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1

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

2

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

3

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

4

Advanced radar cross section clutter removal algorithms  

Microsoft Academic Search

Producing good quality radar cross section (RCS) measurement data of a target is proportional to the extent of clutter mitigation. Although RCS measurements usually include clutter reduction methods, typically some level of clutter remains in the target data. In order to achieve maximum RCS data quality several computational clutter removal algorithms have been developed, each having strengths and weaknesses, which

Andre Bati; Long To; Don Hilliard

2010-01-01

5

Radar cross section of a long wire  

Microsoft Academic Search

Monostatic radar cross-section (RCS) results for five- and eleven-wavelength straight wires are presented. The numerical RCS values which are obtained from solving Pocklington's integral equation for the induced current by collocation fall within 1 dB of the experimental measurements over all major lobes of the RCS pattern. The computer times required for the computations are 1.2 and 7.6 seconds for

E. Miller; G. Burke; B. Maxum; G. Pjerrov; A. Neureuther

1969-01-01

6

The radar cross section reduction of microstrip patches  

Microsoft Academic Search

The radar cross section (RCS) reduction of microstrip patch antennas for low-observable platforms is considered, with emphasis on the application of lossy superstrates. The observed effect of these on antenna parameters is related to expected RCS reduction using results from the literature. The RCS computed by a finite element method\\/method of moments code is also presented. Other RCS reduction techniques

C. B. Wilsen; D. B. Davidson

1996-01-01

7

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

8

Precision radar cross-section measurements for computer code validation  

Microsoft Academic Search

Precision measurements of the radar cross section (RCS) of simple rod and cylinder targets for all angles of incidence in a plane containing the long axis of the target are presented. The RCS is presented as a contour map as a function of the frequency and the incidence angle. These extensive measured RCS data are used as a reference for

S. R. Mishra; C. L. Larose; C. W. Trueman

1993-01-01

9

Radar cross section prediction and measurement at 77 GHz  

Microsoft Academic Search

This paper presents a comparison of predicted and measured radar cross sections (RCS) of complex metallic objects at 77 GHz. For computing the RCS, a ray tracing algorithm combined with physical optics and the incremental length diffraction coefficient is used. The simulated results are compared against measurements, obtained using a 77-GHz frequency-modulated continuous-wave radar sensor.

Markus Treml; Reinhard Feger; Christoph Wagner; Andreas Stelzer; H. Jager

2009-01-01

10

On the meteoric head echo radar cross section angular dependence  

Microsoft Academic Search

We present radar cross section (RCS) measurements of meteor head echoes observed with the tristatic 930 MHz EISCAT UHF radar system. The three receivers offer a unique possibility to accurately compare the monostatic RCS of a meteor target with two simultaneously probed bistatic RCSs at different aspect angles. Meteoroids from all possible directions entering the common volume monitored by the

J. Kero; C. Szasz; G. Wannberg; A. Pellinen-Wannberg; A. Westman

2008-01-01

11

Retrodirective array radar cross-section performance comparisons  

Microsoft Academic Search

This paper reports on the comparison of the radar cross-section (RCS) of a 4-element retrodirective array (RDA) calculated from its measured gain with the predicted RCS of a flat plate, and a 90° dihedral corner reflector. The comparison showed that the boresight RCS of the 4-element RDA is 2.33 dB higher than the boresight RCS of the 90° dihedral passive

B. Y. Toh; V. F. Fusco

2000-01-01

12

Radar cross section of human cardiopulmonary activity for recumbent subject  

Microsoft Academic Search

The radar cross section (RCS) corresponding to human cardio-respiratory motion is measured for a subject in two different recumbent positions. Lying face-up (supine), the subject showed an RCS of 0.326 m2. But when lying face-down (prone), the RCS increased to 2.9 m2. This is the first reported RCS measurement corresponding to human cardio-respiratory motion. The results obtained in this experiment

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

2009-01-01

13

Radar cross section reduction of aircraft wing front end  

Microsoft Academic Search

In this paper we present a comparison of two methods for radar cross section reduction (RCSR) of a wing-front profile. The aim is to reduce RCS over the frequency range 1-16 GHz in a forward sector of the traveling direction. We achieved a 5 dB reduction of the two dimensional mono-static radar cross section (RCS) for 68% (or more) of

A. Motevasselian; B. L. G. Jonsson

2009-01-01

14

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

15

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

16

Radar Cross Section measurements of small Unmanned Air Vehicle Systems in non-cooperative field environments  

Microsoft Academic Search

The growing use of unmanned air vehicle systems (UAVS) is drawing increased interest in their radar signature to search and track radars. Because it is not always possible to transport UAVS to radar cross section (RCS) measurement facilities, a portable RCS measurement system has been developed and demonstrated in non-cooperative field environments. This paper presents the portable RCS measurement system

A. Bati; D. Hilliard

2009-01-01

17

Microwave techniques for radar cross section measurements: a review  

Microsoft Academic Search

During the past several years, the increasing interest taken in radar signature reduction techniques has induced the development of radar cross section (RCS) measurement facilities. Various principles and techniques are used to perform these characterizations. This paper recapitulates the different types of experimental set-up dedicated to this kind of measurements. The illumination arrangements and the instrumentation systems generally adopted are

J. Garat

1996-01-01

18

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

19

A 100 GHz Polarimetric Compact Radar Range for Scale-Model Radar Cross Section Measurements  

E-print Network

William E. Nixon U.S. Army National Ground Intelligence Center Charlottesville, VA 22902 l Abstract for obtaining radar cross section, inverse synthetic aperture radar imagery and high range resolution profiles. Keywords: Compact Radar Range, Doppler, Imagery, Instrumentation, ISAR, Millimeter-Wave, Radar, RCS

Massachusetts at Lowell, University of

20

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

21

Accurate Radar Cross Section Modelling of Jet Inlets & Engines  

Microsoft Academic Search

SUMMARY Most of the industrial software codes used for the prediction of the radar cross-section (RCS) of aircrafts are based on ray tracing. While ray based methods give useful scattered fields from the skin of the aircraft illuminated by an incident plane wave, they largely fail to predict the returns from cavities onboard. As a possible enhancement to these ray-tracing

Kwok Kee Chan; Silvester Wong; Edwin Riseborough

22

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

23

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

24

A Method to Measure Radar Cross Section Parameters of Antennas  

Microsoft Academic Search

A new method to measure radar cross section (RCS) parameters of antennas is presented in this paper. This method relies on an equation derived for the received signal power which is represented as the superposition of structural-mode scattered, antenna-mode scattered, and leakage signals. The method also measures relative phase and provides the effect of the load connected to the antenna.

Sudhir Shrestha; M. D. Balachandran; Mangilal Agarwal; Li-He Zou; Kody Varahramyan

2008-01-01

25

Orientation of a support pylon used in radar cross section measurements  

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

2007-01-01

26

Radar cross section of the human heartbeat and respiration  

Microsoft Academic Search

This paper describes an experimental approach for finding the radar cross section (RCS) of human heartbeats and respiratory movements. A measurement setup, a calibration routine and required processing steps are presented. Using a 2-3GHz Ultra Wideband (UWB) radar, heartbeats and respiration of a human subject were recorded from a distance of 1.14m. Combining the recorded data to measurements with a

O. Aardal; Svein-Erik Hamran; T. Berger; J. Hammerstad; T. S. Lande

2010-01-01

27

Extended Characterisation Of A UHF Direction Finding Antenna With Optimised Radar Cross Section  

Microsoft Academic Search

In R. Mueller et. al. (2006) the design of a UHF direction finding antenna with optimised radar cross section (RCS) was introduced. In the present paper the monostatic RCS of the antenna is characterised up to 18 GHz. Measured results of the RCS are compared to simulated results which are obtained using the new commercially available multilevel fast multipole method

Rainer Mueller; Ralf Lorch; Wolfgang Menzel

2007-01-01

28

An estimation and verification of vessel radar-cross-sections for HF surface wave radar  

Microsoft Academic Search

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 and by using measurements from a HFSWR system at Cape Race, Newfoundland, Canada. The results of the study indicate that Teleost, a 2405-ton Canadian Coast Guard ship, and large cargo-container vessels (?36000 ton) have comparable

Harold Wilson; Hank Leong

2003-01-01

29

An improved physical optics method for the computation of radar cross section of electrically large objects  

Microsoft Academic Search

An improved physical optics method for the computation of radar cross section of electrically large objects is presented. The method is quite general to compute the radar cross section (RCS) of arbitrarily shaped metal structures by rigorously transforming the radiation surface integral in the traditional PO method to a line integral along the metal boundary. Since the line integral is

Chonghua Fang; Xiaonan Zhao; Qian Liu

2008-01-01

30

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

31

Radar cross section dependence on wind speed  

Microsoft Academic Search

YSCAT was an ultrawideband (2-20 GHz), near constant beamwidth scatterometer intended to provide radar cross section measurements at varying radar and environmental parameters. YSCAT was deployed on the CCIW (Canada Center for Inland Waters) tower on Lake Ontario for a period of six months in 1994. Using YSCAT data, this paper reports (1) observance of a “low wind-speed cutoff”, the

David G. Long; Ben E. Barrowes; David V. Arnold

1999-01-01

32

Investigation of metamaterial coated conducting cylinders for achieving transparency and maximizing radar cross section  

Microsoft Academic Search

Recently, reducing the radar cross sections (RCS) of various structures to achieve transparency and obtaining resonant structures aimed at increasing the electromagnetic intensities, stored or radiated power levels have been investigated. The transparency and resonance (RCS maximization) conditions investigated in are mainly attributed to pairing of \\

Erdinc Irci; Vakur B. Erturk

2007-01-01

33

Evaluation of the radar cross section of circular microstrip patches on anisotropic and chiral substrates  

Microsoft Academic Search

Galerkin's method in the Hankel transform domain (HTD) is applied to the determination of the radar cross section (RCS) of a circular microstrip patch printed on a substrate which may be an uniaxial anisotropic dielectric, a magnetized ferrite, or a chiral material. The results obtained for circular patches on magnetized ferrites show that the RCS of these patches can be

V. Losada; R. R. Boix; F. Medina

2001-01-01

34

RECONFIGURABLE YAGI-UDA SUBSTRATE FOR RADAR CROSS SECTION REDUCTION OF PATCH ANTENNA  

Microsoft Academic Search

In this paper, a new Yagi-Uda substrate is proposed to obtain radar cross section (RCS) reduction. The Yagi-Uda substrate on which three kinds of metal microstrip lines are etched is put directly on the top of a patch antenna and can reduce RCS sharply by steering the direction of reflecting wave at resonant frequencies. Using a reconfiguration technique, the antenna

S.-C. Zhao; B.-Z. Wang; W. Shao

2009-01-01

35

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

36

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

37

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

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

38

NUFFT-Based Near-Field Imaging Technique for Far-Field Radar Cross Section Calculation  

Microsoft Academic Search

Near-field images can be applied to determine the far-field radar cross section (RCS) of the target overcoming the need for long-range measurement setups. This letter presents a far-field RCS calculation technique based on the nonuniform fast Fourier transformation (NUFFT). The NUFFT is first incorporated in the near-field imaging procedure, and then is used for the subsequent RCS calculation. Comparisons of

Shiyong Li; Bocheng Zhu; Houjun Sun

2010-01-01

39

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

40

From radar cross section to electrostatics  

Microsoft Academic Search

This letter discusses the connection of a dynamic electromagnetic variable, the radar cross section, and a static parameter, the polarizability. It is shown that with full-wave electromagnetic computation of the scattering of a sphere, its static response can be enumerated with good accuracy with remarkably few unknowns. The result suggests that the code can be used with success to also

Ari Sihvola; Tapan K. Sarkar; B. Kolundzija

2004-01-01

41

RCS Reduction of Array Antennas with Radar Absorbing Structures  

Microsoft Academic Search

This paper introduces a radar absorbing structures (RAS) applied to reduce the in-band radar cross section (RCS) of the array antennas. The structure of the RAS is based on square patch structure loaded with lumped resistances. An array with four patch elements was designed and built, and the RAS was located between two adjacent patch elements. The simulated and measured

F.-W. Wang; S.-X. Gong; S. Zhang; X. Mu; T. Hong

2011-01-01

42

Role of Radar Cross Section facilities in a Radar and Electronic Warfare Defence Research and Evaluation capability  

Microsoft Academic Search

Abstract: This paper demonstrates the role of Radar Cross Section (RCS) facilities, consisting of modelling and simulation (M&S), Hardware in the Loop- (HWIL) and field Test and Evaluation (T&E) environments, in a Radar and Electronic Warfare (EW) Defence Research and Evaluation capability. The link between the development and utilisation of radar and EW facilities and the scientific process is illustrated

Ewerlank Pienaar; Thomas Küsel; Pieter Goosen; Christo Cloete; Louis Botha

43

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

Microsoft Academic Search

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

Christophe Bourlier; Philippe Pouliguen

2009-01-01

44

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

45

Radar cross-section modeling of marine vessels in practical oceanic environments for high-frequency surface-wave radar  

Microsoft Academic Search

Models of the Teleost marine vessel and the Bonn express cargo freighter are developed for generation of monostatic and bistatic radar cross section (RCS) returns for high-frequency surface-wave radar (HFSWR). Simulated monostatic RCS values are in good agreement with measured values at 4.1 MHz, thus additional investigations, to model varied practical situations may also be of interest. Specifically, the effects

Symon K. Podilchak; Hank Leong; Ryan Solomon; Yahia M. M. Antar

2009-01-01

46

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

47

Transient ultra wide band measurement applications: radar cross section, synthetic aperture radar, electromagnetic compatibility  

Microsoft Academic Search

The Electronic Armament Centre (CELAR: Centre d'Electronique de L'Armement) and the Research Institute of Microwave and Optical Communications (IRCOM: Institut de Recherches en Communications Optiques et Micro-ondes) has evaluated the use of ultra-wide-band (UWB) short pulse measurement facilities to characterize target electromagnetic signatures. A first device is capable of determining the radar cross section (RCS) within a 200 MHz to

J. Andrieu; C. Dubois; M. Lalande; V. Bertrand; P. Delmote; B. Beillard; E. Martinod; B. Jecko; R. Guilleret; F. Monnier; M. Legoff

2003-01-01

48

A Novel Two-Dimensional Extrapolation Technique for Fast and Accurate Radar Cross Section Computation  

Microsoft Academic Search

In this letter, a novel two-dimensional (2-D) extrapolation technique for the approximation of three-dimensional (3-D) radar cross section (RCS) pattern is presented. The best uniform rational approximation, performed by the Maehly approximation, is applied to the method of moments (MoM) to predict the 3-D monostatic RCS pattern. Compared to the asymptotic waveform evaluation (AWE) technique, the major advantage of the

Jin Ling; Shu-Xi Gong; Xing Wang; Bao Lu; Wen-Tao Wang

2010-01-01

49

Study and Optimization of Plasma-Based Radar Cross Section Reduction Using Three-Dimensional Computations  

Microsoft Academic Search

The radar cross section (RCS) of a flat plate covered with a cold collisional inhomogeneous plasma has been studied using a 3-D finite-difference time-domain (FDTD) method for electromagnetics. Two problems have been considered. In problem 1, using experimentally reported plasma density profiles, we have observed some interesting features in the bistatic RCS and provided simple physical interpretations for some of

Bhaskar Chaudhury; Shashank Chaturvedi

2009-01-01

50

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

51

Full polarimetric calibration for radar cross-section measurements: performance analysis  

Microsoft Academic Search

Full polarimetric scattering measurements are increasingly required for radar cross-section (RCS) tests. Conventional calibration fails to take into account the small amount of antenna cross-polarization coupling that will be present for any practical antenna. In contrast, full polarimetric calibration takes into account and compensates for the nonideal couplings in the transmit and receive channels and paths. We use an existing

Byron M. Welsh; Brian M. Kent; Alan L. Buterbaugh

2004-01-01

52

Radar cross section of stacked circular microstrip patches on anisotropic and chiral substrates  

Microsoft Academic Search

Galerkin's method in the Hankel transform domain (HTD) is applied to the determination of the radar cross section (RCS) of stacked circular microstrip patches fabricated on a two-layered substrate which may be made of a uniaxial anisotropic dielectric, a magnetized ferrite or a chiral material. Concerning the case of stacked patches printed on magnetized ferrites, the results show that substantial

V. Losada; R. R. Boix; F. Medina

2003-01-01

53

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

54

Acceleration of Ray-Based Radar Cross Section Predictions Using Monostatic-Bistatic Equivalence  

Microsoft Academic Search

An approach is presented to simulate the monostatic scattering properties of complex shaped realistic objects in a very efficient way. To achieve this, the calculation of the radar cross section (RCS) in the high frequency regime based on the well known shooting and bouncing rays (SBR) technique is considerably accelerated by the use of the monostatic bistatic equivalence principle. Instead

Hermann Buddendick; Thomas F. Eibert

2010-01-01

55

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

56

Measurements of the radar cross section and Inverse Synthetic Aperture Radar (ISAR) images of a Piper Navajo at 9.5 GHz and 49 GHz  

Microsoft Academic Search

Studies were conducted of the enhanced radar cross section (RCS) and improved inverse synthetic aperture radar (ISAR) image quality that may result at millimeter-wave (mmw) frequencies. To study the potential for mmw radar in these areas, a program was initiated in FY-90 to design and fabricate a 49.0- to 49.5-GHz stepped-frequency radar. After conducting simultaneous measurements of the RCS of

R. Dinger; G. Kinzel; W. Lam; S. Jones

1993-01-01

57

Wireless Measurement of radar cross section using Surface Acoustic Wave sensors in MEMS  

Microsoft Academic Search

In this paper a simple and efficient numerical procedure for treating problems of radar cross section (RCS) prediction of arbitrarily shaped Perfect Electric Conductor (PEC) objects is developed using Micro-ElectroMechanicalSystems(MEMS). Surface Acoustic Wave (SAW) devices perform a radar measurement using impulse response of the SAW transponder via a high frequency electromagnetic radio link. By analyzing the time delay between the

Suresh Kumar Perumal; M. Madheswaran

2008-01-01

58

Calibration standards and uncertainties in radar cross section measurements  

Microsoft Academic Search

Standards for radar cross section measurements are being developed cooperatively by NIST and DoD scientists. Three technical areas were defined as the foundation of such an effort: (1) monostatic single-channel calibration, (2) full polarimetric calibration using a scattering matrix formalism, and (3) analysis of radar cross section calibration and measurement uncertainty. The authors reviews the results of assessment of calibration

Lorant A. Muth

1999-01-01

59

Low profile array with reduced Radar Cross Section  

Microsoft Academic Search

The use of a band-stop Frequency Selective Surface for reducing the Radar Cross Section of an antenna array is described. For the first time such approach is employed for the case of an array of patch antennas with emphasis on the effects on the Radar Cross Section reduction and on the radiation performance of the new structure.

Simone Genovesi; Agostino Monorchio

2010-01-01

60

An estimation and verification of vessel radar cross sections for high-frequency surface-wave radar  

Microsoft Academic Search

The radar cross sections of both small and large ships for high-frequency surface-wave radar (HFSWR) were studied by using the numerical electromagnetics code, and by using measurements from an HFSWR system at Cape Race, Newfoundland, Canada. The results of the study indicated that Teleost, a 2405-ton Canadian Coast Guard ship, and large cargo container vessels (-36000 ton) have comparable RCS

H. Leong; H. Wilson

2006-01-01

61

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

62

Recognition of the major scattering sources on complex targets based on the high frequency radar cross section integrated calculation technique  

Microsoft Academic Search

Based on the high frequency (HF) integrated radar cross section (RCS) calculation approach, a technique of detecting major\\u000a scattering source is developed by using an appropriate arithmetic for scattering distribution and scattering source detection.\\u000a For the perfect adaptability to targets and the HF of the HF integrated RCS calculation platform, this technique is suitable\\u000a to solve large complex targets and

Min-jie Huang; Ming-yun Lü; Jun Huang; Zhe Wu

2009-01-01

63

Accuracy Check of the PO with the Modified Surface-Normal Vectors for Radar Cross Section Analyses  

Microsoft Academic Search

The diffraction error in the Physical Optics (PO) is well known. The Physical Theory of Diffraction (PTD) succeeded in correcting of the PO diffraction error. As another modification theory, we had already suggested modifying the definition of the surface-normal vectors in the PO currents. This novel method has quite and easy vector configuration in Radar Cross Section (RCS) analyses. This

Nobutaka Omaki; Luis Rodriguez; Tetsu Shijo; Makoto Ando

64

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

65

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

66

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

67

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

NASA Astrophysics Data System (ADS)

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

Huang, Xianjun; Hu, Zhirun; Liu, Peiguo

2014-11-01

68

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

NASA Technical Reports Server (NTRS)

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

1998-01-01

69

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

NASA Technical Reports Server (NTRS)

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

1997-01-01

70

An improved model for snowfall measurement using lidar and radar Lidar Backscatter Cross Section ~ number density * Radar Backscatter Cross Section ~ number density * Radar Doppler Velocity ~ f( mass, projected area, air density)  

E-print Network

An improved model for snowfall measurement using lidar and radar Lidar Backscatter Cross Section * radar Doppler velocity = precipitation rate Integrating precip rate yields total precipitation Eureka

Eloranta, Edwin W.

71

Peculiar radar cross section properties of metamaterials with zero index of refraction  

Microsoft Academic Search

In this paper, based on peculiar electromagnetic characteristics of metamaterials, peculiar radar cross section properties of metamaterials with zero index of refraction are discussed. These results provide some interested insights for potential applications in radar.

Wanzhao Cui; Jia Chen; Wei Ma; Lede Qiu

2008-01-01

72

Normalized radar cross section of the sea for backscatter: 2. Modulation by internal waves  

Microsoft Academic Search

We report measurements of microwave surface signatures of internal waves with dual-polarized, coherent, X band radars mounted on three ships and an airplane. In shipboard measurements in the South China Sea, internal waves generally increased the backscattering cross section near the peaks of the internal waves with little detectable decrease afterward. The peak of the cross-section signature shifted its location

William J. Plant; William C. Keller; Kenneth Hayes; Gene Chatham; Nicholas Lederer

2010-01-01

73

Verication of the Second-Order HF Bistatic Radar Cross Section of \\\\Patch Scatter\\  

Microsoft Academic Search

The verication of the second-order cross section on a surface patch remote from the transmitter and receiver is presented. In order to verify the result, two proofs are used: (1)the complete form of the bistatic HF radar cross section in backscattering case is equvielent with monstatic equation; (2)the bistatic coupling coecience can be shown to reduce to the monostatic result

Weimin Huang; Eric Gill; John Walsh

74

Radar cross-section reduction via route planning and intelligent control  

Microsoft Academic Search

Establishes a methodology for minimizing the peak and\\/or aggregate radar cross sections (RCSs) of autonomous precision guided munitions (APGMs) as they ingress to a selected target through a radar threat environment. This research demonstrates how route planning may be combined with the simultaneous specification of aerodynamically feasible yaw and bank angles to significantly reduce APGM observability. The approach described in

Frank W. Moore

2002-01-01

75

Surface reference normalized radar cross section over land for the improvement of the TRMM PR algorithm  

Microsoft Academic Search

The Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) standard algorithm 2A21 produces the surface normalized radar cross section (NRCS) values under no rain conditions as functions of the incidence angle and surface physical parameters which affect surface scattering. These NRCS values are used as the reference values to calculate the path integrated attenuation (PIA) values in the surface reference

Ken'ichi Okamoto; Jun Komukai; Shoichi Shige; Takeshi Manabe

2010-01-01

76

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

77

On reconciling ground-based with spaceborne normalized radar cross section measurements  

Microsoft Academic Search

This study examines differences in the normalized radar cross section, derived from ground-based versus spaceborne radar data. A simple homogeneous half-space model, indicates that agreement between the two improves as 1) the distance from the scatterer is increased; and\\/or 2) the extinction coefficient increases

François Baumgartner; Jens Munk; Kenneth C. Jezek; Sivaprasad Gogineni

2002-01-01

78

Normalized radar cross section of the sea for backscatter: 1. Mean levels  

Microsoft Academic Search

The normalized radar cross section of the sea for backscatter, ?o, is investigated for incidence angles between 0° and 89° using data collected over more than two decades. The most recent measurements were made from several ships using a coherent, dual-polarized, X band radar. These measurements show that vertically polarized transmit and receive signals, ?o(VV), at high incidence angles exhibit

William J. Plant; William C. Keller; Kenneth Hayes; Gene Chatham

2010-01-01

79

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

80

Deterministic Approach for Spatial Diversity Analysis of Radar Systems Using Near-Field Radar Cross Section of a Metallic Plate  

Microsoft Academic Search

A deterministic analysis of spatial diversity is presented in connection with radar systems. A numerical technique based on physical optics is used for our analysis. Contrary to statistical models, the proposed technique takes into account accurate near-field radar cross section of the target, and radiation characteristics of transmitting and receiving antennas. The power scattered by the target and received by

Ramin Deban; Halim Boutayeb; Ke Wu; Jean Conan

2010-01-01

81

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

82

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

83

Estimation of the sea surface radar cross section at HF from second order Doppler spectrum characteristics  

Microsoft Academic Search

A technique is developed for estimating the radar cross section of the sea surface at HF (2-30 MHz) from two simple measurements made of the radar Doppler spectrum. These are: the ratio of approach\\/recede Bragg line energy, and the ratio of strongest Bragg line amplitude to average value amplitude of second-order backscatter at zero Doppler frequency. A nomograph is given,

D. B. Trizna

1982-01-01

84

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

E-print Network

kind of electronic counter measures (ECM) to engage against a certain threat [Winchester, 1992]. [3Validation through comparison: Measurement and calculation of the bistatic radar cross section of a stealth target L. Gu¨rel and H. Bagc� Department of Electrical and Electronics Engineering, Bilkent

Gürel, Levent

85

Spectrum of rough sea surfaces covered in oil: consequences on the radar cross section  

Microsoft Academic Search

This paper describes the influence of oil pollution over sea surfaces on the height spectrum of the rough surfaces. An oil slick damps the capillarity waves of the surface height spectrum, and reduces the RMS slope of the surface. These modified functions have then an influence on the radar cross section from contaminated sea surfaces. The impact of the contaminated

Nicolas Pinel; Christophe Bourlier; N. Dechamps

2007-01-01

86

Spectrum of rough sea surfaces covered in oil: Consequences on the radar cross section  

Microsoft Academic Search

This paper describes the influence of oil pollution over sea surfaces on the height spectrum of the rough surfaces. An oil slick damps the capillarity waves of the surface height spectrum, and reduces the RMS slope of the surface. These modified functions have then an influence on the radar cross section from contaminated sea surfaces. The impact of the contaminated

Nicolas Pinel; Christophe Bourlier; N. Dechamps

2007-01-01

87

Scaled radar cross section measurements with terahertz-spectroscopy up to 800 GHz  

Microsoft Academic Search

Radar cross section measurements of complex, large objects (e.g. aircraft) are usually performed on miniaturized models, as this enables a well controllable measurement environment. The system frequency in the scaled scenario is proportional to the inverse size ratio of the model compared to the original object. If a high scaling factor is required to accommodate the measurement setup in a

C. Jansen; N. Krumbholz; R. Geise; A. Enders; M. Koch

2009-01-01

88

Frequency extrapolation by genetic algorithm based on GTD model for radar cross section  

Microsoft Academic Search

A frequency extrapolation scheme is developed to effectively predict radar cross sections using the genetic algorithm based on the GTD model. The parameterized model to extrapolate the frequency response to a higher frequency band is used and some test targets are calculated to test the effectiveness of the method. The influence of extrapolation on the range profile is studied, and

Z. L. Yang; D. G. Fang; W. X. Sheng; T. J. Liu; J. Zhuang

2000-01-01

89

A fast method for computation of the bistatic radar cross section  

Microsoft Academic Search

Computation of the Bistatic Radar Cross Section in two dimensions from the near field evaluated by means of the Finite Element Method, is readily improved by taking advantage of the decomposition of the scattered field into cylindrical waves. This decomposition also allows us to check the relative error for both the near and far fields. Examples of application are provided

Salvatore Alfonzetti; Giuseppe Borzì

2000-01-01

90

A closed form, physical optics expression for the radar cross section of a perfectly conducting flat plate over a dielectric half-space  

NASA Astrophysics Data System (ADS)

The physical optics approximation is employed in the derivation of a closed form expression for the radar cross section (RCS) of a flat, perfectly conducting plate of various shapes, located over a dielectric, possibly lossy half-space. The half-space is assumed to lie in the far field region of the plate. The well-known "four-path model" is invoked in a first-order approximation of the half-space contribution to the scattering mechanisms. Numerical results are compared to a reference, Moment Method solution, and the agreement is investigated, to assess the accuracy of the approximations used. The analytical expressions derived can facilitate very fast RCS calculations for realistic scatterers, such as ships in a sea environment, or aircraft flying low over the ground.

