Fast multi-core based multimodal registration of 2D cross-sections and 3D datasets
Pielot Rainer
2010-01-01
Full Text Available Abstract Background Solving bioinformatics tasks often requires extensive computational power. Recent trends in processor architecture combine multiple cores into a single chip to improve overall performance. The Cell Broadband Engine (CBE, a heterogeneous multi-core processor, provides power-efficient and cost-effective high-performance computing. One application area is image analysis and visualisation, in particular registration of 2D cross-sections into 3D image datasets. Such techniques can be used to put different image modalities into spatial correspondence, for example, 2D images of histological cuts into morphological 3D frameworks. Results We evaluate the CBE-driven PlayStation 3 as a high performance, cost-effective computing platform by adapting a multimodal alignment procedure to several characteristic hardware properties. The optimisations are based on partitioning, vectorisation, branch reducing and loop unrolling techniques with special attention to 32-bit multiplies and limited local storage on the computing units. We show how a typical image analysis and visualisation problem, the multimodal registration of 2D cross-sections and 3D datasets, benefits from the multi-core based implementation of the alignment algorithm. We discuss several CBE-based optimisation methods and compare our results to standard solutions. More information and the source code are available from http://cbe.ipk-gatersleben.de. Conclusions The results demonstrate that the CBE processor in a PlayStation 3 accelerates computational intensive multimodal registration, which is of great importance in biological/medical image processing. The PlayStation 3 as a low cost CBE-based platform offers an efficient option to conventional hardware to solve computational problems in image processing and bioinformatics.
Bock, David C; Kirshenbaum, Kevin C; Wang, Jiajun; Zhang, Wei; Wang, Feng; Wang, Jun; Marschilok, Amy C; Takeuchi, Kenneth J; Takeuchi, Esther S
2015-06-24
When electroactive nanomaterials are fully incorporated into an electrode structure, characterization of the crystallite sizes, agglomerate sizes, and dispersion of the electroactive materials can lend insight into the complex electrochemistry associated with composite electrodes. In this study, composite magnetite electrodes were sectioned using ultramicrotome techniques, which facilitated the direct observation of crystallites and agglomerates of magnetite (Fe3O4) as well as their dispersal patterns in large representative sections of electrode, via 2D cross sectional analysis by Transmission Electron Microscopy (TEM). Further, the electrochemistry of these electrodes were recorded, and Transmission X-ray Microscopy (TXM) was used to determine the distribution of oxidation states of the reduced magnetite. Unexpectedly, while two crystallite sizes of magnetite were employed in the production of the composite electrodes, the magnetite agglomerate sizes and degrees of dispersion in the two composite electrodes were similar to each other. This observation illustrates the necessity for careful characterization of composite electrodes, in order to understand the effects of crystallite size, agglomerate size, and level of dispersion on electrochemistry. PMID:26024206
geomIO: A tool for geodynamicists to turn 2D cross-sections into 3D geometries
Baumann, Tobias; Bauville, Arthur
2016-04-01
In numerical deformation models, material properties are usually defined on elements (e.g., in body-fitted finite elements), or on a set of Lagrangian markers (Eulerian, ALE or mesh-free methods). In any case, geometrical constraints are needed to assign different material properties to the model domain. Whereas simple geometries such as spheres, layers or cuboids can easily be programmed, it quickly gets complex and time-consuming to create more complicated geometries for numerical model setups, especially in three dimensions. geomIO (geometry I/O, http://geomio.bitbucket.org/) is a MATLAB-based library that has two main functionalities. First, it can be used to create 3D volumes based on series of 2D vector drawings similar to a CAD program; and second, it uses these 3D volumes to assign material properties to the numerical model domain. The drawings can conveniently be created using the open-source vector graphics software Inkscape. Adobe Illustrator is also partially supported. The drawings represent a series of cross-sections in the 3D model domain, for example, cross-sectional interpretations of seismic tomography. geomIO is then used to read the drawings and to create 3D volumes by interpolating between the cross-sections. In the second part, the volumes are used to assign material phases to markers inside the volumes. Multiple volumes can be created at the same time and, depending on the order of assignment, unions or intersections can be built to assign additional material phases. geomIO also offers the possibility to create 3D temperature structures for geodynamic models based on depth dependent parameterisations, for example the half space cooling model. In particular, this can be applied to geometries of subducting slabs of arbitrary shape. Yet, geomIO is held very general, and can be used for a variety of applications. We present examples of setup generation from pictures of micro-scale tectonics and lithospheric scale setups of 3D present-day model
Shen Guang-Xian; Linghu Rong-Feng; Wang Rong-Kai; Yang Xiang-Dong
2007-01-01
In this paper, close-coupling method was applied to the He-H2(D2,T2) system, and the first vibrational excitation differences of these partial wave cross sections, this paper have obtained the change rules of the partial wave cross sections with increases of quantum number, and with change of reduced mass of system. Based on the calculation,influence on the partial wave cross sections brought by the variations in the reduced mass of systems and in the relative kinetic energy of incident atoms is discussed.
ZZ DLC-2D/100G, 100 Neutron-Group Cross-Section Library by SUPERTOG Calculation for ANISN, DOT
1 - Nature of physical problem solved: Format: ANISN, DOT or DTF-4; Number of groups: 100; Nuclides: H, D, He, He-3, Li-6, Li-7, Be-9, B-10, B-11, C-12, N-14, O-16, Na-23, Mg, Al-27, Si, Cl, K, Ca, V, Cr, Mn-55, Fe, Co-59, Ni, Cu, Cu-63, Cu-65, Nb, Mo, Ag-107, Xe-135, Cs-133, Sm-149, Eu-151, Eu-153, Gd, Dy-164, Lu-175, Lu-176, Ta-181, Ta-182, W-182, W-183, W-184, W-186, Re-185, Re-187, Au-197, Pb, Th-232, Pa-233, U-234, U-235, U-238, Pu-238, Pu-239, Pu-240, Pu-241, Pu-242, Am-241, Am-243, and Cm-244. Origin: The nuclides in DLC-2 are those which have been released as category I ENDF/B by the National Neutron Cross Section Center, Brookhaven National Laboratory. Weighting spectrum: The explicit assumption was made that the flux has the shape of a fission spectrum joined at 0.0674 MeV by a 1/E tail. Neutron transport calculations can be performed with DLC-2 data. Since the data are intended for use in multigroup discrete-ordinates or Monte Carlo transport codes which treat anisotropic scattering, possible cross section angular expansion is limited only by the options available in the particular code used. Specifically, the retrieval program manipulates DLC-2 such that it conforms to input requirements of the ANISN, DOT, or DTF-4 codes, or any computer code using data in the ANISN or DTF-4 format. The nuclides in DLC-2 are those which have been released as category I ENDF/B by the National Neutron Cross Section Center, Brookhaven National Laboratory. The library contains data for H, D, He, 3-He, 6-Li, 7-Li, 9-Be, 10-B, 11-B, 12-C, 14-N, 16-O, 23-Na, Mg, 27-Al, Si, Cl, K, Ca, V, Cr, 55-Mn, Fe, 59-Co, Ni, Cu, 63-Cu, 65-Cu, Nb, Mo, 107-Ag, 135-Xe, 133-Cs, 149-Sm, 151-Eu, 153-Eu, Gd, 164-Dy, 175-Lu, 176-Lu, 181-Ta, 182-Ta, 182-W, 183-W, 184-W, 186-W, 185-Re, 187-Re, 197-Au, Pb, 232-Th, 233-Pa, 234-U, 235-U, 238-U, 238-Pu, 239-Pu, 240-Pu, 241-Pu, 242-Pu, 241-Am, 243-Am, and 244-Cm. 2 - Method of solution: DLC-2 was generated by SUPERTOG from nuclear data in either point
Graphical abstract: -- Highlights: •LA-ICP-MS mapping to study the distribution of Hg in plant root cross-sections. •Sorption of LA-generated Hg vapour leads to serious memory effects. •Spot analysis with a delay time of 10 s in between spots alleviates memory effects. •Ablation straight through the sample simplifies calibration. •Hg2+ does not cross the endodermal root barrier of maize plants. -- Abstract: A LA-ICP-MS method based on a 213 nm Nd:YAG laser and a quadrupole ICP-MS has been developed for mapping of mercury in root cross-sections of maize (Zea mays L.) to investigate the mechanism of mercury uptake from soil and its potential translocation to the edible parts. Conventional rastering was found to be unusable due to sorption of mercury onto the internal parts of the LA device, giving rising to memory effects resulting in serious loss of resolution and inaccurate quantification. Spot analysis on a virtual grid on the surface of the root sections using washout times of 10 s in between spots greatly alleviated problems related to these memory effects. By ablating straight through the root sections on a poly(methyl methacrylate) support the calibration process was simplified as internal standardization and matrix-matching could be circumvented. Mercury-spiked freeze-drying embedding medium, sectioned similarly to the root sections, was used for the preparation of the standards. Standards and root sections were subjected to spot analysis using the following operational parameters: beam diameter, 15 μm; laser fluence, 2.5 J cm−2; repetition rate, 20 Hz; dwell time, 1 s; acquisition time, 0.1 s. The mercury peaks for standards and roots sections could be consistently integrated for quantification and construction of the 2D mercury maps for the root sections. This approach was successfully used to investigate the mercury distribution in root sections of maize grown in soil spiked to a level of 50 mg kg−1 DW HgCl2. It was found that at given Hg
Debeljak, Marta [Analytical Chemistry Laboratory, National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana (Slovenia); Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna Pot 111, SI-1000 Ljubljana (Slovenia); Elteren, Johannes T. van, E-mail: elteren@ki.si [Analytical Chemistry Laboratory, National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana (Slovenia); Vogel-Mikuš, Katarina [Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna Pot 111, SI-1000 Ljubljana (Slovenia)
2013-07-17
Graphical abstract: -- Highlights: •LA-ICP-MS mapping to study the distribution of Hg in plant root cross-sections. •Sorption of LA-generated Hg vapour leads to serious memory effects. •Spot analysis with a delay time of 10 s in between spots alleviates memory effects. •Ablation straight through the sample simplifies calibration. •Hg{sup 2+} does not cross the endodermal root barrier of maize plants. -- Abstract: A LA-ICP-MS method based on a 213 nm Nd:YAG laser and a quadrupole ICP-MS has been developed for mapping of mercury in root cross-sections of maize (Zea mays L.) to investigate the mechanism of mercury uptake from soil and its potential translocation to the edible parts. Conventional rastering was found to be unusable due to sorption of mercury onto the internal parts of the LA device, giving rising to memory effects resulting in serious loss of resolution and inaccurate quantification. Spot analysis on a virtual grid on the surface of the root sections using washout times of 10 s in between spots greatly alleviated problems related to these memory effects. By ablating straight through the root sections on a poly(methyl methacrylate) support the calibration process was simplified as internal standardization and matrix-matching could be circumvented. Mercury-spiked freeze-drying embedding medium, sectioned similarly to the root sections, was used for the preparation of the standards. Standards and root sections were subjected to spot analysis using the following operational parameters: beam diameter, 15 μm; laser fluence, 2.5 J cm{sup −2}; repetition rate, 20 Hz; dwell time, 1 s; acquisition time, 0.1 s. The mercury peaks for standards and roots sections could be consistently integrated for quantification and construction of the 2D mercury maps for the root sections. This approach was successfully used to investigate the mercury distribution in root sections of maize grown in soil spiked to a level of 50 mg kg{sup −1} DW HgCl{sub 2}. It was
The 3D imaging of the middle ear facilitates better understanding of the patient's anatomy. Cross-sectional slices, however, often allow a more accurate evaluation of anatomical structures, as some detail may be lost through post-processing. In order to demonstrate the advantages of combining both approaches, we performed computed tomography (CT) imaging in two normal and 15 different pathological cases, and the 3D models were correlated to the cross-sectional CT slices. Reconstructed CT datasets were acquired by multi-slice CT. Post-processing was performed using the in-house software ''3D Slicer'', applying thresholding and manual segmentation. 3D models of the individual anatomical structures were generated and displayed in different colours. The display of relevant anatomical and pathological structures was evaluated in the greyscale 2D slices, 3D images, and the 2D slices showing the segmented 2D anatomy in different colours for each structure. Correlating 2D slices to the 3D models and virtual endoscopy helps to combine the advantages of each method. As generating 3D models can be extremely time-consuming, this approach can be a clinically applicable way of gaining a 3D understanding of the patient's anatomy by using models as a reference. Furthermore, it can help radiologists and otolaryngologists evaluating the 2D slices by adding the correct 3D information that would otherwise have to be mentally integrated. The method can be applied to radiological diagnosis, surgical planning, and especially, to teaching. (orig.)
Kalyar, M. A.; Yar, A.; Iqbal, J.; Ali, R.; Baig, M. A.
2016-03-01
We have carried out measurements of absolute photoionization cross sections of the 4p excited levels and oscillator strengths of the 4p→nd Rydberg transitions in potassium using a two-step photo-excitation and ionization technique in conjunction with a thermionic diode ion detector. The measurements were conducted using the linearly polarized laser light and the absolute values of the cross sections from the 4p 2P3/2 and 2P1/2 excited levels have been determined at the ionization threshold as (6.3±0.9) Mb and (5.4±0.8) Mb respectively. In addition, photoionization cross sections have been determined at various ionizing wavelengths above the first ionization threshold to explore different energy regions of the continuum. The oscillator strengths for the 4p 2P1/2→nd 2D3/2 and 4p 2P3/2→nd 2D3/2,5/2 Rydberg transitions have been deduced by using the measured cross sections of the 4p 2P1/2 and 2P3/2 levels at the ionization threshold. The new results are in good agreement with the available theoretical and experimental data.
Maija E Miettinen
Full Text Available OBJECTIVES: Low serum 25-hydroxyvitamin D (25OHD level has been associated with an increased risk of several chronic diseases. Our aim was to determine lifestyle and clinical factors that are associated with 25OHD level and to investigate connection of 25OHD level with metabolic and cardiovascular disease markers. DESIGN: In total, 2868 Finnish men and women aged 45-74 years participated in FIN-D2D population-based health survey in 2007. Participants that had a serum sample available (98.4%; n = 2822 were included in this study. 25OHD was measured with chemiluminescent microparticle immunoassay method. RESULTS: The mean 25OHD level was 58.2 nmol/l in men (n = 1348 and 57.1 nmol/l in women (n = 1474. Mean 25OHD level was lower in the younger age groups than in the older ones (p<0.0001 both in men and women. This study confirmed that low physical activity (p<0.0001 both in men and women, smoking (p = 0.0002 in men and p = 0.03 in women and high BMI (p<0.0001 in women are factors that independently associate with low 25OHD level. Of the metabolic and cardiovascular disease markers high triglyceride concentration (p = 0.02 in men and p = 0.001 in women and high apolipoprotein B/apolipoprotein A1 ratio (p = 0.04 in men and p = 0.03 in women were independently associated with low 25OHD level. CONCLUSIONS: Higher age did not predict lower 25OHD level in this study population of aged 45-74 years which may derive from a healthy life-style of "active pensioners". Low physical activity and smoking came up as independent lifestyle factors associated with low 25OHD level. Defining the molecular mechanisms behind the associations of 25OHD with low physical activity and smoking are important objective in future studies. The association of 25OHD with BMI, high triglyceride concentration and apolipoprotein B/apolipoprotein A1 ratio may be related to the role of vitamin D in inflammation, but more detailed studies are needed.
Minnesota Department of Natural Resources — FEMA Cross Sections are required for any Digital Flood Insurance Rate Map database where cross sections are shown on the Flood Insurance Rate Map (FIRM). Normally...
G. GiacomelliBologna University and INFN
2014-01-01
The measurements of the hadron-hadron total cross sections are the first measurements performed when a new hadron accelerator opens up a new energy region; the measurements were made as function of the incoming beam momentum or c.m. energy and have often been repeated with improved accuracy and finer energy spacing.
Gollapinni, Sowjanya
2016-01-01
The study of neutrino-nucleus interactions has recently received renewed attention due to their importance in interpreting the neutrino oscillation data. Over the past few years, there has been continuous disagreement between neutrino cross section data and predictions due to lack of accurate nuclear models suitable for modern experiments which use heavier nuclear targets. Also, the current short and long-baseline neutrino oscillation experiments focus in the few GeV region where several distinct neutrino processes come into play resulting in complex nuclear effects. Despite recent efforts, more experimental input is needed to improve nuclear models and reduce neutrino interaction systematics which are currently dominating oscillation searches together with neutrino flux uncertainties. A number of new detector concepts with diverse neutrino beams and nuclear targets are currently being developed to provide necessary inputs required for next generation oscillation experiments. This paper summarizes these effor...
Group cross sections calculations
Just a few methods have been developped to compute multigroup cross-sections from ENDF data. We have developped an original method in order to get accuracy and to reduce the number of discretization points in the same time; this is why we have tried to use polynomial integration. In this paper, we describe this method: in the first part, we recall some physical hypothesis generally used to solve the linear Boltzmann equation: that is the frame in which the numerical method has been developped. Polynomial methods are really powerfull only if discretization points are suitably chosen. This choice is explained in the next part of this paper. In conclusion, some numerical results are given to illustrate our method
Diffractive and rising cross sections
The energy dependence of the diffractive component of the proton-proton cross section is discussed and its contribution to the rise of the total cross section at high energies is examined. 17 refs., 9 figs
[Fast neutron cross section measurements
This paper discusses the following topics: 14 MeV pulsed neutron facility; detection and measurement system; 238U capture cross sections at 23 and 964 keV using photon neutron sources; capture cross sections of Au-197 at 23 and 964 keV; and yttrium nuclear cross section measurement
Most of the fission products and a few of the actinides in ENDF/B-V do not have (n,2n) cross sections. A complete set of these cross sections is presented in the multigroup structure defined. These were constructed for future use in the DANDE Code System
XCOM: Photon Cross Sections Database
SRD 8 XCOM: Photon Cross Sections Database (Web, free access) A web database is provided which can be used to calculate photon cross sections for scattering, photoelectric absorption and pair production, as well as total attenuation coefficients, for any element, compound or mixture (Z <= 100) at energies from 1 keV to 100 GeV.
Cross Sections and Lorentz Violation
Colladay, Don; Kostelecky, Alan
2001-01-01
The derivation of cross sections and decay rates in the Lorentz-violating standard-model extension is discussed. General features of the physics are described, and some conceptual and calculational issues are addressed. As an illustrative example, the cross section for the specific process of electron-positron pair annihilation into two photons is obtained.
Measurement of fission cross sections
A review is presented on the recent progress in the experiment of fission cross section measurement, including recent activity in Japan being carried out under the project of nuclear data measurement. (author)
R. Vogt
2007-01-01
We assess the theoretical uncertainties on the total charm cross section. We discuss the importance of the quark mass, the scale choice and the parton densities on the estimate of the uncertainty. We conclude that due to the small charm quark mass, which amplifies the effect of the other parameters in the calculation, the uncertainty on the total charm cross section is difficult to quantify.
Revolutionizing Cross-sectional Imaging
Fan, Yifang; Luo, Liangping; Lin, Wentao; Li, Zhiyu; Zhong, Xin; Shi, Changzheng; Newman, Tony; Zhou, Yi; Lv, Changsheng; Fan, Yuzhou
2014-01-01
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...
Terahertz radar cross section measurements
Iwaszczuk, Krzysztof; Heiselberg, Henning; Jepsen, Peter Uhd
2010-01-01
We perform angle- and frequency-resolved radar cross section (RCS) measurements on objects at terahertz frequencies. Our RCS measurements are performed on a scale model aircraft of size 5-10 cm in polar and azimuthal configurations, and correspond closely to RCS measurements with conventional radar...
Cross sections for nuclear astrophysics
General properties of low-energy cross sections and of reaction rates are presented. We describe different models used in nuclear astrophysics: microscopic models, the potential model, and the R-matrix method. Two important reactions, 7Be(p,γ)8B and 12C(α,γ)16O, are then briefly discussed. (author)
Metonymy and Cross Section Demand
Evstigneev, Igor V.; Hildenbrand, Werner; Jerison, Michael
1996-01-01
Cross section consumer expenditure data are frequently used to make conclusions about consumer demand behavior. Such conclusions, however, can only be justified 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 then exploited by Hardle, Hildenbrand and Jerison when analyzing the monotonicity property of aggregate demand functions. The purpose of the present paper is to exa...
Wind Turbine Radar Cross Section
David Jenn; Cuong Ton
2012-01-01
The radar cross section (RCS) of a wind turbine is a figure of merit for assessing its effect on the performance of electronic systems. In this paper, the fundamental equations for estimating the wind turbine clutter signal in radar and communication systems are presented. Methods of RCS prediction are summarized, citing their advantages and disadvantages. Bistatic and monostatic RCS patterns for two wind turbine configurations, a horizontal axis three-blade design and a vertical axi...
New activation cross section data
New nuclear cross section libraries (known as USACT92) have been created for activation calculations. A point-wise file was created from merging the previous version of the activation library, the U.S. Nuclear Data Library (ENDF/B-VI), and the European Activation File (EAF-2). 175 and 99 multi-group versions were also created. All the data are available at the National Energy Research Supercomputer Center
Microscopic cross sections: An utopia?
Hilaire, S. [CEA Bruyeres-le-Chatel, DIF 91 (France); Koning, A.J. [Nuclear Research and Consultancy Group, PO Box 25, 1755 ZG Petten (Netherlands); Goriely, S. [Institut d' Astronomie et d' Astrophysique, Universite Libre de Bruxelles, Campus de la Plaine, CP 226, 1050 Brussels (Belgium)
2010-07-01
The increasing need for cross sections far from the valley of stability poses a challenge for nuclear reaction models. So far, predictions of cross sections have relied on more or less phenomenological approaches, depending on parameters adjusted to available experimental data or deduced from systematical relations. While such predictions are expected to be reliable for nuclei not too far from the experimentally known regions, it is clearly preferable to use more fundamental approaches, based on sound physical bases, when dealing with very exotic nuclei. Thanks to the high computer power available today, all major ingredients required to model a nuclear reaction can now be (and have been) microscopically (or semi-microscopically) determined starting from the information provided by a nucleon-nucleon effective interaction. We have implemented all these microscopic ingredients in the TALYS nuclear reaction code, and we are now almost able to perform fully microscopic cross section calculations. The quality of these ingredients and the impact of using them instead of the usually adopted phenomenological parameters will be discussed. (authors)
[Fast neutron cross section measurements
In this report, we outline the progress achieved in two distinct under the DOE-sponsored cross section project: the initial results obtained from the pulsed 14 MeV neutron facility, and a cooperative effort with Argonne National Laboratory in the measurement of fast neutron cross sections in yttrium. In the 14 MeV neutron laboratory, this year has seen the maturation of the project into one in which initial scattering measurements are now underway. We have improved the accelerator and ion source in several significant ways, so that neutron intensities have now been proven to be adequate for our series of elastic scattering angular distribution measurements outlined in our initial proposal of two years ago. We have successfully tested all components of the time-of-flight spectrometer and recorded initial neutron spectra from the ring targets that we have obtained for our first angular distribution measurements. Examples of the time-of-flight spectra that have been obtained are given later in this report. At the present time, the accelerator is operating with the highest degree of reliability that we have experienced since installing the pulsing system. Improvements made over the past year have not only increased the available neutron intensity, but also increased our capability to deal with inevitable component failures that require repair or replacement. The measurements carried out in conjunction with Argonne have contributed significantly to the available database on fast neutron interactions in yttrium. Results indicate that the cross section for the 89 Y(n,p)89Sr reaction is substantially higher than represented in ENDF/B-VI
Wind Turbine Radar Cross Section
David Jenn
2012-01-01
Full Text Available The radar cross section (RCS of a wind turbine is a figure of merit for assessing its effect on the performance of electronic systems. In this paper, the fundamental equations for estimating the wind turbine clutter signal in radar and communication systems are presented. Methods of RCS prediction are summarized, citing their advantages and disadvantages. Bistatic and monostatic RCS patterns for two wind turbine configurations, a horizontal axis three-blade design and a vertical axis helical design, are shown. The unique electromagnetic scattering features, the effect of materials, and methods of mitigating wind turbine clutter are also discussed.
