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1

Radar Cross Section (RCS) Data Base Deduced from Radar Images.  

National Technical Information Service (NTIS)

The creation of radar cross section (RCS) catalogs using existing radar images is discussed. Analysis of SIR-B images shows that spatial resolution has a significant impact on the radar data information content. Interpretation of radar data must be based ...

A. J. Sieber

1986-01-01

2

Radar cross section analysis of various objects and RCS optimisation  

Microsoft Academic Search

This work is based on the analysis and optimization of the radar cross section that is indispensable for today's defense industry. In this study, radar cross section analysis of many objects from simple geometric structures to military vehicles are made. Nowadays, when the electronic war technology is growing rapidly in, the stealth technology in radar systems became one of the

Ozan Yurduseven; Okan Yurduseven; Ahmet Serdar Turk

2010-01-01

3

A study of Radar Cross Section (RCS) characteristics and their application in future weapon systems  

Microsoft Academic Search

The sum of components technique was used to calculate the radar cross section (RCS) of a Canberra B2 aircraft. The theoretical result obtained by using simple shapes to model the aircraft were compared with practical results. It is found that this technique can be used to give a quick order of magnitude estimation of a target's RCS. However, the major

W. A. McCluggage

1987-01-01

4

A study of Radar Cross Section (RCS) characteristics and their application in future weapon systems  

NASA Astrophysics Data System (ADS)

The sum of components technique was used to calculate the radar cross section (RCS) of a Canberra B2 aircraft. The theoretical result obtained by using simple shapes to model the aircraft were compared with practical results. It is found that this technique can be used to give a quick order of magnitude estimation of a target's RCS. However, the major drawback of this technique is that it cannot predict the rapid changes in RCS which result from a small change in aspect angle. Trends in radar guided weapons, the effects of aircraft shape on the overall RCS of a weapons platform, and reduction of aircraft RCS by appropriate shaping are discussed. Methods, including radar absorption, radar absorbing materials, impedance loading, and active cancellation, which can be used to reduce an aircraft's radar signature and the associated penalties are reviewed.

McCluggage, W. A.

5

Radar cross section measurements  

Microsoft Academic Search

The present status of radar cross section (RCS) measurements is addressed. The fundamental considerations and definitions associated with RCS measurements are reviewed, including radar waveform, polarization requirements, far-field requirements, and target dimensional scaling. Different types of measurement facilities are examined, including their range geometries, target support systems, calibration standards, and facility evaluation. Instrumentation radar requirements and designs are reviewed, and

Robert B. Dybdal

1987-01-01

6

Inductively Coupled Compact RFID Tag Antenna at 910 MHz With Near-Isotropic Radar Cross-Section (RCS) Patterns  

Microsoft Academic Search

This letter presents a compact (0.12 x 0.14lambda) RFID tag antenna which has near-isotropic radar cross-section (RCS) patterns and easy conjugate impedance matching property by virtue of an inductively coupled feeding. Its measured maximum and minimum RCS' are -17.3 dBm2 and -20.4 dBm2, respectively, with a difference of only 3.1 dB in all incident angles. The measured RCS' have been

Juno Ahn; Hyungmin Jang; Hyosang Moon; Jong-Wook Lee; Bomson Lee

2007-01-01

7

Radar Cross Section of Ships  

Microsoft Academic Search

A laboratory method to determine the magnitude and position of radar reflection sources on complex targets is described. In addition the method provides a way to measure the modification of the radar cross section (RCS) due to multipath. The method has application in modeling RCS for radar and electronic countermeasure (ECM) system performance analysis and in the study of the

F. C. Paddison; C. A. Shipley; A. L. Maffett; M. H. Dawson

1978-01-01

8

An analytic model for estimating the average radar cross section (RCS) for identifying the flickering target  

Microsoft Academic Search

We develop an analytical model for estimating the average RCS which gives good results in identifying flickering targets. The proposed analytical model is applied, specially in the high frequency operating range, by resolving the shape of the complex flicker targets into a number of simple geometric segments, of defined cross-section. Thus the scattered-field contribution from each of these geometric components

F. A. Salem

1996-01-01

9

Radar cross section  

Microsoft Academic Search

The technological evolution in signal processing that has been made in last decades led to improvements in radar performances. Increasing the radar range by improving its sensitivity has been made by the designers of aircraft and other military systems to try to decrease the radar cross section of these types of equipment. The radar cross section is a matter of

L. Nicolaescu; Teofil Oroian

2001-01-01

10

Analysis of the radar cross-section (RCS) of aircraft vortices  

NASA Astrophysics Data System (ADS)

Radar has been proposed as one way to track wake vortices to reduce aircraft spacing. Radar echoes from aircraft wakes are usually interpreted qualitatively using Tatarski's theory of scattering by isotropic atmospheric turbulence. The present work predicts RCS by (1) Keeping the weak scattering approximation but dropping the assumptions of a far-field and a uniform incident wave, neither of which is generally valid for a coherent wake (2) Considering three simple mechanisms for the structure and magnitude of refractive index variations: (i) Radial density gradient in each vortex (ii) Adiabatic transport of atmospheric fluid in the oval surrounding the vortices (iii) 3D fluctuations in the vortex cores. For mechanism (ii) the predictions agree with available data. However, the predictions have a cut-off away from normal incidence which is not present in the measurements due possibly to 3D fluctuations in the oval. The reflectivity of mechanism (i) is comparable but cuts-off at frequencies lower than those considered in the experiment. Finally, we suggest that hot engine exhaust could increase RCS by 40 db and reveal vortex circulation, provided its mixing is prevented in the laminar vortices.

Shariff, Karim; Wray, Alan

1999-11-01

11

Cavity Radar Cross Section Prediction  

Microsoft Academic Search

Alternative models are discussed for the determination of the interior irradiation contribution to the radar cross section (RCS) of open-ended cavities. Typical applications of practical interest include radiation field prediction of open-ended waveguides and signature prediction of jet engine air intakes and exhaust outlets. It is shown and explained why the classic perfectly conducting (PEC) ground plane (GP) model sometimes

Adam Zdunek; Waldemar Rachowicz

2008-01-01

12

Bi-static radar cross section (RCS) reduction of impedance cylinder  

Microsoft Academic Search

Reduction of RCS of military targets is important issue and can be regarded as part of passive ECM (electronic counter measure). Reduction of RCS is basically made by multilayer coating the surface of the target by lossy dielectrics. In this case, boundary condition which is satisfied on the surface of target can be modelled by IBC (impedance boundary condition). We

Necmi Serkan Tezel; Selçuk Paker

2006-01-01

13

Radar Cross Sections of Standard and Complex Shape Targets.  

National Technical Information Service (NTIS)

The theoretical, analytical, and experimental results are described for radar cross sections (RCS) of different-shaped targets. Various techniques for predicting RCS are given, and RCS of finite standard targets are presented. Techniques used to predict t...

M. S. Sohel

1974-01-01

14

Radar cross section: Its prediction measurement and reduction  

Microsoft Academic Search

An introduction to the echo characteristics of radar targets is presented. An overview is first given of radar fundamentals and electromagnetic scattering. Exact prediction techniques, including those pertaining to high-frequency radar cross section (RCS), are addressed. Examples of RCS behavior for simple and complex bodies are shown and discussed. Radar cross section reduction methods and techniques for measuring absorber properties

E. F. Knott; J. F. Shaeffer; M. T. Tuley

1985-01-01

15

HIGH IMPEDANCE GROUND PLANE (HIGP) INCORPORATED WITH RESISTANCE FOR RADAR CROSS SECTION (RCS) REDUCTION OF ANTENNA  

Microsoft Academic Search

In this paper a novel ultra-thin radar absorbent material (RAM) using HIGP is presented and investigated. Owing to the high impedance property of the HIGP, the thickness of the RAM is about several tenths of the centre wavelengthof the absorption band, considerably thinner than conventional absorbers. The absorption band of the RAM is about several hundred megahertz. In the new

Qiu-Rong Zheng; You-Ming Yan; Xiang-Yu Cao; Nai-Chang Yuan

2008-01-01

16

Radar Cross Section Reduction by Absorber Covering  

Microsoft Academic Search

Radar cross section (RCS) reduction by absorber covering is experimentally studied by employing microwave diversity imaging. Experimental results show that broadband absorber covering is not effective at reducing the co-polarized (the transmitting andreceiving antennas have opposite sense of circular polarization) RCS of a plate when the incident wave approximates the edge-on direction but is effective at reducing the cross-polarized (both

H. J. Li; N. H. Farhat; Y. Shen

1989-01-01

17

Radar cross section reduction by absorber covering  

Microsoft Academic Search

Radar cross section (RCS) reduction by absorber covering is experimentally studied by employing microwave diversity imaging. Experimental results show that broadband absorber covering is not effective at reducing the co-polarized (the transmitting and receiving antennas have opposite sense of circular polarization) RCS of a plate when the incident wave approximates the edge-on direction but is effective at reducing the cross-polarized

H. J. Li; N. H. Farhat; Y. Shen

1989-01-01

18

Radar cross section reduction by absorber covering  

NASA Technical Reports Server (NTRS)

Radar cross section (RCS) reduction by absorber covering is experimentally studied by employing microwave diversity imaging. Experimental results show that broadband absorber covering is not effective at reducing the co-polarized (the transmitting and receiving antennas have opposite sense of circular polarization) RCS of a plate when the incident wave approximates the edge-on direction but is effective at reducing the cross-polarized (both the transmitting and receiving antennas have the same sense of circular polarization) RCS for all incident directions. The surface current absorber covering is effective at reducing the nonspecular energy and multiple bounces regardless of the polarization status of the measurement.

Li, H. J.; Farhat, N. H.; Shen, Y.

1989-01-01

19

Simulations of the Radar Cross Section of a Pylon  

Microsoft Academic Search

Simulations of the radar cross section (RCS) of a four-column square-based support pylon were performed in order to find the orientation between a radar antenna and the pylon in which the radar return from the pylon is minimal. From RCS simulations at 2, 6 and 10 GHz it was found that the optimal positioning of pylon occurs when the side

Mauro A. Alves; Guilherme G. Peixoto; Mirabel C. Rezende

20

Calibration accuracy considerations for radar cross-section measurements  

Microsoft Academic Search

This paper examines the calibration accuracy of a total radar cross-section (RCS) measurement system, together with the limitations of the system. The equation for the functional relationship between RCS and the system's parameters is presented. It is shown that the accuracy of an RCS measurement system depends mostly on the use of high-quality calibration standards. The effects of multipath target

G. J. Matyas; B. J. Kelsall

1991-01-01

21

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

22

Uncertainty Analysis for NRaD Radar Cross Section Measurements.  

National Technical Information Service (NTIS)

The Naval Command, Control and Ocean Surveillance Center RDT&E Division (NRaD) conducts Radar Cross Section (RCS) measurements on US naval ships and other targets. This document discusses the assessment of measurement uncertainty and follows general guide...

M. J. Prickett R. A. Bloomfield G. A. Kinzel R. C. Wittmann L. A. Muth

1997-01-01

23

Radar cross section prediction and reduction for naval ships  

NASA Astrophysics Data System (ADS)

Radar cross section (RCS) is the measurement of the reflective strength of a target. Reducing the RCS of a naval ship enables its late detection, which is useful for capitalizing on elements of surprise and initiative. Thus, the RCS of a naval ship has become a very important design factor for achieving surprise, initiative, and survivability. Consequently, accurate RCS determination and RCS reduction are of extreme importance for a naval ship. The purpose of this paper is to provide an understanding of the theoretical background and engineering approach to deal with RCS prediction and reduction for naval ships. The importance of RCS, radar fundamentals, RCS basics, RCS prediction methods, and RCS reduction methods for naval ships is also discussed.

Khan, Jawad; Duan, Wenyang; Sherbaz, Salma

2012-06-01

24

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

25

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

26

Application of Bionics in Antenna Radar Cross Section Reduction  

Microsoft Academic Search

Bionics principle is applied to antenna radar cross section (RCS) reduction in this letter for the first time. To authenticate the method, a novel bionic ultrawideband (UWB) antenna is proposed by use of a model of insect tentacle. Its UWB-related radiation characteristics are simulated and experimentally verified. Monostatic RCS of an insect tentacle antenna (ITA) terminated with three different loads

Wen Jiang; Ying Liu; Shuxi Gong; Tao Hong

2009-01-01

27

Topics for a statistical description of radar cross section  

Microsoft Academic Search

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

Andrew Lewis Maffett

1989-01-01

28

Optimization of radar cross section by a gradient method  

Microsoft Academic Search

Analytical expressions are derived for the derivatives of radar cross sections (RCS) with respect to scatterer shape in two and three dimensions. Using the adjoint formulation, the derivatives of the RCS, with respect to an arbitrary number of design parameters, are found from a single solution of the scattering problem. In two dimensions, gradient-based optimizations converge with a small number

A. Bondeson; Y. Yang; P. Weinerfelt

2004-01-01

29

Radar-Cross-Section Reduction of Wind Turbines. Part 1.  

National Technical Information Service (NTIS)

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...

B. C. Brock J. A. Paquette J. J. McDonald P. G. Clem S. E. Allen W. E. Patitz

2012-01-01

30

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

Microsoft Academic Search

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

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

2012-01-01

31

Calibration accuracy considerations for radar cross-section measurements  

NASA Astrophysics Data System (ADS)

This paper examines the calibration accuracy of a total radar cross-section (RCS) measurement system, together with the limitations of the system. The equation for the functional relationship between RCS and the system's parameters is presented. It is shown that the accuracy of an RCS measurement system depends mostly on the use of high-quality calibration standards. The effects of multipath target support structure coupling and background drift are discussed.

Matyas, G. J.; Kelsall, B. J.

1991-03-01

32

Analysis and Simulation of Quantum Radar Cross Section  

NASA Astrophysics Data System (ADS)

We derive a modified analytical expression of a quantum radar cross section (QRCS). Subsequently, we present a comparison between the QRCS and a classical radar cross section (RCS) and analyze the factors that can affect the intensity of the peak and side lobes. Simulation results on a flat rectangular plate demonstrate that QRCS has a similar structure to that of RCS. The analysis of side-lobe structure can benefit the design of quantum stealth platforms as well as the research on quantum radars.

Liu, Kang; Xiao, Huai-Tie; Fan, Hong-Qi

2014-03-01

33

Radar cross-section analysis of wind turbine blades with radar absorbing materials  

Microsoft Academic Search

Wind turbines interfere with radar systems due to their large radar cross-section (RCS) and the rotation of the blades. Applying radar absorbing materials (RAM) is considered as a possible mitigation measure. This paper will present RCS modeling results of a generic 40 meters blade. The blade is segmented into 4 sections and the monostatic scattering from each section is modeled.

L. S. Rashid; A. K Brown

2011-01-01

34

Warship radar cross section determination and reduction, and hindrances in optimizing radar cross section reduction on warships  

NASA Astrophysics Data System (ADS)

From the begining of military warfare, it has always been extremely important to know the enemy position and hide oneself to capitalize on elements of surprise and initiative, and same is true for naval warfare. Radar is the primary instrument used for detecting enemy platforms today.Radar detects a target by clocking time taken by a known pulse of electromagnetic energy to get to the target and return. Radar cross section (RCS) is the measure of reflective strength of a target. Reducing the RCS of a platform implies its late detection, used to capitalize on surprise and initiative. RCS is also important for survivability evaluation since most modern weapons use installed radars during final engagement phase. As a result, RCS of a warship has transformed into a very important design factor for stealth to achieve surprise, initiative and survivability. Thus accurate RCS determination and RCS reduction are matters of extreme importance. The purpose of this study is to provide an understanding RCS reduction and RCS determination methods used on warships today. In doing so, this study will discuss importance of RCS, radar fundamentals and RCS basics, RCS reduction and RCS determination methods. It will also present hindrances in optimizing RCSR on warships, impact of these hindrances on navies around the world, and comment on possible remedies to these hindrances.

Khan, Jawad; Duan, Wenyang

2011-04-01

35

Evaluation of the Sensitivity of Radar Cross Section Predictions to Uncertainties in Material Characteristics.  

National Technical Information Service (NTIS)

The purpose of this study was to evaluate the effects of material characteristics uncertainties on Radar Cross Section (RCS) predictions. Many methods have been developed to predict the RCS of metal objects, but for material coated objects, these methods ...

G. A. Barnhart

1995-01-01

36

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

37

Simulations of the radar cross section of a stealth aircraft  

Microsoft Academic Search

The radar cross section (RCS) of a CAD model of the stealth bomber B-2 Spirit was simulated with the CADRCS software. Results from simulations with the aircraft model having a perfectly conducting surface and rotating about the yaw, pitch and roll axes are presented and compared with results of simulations where the surface of the model was covered with a

Mauro A. Alves; Rafael J. Port; Mirabel C. Rezende

2007-01-01

38

Considerations in measuring vital signs cross section with Doppler radar  

Microsoft Academic Search

This paper describes the different considerations and challenges in measuring human cardiopulmonary radar cross section (RCS). The effect of clutter on the received signal is explained as well as the importance of preserving baseband dc content for valid readings. The center estimation algorithm with dc- cancellation is presented as a solution to restore dc content in the baseband signals and

John E. Kiriazi; Olga Boric-Lubecke; Victor M. Lubecke

2011-01-01

39

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

Microsoft Academic Search

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

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

1989-01-01

40

Radar absorbing material (RAM) and shaping on radar cross section reduction of dihedral corners  

Microsoft Academic Search

How far can a radar system detect an object depends the radar cross section (RCS) of the target. Corner reflectors are the major scattering centers in the radar signatures of vehicles. The monostatic return from such structures can be reduced by ensuring that surfaces never meet at right angles and by application of radar absorbing materials (RAM). This paper deals

G. G. Peixoto; A. L. de Paula; L. A. Andrade; C. M. A. Lopes; M. C. Rezende

2005-01-01

41

Radar cross section measurement by subscale models  

Microsoft Academic Search

The paper focuses on the methodology of the RCS measurement by using radar object subscale model and on the description of the measurement facilities. The first phase of the RCS measurement by applying comparison method is the reference object (shape) design. There are some necessary conditions of the RCS calculation according to comparison method and subscale modeling. Experimental results, obtained

Jan Ochodnicky; Zdenek Matousek; Mikulas Sostronek; Arnost Hykel

2008-01-01

42

3-d simulations for radar cross-section reduction using plasma absorbers  

Microsoft Academic Search

Summary form only given. Radar cross section (RCS) is the measure of a target's ability to reflect radar signals in the direction of the radar receiver. A collisional unmagnetized plasma, surrounding the target, acts as a good absorber of electromagnetic waves over a wide frequency range, reducing its RCS. This has given rise to world wide interest in plasma stealth

B. Chaudhury; S. Chaturvedi

2006-01-01

43

Numerical computation and measurement of radar cross section for impulse radar  

Microsoft Academic Search

The report investigates the applicability of a computer simulation package, GEMACS, for numerical computation of broadband electromagnetic scattering. Radar cross section (RCS) approximation for three dimensional objects by means of an integral equation approach using the method of moments is examined. RCS versus frequency, viewing angle, and polarization is obtained for finite cylinders and a sphere in the resonance region

L. Christerson

1993-01-01

44

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

45

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

46

Radar cross section statistics of ground vehicles at Ku-band  

Microsoft Academic Search

Knowing the statistical characteristics of a target's radar cross-section (RCS) is crucial to the success of radar target detection algorithms. Open literature studies regarding the statistical nature of the RCS of ground vehicles focus primarily on simulations, scale model chamber measurements, or limited experimental data analysis of specific vehicles at certain frequencies. This paper seeks to expand the existing body

Ann Marie Raynal; Douglas L. Bickel; Michael M. Denton; Wallace J. Bow; Armin W. Doerry

2011-01-01

47

Radar cross section reduction of a flat plate by ram coating  

Microsoft Academic Search

The problem of reduction of radar cross section (RCS) of a flat plate coated with a radar absorbing material has been examined using the uniform asymptotic theory of diffraction. The variation and reduction of RCS with different parameters have been studied and theoretical results have been compared with the experiment and the spectral Galerkin method.

Asoke K. Bhattacharyya

1990-01-01

48

Estimation and Verification of Vessel Radar-Cross-Sections for HF Surface Wave Radar.  

National Technical Information Service (NTIS)

The radar cross sections (RCS) of both small and large ships for High Frequency Surface Wave Radar (HFSWR) were studied by using Numerical Electromagnetics Code 4 and by using measurements from a HFSWR system at Cape Race, Newfoundland, Canada. The result...

H. Wilson H. Leong

2005-01-01

49

Radar cross section statistics of dismounts at Ku-band  

NASA Astrophysics Data System (ADS)

Knowing the statistical characteristics of a target's radar cross-section (RCS) is crucial to the success of radar target detection algorithms. A wide range of applications currently exist for dismount (i.e. human body) detection and monitoring using ground-moving target indication (GMTI) radar systems. Dismounts are particularly challenging to detect. Their RCS is orders of magnitude lower than traditional GMTI targets, such as vehicles. Their velocity of about 0 to 1.5 m/s is also much slower than vehicular targets. Studies regarding the statistical nature of the RCS of dismounts focus primarily on simulations or very limited empirical data at specific frequencies. This paper seeks to enhance the existing body of work on dismount RCS statistics at Ku-band, which is currently lacking, and has become an important band for such remote sensing applications. We examine the RCS probability distributions of different sized humans in various stances, across aspect and elevation angle, for horizontal (HH) and vertical (VV) transmit/receive polarizations, and at diverse resolutions, using experimental data collected at Ku-band. We further fit Swerling target models to the RCS distributions and suggest appropriate detection thresholds for dismounts in this band.

Raynal, Ann Marie; Burns, Bryan L.; Verge, Tobias J.; Bickel, Douglas L.; Dunkel, Ralf; Doerry, Armin W.

2011-05-01

50

The radar cross section of dielectric disks  

NASA Technical Reports Server (NTRS)

A solution is presented for the backscatter (nonstatic) radar cross section of dielectric disks of arbitrary shape, thickness and dielectric constant. The result is obtained by employing a Kirchhoff type approximation to obtain the fields inside the disk. The internal fields induce polarization and conduction currents from which the scattered fields and the radar cross section can be computed. The solution for the radar cross section obtained in this manner is shown to agree with known results in the special cases of normal incidence, thin disks and perfect conductivity. The solution can also be written as a product of the reflection coefficient of an identically oriented slab times the physical optics solution for the backscatter cross section of a perfectly conducting disk of the same shape. This result follows directly from the Kirchhoff type approximation without additional assumptions.

Levine, D. M.

1982-01-01

51

A theory on the distribution function of backscatter radar cross section from ocean waves of individual wavelength  

Microsoft Academic Search

A new and simple method of interpreting the “distribution” of the backscatter radar cross section (RCS) from ocean waves of individual wavelength is presented. Using the Kirchhoff scattering (Physical Optics) theory, the “cumulative” RCS from the ambient waveheight spectrum is first computed as a function of the wavenumber. Differentiating this cumulative RCS yields the distribution function of the RCS from

Kazuo Ouchi

2000-01-01

52

Small Boat HF Radar Cross Sections.  

National Technical Information Service (NTIS)

The HF radar cross section of three small ocean-going craft were measured in full scale with the SEA ECHO radar. The measurements were made over a wide band of frequencies. Care was taken in the calibration of the system to insure accurate absolute values...

R. W. Bogle D. B. Trizna

1976-01-01

53

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

54

Bistatic, fully polarimetric radar cross-section calibration techniques and measurement error analysis  

Microsoft Academic Search

Accurate polarimetric radar cross-section (RCS) measurements require effective calibration procedures and strict attention to possible sources of error. The development of a detailed computer simulation of bistatic, fully polarimetric RCS measurements allowed determination of principal error sources and their relative effect on measurement accuracy. The computer simulation divides the measurement process into five distinct phases: transmission, propagation from the transmit

Brian David Jersak

1993-01-01

55

Application of Millimeter Wave in Verification of Scale Model Measurement for Radar Cross Section  

Microsoft Academic Search

According to the physical optic approximation, a physical scale factor is suggested for scale model measurement of radar cross section (RCS). By this factor, the models of radar targets can be tested at the same frequency as prototype. This is significant for the lack of experimental equipment required or the problem of frequency dependency of radar absorbing materials on the

Hongwei Liu; Yahia M. M. Antar

1999-01-01

56

Application of Millimeter Wave in Verification of Scale Model Measurement for Radar Cross Section  

Microsoft Academic Search

According to the physical optic approximation, a physical scale factor is suggested for scale model measurement of radar cross section (RCS). By this factor, the models of radar targets can be tested at the same frequency as prototype. This is significant for the lack of experimental equipment required or the problem of frequency dependency of radar absorbing materials on the

Hongwei Liu; Yahia M. M. Antar; Zhendong Shi; Zhengde Wu

1998-01-01

57

Radar cross-section measurements of a full-scale aircraft duct\\/engine structure  

Microsoft Academic Search

Cavity radar cross-section (RCS) data are measured from a full-sized generic aircraft duct\\/engine mock-up experimental apparatus. Details of the experimental measurements and characterization of the RCS from a generic aircraft engine inlet with a fan assembly embedded inside are described. The experimental results reveal that the azimuthal RCS patterns from an aircraft engine inlet with fan components embedded inside are

S. K. Wong; E. Riseborough; G. Duff; K. K. Chan

2006-01-01

58

Relationship of radar cross section to the geometric size of orbital debris  

NASA Technical Reports Server (NTRS)

An accurate determination of the sizes of orbiting debris objects is essential to predicting collision rates, atmospheric decay rates, and fragmentation laws for orbiting objects. The radar cross section (RCS) is the most common means of estimating the size of orbiting objects. However, the RCS is prone to error due to Mie scattering, compositional effects, geometrical effects, tumbling, and other dependencies. Optical measurement methods are theoretically much more accurate, but necessitate estimates of the object's albedo. This paper examines the relationship of RCS and optical cross section to physical size and albedo, and presents rules useful for quantizing the physical size of space objects.

Badhwar, Gautam D.; Anz-Meador, Phillip D.

1990-01-01

59

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

60

Automation of an RCS (Radar Cross Section) Measurement System and Its Application to Investigate the Electromagnetic Scattering from Scale Model Aircraft Canopies.  

National Technical Information Service (NTIS)

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 v...

S. A. Owens

1989-01-01

61

Peculiar radar cross section properties of metamaterials with negative permittivity  

Microsoft Academic Search

In this paper, we discuss the peculiar radar cross section properties of metamaterials with negative permittivity, and the connections between the radar cross section, the polarizability and the permittivity of metamaterials are investigated, respectively. These results have shown that the polarizability and radar cross section of the spherical object made of metamaterials whose permittivity is less than - 2 are

Wanzhao Cui; Jia Chen; Enrang Zheng

2008-01-01

62

Radar-cross-section measurement errors caused by test object interaction with low-dielectric-constant supports  

Microsoft Academic Search

In the search for an ideal test-object support for simulated free-space radar-cross-section (RCS) measurements, low-density polystyrene foam has achieved considerable popularity. However, significant error can be introduced into a measurement by the use of an inappropriately designed support. Although low backscatter radar-cross-section (RCS) can be obtained with this material, interactions can occur between the test object and the mount which

B. C. Brock; W. E. Patitz; K. W. Sorensen; D. H. Zittel

1991-01-01

63

Radar cross section measurements in VHF/UHF  

NASA Astrophysics Data System (ADS)

Scientists and technicians tasked with developing future radar systems are becoming increasingly interested in the UHF and VHF bands. Some such systems, especially Soviet ones, have existed for several decades and are used for long distance surveillance and advance alert for ABM missiles. Some of the advantages for tactical and strategic military applications are the stealth weapons and missiles and hidden targets, undetectable at hyperfrequency bands, can be detected at VHF/UHF, and propagation in these bands is relatively unaffected by weather conditions such as snow, rain, or cloud cover. Some of the difficulties linked to radar cross section (RCS) measurement in VHF/UHF are the need for an adequate illumination system, elimination of surrounding clutter, instrumentation, and processing. Techniques for overcoming each of these difficulties are discussed and anechoic chamber experiments carried out in order to verify specific implementations are described.

Saget, Jacques

1991-09-01

64

A study of GEOS-3 terrain data with emphasis on radar cross section  

NASA Technical Reports Server (NTRS)

Radar cross sections (RCS) of terrain are studied using GEOS 3 radar altimeter data. Maps of RCS for portions of four east coast states (U.S.A.) are presented and used to draw curves of RCS versus inland distance as measured from the land/sea interface. The results show RCS to decay approximately exponentially with inland distance. The GEOS 3 data are also used to develop curves of RCS seasonal variation for the same regions. Observed variations correlate strongly with local potential evaporation. Results also show that farming operations in the state of North Carolina are observable in the RCS data. A restricted method for determining surface roughness features from saturated average return waveforms for some types of terrain is developed. Sensor bias induced by receiver saturation for certain terrain returns is briefly discussed.

Priester, R. W.

1980-01-01

65

Radar Cross Section reduction using plasma blobs: 3-D Finite Difference Time Domain simulations  

Microsoft Academic Search

Bistatic scattering cross-section or radar cross section (RCS) of a flat plate covered with cold, collisional, steady-state, inhomogeneous plasma blobs have been studied in this paper. We have performed 3-D finite difference time domain (FDTD) simulations for this study which provides a detailed spatio-temporal evolution of electromagnetic fields. The simulation has been performed using a 10 GHz sinusoidal wave for

Bhaskar Chaudhury; Shashank Chaturvedi

2007-01-01

66

Radar Cross Sections of Ground Clutter at 95 GHz for Summer and Fall Conditions.  

National Technical Information Service (NTIS)

Radar cross section (RCS) measurements were made on an extensively instrumented ground-clutter patch over a period of one month from late summer to early fall. The instrumentation allowed collection of a full set of data on meteorological conditions, sola...

R. J. Wellman D. R. Hutchins J. L. Silvious H. Dropkin G. Goldman

1993-01-01

67

Planar near-field scanning for compact range bistatic radar cross-section measurement  

Microsoft Academic Search

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

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

1991-01-01

68

A comparison of measured radar cross section of solid and mesh ogives  

Microsoft Academic Search

An experimental program was conducted in which the radar cross section (RCS) of solid and mesh ogive models was measured and compared. The data covered an ogive length to wavelength ratio varying by a factor of 100. The various ogive models, the measurement ranges employed, and typical data are discussed in detail. Some of the conclusions drawn from the study

K. Lang; B. Lapage

1974-01-01

69

A Hybrid High-Order Algorithm for Radar Cross Section Computations  

Microsoft Academic Search

We describe a high-order method for computing the monostatic and bistatic radar cross section (RCS) of a class of three-dimensional targets. Our method is based on an electric field surface integral equation reformulation of the Maxwell equations. The hybrid nature of the scheme is due to approximations based on a combination of tangential and nontangential basis functions on a parametric

M. Ganesh; S. C. Hawkins

2007-01-01

70

Model measurement of radar cross-section for fully coated target by variance in the size  

Microsoft Academic Search

Using dimensional analysis, geometric and physical optic approximation, a new method is suggested for electromagnetic scattering measurement of a lossy target. By this method, model measurement for radar cross-section (RCS) can be carried out at the same frequency with a prototype by variance in the size of model. This is significant for the lack of experimental equipment required or the

Hongwei Liu; Zhendong Shi; Zhengde Wu; Y. M. M. Antar

1998-01-01

71

Effect of imperfectly conducting surface of scatter on its radar cross section  

Microsoft Academic Search

The scale-down model testing of radar cross sections (RCSs) for imperfectly conducting bodies requires physical similarity between models and prototype. It is often impossible to satisfy all the requirements at the same time, so it is necessary to study the effect of imperfectly conducting surface of scatter on its RCS. Dimensional analysis and theory of the model are used. As

Zhendong Shi; Chunsheng Ding

1992-01-01

72

Conical cut radar cross section calculations for a thin, perfectly conducting plate  

NASA Technical Reports Server (NTRS)

Radar cross section (RCS) calculations for flat, perfectly conducting plates are readily available through the use of conventional frequency domain techniques such as the method of moments. However, if time domain scattering or wideband frequency domain results are desired, then the finite difference time domain (FDTD) technique is a suitable choice. We present the application of the FDTD technique to the problem of electromagnetic scattering and RCS calculations from a thin, perfectly conducting plate for a conical cut in the scattering angle phi. RCS calculations versus angle phi are presented and discussed.

Luebbers, Raymond J.; Beggs, John H.