Anastassiu, Hristos T.

2003-04-01

91

The second-order monostatic HF radar cross section incorporating antenna barge motion  

Microsoft Academic Search

The second-order HF radar ocean cross section is derived for the case of the transmitting and receiving antenna undergoing platform (i.e. barge) motion. The derivation for electromagnetic patch scatter begins with a general expression for the bistatically received second-order electric field. Based on an assumption that the ocean surface can be described as a Fourier series with coefficients being zero-mean

John Walsh; Weimin Huang; Eric Gill

2009-01-01

92

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

93

Estimation of the sea surface radar cross section at HF from second order Doppler spectrum characteristics  

NASA Astrophysics Data System (ADS)

A technique is developed for estimating the radar cross section of the sea surface at HF (2-30 MHz) from two simple measurements made of the radar Doppler spectrum. These are: the ratio of approach/recede Bragg line energy, and the ratio of strongest Bragg line amplitude to average value amplitude of second-order backscatter at zero Doppler frequency. A nomograph is given, based on a theoretical model of second-order scatter developed by the author, which then allows one to determine the number of decibels the Bragg ocean spectral component is down from the classical Phillips asymptotic value, used here only for a reference. Comparison is made with some surface wave data for three different cases in which buoy data are available for comparison with multi-frequency radar data collected simultaneously at two different look angles. An example is also shown where such a calculation can be used to estimate the cross section of a target return existing within the same Doppler spectrum. Limitations of the technique are also discussed.

Trizna, D. B.

1982-05-01

94

Fabrication of Radar Absorbing Shells Made of Hybrid Composites and Evaluation of Radar Cross Section  

Microsoft Academic Search

** , Seoung-Bae Park ** and Myung-Shik Won *** ABSTRACT The avoidance of enemy's radar detection is very important issue in the modern electronic weapon system. Researchers have been studied to minimize reflected signals of radar. In this research, two types of radar absorbing structure (RAS), \\

Woo-Kyun Jung; Sung-Hoon Ahn; Bierng-Chearl Ahn

2005-01-01

95

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

96

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

Microsoft Academic Search

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

John Walsh; Eric Gill; Weimin Huang

2008-01-01

97

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

98

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

99

Dramatic decrease in radar cross section over Greenland observed by the ERS-1 scatterometer between 1991 and 1995  

Microsoft Academic Search

Radar backscatter measurements obtained over Greenland by the ERS-1 scatterometer between August 1991 and November 1995 are investigated. The different snow and ice facies can be identified on NRCS maps by their different radar cross section. In the wet snow zones summer melting leads to a strong short-term decrease in NRCS of several dB in the months June to August

Volkmar R. Wismann; Kai Boehnke

1996-01-01

100

Measurements of the effect of rain-induced sea surface roughness on the satellite scatterometer radar cross section  

Microsoft Academic Search

Radar measurements of the sea surface, with satellite scatterometers that operate at Ku-band, will be 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 reflectivity and attenuation that affect the measured normalized radar cross section (NRCS). Numerous surface-based studies, using ocean platforms and wind-wave

David E. Weissman; Mark A. Bourassa

2007-01-01

101

An algorithm for retrieval of oceanic wind vectors from the simulated Sass normalized radar cross-section measurements  

Microsoft Academic Search

A new algorithm has been proposed to recover wind vectors from the simulated Seasat A satellite scattero meter (SASS) normalized radar cross-section (NRCS) measurements exploiting the fact that all the dual polarized noise-free NRCS measurements taken in any azimuth direction should provide the same wind speed in the true direction of wind. The algorithm deals with the computation of wind

B. S. Gohil; P. C. Pandey

1985-01-01

102

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

103

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

104

Exact RCS reconstruction of interested targets from SAR images  

NASA Astrophysics Data System (ADS)

A procedure is proposed to reconstruct the radar cross section (RCS) of interested targets from synthetic aperture radar (SAR) images. Key factors in imaging are considered for exact RCS reconstruction, including image defocusing from target motion, system over-sampling, window function, zero-padding and image calibration. Experimental results for both numerically calculated inverse SAR (ISAR) and spaceborne SAR image demonstrate the effectiveness and accuracy of the proposed technique.

Gu, Dandan; Xu, Xiaojian

2012-09-01

105

RCS reduction for a microstrip antenna using a normally biased ferrite substrate  

Microsoft Academic Search

It is shown that the radar cross section (RCS) of a microstrip antenna can be significantly reduced over a broad frequency range by using a ferrite substrate biased to a cutoff state. When unbiased, the antenna operates in its usual fashion, with relatively large RCS peaks at frequencies corresponding to the resonances of the patch element. When the ferrite substrate

D. M. Pozar

1992-01-01

106

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

107

Modulation of waveheight spectrum and radar cross section by varying surface currents  

Microsoft Academic Search

This paper investigates the validity of the relaxation model which is generally used to describe the modulation of wind-generated ocean waves by slowly varying surface currents, and the applicability of the model to illustrating features observed in the radar images of internal wave wakes. The amplitude and phase modulations in the waveheight spectrum are examined for sinusoidal current variations; these

Kazuo Ouchi

1994-01-01

108

A Novel Fractal Patch Antenna with Low RCS  

Microsoft Academic Search

The special space filling capability of Koch fractal is used in the Radar Cross Section (RCS) reduction of microstrip patch antenna. Compared with normal rectangular microstrip patch antenna, the resonance sides are designed in the shape of Koch fractal, while two Koch fractal shape slots are cut in the antenna. Based on the design, antenna prototypes were fabricated and tested,

G. Cui; Y. Liu; S. Gong

2007-01-01

109

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

110

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

111

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

112

Progress in smart radar absorbers  

Microsoft Academic Search

Conventional (i.e. passive) radar absorbers are widely used for modifying the radar cross-section (RCS) of current military platforms but such absorbers may not have adequate performance to satisfy future requirements. Active absorbers, however, offer the potential to overcome the so-called Rozanov performance limit and to enable additional 'smart' functionality such as monitoring damage, adaptive control of RCS or target appearance,

Barry Chambers; Alan Tennant

2003-01-01

113

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

114

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

E-print Network

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

Paris-Sud XI, Université de

115

RCS Reduction of Array Antenna by Using Bandstop FSS Reflector  

Microsoft Academic Search

This paper investigates the application of a novel frequency selective surface (FSS) reflector for 4×2 dipole array antenna to reduce radar cross section (RCS) out of operating band. The proposed FSS adopting a regular hexagon quasi-fractal structure has good bandstop characteristic. By replacing the metal reflector with this bandstop FSS sheet, the in-band radiation performance of the proposed array antenna

W.-T. Wang; S.-X. Gong; X. Wang; H.-W. Yuan; J. Ling; T.-T. Wan

2009-01-01

116

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

NASA Astrophysics Data System (ADS)

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

Yang, Ruike; Wu, Zhensen; Chen, Yinliang

2002-02-01

117

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

118

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

119

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

120

NEUTRON CROSS SECTIONS  

Microsoft Academic Search

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

Donald J. Hughes; R. B. Schwartz

1958-01-01

121

A smart radar absorber based on the phase-switched screen  

Microsoft Academic Search

Although conventional (i.e., passive) radar absorbers are widely used for modifying the radar cross-section (RCS) of current military platforms, such absorbers may not have adequate performance to satisfy future requirements. Active absorbers, however, offer the potential to overcome the so-called Rozanov performance limit and to enable additional smart functionality such as monitoring damage, adaptive control of RCS or target appearance,

Barry Chambers; Alan Tennant

2005-01-01

122

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

Microsoft Academic Search

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

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

2009-01-01

123

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

124

Scattering cross section of sound waves by the modal element method  

NASA Technical Reports Server (NTRS)

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

Baumeister, Kenneth J.; Kreider, Kevin L.

1994-01-01

125

Jet inclusive cross sections  

SciTech Connect

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

Del Duca, V.

1992-11-01

126

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

127

Threshold cross section measurements  

E-print Network

Accurate measurements of particles masses, couplings and widths are possible by measuring production cross sections near threshold. We discuss the prospects for performing such measurements at a high luminosity muon collider.

M. S. Berger

1998-02-02

128

Solar fusion cross sections  

Microsoft Academic Search

We review and analyze the available information on the nuclear-fusion cross sections that are most important for solar energy generation and solar neutrino production. We provide best values for the low-energy cross-section factors and, wherever possible, estimates of the uncertainties. We also describe the most important experiments and calculations that are required in order to improve our knowledge of solar

Eric G. Adelberger; Sam M. Austin; John N. Bahcall; A. B. Balantekin; Gilles Bogaert; Lowell S. Brown; Lothar Buchmann; F. Edward Cecil; Arthur E. Champagne; Ludwig de Braeckeleer; Charles A. Duba; Steven R. Elliott; Stuart J. Freedman; Moshe Gai; G. Goldring; Christopher R. Gould; Andrei Gruzinov; Wick C. Haxton; Karsten M. Heeger; Ernest Henley; Calvin W. Johnson; Marc Kamionkowski; Ralph W. Kavanagh; Steven E. Koonin; Kuniharu Kubodera; Karlheinz Langanke; Tohru Motobayashi; Vijay Pandharipande; Peter Parker; R. G. Robertson; Claus Rolfs; R. F. Sawyer; N. Shaviv; T. D. Shoppa; K. A. Snover; Erik Swanson; Robert E. Tribble; Sylvaine Turck-Chièze; John F. Wilkerson

1998-01-01

129

Geologic Cross Sections  

NSDL National Science Digital Library

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

Browning, Sharon

130

Solar Fusion Cross Sections  

E-print Network

We review and analyze the available information for nuclear fusion cross sections that are most important for solar energy generation and solar neutrino production. We provide best values for the low-energy cross-section factors and, wherever possible, estimates of the uncertainties. We also describe the most important experiments and calculations that are required in order to improve our knowledge of solar fusion rates.

E. Adelberger; S. Austin; J. Bahcall; A. Balantekin; G. Bogaert; L. Brown; L. Buchmann; F. Cecil; A. Champagne; L. de Braeckeleer; C. Duba; S. Elliott; S. Freedman; M. Gai; G. Goldring; C. Gould; A. Gruzinov; W. Haxton; K. Heeger; E. Henley; C. Johnson; M. Kamionkowski; R. Kavanagh; S. Koonin; K. Kubodera; K. Langanke; T. Motobayashi; V. Pandharipande; P. Parker; R. Robertson; C. Rolfs; R. Sawyer; N. Shaviv; T. Shoppa; K. Snover; E. Swanson; R. Tribble; S. Turck-Chieze; J. Wilkerson

1998-05-12

131

Validation of a ?2 model of HRR target RCS variability and verification of the resulting ATR performance model  

NASA Astrophysics Data System (ADS)

A (chi) 2 model for radar cross section (RCS) variability of High Range Resolution (HRR) measurements is validated using compact range data from the U.S. Army National Ground Intelligence Center (NGIC). It is shown that targets can be represented by a mean template and by a variance template, or in this case, an effective number of degrees-of-freedom for the (chi) 2-distribution. The analysis also includes comparison of the measured tails of the RCS distribution to that predicated by the (chi) 2-distribution. The likelihood classifier is obtained, and a Monte Carlo performance model is developed to validate the statistical model at the level of ATR performance.

Holt, Craig R.; Attili, Joseph B.; Schmidt, Steven L.

2001-10-01

132

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

133

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

134

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

135

Progress in smart radar absorbers  

NASA Astrophysics Data System (ADS)

Conventional (i.e. passive) radar absorbers are widely used for modifying the radar cross-section (RCS) of current military platforms but such absorbers may not have adequate performance to satisfy future requirements. Active absorbers, however, offer the potential to overcome the so-called Rozanov performance limit and to enable additional 'smart' functionality such as monitoring damage, adaptive control of RCS or target appearance, Identification-Friend-or-Foe (IFF) and Absorb-While-Scan (AWS) This paper outlines the concept and basic properties of a novel type of active radar absorber, the so-called Phase-Switched Screen (PSS). The basic PSS topology is then modified so as to enable it to operate as a smart radar absorber when used together with an external sensor and feedback control loop. The theoretical predictions are confirmed using data measured on transmission-line analogues of the smart PSS structure.

Chambers, Barry; Tennant, Alan

2003-07-01

136

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

137

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

138

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

139

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

140

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

141

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

142

ATR discrimination-SNR for HRR assuming ?2 model of RCS variability  

NASA Astrophysics Data System (ADS)

A discrimination SNR for predicting classification performance is developed as an analogy to the RADAR equation that is used to predict detection performance. It assumes a statistical model for the target radar cross-section (RCS) and that the resulting likelihood classifier is employed. The relationship between the probability of classification errors and the dB value of the discrimination SNR is obtained. A specific form for the likelihood classifier and the discrimination SNR is developed assuming that the variability of the target RCS is described by a (chi) 2 - distribution. The form of this (chi) 2 - based classifier is novel and significantly different from the more common Gaussian based mean-square-error classifier. It is shown that the discrimination SNR has an intuitive interpretation in terms of the number of radar samples, the average contrast between targets and the contrast-noise. The use of this tool is illustrated using compact range High Range Resolution (HRR) Doppler measurements from the U.S. Army National Ground Intelligence Center (NGIC). The sensitivity of ATR performance to radar parameters is quantified using the discrimination SNR with gains measured in meaningful dB units.

Holt, Craig R.; Schmidt, Steven L.; Attili, Joseph B.

2001-10-01

143

Issues surrounding surfactant effects upon radar imagery of convergent ocean surface flows with application to the Hi-Res I rip feature  

Microsoft Academic Search

X-band radar signatures of a current rip convergence, resulting from denser Gulf Stream fluid interacting with fresh coastal shelf water near Cape Hatteras, were observed during the First High Resolution (Hi-Res I) experiment. These signatures, which appeared as intense (~10 dB) enhancements in radar cross section (RCS) in the form of meandering linear segments, were accompanied by secondary parallel meandering

A. L. Cooper; S. R. Chubb; J. A. C. Kaiser

1996-01-01

144

Automatic real-time collection of RCS of airplanes in a real bistatic low-frequency configuration using a software defined passive radar based on illuminators of opportunity  

Microsoft Academic Search

In this paper, a novel method of measurement of the real RCS of various airplanes in real conditions, in bistatic mode, and at low frequency is derived. The presence of an airplane is detected by the use of an ADS-B receiver. The RCS of an airplane is derived thanks to the ratio of the power of the received echo signal

Jonathan Pisane; Sylvain Azarian; Marc Lesturgie; Jacques Verly

2012-01-01

145

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

146

The Radar Image Generation (RIG) model  

NASA Technical Reports Server (NTRS)

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

Stenger, Anthony J.

1993-01-01

147

Revolutionizing Cross-sectional Imaging  

E-print Network

Cross-sectional imaging is so important that, six Nobel Prizes have been awarded to the field of nuclear magnetic resonance alone because it revolutionized clinical diagnosis. The BigBrain project supported by up to 1 billion euro each over a time period of 10 years predicts to "revolutionize our ability to understand internal brain organization" (Evan 2013). If we claim that cross-sectional imaging diagnosis is only semi-quantitative, some may believe because no doctor would ever tell their patient that we can observe the changes of this cross-sectional image next time. If we claim that BigBrain will make no difference in clinical medicine, then few would believe because no doctor would ever tell their patient to scan this part of the image and compare it with that from the BigBrain. If we claim that the BigBrain Project and the Human Brain Project have defects in their key method, one might believe it. But this is true. The key lies in the reconstruction of any cross-sectional image along any axis. Using Ga...

Fan, Yifang; Luo, Liangping; Lin, Wentao; Li, Zhiyu; Zhong, Xin; Shi, Changzheng; Newman, Tony; Zhou, Yi; Lv, Changsheng; Fan, Yuzhou

2014-01-01

148

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

149

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

NASA Astrophysics Data System (ADS)

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 is based on tracking a large number of rays launched into the cavity through the opening and determining the geometrical optics field associated with each ray by taking into consideration (1) the geometrical divergence factor, (2) polarization, and (3) material loading of the cavity walls. A physical optics scheme is then applied to compute the backscattered field from the exit rays. This method is so simple in concept that there is virtually no restriction on the shape or material loading of the cavity. Numerical results obtained by this method are compared with those for the modal analysis for a circular cylinder terminated by a PEC plate. RCS results for an S-bend circular cylinder generated on the Cray X-MP supercomputer show significant RCS reduction. Some of the limitations and possible extensions of this technique are discussed.

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

1989-02-01

150

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

NASA Technical Reports Server (NTRS)

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 is based on tracking a large number of rays launched into the cavity through the opening and determining the geometrical optics field associated with each ray by taking into consideration (1) the geometrical divergence factor, (2) polarization, and (3) material loading of the cavity walls. A physical optics scheme is then applied to compute the backscattered field from the exit rays. This method is so simple in concept that there is virtually no restriction on the shape or material loading of the cavity. Numerical results obtained by this method are compared with those for the modal analysis for a circular cylinder terminated by a PEC plate. RCS results for an S-bend circular cylinder generated on the Cray X-MP supercomputer show significant RCS reduction. Some of the limitations and possible extensions of this technique are discussed.

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

1989-01-01

151

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

152

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

153

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

154

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

155

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

156

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

157

Detecting and Mitigating Wind Turbine Clutter for Airspace Radar Systems  

PubMed Central

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

2013-01-01

158

Charged-particle elastic cross sections  

SciTech Connect

Modern treatments of energy loss in plasmas through elastic scattering of energetic ions require complete knowledge of charged-particle elastic cross sections. R-matrix theory provides an explicit separation of nuclear and Coulomb effects in these cross sections, and gives reasonable extrapolations to small angles and low energies, where data may be scarce. We outline the calculation of charged-particle elastic cross sections from R-matrix parameters, and given examples for d-T, d-..cap alpha.., and t-..cap alpha.. scattering, obtained from comprehensive analyses of reactions in the /sup 5/He, /sup 6/Li, and /sup 7/Li compound systems. Expansion coefficients for an exact polynomial representation for the difference of the scattering and Rutherford cross sections (sigma/sub NI/) are given for d-T scattering. Integral quantities involving sigma/sub NI/ calculated from the present cross sections disagree substantially in some cases near resonances with a recent Livermore evaluation.

Hale, G.M.; Dodder, D.C.; DeVeaus, J.C.

1982-01-01

159

Photodetachment cross section for Ca sup minus  

SciTech Connect

Multiconfiguration Hartree-Fock calculations for photodetachment cross sections in Ca{sup {minus}} are reported, both to the {ital ks} {sup 2}{ital S} and {ital kd} {sup 2}{ital D} final state. Correlation is important to the binding of the 4{ital s}{sup 2}4{ital p} {sup 2}{ital P} state and also to the cross section. In the final state, correlation is particularly important for the {ital kd} partial cross section. The value of the electron affinity in Ca{sup {minus}} is critical to agreement in the length and velocity form of the cross section. Better agreement is obtained when a theoretical value is used. Agreement with an experimental photodetachment cross section is good.

Froese Fischer, C. (Department of Computer Science, Vanderbilt University, Box 6035B, Nashville, TN (USA)); Hansen, J.E. (Zeeman Laboratory, Plantage Muidergracht 4, NL-1018 TV Amsterdam, The Netherlands (NL))

1991-08-01

160

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

E-print Network

45. Neutrino Cross Section Measurements 1 45. Neutrino Cross Section Measurements Written in April 2012 by G.P. Zeller (Fermilab) Neutrino interaction cross sections are an essential ingredient in most neutrino experiments. Interest in neutrino scattering has recently increased due to the need

161

Controlling radar signature  

SciTech Connect

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, K.W. (U.S. Navy, Naval Air Warfare Center, China Lake, CA (United States))

1992-08-01

162

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

163

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

164

Developing Cross Section Sets for Fluorocarbon Etchants  

NASA Astrophysics Data System (ADS)

Successful modeling of plasmas used in materials processing depends on knowledge of a variety of collision cross sections and reaction rates, both within the plasma and at the surface. Electron-molecule collision cross sections are especially important, affecting both electron transport and the generation of reactive fragments by dissociation and ionization. Because the supply of cross section data is small and measurements are difficult, computational approaches may make a valuable contribution, provided they can cope with the significant challenges posed. In particular, a computational method must deal with the full complexity of low-energy electron-molecule interactions, must treat polyatomic molecules, and must be capable of computing cross sections for electronic excitation. These requirements imply that the method will be numerically intensive and thus must exploit high-performance computers to be practical. We have developed an ab initio computational method, the Schwinger multichannel (SMC) method, that possesses the characteristics just described, and we have applied it to compute cross sections for a variety of molecules, with particular emphasis on fluorocarbon and hydrofluorocarbon etchants used in the semiconductor industry. A key aspect of this work has been an awareness that cross section sets, validated when possible against swarm data, are more useful than individual cross sections. To develop such sets, cross section calculations must be integrated within a focused collaborative effort. Here we describe electron cross section calculations carried out within the context of such a focused effort, with emphasis on fluorinated hydrocarbons including CHF3 (trifluoromethane), c-C4F8 (octafluorocyclobutane), and C2F4 (tetrafluoroethene).

Winstead, Carl; McKoy, Vincent

2002-10-01

165

Neutron Capture Cross Section of 239Pu  

NASA Astrophysics Data System (ADS)

The Detector for Advanced Neutron Capture Experiments (DANCE) has been used to measure the 239Pu(n,?) cross section from 10 eV to the keV region. Three experimental run conditions were used to characterize the prompt fission ?-ray spectrum across the entire energy regime, measure the cross section in the resolved resonance region, and obtain necessary count rate well into the keV region. The preliminary cross sections are in good agreement with current evaluations from 10 eV to 80 keV.

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

2014-05-01

166

A nuclear cross section data handbook  

SciTech Connect

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

Fisher, H.O.M.

1989-12-01

167

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

168

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

169

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

170

The rolling cross-section design  

Microsoft Academic Search

This article describes the 'rolling cross-section', a design well-adapted to telephone surveys and to capturing real-time effects in campaigns. In one sense, the design is just a standard cross-section, but the day on which a respondent is interviewed is chosen randomly. As a result, analysis of longitudinal factors is possible with only modest controls. The design necessitates an estimation strategy

Richard Johnston; Henry E. Brady

2001-01-01

171

The rolling cross-section design  

Microsoft Academic Search

This article describes the ‘rolling cross-section’, a design well-adapted to telephone surveys and to capturing real-time effects in campaigns. In one sense, the design is just a standard cross-section, but the day on which a respondent is interviewed is chosen randomly. As a result, analysis of longitudinal factors is possible with only modest controls. The design necessitates an estimation strategy

Richard Johnston; Henry E. Brady

2002-01-01

172

Asymptotic cross sections for composite projectile reactions  

E-print Network

ASYMPTOTIC CROSS SECTIONS FOR COMPOSITE PROJECTILE REACTIONS A Thesis by ANDREA MAROLT PIMENTA NEVES Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER... OF SCIENCE August 1995 Major Subject: Physics ASYMPTOTIC CROSS SECTIONS FOR COMPOSITE PROJECTILE REACTIONS A Thesis by ANDREA MAROLT P JMENTA NEVES Submitted to Texas ARM University in partial fulfillment of the requirements for the degree...

Neves, Andrea Marolt Pimenta

2012-06-07

173

The hadronic cross section measurement at KLOE  

NASA Astrophysics Data System (ADS)

KLOE uses the radiative return to measure cross section ?(ee????) at the electron-positron collider DA?NE. Divinding by a theoretical radiator function, we obtain the cross section ?(ee????) for the mass range 0.35

Aloisio, A.; Ambrosino, F.; Antonelli, A.; Antonelli, M.; Bacci, C.; Barva, M.; Bencivenni, G.; Bertolucci, S.; Bini, C.; Bloise, C.; Bocci, V.; Bossi, F.; Branchini, P.; Bulychjov, S. A.; Caloi, R.; Campana, P.; Capon, G.; Capussela, T.; Carboni, G.; Ceradini, F.; Cervelli, F.; Cevenini, F.; Chiefari, G.; Ciambrone, P.; Conetti, S.; De Lucia, E.; De Santis, A.; De Simone, P.; De Zorzi, G.; Dell'Agnello, S.; Denig, A.; Di Domenico, A.; Di Donato, C.; Di Falco, S.; Di Micco, B.; Doria, A.; Dreucci, M.; Erriquez, O.; Farilla, A.; Felici, G.; Ferrari, A.; Ferrer, M. L.; Finocchiaro, G.; Forti, C.; Franzini, P.; Gatti, C.; Gauzzi, P.; Giovannella, S.; Gorini, E.; Graziani, E.; Incagli, M.; Kluge, W.; Kulikov, V.; Lacava, F.; Lanfranchi, G.; Lee-Franzini, J.; Leone, D.; Lu, F.; Martemianov, M.; Martini, M.; Matsyuk, M.; Mei, W.; Merola, L.; Messi, R.; Miscetti, S.; Moulson, M.; Müller, S.; Murtas, F.; Napolitano, M.; Nguyen, F.; Palutan, M.; Pasqualucci, E.; Passalacqua, L.; Passeri, A.; Patera, V.; Perfetto, F.; Petrolo, E.; Pontecorvo, L.; Primavera, M.; Santangelo, P.; Santovetti, E.; Saracino, G.; Schamberger, R. D.; Sciascia, B.; Sciubba, A.; Scuri, F.; Sfiligoi, I.; Sibidanov, A.; Spadaro, T.; Spiriti, E.; Tabidze, M.; Testa, M.; Tortora, L.; Valente, P.; Valeriani, B.; Venanzoni, G.; Veneziano, S.; Ventura, A.; Versaci, R.; Villella, I.; Xu, G.; KLOE Collaboration

174

Target identification by means of impulse radar  

NASA Astrophysics Data System (ADS)

The scattering interaction of short electromagnetic pulses with a spherical target is studied. The target is assumed penetrable and is modeled as an air-filled dielectric shell. The radar cross-section (RCS) of such a target is obtained and its resonance features are analyzed. A dielectric composition makes the resonance features become very prominent compared with the case of an ideally conducting sphere. When the interrogating waveform is a pulse of short duration, the resonance features of the backscattering cross-section can be extracted within the frequency band of the incident pulse. To verify theoretical predictions, spherical targets were illuminated with short broad-band pulses using an impulse radar system. The actual shape of the pulse that is incident on the target is theoretically modeled using a digital filter design techniques, and the predicted backscattered returns of spherical targets are compared with selected echoes of the pulses transmitted by the impulse radar. The authors verify that the shape of the predicted backscattered pulse that results from the design method agrees well with the experimental findings using metal spheres of three different sizes. By means of an incident pulse of designed shape, the form-function in the backscattering radar cross-section of a dielectric target is predicted using a discrete Fourier transform (DFT) technique. It is shown that many of the resonance features of a dielectric spherical shell can be extracted from the frequency band of the incident pulse employing this method. The methodology that is developed can handle broadband pulses of any sufficiently smooth spectrum, interacting with (lossy or lossless) dielectric scatterers, and can extract the resonance features within the frequency band of the transmitted pulse. Accordingly, this methodology could also be used for assessing the performance of high-power impulse radar systems.

Abrahamson, Steffan; Brusmark, B.; Gaunaurd, Guillermo C.; Strifors, Hans C.

1991-08-01

175

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

E-print Network

of Okhotsk Lake Lake Great Bear Great Slave Sea Baltic Black Sea Sea Bering Strait Chukchi average minimum Great Bear Great Slave Sea Baltic Black Sea Sea Bering Strait Chukchi average minimum extent of sea ice

Eloranta, Edwin W.

176

Modeling the heavy ion upset cross section  

NASA Astrophysics Data System (ADS)

The standard Rectangular Parallelepiped (RPP) construct is used to derive a closed form expression for, sigma-bar (theta, phi, L) the directional-spectral heavy ion upset cross section. This is an expected value model obtained by integrating the point-value cross section model, sigma (theta, phi, L, E), also developed here, with the Weibull density function, f(E), assumed to govern the stochastic behavior of the upset threshold energy, E. A comparison of sigma-bar (theta, phi, L) with experimental data show good agreement, lending strong credibility to the hypothesis that E-randomness is responsible for the shape of the upset cross section curve. The expected value model is used as the basis for a new, rigorous mathematical formulation of the effective cross section concept. The generalized formulation unifies previous corrections to the inverse cosine scaling, collapsing to Petersen's correction, (cos theta - (h/l) sin theta)(sup -1), near threshold and Sexton's, (cos theta + (h/l) sin theta)(sup -1), near saturation. The expected value cross section model therefore has useful applications in both upset rate prediction and test data analysis.