Acoustical cross-talk in row–column addressed 2-D transducer arrays for ultrasound imaging
Christiansen, Thomas Lehrmann; Jensen, Jørgen Arendt; Thomsen, Erik Vilain
2015-01-01
The acoustical cross-talk in row–column addressed 2-D transducer arrays for volumetric ultrasound imaging is investigated. Experimental results from a 2.7 MHz, λ/2-pitch capacitive micromachined ultrasonic transducer (CMUT) array with 62 rows and 62 columns are presented and analyzed in the...
[Fast neutron cross section measurements
In the 14 MeV Neutron Laboratory, we have continued the development of a facility that is now the only one of its kind in operation in the United States. We have refined the klystron bunching system described in last year's report to the point that 1.2 nanosecond pulses have been directly measured. We have tested the pulse shape discrimination capability of our primary NE 213 neutron detector. We have converted the RF sweeper section of the beamline to a frequency of 1 MHz to replace the function of the high voltage pulser described in last year's report which proved to be difficult to maintain and unreliable in its operation. We have also overcome several other significant experimental difficulties, including a major problem with a vacuum leak in the main accelerator column. We have completed additional testing to prove the remainder of the generation and measurement systems, but overcoming some of these experimental difficulties has delayed the start of actual data taking. We are now in a position to begin our first series of ring geometry elastic scattering measurements, and these will be underway before the end of the current contract year. As part of our longer term planning, we are continuing the conceptual analysis of several schemes to improve the intensity of our current pulsed beam. These include the provision of a duoplasmatron ion source and/or the provision of preacceleration bunching. Additional details are given later in this report. A series of measurements were carried out at the Tandem Dynamatron Facility involving the irradiation of a series of yttrium foils and the determination of activation cross sections using absolute counting techniques. The experimental work has been completed, and final analysis of the cross section data will be completed within several months
Zuo, M.; Smith, Steven J.; Chutjian, A.; Williams, I. D.; Tayal, S. S.; Mclaughlin, Brendan M.
1995-01-01
Experimental and theoretical excitation cross sections are reported for the first forbidden transition 4S(O) -- 2S(2)2p(3) 2D(O) (lambda-lambda 3726, 3729) and the first allowed (resonance) transition 4S(O) -- 2s2p(4) 4P(lambda-833) in O II. Use is made of electron energy loss and merged-beams methods. The electron energy range covered is 3.33 (threshold) to 15 eV for the S -- D transition, and 14.9 (threshold) to 40 eV for the S -- P transition. Care was taken to assess and minimize the metastable fraction of the O II beam. An electron mirror was designed and tested to reflect inelastically backscattered electrons into the forward direction to account for the full range of polar scattering angles. Comparisons are made between present experiments and 11-state R-matrix calculations. Calculations are also presented for the 4S(O) -- 2s(2)2p(3)2P(O) (lambda-2470) transition.
Liao, C.; Chutjian, A.; Hitz, D.; Tayal, S. S.
1997-01-01
Experimental and theoretical collisional excitation cross sections are reported for the transitions 3s(exp 2)3p(exp 3)4S(exp o) approaches 3s(exp 2)3p(exp 3) 2D(exp o), 2P(exp o), and 3s3P(exp 4) 4P in S II. The transition wavelengths (energies) are 6716 A (1.85 eV), 4069 A (3.05 eV), and 1256 A (9.87 eV), respectively. In the experiments, use is made of the energy-loss merged-beams method. The metastable fraction of the S II beam was assessed and minimized. The contribution of elastically scattered electrons was reduced by the use of a lowered solenoidal magnetic field and a modulated radio-frequency voltage on the analyzing plates and by retarding grids to reject the elastically scattered electrons with larger Larmor radii. For each transition, comparisons are made among experiments, the new 19 state R-matrix calculation, and three other close-coupling calculations.
Electron-Impact Ionization Cross Section Database
SRD 107 Electron-Impact Ionization Cross Section Database (Web, free access) This is a database primarily of total ionization cross sections of molecules by electron impact. The database also includes cross sections for a small number of atoms and energy distributions of ejected electrons for H, He, and H2. The cross sections were calculated using the Binary-Encounter-Bethe (BEB) model, which combines the Mott cross section with the high-incident energy behavior of the Bethe cross section. Selected experimental data are included.
Aeroelastic Stability of a 2D Airfoil Section equipped with a Trailing Edge Flap
Bergami, Leonardo
2008-01-01
Recent studies conclude that important reduction of the fatigue loads encountered by a wind turbine blade can be achieved using a deformable trailing edge control system. The focus of the current work is to determine the effect of this flap-like system on the aeroelastic stability of a 2D airfoil section. A simulation tool is implemented to predict the flow speed at which a flap equipped section may become unstable, either due to flutter or divergence. First, the stability limits of the airfo...
Aeroelastic Stability of a 2D Airfoil Section equipped with a Trailing Edge Flap
Bergami, Leonardo
Recent studies conclude that important reduction of the fatigue loads encountered by a wind turbine blade can be achieved using a deformable trailing edge control system. The focus of the current work is to determine the effect of this flap-like system on the aeroelastic stability of a 2D airfoil...... section. A simulation tool is implemented to predict the flow speed at which a flap equipped section may become unstable, either due to flutter or divergence. First, the stability limits of the airfoil without flap are determined, and, in the second part of the work, a deformable trailing edge flap is...
Evaluation of cross section for 103Rh
A completely new evaluation for the neutron cross sections is presented. The experimental data mainly referred to EXFOR, and the recommended cross sections are compared with ENDF/B-6, BROND-2, JENDL-3.2 and JEF-2
Isotope effect in dissociative electron attachment cross sections in acetylene
May, Olivier; Fedor, Juraj; Allan, Michael, E-mail: olivier.may@unifr.c [Department of Chemistry, University of Fribourg, Chemin du Muse 9, 1700 Fribourg (Switzerland)
2009-11-01
We present absolute cross section measurement of dissociative electron attachment to C{sub 2}H{sub 2} and C{sub 2}D{sub 2}. The C{sub 2}H{sup -}/ C{sub 2}D{sup -} band at 3 eV shows pronounced isotope effect with the cross section for C{sub 2}H{sub 2} being 14.7 times larger than that for C{sub 2}D{sub 2}. The light fragments H{sup -} and D{sup -} dominate the second dissociative electron attachment band around 8 eV. These bands exhibit much weaker isotope effects which is in agreement with their assignment to Feshbach resonances.
Photoproduction total cross section and shower development
Cornet, F.; García Canal, C. A.; Grau, A.; Pancheri, G.; Sciutto, S. J.
2015-12-01
The total photoproduction cross section at ultrahigh energies is obtained using a model based on QCD minijets and soft-gluon resummation and the ansatz that infrared gluons limit the rise of total cross sections. This cross section is introduced into the Monte Carlo system AIRES to simulate extended air showers initiated by cosmic ray photons. The impact of the new photoproduction cross section on common shower observables, especially those related to muon production, is compared with previous results.
Photoproduction total cross section and shower development
Cornet, F; Grau, A; Pancheri, G; Sciutto, S J
2015-01-01
The total photoproduction cross section at ultra-high energies is obtained using a model based on QCD minijets and soft-gluon resummation and the ansatz that infrared gluons limit the rise of total cross sections. This cross section is introduced into the Monte Carlo system AIRES to simulate extended air-showers initiated by cosmic ray photons. The impact of the new photoproduction cross section on common shower observables, especially those related to muon production, is compared with previous results.
JENDL gas-production cross section file
The JENDL gas-production cross section file was compiled by taking cross-section data from JENDL-3 and by using the ENDF-5 format. The data were given to 23 nuclei or elements in light nuclei and structural materials. Graphs of the cross sections and brief description on their evaluation methods are given in this report. (author)
2D Direction of Arrival Estimation for Cross Array in the Presence of Mutual Coupling
2014-01-01
This paper proposes a new method for cross array to estimate two-dimensional direction of arrival (2-D DOA) in the presence of mutual coupling. In this method, the array elements which are affected by the same mutual coupling are chosen on x-axis and z-axis, respectively. Then a new matrix is constructed with the proper entries of cross covariance matrix of the chosen elements outputs on x-axis and z-axis. Propagation method (PM) and rotational invariance techniques for uniform linear array (...
[Fast neutron cross section measurements
From its inception, the Nuclear Data Project at the University of Michigan has concentrated on two major objectives: (1) to carry out carefully controlled nuclear measurements of the highest possible reliability in support of the national nuclear data program, and (2) to provide an educational opportunity for students with interests in experimental nuclear science. The project has undergone a successful transition from a primary dependence on our photoneutron laboratory to one in which our current research is entirely based on a unique pulsed 14 MeV fast neutron facility. The new experimental facility is unique in its ability to provide nanosecond bursts of 14 MeV neutrons under conditions that are ''clean'' and as scatter-free as possible, and is the only one of its type currently in operation in the United States. It has been designed and put into operation primarily by graduate students, and has met or exceeded all of its important initial performance goals. We have reached the point of its routine operation, and most of the data are now in hand that will serve as the basis for the first two doctoral dissertations to be written by participating graduate students. Our initial results on double differential neutron cross sections will be presented at the May 1993 Fusion Reactor Technology Workshop. We are pleased to report that, after investing several years in equipment assembly and optimization, the project has now entered its ''data production'' phase
SNL RML recommended dosimetry cross section compendium
Griffin, P.J.; Kelly, J.G.; Luera, T.F. [Sandia National Labs., Albuquerque, NM (United States); VanDenburg, J. [Science and Engineering Associates, Inc., Albuquerque, NM (United States)
1993-11-01
A compendium of dosimetry cross sections is presented for use in the characterization of fission reactor spectrum and fluence. The contents of this cross section library are based upon the ENDF/B-VI and IRDF-90 cross section libraries and are recommended as a replacement for the DOSCROS84 multigroup library that is widely used by the dosimetry community. Documentation is provided on the rationale for the choice of the cross sections selected for inclusion in this library and on the uncertainty and variation in cross sections presented by state-of-the-art evaluations.
Recent fission cross section standards measurements
Wasson, O.A.
1985-01-01
The /sup 235/U(n,f) reaction is the standard by which most neutron induced fission cross sections are determined. Most of these cross sections are derived from relatively easy ratio measurements to /sup 235/U. However, the more difficult /sup 235/U(n,f) cross section measurements require the use of advanced neutron detectors for the determination of the incident neutron fluence. Examples of recent standard cross section measurements are discussed, various neutron detectors are described, and the status of the /sup 235/U(n,f) cross section standard is assessed. 23 refs., 8 figs., 4 tabs.
Recent fission cross section standards measurements
The 235U(n,f) reaction is the standard by which most neutron induced fission cross sections are determined. Most of these cross sections are derived from relatively easy ratio measurements to 235U. However, the more difficult 235U(n,f) cross section measurements require the use of advanced neutron detectors for the determination of the incident neutron fluence. Examples of recent standard cross section measurements are discussed, various neutron detectors are described, and the status of the 235U(n,f) cross section standard is assessed. 23 refs., 8 figs., 4 tabs
Background-cross-section-dependent subgroup parameters
A new set of subgroup parameters was derived that can reproduce the self-shielded cross section against a wide range of background cross sections. The subgroup parameters are expressed with a rational equation which numerator and denominator are expressed as the expansion series of background cross section, so that the background cross section dependence is exactly taken into account in the parameters. The advantage of the new subgroup parameters is that they can reproduce the self-shielded effect not only by group basis but also by subgroup basis. Then an adaptive method is also proposed which uses fitting procedure to evaluate the background-cross-section-dependence of the parameters. One of the simple fitting formula was able to reproduce the self-shielded subgroup cross section by less than 1% error from the precise evaluation. (author)
Vertically stabilized elongated cross-section tokamak
Sheffield, George V.
1977-01-01
This invention provides a vertically stabilized, non-circular (minor) cross-section, toroidal plasma column characterized by an external separatrix. To this end, a specific poloidal coil means is added outside a toroidal plasma column containing an endless plasma current in a tokamak to produce a rectangular cross-section plasma column along the equilibrium axis of the plasma column. By elongating the spacing between the poloidal coil means the plasma cross-section is vertically elongated, while maintaining vertical stability, efficiently to increase the poloidal flux in linear proportion to the plasma cross-section height to achieve a much greater plasma volume than could be achieved with the heretofore known round cross-section plasma columns. Also, vertical stability is enhanced over an elliptical cross-section plasma column, and poloidal magnetic divertors are achieved.
Cross section inference based on PDE-constrained optimization
The problem of inferring the material properties (cross section) in noninvasive inverse problems is formulated as a PDE-constrained optimization problem, where the governing laws of the chosen physics act as a constraint. A standard Lagrangian functional, containing the objective function to be minimized and the constraints to satisfy, is formed. The resolution of the optimality conditions lead to a nonlinear problem that is tackled with a Gauss-Newton procedure. Results of cross section inference are presented in the case of 1-group 2D neutron diffusion theory. (authors)
Measurements of neutron capture cross sections
A review of measurement techniques for the neutron capture cross sections is presented. Sell transmission method, activation method, and prompt gamma-ray detection method are described using examples of capture cross section measurements. The capture cross section of 238U measured by three different prompt gamma-ray detection methods (large liquid scintillator, Moxon-Rae detector, and pulse height weighting method) are compared and their discrepancies are resolved. A method how to derive the covariance is described. (author)
Compilation of cross-sections. Pt. 2
A compilation of integrated cross-sections for hadronic reactions is presented. This is an updated version of CERN/HERA 79-1, 79-2, 79-3. It contains all data published up to the beginning of 1982, but some more recent data have also been included. Plots of the cross sections versus incident laboratory momentum are also given. This volume II contains cross-sections for K+ and K- induced reactions. (orig.)
Cross Sections for Electron Collisions with Methane
Song, Mi-Young, E-mail: mysong@nfri.re.kr; Yoon, Jung-Sik [Plasma Technology Research Center, National Fusion Research Institute, 814-2 Osikdo-dong, Gunsan, Jeollabuk-do 573-540 (Korea, Republic of); Cho, Hyuck [Department of Physics, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Itikawa, Yukikazu [Institute of Space and Astronautical Science, Sagamihara 252-5210 (Japan); Karwasz, Grzegorz P. [Faculty of Physics, Astronomy and Applied Informatics, University Nicolaus Copernicus, Grudziadzka 5, 87100 Toruń (Poland); Kokoouline, Viatcheslav [Department of Physics, University of Central Florida, Orlando, Florida 32816 (United States); Nakamura, Yoshiharu [6-1-5-201 Miyazaki, Miyamae, Kawasaki 216-0033 (Japan); Tennyson, Jonathan [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)
2015-06-15
Cross section data are compiled from the literature for electron collisions with methane (CH{sub 4}) molecules. Cross sections are collected and reviewed for total scattering, elastic scattering, momentum transfer, excitations of rotational and vibrational states, dissociation, ionization, and dissociative attachment. The data derived from swarm experiments are also considered. For each of these processes, the recommended values of the cross sections are presented. The literature has been surveyed through early 2014.
Ion and electron impact ionization cross sections
Several current projects are described in which cross sections of interest to radiation physics are being measured. These include total and multiple ionization cross sections for protons on several gases covering a wide energy range, the measurement of cross sections differential in the angle and energy of ejected electrons for several gases including water vapor, and a review of proton ionization data. The work on water vapor has also been extended to electron and neutral hydrogen impact. A brief discussion is also given of some systematics of ionization cross sections. 13 references
Improved Empirical Parametrization of Fragmentation Cross Sections
Sümmerer, Klaus
2012-01-01
A new version is proposed for the universal empirical formula, EPAX, which describes fragmentation cross sections in high-energy heavy-ion reactions. The new version, EPAX 3, can be shown to yield cross sections that are in better agreement with experimental data for the most neutron-rich fragments than the previous version. At the same time, the very good agreement of EPAX 2 with data on the neutron-deficient side has been largely maintained. Comparison with measured cross sections show that the bulk of the data is reproduced within a factor of about 2, for cross sections down to the pico-barn range.
Damage cross section library (DAMSIG77)
The damage cross sections of various materials are converted to a data format, which can be used as library for the program SAND-II. The materials available in this library are graphite, stainless steel, aluminium, silicium, chromium, iron, nickel, copper, zirconium, molybdenum, tungsten, vanadium and niobium. A number of these materials have more than one cross section set, originating from different evaluations. Cross sections for some activation reactions, commonly used to determine thermal and fast neutron fluences have been included too. Moreover, also some artificial cross sections are introduced in this library which can be used to derive values for some physical quantities which may characterize neutron spectra
Compilation of cross-sections. Pt. 4
This is the fourth volume in our series of data compilations on integrated cross-sections for weak, electromagnetic, and strong interaction processes. This volume covers data on reactions induced by photons, neutrinos, hyperons, and KL0. It contains all data published up to June 1986. Plots of the cross-sections versus incident laboratory momentum are also given. (orig.)
Compilation of cross-sections. Pt. 1
A compilation of integral cross-sections for hadronic reactions is presented. This is an updated version of CERN/HERA 79-1, 79-2, 79-3. It contains all data published up to the beginning of 1982, but some more recent data have also been included. Plots of the cross-sections versus incident laboratory momentum are also given. (orig.)
Nucleon-XcJ Dissociation Cross Sections
冯又层; 许晓明; 周代翠
2002-01-01
Nucleon-XcJ dissociation cross sections are calculated in a constituent interexchange model in which quark-quark potential is derived from the Buchmüller-Tye quark-anti-quark potential. These new cross sections for dominant reaction channels depend on the centre-of-mass energy of the nucleon and the charmonium.
Fission cross section calculations for Pa isotopes
Based on the recently measured cross-section values for the neutron-induced fission of 231Pa and our experience gained with other isotopes, new self consistent neutron cross section calculations for n+231Pa have been performed up to 30 MeV. The results are quite different to the existing evaluations, especially above the first chance fission threshold. (authors)
Comparative analysis among several cross section sets
Critical parameters were calculated using the one dimensional multigroup transport theory for several cross section sets. Calculations have been performed for water mixtures of uranium metal, plutonium metal and uranium-thorium oxide, and for metallics systems, to determine the critical dimensions of geometries (sphere and cylinder). For this aim, the following cross section sets were employed: 1) multigroup cross section sets obtained from the GAMTEC-II code; 2) the HANSEN-ROACH cross section sets; 3) cross section sets from the ENDF/B-IV, processed by the NJOY code. Finally, we have also calculated the corresponding critical radius using the one dimensional multigroup transport DTF-IV code. The numerical results agree within a few percent with the critical values obtained in the literature (where the greatest discrepancy occured in the critical dimensions of water mixtures calculated with the values generated by the NJOY code), a very good results in comparison with similar works. (Author)
Photoproton cross section for 17O
The measurement of the 17O(γ,p)16N reaction from threshold to an excitation energy of 44 MeV is presented. These results have been summed with the previously measured total photoneutron cross section to provide an approximation to the total photoabsorption cross section of 17O. The magnitude of the 17O photoabsorption cross section at the peak of the Giant Dipole Resonance is considerably less than the equivalent value for the photoabsorption cross sections of 16O and 18O. In addition, the integrated total photoabsorption cross section for 17O (up to 40 MeV) exhausts only about 58% of the sum rule; the values for the cases of 16O and 18O are significantly larger than this. The present data along with results from other reaction channels of this nucleus, were used to make spin, parity, and isospin assignments for several states in 17O. 48 refs., 4 tabs., 7 figs
Recommended evaluation procedure for photonuclear cross section
Lee, Young-Ouk; Chang, Jonghwa; Fukahori, Tokio [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment
1998-03-01
In order to generate photonuclear cross section library for the necessary applications, data evaluation is combined with theoretical evaluation, since photonuclear cross sections measured cannot provide all necessary data. This report recommends a procedure consisting of four steps: (1) analysis of experimental data, (2) data evaluation, (3) theoretical evaluation and, if necessary, (4) modification of results. In the stage of analysis, data obtained by different measurements are reprocessed through the analysis of their discrepancies to a representative data set. In the data evaluation, photonuclear absorption cross sections are evaluated via giant dipole resonance and quasi-deutron mechanism. With photoabsorption cross sections from the data evaluation, theoretical evaluation is applied to determine various decay channel cross sections and emission spectra using equilibrium and preequilibrium mechanism. After this, the calculated results are compared with measured data, and in some cases the results are modified to better describe measurements. (author)
Aeroservoelastic stability of a 2D airfoil section equipped with a trailing edge flap
Bergami, Leonardo
2008-11-15
Recent studies conclude that important reduction of the fatigue loads encountered by a wind turbine blade can be achieved using a deformable trailing edge control system. The focus of the current work is to determine the effect of this flap-like system on the aeroelastic stability of a 2D airfoil section. A simulation tool is implemented to predict the flow speed at which a flap equipped section may become unstable, either due to flutter or divergence. First, the stability limits of the airfoil without flap are determined, and, in the second part of the work, a deformable trailing edge flap is applied. Stability is investigated for the uncontrolled flap, and for three different control algorithms. The three controls are tuned for fatigue load alleviation and they are based on, respectively, measurement of the heave displacement and velocity, measurement of the local angle of attack, measurement of the pressure difference between the two sides of the airfoil. The stability of the aeroservoelastic system in a defined equilibrium state, and for a given flow speed, is then determined by solving an eigenvalue problem. Results show that the trailing edge control system modifies significantly the stability limits of the section. In the investigated case, increased flutter limits are reported when the elastic flap is left without control, whereas, by applying any of the control algorithms, the flutter velocity is reduced. Nevertheless, only in the heave control case the flutter limit becomes critically close to normal operation flow speeds. Furthermore, a marked dependence of the stability limits on the control gain is also observed and, by tuning the gain parameters, flutter and divergence can be suppressed for flow speed even above the flutter velocity encountered with uncontrolled flap. (author)
Photoneutron cross sections for the silicon isotopes
The photoneutron cross sections for 28Si, 29Si, and 30Si have been measured up to 33 MeV with monoenergetic photons from the annihilation in flight of fast positrons, using neutron multiplicity counting. Average neutron energies were obtained simultaneously with the cross-section data by the ring-ratio technique. The giant dipole resonance for 28Si and 30Si exhibit appreciable fragmentation; that for 29Si does not. The (γ,2n) cross section for 30Si is large; that for 29Si is consistent with zero. The (γ,1n) cross section for 30Si decreases sharply with energy to values near zero as the (γ,2n) cross section grows, then increases to appreciable values as the (γ,2n) cross section diminishes; this extreme behavior, although never seen before, is attributable to the competition between the (γ,n), (γ,2n), and (γ,pn) decay channels. Some properties of the isospin components of the giant resonance are inferred. Other features of the data, including the integrated cross sections, are found to be similar in many respects to corresponding results for the oxygen and magnesium isotopes. The 28Si nucleus is found to be a better core for 29Si and 30Si than might have been expected from previous descriptions of its open-shell character
The 42Ca photoneutron cross section
The measurement of the 42Ca(γ,nsub(t)) is reported here over the energy range 10.5 - 28 MeV. Bremsstrahlung radiation from the 35 MeV Betatron at this University was used to measure a yield curve of photoneutrons, from which the (γ,nsub(t)) cross section was derived. Since proton and neutron emission are the major decay modes of the giant dipole resonance, summing these cross sections approximates the photo-absorption cross section. With this information the theoretical predictions can be checked
Compilation of cross-sections. Pt. 3
A compilation of integrated cross-sections for hadronic reactions is presented. This is an updated version of CERN/HERA 79-1, 79-2, 79-3. It contains all data published up to the beginning of 1982, but some more recent data, particularly those from the CERN Collider, have also been included. Plots of the cross-sections versus incident laboratory momentum are also given. This volume III contains cross-sections for p and anti p induced reactions. (orig.)