1991-01-01

73

Conical cut radar cross section calculations for a thin, perfectly conducting plate  

NASA Technical Reports Server (NTRS)

Radar Cross Section (RCS) calculations for flat, perfectly conducting plates are readily available through the use of conventional frequency domain techniques such as the Method of Moments. However, if time domain scattering or wideband frequency domain results are desired, then the Finite Difference Time Domain (FDTD) technique is a suitable choice. In this paper, we present the application of the Finite Difference Time Domain (FDTD) technique to the problem of electromagnetic scattering and RCS calculations from a thin, perfectly conducting plate for a conical cut in the scattering angle phi. RCS calculations versus angle phi will be presented and discussed.

Luebbers, Raymond J.; Beggs, John H.

1991-01-01

74

Radar Cross-Section Measurements of V22 Blade Tip with and without LLNL Tipcap Reflector  

SciTech Connect

It is desired to quantify the effect, in terms of radar cross-section (RCS), of the addition of a small aluminum reflector to the end of the V22 blades. This reflector was designed and manufactured in order to facilitate blade lag measurements by the 95 GHz Lawrence Livermore National Laboratory (LLNL) Radar Blade Tracker (RBT) system. The reflector used in these measurements was designed and fabricated at LLNL and is pictured in Figure 1.

Poland, D; Simpson, R

2000-07-01

75

Radar cross section statistics of ground vehicles at Ku-band  

NASA Astrophysics Data System (ADS)

Knowing the statistical characteristics of a target's radar cross-section (RCS) is crucial to the success of radar target detection algorithms. Open literature studies regarding the statistical nature of the RCS of ground vehicles focus primarily on simulations, scale model chamber measurements, or limited experimental data analysis of specific vehicles at certain frequencies. This paper seeks to expand the existing body of work on ground vehicle RCS statistics at Ku-band for ground moving target indication (GMTI) applications. We examine the RCS probability distributions of civilian and military vehicles, across aspect and elevation angle, for HH and VV polarizations, and at diverse resolutions, using experimental data collected at Ku-band. We further fit Swerling target models to the distributions and suggest appropriate detection thresholds for ground vehicles in this band.

Raynal, Ann Marie; Bickel, Douglas L.; Denton, Michael M.; Bow, Wallace J.; Doerry, Armin W.

2011-05-01

76

Design and fabrication of a microstrip patch antenna with a low radar cross section in the X-band  

Microsoft Academic Search

In this study, the authors developed a radar absorbing method to reduce the antenna radar cross section (RCS) without any loss of antenna performance. The new method was based upon an electromagnetic bandgap (EBG) absorber using conducting polymer (CP). First, a microstrip patch antenna was made by using a copper film and glass\\/epoxy composite materials, which are typically used for

Hong-Kyu Jang; Won-Jun Lee; Chun-Gon Kim

2011-01-01

77

Radar Cross Section Target Supports, Plastic Materials.  

National Technical Information Service (NTIS)

The results of studies into the scattering properties of cellular plastic materials are presented. A mathematical model for scattering from cellular plastics, developed to provide a method of determining the optimum low cross section target support for a ...

C. H. Smith C. C. Freeny E. F. Knott T. B. A. Senior

1964-01-01

78

Radar cross section of a perfectly conducting, flat, polygonal plate over a dielectric, lossy half space: a closed form, physical optics expression  

Microsoft Academic Search

The Physical Optics approximation is employed in the derivation of a closed form expression for the Radar Cross Section (RCS) of a flat, polygonal, perfectly conducting (PEC) plate, located over a dielectric, possibly lossy half space. The well-known \\

Hristos T. Anastassiu

2002-01-01

79

Review of FD-TD numerical modeling of electromagnetic wave scattering and radar cross section  

NASA Technical Reports Server (NTRS)

Applications of the finite-difference time-domain (FD-TD) method for numerical modeling of electromagnetic wave interactions with structures are reviewed, concentrating on scattering and radar cross section (RCS). A number of two- and three-dimensional examples of FD-TD modeling of scattering and penetration are provided. The objects modeled range in nature from simple geometric shapes to extremely complex aerospace and biological systems. Rigorous analytical or experimental validatons are provided for the canonical shapes, and it is shown that FD-TD predictive data for near fields and RCS are in excellent agreement with the benchmark data. It is concluded that with continuing advances in FD-TD modeling theory for target features relevant to the RCS problems and in vector and concurrent supercomputer technology, it is likely that FD-TD numerical modeling will occupy an important place in RCS technology in the 1990s and beyond.

Taflove, Allen; Umashankar, Korada R.

1989-01-01

80

RCS evaluation of complex objects coated with radar absorbing materials using the complex ray method  

Microsoft Academic Search

The strategy and results of an RCS (radar cross section) evaluation of a dihedral corner reflector coated with lossy materials using the complex ray method are described. A computer program based on the analysis presented has been developed to perform effective RCS calculations of dihedral corner reflectors having the inner surfaces coated with or without radar adsorbing materials. One of

Y. Z. Ruan; H. P. Du

1992-01-01

81

Joint passive radar tracking and target classification using radar cross section  

NASA Astrophysics Data System (ADS)

We present a recursive Bayesian solution for the problem of joint tracking and classification of airborne targets. In our system, we allow for complications due to multiple targets, false alarms, and missed detections. More importantly, though, we utilize the full benefit of a joint approach by implementing our tracker using an aerodynamically valid flight model that requires aircraft-specific coefficients such as wing area and vehicle mass, which are provided by our classifier. A key feature that bridges the gap between tracking and classification is radar cross section (RCS). By modeling the true deterministic relationship that exists between RCS and target aspect, we are able to gain both valuable class information and an estimate of target orientation. However, the lack of a closed-form relationship between RCS and target aspect prevents us from using the Kalman filter or its variants. Instead, we rely upon a sequential Monte Carlo-based approach known as particle filtering. In addition to allowing us to include RCS as a measurement, the particle filter also simplifies the implementation of our nonlinear non-Gaussian flight model.

Herman, Shawn M.

2003-12-01

82

Radar cross-section calculation method for antenna of P-18 radar station  

Microsoft Academic Search

The scattered electromagnetic field calculation method for finite cylinder with resonant cross-section is considered. The method is used for calculation of radar cross-section for antenna of P-18 radar station. Also radar cross-sections for perfectly conducting antenna and antenna partially made of perfectly absorbing materials (Macdonald model) are compared.

O. Sukharevsky; Y. Belevshchuk; V. Vasilets; S. Nechitaylo

2010-01-01

83

Verification and validation of the simulated radar image (SRIM) code radar cross section predictions  

NASA Astrophysics Data System (ADS)

The objectives of this study were to verify and validate the Simulated Radar Image (SRIM) Code Version 4.0 monostatic radar cross section (RCS) predictions. SRIM, uses the theory of Physical Optics (PO) to predict backscatter for a user specified aspect angle. Target obscuration and multiple reflections are taken into account by sampling the target with ray tracing. The software verification and validation technique followed in this study entailed comparing the code predictions to closed form PO equations, other RCS prediction software packages, and measured data. The targets analyzed were a sphere, rectangular flat plate, circular flat plate, solid right circular cylinder, dihedral and trihedral corner reflectors, top hat, cone, prolate spheroid, and generic missile. SRIM RCS predictions are shown for each target as a function of frequency, aspect angle, and ray density. Also presented is an automation technique that enables the user to run SRIM sequentially over a range of azimuth angles. The FORTRAN code written by the author for the PO equations is also provided.

Stanley, Dale A.

1991-12-01

84

A review of high-frequency radar cross section analysis capabilities at McDonnell Douglas Aerospace  

Microsoft Academic Search

Two basic types of physical-optics (PO)-based radar cross section (RCS) analysis codes have come to maturity in today's HF electromagnetic analysis environment. These are facet based and curved surface based codes. Facet codes have very fast analysis rates, while curved-surface codes are usually considered more accurate. At McDonnell Douglas Aerospace (MDA), the need for very reliable RCS results to guide

D. M. Elking; J. M. Roedder; D. D. Car; S. D. Alspach

1995-01-01

85

Research into Influence of Gaussian Beam on Terahertz Radar Cross Section of a Semicircular Boss  

NASA Astrophysics Data System (ADS)

In radar cross section (RCS) calculation of a rough surface, the model can be simplified into the scattering of geometrically idealized bosses on a surface. Thus the problem of the RCS calculation of a rough surface is changed to the RCS calculation of the semicircular boss. The RCS measurement of scale model can help save time and money. The utilization of terahertz in RCS is attractive because of its special properties: the wavelength of the terahertz wave can help limit the size of the model in a suitable range in the measurement of the scale model and get more detailed data in the measurement of the real object. However, usually the incident beam of a terahertz source is a Gaussian beam; in the theoretical RCS estimation, usually a plane wave is assumed as the incident beam for sake of simplicity which may lead to an error between the measurement and calculation results. In this paper, the method of images is used to calculate the RCS of a semicircular boss at 2.52 THz and the results are compared to the one calculated when the incident beam is a plane wave.

Li, Hui-Yu; Li, Qi; She, Jian-Yu; Zhao, Yong-Peng; Chen, De-Ying; Wang, Qi

2013-08-01

86

Radar cross section computation of inhomogeneous scatterers using edge-based finite element methods in frequency and time domains  

Microsoft Academic Search

This paper presents a flexible, body-conforming finite element modeling technique, using Whitney's edge and face basis functions, for efficient computation of radar cross section (RCS) of inhomogeneous scatterers, both in the frequency and time domains. The vector absorbing boundary conditions, originally developed for a spherical absorbing boundary, are generalized for planar and cylindrical boundaries. The computational resources required for the

K. Mahadevan; R. Mittra

1993-01-01

87

Radar cross section measurement by compact range method using 8-element small antenna array instead of one large antenna  

Microsoft Academic Search

RCS (radar cross section) measurement by the compact range method was performed using an 8-element small antenna array instead of one large antenna. The span of each antenna is 800 mm; 4 of the 8 antennas are used for transmission and the other 4 antennas are used for receiving. The transmission antennas and the receiving antennas are placed in cross

H. Suzuki; K. Saito; T. Yoshizawa; S. Uwabe; M. Inoue

2009-01-01

88

Frequency dependence of radar cross section for arbitrarily shaped scatterers  

Microsoft Academic Search

This letter introduces a method to perform frequency dependence of radar cross section for either simple or complex scatters in terms of model measurement. To do so, the expressions of physical scale factor based on the electromagnetic similarity are suggested by means of dimensional analysis, geometric and physical optics approximation. Using the results of model measurement within a small range

Hongwei Liu; Yahia M. M. Antar; Zhendong Shi; Zhengde Wu

1998-01-01

89

Improved Near-Field Radar Cross-Section Measurement Technique  

Microsoft Academic Search

This letter presents an improved image-based coherent Doppler tomography (CDT) technique for near-field radar cross-section measurement. The present formulation, developed using the back-projection algorithm, explicitly incorporates the network analyzer calibration in the near-field to far-field transformation. Experimental measurements and computer simulations are presented to validate the improved CDT technique.

Kelvin J. Nicholson; Chun H. Wang

2009-01-01

90

FDTD modeling of thin impedance sheets [radar cross section calculation  

Microsoft Academic Search

Thin sheets of resistive or dielectric material are commonly encountered in radar cross section calculations. Analysis of such sheets is simplified by using sheet impedances. It is shown that sheet impedances can be modeled easily and accurately using finite-difference time-domain methods

Raymond J. Luebbers; Karl Kunz

1992-01-01

91

Coherent FM-CW millimeter-wave radar systems for radar cross section measurements  

Microsoft Academic Search

Coherent instrumentation radars have been developed at 35 and 94 GHz for use in radar cross section measurements at angles of incidence ranging from 0° to 60°. The systems are designed to measure the radar cross section of various targets, at like and cross-polarizations, in an effort to better understand their scattering characteristics. Both are dual antenna systems capable of

RICHARD T. LAWNER; PETER F. BLANCHARD; SIVA PRASAD GOGINENI

1990-01-01

92

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

93

Radar cross sections of ground clutter at 95 GHz for summer and fall conditions  

NASA Astrophysics Data System (ADS)

Radar cross section (RCS) measurements were made on an extensively instrumented ground-clutter patch over a period of one month from late summer to early fall. The instrumentation allowed collection of a full set of data on meteorological conditions, solar flux, and soil moisture content. The RCS measurements were made using a 95-GHz, polarimetric, monopulse instrumentation radar. The radar is all solid-state, coherent, frequency steppable over a 640-MHz bandwidth, and completely polarimetric for linearly or circularly polarized radiation. The clutter area measured was located in Grayling, Michigan, and consisted of a rectangular patch of ground, 50 by 100 m in area, at a range of about 100 to 250 m from the radar. The clutter patch included areas of bare sandy ground, short grass, low shrubs, evergreen trees, and deciduous trees and was similar to a NATO European environment. A wide range of atmospheric conditions were observed over the measurement period, including a few days of measurable snowfall. The paper describes analysis of the effects of different clutter types and different atmospheric conditions on the measured RCS of the clutter patch.

Wellman, R. J.; Hutchins, D. R.; Silvious, J. L.; Dropkin, H.; Goldman, G.; Nemarich, J.; Wikner, D. A.; Dahlstrom, R. K.

1993-11-01

94

Effect of imperfectly conducting surface of scatter on its radar cross section  

NASA Astrophysics Data System (ADS)

The scale-down model testing of radar cross sections (RCSs) for imperfectly conducting bodies requires physical similarity between models and prototype. It is often impossible to satisfy all the requirements at the same time, so it is necessary to study the effect of imperfectly conducting surface of scatter on its RCS. Dimensional analysis and theory of the model are used. As a result the relationship between sigma/lambda squared and eta sub s is obtained, and the comparison between theoretical and experimental values for a cylinder coated with absorbent materials is given.

Shi, Zhendong; Ding, Chunsheng

1992-06-01

95

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

96

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

97

A calibration method for radar cross section measurements at sea  

NASA Astrophysics Data System (ADS)

A technique is presented which yields a free space calibration at the measuring site. The free space calibration eliminates the effect of multipath on calibration and makes it possible to take atmospheric attenuation into account. The technique has been used to make radar-cross-section measurements for ships in the Baltic Sea. The calibration target has been a corner reflector with a 47-cm side mounted at the front of the Alouette II helicopter.

Lok, Hans

98

Simulations and measurements of a radar cross section of a Boeing 747-200 in the 20-60 MHz frequency band  

Microsoft Academic Search

HF and VHF low frequency bands provide a promising way to perform radar target recognition. At these frequencies, Radar Cross Section (RCS) behavior is not well known because the scattered field is due to a complex phenomenon where the interactions between the different parts of the structure have a significant contribution, which makes the prediction difficult. A wire model of

A. David; C. Brousseau; A. Bourdillon

2003-01-01

99

Simulations and measurements of a radar cross section of a Boeing 747-200 in the 20–60 MHz frequency band  

Microsoft Academic Search

HF and VHF low frequency bands provide a promising way to perform radar target recognition. At these frequencies, Radar Cross Section (RCS) behavior is not well known because the scattered field is due to a complex phenomenon where the interactions between the different parts of the structure have a significant contribution, which makes the prediction difficult. A wire model of

A. David; C. Brousseau; A. Bourdillon

2003-01-01

100

Method based on physical optics for the computation of the radar cross section including diffraction and double effects of metallic and absorbing bodies modeled with parametric surfaces  

Microsoft Academic Search

A method to compute the monostatic radar cross section (RCS) of complex bodies modeled by nonuniform rational B-spline (NURBS) surfaces is presented. The bodies can be covered by any kind of radar absorbing material (RAM) with electric and\\/or magnetic losses. Physical optics (PO) is used to obtain the scattered field of each surface. Fresnel coefficients are included in the stationary

Francisco Saez de Adana; Iván González Diego; Oscar Gutiérrez Blanco; Pablo Lozano; Manuel F. Cátedra

2004-01-01

101

Computation of RCS from a flat plate covered with radar absorbing material  

Microsoft Academic Search

Since the early 1980s, the electromagnetic stealth technique has been developed for reducing the radar cross section (RCS) of aircraft based on two principal methods. One is to cover the aircraft with a radar absorbing material (RAM), the other is to modify the aircraft shape. The scattering from an arbitrary flat plate of electrically large dimensions and coated with a

Liang Chao Wu; Wen Xun Zhang; Mao Guang Wang

1995-01-01

102

Coherent FM-CW millimeter-wave radar systems for radar cross-section measurements  

Microsoft Academic Search

Coherent instrumentation radars have been developed at 35 GHz and 94 GHz for use in radar-cross-section measurements at angles of incidence ranging from 0° to 60°. The systems are designed to measure the radar cross section of various targets, at like- and cross-polarizations, in an effort to better understand their scattering characteristics. Both are dual-antenna systems capable of operating in

R. T. Lawner; P. F. Blanchard; S. P. Gogineni

1989-01-01

103

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

104

Design and fabrication of a microstrip patch antenna with a low radar cross section in the X-band  

NASA Astrophysics Data System (ADS)

In this study, the authors developed a radar absorbing method to reduce the antenna radar cross section (RCS) without any loss of antenna performance. The new method was based upon an electromagnetic bandgap (EBG) absorber using conducting polymer (CP). First, a microstrip patch antenna was made by using a copper film and glass/epoxy composite materials, which are typically used for load-bearing structures, such as aircraft and other vehicles. Then, CP EBG patterns were also designed that had a 90% electromagnetic (EM) wave absorbing performance within the X-band (8.2-12.4 GHz). Finally, the CP EBG patterns were printed on the top surface of the microstrip patch antenna. The measured radar absorbing performance of the fabricated patch antenna showed that the frontal RCS of the antenna declined by nearly 95% at 10 GHz frequency while the CP EBG patterns had almost no effect on the antenna's performance.

Jang, Hong-Kyu; Lee, Won-Jun; Kim, Chun-Gon

2011-01-01

105

Radar and wind turbines — RCS theory and results for objects on the ground and in finite distances  

Microsoft Academic Search

This paper describes the application of the numerical scattering analysis embedded into systems simulations for navi- gation and radar systems. A special focus is on the theory and application and the numerical scattering analysis of the Radar Cross Section RCS for wind turbines WT. WT are installed on the ground and are in the mutual near field of the radar

G. Greving; W.-D. Biermann; R. Mundt

2011-01-01

106

Evaluation of RFID tag antenna performance using radar cross sections  

Microsoft Academic Search

Evaluation of a RFID tag antenna performance using RCS is shown to be very effective compared with that based on a detection distance. A tag antenna of which impedance is 35Q at 911MHz is designed and its performances are evaluated by RCS'. The procedures to obtain RCS' by EM simulation are described in detail. How to interpret the tag RCS'

Hongil Kwon; Bomson Lee

2005-01-01

107

CFD spinoff - Computational electromagnetics for radar cross section (RCS) studies  

NASA Technical Reports Server (NTRS)

A finite-volume discretization procedure derived from proven CFD methods is used to solve the conservation form of the time-domain Maxwell's equations, in order to compute EM scattering from layered objects. This time-domain approach handles both single-frequency/continuous wave and broadband-frequency/pulse incident excitation. Arbitrarily shaped objects are modeled by means of a body-fitted coordinate transformation; complex internal/external structures with many material layers are treated through the implementation of a multizone framework capable of handling any type of zonal boundary condition. Results are presented for various two- and three-dimensional problems.

Shankar, Vijaya; Mohammadian, Alireza H.; Hall, William F.; Erickson, Roy

1990-01-01

108

Parallel computation of Radar Cross Section of target with coatings  

Microsoft Academic Search

This paper deals with the problem of RCS prediction of body with coatings using the method of Physical Optics (PO). In order to shorten the calculation time, this paper uses parallel computation mechanism which is based on MPI. The results show that it can effectively improve the calculation efficiency. Keywords—RCS; body with coatings; PO; MPI I. INTRODUCTION The significance of

Y. Yan; H. Zhao; Y. Zhang; X. W. Zhao; C. H. Liang; D. Garcia-Donoro; T. K. Sarkar

2011-01-01

109

Correlation between radar cross section and ballistic coefficient for orbiting objects  

NASA Astrophysics Data System (ADS)

The correlation between radar cross sections and ballistic coefficients for orbiting objects is studied using orbital element data from NORAD and radar cross section data from the radar systems at Eglin Air Force Base. The time variation of the orbital elements is used to calculate an accurate effective ballistic coefficient for representative orbiting objects of various sizes. These are compared with radar cross sections from several observations of the same object. The results of the study tend to support Kessler's conjecture that the correlation between radar cross section and effective area is poor in the absence of detailed information about the target and that the correlation is worse for the smallest detectable objects than for larger objects.

Culp, Robert D.; Dickey, Michael R.

110

A physical radar cross-section model for a wind-driven sea with swell  

Microsoft Academic Search

A new spectrum model for the ocean surface is proposed. We determine the two unknown parameters in this spectrum by fitting it to radar observations. We find that this spectrum combined with two-scale scattering theory can predict much of the observed dependence of the radar cross section on radar frequency, polarization, angle of incidence, and wind velocity at incidence angles

S. Durden; J. Vesecky

1985-01-01

111

Radar Cross Section Studies/Compact Range Research.  

National Technical Information Service (NTIS)

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...

W. D. Burnside A. K. Dominek I. J. Gupta E. H. Newman P. H. Pathak

1988-01-01

112

The Radar Cross Sections of ‘Spongy’ Ice Spheres  

Microsoft Academic Search

By means of the complete Mie equations, calculations have been made of the backscattering of 3.21-cm microwaves by 'spongy' ice spheres, that is, ice spheres composed of a homogeneous mixture of water and ice. It is found that as the percentage of water is in- creased the cross sections of spheres of diameter greater than about 3 cm decrease fairly

Louis J. Battan; Benjamin M. Herman

1962-01-01

113

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

114

The Radar Cross Section and wind turbines - definition and effects of the ground and finite distances  

Microsoft Academic Search

This paper describes the application of the numerical scattering analysis em- bedded into systems simulations for navigation and radar systems. A special focus is on the theory and application and the numerical scattering analysis of the Radar Cross Sec- tion RCS for wind turbines WT. WT are installed on the ground and are in the mutual near field of the

G. Greving; W.-D. Biermann; R. Mundt

2011-01-01

115

On radar cross-section of the Sun during earthward-directed CME  

Microsoft Academic Search

In order to design radar experiments for the study of the Sun, it is necessary to make some preliminary estimates. We report results of crude calculations of the solar radar cross section during the appearance of a geoeffective CME. For the calculations, we consider the CME to be a spherical expanding plasma shell with a constant mass moving towards the

Yu. I. Belov; S. M. Grach; P. Rodriguez; B. Thide; Yu. V. Tokarev

2003-01-01

116

Radar cross section measurements (8-12 GHz) of flat plates painted with microwave absorbing materials  

Microsoft Academic Search

The aim of the present work is to present radar cross section measurements of flat plates painted with radar absorbing material (RAM) in the range of 8-12 GHz. The measurements were carried out in an anechoic chamber at Centro Tecnico Aeroespacial (CTA)-Ministerio da Defesa facilities, and the RAM coating was manufactured at Divisao de Materiais of Instituto de Aeronautica e

M. C. Rezende; I. M. Martin; M. A. S. Miacci; E. L. Nohara

2001-01-01

117

Importance of the sea surface curvature to interpret the normalized radar cross section  

Microsoft Academic Search

Asymptotic models (small perturbation and small slope approximation at first-order, Kirchhoff approximation or two-scale model) used to predict the normalized radar cross section of the sea surface generally fail to reproduce in detail backscatter radar measurements. In particular, the predicted polarization ratio versus incidence and azimuth angles is not in agreement with experimental data. This denotes the inability of these

A. A. Mouche; B. Chapron; N. Reul; D. Hauser; Y. Quilfen

2007-01-01

118

Radar Background Signal Reduction Study.  

National Technical Information Service (NTIS)

This report summarizes a study whose objective was to identify materials and/or techniques to reduce radar background signals for ground plane radar cross section (RCS) ranges. Background signal reduction is essential for improving the accuracy of RCS mea...

E. F. Knott C. J. Ray M. S. West R. J. Wohlers

1980-01-01

119

Simulations and measurements of a radar cross section of a Boeing 747-200 in the 20-60 MHz frequency band  

NASA Astrophysics Data System (ADS)

HF and VHF low frequency bands provide a promising way to perform radar target recognition. At these frequencies, Radar Cross Section (RCS) behavior is not well known because the scattered field is due to a complex phenomenon where the interactions between the different parts of the structure have a significant contribution, which makes the prediction difficult. A wire model of a commercial Boeing 747-200 aircraft, developed to be used with the Numerical Electromagnetic Code (NEC), is presented. The reliability of this model has been assessed by comparing the results given by NEC with the measurements made in an anechoïc chamber with a scaled aircraft, and a relatively good agreement was observed between simulations and measurements. The RCS variations of an aircraft along different flight routes have been investigated, and it is shown that it is necessary to know the flight route of the airplane to envisage target identification in spite of the use of the low frequency band.

David, A.; Brousseau, C.; Bourdillon, A.

2003-08-01

120

Simulations of the radar cross section of a generic air-to-air missile coated with radar absorbing materials  

Microsoft Academic Search

Simulations of the radar cross section of a heat- seeking air-to-air missile model were performed using the CADRCS software. In these simulations at a frequency of 10 GHz, the surface of the missile was considered to be a perfect conductor and to be coated with a radar absorbing material (RAM). The comparison of results from the simulations shows how different

Mauro A. Alves; Guilherme G. Peixoto; Mirabel C. Rezende

2007-01-01

121

Relationship between wind vectors and L-band radar cross sections examined using PALSAR  

Microsoft Academic Search

The relationship between ocean wind vectors and L-band normalized radar cross sections (NRCS) is examined using the Phased-Array L-band Synthetic Aperture Radar (PALSAR). We used PALSAR ScanSAR images with a wide range of incidence angles from 17deg to 43deg. More than 6,000 match-ups, each consisting of the NRCS, incidence angles, wind speeds and wind directions, were collected. The NRCS exhibits

Osamu Isoguchi; Masanobu Shimada

2007-01-01

122

Simultaneous measurements of ku- and ka-band sea surface cross sections by an airborne Radar  

Microsoft Academic Search

The dual-frequency Airborne Precipitation Radar-2 (APR-2) was deployed during the Wakasa Bay Experiment in 2003, for validation of the Advanced Microwave Scanning Radiometer-EOS. Besides providing extensive observations of diverse precipitating systems, this Ku-(13.4 GHz) and Ka-band (35.6 GHz) cross-track scanning radar measured sea surface backscatter simultaneously. While the characteristics of the normalized sea surface cross section sigma0 at Ku-band are

Simone Tanelli; Stephen L. Durden; E. Im

2006-01-01

123

Validation through comparison: Measurement and calculation of the bistatic radar cross section of a stealth target  

Microsoft Academic Search

Bistatic radar cross section (BRCS) values of a stealth airborne target are predicted by performing both scaled-model measurements and numerical simulations. In order to achieve the solution of large-scale electromagnetic problems in the numerical simulation environment, the fast multipole method (FMM) is implemented and used. The FMM has produced remarkably accurate results, in addition to its efficiency. The efficiency of

L. Gürel; H. BagùcØ; J. C. Castelli; A. Cheraly; F. Tardivel

2003-01-01

124

Statistics of the laser radar cross section of a randomly rough target  

Microsoft Academic Search

The problem of calculating the laser radar cross section of a randomly rough target is studied. It is shown that subject to a minimum set of assumptions, all with reasonable physical interpretation, the statistics are Rician for any degree of roughness. A rigorous theory is developed to allow the two parameters of the Rician distribution to be calculated for any

D. L. Fried

1976-01-01

125

Robust separation of background and target signals in radar cross section measurements  

Microsoft Academic Search

Coherent measurements of radar cross-section on a target moving along the system line-of-sight in free space will trace a circle centered on the origin of the complex (I,Q) plane. The presence of additional complex background signals (including stationary clutter, target support, and averaged target-mount interactions), which do not depend on target position, will translate the origin of the circle to

Lorant A. Muth; Chih-Ming Wang; Timothy Conn

2005-01-01

126

Standard Deviation of Spatially-Averaged Surface Cross Section Data from the TRMM Precipitation Radar  

NASA Technical Reports Server (NTRS)

We investigate the spatial variability of the normalized radar cross section of the surface (NRCS or Sigma(sup 0)) derived from measurements of the TRMM Precipitation Radar (PR) for the period from 1998 to 2009. The purpose of the study is to understand the way in which the sample standard deviation of the Sigma(sup 0) data changes as a function of spatial resolution, incidence angle, and surface type (land/ocean). The results have implications regarding the accuracy by which the path integrated attenuation from precipitation can be inferred by the use of surface scattering properties.

Meneghini, Robert; Jones, Jeffrey A.

2010-01-01

127

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

NASA Technical Reports Server (NTRS)

A modified version of the surface-target-attenuation radar described by Meneghini et al. (1983) is proposed which permits simultaneous measurement of ocean radar cross sections and path-average rain rates using a nadir-pointing satellite-borne microwave radar. The basic concept is explained and illustrated; the equations describing the data reduction are derived; some preliminary numerical computations based on a 7.5-m-diameter 10-kW 1.33-microsec-pulse radar operating at 1.87 cm from an altitude of 500 km are performed; and the major error sources (mismatches between rain scattering volumes and additional multipath contributions) and limitations (nadir pointing) are discussed. It is suggested that the system could provide a nadir calibration for wide-swath observing systems such as scanning microwave radiometers.

Atlas, D.; Meneghini, R.

1983-01-01

128

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

129

Reduced backscattering cross section (Sigma degree) data from the Skylab S-193 radar altimeter  

NASA Technical Reports Server (NTRS)

Backscattering cross section per unit scattering area data, reduced from measurements made by the Skylab S-193 radar altimeter over the ocean surface are presented. Descriptions of the altimeter are given where applicable to the measurement process. Analytical solutions are obtained for the flat surface impulse response for the case of a nonsymmetrical antenna pattern. Formulations are developed for converting altimeter AGC outputs into values for the backscattering cross section. Reduced data are presented for Missions SL-2, 3 and 4 for all modes of the altimeter where sufficient calibration existed. The problem of interpreting land scatter data is also discussed. Finally, a comprehensive error analysis of the measurement is presented and worst case random and bias errors are estimated.

Brown, G. S.

1975-01-01

130

Modulation of sea surface radar cross section by surface stress: Wind speed and temperature effects across the Gulf Stream  

SciTech Connect

During the past several years, many radars (Moskowitz, 1973; Larson et al., 1976) have observed the distinct and interesting features associated with the Gulf Stream and its boundaries. Some of these Gulf Stream radar features are small scale, with dimensions comparable to and slightly greater than long gravity waves. Other features are larger, with dimensions much greater than the length of long gravity waves. This study describes radar cross-section variations within the Gulf Stream and just outside, seen with a 'scatterometer' type measurement. The significant features of these radar cross-section data were that the Gulf Stream always had a higher cross section per unit area (interpreted here as a greater roughness) than the water on the continental shelf. Also, a steep gradient in cross section often was seen at the expected location of the western boundary. There also were longer scale (10--20 km) gradual fluctuations within the stream. These roughness variations are correlated with the surface shear stress that the local wind imposes on the sea. By using the available surface truth information regarding the wind speed and direction, an assumed Gulf Stream velocity profile and high-resolution ocean surface temperature data obtained by the very high resolution radiometer on board a NOAA polar-orbiting satellite, profiles of sea surface stress were calculated for comparison with radar cross-section data. This study demonstrates that the measured radar cross-section variations are correlated with computed surface stress and that both surface-air temperatures and surface winds are important factors in determining surface stress and radar cross section.