Connell, L. W.; McDaniel, P. J.; Prinja, A. K.; Sexton, F. W.

1995-04-01

177

Precise neutron inelastic cross section measurements  

SciTech Connect

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

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

2012-11-20

178

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

179

Optical Model and Cross Section Uncertainties  

SciTech Connect

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

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

2009-10-05

180

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

181

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

182

Hadronic cross section from radiative return  

E-print Network

The impact of final-state radiation (FSR) on the radiative return method for the extraction of the e+e- hadronic cross section is discussed in detail and experimental tests of the model dependence of FSR are proposed for the pi+pi- hadronic final state.

Henryk Czyz; Agnieszka Grzelinska

2004-02-03

183

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

184

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

185

ELECTRON IMPACT CROSS SECTIONS FOR CO  

Microsoft Academic Search

Using the concept of the generalized oscillator strength and the techniques previously de- veloped, we synthisize a diverse body of experimental data on carbon dioxide into a set of analytical electron impact cross sections. The generalized oscillator strengths of Lassettre and $hiloff (1965) serve as the primary data. We include in our analysis discrete excitation, autoionization, direct ionization, and dissociative

D. J. Strickland; A. E. S. Green

1969-01-01

186

Metonymy and cross-section demand  

Microsoft Academic Search

Cross-section consumer expenditure data are frequently used to draw conclusions about consumer demand behavior. Such conclusions, however, are justified only under certain assumptions, which are often left unstated in the empirical demand literature. An assumption of this type, the metonymy hypothesis, was stated rigorously and exploited by Härdle et al. when analyzing the monotonicity of aggregate demand functions. The purpose

Igor V. Evstigneev; Werner Hildenbrand; Michael Jerison

1997-01-01

187

Neutron scattering lengths and cross sections  

Microsoft Academic Search

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

Varley F. Sears

1992-01-01

188

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

189

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

190

ORCON1. Stream Condenser Circular Cross Section  

Microsoft Academic Search

ORCON1 is a program for design or metric study of steam condensers whose tubes form a horizontal bundle of circular or semicircular cross section with central void. Baffles and a cooler section may be provided as options. The output shows steam conditions at each row.

Hafford

1973-01-01

191

Simplified model of dismount microDoppler and RCS  

Microsoft Academic Search

Our goal is to be able to detect and classify dismounts, but we were lacking a quick way to estimate dismount parameters, especially with respect to angle of motion and depression angle of the radar. Micro-Doppler models have been developed which attempt to predict the human micro-Doppler response, and here we present a simplified model to quickly estimate dismount RCS

Dave Tahmoush; Jerry Silvious

2010-01-01

192

Converting a 3D surface into a set of directional scatterers for high-resolution radar response simulation  

NASA Astrophysics Data System (ADS)

It is practical and efficient to simplify targets to point scatterers in radar simulations. With low-resolution radars, the radar cross section (RCS) is a sufficient feature to characterize the scattering properties of a target. However, the RCS totals the target scattering properties to a scalar value for each aspect angle. Thus, a more detailed representation of the target is required with high-resolution radar techniques, such as Inverse Synthetic-Aperture Radar (ISAR). In straightforward simulation scenarios, high-resolution targets have been modeled placing identical point scatterers in the shape of the target, or with a few dominant point scatterers. As extremely simple arrangements, these do not take the self-shadowing into account and are not realistic enough for high demands. Our radar response simulation studies required a target characterization akin to RCS, which would also function in highresolution cases and take the self-shadowing and multiple reflections into account. Thus, we propose an approach to converting a 3-dimensional (3D) surface into a set of scatterers with locations, orientations, and directional scattering properties. The method is intended for far field operation, but could be adjusted for use in the near field. It is based on ray tracing which provides the self-shadowing and reflections naturally. In this paper, we present ISAR simulation results employing the proposed method. The constructed scatterer set is scalable for different wavelengths enabling the fast production of realistic simulations including authentic RCS scattering center formation. This paper contributes to enhancing the reality of the simulations, yet keeping them manageable and computationally reasonable.

Perälä, Henna; Väilä, Minna; Jylhä, Juha; Venäläinen, Ilkka; Visa, Ari

2011-09-01

193

Electron-collision cross sections for iodine  

SciTech Connect

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

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

2011-04-15

194

Cross sections required for FMIT dosimetry  

SciTech Connect

The Fusion Materials Irradiation Test (FMIT) facility, currently under construction, is designed to produce a high flux of high energy neutrons for irradiation effects experiments on fusion reactor materials. Characterization of the flux-fluence-spectrum in this rapidly varying neutron field requires adaptation and extension of currently available dosimetry techniques. This characterization will be carried out by a combination of active, passive, and calculational dosimetry. The goal is to provide the experimenter with accurate neutron flux-fluence-spectra at all positions in the test cell. Plans have been completed for a number of experimental dosimetry stations and provision for these facilities has been incorporated into the FMIT design. Overall needs of the FMIT irradiation damage program delineate goal accuracies for dosimetry that, in turn, create new requirements for high energy neutron cross section data. Recommendations based on these needs have been derived for required cross section data and accuracies.

Gold, R.; McElroy, W.N.; Lippincott, E.P.; Mann, F.M.; Oberg, D.L.; Roberts, J.H.; Ruddy, F.H.

1980-05-02

195

Photonuclear Reaction Cross Sections for Gallium Isotopes  

E-print Network

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

Serkan Akkoyun; Tuncay Bayram

2014-09-08

196

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

197

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

198

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

199

Resonance capture cross section of Pb207  

Microsoft Academic Search

The radiative neutron capture cross section of Pb207 has been measured at the CERN neutron time of flight installation n_TOF using the pulse height weighting technique in the resolved energy region. The measurement has been performed with an optimized setup of two C6D6 scintillation detectors, which allowed us to reduce scattered neutron backgrounds down to a negligible level. Resonance parameters

C. Domingo-Pardo; U. Abbondanno; G. Aerts; H. Álvarez-Pol; F. Alvarez-Velarde; S. Andriamonje; J. Andrzejewski; P A Assimakopoulos; L. Audouin; G. Badurek; P. Baumann; F. Becvár; E. Berthoumieux; S. Bisterzo; F. Calviño; D. Cano-Ott; R. Capote; C. Carrapiço; P. Cennini; V. Chepel; Enrico Chiaveri; N. Colonna; G. Cortes; A. Couture; J. Cox; M. Dahlfors; S. David; I. Dillman; R. Dolfini; W. Dridi; I. Duran; C. Eleftheriadis; M. Embid-Segura; L. Ferrant; A. Ferrari; R. Ferreira-Marques; L. Fitzpatrick; H. Frais-Koelbl; K. Fujii; W. Furman; R. Gallino; I. Goncalves; E M González-Romero; A. Goverdovski; F. Gramegna; E. Griesmayer; C. Guerrero; F. Gunsing; B. Haas; R. Haight; M. Heil; A. Herrera-Martinez; M. Igashira; S. Isaev; E. Jericha; Y. Kadi; F K Käppeler; D. Karamanis; D. Karadimos; M. Kerveno; V. Ketlerov; P. Koehler; V. Konovalov; E. Kossionides; M. Krticka; C. Lamboudis; H. Leeb; A. Lindote; I. Lopes; M. Lozano; S. Lukic; J. Marganiec; S. Marrone; P. Mastinu; A. Mengoni; P. M. Milazzo; C. Moreau; M. Mosconi; F. Neves; Heinz Oberhummer; M. Oshima; S. O'Brien; J. Pancin; C. Papachristodoulou; C. Papadopoulos; C. Paradela; N. Patronis; A. Pavlik; P. Pavlopoulos; L. Perrot; R. Plag; A. Plompen; A. Plukis; A. Poch; C. Pretel; J. Quesada; T. Rauscher; R. Reifarth; M. Rosetti; Carlo Rubbia; G. Rudolf; P. Rullhusen; J. Salgado; L. Sarchiapone; I. Savvidis; C. Stephan; G. Tagliente; J. L. Tain; L. Tassan-Got; L. Tavora; R. Terlizzi; G. Vannini; P. Vaz; A. Ventura; D. Villamarin; M C Vincente; V. Vlachoudis; R. Vlastou; F. Voss; S. Walter; H. Wendler; M. Wiescher; K. Wisshak

2006-01-01

200

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

201

Neutron cross section standards and instrumentation  

NASA Astrophysics Data System (ADS)

This report from the National Institute of Standards and Technology contains a summary of the accomplishments of the Neutron Cross Section Standards and Instrumentation Project during the second year of a three-year interagency agreement. This program includes a broad range of data measurements and evaluations. An emphasis has been focused on the (sup 10)B cross sections where serious discrepancies in the nuclear data base remain. In particular, there are important problems with the interpretation of the helium gas production associated with diagnostic measurements of interest in nuclear technology. The enhanced use of this isotope for medical treatment is also of significance. New measurements of neutron reaction cross sections for (sup 10)B are in progress in collaboration with scientists at the Oak Ridge National Laboratory. New experiments are in progress on the important dosimetry standards (sup 237)Np(n,f) and (sup 239)Pu(n,f) below 1 MeV neutron energy. In addition, new measurements of charged-particle production in basic biological elements for medical applications are underway. Further measurements are planned or in progress in collaborations which include fission fragment energy and angular distributions, and neutron energy spectra and angular distributions from neutron-induced fission. Also measurements of angular distributions of neutrons from scattering on protons, and determinations of capture cross section of gold are planned for a later time. Data evaluation will shift to include a unified international effort to motivate new measurements and evaluations. In response to the requests of the measurement community, NIST is beginning the formation of a national depository for fissionable isotope mass standards. This action will preserve for future measurements the valuable and irreplaceable critical samples whose masses and composition have been carefully determined and documented over the past 30 years of the nuclear program.

1992-09-01

202

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

203

Cross-section measurements for radioactive samples  

Microsoft Academic Search

The measurement of (n,p), (n,..cap alpha..) and (n,..gamma..) cross sections for radioactive nuclei is of interest to both nuclear physics and astrophysics. For example, using these reactions, properties of levels in nuclei at high excitation energies, which are difficult or impossible to study using other reactions, can be investigated. Also, reaction rates for both big-bang and stellar nucleosynthesis can be

P. E. Koehler; H. A. OBrien

1988-01-01

204

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

205

(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

206

Trigonometric approximations for the computation of Radar cross sections  

Microsoft Academic Search

Trigonometric approximation methods for the interpolation of the far field of a scatterer lit up by plane waves are presented. The Wacker method, commonly used to determine the far field of an antenna from spherical near field measurements, is adapted to decompose the scattered field in a finite series of vector spherical harmonics. The decomposition coefficients are used to assess

Giuseppe Borzì

2004-01-01

207

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

208

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

209

RCS: An Intelligent Agent Architecture  

Microsoft Academic Search

RCS (Real-time Control System) is an intelligent agent architecture designed to enable any level of intelligent behavior, up to and including human levels of performance. RCS was inspired 30 years ago by a theoretical model of the cerebellum, the portion of the brain responsible for fine motor coordination and control of conscious motions. It was originally designed for sensory-interactive goal-

Jim Albus; Tony Barbera; Craig Schlenoff

210

A New Neutrino Cross Section Database  

E-print Network

We describe a new web based data resource being developed to provide access to accurate and validated cross sections of low energy neutrino and antineutrino interactions. The proposed content of this database are outlined which cover total and differential cross from inclusive, quasi-elastic and exclusive pion production processes from charged and neutral current interactions. Efforts to obtain these data, which come mainly from old bubble chamber experiments, are described as well as the implementation of an embryonic web site to make the resource generally accessible.

M. R. Whalley

2004-10-29

211

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

212

Measurement of actinide neutron cross sections  

SciTech Connect

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

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

2003-06-15

213

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

214

Accurate universal parameterization of absorption cross sections II--neutron absorption cross sections  

NASA Technical Reports Server (NTRS)

A recent parameterization (here after referred as paper I, Ref. [4]) of absorption cross sections for any system of charged ions collisions including proton -nucleus collisions, is extended for neutron-nucleus collisions valid from approximately 1 MeV to a few GeV, thus providing a comprehensive picture of absorption cross sections for any system of collision pair (charged and/or uncharged). The parameters are associated with the physics of the problem. At lower energies, the optical potential at the surface is important and the Pauli operator plays an increasingly important role at intermediate energies. The agreement between the calculated and experimental data is better than earlier published results.

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

1997-01-01

215

Applying GTD to calculate the RCS of polygonal plates  

Microsoft Academic Search

A difficulty that may be encountered in applying the geometrical theory of diffraction (GTD) to calculate the radar cross section (RDC) of polygonal plates is discussed. The simple example of a square plate is considered and it is shown that when the same specular direction is reached through two different pattern cuts, a different value of the total scattered field

Giuseppe Pelosi; R. Tiberio; S. Puccini; S. Maci

1990-01-01

216

EXPLAINING DISCREPANCIES BETWEEN LONGITUDINAL AND CROSS-SECTIONAL MODELS  

EPA Science Inventory

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

217

Total and ionization cross sections of electron scattering by fluorocarbons  

NASA Astrophysics Data System (ADS)

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

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

2005-02-01

218

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

219

Electron Elastic-Scattering Cross-Section Database  

National Institute of Standards and Technology Data Gateway

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

220

Why understanding neutrino cross sections is important for astrophysics  

SciTech Connect

Neutrino cross sections are important in many different astrophysical environments. Particularly needed is information about low energy (tens of MeV) cross sections. We review, for a few situations, the importance of neutrino cross sections for supernovae, gamma ray bursts and neutron stars.

McLaughlin, G. C. [Department of Physics North Carolina State University, Raleigh, NC 27695-8202 (United States)

2007-12-21

221

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

NASA Technical Reports Server (NTRS)

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

Minott, P. O.

1974-01-01

222

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

223

The hadronic cross section measurement at KLOE  

NASA Astrophysics Data System (ADS)

KLOE uses the radiative return to measure the hadronic cross section e+e- ? ? +- at DANE. Theemission of one or more hard photons in the initial state ( ISR) reduces the collision energy, otherwise fixed at 1020 MeV, and allows to perform an effective scan of the two pions invariant mass squared, s?, in the whole s?, region from threshold to m?2. An extremely accurate knowledge of experimental systematics, background, luminosity and, on the theoretical side, a precise description of initial state radiation are needed to perform a competitive measurement. We present here the status of the analysis of 140 pb -1 collected in 2001. A preliminary evaluation of the hadronic contribution to a? in the s? range between 0.37 GeV 2 and 0.93 GeV 2 yields a? = 378.4 ± 0.8 stat ± 4.5 syst ± 3.0 theo ± 3.8 FSR, consistent with the CMD-2 result and confirming the present discrepancy between e+e - and ? data.

Valeriani, B.; KLOE Collaboration

224

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

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

225

Cross-section optimization of tower crane lattice boom  

Microsoft Academic Search

This paper discusses the problem of cross-section optimization of tower crane lattice boom. The trapezoid cross section has\\u000a been analyzed. The triangular and rectangular cross sections have also been analyzed as special cases. Total mass of the construction\\u000a has been selected as the objective function. Optimization parameters have been determined by Lagrange’s multipliers method.\\u000a Criterion of stress is used as

R. Mijailovi?; G. Kastratovi?

2009-01-01

226

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

227

Derivation of reaction cross sections from experimental elastic backscattering probabilities  

E-print Network

The relationship between the backward elastic scattering probabilities and reaction cross sections is derived. This is a a very simple and useful method to extract reaction cross sections for heavy ion systems. We compare the results of our method with those using 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 using the present method, we derive the cross sections of other mechanisms for nearly spherical systems.

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

2013-11-17

228

Neutron-capture Cross Sections from Indirect Measurements  

SciTech Connect

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

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

2011-10-18

229

Exponent of Cross-sectional Dependence: Estimation and Inference  

E-print Network

, how to model cross-sectional dependence, and how to carry out counterfactual exercises under alterna- tive network formations or market inter-connections. Many of these topics are the subject of ongoing research. In this paper we focus on measures... of cross-sectional dependence and how such measures are related to the behaviour of cross-sectional averages or aggregates. Perhaps, the simplest and most concise way to motivate the need for determining the extent of cross-sectional dependence is to view...

Bailey, Natalia; Kapetanios, George; Pesaran, M. Hashem

2012-01-23

230

Positive Scattering Cross Sections using Constrained Least Squares  

SciTech Connect

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

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

1999-09-27

231

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

232

PRELIMINARY LES OVER A HYPERSONIC ELLIPTICAL CROSS-SECTION CONE  

E-print Network

PRELIMINARY LES OVER A HYPERSONIC ELLIPTICAL CROSS-SECTION CONE M.P. MARTIN Mechanical. The characteristics of the hypersonic flow around an elliptical- cross section cone and the computational code of transitional and turbulent flows are not fully understood. This is especially true in the hypersonic regime

Martín, Pino

233

Comparison of differential and integral cross section measurements  

Microsoft Academic Search

A program has been undertaken to simultaneously measure integral and ; differential cross sections in order to establish the degree of consistency ; between integral and differentially derived spectra. An assessment is then made ; concerning cross section limitations in deriving high energy neutron spectra by ; the foil-activation spectral-unfolding technique. (SDF)

L. R. Greenwood; R. R. Heinrich; N. D. Dudey

1975-01-01

234

The effect on cross sections for Quad Cities by introducing  

E-print Network

vs The effect on cross sections for Quad Cities by introducing control rod history in the assembly THE EFFECT ON CROSS SECTIONS FOR QUAD CITIES BY INTRODUCING CONTROL ROD HISTORY IN THE ASSEMBLY PROGRAM for the BWR reactor Quad Cities by introducing control rod "history" in the assembly program LEWARD. Control

235

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

236

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

237

Attachment cross-sections of protonated and deprotonated water clusters  

E-print Network

and several additional peaks corresponding to the attachment of water molecules onto the parent cluster. We1 Attachment cross-sections of protonated and deprotonated water clusters Sébastien Zamith1 Toulouse, France Abstract Attachment cross-sections of water molecules onto size selected protonated

Paris-Sud XI, Université de

238

Electromgnetic-gravitational cross-sections in external elctromagnetic fields  

E-print Network

The classical processes: the conversion of photons into gravitons in the static electromagnetic fields are considered by using Feynman perturbation techniques. The differential cross sections are presented for the conversion in the electric field of the flat condesor and the magnetic field of the selenoid. A numerical evaluation shows that the cross sections may have the observable value in the present technical scenario.

Hoang Ngoc Long; Dang Van Soa; Tuan A. Tran

1994-10-03

239

Electron impact ionization cross sections of phosphorus and arsenic molecules  

E-print Network

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

Paris-Sud XI, Université de

240

Positive Scattering Cross Sections using Constrained Least Squares  

Microsoft Academic Search

A method which creates a positive Legendre expansion from truncated Legendre cross section libraries is presented. The cross section moments of order two and greater are modified by a constrained least squares algorithm, subject to the constraints that the zeroth and first moments remain constant, and that the standard discrete ordinate scattering matrix is positive. A method using the maximum

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

1999-01-01

241

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

242

Measuring the differential scattering cross-section of gold nanoparticles  

NASA Astrophysics Data System (ADS)

In this paper we present an experimental apparatus capable of measuring the differential scattering cross sections of individual nanoparticles and arrangement of nanoparticles. We show that the mapping a partial differential scattering cross section, qualitative information about the electromagnetic local density of states dominated by evanescent modes scattered by the structure can be obtained.

Huang, C.; Bouhelier, A.; Colas des Francs, G.; Weeber, J.-C.; Dereux, A.

2008-08-01

243

Incoherent scattering cross sections for some ions of solar abundance  

SciTech Connect

Incoherent scattering cross sections are calculated in a relativistic formalism for a number of ions abundant in the solar atmosphere. It is argued that such cross sections are necessary for properly calculating Compton scattering and radiation transport in this or similar environments.

Kahane, Sylvian [Physics Department, Nuclear Research Center Negev, PO Box 9001, 84190 Beer Sheva (Israel)]. E-mail: skahane@bgu.ac.il

2007-03-15

244

Electron-impact total cross sections for phosphorous triflouride  

NASA Astrophysics Data System (ADS)

Various total cross sections for scattering of electrons by phosphorous triflouride (PF3) using the R-matrix method for incident energies from 0.1-15 eV and using spherical complex optical potential formalism beyond ionization threshold of target to 5000 eV are reported. We performed close-coupling calculations using static exchange plus polarization model. We employed different target models in order to study their relative dependence on the total cross sections. Three important structures are revealed in the total-cross-section curve: one that corresponds to the Ramsauer-Townsend minimum at 0.33 eV, the second is a strong maximum of 100 Å2 at 1 eV, the third is around 11 eV corresponding to negative ion formation as predicted by earlier study. The total ionization cross sections are computed using the complex scattering potential ionization contribution method and the binary encounter Bethe method. The electronic-excitation cross sections, momentum-transfer cross sections, and differential and ionization cross sections are our maiden efforts for this system. We have compared our total-cross-section results with available theoretical and experimental results.

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

2014-06-01

245

A New Technique To Investigate Total Reaction Cross Sections  

SciTech Connect

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

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

2010-08-04

246

Benchmark Calculations of Electron-Impact Differential Cross Sections  

SciTech Connect

The calculation of electron-atom excitation and ionization cross section is considered in both the non-relativistic and relativistic scattering theory. We consider electron collisions with H, He, Cs, and Hg. Differential cross sections for elastic scattering and ionization are presented.

Bray, I.; Bostock, C. J.; Fursa, D. V.; Hines, C. W.; Kadyrov, A. S.; Stelbovics, A. T. [ARC Centre for Antimatter-Matter Studies, Curtin University, GPO Box U1987 Perth, Western Australia 6845 (Australia)

2011-05-11

247

Isolated photon cross section measurement at D0  

SciTech Connect

We report a new measurement of the isolated photon cross section by the D0 experiment at Fermilab using 326 pb{sup -1} of data from Run II of the Tevatron. The measured cross section agrees with the theoretical predictions within uncertainties.

Kumar, Ashish; /SUNY, Buffalo

2006-05-01

248

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

249

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

250

Electron scattering cross-section measurements in ESEM.  

PubMed

A review, analysis and discussion on the derivation and measurement of electron scattering cross-sections of gases mostly used in environmental scanning electron microscopy is presented together with some previously unreported experimental material. There are significant differences in values published for cross-sections of such gases. Scanning the electron beam across a clean edge seems to be a most reliable technique to produce and measure beam profiles, from which the scattering cross-sections can be obtained with high accuracy and reliability. Results based on this method produce an excellent agreement with a theoretically derived value of scattering cross-section using an average factor of energy loss for all inelastic collisions. The discussion addresses the difficulties involved and provides alternative ways to reliably obtain cross-sections as a function of accelerating voltage in the range mostly used in environmental scanning electron microscopy. PMID:23154136

Danilatos, Gerasimos D

2013-02-01

251

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

252

Joint strength in RCS frames  

E-print Network

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

Kirby, Cynthia Dawn

2012-06-07

253

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

254

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

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

255

Cross Section Sensitivity and Propagated Errors in HZE Exposures  

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

256

Cross sections for electron scattering by atomic potassium  

SciTech Connect

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

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

1992-12-01

257

Review of electron impact excitation cross sections for copper atom  

SciTech Connect

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 cross sections, and the uncertainty in the correct normalization of the data has been a source of confusion and concern for the kinetic modeling efforts. This difficulty has motivated us to review previous work on the electron impact excitation of copper atom and to perform new calculations of the inelastic cross sections using the impact parameter method. In this memorandum we review the previous attempts to normalize the experimental data and provide a critical assessment of the accuracy of the resulting cross sections. We also present new theoretical cross sections for the electron impact excitation of the /sup 2/S ..-->.. /sup 2/P/sup 0/ and /sup 2/S ..-->.. /sup 2/D transitions in copper. When the experimental cross sections are renormalized to the results of the impact parameter calculations, they are a factor of three smaller than those published in the latest paper of Trajmar et. al. At impact energies above 60 eV the excitation cross sections obtained with the impact parameter method agree well with the results of the very recent, unpublished, close-coupling calculations of Henry. This agreement suggests that the present normalization of the experimental cross sections is probably the most reliable one obtained to date.

Winter, N.W.; Hazi, A.U.

1982-02-01

258

Neutron total scattering cross sections of elemental antimony  

SciTech Connect

Neutron total cross sections are measured from 0.8 to 4.5 MeV with broad resolutions. Differential-neutron-elastic-scattering cross sections are measured from 1.5 to 4.0 MeV at intervals of 50 to 200 keV and at scattering angles distributed between 20 and 160 degrees. Lumped-level neutron-inelastic-scattering cross sections are measured over the same angular and energy range. The exPerimental results are discussed in terms of an optical-statistical model and are compared with respective values given in ENDF/B-V.

Smith, A.B.; Guenther, P.T.; Whalen, J.F.

1982-11-01

259

Top quark pair production cross section at Tevatron  

SciTech Connect

An overview of the recent measurements of the top antitop quark pair production cross section in proton antiproton collisions at {radical}s = 1.96 TeV in lepton + jets and dilepton final states is presented. These measurements are based on 1-2.8 fb{sup -1} of data collected with the D0 and CDF experiments at the Fermilab Tevatron collider. The cross section is measured with a precision close to 8 % and found to be compatible with the standard model prediction. Interpretations of the cross-section measurements for charge higgs search and for top quark mass measurement are also discussed.

Shary, V.; /DAPNIA, Saclay

2009-05-01

260

Neutron inelastic cross-section measurements for Mg24  

NASA Astrophysics Data System (ADS)

The ? production cross sections from neutron inelastic scattering on 24Mg were measured for neutron energies up to 18 MeV at GELINA (the Geel Linear Accelerator), the neutron source operated by EC-JRC-IRMM, Belgium. The level cross section and the total inelastic cross section were determined. We used the GAINS (Gamma Array for Inelastic Neutron Scattering) spectrometer with seven large-volume high-purity germanium (HPGe) detectors placed at 110? and 150? with respect to the beam direction. The neutron flux was determined with a U235 fission chamber. The results are compared with calculations performed with the talys 1.6 code using the default settings.

Olacel, A.; Borcea, C.; Dessagne, P.; Kerveno, M.; Negret, A.; Plompen, A. J. M.

2014-09-01

261

Low Energy Electron-Molecule Collision Cross Sections  

NASA Astrophysics Data System (ADS)

Recent progress in the measurement of absolute collision cross sections for electron molecule scattering is discussed in the context of measurements which have relevance to atmospheric phenomena and technological applications. Cross sections for low energy (< 5 eV) scattering from NO highlight the role of resonant processes in the excitation of this important atmospheric gas, while for both C2F4 and C4F8, which are used in plasma processing of semiconductors, we present a range of experimental data. In each case we make comparison of the measured cross sections with results derived from the analysis of transport data from electron swarm experiments.

Buckman, Stephen J.; Panajotovic, Radmila; Jelisavcic, Milica

262

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

263

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

264

Handbook of LHC Higgs Cross Sections: 2. Differential Distributions  

E-print Network

This Report summarises the results of the second year's activities of the LHC Higgs Cross Section Working Group. The main goal of the working group was to present the state of the art of Higgs Physics at the LHC, integrating all new results that have appeared in the last few years. The first working group report Handbook of LHC Higgs Cross Sections: 1. Inclusive Observables (CERN-2011-002) focuses on predictions (central values and errors) for total Higgs production cross sections and Higgs branching ratios in the Standard Model and its minimal supersymmetric extension, covering also related issues such as Monte Carlo generators, parton distribution functions, and pseudo-observables. This second Report represents the next natural step towards realistic predictions upon providing results on cross sections with benchmark cuts, differential distributions, details of specific decay channels, and further recent developments.