Screening corrections to the Rutherford cross section
Differential cross sections for elastic p-Au scattering were measured in the energy range between 0.2 and 0.8 MeV for scattering angles from 300 to 1500 in order to determine corrections to the Rutherford cross section due to the screening of the nuclear charge by the atomic electrons. Furthermore, differential cross sections have been calculated in the weakly screening region using various screening functions. A simple analytical expression has been derived for the representation of both experimental and theoretical results. (orig.)
A nuclear cross section data handbook
Fisher, H.O.M.
1989-12-01
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.
Differential cross sections of positron hydrogen collisions
于荣梅; 濮春英; 黄晓玉; 殷复荣; 刘旭焱; 焦利光; 周雅君
2016-01-01
We make a detailed study on the angular differential cross sections of positron–hydrogen collisions by using the momentum-space coupled-channels optical (CCO) method for incident energies below the H ionization threshold. The target continuum and the positronium (Ps) formation channels are included in the coupled-channels calculations via a complex equivalent-local optical potential. The critical points, which show minima in the differential cross sections, as a function of the scattering angle and the incident energy are investigated. The resonances in the angular differential cross sections are reported for the first time in this energy range. The effects of the target continuum and the Ps formation channels on the different cross sections are discussed.
Systematics of (n,2n) Cross Sections
2008-01-01
<正>The experimental data of (n, 2n) cross sections were collected and evaluated as complete as possible. There are 640 sets of experimental data for 130 nuclei. The data were fitted to the expressions that describe the
Photoneutron cross section of 34S
Using an enriched 34S target, the reaction 34S(γ,sn)33S has been measured from below threshold (10.4 MeV) to 28 MeV by directly counting the photoneutrons as a function of bremsstrahlung energy. The resultant cross section shows gross splitting in the GDR region. The integrated cross section is discussed in the light of the systematics of similar nuclei having two neutrons outside a doubly closed shell/sub-shell core
Photoneutron cross section of 34S
Using an enriched 34S target, the reaction 34S(γ, sn) has been measured from below threshold (10.4 MeV) to 28 MeV by directly counting the photoneutrons as a function of bremsstrahlung energy. The resultant cross section shows gross splitting in the GDR region. The integrated cross section is discussed in the light of the systematics of similar nuclei having two neutrons outside a doubly closed shell/sub-shell core. (orig.)
Neutron capture cross sections from Surrogate measurements
Scielzo N.D.; Dietrich F.S.; Escher J.E.
2010-01-01
The prospects for determining cross sections for compound-nuclear neutron-capture reactions from Surrogate measurements are investigated. Calculations as well as experimental results are presented that test the Weisskopf-Ewing approximation, which is employed in most analyses of Surrogate data. It is concluded that, in general, one has to go beyond this approximation in order to obtain (n,γ) cross sections of sufficient accuracy for most astrophysical and nuclear-energy applications.
Neutron capture cross sections from Surrogate measurements
Scielzo N.D.
2010-03-01
Full Text Available The prospects for determining cross sections for compound-nuclear neutron-capture reactions from Surrogate measurements are investigated. Calculations as well as experimental results are presented that test the Weisskopf-Ewing approximation, which is employed in most analyses of Surrogate data. It is concluded that, in general, one has to go beyond this approximation in order to obtain (n,γ cross sections of sufficient accuracy for most astrophysical and nuclear-energy applications.
Evaluation methods for neutron cross section standards
Methods used to evaluate the neutron cross section standards are reviewed and their relative merits, assessed. These include phase-shift analysis, R-matrix fit, and a number of other methods by Poenitz, Bhat, Kon'shin and the Bayesian or generalized least-squares procedures. The problems involved in adopting these methods for future cross section standards evaluations are considered, and the prospects for their use, discussed. 115 references, 5 figures, 3 tables
Methods for calculating anisotropic transfer cross sections
The Legendre moments of the group transfer cross section, which are widely used in the numerical solution of the transport calculation can be efficiently and accurately constructed from low-order (K = 1--2) successive partial range moments. This is convenient for the generation of group constants. In addition, a technique to obtain group-angle correlation transfer cross section without Legendre expansion is presented. (author)
Photoproton cross section for 14C
Using bremsstrahlung, the 14C(γ,p) reaction cross section has been measured from threshold to 29 MeV. The integrated cross section up to 30 MeV is 18±3 MeV mb. Above 23.5 MeV, the reported cross section includes a contribution, estimated at 3.5 MeV mb, due to the 14C(γ,d) and 14Cγ,pn) reactions. Essentially the entire 14C(γ,p) cross section results from decay of T> dipole states. From knowledge of other decay channels estimates of the cross section, integrated to 30 MeV for the T and T> components of the giant resonance (GDR) of 81 MeV mb and 43 MeV mb are obtained. The splitting of the mean energies of the GDR isospin components is 8.5 MeV. Comparisons with several shell-model calculations are made with the data, and general agreement is found. A comparison of photonuclear absorption cross sections for 12,1314C and 16,17,18 O shows dramatic redistribution of dipole strength as neutrons are added to the core nuclei. 41 refs., 1 tab., 7 figs
Couvreur, Valentin; Faget, Marc; Javaux, Mathieu; Chaumont, Francois; Draye, Xavier; 2016 Kirkham Conference
2016-01-01
Objectives: To improve our understanding of aquaporin (AQP) expression patterns and root anatomy effects on radial hydraulic conductivity by combining quantitative in vivo and in silico experiments from the cell to the root cross-section scales in various hydric environments. Methods: A program generates explicit 2D root cross-section hydraulic networks from cross-section anatomy images. The hydraulic network includes "cell wall" and "intra cell" nodes constituting connected pathways allowing...
abo-cross: Hydrogen broadening cross-section calculator
Barklem, P. S.; Anstee, S. D.; O'Mara, B. J.
2015-07-01
Line broadening cross sections for the broadening of spectral lines by collisions with neutral hydrogen atoms have been tabulated by Anstee & O'Mara (1995), Barklem & O'Mara (1997) and Barklem, O'Mara & Ross (1998) for s-p, p-s, p-d, d-p, d-f and f-d transitions. abo-cross, written in Fortran, interpolates in these tabulations to make these data more accessible to the end user. This code can be incorporated into existing spectrum synthesis programs or used it in a stand-alone mode to compute line broadening cross sections for specific transitions.
A Pebble Bed Reactor cross section methodology
A method is presented for the evaluation of microscopic cross sections for the Pebble Bed Reactor (PBR) neutron diffusion computational models during convergence to an equilibrium (asymptotic) fuel cycle. This method considers the isotopics within a core spectral zone and the leakages from such a zone as they arise during reactor operation. The randomness of the spatial distribution of fuel grains within the fuel pebbles and that of the fuel and moderator pebbles within the core, the double heterogeneity of the fuel, and the indeterminate burnup of the spectral zones all pose a unique challenge for the computation of the local microscopic cross sections. As prior knowledge of the equilibrium composition and leakage is not available, it is necessary to repeatedly re-compute the group constants with updated zone information. A method is presented to account for local spectral zone composition and leakage effects without resorting to frequent spectrum code calls. Fine group data are pre-computed for a range of isotopic states. Microscopic cross sections and zone nuclide number densities are used to construct fine group macroscopic cross sections, which, together with fission spectra, flux modulation factors, and zone buckling, are used in the solution of the slowing down balance to generate a new or updated spectrum. The microscopic cross-sections are then re-collapsed with the new spectrum for the local spectral zone. This technique is named the Spectral History Correction (SHC) method. It is found that this method accurately recalculates local broad group microscopic cross sections. Significant improvement in the core eigenvalue, flux, and power peaking factor is observed when the local cross sections are corrected for the effects of the spectral zone composition and leakage in two-dimensional PBR test problems.
Saxena, Nishank; Mavko, Gary
2016-03-01
Estimation of elastic rock moduli using 2D plane strain computations from thin sections has several numerical and analytical advantages over using 3D rock images, including faster computation, smaller memory requirements, and the availability of cheap thin sections. These advantages, however, must be weighed against the estimation accuracy of 3D rock properties from thin sections. We present a new method for predicting elastic properties of natural rocks using thin sections. Our method is based on a simple power-law transform that correlates computed 2D thin section moduli and the corresponding 3D rock moduli. The validity of this transform is established using a dataset comprised of FEM-computed elastic moduli of rock samples from various geologic formations, including Fontainebleau sandstone, Berea sandstone, Bituminous sand, and Grossmont carbonate. We note that using the power-law transform with a power-law coefficient between 0.4-0.6 contains 2D moduli to 3D moduli transformations for all rocks that are considered in this study. We also find that reliable estimates of P-wave (Vp) and S-wave velocity (Vs) trends can be obtained using 2D thin sections.
Error Assessment of Homogenized Cross Sections Generation for Whole Core Neutronic Calculation
The objective of the work here was to assess the errors introduced by using 2D, few group homogenized cross sections to perform neutronic analysis of BWR problems with significant axial heterogeneities. The 3D method of characteristics code DeCART is used to generate 2-group assembly homogenized cross sections first using a conventional 2D lattice model and then using a full 3D solution of the assembly. A single BWR fuel assembly model based on an advanced BWR lattice design is used with a typical void distribution applied to the fuel channel coolant. This model is validated against an MCNP model. A comparison of the cross sections is performed for the assembly homogenized planar cross sections from the DeCART 3D and DeCART 2D solutions
Axial dependence of homogenized cross sections used for nodal analysis of the boiling water reactor
The objective of the work here was to assess the errors introduced by using 2D, few group homogenized cross sections to perform neutronics analysis of BWR problems with significant axial heterogeneities. The 3D method of characteristics code DeCART is used to generate 2-group assembly homogenized cross sections first using a conventional 2D lattice model and then using a full 3D solution of the assembly. A single BWR fuel assembly model based on an advanced BWR lattice design is used with a typical void distribution applied to the fuel channel coolant. This model is validated against an MCNP model. A comparison of the cross sections is performed for the assembly homogenized planar cross sections from the DeCART 3D and DeCART 2D solutions. (authors)
Reduction Methods for Total Reaction Cross Sections
Gomes, P. R. S.; Mendes Junior, D. R.; Canto, L. F.; Lubian, J.; de Faria, P. N.
2016-03-01
The most frequently used methods to reduce fusion and total reaction excitation functions were investigated in a very recent paper Canto et al. (Phys Rev C 92:014626, 2015). These methods are widely used to eliminate the influence of masses and charges in comparisons of cross sections for weakly bound and tightly bound systems. This study reached two main conclusions. The first is that the fusion function method is the most successful procedure to reduce fusion cross sections. Applying this method to theoretical cross sections of single channel calculations, one obtains a system independent curve (the fusion function), that can be used as a benchmark to fusion data. The second conclusion was that none of the reduction methods available in the literature is able to provide a universal curve for total reaction cross sections. The reduced single channel cross sections keep a strong dependence of the atomic and mass numbers of the collision partners, except for systems in the same mass range. In the present work we pursue this problem further, applying the reduction methods to systems within a limited mass range. We show that, under these circumstances, the reduction of reaction data may be very useful.
The effect of intersystem crossings in N({sup 2}D) + H{sub 2} collisions
Galvão, B. R. L., E-mail: brenogalvao@gmail.com; Poveda, L. A. [Centro Federal de Educação Tecnológica de Minas Gerais, CEFET-MG, Av. Amazonas 5253, 30421-169 Belo Horizonte, Minas Gerais (Brazil)
2015-05-14
The transitions between quartet and doublet states of the NH{sub 2} molecule are studied for the first time, allowing the evaluation of the N({sup 4}S) + H{sub 2} reactive channel. High level ab initio calculations of the spin-orbit coupling are performed over the whole configurational space of the NH{sub 2} molecule and fitted to a proposed analytic form. Quasiclassical trajectories coupled with the surface hopping method are employed to calculate reaction cross section and rate constants. The reaction is largely affected by the initial rovibrational states of H{sub 2}, while the formation of long-lived complexes enhances the reaction probability.
Neutron cross section of methane hydrate
Kiyanagi, Y.; Date, S.; Horikawa, T.; Takamine, J.; Iwasa, H.; Kamiyama, T. [Graduate School of Eng., Hokkaido Univ., Sapporo (Japan); Uchida, T.; Ebinuma, T.; Narrita, H. [National Inst. of Advanced Industrial Science, Tsukisamu, Sapporo (Japan); Bennington, S.M. [ISIS Dept., Rutherford Appleton, Chilton, Didcot, Oxon (United Kingdom)
2004-03-01
To estimate the neutronic characteristics of methane hydrate and also to synthesize cross section data for simulation we need neutron scattering data ranging wide energy and momentum region. We performed inelastic neutron scattering experiments to get information about the neutron cross section on methane hydrate. It was found that at high momentum transfer region rotational mode as well as vibration mode showed recoil like behavior. On the other hand, at low momentum region, as well known, free rotation like energy levels were observed. The energy level of ice in methane hydrate was very similar to normal ice. The results suggest that the rough expression of the cross section of the methane hydrate is presented by linear combination of the methane and ice. (orig.)
Prospects for Precision Neutrino Cross Section Measurements
Harris, Deborah A. [Fermilab
2016-01-28
The need for precision cross section measurements is more urgent now than ever before, given the central role neutrino oscillation measurements play in the field of particle physics. The definition of precision is something worth considering, however. In order to build the best model for an oscillation experiment, cross section measurements should span a broad range of energies, neutrino interaction channels, and target nuclei. Precision might better be defined not in the final uncertainty associated with any one measurement but rather with the breadth of measurements that are available to constrain models. Current experience shows that models are better constrained by 10 measurements across different processes and energies with 10% uncertainties than by one measurement of one process on one nucleus with a 1% uncertainty. This article describes the current status of and future prospects for the field of precision cross section measurements considering the metric of how many processes, energies, and nuclei have been studied.
Radar Cross Section measurements on the stealth metamaterial objects
Iwaszczuk, Krzysztof; Fan, Kim; Strikwerda, Andrew C.; Zhang, Xi; Averitt, Richard D.; Jepsen, Peter Uhd
have been realized in the form of thin, flexible metallized films of polyimide [1]. Here we apply a near-unity absorbing MM as a way to reduce the radar cross section of an object, and consider the real-life situation where the probe beam is significantly larger than the MM film and the object under...... investigation. We use a terahertz radar cross section (RCS) setup [2] for the characterization of the RCS of a real object covered with an absorbing MM film designed for high absorption in the THz frequency range, specifically at 0.8 THz. The results are in a form of 2D maps (sinograms), from which the RCS is...
Radiation pressure cross section for fluffy aggregates
We apply the discrete dipole approximation (DDA) to estimate the radiation pressure cross section for fluffy aggregates by computing the asymmetry parameter and the cross sections for extinction and scattering. The ballistic particle-cluster aggregate and the ballistic cluster-cluster aggregate consisting of either dielectric or absorbing material are considered to represent naturally existing aggregates. We show that the asymmetry parameter perpendicular to the direction of wave propagation is maximized where the wavelength is comparable to the aggregate size, which may be characterized by the area-equivalent radius or the radius of gyration rather than the volume-equivalent radius. The asymmetry parameter for the aggregate depends on the morphology of the particle, but not on the constituent material. Therefore, the dependence of the radiation pressure cross section on the material composition arises mainly from that of the extinction and scattering cross sections, in other words, the single-scattering albedo. We find that aggregates consisting of high-albedo material show a large deviation of radiation pressure from the direction of incident radiation. When the aggregates are illuminated by blackbody radiation, the deviation of the radiation pressure increases with increasing temperature of the blackbody. Since the parallel component of the radiation pressure cross section for the aggregates is smaller than that for the volume-equivalent spheres at the size parameter close to unity, the Planck-mean radiation pressure cross section for the aggregates having radius comparable to the effective wavelength of radiation shows a lower value, compared with the volume-equivalent sphere. Consequently, the slope of the radiation pressure force per mass of the particle as a function of particle mass shows a lower maximum for the aggregates than for compact spherical particles. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)
Charged particle reaction cross sections and nucleosynthesis
The role of proton and α-particle induced reactions in carbon, neon, oxygen and silicon burning in massive stars is surveyed. The problems associated with determining thermonuclear reaction rates for reactions with widely spaced resonances and with closely spaced or overlapping resonances are discussed and the associated experimental approaches are reviewed. Experimental techniques which have been used in the measurement of reaction cross sections are discussed and their strengths and weaknesses are identified. Recent developments in attempts to establish reliable statistical-model codes for calculation of reaction cross sections are presented and discussed. The results of experimental tests of statistical model codes are summarised and evaluated
Neutron capture cross sections from surrogate measurements
The prospects for determining cross sections for compound-nuclear neutron-capture reactions from Surrogate measurements are investigated. Calculations as well as experimental results are presented that test the Weisskopf-Ewing approximation, which is employed in most analyses of Surrogate data. The method is applied to the 155Gd(n,γ) reaction. It is concluded that, in general, one has to go beyond this approximation in order to obtain (n,γ) cross sections of sufficient accuracy for most astrophysical and nuclear-energy applications. (authors)
Precise neutron inelastic cross section measurements
Negret, Alexandru
2012-11-01
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.
Optical Model and Cross Section Uncertainties
Herman,M.W.; Pigni, M.T.; Dietrich, F.S.; Oblozinsky, P.
2009-10-05
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.
Saturation Effects in Hadronic Cross Sections
Shoshi, Arif I.; Steffen, Frank D.
2002-01-01
We compute total and differential elastic cross sections of high-energy hadronic collisions in the loop-loop correlation model that provides a unified description of hadron-hadron, photon-hadron, and photon-photon reactions. The impact parameter profiles of pp and gamma*p collisions are calculated. For ultra-high energies the hadron opacity saturates at the black disc limit which tames the growth of the hadronic cross sections in agreement with the Froissart bound. We compute the impact param...
Covariance Evaluation Methodology for Neutron Cross Sections
Herman,M.; Arcilla, R.; Mattoon, C.M.; Mughabghab, S.F.; Oblozinsky, P.; Pigni, M.; Pritychenko, b.; Songzoni, A.A.
2008-09-01
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.
Atlas of neutron capture cross sections
This report describes neutron capture cross sections in the range 10-5 eV - 20 MeV as evaluated and compiled in recent activation libraries. The selected subset comprise the (n,γ) cross sections for a total of 739 targets for the elements H (Z = 1, Z = 1) to Cm (Z = 96, A = 238) totaling 972 reactions. Plots of the point-wise data are shown and comparisons are made with the available experimental values at thermal energy, 30 keV and 14.5 MeV. 10 refs, 7 tabs
Verification of important cross section data
Full text: Continuing efforts in nuclear data development have made the design of a fusion power system less uncertain. The fusion evaluated nuclear data library (FENDL) development effort since 1987 under the leadership of the IAEA Nuclear Data Section has provided a credible international library for the investigation and design of the International Thermonuclear Engineering Reactor (ITER). Integral neutronics experiments are being carried out for ITER and fusion power plant blanket and shield assemblies to validate the available nuclear database and to identify deficiencies for further improvement. Important cross section data need experimental verifications if these data are evaluated based on physics model calculations and there are no measured data points available. A particular reaction cross section is Si28(n,x)Al27, which is the important cross section to determine whether the low activation SiC composite structure can be qualified as low level nuclear waste after life time exposure in the first wall neutron environment in a fusion power plant. Measurements of helium production data for candidate fusion materials are also needed, particularly at energies above 14 MeV for the assessment of materials damage in the IFMIF neutron spectrum. To a less extent, it appears that V51(n,x)Ti50 reaction cross section also needs to be measured to further confirm a recent new evaluation of vanadium for ENDF/B-VII. (author)
Fusion cross sections and the new dynamics
The prediction of the need for an extra push over the interaction barrier in order to make the heavier nuclei fuse is made the basis of a simple algebraic theory for the energy-dependence of the fusion cross-section. A comparison with recent experiments promises to provide a quantitative test of the New Dynamics
LSP-Nucleus Elastic Scattering Cross Sections
Vergados, J. D.; Kosmas, T. S.
1997-01-01
We calculate LSP-nucleus elastic scattering cross sections using some representative input in the restricted SUSY parameter space. The coherent matrix elements are computed throughout the periodic table while the spin matrix elements for the proposed $^{207}Pb$ target which has a rather simple nuclear structure. The results are compared to those given from other cold dark matter detection targets.
Electron impact excitation cross sections for carbon
Ganas, P. S.