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

1980-09-20

131

Relative RADAR cross section based feature identification with millimeter wave RADAR for outdoor SLAM  

Microsoft Academic Search

Millimeter wave RADARs are more robust than most other sensors used in outdoor autonomous navigation in that their performance is less affected by dust, fog, moderate rain or snow and ambient lighting conditions. Millimeter wave (MMW) RADAR differs from other range sensors as it can provide complete power returns for many points down range. Im addition, MMW RADAR has a

E. Jose; M. D. Adams

2004-01-01

132

Measurements of the Effect of Rain-Induced Sea Surface Roughness on the QuikSCAT Scatterometer Radar Cross Section  

Microsoft Academic Search

Radar measurements of the sea surface, with satellite scatterometers that operate at Ku-band, are affected by the presence of rain through modification of the sea surface roughness by rain impacts. This is in addition to wind driven roughness, atmospheric scattering, and attenuation that affect the measured normalized radar cross section (NRCS). This paper presents a case study of the increase

David E. Weissman; Mark A. Bourassa

2008-01-01

133

Fabrication of Radar Absorbing Structure and Evaluation of Radar Cross Section: Case Study of Hybrid Shells  

Microsoft Academic Search

Fiber-reinforced composite materials have outstanding mechanical and electrical properties; their applications have been expanded to commercial products as well as military components. Using composite materials, researchers have studied the radar absorbing, or `stealth' technology. In this research, to develop the radar absorbing structure (RAS), hybrid composite materials are fabricated into three-dimensional `C' and `U' shape shells. A series of experiments

Woo-Kyun Jung; Sung-Hoon Ahn; Bierng-Chearl Ahn; Seoung-Bae Park; Myung-Shik Won

2007-01-01

134

The Effects of Plasma Shield on the Radar Cross Section of a Generic Missile in UHF Band  

NASA Astrophysics Data System (ADS)

RF Stealth is the dominant technology in today's military aircraft, and most is achieved by shape design with a few reductions achieved by RAM, but most of these effects are only valid in X band. With the popularity of UHF radar again rising, the possibility of detecting a stealth object has increased due to resonance effect, and this is difficult to decrease with previous means due to the long wavelength. A plasma shield generated in front of an object may be suitable to alter the RCS in specific band without physically changing its shape. We examine the RCS of a generic missile in UHF band, and compared it with one with a cone-shape plasma generated in front of the missile. We find the plasma effectively changes the RCS of the missile, though not necessarily smaller. The RCS of the missile with the plasma shield is now dominated by the plasma instead of the missile. The RCS is a function of the size, shape, and density of the plasma shield. For higher frequency signals like the X band radar, it can still penetrate the plasma, and sees the original RCS of the missile. Due to the relatively lower UHF frequency, the plasma density needed is lower than one in X band and thus more practical to achieve.

Chung, Shen Shou Max

2011-11-01

135

Scale factors of RCS for lossy targets  

Microsoft Academic Search

The paper presents the scale factor of the radar cross section (RCS) for lossy targets from which the RCS of a complex lossy target can be calculated in terms of scale-model testing, even though the model does not satisfy similarity because of coated absorbent materials. It is proposed that the absorbent materials must be coated on conducting bodies completely.

Zhendong Shi

1992-01-01

136

Scale factors of RCS for lossy targets  

NASA Astrophysics Data System (ADS)

The paper presents the scale factor of the radar cross section (RCS) for lossy targets from which the RCS of a complex lossy target can be calculated in terms of scale-model testing, even though the model does not satisfy similarity because of coated absorbent materials. It is proposed that the absorbent materials must be coated on conducting bodies completely.

Shi, Zhendong

1992-06-01

137

RCS reduction of Vivaldi antenna array using a PSS boundary  

Microsoft Academic Search

Phase-switched screen (PSS) is a novel technique proposed recently for radar cross section (RCS) reduction. Different from conventional radar absorbing materials (RAM), PSS technique modulates in phase the scattered waves using a switching signal and redistributes the scattered energy in a wider band, enabling dynamic control of RCS.

Guoquan Zhang; Liming Xu; Aixin Chen

2008-01-01

138

Backscattering Cross Section of Ultrawideband Antennas  

Microsoft Academic Search

Backscattering of ultrawideband (UWB) antennas is theoretically and experimentally studied in this letter. The finite-difference time-domain (FDTD) method using Berenger's perfectly matched layer absorbing boundary condition (PML-ABC) is employed for simulation and the measurement is carried out in indoor environment. Monostatic radar cross section (RCS) of square-slot antenna and printed circular-disc monopole antenna (PCDMA) terminated with three different kinds of

Sanming Hu; Honghui Chen; C. K. Law; Z. Shen; L. Zhu; W. Zhang; W. Dou

2007-01-01

139

Using a Kernel Adatron for Object Classification with RCS Data.  

National Technical Information Service (NTIS)

Rapid identification of object from radar cross section (RCS) signals is important for many space and military applications. This identification is a problem in pattern recognition which either neural networks or support vector machines should prove to be...

E. A. Rietman J. T. Demers M. F. Byl

2010-01-01

140

Correction of Sampling Errors in Ocean Surface Cross-Sectional Estimates from Nadir-Looking Weather Radar  

NASA Technical Reports Server (NTRS)

The return from the ocean surface has a number of uses for airborne meteorological radar. The normalized surface cross section has been used for radar system calibration, estimation of surface winds, and in algorithms for estimating the path-integrated attenuation in rain. However, meteorological radars are normally optimized for observation of distributed targets that fill the resolution volume, and so a point target such as the surface can be poorly sampled, particularly at near-nadir look angles. Sampling the nadir surface return at an insufficient rate results in a negative bias of the estimated cross section. This error is found to be as large as 4 dB using observations from a high-altitude airborne radar. An algorithm for mitigating the error is developed that is based upon the shape of the surface echo and uses the returned signal at the three range gates nearest the peak surface echo.

Caylor, I. Jeff; Meneghini, R.; Miller, L. S.; Heymsfield, G. M.

1997-01-01

141

Research into Influence of Gaussian Beam on Terahertz Radar Cross Section of a Conducting Cylinder  

NASA Astrophysics Data System (ADS)

In RCS measurement, usually the incident beam is a Gaussian beam or a similar beam source; however, in the theoretical RCS estimation, usually a plane wave is assumed as the incident beam for sake of simplicity. In this paper, the RCS of an infinite perfect conducting cylinder is estimated. In the estimation, the influence of a 2.52 THz laser beam on RCS is studied and the RCS in dependence with scattering angle and some other factors is obtained after the change of RCS equation; meanwhile, comparisons of RCS when the incident beam is a plane wave and a Gaussian beam respectively, are also given. The estimation results show, when the cylinder radius is 10 mm, choosing a beam width of 40 mm can keep the relative error less than 0.48 dB.

Li, Hui-Yu; Li, Qi; Xue, Kai; Zhao, Yong-Peng; Chen, De-Ying; Wang, Qi

2013-04-01

142

ENDO atmospheric EXO atmospheric radar modeling. Radar cross section modeling, appendix L  

Microsoft Academic Search

This effort is concerned with the development and inplementation of a set of digital computer programs that will augment the RADC digital computer radar simulation model procured under Contract F30602-72-C0393 (01707201). The computer programs shall consist of a sequence of subroutines that correspond to separate functions such as a chaff model, target model, propagation effects, and clutter model. The original

R. J. Hancock; F. H. Cleveland

1976-01-01

143

Meander line RFID tag at UHF band evaluated with radar cross sections  

Microsoft Academic Search

This paper presents a meander line RFID tag antenna operating at UHF band. The proposed inductively-coupled tag can be easily designed to have a specific antenna impedance. The designed antenna impedance is 77+j100? at 911 MHz. The performance of the antenna is evaluated by monitoring RCS' corresponding to varied chip impedances. The procedures to determine RCS by EM simulation are

Hongil Kwon; Bomson Lee

2005-01-01

144

Ambiguity Function of the Stepped Frequency Radar.  

National Technical Information Service (NTIS)

High range resolution radar systems have many advantages such as target classification, resolution of multiple target, accurate range profile and detection of low radar cross section (RCS) targets in clutter. High range resolution requires large bandwidth...

J. C. Huang

1994-01-01

145

Partial treatment of wind turbine blades with radar absorbing materials (RAM) for RCS reduction  

Microsoft Academic Search

The application of radar absorbing materials (RAM) in order to reduce the interference of wind farms with radar systems is considered as a possible mitigation solution. This paper will address the key challenges when trying to efficiently apply RAM to certain parts of the wind turbine blades to significantly reduce the scattering of radar signals. Modeling of the radar cross-section

Laith Rashid; Anthony Brown

2010-01-01

146

RCS measurement of wind turbines  

Microsoft Academic Search

A set of measurements has recently been undertaken in the UK with the aim of determining the RCS (Radar Cross Section) of typical wind turbines, both in an isolated location, and within a wind farm. The measurements made use of a triband channel sounder, employing 10 MChip\\/s PN sequence with off-line correlation. The results from this campaign are presented, with

Richard Rudd; Bal Rhandawa

2009-01-01

147

RCS analysis code for complex targets modelled with NURBS surfaces  

Microsoft Academic Search

In this communication a FORTRAN code, RANURS, to analyze the Radar Cross Section (RCS) of electrically large complex targets is presented. The scattered fields is calculated by using PO+PTD approach. The following contributions to the RCS are taken into account: reflected and diffracted fields, double reflected and diffracted-reflected fields. The targets are modelled by using curved patches (NURBS). In addition

M. F. Catedra; R. P. Torres; F. Rivas; J. Perez; M. Domingo

1993-01-01

148

Alignment and illumination issues in scaled THz RCS measurements  

Microsoft Academic Search

Radar cross section (RCS) measurements are widely employed for the target identification of objects such as aircraft. The RCS of large, complex geometries is usually determined in a well defined, scaled experimental setup. In such a setup, the measuring frequency equates the frequency of interest multiplied by the scaling factor of the model. For high scaling factors, frequencies well above

C. Jansen; N. Krumbholz; R. Geise; T. Probst; O. Peters; A. Enders; M. Koch

2009-01-01

149

On the Development of a Second-Order Bistatic Radar Cross Section of the Ocean Surface: A High-Frequency Result for a Finite Scattering Patch  

Microsoft Academic Search

The development of a model for the second-order bistatic high-frequency (HF) radar cross section on an ocean surface patch remote from the transmitter and receiver is addressed. A new approach is taken that allows a direct comparison with existing monostatic cross sections for finite regions of the ocean surface. The derivation starts with a general expression for the bistatically received

Eric Gill; Weimin Huang; John Walsh

2006-01-01

150

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

151

Research on Typical Millimeter Wave Radar Target Characteristic  

Microsoft Academic Search

The advantage of millimeter wave radar, radar cross section (RCS) and one dimension range profile are presented at this paper. With the high frequency approximate method, the typical millimeter wave (35 GHz, 94 GHz) radar target characteristics are simulated. With the comparison, it is found that the target's radar cross section at 94 GHz has more details and evident scattering

Liu Yan; Su Donglin; Fang Xiang; Zeng Guoqi

2006-01-01

152

Simultaneous Ocean Cross-Section and Rainfall Measurements from Space with a Nadir-Pointing Radar.  

National Technical Information Service (NTIS)

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 scattere...

R. Meneghini D. Atlas

1984-01-01

153

Radar cross-section study of cylindrical cavity-backed apertures with outer or inner material coating: the case of H-polarization  

Microsoft Academic Search

A dual-series-based solution is obtained for the scattering of an H-polarized plane wave from a slitted infinite circular cylinder coated with absorbing material from inside or outside. For both cases, numerical results are presented for the radar cross section and comparisons are given for two different realistic absorbing materials. The radar cross-section dependencies are also given for the aspect angle

Dilek Colak; Alexander I. Nosich; Ayhan Altintas

1995-01-01

154

Nonsinusoidal radar signal design for stealth targets  

Microsoft Academic Search

The detection of stealth point targets challenges the design of conventional radars using sinusoidal carriers since the objective of stealth technology is to reduce the radar cross section (RCS) of targets to a level where the radar receiver cannot detect the target. While there are a number of techniques employing different technologies to reduce the RCS of targets, shaping and

Nasser J. Mohamed

1995-01-01

155

Imaging a BQM-74E Target Drone Using Coherent Radar Cross Section Measurements  

Microsoft Academic Search

ince the early 1980s and the advent of the modern computer, digital radar imaging has developed into a mature field. In this article, the specific problem of imaging a rotating target with a stationary radar is reviewed and built upon. The relative motion between the rotating target and the stationary radar can be used to create a circular synthetic aperture

Allen J. Bric

1997-01-01

156

Effect of Phase Errors in Stepped-Frequency Radar Systems.  

National Technical Information Service (NTIS)

Stepped-frequency waveforms are being considered for inverse synthetic aperture radar (ISAR) imaging from ship and airborne platforms and for detailed radar cross section (RCS) measurements of ships and aircraft. These waveforms make it possible to achiev...

H. E. VanBrundt

1988-01-01

157

The estimation of pointing angle and normalized surface scattering cross section from GEOS-3 radar altimeter measurements  

NASA Technical Reports Server (NTRS)

The statistical error of the pointing angle estimation technique is determined as a function of the effective receiver signal to noise ratio. Other sources of error are addressed and evaluated with inadequate calibration being of major concern. The impact of pointing error on the computation of normalized surface scattering cross section (sigma) from radar and the waveform attitude induced altitude bias is considered and quantitative results are presented. Pointing angle and sigma processing algorithms are presented along with some initial data. The intensive mode clean vs. clutter AGC calibration problem is analytically resolved. The use clutter AGC data in the intensive mode is confirmed as the correct calibration set for the sigma computations.

Brown, G. S.; Curry, W. J.

1977-01-01

158

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

159

A simple device for long-term radar cross section recordings  

NASA Astrophysics Data System (ADS)

A sample and hold circuit with settable delay can be used for recording of radar echo amplitude variations having time scales up to 100 s at the selected range bin in systems utilizing short rf pulses. The design is based on two integrated circuits and gives 1% uncertainty for 70 ns pulses. The key benefit is a real-time display of lengthy amplitude variations because the sample rate is defined by the radar pulse repetition frequency. Additionally we get a reduction in file size at least by the inverse of the radar's duty cycle. Examples of 10 and 100 s recordings with a Ka-band short pulse radar are described.

Eskelinen, Pekka; Ruoskanen, Jukka; Peltonen, Jouni

2009-05-01

160

Reduction of the radar cross section of a wind turbine using a microwave absorbing material  

Microsoft Academic Search

Wind turbines are devices which usually have a large surface area. The combination of effects related to the large surface area and properties of the materials used in their construction can make a wind turbine an important reflector of radar waves, which may interfere with the proper operation of civilian and military radars. There are several possible methods to reduce

Mauro A. Alves; Luiza C. Folgueras; Mirabel C. Rezende

2011-01-01

161

UHF-band inductively-coupled RFID antenna with near-isotropic radar cross section patterns  

Microsoft Academic Search

This paper presents a RFID tag antenna at 911 MHz which has near-isotropic radiation patterns and easy conjugate impedance matching property by adopting an inductively- coupled feeding. With a typical antenna impedance of 2+j146Omega, the proposed tag of compact size 40 x 46 mm(0.12x0.14lambda) has the simulated maximum and minimum RCS' of -16.75 dBm2 and -21.47dBm2, respectively, depending on the

Hyungmin Jang; Bomson Lee

2007-01-01

162

Analysis of normalized radar cross section (sigma-O) signature of Amazon rain forest using SEASAT scatterometer data  

NASA Technical Reports Server (NTRS)

The normalized radar cross section (NRCS) signature of the Amazon rain forest was SEASAT scatterometer data. Statistics of the measured (NRCS) values were determined from multiple orbit passes for three local time periods. Plots of mean normalized radar cross section, dB against incidence angle as a function of beam and polarization show that less than 0.3 dB relative bias exists between all beams over a range of incidence angle from 30 deg to 53 deg. The backscattered measurements analyzed show the Amazon rain forest to be relatively homogeneous, azimuthally isotropic and insensitive to polarization. The return from the rain forest target appears relatively consistent and stable, except for the small diurnal variation (0.75 dB) that occurs at sunrise. Because of the relative stability of the rain forest target and the scatterometer instrument, the response of versus incidence angle was able to detect errors in the estimated yaw altitude angle. Also, small instrument gain biases in some of the processing channels were detected. This led to the development of an improved NRCS algorithm, which uses a more accurate method for estimating the system noise power.

Bracalente, E. M.; Sweet, J. L.

1984-01-01

163

METRRA Signature - Radar Cross Section Measurements. Final Report/Instruction Manual.  

National Technical Information Service (NTIS)

The acronym METRRA represents 'Metal R-Radiating Radar'. The METRRA signature tests result from a third harmonic system, since the receive frequency is three times that of the transmit frequency. Of particular significance is METRRA's inherent ability to ...

D. A. Dauben D. Hull

1978-01-01

164

A radar cross-section model for power lines at millimeter-wave frequencies  

Microsoft Academic Search

The knowledge of radar backscatter characteristics of high-voltage power lines is of great importance in the development of a millimeter-wave wire detection system. In this paper, a very high-frequency technique based on an iterative physical optics approach is developed for predicting polarimetric radar backscattering behavior of power lines of arbitrary strand arrangement. In the proposed scattering model the induced surface

K. Sarabandi

2003-01-01

165

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

NASA Technical Reports Server (NTRS)

In the case of a nadir-looking spaceborne or aircraft radar in the presence of rain, the return power corresponding to secondary surface scattering may provide information on the properties of the surface and the precipitation. The object of the study is to evaluate a method for determining simultaneously the rainfall rate and the backscattering coefficient of the surface. The method is based upon the mirror-reflected power, 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.

Meneghini, Robert; Atlas, David

1986-01-01

166

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

167

RCS Reduction of Ridged Waveguide Slot Antenna Array Using EBG Radar Absorbing Material  

Microsoft Academic Search

This letter investigates the application of EBG radar absorbing material (RAM) to asymmetric ridged waveguide slot antenna array to reduce its backward RCS. The EBG RAM is based on the mushroom-like EBG structure loaded with lumped resistances. A ridged waveguide slot antenna array with 4 times 10 slot elements was designed and built, part of the metal ground plane of

You-Quan Li; Hui Zhang; Yun-Qi Fu; Nai-Chang Yuan

2008-01-01

168

Radar observables  

NASA Astrophysics Data System (ADS)

A comprehensive account is given of missile design considerations relevant to the prediction, control, and measurement of airframe radar cross sections (RCSs), with a view to the minimization of missile observability. RCS reduction may proceed through airframe shaping to deflect incident radar emissions, as well as through the use of radar-absorbing surface materials and the devision of active radar signal-cancellation methods; some combination of these is often required, due to the deficiencies of any one method. The interaction of all RCS-reduction methods with airframe aerodynamic-design criteria are stressed.

Knott, Eugene F.

169

APPLICATION OF DOUBLE ZERO METAMATERIALS AS RADAR ABSORBING MATERIALS FOR THE RE DUCTION OF RADAR CROSS SECTION  

Microsoft Academic Search

We introduce and investigate the applications of double zero (DZR) metamaterials (having the real parts of permittivity and permeability equal to zero) as radar absorbing materials (RAMs). We consider a perfectly electric conductor (PEC) plate covered by several layers of DZR metamaterial coatings under an oblique plane wave incidence of arbitrary polarization. Several analytical formulas are derived for the realization

H. Oraizi; A. Abdolali; N. Vaseghi

2010-01-01

170

Interaction between radar systems and wind farms  

Microsoft Academic Search

At typical radar frequencies a wind turbine has a large radar-cross-section (RCS) and due to the movement of the blades, the wind turbine generates a Doppler spectrum. This scattering behaviour has caused concern with radar operators, particularly those working with safety critical radar and national defence. This paper presents results from a modelling tool developed by BAE systems, advanced technology

J. C. G. Matthews; C. Sarno; R. Herring

2008-01-01

171

CFRP-based broad-band Radar Absorbing Materials  

Microsoft Academic Search

Strong interest in radar absorbing materials (RAMs) took place with years due to their extensive sectors of application. RAMs are coatings whose electric and magnetic properties allow the absorption of microwave energy over certain frequencies. In particular, RAMs are very effective means of Radar Cross Section (RCS) reduction in the context of stealth technology. RCS reduction requires absorbers with broad-band

C. Mitrano; A. Balzano; M. Bertacca; M. Flaccavento; R. Mancinelli

2008-01-01

172

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

173

Application of improved Z-buffer technique to RCS computation  

Microsoft Academic Search

This paper presents a new method for computation of the monostatic radar cross section (RCS) of electrically large conducting\\u000a objects. Compared with the traditional Z-buffer technique, the improved one can record not only the illuminated surface of\\u000a the body, but also the information about the shadowed part. So multi-scattering and RCS of cavity can be calculated. The second\\u000a advantage of

Cao Qinfeng; Xu Penggen

1998-01-01

174

RCS and radar propagation near offshore wind farms  

Microsoft Academic Search

The wind farm impact on marine radars has not been widely reported. Some past publications have touched on the subject but there has been no accurate model in place to readily examine the effects of different farm geometries, tower shapes and turbine sizes. This paper discusses the radar propagation modeling near offshore wind farms including the methods used to model

Laith S Rashid; Anthony K Brown

2007-01-01

175

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

176

Radar Cross-Sectional Spectra of Rotating Multiple Skew-Plated Metal Fan Blades by Physical Optics\\/Physical Theory of Diffraction, Equivalent Currents Approximation  

Microsoft Academic Search

The monostatic radar cross-sectional spectra of rotating multiple skew-plated metal fan blades are investigated. The theoretical treatment of such a slowly rotating and electrically large scatterer is based on the quasi-stationary method together with physical optics\\/physical theory of diffraction (PO\\/PTD) equivalent current techniques. Only the thetatheta polarization case is considered here, but the \\\\psi\\\\psi polarization case can be treated in

Sheau-Shong Bor; Tai-Lin Yang; Shui-Yuan Yang

1992-01-01

177

Radar cross-section study of cylindrical cavity-backed apertures with outer or inner material coating: the case of E-polarization  

Microsoft Academic Search

A dual-series-based solution is obtained for the scattering of an E-polarized plane wave from a cavity-backed aperture which is formed by a slitted infinite circular cylinder coated with absorbing material. The material coating can be done on the inner or outer surface of the cylinder. For both cases, numerical results are presented for the radar cross section and comparisons are

Dilek Colak; Alexander I. Nosich; Ayhan AltintaS

1993-01-01

178

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

179

Improved RCS model for censored Swerling III and IV target models  

NASA Astrophysics Data System (ADS)

In radar tracking applications, it is often necessary to estimate the Radar Cross Section (RCS) of a target. This estimate is especially important for monopulse radar tracking systems where waveform selection and revisit times are dependent on this estimate. The conventional approach to estimating the RCS for Swerling III and IV (Chi-squared distributed) targets ignores censoring issues that arise from voltage clipping. A maximum likelihood estimator of the target RCS for Swerling III and IV targets for censored distributions is derived and compared to the conventional estimator.

Backes, Thomas; Smith, L. Donnie

180

Radar Cross-Section (RCS) Measurements of a Dismount With Rocket- Propelled Grenade (RPG) Launcher at Ka-Band.  

National Technical Information Service (NTIS)

The U.S. Army Research Laboratory's (ARL's) Radio Frequency and Electronics Division sponsored and conducted a series of measurements to characterize the millimeter wave (MMW) signatures of one Soldier carrying a rocket-propelled grenade (RPG) launcher wi...

S. R. Stratton R. L. Bender

2006-01-01

181

Modeling the impact of discrete clutter on airborne adaptive radar systems  

Microsoft Academic Search

This paper will examine the impact of discrete clutter on airborne adaptive radar systems using a hi-fidelity radar cross section (RCS) model of buildings. A realistic model of the RCS for different building designs with respect to incidence angle and operating frequency has been developed that captures the phenomenology necessary to study the impact of discrete clutter on adaptive signal

Steven C. McNeil; Jameson S. Bergin; Paul Techau

2006-01-01

182

The design of broadband radar absorbing surfaces  

Microsoft Academic Search

There has been a growing and widespread interest in radar absorbing material technology. As the name implies, radar absorbing materials or RAM's are coatings whose electric and magnetic properties have been selected to allow the absorption of microwave energy at discrete or broadband frequencies. In military applications low radar cross section (RCS) of a vehicle may be required in order

Go H. Suk

1990-01-01

183

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

184

ERS-1 scatterometer measurements. I. The relationship between radar cross section and buoy wind in two oceanic regions  

Microsoft Academic Search

Extensive European Remote Sensing Satellite (ERS-1) spacecraft scatterometer measurements were collocated within ±25 km of buoy measurements at midlatitudes and in the equatorial Pacific during 1992-1994. Two different directional functional forms for the geophysical model were fit to these measurements described by cross section maxima aligned and offset, with respect to the mean wind direction. The two models exhibit fits

C. L. Rufencach; John J. Bates; Stephen Tosini

1998-01-01

185

Low frequency RCS measurements with parallel plates  

NASA Astrophysics Data System (ADS)

A backscatter range made up of a parallel-plate transmission line and a frequency-domain network analyzer is presented and evaluated in terms of investigating the radar cross sections (RCSs) of aerospace components. The instrument measures 42 x 15 feet and is operated at frequencies of 0.1-1.0 GHz, and the quasi-TEM wave simulates free-space propagating conditions. VHF and UHF RCS measurements are possible with the instrument, and a low background signature is reported.

McGinn, V. P.; Mathis, D. R.; Smith, B. A.

186

A compact RCS-range based on a phase hologram for scale model measurements at sub-mm-wavelengths  

Microsoft Academic Search

The HUT Radio Laboratory develops a novel compact radar cross section (RCS) test range for scale model measurements. The test range is based on a phase hologram that converts the feed horn radiation to a plane wave. The measurements are performed using CW at 310 GHz in a quasi-monostatic radar configuration where the identical receiving and transmitting corrugated horn antennas

A. V. Raisanen; A. Lonnqvist; J. Mallat; E. Noponen; J. Ala-Laurinaho; J. Saily; T. Koskinen; J. Hakli

2003-01-01

187

GRECO: graphical electromagnetic computing for RCS prediction in real time  

Microsoft Academic Search

An innovative approach to computing the high-frequency radar cross sections (RCSs) of complex radar targets in real time, using a 3-D graphics workstation, is presented. The target (typically, an aircraft) is modeled with the I-IDEAS solid-modeling software, using a parametric-surface approach. The high-frequency RCS is obtained through physical optics (PO), the method of equivalent currents (MEC), the physical theory of

Juan M. Rius; M. Ferrando; L. Jofre

1993-01-01

188

Modulation of sea surface radar cross section by surface stress: Wind speed and temperature effects across the Gulf Stream  

Microsoft Academic Search

During the past several years, many radars (Moskowitz, 1973; Larson et al., 1976) have observed the distinct and interesting features associated with the Gulf Stream and its boundaries. Some of these Gulf Stream radar features are small scale, with dimensions comparable to and slightly greater than long gravity waves. Other features are larger, with dimensions much greater than the length

D. E. Weissman; T. W. Thompson; R. Legeckis

1980-01-01

189

Phase-hologram-based compact RCS test range at 310 GHz for scale models  

Microsoft Academic Search

A compact radar cross section (RCS) test range based on a phase hologram has been developed for scale-model measurements. The phase hologram converts the feed-horn radiation to a plane wave needed for RCS determination. The measurements are performed at 310 GHz using continuous-wave operation. A monostatic configuration is realized using a dielectric slab as a directional coupler. The main advantage

Anne Lönnqvist; Juha Mallat; Antti V. Räisänen

2006-01-01

190

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

191

Shooting and bouncing rays - Calculating the RCS of an arbitrarily shaped cavity  

Microsoft Academic Search

A ray-shooting approach is presented for calculating the interior radar cross section (RCS) from a partially open cavity. In the problem considered, a dense grid of rays is launched into the cavity through the opening. The rays bounce from the cavity walls based on the laws of geometrical optics and eventually exit the cavity via the aperture. The ray-bouncing method

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

1989-01-01

192

Combined Wind Vector and Sea State Impact on Ocean Nadir-Viewing Ku- and C-Band Radar Cross-Sections  

PubMed Central

The authors report the first results in studying the polarization anisotropy of the microwave backscatter from nadir observations provided by Jason-1 altimeter in both Ku- and C-band. A small but clear wind direction signal for wind speeds above 6 m/s is revealed. These azimuthal variations of radar cross-section increase with increasing wind speed up to 14 m/s. The signatures then level off at higher winds. These results extend, for the first time, recent theoretical improved scattering approximation, and point some similarities between scattering and emission mechanisms at nadir. The observed directional effect can thus be interpreted as a signature of the curvature anisotropy of wind-generated short-scale waves. Sensitivities to both wind speed and sea state are also reported in the present analysis.

Tran, Ngan; Chapron, Bertrand

2006-01-01

193

Performance of resonant radar target identification algorithms using intra-class weighting functions  

Microsoft Academic Search

The use of calibrated resonant-region radar cross section (RCS) measurements of targets for the classification of large aircraft is discussed. Errors in the RCS estimate of full scale aircraft flying over an ocean, introduced by the ionospheric variability and the sea conditions were studied. The Weighted Target Representative (WTR) classification algorithm was developed, implemented, tested and compared with the nearest

A. Mustafa

1985-01-01

194

Multi-frequency and multi-polarization measurements of water surface radar cross section and brightness temperature angular dependences  

NASA Astrophysics Data System (ADS)

In this paper the results of simultaneous and spatially coincident, multi-frequency, polarimetric, spatio-temporally collocated measurements of waved pool water surface microwave reflective (radar backscattering coefficient) and emissive (brightness temperature) characteristics angular dependences at 5.6GHz, 15GHz and 37GHz are presented. Angular measurements were carried out for various water surface roughness parameters at clear air, cloudy and rain conditions. For these measurements C-, Ku and Ka-band, polarimetric, combined scatterometric-radiometric systems were used, set jointly on a mobile buggy moving along the measuring platform. Structures, operational features and the main technical characteristics of the utilized systems are presented too. The paper has an aim as well to attract attention of interested researchers and to invite them to perform their own or joint researches using available devices and facilities.

Arakelyan, Artashes K.; Hambaryan, Astghik K.; Arakelyan, Arsen A.; Grigoryan, Melanya L.

2011-10-01

195

The ogive as a RCS compact range standard  

NASA Technical Reports Server (NTRS)

E- and H-plane radar cross section (RCS) patterns at 4 and 10 GHz are provided (based upon moment method calculations) for a perfectly conducting ogive to be used as a compact range verification standard. The dimensions of the ogive are 36 in. and 9.546 in. long with half tip angles of 15 deg and 20 deg, respectively. Comparison between the calculations and measurements are also provided.

Dominek, A.; Nguyen, T.

1989-01-01

196

A physical optics approach to near field RCS computations  

Microsoft Academic Search

\\u000a Abstract  The scattered field of a perfectly conducting body treated using a physical optics approach is obtained in near field in either\\u000a the monostatic or bistatic case. This approach opens new prospects for a broad range of applications in the areas of radar\\u000a cross section (rcs) and antennas. Numerical examples for simple shapes (circular and rectangular plates) are given. Remarkable\\u000a phenomena

Philippe Pouliguen; Laurent Desclos

1996-01-01

197

On radar accuracy using beam wave in random media  

Microsoft Academic Search

The accuracy of radar detection is measured in this paper through comparing the laser radar cross-section (LRCS) to RCS data for plane-wave incidence in free space. This is to study the performance of backscattering enhancement from conducting targets with finite size. LRCS is calculated using beam wave incidence propagating in a random medium. Targets are of large size with relatively

Hosam El-Ocla

2011-01-01

198

On the ability of rough surface scattering approximations to predict hydrodynamic modulation of the ocean radar cross section - A numerical study  

NASA Technical Reports Server (NTRS)

Scattering from the ocean surface at microwave frequencies is often described by the Bragg scattering model or the two-scale model. Here, the ability of these models to predict cross section modulation is investigated by comparing Bragg and two-scale cross-sections with cross sections calculated by a numerical electromagnetic approach. The numerical method is used as the standard of comparison. For slightly rough surfaces, the Bragg model is found to be very accurate, but for much rougher surfaces, the two-scale model is superior and should be used for calculating both the absolute cross section and the change in cross section due to spatial or temporal modulation of the ocean wave height spectrum. These results are relevant to the interpretation of SAR images of ocean surface phenomena which perturb the wave height spectrum at ripple wavelengths.

Durden, Stephen L.; Vesecky, John F.

1989-01-01

199

On the Statistical Analysis of the Radar Signature of the MQM-34D.  

National Technical Information Service (NTIS)

The report contains the results of an analysis of the radar signature of the MQM-34D target drone for seven aspect angle regions for a horizontally polarized measurements system. The radar cross section (RCS) and glint are compared with classical models. ...

J. W. Wright

1975-01-01

200

Analysis of the efficiency of radiation absorbing material at X-band by measurement of RCS of planes and cylinder in open field  

Microsoft Academic Search

This paper presents an analysis of the measurements of the electromagnetic scattering in open field at the frequency of 8.76 GHz through the radar cross section (RCS) in the bi-static condition. Three structures have been investigated: a plane plate, a dihedral angle of 95°, and a metallic massive cylinder, in all cases before and after application of the multilayer absorbing

S. M. L. da Silva; A. J. de Faro Orlando; M. C. Rezende

2005-01-01

201

High-frequency techniques for RCS prediction of plate geometries  

NASA Technical Reports Server (NTRS)

Several different high-frequency methods for modeling the radar cross sections (RCSs) of plate geometries are examined. The Method of Equivalent Currents and a numerically derived corner diffraction coefficient are used to model the RCS of a rectangular, perfectly conducting plate in nonprincipal planes. The Uniform Theory of Diffraction is used to model the RCS of a rectangular, perfectly conducting plate in principal planes. For the soft polarization case, first-order and slope-diffraction terms are included. For the hard polarization case, up to four orders of diffraction are included. Finally, the Uniform Theory of Diffraction for impedance wedges and the Impedance Boundary Condition are used to model the RCS of a coated, rectangular plate in principal planes. In most of the cases considered, comparisons are made between theoretical and experimental results.