Dittmaier, S; Passarino, G; Tanaka, R; Alekhin, S; Alwall, J; Bagnaschi, E A; Banfi, A; Blumlein, J; Bolognesi, S; Chanon, N; Cheng, T; Cieri, L; Cooper-Sarkar, A M; Cutajar, M; Dawson, S; Davies, G; De Filippis, N; Degrassi, G; Denner, A; D'Enterria, D; Diglio, S; Di Micco, B; Di Nardo, R; Ellis, R K; Farilla, A; Farrington, S; Felcini, M; Ferrera, G; Flechl, M; de Florian, D; Forte, S; Ganjour, S; Garzelli, M V; Gascon-Shotkin, S; Glazov, S; Goria, S; Grazzini, M; Guillet, J -Ph; Hackstein, C; Hamilton, K; Harlander, R; Hauru, M; Heinemeyer, S; Hoche, S; Huston, J; Jackson, C; Jimenez-Delgado, P; Jorgensen, M D; Kado, M; Kallweit, S; Kardos, A; Kauer, N; Kim, H; Kovac, M; Kramer, M; Krauss, F; Kuo, C -M; Lehti, S; Li, Q; Lorenzo, N; Maltoni, F; Mellado, B; Moch, S O; Muck, A; Muhlleitner, M; Nadolsky, P; Nason, P; Neu, C; Nikitenko, A; Oleari, C; Olsen, J; Palmer, S; Paganis, S; Papadopoulos, C G; Petersen, T C; Petriello, F; Petrucci, F; Piacquadio, G; Pilon, E; Potter, C T; Price, J; Puljak, I; Quayle, W; Radescu, V; Rebuzzi, D; Reina, L; Rojo, J; Rosco, D; Salam, G P; Sapronov, A; Schaarschmidt, J; Schonherr, M; Schumacher, M; Siegert, F; Slavich, P; Spira, M; Stewart, I W; Stirling, W J; Stockli, F; Sturm, C; Tackmann, F J; Thorne, R S; Tommasini, D; Torrielli, P; Tramontano, F; Trocsanyi, Z; Ubiali, M; Uccirati, S; Acosta, M Vazquez; Vickey, T; Vicini, A; Waalewijn, W J; Wackeroth, D; Warsinsky, M; Weber, M; Wiesemann, M; Weiglein, G; Yu, J; Zanderighi, G

2012-01-01

265

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

266

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

267

Determination of absolute photoionization cross sections of the phenyl radical  

E-print Network

wavelengths. Using the photoionization cross section values for each channel, photoionization efficiency of interest to microwave spectroscopists and astrophysicists as these species are possible components wavelengths to create the radical and taking advantage of the multiple channels for chlorobenzene

Neumark, Daniel M.

268

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

269

11. DETAIL OF DITCH CROSS SECTION WITH VISUAL SCALES. DITCH ...  

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

11. DETAIL OF DITCH CROSS SECTION WITH VISUAL SCALES. DITCH WAS BISECTED BY LOCAL DRAINAGE; VIEW TO SOUTH. - Keefe-McDerby Mine Ditch, East of East Bidwell Street between Clarksville Road & Highway 50, Folsom, Sacramento County, CA

270

Compound-nuclear reaction cross sections from surrogate measurements  

NASA Astrophysics Data System (ADS)

Nuclear reaction cross sections are important for a variety of applications in the areas of astrophysics, nuclear energy, and national security. When these cross sections cannot be measured directly or predicted reliably, it becomes necessary to develop indirect methods for determining the relevant reaction rates. The surrogate nuclear reactions approach is such an indirect method. First used in the 1970s for estimating (n,f) cross sections, the method has recently been recognized as a potentially powerful tool for a wide range of applications that involve compound-nuclear reactions. The method is expected to become an important focus of inverse-kinematics experiments at rare-isotope facilities. The present paper reviews the current status of the surrogate approach. Experimental techniques employed and theoretical descriptions of the reaction mechanisms involved are presented and representative cross section measurements are discussed.

Escher, Jutta E.; Burke, Jason T.; Dietrich, Frank S.; Scielzo, Nicholas D.; Thompson, Ian J.; Younes, Walid

2012-01-01

271

An Exploratory Cross-Sectional Study of Interlanguage Pragmatic Development.  

ERIC Educational Resources Information Center

Reports results of an exploratory cross-sectional study of pragmatic development among three groups of primary school students in Hong Kong who complete a cartoon oral production task designed to elicit requests, apologies, and compliment responses. (Author/VWL)

Rose, Kenneth R.

2000-01-01

272

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

273

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

274

Fragmentation cross sections outside the limiting-fragmentation regime  

Microsoft Academic Search

The empirical parametrization of fragmentation cross sections, EPAX, has been successfully applied to estimate fragment production cross sections in reactions of heavy ions at high incident energies. It is checked whether a similar parametrization can be found for proton-induced spallation around 1 GeV, the range of interest for ISOL-type RIB facilities. The validity of EPAX for medium-energy heavy-ion induced reactions

K. Sümmerer

2003-01-01

275

Fragmentation cross sections of relativistic 208Pb projectiles  

Microsoft Academic Search

Production cross sections of more than 270 isotopes ranging from Z = 59 to Z = 82 were measured in the reaction 208Pb(1 GeV A)+Cu. The method of identifying the projectile fragments and evaluating the production cross sections is described. The experimental data are compared with a modern version of the abrasion-ablation model and with the empirical parameterization EPAX. Apart

M. de Jong; K.-H. Schmidt; B. Blank; C. Böckstiegel; T. Brohm; H.-G. Clerc; S. Czajkowski; M. Dornik; H. Geissel; A. Grewe; E. Hanelt; A. Heinz; H. Irnich; A. R. Junghans; A. Magel; G. Münzenberg; F. Nickel; M. Pfützner; A. Piechaczek; C. Scheidenberger; W. Schwab; S. Steinhäuser; K. Sümmerer; W. Trinder; B. Voss; C. Ziegler

1998-01-01

276

Predicted cross-sections for photon-induced particle emission  

Microsoft Academic Search

Cross-sections for the photon-induced particle-emission reactions (?,n), (?,p), and (?,?) are given for all natural isotopes from Ti to Bi. The target nuclei are assumed to be in their ground states, except for 180Ta which is naturally occurring as the isomer 180mTa. The cross-sections are calculated in a statistical model (Hauser–Feshbach) approach and covering an energy range from threshold up

T. Rauscher; F.-K. Thielemann

2004-01-01

277

Partial ionisation cross-sections of 2-propanol and ethanal  

Microsoft Academic Search

Electron impact ionisation of 2-propanol and ethanal is studied using mass spectrometry. Cross-sections of the formation of molecular ions and ionic fragments are measured between 14 and 86eV. Free energy changes are evaluated using ab initio calculations. For 2-propanol, two ions, identified as CH3CHOH+ (45amu) and CH3CHCH3+ (43amu), contribute more than 75% to the total cross-section over the whole range

J. R. Vacher; F. Jorand; N. Blin-Simiand; S. Pasquiers

2006-01-01

278

Photon Cross Sections at Ecm = 2 TeV  

E-print Network

Photon production rates have been studied by the D0 and CDF experiments in Run II of the Fermilab Tevatron Collider. Measurements of the inclusive isolated photon cross section and the di-photon cross section are presented, based on integrated luminosities of 0.3 fb-1 and 0.2 fb-1, respectively. The results are compared to perturbative QCD calculations in various approximations.

M. Wobisch

2006-06-30

279

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

280

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

281

Experimental nuclear cross sections for spacecraft shield analysis  

NASA Technical Reports Server (NTRS)

Experiments have been performed to validate and to supplement the intranuclear cascade model as a method for estimating cross sections of importance to spacecraft shield design. The experimental situation is inconclusive particularly for neutron-producing reactions, but is relatively sound for reaction cross sections and for proton spectra at several hundred MeV at medium forward angles. Secondary photon contributions are imprecisely known.

Peelle, R. W.

1972-01-01

282

Meteor head echo radar data: Mass-velocity selection effects  

NASA Astrophysics Data System (ADS)

High-power, large-aperture (HPLA) radars detect the plasma that forms in the vicinity of a meteoroid and moves approximately at its velocity; reflections from these plasmas are called head echoes. For over a decade, HPLA radars have been detecting head echoes with peak velocity distributions >50 km/s. These results have created some controversy within the field of meteor physics because previous data, including spacecraft impact cratering studies, optical and specular meteor data, indicate that the peak of the velocity distribution to a set limiting mass should be <20 km/s [Love, S.G., Brownlee, D.E., 1993. Science 262, 550-553]. Thus the question of whether HPLA radars are preferentially detecting high-velocity meteors arises. In this paper we attempt to address this question by examining both modeled and measured head echo data using the ALTAIR radar, collected during the Leonid 1998 and 1999 showers. These data comprise meteors originating primarily from the North Apex sporadic meteor source. First, we use our scattering theory to convert measured radar-cross-section (RCS) to electron line density and mass, as well as to convert modeled electron line density and mass to RCS. We subsequently compare the dependence between mass, velocity, mean-free-path, RCS and line density using both the measured and modeled data by performing a multiple, linear regression fit. We find a strong correlation between derived mass and velocity and show that line density is approximately proportional to mass times velocity 3.1. Next, we determine the cumulative mass index using subsets of our data and use this mass index, along with the results of our regression fit, to weight the velocity distribution. Our results show that while there does indeed exist a bias in the measured head echo velocity distribution, it is smaller than those calculated using traditional specular trail data due to the different scattering mechanism, and also includes a bias against the low-mass, very high-velocity meteoroids.

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

2007-02-01

283

Cross-sectional area and intensity variations of sausage modes  

NASA Astrophysics Data System (ADS)

Context. The observations obtained using the Rapid Oscillations in the Solar Atmosphere instrument (ROSA) show variations in both cross-sectional area and intensity for magnetic pores in the photosphere. Aims: We study the phase behaviour between cross-sectional area and intensity variations for sausage modes in a photospheric context. We aim to determine the wave mode by looking at the phase difference between the cross-sectional area and intensity variations. Methods: We used a straight cylinder as a model for the flux tube. The plasma is uniform both inside and outside the flux tube with a possible jump in the equilibrium values at the boundary, the magnetic field is directed along the flux tube. We derived analytic expressions for the cross-sectional area variation and the total intensity variation. Using these analytic expressions, we calculated the phase differences between the cross-sectional area and the intensity variations. These phase differences were then used to identify the wave mode. Results: We found that for slow sausage modes the cross-sectional area and intensity variations are always in phase, while for fast sausage modes the variations are in antiphase. Appendix A is available in electronic form at http://www.aanda.org

Moreels, M. G.; Goossens, M.; Van Doorsselaere, T.

2013-07-01

284

Krypton charge exchange cross sections for Hall effect thruster models  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

285

Krypton charge exchange cross sections for Hall effect thruster models  

SciTech Connect

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

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

2013-04-28

286

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

287

Photodissociation cross section of ClOOCl at 330 nm.  

PubMed

The photolysis rate of ClOOCl is crucial in the catalytic destruction of polar stratospheric ozone. In this work, we determined the photodissociation cross section of ClOOCl at 330 nm with a molecular beam and with mass-resolved detection. The photodissociation cross section is the product of the absorption cross section and the dissociation quantum yield. We formed an effusive molecular beam of ClOOCl at a nozzle temperature of 200 or 250 K and determined its photodissociation probability by measuring the decrease of the ClOOCl intensity upon laser irradiation. By comparing with a reference molecule (Cl(2)), of which the absorption cross section and dissociation quantum yield are well-known, we determined the absolute photodissociation cross section of ClOOCl at 330 nm to be (2.31 +/- 0.11) x 10(-19) cm(2) at 200 K and (2.47 +/- 0.12) x 10(-19) cm(2) at 250 K. Impurity interference has been a well-recognized problem in conventional spectroscopic studies of ClOOCl; our mass-resolved measurement directly overcomes such a problem. This measurement of the ClOOCl photolysis cross section at 330 nm is particularly useful in constraining its atmospheric photolysis rate, which in the polar stratosphere peaks near this wavelength. PMID:20085296

Jin, Bing; Chen, I-Cheng; Huang, Wen-Tsung; Lien, Chien-Yu; Guchhait, Nikhil; Lin, Jim J

2010-04-15

288

Total cross sections for neutron-nucleus scattering  

E-print Network

Systematics of neutron scattering cross sections on various materials for neutron energies up to several hundred MeV are important for ADSS applications. Ramsauer model is well known and widely applied to understand systematics of neutron nucleus total cross sections. In this work, we examined the role of nuclear effective radius parameter (r$_0$) on Ramsauer model fits of neutron total cross sections. We performed Ramsauer model global analysis of the experimental neutron total cross sections reported by W. P. Abfalterer, F. B. Bateman, {\\it et. al.,}, from 20MeV to 550MeV for nuclei ranging from Be to U . The global fit functions which can fit total cross section data over periodic table are provided along with the required global set of parameters. The global fits predict within $\\pm 8%$ deviation to data, showing the scope for improvement. It has been observed that a finer adjustment of r$_0$ parameter alone can give very good Ramsauer model description of neutron total scattering data within $\\pm 4%$ deviation. The required r$_0$ values for Ramsauer model fits are shown as a function of nuclear mass number and an empirical formula is suggested for r$_0$ values as a function of mass number. In optical model approach for neutron scattering, we have modified the real part of Koning-Deleroche potentails to fit the neutron total cross sections using SCAT2 code. The modified potentails have a different energy dependence beyond 200MeV of neutron energy and fit the total cross sections from Al to Pb.

S. V. Suryanarayana; H. Naik; S. Ganesan; S. Kailas; R. K. Choudhury; Guinyum Kim

2010-05-28

289

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

290

Angle dependent total cross sections and the optical theorem.  

PubMed

Cross sections are either represented by generalized asymptotical partial wave expansions or obtained as a spherical average of an appropriate differential cross section. In these cases it is usually assumed that the total scattering cross section, as a property of a scattering object, does not depend on the incident angles. This viewpoint is supported by common knowledge in connection with low energy scattering. However this unconscious belief is not always correct. In the present paper we will show that a non-spherical scatterer may exhibit strong dependence on the incident direction. To do this we will represent the scattering data of the most general potential, separable in ellipsoidal coordinates, in perturbed ellipsoidal (Lamé) wave functions. These functions arise when variables in the Schrödinger equation are separated in an ellipsoidal coordinate system. The Lamé wave functions are analogous to spherical- and Bessel functions in the case of spherical symmetry. We will expand the total scattering cross section and derive the optical theorem explicitly demonstrating the incident angle dependence for such a class of potentials. As an illustration we will present and display some calculations of the total cross section versus incident direction. Unexpected behavior will be discussed and explained. We also use results from classical acoustic scattering by a triaxial ellipsoid. The general character of the ellipsoidal coordinate system is emphasized. PMID:11153801

Levitina, T V; Brändas, E J

2001-01-01

291

Angle dependent total cross sections and the optical theorem.  

PubMed

Cross sections are either represented by generalized asymptotical partial wave expansions or obtained as a spherical average of an appropriate differential cross section. In these cases it is usually assumed that the total scattering cross section, as a property of a scattering object, does not depend on the incident angles. This viewpoint is supported by common knowledge in connection with low energy scattering. However this unconscious belief is not always correct. In the present paper we will show that a non-spherical scatterer may exhibit strong dependence on the incident direction. To do this we will represent the scattering data of the most general potential, separable in ellipsoidal coordinates, in perturbed ellipsoidal (Lamé) wave functions. These functions arise when variables in the Schrödinger equation are separated in an ellipsoidal coordinate system. The Lamé wave functions are analogous to spherical- and Bessel functions in the case of spherical symmetry. We will expand the total scattering cross section and derive the optical theorem explicitly demonstrating the incident angle dependence for such a class of potentials. As an illustration we will present and display some calculations of the total cross section versus incident direction. Unexpected behavior will be discussed and explained. We also use results from classical acoustic scattering by a triaxial ellipsoid. The general character of the ellipsoidal coordinate system is emphasized. PMID:12927118

Levitina, T V; Brändas, E J

2003-07-01

292

Stellar neutron capture cross sections of the Yb isotopes.  

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of 170Yb, 171Yb, 172Yb, 173Yb, 174Yb, and 176Yb have been measured in the energy range from 3 to 225 keV at the Karlsruhe 3.75 MV Van de Graaff accelerator. Neutrons were produced via the 7Li(p,n)7Be reaction by bombarding metallic Li targets with a pulsed proton beam. Capture events were registered with the Karlsruhe 4? barium fluoride detector. The cross sections were determined relative to the gold standard. Neutron capture in the even ytterbium isotopes is characterized by a strong population of isomeric states, resulting in severe systematic uncertainties in previous experiments. In the present work, the partial cross sections to the ground- and isomeric states in 172Yb, 174Yb, 176Yb could be experimentally separated for the first time, yielding cross section ratios with an overall uncertainty of 1 - 1.5%. Compared to previous measurements, this corresponds to an improvement by factors of 4 to 10. Maxwellian averaged neutron capture cross sections were calculated for thermal energies between kT = 8 keV and 100 keV. The results of four isotopes differ by more than 15% from recent evaluations.

Wisshak, K.; Voss, F.; Käppeler, F.; Kazakov, L.

1998-11-01

293

Absolute cross sections for electron scattering from furan  

NASA Astrophysics Data System (ADS)

We report results of measurements and calculations of absolute cross sections for electron scattering from furan molecules (C4H4O). The experimental absolute differential cross sections (DCSs) for elastic electron scattering were obtained for the incident energies from 50 eV to 300 eV and for scattering angles from 20º to 110º, by using a crossed electron-target beam setup and the relative flow technique for calibration to the absolute scale. The calculations of the electron interaction cross sections are based on a corrected form of the independent-atom method, known as the screening corrected additivity rule (SCAR) procedure and using an improved quasifree absorption model. The latter calculations also account for rotational excitations in the approximation of a free electric dipole and were used to obtain elastic DCSs as well as total and integral elastic cross sections which are tabulated in the energy range from 10 to 10 000 eV. All SCAR calculated cross sections agree very well with both the present and previously published experimental results. Additionally, calculations based on the first Born approximation were performed to calculate both elastic and vibrationally inelastic DCSs for all the modes of furane, in the energy range from 50 eV to 300 eV. The ratios of the summed vibrational to elastic DCSs are presented and discussed. Finally, the present results for furan are compared with previously published elastic DCSs for the tetrahydrofuran molecule and discussed.

Maljkovi?, J. B.; Blanco, F.; ?urík, R.; García, G.; Marinkovi?, B. P.; Milosavljevi?, A. R.

2012-08-01

294

Application of simple ramsauer model to neutron total cross sections  

SciTech Connect

The simple nuclear Ramsauer model has been used successfully to fit neutron cross sections for three decades, but has not been widely used because the foundations of the model seem to be so unrealistic. We have shown that the Glauber calculations with the inclusion of refraction and optical model calculations essentially validate this simple model for neutron total cross sections in the neutron energy range of 5-50 MeV. This model yields a simple formula for parameterizing the energy dependence of the neutron cross section. We have applied the model to nuclei ranging from vanadium to bismuth. With the addition of a single parameter, we can improve these fits to less than 1.5%.

Bauer, R.W.; Anderson, J.D.; Grimes, S.M.; Madsen, V.A.

1997-04-29

295

Fast-neutron total and scattering cross sections of niobium  

SciTech Connect

Neutron total cross sections of niobium were measured from approx. = 0.7 to 4.5 MeV at intervals of less than or equal to 50 keV with broad resolution. Differential-elastic-scattering cross sections were measured from approx. = 1.5 to 4.0 MeV at intervals of 0.1 to 0.2 MeV and at 10 to 20 scattering angles distributed between approx. = 20 and 160 degrees. Inelastically-scattered neutrons, corresponding to the excitation of levels at: 788 +- 23, 982 +- 17, 1088 +- 27, 1335 +- 35, 1504 +- 30, 1697 +- 19, 1971 +- 22, 2176 +- 28, 2456 +- (.), and 2581 +- (.) keV, were observed. An optical-statistical model, giving a good description of the observables, was deduced from the measured differential-elastic-scattering cross sections. The experimental-results were compared with the respective evaluated quantities given in ENDF/B-V.

Smith, A.B.; Guenther, P.T.; Whalen, J.F.

1982-07-01

296

Ionization cross sections for low energy electron transport  

E-print Network

Two models for the calculation of ionization cross sections by electron impact on atoms, the Binary-Encouter-Bethe and the Deutsch-Maerk models, have been implemented; they are intended to extend and improve Geant4 simulation capabilities in the energy range below 1 keV. The physics features of the implementation of the models are described, and their differences with respect to the original formulations are discussed. Results of the verification with respect to the original theoretical sources and of extensive validation with respect to experimental data are reported. The validation process also concerns the ionization cross sections included in the Evaluated Electron Data Library used by Geant4 for low energy electron transport. Among the three cross section options, the Deutsch-Maerk model is identified as the most accurate at reproducing experimental data over the energy range subject to test.

Seo, Hee; Saracco, Paolo; Kim, Chan Hyeong

2011-01-01

297

Ionization cross sections for low energy electron transport  

E-print Network

Two models for the calculation of ionization cross sections by electron impact on atoms, the Binary-Encouter-Bethe and the Deutsch-Maerk models, have been implemented; they are intended to extend and improve Geant4 simulation capabilities in the energy range below 1 keV. The physics features of the implementation of the models are described, and their differences with respect to the original formulations are discussed. Results of the verification with respect to the original theoretical sources and of extensive validation with respect to experimental data are reported. The validation process also concerns the ionization cross sections included in the Evaluated Electron Data Library used by Geant4 for low energy electron transport. Among the three cross section options, the Deutsch-Maerk model is identified as the most accurate at reproducing experimental data over the energy range subject to test.

Hee Seo; Maria Grazia Pia; Paolo Saracco; Chan Hyeong Kim

2011-10-11

298

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

299

pi+- p differential cross sections at low energies  

E-print Network

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

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

2005-12-03

300

Photoabsorption cross section of acetylene in the EUV region  

NASA Technical Reports Server (NTRS)

The measurement of the absolute photoabsorption cross sections of C2H2 in the 175-740 A region by means of a double ionization chamber is reported. The continuum background source is the synchrotron radiation emitted by the Wisconsin 240 MeV electron storage ring. It is found that the cross sections range from 2 to a maximum of 36 Mb. Two new Rydberg series are identified and the cross section data are applied in the analysis of various sum rules. From the rules, it is shown that the data of C2H2 in the 580-1088 A range may be too low, while the measured ionization transition moment may be too high.

Wu, C. Y. R.; Judge, D. L.

1985-01-01

301

Recent advances in modeling fission cross sections over intermediate structures  

SciTech Connect

More accurate fission cross section calculations in presence of underlying intermediate structure are strongly desired. This paper recalls the common approximations used below the fission threshold and quantifies their impact. In particular, an exact expanded R-matrix Monte Carlo calculation of the intermediate structure, deeply mixed with the fluctuations of the class-I and II decay amplitudes, is shown. This paper also insists on the microscopic structure of the level densities as a function of the nucleus deformation and show preliminary neutron induced fission cross section calculations for {sup 239}Pu and {sup 240}Pu using newly calculated combinatorial level densities. Comparisons with recent evaluated and measured fission cross sections are made.

Bouland, Olivier [Los Alamos National Laboratory; Lynn, J. Eric [Los Alamos National Laboratory; Talou, Patrick [Los Alamos National Laboratory

2009-01-01

302

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

303

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

304

Elastic electron scattering cross sections at high momentum transfer  

NASA Astrophysics Data System (ADS)

The elastic scattering cross section of keV electrons over large angles (>90°) is discussed. A comparison is made of the Rutherford cross section, the cross section obtained in the first Born approximation and that obtained by a partial wave calculation. The last approach differs significantly from the first two. For compounds, the recoil energy makes it possible to distinguish experimentally from which atom the electron has scattered. We compare the elastic peak ratio of H and O in water at several keV and for Hf and O in HfO2 at 20-40 keV with the calculated ratios. Reasonable (but not perfect) agreement is obtained between the experiment and theory for the partial wave calculations.

Vos, M.; McEachran, R. P.; Weigold, E.; Bonham, R. A.

2013-04-01

305

Stellar neutron capture cross sections of the Ba isotopes  

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of 134Ba, 135Ba, 136Ba, and 137Ba were measured in the energy range from 5 to 225 keV at the Karlsruhe 3.75 MV Van de Graaff accelerator. Neutrons were produced via the 7Li (p,n)7 Be reaction by bombarding metallic Li targets with a pulsed proton beam. Capture events were registered with the Karlsruhe 4? barium fluoride detector. The cross section ratios were determined with an overall uncertainty of ~3%, an improvement by factors of 5 to 8 compared to existing data. Severe discrepancies were found with respect to previous results. As a new possibility in time of flight experiments, isomeric cross section ratios could be determined for 135Ba, 136Ba, and 137Ba. Maxwellian averaged neutron capture cross sections were calculated for thermal energies between kT=10 keV and 100 keV. These stellar cross sections were used in an s-process analysis. For the s-only isotopes 134Ba and 136Ba the Ns ratio was determined to 0.875+/-0.025. Hence, a significant branching of the s-process path at 134Cs can be claimed for the first time, in contrast to predictions from the classical approach. This branching yields information on the s-process temperature, indicating values around T8=2. The new cross sections are also important for the interpretation of barium isotopic anomalies, which were recently discovered in SiC grains of carbonaceous chondrite meteorites. Together with the results from previous experiments on tellurium and samarium, a general improvement of the Ns systematics in the mass range A=120-150 is achieved. This yields a more reliable separation of s- and r-process contributions for comparison with stellar observations, but reveals a 20% discrepancy with respect to the solar barium abundance.

Voss, F.; Wisshak, K.; Guber, K.; Käppeler, F.; Reffo, G.

1994-11-01

306

Analysis of Ku-band cross section at low incidence angles  

NASA Technical Reports Server (NTRS)

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

Chapron, B.; Vandemark, D.

1993-01-01

307

Singly differential cross sections with exchange for Ps-fragmentation  

E-print Network

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

Hasi Ray

2008-08-28

308

Direct processes effects on deuteron activation cross sections  

NASA Astrophysics Data System (ADS)

An extended analysis of reaction mechanisms involved in deuterons interaction with target nuclei from 27Al till 231Pa, at incident energies up to 60 MeV, is presented. Increased attention is devoted to direct processes, concerning the breakup, stripping, and pickup contributions to the deuteron activation cross sections. Finally, the pre-equilibrium and evaporation cross sections, corrected for the initial flux leakage towards direct processes, have completed the deuteron interaction analysis. The overall agreement of the measured data and model calculations proves the correctness of nuclear mechanism description.

Avrigeanu, M.; Avrigeanu, V.

2014-09-01

309

Fast-neutron scattering cross sections of elemental zirconium  

SciTech Connect

Differential neturon-elastic-scattering cross sections of elemental zirconium are measured from 1.5 to 4.0 MeV at intervals of less than or equal to 200 keV. Inelastic-neutron-scattering cross sections corresponding to the excitation of levels at observed energies of: 914 +- 25, 1476 +- 37, 1787 +- 23, 2101 +- 26, 2221 +- 17, 2363 +- 14, 2791 +- 15 and 3101 +- 25 keV are determined. The experimental results are interpreted in terms of the optical-statistical model and are compared with corresponding quantities given in ENDF/B-V.

Smith, A.B.; Guenther, P.T.

1982-12-01

310

Dielectronic-Recombination Cross-Sections of Hydrogenlike Argon  

E-print Network

PHYSICAL REVIEW A VOLUME 44, NUMBER 11 1 DECEMBER 1991 Dielectronic-recombination cross sections of hytlrogenlike argon D. R. DeWitt, D. Schneider, M. W. Clark, and M. H. Chen Latvrenee Livermore National Laboratory, University of California.... Comparison with theory shows that the total cross sections agree within +6%%uo. PACS number(s): 34.80.Kw, 34.80.Dp, 52.20.Fs INTRODUCTION The importance of the dielectronic-recombination (DR) process as a major contributor to the ion balance in high...

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

1991-01-01

311

Differential Cross Sections for Proton-Proton Elastic Scattering  

NASA Technical Reports Server (NTRS)

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

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

2009-01-01

312

Photoabsorption cross sections of OH at 115-183 nm  

NASA Technical Reports Server (NTRS)

The absorption spectrum for OH was obtained in the 115-183 nm region. The OH radicals were produced by a pulse discharge of trace H2O in few torr of Ar. Absorption cross sections were obtained by calibration with absorption of the OH (X 2 Pi to A 2 Sigma +) transition. The features in the absorption spectrum are correlated with the excited states 1 2 Sigma -, D 2 Sigma -, 1 2 Delta, B 2 Sigma + and possibly others calculated by van Dishoeck, Langhoff, and Dalgarno. The measured cross sections are comparable with the calculated values.

Nee, J. B.; Lee, L. C.