1981-04-01
A realistic analytic atomic independent particle model is used to generate wave functions for the valence and excited states of carbon. Using these wave functions in conjunction with the Born approximation and the Russell-Saunders LS-coupling scheme, we calculate generalized oscillator strengths and integrated cross sections for various excitations from the 2p 2( 3P O) valence state.
Electron impact excitation cross sections for carbon
A realistic analytic atomic independent particle model is used to generate wave functions for the valence and excited states of carbon. Using these wave functions in conjunction with the Born approximation and the Russell-Saunders LS-coupling scheme, we calculate generalized oscillator strengths and integrated cross sections for various excitations from the 2p2(3P0) valence state. (orig.)
Top quark cross sections and differential distributions
Kidonakis, Nikolaos
2011-01-01
I present results for the top quark pair total cross section and the top quark transverse momentum distribution at Tevatron and LHC energies. I also present results for single top quark production. All calculations include NNLO corrections from NNLL threshold resummation.
Neutron cross sections of importance to astrophysics
Neutron reactions of importance to the various stellar burning cycles are discussed. The role of isomeric states in the branched s-process is considered for particular cases. Neutron cross section needs for the 187Re-187Os, 87Rb-87Sr clocks for nuclear cosmochronology are discussed. Other reactions of interest to astrophysical processes are presented. 35 references
Modelisation of the fission cross section
The neutron cross sections of four nuclear systems (n+235U, n+233U, n+241Am and n+237Np) are studied in the present document. The target nuclei of the first case, like 235U and 239Pu, have a large fission cross section after the absorption of thermal neutrons. These nuclei are called 'fissile' nuclei. The other type of nuclei, like 237Np and 241Am, fission mostly with fast neutrons, which exceed the fission threshold energy. These types of nuclei are called 'fertile'. The compound nuclei of the fertile nuclei have a binding energy higher than the fission barrier, while for the fissile nuclei the binding energy is lower than the fission barrier. In this work, the neutron induced cross sections for both types of nuclei are evaluated in the fast energy range. The total, reaction and shape-elastic cross sections are calculated by the coupled channel method of the optical model code ECIS, while the compound nucleus mechanism are treated by the statistical models implemented in the codes STATIS, GNASH and TALYS. The STATIS code includes a refined model of the fission process. Results from the theoretical calculations are compared with data retrieved from the experimental data base EXFOR. (author)
Neutron Capture Cross Sections for Radioactive Nuclei
Tonchev, Anton; Bedrossian, Peter; Escher, Jutta; Scielzo, Nicholas
2015-10-01
Accurate neutron-capture cross sections for radioactive nuclei near or far away from the line of beta stability are crucial for understanding the nucleosynthesis of heavy elements. However, neutron-capture cross sections for short-lived radionuclides are difficult to measure due to the fact that the measurements require both highly radioactive samples and intense neutron sources. Essential ingredients for describing the γ decays following neutron capture are the γ-ray strength function and level densities. We will compare different indirect approaches for obtaining observables that can constrain Hauser-Feshbach statistical model calculations of capture cross sections. Specifically, we will consider photon scattering, transfer reactions, and beta-delayed neutron emission. Challenges that exist on the path to obtaining neutron-capture cross sections for reactions on isotopes far from stability will be discussed. This work was performed under the auspices of US DOE by LLNL under contract DE-AC52-07NA27344. Funding was provided via the LDRD-ERD-069 project.
Symmetric charge transfer cross section of uranium
Symmetric charge transfer cross section of uranium was calculated under consideration of reaction paths. In the charge transfer reaction a d3/2 electron in the U atom transfers into the d-electron site of U+(4I9/2) ion. The J value of the U atom produced after the reaction is 6, 5, 4 or 3, at impact energy below several tens eV, only resonant charge transfer in which the product atom is ground state (J=6) takes place. Therefore, the cross section is very small (4-5 x 10-15 cm2) compared with that considered so far. In the energy range of 100-1000eV the cross section increases with the impact energy because near resonant charge transfer in which an s-electron in the U atom transfers into the d-electron site of U+ ion. Charge transfer cross section between U+ in the first excited state (289 cm-1) and U in the ground state was also obtained. (author)
Measurement cross sections for radioisotopes production
New radioactive isotopes for nuclear medicine can be produced using particle accelerators. This is one goal of Arronax, a high energy - 70 MeV - high intensity - 2*350 μA - cyclotron set up in Nantes. A priority list was established containing β- - 47Sc, 67Cu - β+ - 44Sc, 64Cu, 82Sr/82Rb, 68Ge/68Ga - and α emitters - 211At. Among these radioisotopes, the Scandium 47 and the Copper 67 have a strong interest in targeted therapy. The optimization of their productions required a good knowledge of their cross-sections but also of all the contaminants created during irradiation. We launched on Arronax a program to measure these production cross-sections using the Stacked-Foils' technique. It consists in irradiating several groups of foils - target, monitor and degrader foils - and in measuring the produced isotopes by γ-spectrometry. The monitor - natCu or natNi - is used to correct beam loss whereas degrader foils are used to lower beam energy. We chose to study the natTi(p,X)47Sc and 68Zn(p,2p)67Cu reactions. Targets are respectively natural Titanium foil - bought from Goodfellow - and enriched Zinc 68 deposited on Silver. In the latter case, Zn targets were prepared in-house - electroplating of 68Zn - and a chemical separation between Copper and Gallium isotopes has to be made before γ counting. Cross-section values for more than 40 different reactions cross-sections have been obtained from 18 MeV to 68 MeV. A comparison with the Talys code is systematically done. Several parameters of theoretical models have been studied and we found that is not possible to reproduce faithfully all the cross-sections with a given set of parameters. (author)
Zuo, M.; Smith, S.; Chutjian, A.; Williams, I.; Tayal, S.; McLaughlin, B.
1994-01-01
Experimental and theoretical excitation cross sections are reported for the first forbidden transition xxx and the first allowed (resonance) transition xxx in OII. Use is made of electron-energy loss and merged beams methods. The electron energy range covered is 3.33 eV (threshold) to 15 eV for the S->D transition, and 14.9 eV (threshold) to 40 eV for the S->P transition. Care was taken to assess and minimize the metastable fraction of the OII beam. An electron mirror was designed and tested to reflect inelastically back-scattered electrons into the forward direction to account for the full range of polar scattering angles. Comparisons are made between present experiments and 11-state R-Matrix calculations. Calculations are also presented for the xxx transition.
A New Neutrino Cross Section Data Ressource
Whalley, M R
2005-01-01
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.
We are developing a method of (n,α) cross section measurement using gaseous samples in a gridded ionization chamber (GIC). This method enables cross section measurements in large solid angle without the distortion by the energy loss in a sample, but requires a method to estimate the detection efficiency. We solve this problem by using GIC signals and a tight neutron collimation. The validity of this method was confirmed through the 12C(n,α0)9Be measurement. We applied this method to the 16O(n,α)13C cross section around 14.1 MeV. (author)
Sanami, Toshiya; Baba, Mamoru; Saito, Keiichiro; Ibara, Yasutaka; Hirakawa, Naohiro [Tohoku Univ., Sendai (Japan). Faculty of Engineering
1997-03-01
We are developing a method of (n,{alpha}) cross section measurement using gaseous samples in a gridded ionization chamber (GIC). This method enables cross section measurements in large solid angle without the distortion by the energy loss in a sample, but requires a method to estimate the detection efficiency. We solve this problem by using GIC signals and a tight neutron collimation. The validity of this method was confirmed through the {sup 12}C(n,{alpha}{sub 0}){sup 9}Be measurement. We applied this method to the {sup 16}O(n,{alpha}){sup 13}C cross section around 14.1 MeV. (author)
Structured ion impact: Doubly differential cross sections
The electron emission in coincidence with a projectile that has been ionized has been measured, thus making it possible to separate and identify electrons resulting from these various mechanisms. In 1985, coincidence doubly differential cross sections were measured for 400 to 750 keV/atomic mass unit (amu) He+ impact on He, Ne, Ar, Kr, and H2O. Cross sections were measured for selected angles and for electron energies ranging from 10 to 1000 eV. Because of the coincidence mode of measurement, the total electron emission was subdivided into its target emission and its projectile emission components. The most interesting findings were that target ionization does not account for the electron emission spectrum at lower electron energies. A sizable percentage of these low-energy electrons were shown to originate as a result of simultaneous projectile/target ionizations. Similar features were observed for all targets and impact energies that were studied
Elliptical cross section fuel rod study II
In this paper it is continued the behavior analysis and comparison between cylindrical fuel rods of circular and elliptical cross sections. Taking into account the accepted models in the literature, the fission gas swelling and release were studied. An analytical comparison between both kinds of rod reveals a sensible gas release reduction in the elliptical case, a 50% swelling reduction due to intragranular bubble coalescence mechanism and an important swelling increase due to migration bubble mechanism. From the safety operation point of view, for the same linear power, an elliptical cross section rod is favored by lower central temperatures, lower gas release rates, greater gas store in ceramic matrix and lower stored energy rates. (author). 6 refs., 8 figs., 1 tab
Jet cross sections and PDF constraints
CMS Collaboration
2012-01-01
A measurement of inclusive jet and dijet production cross sections is presented. Data from LHC proton-proton collisions at $\\sqrt{s}=7\\TeV$, corresponding to $4.67\\fbinv$ of integrated luminosity, have been collected with the CMS detector. Jets are reconstructed with the anti-$k_T$ clustering algorithm of size parameter $R=0.7$, extending to rapidity $|y|=2.5$, transverse momentum $\\pt=2\\TeV$, and dijet invariant mass $M_{JJ}=5\\TeV$. The measured cross sections are corrected for detector effects and compared to perturbative QCD predictions at next-to-leading order, using various sets of parton distribution functions.
The photoneutron cross section of 20Ne
The photoneutron cross section of 20Ne has been measured over a photon energy range 16 to 29 MeV in steps of 100 keV. The giant dipole resonance is resolved into three strong peaks below 21 MeV and at least two broader resonances at higher excitations. This structure is consistent with earlier measurements of poorer resolution and shows a correlation with the recent calculations of Schmid and Do Dang. Comparisons with high resolution neutron time-of-flight and electron scattering data indicate that there appear to exist in the giant resonance of 20Ne, regions of structure roughly 2-3 MeV wide which exhibit localised characteristics related to the excitation mechanisms. The role of deformation and configuration splitting effects in the cross section are discussed and possible directions of further study are noted which might clarify the situation more fully
Electron capture cross sections for stellar nucleosynthesis
Giannaka, P G
2015-01-01
In the first stage of this work, we perform detailed calculations for the cross sections of the electron capture on nuclei under laboratory conditions. Towards this aim we exploit the advantages of a refined version of the proton-neutron quasi-particle random-phase approximation (pn-QRPA) and carry out state-by-state evaluations of the rates of exclusive processes that lead to any of the accessible transitions within the chosen model space. In the second stage of our present study, we translate the above mentioned $e^-$-capture cross sections to the stellar environment ones by inserting the temperature dependence through a Maxwell-Boltzmann distribution describing the stellar electron gas. As a concrete nuclear target we use the $^{66}Zn$ isotope, which belongs to the iron group nuclei and plays prominent role in stellar nucleosynthesis at core collapse supernovae environment.
Cross-section analysis for TRADE fuel
The TRIGA core includes bounded hydrogen in Zirconium hydride in its fuel meat allowing for fast reactivity transients. The inherent safety mechanism is based on the immediate increase of neutron up-scattering by the hydrogen as a result of a fuel temperature increase. The temperature dependent resonance absorption is the second safety feature. The special fuel type together with the introduction of an external source within it for the TRADE project necessitates an accurate evaluation of the bounded hydrogen cross section generation technique as well as of the resonance treatment. By comparing deterministic tools and Monte Carlo solution methods the generated bounded isotopes cross sections are analysed. Further, the importance of the Doppler and the thermal up-scattering effects are quantified and the sensitivities to the solution method are discussed. (authors)
Measurements of neutron spallation cross section. 2
Kim, E.; Nakamura, T. [Tohoku Univ., Sendai (Japan). Cyclotron and Radioisotope Center; Imamura, M.; Nakao, N.; Shibata, S.; Uwamino, Y.; Nakanishi, N.; Tanaka, Su.
1997-03-01
Neutron spallation cross section of {sup 59}Co(n,xn){sup 60-x}Co, {sup nat}Cu(n,sp){sup 56}Mn, {sup nat}Cu(n,sp){sup 58}Co, {sup nat}Cu(n,xn){sup 60}Cu, {sup nat}Cu(n,xn){sup 61}Cu and {sup nat}Cu(n,sp){sup 65}Ni was measured in the quasi-monoenergetic p-Li neutron fields in the energy range above 40 MeV which have been established at three AVF cyclotron facilities of (1) INS of Univ. of Tokyo, (2) TIARA of JAERI and (3) RIKEN. Our experimental data were compared with the ENDF/B-VI high energy file data by Fukahori and the calculated cross section data by Odano. (author)
Reinforced concrete columns of variable cross section
Brant, N.F.A.
1984-01-01
The results of a series of 19 full scale tests carried out on pin-ended reinforced concrete columns are reported. The columns tested had either tapered rectangular sections along the length or octagonal cross sections. All columns, except the last 6, were subjected to uniaxial eccentricities at one of the ends (the stronger end), and a nominally concentric load at the other end. For the case of the last six columns the loading applied at the stronger end was biaxially eccentric. For each of t...
Neutron capture cross section measurement techniques
A review of currently-used techniques to measure neutron capture cross sections is presented. Measurements involving use of total absorption and Moxon-Rae detectors are based on low-resolution detection of the prompt γ-ray cascades following neutron captures. In certain energy ranges activation methods are convenient and useful. High resolution γ-ray measurements with germanium detectors can give information on the parameters of resonance capture states. The use of these techniques is described. (U.S.)
Fusion cross sections at deep subbarrier energies
Hagino, K.; Rowley, N.; Dasgupta, M
2003-01-01
A recent publication reports that heavy-ion fusion cross sections at extreme subbarrier energies show a continuous change of their logarithmic slope with decreasing energy, resulting in a much steeper excitation function compared with theoretical predictions. We show that the energy dependence of this slope is partly due to the asymmetric shape of the Coulomb barrier, that is its deviation from a harmonic shape. We also point out that the large low-energy slope is consistent with the surprisi...
How to calculate colourful cross sections efficiently
Gleisberg, Tanju; Krauss, Frank
2008-01-01
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.
Jet cross sections in leptoproduction from QCD
We have calculated the longitudinal and other polarization dependent cross sections for jet production in deep inelastic ep, νp and anti νp scattering up to order αsub(s) of the quark-gluon coupling constant. Fragmentation of final state partons into hadrons is taken into account. Distributions in thrust, p2sub(Tin) and p2sub(Tout) are predicted for all three reactions and various values of W and Q. (orig.)
Measurements of Fission Cross Sections of Actinides
Wiescher, M; Cox, J; Dahlfors, M
2002-01-01
A measurement of the neutron induced fission cross sections of $^{237}$Np, $^{241},{243}$Am and of $^{245}$Cm is proposed for the n_TOF neutron beam. Two sets of fission detectors will be used: one based on PPAC counters and another based on a fast ionization chamber (FIC). A total of 5x10$^{18}$ protons are requested for the entire fission measurement campaign.
Neutron cross section standards and instrumentation
1992-09-01
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.
Electron collision cross sections and radiation chemistry
A survey is given of the cross section data needs in radiation chemistry, and of the recent progress in electron impact studies on dissociative excitation of molecules. In the former some of the important target species, processes, and collision energies are presented, while in the latter it is demonstrated that radiation chemistry is a source of new ideas and information in atomic collision research. 37 references, 4 figures
Atomic-process cross section data, 1
Compiled by the Data Study Group, the data are intended for fusion plasma physics research. Cross sections of the latest experimental and theoretic studies cover the processes involving H,D,T as principal plasma materials as well as photons and electrons: emission and absorption of electromagnetic wave, electron collision, ion collision, recombination, neutral atom mutual collision, etc. Edition is so made to enable the future renewal by users. (J.P.N.)
Cross section of the CMS solenoid
Tejinder S. Virdee, CERN
2005-01-01
The pictures show a cross section of the CMS solenoid. One can see four layers of the superconducting coil, each of which contains the superconductor (central part, copper coloured - niobium-titanium strands in a copper coating, made into a "Rutherford cable"), surrounded by an ultra-pure aluminium as a magnetic stabilizer, then an aluminium alloy as a mechanical stabilizer. Besides the four layers there is an aluminium mechanical piece that includes pipes that transport the liquid helium.
Neutron cross section standards and instrumentation
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 10B 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 10B are in progress in collaboration with scientists at the Oak Ridge National Laboratory. New experiments are in progress on the important dosimetry standards 237Np(n,f) and 239Pu(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
The Pa-233 fission cross section
The energy dependent neutron-induced fission cross section of 233Pa has for the first time been measured directly with mono-energetic neutrons. This isotope is produced in the thorium fuel cycle and serves as an intermediate step between the 232Th source material and the 233U fuel material. Four neutron energies between 1.0 and 3.0 MeV have been measured in a first campaign. Some preliminary results are presented and compared to literature. (author)
Fusion cross sections measurements with MUSIC
Carnelli, P. F. F.; Fernández Niello, J. O.; Almaraz-Calderon, S.; Rehm, K. E.; Albers, M.; Digiovine, B.; Esbensen, H.; Henderson, D.; Jiang, C. L.; Nusair, O.; Palchan-Hazan, T.; Pardo, R. C.; Ugalde, C.; Paul, M.; Alcorta, M.; Bertone, P. F.; Lai, J.; Marley, S. T.
2014-09-01
The interaction between exotic nuclei plays an important role for understanding the reaction mechanism of the fusion processes as well as for the energy production in stars. With the advent of radioactive beams new frontiers for fusion reaction studies have become accessible. We have performed the first measurements of the total fusion cross sections in the systems 10 , 14 , 15C + 12C using a newly developed active target-detector system (MUSIC). Comparison of the obtained cross sections with theoretical predictions show a good agreement in the energy region accessible with existing radioactive beams. This type of comparison allows us to calibrate the calculations for cases that cannot be studied in the laboratory with the current experimental capabilities. The high efficiency of this active detector system will allow future measurements with even more neutron-rich isotopes. The interaction between exotic nuclei plays an important role for understanding the reaction mechanism of the fusion processes as well as for the energy production in stars. With the advent of radioactive beams new frontiers for fusion reaction studies have become accessible. We have performed the first measurements of the total fusion cross sections in the systems 10 , 14 , 15C + 12C using a newly developed active target-detector system (MUSIC). Comparison of the obtained cross sections with theoretical predictions show a good agreement in the energy region accessible with existing radioactive beams. This type of comparison allows us to calibrate the calculations for cases that cannot be studied in the laboratory with the current experimental capabilities. The high efficiency of this active detector system will allow future measurements with even more neutron-rich isotopes. This work is supported by the U.S. DOE Office of Nuclear Physics under Contract No. DE-AC02-06CH11357 and the Universidad Nacional de San Martin, Argentina, Grant SJ10/39.
Inclusive jet cross section at D0
Bhattacharjee, M. [Delhi Univ. (India). Dept. of Physics and Astrophysics
1996-09-01
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.
Total neutron cross section for 181Ta
Schilling K.-D.
2010-10-01
Full Text Available The neutron time of flight facility nELBE, produces fast neutrons in the energy range from 0.1 MeV to 10 MeV by impinging a pulsed relativistic electron beam on a liquid lead circuit [1]. The short beam pulses (∼10 ps and a small radiator volume give an energy resolution better than 1% at 1 MeV using a short flight path of about 6 m, for neutron TOF measurements. The present neutron source provides 2 ⋅ 104 n/cm2s at the target position using an electron charge of 77 pC and 100 kHz pulse repetition rate. This neutron intensity enables to measure neutron total cross section with a 2%–5% statistical uncertainty within a few days. In February 2008, neutron radiator, plastic detector [2] and data acquisition system were tested by measurements of the neutron total cross section for 181Ta and 27Al. Measurement of 181Ta was chosen because lack of high quality data in an anergy region below 700 keV. The total neutron cross – section for 27Al was measured as a control target, since there exists data for 27Al with high resolution and low statistical error [3].
Cross-section reconstruction during uniaxial loading
The inelastic response of materials to applied uniaxial loading is typically measured using tensile or compressive specimens of an initially circular cross-section. Under deformation, this cross-section may become elliptical due to anisotropic material behaviour. An optical technique for measuring the elliptical deformation of anisotropic, homogeneous cylindrical specimens undergoing uniaxial deformation is presented. It enables the quantification of anisotropic deformation in situ and provides data for material characterization. Three or more silhouette views of a specimen are obtained using multiple cameras or mirrored views. The positions of the edges are computed using a sub-pixel edge detection method, and 3D tangent rays from the camera through these positions are calculated. These bounding tangents are used as the basis for an elliptical fit by least squares at cross-sections along the length of the specimen. Stochastic error estimates are performed by simulation of the experiment. Error estimates, for the experimental set-up used, are also calculated by reconstructing elliptical prisms of precisely measured dimensions. Example reconstructions from specimens of rolled titanium deformed plastically in tension at quasi-static (7 × 10−4 s−1) and high strain rates (3 × 103 s−1) are presented
Electron impact cross sections of vibrationally and electronically excited molecules
Yoon, Jung-Sik, E-mail: jsyoon@nfri.re.kr [Plasma Technology Research Center, National Fusion Research Institute, 814-2, Osikdo-Dong, Gunsan, Jeollabuk-Do, 573-540 (Korea, Republic of); Song, Mi-Young; Kwon, Deuk-Chul; Choi, Heechol [Plasma Technology Research Center, National Fusion Research Institute, 814-2, Osikdo-Dong, Gunsan, Jeollabuk-Do, 573-540 (Korea, Republic of); Kim, Chang-Geun [National Center for Standard Reference Data, Korea Research Institute of Standards and Science, Doryong-Dong, Yuseong-Gu, Daejeon 305-340 (Korea, Republic of); Kumar, Vijay [B-82, Aarohi Twin Bungalows, Near Govt. Tubewell, Bopal, Ahmedabad-380058 (India)
2014-10-30
It is well known that the electron impact cross sections for elastic and inelastic processes for the vibrationally and electronically excited molecules are predominantly different than those for molecules in the ground state. Collisions of low energy electrons with excited molecules play an important role in explaining the behavior of gas discharges in laser and plasma physics, in planetary atmospheres, stars, and interstellar medium and in plasmas widely used in the fabrication of microelectronics. This explains as to why there is a need for having validated sets of electron impact cross sections for different processes. This work reviews the subject of electron collisions with vibrationally and electronically excited molecules in a comprehensive way. The survey has been carried out for a few excited molecules such as H{sub 2}, D{sub 2}, T{sub 2}, HD, HT, DT, N{sub 2}, O{sub 2}, and CO{sub 2}. This review includes the discussion on the methods to produce and detect vibrationally and electronically excited molecules. We will take up the cross section data available in the literature for such molecules on electron scattering, dissociation, ionization and attachment processes and will discuss, evaluate and well-validate the same wherever and whenever possible.