Balanis, Constantine A.; Polka, Lesley A.

1991-01-01

202

Simulation assessment of RCS-aided multiple target tracking  

NASA Astrophysics Data System (ADS)

Closely-spaced (but resolved) targets pose a significant challenge for single-frame unique measurement-to-track data association algorithms. This is due to the similarity of the Mahalanobis distances between the closely-spaced measurements and tracks. Contrary to conventional wisdom, adding target feature information (e.g., target amplitude) does not necessarily improve the probability of correctly assigning measurements to tracks. In this paper, the theoretical limitations of using radar cross section (RCS) data to aid in measurement-totrack association are reviewed. The results of a high-fidelity simulation assessment of the benefits of RCSaided measurement-to-track association (using the Signal-to-Noise Ratio) are given and other possibilities for RCS-aided tracking are discussed. Namely, we show the analytical results of our investigation into using RCS information to determine the presence of merged measurements.

Dunham, Darin T.; Ehrman, Lisa M.; Blair, W. Dale; Frost, Susan A.

2007-08-01

203

RCS of ships and aircraft at HF frequencies  

NASA Astrophysics Data System (ADS)

Coastal radar operating at high frequency (HF) has the potential of monitoring iceberg movement and ship and aircraft traffic over a wide area of ocean. The HF radar cross-section of an aircraft-like scatterer of simple geometry is investigated. At these frequencies, the aircraft size is comparable to the wavelength. The aircraft radar cross-section (RCS) is obtained both by computation and by direct measurement. It is demonstrated that at low frequencies in the HF range, the dorsal fin is the dominant scatterer, but at high HF the fuselage can scatter more strongly than the dorsal fin. Aircraft often carry wire antennas for HF communication, and it is shown that such wires can dramatically alter the RCS of the aircraft near the resonant frequencies of the wire. The RCS of a ship modelled as a parallelepiped with mast is 20-30 decibels larger than that of an aircraft, and is dominated at low HF by the contribution of the mast.

Trueman, C. W.; Kubina, S. J.; Mishra, S. R.; Larose, C.

204

Radar backscattering from breaking wind waves: field observation and modelling  

Microsoft Academic Search

In this article, the results of a field study of the Ka-band (37.5 GHz) radar backscattering from breaking wind waves are presented. Radar and a video camera were simultaneously used to measure the radar cross section (RCS) of the whitecap zone and the characteristics of wave-breaking events. A comparison is made between absolute geometrical lengths, areas and orientations of the

Yury Yu. Yurovsky; Vladimir V. Malinovsky

2012-01-01

205

Radar backscattering from breaking wind waves: field observation and modelling  

Microsoft Academic Search

In this article, the results of a field study of the Ka-band (37.5 GHz) radar backscattering from breaking wind waves are presented. Radar and a video camera were simultaneously used to measure the radar cross section (RCS) of the whitecap zone and the characteristics of wave-breaking events. A comparison is made between absolute geometrical lengths, areas and orientations of the

Yury Yu. Yurovsky; Vladimir V. Malinovsky

2011-01-01

206

Group Cross Sections Calculations.  

National Technical Information Service (NTIS)

Just a few methods have been developped to compute multigroup cross-sections from ENDF data. We have developped an original method in order to get accuracy and to reduce the number of discretization points in the same time; this is why we have tried to us...

D. Verwaerde

1985-01-01

207

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

NASA Astrophysics Data System (ADS)

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 separation between the interference, which propagates directly from the transmitter to the receiver, and the target return is less than the Rayleigh resolution limit of the receiving antenna. This research presents the results of a parametric study of the ability of a forward-scatter radar to detect and measure the bearing of a large target, whose RCS is reduced via passive means. Super-resolution array processing techniques, particularly root-MUSIC (multiple signal classification), are used to overcome the traditional limitations resulting from the Rayleigh resolution limit of the antenna. The study compares the received power and the bearing measurement accuracy of the forward-scatter radar to that of an 'equivalent' monostatic radar system. The results indicate that forward-scatter radars enjoy advantages in detection and bearing measurement when the backscatter RCS of the target has been reduced and when the target is close to the baseline. The results also indicate that, through the use of super-resolution array processing, the capability of the forward-scatter radar to accurately measure the bearing of the target is dependent upon the amount of interference from the direct wave (i.e., the wave which propagates from the transmitter directly to the receiver) and the correlation between the direct wave and the target echo. Good bearing estimates can be achieved if the correlation coefficient is less than 0.95. Bearing measurements may be improved by suppressing the direct wave by either sidelobe control or null steering techniques.

Boyle, Robert J.; Wasylkiwskyj, Wasyl

1994-07-01

208

Analysis of impacts of various RAM on RCS of 3-D complex targets using the FEM-FMA [radar absorbing materials  

Microsoft Academic Search

The hybrid vector finite element method and fast multipole algorithm (FEM-FMA) are used to calculate the RCS of 3D complex targets coated with various radar absorbing materials (RAM). For a cone as an example, This work analyzes the impact of four canonical RAM coatings, including lossy isotropic, positive uniaxial anisotropic, negative uniaxial anisotropic and nanometer absorbing materials on the electromagnetic

Wang Pai; Zhou Lezhu; Tan Yanhua; Xia Mingyao

2004-01-01

209

Electromagnetic Wave Absorbing Technique Using Periodic Patterns for Low RCS Patch Array Antenna  

NASA Astrophysics Data System (ADS)

This paper presents an electromagnetic wave absorbing technique to reduce a radar cross-section (RCS) of a patch array antenna without compromising their antenna performance. The technique is based on periodic patterns, which is made of resistive materials. The 2×2 patch array antenna with a resonance frequency of 3.0 GHz was designed and fabricated. To reduce the RCS of the patch array antenna, the periodic patterns using a square patch element were proposed and applied to the surface between the four antenna patches. The printed lossy periodic patterns have radar absorbing performance at 12.0 GHz frequency. The measured results show that the lossy periodic patterns have no significant effect on the antenna radiation performance. On the other hand, the RCS is reduced by more than 98% compared to the conventional antenna at the target frequency.

Jang, Hong-Kyu; Lee, Yeon-Gwan; Shin, Jae-Hwan; Kim, Chun-Gon

2013-07-01

210

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.

Pinter, Nicholas

211

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.

2010-01-01

212

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

213

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

214

High-frequency techniques for RCS prediction of plate geometries  

NASA Technical Reports Server (NTRS)

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 (t much less than lambda), lossy dielectric is presented. The incorporation of higher-order, multiple diffractions and of multiply diffracted surface-waves is discussed in detail. It is demonstrated that these terms are crucial to obtaining an accurate model. Approximations that are used in the model are discussed. Suggestions for improvements to the model are made. Validation is provided via comparison with experimental data and a physical optics (PO) model.

Balanis, Constantine A.; Polka, Lesley A.

1993-01-01

215

Comparison between EISCAT UHF and VHF backscattering cross section  

Microsoft Academic Search

We present a comparison between the backscattering cross sections at 224 and 933 MHz measured with European Incoherent Scatter (EISCAT) radars during the passage of a discrete arc. It shows a difference of 2 orders of magnitude which cannot simply be explained by normal thermal ionospheric density fluctuations. We claim that the observed difference in the scattering cross sections is

B. Cabrit; H. Opgenoorth; W. Kofman

1996-01-01

216

Automatic recognition of ground radar targets based on target RCS and short time spectrum variance  

Microsoft Academic Search

This paper presents a novel feature vector to be used with a robust automatic target recognition (ATR) classifier designed for a ground surveillance radar. A three element feature vector has been used where features are based on radar audio signal of 100 milliseconds duration. The short feature length allows fast real-time implementation of the classifier. Classification is done using a

S. Liaqat; S. A. Khan; M. B. Ihsan; S. Z. Asghar; A. Ejaz; A. I. Bhatti

2011-01-01

217

RCS prediction from scattering matrix measurements  

Microsoft Academic Search

The radar cross-section measurement equipment described in this paper was designed as a research tool for use in radar discrimination studies. Measurements of the radar scattering matrix made for various bodies were then used to predict the radar cross section of the body for any arbitrary polarization. All measurements were made at X-band with both metal and dielectric covered models

J. A. Webb

1965-01-01

218

Difference between interaction cross sections and reaction cross sections  

SciTech Connect

We study the validity of the substitution of interaction cross sections for total reaction cross sections for a nucleus incident on a target nucleus at relativistic energies. We show that, for incident stable nuclei, the predicted difference between interaction and total reaction cross sections is large enough to probe the nuclear structure, particularly in a mass region of less than around 40. For analyses of the difference, we construct ''pseudo data'' for the reaction cross sections because empirical data are very limited at high energies. The construction of the pseudo data is based on our assumption that empirically unknown total reaction cross sections are precisely predicted by the phenomenological black-sphere model of nuclei that we developed recently. The comparison with the empirical interaction cross sections suggests a significant difference between the reaction and interaction cross sections for stable projectiles on a carbon target, which is of the order of 0-100 mb.

Kohama, Akihisa [RIKEN Nishina Center, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198 (Japan); Iida, Kei [RIKEN Nishina Center, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198 (Japan); Department of Natural Science, Kochi University, Kochi 780-8520 (Japan); Oyamatsu, Kazuhiro [RIKEN Nishina Center, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198 (Japan); Department of Media Theories and Production, Aichi Shukutoku University, Nagakute, Nagakute-cho, Aichi-gun, Aichi 480-1197 (Japan)

2008-12-15

219

Implementering av Algoritm foer Beraekning av Radarmalyta med NURBS-ytor (Implementation of Algorithm for Calculation of Radar-Cross-Section Using NURBS-Surfaces).  

National Technical Information Service (NTIS)

NURBS (Non Uniform Rational B-Spline) is a powerful and often used method for a mathematical description of curves, surfaces and bodies in general. By using NURBS-surfaces an accurate object description can be kept further into the calculations of radar c...

M. Gustafsson S. Nilsson J. Rahm E. Zdansky

2001-01-01

220

RCS analysis and reduction for lossy dihedral corner reflectors  

NASA Technical Reports Server (NTRS)

The radar-cross-section (RCS) patterns of lossy dihedral corner reflectors are calculated, using a uniform geometrical theory of diffraction for impedance surfaces. All terms of up to third-order reflections and diffractions are considered for patterns in the principal plane. The surface waves are included whenever they exist for reactive surface impedances. The dihedral corner reflectors examined have right, obtuse, and acute interior angles, and patterns over the entire 360 deg azimuthal plane are calculated. The surface impedances can be different on the four faces of the dihedral corner reflector; however, the surface impedance must be uniform over each face. Computed cross sections are compared with the results of a moment-method technique for a dielectric/ferrite absorber coating on a metallic corner reflector.

Griesser, Timothy; Balanis, Constantine A.; Liu, Kefeng

1989-01-01

221

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

222

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

223

Radar targets reveal all to automated tester  

NASA Astrophysics Data System (ADS)

Technological developments in the field of automated test equipment for low radar-cross-section (RCS) systems are reviewed. Emphasis is given to an Automated Digital Analysis and Measurement (ADAM) system for measuring, scattering, and evaluating RCS using a minicomputer in combination with a vector network analyzer and a positioner programmer. ADAM incorporates a stepped CW measurement technique to obtain RCS as a function of both range and frequency at a fixed aspect angle. The operating characteristics and calibration procedures of the ADAM system are described and estimates of RCS sensitivity are obtained. The response resolution of the ADAM system is estimated to be 36 cm per measurement bandwidth (in GHz) for a minimum window. A block diagram of the error checking routine of the ADAM system is provided.

Hartman, R. E.

1985-09-01

224

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.

225

Monostatic Reflectivity and Transmittance of Radar Absorbing Materials at 650 GHz  

Microsoft Academic Search

Transmittance and monostatic reflectivity of different radar absorbing materials at 650 GHz are presented. The reflectivity was measured in plane-wave conditions in a radar cross-section (RCS) range with vertical polarization. The lowest reflectivity level (-70 dB) was achieved with commercial absorbers TK THz RAM and Firam-500 with oblique incidence angles. Floor carpets were also studied, and the reflectivity level of

Aleksi Tamminen; Anne Lonnqvist; Juha Mallat; Antti V. Raisanen

2008-01-01

226

Neutron cross sections: Volume 2, Neutron cross section curves  

Microsoft Academic Search

Data is presented only for total (i.e., integrated) reaction cross sections (and related fission parameters) as a function of incident-neutron energy. The energy range has been limited to 0.01 eV to 200 MeV in order to exclude crystalline and magnetic effects for slow neutrons and relativistic effects for high energy neutrons. Angular distributions and partial reaction cross sections to specific

V. McLane; C. L. Dunford; P. F. Rose

1988-01-01

227

Monostatic Reflectivity and Transmittance of Radar Absorbing Materials at 650 GHz  

NASA Astrophysics Data System (ADS)

Transmittance and monostatic reflectivity of different radar absorbing materials at 650 GHz are presented. The reflectivity was measured in plane-wave conditions in a radar cross-section (RCS) range with vertical polarization. The lowest reflectivity level (-70 dB) was achieved with commercial absorbers TK THz RAM and Firam-500 with oblique incidence angles. Floor carpets were also studied, and the reflectivity level of those was found to be sufficiently low (from -50 to -60 dB) for use in antenna test ranges. Results agree with earlier studies and indicate the applicability of the RCS method in reflectivity measurements also at 650 GHz.

Tamminen, Aleksi; Lonnqvist, Anne; Mallat, Juha; Raisanen, Antti V.

2008-03-01

228

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

229

DSI3D-RCS: Theory 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 non-dissipative, 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 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.; Eme, B.

1995-03-16

230

Semicylindrical Radar Absorbing Structures using Fiber-reinforced Composites and Conducting Polymers in the X-band  

Microsoft Academic Search

This paper presents a low observable structure with curved surfaces made by fiber-reinforced composites, conducting polymers and shows the possibility of developing stealth platforms for military applications. We propose radar absorbing structures (RAS) based on a circuit analog absorber in order to reduce the radar cross-section (RCS) of an object with curved surfaces. First, semi-cylindrical RAS with a periodic square

Hong-Kyu Jang; Jae-Hwan Shin; Chun-Gon Kim; Sang-Hun Shin; Jin-Bong Kim

2011-01-01

231

Radar cross section of complex objects  

Microsoft Academic Search

The present issue of the Annals of Telecommunications, initiated by J. M. L. Bernard, G. Pelosi, and P. Ya. Ufimtsev, is devoted to the presentation of several recently obtained results in the field of electromagnetic wave diffraction by complex objects. This now well recognized scientific field has strongly expanded during the last decades most notably thanks to the efforts of

Alain F. Lanusse; Pierre Fuerxer

1995-01-01

232

Low Energy Neutrino Cross Sections  

NASA Astrophysics Data System (ADS)

Present atmospheric and accelerator based neutrino oscillation experiments operate at low neutrino energies (Ev ~ 1 GeV) to access the relevant regions of oscillation parameter space. As such, they require precise knowledge of the cross sections for neutrino-nucleon interactions in the sub-to-few GeV range. At these energies, neutrinos predominantly interact via quasi-elastic (QE) or single pion production processes, which historically have not been as well studied as the deep inelastic scattering reactions that dominate at higher energies. Data on low energy neutrino cross sections come mainly from bubble chamber, spark chamber, and emulsion experiments that collected their data decades ago. Despite relatively poor statistics and large neutrino flux uncertainties, these measurements provide an important and necessary constraint on Monte Carlo models in present use. The following sections discuss the current status of QE, resonant single pion, coherent pion, and single kaon production cross section measurements at low energy.

Zeller, G. P.

2004-10-01

233

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

234

Negative ion detachment cross sections  

SciTech Connect

During past year, we have measured cross sections for associative and collisional detachment for several negative ions in collisions with atomic hydrogen. Additional experiments have been performed in which the formation of secondary negative ions and electrons by means of low energy ion impact on surfaces has been studied. Brief descriptions of these activities along with future plans for the project follow.

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

1991-12-01

235

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

236

Stray signal requirements for compact range reflectors based on RCS measurement errors  

NASA Technical Reports Server (NTRS)

The authors present a performance criterion for compact range reflectors such that their edge diffracted stray signal levels meet a reasonable radar cross section (RCS) measurement error requirement. It is shown by example that one of the significant error sources is the diffracted fields emanating from the edges or junctions of the reflector. This measurement error is demonstrated by placing a diagonal square flat plate in the target zone and rotating it to appropriate angles. These angles are determined by bisecting the plane wave and stray signal directions. This results in a peak bistatic measurement of the edge diffracted stray signal. It is proposed that the diagonal flat plate be used to evaluate new reflector designs as well as existing systems. A reasonable stray signal performance level has been developed so that new reflector systems can be characterized in terms of an RCS measurement error requirement.

Lee, Teh-Hong; Burnside, Walter D.

1991-01-01

237

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 âÂÂImageâÂÂ), or an image from a CAT scan (by choosing âÂÂCTâÂÂ). 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.

2010-07-20

238

A compact range RCS measurement system  

Microsoft Academic Search

This paper discusses a compact range radar cross-section measurement system. The system consists of a dual-shaped offset Cassegrain antenna system and a short pulse coherent radar cross-section instrumentation system. The combination of a highly focused antenna beam and a short pulse radar system with high performance time domain gating allows a considerable improvement of the compact range performance as compared

F. Pasqualucci; J. A. Paul; J. H. Andrews; J. K. Conn; L. S. Gans

1986-01-01

239

A progression of high-frequency RCS prediction techniques  

NASA Astrophysics Data System (ADS)

Attention is given to the unique features and advantages of the various methods that have been devised over the years to predict the radar cross section (RCS) of large, complex detection targets. The method of moments is unsuitable for routine large body computations, and geometric optics yields erroneous results for flat and singly curved surfaces. The theories of Keller (1957) and Ufimtsev (1957) have poor diffraction coefficients in the transition regions of shadow and reflection boundaries. In the Kouyomjian and Pathak (1974) theory, the scattering direction is constrained to lie on the Keller cone, while a method of equivalent currents, although permitting the scattering direction to be arbitrary, yields nonphysical equivalent currents. It is noted that the methods discussed do not address the problem posed by the surface traveling wave of long, smooth bodies.

Knott, E. F.

1985-02-01

240

Detection with high resolution radar - Great promise, big challenge  

NASA Astrophysics Data System (ADS)

An approach to improving the radar sensitivity against low radar-cross-section (RCS) and stealth targets without requiring very large power-aperture products is proposed. The problem of target detection performed by a high-resolution radar is discussed, and it is shown that imaging can improve radar sensitivity by a proper design of both transmitter and receiver. In essence, the technique is regarded as an attempt to achieve a perfect equalization of the composite channel formed by the transmitter, antenna, target response, and receiver. An outline of the design criteria for the optimization of the transmitter and receiver in noise-limited conditions is presented. An assessment of the detection performance of a high-resolution radar and a comparison with a low-resolution radar are made for a simple case involving the use of a coherent pulse train as a radar waveform.

Farina, Alfonso; Studer, Flavio A.

1991-05-01

241

Radar target recognition system using 3D mathematical model  

NASA Astrophysics Data System (ADS)

A target recognition system is described using 3-D mathematical models which simulate radar images. The simulated radar images are created from radar cross section (RCS) responses of the 3-D models and compared with measured target radar images. The 3-D models consist of several thousands facets, and one facet size is less than the radar resolution. An RCS response of each facet in the models is calculated by the modified geometrical theory of diffraction (GTD) method using the information of the radar frequency and the target aspect angle. The RCS response of each facet is projected onto the 2-D plane based on target aspect angle to create the final simulation radar images. The system is verified to be able to simulate even a ship radar imagery, in spite of the difficulty in the simulation due to its structural complexity. Evaluations were made for this recognition system by comparing the simulated ship images created from the 3-D models with the real ship images obtained by an airborne MITSUBISHI-SAR which has the capability of obtaining the X-band 1m resolution SAR and ISAR images, and the system has been proved to have the classification accuracy of better than 90%.

Nakano, Yosuke; Hara, Yoshihisa; Saito, Jun; Inasawa, Yoshio

1998-09-01

242

Radar principles  

Microsoft Academic Search

The basic operating principles, design, and applications of radars are discussed in an introductory text intended for first-year graduate students. Topics addressed include radar measurements, radar target cross sections, radar detection, ground effects, matched filters, ambiguity functions, coded radar signals, and radar measurement accuracy. Consideration is given to processing coherent pulse trains, moving-target indicators, CFAR, SAR, and monopulse antenna tracking.

Nadav Levanon

1988-01-01

243

Three radar imaging methods based on the one-dimensional laser range profile  

NASA Astrophysics Data System (ADS)

One-dimensional range profile is known as a simple radar imaging technology. Based on the imaging mechanism, the laser range profiles (LRPS) of the convex rotators in three different methods, which named as the Beam Scattering Method (BS method), Radar Cross Section Method (RCS method) and Surface Elements Method (SE method),were studied. In detail, BS method, which combined the laser beam pulse scattering theory and radar equation, is the very model that can be applied to the convex quadric rotary bodies, however, it may produce singular solutions in certain incident directions. The RCS method is just an extension of the theory of radar cross section theory and radar equation. According to the definition, the simplest forms of RCS which were then substituted into the radar equation were obtained, finally the one-dimensional range profiles were analytically resolved. The SE Method is a much more comprehensive theory to get the laser range profiles of arbitrary objects. The object should be first divided into numerous small triangle facets, and sum the backscattering power of these facets in the same distance, and in this way the final LRPS were deduced. In the meanwhile, the SE method is the most convenient way to evolve into the three-dimensional range profile. In the paper, the LRPS of a cone based on the three models above were simulated, it was found that the features and shape of each profiles were similar basically, but theoretical correction to SE method was still needed.

Mou, Yuan; Wu, Zhen-sen; Qu, Tan; Liao, Run-gui

2013-09-01

244

Photoionization cross section of Fe7+ ion  

NASA Astrophysics Data System (ADS)

The fully relativistic R-matrix calculation is performed for the photoionization cross section of Fe7+. The results are compared with available experimental spectrum and previous calculations of the cross section.

Gao, L. C.; Xie, L. Y.; Zhang, D. H.; Wang, J. G.; Shi, Y. L.; Dong, C. Z.

2014-04-01

245

Neutron cross sections: Book of curves  

SciTech Connect

Neuton Cross Sections: Book of Curves represents the fourth edition of what was previously known as BNL-325, Neutron Cross Sections, Volume 2, CURVES. Data is presented only for (i.e., intergrated) reaction cross sections (and related fission parameters) as a function of incident-neutron energy for the energy range 0.01 eV to 200 MeV. For the first time, isometric state production cross sections have been included. 11 refs., 4 figs.

McLane, V.; Dunford, C.L.; Rose, P.F.

1988-01-01

246

Hadronic absorption cross sections of B c  

Microsoft Academic Search

The absorption cross sections Bc meson by hadronic commoving systems (nucleons) are investigated using a gauged SU5 hadronic Lagrangian in mesonic exchange model. The energy dependence of dissociation cross sections are calculated from the threshold to higher energies with monopole form factor. Depending on values of the monopole form factor cut off parameter used, the peak cross sections are found

M. A. K. Lodhi; Rain Marshall

2007-01-01

247

Recent fission cross section standards measurements  

SciTech Connect

The /sup 235/U(n,f) reaction is the standard by which most neutron induced fission cross sections are determined. Most of these cross sections are derived from relatively easy ratio measurements to /sup 235/U. However, the more difficult /sup 235/U(n,f) cross section measurements require the use of advanced neutron detectors for the determination of the incident neutron fluence. Examples of recent standard cross section measurements are discussed, various neutron detectors are described, and the status of the /sup 235/U(n,f) cross section standard is assessed. 23 refs., 8 figs., 4 tabs.

Wasson, O.A.

1985-01-01

248

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

249

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

250

DSI3D-RCS test case 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 has been used to solve the following problems: (1) wedge cylinder--thin flat metal plate; (2) wedge cylinder with plate extension--thin flat metal plate; (3) plate with half cylinder extension--thin flat metal plate; (4) rectangular plate (business card)--thin flat metal plate; (5) wedge cylinder with gap--thin flat metal plate; (6) NASA Almond; (7) wavelength circular cavity. In order to generate each of the angle sweeps, it was necessary to run DSI3D once for each data point on the graphs. This is because these are backscatter calculations, and the incident pulse comes from a different direction as the angle {phi} is changed.

Madsen, N.; Steich, D.; Cook, G.; Eme, B.

1995-08-01

251

[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

252

Aircraft Wake RCS Measurement  

NASA Technical Reports Server (NTRS)

A series of multi-frequency radar measurements of aircraft wakes at altitudes of 5,000 to 25,00 ft. were performed at Kwajalein, R.M.I., in May and June of 1990. Two aircraft were tested, a Learjet 35 and a Lockheed C-5A. The cross-section of the wake of the Learjet was too small for detection at Kwajalein. The wake of the C-5A, although also very small, was detected and measured at VHF, UHF, L-, S-, and C-bands, at distances behind the aircraft ranging from about one hundred meters to tens of kilometers. The data suggest that the mechanism by which aircraft wakes have detectable radar signatures is, contrary to previous expectations, unrelated to engine exhaust but instead due to turbulent mixing by the wake vortices of pre-existing index of refraction gradients in the ambient atmosphere. These measurements were of necessity performed with extremely powerful and sensitive instrumentation radars, and the wake cross-section is too small for most practical applications.

Gilson, William H.

1994-01-01

253

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

254

Radar scattering from foamed plastic target supports  

NASA Astrophysics Data System (ADS)

This study investigates the scattering from foamed plastic target supports. This material is often used in both indoor and outdoor ranges to support all sizes of targets for radar cross section measurements. Two common foamed plastics, styrofoam and expanded bead polystyrene (EPS), are discussed. Two types of scattering are associated with foamed plastic, coherent and incoherent. The incoherent is normally the lowest, but has not been satisfactorily quantified. Coherent scattering is related to the shape of the target, and the emphasis of this study is on the coherent return. One goal was to predict the coherent RCS of an EPS column using the Uniform Theory of Diffraction (UTD). It was found that UTD can accurately predict the backscatter of an EPS column consisting of flat and curved surfaces. The second goal was to experimentally study the effects of shaping on coherent RCS. The benefits of adding a vertical slope to circular cylindrical columns was studied. RCS reductions of approximately 20 dB were achieved. Some low RCS column shapes were also measured; sloping did not produce a measurable RCS reduction in these cases.

Chambers, Michael W.

1991-12-01

255

Photoacoustic measurement of absolute overtone cross sections  

NASA Astrophysics Data System (ADS)

Using the photoacoustic effect, integrated absorption cross sections for the 5-0 and 6-0 C?H stretching overtones of ethane and ethylene were calibrated against the well-known cross sections for the 4-0 and 5-0 overtones of HD. The results of this calibration procedure agree well with FT-IR measurements by Quack and co-workers. Thus, these absorption cross sections would serve well as secondary reference standards in overtone measurements.

Gutow, J. H.; Davidsson, J.; Zare, R. N.

1991-10-01

256

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

257

Theoretical antideuteron-nucleus absorptive cross sections  

NASA Technical Reports Server (NTRS)

Antideuteron-nucleus absorptive cross sections for intermediate to high energies are calculated using an ion-ion optical model. Good agreement with experiment (within 15 percent) is obtained in this same model for (bar p)-nucleus cross sections at laboratory energies up to 15 GeV. We describe a technique for estimating antinucleus-nucleus cross sections from NN data and suggest that further cosmic ray studies to search for antideuterons and other antinuclei be undertaken.

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

1993-01-01

258

Cross-section Regression with Common Shocks  

Microsoft Academic Search

This paper considers regression models for cross-section data that exhibit cross-section dependence due to common shocks, such as macroeconomic shocks. The paper analyzes the properties of least squares (LS) and instrumental variables (IV) estimators in this context. The results of the paper allow for any form of cross-section dependence and heterogeneity across population units. The probability limits of the LS

Donald W. K. Andrews

2004-01-01

259

Cross-section Regression with Common Shocks  

Microsoft Academic Search

This paper considers regression models for cross-section data that exhibit cross-section dependence due to common shocks, such as macroeconomic shocks. The paper analyzes the properties of least squares (LS) and instrumental variables (IV) estimators in this context. The results of the paper allow for any form of cross-section dependence and heterogeneity across population units. The probability limits of the LS

Donald W. K. Andrews

2003-01-01

260

{sup 16}O neutron cross section evaluation  

SciTech Connect

This work has resulted from a need to compute more accurately the neutron scattering cross sections and angular distributions for {sup 16}O. Several oxygen evaluations have been performed in the past with R-Matrix theory, including ENDF/B-V and ENDF/B-VI. ENDF/B-VI is an improvement over ENDF/B-V, but still underpredicts in general the forward scattering of neutrons below 2.5 MeV. R-Matrix theory is used in describing cross sections at and near the resonance energies; but may not always be adequate in describing cross sections between resonances, especially when they are widely spaced. The optical (potential well) model of the nucleus is very good in representing cross sections that vary smoothly with energy, but not at describing all of the detailed resonance cross sections. A combination of the potential well model and R-Matrix theory was used for this work to represent cross sections with isolated resonances with large spacings between them. The total neutron cross section of oxygen-16 below 3.0 MeV has widely separated resonances and a dip in the cross section at 2.35 MeV. In the vicinity of resonances, where cross sections vary rapidly with energy, R-Matrix theory has been successful in fitting experimental data. In the region between resonances, an analytical procedure with physical basis is needed that agrees with data over a wide range of energies bracketing regions where experimental measurements are lacking.

Caro, E. [Lockheed Martin Corp., Schenectady, NY (United States)

1998-06-01

261

Production cross section of rotating string  

Microsoft Academic Search

We calculate production cross sections of a single rotating string from a collision of two light states in bosonic string theory. We find that the cross sections are written in terms of the modified Bessel function of the first kind with the degree given by the angular momentum in the high energy regime. We also obtain a similar formula from

Tsunehide Kuroki; Toshihiro Matsuo

2008-01-01

262

A compact range RCS measurement system  

NASA Astrophysics Data System (ADS)

This paper discusses a compact range radar cross-section measurement system. The system consists of a dual-shaped offset Cassegrain antenna system and a short pulse coherent radar cross-section instrumentation system. The combination of a highly focused antenna beam and a short pulse radar system with high performance time domain gating allows a considerable improvement of the compact range performance as compared with front-fed offset parabolic antenna systems. The paper also presents some of the results obtained in a scaled-down EHF compact range set up in a small room with no microwave absorbing material on the ceiling, floor, and sidewalls.

Pasqualucci, F.; Paul, J. A.; Andrews, J. H.; Conn, J. K.; Gans, L. S.

263

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

264

Cross Section Evaluations for Arsenic Isotopes  

SciTech Connect

The authors present an evaluation of cross sections describing reactions with neutrons incident on the arsenic isotopes with mass numbers 75 and 74. Particular attention is paid to (n,2n) reactions. The evaluation for {sup 75}As, the only stable As isotope, is guided largely by experimental data. Evaluation for {sup 74}As is made through calculations with the EMPIRE statistical-model reaction code. Cross sections describing the production and destruction of the 26.8 ns isomer in {sup 74}As are explicitly considered. Uncertainties and covariances in some evaluated cross sections are also estimated.

Pruet, J; McNabb, D P; Ormand, W E

2005-03-10

265

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

266

Relative cross section and depolarization of NOCl  

NASA Technical Reports Server (NTRS)

A standard photon counting technique and an argon-ion laser with 4545, 4579, 4727, 4765, 4880, 4965, 5017 and 5145-A lasing lines, providing a measurable Raman spectrum from NOCl, were used in the measurement of the Raman scattering cross section of NOCl at a Raman shift of 334.4 plus or minus 1.6/cm in relation to the N2 Raman cross section. A polarization analyzer and a quartz wedge were placed in front of the entrance slit of the double monochromator for depolarization measurements. Diagrams are plotted to show the scattering cross section and depolarization measurement results.

Hoell, J. M.; Wade, W. R.