1984-01-01

313

Light ray tracing through a leaf cross section  

NASA Technical Reports Server (NTRS)

A light ray, incident at about 5 deg to the normal, is geometrically plotted through the drawing of the cross section of a soybean leaf using Fresnel's equations and Snell's law. The optical mediums of the leaf considered for ray tracing are air, cell sap, chloroplast, and cell wall. The above ray is also drawn through the same leaf cross section considering cell wall and air as the only optical mediums. The values of the reflection and transmission found from ray tracing agree closely with the experimental results obtained using a Beckman DK-2A spectroreflectometer.

Kumar, R.; Silva, L.

1973-01-01

314

Suppressed fusion cross section for neutron halo nuclei  

E-print Network

Fusion reactions of neutron-halo nuclei are investigated theoretically with a three-body model. The time-dependent wave-packet method is used to solve the three-body Schrodinger equation. The halo neutron behaves as a spectator during the Coulomb dissociation process of the projectile. The fusion cross sections of 11Be-209Bi and 6He-238U are calculated and are compared with measurements. Our calculation indicates that the fusion cross section is slightly hindered by the presence of weakly bound neutrons.

Makoto Ito; Kazuhiro Yabana; Takashi Nakatsukasa; Manabu Ueda

2005-06-23

315

QE Neutrino CC Cross Sections off 16O  

E-print Network

The charged-current quasi-elastic scattering of muon neutrino on oxygen target is computed for neutrino energy between 200 MeV and 2.5 GeV using different approximations: the Plane Wave Impulse Approximation (PWIA), the Relativistic Distorted Wave Impulse Approximation with relativistic optical potential (RDWIA), and the Relativistic Fermi Gas Model (RFGM). The comparison with RFGM, which is widely used in data analyses of neutrino experiments, shows that the RFGM fails completely when applied to exclusive cross section data and leads to overestimated values of inclusive and total cross sections.

A. V. Butkevich; S. A. Kulagin

2007-11-20

316

Neutrino cross section measurements @ SciBooNE  

E-print Network

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. Contribution to NUFACT 11, XIIIth International Workshop on Neutrino Factories, Super beams and Beta beams, 1-6 August 2011, CERN and University of Geneva (Submitted to IOP conference series)

C. Mariani

2011-10-07

317

Cosmic Neutrino Secret Interactions, Enhancement and Total Cross Section  

E-print Network

The scattering of neutrinos assuming a "secret" interaction at low energy is considered. To leading order in energy, the two-body potential is a delta-potential, and it is used to model all short-range elastic interactions between neutrinos. The scattering cross section depends only on the renormalized strength of the potential, while the Sommerfeld enhancement factor also depends on the short-range length scale of the interaction. If this potential is repulsive, it can lead to a decrease in the total cross section, resulting in an enhancement of the neutrino density. For attractive potentials, substantial Sommerfeld enhancement can appear.

Carcamo, Dante; Gamboa, Jorge; Mendez, Fernando; Polychronakos, Alexios P

2014-01-01

318

Measurements of multiphoton action cross sections for multiphoton microscopy  

PubMed Central

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

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

2014-01-01

319

Total cross section of electron scattering by fluorocarbon molecules  

NASA Astrophysics Data System (ADS)

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

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

2008-12-01

320

Light ray tracing through a leaf cross section  

NASA Technical Reports Server (NTRS)

A light ray, incident at about 5 deg to the normal, is geometrically plotted through the drawing of the cross section of a soybean leaf using Fresnel's equations and Snell's law. The optical mediums of the leaf considered for ray tracing are: air, cell sap, chloroplast, and cell wall. The ray is also drawn through the same leaf cross section with cell wall and air as the only optical mediums. The values of the reflection and transmission found from the ray tracing tests agree closely with the experimental results obtained using a Beckman Dk-2A Spectroreflector.

Kumar, R.; Silva, L. F.

1973-01-01

321

Inclusive jet cross section measurement at D0  

SciTech Connect

We present a new preliminary measurement of the inclusive jet cross section in p{bar p} collisions based on a integrated luminosity of about 0.8 fb{sup -1}. The data were acquired using the D0 detector between 2002 and 2005. Jets are reconstructed using an iterative cone algorithm with radius R{sub cone} = 0.7. The inclusive jet cross section is presented as a function of transverse jet momentum and rapidity. Predictions from perturbative QCD in next-to-leading order, plus threshold corrections in 2-loop accuracy describe the shape in the transverse jet momentum.

Voutilainen, M.; /Nebraska U. /Helsinki Inst. of Phys.

2006-09-01

322

55. CROSS SECTION OF POWER HOUSE, EXHIBIT L, SANTA ANA ...  

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

55. CROSS SECTION OF POWER HOUSE, EXHIBIT L, SANTA ANA RIVER NO. 1 PROJECT, APR. 30, 1945. SCE drawing no. 523199 (sheet no. 9, for filing with Federal Power Commission). - Santa Ana River Hydroelectric System, SAR-1 Powerhouse, Redlands, San Bernardino County, CA

323

Electrogravitational conversion cross sections in static electromagnetic fields  

Microsoft Academic Search

We use Feynman perturbation techniques to analyze a classical process: the conversion of gravitational waves into electromagnetic waves (and vice versa) under the 'catalytic' action of a static electromagnetic background field. Closed-form differential cross sections are presented for conversion in the Coulomb field of a point charge, electric and magnetic dipole fields, and uniform electrostatic and magnetostatic fields. Using the

W. K. de Logi; A. R. Mickelson

1977-01-01

324

Econometric Analysis of Cross Section and Panel Data  

Microsoft Academic Search

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

Jeffrey M. Wooldridge

2002-01-01

325

Soda Lake Well Lithology Data and Geologic Cross-Sections  

SciTech Connect

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

James E. Faulds

2013-12-31

326

XCOM: Photon cross sections on a personal computer  

Microsoft Academic Search

A computer program and data base are presented which can be used to calculate, with a personal computer, 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.

M. J. Berger; J. H. Hubbell

1987-01-01

327

Phenomenology of SIDIS unpolarized cross sections and azimuthal asymmetries  

E-print Network

I review the phenomenology of unpolarized cross sections and azimuthal asymmetries in semi-inclusive deeply inelastic scattering (SIDIS). The general theoretical framework is presented and the validity of the Gaussian model is discussed. A brief account of the existing analyses is provided.

Vincenzo Barone

2012-03-28

328

EXPERIMENTAL PROTOCOL FOR DETERMINING ABSORPTION CROSS SECTIONS OF ORGANIC COMPOUNDS  

EPA Science Inventory

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

329

Absolute cross sections for elastic electron scattering from 3-hydroxytetrahydrofuran  

NASA Astrophysics Data System (ADS)

The results of measurements and calculations of absolute cross sections for elastic electron scattering from the 3-hydroxytetrahydrofuran (3hTHF) (C4H8O2) molecule are reported. The measurements were performed using a crossed beam experimental setup, for an incident electron energy range of 40 300 eV and an overall scattering angle range of 10° 110°. Relative differential cross sections (DCSs) were measured both as a function of the angle and the incident energy and the absolute DCSs were determined using the relative flow technique. The calculations of molecular cross sections are based on a corrected form of the independent-atom method, known as the screen corrected additivity rule (SCAR) procedure and using an improved quasifree absorption model. Additional calculations are also done to investigate the influence of rotational excitations and low-angular behavior of SCAR DCSs. The calculated dataset includes differential, integral and total cross sections in the energy range from 5 eV to 10 000 eV. The present results are discussed regarding the most recent low-energy elastic DCSs for 3hTHF (Vizcaino et al 2008 New J. Phys. 10 053002), as well as the recent DCSs for molecules of similar structure (tetrahydrofuran and tetrahydrofurfuryl alcohol).

Milosavljevi?, A. R.; Blanco, F.; Maljkovi?, J. B.; Ševi?, D.; García, G.; Marinkovi?, B. P.

2008-10-01

330

Learning of Cross-Sectional Anatomy Using Clay Models  

NSDL National Science Digital Library

This article describes the effect of adding clay modeling to a gross anatomy and neuro anatomy course. The purpose of adding the clay modeling was to assist students with gaining a greater understanding of cross sectional anatomy and to compare these models to CT and MRI scans. Outcomes of the positive effect of clay modeling are explained.

2009-07-27

331

Cross Sections: No 6 Hold Section at Fr 178 Looking ...  

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

Cross Sections: No 6 Hold Section at Fr 178 Looking Fwd, No 7 Hold Section at No 154 Looking Fwd, No 7 Hold Section at Fr 195 Looking Fwd Showing Trans 194, No 7 Hold Section at Fr 198 Looking Fwd - General John Pope, Suisun Bay Reserve Fleet, Benicia, Solano County, CA

332

Cross Sections: No. 1 Hold section at Fr 24 Looking ...  

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

Cross Sections: No. 1 Hold section at Fr 24 Looking Fwd, No 1 Hold Section at Fr 28 Looking Aft, No 2 Hold Section at Fr 48 Looking Aft, No 3 Hold Section at Fr 70 Looking Aft, No 4 Hold Section at Fr 90 Looking Aft - General John Pope, Suisun Bay Reserve Fleet, Benicia, Solano County, CA

333

Scattering by a dielectric cylinder of arbitrary cross section shape  

Microsoft Academic Search

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

JACK H. RICHMOND

1965-01-01

334

Stellar neutron capture cross sections of the Lu isotopes  

NASA Astrophysics Data System (ADS)

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

Wisshak, K.; Voss, F.; Käppeler, F.; Kazakov, L.

2006-01-01

335

Stellar neutron capture cross sections of the tin isotopes.  

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of 114Sn, 115Sn, 116Sn, 117Sn, 118Sn, and 120Sn were measured in the enrgy range from 3 to 225 keV at the Karlsruhe 3.75 MV Van de Graaff accelerator. Neutrons were produced via the 7Li(p, n)7Be reaction by bombarding metallic Li targets with a pulsed proton beam. Capture events were registered with the Karlsruhe 4? Barium Fluoride Detector, which was improved by replacing crystals with high ? background. This allowed to lower the threshold in sum energy and resulted in a significantly increased efficiency for capture events. The experiment was difficult due to the small (n, ?) cross sections of the proton magic tin isotopes, and due to the comparably low enrichment of the rare isotopes 114Sn and 115Sn. This caused significant corrections for capture of scattered neutrons and for isotopic impurities, but the high efficiency and the spectroscopic quality of the BaF2 detector allowed to determine these corrections reliably. Typical overall uncertainties of 1 - 2% could be achieved for the cross section ratios, five times smaller compared to existing data. Based on these results, Maxwellian averaged (n, ?) cross sections were calculated for thermal energies between kT = 10 keV and 100 keV.

Wisshak, K.; Voss, F.; Theis, C.; Käppeler, F.; Guber, K.; Kazakov, L.; Kornilov, N.; Reffo, G.

1995-08-01

336

Stellar neutron capture cross sections of the tin isotopes  

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of 114Sn, 115Sn, 116Sn, 117Sn, 118Sn, and 120Sn were measured in the energy range from 3 to 225 keV at the Karlsruhe 3.75 MV Van de Graaff accelerator. Neutrons were produced via the 7Li(p,n)7Be reaction using a pulsed proton beam. Capture events were registered with the Karlsruhe 4? barium fluoride detector. The experiment was complicated by the small (n,?) cross sections of the proton magic tin isotopes and by the comparably low enrichment of the rare isotopes 114Sn and 115Sn. Despite significant corrections for capture of scattered neutrons and for isotopic impurities, the high efficiency and the spectroscopic quality of the BaF2 detector allowed the determination of the cross-section ratios with overall uncertainties of 1-2 %, five times smaller compared to existing data. Based on these results, Maxwellian averaged (n,?) cross sections were calculated for thermal energies between kT=10 and 100 keV. These data are used for a discussion of the solar tin abundance and for an improved determination of the isotopic s- and r-process components.

Wisshak, K.; Voss, F.; Theis, Ch.; Käppeler, F.; Guber, K.; Kazakov, L.; Kornilov, N.; Reffo, G.

1996-09-01

337

Neutron capture cross sections for stellar Cd production  

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of 110Cd, 111Cd, 112Cd, 113Cd, 114Cd, and 116Cd have been measured in the energy range from 3 to 225 keV at the Karlsruhe 3.75 MV Van de Graaff accelerator. Neutrons were produced via the 7Li(p,n)7Be reaction by bombarding metallic Li targets with a pulsed proton beam. The Karlsruhe 4? barium fluoride detector was used for registration of capture events. The cross sections were determined relative to the gold standard using highly enriched metallic Cd samples. The respective ratios could be obtained with overall uncertainties between 0.8% and 1.6%, about an order of magnitude more accurate than previous data. Maxwellian averaged neutron capture cross sections were calculated for thermal energies between kT=8 keV and 100 keV. Discrepancies of 30% to 40% were found with respect to previous data. The new cross sections provide a reliable definition of the s-abundance pattern of the Cd isotopes, thus improving the corresponding r-process residuals, and, most importantly, the impact of s-only 110Cd as a normalization point for the overall distribution of the s abundances.

Wisshak, K.; Voss, F.; Käppeler, F.; Kazakov, L.

2002-08-01

338

Applications of cross sections for electron-molecule collision processes  

SciTech Connect

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

Cartwright, D.C.

1985-01-01

339

Lava flow in tubes with elliptical cross sections  

Microsoft Academic Search

We develop a model of lava flow in a cylindrical tube with elliptical cross section. The lava is considered an isothermal, incompressible Newtonian fluid. We solve analytically the steady-state Navier–Stokes equation under a constant driving force, given by the component of gravity along the axis of the tube and obtain the velocity and stress field components in the fluid. The

Michele Dragoni; Stefano Santini

2007-01-01

340

Correlations in the scattering cross section of regular systems  

Microsoft Academic Search

Recently, several authors recognized and discussed the fact that regular closed quantum systems, i.e., systems which do not show correlations in their level spectrum, are nevertheless likely to exhibit correlations in the scattering cross section if they are coupled with sufficient strength to decay channels. In this paper a new averaging method is developed, especially designed to deal with S-

T. Gorin

1999-01-01

341

Measurement of extinction cross section by high spectral resolution lidar  

Microsoft Academic Search

A high-spectral-resolution lidar (HSRL) designed to overcome the problems involved in assessing visibility and measuring aerosol optical properties by interferometrically separating the backscatter return into a component due to aerosol scattering and a component due to scattering from air molecules is presented. A graph is provided to show the extinction cross section measured by the HSRL averaged over a 2-km

Christian J. Grund; Edwin W. Eloranta

1991-01-01

342

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

E-print Network

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

Taylor, Frank E.

343

Stellar neutron capture cross sections of the tin isotopes  

SciTech Connect

The neutron capture cross sections of {sup 114}Sn, {sup 115}Sn, {sup 116}Sn, {sup 117}Sn, {sup 118}Sn, and {sup 120}Sn were measured in the energy range from 3 to 225 keV at the Karlsruhe 3.75 MV Van de Graaff accelerator. Neutrons were produced via the {sup 7}Li({ital p},{ital n}){sup 7}Be reaction using a pulsed proton beam. Capture events were registered with the Karlsruhe 4{pi} barium fluoride detector. The experiment was complicated by the small ({ital n},{gamma}) cross sections of the proton magic tin isotopes and by the comparably low enrichment of the rare isotopes {sup 114}Sn and {sup 115}Sn. Despite significant corrections for capture of scattered neutrons and for isotopic impurities, the high efficiency and the spectroscopic quality of the BaF{sub 2} detector allowed the determination of the cross-section ratios with overall uncertainties of 1{endash}2{percent}, five times smaller compared to existing data. Based on these results, Maxwellian averaged ({ital n},{gamma}) cross sections were calculated for thermal energies between {ital kT}=10 and 100 keV. These data are used for a discussion of the solar tin abundance and for an improved determination of the isotopic {ital s}- and {ital r}-process components. {copyright} {ital 1996 The American Physical Society.}

Wisshak, K.; Voss, F.; Theis, C.; Kaeppeler, F. [Forschungszentrum Karlsruhe, Institut fuer Kernphysik, Postfach 3640, D-76021 Karlsruhe (Germany)] [Forschungszentrum Karlsruhe, Institut fuer Kernphysik, Postfach 3640, D-76021 Karlsruhe (Germany); Guber, K. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)] [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Kazakov, L.; Kornilov, N. [Institute for Physics and Power Engineering, Obninsk, Kaluga Region (Russia)] [Institute for Physics and Power Engineering, Obninsk, Kaluga Region (Russia); Reffo, G. [Comitato Nazionale per la Ricerca e per lo Sviluppo dell`Energia Nucleare e delle Energia Alternative, Centro Dati Nucleari, Via Martiri di Monte Sole 4, I-40138 Bologna (Italy)] [Comitato Nazionale per la Ricerca e per lo Sviluppo dell`Energia Nucleare e delle Energia Alternative, Centro Dati Nucleari, Via Martiri di Monte Sole 4, I-40138 Bologna (Italy)

1996-09-01

344

Optimization of negative central shear discharges in shaped cross sections  

Microsoft Academic Search

Magnetohydrodynamic (MHD) stability analyses of Negative Central Shear (NCS) equilibria have revealed a new understanding of the limiting MHD instabilities in NCS experiments. Ideal stability calculations show a synergistic effect between cross section shape and pressure profile optimization; strong shaping and broader pressure independently lead to moderately higher Î limits, but broadening of the pressure profile in a strongly dee-shaped

A. D. Turnbull; M. S. Chu; T. S. Taylor; T. A. Casper; B. W. Rice; J. M. Greene; C. M. Greenfield; R. J. La Haye; L. L. Lao; B. J. Lee; R. L. Miller; C. L. RETTIG; E. J. Strait; K. Tritz; T. L. Rhodes; O. Sauter

1996-01-01

345

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

E-print Network

Nuclear Science and Technology, November 2000. 1 NEUTRON CROSS SECTION EVALUATIONS FOR 238 U UP and Power Engineering, 249020 Obninsk, Russia A.Ventura ENEA, Nuclear Data Center and INFN, Bologna Section of the statistical description that includes direct, pre-equilibrium and equilibrium mechanisms of nuclear reactions

346

XCOM: Photon cross sections on a personal computer  

SciTech Connect

A computer program and data base are presented which can be used to calculate, with a personal computer, 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.

Berger, M.J.; Hubbell, J.H.

1987-07-01

347

Photoabsorption cross section of OD at 115-180 nm  

NASA Technical Reports Server (NTRS)

The photoabsorption cross sections of OD in the 115-180 nm region were measured. The OD radicals were produced from a pulsed discharge in a mixture containing a trace of D2O in a few Torr of argon. Results are compared with the photoabsorption of OH previously measured.

Nee, J. B.; Lee, L. C.

1984-01-01

348

Photoabsorption cross sections at superhigh energies of real photons  

E-print Network

The brief review of modern theoretical models describing the process of the photon absorption by nucleons at superhigh energies of real photons is given. The main aim of the work is an estimation of the theoretical uncertainty of the cross section prediction at photon energies around 10^19-10^20 eV.

E. V. Bugaev

2006-12-01

349

Photoabsorption cross sections at superhigh energies of real photons  

E-print Network

The brief review of modern theoretical models describing the process of the photon absorption by nucleons at superhigh energies of real photons is given. The main aim of the work is an estimation of the theoretical uncertainty of the cross section prediction at photon energies around 10^19-10^20 eV.

Bugaev, E V

2006-01-01

350

Analysis of Cylindrical Waveguides of General Cross-Section  

Microsoft Academic Search

This paper describes a novel method for the analysis of waveguides of general cross-section. In this approach the field inside the waveguide is expanded in terms of cylindrical wave functions. The field is then subjected to the pertinent boundary conditions via an integral formulation. This procedure leads to a homogeneous system of linear equations from which both the cut-off frequencies

E. Kuhn

1985-01-01

351

Accurate transport cross sections for the Lennard-Jones potential  

NASA Astrophysics Data System (ADS)

Physically motivated expressions for the transport cross sections describing classical scattering in the Lennard-Jones potential are proposed. These expressions, which agree with the numerical results better than to within ± 1%, can be easy implemented in practical situations. Some relevant examples are provided.

Khrapak, Sergey A.

2014-10-01

352

RZ calculations for self shielded multigroup cross sections  

SciTech Connect

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

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

2006-07-01

353

Atlas of Photoneutron Cross Sections Obtained with Monoenergetic Photons.  

National Technical Information Service (NTIS)

The data included in this supplement replace earlier preliminary results presented in the Bicentennial Edition of the Atlas of Photoneutron Cross Sections (UCRL-78482, 1976). The nuclei included are exp 13 C, exp 18 O, exp 55 Mn, exp 59 Co, exp 186 exp 18...

B. L. Berman

1979-01-01

354

Linear system identification from nonstationary cross-sectional data  

Microsoft Academic Search

The identification of time-invariant linear stochastic systems from cross-sectional data on nonstationary system behavior is considered. A strong consistency and asymptotic normality result for maximum likelihood and prediction error estimates of the system parameters, system and measurement noise covariances, and the initial state covariance is proven. A new tdentifiability property for the system model is defined and appears in the

ROBERT L. GOODRICH; PETER E. CAINES

1979-01-01

355

Quality at general practice consultations: cross sectional survey  

Microsoft Academic Search

Objectives To measure quality of care at general practice consultations in diverse geographical areas, and to determine the principal correlates associated with enablement as an outcome measure. Design Cross sectional multipractice questionnaire based study. Setting Random sample of practices in four participating regions: Lothian, Coventry, Oxfordshire,

John G R Howie; David J Heaney; Margaret Maxwell; Jeremy J Walker; George K Freeman; Harbinder Rai

1999-01-01

356

Cross-section Polisher CP, 22 FIB-SEM  

E-print Network

1. (SOFC) SOFC Redox (1)(7) FIB-SEM 3 (7) 3 (8) 2. 3 21 (YSZ) (9) , , , 12 Cross-section Polisher CP, YSZ , TED PELLA 22 FIB-SEM 1 FIB-SEM(Carl Zeiss, NVision 40) FIB SEM In-lens SE, 3000 , 1.5-2.0kV SEM 36°, , SEM SOFC Numerical simulation of SOFC

Tokyo, University of

357

Differential cross sections for modeling of noble gas plasmas  

Microsoft Academic Search

Differential cross sections are required to model the 3D diffusion of electrons in a gas under the influence of electromagnetic fields. In a low temperature plasma containing a noble gas elastic scattering from the neutral atoms is an important process governing this diffusion even at energies above the inelastic thresholds. We have calculated the phase shifts at such energies using

Allan Stauffer; Robert McEachran

2009-01-01

358

Propagation of sound waves in tubes of noncircular cross section  

NASA Technical Reports Server (NTRS)

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

Richards, W. B.

1986-01-01

359

Neutron capture cross section of {sup 241}Am  

SciTech Connect

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

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

2008-09-15

360

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

ERIC Educational Resources Information Center

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

Shrout, Patrick E.

2011-01-01

361

Elastic cross sections for high energy hadron-hadron scattering  

E-print Network

This report discusses some results on differential cross sections for high energy and small momentum transfer elastic hadron-hadron scattering in QCD, using a functional integral approach. In particulary a matrix cumulant expansion for the vacuum expectation values of lightlike Wegner-Wilson loops, which governs the hadronic amplitudes, is presented. The cumulants are evaluated using the model of the stochastic vacuum.

E. R. Berger

1998-11-11

362

Histomorphometry of spherical tumors using holoptical cross-sections  

Microsoft Academic Search

A new morphometric method for quantifying tumour regression on holoptical cross-sections is described which permits assessment of the extent and distribution of viable tumour tissue and necrosis in spherical tumours. The value of the method is demonstrated by comparing tumour regression in the liver metastases of a colorectal adenocarcinoma before and after regional chemotherapy. The practicability of the method for

Hans-Peter Fischer

1985-01-01

363

Extinction and backscatter cross sections of biological materials  

NASA Astrophysics Data System (ADS)

Aerosol backscatter and extinction cross-sections are required to model and evaluate the performance of both active and passive detection systems. A method has been developed that begins with laboratory measurements of thin films and suspensions of biological material to obtain the complex index refraction of the biological material from the UV to the LWIR. Using that result with particle size distribution and shape information as inputs to T-matrix or discrete dipole approximation (DDA) calculations yields the extinction cross-section and backscatter cross section as a function of wavelength. These are important inputs to the lidar equation. In a continuing effort to provide validated optical cross-sections, measurements have been made on a number of high purity biological species in the laboratory as well as measurements of material released at recent field tests. The resulting observed differences between laboratory and field measurements aid in distinguishing between intrinsic and extrinsic effects, which can affect the characteristic signatures of important biological aerosols. A variety of biological and test aerosols are examined, including Bacillus atrophaeus (BG), and Erwina, ovalbumin, silica and polystyrene.

Thomas, M. E.; Hahn, D. V.; Carr, A. K.; Limsui, D.; Carter, C. C.; Boggs, N. T.; Jackman, J.

2008-04-01

364

Loneliness Predicts Reduced Physical Activity: Cross-Sectional & Longitudinal Analyses  

Microsoft Academic Search

Objective: To determine cross-sectional and prospective associations between loneliness and physical activity, and to evaluate the roles of social control and emotion regulation as mediators of these associations. Design: A population-based sample of 229 White, Black, and Hispanic men and women, age 50 to 68 years at study onset, were tested annually for each of 3 years. Main Outcome Measures:

Louise C. Hawkley; Ronald A. Thisted; John T. Cacioppo

2009-01-01

365

Impact parameter method calculations for fully differential ionization cross sections  

Microsoft Academic Search

In this work, our previous fully differential ionization cross section calculations using the semiclassical, impact parameter method are improved by a new method suitable to calculate impact parameter values corresponding to different momentum transfers. This goal is achieved by two successive steps. First, using the transverse momentum balance different projectile scattering angles are calculated for the binary and recoil peak

F. Járai-Szabó; L. Nagy

2009-01-01

366

Fusion cross-sections for inertial fusion energy  

Microsoft Academic Search

The application of selective resonant tunneling model is extended from d 1 t fusion to other light nucleus fusion reactions, such as d 1 d fusion and d 1 3 He. In contrast to traditional formulas, the new formula for the cross-section needs only a few parameters to fit the experimental data in the energy range of interest. The features

XING ZHONG LI; BIN LIU; SI CHEN; QING MING WEI; HEINRICH HORA

2004-01-01

367

Absolute photoionization cross-section of the methyl radical.  

SciTech Connect

The absolute photoionization cross-section of the methyl radical has been measured using two completely independent methods. The CH{sub 3} photoionization cross-section was determined relative to that of acetone and methyl vinyl ketone at photon energies of 10.2 and 11.0 eV by using a pulsed laser-photolysis/time-resolved synchrotron photoionization mass spectrometry method. The time-resolved depletion of the acetone or methyl vinyl ketone precursor and the production of methyl radicals following 193 nm photolysis are monitored simultaneously by using time-resolved synchrotron photoionization mass spectrometry. Comparison of the initial methyl signal with the decrease in precursor signal, in combination with previously measured absolute photoionization cross-sections of the precursors, yields the absolute photoionization cross-section of the methyl radical; {sigma}{sub CH}(10.2 eV) = (5.7 {+-} 0.9) x 10{sup -18} cm{sup 2} and {sigma}{sub CH{sub 3}}(11.0 eV) = (6.0 {+-} 2.0) x 10{sup -18} cm{sup 2}. The photoionization cross-section for vinyl radical determined by photolysis of methyl vinyl ketone is in good agreement with previous measurements. The methyl radical photoionization cross-section was also independently measured relative to that of the iodine atom by comparison of ionization signals from CH{sub 3} and I fragments following 266 nm photolysis of methyl iodide in a molecular-beam ion-imaging apparatus. These measurements gave a cross-section of (5.4 {+-} 2.0) x 10{sup -18} cm{sup 2} at 10.460 eV, (5.5 {+-} 2.0) x 10{sup -18} cm{sup 2} at 10.466 eV, and (4.9 {+-} 2.0) x 10{sup -18} cm{sup 2} at 10.471 eV. The measurements allow relative photoionization efficiency spectra of methyl radical to be placed on an absolute scale and will facilitate quantitative measurements of methyl concentrations by photoionization mass spectrometry.