Electron impact cross sections of vibrationally and electronically excited molecules
It is well known that the electron impact cross sections for elastic and inelastic processes for the vibrationally and electronically excited molecules are predominantly different than those for molecules in the ground state. Collisions of low energy electrons with excited molecules play an important role in explaining the behavior of gas discharges in laser and plasma physics, in planetary atmospheres, stars, and interstellar medium and in plasmas widely used in the fabrication of microelectronics. This explains as to why there is a need for having validated sets of electron impact cross sections for different processes. This work reviews the subject of electron collisions with vibrationally and electronically excited molecules in a comprehensive way. The survey has been carried out for a few excited molecules such as H2, D2, T2, HD, HT, DT, N2, O2, and CO2. This review includes the discussion on the methods to produce and detect vibrationally and electronically excited molecules. We will take up the cross section data available in the literature for such molecules on electron scattering, dissociation, ionization and attachment processes and will discuss, evaluate and well-validate the same wherever and whenever possible
无
2006-01-01
Using the nullisomic back-cross procedure, four wheat-rye chromosome substitution 2R (2D) lines with different agronomic performance, designated WR02-145-1, WR01-145-2, WR02-145-3, and WR02-145-4, were produced from a cross between 2D nullisomic wheat (Triticum aestivum L. cv. "Xiaoyan 6") and rye (Secale cereale L. cv. "German White"). The chromosomal constitution of 2n=42=21 in WR02-145 lines was confirmed by cytological and molecular cytogenetic methods. Using genomic in situ hybridization on root tip chromosome preparations, a pair of intact rye chromosomes was detected in the WR02-145 lines. PCR using chromosome-specific primers confirmed the presence of 2R chromosomes of rye in these wheat-rye lines, indicating that WR02-145 lines are disomic chromosome substitution lines 2R (2D). The WR02-145 lines are resistant to the powdery mildew (Erysiphe graminis DC. f. sp. tritici E. Marchal) isolates prevalent in northern China and may possess gene(s) for resistance to powdery mildew, which differ from the previously identified Pm7 gene located on chromosome 2RL. The newly developed "Xiaoyan 6"- "German White"2R (2D) chromosome substitution lines are genetically stable, show desirable agronomic traits, and are expected to be useful in wheat improvement.
Crossing the c=1 barrier in 2D Lorentzian quantum gravity
Ambjørn, J.; Anagnostopoulos, K.; Loll, R.
2000-02-01
In an extension of earlier work we investigate the behavior of two-dimensional (2D) Lorentzian quantum gravity under coupling to a conformal field theory with c>1. This is done by analyzing numerically a system of eight Ising models (corresponding to c=4) coupled to dynamically triangulated Lorentzian geometries. It is known that a single Ising model couples weakly to Lorentzian quantum gravity, in the sense that the Hausdorff dimension of the ensemble of two-geometries is two (as in pure Lorentzian quantum gravity) and the matter behavior is governed by the Onsager exponents. By increasing the amount of matter to eight Ising models, we find that the geometry of the combined system has undergone a phase transition. The new phase is characterized by an anomalous scaling of spatial length relative to proper time at large distances, and as a consequence the Hausdorff dimension is now three. In spite of this qualitative change in the geometric sector, and a very strong interaction between matter and geometry, the critical exponents of the Ising model retain their Onsager values. This provides evidence for the conjecture that the KPZ values of the critical exponents in 2D Euclidean quantum gravity are entirely due to the presence of baby universes. Lastly, we summarize the lessons learned so far from 2D Lorentzian quantum gravity.
This paper discusses recent developments and future plans for the SENSIBL code (the successor to the SENSIT[6] and SENSIT-2D[7] codes), along with associated covariance data and cross section libraries. 34 refs
Averaging cross section data so we can fit it
Brown, D. [Brookhaven National Lab. (BNL), Upton, NY (United States). NNDC
2014-10-23
The ^{56}Fe cross section we are interested in have a lot of fluctuations. We would like to fit the average of the cross section with cross sections calculated within EMPIRE. EMPIRE is a Hauser-Feshbach theory based nuclear reaction code, requires cross sections to be smoothed using a Lorentzian profile. The plan is to fit EMPIRE to these cross sections in the fast region (say above 500 keV).
Averaging cross section data so we can fit it
The 56Fe cross section we are interested in have a lot of fluctuations. We would like to fit the average of the cross section with cross sections calculated within EMPIRE. EMPIRE is a Hauser-Feshbach theory based nuclear reaction code, requires cross sections to be smoothed using a Lorentzian profile. The plan is to fit EMPIRE to these cross sections in the fast region (say above 500 keV).
Nuclear interaction cross sections for proton radiotherapy
Chadwick, M B; Arendse, G J; Cowley, A A; Richter, W A; Lawrie, J J; Newman, R T; Pilcher, J V; Smit, F D; Steyn, G F; Koen, J W; Stander, J A
1999-01-01
Model calculations of proton-induced nuclear reaction cross sections are described for biologically-important targets. Measurements made at the National Accelerator Centre are presented for double-differential proton, deuteron, triton, helium-3 and alpha particle spectra, for 150 and 200 MeV protons incident on C, N, and O. These data are needed for Monte Carlo simulations of radiation transport and absorbed dose in proton therapy. Data relevant to the use of positron emission tomography to locate the Bragg peak are also described.
Neutron capture cross section of $^{93}$Zr
We propose to measure the neutron capture cross section of the radioactive isotope $^{93}$Zr. This project aims at the substantial improvement of existing results for applications in nuclear astrophysics and emerging nuclear technologies. In particular, the superior quality of the data that can be obtained at n_TOF will allow on one side a better characterization of s-process nucleosynthesis and on the other side a more accurate material balance in systems for transmutation of nuclear waste, given that this radioactive isotope is widely present in fission products.
Charge changing cross sections of relativistic uranium
We report equilibrium charge state distributions of uranium at energies of 962 MeV/nucleon, 437 MeV/nucleon and 200 MeV/nucleon in low Z and high Z targets and the cross sections for U92+ reversible U91+ and U91+ reversible U90+ at 962 MeV/nucleon and 437 MeV/nucleon. Equilibrium thickness Cu targets produce approx. = 5% bare U92+ at 200 MeV/nucleon and 85% U92+ at 962 MeV/nucleon. 7 references, 5 figures
Fission cross section measurements for minor actinides
Fursov, B. [IPPE, Obninsk (Russian Federation)
1997-03-01
The main task of this work is the measurement of fast neutron induced fission cross section for minor actinides of {sup 238}Pu, {sup 242m}Am, {sup 243,244,245,246,247,248}Cm. The task of the work is to increase the accuracy of data in MeV energy region. Basic experimental method, fissile samples, fission detectors and electronics, track detectors, alpha counting, neutron generation, fission rate measurement, corrections to the data and error analysis are presented in this paper. (author)
LEP vacuum chamber, cross-section
1983-01-01
Cross-section of the final prototype for the LEP vacuum chamber. The elliptic main-opening is for the beam. The small channel to the left is for the cooling water, to carry away the heat deposited by the synchrotron radiation. The square channel to the right houses the Non-Evaporable Getter (NEG) pump. The chamber is made from extruded aluminium. Its outside is clad with lead, to stop the synchrotron radiation emitted by the beam. For good adherence between Pb and Al, the Al chamber was coated with a thin layer of Ni. Ni being slightly magnetic, some resulting problems had to be overcome. See also 8301153.
Critical behavior of cross sections at LHC
Dremin, I M
2016-01-01
Recent experimental data on elastic scattering of high energy protons show that the critical regime has been reached at LHC energies. The approach to criticality is demonstrated by increase of the ratio of elastic to total cross sections from ISR to LHC energies. At LHC it reaches the value which can result in principal change of the character of proton interactions. The treatment of new physics of hollowed toroid-like hadrons requires usage of another branch of the unitarity condition. Its further fate is speculated and interpreted with the help of the unitarity condition in combination with present experimental data. The gedanken experiments to distinguish between different possibilities are proposed.
Neutron absorption cross section of uranium-236
U-236 neutron absorption was measured as a function of neutron time-of-flight from 20 eV to 1 MeV. The neutron flux was monitored with a 6Li glass scintillator. Average cross sections from 3 keV to 1 MeV were derived. Estimated uncertainties were less than 5% below 600 keV and increased to 9.5% at 1 MeV. Resonance parametrization from 20 eV to a few keV remains to be done. 17 refs., 5 figs., 3 tabs
30 CFR 779.25 - Cross sections, maps, and plans.
2010-07-01
... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Cross sections, maps, and plans. 779.25 Section... RESOURCES § 779.25 Cross sections, maps, and plans. (a) The application shall include cross sections, maps..., maps and plans included in a permit application as required by this section shall be prepared by,...
Monochromatic path crossing exponents and graph connectivity in 2D percolation
Jacobsen, Jesper Lykke; Zinn-Justin, Paul
2002-01-01
We consider the fractal dimensions d_k of the k-connected part of percolation clusters in two dimensions, generalizing the cluster (k=1) and backbone (k=2) dimensions. The codimensions X_k = 2-d_k describe the asymptotic decay of the probabilities P(r,R) ~ (r/R)^{X_k} that an annulus of radii r1 is traversed by k disjoint paths, all living on the percolation clusters. Using a transfer matrix approach, we obtain numerical results for X_k, k
Windowed multipole for cross section Doppler broadening
Josey, C.; Ducru, P.; Forget, B.; Smith, K.
2016-02-01
This paper presents an in-depth analysis on the accuracy and performance of the windowed multipole Doppler broadening method. The basic theory behind cross section data is described, along with the basic multipole formalism followed by the approximations leading to windowed multipole method and the algorithm used to efficiently evaluate Doppler broadened cross sections. The method is tested by simulating the BEAVRS benchmark with a windowed multipole library composed of 70 nuclides. Accuracy of the method is demonstrated on a single assembly case where total neutron production rates and 238U capture rates compare within 0.1% to ACE format files at the same temperature. With regards to performance, clock cycle counts and cache misses were measured for single temperature ACE table lookup and for windowed multipole. The windowed multipole method was found to require 39.6% more clock cycles to evaluate, translating to a 7.9% performance loss overall. However, the algorithm has significantly better last-level cache performance, with 3 fewer misses per evaluation, or a 65% reduction in last-level misses. This is due to the small memory footprint of the windowed multipole method and better memory access pattern of the algorithm.
The Elusive p-air Cross Section
Block, Martin M
2006-01-01
For the $\\pbar p$ and $pp$ systems, we have used all of the extensive data of the Particle Data Group[K. Hagiwara {\\em et al.} (Particle Data Group), Phys. Rev. D 66, 010001 (2002).]. We then subject these data to a screening process, the ``Sieve'' algorithm[M. M. Block, physics/0506010.], in order to eliminate ``outliers'' that can skew a $\\chi^2$ fit. With the ``Sieve'' algorithm, a robust fit using a Lorentzian distribution is first made to all of the data to sieve out abnormally high $\\delchi$, the individual i$^{\\rm th}$ point's contribution to the total $\\chi^2$. The $\\chi^2$ fits are then made to the sieved data. We demonstrate that we cleanly discriminate between asymptotic $\\ln s$ and $\\ln^2s$ behavior of total hadronic cross sections when we require that these amplitudes {\\em also} describe, on average, low energy data dominated by resonances. We simultaneously fit real analytic amplitudes to the ``sieved'' high energy measurements of $\\bar p p$ and $pp$ total cross sections and $\\rho$-values for $\\...
Cross-section measurements for radioactive samples
The measurement of (n,p), (n,α) and (n,γ) 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 obtained from these measurements. In the past, the large background associated with the sample activity limited these types of measurements to radioisotopes with very long half-lives. The advent of the low-energy, high-intensity neutron source at the Los Alamos Neutron Scattering CEnter (LANSCE) has greatly increased the number of nuclei which can be studied. Examples of (n,p) measurements on samples with half lives as short as fifty-three days will be given. The nuclear physics and astrophysics to be learned from these data will be discussed. Additional difficulties are encountered when making (n,γ) rather than (n,p) or (n,α) measurements. However, with a properly-designed detector, and the high peak neutron intensities now available, (n,γ) measurements can be made for nuclei with half lives as short as several months. Progress on the Los Alamos (n,γ) cross-section measurement program for radioactive samples will be discussed. 39 refs., 7 figs
Calculation of cross sections for heavy isotopes
In the present work an integrated system of codes for basic neutron data evaluation were assembled and built. Complete evaluations for the isotopes 240Pu, 241Pu, 242Pu and 238Pu were performed. The following cross sections: total, elastic, radiative capture, fission, total inelastic, partial inelastic, (n,2n), (n,3n) and differential elastic were evaluated as well as the average number of neutrons per neutron-induced fission and the average elastic scattering cosine in the lab system.The data for the plutonium isotopes were incorporated into the German KEDAK file. A method was developed for calculating the energy distributions of the second and third secondary neutrons from the A(n,2n) and (n,3n) reactions in the framework of the compound nucleus theory, and utilizing the nuclear data of the nuclei A, A-1, A-2. This method was used to generate the 238U secondary neutron energy distributions in the incident neutron energy range of 6 to 15 MeV. A nuclear data evaluation for 237U in the resolved inelastic scattering range (10-700 keV) was performed. The compound elastic and partial inelastic scattering cross sections were used in the 238U secondary neutron energy distribution calculations. (B.G.)
Combined crustal-geological cross-section of Ellesmere Island
Stephenson, Randell Alexander; Schiffer, Christian; Oakey, Gordon
Ellesmere Island, in Canada’s Arctic, consists of a series of ~SW-NE trending tectonic provinces, the crustal structure and geological expression of which represent a combination of interplate, accretionary orogenesis in the Palaeozoic and, most recently, intraplate deformation in the Cenozoic...... are reported in detail in another presentation at this symposium (Schiffer et al.). Moho depth, a number of intracrustal horizons and sedimentary thicknesses can be inferred. Meanwhile, geological mapping on Ellesmere Island in the framework of BGR’s (Germany) CASE (“Circum-Arctic Structural Events...... cross-sections have been integrated to produce a single, combined crustal-geological 2-D model of Ellesmere Island with the aim of illuminating the relationships between crustal architecture and geology as expressed at the surface of and in the topography of Ellesmere Island....
Nonlinear 2D convection and enhanced cross-field plasma transport near the MHD instability threshold
Results of theoretical study and computer simulations of nonlinear 2D convection induced by a convective MHD instability near its threshold in FRC-like non-paraxial magnetic confinement system are presented. An appropriate closed set of weakly nonideal reduced MHD equations is derived to describe the self-consistent plasma dynamics. It is shown that the convection forms nonlinear large scale stochastic vortices (convective cells), which tend to restore and to maintain the marginally stable pressure pro e and result in an essentially nonlocal enhanced heat transport. A large amount of data on the structure of the nascent convective flows is obtained and analyzed. The computer simulations of long time plasma evolutions demonstrate such features of the resulting anomalous transport as pro e consistency, L-H transition, external transport barrier, pinch of impurities, etc. (author)
30 CFR 783.25 - Cross sections, maps, and plans.
2010-07-01
... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Cross sections, maps, and plans. 783.25 Section... ENVIRONMENTAL RESOURCES § 783.25 Cross sections, maps, and plans. (a) The application shall include cross sections, maps, and plans showing— (1) Elevations and locations of test borings and core samplings;...
Elastic cross sections in an RSIIp scenario
The elastic differential cross section is calculated at low energies (below 100 MeV) for the elements 3He, 20Ne, 40Ar, 14N, 12C, and for the 208Pb using a finite electromagnetic potential, which is obtained by considering a Randall–Sundrum II scenario modified by the inclusion of p compact extra-dimensions. The length scale is adjusted in the potential to compare with known experimental data and to set bounds for the parameter of the model. The effective four-dimensional (4D) electromagnetic potential is produced by a point charge, as seen from the three-brane that contains it, in uniform motion in an RSIIp scenario. (paper)
Lunar Radar Cross Section at Low Frequency
Rodriguez, P.; Kennedy, E. J.; Kossey, P.; McCarrick, M.; Kaiser, M. L.; Bougeret, J.-L.; Tokarev, Y. V.
2002-01-01
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.
Plasma-based radar cross section reduction
Singh, Hema; Jha, Rakesh Mohan
2016-01-01
This book presents a comprehensive review of plasma-based stealth, covering the basics, methods, parametric analysis, and challenges towards the realization of the idea. The concealment of aircraft from radar sources, or stealth, is achieved through shaping, radar absorbing coatings, engineered materials, or plasma, etc. Plasma-based stealth is a radar cross section (RCS) reduction technique associated with the reflection and absorption of incident electromagnetic (EM) waves by the plasma layer surrounding the structure. A plasma cloud covering the aircraft may give rise to other signatures such as thermal, acoustic, infrared, or visual. Thus it is a matter of concern that the RCS reduction by plasma enhances its detectability due to other signatures. This needs a careful approach towards the plasma generation and its EM wave interaction. The book starts with the basics of EM wave interactions with plasma, briefly discuss the methods used to analyze the propagation characteristics of plasma, and its generatio...
Calculated medium energy fission cross sections
An analysis has been made of medium-energy nucleon induced fission of 238U and 237Np using detailed models of fission, based upon the Bohr-Wheeler formalism. Two principal motivations were associated with these calculations. The first was determination of barrier parameters for proton-rich uranium and neptunium isotopes normally not accessible in lower energy reactions. The second was examination of the consistency between (p,f) experimental data versus new (n,f) data that has recently become available. Additionally, preliminary investigations were also made concerning the effect of fission dynamics on calculated fission cross sections at higher energies where neutron emission times may be significantly less than those associated with fission
Partial cross sections in H- photodetachment
This dissertation reports experimental measurements of partial decay cross sections in the H- photodetachment spectrum. Observed decays of the 1P0 H-**(n) doubly-excitedresonances to the H(N=2) continuum are reported for n=2,3, and 4 from 1990 runs in which the author participated. A recent analysis of 1989 data revealing effects of static electric fields on the partial decay spectrum above 13.5 eV is also presented. The experiments were performed at the High Resolution Atomic Beam Facility. the Los Alamos Meson Physics Facility, with a relativistic H-beam (β=0.842)intersecting a ND:YAG laser. Variation of the intersection angle amounts to Doppler-shifting the photon energy, allowing continuous tuning of the laser energy as viewed from the moving ions' frame
Radar Cross Section of Moving Objects
Gholizade, H
2013-01-01
I investigate the effects of movement on radar cross section calculations. The results show that relativistic effects (the constant velocity case) can change the RCS of moving targets by changing the incident plane wave field vectors. As in the Doppler effect, the changes in the fields are proportional to $\\frac{v}{c}$. For accelerated objects, using the Newtonian equations of motion yields an effective electric field (or effective current density) on the object due to the finite mass of the conducting electrons. The results indicate that the magnetic moment of an accelerated object is different from that of an un-accelerated object, and this difference can change the RCS of the object. Results for moving sphere and non-uniformly rotating sphere are given and compared with static (\\textbf{v}=0) case.
Luo, Y.; Xia, J.; Liu, J.; Xu, Y.; Liu, Q.
2008-01-01
Multichannel Analysis of Surface Waves utilizes a multichannel recording system to estimate near-surface shear (S)-wave velocities from high-frequency Rayleigh waves. A pseudo-2D S-wave velocity (vS) section is constructed by aligning 1D models at the midpoint of each receiver spread and using a spatial interpolation scheme. The horizontal resolution of the section is therefore most influenced by the receiver spread length and the source interval. The receiver spread length sets the theoretical lower limit and any vS structure with its lateral dimension smaller than this length will not be properly resolved in the final vS section. A source interval smaller than the spread length will not improve the horizontal resolution because spatial smearing has already been introduced by the receiver spread. In this paper, we first analyze the horizontal resolution of a pair of synthetic traces. Resolution analysis shows that (1) a pair of traces with a smaller receiver spacing achieves higher horizontal resolution of inverted S-wave velocities but results in a larger relative error; (2) the relative error of the phase velocity at a high frequency is smaller than at a low frequency; and (3) a relative error of the inverted S-wave velocity is affected by the signal-to-noise ratio of data. These results provide us with a guideline to balance the trade-off between receiver spacing (horizontal resolution) and accuracy of the inverted S-wave velocity. We then present a scheme to generate a pseudo-2D S-wave velocity section with high horizontal resolution using multichannel records by inverting high-frequency surface-wave dispersion curves calculated through cross-correlation combined with a phase-shift scanning method. This method chooses only a pair of consecutive traces within a shot gather to calculate a dispersion curve. We finally invert surface-wave dispersion curves of synthetic and real-world data. Inversion results of both synthetic and real-world data demonstrate that
Single-level resonance parameters fit nuclear cross-sections
Drawbaugh, D. W.; Gibson, G.; Miller, M.; Page, S. L.
1970-01-01
Least squares analyses of experimental differential cross-section data for the U-235 nucleus have yielded single level Breit-Wigner resonance parameters that fit, simultaneously, three nuclear cross sections of capture, fission, and total.
Residual diagnostics for cross-section time series regression models
Baum, Christopher F
2001-01-01
These routines support the diagnosis of groupwise heteroskedasticity and cross-sectional correlation in the context of a regression model fit to pooled cross-section time series (xt) data. Copyright 2001 by Stata Corporation.
Photoneutron cross sections measured by Saclay and Livermore
The differences between the Saclay and Livermore photoneutron cross sections are discussed. It is shown that the differences between Saclay and Livermore (γ,n) and (γ,2n) cross sections arise from the neutron multiplicity sorting. (Author)
Development of an iterative lattice-core coupling method based on MICROX-2 cross section libraries
This paper describes an innovative online cross section generation method, developed based on Iterative Diffusion-Transport (IDT) calculation to minimize the inconsistency and inaccuracy in determining physics parameters by feeding actual reactor core conditions into the cross section generation process. A 2-dimensional (2-D) pin-by-pin lattice program, NEMA, was also developed to generate assembly lattice parameters using the embedded MICROX-2 cross section libraries and Nodal Expansion Method (NEM). The proposed methods were validated against a 2-D miniature core benchmark problem for both NEMA itself and its coupling to a reactor code by the IDT method (NEMA-DIF3D). The computational benchmark calculations have shown that the IDT improves the eigenvalue and power distribution predictions when compared with the conventional offline method. (author)
Electron Impact Ionization of the Edge Plasma Constituents: Partial Cross-Sections
The partial cross-section for positive ions formed via electron impact ionization (EII) to methane (CH3D and CD4), deuteriated ethane (C2D6) and propane (C3H8) have been measured in a crossed electron/neutral beams apparatus with mass spectrometric analysis of the ions. The partial cross-sections of the ions formed via electron impact ionization to these molecules were determined at low temperature (approximately 300 K and 370 K in the case of propane) and at elevated temperature (approximately 700 K). Gas temperature induced differences in the partial cross-sections have been observed. Additionally, the effect of the isotopic composition of a molecules on the partial cross-sections for EII have been observed. (author)
Electron Elastic-Scattering Cross-Section Database
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).