1974-01-01

267

Radar principles  

NASA Astrophysics Data System (ADS)

The basic operating principles, design, and applications of radars are discussed in an introductory text intended for first-year graduate students. Topics addressed include radar measurements, radar target cross sections, radar detection, ground effects, matched filters, ambiguity functions, coded radar signals, and radar measurement accuracy. Consideration is given to processing coherent pulse trains, moving-target indicators, CFAR, SAR, and monopulse antenna tracking. Extensive diagrams and graphs are provided.

Levanon, Nadav

268

3D characterization of radar targets by means of ISAR/SAR near field imaging techniques  

NASA Astrophysics Data System (ADS)

Inverse synthetic aperture radar (ISAR) imaging techniques based on indoor near field backscattering measurements turns out to be a powerful tool for diagnostic purposes in radar cross-section (RCS) reduction and for deriving RCS target models, viable for radar systems operating at larger distances, e.g. under far field conditions. This paper presents an advanced 3-D imaging approach, where in addition to the turntable rotation the antenna is moved along a linear path chosen in accordance with the geometry of the target and the aspect angle of interest. For reconstructing the reflectivity distribution a configuration-specific grid of spatial sampling points is employed which reduces the complexity of determining correct values for the scattering amplitudes. The reflectivity distribution reproduces the backscattering seen from an antenna moved along a finite surface (synthetic 2-D-aperture) in the scattering near field of the target, but is to be used to model backscattering for antennas at larger distances, e.g. in the far field. Therefore, the feasibility of this approach is discussed with respect to different applications, i.e. for the diagnostic of RCS reduction and for deterministic or statistical RCS models. Results obtained for a car as X-band radar target are presented in order to verify the features of the imaging system.

John, Marc-Andre; Aulenbacher, Uwe; Inaebnit, Christian

2007-04-01

269

MODELING AND FISSION CROSS SECTIONS FOR AMERICIUM.  

SciTech Connect

This is the final report of the work performed under the LANL contract on the modeling and fission cross section for americium isotopes (May 2004-June 2005). The purpose of the contract was to provide fission cross sections for americium isotopes with the nuclear reaction model code EMPIRE 2.19. The following work was performed: (1) Fission calculations capability suitable for americium was implemented to the EMPIRE-2.19 code. (2) Calculations of neutron-induced fission cross sections for {sup 239}Am to {sup 244g}Am were performed with EMPIRE-2.19 for energies up to 20 MeV. For the neutron-induced reaction of {sup 240}Am, fission cross sections were predicted and uncertainties were assessed. (3) Set of fission barrier heights for each americium isotopes was chosen so that the new calculations fit the experimental data and follow the systematics found in the literature.

ROCHMAN, D.; HERMAN, M.; OBLOZINSKY, P.

2005-05-01

270

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

271

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

272

Total cross section for top quark production.  

National Technical Information Service (NTIS)

We summarize our calculation of the total 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...

E. L. Berger H. Contopanagos

1996-01-01

273

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

274

ConcepTest: Cross Section Explaination  

NSDL National Science Digital Library

During fieldwork in the western U.S., an experienced geologist sketched the cross section below showing three different units of tilted rocks and their relative ages. What could you best infer from this diagram? a. ...

275

Low energy antiproton nuclear absorption cross sections  

SciTech Connect

We have studied the absorption cross section of antiprotons on Al, Cu, and Pb for T = 131.6 and 193.6 MeV. These results are compared with predictions of an optical model fitted to antiproton elastic scattering data on these nuclei and are in agreement with these predictions. The cross sections have an exponential dependence on the mass number A with an exponent of approximately 0.61.

Ashford, V.; Sainio, M.E.; Sakitt, M.; Skelly, J.; Debbe, R.; Fickinger, W.; Marino, R.; Robinson, D.K.

1985-02-01

276

Electron impact cross sections for molecular lasers  

NASA Astrophysics Data System (ADS)

This project deals with electron impact experiments on atoms and molecules relevant to the development of the N2-CO2 and rare-gas halide lasers. Cross sections for state-of-state transitions in a variety of collisional processes (rotational, vibrational, and electronic excitation; dissociative attachment) have been determined in the first 4 eV of threshold and are generally found to exhibit great enhancement attributable to resonances. Highlights of the methods of cross-section measurement are also presented.

Wong, S. F.

1984-04-01

277

Path forward for dosimetry cross sections  

SciTech Connect

In the 1980's the dosimetry community embraced the need for a high fidelity quantification of uncertainty in nuclear data used for dosimetry applications. This led to the adoption of energy-dependent covariance matrices as the accepted manner of quantifying the uncertainty data. The trend for the dosimetry community to require high fidelity treatment of uncertainty estimates has continued to the current time where requirements on nuclear data are codified in standards such as ASTM E 1018. This paper surveys the current state of the dosimetry cross sections and investigates the quality of the current dosimetry cross section evaluations by examining calculated-to-experimental ratios in neutron benchmark fields. In recent years more nuclear-related technical areas are placing an emphasis on uncertainty quantification. With the availability of model-based cross sections and covariance matrices produced by nuclear data codes, some nuclear-related communities are considering the role these covariance matrices should play. While funding within the dosimetry community for cross section evaluations has been very meager, other areas, such as the solar-related astrophysics community and the US Nuclear Criticality Safety Program, have been supporting research in the area of neutron cross sections. The Cross Section Evaluation Working Group (CSEWG) is responsible for the creation and maintenance of the ENDF/B library which has been the mainstay for the reactor dosimetry community. Given the new trends in cross section evaluations, this paper explores the path forward for the US nuclear reactor dosimetry community and its use of the ENDF/B cross-sections. The major concern is maintenance of the sufficiency and accuracy of the uncertainty estimate when used for dosimetry applications. The two major areas of deficiency in the proposed ENDF/B approach are: 1) the use of unrelated covariance matrices in ENDF/B evaluations and 2) the lack of 'due consideration' of experimental data in the evaluation. (authors)

Griffin, P.J. [Sandia National Laboratories, Albuquerque, NM 87185-1146 (United States); Peters, C.D. [Sandia Staffing Alliance, Albuquerque, NM 87110 (United States)

2011-07-01

278

Upper bound on neutrino cross sections  

NASA Technical Reports Server (NTRS)

Asymptotic bounds on the total cross sections of neutrino (weak) scattering processes are obtained. It is shown that the elastic neutrino-neutrino cross section obeys the following bound in the high energy region: sigma sub T (S) equals ImF(S,0)/S is less than or equal to const. (LogS) squared. Assumptions of analyticity, crossing, unitarity, polynomial boundaries, and a zero-condition on the absorptive part of the scattering amplitude, are used to obtain this bound.

Mickens, R. E.

1975-01-01

279

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

280

Controlling radar signature  

Microsoft Academic Search

Low observable technologies for military and tactical aircraft are reviewed including signature-reduction techniques and signal detection\\/jamming. Among the applications considered are low-signature sensors and the reduction of radar cross section in conjunction with radar-absorbing structures and materials. Technologies for reducing radar cross section are shown to present significant technological challenges, although they afford enhanced aircraft survivability.

Foulke

1992-01-01

281

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

282

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

283

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

284

SSC 50 mm dipole cross section  

SciTech Connect

In this paper we present the magnetic design of the two dimensional coil and iron cross section, referred to as DSX201/W6733, for the 50 mm aperture main ring dipole magnet for the Superconducting Super Collider (SSC). The computed values of the allowed field harmonics as a function of current, the quench performance predictions, the stored energy calculations, the effect of random errors on the coil placement and the Lorentz forces on the coil will be presented. The yoke has been optimized to reduce iron saturation effects on the field harmonics. We shall present the summary of this design which will include the expected overall performance of this cross section. Prototypes of these dipoles are being built at the Brookhaven National Laboratory (BNL) and at the Fermi National Accelerator Laboratory (FNAL). There are slight differences between the cross sections at the two laboratories. 7 refs., 6 figs., 11 tabs.

Gupta, R.C.; Kahn, S.A.; Morgan, G.H.

1991-01-01

285

Photoneutron Cross Sections of Astrophysical Significance  

NASA Astrophysics Data System (ADS)

Presented in this paper are some of the latest measurements of photoneutron cross sections of direct relevance to the p-process nucleosynthesis in the context of the statistical model of compound nuclear reactions. We discuss the p-process origin of the rarest nuclide and the only naturally occurring isomer 180Tam, a serious underproduction problem of 138La, and the nuclear level density of 180Ta determined from the partial photoneutron cross section for 180Tam. As the laser-Compton scattering ? ray at AIST has enabled one to directly determine (?,n) cross sections, the blackbody synchrotron radiation to be produced by a ten-Tesla superconducting wiggler at SPring-8 is expected to be a promising tool for exploring (?,?) and (?,p) reactions in the future.

Utsunomiya, H.

2007-02-01

286

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

287

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

288

Cross section for 246Cm subbarrier fission  

NASA Astrophysics Data System (ADS)

The cross section for 246Cm fission induced by neutrons of energy in the range 0.1 eV-20 keV was measured by the neutron lead slowing-down spectrometer (LSDS-100) of the Institute for Nuclear Research (INR, Russian Academy of Sciences, Moscow). The parameters of the resonance area and of the fission width were evaluated for several low-lying s-wave neutron resonances. The parameters of the intermediate structure in the cross section for the subbarrier fusion of 246Cm nuclei were found. The results obtained in this way were compared with available experimental data and with recommended evaluated data.

Alekseev, A. A.; Bergman, A. A.; Berlev, A. I.; Koptelov, E. A.; Samylin, B. F.; Trufanov, A. M.; Fursov, B. I.; Shorin, V. S.

2010-10-01

289

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

290

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

291

Total cross section in ?? collisions at LEP  

Microsoft Academic Search

The reaction e+e??e+e??????e+e?hadrons for quasi-real photons is studied using data from s=183 GeV up to 202 GeV. Results on the total cross sections ?(e+e??e+e?hadrons) and ?(???hadrons) are given for the two-photon centre-of-mass energies 5 GeV?W???185 GeV. The total cross section of two real photons is described by a Regge parametrisation. We observe a steeper rise with the two-photon centre-of-mass energy as compared to the

M. Acciarri; P. Achard; O. Adriani; M. Aguilar-Benitez; J. Alcaraz; G. Alemanni; J. Allaby; A. Aloisio; M. G. Alviggi; G. Ambrosi; H. Anderhub; V. P. Andreev; T. Angelescu; F. Anselmo; A. Arefiev; T. Azemoon; T. Aziz; P. Bagnaia; A. Bajo; L. Baksay; A. Balandras; S. V. Baldew; S. Banerjee; A. Barczyk; R. Barillère; P. Bartalini; M. Basile; N. Batalova; R. Battiston; A. Bay; F. Becattini; U. Becker; F. Behner; L. Bellucci; R. Berbeco; J. Berdugo; P. Berges; B. Bertucci; B. L. Betev; S. Bhattacharya; M. Biasini; A. Biland; J. J. Blaising; S. C. Blyth; G. J. Bobbink; A. Böhm; L. Boldizsar; B. Borgia; D. Bourilkov; M. Bourquin; S. Braccini; J. G. Branson; F. Brochu; A. Buffini; A. Buijs; J. D. Burger; W. J. Burger; X. D. Cai; M. Capell; G. Carlino; A. M. Cartacci; J. Casaus; G. Castellini; F. Cavallari; N. Cavallo; C. Cecchi; M. Cerrada; F. Cesaroni; M. Chamizo; Y. H. Chang; U. K. Chaturvedi; M. Chemarin; A. Chen; G. Chen; H. F. Chen; H. S. Chen; G. Chiefari; L. Cifarelli; F. Cindolo; C. Civinini; I. Clare; R. Clare; G. Coignet; N. Colino; S. Costantini; F. Cotorobai; A. Csilling; S. Cucciarelli; T. S. Dai; R. D'Alessandro; P. Déglon; A. Degré; K. Deiters; E. Delmeire; P. Denes; F. DeNotaristefani; M. Diemoz; M. Dierckxsens; C. Dionisi; M. Dittmar; A. Dominguez; A. Doria; M. T. Dova; D. Duchesneau; D. Dufournaud; P. Duinker; A. Engler; F. J. Eppling; F. C. Erné; A. Ewers; P. Extermann; M. Fabre; M. A. Falagan; S. Falciano; A. Favara; J. Fay; O. Fedin; M. Felcini; T. Ferguson; H. Fesefeldt; E. Fiandrini; J. H. Field; F. Filthaut; P. H. Fisher; I. Fisk; G. Forconi; K. Freudenreich; C. Furetta; Yu. Galaktionov; S. N. Ganguli; P. Garcia-Abia; M. Gataullin; S. S. Gau; S. Gentile; N. Gheordanescu; S. Giagu; Z. F. Gong; G. Grenier; O. Grimm; M. W. Gruenewald; M. Guida; V. K. Gupta; A. Gurtu; L. J. Gutay; D. Haas; A. Hasan; D. Hatzifotiadou; T. Hebbeker; A. Hervé; P. Hidas; J. Hirschfelder; H. Hofer; G. Holzner; H. Hoorani; S. R. Hou; Y. Hu; I. Iashvili; B. N. Jin; L. W. Jones; I. Josa-Mutuberr??a; R. A. Khan; D. Käfer; M. Kaur; M. N. Kienzle-Focacci; D. Kim; J. K. Kim; J. Kirkby; D. Kiss; W. Kittel; A. Klimentov; A. C. König; M. Kopal; A. Kopp; V. Koutsenko; M. Kräber; R. W. Kraemer; W. Krenz; A. Krüger; A. Kunin; I. Laktineh; G. Landi; M. Lebeau; A. Lebedev; P. Lebrun; P. Lecomte; P. Lecoq; H. J. Lee; R. Leiste; P. Levtchenko; C. Li; S. Likhoded; C. H. Lin; W. T. Lin; F. L. Linde; L. Lista; Z. A. Liu; W. Lohmann; E. Longo; Y. S. Lu; K. Lübelsmeyer; C. Luci; D. Luckey; L. Lugnier; L. Luminari; W. Lustermann; W. G. Ma; M. Maity; L. Malgeri; A. Malinin; C. Maña; D. Mangeol; J. Mans; G. Marian; J. P. Martin; F. Marzano; K. Mazumdar; R. R. McNeil; S. Mele; L. Merola; M. Meschini; W. J. Metzger; A. Mihul; H. Milcent; G. Mirabelli; J. Mnich; G. B. Mohanty; T. Moulik; G. S. Muanza; A. J. M. Muijs; B. Musicar; M. Musy; M. Napolitano; F. Nessi-Tedaldi; H. Newman; T. Niessen; A. Nisati; H. Nowak; R. Ofierzynski; G. Organtini; A. Oulianov; C. Palomares; D. Pandoulas; S. Paoletti; P. Paolucci; R. Paramatti; H. K. Park; I. H. Park; G. Passaleva; S. Patricelli; T. Paul; M. Pauluzzi; C. Paus; F. Pauss; M. Pedace; S. Pensotti; D. Perret-Gallix; B. Petersen; D. Piccolo; F. Pierella; M. Pieri; P. A. Piroué; E. Pistolesi; V. Plyaskin; M. Pohl; V. Pojidaev; H. Postema; J. Pothier; D. O. Prokofiev; J. Quartieri; G. Rahal-Callot; M. A. Rahaman; P. Raics; N. Raja; R. Ramelli; P. G. Rancoita; R. Ranieri; A. Raspereza; G. Raven; P. Razis; D. Ren; M. Rescigno; S. Reucroft; S. Riemann; K. Riles; J. Rodin; B. P. Roe; L. Romero; A. Rosca; S. Rosier-Lees; S. Roth; C. Rosenbleck; B. Roux; J. A. Rubio; G. Ruggiero; H. Rykaczewski; S. Saremi; S. Sarkar; J. Salicio; E. Sanchez; M. P. Sanders; C. Schäfer; V. Schegelsky; S. Schmidt-Kaerst; D. Schmitz; H. Schopper; D. J. Schotanus; G. Schwering; C. Sciacca; A. Seganti; L. Servoli; S. Shevchenko; N. Shivarov; V. Shoutko; E. Shumilov; A. Shvorob; T. Siedenburg; D. Son; B. Smith; P. Spillantini; M. Steuer; D. P. Stickland; A. Stone; B. Stoyanov; A. Straessner; K. Sudhakar; G. Sultanov; L. Z. Sun; S. Sushkov; H. Suter; J. D. Swain; Z. Szillasi; T. Sztaricskai; X. W. Tang; L. Tauscher; L. Taylor; B. Tellili; D. Teyssier; C. Timmermans; Samuel C. C. Ting; S. M. Ting; S. C. Tonwar; J. Tóth; C. Tully; K. L. Tung; Y. Uchida; J. Ulbricht; E. Valente; G. Vesztergombi; I. Vetlitsky; D. Vicinanza; G. Viertel; S. Villa; M. Vivargent; S. Vlachos; I. Vodopianov; H. Vogel; H. Vogt; I. Vorobiev; A. A. Vorobyov; A. Vorvolakos; M. Wadhwa; W. Wallraff; M. Wang; X. L. Wang; Z. M. Wang; A. Weber; M. Weber; P. Wienemann; H. Wilkens; S. X. Wu; S. Wynhoff; L. Xia; Z. Z. Xu; J. Yamamoto; B. Z. Yang; C. G. Yang; H. J. Yang; M. Yang; J. B. Ye; S. C. Yeh; An. Zalite; Yu. Zalite; Z. P. Zhang; G. Y. Zhu; R. Y. Zhu; A. Zichichi; G. Zilizi; B. Zimmermann; M. Zöller

2001-01-01

292

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

293

Simple Calculations of Proton SEU Cross Sections from Heavy Ion Cross Sections  

Microsoft Academic Search

Simple expressions, based on previous analytical and empirical models for the energy deposited by protons through their p+Si interactions, are proposed for calculating proton induced SEU cross sections from heavy ion cross sections in devices with sub-micron sensitive volumes. Calculations for modern devices yield good agreement with the experiments. The implications on calculating SEU rates in space are discussed

J. Barak

2006-01-01

294

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

295

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

296

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

297

NIST XCOM: Photon Cross Sections Database  

NSDL National Science Digital Library

This web program 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

2003-11-10

298

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

299

Total cross section for top quark production  

SciTech Connect

We summarize our calculation of the total 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.

Berger, E.L.; Contopanagos, H.

1996-08-30

300

Total cross section for top quark production  

Microsoft Academic Search

We summarize our calculation of the total 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.

E. L. Berger; H F Contopanagos

1996-01-01

301

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.

Keith, Minor; Cretaceousfossils.com

302

Cross sections for positron scattering from ethane  

NASA Astrophysics Data System (ADS)

We report experimental and theoretical cross sections for positron scattering from the fundamental organic-chemistry molecule ethane (C2H6). The experimental total cross sections (TCSs) were obtained using a linear transmission technique, for energies in the range 0.1-70 eV and with an energy resolution of ˜0.25 eV (full width at half maximum). Agreement, over the common energy range, with the earlier TCS measurements of Floeder [J. Phys. BJPAMA40022-370010.1088/0022-3700/18/16/019 18, 3347 (1985)] is excellent, while both the present results and those of Floeder are consistently higher in magnitude than the data of Sueoka and Mori [J. Phys. BJPAMA40022-370010.1088/0022-3700/19/23/021 19, 4035 (1986)]. The present calculations employed the Schwinger multichannel method and were performed in the static plus polarization approximation for energies up to 10 eV. Our calculated elastic integral cross sections (ICSs) indicate a Ramsauer-Townsend minimum at around 1.4 eV in the Ag scattering symmetry, and a virtual state. In addition we calculated from our scattering cross section a scattering length of -13.83a0. Agreement between our measured TCS and calculated elastic ICS is found to be only qualitative, although this is perhaps not so surprising given the TCS below 10 eV in principle includes contributions from rotational, vibrational, and electronic-state excitation and positronium formation whereas the calculation does not.

Chiari, L.; Zecca, A.; Trainotti, E.; Bettega, M. H. F.; Sanchez, S. d'A.; Varella, M. T. do N.; Lima, M. A. P.; Brunger, M. J.

2013-03-01

303

Cross-sectional structural parameters from densitometry  

NASA Technical Reports Server (NTRS)

Bone densitometry has previously been used to obtain cross-sectional properties of bone from a single X-ray projection across the bone width. Using three unique projections, we have extended the method to obtain the principal area moments of inertia and orientations of the principal axes at each scan cross-section along the length of the scan. Various aluminum phantoms were used to examine scanner characteristics to develop the highest accuracy possible for in vitro non-invasive analysis of cross-sectional properties. Factors considered included X-ray photon energy, initial scan orientation, the angle spanned by the three scans (included angle), and I(min)/I(max) ratios. Principal moments of inertia were accurate to within +/-3.1% and principal angles were within +/-1 degrees of the expected value for phantoms scanned with included angles of 60 degrees and 90 degrees at the higher X-ray photon energy (140 kVp). Low standard deviations in the error (0.68-1.84%) also indicate high precision of calculated measurements with these included angles. Accuracy and precision decreased slightly when the included angle was reduced to 30 degrees. 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 (I(min)/I(max)) values when various included angles are used make this technique viable for future in vivo studies.

Cleek, Tammy M.; Whalen, Robert T.

2002-01-01

304

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

305

High-frequency techniques for RCS prediction of plate geometries  

NASA Technical Reports Server (NTRS)

Radar cross section (RCS) prediction of several rectangular plate geometries is discussed using high-frequency techniques such as the Uniform Theory of Diffraction (UTD) for perfectly conducting and impedance wedges and the Method of Equivalent Currents (MEC). Previous reports have presented detailed solutions to the principal-plane scattering by a perfectly conducting and a coated rectangular plate and nonprincipal-plane scattering by a perfectly conducting plate. These solutions are briefly reviewed and a modified model is presented for the coated plate. Theoretical and experimental data are presented for the perfectly conducting geometries. Agreement between theory and experiment is very good near and at normal incidence. In regions near and at grazing incidence, the disagreement between the data vary according to diffraction distances and angles involved. It is these areas of disagreement which are of extreme interest as an explanation for the disagreement will yield invaluable insight into scattering mechanisms which are not yet identified as major contributors near and at grazing incidence. Areas of disagreement between theory and experiment are identified and examined in an attempt to better understand and predict near-grazing incidence, grazing incidence, and nonprincipal-plane diffractions.

Balanis, Constantine A.; Polka, Lesley A.

1991-01-01

306

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

NASA Astrophysics Data System (ADS)

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.; Arndt, R. A.; Briscoe, W. J.; Paris, M. W.; Strakovsky, I. I.; Workman, R. L.

2011-06-01

307

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

308

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

309

Radar Absorbing Material Design.  

National Technical Information Service (NTIS)

Low observable platforms have extremely low radar cross section specifications that cannot be achieved by shaping alone. The application of radar absorbing material is necessary, in which case the appropriate constitutive parameters and thickness must be ...

C. K. Yuzcelik

2003-01-01

310

New cross sections for H on H2 collisional transitions  

NASA Astrophysics Data System (ADS)

The cross section for H on H2 collisions is important for astrophysics as well as our understanding of the simple chemical systems. This is the simplest atom-molecule cross section. With a new H3 potential surface by Mielke et al., we have modified the ABC code by Skouteris, Castillo and Manolopoulos to calculate new cross sections. These cross sections are compared to previous cross section calculations.

Zou, Qianxia

311

Electron-collision cross sections for iodine  

NASA Astrophysics Data System (ADS)

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.; Garcia, G.; Blanco, F.; Hargreaves, L. R.; Jones, D. B.; Murrie, R.; Brunton, J. R.; Brunger, M. J.; Hoshino, M.; Buckman, S. J.

2011-04-01

312

Neutron cross section measurements at WNR  

SciTech Connect

The Weapons Neutron Research Facility has been used to obtain moderate-resolution total neutron cross section data for H, C, /sup 208/Pb, /sup 232/Th, /sup 238/U, and /sup 242/Pu over the energy range 5 to 200 MeV. Neutrons were produced by bombarding a 2.5-cm diam by 15-cm long Ta target with an 800 MeV pulsed proton beam from LAMPF. A 10.2-cm diam by 15.2-cm thick NE110 proton recoil detector was used at a flight path of 32 meters, giving a time-of-flight resolution of 60 ps/m. The total cross section results are compared to ENDF/BV evaluations and to previous data where possible.

Lisowski, P.W.; Archampaugh, G.F.; Moore, M.S.; Morgan, G.L.; Shamu, R.E.

1980-01-01

313

Measurement of Neutrino-Nucleus Cross Sections  

NASA Astrophysics Data System (ADS)

For more than 50 years, neutrinos have surprised us: not only by their mere presence, but by the recent revelation that these ghostlike particles can oscillate from one type to another. This stunning discovery has opened up a host of new questions about neutrinos and their properties; questions which we are currently in a global race to answer. The results inherently hinge upon knowledge of neutrino interaction cross sections. Such cross sections are generally poorly known and have not been updated for decades. With the advent of intense man-made neutrino beams, this situation is quickly changing. Detailed studies of low energy neutrino-nucleus interactions are now being made and revealing surprises of their own. Recent neutrino scattering measurements from a variety of experiments will be presented along with a projection for what the future holds.

Zeller, Geralyn

2011-04-01

314

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

315

Practical restoration of extension cross sections  

SciTech Connect

Cross section restoration must be based on assumptions valid for the type of terrane considered. Restore' was designed specifically for extensional terranes, representing an easy and efficient tool to routinely restore cross sections on a Macintosh personal computer. Accurate reconstructions are produced without undue complexity or the necessity for computer expertise. Success of restorations is judged by compatibility between fault blocks and reasonableness of the restored structures. Incompatibilities may indicate revisions of the original interpretation or adjustment of restoration parameters such as shear and rotation angles. The sequential reconstruction of a section's evolution is an invaluable aid to inferring the creations, migration, and trapping of hydrocarbons, or to understanding the structural and tectonic processes involved.

Schultz-Ela, D.D. (Univ. of Texas, Austin (United States))

1991-12-01

316

Time-Series-Cross-Section Methods  

Microsoft Academic Search

Time-series-cross-section (TSCS) data consist of comparable time series data observed on a variety of units. The paradigmatic applications are to the study of comparative politi-cal economy, where the units are countries (often the advanced industrial democracies) and where for each country we observe annual data on a variety of political and economic vari-ables. A standard question for such studies relates

Nathaniel Beck

317

Inclusive jet cross section at D0  

SciTech Connect

Preliminary measurement of the central ({vert_bar}{eta}{vert_bar} {<=} 0.5) inclusive jet cross sections for jet cone sizes of 1.0, 0.7, and 0.5 at D{null} based on the 1992-1993 (13.7 {ital pb}{sup -1}) and 1994-1995 (90 {ital pb}{sup -1}) data samples are presented. Comparisons to Next-to-Leading Order (NLO) Quantum Chromodynamics (QCD) calculations are made.

Bhattacharjee, M. [Delhi Univ. (India). Dept. of Physics and Astrophysics

1996-09-01

318

Electron impact excitation cross sections for CO  

Microsoft Academic Search

The R-matrix method has been used to calculate electron impact excitation cross sections for the lowest seven electronically excited states of CO in the energy range 6-18 eV. These states are represented using configuration interaction (CI) expansions and an algorithm for treating long CI expansions in scattering calculations is presented. The calculations are carried out for a range of internuclear

L. A. Morgan; J. Tennyson

1993-01-01

319

Electron impact excitation cross sections for phosphorus  

Microsoft Academic Search

:   An analytic atomic independent-particle-model is used to generate wave functions for the valence and excited states of the\\u000a neutral phosphorus atom. These wave functions are used to calculate generalized oscillator strengths, and from these quantities\\u000a the cross sections are obtained in Born approximation. Various excitations from the ground state are considered, and results are presented for electron impact energies

P. S. Ganas

1998-01-01

320

Absolute photoionization cross sections of atomic oxygen  

NASA Technical Reports Server (NTRS)

The absolute values of photoionization cross sections of atomic oxygen were measured from the ionization threshold to 120 A. An auto-ionizing resonance belonging to the 2S2P4(4P)3P(3Do, 3So) transition was observed at 479.43 A and another line at 389.97 A. The experimental data is in excellent agreement with rigorous close-coupling calculations that include electron correlations in both the initial and final states.

Samson, J. A. R.; Pareek, P. N.

1985-01-01

321

Absolute photoionization cross sections of atomic oxygen  

NASA Technical Reports Server (NTRS)

The absolute values of photoionization cross sections of atomic oxygen were measured from the ionization threshold to 120 A. An auto-ionizing resonance belonging to the 2S2P4(4P)3P(3Do, 3So) transition was observed at 479.43 A and another line at 389.97 A. The experimental data is in excellent agreement with rigorous close-coupling calculations that include electron correlations in both the initial and final states.

Samson, J. A. R.; Pareek, P. N.

1982-01-01

322

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

323

Neutron-Proton Capture Cross Section  

Microsoft Academic Search

The mean lifetime of thermal neutrons in water is measured with a large moderator (radius ~7 diffusion lengths), for which the correction for escape is only about 5%. The geometry is such that the perturbing effect of the immersed BF3 neutron detector can be almost rigorously calculated. The value obtained is tau=206.3+\\/-5.0 musec, giving the neutron-proton capture cross section as

Robert W. Stooksberry; Marshall F. Crouch

1959-01-01

324

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.

Pagliarone, C. [Universita di Torino and INFN, Trieste (Italy)

1996-08-01

325

First measurement of the Rayleigh cross section  

Microsoft Academic Search

Summary form only given. A century ago Lord Rayleigh formulated a theory of light scattering by ideal gases that not only explained the molecular origin of atmospheric scattering and the blue colour of the sky but also provided a quantitative expression for the amount of light scattered. The cross section (in cm2) is given by the well known equation: ?(?)=(24?3?4(n2-1)2

H. Naus; W. Ubachs

2000-01-01

326

WW cross sections and | Vcs| measurement  

NASA Astrophysics Data System (ADS)

Data collected by the four LEP experiments at collision energies up to 209 GeV have been analysed to extract the W pair production cross section. Combining all LEP2 centre-of-mass energies has allowed the determination of the W decay branching ratios into leptons and hadrons and to derive the value of the CKM matrix element | Vcs|. A review of existing direct and indirect | Vcs| measurements is also presented.

Ealet, A.

2003-02-01

327

MXS cross-section preprocessor user's manual  

SciTech Connect

The MXS preprocessor has been designed to reduce the execution time of programs using isotopic cross-section data and to both reduce the execution time and improve the accuracy of shielding-factor interpolation in the SIMMER-II accident analysis program. MXS is a dual-purpose preprocessing code to: (1) mix isotopes into materials and (2) fit analytic functions to the shelf-shielding data. The program uses the isotope microscopic neutron cross-section data from the CCCC standard interface file ISOTXS and the isotope Bondarenko self-shielding data from the CCCC standard interface file BRKOXS to generate cross-section and self-shielding data for materials. The materials may be a mixture of several isotopes. The self-shielding data for the materials may be the actual shielding factors or a set of coefficients for functions representing the background dependence of the shielding factors. A set of additional data is given to describe the functions necessary to interpolate the shielding factors over temperature.

Parker, F.; Ishikawa, M.; Luck, L.

1987-03-01

328

(n,?) reactions cross section research at IPPE  

NASA Astrophysics Data System (ADS)

An experimental set-up based on an ionization chamber with a Frisch grid and wave form digitizer was used for (n,?) cross section measurements. Use of digital signal processing allowed us to select a gaseous cell inside the sensitive area of the ionization chamber and determine the target atoms in it with high accuracy. This kind of approach provided us with a powerful method to suppress background arising from the detector structure and parasitic reactions on the working gas components. This method is especially interesting to study neutron reactions with elements for which solid target preparation is difficult (noble gases for example). In the present experiments we used a set of working gases which contained admixtures of nitrogen, oxygen, neon, argon and boron. Fission of 238U was used as neutron flux monitor. The cross section of the (n,?) reaction for 16O, 14N, 20Ne, 36Ar, 40Ar and the yield ratio ?0/?1 of 10B(n,?0) to 10B(n,?1) reactions was measured for neutron energies between 1.5 and 7 MeV. Additionally a measurement of the 50Cr(n,?) cross section using a solid chromium target is also reported.

Khryachkov, V. A.; Bondarenko, I. P.; Kuzminov, B. D.; Semenova, N. N.; Sergachev, A. I.; Ivanova, T. A.; Giorginis, G.