Taatjes, C. A.; Osborn, D. L.; Selby, T.; Meloni, G.; Fan, H.; Pratt, S. T.; Chemical Sciences and Engineering Division; SNL

2008-01-01

368

Thermal neutron capture cross sections of the potassium isotopes  

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

369

Stellar neutron capture cross sections of the Nd isotopes  

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of 142Nd, 143Nd, 144Nd, 145Nd, 146Nd, and 148Nd have been measured in the energy range from 3 to 225 keV at the Karlsruhe 3.75 MV Van de Graaff accelerator. Neutrons were produced via the 7Li(p,n)7Be reaction by bombarding metallic Li targets with a pulsed proton beam. Capture events were registered with the Karlsruhe 4? Barium Fluoride Detector. The cross sections were determined relative to the gold standard. The experiment was difficult due to the small cross sections of the even isotopes at or near the magic neutron number N=82, and also since the isotopic enrichment of some samples was comparably low. The necessary corrections for capture of scattered neutrons and for isotopic impurities could be determined reliably thanks to the high efficiency and the spectroscopic quality of the BaF2 detector, resulting in a consistent set of (n,?) cross sections for the six stable neodymium isotopes involved in the s process with typical uncertainties of 1.5-2 %. From these data, Maxwellian averaged cross sections were calculated between kT=10 and 100 keV. The astrophysical implications of these results were investigated in an s-process analysis, which deals with the role of the s-only isotope 142Nd for the Ns systematics near the magic neutron number N=82, the decomposition of the Nd abundances into the respective r-, s-, and p-process components, and the interpretation of isotopic anomalies in meteoritic material.

Wisshak, K.; Voss, F.; Käppeler, F.; Kazakov, L.; Reffo, G.

1998-01-01

370

Thermal Neutron Capture Cross Sections of the PalladiumIsotopes  

SciTech Connect

Precise gamma-ray thermal neutron capture cross sectionshave been measured at the Budapest Reactor for all elements withZ=1-83,92 except for He and Pm. These measurements and additional datafrom the literature been compiled to generate the Evaluated Gamma-rayActivation File (EGAF), which is disseminated by LBNL and the IAEA. Thesedata are nearly complete for most isotopes with Z<20 so the totalradiative thermal neutron capture cross sections can be determineddirectly from the decay scheme. For light isotopes agreement with therecommended values is generally satisfactory although large discrepanciesexist for 11B, 12,13C, 15N, 28,30Si, 34S, 37Cl, and 40,41K. Neutroncapture decay data for heavier isotopes are typically incomplete due tothe contribution of unresolved continuum transitions so only partialradiative thermal neutron capture cross sections can be determined. Thecontribution of the continuum to theneutron capture decay scheme arisesfrom a large number of unresolved levels and transitions and can becalculated by assuming that the fluctuations in level densities andtransition probabilities are statistical. We have calculated thecontinuum contribution to neutron capture decay for the palladiumisotopes with the Monte Carlo code DICEBOX. These calculations werenormalized to the experimental cross sections deexciting low excitationlevels to determine the total radiative thermal neutron capture crosssection. The resulting palladium cross sections values were determinedwith a precision comparable to the recommended values even when only onegamma-ray cross section was measured. The calculated and experimentallevel feedings could also be compared to determine spin and parityassignments for low-lying levels.

Firestone, R.B.; Krticka, M.; McNabb, D.P.; Sleaford, B.; Agvaanluvsan, U.; Belgya, T.; Revay, Zs.

2006-07-17

371

Fusion, reaction, and breakup cross sections of {sup 9}Be on a light mass target  

SciTech Connect

The total fusion cross section for the {sup 9}Be+{sup 27}Al system has been measured at energies close and above the Coulomb barrier. Reaction cross sections for this system were derived from elastic scattering data, and the breakup-plus-transfer-channel cross sections were estimated from the difference between these data and measured cross-section fusion.

Marti, G.V.; Capurro, O.A.; Pacheco, A.J.; Testoni, J.E.; Ramirez, M.; Arazi, A. [Laboratorio Tandar, Departamento de Fisica, Comision Nacional de Energia Atomica, Av. del Libertador 8250 (1419), Buenos Aires (Argentina); Gomes, P.R.S.; Padron, I.; Anjos, R.M.; Lubian, J. [Instituto de Fisica, Universidade Federal Fluminense, Av. Litoranea, s/n, Gragota, Niteroi, R.J., 24210-340 (Brazil); Rodriguez, M.D.; Niello, J.O. Fernandez [Laboratorio Tandar, Departamento de Fisica, Comision Nacional de Energia Atomica, Av. del Libertador 8250 (1419), Buenos Aires (Argentina); Escuela de Ciencia y Tecnologia, Universidad de Gral, San Martin (Argentina); Crema, E. [Departamento de Fisica Nuclear, Universidade de Sao Paulo, Caixa Postal 66318, 05315-970, Sao Paulo, S.P. (Brazil)

2005-02-01

372

Evaluation of Neutron Resonance Cross Section Data at GELINA  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

373

Improved neutron capture cross section of Pu239  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

374

Vibrationally resolved K-shell photoionization cross sections of methane  

NASA Astrophysics Data System (ADS)

We use an extension of the static-exchange density functional theory (DFT) method, previously reported in [E. Plésiat et al., Phys. Rev. A 2, 023409 (2012), E. Plésiat, P. Decleva, F. Martín, Phys. Chem. Chem. Phys. 31, 10853 (2012)], to evaluate vibrationally resolved (total and angular) K-shell photoelectron cross sections of methane. The calculated cross sections are in very good agreement with the existing experimental measurements at low photoelectron energies. We show that, in contrast with the rich interference patterns previously observed in molecular frame C(1s) photoelectron angular distributions of methane at both low and high photoelectron energy, no interference effects are observed in the calculated ? parameters, even at high photon energies.

Plésiat, Etienne; Decleva, Piero; Martín, Fernando

2013-09-01

375

Fast-neutron scattering cross sections of elemental silver  

SciTech Connect

Differential neutron elastic- and inelastic-scattering cross sections of elemental silver are measured from 1.5 to 4.0 MeV at intervals of less than or equal to 200 keV and at 10 to 20 scattering angles distributed between 20 and 160/sup 0/. Inelastically-scattered neutron groups are observed corresponding to the excitation of levels at; 328 +- 13, 419 +- 50, 748 +- 25, 908 +- 26, 1150 +- 38, 1286 +- 25, 1507 +- 20, 1623 +- 30, 1835 +- 20 and 1944 +- 26 keV. The experimental results are used to derive an optical-statistical model that provides a good description of the observed cross sections. The measured values are compared with corresponding quantities given in ENDF/B-V.

Smith, A.B.; Guenther, P.T.

1982-05-01

376

Improved activation cross sections for vanadium and titanium  

SciTech Connect

Vanadium alloys such as V-20Ti and V-Cr-Ti are attractive candidates for use as structural materials in fusion-reactor blankets. The virtual absence of long-lived activation products in these alloys suggest the possibility of reprocessing on an intermediate time scale. We have employed the modern Hauser-Feshbach nuclear-model code GNASH to calculate cross sections for neutron-activation reactions in /sup 50/V and /sup 51/V, to allow a more accurate assessment of induced radioactivity in vanadium alloys. In addition, cross sections are calculated for the reactions /sup 46/Ti(n,2n) and /sup 45/Ti(n,2n) in order to estimate the production of /sup 44/Ti, a 1.2-MeV gamma-ray source with a half-life of 47 years.

Muir, D.W.; Arthur, E.D.

1983-01-01

377

The O(+) 834-A dayglow: Revised cross sections  

NASA Technical Reports Server (NTRS)

This study assesses the impact of new O((sup 3)P) photoionization and N2 photoabsorption cross sections, and O(+) oscillator strengths and transition probabilities, on O II 834-A airglow calculations. The 834-A intensities computed using the new emission parameters are in good agreement with rocket measurements obtained in 1978 and 1980. The present study does not support a suggested reduction in the N2 photoabsorption cross section based on an earlier analysis of the rocket data. This study also explores the problem of determining F region electron densities from satellite limb scans of the O(+) 834-A emission. Our results indicate that electron density profiles inferred from limb scans are not necessarily unique; estimates of N(sub m)F(sub 2) and h(sub m)F(sub 2) can vary by at least a factor of 2 and 50 km, respectively.

Link, R.; Evans, J. S.; Gladstone, G. R.

1994-01-01

378

Cross section measurement of the ?-p? ?-?+n reaction near threshold  

NASA Astrophysics Data System (ADS)

Result of cross section measurements for the reaction ?-p? ?-?+n are presented. They cover a range of incident pion momenta between 295 and 450 MeV/ c. It is the first time that the cross section has been measured so close to threshold. The experiment was performed with Omicron, a large-solid-angle spectrometer, which enables a measurement of the full set of kinematic variables. In the region of overlap there is a good agreement with other experiments. The extracted value for the chiral-symmetry-breaking parameter ? is seen to be largely extrapolition dependent but the measured value of -0.5±0.8 leaves Weinberg's prediction of ?=0 the only remaining choice.

Kernel, G.; Korbar, D.; Križan, P.; Mikuž, M.; Sever, F.; Stanovnik, A.; Stari?, M.; Zavrtanik, D.; van Eijk, C. W. E.; Hollander, R. W.; Lourens, W.; Michaelis, E. G.; Tanner, N. W.; Clark, S. A.; Jovanovich, J.; Davies, J. D.; Lowe, J.; Playfer, S. M.; Omicron Collaboration

1989-01-01

379

Probing neutron-skin thickness with total reaction cross sections  

E-print Network

We analyze total reaction cross sections, $\\sigma_R$, for exploring their sensitivity to the neutron-skin thickness of nuclei. We cover 91 nuclei of O, Ne, Mg, Si, S, Ca, and Ni isotopes. The cross sections are calculated in the Glauber theory using the density distributions obtained with the Skyrme-Hartree-Fock method in 3-dimensional coordinate space. Defining a reaction radius, $a_R=\\sqrt{\\sigma_R/\\pi}$, to characterize the nuclear size and target (proton or $^{12}$C) dependence, we find an empirical formula for expressing $a_R$ with the point matter radius and the skin thickness, and assess two practical ways of determining the skin thickness from proton-nucleus $\\sigma_R$ values measured at different energies or from $\\sigma_R$ values measured for different targets.

W. Horiuchi; Y. Suzuki; T. Inakura

2014-01-08

380

Electron impact excitation cross sections of N2  

NASA Astrophysics Data System (ADS)

Differential cross sections (DCSs) are presented for electron impact excitation of the C3?u, E3?+g, and a'' 1?+g states in N2 from the ground state. Vibrationally-resolved DCSs are also presented for excitation of the C 3?? (?') state, where ?' = 0-4. The DCSs were obtained from measurements of energy-loss spectra in the region of 10.75 eV to 12.75 eV measured at numerous incident energies between 13 eV and 100 eV, and for scattering angles ranging from 5° to 130°. Relative excitation probabilities for the vibrational levels of the C 3?u state are shown to demonstrate non-Franck-Condon behavior for excitation energies less than approximately 50 eV. Integral cross sections are also presented for these excitation processes. These results are compared with existing measurements.

Malone, C. P.; Johnson, P. V.; Young, J. A.; Kanik, I.; Ajdari, B.; Khakoo, M. A.

2009-11-01

381

Neutron Capture Cross Sections of 236U and 234U  

SciTech Connect

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

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

2006-03-13

382

Photoionization of the Be isoelectronic sequence: total cross sections  

NASA Astrophysics Data System (ADS)

The photoionization of the four-electron beryllium-like isoelectronic series from the neutral to Fe+22 has been studied for ground 1S and metastable 3P initial states. The wavefunctions of the final-state (target) ions were built using the CIV3 code. Both nonrelativistic LS-coupling R-matrix and relativistic Breit-Pauli (BP) R-matrix methods were used to calculate the cross sections in the photon-energy range between the first ionization threshold and the 1s24f7/2 threshold for each ion. Our total cross sections compare well with experiment which is available for Be, B+, C+2, N+3 and O+4. The agreement between the present work and previous calculations is discussed in detail. The importance of relativistic effects is seen by the comparison between the LS and the BP results.

Chu, W.-C.; Zhou, H.-L.; Hibbert, A.; Manson, S. T.

2009-10-01

383

Generalized x-ray scattering cross section from nonequilibrium plasmas  

SciTech Connect

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

Gregori, G.; Glenzer, S. H.; Landen, O. L. [CCLRC, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, Great Britain and Clarendon Laboratory, University of Oxford, Parks Road, Oxford, OX1 3PU, Great Britain (United Kingdom); Lawrence Livermore National Laboratory, University of California, P.O. Box 808, California 94551 (United States)

2006-08-15

384

Calculation of the Cross Section for Top Quark Production  

E-print Network

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

Edmond L. Berger; Harry Contopanagos

1996-06-24

385

Black Hole Cross Section at the Large Hadron Collider  

Microsoft Academic Search

Black hole production at the Large Hadron Collider (LHC) was first discussed\\u000ain 1999. Since then, much work has been performed in predicting the black hole\\u000across section. In light of the start up of the LHC, it is now timely to review\\u000athe state of these calculations. We review the uncertainties in estimating the\\u000ablack hole cross section in

Douglas M. Gingrich

2006-01-01

386

Measurement of 139La(n,?) Cross Section  

Microsoft Academic Search

We measured the neutron capture cross section of 139La relative to 197Au in the energy range of 0.6 eV to 9 keV at n_TOF, the neutron time-of-flight facility at CERN. After a description of the experimental apparatus, we discuss data analysis procedures. The data were fitted using R-matrix formalism to extract resonance parameters which, in turn, were used to calculate

R. Terlizzi; U. Abbondanno; G. Aerts; H. A´lvarez; F. Alvarez-Velarde; S. Andriamonje; J. Andrzejewski; P. Assimakopoulos; L. Audouin; G. Badurek; P. Baumann; E. Berthoumieux; D. Cano-Ott; R. Capote; A. Carrillo de Albornoz; P. Cennini; V. Chepel; E. Chiaveri; N. Colonna; G. Cortes; A. Couture; J. Cox; M. Dahlfors; S. David; I. Dillmann; R. Dolfini; C. Domingo-Pardo; W. Dridi; I. Duran; C. Eleftheriadis; M. Embid-Segura; L. Ferrant; A. Ferrari; R. Ferreira-Marques; L. Fitzpatrick; H. Frais-Koelbl; K. Fujii; W. Furman; R. Gallino; I. Goncalves; E. Gonzalez-Romero; A. Goverdovski; F. Gramegna; E. Griesmayer; C. Guerrero; F. Gunsing; B. Haas; R. Haight; M. Heil; A. Herrera-Martinez; M. Igashira; S. Isaev; E. Jericha; Y. Kadi; D. Karamanis; D. Karadimos; M. Kerveno; V. Ketlerov; P. Koehler; V. Konovalov; E. Kossionides; C. Lamboudis; H. Leeb; A. Lindote; I. Lopes; M. Lozano; S. Lukic; J. Marganiec; L. Marques; S. Marrone; P. Mastinu; A. Mengoni; P. M. Milazzo; C. Moreau; M. Mosconi; F. Neves; H. Oberhummer; S. O’Brien; M. Oshima; J. Pancin; C. Papachristodoulou; C. Papadopoulos; C. Paradela; N. Patronis; A. Pavlik; P. Pavlopoulos; L. Perrot; R. Plag; A. Plompen; A. Plukis; A. Poch; C. Pretel; J. Quesada; T. Rauscher; R. Reifarth; M. Rosetti; C. Rubbia; G. Rudolf; P. Rullhusen; J. Salgado; L. Sarchiapone; I. Savvidis; C. Stephan; G. Tagliente; J. L. Tain; L. Tassan-Got; L. Tavora; G. Vannini; P. Vaz; A. Ventura; D. Villamarin; M. C. Vincente; V. Vlachoudis; R. Vlastou; F. Voss; S. Walter; H. Wendler; M. Wiescher; K. Wisshak

2006-01-01

387

Neutron Capture Cross Sections for the Re\\/Os Clock  

Microsoft Academic Search

The radioactive decay of 187Re --> 187Os (t1\\/2 = 43 Gyr) is suited for dating the onset of heavy-element nucleosynthesis. The radiogenic contribution to the 187Os abundance is the difference between the natural abundance and the corresponding s-process component. This component can be obtained via the well-established sigmaN systematics using the neighboring s-only isotope 186Os, provided the neutron-capture cross sections

M. Mosconi; A. Mengoni; M. Heil; F. Käppeler; G. Aerts; R. Terlizzi; U. Abbondanno; H. Álvarez; F. Alvarez-Velarde; S. Andriamonje; J. Andrzejewski; P. Assimakopoulos; L. Audouin; G. Badurek; P. Baumann; F. Becvár; J. Benlliure; E. Berthoumieux; F. Calviño; D. Cano-Ott; R. Capote; A. Carrillo de Albornoz; P. Cennini; V. Chepel; E. Chiaveri; N. Colonna; G. Cortes; D. Cortina; A. Couture; J. Cox; S. David; R. Dolfini; C. Domingo-Pardo; W. Dridi; I. Duran; M. Embid-Segura; L. Ferrant; A. Ferrari; L. Fitzpatrick; R. Ferreira-Marques; H. Frais-Kölbl; K. Fujii; W. Furman; C. Guerrero; I. Goncalves; R. Gallino; E. Gonzalez-Romero; A. Goverdovski; F. Gramegna; E. Griesmayer; F. Gunsing; B. Haas; R. Haight; A. Herrera-Martinez; M. Igashira; S. Isaev; E. Jericha; Y. Kadi; D. Karamanis; D. Karadimos; M. Kerveno; V. Ketlerov; P. Koehler; V. Konovalov; E. Kossionides; C. Lamboudis; H. Leeb; A. Lindote; I. Lopes; M. Lozano; S. Lukic; J. Marganiec; L. Marques; S. Marrone; P. Mastinu; P. M. Milazzo; C. Moreau; F. Neves; H. Oberhummer; S. O'Brien; M. Oshima; J. Pancin; C. Papachristodoulou; C. Papadopoulos; C. Paradela; N. Patronis; A. Pavlik; P. Pavlopoulos; L. Perrot; R. Plag; A. Plompen; A. Plukis; A. Poch; C. Pretel; J. Quesada; T. Rauscher; R. Reifarth; M. Rosetti; C. Rubbia; G. Rudolf; P. Rullhusen; J. Salgado; L. Sarchiapone; C. Stephan; G. Tagliente; J. L. Tain; L. Tassan-Got; L. Tavora; G. Vannini; P. Vaz; A. Ventura; D. Villamarin; M. C. Vincente; V. Vlachoudis; R. Vlastou; F. Voss; H. Wendler; M. Wiescher

2005-01-01

388

Measurement of 139La(n,gamma) Cross Section  

Microsoft Academic Search

We measured the neutron capture cross section of 139La relative to 197Au in the energy range of 0.6 eV to 9 keV at n_TOF, the neutron time-of-flight facility at CERN. After a description of the experimental apparatus, we discuss data analysis procedures. The data were fitted using R-matrix formalism to extract resonance parameters which, in turn, were used to calculate

R. Terlizzi; U. Abbondanno; G. Aerts; H. Álvarez; F. Alvarez-Velarde; S. Andriamonje; J. Andrzejewski; P. Assimakopoulos; L. Audouin; G. Badurek; P. Baumann; F. Becvár; E. Berthoumieux; F. Calviño; D. Cano-Ott; R. Capote; A. Carrillo de Albornoz; P. Cennini; V. Chepel; E. Chiaveri; N. Colonna; G. Cortes; A. Couture; J. Cox; M. Dahlfors; S. David; I. Dillmann; R. Dolfini; C. Domingo-Pardo; W. Dridi; I. Duran; C. Eleftheriadis; M. Embid-Segura; L. Ferrant; A. Ferrari; R. Ferreira-Marques; L. Fitzpatrick; H. Frais-Koelbl; K. Fujii; W. Furman; R. Gallino; I. Goncalves; E. Gonzalez-Romero; A. Goverdovski; F. Gramegna; E. Griesmayer; C. Guerrero; F. Gunsing; B. Haas; R. Haight; M. Heil; A. Herrera-Martinez; M. Igashira; S. Isaev; E. Jericha; Y. Kadi; F. Käppeler; D. Karamanis; D. Karadimos; M. Kerveno; V. Ketlerov; P. Koehler; V. Konovalov; E. Kossionides; M. Krticka; C. Lamboudis; H. Leeb; A. Lindote; I. Lopes; M. Lozano; S. Lukic; J. Marganiec; L. Marques; S. Marrone; P. Mastinu; A. Mengoni; P. M. Milazzo; C. Moreau; M. Mosconi; F. Neves; H. Oberhummer; S. O'Brien; M. Oshima; J. Pancin; C. Papachristodoulou; C. Papadopoulos; C. Paradela; N. Patronis; A. Pavlik; P. Pavlopoulos; L. Perrot; R. Plag; A. Plompen; A. Plukis; A. Poch; C. Pretel; J. Quesada; T. Rauscher; R. Reifarth; M. Rosetti; C. Rubbia; G. Rudolf; P. Rullhusen; J. Salgado; L. Sarchiapone; I. Savvidis; C. Stephan; G. Tagliente; J. L. Tain; L. Tassan-Got; L. Tavora; G. Vannini; P. Vaz; A. Ventura; D. Villamarin; M. C. Vincente; V. Vlachoudis; R. Vlastou; F. Voss; S. Walter; H. Wendler; M. Wiescher; K. Wisshak

2006-01-01

389

Top quark pair production cross section at the Tevatron  

SciTech Connect

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

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

2008-04-01

390

Cross-section studies of light exotic nuclei  

Microsoft Academic Search

Production cross-sections for some exotic fragments produced in the reaction 40Ar+Be at 1000 MeV\\/nucleon have been studied. These data, together with new available data at higher projectile Z, and with new data for the same reaction at lower energies, allowed a revision of the semi-empirical EPAX formula. A discussion of some of the improvements introduced in this semi-empirical parameterization will

D. Cortina-Gil; K. Suemmerer; T. Baumann; H. Geissel

1998-01-01

391

W and Z production cross sections at D0  

SciTech Connect

We present a measurement of the production cross section times branching ratio for {ital W} and {ital Z} bosons decaying to the electrons or muons in {ital p}{ital {anti p}} collisions at {radical}s = 1.8 TeV using data recorded at the Tevatron during the 1994-1995 collider run. Using the ratio of these two measurements, we derive the {ital W} leptonic branching fraction and the width of the {ital W} boson.

Tarazi, J.N. [California Univ., Irvine, CA (United States). Dept. of Physics and Astronomy; D0 Collaboration

1996-11-01

392

Stellar neutron capture cross sections of the Gd isotopes  

NASA Astrophysics Data System (ADS)

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

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

1995-11-01

393

Stellar neutron capture cross sections of the Gd isotopes.  

NASA Astrophysics Data System (ADS)

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

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

1995-05-01

394

Top-Quark Cross Section and Properties at the Tevatron  

SciTech Connect

At the Tevatron, the collider experiments CDF and D0 have data sets at their disposal that compromise several hundreds of reconstructed top-antitop-quark pairs and allow for precision measurements of the cross section and production and decay properties. Besides comparing the measurements to standard model predictions, these data sets open a window to physics beyond the standard model. Dedicated analyses look for new heavy gauge bosons, fourth generation quarks, and flavor-changing neutral currents.

Wagner, Wolfgang; /Wuppertal U.

2009-09-01

395

Drivers' knowledge, attitudes, and behavior: a cross-sectional study.  

PubMed

A cross-sectional survey was conducted by random duster sampling in the city of Tehran. Knowledge of the drivers was assessed with 6 questions about national traffic laws. Attitude was assessed on a 7-item scale of drivers' perceptions. Behavior was observed by a police officer on 13 areas of assessment. Correlations were low among these three scores. Drivers with advanced education had higher scores on behavior. Knowledge, attitude, and behavior of these drivers did not seem associated. PMID:18567211

Yunesian, Masud; Mesdaghinia, Alireza; Moradi, Ali; Vash, Javad Homayoun

2008-04-01

396

Vessel Cross-Sectional Diameter Measurement on Color Retinal Image  

Microsoft Academic Search

Vessel cross-sectional diameter is an important feature for analyzing retinal vascular changes. In automated retinal image\\u000a analysis, the measurement of vascular width is a complex process as most of the vessels are few pixels wide or suffering from\\u000a lack of contrast. In this paper, we propose a new method to measure the retinal blood vessel diameter which can be used

Alauddin Bhuiyan; Baikunth Nath; Joselíto J. Chua; Ramamohanarao Kotagiri

2008-01-01

397

Isotopic dependence of induced fission cross sections for heavy nuclei  

NASA Astrophysics Data System (ADS)

Using the statistical model, we calculate the induced fission cross sections for the nuclei 211-223Ra in their peripheral collisions with 208Pb. The role of closed shell N = 126 is studied. Level densities of the Fermi-gas model and of the model with collective enhancement are used. Taking into account the particle-hole excitation in addition to the collective Coulomb excitation, we obtain satisfactory agreement with the experimental data.

Zubov, A. S.; Bolgova, O. N.; Adamian, G. G.; Antonenko, N. V.; Scheid, W.

2009-10-01

398

Share issuance and cross-sectional returns: International evidence  

Microsoft Academic Search

Share issuance predicts cross-sectional returns in a non-U.S. sample of stocks from 41 different countries. Issuance predictability has greater statistical significance than either size or momentum, and is similar to book-to-market. As in the U.S., the international issuance effect is robust across both small and large firms. Unlike the U.S., the effect is driven more by low returns after share

R. David McLean; Jeffrey Pontiff; Akiko Watanabe

2009-01-01

399

Vacuum ultraviolet absorption cross sections for halogen containing molecules  

NASA Astrophysics Data System (ADS)

Vacuum ultraviolet absorption cross sections for the compounds Cl2, Br2, I2, HCl, HBr, HI, CCl4, CCl3Br, CF3Br, CF3I, HgCl2, HgBr2, and HgI2 have been measured between 170 and 230 nm. Studies of the Xe*2 discharge lamp used are reported. The absorption bands of various mercuric halides are identified.

Roxlo, C.; Mandl, A.

1980-06-01

400

Cross section of hadron production in ?? collisions at LEP  

Microsoft Academic Search

The reaction e+e? ? e+e????? ? e+e? hadrons is analysed using data collected by the L3 detector during the LEP runs at s = 130?140 GeV and s = 161 GeV. The cross sections ?(e+e? ? e+e? hadrons) and ?(?? ? hadrons) are measured in the interval 5 ? W?? ? 75 GeV. The energy dependence of the ?(?? ?

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; 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; Samuel C. C Ting; S. M Ting; M Tonutti; S. C Tonwar; J Tóth; C Tully; H Tuchscherer; K. L Tung; Y Uchida; J Ulbricht; U Uwer; E Valente; R. T Van de Walle; G Vesztergombi; I Vetlitsky; G Viertel; M Vivargent; R Völkert; H Vogel; H Vogt; I Vorobiev; A. A Vorobyov; A Vorvolakos; M Wadhwa; W Wallraff; J. C Wang; X. L Wang; Z. M Wang; A Weber; F Wittgtenstein; S. X Wu; S Wynhoff; J Xu; Z. Z Xu; B. Z Yang; C. G Yang; X. Y Yao; J. B Ye; S. C Yeh; J. M You; An Zalite; Yu Zalite; P Zemp

1997-01-01

401

Total cross section of two-photon production of hadrons  

Microsoft Academic Search

The total cross section for ???hadrons was measured as a function of the invariant massW of the system (1.25 to 4.25 GeV) at thee+e--collider VEPP-4 with the detector MD-1. For the first time the data were obtained by detecting both scattered leptons with almost zero emission angles. The mean squared four momentum transfer q2> is -0.005 GeV2, the rmsW resolution

S. E. Baru; M. V. Beilin; A. E. Blinov; V. E. Blinov; A. E. Bondar; A. D. Bukin; S. I. Eidelman; Yu. I. Eidelman; V. R. Groshev; V. A. Kiselev; S. G. Klimenko; G. M. Kolachev; S. I. Mishnev; A. P. Onuchin; V. S. Panin; V. V. Petrov; I. Ya. Protopopov; A. G. Shamov; V. A. Sidorov; Yu. I. Skovpen; A. N. Skrinsky; V. A. Tayursky; V. I. Telnov; A. B. Temnykh; Yu. A. Tikhonov; G. M. Tumaikin; A. E. Undrus; A. I. Vorobiov; V. N. Zhilich; A. A. Zholents

1992-01-01

402

Neutron-induced Cross Section Measurements of Calcium  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

403

Differential collision cross-sections for atomic oxygen  

NASA Technical Reports Server (NTRS)

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

Torr, Douglas G.

1991-01-01

404

Inclusive jet cross-section measurement at CDF  

SciTech Connect

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

Norniella, Olga; /Barcelona, IFAE

2007-05-01

405

Top Quark Production Cross Section at the Tevatron  

SciTech Connect

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

Shabalina, E.; /Chicago U.