Total cross sections for neutron-nucleus scattering
Suryanarayana, S. V.; H. Naik; Ganesan, S; Kailas, S; Choudhury, R. K.; Kim, Guinyum
2010-01-01
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 section...
Development of an iterative diffusion-transport method based on MICROX-2 cross section libraries
Highlights: • Innovative Iterative Diffusion Transport (IDT) method is developed. • A 2-dimensional (2-D) pin-by-pin lattice program, NEMA, is also developed. • The developed methods and codes are verified on benchmark problems. • Results show that the IDT method improves the global and local predictions. - Abstract: This paper introduces an innovative online cross section generation method, developed based on Iterative Diffusion-Transport (IDT) calculation to minimize the inconsistency and inaccuracy in determining physics parameters by feeding actual reactor core conditions into the cross section generation process. A two-dimensional (2-D) pin-by-pin lattice program, NEMA, was developed to generate assembly lattice parameters using the refined MICROX-2 cross section libraries and Nodal Expansion Method (NEM). The proposed method was verified against a 2-D miniature core (mini-core) benchmark problem. First, the few-group cross sections generated by NEMA were compared with those calculated by a Monte Carlo method code Serpent. Next, the analysis of a 2-D Light Water Reactor (LWR) mini-core benchmark problem was carried out by the nodal transport code DIF3D using few-group cross sections generated by NEMA, and the results were compared with those obtained from the Serpent full core calculation. Finally, the same benchmark problem was solved by the NEMA-DIF3D approach using the IDT coupling method. The computational benchmark calculations have shown that the homogenization technique implemented in NEMA is reliable when producing the few-group cross sections for the reactor core calculation. The IDT method also improves the eigenvalue and power distribution predictions
Finite sum expressions for elastic and reaction cross sections
Nuclear cross section calculations are often performed by using the partial wave method or the Eikonal method through Glauber theory. The expressions for the total cross section, total elastic cross section, and total reaction cross section in the partial wave method involve infinite sums and do not utilize simplifying approximations. Conversely, the Eikonal method gives these expressions in terms of integrals but utilizes the high energy and small angle approximations. In this paper, by using the fact that the lth partial wave component of the T-matrix can be very accurately approximated by its Born term, the infinite sums in each of the expressions for the differential cross section, total elastic cross section, total cross section, and total reaction cross section are re-written in terms of finite sums plus closed form expressions. The differential cross sections are compared to the Eikonal results for 16O+16O,12C+12C, and p+12C elastic scattering. Total cross sections, total reaction cross sections, and total elastic cross sections are compared to the Eikonal results for 12C+12C scattering
Cross sections for electron impact excitation of molecules
The discussion in this chapter is restricted to elastic scattering, rotational, vibrational, and electronic excitation and total scattering cross sections in electron molecule collisions. Experimental data on differential, integral and momentum transfer cross sections are surveyed and short remarks are made on experimental techniques and theoretical approaches used for generating cross section data. 11 references, 3 figures
Radar Cross-section Measurement Techniques
V.G. Borkar
2010-03-01
Full Text Available Radar cross-section (RCS is an important study parameter for defence applications specially dealing with airborne weapon system. The RCS parameter guides the detection range for a target and is therefore studied to understand the effectiveness of a weapon system. It is not only important to understand the RCS characteristics of a target but also to look into the diagnostic mode of study where factors contributing to a particular RCS values are studied. This further opens up subject like RCS suppression and stealth. The paper discusses the RCS principle, control, and need of measurements. Classification of RCS in terms of popular usage is explained with detailed theory of RF imaging and inverse synthetic aperture radar (ISAR. The various types of RCS measurement ranges are explained with brief discussion on outdoor RCS measurement range. The RCS calibration plays a critical role in referencing the measurement to absolute values and has been described.The RCS facility at Reseach Centre Imarat, Hyderabad, is explained with some details of different activities that are carried out including RAM evaluation, scale model testing, and diagnostic imaging.Defence Science Journal, 2010, 60(2, pp.204-212, DOI:http://dx.doi.org/10.14429/dsj.60.341
Resonance capture cross section of 207Pb
Domingo-Pardo, C; Aerts, G; Alvarez-Pol, H; Alvarez-Velarde, F; Andrzejewski, J; Andriamonje, Samuel A; Assimakopoulos, P A; Audouin, L; Badurek, G; Baumann, P; Becvar, F; Berthoumieux, E; Bisterzo, S; Calviño, F; Cano-Ott, D; Capote, R; Carrapico, C; Chepel, V; Cennini, P; Chiaveri, Enrico; Colonna, N; Cortés, G; Couture, A; Cox, J; Dahlfors, M; David, S; Dillman, I; Dolfini, R; Dridi, W; Durán, I; Eleftheriadis, C; Embid-Segura, M; Ferrant, L; Ferrari, A; Ferreira-Marques, R; Fitzpatrick, L; Frais-Kölbl, H; Fujii, K; Furman, W; Gallino, R; Gonçalves, I; González-Romero, E M; Goverdovski, A; Gramegna, F; Griesmayer, E; Guerrero, C; Gunsing, F; Haas, B; Haight, R; Heil, M; Herrera-Martínez, A; Igashira, M; Isaev, S; Jericha, E; Kadi, Y; Käppeler, F K; Karamanis, D; Karadimos, D; Kerveno, M; Ketlerov, V; Köhler, P; Konovalov, V; Kossionides, E; Krticka, M; Lamboudis, C; Leeb, H; Lindote, A; Lopes, I; Lozano, M; Lukic, S; Marganiec, J; Marrone, S; Mastinu, P; Mengoni, A; Milazzo, P M; Moreau, C; Mosconi, M; Neves, F; Oberhummer, Heinz; Oshima, M; O'Brien, S; Pancin, J; Papachristodoulou, C; Papadopoulos, C; Paradela, C; Patronis, N; Pavlik, A; Pavlopoulos, P; Perrot, L; Plag, R; Plompen, A; Plukis, A; Poch, A; Pretel, C; Quesada, J; Rauscher, T; Reifarth, R; Rosetti, M; Rubbia, Carlo; Rudolf, G; Rullhusen, P; Salgado, J; Sarchiapone, L; Savvidis, I; Stéphan, C; Tagliente, G; Taín, J L; Tassan-Got, L; Tavora, L; Terlizzi, R; Vannini, G; Vaz, P; Ventura, A; Villamarín, D; Vincente6, M C; Vlachoudis, V; Vlastou, R; Voss, F; Walter, S; Wendler, H; Wiescher, M; Wisshak, K
2006-01-01
The radiative neutron capture cross section of 207Pb 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 and radiative kernels have been determined for 16 resonances by means of an R-matrix analysis in the neutron energy range from 3 keV to 320 keV. Good agreement with previous measurements was found at low neutron energies, whereas substantial discrepancies appear beyond 45 keV. With the present results, we obtain an s-process contribution of 77(8)% to the solar abundance of 207Pb. This corresponds to an r-process component of 23(8)%, which is important for deriving the U/Th ages of metal poor halo stars.
Production cross sections from phenomenological constraints
Hadronic production cross sections ν sub(n) (s) satisfying exactly the high energy empirical laws known for the first, second and third multiplicity moments are determined. The result is obtained in the form of a second order linear differential equation for ν sub(n) (s) which allows one to calculate explicitly all successive moments. In particular, the fourth moment is in excellent agreement with the data. The asymptotic solution of the equation for ν sub(n) (s) is given analytically. KNO scaling turns out to be an asymptotic property of the solution. The full solution for ν sub(n) (s) is studied numerically and the KNO plot is compared with the data. No free parameters are left to be adjusted except for an overall normalization constant. As expected, KNO scaling sets in rather quickly with increasing n and the agreement with the data is progressively good. This agreement becomes excellent for the whole interval of n/ for which data exist (O) approximately equal to 2. It turns out that the asymptotic solution, given in analytic terms, is an excellent approximation to the data and can thus be used for practical purposes instead of the full solution for calculating ν sub(n) (s). (author)
Differential cross section and related integrals for the Moliere potential
The Moliere potential is widely used in radiation damage simulation studies. It is not much used in analytical transport theory calculations because of the awkward expression for the differential cross section corresponding to the potential. A two step process is followed to obtain a useful cross section: adopting the Lindhard, Nielsen and Scharff (LNS) approximations in order to generate a simpler form of the Moliere cross section and then creating a simple, easy-to-use, fit to that approximate form. Within the framework of the LNS treatment of atomic cross sections, our fit is accurate to 6%. Simple forms for the total cross section and several related quantities are presented. (author)
Graphs of all neutron cross sections and photon production cross sections on the Alternate Monte Carlo Cross Section (AMCCS) library have been plotted along with local neutron heating numbers. The values of ν-bar, the average number of neutrons per fission, are also plotted for appropriate isotopes
Lopez-Sanchez, Marco; Llana-Fúnez, Sergio
2016-04-01
The understanding of creep behaviour in rocks requires knowledge of 3D grain size distributions (GSD) that result from dynamic recrystallization processes during deformation. The methods to estimate directly the 3D grain size distribution -serial sectioning, synchrotron or X-ray-based tomography- are expensive, time-consuming and, in most cases and at best, challenging. This means that in practice grain size distributions are mostly derived from 2D sections. Although there are a number of methods in the literature to derive the actual 3D grain size distributions from 2D sections, the most popular in highly deformed rocks is the so-called Saltykov method. It has though two major drawbacks: the method assumes no interaction between grains, which is not true in the case of recrystallised mylonites; and uses histograms to describe distributions, which limits the quantification of the GSD. The first aim of this contribution is to test whether the interaction between grains in mylonites, i.e. random grain packing, affects significantly the GSDs estimated by the Saltykov method. We test this using the random resampling technique in a large data set (n = 12298). The full data set is built from several parallel thin sections that cut a completely dynamically recrystallized quartz aggregate in a rock sample from a Variscan shear zone in NW Spain. The results proved that the Saltykov method is reliable as long as the number of grains is large (n > 1000). Assuming that a lognormal distribution is an optimal approximation for the GSD in a completely dynamically recrystallized rock, we introduce an additional step to the Saltykov method, which allows estimating a continuous probability distribution function of the 3D grain size population. The additional step takes the midpoints of the classes obtained by the Saltykov method and fits a lognormal distribution with a trust region using a non-linear least squares algorithm. The new protocol is named the two-step method. The
Proton-nucleus cross section at high energies
Wibig, Tadeusz; Sobczynska, Dorota
1998-01-01
Cross sections for proton inelastic collision with different nuclei are described within the Glauber and multiple scattering approximations. A significant difference between approximate `Glauber' formula and exact calculations with a geometrical scaling assumption for very high-energy cross section is shown. Experimental values of proton-proton cross sections obtained using extensive air shower data are based on the relationship of proton-proton and respective proton-air absorption cross sect...
Reference solution for cross section parametrization
Core calculations of nuclear reactors are usually performed by core physics codes (e.g. with NEM or FDM solvers) in diffusion or SP3 approximation of the transport equation. For each fuel type parameterized data libraries are prepared by means of a lattice code. The data libraries are burnup dependent, and the parameterization covers the hyperspace of admissible values of all operational parameters (fuel temperature, moderator density, boron concentration etc.) This approach has two weak spots. The first is, that it is difficult to make perfect parameterization of the data library because of relatively broad range of the parameter values and the fact that the parameters' effect on the macroscopic cross-sections are not mutually independent. The second is that even for perfect parameterizations with precise approximations of the data changes with respect to the feedback parameters the so-called history effects are neglected. It is generally difficult to assess the cumulative errors arising due to the approximative parameterization of the data libraries and due to the history effects. It is as well difficult to assess the efficiency of techniques developed in order to incorporate the history effect in the data library (such as time integration). In this paper we present a tool for reference core calculations in which the above stated approximations are eliminated. This paper presents the solution method, its implementation, as well as the results of a demonstration calculation showing the improvement of the calculation results over the traditional approach, assessing the magnitude of history and parameterization effects importance. The most important feature of the presented method is that it provides the perfect parameterization of macroscopic data, allowing the core physics code developers to understand sources of modeling uncertainties by completely removing the parameterization error (including, unlike other approaches, a complete representation of the
Color dipole cross section and inelastic structure function
Jeong, Yu Seon; Reno, Mary Hall
2014-01-01
Instead of starting from a theoretically motivated form of the color dipole cross section in the dipole picture of deep inelastic scattering, we start with a parametrization of the deep inelastic structure function for electromagnetic scattering with protons, and then extract the color dipole cross section. Using the Donnachie-Landshoff parametrization of $F_2(x,Q^2)$, we find the dipole cross section from an approximate form of the presumed dipole cross section convoluted with the perturbative photon wave function for virtual photon splitting into a color dipole with massless quarks. The color dipole cross section determined this way works quite well in the massive case, reproducing the original Donnachie-Landshoff structure function for $0.1$ GeV$^2\\leq Q^2\\leq 10$ GeV$^2$. We discuss the large and small form of the dipole cross section and compare with other parameterizations.
Polynomial parameterized representation of macroscopic cross section for PWR reactor
Fiel, Joao Claudio B., E-mail: fiel@ime.eb.br [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil). Departamento de Engenharia Nuclear
2015-07-01
The purpose of this work is to describe, by means of Tchebychev polynomial, a parameterized representation of the homogenized macroscopic cross section for PWR fuel element as a function of soluble boron concentration, moderator temperature, fuel temperature, moderator density and {sup 235} U {sub 92} enrichment. Analyzed cross sections are: fission, scattering, total, transport, absorption and capture. This parameterization enables a quick and easy determination of the problem-dependent cross-sections to be used in few groups calculations. The methodology presented here will enable to provide cross-sections values to perform PWR core calculations without the need to generate them based on computer code calculations using standard steps. The results obtained by parameterized cross-sections functions, when compared with the cross-section generated by SCALE code calculations, or when compared with K{sub inf}, generated by MCNPX code calculations, show a difference of less than 0.7 percent. (author)
Resonance Averaged Photoionization Cross Sections for Astrophysical Models
Bautista, M A; Pradhan, A K
1997-01-01
We present ground state photoionization cross sections of atoms and ions averaged over resonance structures for photoionization modeling of astrophysical sources. The detailed cross sections calculated in the close-coupling approximation using the R-matrix method, with resonances delineated at thousands of energies, are taken from the Opacity Project database TOPbase and the Iron Project, including new data for the low ionization stages of iron Fe I--V. The resonance-averaged cross sections are obtained by convolving the detailed cross sections with a Gaussian distribution over the autoionizing resonances. This procedure is expected to minimize errors in the derived ionization rates that could result from small uncertainties in computed positions of resonances, while preserving the overall resonant contribution to the cross sections in the important near threshold regions. The detailed photoionization cross sections at low photon energies are complemented by new relativistic distorted-wave calculations for Z1...
Sterling, N C; Bilodeau, R C; Kilcoyne, A L D; Red, E C; Phaneuf, R A; Aguilar, A
2010-01-01
Absolute photoionization cross-section measurements are reported for Se+ in the photon energy range 18.0-31.0 eV, which spans the ionization thresholds of the 4S_{3/2} ground state and the low-lying 2P_{3/2,1/2} and 2D_{5/2,3/2} metastable states. The measurements were performed using the Advanced Light Source synchrotron radiation facility. Strong photoexcitation-autoionization resonances due to 4p-->nd transitions are seen in the cross-section spectrum and identified with a quantum-defect analysis.
Full text: Ring opening metathesis polymerization (ROMP) has become an important tool for the synthesis of highly defined polymers and various polymer architectures. In the present work, the residual double bonds in ROMP derived polymeric materials were exploited for a photoinduced thiol-ene reaction in order to achieve a selective cross-linking of the macromolecules. To demonstrate the versatility of this reaction for the realization of polymeric microstructures, thin films of poly(norbornene dicarboxylic acid, dimethylester) were structured by means of photolithography. Besides the photoinduced thiol-ene reaction, which was investigated by means of FTIR measurements, also the cross-linking of the macromolecules and thus the change in the solubility were assessed by means of sol-gel analysis. Thin films of this polymer were laterally patterned using conventional single photon lithography leading to resolutions in the μm range. Going a step further, this approach can also be used for realizing 3D polynorborne microstructures employing the two photo absorption writing technique. The obtained 3D features have been visualized by scanning electron microscopy and atomic force microscopy, respectively. The accessibility and reactivity of the polynorbornene main chain C = C double bonds in the thiol-ene reaction paves the way towards novel strategies for the realization of polymer 2D and 3D microstructures. (author)
Projectile and Lab Frame Differential Cross Sections for Electromagnetic Dissociation
Norbury, John W.; Adamczyk, Anne; Dick, Frank
2008-01-01
Differential cross sections for electromagnetic dissociation in nuclear collisions are calculated for the first time. In order to be useful for three - dimensional transport codes, these cross sections have been calculated in both the projectile and lab frames. The formulas for these cross sections are such that they can be immediately used in space radiation transport codes. Only a limited amount of data exists, but the comparison between theory and experiment is good.
LINX-1: a code for linking polynomial cross section files
The capabilities of the LINX-1 code are described. It was developed for the purpose of linking seperate fuel assembly and reflector node polynomial cross section files, obtained by the POLX-1 code, together into a single reactor polynomial cross section library. The output of the polynomial cross section library can be in either binary or fixed (BCD) format. Input data requirements and the format of the output file generated by LINX-1 are also described. 2 refs
Theoretical estimates of cross sections for neutron-nucleus collisions
Mukhopadhyay, Tapan; Lahiri, Joydev; Basu, D. N.
2010-01-01
We construct an analytical model derived from nuclear reaction theory and having a simple functional form to demonstrate the quantitative agreement with the measured cross sections for neutron induced reactions. The neutron-nucleus total, reaction and scattering cross sections, for energies ranging from 5 to 700 MeV and for several nuclei spanning a wide mass range are estimated. Systematics of neutron scattering cross sections on various materials for neutron energies upto several hundred Me...
Simulation of cross sections for practical ALCHEMI
Full text: Precisely known atomic scattering factors are essential for accurate atom location by channeling enhanced microanalysis (ALCHEMI) based on inner-shell ionization. For ALCHEMI using energy dispersive x-ray analysis (EDX), first principles calculations of ionization cross sections, realistically modelling the 'delocalization' of the ionization interaction, give excellent agreement with experiment. Such calculations are complex and computationally intensive. Hence, simple analytic forms are often assumed to describe the ionization potential. Such an approach assumes that the precise shape of the ionization potential is not important but that at least the half width at half maximum (HWHM) should be accurately estimated, for example using estimates of the HWHM from root-mean-square impact parameters for ionization. However this is generally not a good approximation and we have provided more realistic estimates. These are based on accurate atomic scattering form factors for ionization that have been calculated from first principles using relativistic Hartree-Fock wave functions for bound states and Hartree-Slater wave functions for the continuum states. The effective ionization interaction may be approximated by an equivalent local potential. The scattering factors have been calculated for K-shell ionization for elements in the range Z= 6 (carbon) to Z = 50 (tin) and for Z-shell ionization in the range Z = 20 (calcium) to Z = 60 (neodymium). Accurate values of the scattering factors can be obtained by interpolation for incident electron energies between 50 and 400 keV. The utility of these form factors is illustrated, using some data obtained by Matsumura and coworkers during their project to investigate radiation-induced disordering in magnesium aluminate spinel. High angular resolution electron channeling x-ray spectroscopy was employed to investigate ion displacements in MgOnAl2O3 (n = 1.0 and 2.4) irradiated with 1 MeV Ne+ ions or 900 keV electrons at 873
Neutron-capture Cross Sections from Indirect Measurements
Escher, J E; Burke, J T; Dietrich, F S; Ressler, J J; Scielzo, N D; Thompson, I J
2011-10-18
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.
Fano interference and cross-section fluctuations in molecular photodissociation
We derive an expression for the total photodissociation cross section of a molecule incorporating both direct and indirect processes that proceed through excited resonances, and show that it exhibits generalized Beutler-Fano line shapes. Assuming that the closed system can be modeled by random-matrix theory, we derive the statistical properties of the photodissociation cross section and find that they are significantly affected by the direct processes. In the limit of isolated resonances, we find that direct processes suppress the correlation hole of the cross-section autocorrelation function and lead to a maximum in the cross-section distribution
Positive Scattering Cross Sections using Constrained Least Squares
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
Systematics of fission cross sections at the intermediate energy region
Fukahori, Tokio; Chiba, Satoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment
1997-03-01
The systematics was obtained with fitting experimental data for proton induced fission cross sections of Ag, {sup 181}Ta, {sup 197}Au, {sup 206,207,208}Pb, {sup 209}Bi, {sup 232}Th, {sup 233,235,238}U, {sup 237}Np and {sup 239}Pu above 20 MeV. The low energy cross section of actinoid nuclei is omitted from systematics study, since the cross section has a complicated shape and strongly depends on characteristic of nucleus. The fission cross sections calculated by the systematics are in good agreement with experimental data. (author)
Positive Scattering Cross Sections using Constrained Least Squares
Dahl, J.A.; Ganapol, B.D.; Morel, J.E.
1999-09-27
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.
Continuous Extraction of Subway Tunnel Cross Sections Based on Terrestrial Point Clouds
Zhizhong Kang
2014-01-01
Full Text Available An efficient method for the continuous extraction of subway tunnel cross sections using terrestrial point clouds is proposed. First, the continuous central axis of the tunnel is extracted using a 2D projection of the point cloud and curve fitting using the RANSAC (RANdom SAmple Consensus algorithm, and the axis is optimized using a global extraction strategy based on segment-wise fitting. The cross-sectional planes, which are orthogonal to the central axis, are then determined for every interval. The cross-sectional points are extracted by intersecting straight lines that rotate orthogonally around the central axis within the cross-sectional plane with the tunnel point cloud. An interpolation algorithm based on quadric parametric surface fitting, using the BaySAC (Bayesian SAmpling Consensus algorithm, is proposed to compute the cross-sectional point when it cannot be acquired directly from the tunnel points along the extraction direction of interest. Because the standard shape of the tunnel cross section is a circle, circle fitting is implemented using RANSAC to reduce the noise. The proposed approach is tested on terrestrial point clouds that cover a 150-m-long segment of a Shanghai subway tunnel, which were acquired using a LMS VZ-400 laser scanner. The results indicate that the proposed quadric parametric surface fitting using the optimized BaySAC achieves a higher overall fitting accuracy (0.9 mm than the accuracy (1.6 mm obtained by the plain RANSAC. The results also show that the proposed cross section extraction algorithm can achieve high accuracy (millimeter level, which was assessed by comparing the fitted radii with the designed radius of the cross section and comparing corresponding chord lengths in different cross sections and high efficiency (less than 3 s/section on average.
