenzie, P. H. Norrington, D. F. Mayers and N. C. Pyper, Comput. Phys. Commun. 21 207 (1980)

Stauffer, A. D.; McEachran, R. P.

2012-10-01

473

Effect of strongly coupled plasma on photoionization cross section  

NASA Astrophysics Data System (ADS)

The effect of strongly coupled plasma on the ground state photoionization cross section is studied. In the non relativistic dipole approximation, cross section is evaluated from bound-free transition matrix element. The bound and free state wave functions are obtained by solving the radial Schrodinger equation with appropriate plasma potential. We have used ion sphere potential (ISP) to incorporate the plasma effects in atomic structure calculation. This potential includes the effect of static plasma screening on nuclear charge as well as the effect of confinement due to the neighbouring ions. With ISP, the radial equation is solved using Shooting method approach for hydrogen like ions (Li+2, C+5, Al+12) and lithium like ions (C+3, O+5). The effect of strong screening and confinement is manifested as confinement resonances near the ionization threshold for both kinds of ions. The confinement resonances are very much dependent on the edge of the confining potential and die out as the plasma density is increased. Plasma effect also results in appearance of Cooper minimum in lithium like ions, which was not present in case of free lithium like ions. With increasing density the position of Cooper minimum shifts towards higher photoelectron energy. The same behaviour is also true for weakly coupled plasma where plasma effect is modelled by Debye-Huckel potential.

Das, Madhusmita

2014-01-01

474

Temperature Dependent Absorption Cross-sections of PFTBA  

NASA Astrophysics Data System (ADS)

We present temperature-dependent absorption cross sections of perfluorotributylamine (PFTBA). PFTBA is a fully-fluorinated liquid commonly used in electronic reliability and quality testing. PFTBA vapour can be considered a potential greenhouse gas due being radiatively active in the mid-IR spectral region and having a long atmospheric lifetime. A recent paper by Hong et al.1 as well as comparisons with previous works for the ethylene calculationsc determined that PFTBA has the highest radiative efficiency of any compound detected in the atmosphere with a detected a mixing ratio of 0.18 parts per trillion by volume over Toronto, ON. Theoretical density functional theory (DFT) calculations are done using the B3LYP method and the 6-311G(d,p) basis set. The calculations have determined the optimized geometrical configuration and IR intensities and wavenumbers of the harmonic frequencies for both PFBAm (N(CF2CF2CF2CF3)3) and its congener (F3CN(CF2CF2CF2CF3)2). Experimental cross sections are derived from Fourier transform spectroscopy performed from 600-1450 cm-1 at a resolution of 0.02 cm-1 for room temperature and above. These experimental results are compared to compared to previous measurements of PFTBA made at room temperature by Young2.

Godin, Paul J.; Conway, Stephanie; Hong, Angela; Mabury, Scott; Strong, Kimberly

2014-06-01

475

CROSS SECTION EVALUATIONS FOR ENDF/B-VII.  

SciTech Connect

This is the final report of the work performed under the LANL contract on neutron cross section evaluations for ENDF/B-VII (April 2005-May 2006). The purpose of the contract was to ensure seamless integration of the LANL neutron cross section evaluations in the new ENDF/B-VII library. The following work was performed: (1) LANL evaluated data files submitted for inclusion in ENDF/B-VII were checked and, when necessary, formal formatting errors were corrected. As a consequence, ENDF checking codes, run on all LANL files, do not report any errors that would rise concern. (2) LANL dosimetry evaluations for {sup 191}Ir and {sup 193}Ir were completed to match ENDF requirements for the general purpose library suitable for transport calculations. A set of covariances for both isotopes is included in the ENDF files. (3) Library of fission products was assembled and successfully tested with ENDF checking codes, processed with NJOY-99.125 and simple MCNP calculations. (4) KALMAN code has been integrated with the EMPIRE system to allow estimation of covariances based on the combination of measurements and model calculations. Covariances were produced for 155,157-Gd and also for 6 remaining isotopes of Gd.

HERMAN, M.; ROCHMAN, D.; OBLOZINSKY, P.