2006-05-01

406

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

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

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

407

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

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

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

408

Direct photon cross section with conversions at CDF  

Microsoft Academic Search

We present a measurement of the isolated direct photon cross section in pp¯ collisions at &surd;(s)=1.8 TeV and |eta|<0.9 using data collected between 1994 and 1995 by the Collider Detector at Fermilab (CDF). The measurement is based on events where the photon converts into an electron-positron pair in the material of the inner detector, resulting in a two track event

D. Acosta; T. Affolder; M. G. Albrow; D. Ambrose; D. Amidei; K. Anikeev; J. Antos; G. Apollinari; T. Arisawa; A. Artikov; W. Ashmanskas; F. Azfar; P. Azzi-Bacchetta; N. Bacchetta; H. Bachacou; W. Badgett; A. Barbaro-Galtieri; V. E. Barnes; B. A. Barnett; S. Baroiant; M. Barone; G. Bauer; F. Bedeschi; S. Behari; S. Belforte; W. H. Bell; G. Bellettini; J. Bellinger; D. Benjamin; A. Beretvas; A. Bhatti; M. Binkley; D. Bisello; M. Bishai; R. E. Blair; C. Blocker; K. Bloom; B. Blumenfeld; A. Bocci; A. Bodek; G. Bolla; A. Bolshov; D. Bortoletto; J. Boudreau; C. Bromberg; E. Brubaker; J. Budagov; H. S. Budd; K. Burkett; G. Busetto; K. L. Byrum; S. Cabrera; M. Campbell; W. Carithers; D. Carlsmith; A. Castro; D. Cauz; A. Cerri; L. Cerrito; J. Chapman; C. Chen; Y. C. Chen; M. Chertok; G. Chiarelli; G. Chlachidze; F. Chlebana; M. L. Chu; J. Y. Chung; W.-H. Chung; Y. S. Chung; C. I. Ciobanu; A. G. Clark; M. Coca; A. Connolly; M. Convery; J. Conway; M. Cordelli; J. Cranshaw; R. Culbertson; D. Dagenhart; S. D'Auria; P. de Barbaro; S. de Cecco; S. dell'Agnello; M. dell'Orso; S. Demers; L. Demortier; M. Deninno; D. de Pedis; P. F. Derwent; C. Dionisi; J. R. Dittmann; A. Dominguez; S. Donati; M. D'Onofrio; T. Dorigo; N. Eddy; R. Erbacher; D. Errede; S. Errede; R. Eusebi; S. Farrington; R. G. Feild; J. P. Fernandez; C. Ferretti; R. D. Field; I. Fiori; B. Flaugher; L. R. Flores-Castillo; G. W. Foster; M. Franklin; J. Friedman; I. Furic; M. Gallinaro; M. Garcia-Sciveres; A. F. Garfinkel; C. Gay; D. W. Gerdes; E. Gerstein; S. Giagu; P. Giannetti; K. Giolo; M. Giordani; P. Giromini; V. Glagolev; D. Glenzinski; M. Gold; N. Goldschmidt; J. Goldstein; G. Gomez; M. Goncharov; I. Gorelov; A. T. Goshaw; Y. Gotra; K. Goulianos; A. Gresele; C. Grosso-Pilcher; M. Guenther; J. Guimaraes da Costa; C. Haber; S. R. Hahn; E. Halkiadakis; C. Hall; R. Handler; F. Happacher; K. Hara; R. M. Harris; F. Hartmann; K. Hatakeyama; J. Hauser; J. Heinrich; M. Hennecke; M. Herndon; C. Hill; A. Hocker; K. D. Hoffman; S. Hou; B. T. Huffman; R. Hughes; J. Huston; C. Issever; J. Incandela; G. Introzzi; M. Iori; A. Ivanov; Y. Iwata; B. Iyutin; E. James; M. Jones; T. Kamon; J. Kang; M. Karagoz Unel; S. Kartal; H. Kasha; Y. Kato; R. D. Kennedy; R. Kephart; B. Kilminster; D. H. Kim; H. S. Kim; M. J. Kim; S. B. Kim; S. H. Kim; T. H. Kim; Y. K. Kim; M. Kirby; L. Kirsch; S. Klimenko; P. Koehn; K. Kondo; J. Konigsberg; A. Korn; A. Korytov; J. Kroll; M. Kruse; V. Krutelyov; S. E. Kuhlmann; N. Kuznetsova; A. T. Laasanen; S. Lami; S. Lammel; J. Lancaster; K. Lannon; M. Lancaster; R. Lander; A. Lath; G. Latino; T. Lecompte; Y. Le; J. Lee; S. W. Lee; N. Leonardo; S. Leone; J. D. Lewis; K. Li; C. S. Lin; M. Lindgren; T. M. Liss; T. Liu; D. O. Litvintsev; N. S. Lockyer; A. Loginov; M. Loreti; D. Lucchesi; P. Lukens; L. Lyons; J. Lys; R. Madrak; K. Maeshima; P. Maksimovic; L. Malferrari; M. Mangano; G. Manca; M. Mariotti; M. Martin; A. Martin; V. Martin; M. Martínez; P. Mazzanti; K. S. McFarland; P. McIntyre; M. Menguzzato; A. Menzione; P. Merkel; C. Mesropian; A. Meyer; T. Miao; R. Miller; J. S. Miller; S. Miscetti; G. Mitselmakher; N. Moggi; R. Moore; T. Moulik; M. Mulhearn; A. Mukherjee; T. Muller; A. Munar; P. Murat; J. Nachtman; S. Nahn; I. Nakano; R. Napora; F. Niell; C. Nelson; T. Nelson; C. Neu; M. S. Neubauer; C. Newman-Holmes; T. Nigmanov; L. Nodulman; S. H. Oh; Y. D. Oh; T. Ohsugi; T. Okusawa; W. Orejudos; C. Pagliarone; F. Palmonari; R. Paoletti; V. Papadimitriou; J. Patrick; G. Pauletta; M. Paulini; T. Pauly; C. Paus; D. Pellett; A. Penzo; T. J. Phillips; G. Piacentino; J. Piedra; K. T. Pitts; A. Pompos; L. Pondrom; G. Pope; T. Pratt; F. Prokoshin; J. Proudfoot; F. Ptohos; O. Poukhov; G. Punzi; J. Rademacker; A. Rakitine; F. Ratnikov; H. Ray; A. Reichold; P. Renton; M. Rescigno; F. Rimondi; L. Ristori; W. J. Robertson; T. Rodrigo; S. Rolli; L. Rosenson; R. Roser; R. Rossin; C. Rott; A. Roy; A. Ruiz; D. Ryan; A. Safonov; R. St. Denis; W. K. Sakumoto; D. Saltzberg; C. Sanchez; A. Sansoni; L. Santi; S. Sarkar; P. Savard; A. Savoy-Navarro; P. Schlabach; E. E. Schmidt; M. P. Schmidt; M. Schmitt; L. Scodellaro; A. Scribano; A. Sedov; S. Seidel; Y. Seiya; A. Semenov; F. Semeria; M. D. Shapiro; P. F. Shepard; T. Shibayama; M. Shimojima; M. Shochet; A. Sidoti; A. Sill; P. Sinervo; A. J. Slaughter; K. Sliwa; F. D. Snider; R. Snihur; M. Spezziga; F. Spinella; M. Spiropulu; L. Spiegel; A. Stefanini; J. Strologas; D. Stuart; A. Sukhanov; K. Sumorok; T. Suzuki; R. Takashima; K. Takikawa; M. Tanaka; M. Tecchio; R. J. Tesarek; P. K. Teng; K. Terashi; S. Tether; J. Thom; A. S. Thompson; E. Thomson; P. Tipton; S. Tkaczyk; D. Toback; K. Tollefson; D. Tonelli; M. Tönnesmann; H. Toyoda; W. Trischuk; J. Tseng; D. Tsybychev; N. Turini; F. Ukegawa; T. Unverhau; T. Vaiciulis; A. Varganov; E. Vataga; S. Vejcik; G. Velev; G. Veramendi; R. Vidal; I. Vila; R. Vilar

2004-01-01

409

Neutrino and Antineutrino Cross sections at MiniBooNE  

SciTech Connect

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

Dharmapalan, Ranjan; /Alabama U.

2011-10-01

410

Neutrino and Antineutrino Cross sections at MiniBooNE  

E-print Network

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

Ranjan Dharmapalan; for the MiniBooNE Collaboration

2011-10-20

411

Calculation of light nucleus reaction cross sections in Geant4  

E-print Network

Total reaction cross sections of light projectile nucleus (H-2, H-3, He-3 and He-4) interactions with nuclei are calculated using Geant4 models, and compared with experimental data. It is shown that the models give various predictions at low energies, in the region of the Coulomb barrier. "Shen model" (W.-Q. Shen et al., Nucl. Phys. {\\bf A491} (1989) 130) is identified as an improvement over other models.

V. Uzhinsky

2012-09-20

412

Analysis of charged-current neutrino-nucleus cross section  

NASA Astrophysics Data System (ADS)

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

Megias, G.; Caballero, J. A.

2013-06-01

413

Pooling Time-Series of Cross-Section Data  

Microsoft Academic Search

\\u000a In this chapter, we will consider pooling time-series of cross-sections. This may be a panel of households or firms or simply\\u000a countries or states followed over time. Two well known examples of panel data in the U.S. are the Panel Study of Income Dynamics\\u000a (PSID) and the National Longitudinal Survey (NLS). The PSID began in 1968 with 4802 families, including

Badi H. Baltagi

414

Stellar neutron capture cross sections of the Yb isotopes  

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of 170Yb, 171Yb, 172Yb, 173Yb, 174Yb, and 176Yb have been measured in the energy range from 3 to 225 keV relative to the gold standard. Neutrons were produced at the Karlsruhe 3.75 MV Van de Graaff Accelerator via the 7Li(p,n)7Be reaction by bombarding metallic Li targets with a pulsed proton beam, and capture events were registered with the Karlsruhe 4? Barium Fluoride Detector. Neutron capture in the even ytterbium isotopes is characterized by a strong population of isomeric states, leading to unrecognized systematic uncertainties in previous measurements. For the first time, partial cross sections to ground and isomeric states could be experimentally identified in neutron time-of-flight measurements for 172Yb, 173Yb, 174Yb, and 176Yb. The present overall uncertainties of (1-1.5) % correspond to an improvement by factors of 4-10 compared to existing data. Maxwellian averaged neutron capture cross sections were calculated for thermal energies between kT=8 keV and 100 keV. In four cases, the results differ by more than 15% from recent evaluations. The s-process analyses based on the present data provide further evidence in favor of stellar models for thermally pulsing low-mass asymptotic giant branch stars.

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

2000-06-01

415

Extension of the Bgl Broad Group Cross Section Library  

NASA Astrophysics Data System (ADS)

The broad group cross-section libraries BUGLE and BGL are applied for reactor shielding calculation using the DOORS package based on discrete ordinates method and multigroup approximation of the neutron cross-sections. BUGLE and BGL libraries are problem oriented for PWR or VVER type of reactors respectively. They had been generated by collapsing the problem independent fine group library VITAMIN-B6 applying PWR and VVER one-dimensional radial model of the reactor middle plane using the SCALE software package. The surveillance assemblies (SA) of VVER-1000/320 are located on the baffle above the reactor core upper edge in a region where geometry and materials differ from those of the middle plane and the neutron field gradient is very high which would result in a different neutron spectrum. That is why the application of the fore-mentioned libraries for the neutron fluence calculation in the region of SA could lead to an additional inaccuracy. This was the main reason to study the necessity for an extension of the BGL library with cross-sections appropriate for the SA region. Comparative analysis of the neutron spectra of the SA region calculated by the VITAMIN-B6 and BGL libraries using the two-dimensional code DORT have been done with purpose to evaluate the BGL applicability for SA calculation.

Kirilova, Desislava; Belousov, Sergey; Ilieva, Krassimira

2009-08-01

416

Photonuclear Reactions in FLUKA: Cross Sections and Interaction Models  

SciTech Connect

Photonuclear reactions, implemented in FLUKA about ten years ago, have opened the way to a more accurate design of electron accelerator shielding. Since then, they have been introduced also in other codes: but the FLUKA design, covering all nuclei over the whole energy range, remains still unique. The FLUKA scheme is based on several physical models corresponding to different energy ranges but partially overlapping to ensure continuity. All models are smoothly integrated in the FLUKA hadronic event generator. Here we will mainly focus on the FLUKA Giant Resonance total cross-section database, which has been derived from experimental data or from existing evaluations for 190 nuclides. For all other nuclei, excitation functions are obtained from parameterizations or by interpolation. Many partial cross sections, not used explicitly in FLUKA, have also been evaluated in order to ensure consistency of the total cross sections entered into the database. The FLUKA implementation of photonuclear reactions has been successfully benchmarked with activation and neutron spectrometry experiments, and is being widely used to design shielding and to predict radiation damage.

Fasso, Alberto [SLAC, MS 48, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Ferrari, Alfredo [CERN, CH-1211 Geneva 23 (Switzerland); Sala, Paola R. [ETH, CH-8093 Zurich (Switzerland)

2005-05-24

417

Three Dimensional Cross-Sectional Properties From Bone Densitometry  

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

418

Summary of the Workshop on Neutron Cross Section Covariances  

SciTech Connect

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

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

2008-12-15

419

Infrared Gluon Resummation and pp total cross-sections  

E-print Network

We address here the problem of describing both the total and the elastic proton-proton cross-section, through the four outstanding features of hadron scattering: (i) the optical point; (ii) the forward peak, (iii) the dip and (iv) the subsequent descent at larger momentum transfers. These issues are discussed through an eikonal model for the elastic amplitude where the matter distribution in impact parameter space is given by resummed soft gluons down into the infrared (IR) region. The asymptotic growth of the total cross-section is obtained in a mini-jet model and the taming (saturation) at high energies is related to confinement realized here through an IR singular strong coupling constant alpha_s(Q^2). We present an ansatz that links the IR singularity of alpha_s(Q^2) to that of asymptotic freedom (AF) (at lowest order). Through this model, we illustrate the problems that arise in a generic one-channel eikonal model employed for a description of the measured differential elastic cross-section at LHC7.

Pancheri, Giulia; Grau, A; Shekhovtsova, O; Srivastava, Yogendra N

2014-01-01

420

Towards Reliable Cross Sections for National Security Applications  

SciTech Connect

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

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

2011-02-24

421

Coherent set of electron cross sections for argon  

NASA Astrophysics Data System (ADS)

This paper presents a coherent set of electron impact cross sections for argon [1] (elastic momentum-transfer, inelastic for the excitation of 37 levels Ar(4s,4p,3d,5p,4d,6s) and ionization), which was recently uploaded onto the LXcat IST-Lisbon database [2]. The cross section set was validated by comparing calculated swarm parameters (electron mobility and characteristic energy) and rate coefficients (Townsend ionization coefficient and direct + cascade excitation coefficients to the 4s and 4p states) with available experimental data, for E/N = 10-4 -- 100 Td and Tg = 300, 77 K. The validation procedure involves the solution to the homogeneous two-term electron Boltzmann equation, resorting to three different solvers: (i) IST-Lisbon's; (ii) BOLSIG+ (v1.2) with LXcat; (iii) BOLSIG+ (v1.23) [3]. The results obtained with these solvers are compared to evidence the importance of certain numerical features related with both the energy-grid (number of points, grid-type and maximum energy value) and the interpolation scheme adopted for the cross sections. In particular, the latter can cause a 6% variation on the values of swarm parameters at intermediate E/Ns. [1] A. Yanguas-Gil, J. Cotrino and L.L. Alves, J. Phys. D 38, 1588 (2005). [2] http://www.lxcat.laplace.univ-tlse.fr/ [3] G.J.M. Hagelaar and L.C. Pitchford, Plasma Sources Sci. Technol. 14, 722 (2005).

Alves, L. L.; Ferreira, C. M.

2011-11-01

422

Hydraulic geometry of river cross sections; theory of minimum variance  

USGS Publications Warehouse

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

Williams, Garnett P.

1978-01-01

423

Neutron Capture Cross Sections for the Re/Os Clock  

SciTech Connect

The radioactive decay of 187Re {yields} 187Os (t1/2 = 43 Gyr) is suited for dating the onset of heavy-element nucleosynthesis. The radiogenic contribution to the 187Os abundance is the difference between the natural abundance and the corresponding s-process component. This component can be obtained via the well-established {sigma}N systematics using the neighboring s-only isotope 186Os, provided the neutron-capture cross sections of both isotopes are known with sufficient accuracy. We report on a new set of experiments performed with a C6D6 detector array at the n{sub T}OF neutron spallation facility of CERN. The capture cross sections of 186Os, 187Os, and 188Os have been measured in the neutron-energy range between 1 eV and 1 MeV, and Maxwellian-averaged cross sections were deduced for the relevant thermal energies from kT=5 keV to 100 keV.

Mosconi, M.; Heil, M.; Kaeppeler, F.; Plag, R.; Voss, F.; Wisshak, K. [Forschungszentrum Karlsruhe GmbH (FZK), Institut fuer Kernphysik (Germany); Mengoni, A.; Cennini, P.; Chiaveri, E.; Ferrari, A.; Fitzpatrick, L.; Herrera-Martinez, A.; Kadi, Y.; Sarchiapone, L.; Vlachoudis, V.; Wendler, H. [CERN, Geneva (Switzerland); Aerts, G.; Andriamonje, S.; Berthoumieux, E.; Dridi, W. [EA/Saclay - DSM, Gif-sur-Yvette (France)] [and others

2005-05-24

424

Status of Nuclear Physics Cross Sections Models and Future Directions  

NASA Astrophysics Data System (ADS)

Exposures from the hazards of space radiation in deep space/long duration missions are very different from that of low earth orbit, and much needs to be learned about their effects. The overall situation is further augmented by the nonexistence of in vivo or in vitro data or studies about continuous long duration tissues exposure to radiation and concomitant biological uncertainties. All radiation protection and shielding transport and needed nuclear cross sections models so far have focused on radiation that goes through the shielding materials and are usually high energy physics models. From the perspective of exposure to astronauts, this exposure contributes to health risks. However, the very important radiation exposure where the radiation traverses through the astronauts and considerably slows down and/or even stops inside their body is less well studied. This kind of radiation contributes may be more biologically damaging than the radiation which just passes through because the ionizing power is highest as the particle stops in tissue. There is a clear need for improved nuclear physics cross sections models to described low energy collisions. Low energy physics significantly contributes to biological dose, risk assessments, and related uncertainty evaluations. In this report we will focus on the current status of these (mostly low energy) cross sections models and elaborate on future directions.

Cucinotta, Francis A.; Tripathi, Ram; Kim, Myung-Hee Y.

2012-07-01

425

Electron collision cross-section data for plasma modeling  

SciTech Connect

Electron collisions provide the driving mechanism behind the plasma processes employed in semiconductor manufacturing and related industries. The radicals and ions produced by the collisions of electrons with the feed gas interact with the surface through a series of complex chemical reactions, leading to etching, deposition, or cleaning. Thus electron collision data are just as important as data on heterogeneous surface reactions in understanding and controlling such processes. Here, an overview of the current status in electron collision cross section databases for plasma modeling is presented. Emphasis is on dissociation, ionization, and dissociative ionization. The effect of the operating conditions on the relative importance of different collision mechanisms is discussed. For high density plasmas with low gas pressure, a second collision with electrons becomes likely and metastable states may play a role in the dissociation and ionization processes. A number of outstanding theoretical and experimental issues in the cross-section data are discussed. For the total ionization cross section, a four=parameter fitting formulate is found to represent the numerical data well and the parameters for some molecules used in plasma modeling are presented.

Huo, W.M.; Kim, Y.K.

1999-10-01

426

Composite RCS frame systems: construction and peformance  

E-print Network

, to simulate the wind loads in a subassembly of a prototype building. To compliment the experimental work, nonlinear analyses were performed to evaluate the specimen strength and hysteretic degradation parameters for RCS systems. In addition, current...

Steele, John Phillip

2004-09-30

427

Determination of the pi0 gamma cross-section  

SciTech Connect

In this memo the authors address the following questions: how the {pi}{sup 0}{gamma} cross section, which is measured in E760, compares to the expected leakage from the {pi}{sup 0}{pi}{sup 0} final states; is it possible to affirm that a substantial fraction of the {pi}{sup 0}{gamma} events are due to continuum production? Naively, the expected continuum {pi}{sup 0}{gamma} cross section can be estimated using the Vector Meson Dominance Model (VDM). In that framework, a photon is coupled to a neutral vector meson V by G{sub {gamma}V}. Then {sigma}{sub {pi}{sup 0}{gamma}} = {sigma}{sub {pi}{sup 0}{rho}} x G{sub {gamma}{rho}}{sup 2} with G{sub {gamma}{rho}}{sup 2} = 1./160 {divided_by} 1./380 [1]. At E{sub CM} = 2.611 GeV, {sigma}{sub {pi}{sup 0}{rho}} = (70 {+-} 30){mu}b [2] which gives {sigma}{sub {pi}{sup 0}{gamma}} = 184 {divided_by} 438 nb. To predict the cross section within a limited acceptance they assume that the angular production of {pi}{sup 0}{gamma} is similar to the {pi}{sup 0}{pi}{sup 0} and {pi}{sup 0}{rho} ones. To estimate the fraction of events with |cos{theta}*| < 0.5, being {theta}* the center of mass production angle, they do use the total {pi}{sup +}{pi}{sup -} cross section {sigma}{sub {pi}{sup +}{pi}{sup -}} = (6.6 {+-} 3.5){mu}b at 2.975 GeV [3]. {sigma}{sub {pi}{sup 0}{pi}{sup 0}} = 0.5 x {sigma}{sub {pi}{sup +}{pi}{sup -}}, while for |cos{theta}*| < 0.5 E760 measures {sigma}{sub {pi}{sup 0}{pi}{sup 0}} {approx_equal} 180. nb at the above center of mass energy and |cos{theta}*| < 0.5. They obtain that the fraction of {pi}{sup 0}{pi}{sup 0} events with |cos{theta}*| < 0.5 is 5.4 x 10{sup -2}. Finally, multiplying the expected total cross section and the above fraction, they obtain {sigma}{sub {pi}{sup 0}{gamma}} = (10. {divided_by} 23.8) nb with |cos{theta}*| < 0.5. This prediction gives a value which is far from being negligible and certainly measurable in the experiment.

Govi, G.; Lombardo, M.; Marchetto, F.; /INFN, Turin /Turin U.

1992-06-01

428

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

SciTech Connect

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

Strauss, Emanuel Alexandre; /SUNY, Stony Brook

2009-08-01

429

A radar-echo model for Mars  

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

430

Radar Scattering from Foamed Plastic Target Supports.  

National Technical Information Service (NTIS)

This study investigates the scattering from foamed 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 associate...

M. W. Chambers

1991-01-01

431

Signature management of radar returns from wind turbine generators  

Microsoft Academic Search

The large radar cross section of wind turbine generator (WTG) blades combined with high tip speeds can produce significant Doppler returns when illuminated by a radar. Normally, an air traffic control radar system will filter out large returns from stationary targets, but the Doppler shifts introduced by the WTG blades are interpreted as moving aircraft that can confuse radar operators

A. Tennant; B. Chambers

2006-01-01

432

Space object observation with radar  

NASA Astrophysics Data System (ADS)

FGAN developed a High Power Radar System, able to track and image low Earth orbiting objects, for experimental radar research. The system is unique in Germany; it consists of a narrow band tracking radar and a high resolution imaging radar. The radars are supported from one 34-m parabolic dish antenna. They operate simultaneously on the object of interest. All information which a radar can gain about physical characteristics of targets have to be extracted from the backscattered electromagnetic field of transmitted pulses. L-band tracking data provide information on range, range rate, angular direction, and radar cross-section. From high resolution polarimetric Ku-band radar data projections of the 1- and 2-dimensional scatter centre distributions are computed. This paper gives a brief description of the FGAN radar and summarizes some radar based methods for orbit analysis, orbital lifetime prediction, reconstruction of object images, assessment of object dimensions, shape, attitude, and mass.

Mehrholz, D.

1993-08-01

433

Constant cross section of loops in the solar corona  

NASA Astrophysics Data System (ADS)

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

Peter, H.; Bingert, S.

2012-12-01

434

MOX Cross-Section Libraries for ORIGEN-ARP  

SciTech Connect

The use of mixed-oxide (MOX) fuel in commercial nuclear power reactors operated in Europe has expanded rapidly over the past decade. The predicted characteristics of MOX fuel such as the nuclide inventories, thermal power from decay heat, and radiation sources are required for design and safety evaluations, and can provide valuable information for non-destructive safeguards verification activities. This report describes the development of computational methods and cross-section libraries suitable for the analysis of irradiated MOX fuel with the widely-used and recognized ORIGEN-ARP isotope generation and depletion code of the SCALE (Standardized Computer Analyses for Licensing Evaluation) code system. The MOX libraries are designed to be used with the Automatic Rapid Processing (ARP) module of SCALE that interpolates appropriate values of the cross sections from a database of parameterized cross-section libraries to create a problem-dependent library for the burnup analysis. The methods in ORIGEN-ARP, originally designed for uranium-based fuels only, have been significantly upgraded to handle the larger number of interpolation parameters associated with MOX fuels. The new methods have been incorporated in a new version of the ARP code that can generate libraries for low-enriched uranium (LEU) and MOX fuel types. The MOX data libraries and interpolation algorithms in ORIGEN-ARP have been verified using a database of declared isotopic concentrations for 1042 European MOX fuel assemblies. The methods and data are validated using a numerical MOX fuel benchmark established by the Organization for Economic Cooperation and Development (OECD) Working Group on burnup credit and nuclide assay measurements for irradiated MOX fuel performed as part of the Belgonucleaire ARIANE International Program.

Gauld, I.C.

2003-07-01

435

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

SciTech Connect

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

Chung, Kwangzoo; /Carnegie Mellon U.

2008-05-01

436

Final Report - Nucelar Astrophysics & Neutron Cross Section Measurements  

SciTech Connect

This enduring research program of 28 years has taken advantage of the excellent research facility of ORELA at Oak Ridge National Laboratory. The fruitful collaborations include a number of scientists from ORNL and some from LASL. This program which has ranged from nuclear structure determinations to astrophysical applications has resulted in the identification and/or the refinement of the nuclear properties of more than 5,000 nuclear energy levels or compound energy states. The nuclei range from 30Si to 250Cf, the probes range from thermal to 50 MeV neutrons, and the studies range from capture gamma ray spectra to total and differential scattering and absorption cross sections. Specific target nuclei studied include the following: 120Sn 124Sn 125Sn 113Sn 115Sn 117Sn 119Sn 249Cf 33S 34S 249Bk 186Os 187Os 188Os 30Si 32S 40Ca 48Ca 60Ni 54Fe 86Kr 88Sr 40Ar 122Sn 90Zr 122Sn(n,?) 208Pb 204Pb 52Cr 54Cr 50Cr 53Cr As can be seen, we have studied, on average, more than one isotope per year of grant funding and have focused on exploiting those elements having multiple isotopes in order to investigate systematic trends in nuclear properties, for the purpose of providing more stringent tests of the nuclear spherical optical model with a surface imaginary potential. We have investigated an l-dependence of the real-well depth of the spherical optical model; we have used these measurements to deduce the existence of doorway states in the compound nucleus; and in the total cross section measurements we have, in addition to resonance energies and widths, obtained values for the level density and neutron strength function. Due to the high neutron energy resolution of the ORELA and in some cases the addition of differential scattering cross section data, we have been able to disaggregate the spin states and provide level spacing and strength function for each partial wave in the neutron-nucleus interaction, in some cases up to d5/2. In the following we will summarize the most recent analyses of neutron total cross section measurements, some of which have not been previously reported.