Cross sections for the reaction 197Au(γ, chin)(chi<=12) have been measured for bremsstrahlung end-point energies in the range 60-340 MeV. From these dominant cross sections, the total photon absorption cross section is determined using a cascade-evaporation calculation to account for the missing reaction channels. The enhancement factor for the classical E1 sum rule is found to be 0.93+-0.10. (orig.)
Cross Sections for Inner-Shell Ionization by Electron Impact
An analysis is presented of measured and calculated cross sections for inner-shell ionization by electron impact. We describe the essentials of classical and semiclassical models and of quantum approximations for computing ionization cross sections. The emphasis is on the recent formulation of the distorted-wave Born approximation by Bote and Salvat [Phys. Rev. A 77, 042701 (2008)] that has been used to generate an extensive database of cross sections for the ionization of the K shell and the L and M subshells of all elements from hydrogen to einsteinium (Z = 1 to Z = 99) by electrons and positrons with kinetic energies up to 1 GeV. We describe a systematic method for evaluating cross sections for emission of x rays and Auger electrons based on atomic transition probabilities from the Evaluated Atomic Data Library of Perkins et al. [Lawrence Livermore National Laboratory, UCRL-ID-50400, 1991]. We made an extensive comparison of measured K-shell, L-subshell, and M-subshell ionization cross sections and of Lα x-ray production cross sections with the corresponding calculated cross sections. We identified elements for which there were at least three (for K shells) or two (for L and M subshells) mutually consistent sets of cross-section measurements and for which the cross sections varied with energy as expected by theory. The overall average root-mean-square deviation between the measured and calculated cross sections was 10.9% and the overall average deviation was −2.5%. This degree of agreement between measured and calculated ionization and x-ray production cross sections was considered to be very satisfactory given the difficulties of these measurements
Ni elemental neutron induced reaction cross-section evaluation
A completely new evaluation of the nickel neutron induced reaction cross sections was undertaken as a part of the ENDF/B-V effort. (n,xy) reactions and capture reaction time from threshold to 20 MeV were considered for 5860616264Ni isotopes to construct the corresponding reaction cross section for natural nickel. Both experimental and theoretical calculated results were used in evaluating different partial cross sections. Precompound effects were included in calculating (n,xy) reaction cross sections. Experimentally measured total section data extending from 0.7 MeV to 20 MeV were used to generate smooth cross section. Below 0.7 to MeV elastic and capture cross sections are represented by resonance parameters. Inelastic angular distributions to the discrete isotopic levels and elemental elastic angular distributions are included in the evaluated data file. Gamma production cross sections and energy distribution due to capture and the (n,xy) reactions were evaluated from experimental data. Finally, error files are constructed for all partial cross sections
Modeling and analysis of ground target radiation cross section
SHI Xiang; LOU GuoWei; LI XingGuo
2008-01-01
Based on the analysis of the passive millimeter wave (MMW) radiometer detection, the ground target radiation cross section is modeled as the new token for the target MMW radiant characteristics. Its ap-plication and actual testing are discussed and analyzed. The essence of passive MMW stealth is target radiation cross section reduction.
Analysis of cross sections using various nuclear potential
The relevant astrophysical reaction rates which are derived from the reaction cross sections are necessary input to the reaction network. In this work, we analyse several theoretical models of the nuclear potential which give better prediction of the cross sections for some selected reactions
Total Cross Sections at High Energies - An Update
Fazal-e-Aleem; Sohail Afzal Tahir; M. Alam Saeed; M. Qadeer Afzal
2002-01-01
Current and future measurements for the total cross sections at E-811, PP2PP, CSM, FELIX, and TOTEMhave been analyzed using various models. In the light of this study an attempt has been made to focus on the behaviorof total cross section at very high energies.
Surrogate reaction methods for neutron induced cross-sections
A brief discussion on surrogate reaction methods and some of the recent results on neutron induced fission cross-section measurements carried out by our group and the possibility of extending the measurements for determining (n,g), (n,2n) and (n,p) reaction cross-sections by surrogate reaction method are presented
Cross Sections for Electron Collisions with Carbon Monoxide
Cross section data are collected and reviewed for electron collisions with carbon monoxide. Collision processes included are total scattering, elastic scattering, momentum transfer, excitations of rotational, vibrational and electronic states, ionization, and dissociation. For each process, recommended values of the cross sections are presented, when possible. The literature has been surveyed through to the end of 2013
Applications of the BEam Cross section Analysis Software (BECAS)
Blasques, José Pedro Albergaria Amaral; Bitsche, Robert; Fedorov, Vladimir;
2013-01-01
A newly developed framework is presented for structural design and analysis of long slender beam-like structures, e.g., wind turbine blades. The framework is based on the BEam Cross section Analysis Software – BECAS – a finite element based cross section analysis tool. BECAS is used for the...
Learning of Cross-Sectional Anatomy Using Clay Models
Oh, Chang-Seok; Kim, Ji-Young; Choe, Yeon Hyeon
2009-01-01
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…
On the scattering cross section of passive linear arrays
Solymar, L.
1973-01-01
A general formula is derived for the scattering cross section of a passiven-element linear array consisting of isotropic radiators. When all the reactances are tuned out and scattering in the mirror direction is investigated, it is found thatA_{sr}, the relative scattering cross section is equal to...
Simplified polynomial representation of cross sections for reactor calculation
It is shown a simplified representation of a cross section library generated by transport theory using the cell model of Wigner-Seitz for typical PWR fuel elements. The effect of burnup evolution through tables of reference cross sections and the effect of the variation of the reactor operation parameters considered by adjusted polynomials are presented. (M.C.K.)
Parametric equations for calculation of macroscopic cross sections
Botelho, Mario Hugo; Carvalho, Fernando, E-mail: mariobotelho@poli.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear
2015-07-01
Neutronic calculations of the core of a nuclear reactor is one thing necessary and important for the design and management of a nuclear reactor in order to prevent accidents and control the reactor efficiently as possible. To perform these calculations a library of nuclear data, including cross sections is required. Currently, to obtain a cross section computer codes are used, which require a large amount of processing time and computer memory. This paper proposes the calculation of macroscopic cross section through the development of parametric equations. The paper illustrates the proposal for the case of macroscopic cross sections of absorption (Σa), which was chosen due to its greater complexity among other cross sections. Parametric equations created enable, quick and dynamic way, the determination of absorption cross sections, enabling the use of them in calculations of reactors. The results show efficient when compared with the absorption cross sections obtained by the ALPHA 8.8.1 code. The differences between the cross sections are less than 2% for group 2 and less than 0.60% for group 1. (author)
Cross section probability tables in multi-group transport calculations
The use of cross section probability tables in multigroup transport calculations is presented. Emphasis is placed on how probability table parameters are generated in a multigroup cross section processor and how existing transport codes must be modifed to use them. In order to illustrate the accuracy obtained by using probability tables, results are presented for a variety of neutron and photon transport problems
Possibility of spin mechanism of total cross section growth
The possibility of existence of the spin mechanism of total cross section growth is considered. A nucleon-nucleon scattering is studied. The energy dependence of scattering amplitude and possible effects related with the spin mechanism of total cross section growth are studied. It is shown that the considered mechanism can play a great role at high energies
Temperature dependence of the HNO3 UV absorption cross sections
Burkholder, James B.; Talukdar, Ranajit K.; Ravishankara, A. R.; Solomon, Susan
1993-01-01
The temperature dependence of the HNO3 absorption cross sections between 240 and 360 K over the wavelength range 195 to 350 nm has been measured using a diode array spectrometer. Absorption cross sections were determined using both (1) absolute pressure measurements at 298 K and (2) a dual absorption cell arrangement in which the absorption spectrum at various temperatures is measured relative to the room temperature absorption spectrum. The HNO3 absorption spectrum showed a temperature dependence which is weak at short wavelengths but stronger at longer wavelengths which are important for photolysis in the lower stratosphere. The 298 K absorption cross sections were found to be larger than the values currently recommended for atmospheric modeling (DeMore et al., 1992). Our absorption cross section data are critically compared with the previous measurements of both room temperature and temperature-dependent absorption cross sections. Temperature-dependent absorption cross sections of HNO3 are recommended for use in atmospheric modeling. These temperature dependent HNO3 absorption cross sections were used in a two-dimensional dynamical-photochemical model to demonstrate the effects of the revised absorption cross sections on loss rate of HNO3 and the abundance of NO2 in the stratosphere.
Nuclear characteristics of Pu fueled LWR and cross section sensitivities
Takeda, Toshikazu [Osaka Univ., Suita (Japan). Faculty of Engineering
1998-03-01
The present status of Pu utilization to thermal reactors in Japan, nuclear characteristics and topics and cross section sensitivities for analysis of Pu fueled thermal reactors are described. As topics we will discuss the spatial self-shielding effect on the Doppler reactivity effect and the cross section sensitivities with the JENDL-3.1 and 3.2 libraries. (author)
The effect of the decay data on activation cross section
The effect of the decay data on evaluation of activation cross section is investigated. Present work shows that these effects must be considered carefully when activation cross section is evaluated. Sometime they are main reason for causing the discrepancies among the experimental data
Minijets, soft gluon resummation and photon cross-sections
Godbole, R. M.; Grau, A.; Pancheri, G.; Srivastava, Y. N.
2008-01-01
We compare the high energy behaviour of hadronic photon-photon cross-sections in different models. We find that the photon-photon cross-section appears to rise faster than the purely hadronic ones (proton-proton and proton-antiproton).
Measurement of the fission cross section of 238Pu
The fission cross sections of 238Pu have been measured from 0.1 eV to 80 keV energy range using the Rensselaer Intense Neutron Spectrometer. The cross sections were normalized to the 235U ENDF/B-V data broadened to the resolution of the Rensselaer Intense Neutron Spectrometer system. The fission areas and widths were determined for the resolved low-energy resonances. The ENDF/B-V fission cross sections for the 238Pu isotope are, in general, not in good agreement with the measured cross sections and a new evaluation is recommended. The observations of structure in the unresolved fission cross sections is suggestive of the existence of intermediate structure. 18 refs., 1 fig., 1 tab
Capture cross-section of threading dislocations in thin films
Highlights: ► We study the effect of film stress on capture cross-section of interacting threads. ► Capture cross-section area diverges near film channeling stress. ► Thread interactions are much more likely when local stress is near critical stress. - Abstract: The capture cross section for annihilation of two threads with opposite Burgers vectors moving on orthogonal slip planes in a thin film is examined using a numerical model. The initial configurations of threads that lead to annihilation are mapped out for a range of applied film stresses. The area of the region of initial configurations that lead to annihilation at a given stress and thickness is the capture cross-section. The size of the capture cross-section is shown to be highly sensitive to the applied stress relative to the critical stress for dislocation motion imposed by the film thickness.
Anomalously large neutron capture cross sections: a random phenomenon?
Carlson, B V; Kerman, A K
2015-01-01
We discuss the existence of huge thermal neutron capture cross sections in several nuclei. The values of the cross sections are several orders of magnitude bigger than expected at these very low energies. We lend support to the idea that this phenomenon is random in nature and is similar to what we have learned from the study of parity violation in the actinide region. The idea of statistical doorways is advanced as a unified concept in the delineation of large numbers in the nuclear world. The average number of maxima per unit mass, $$ in the capture cross section is calculated and related to the underlying cross section correlation function and found to be $ = \\frac{3}{\\pi \\sqrt{2}\\gamma_{A}}$, where $\\gamma_{A}$ is a characteristic mass correlation width which designates the degree of remnant coherence in the system. We trace this coherence to nucleosynthesis which produced the nuclei whose neutron capture cross sections are considered here.
Transport model based on three-dimensional cross-section generation for TRIGA core analysis
Kriangchaiporn, Nateekool
This dissertation addresses the development of a reactor core physics model based on 3-D transport methodology utilizing 3-D multigroup fuel lattice cross-section generation and core calculation for PSBR. The proposed 3-D transport calculation scheme for reactor core simulations is based on the TORT code. The methodology includes development of algorithms for 2-D and 3-D cross-section generation. The fine- and broad-group structures for the TRIGA cross-section generation problems were developed based on the CPXSD (Contributon and Point-wise Cross-Section Driven) methodology that selects effective group structure. Along with the study of cross section generation, the parametric studies for SN calculations were performed to evaluate the impact of the spatial meshing, angular, and scattering order variables and to obtain the suitable values for cross-section collapsing of the TRIGA cell problem. The TRIGA core loading 2 is used to verify and validate the selected effective group structures. Finally, the 13 group structure was selected to use for core calculations. The results agree with continuous energy for eigenvalues and normalized pin power distribution. The Monte Carlo solutions are used as the references.
Nelson, R; R. Vogt; Frawley, A. D.
2012-01-01
We explore the available parameter space that gives reasonable fits to the total charm cross section to make a better estimate of its true uncertainty. We study the effect of the parameter choices on the energy dependence of the J/\\psi\\ cross section.
Meeting cross-section requirements for nuclear-energy design
Current requirements in cross-section data that are essential to nuclear-energy programmes are summarized and explained and some insight into how these data might be obtained is provided. The six sections of the paper describe: design parameters and target accuracies; data collection, evaluation and analysis; determination of high-accuracy differential nuclear data for technological applications; status of selected evaluated nuclear data; analysis of benchmark testing; identification of important cross sections and inferred needs. (U.K.)
Meeting cross section requirements for nuclear energy design
The purpose of this report is to summarize and explain current requirements in cross section data that are essential to nuclear energy programs and to provide some insight into how these data might be obtained. The report is divided into six sections that describe: design parameters and target accuracies; data collection, evaluation, and analysis; determination of high accuracy differential nuclear data for technological applications; status of selected evaluated nuclear data; analysis of benchmark testing; and identification of important cross sections and inferred needs
Panman, Matthijs R; van Dijk, Chris N; Meuzelaar, Heleen; Woutersen, S
2015-01-28
We present a simple method to measure the dynamics of cross peaks in time-resolved two-dimensional vibrational spectroscopy. By combining suitably weighted dispersed pump-probe spectra, we eliminate the diagonal contribution to the 2D-IR response, so that the dispersed pump-probe signal contains the projection of only the cross peaks onto one of the axes of the 2D-IR spectrum. We apply the method to investigate the folding dynamics of an alpha-helical peptide in a temperature-jump experiment and find characteristic folding and unfolding time constants of 260 ± 30 and 580 ± 70 ns at 298 K. PMID:25637962
Panman, Matthijs R.; van Dijk, Chris N.; Meuzelaar, Heleen; Woutersen, S.
2015-01-01
We present a simple method to measure the dynamics of cross peaks in time-resolved two-dimensional vibrational spectroscopy. By combining suitably weighted dispersed pump-probe spectra, we eliminate the diagonal contribution to the 2D-IR response, so that the dispersed pump-probe signal contains the projection of only the cross peaks onto one of the axes of the 2D-IR spectrum. We apply the method to investigate the folding dynamics of an alpha-helical peptide in a temperature-jump experiment and find characteristic folding and unfolding time constants of 260 ± 30 and 580 ± 70 ns at 298 K.
The photonuclear absorption cross section of Pb, σ(TOT:Esub(γ), is studied in the 145-440 MeV Δ resonance range using a quasi-monochromatic photon beam obtained by monoenergetic positon in-flight annihilation. This study is deduced of the cross section measurement for at least j neutron emission σsup(j))Esub(γ). The cross sections of reactions with 1 or 0 neutron are evaluated as the same values as the experimental errors. The variation of the photonuclear absorption cross section for a nuclear σ(TOT:Esub(γ)/A is mass independent for A<=4-6. It seems that the damping between σ(TOT:Esub(γ)/A and the cross section of the free nucleon is caused by the Fermi movement of the nucleons. In conclusion: it seems that the excitation of the nucleus in the Δ resonance region is produced on free nucleons and there are no collective states
Neutron standard cross sections in reactor physics - Need and status
The design and improvement of nuclear reactors require detailed neutronics calculations. These calculations depend on comprehensive libraries of evaluated nuclear cross sections. Most of the cross sections that form the data base for these evaluations have been measured relative to neutron cross-section standards. The use of these standards can often simplify the measurement process by eliminating the need for a direct measurement of the neutron fluence. The standards are not known perfectly, however; thus the accuracy of a cross-section measurement is limited by the uncertainty in the standard cross section relative to which it is measured. Improvements in a standard cause all cross sections measured relative to that standard to be improved. This is the reason for the emphasis on improving the neutron cross-section standards. The continual process of measurement and evaluation has led to improvements in the accuracy and range of applicability of the standards. Though these improvements have been substantial, this process must continue in order to obtain the high-quality standards needed by the user community
The total collision cross section in the glory region
Chapter 1 presents a calculation of approximate total cross sections in the glory region from noble gas potentials. The relations between the main features of the total cross section and the properties of the potential to which these are sensitive are extensively investigated in chapter II. A beam apparatus has been developed, which allows for accurate measurements on the total cross section. All effects due to the finite angular and velocity resolution of the apparatus can be eliminated from the data to yield actual total cross sections as a function of the relative velocity. This facilitates a comparison to total cross sections predicted by potentials available in the literature. A brief description of the apparatus and of the data reduction is given in chapter III. The total cross section data obtained for various noble gas combinations are presented and analysed in chapter IV, where also a large number of potentials proposed in the literature is tested. In chapter V the quenching of the glories in the case of a non-spherical interaction is analysed. Subsequently, total cross section data for some atom-molecule systems are discussed. (Auth.)
Cross-Sectional Drawing Techniques And The Artist
Berry, William A.
1980-07-01
Although Democritus, a Greek pholosopher of the fifth century B.C. described the use of cross-sections in analyzing a solid form, this method was not extensively developed in art until the Renaissance. The earliest treatise documenting the integration of the cross-section and linear perspective is Piero della Francesca's De prospective pingendi (c. 1480), in which a drawing of the human head is mathematically conceived and plotted by means of cross-section contours. Piero's method anticipates contemporary biostereometric techniques and current theories of visual perception. Outside of theoretical treatises the complete cross-section rarely occurs in art, though certain pictorial elements such as the religious halo can be interpreted as cross-sections. The chan-ging representation of the halo in art of the Medieval, Renaissance and Baroque periods parallels the development of the artist's concepts and techniques for representing form and space. During the Renaissance and Baroque periods the widespread use of contour hatching, a drawing technique based on the cross-section, indicates that the cross-section concept has played a greater role in pictorial representation than has generally been recognized.
Electron impact ionization cross sections of beryllium-tungsten clusters*
Sukuba, Ivan; Kaiser, Alexander; Huber, Stefan E.; Urban, Jan; Probst, Michael
2016-01-01
We report calculated electron impact ionization cross sections (EICSs) of beryllium-tungsten clusters, BenW with n = 1,...,12, from the ionization threshold to 10 keV using the Deutsch-Märk (DM) and the binary-encounter-Bethe (BEB) formalisms. The positions of the maxima of DM and BEB cross sections are mostly close to each other. The DM cross sections are more sensitive with respect to the cluster size. For the clusters smaller than Be4W they yield smaller cross sections than BEB and vice versa larger cross sections than BEB for clusters larger than Be6W. The maximum cross section values for the singlet-spin groundstate clusters range from 7.0 × 10-16 cm2 at 28 eV (BeW) to 54.2 × 10-16 cm2 at 43 eV (Be12W) for the DM cross sections and from 13.5 × 10-16 cm2 at 43 eV (BeW) to 38.9 × 10-16 cm2 at 43 eV (Be12W) for the BEB cross sections. Differences of the EICSs in different isomers and between singlet and triplet states are also explored. Both the DM and BEB cross sections could be fitted perfectly to a simple expression used in modeling and simulation codes in the framework of nuclear fusion research. Contribution to the Topical Issue "Atomic Cluster Collisions (7th International Symposium)", edited by Gerardo Delgado Barrio, Andrey Solov'Yov, Pablo Villarreal, Rita Prosmiti.Supplementary material in the form of one pdf file available from the Journal web page at http://dx.doi.org/10.1140/epjd/e2015-60583-7
Unified nonlinear analysis for nonhomogeneous anisotropic beams with closed cross sections
Atilgan, Ali R.; Hodges, Dewey H.
1991-01-01
A unified methodology for geometrically nonlinear analysis of nonhomogeneous, anisotropic beams is presented. A 2D cross-sectional analysis and a nonlinear 1D global deformation analysis are derived from the common framework of a 3D, geometrically nonlinear theory of elasticity. The only restrictions are that the strain and local rotation are small compared to unity and that warping displacements are small relative to the cross-sectional dimensions. It is concluded that the warping solutions can be affected by large deformation and that this could alter the incremental stiffnes of the section. It is shown that sectional constants derived from the published, linear analysis can be used in the present nonlinear, 1D analysis governing the global deformation of the beam, which is based on intrinsic equations for nonlinear beam behavior. Excellent correlation is obtained with published experimental results for both isotropic and anisotropic beams undergoing large deflections.
Neutron inelastic cross section measurements for 24Mg
OLACEL A.; Borcea, C.; DESSAGNE Philippe; Kerveno, M.; NEGRET A.; PLOMPEN Arjan
2014-01-01
The gamma production cross sections from the neutron inelastic scattering on 24Mg were measured for neutron energies up to 18 MeV at GELINA (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 7 large volume HPGe detectors placed at 110◦ and 150◦ with respect to the beam direction. The neutron flux was dete...