2012-02-01

329

Syracuse Research Corporation (SRC) ultrawide-bandwidth measurements radar  

NASA Astrophysics Data System (ADS)

In recent years, Syracuse Research Corporation has implemented bandwidth expansion and extended coherent processing techniques to improve scatterer resolution of images derived from existing data. The algorithms can produce extraneous responses, however, which is not the case if the data is collected using an ultrawide bandwidth radar. The long and continuous effort in radar imaging at SRC and the limited number and availability of wideband sensors justified the development of an in-house imaging facility that would be available on demand. As a result, the SRC Ultrawide Bandwidth Measurements Radar was assembled to perform the required measurements of the radar cross section (RCS) of isolated scatterers and to determine their relative location on a wide variety of target types. Along with the use of radar images for target analysis has been the development of target modeling algorithms and software that accurately predict the electromagnetic scattering from complex objects. A few years ago, the software was expanded to model objects as viewed in wide angle bistatic configurations. The SRC radar was utilized to validate these modeling algorithms in several radar bands at large bistatic angles. The system has subsequently been employed to measure a variety of target models and complex shapes and to evaluate the effects of radar absorbing materials (RAMs).

Rankin, Peter M.; Wallenberg, Robert F.

1993-05-01

330

Neutron activation cross sections on lead isotopes  

SciTech Connect

The cross sections for the reactions {sup 204}Pb(n,n{sup '}{gamma}){sup 204}Pb{sup m}, {sup 204}Pb(n,2n){sup 203}Pb, {sup 204}Pb(n,2n){sup 203}Pb{sup m1}, {sup 204}Pb(n,3n){sup 202}Pb{sup m}, {sup 206}Pb(n,3n){sup 204}Pb{sup m}, {sup 206}Pb(n,{alpha}){sup 203}Hg, and {sup 208}Pb(n,p){sup 208}Tl were determined at the IRMM van de Graaff laboratory in the neutron energy range from 14 to 21 MeV. Both natural and enriched samples were irradiated with neutrons produced via the {sup 3}H(d,n){sup 4}He reaction. The induced activities were determined by gamma-ray spectrometry using a HPGe detector in a low-background shield. Neutron fluences were determined with the well-known cross section of the {sup 27}Al(n,{alpha}){sup 24}Na reaction. Enriched samples were essential to determine the cross sections for the reactions with {sup 204}Pb{sup m} and {sup 206}Pb{sup m} isomers in the final state. Accurate results for reactions with {sup 204,206}Pb as target nuclei with natural lead samples were enabled through a precise measurement of the isotopic ratios. For a first investigation of the consequences of the present data for nuclear reaction models they were confronted with calculations based on global parameter systematics in a phenomenological and in a microscopic approach and with parameters selected to reproduce the available data. The TALYS code was used for the former two calculations involving parameter systematics while the STAPRE code was used for the latter calculation.

Semkova, V.; Reimer, P.; Altzitzoglou, T.; Plompen, A. J. M.; Quetel, C.; Sudar, S.; Vogl, J.; Koning, A. J.; Qaim, S. M.; Smith, D. L. [European Commission, Joint Research Centre, Institute for Reference Materials and Measurements, B-2440 Geel (Belgium); Nuclear Research and Consultancy Group NRG, P. O. Box 25, 1755 ZG Petten (Netherlands); Institut fuer Nuklearchemie, Forschungszentrum Juelich GmbH, D-52425 Juelich (Germany); Nuclear Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2009-08-15

331

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.

2009-04-02

332

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

333

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

334

Harmonic radar cross-section of bistatic nonlinear responder  

Microsoft Academic Search

Nonlinearly loaded antennas could be employed in a number of applications. Examples of such applications are related to anticollision aids in freeway traffic control and aircraft landing operations and ground station components in solar power satellite systems. The present investigation is concerned with the results of measurements regarding a microwave bistatic responder operating in the G-band (3.95-5.85 GHz). The receiving

O. M. Bucci; A. de Bonitatibus; I. Pinto

1984-01-01

335

Harmonic radar cross-section of bistatic nonlinear responder  

NASA Astrophysics Data System (ADS)

Nonlinearly loaded antennas could be employed in a number of applications. Examples of such applications are related to anticollision aids in freeway traffic control and aircraft landing operations and ground station components in solar power satellite systems. The present investigation is concerned with the results of measurements regarding a microwave bistatic responder operating in the G-band (3.95-5.85 GHz). The receiving and transmitting horns of the responder form an angle of approximately 67 deg. The experimental results obtained with the responder are compared with theoretical values computed on the basis of a Volterra series solution considered by Franceschetti and Pinto (1980). The agreement between theory and experimental values demonstrates both the accuracy of the model and the efficiency of the mathematical method.

Bucci, O. M.; de Bonitatibus, A.; Pinto, I.

1984-06-01

336

Radar Cross-Section Estimation of SAR Images  

Microsoft Academic Search

We present an algorithm that is able to smooth out the speckle from many SAR images and which does not suffer from the drawbacks of multilooking. The algorithm is able to preserve the detail and resolution of the original image while preserving a smooth, real-valued output. In many cases the quality of the smoothed image is sufficiently high that it

Ian Mcconnell; Richard White; Chris Oliver; Rod Cook

1995-01-01

337

Actinide Targets for Neutron Cross Section Measurements  

SciTech Connect

The Advanced Fuel Cycle Initiative (AFCI) and the Generation IV Reactor Initiative have demonstrated a lack of detailed neutron cross-sections for certain "minor" actinides, those other than the most common (235U, 238U, and 239Pu). For some closed-fuel-cycle reactor designs more than 50% of reactivity will, at some point, be derived from "minor" actinides that currently have poorly known or in some cases not measured (n,?) and (n,f) cross sections. A program of measurements under AFCI has begun to correct this. One of the initial hurdles has been to produce well-characterized, highly isotopically enriched, and chemically pure actinide targets on thin backings. Using a combination of resurrected techniques and new developments, we have made a series of targets including highly enriched 239Pu, 240Pu, and 242Pu. Thus far, we have electrodeposited these actinide targets. In the future, we plan to study reductive distillation to achieve homogeneous, adherent targets on thin metal foils and polymer backings. As we move forward, separated isotopes become scarcer, and safety concerns become greater. The chemical purification and electodeposition techniques will be described.

John D. Baker; Christopher A. McGrath

2006-10-01

338

Electron Collision Cross Sections for Iodine  

NASA Astrophysics Data System (ADS)

We performed a joint experimental and theoretical study of elastic electron scattering from atomic and molecular iodine. The experimental results for atomic iodine 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 [1] and an optical model potential approach [2]. 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 very encouraging. It suggests that the present results are suitable for use in modeling plasma kinetic behavior when iodine is an important constituent.[4pt] [1] O. Zatsarinny and K. Bartschat, Phys. Rev. A 77 (2008) 062701.[0pt] [2] F. Blanco and G. Garcia, Phys. Lett. A 317 (2003) 458 (2003).

Bartschat, K.; Zatsarinny, O.; Garcia, G.; Blanco, F.; Hargreaves, L. R.; Jones, D. B.; Murrie, R.; Brunton, J. R.; Brunger, M. J.; Hoshino, M.; Buckman, S. J.

2011-06-01

339

Pion production cross sections and associated parameters  

SciTech Connect

Negative pions have been used for radiotherapy at the meson factories LAMPF (USA), SIN (Switzerland), and TRIUMF (Canada) and have been planned for use at new meson facilities under construction (USSR) and at proposed dedicated medical facilities. Providing therapeutically useful dose rates of pions requires a knowledge of the pion production cross sections as a function of primary proton energy (500 to 1000 MeV), pion energy (less than or equal to100 MeV), production angle, and target material. The current status of the data base in this area is presented including theoretical guidelines for extrapolation purposes. The target material and geometry, as well as the proton and pion beam parameters, will affect the electron (and muon) contamination in the beam which may have an important effect on both the LET characteristics of the dose and the dose distribution. In addition to cross-section data, channel characteristics such as length of pion trajectory, solid-angle acceptance, and momentum analysis will affect dose rate, distribution, and quality. Such considerations are briefly addressed in terms of existing facilities and proposed systems. 16 refs., 6 figs.

Bradbury, J.N.

1985-01-01

340

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

341

FT-IR Measurements of Cold Cross Sections of Hydrocarbons  

NASA Astrophysics Data System (ADS)

We discuss temperature dependent cross sections of hydrocarbons by analyzing laboratory spectra in two approaches; 1) direct measurements of the cold cross sections, 2) derivation of pseudolines by fitting the laboratory spectra simultaneously.

Sung, K.; Toon, G. C.; Brown, L. R.

2014-02-01

342

Electron-Impact Excitation Cross Sections for Metal Vapors  

Microsoft Academic Search

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 sigma_BE and sigmaf

Yong-Ki Kim

2001-01-01

343

Mental Visualization of Objects from Cross-Sectional Images  

ERIC Educational Resources Information Center

We extended the classic anorthoscopic viewing procedure to test a model of visualization of 3D structures from 2D cross-sections. Four experiments were conducted to examine key processes described in the model, localizing cross-sections within a common frame of reference and spatiotemporal integration of cross sections into a hierarchical object…

Wu, Bing; Klatzky, Roberta L.; Stetten, George D.

2012-01-01

344

Cross-Sectional and Longitudinal Surveys of Dental Student Values: Limitations of Cross-Sectional Design.  

ERIC Educational Resources Information Center

Surveys of dental student values are described that were designed to assess value ratings by four dental classes in 1976, annual value ratings of a freshman class as they progressed through their four year program, and the usefulness of the cross-sectional design versus the longitudinal design. Each of the two surveys, which were conducted by the…

Sakumura, Joseph S.

345

Status of high energy neutron cross sections  

SciTech Connect

Review is presented of the current status of neutron-induced reactions of interest to the fusion community in the 10- to 50-MeV neutron energy range. Although there has been significant activity in this area since the 1977 BNL Symposium on Neutron Cross Sections from 10 to 40 MeV, this review concludes that there are many areas which require more experimentation to obtain the requested accuracy. Examples of various neutron data obtained since 1977 are presented and compared to determine the extent of agreement. An attempt is made to determine what the prospects are for satisfying the fusion data needs defined by the US DOE based upon progress to date.

Browne, J.C.; Lisowski, P.W.

1980-01-01

346

Geophysical Fluid Flow Cell (GFFC) Cross Section  

NASA Technical Reports Server (NTRS)

This drawing shows a cross-section view of the test cell at the heart of the Geophysical Fluid Flow Cell (GFFC) that flew on two Spacelab missions. The middle and lower drawings depict the volume of the silicone oil layer that served as the atmosphere as the steel ball rotated and an electrostatic field pulled the oil inward to mimic gravity's effects during the experiments. The GFFC thus produced flow patterns that simulated conditions inside the atmospheres of Jupiter and the Sun and other stars. The principal investigator was John Hart of the University of Colorado at Boulder. It was managed by NASA's Marshall Space Flight Center (MSFC). An Acrobat PDF copy of this drawing is available at http://microgravity.nasa.gov/gallery. (Credit: NASA/Marshall Space Flight Center)

1995-01-01

347

Flow duct with cross-sectional step  

US Patent & Trademark Office Database

In heat generators and burners, it is frequently necessary to realize discontinuous cross-sectional expansions of a flow duct. When the flow (U) passes over the step (10) formed in the wall (8) of the flow duct, coherent lateral separation vortices form which are propagated almost undamped downstream of the step and frequently represent the cause of thermo-acoustic vibrations of high amplitude. In accordance with the invention, vortex-generating elements (20) with a lateral pitch dimension (t) are arranged on a line transverse to the main flow (U) a distance (s) upstream of the step (10). Given an expedient selection of the pitch dimension (t), the lateral coherence of the separation vortex is enduringly destroyed.

2001-04-17

348

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

349

Spectroscopy and photoabsorption cross sections of FNO  

SciTech Connect

The spectroscopy and photoabsorption cross sections of nitrosyl fluoride are investigated in the spectral region 350-180 nm. Results for 350-250 nm are in good agreement with the initial measurements of Johnston and Bertin and later measurements from Solgadi and Flament and Huber et al. The spectrum is assigned to a series of vibrational progressions which arise from (0, 0, 0)[double prime] and involve excitation of the [nu][sub 1][prime] mode. Excitations to (n, 0, 0)[prime] and (n, 0, 1)[prime] make up the bulk of the spectrum, with promotions to (n, 1, 0)[prime], (n, 0, 2)[prime], and (n, 1, 2)[prime] becoming dominant at higher energies. Analysis of the spectrum results in values of [nu][sub 1][prime] = 1,096 cm[sup [minus]1], [nu][sub 2][prime] = 480 cm[sup [minus]1] and [nu][sub 3][prime] and [nu][sub 3][prime] is distinctly stronger than that for [nu][sub 2][prime]. Below 250 nm, a broad, featureless continuum absorption is observed, which rises in intensity from [sigma] = 1.77 [times] 10[sup [minus]20] cm[sub 2] at 245 nm to 5.24 [times] 10[sup [minus]19] cm[sub 2] at 180 nm.

Burley, J.D.; Miller, C.E.; Johnston, H.S. (Lawrence Berkeley Lab., CA (United States))

1993-04-01

350

[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

351

Electron collisions with CO: Elastic and vibrational excitation cross sections  

NASA Astrophysics Data System (ADS)

Absolute differential elastic and vibrational excitation cross sections up to v=11 were measured for CO in scattering angle ranges extending to 180° at energies between 0.2 and 5 eV (and an elastic measurement at 10 eV). The lowest angles were 0° for inelastic scattering and between 5° and 20° 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 , 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.

2010-04-01

352

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

353

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

354

Criticality benchmark comparisons leading to cross-section upgrades  

SciTech Connect

For several years criticality benchmark calculations with COG. COG is a point-wise Monte Carlo code developed at Lawrence Livermore National Laboratory (LLNL). It solves the Boltzmann equation for the transport of neutrons and photons. The principle consideration in developing COG was that the resulting calculation would be as accurate as the point-wise cross-sectional data, since no physics computational approximations were used. The objective of this paper is to report on COG results for criticality benchmark experiments in concert with MCNP comparisons which are resulting in corrections an upgrades to the point-wise ENDL cross-section data libraries. Benchmarking discrepancies reported here indicated difficulties in the Evaluated Nuclear Data Livermore (ENDL) cross-sections for U-238 at thermal neutron energy levels. This led to a re-evaluation and selection of the appropriate cross-section values from several cross-section sets available (ENDL, ENDF/B-V). Further cross-section upgrades anticipated.

Alesso, H.P.; Annese, C.E.; Heinrichs, D.P.; Lloyd, W.R.; Lent, E.M.

1993-03-01

355

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

356

A method for measuring light ion reaction cross-sections  

Microsoft Academic Search

An experimental procedure for measuring reaction cross-sections of light ions in the energy range 20–50MeV\\/nucleon, using a modified attenuation technique, is described. The detection method incorporates a forward detector that simultaneously measures the reaction cross-sections for five different sizes of the solid angle in steps from 99.1% to 99.8% of the total solid angle. The final reaction cross-section values are

R. F. Carlson; A. Ingemarsson; M. Lantz; G. J. Arendse; A. Auce; A. J. Cox; S. V. Förtsch; N. M. Jacobs; R. Johansson; J. Nyberg; J. Peavy; P.-U. Renberg; O. Sundberg; J. A. Stander; G. F. Steyn; G. Tibell; R. Zorro

2005-01-01

357

Inelastic Electron-Deuteron Scattering Cross Sections at High Energies  

Microsoft Academic Search

The effects on the cross sections for the inelastic electron-deuteron scattering process e+d-->e+n+p of interactions between the outgoing nucleons are examined in detail. The cross sections are calculated in the first Born approximation with respect to the electromagnetic interaction using nucleon wave functions modified by the final state interactions. Crude estimates indicate that the peak value of the cross section

Loyal Durand

1959-01-01

358

Nonlinear acoustic waves in channels with variable cross sections  

NASA Astrophysics Data System (ADS)

The point symmetry group is studied for the generalized Webster-type equation describing nonlinear acoustic waves in lossy channels with variable cross sections. It is shown that, for certain types of cross section profiles, the allowed 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.

Kovalev, V. F.; Rudenko, O. V.

2012-05-01

359

Radiation shape factors for channels with varying cross sections  

NASA Astrophysics Data System (ADS)

Robin's (1961) method of blocking by an intermediate segment is extended to include blocking by the horizon and by the orientation of the area radiated to, with application to radiative heat transfer in underground coal gasification. Good approximations are obtained for converting irregular cross sections to effective circular cross sections. Techniques for using these view factors to model radiation within irregularly shaped enclosures with nonisothermal cross sections are presented.

Eddy, T. L.; Nielsson, G. E.

1988-02-01

360

Total ionization cross-sections for fluoro acetylene molecule  

NASA Astrophysics Data System (ADS)

Total ionization cross-sections for Fluoro acetylene molecule is calculated by applying Binary Encounter Bethe (BEB) model by electron impact. The cross-sections are calculated in the energy range from ionization threshold to 2 keV. No experimental or theoretical work is reported in the literature to the best of my knowledge for comparison. Present work is a maiden attempt to find electron impact ionization cross section.

Pandya, C. V.

2014-04-01

361

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

362

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

363

Hafnium neutron cross sections and resonance analysis  

NASA Astrophysics Data System (ADS)

The focus of this thesis is to determine resonance parameters for the stable hafnium isotopes in the 0.005--200 eV region, with emphasis on the overlapping 176Hf and 178Hf resonances near 8 eV. The large neutron cross section of hafnium, combined with its corrosion resistance and excellent mechanical properties, make it an ideal material for controlling nuclear reactions. Experiments measuring neutron capture and transmission were performed at the Rensselaer Polytechnic Institute (RPI) LINAC using the time of flight method. Transmission experiments utilized 6Li glass scintillation detectors at flight path lengths of 15 and 25 m. Capture experiments were done using a sixteen section NaI(Tl) multiplicity type detector at a flight path length of 25 m. These experiments utilized various thicknesses of metallic and isotope-enriched liquid samples. The liquid samples were designed to provide information on the 176Hf and 178Hf contributions to the 8 eV doublet without saturation. Data analysis was done using the R-matrix Bayesian fitting code SAMMY version M6 beta. SAMMY is able to account for experimental resolution effects for each of the experimental setups at the RPI LINAC, and also can correct for some of the multiple scattering effects in yield data. The resolution function for specific experimental setups was determined. A method was developed for estimating errors on the fitted resonance parameters due to uncertainties in the resolution function parameters. The combined capture and transmission data analysis yielded resonance parameters for all stable hafnium isotopes from 0.005--200 eV. Resonance integrals were calculated along with errors for each of the hafnium isotopes using the NJOY and INTER codes. The isotopic resonance integrals calculated were significantly different than some of the previous values; however the calculated elemental hafnium resonance integral changed very little.

Trbovich, Michael J.

364

Thermal Neutron Capture Cross Section of 22Ne  

NASA Astrophysics Data System (ADS)

The radiative thermal neutron capture cross section of the astrophysically important 22Ne nucleus has been measured at the guided cold neutron beam of the Budapest Research Reactor. High-pressure gas-bottles filled with mixtures of enriched 22Ne and CH4 were used. The cross section was determined by means of the comparator method, and an improved decay-scheme obtained in this work. The new value for the thermal neutron cross section is 52.7+/-0.7 mb, 18% larger than the accepted value. The influence of the new cross section on the astrophysical reaction rate is under investigation.

Belgya, T.; Uberseder, E.; Petrich, D.; Käppeler, F.

2009-01-01

365

Derivation of reaction cross sections from experimental elastic backscattering probabilities  

NASA Astrophysics Data System (ADS)

The relationship between the backward elastic scattering probabilities and the reaction cross sections is derived. This is a very simple and useful method to extract reaction cross sections for heavy-ion systems. We compare the results of our method with those that use the traditional full elastic scattering angular distributions for several systems at energies near and above the Coulomb barrier. From the calculated reaction and capture cross sections that use the present method, we derive the cross sections of other mechanisms for weak nearly spherical systems.

Sargsyan, V. V.; Adamian, G. G.; Antonenko, N. V.; Gomes, P. R. S.

2013-10-01

366

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

367

14 MeV Neutrons SEU Cross Sections in Deep Submicron Devices Calculated Using Heavy Ion SEU Cross Sections  

Microsoft Academic Search

Ananalyticalmodelisdevelopedtocalculateneutron- induced SEU cross section in deep submicron devices from heavy ion SEU cross section. It is based on the energy spectra of the sec- ondaries of nuclear reactions which yields the LET dis- tribution of all secondary ions. The integration of this distribution function with the measured heavy ion cross section vs. LET yields then-SEUcrosssection.Tomakethecalculationsstraightforward, the neutron-induced LET distribution

Avner Haran; Joseph Barak; Leo Weissman; David David; Eitan Keren

2011-01-01

368

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

369

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

370

TOTAL CROSS SECTIONS FOR NEUTRON ENERGIES NEAR 14 Mev  

Microsoft Academic Search

The total cross section of C, Mg, Sd, Fe, Cu, Pb, and U has been ; measured for neutron energies near 14 Mev by transmission experiments with good ; geometry. The agreement with previous measurements is satisfactory; the general ; form of total cross section curves is the same for elements with neighboring A-; values; giant resonances have been found

J. F. Vervier; A. Martegani

1958-01-01

371

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

372

Differential cross sections for muonic hydrogen scattering on hydrogen molecules  

Microsoft Academic Search

The results of first calculations of the differential cross sections for muonic hydrogen scattering on hydrogen molecules are presented. They are functions of the initial and final kinetic energy of the system and the scattering angle. These calculations are based on the respective set of cross sections for muonic hydrogen scattering on hydrogen nuclei, obtained within the framework of the

Andrzej Adamczak

1993-01-01

373

Total electron impact excitation cross sections of Ar and Kr  

Microsoft Academic Search

A simple accurate method for normalizing the absolute magnitude of measured relative rare-gas excitation cross-section data to published measurements of the first Townsend coefficient is presented. Using a code which solved the Boltzmann equation we have determined that the predicted first Townsend coefficient is a very sensitive function of the electron impact excitation cross section. In Ar and Kr we

J. H. Jacob; J. A. Mangano

1976-01-01

374

Review of electron impact excitation cross sections for copper atom  

Microsoft Academic Search

Excitation of atomic copper by electron impact plays an important role in the copper vapor laser and accurate cross sections are needed for understanding and modeling laser performance. During the past seven years, there have been several attempts to normalize the relative elastic and inelastic cross sections measured by Trajmar and coworkers. However, each of these efforts have yielded different

N. W. Winter; A. U. Hazi

1982-01-01

375

Measurement of electron impact excitation cross sections for heliumlike titanium  

Microsoft Academic Search

The first measurement of electron impact excitation cross sections as a function of energy has been obtained for a highly charged ion. Collisional excitation cross sections to four n = 2 levels of He-like titanium were measured from threshold to 1.7 times threshold. The data conform well to established theory, especially for direct excitation; however, significant differences are found with

S. Chantrenne; P. Beiersdorfer; R. Cauble; M. B. Schneider

1992-01-01

376

ORELA Measurements to Meet Fusion Energy Neutron Cross Section Needs.  

National Technical Information Service (NTIS)

Major neutron cross section measurements made at the Oak Ridge Electron Linear Accelerator (ORELA) that are useful to the fusion energy program are reviewed. Cross sections for production of gamma rays with energies 0.3 < E/sub gamma / < 10.5 MeV were mea...

D. C. Larson

1980-01-01

377

Photoabsorption cross sections of methane from 1400 to 1850 A  

NASA Technical Reports Server (NTRS)

Photoabsorption cross sections of methane in the 1400-1850-A spectral region have been measured. Cross sections at wavelengths greater than 1475 A are approximately 200 times smaller than those currently accepted. This has a significant effect on the interpretation of spectral measurements of the Jovian planets in this wavelength region.

Mount, G. H.; Warden, E. S.; Moos, H. W.

1977-01-01

378

Scattering from parallel metallic cylinders with arbitrary cross sections  

Microsoft Academic Search

The integral equations for scattering by a set of parallel metallic cylinders, each cylinder of arbitrary cross section, are solved directly by means of a digital computer program giving the current distribution induced on the scatterer surfaces, the scattering cross section vs azimuthal angle, and the induced field ratio (IFR) for both parallel and perpendicularly polarized incident waves. The present

MOGENS G. ANDREASEN

1964-01-01

379

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

380

Measurement of cross sections at low p-pbar momenta  

SciTech Connect

In a recent experiment at the Low Energy Anti-Proton Ring (LEAR) at CERN, the p-pbar differential elastic and charge exchange (CEX) cross sections as well as the annihilation to charged and neutral pions cross section have been measured. A description of the experiment and some preliminary results are presented.

Brueckner, W.; Doebbeling, H.; von Harrach, D.; Kneis, H.; Majewski, S.; Nomachi, M.; Paul, S.; Povh, B.; Ransome, R.; Shibata, T.

1984-11-15

381

Neutron Capture Cross Sections: From Theory to Experiments and Back  

SciTech Connect

The method for an experimental determination of the stellar enhancement factor for the cross section of the 151Sm(n,{gamma}) reaction process is proposed. This study offered the pretext for an excursus on the interconnections between capture and dissociation reactions and the interplay between theory and experiments in the determination of neutron capture cross sections.

Mengoni, A. [CERN, CH-1211 Geneva 23 (Switzerland); ENEA, Via Don Fiammelli, 2 - 40129 Bologna (Italy)

2005-05-24

382

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

383

MEASUREMENTS OF RADIATIVE CAPTURE CROSS SECTIONS FOR FAST NEUTRONS  

Microsoft Academic Search

Cross-section measurements of radiative capture were made both for ; monoenergetic fast neutrons and for a wide spectra of fast neutrons by means of ; an activation method, as well as by neutron halance in the spherical geometry of ; the experiment, by capture gamma rays, and by reactivity measurements. ; Measurements of capture cross sections for a number of

A. I. Leipunskii; O. D. Kazachkovskii; G. Y. Artyukov

1959-01-01

384

Collision cross sections of gas phase DNA ions  

Microsoft Academic Search

Collision cross sections of negative ions of a 28-, 40- and 55-mer of single stranded DNA have been measured by an energy loss method, and compared to collision cross sections of proteins of nearly the same molecular weight—ubiquitin, cytochrome c and apomyoglobin, respectively. The oligonucleotides produce negative charge states in electrospray ionization (ESI) similar to the positive charge states produced

Annie Moradian; Mark Scalf; Michael S. Westphall; Lloyd M. Smith; D. J. Douglas

2002-01-01

385

Analysis of cross sections using various nuclear potential  

NASA Astrophysics Data System (ADS)

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; Kassim, Hasan Abu; Yusof, Norhasliza; Muhammad Zamrun, F.

2014-05-01

386

Born cross sections for ion-atom collisions  

Microsoft Academic Search

Selected total cross sections are calculated in the closure-Born approximation for the ions Li+, Cs+, and Au+ incident on several gas constituents. Targets included are H, H2, He, C, N, and O. Four general types of cross sections are considered depending on whether the incident ion or target atom is scattered elastically or inelastically. Expressions are given for the Born

George H. Gillespie; Yong-Ki Kim; Kwok-Tsang Cheng

1978-01-01

387

Difiractive and Total pp Cross Sections at LHC  

Microsoft Academic Search

The single-difiractive and total pp cross sections at the LHC are predicted in a phenomeno- logical approach that obeys all unitarity constraints. The approach is based on the renor- malization model of difiraction and a saturated Froissart bound for the total cross section yielding æt = (…=so) ¢ ln2(s=sF ) for s > sF , where the parameters so and

Konstantin Goulianos

388

Flow in Tubes of Non-Circular Cross-Sections  

Microsoft Academic Search

In this thesis steady, laminar, viscous, incompressible flow in tubes of non-circular cross sections is investigated. The specific aims of the investigation are (a) to look at the problems of both developing flow and fully developed flow, (b) to consider non-circular cross sections in a more systematic manner than has been done in the past, and (c) to develop a

Raushan Ara Quadir

1993-01-01

389

Neutron Induced Cross Sections for Radiochemistry for Isotopes of Arsenic  

SciTech Connect

We have developed a set of modeled nuclear reaction cross sections for use in radiochemical diagnostics. Local systematics for the input parameters required by the Hauser-Feshbach statistical model were developed and used to calculate neutron induced nuclear reaction cross sections for isotopes of Arsenic (Z = 33) in the mass range 71 {le} A {le} 77.

Kelley, K; Hoffman, R D; Dietrich, F S; Mustafa, M

2006-01-10

390

Facile synthesis, phase transition, optical switching and oxidation resistance properties of belt-like VO{sub 2}(A) and VO{sub 2}(M) with a rectangular cross section  

SciTech Connect

Highlights: ? Belt-like VO{sub 2}(A) with a rectangular cross section was synthesized. ? The formation mechanism of belt-like VO{sub 2}(A) was proposed. ? Belt-like VO{sub 2}(M) was prepared by the irreversible transformation of VO{sub 2}(A). ? VO{sub 2}(A) and VO{sub 2}(M) can be used as the optical switching materials. ? VO{sub 2}(A) and VO{sub 2}(M) have good oxidation resistance below 400 °C in air. -- Abstract: Belt-like VO{sub 2}(A) with a rectangular cross section (VA-RCS) was successfully synthesized using V{sub 2}O{sub 5}, H{sub 2}C{sub 2}O{sub 4}·2H{sub 2}O and H{sub 2}O as the starting materials by a facile hydrothermal approach. Some synthetic parameters, such as, the reaction time, reaction temperature and concentration of H{sub 2}C{sub 2}O{sub 4}·2H{sub 2}O, were systematically investigated to control the fabrication of belt-like VA-RCS. The formation mechanism of belt-like VA-RCS was proposed. Subsequently, belt-like VO{sub 2}(M) with a rectangular cross section (VM-RCS) was prepared by the irreversible transformation of VA-RCS at 700 °C for 2 h under the inert atmosphere. The phase transition temperature (T{sub c}) of VA-RCS and VM-RCS was evaluated by DSC test. The optical switching properties of VA-RCS and VM-RCS were studied by the variable-temperature infrared spectra, and it was found that the as-obtained VA-RCS and VM-RCS could be used as the optical switching materials. Furthermore, the oxidation resistance properties of VA-RCS and VM-RCS were investigated by TGA, indicating that they have good thermal stability and oxidation resistance below 400 °C in air.

Zhang, Yifu; Huang, Yanfen; Zhang, Juecheng; Wu, Weibing; Niu, Fei; Zhong, Yalan [College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China)] [College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China); Liu, Xinghai, E-mail: liuxh@whu.edu.cn [School of Printing and Packaging, Wuhan University, Wuhan 430079 (China)] [School of Printing and Packaging, Wuhan University, Wuhan 430079 (China); Liu, Xin [School of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China)] [School of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); Huang, Chi, E-mail: chihuang@whu.edu.cn [College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China)] [College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China)

2012-08-15

391

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

392

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

393

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

394

The Scattering Cross Section for a Target Irradiated by Time-varying Electromagnetic Waves  

Microsoft Academic Search

Based on the analysis of the target cross section, the cross section expression for a target irradiated by the time-varying electromagnetic waves is presented utilizing its cross section in frequency domain. Result shows that the cross section of a target is easy obtained in time domain if only its cross section in frequency domain is known. This cross section is

Y.-L. Li; J.-Y. Huang; M.-J. Wang; S.-H. Gong

2007-01-01

395

Cross-section adjustment techniques for BWR adaptive simulation  

NASA Astrophysics Data System (ADS)

Computational capability has been developed to adjust multi-group neutron cross-sections to improve the fidelity of boiling water reactor (BWR) modeling and simulation. The method involves propagating multi-group neutron cross-section uncertainties through BWR computational models to evaluate uncertainties in key core attributes such as core k-effective, nodal power distributions, thermal margins, and in-core detector readings. Uncertainty-based inverse theory methods are then employed to adjust multi-group cross-sections to minimize the disagreement between BWR modeling predictions and measured plant data. For this work, measured plant data were virtually simulated in the form of perturbed 3-D nodal power distributions with discrepancies with predictions of the same order of magnitude as expected from plant data. Using the simulated plant data, multi-group cross-section adjustment reduces the error in core k-effective to less than 0.2% and the RMS error in nodal power to 4% (i.e. the noise level of the in-core instrumentation). To ensure that the adapted BWR model predictions are robust, Tikhonov regularization is utilized to control the magnitude of the cross-section adjustment. In contrast to few-group cross-section adjustment, which was the focus of previous research on BWR adaptive simulation, multigroup cross-section adjustment allows for future fuel cycle design optimization to include the determination of optimal fresh fuel assembly designs using the adjusted multi-group cross-sections. The major focus of this work is to efficiently propagate multi-group neutron cross-section uncertainty through BWR lattice physics calculations. Basic neutron cross-section uncertainties are provided in the form of multi-group cross-section covariance matrices. For energy groups in the resolved resonance energy range, the cross-section uncertainties are computed using an infinitely-dilute approximation of the neutron flux. In order to accurately account for spatial and energy resonance self-shielding effects, the multi-group cross-section covariance matrix has been reformulated to include the uncertainty in resonance correction factors, or self-shielding factors, which are used to calculate the self-shielded multi-group cross-sections used in the lattice physics neutron transport model. This is shown to change the U-238 capture cross-section uncertainty contribution to Beginning-of-Life (BOL) lattice k-infinity by 14% (i.e. 0.291% relative standard deviation in k-infinity (self-shielded) compared to 0.255% (infinitely-dilute)). Using the reformulated multi-group cross-section covariance matrix, Efficient Subspace Methods (ESM) are used to propagate multi-group cross-section uncertainty through the lattice physics calculation. ESM algorithms have been developed by H. S. Abdel-Khalik and P. J. Turinsky to calculate low-rank approximations to large, dense sensitivity and covariance matrices used in data adjustment and uncertainty propagation applications. Using ESM, the singular value spectrum of the multi-group cross-section covariance matrix reveals an effective rank of the order of 103. Using this singular value decomposition of the multigroup cross-section covariance matrix reduces the number of lattice physics calculations per lattice from ˜107 to ˜10 3. In addition, a BOL sensitivity analysis using generalized perturbation theory at the lattice physics level is shown to further reduce the rank by a factor of 5.