2006-06-05

476

Neutron cross section standards and instrumentation. Annual report  

SciTech Connect

The objective of this interagency program is to provide accurate neutron interaction measurements for the US Department of Energy nuclear programs which include waste disposal, fusion, safeguards, defense, fission, and personnel protection. These measurements are also useful to other energy programs which indirectly use the unique properties of the neutron for diagnostic and analytical purposes. The work includes the measurement of reference cross sections and related neutron data employing unique facilities and capabilities at NIST and other laboratories as required; leadership and participation in international intercomparisons and collaborations; the preservation of standard reference deposits and the development of improved neutron detectors and measurement methods. A related and essential element of the program is critical evaluation of neutron interaction data including international coordinations. Data testing of critical data for important applications is included. The program is jointly supported by the Department of Energy and the National Institute of Standards and Technology. This report from the National Institute of Standards and Technology contains a summary of the accomplishments of the Neutron Cross Section Standards and Instrumentation Project during the third year of this three-year interagency agreement. The proposed program and required budget for the following three years are also presented. The program continues the shifts in priority instituted in order to broaden the program base.

Wasson, O.A.

1993-07-01

477

Measuring differential cross sections using the Doppler shift  

SciTech Connect

We discuss two methods, one of them new, for recovering level-specific differential cross sections in crossed molecular beams experiments from the Doppler profiles of line shapes observed by laser induced fluorescence. The angular resolutions of the two methods are compared and shown to be complementary. An experiment using both methods can have moderately good angular resolution at all scattering angles. In the first method, which has previously been demonstrated experimentally, the Dopper profile is taken with the laser beam parallel to the relative velocity of the collision system. Good angular resolution is obtained between ..pi../4 and 3..pi../4. In the second method, which is proposed here, the Doppler profile is taken with the laser beam perpendicular to this relative velocity, and the best angular resolution is obtained in the regions 0 to ..pi../4 and 3..pi../4 to ..pi... This method requires an integral transform to recover the cross section from the Doppler profile. A practical implementation of this transform is presented along with a numerical example showing its relative insensitivity to noise in the profile.

Serri, J.A.; Kinsey, J.L.; Pritchard, D.E.

1981-07-15

478

Research on Fast-Doppler-Broadening of neutron cross sections  

SciTech Connect

A Fast-Doppler-Broadening method is developed in this work to broaden Continuous Energy neutron cross-sections for Monte Carlo calculations. Gauss integration algorithm and parallel computing are implemented in this method, which is unprecedented in the history of cross section processing. Compared to the traditional code (NJOY, SIGMA1, etc.), the new Fast-Doppler-Broadening method shows a remarkable speedup with keeping accuracy. The purpose of using Gauss integration is to avoid complex derivation of traditional broadening formula and heavy load of computing complementary error function that slows down the Doppler broadening process. The OpenMP environment is utilized in parallel computing which can take full advantage of modern multi-processor computers. Combination of the two can reduce processing time of main actinides (such as {sup 238}U, {sup 235}U) to an order of magnitude of 1{approx}2 seconds. This new method is fast enough to be applied to Online Doppler broadening. It can be combined or coupled with Monte Carlo transport code to solve temperature dependent problems and neutronics-thermal hydraulics coupled scheme which is a big challenge for the conventional NJOY-MCNP system. Examples are shown to determine the efficiency and relative errors compared with the NJOY results. A Godiva Benchmark is also used in order to test the ACE libraries produced by the new method. (authors)

Li, S.; Wang, K.; Yu, G. [Dept. of Engineering Physics, Tsinghua Univ., Beijing, 100084 (China)

2012-07-01

479

Prediction of the separated flow around forebody cross-sections  

NASA Astrophysics Data System (ADS)

Detached Eddy Simulation (DES) and the Reynolds-averaged Navier-Stokes (RANS) equations have been used to predict the unsteady separated flow around forebody cross-sections. Results are presented for cross-sectional shapes comprised of a rounded-corner square and 2:1 aspect ratio ellipse. Freestream flows at an attack angle of 10^circ and Reynolds numbers varying from 5× 10^4 to 8× 10^5 are considered. Grid sizes are approximately 2.8× 10^4 points for two-dimensional simulations and 1.4× 10^6 points for three-dimensional calculations. Simulations are used to assess changes in the flow structure and forces on the body with separation type, i.e., laminar or turbulent boundary layer separation, and to investigate conditions leading to force reversal. Streamwise force coefficients in the flow around the rounded-corner square for the turbulent separation cases