Carlton, Robert F

2009-12-01

437

He3 Spin-Dependent Cross Sections and Sum Rules  

Microsoft Academic Search

We present a measurement of the spin-dependent cross sections for the He-->3(e-->,e')X reaction in the quasielastic and resonance regions at a four-momentum transfer 0.1<=Q2<=0.9GeV2. The spin-structure functions have been extracted and used to evaluate the nuclear Burkhardt-Cottingham and extended Gerasimov-Drell-Hearn sum rules for the first time. The data are also compared to an impulse approximation calculation and an exact three-body

Karl Slifer; M. Amarian; L. Auerbach; T. Averett; J. Berthot; P. Bertin; B. Bertozzi; T. Black; E. Brash; D. Brown; E. Burtin; J. Calarco; G. Cates; Z. Chai; J.-P. Chen; Seonho Choi; E. Chudakov; C. Ciofi Degli Atti; E. Cisbani; C. W. de Jager; A. Deur; R. Disalvo; S. Dieterich; P. Djawotho; M. Finn; K. Fissum; H. Fonvieille; S. Frullani; H. Gao; J. Gao; F. Garibaldi; A. Gasparian; S. Gilad; R. Gilman; A. Glamazdin; C. Glashausser; W. Glöckle; J. Golak; E. Goldberg; J. Gomez; V. Gorbenko; J.-O. Hansen; B. Hersman; R. Holmes; G. M. Huber; E. Hughes; B. Humensky; S. Incerti; M. Iodice; S. Jensen; X. Jiang; C. Jones; G. Jones; M. Jones; C. Jutier; H. Kamada; A. Ketikyan; I. Kominis; W. Korsch; K. Kramer; K. Kumar; G. Kumbartzki; M. Kuss; E. Lakuriqi; G. Laveissiere; J. J. Lerose; M. Liang; N. Liyanage; G. Lolos; S. Malov; J. Marroncle; K. McCormick; R. D. McKeown; Z.-E. Meziani; R. Michaels; J. Mitchell; A. Nogga; E. Pace; Z. Papandreou; T. Pavlin; G. G. Petratos; D. Pripstein; D. Prout; R. Ransome; Y. Roblin; D. Rowntree; M. Rvachev; F. Sabatié; A. Saha; G. Salmè; S. Scopetta; R. Skibinski; P. Souder; T. Saito; S. Strauch; R. Suleiman; K. Takahashi; S. Teijiro; Luminita Todor; Hiroaki Tsubota; Hiroaki Ueno; Guido Urciuoli; Rob van der Meer; Pascal Vernin; H. Voskanian; Henryk Witala; Bogdan Wojtsekhowski; Feng Xiong; Wang Xu; Jae-Choon Yang; Bin Zhang; Piotr Zolnierczuk

2008-01-01

438

PHOTON PLUS JET CROSS SECTIONS AT THE TEVATRON  

E-print Network

Photon plus jet production has been studied by the DØ and CDF experiments in Run II of the Fermilab Tevatron Collider at a center of mass energy of ? s = 1.96 TeV. Measurements of the inclusive photon plus jet, di-photon and photon plus b jet cross section are presented. They are based on integrated luminosities between 0.2 fb ?1 and 1.1 fb ?1. The results are compared to perturbative QCD calculations in various approximations. 1

L. Sonnenschein

439

Doubly differential cross sections for galactic heavy-ion fragmentation  

NASA Technical Reports Server (NTRS)

An abrasion-ablation T-matrix formulation is applied to the calculation of double differential-cross sections in projectile fragmentation of 2.1 GeV/nucleon O-16 on Be-9 and 86 MeV/nucleon C-12 on C-12 and Ag-108. An exponential parameterization of the ablation T-matrix is used and the total width of the intermediate states is taken as a parameter. Fitted values of the total width to experimental results are used to predict the lifetime of the ablation stage and indicate a decay time on the order of 10 to the -19th power sec.

Cucinotta, Francis A.; Norbury, John W.; Khandelwal, Govind S.; Townsend, Lawrence W.

1987-01-01

440

Dielectronic Recombination Cross-Sections of Fluorinelike Xenon  

E-print Network

PHYSICAL REVIEW A VOLUME 47, NUMBER 3 MARCH 1993 Dielectronic recombination cross sections of Snorinelike xenon D. R. DeWitt, D. Schneider, M. H. Chen, and M. B. Schneider Laturence Li uermore National Laboratory, Uniuersity of California... width at half maximum. The experimentally measured res- onances are compared to convolved theoretical DR resonance strengths. The agreement with theory is excellent. PACS number(s): 34.80.Kw, 34.80.Dp A (ls 2s 2p )+e~A**(ls 2s 2p nln'1') ~ A *(ls 2s...

Dewitt, D. R.; Schneider, D.; Chen, M. H.; Schneider, M. B.; Church, David A.; Weinberg, G.; Sakurai, M.

1993-01-01

441

Upper bound on the dark matter total annihilation cross section.  

PubMed

We consider dark matter annihilation into standard model particles and show that the least detectable final states, namely, neutrinos, define an upper bound on the total cross section. Calculating the cosmic diffuse neutrino signal, and comparing it to the measured terrestrial atmospheric neutrino background, we derive a strong and general bound. This can be evaded if the annihilation products are dominantly new and truly invisible particles. Our bound is much stronger than the unitarity bound at the most interesting masses, shows that dark matter halos cannot be significantly modified by annihilations, and can be improved by a factor of 10-100 with existing neutrino experiments. PMID:18233354

Beacom, John F; Bell, Nicole F; Mack, Gregory D

2007-12-01

442

Measuring the hadronic cross section via radiative return  

E-print Network

Recently it has been demonstrated that particle factories, such as DAPHNE and PEP-II, operating at fixed center-of-mass energies, are able to measure hadronic cross sections as a function of the hadronic system energy using the raditive return. This paper is an experimental overview of the progress in this aera. Preliminary results from KLOE for the process e+e- -> \\rho \\gamma -> \\pi+\\pi-\\gamma and a fit to the pion form factor are presented. Some first results from the BABAR collaboration are also shown.

Achim G. Denig; for the KLOE collaboration

2002-11-11

443

Measuring the hadronic cross section via radiative return  

E-print Network

Recently it has been demonstrated that particle factories, such as DAPHNE and PEP-II, operating at fixed center-of-mass energies, are able to measure hadronic cross sections as a function of the hadronic system energy using the raditive return. This paper is an experimental overview of the progress in this aera. Preliminary results from KLOE for the process e+e- -> \\rho \\gamma -> \\pi+\\pi-\\gamma and a fit to the pion form factor are presented. Some first results from the BABAR collaboration are also shown.

Denig, A G

2003-01-01

444

Top: Latest results from the Tevatron - Cross section and mass  

SciTech Connect

The Tevatron is presently the world's only source of top quark production. This presentation summarizes the latest Run II results on top physics obtained by the CDF and D0 collaborations, using data taken until mid-January 2003. The first cross section measurements at 1.96 TeV in dilepton and lepton+jets channels agree with the NLO (Next-to-Leading-Order) theoretical predictions. Two top mass measurements, one by CDF using Run II data and another by D0 using an improved technique anticipate the improvements to come in the near future.

M. Coca

2003-09-02

445

Cross sections and reaction rates of relevance to aeronomy  

SciTech Connect

Experimental and theoretical data relevant to models and measurements of the chemical and thermal structures and luminosity of the thermospheres of the earth and planets published during the last four years are surveyed. Among chemical processes, attention is given to ion-molecule reactions, dissociative recombination of molecular ions, and reactions between neutral species. Both reactions between ground state species and species in excited states are considered, including energy transfer and quenching. Measured and calculated cross sections for interactions of solar radiation with atmospheric species, such as photoabsorption, photoionization, and photodissociation and related processes are surveyed.

Fox, J.L. (USAF, Geophysics Laboratory, Hanscom AFB, MA (United States))

1991-01-01

446

Fluctuating annihilation cross sections and the generation of density perturbations  

SciTech Connect

Fluctuations in the mass and decay rate of a heavy particle which for some period dominates the energy density of the Universe are known to lead to adiabatic density perturbations. We show that generically the annihilation cross section of the same particle also receives fluctuations, which leads to entropy perturbations at freeze-out. If the particle comes to dominate the energy density of the Universe and subsequently decays, this leads to an additional source of adiabatic density perturbations. On the other hand, nonadiabatic density perturbations result when the particle does not decay but contributes to the observed dark matter.

Bauer, Christian W.; Graesser, Michael L.; Salem, Michael P. [California Institute of Technology, Pasadena, California 91125 (United States)

2005-07-15

447

Photon plus Jet Cross Sections at the Tevatron  

E-print Network

Photon plus jet production has been studied by the D0 and CDF experiments in Run II of the Fermilab Tevatron Collider at a center of mass energy of sqrt{s}=1.96 TeV. Measurements of the inclusive photon plus jet, di-photon and photon plus b jet cross section are presented. They are based on integrated luminosities between 0.2 fb^-1 and 1.1 fb^-1. The results are compared to perturbative QCD calculations in various approximations.

Lars Sonnenschein

2008-04-03

448

Self-consistent description of nuclear photoabsorption cross sections  

E-print Network

Several approaches to photonuclear reactions, based on the time-dependent density-functional theory, have been developed recently. The standard linearization leads to the random-phase approximation (RPA) or the quasiparticle-random-phase approximation (QRPA). We have developed a parallelized QRPA computer program for axially deformed nuclei. We also present a feasible approach to the (Q)RPA calculation, that is the finite amplitude method (FAM). We show results of photoabsorption cross sections for deformed nuclei using the QRPA and FAM calculations. Finally, the canonical-basis approach to the time-dependent Hartree-Fock-Bogoliubov method is presented, to demonstrate its feasibility and usefulness.

Takashi Nakatsukasa; Paolo Avogadro; Shuichiro Ebata; Tsunenori Inakura; Kenichi Yoshida

2011-01-17

449

Self-consistent description of nuclear photoabsorption cross sections  

E-print Network

Several approaches to photonuclear reactions, based on the time-dependent density-functional theory, have been developed recently. The standard linearization leads to the random-phase approximation (RPA) or the quasiparticle-random-phase approximation (QRPA). We have developed a parallelized QRPA computer program for axially deformed nuclei. We also present a feasible approach to the (Q)RPA calculation, that is the finite amplitude method (FAM). We show results of photoabsorption cross sections for deformed nuclei using the QRPA and FAM calculations. Finally, the canonical-basis approach to the time-dependent Hartree-Fock-Bogoliubov method is presented, to demonstrate its feasibility and usefulness.

Nakatsukasa, Takashi; Ebata, Shuichiro; Inakura, Tsunenori; Yoshida, Kenichi

2011-01-01

450

Measuring the hadronic cross section via radiative return  

NASA Astrophysics Data System (ADS)

Recently it has been demonstrated that particle factories, such as DA?NE and PEP-II, operating at fixed center-of-mass energies, are able to measure hadronic cross sections as a function of the hadronic system energy using the radiative return. This paper is an experimental overview of the progress in this area. Preliminary results from KLOE for the process e+e- ? ?? ? ?+?-? and a fit to the pion form factor are presented. Some first results from the BABAR collaboration are also shown.

Aloisio, A.; Ambrosino, F.; Antonelli, A.; Antonelli, M.; Bacci, C.; Bencivenni, G.; Bertolucci, S.; Bini, C.; Bloise, C.; Bocci, V.; Bossi, F.; Branchini, P.; Bulychjov, S. A.; Caloi, R.; Campana, P.; Capon, G.; Carboni, G.; Casarsa, M.; Casavola, V.; Cataldi, G.; Ceradini, F.; Cervelli, F.; Cevenini, F.; Chiefari, G.; Ciambrone, P.; Conetti, S.; De Lucia, E.; De Robertis, G.; De Simone, P.; De Zorzi, G.; Dell'Agnello, S.; Denig, A.; Di Domenico, A.; Di Donato, C.; Di Falco, S.; Doria, A.; Dreucci, M.; Erriquez, O.; Farilla, A.; Felici, G.; Ferrari, A.; Ferrer, M. L.; Finocchiaro, G.; Forti, C.; Franceschi, A.; Franzini, P.; Gatti, C.; Gauzzi, P.; Giovannella, S.; Gorini, E.; Grancagnolo, F.; Graziani, E.; Han, S. W.; Incagli, M.; Ingrosso, L.; Kluge, W.; Kuo, C.; Kulikov, V.; Lacava, F.; Lanfranchi, G.; Lee-Franzini, J.; Leone, D.; Lu, F.; Martemianov, M.; Matsyuk, M.; Mei, W.; Merola, L.; Messi, R.; Miscetti, S.; Moulson, M.; Müller, S.; Murtas, F.; Napolitano, M.; Nedosekin, A.; Nguyen, F.; Palutan, M.; Paoluzi, L.; Pasqualucci, E.; Passalacqua, L.; Passeri, A.; Patera, V.; Petrolo, E.; Pontecorvo, L.; Primavera, M.; Ruggieri, F.; Santangelo, P.; Santovetti, E.; Saracino, G.; Schamberger, R. D.; Sciascia, B.; Sciubba, A.; Scuri, F.; Sfiligoi, I.; Spadaro, T.; Spiriti, E.; Tong, G. L.; Tortora, L.; Valente, E.; Valente, P.; Valeriani, B.; Venanzoni, G.; Veneziano, S.; Ventura, A.; Xu, G.; Yu, G. W.; KLOE Collaboration

2003-03-01

451

SCAMPI: A code package for cross-section processing  

SciTech Connect

The SCAMPI code package consists of a set of SCALE and AMPX modules that have been assembled to facilitate user needs for preparation of problem-specific, multigroup cross-section libraries. The function of each module contained in the SCANTI code package is discussed, along with illustrations of their use in practical analyses. Ideas are presented for future work that can enable one-step processing from a fine-group, problem-independent library to a broad-group, problem-specific library ready for a shielding analysis.

Parks, C.V.; Petrie, L.M.; Bowman, S.M.; Broadhead, B.L.; Greene, N.M.; White, J.E.

1996-04-01

452

NLO Corrections to Jet Cross Sections in DIS  

E-print Network

Next-to-leading order corrections to jet cross sections in deep inelastic scattering at HERA are studied. The predicted jet rates allow for a precise determination of $\\alpha_s(\\mu_R)$ at HERA over a wide range of $\\mu_R$. We argue, that the ``natural'' renormalization and factorization scale is set by the average $k_T^B$ of the jets in the Breit frame and suggest to divide the data in corresponding $$ intervals. Some implications for the determination of the gluon density and the associated forward jet production in the low $x$ regime at HERA are briefly discussed.

Erwin Mirkes; Dieter Zeppenfeld

1996-08-01

453

QCD Corrections to Jet Cross Sections in DIS  

E-print Network

Next-to-leading order corrections to jet cross sections in deep inelastic scattering at HERA are studied. The predicted jet rates allow for a precise determination of $\\alpha_s(\\mu_R)$ at HERA over a wide range of $\\mu_R$. We argue, that the ``natural'' renormalization and factorization scale is set by the average $k_T^B$ of the jets in the Breit frame and suggest to divide the data in corresponding $$ intervals. Some implications for the determination of the gluon density and the associated forward jet production in the low $x$ regime at HERA are briefly discussed.

Erwin Mirkes; Dieter Zeppenfeld

1996-06-14

454

Perturbative Gluon Resummation of the Top Quark Production Cross Section  

E-print Network

We present a calculation of the total cross section for top quark production based on a new perturbative resummation of gluon radiative corrections to the basic QCD subprocesses. We use Principal Value Resummation to calculate all relevant large threshold corrections. Advantages of this method include its independence from arbitrary infrared cutoffs and specification of the perturbative regime of applicability. For $p\\bar{p}$ collisions at center-of-mass energy $\\sqrt{s}=1.8$TeV and a top mass of 175 GeV, we compute $\\sigma(t\\bar{t})=5.52^{+0.07}_{-0.45}pb$.

Edmond L. Berger; Harry Contopanagos

1995-07-20

455

Photoneutron Cross Sections for Unstable Neutron-Rich Oxygen Isotopes  

SciTech Connect

The dipole response of stable and unstable neutron-rich oxygen nuclei of masses A=17 to A=22 has been investigated experimentally utilizing electromagnetic excitation in heavy-ion collisions at beam energies about 600 MeV/nucleon . A kinematically complete measurement of the neutron decay channel in inelastic scattering of the secondary beam projectiles from a Pb target was performed. Differential electromagnetic excitation cross sections d{sigma}/dE were derived up to 30MeV excitation energy. In contrast to stable nuclei, the deduced dipole strength distribution appears to be strongly fragmented and systematically exhibits a considerable fraction of low-lying strength.

Leistenschneider, A.; Aumann, T.; Boretzky, K.; Cortina, D.; Cub, J.; Pramanik, U. Datta; Dostal, W.; Elze, Th. W.; Emling, H.; Geissel, H. (and others)

2001-06-11

456

Neutron cross section standards evaluations for ENDF/B-VI  

SciTech Connect

The neutron cross section standards are now being evaluated as the initial phase in the development of the new ENDF/B-VI file. These standards evaluations are following a somewhat different process compared with that used for earlier versions of ENDF. The primary effort is concentrated on a simultaneous evaluation using a generalized least squares program, R-matrix evaluations, and a procedure for combining the results of these evaluations. The ENDF/B-VI standards evaluation procedure is outlined, and preliminary simultaneous evaluation and R-matrix results are presented. 16 refs., 7 figs.

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

1985-01-01

457

Sensitivity of reaction cross sections to halo nucleus density distributions  

NASA Astrophysics Data System (ADS)

In order to clear up the sensitivity of the nucleus-nucleus reaction cross sections ? R to the nuclear matter distributions in exotic halo nuclei, we have calculated the values of ? R for scattering of 6He, 11Li, and 19C nuclei on several nuclear targets at the energy of 0.8 GeV/nucleon. The calculations were performed in the "rigid target" approximation to the Glauber theory, different shapes of the nuclear density distributions in 6He, 11Li, and 19C being assumed.

Alkhazov, G. D.; Sarantsev, V. V.

2014-07-01

458

Measurement of 139La(n,{gamma}) Cross Section  

SciTech Connect

We measured the neutron capture cross section of 139La relative to 197Au in the energy range of 0.6 eV to 9 keV at n{sub T}OF, the neutron time-of-flight facility at CERN. After a description of the experimental apparatus, we discuss data analysis procedures. The data were fitted using R-matrix formalism to extract resonance parameters which, in turn, were used to calculate average level spacings D0 = 268 {+-} 22 eV and D1 < 250 eV, and neutron strength functions S0 = (0.79 {+-} 0.03)x10-4 and S1 = (0.73 {+-} 0.05)x10-4 for s- and p-wave resonances. The data also were used to determine Maxwellian-averaged neutron capture cross sections which, in turn, were used to calculate the 139La abundance synthesized in a stellar model of the main component of the s process.

Terlizzi, R.; Colonna, N.; Marrone, S.; Tagliente, G. [Dipartimento di Fisica, Bari (Italy); Istituto Nazionale di Fisica Nucleare, Bari (Italy); Abbondanno, U.; Fujii, K.; Milazzo, P. M.; Moreau, C. [Istituto Nazionale di Fisica Nucleare, Trieste (Italy); Aerts, G.; Andriamonje, S.; Berthoumieux, E.; Dridi, W.; Gunsing, F.; Pancin, J.; Perrot, L.; Plukis, A. [CEA/Saclay - DSM, Gif-sur-Yvette (France); Alvarez, H.; Duran, I.; Paradela, C. [Universidade de Santiago de Compostela (Spain); Alvarez-Velarde, F. [Centro de Investigaciones Energeticas Medioambientales y Technologicas, Madrid (Spain)] (and others)

2006-03-13

459

Measurement of 173Lu(n,?) Cross Sections at DANCE  

NASA Astrophysics Data System (ADS)

A highly gamma-radioactive target, 3.7 GBq, of 173Lu isotope was placed inside the DANCE array (Detector for Advanced Neutron Capture Experiments) at Los Alamos to study the radiative neutron capture on an unstable isotope. The 173Lu element was produced by naturalHf(p,xn) reactions following by beta-decays at the Isotope Production Facility (IPF). Measurements of radiative neutron capture cross section on 173Lu were achieved at the Los Alamos Neutron Science Center (LANSCE) spallation neutron source facility over the neutron energy range from thermal up to 1 keV. A special configuration was necessary to perform the experiment using the DANCE [1] array due to the high gamma activity of the target. We will report on the target production, the experiment and the results obtained for the radiative neutron capture on 173Lu. The radiative capture cross section was obtained for the first time on this unstable nucleus. Some resonances have been characterized. A comparison with a recent data evaluation is presented.

Roig, O.; Theroine, C.; Ebran, A.; Méot, V.; Bond, E. M.; Bredeweg, T. A.; Couture, A.; Haight, R. C.; Jandel, M.; Nortier, F. M.; O'Donnell, J. M.; Rundberg, R. S.; Taylor, W. A.; Ullmann, J. L.; Vieira, D. J.

2014-05-01

460

Difference cross sections of unpolarized SIDIS with transverse momentum dependence  

NASA Astrophysics Data System (ADS)

Previously we showed that, based only on charge conjugation and isospin invariance of strong interactions, the difference cross sections of hadrons with opposite charge in semi-inclusive deep inelastic scattering (SIDIS) e+N?l+h+X are expressed solely in terms of the valence-quark densities and certain nonsinglet combinations of fragmentation functions (FFs). This allowed us to determine these quantities in a model-independent way. Now we extend this approach to processes when the transverse momentum of the final hadron is measured as well. We show that the difference cross sections of unpolarized SIDIS on proton and deuterium targets, d?Nh+-h-, d?N?+-?- and d?NK+-K-, are expressed solely in terms of the transverse momentum-dependent (TMD) unpolarized valence-quark densities and FFs, and the valence-quark Boer-Mulders and Collins functions. This allows us to determine them separately and study the flavor dependence of the quark transverse momentum. Measurements on the deuterium target, d?dh+-h-, d?d?+-?- and d?dK+-K-, provide three independent measurements for the sum of the TMD valence-quark densities and Boer-Mulders functions: (u1,V+d1,V) and (h1,uV?+h1,dV?).

Christova, Ekaterina

2014-09-01

461

PWR Cross Section Libraries for ORIGEN-ARP  

SciTech Connect

New pressurized water reactor (PWR) cross-section libraries were generated for use with the ORIGEN-ARP depletion sequence in the SCALE nuclear analysis code system. These libraries are based on ENDF/B-VII nuclear data and were generated using the two-dimensional depletion sequence, TRITON/NEWT, in SCALE 6.1. The libraries contain multiple burnup-dependent cross-sections for seven PWR fuel designs, with enrichments ranging from 1.5 to 6 wt% 235U. The burnup range has been extended from the 72 GWd/MTU used in previous versions of the libraries to 90 GWd/MTU. Validation of the libraries using radiochemical assay measurements and decay heat measurements for PWR spent fuel showed good agreement between calculated and experimental data. Verification against detailed TRITON simulations for the considered assembly designs showed that depletion calculations performed in ORIGEN-ARP with the pre-generated libraries provide similar results as obtained with direct TRITON depletion, while greatly reducing the computation time.

McGraw, Carolyn [Texas A& M University; Ilas, Germina [ORNL

2012-01-01

462

Measurement of the total hadronic cross section in tagged ?? reactions  

NASA Astrophysics Data System (ADS)

We present a measurement of the total cross section for ??-->hadrons, with one photon quasireal and the other a spacelike photon of mass squared -Q2. Results are presented as a function of Q2 and the ?? center-of-mass energy W, with the Q2 range extending from 0.2 to 60 GeV2, and W in the range from 2 to 10 GeV. The data were taken with the TPC/Two-Gamma facility at the SLAC e+e- storage ring PEP, which was operated at a beam energy of 14.5 GeV. The cross section exhibits a gentle falloff with increasing W. Its Q2 dependence is shown to be well described by an incoherent sum of vector-meson and pointlike scattering over most of the observed W range. Agreement at high Q2 is improved if a minimum-pT cutoff (motivated by QCD) is imposed on the pointlike contribution.

Aihara, H.; Alston-Garnjost, M.; Avery, R. E.; Barker, A. R.; Bauer, D. A.; Bay, A.; Belcinski, R.; Bingham, H. H.; Bloom, E. D.; Buchanan, C. D.; Caldwell, D. O.; Chao, H.-Y.; Chun, S.-B.; Clark, A. R.; Cowan, G. D.; Crane, D. A.; Dahl, O. I.; Daoudi, M.; Derby, K. A.; Eastman, J. J.; Eberhard, P. H.; Edberg, T. K.; Eisner, A. M.; Erné, F. C.; Fairfield, K. H.; Fridman, A.; Godfrey, G.; Hauptman, J. M.; Ho, C.; Hofmann, W.; Kamae, T.; Kenney, R. W.; Khacheryan, S.; Kofler, R. R.; Lambert, D. J.; Langeveld, W. G.; Layter, J. G.; Lin, W. T.; Linde, F. L.; Loken, S. C.; Lu, A.; Lynch, G. R.; Lys, J. E.; Madaras, R. J.; Magnuson, B. D.; Marsiske, H.; Masek, G. E.; Mathis, L. G.; Maxfield, S. J.; McNeil, R. R.; Miller, E. S.; Nicol, N. A.; Nygren, D. R.; Oddone, P. J.; Oh, H.; Oyang, Y.-T.; Paar, H. P.; Palounek, A. P.; Park, S. K.; Pellett, D. E.; Pripstein, M.; Ronan, M. T.; Ross, R. R.; Rouse, F. R.; Schwitkis, K. A.; Sens, J. C.; Shapiro, G.; Shen, B. C.; Smith, J. R.; Steinman, J. S.; Stephens, R. W.; Stevenson, M. L.; Stork, D. H.; Strauss, M. G.; Sullivan, M. K.; Takahashi, T.; Toutounchi, S.; Vandalen, G. J.; van Tyen, R.; Vernon, W.; Wagner, W.; Wang, E. M.; Wang, Y.-X.; Wenzel, W. A.; Wolf, Z. R.; Yamamoto, H.; Yellin, S. J.; Yost, G. P.; Zapalac, G.; Zeitlin, C.

1990-05-01

463

Momentum transfer cross sections for the heavy noble gases  

NASA Astrophysics Data System (ADS)

We have used our relativistic optical potential method [1] to calculate the momentum transfer cross sections for Ar, Kr and Xe from threshold to 1000 eV. The target ground state as well as the open excited and ionization channels used in the optical potential have been calculated using the MCDF program [2]. We have included 17 excitation channels for Ar, 26 for Kr and 15 for Xe. In the ionization channels, ionization of the outer p, s and d shells were included for Kr and Xe while for Ar all electrons were allowed to be ionized. Comparisons with previous calculations and experimental measurements will be included. We also include analytic fits to our cross sections to aid in plasma modelling studies. [4pt] [1] S. Chen, R. P. McEachran and A. D. Stauffer, J. Phys. B 41 025201 (2008) [0pt] [2] I. P. Grant, B. J. McKenzie, P. H. Norrington, D. F. Mayers and N. C. Pyper, Comput. Phys. Commun. 21 207 (1980)

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

2012-10-01

464

Jet Cross Sections in D* Photoproduction with ZEUS  

NASA Astrophysics Data System (ADS)

Charm photoproduction in D* photoproduction have been studied using 78.6 pb-1 of data collected by the ZEUS detector. The measurement of inclusive jet cross section with a D* in the final state was performed in the kinematic region, Q2 < 1 GeV, 130 < W < 280 GeV, pTD* > 3 GeV, |?D*| < 1.5, ETjet > 6 GeV and -1.5 < ?jet < 2.4. Differential cross sections as a function of ETjet and ?jet were compared to the NLO QCD predictions. There is a general agreement with the NLO QCD preditions. In addition to above requirements, a dijet sub-sample having at least two jets with ETjet > 6 GeV and the leading jet with ETjet > 7 GeV was used to measure dijet correlations. Dijet correlations are compared to the NLO QCD predictions and leading-order (LO) Monte Carlo (MC) models with parton showers (PS). Dijet correlations are described well by the LO+PS models, while the NLO QCD prediction underestimates the measurement in the region where higher-order effects are expected to become significant.

Kohno, Takanori

2005-10-01

465

CROSS SECTION EVALUATIONS FOR ENDF/B-VII.  

SciTech Connect

This is the final report of the work performed under the LANL contract on neutron cross section evaluations for ENDF/B-VII (April 2005-May 2006). The purpose of the contract was to ensure seamless integration of the LANL neutron cross section evaluations in the new ENDF/B-VII library. The following work was performed: (1) LANL evaluated data files submitted for inclusion in ENDF/B-VII were checked and, when necessary, formal formatting errors were corrected. As a consequence, ENDF checking codes, run on all LANL files, do not report any errors that would rise concern. (2) LANL dosimetry evaluations for {sup 191}Ir and {sup 193}Ir were completed to match ENDF requirements for the general purpose library suitable for transport calculations. A set of covariances for both isotopes is included in the ENDF files. (3) Library of fission products was assembled and successfully tested with ENDF checking codes, processed with NJOY-99.125 and simple MCNP calculations. (4) KALMAN code has been integrated with the EMPIRE system to allow estimation of covariances based on the combination of measurements and model calculations. Covariances were produced for 155,157-Gd and also for 6 remaining isotopes of Gd.

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

2006-06-05

466

Actinide Targets for Neutron Cross Section Measurements (C)  

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