Jessee, Matthew Anderson

396

Line shape cross sections of HD immersed in He and H2 gas. I - Pressure broadening cross sections  

Microsoft Academic Search

The results of two tests of the electronic potential energy surface of hydrogenlike systems are reported here, including the second virial coefficient of para hydrogen at low temperatures and HD-D2 elastic and inelastic differential scattering cross sections. Formulas are given for Dicke narrowing as well as for the line broadening and calculated shift cross sections. Close coupling calculations are performed

Joachim Schaefer; Louis Monchick

1987-01-01

397

Electron-impact ionization cross sections of atmospheric molecules  

SciTech Connect

A theoretical model for electron-impact total ionization cross sections, which has been found to be reliable for a wide range of molecules, is applied to molecules of interest to atmospheric science. The new theory, the binary-encounter-Bethe (BEB) model, combines the binary-encounter theory and the Bethe theory for electron-impact ionization, and uses simple theoretical data for the ground state of the target molecule, which are readily available from molecular structure codes. Total ionization cross sections of 11 molecules, CS, CS{sub 2}, COS, CH{sub 4}, H{sub 2}S, NH{sub 3}, NO{sub 2}, N{sub 2}O, O{sub 3}, S{sub 2}, and SO{sub 2}, are presented for incident electron energies from threshold to 1 keV with an average accuracy of 15{percent} or better at the cross section peak. We also found that the use of vertical ionization potentials (IPs) rather than adiabatic IPs for the lowest IPs significantly improves BEB cross sections between the threshold and cross section peak for molecules whose adiabatic and vertical IPs are different by {approximately}1 eV or more (CH{sub 4} and NH{sub 3}). The BEB cross sections are presented in a compact analytic form with a small number of constants, making the cross sections suitable for modeling applications. {copyright} {ital 1997 American Institute of Physics.}

Kim, Y.; Hwang, W.; Weinberger, N.M. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)] [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Ali, M.A. [Department of Chemistry, Howard University, Washington, D.C. 20059 (United States)] [Department of Chemistry, Howard University, Washington, D.C. 20059 (United States); Rudd, M.E. [Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0111 (United States)] [Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0111 (United States)

1997-01-01

398

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

399

Momentum transfer cross sections for the heavy noble gases  

NASA Astrophysics Data System (ADS)

We present momentum transfer cross sections for elastic electron scattering from argon, krypton and xenon atoms over the energy range from zero to 1 keV. These have been calculated using the Dirac equations with a relativistic complex optical potential which includes polarization of the target atom by the incident electron and allows for the absorption of some of the incident electron flux into channels representing excitation and ionization of the atom. In order to aid in plasma modelling calculations, we provide simple analytic fits to these cross sections as well as to the elastic scattering cross sections. Comparisons are made with previous experimental and theoretical results.

McEachran, R. P.; Stauffer, A. D.

2014-06-01

400

Low energy e-Ar momentum transfer cross-section  

SciTech Connect

Recent work has shown that solutions of the Boltzmann equation which use the so called {open_quotes}two-term{close_quotes} approximation provide an inadequate description of the transverse diffusion of electrons in argon gas at low values of E/N, contrary to earlier evidence. Previous determinations of the momentum transfer cross section for argon from the analysis of transport data have used two-term codes in good faith. Progress towards the determination of a new cross section in the energy range O - 4 eV, including an analysis of the energy dependence of the uncertainty in the derived cross section is reported.

Brennan, M.J.

1992-12-01

401

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

402

Modifying excitation transfer cross sections with an ac Stark effect.  

PubMed

We show that it is possible to manipulate electronic energy transfer collision cross sections between different atomic species by using a strong electromagnetic field close to resonance with a transition between two excited states to modify the energy levels (i.e., to create dressed states), which may be placed in or out of resonance with populated states (forming a population reservoir) in one of the species. We outline an estimate for a transfer cross section for a demonstration scheme and show that cross-section enhancements up to the order of 10(3) are possible. PMID:19745896

Coutts, J; Cooper, J; Burnett, K

1988-05-01

403

Actinide neutron-induced fission cross section measurements 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 in a wide energy range from sub-thermal energies up to 200 MeV. A parallel-plate ionization chamber are used to measure fission cross sections ratios relative to the {sup 235}U standard while incident neutron energies are determined using the time-of-flight method. Recent measurements include the {sup 233,238}U, {sup 239-242}Pu and {sup 243}Am neutron-induced fission cross sections. Obtained data are presented in comparison with ex isting evaluations and previous data.

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

2010-01-01

404

Absolute OH absorption cross sections (for lidar measurements)  

NASA Technical Reports Server (NTRS)

Experimental data are employed to calculate absorption cross sections for several rotational lines in the OH A-X system. The cross sections are computed as functions of the spectral and line widths and temperature of a laser beam, and account for lifetimes and branching ratios. Detection limits for the P1(2) transition of the (1,0) band were examined. The oscillator strengths and cross-sections obtained are important for quantifying OH concentrations in the stratosphere from lidar return signals.

Mcgee, T. J.; Mcilrath, T. J.

1984-01-01

405

CROSS SECTION MEASUREMENTS FOR CHARM PRODUCTION BY MUONS AND PHOTONS  

SciTech Connect

Interactions of 209-GeV muons in the Multimuon Spectrometer at Fermilab have yielded 20072 dimuon final states, with (81±10)% attributed to production of charmed states decaying to muons. The cross section for diffractive charm muoproduction is 6.9{sub -1.4}{sup +1.9} nb. Extrapolated to Q{sup 2} =0, the effective cross section for 178(100)-GeV photons is 750{sup +180}{sub -130} (560{sup +200}{sub -130}) nb, too small to explain the high-energy rise in the photon-nucleon total cross section.

Clark, A.R.; Johnson, K.J.; Kerth, L.T.; Loken, S.C.; Markiewicz, T.W.; Meyers, P.D.; Smith, W.H.; Strovink, M.; Wenzel, W.A.; Johnson, R.P.; Moore, C.; Mugge, M.; Shafer, R.E.; Gollin, G.D.; Shoemaker, F.C.; Surko, P.

1980-04-01

406

Fission cross sections in the intermediate energy region  

SciTech Connect

Until recently there has been very little cross section data for neutron-induced fission in the intermediate energy region, primarily because no suitable neutron source has existed. At Los Alamos, the WNR target-4 facility provides a high-intensity source of neutrons nearly ideal for fission measurements extending from a fraction of a MeV to several hundred MeV. This paper summarizes the status of fission cross section data in the intermediate energy range (En > 30 MeV) and presents our fission cross section data for {sup 235}U and {sup 238}U compared to intranuclear cascade and statistical model predictions.

Lisowski, P.W.; Gavron, A.; Parker, W.E.; Ullmann, J.L.; Balestrini, S.J. (Los Alamos National Lab., NM (USA)); Carlson, A.D.; Wasson, O.A. (National Inst. of Standards and Technology, Gaithersburg, MD (USA)); Hill, N.W. (Oak Ridge National Lab., TN (USA))

1991-01-01

407

Cross section for the subthreshold fission of {sup 236}U  

SciTech Connect

The cross section for {sup 236}U fission in the neutron-energy range E{sub n} = 0.001-20 keV was measured by using the INR RAS (Institute of Nuclear Research, Russian Academy of Sciences, Moscow) LSDS-100 neutron spectrometer of the lead slowing-down spectrometer type. The resonance fission areas of the resonances at 5.45 eV and 1.28 keV were found, and the fission widths of these resonances were evaluated. The cross section for the {sup 238}U(n, f) fission process was measured, and the threshold sensitivity of the LSDS-100 to small values of fission cross sections was estimated. The well-known intermediate structure in the cross section for the neutron-induced subbarrier fission of {sup 236}U was confirmed.

Alekseev, A. A.; Bergman, A. A.; Berlev, A. I.; Koptelov, E. A. [Russian Academy of Sciences, Institute for Nuclear Research (Russian Federation); Samylin, B. F.; Trufanov, A. M.; Fursov, B. I.; Shorin, V. S., E-mail: shorin@ippe.r [Institute of Physics and Power Engineering (Russian Federation)

2008-08-15

408

Cross section for the subthreshold fission of 236U  

NASA Astrophysics Data System (ADS)

The cross section for 236U fission in the neutron-energy range E n = 0.001 20 keV was measured by using the INR RAS (Institute of Nuclear Research, Russian Academy of Sciences, Moscow) LSDS-100 neutron spectrometer of the lead slowing-down spectrometer type. The resonance fission areas of the resonances at 5.45 eV and 1.28 keV were found, and the fission widths of these resonances were evaluated. The cross section for the 238U( n, f) fission process was measured, and the threshold sensitivity of the LSDS-100 to small values of fission cross sections was estimated. The well-known intermediate structure in the cross section for the neutron-induced subbarrier fission of 236U was confirmed.

Alekseev, A. A.; Bergman, A. A.; Berlev, A. I.; Koptelov, E. A.; Samylin, B. F.; Trufanov, A. M.; Fursov, B. I.; Shorin, V. S.

2008-08-01

409

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

NASA Astrophysics Data System (ADS)

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 is based on a data sample corresponding to an integrated luminosity of 36pb-1, at a proton-proton center-of-mass energy of s=7TeV. Cross sections are measured separately for each final state in fiducial regions of high detector acceptance, as well as in the full phase space, over the mass region 66-116 GeV. The individual cross sections are combined and the product of the total Z production cross section and Z??? branching fraction is measured to be 0.97±0.07(stat)±0.06(syst)±0.03(lumi)nb, in agreement with next-to-next-to-leading order calculations.

Aad, G.; Abbott, B.; Abdallah, J.; Abdelalim, A. A.; Abdesselam, A.; Abdinov, O.; Abi, B.; Abolins, M.; Abramowicz, H.; Abreu, H.; Acerbi, E.; Acharya, B. S.; Adams, D. L.; Addy, T. N.; Adelman, J.; Aderholz, M.; Adomeit, S.; Adragna, P.; Adye, T.; Aefsky, S.; Aguilar-Saavedra, J. A.; Aharrouche, M.; Ahlen, S. P.; Ahles, F.; Ahmad, A.; Ahsan, M.; Aielli, G.; Akdogan, T.; Åkesson, T. P. A.; Akimoto, G.; Akimov, A. V.; Akiyama, A.; Alam, M. S.; Alam, M. A.; Albert, J.; Albrand, S.; Aleksa, M.; Aleksandrov, I. N.; Alessandria, F.; Alexa, C.; Alexander, G.; Alexandre, G.; Alexopoulos, T.; Alhroob, M.; Aliev, M.; Alimonti, G.; Alison, J.; Aliyev, M.; Allport, P. P.; Allwood-Spiers, S. E.; Almond, J.; Aloisio, A.; Alon, R.; Alonso, A.; Alviggi, M. G.; Amako, K.; Amaral, P.; Amelung, C.; Ammosov, V. V.; Amorim, A.; Amorós, G.; Amram, N.; Anastopoulos, C.; Andari, N.; Andeen, T.; Anders, C. F.; Anderson, K. J.; Andreazza, A.; Andrei, V.; Andrieux, M.-L.; Anduaga, X. S.; Angerami, A.; Anghinolfi, F.; Anjos, N.; Annovi, A.; Antonaki, A.; Antonelli, M.; Antonov, A.; Antos, J.; Anulli, F.; Aoun, S.; Aperio Bella, L.; Apolle, R.; Arabidze, G.; Aracena, I.; Arai, Y.; Arce, A. T. H.; Archambault, J. P.; Arfaoui, S.; Arguin, J.-F.; Arik, E.; Arik, M.; Armbruster, A. J.; Arnaez, O.; Arnault, C.; Artamonov, A.; Artoni, G.; Arutinov, D.; Asai, S.; Asfandiyarov, R.; Ask, S.; Åsman, B.; Asquith, L.; Assamagan, K.; Astbury, A.; Astvatsatourov, A.; Atoian, G.; Aubert, B.; Auerbach, B.; Auge, E.; Augsten, K.; Aurousseau, M.; Austin, N.; Avolio, G.; Avramidou, R.; Axen, D.; Ay, C.; Azuelos, G.; Azuma, Y.; Baak, M. A.; Baccaglioni, G.; Bacci, C.; Bach, A. M.; Bachacou, H.; Bachas, K.; Bachy, G.; Backes, M.; Backhaus, M.; Badescu, E.; Bagnaia, P.; Bahinipati, S.; Bai, Y.; Bailey, D. C.; Bain, T.; Baines, J. T.; Baker, O. K.; Baker, M. D.; Baker, S.; Baltasar Dos Santos Pedrosa, F.; Banas, E.; Banerjee, P.; Banerjee, Sw.; Banfi, D.; Bangert, A.; Bansal, V.; Bansil, H. S.; Barak, L.; Baranov, S. P.; Barashkou, A.; Barbaro Galtieri, A.; Barber, T.; Barberio, E. L.; Barberis, D.; Barbero, M.; Bardin, D. Y.; Barillari, T.; Barisonzi, M.; Barklow, T.; Barlow, N.; Barnett, B. M.; Barnett, R. M.; Baroncelli, A.; Barone, G.; Barr, A. J.; Barreiro, F.; Barreiro Guimarães da Costa, J.; Barrillon, P.; Bartoldus, R.; Barton, A. E.; Bartsch, D.; Bartsch, V.; Bates, R. L.; Batkova, L.; Batley, J. R.; Battaglia, A.; Battistin, M.; Battistoni, G.; Bauer, F.; Bawa, H. S.; Beare, B.; Beau, T.; Beauchemin, P. H.; Beccherle, R.; Bechtle, P.; Beck, H. P.; Beckingham, M.; Becks, K. H.; Beddall, A. J.; Beddall, A.; Bedikian, S.; Bednyakov, V. A.; Bee, C. P.; Begel, M.; Behar Harpaz, S.; Behera, P. K.; Beimforde, M.; Belanger-Champagne, C.; Bell, P. J.; Bell, W. H.; Bella, G.; Bellagamba, L.; Bellina, F.; Bellomo, M.; Belloni, A.; Beloborodova, O.; Belotskiy, K.; Beltramello, O.; Ben Ami, S.; Benary, O.; Benchekroun, D.; Benchouk, C.; Bendel, M.; Benedict, B. H.; Benekos, N.; Benhammou, Y.; Benjamin, D. P.; Benoit, M.; Bensinger, J. R.; Benslama, K.; Bentvelsen, S.; Berge, D.; Bergeaas Kuutmann, E.; Berger, N.; Berghaus, F.; Berglund, E.; Beringer, J.; Bernardet, K.; Bernat, P.; Bernhard, R.; Bernius, C.; Berry, T.; Bertin, A.; Bertinelli, F.; Bertolucci, F.; Besana, M. I.; Besson, N.; Bethke, S.; Bhimji, W.; Bianchi, R. M.; Bianco, M.; Biebel, O.; Bieniek, S. P.; Biesiada, J.; Biglietti, M.; Bilokon, H.; Bindi, M.; Binet, S.; Bingul, A.; Bini, C.; Biscarat, C.; Bitenc, U.; Black, K. M.; Blair, R. E.; Blanchard, J.-B.; Blanchot, G.; Blazek, T.; Blocker, C.; Blocki, J.; Blondel, A.; Blum, W.; Blumenschein, U.; Bobbink, G. J.; Bobrovnikov, V. B.; Bocchetta, S. S.; Bocci, A.; Boddy, C. R.; Boehler, M.; Boek, J.; Boelaert, N.; Böser, S.; Bogaerts, J. A.; Bogdanchikov, A.; Bogouch, A.; Bohm, C.; Boisvert, V.; Bold, T.; Boldea, V.; Bolnet, N. M.; Bona, M.; Bondarenko, V. G.; Boonekamp, M.; Boorman, G.; Booth, C. N.; Bordoni, S.; Borer, C.; Borisov, A.; Borissov, G.; Borjanovic, I.; Borroni, S.; Bos, K.; Boscherini, D.; Bosman, M.; Boterenbrood, H.; Botterill, D.; Bouchami, J.; Boudreau, J.; Bouhova-Thacker, E. V.; Boulahouache, C.; Bourdarios, C.; Bousson, N.; Boveia, A.; Boyd, J.; Boyko, I. R.; Bozhko, N. I.; Bozovic-Jelisavcic, I.; Bracinik, J.; Braem, A.; Branchini, P.; Brandenburg, G. W.; Brandt, A.; Brandt, G.; Brandt, O.; Bratzler, U.; Brau, B.; Brau, J. E.; Braun, H. M.; Brelier, B.; Bremer, J.; Brenner, R.; Bressler, S.; Breton, D.; Britton, D.; Brochu, F. M.; Brock, I.; Brock, R.; Brodbeck, T. J.; Brodet, E.; Broggi, F.; Bromberg, C.; Brooijmans, G.; Brooks, W. K.; Brown, G.; Brown, H.; Bruckman de Renstrom, P. A.; Bruncko, D.; Bruneliere, R.; Brunet, S.; Bruni, A.; Bruni, G.; Bruschi, M.; Buanes, T.; Bucci, F.; Buchanan, J.

2011-12-01

410

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

411

56. CROSS SECTIONS OF CANAL AND TUNNELS. POWER CANAL, SALT ...  

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

56. CROSS SECTIONS OF CANAL AND TUNNELS. POWER CANAL, SALT RIVER RESERVOIR Courtesy of U.S.G.S., Reclamation Service - Roosevelt Power Canal & Diversion Dam, Parallels Salt River, Roosevelt, Gila County, AZ

412

Calculation of the cross section for top quark production.  

National Technical Information Service (NTIS)

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...

E. L. Berger H. Contopanagos

1996-01-01

413

Scaling Cross Sections for Ion-atom Impact Ionization  

SciTech Connect

The values of ion-atom ionization cross sections are frequently needed for many applications that utilize the propagation of fast ions through matter. When experimental data and theoretical calculations are not available, approximate formulas are frequently used. This paper briefly summarizes the most important theoretical results and approaches to cross section calculations in order to place the discussion in historical perspective and offer a concise introduction to the topic. Based on experimental data and theoretical predictions, a new fit for ionization cross sections is proposed. The range of validity and accuracy of several frequently used approximations (classical trajectory, the Born approximation, and so forth) are discussed using, as examples, the ionization cross sections of hydrogen and helium atoms by various fully stripped ions.

Igor D. Kaganovich; Edward Startsev; Ronald C. Davidson

2003-06-06

414

A new technique for dosimetry reaction cross-section evaluation  

SciTech Connect

Document available in abstract form only, full text of document follows: An objective of this paper is a unification of the procedure for dosimetry reaction cross-section evaluation. A set of requirements for the unified evaluation procedure is presented. A new code (ORTHO) was developed in order to meet these requirements. A statistical model, an algorithm, and the basic formulae employed in the code are described. The code was used for Ti48(n,p) reaction cross-section evaluation. The results of the evaluation are compared to International Reactor Dosimetry File (IRDF)-2002 data. The evaluated cross-sections and their correlations from this work are in good agreement with the IRDF-2002 evaluated data, whereas the uncertainties of the evaluated cross-sections are inconsistent. (authors)

Badikov, S.A. [JSC Energy and Industry Analytica, 127287, Moscow (Russian Federation)

2011-07-01

415

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

416

On the cyclo-synchrotron cross-section  

NASA Astrophysics Data System (ADS)

The study of the synchrotron and cyclotron absorption processes and their relative cross-sections, recently analysed by Ghisellini & Svensson, is extended to the case of photons propagating along the direction of the magnetic field. In the relativistic regime we follow a quantum approach, which requires first the derivation of the particle emissivity for the assumed configuration. The expression for the cross-section coincides with that obtained through a classical treatment of the problem in the non-relativistic regime. In the frequency range where absorption is important, the cross-section is larger than the Thomson cross-section by several orders of magnitude, implying a strong coupling between radiation and magnetized plasma. The possible atrophysical implications of this process are briefly discussed; in particular, in a magnetized plasma the Eddington luminosity for synchrotron interaction can be much lower than the standard value.

Gliozzi, M.; Bodo, G.; Ghisellini, G.; Trussoni, E.

1996-06-01

417

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

418

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

419

Absolute two-photon excitation cross-sections in NO  

NASA Technical Reports Server (NTRS)

A technique has been developed which allows the determination of a two-photon absorption cross-section to be made relative to the Raman scattering cross-section in nitrogen. Spatial and temporal effects associated with the lasers are ratioed out to give a result independent of laser parameters. The necessary theory to extract a cross-section from the measured ratio of a Coherent Anti-Stokes Raman Scattering (CARS) signal in N2 to a four-wave mixing signal in NO has been developed. The technique has been demonstrated on the R(22) + S(12) (J-double-prime = 9 1/2) line in NO and a cross-section of (2.9 + or - 1.8) x 10 to the -49th (cm to the 4th power)-s was determined. This technique appears to be applicable to a number of other diatomic molecules.

Burris, J.; Mcgee, T.; Mcilrath, T.

1984-01-01

420

Evaluation of Electron Ionization Cross Sections for Carbon Fullerenes  

NASA Astrophysics Data System (ADS)

Recently, we have introduced a semi empirical formulation for the calculation of partial and total integral ionization cross sections for C60 and C70 in the energy range from ionization threshold to 1000 eV which yielded results which were in satisfactory agreement with available experimental and theoretical data. Subsequently, we extended and generalized the same revisited JK semi empirical formulation for the evaluation of partial integral ionization cross sections for C2 dimmer and C3 trimmer. The major input data required in the formulation is the oscillator strength which is taken from the statistical sum of individual carbon atoms. The results are found in satisfactory agreement with the only theoretical calculation based on the modified additive rule (MAR). In addition to the partial integral ionization cross sections, we have also evaluated the ionization rate coefficients using the calculated ionization cross sections and Maxwell-Boltzmann distribution for the electrons as a function of energy.

Pal, Satyendra; Kumar, Neeraj

2011-11-01

421

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

422

A comparison of spatial sampling techniques enabling first principles modeling of a synthetic aperture RADAR imaging platform  

NASA Astrophysics Data System (ADS)

Simulation of synthetic aperture radar (SAR) imagery may be approached in many different ways. One method treats a scene as a radar cross section (RCS) map and simply evaluates the radar equation, convolved with a system impulse response to generate simulated SAR imagery. Another approach treats a scene as a series of primitive geometric shapes, for which a closed form solution for the RCS exists (such as boxes, spheres and cylinders), and sums their contribution at the antenna level by again solving the radar equation. We present a ray-tracing approach to SAR image simulation that treats a scene as a series of arbitrarily shaped facetized objects, each facet potentially having a unique radio frequency optical property and time-varying location and orientation. A particle based approach, as compared to a wave based approach, presents a challenge for maintaining coherency of sampled scene points between pulses that allows the reconstruction of an exploitable image from the modeled complex phase history. We present a series of spatial sampling techniques and their relative success at producing accurate phase history data for simulations of spotlight, stripmap and SAR-GMTI collection scenarios.

Gartley, Michael; Goodenough, Adam; Brown, Scott; Kauffman, Russel P.

2010-04-01

423

Line shape cross sections of HD immersed in He and H2 gas. I - Pressure broadening cross sections  

NASA Astrophysics Data System (ADS)

The results of two tests of the electronic potential energy surface of hydrogenlike systems are reported here, including the second virial coefficient of para hydrogen at low temperatures and HD-D2 elastic and inelastic differential scattering cross sections. Formulas are given for Dicke narrowing as well as for the line broadening and calculated shift cross sections. Close coupling calculations are performed for the R(0) and R(1) transitions of HD immersed in He and for the R(0) transition of HD immersed in H2. These cross sections are anticipated to be reliable at temperatures above 50 K.

Schaefer, Joachim; Monchick, Louis

1987-07-01

424

Electron-impact-excitation cross sections of hydrogenlike ions  

Microsoft Academic Search

Convergent close-coupling (CCC) and Coulomb-Born with exchange and normalization (CBE) methods are used to study electron-impact excitation of hydrogenlike ions. The nl-->n|IHl|IH cross sections demonstrate (i) good agreement between the CCC and CBE results, (ii) a scaling over ion nuclear charge z, (iii) a domination of the dipole (l|IH=l+\\/-1) contributions in total n-->n|IH cross sections, and (iv) significant effect of

Vladimir I. Fisher; Yuri V. Ralchenko; Vladimir A. Bernshtam; Alexander Goldgirsh; Yitzhak Maron; Leonid A. Vainshtein; Igor Bray; Helen Golten

1997-01-01

425

Electron-impact excitation cross sections of atomic silver  

Microsoft Academic Search

The method of extended crossed beams is used to measure excitation cross sections of atomic silver. The results, together\\u000a with theoretical data on the transition probabilities of AgI, are used to calculate the excitation cross sections of the energy\\u000a levels of the silver atom and the contribution of cascade population of states. It is found that the dependence of the

Yu. M. Smirnov

1999-01-01

426

Electron-impact-excitation cross sections of lithiumlike ions  

Microsoft Academic Search

We present an easy to use expression for cross sections of electron-impact-induced 1s2nl-->1s2n'l' excitation transitions with 2<=n<=n'<=4 in multiply charged ions of lithium isoelectronic sequence. This expression is based on our computations by convergent close-coupling (CCC) and Coulomb-Born with exchange and normalization (CBE) methods. We show scaling of the CCC and CBE cross sections with atomic number Z and use

V. I. Fisher; Yu. V. Ralchenko; V. A. Bernshtam; A. Goldgirsh; Y. Maron; L. A. Vainshtein; Igor Bray

1997-01-01

427

Asymptotic neutrino-nucleon cross section and saturation effects  

SciTech Connect

In this paper we present a simple analytic expression for the (spin-averaged) neutrino-nucleon cross section for ultrahigh energies at twist-2, obtained as the asymptotic limit of our previous findings. This expression gives values for the cross section in remarkable numerical agreement with the previous numerical evaluation in the energy region relevant for forthcoming neutrino experiments. Moreover, we discuss the role and the relevance of saturation and recombination effects in our approach, in comparison with other recent suggestions.

Fiore, R.; Papa, A. [Dipartimento di Fisica, Universita della Calabria, Istituto Nazionale di Fisica Nucleare, Gruppo collegato di Cosenza, I-87036 Arcavacata di Rende, Cosenza (Italy); Jenkovszky, L.L. [Bogolyubov Institute for Theoretical Physics, Academy of Sciences of Ukraine, UA-03143 Kiev (Ukraine); Kotikov, A.V. [Bogolyubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, RU-141980 Dubna (Russian Federation); Paccanoni, F. [Dipartimento di Fisica, Universita di Padova, Istituto Nazionale di Fisica Nucleare, Sezione di Padova, via F. Marzolo 8, I-35131 Padova (Italy)

2006-03-01

428

Total photoproduction cross section measurement at HERA energies  

Microsoft Academic Search

We present first results on the total photoproduction cross section measurement with the H1 detector at HERA. The data were extracted from low Q2 collisions of 26.7 GeV electrons with 820 GeV protons. The gammap total cross section has been measured by two independent methods in the gammap center of mass energy range from 90 to 290 GeV. For an

T. Ahmed; V. Andreev; B. Andrieu; M. Arpagaus; A. Babaev; H. Bärwolff; J. Bán; P. Baranov; E. Barrelet; W. Bartel; U. Bassler; G. A. Beck; H. P. Beck; H.-J. Behrend; A. Belousov; Ch. Berger; H. Bergstein; G. Bernardi; R. Bernet; U. Berthon; G. Bertrand-Coremans; M. Besançon; P. Biddulph; E. Binder; J. C. Bizot; V. Blobel; K. Borras; P. C. Bosetti; V. Boudry; C. Bourdarios; F. Brasse; U. Braun; W. Braunschweig; V. Brisson; D. Bruncko; J. Bürger; F. W. Büsser; A. Buniatian; S. Burke; G. Buschhorn; A. J. Campbell; T. Carli; F. Charles; D. Clarke; A. B. Clegg; M. Colombo; J. A. Coughlan; A. Courau; Ch. Coutures; G. Cozzika; L. Criegee; J. Cvach; J. B. Dainton; M. Danilov; A. W. E. Dann; W. D. Dau; M. David; E. Deffur; B. Delcourt; L. del Buono; M. Devel; A. de Roeck; P. Dingus; C. Dollfus; J. D. Dowell; H. B. Dreis; A. Drescher; J. Duboc; D. Düllmann; O. Dünger; H. Duhm; M. Eberle; J. Ebert; T. R. Ebert; G. Eckerlin; V. Efremenko; S. Egli; S. Eichenberger; R. Eichler; F. Eisele; E. Eisenhandler; N. N. Ellis; R. J. Ellison; E. Elsen; M. Erdmann; E. Evrard; L. Favart; A. Fedotov; D. Feeken; R. Felst; J. Feltesse; Y. Feng; I. F. Fensome; J. Ferencei; F. Ferrarotto; W. Flauger; M. Fleischer; P. S. Flower; G. Flügge; A. Fomenko; B. Fominykh; M. Forbush; J. Formánek; J. M. Foster; G. Franke; E. Fretwurst; P. Fuhrmann; E. Gabathuler; K. Gamerdinger; J. Garvey; J. Gayler; A. Gellrich; M. Gennis; U. Gensch; H. Genzel; R. Gerhards; D. Gillespie; L. Godfrey; U. Goerlach; L. Goerlich; M. Goldberg; A. M. Goodall; I. Gorelov; P. Goritchev; C. Grab; H. Grässler; T. Greenshaw; H. Greif; G. Grindhammer; C. Gruber; J. Haack; D. Haidt; L. Hajduk; O. Hamon; D. Handschuh; E. M. Hanlon; M. Hapke; J. Harjes; P. Hartz; R. Haydar; W. J. Haynes; J. Heatherington; V. Hedberg; R. Hedgecock; G. Heinzelmann; R. C. W. Henderson; H. Henschel; R. Herma; I. Herynek; W. Hildesheim; P. Hill; C. D. Hilton; J. Hladký; K. C. Hoeger; Ph. Huet; H. Hufnagel; N. Huot; M. Ibbotson; M. A. Jabiol; A. Jacholkowska; C. Jacobsson; M. Jaffre; L. Jönsson; K. Johannsen; D. P. Johnson; L. Johnson; H. Jung; P. I. P. Kalmus; S. Kasarian; R. Kaschowitz; P. Kasselmann; U. Kathage; H. H. Kaufmann; I. R. Kenyon; S. Kermiche; C. Kiesling; M. Klein; C. Kleinwort; G. Knies; T. Köhler; H. Kolanoski; F. Kole; S. D. Kolya; V. Korbel; M. Korn; P. Kostka; S. K. Kotelnikov; M. W. Krasny; H. Krehbiel; D. Krücker; U. Krüger; J. P. Kubenka; H. Küster; M. Kuhlen; T. Kurça; J. Kurzhöfer; B. Kuznik; R. Lander; M. P. J. Landon; R. Langkau; P. Lanius; J. F. Laporte; A. Lebedev; A. Leuschner; C. Leverenz; D. Levin; S. Levonian; Ch. Ley; A. Lindner; G. Lindström; P. Loch; H. Lohmander; G. C. Lopez; D. Lüers; N. Magnussen; E. Malinovski; S. Mani; P. Marage; J. Marks; R. Marshall; J. Martens; R. Martin; H.-U. Martyn; J. Martyniak; S. Masson; A. Mavroidis; S. J. Maxfield; S. J. McMahon; A. Mehta; K. Meier; T. Merz; C. A. Meyer; H. Meyer; J. Meyer; S. Mikocki; V. Milone; E. Monnier; F. Moreau; J. Moreels; J. V. Morris; J. M. Morton; K. Müller; P. Murín; S. A. Murray; V. Nagovizin; B. Naroska; Th. Naumann; D. Newton; H. K. Nguyen; F. Niebergall; R. Nisius; G. Nowak; G. W. Noyes; M. Nyberg; H. Oberlack; H. Obrock; J. E. Olsson; S. Orenstein; F. Ould-Saada; C. Pascaud; G. D. Patel; E. Peppel; S. Peters; H. T. Phillips; J. P. Phillips; Ch. Pichler; W. Pilgram; D. Pitzl; R. Prosi; F. Raupach; K. Rauschnabel; P. Reimer; P. Ribarics; V. Riech; J. Riedlberger; M. Rietz; S. M. Robertson; P. Robmann; R. Roosen; A. Rostovtsev; C. Royon; M. Rudowicz; M. Ruffer; S. Rusakov; K. Rybicki; E. Ryseck; J. Sacton; N. Sahlmann; E. Sanchez; D. P. C. Sankey; M. Savitsky; P. Schacht; P. Schleper; W. von Schlippe; C. Schmidt; D. Schmidt; W. Schmitz; V. Schröder; M. Schulz; A. Schwind; W. Scobel; U. Seehausen; R. Sell; M. Seman; A. Semenov; V. Shekelyan; I. Sheviakov; H. Shooshtari; G. Siegmon; U. Siewert; Y. Sirois; I. O. Skillicorn; P. Smirnov; J. R. Smith; L. Smolik; Y. Soloviev; H. Spitzer; P. Staroba; M. Steenbock; P. Steffen; R. Steinberg; H. Steiner; B. Stella; K. Stephens; J. Stier; J. Strachota; U. Straumann; W. Struczinski; J. P. Sutton; R. E. Taylor; G. Thompson; R. J. Thompson; I. Tichomirov; C. Trenkel; P. Truöl; V. Tchernyshov; J. Turnau; J. Tutas; L. Urban; A. Usik; S. Valkar; A. Valkarova; C. Vallee; P. van Esch; A. Vartapetian; Y. Vazdik; M. Vecko; P. Verrecchia; R. Vick; G. Villet; E. Vogel; K. Wacker; I. W. Walker; A. Walther; G. Weber; D. Wegener; A. Wegner; H. P. Wellisch; S. Willard; M. Winde; G.-G. Winter; Th. Wolff; L. A. Womersley; A. E. Wright; N. Wulff; T. P. Yiou; J. Áçek; P. Závada; C. Zeitnitz; H. Ziaeepour; M. Zimmer; W. Zimmermann; F. Zomer

1993-01-01

429

The nucleon-nucleon collision profile and cross section fluctuations  

NASA Astrophysics Data System (ADS)

The nucleon-nucleon collision profile, being the basic entity of the wounded nucleon model, is usually adopted in the form of a hard sphere or Gaussian shape. We suggest that the cross section fluctuations given by the gamma distribution leads to the profile function which smoothly ranges between both limiting forms. Examples demonstrating the sensitivity of the profile function on cross section fluctuations are discussed.

Rybczy?ski, Maciej; W?odarczyk, Zbigniew

2014-01-01

430

Electron differential cross section for H--He stripping collisions  

NASA Astrophysics Data System (ADS)

The Born approximation and a closure technique are employed to obtain the single and double differential cross sections for the ejected electron produced by electron detachment of H- ions in collisions with He. Comparison is made to the recent measurements of Menendez and Duncan at 0.5 MeV. The theoretical results show that the experimentally observed structure in the double differential cross sections in the forward direction can be explained in terms of single-electron-loss processes alone.

Franz, M. R.; Wright, L. A.; Genoni, T. C.

1981-08-01

431

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

432

Nuclear deformation and sub-barrier fusion cross sections  

Microsoft Academic Search

We present calculations of sub-barrier fusion cross sections for spherical projectiles and deformed targets. For a given spherical-projectile and deformed-target combination we calculate exactly the sum of the Coulomb and nuclear potentials. There are no free parameters in the calculations, except for a simple energy shift of the calculated cross sections. The shapes of the target nuclei are taken from

Akira Iwamoto; Peter Möller

1996-01-01

433

Absolute measurement of neutron cross sections. Progress report  

SciTech Connect

The procedures and status of the absolute measurement of the neutron capture cross sections for /sup 115/In and /sup 232/Th are described. Work on the /sup 239/Pu fission fragment anisotropy and absolute measurement of the fast neutron fission cross section for /sup 233/U are briefly described. Progress in establishing the 14 MeV neutron measurements at the facility are discussed. (WHK)

Knoll, G.F.

1981-02-19

434

Nucleon-nucleon cross sections in nuclear matter  

SciTech Connect

We provide a microscopic calculation of neutron-proton and neutron-neutron cross sections in symmetric nuclear matter at various densities, using the Brueckner-Hartree-Fock approximation scheme with the Paris potential. We investigate separately the medium effects on the effective mass and on the scattering amplitude. We determine average cross sections suitable for application in the dynamical simulation of heavy ion collisions, including a parametrization of their energy and density dependence. {copyright} {ital 1997} {ital The American Physical Society}

Schulze, H.; Schnell, A.; Roepke, G. [MPG-AG Theoretische Vielteilchenphysik, Universitaet Rostock, D-18051 Rostock (Germany)] [MPG-AG Theoretische Vielteilchenphysik, Universitaet Rostock, D-18051 Rostock (Germany); Lombardo, U. [Dipartimento di Fisica, Universita di Catania, Corso Italia 57, I-95129 Catania (Italy)] [Dipartimento di Fisica, Universita di Catania, Corso Italia 57, I-95129 Catania (Italy)

1997-06-01

435

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

436

The evaluation and application of redundant-cross-section covariances  

SciTech Connect

Certain multigroup covariance libraries, notably COVFILS-2, omit all redundant (or summed) reactions on the grounds that the information content of a well-measured total cross section, for example, is implicitly contained in the covariances of the component, or partial, reactions that add up to the total. It is shown that, while redundant reactions can play an important role in cross-section and covariance evaluation, their emission from libraries intended for applications is justifiable. 3 refs.

Muir, D.W.

1986-01-01

437

A shelf in the ''subthreshold'' photofission cross section  

Microsoft Academic Search

The influence of a double-humped fission barrier on the photofission ; cross section far below the top of the barrier is considered. In the region ; about 2 MeV below the top of the outer barrier and at a cross section in the ; region of 10⁻⁹⁻⁻¹°sup -6$ b the photofission is expected to become almost ; entirely isomeric or

Charles Bowman

1975-01-01

438

Thermal Neutron Capture Cross Sections Of The Palladium Isotopes  

Microsoft Academic Search

We have measured precise thermal neutron capture gamma-ray cross sections cry for all stable Palladium isotopes with the guided thermal neutron beam from the Budapest Reactor. The data were compared with other data from the literature and have been evaluated into the Evaluated Gamma-ray Activation File (EGAF). Total radiative neutron capture cross-sections sigmagamma can be deduced from the sum of

R. B. Firestone; M. Krtiáka; D. P. McNabb; B. Sleaford; U. Agvaanluvsan; T. Belgya; Zs. Révay

2006-01-01

439

Thermal Neutron Capture Cross Sections of The Palladium Isotopes  

Microsoft Academic Search

We have measured precise thermal neutron capture γ-ray cross sections Ï{sub γ} for all stable Palladium isotopes with the guided thermal neutron beam from the Budapest Reactor. The data were compared with other data from the literature and have been evaluated into the Evaluated Gamma-ray Activation File (EGAF)[1]. Total radiative neutron capture cross-sections Ïâ can be deduced from the sum

R B Firestone; M Krticka; D P McNabb; B Sleaford; U Agvaanluvsan; T Belgya; Z Revay

2005-01-01

440

Cross section of hadron production in gammagamma collisions at LEP  

Microsoft Academic Search

The reaction e+e- -> e+e-gamma*gamma* -> e+e-hadrons is analysed using data collected by the L3 detector during the LEP runs at &surd;s= 130-140 GeV and &surd;s= 161 GeV. The cross sections sigma(e+e- -> e+e-hadrons) and sigma(gammagamma -> hadrons) are measured in the interval 5 <= Wgammagamma hadrons) cross section is consistent with the universal Regge behaviour of total hadronic cross

M. Acciarri; O. Adriani; M. Aguilar-Benitez; S. Ahlen; J. Alcaraz; G. Alemanni; J. Allaby; A. Aloisio; G. Alverson; M. G. Alviggi; G. Ambrosi; H. Anderhub; V. P. Andreev; T. Angelescu; F. Anselmo; A. Arefiev; T. Azemoon; T. Aziz; P. Bagnaia; L. Baksay; S. Banerjee; K. Banicz; A. Barczyk; R. Barillère; L. Barone; P. Bartalini; A. Baschirotto; M. Basile; R. Battiston; A. Bay; F. Becattini; U. Becker; F. Behner; J. Berdugo; P. Berges; B. Bertucci; B. L. Betev; S. Bhattacharya; M. Biasini; A. Biland; G. M. Bilei; J. J. Blaising; S. C. Blyth; G. J. Bobbink; R. Bock; A. Böhm; L. Boldizsar; B. Borgia; D. Bourilkov; M. Bourquin; S. Braccini; J. G. Branson; V. Brigljevic; I. C. Brock; A. Buffini; A. Buijs; J. D. Burger; W. J. Burger; J. Busenitz; A. Button; X. D. Cai; M. Campanelli; M. Capell; G. Cara Romeo; G. Carlino; A. M. Cartacci; J. Casaus; G. Castellini; F. Cavallari; N. Cavallo; C. Cecchi; M. Cerrada; F. Cesaroni; M. Chamizo; Y. H. Chang; U. K. Chaturvedi; S. V. Chekanov; M. Chemarin; A. Chen; G. Chen; H. F. Chen; H. S. Chen; X. Chereau; G. Chiefari; C. Y. Chien; L. Cifarelli; F. Cindolo; C. Civinini; I. Clare; R. Clare; H. O. Cohn; G. Coignet; A. P. Colijn; N. Colino; V. Commichau; S. Costantini; F. Cotorobai; B. de La Cruz; A. Csilling; T. S. Dai; R. D'Alessandro; R. de Asmundis; A. Degré; K. Deiters; D. della Volpe; P. Denes; F. Denotaristefani; D. Dibitonto; M. Diemoz; D. van Dierendonck; F. di Lodovico; C. Dionisi; M. Dittmar; A. Dominguez; A. Doria; M. T. Dova; D. Duchesneau; P. Duinker; I. Duran; S. Dutta; S. Easo; Yu. Efremenko; H. El Mamouni; A. Engler; F. J. Eppling; F. C. Erné; J. P. Ernenwein; P. Extermann; M. Fabre; R. Faccini; S. Falciano; A. Favara; J. Fay; O. Fedin; M. Felcini; B. Fenyi; T. Ferguson; F. Ferroni; H. Fesefeldt; E. Fiandrini; J. H. Field; F. Filthaut; P. H. Fisher; I. Fisk; G. Forconi; L. Fredj; K. Freudenreich; C. Furetta; Yu. Galaktionov; S. N. Ganguli; P. Garcia-Abia; S. S. Gau; S. Gentile; N. Gheordanescu; S. Giagu; S. Goldfarb; J. Goldstein; Z. F. Gong; A. Gougas; G. Gratta; M. W. Gruenewald; V. K. Gupta; A. Gurtu; L. J. Gutay; B. Hartmann; A. Hasan; D. Hatzifotiadou; T. Hebbeker; A. Hervé; W. C. van Hoek; H. Hofer; S. J. Hong; H. Hoorani; S. R. Hou; G. Hu; V. Innocente; K. Jenkes; B. N. Jin; L. W. Jones; P. de Jong; I. Josa-Mutuberria; A. Kasser; R. A. Khan; D. Kamrad; Yu. Kamyshkov; J. S. Kapustinsky; Y. Karyotakis; M. Kaur; M. N. Kienzle-Focacci; D. Kim; J. K. Kim; S. C. Kim; Y. G. Kim; W. W. Kinnison; A. Kirkby; D. Kirkby; J. Kirkby; D. Kiss; W. Kittel; A. Klimentov; A. C. König; A. Kopp; I. Korolko; V. Koutsenko; R. W. Kraemer; W. Krenz; A. Kunin; P. Ladron de Guevara; I. Laktineh; G. Landi; C. Lapoint; K. Lassila-Perini; P. Laurikainen; M. Lebeau; A. Lebedev; P. Lebrun; P. Lecomte; P. Lecoq; P. Le Coultre; J. M. Le Goff; R. Leiste; E. Leonardi; P. Levtchenko; C. Li; C. H. Lin; W. T. Lin; F. L. Linde; L. Lista; Z. A. Liu; W. Lohmann; E. Longo; W. Lu; Y. S. Lu; K. Lübelsmeyer; C. Luci; D. Luckey; L. Luminari; W. Lustermann; W. G. Ma; M. Maity; G. Majumder; L. Malgeri; A. Malinin; C. Maña; D. Mangeol; S. Mangla; P. Marchesini; A. Marin; J. P. Martin; F. Marzano; G. G. G. Massaro; D. McNally; R. R. McNeil; S. Mele; L. Merola; M. Meschini; W. J. Metzger; M. von der Mey; Y. Mi; A. Mihul; A. J. W. van Mil; G. Mirabelli; J. Mnich; P. Molnar; B. Monteleoni; R. Moore; S. Morganti; T. Moulik; R. Mount; S. Müller; F. Muheim; A. J. M. Muijs; S. Nahn; M. Napolitano; F. Nessi-Tedaldi; H. Newman; T. Niessen; A. Nippe; A. Nisati; H. Nowak; Y. D. Oh; H. Opitz; G. Organtini; R. Ostonen; C. Palomares; D. Pandoulas; S. Paoletti; P. Paolucci; H. K. Park; I. H. Park; G. Pascale; G. Passaleva; S. Patricelli; T. Paul; M. Pauluzzi; C. Paus; F. Pauss; D. Peach; Y. J. Pei; S. Pensotti; D. Perret-Gallix; B. Petersen; S. Petrak; A. Pevsner; D. Piccolo; M. Pieri; J. C. Pinto; P. A. Piroué; E. Pistolesi; V. Plyaskin; M. Pohl; V. Pojidaev; H. Postema; N. Produit; D. Prokofiev; G. Rahal-Callot; N. Raja; P. G. Rancoita; M. Rattaggi; G. Raven; P. Razis; K. Read; D. Ren; M. Rescigno; S. Reucroft; T. van Rhee; S. Riemann; K. Riles; A. Robohm; J. Rodin; B. P. Roe; L. Romero; S. Rosier-Lees; Ph. Rosselet; W. van Rossum; S. Roth; J. A. Rubio; D. Ruschmeier; H. Rykaczewski; J. Salicio; E. Sanchez; M. P. Sanders; M. E. Sarakinos; S. Sarkar; M. Sassowsky; C. Schäfer; V. Schegelsky; S. Schmidt-Kaerst; D. Schmitz; P. Schmitz; N. Scholz; H. Schopper; D. J. Schotanus; J. Schwenke; G. Schwering; C. Sciacca; D. Sciarrino; L. Servoli; S. Shevchenko; N. Shivarov; V. Shoutko; J. Shukla; E. Shumilov; A. Shvorob; T. Siedenburg; D. Son; A. Sopczak; B. Smith; P. Spillantini; M. Steuer; D. P. Stickland; A. Stone; H. Stone; B. Stoyanov; A. Straessner; K. Strauch; K. Sudhakar; G. Sultanov; L. Z. Sun; G. F. Susinno; H. Suter; J. D. Swain; X. W. Tang; L. Tauscher; L. Taylor

1997-01-01

441

Mental visualization of objects from cross-sectional images.  

PubMed

We extended the classic anorthoscopic viewing procedure to test a model of visualization of 3D structures from 2D cross-sections. Four experiments were conducted to examine key processes described in the model, localizing cross-sections within a common frame of reference and spatiotemporal integration of cross sections into a hierarchical object representation. Participants used a hand-held device to reveal a hidden object as a sequence of cross-sectional images. The process of localization was manipulated by contrasting two displays, in situ vs. ex situ, which differed in whether cross sections were presented at their source locations or displaced to a remote screen. The process of integration was manipulated by varying the structural complexity of target objects and their components. Experiments 1 and 2 demonstrated visualization of 2D and 3D line-segment objects and verified predictions about display and complexity effects. In Experiments 3 and 4, the visualized forms were familiar letters and numbers. Errors and orientation effects showed that displacing cross-sectional images to a remote display (ex situ viewing) impeded the ability to determine spatial relationships among pattern components, a failure of integration at the object level. PMID:22217386

Wu, Bing; Klatzky, Roberta L; Stetten, George D

2012-04-01

442

Asymptotic behaviour of pion-pion total cross-sections  

NASA Astrophysics Data System (ADS)

We derive a sum rule which shows that the Froissart-Martin bound for the asymptotic behaviour of the ?? total cross sections at high energies, if modulated by the Lukaszuk-Martin coefficient of the leading log2 s behaviour, cannot be an optimal bound in QCD. We next compute the total cross sections for ? + ? -, ? ± ? 0 and ? 0 ? 0 scattering within the framework of the constituent chiral quark model (C ?QM) in the limit of a large number of colours N c and discuss their asymptotic behaviours. The same ?? cross sections are also discussed within the general framework of Large- N c QCD and we show that it is possible to make an Ansatz for the isospin I = 1 and I = 0 spectrum which satisfy the Froissart-Martin bound with coefficients which, contrary to the Lukaszuk-Martin coefficient, are not singular in the chiral limit and have the correct Large- N c counting. We finally propose a simple phenomenological model which matches the low energy behaviours of the cross section predicted by the C ?QM with the high energy behaviour predicted by the Large- N c Ansatz. The magnitude of these cross sections at very high energies is of the order of those observed for the pp and scattering total cross sections.

Greynat, David; de Rafael, Eduardo; Vulvert, Grégory

2014-03-01

443

Mental visualization of objects from cross-sectional images  

PubMed Central

We extended the classic anorthoscopic viewing procedure to test a model of visualization of 3D structures from 2D cross-sections. Four experiments were conducted to examine key processes described in the model, localizing cross-sections within a common frame of reference and spatiotemporal integration of cross sections into a hierarchical object representation. Participants used a hand-held device to reveal a hidden object as a sequence of cross-sectional images. The process of localization was manipulated by contrasting two displays, in-situ vs. ex-situ, which differed in whether cross sections were presented at their source locations or displaced to a remote screen. The process of integration was manipulated by varying the structural complexity of target objects and their components. Experiments 1 and 2 demonstrated visualization of 2D and 3D line-segment objects and verified predictions about display and complexity effects. In Experiments 3 and 4, the visualized forms were familiar letters and numbers. Errors and orientation effects showed that displacing cross-sectional images to a remote display (ex-situ viewing) impeded the ability to determine spatial relationships among pattern components, a failure of integration at the object level.

Wu, Bing; Klatzky, Roberta L.; Stetten, George D.

2011-01-01

444

Minimizing the statistical error in capture cross-section measurements  

NASA Astrophysics Data System (ADS)

Measurements of the neutron capture cross-section are performed by measurement of the capture rate of a sample placed in a neutron beam. The capture rate is measured by surrounding the sample with gamma-ray detectors. The capture rate is corrected for background and divided by the rate of neutrons incident on the sample in order to obtain the capture yield. The neutron capture cross-section can be obtained from the capture yield if additional information such as the total or scattering cross-section is known. An error analysis was performed on the measured capture cross-section. The error was minimized with respect to the experimental time split of the capture, background and incident neutron rates and also with respect to the sample thickness. These calculations are useful for the planning of an efficient capture cross-section experiment. The derived equations are compared to experimental data and show excellent agreement. This type of error analysis and minimization is also valid for other types of partial cross-section measurements such as fission and scattering which have similar expressions for the measured yield.

Danon, Yaron; Block, Robert C.

2005-06-01

445

Determining neutron capture cross sections via the surrogate reaction technique  

SciTech Connect

Indirect methods play an important role in the determination of nuclear reaction cross sections that are hard to measure directly. In this paper we investigate the feasibility of using the so-called surrogate method to extract neutron capture cross sections for low-energy compound-nuclear reactions in spherical and near-spherical nuclei. We present the surrogate method and develop a statistical nuclear reaction simulation to explore different approaches to utilizing surrogate reaction data. We assess the success of each approach by comparing the extracted cross sections with a predetermined benchmark. In particular, we employ regional systematics of nuclear properties in the 34{<=}Z{<=}46 region to calculate (n,{gamma}) cross sections for a series of Zr isotopes and to simulate a surrogate experiment and the extraction of the desired cross section. We identify one particular approach that may provide very useful estimates of the cross section, and we discuss some of the limitations of the method. General recommendations for future (surrogate) experiments are also given.

Forssen, C. [Fundamental Physics, Chalmers University of Technology, SE-41296 Goeteborg (Sweden); Lawrence Livermore National Laboratory, P.O. Box 808, L-414, Livermore, California 94551 (United States); Dietrich, F. S.; Escher, J.; Hoffman, R. D.; Kelley, K. [Lawrence Livermore National Laboratory, P.O. Box 808, L-414, Livermore, California 94551 (United States)

2007-05-15

446

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 A?2 with an exception near 70-80 eV.

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

2013-04-01

447

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

448

Calculation of beam neutralization in the IPNS-Upgrade RCS  

SciTech Connect

The author calculated the neutralization of circulating beam in this report. In the calculation it is assumed that all electrons liberated from the background molecules due to the collisional processes are trapped in the potential well of the proton beam. Including the dependence of ionization cross sections on the kinetic energy of the incident particle, the author derived the empirical formula for beam neutralization as a function of time and baseline vacuum pressure, which is applicable to the one acceleration cycle of the IPNS-Upgrade RCS.

Chae, Yong-Chul

1995-01-26

449

Radar  

Microsoft Academic Search

Over 1,000,000 km2 of the equatorial surface of Mars west of the Arsia Mons volcano displays no 3.5-cm radar echo to the very low level of the radar system noise for the Very Large Array; the area displaying this unique property has been terms \\

James R. Zimbelman; Kenneth S. Edgett

1994-01-01

450

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

451

Measurements of pion single charge exchange cross sections in deuterium  

SciTech Connect

Cross sections for the d({pi}{sup {minus}},{pi}{sup 0})nn reaction at incident pion energies of 164, 263, and 371 MeV have been measured. One crate of the LAMPF Neutral Meson Spectrometer, composed of 60 CsI crystals, was used to detect both photons from the {pi}{sup 0} decay. The acceptance of the detector was obtained by comparing measured p({pi}{sup {minus}}, {pi}{sup 0})n yields to the known cross sections. No previous measurement of single charge exchange cross sections for deuterim exists between 164 MeV and 500 MeV. An impulse approximation calcuation including a realistic nucleon momentum distribution describes the energy spectra in the doubly differential cross section well. The low energy tail deviating from the calculation can be attributed to multiple-scattering effects. A Faddeev calculation at 164 MeV incorporating Pauli-blocking and multiple-scattering agrees well with the measured angular distribution. At the two higher energies the d({pi}{sup {minus}},{pi}{sup 0})nn differential cross section is essentially identical to that for p({pi}{sup {minus}},{pi}{sup 0})n, except at forward angles where the former is suppressed by the Pauli principle.

Matthews, J.L.; Park, H.T.; Pate, S.F. [and others

1995-04-01

452

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

453

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

454

Active radar stealth device  

Microsoft Academic Search

This patent discloses an active radar stealth device mounted on a host platform for minimizing the radar cross-section of the host platform. A coating which is essentially microwave transparent is attached to the surface of a host platform and is exposed to an incident microwave field. A plurality of detector\\/emitter pairs contained within the coating detect and actively cancel, respectively,

R. N. Cain; Albert J. Corda

1991-01-01

455

Low Frequency Impedance of Tapered Transitions with Arbitrary Cross Sections  

SciTech Connect

We study the impedance of a tapered transition at small frequencies for an arbitrary shape of the transition cross section. Our approach does not require a symmetry axis in the system (unlike round geometry). We show that the calculation of the impedance reduces to finding a few auxiliary potential functions that satisfy two-dimensional Poisson equations with Dirichlet boundary conditions. In simple cases such solutions can be obtained analytically; for more complicated geometries they can easily be found numerically. We apply our method to axisymmetric geometry and reproduce results known from the literature. We then calculate the impedance of a taper with rectangular cross section in which the vertical dimension of the cross section is a slowly changing function of the longitudinal coordinate. Finally, we find a transverse kick experienced by a beam passing near a conducting wall with a variable distance from the beam to the wall.

Stupakov, G.; /SLAC

2007-07-23

456

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

457

Measurement of Neutron Capture Cross Sections of Selenium Isotopes  

NASA Astrophysics Data System (ADS)

There have been numerous measurements of the neutron capture cross sections of the stable Se isotopes, most dating from at least 40 years ago. The various results for individual isotopes are often in poor agreement with one another, but as yet there has been no attempt at a systematic measurement of the capture cross sections leading to all seven radioisotopes formed from capture by natural Se, which range in halflife from 17 s to 120 d. Using cadmium-shielded and unshielded irradiations of natural Se in various irradiation sites in OSU's TRIGA reactor, we have determined the thermal cross sections and resonance integrals for captures leading to ^75,77m,79m,81g,81m,83g,83mSe.

Dearmon, Howard D.; Krane, Kenneth S.

2011-10-01

458

Cross-Sectional HIV Incidence Estimation in HIV Prevention Research  

PubMed Central

Accurate methods for estimating HIV incidence from cross-sectional samples would have great utility in prevention research. This report describes recent improvements in cross-sectional methods that significantly improve their accuracy. These improvements are based on the use of multiple biomarkers to identify recent HIV infections. These multi-assay algorithms (MAAs) use assays in a hierarchical approach for testing that minimizes the effort and cost of incidence estimation. These MAAs do not require mathematical adjustments for accurate estimation of the incidence rates in study populations in the year prior to sample collection. MAAs provide a practical, accurate, and cost-effective approach for cross-sectional HIV incidence estimation that can be used for HIV prevention research and global epidemic monitoring.

Brookmeyer, Ron; Laeyendecker, Oliver; Donnell, Deborah; Eshleman, Susan H.

2013-01-01

459

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

460

Lactiferous vessel detection from microscopic cross-sectional images  

NASA Astrophysics Data System (ADS)

This paper presents the methods to detect and segment lactiferous vessels or rubber latex vessels from gray scale microscopic cross-sectional images using polynomial curve-fitting with maximum and minimum stationary points. Polynomial curve-fitting is used to detect the location of lactiferous vessels from an image of a non-dyed cross-sectional slice which was taken by a digital camera through microscope lens. The lactiferous vessels are then segmented from an image using maximum and minimum stationary points with morphological closing operation. Two species of rubber trees of age between one to two years old are sampled namely, RRIM600 and RRIT251. Two data sets contain 30 microscopic cross-sectional images of one-year old rubber tree's stems from each species are used in the experiments and the results reveal that most of the lactiferous vessel areas can be segmented correctly.

Jariyawatthananon, Jirapath; Cooharojananone, Nagul; Lipikorn, Rajalida

2014-04-01

461

Neutrino Cross Section Measurements @ SciBooNE  

SciTech Connect

We report measurements of cross sections of neutrinos of 0.7 GeV average energy scattering off a carbon target cross sections with by the SciBooNE experiment at Fermilab. These measurements are important inputs for current and future accelerator-based neutrino oscillation experiments in the interpretation of neutrino oscillation signals. The measurement of neutrino mixing angle {theta}{sub 13} is one of the most important goals in current neutrino experiments. For the current and next generation of long baseline neutrino oscillation experiments, T2K, NOvA and LBNE, the precise measurement of neutrino-nucleus cross sections in the few GeV energy range is an essential ingredient in the interpretation of neutrino oscillation signals.

Mariani, C.; /Columbia U.

2011-10-01

462

Testing wave packet dynamics in computing radiative association cross sections  

NASA Astrophysics Data System (ADS)

A time-dependent wave packet method is used to compute cross sections for radiative recombination reactions using the Li(2S)+H+-->LiH+(X 2?+)+? as a test case. Cross sections are calculated through standard time-to-energy mapping of the time-dependent transition moment and a useful method is introduced to deal with the low collision energy regime. Results are in quantitative agreement over the whole energy range 10-4-5 eV with previous time-independent results for the same system [I. Baccarelli, L. Andric, T. Grozdanov, and R. McCarroll, J. Chem. Phys. 117, 3013 (2002)], thereby suggesting that the method can be of help in computing radiative association cross sections for more complicated systems.

Martinazzo, Rocco; Tantardini, Gian Franco

2005-03-01

463

Nucleon-nucleon cross sections in dense nuclear matter  

SciTech Connect

We present microscopic calculations of cross sections for scattering of identical and nonidentical nucleons in symmetric nuclear matter at various densities, using the Brueckner-Hartree-Fock approximation scheme with the Argonne v{sub 14} potential including the contribution of microscopic three-body forces. We investigate separately the effects of three-body forces on the effective mass and on the scattering amplitude. In the present calculation, the rearrangement contribution of the three-body force is considered, which reduces the neutron and proton effective mass and suppresses the magnitude of the cross section. The presence of 'Z diagrams' in the three-body force enables us to make a comparison with the medium effects on the nucleon-nucleon cross sections obtained with the Dirac-Brueckner-Hartree-Fock approximation.

Zhang, H. F. [School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000 (China); Li, Z. H. [INFN-LNS, Via S. Sofia 64, I-95123 Catania (Italy); Lombardo, U. [INFN-LNS, Via S. Sofia 64, I-95123 Catania (Italy); Dipartimento di Fisica e Astronomia, Via A. Doria 6, I-95123 Catania (Italy); Luo, P. Y.; Zuo, W. [Institute of Modern Physics, Chinese Academy of Science, Lanzhou 730000 (China); Sammarruca, F. [Physics Department, University of Idaho, Moscow, Idaho 83844-0903 (United States)

2007-11-15

464

Inversion of rotationally inelastic differential cross sections under sudden conditions  

SciTech Connect

An inversion method for rotationally inelastic atom--diatom differential cross sections based on the infinite-order-sudden (IOS) approximation is presented. It consists of two separate steps: (1) The scattering phase shift, which is a function of the partial wave parameter l and the orientation angle ..gamma.., is determined by least-squares fitting of the reference cross sections. (2) For fixed orientation ..gamma.. the R dependence of the interaction potential in obtained from the l dependence of the phase shift using the Firsov technique. This method is applicable in the so-called strong coupling case when rotational rainbow features are dominant and yields information about the anisotropy of the potential surface in the repulsive region. Because of the centrifugal sudden condition, scattering systems with deep potential wells cannot be treated by the present method. Test calculations are performed using theoretical IOS cross sections obtained from a realistic He--Na/sub 2/ surface as reference data.

Schinke, R.

1980-12-15

465

Quality of life of patients with ADPKD—Toranomon PKD QOL study: cross-sectional study  

PubMed Central

Background The quality of life (QOL) of patients with autosomal dominant polycystic kidney disease (ADPKD) has not been investigated well. This study was performed to clarify the QOL of patients with ADPKD and to identify factors that affected their QOL. Methods The present cross-sectional study is part of a prospective observational study on the QOL of ADPKD patients. Patients with ADPKD who were referred to Toranomon Hospital between March 2010 and November 2012 were enrolled. The short form-36 (SF-36) questionnaire and our original 12-item questionnaire were used to evaluate QOL. We analyzed the results of the questionnaire survey and then investigated correlations between QOL and clinical features. Results A total of 219 patients (93 men and 126 women) were enrolled and their mean age was 55.1±10.8 years. There were 108 patients on dialysis. The SF-36 scores (PCS, MCS, and RCS) of all patients were significantly lower than the mean scores for the Japanese population. Stepwise multiple regression analysis demonstrated that Hb, serum Alb, ascites, and cerebrovascular disease all had a significant influence on the PCS, while mental disease had a significant influence on the MCS and serum Alb significantly influenced the RCS. The total liver and kidney volume (TLKV) and the dialysis status were not significantly associated with any of the SF-36 scores by multiple regression analysis, but TLKV was closely correlated with abdominal distention and distention had an important influence on QOL. Pain, sleep disturbance, heartburn, fever, gross hematuria, and anorexia also affected QOL, but these variables were not correlated with TLKV. Conclusions Several factors influence QOL, so improving symptoms unrelated to TLKV as well as reducing abdominal distention can improve the QOL of ADPKD patients.

2013-01-01

466

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 validati