Thermal neutron capture cross-sections and neutron separation energies
Thermal radiative neutron capture cross-sections have been re-evaluated as part of an ongoing project at the National Nuclear Data Center at Brookhaven National Laboratory at Upton, New York, to update the Neutron Cross-sections compendia, Vol. 1, Parts A and B, Neutron Resonance Parameters and Thermal Capture Cross-sections, published by Academic Press in 1981 and 1984, respectively. Neutron separation energies are evaluated as part of an ongoing project at the Atomic Mass Data Center in Orsay, France. The adopted data are compared with new results derived from this evaluation
Neutron activation cross section measurements and evaluations in CIAE
The cross sections of 28 reactions have been measured by the activation method since 1995 in CIAE. At the same time the cross sections of 40 reactions which we have measured since 1989 have been compiled and evaluated. A brief description of experimental measurement of activation cross sections is given. The data measured after 1995 by ourselves are listed in Table 4 and our evaluations for 40 reactions are listed in Table 5, respectively. A graphical intercomparison with available experimental data isi given in appendix. (author)
Testing of cross section libraries for TRIGA criticality benchmark
Influence of various up-to-date cross section libraries on the multiplication factor of TRIGA benchmark as well as the influence of fuel composition on the multiplication factor of the system composed of various types of TRIGA fuel elements was investigated. It was observed that keff calculated by using the ENDF/B VII cross section library is systematically higher than using the ENDF/B-VI cross section library. The main contributions (∼220 pcm) are from 235U and Zr. (author)
Neutron total scattering cross sections of elemental antimony
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
A method for measuring light ion reaction cross-sections
An experimental procedure for measuring reaction cross-sections of light ions in the energy range 20-50 MeV/nucleon, using a modified attenuation technique, is described. The detection method incorporates a forward detector that simultaneously measures the reaction cross-sections for five different sizes of the solid angle in steps from 99.1% to 99.8% of the total solid angle. The final reaction cross-section values are obtained by extrapolation to the full solid angle
Evaluation of neutron induced reaction cross sections on Rh isotopes
Evaluations of neutron nuclear data on 101,102,103,105Rh in the incident energies up to 20 MeV were performed, using theoretical nuclear reaction model code CCONE. The calculated cross sections of stable 103Rh are in good agreement with measured inelastic scattering, capture, (n, 2n), (n, p), (n, α) and (n, nα) reaction cross sections. The production cross section for the meta-state of 99Tc with half-life of 6.0 h was evaluated for the estimation of nuclear medicine use and resulted in 2.4 mb at a maximum. (author)
Resonance interaction effects in photonucleon reaction cross sections
The fine structure of a giant dipole resonance in the photonuclear reaction cross section is investigated. Developed is a diagram of parametrization of cross sections, angular distribution and polarization for two resonances, one of which is directly excited by gamma-quantum, the second - due to internal and external mixing with the first state. It is shown, that for several reaction channels the interaction effects significantly the energy dependence of the cross sections and results in qualitative effects in the photonuclear angular distributions and polarization of photonucleons
Comparison of fission and capture cross sections of minor actinides
Nakagawa, T
2003-01-01
The fission and capture cross sections of minor actinides given in JENDL-3.3 are compared with other evaluated data and experimental data. The comparison was made for 32 nuclides of Th-227, 228, 229, 230, 233, 234, Pa-231, 232, 233, U-232, 234, 236, 237, Np-236, 237, 238, Pu-236, 237, 238, 242, 244, Am-241, 242, 242m, 243, Cm-242, 243, 244, 245, 246, 247 and 248. Given in the present report are figures of these cross sections and tables of cross sections at 0.0253 eV and resonance integrals.
Neutron-induced fission cross-section of 231Pa
A first series of fission cross-section measurements for incident neutron energies between 0.6 and 3.4 MeV has confirmed a first chance threshold value around 1b. In contrast to our findings for the fission cross-section in 233Pa, both the direct and the surrogate cross-section data lead to the same result. This seems to support the assumption, that only in cases, where ingoing and outgoing particle are similar, particle-transfer reactions give results that are in agreement with those obtained from direct compound nuclear reactions
Total cross sections of beauty and charmed mesons on protons
Using a simple scaling law we predict the values of the total cross sections σ(B±p), σBd,s0, σ(bar Bd,s0P), σ(Dd,s±P), σ(D0p), σ(bar D0p) from known total Kp cross sections. We assume that mesons with the same light valence quark, q, and differing only by their heavy valence quark content, Q, have total cross sections on protons which scale as the inverse of the nth power of the reduced mass of the meson. We predict that σ(Q bar q)p > σ(bar Qq)p
Comparison of fission and capture cross sections of minor actinides
The fission and capture cross sections of minor actinides given in JENDL-3.3 are compared with other evaluated data and experimental data. The comparison was made for 32 nuclides of Th-227, 228, 229, 230, 233, 234, Pa-231, 232, 233, U-232, 234, 236, 237, Np-236, 237, 238, Pu-236, 237, 238, 242, 244, Am-241, 242, 242m, 243, Cm-242, 243, 244, 245, 246, 247 and 248. Given in the present report are figures of these cross sections and tables of cross sections at 0.0253 eV and resonance integrals. (author)
Measurements of fission cross-sections. Chapter 4
The steps involved in the measurement of fission cross sections are summarized and the range of techniques available are considered. Methods of fission detection are described with particular emphasis on the neutron energy dependent properties of the fission process and the details of fragment energy loss which can lead to energy-dependent changes in detector efficiency. Selected examples of fission cross-section measurements are presented and methods of data reduction, storage, analysis and evaluation, are examined. Finally requested accuracies for fission cross section data are compared to estimated available accuracies. (U.K.)
Photodetachment cross-section of the negatively charged hydrogen ion
Frolov, Alexei M.
2015-01-01
Photodetachment cross-section $\\sigma_{ph}(p_e)$ of the negatively charged hydrogen ion H$^{-}$ is determined with the use of highly accurate variational wave functions constructed for this ion. Photodetachment cross-sections of the H$^{-}$ ion are also studied for very small and very large values of the photo-electron momentum $p_e$. Maximum of this cross-section and its location have been evaluated to high accuracy. In particular, we have found that $[\\sigma_{ph}(p_e)]_{\\max} \\approx$ 3.862...
Cross Section to Multiplicity Ratios at Very High Energy
Block, M M
2014-01-01
Recent data from the LHC makes it possible to examine an old speculation that at very high energy the total multiplicity and the cross section in elementary particle interactions vary in parallel with energy. Using fits incorporating the new data, it appears that the ratios of the total, elastic, and inelastic cross sections to the average multiplicity N can in fact approach constants at very high energy. The approach to the limit is however quite slow for the total and inelastic cross sections and is not yet reached at LHC energies. The elastic ratio sigma^{el}/N at 7 TeV, however, is not far from its asymptotic value.
Cross polarization caused by perturbed circular cross sections of waveguides and horn antennas
Lier, Erik
1987-03-01
The cross polarization caused by a perturbed cross section of the conical hybrid-mode horn is analyzed. The perturbed cross section is assumed to be slightly elliptical. The theory of Lier and Bergh (1986) for cross polarization in a smooth-walled waveguide supporting the TE11-mode is referred and applied to the HE11 mode as well. Simple analytical formulas which are sufficiently accurate for small ellipticites of the cross-section ellipse are presented. These show that the tolerances on the waveguide diameter are extremely strong, typically on the order of 0.02-0.04 mm in the horn throat for typical horn geometries at 12 GHz.
A genetic algorithm to reduce stream channel cross section data
Berenbrock, C.
2006-01-01
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.
Local Deplanation Of Double Reinforced Beam Cross Section Under Bending
Baltov, Anguel; Yanakieva, Ana
2015-12-01
Bending of beams, double reinforced by means of thin composite layers, is considered in the study. Approximate numerical solution is proposed, considering transitional boundary areas, where smooth quadratic transition of the elasticity modulus and deformations take place. Deplanation of the cross section is also accounted for in the areas. Their thickness is found equalizing the total stiffness of the cross section and the layer stiffness. Deplanation of the cross section of the transitional area is determined via the longitudinal deformation in the reinforcing layer, accounting for the equilibrium between the internal and the external moment, generated by the longitudinal stresses in the cross section. A numerical example is given as an illustration demonstrating model's plausibility. The model allows the design and the calculation of recycled concrete beams double reinforced by means of thin layers. The approach is in agreement with modern design of nearly zero energy buildings (NZEB).
Electronic stopping cross sections for use in ion range calculation
Theoretical and empirical methods of determining the electronic stopping cross sections are discussed. The values used by various authors in ion range calculations are outlined. Recommendations are made for future range calculations. (author)
Nonelastic-scattering cross sections of elemental nickel
Neutron total cross sections of elemental nickel were measured from 1.3 to 4.5 MeV, at intervals of approx. 50 keV, with resolutions of 30 to 50 keV and to accuracies of 1 to 2.5%. Neutron differential-elastic-scattering cross sections were measured from 1.45 to 3.8 MeV, at intervals and with resolutions comparable to those of the total cross sections, and to accuracies of 3 to 5%. The nonelastic-scattering cross section is derived from the measured values to accuracies of greater than or equal to 6%. The experimental results are compared with previously reported values as represented by ENDF/B-V, and areas of consistency and discrepancy, noted. The measured results are shown to be in good agreement with the predictions of a model previously reported by the authors. 4 figures, 1 table
Longitudinal Vibrations of Rheological Rod With Variable Cross Section
Katica（Stevanovic）HEDRIH; AleksandarFILIPOVSKI
1999-01-01
Longitudinal vibrations of rheological rod with variable cross section are examined.Particular solutions and eigenfunction are accomplished for natural vibrations of the rod with hereditary material of standard hereditary body.Some examples are given.
Fission cross section for 242Am.met
The neutron-induced fission cross section for 242Am.met (152y) was measured at the Livermore 100-MeV electron linac in the neutron energy range of 0.01 eV to 20 MeV. Fission fragments were detected using a hemispherical fission chamber. The neutron flux was measured below 10 keV using lithium glass scintillators. Above 10 keV, the 242Am.met fission cross section was measured relative to the 235U fission cross section. Below 20 eV, the data were fit with a sum of single-level Breit-Wigner resonances. Results for the distribution of fission widths, the average fission width, and the average level spacing are presented. The fission cross section in the 100 keV to 20 MeV range is compared with previous measurements
Differential cross sections of positron–hydrogen collisions
Rong-Mei, Yu; Chun-Ying, Pu; Xiao-Yu, Huang; Fu-Rong, Yin; Xu-Yan, Liu; Li-Guang, Jiao; Ya-Jun, Zhou
2016-07-01
We make a detailed study on the angular differential cross sections of positron–hydrogen collisions by using the momentum-space coupled-channels optical (CCO) method for incident energies below the H ionization threshold. The target continuum and the positronium (Ps) formation channels are included in the coupled-channels calculations via a complex equivalent-local optical potential. The critical points, which show minima in the differential cross sections, as a function of the scattering angle and the incident energy are investigated. The resonances in the angular differential cross sections are reported for the first time in this energy range. The effects of the target continuum and the Ps formation channels on the different cross sections are discussed. Project supported by the Nanyang Normal University Science Foundation of China (Grant No. ZX2013017) and the National Natural Science Foundation of China (Grant Nos. 11174066, 61306007, and U1304114).
Local Deplanation Of Double Reinforced Beam Cross Section Under Bending*
Baltov Anguel
2015-12-01
Full Text Available Bending of beams, double reinforced by means of thin composite layers, is considered in the study. Approximate numerical solution is proposed, considering transitional boundary areas, where smooth quadratic transition of the elasticity modulus and deformations take place. Deplanation of the cross section is also accounted for in the areas. Their thickness is found equalizing the total stiffness of the cross section and the layer stiffness. Deplanation of the cross section of the transitional area is determined via the longitudinal deformation in the reinforcing layer, accounting for the equilibrium between the internal and the external moment, generated by the longitudinal stresses in the cross section. A numerical example is given as an illustration demonstrating model’s plausibility. The model allows the design and the calculation of recycled concrete beams double reinforced by means of thin layers. The approach is in agreement with modern design of nearly zero energy buildings (NZEB.
Absolute cross sections for dissociative electron attachment to HCCCN
New absolute cross sections for dissociative electron attachment to HCCCN (cyanoacetylene or propiolonitrile) in the range of 0–10 eV electron energy are presented here, which have been determined from a new analysis of previously reported data (Graupner et al 2006 New J. Phys. 8 117). The highest cross sections are observed for the formation of CN− at 5.3 eV and CCCN− at 5.1 eV; approximately 0.06 Å2 and 0.05 Å2 respectively. As part of the re-analysis, it was necessary to determine absolute cross sections for electron-impact ionization of HCCCN with the binary-encounter Bethe method. These electron-impact ionization absolute cross sections for HCCCN are also presented here; the maximum value was found to be ∼6.6 Å2 at ∼80 eV. (paper)
Scaling of Cross Sections for Ion-atom Impact Ionization
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
The neutron cross-sections of Xe135
Measurements of the total and absorption cross-sections of Xe135 reviewed briefly. The low-energy cross-section is very large and dominated by a single resonance at 0.084 eV; the spin state for this level is not known, this being one of the major uncertainties in the data. The resonance parameters given in the literature were found to give a good fit to the total cross-section but failed to reproduce the preferred 2200 m/sec. value of σγ. A new set of parameters was therefore deduced, by a least-squares analysis, which gave this preferred value of σγ and fitted the shape of the total cross section curve. To obtain this fit it was necessary to re-normalise the curve of σT by 4%. The new parameters are listed, and a discussion of the probable accuracy of the data is included. (author)
Radiative neutron capture cross sections on 176Lu at DANCE
Roig, O.; Jandel, M.; Méot, V.; Bond, E. M.; Bredeweg, T. A.; Couture, A. J.; Haight, R. C.; Keksis, A. L.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.
2016-03-01
The cross section of the neutron capture reaction 176Lu(n ,γ ) has been measured for a wide incident neutron energy range with the Detector for Advanced Neutron Capture Experiments at the Los Alamos Neutron Science Center. The thermal neutron capture cross section was determined to be (1912 ±132 ) b for one of the Lu natural isotopes, 176Lu. The resonance part was measured and compared to the Mughabghab's atlas using the R -matrix code, sammy. At higher neutron energies the measured cross sections are compared to ENDF/B-VII.1, JEFF-3.2, and BRC evaluated nuclear data. The Maxwellian averaged cross sections in a stellar plasma for thermal energies between 5 keV and 100 keV were extracted using these data.
Macroscopic cross section measurements in materials by neutron radiography technique
Macroscopic cross-section of materials play an important role in the study of material properties. Number of materials are used for shielding against penetrating radiation like X-rays, gamma rays and neutrons and exhibit different attenuation cross-sections. Neutron radiography technique is a multi discipline non-destructive technique with a large number of applications. The technique was applied to study and analyze the behavior of different shielding materials against thermal neutrons. Samples as step wedges of graphite, copper, brass and acrylic etc. were fabricated. The test samples were exposed to a beam of thermal neutrons at neutron radiography facility and the transmittance of neutrons through different materials was measured. Gamma-ray contribution and scattered radiation were subtracted from the observed neutron intensities to calculate the neutron macroscopic cross-section. Calculated values of the macroscopic cross-section were compared with the values given in the literature. (author)
Scaling of Cross Sections for Ion-atom Impact Ionization
Kaganovich, I D; Startsev, E
2003-01-01
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.
Models for Photon-photon Total Cross-sections
Godbole, RM; Grau, A.; Pancheri, G.
1999-01-01
We present here a brief overview of recent models describing the photon-photon cross-section into hadrons. We shall show in detail results from the eikonal minijet model, with and without soft gluon summation.
Measurements of the cross sections for charged current deep inelastic scattering in e-p collisions with longitudinally polarised electron beams are presented. The measurements are based on a data sample with an integrated luminosity of 175 pb-1 collected with the ZEUS detector at HERA at a centre-of-mass energy of 318 GeV. The total cross section is given for positively and negatively polarised electron beams. The differential cross-sections dσ/dQ2, dσ/dx and dσ/dy are presented for Q2>200 GeV2. The double-differential cross-section d2σ/dxdQ2 is presented in the kinematic range 2802 and 0.015< x<0.65. The measured cross sections are compared with the predictions of the Standard Model. (orig.)
Electron Swarm Parameters and Electron Collision Cross Sections
Electron collision cross section data for atoms and molecules and electron swarm data in respective gases are important for quantitative modeling of related plasmas. This fact and wide application of plasmas in various fields boos data collection and evaluation activities worldwide. We have been measuring electron swarm parameters (drift velocity, longitudinal diffusion coefficient, ionization/attachment coefficients, and so on) over a wide E/N range (where E is the electric field and N the gas number density) in a number of gases. We also derived a set of electron collision cross sections for each gas so that the set was consistent with our experimental swarm data. Our speciality in studying molecular target is to measure swarm parameters not only in the pure molecular gas but also in dilute molecular gas-argon gas mixtures, the mix rations of the molecule are 0.5-5.0%. The swarm parameters in pure molecular gas depend primarily on the elastic momentum transfer cross section of the molecule and its vibrational excitation cross sections. Those in the mixtures, on the other hand, depend mainly on the elastic momentum transfer cross section of major argon atom and the vibrational cross sections of minor admixed molecule. Alternative use of swarm parameters in pure molecular gas and those in the mixtures enable us to derive the momentum transfer cross section and vibrational cross sections for the molecule separately. Combination of the Ramsauer-Townsend minimum of argon atom and sharp structures in vibrational cross sections of the molecule frequently gives rise prominent E/N dependences in swarm parameters, which can be used to determine the position and magnitude of resonances in the vibrational excitation cross sections. Detailed accounts of the procedure, including estimated uncertainty in our electron swarm data and also in the resultant set of electron collision cross sections, will be given in the presentation by referring to our recent results. Stress will be
Total cross-section measurements progress in nuclear physics
Giacomelli, G; Mulvey, J H
2013-01-01
Total Cross-Section Measurements discusses the cross-sectional dimensions of elementary hadron collisions. The main coverage of the book is the resonance and high energy area of the given collision. A section of the book explains in detail the characteristic of a resonance region. Another section is focused on the location of the high energy region of collision. Parts of the book define the meaning of resonance in nuclear physics. Also explained are the measurement of resonance and the identification of the area where the resonance originates. Different experimental methods to measure the tota
Absolute Total np and pp Cross Section Determinations
Arndt, R A; Laptev, A B; Strakovsky, I I; Workman, R L
2008-01-01
Absolute total cross sections for np and pp scattering below 1000 MeV are determined based on partial-wave analyses of NN scattering data. These cross sections are compared with most recent ENDF/B and JENDL data files, and the Nijmegen partial-wave analysis. Systematic deviations from the ENDF/B and JENDL evaluations are found to exist in the low-energy region.
Singly differential cross sections with exchange for Ps-fragmentation
Ray, Hasi
2008-01-01
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 theore...
Photoproduction models for total cross section and shower development
Cornet Fernando
2015-01-01
Full Text Available A model for the total photoproduction cross section, based on the ansatz that resummation of infrared gluons limits the rise induced by QCD minijets in all the total cross-sections, is used to simulate extended air showers initiated by cosmic rays with the AIRES simulation program. The impact on common shower observables, especially those related with muon production, is analysed and compared with the corresponding results obtained with previous photoproduction models.
Measurement of fusion cross section with neutron halo nuclei
Fusion cross sections of 11Be, 10Be and 9Be have been measured on 209Bi target at 30-70MeV. Due to the neutron halo effect of 11Be, a large enhancement or suppression of the fusion cross section around the Coulomb barrier was theoretically predicted. Comparing the excitation function of 11Be with 10Be at near the Coulomb barrier region, no significant difference has been observed. ((orig.))
Top Quark Pair Production Cross Section at the Tevatron
Peters, Reinhild Yvonne [Manchester U.
2015-09-25
The top quark, discovered in 1995 by the CDF and D0 collaborations at the Tevatron proton antiproton collider at Fermilab, has undergone intense studies in the last 20 years. Currently, CDF and D0 converge on their measurements of top-antitop quark production cross sections using the full Tevatron data sample. In these proceedings, the latest results on inclusive and differential measurements of top-antitop quark production cross sections at the Tevatron are reported.
Elastic cross sections for electron-carbon scattering
Liu Jun-Bo; Wang Yang; Zhou Ya-Jun
2007-01-01
We used the close-coupling optical (CCO) approach to investigate the open-shell carbon atom. The elastic cross sections have been presented at the energies below 90eV, and the present CCO results have been compared with other theoretical results. We found that polarization and the continuum states have significant contributions to the elastic cross sections. The present calculations show that the CCO method is capable of calculating electron scattering from open-shell atoms.
Thermal neutron capture cross sections of tellurium isotopes
New values for thermal neutron capture cross sections of the tellurium isotopes 122Te, 124Te, 125Te, 126Te, 128Te, and 130Te are reported. These values are based on a combination of newly determined partial g-ray cross sections obtained from experiments on targets contained natural Te and gamma intensities per capture of individual Te isotopes. Isomeric ratios for the thermal neutron capture on the even tellurium isotopes are also given
Thermal neutron capture cross sections of tellurium isotopes
New values for thermal neutron capture cross sections of the tellurium isotopes 122Te,124Te,125Te,126Te,128Te, and 130Te are reported. These values are based on a combination of newly determined partial γ-ray cross sections obtained from experiments on targets contained natural Te and γ intensities per capture of individual Te isotopes. Isomeric ratios for the thermal neutron capture on the even tellurium isotopes are also given
Thermal neutron capture cross sections of tellurium isotopes
Tomandl, I.; Honzatko, J.; von Egidy, T.; Wirth, H.-F.; Belgya, T.; Lakatos, M.; Szentmiklosi, L.; Revay, Zs.; Molnar, G.L.; Firestone, R.B.; Bondarenko, V.
2004-03-01
New values for thermal neutron capture cross sections of the tellurium isotopes 122Te, 124Te, 125Te, 126Te, 128Te, and 130Te are reported. These values are based on a combination of newly determined partial g-ray cross sections obtained from experiments on targets contained natural Te and gamma intensities per capture of individual Te isotopes. Isomeric ratios for the thermal neutron capture on the even tellurium isotopes are also given.
Evaluation of neutron reaction cross sections for astrophysics
We have developed a code system to evaluate nuclear reaction cross sections for the nucleosynthesis. The system includes an interface to Reference Input Parameter Library (RIPL), as well as some systematics to extrapolate the parameters into unstable regions. We are focusing on neutron capture processes important for s- and r-processes. The structure of the system is reviewed, and calculated capture cross sections in the fission product mass region are compared with experimental data available. (author)
Majorana Dark Matter Cross Sections with Nucleons at High Energies
Jeong, Yu Seon; Kim, C. S.; Reno, Mary Hall
2012-01-01
Non-relativistic dark matter scattering with nucleons is constrained by direct detection experiments. We use the XENON constraints on the spin-independent and spin-dependent cross section for dark matter scattering with nucleons to constrain a hypothetical Majorana fermionic dark matter particle's couplings to the Higgs boson and Z boson. In the procedure we illustrate the change in the dark matter nucleon cross section as one goes from non-relativistic, coherent scattering to relativistic, i...
Modelling of reaction cross sections and prompt neutron emission
Oberstedt S.; Tudora A.; Hambsch F.-J.
2010-01-01
Accurate nuclear data concerning reaction cross sections and the emission of prompt fission neutrons (i.e. multiplicity and spectra) as well as other fission fragment data are of great importance for reactor physics design, especially for the new Generation IV nuclear energy systems. During the past years for several actinides (238U(n, f) and 237Np(n, f)) both the reaction cross sections and prompt neutron multiplicities and spectra have been calculated within the frame of the EFNUDAT project.
Measurement of distribution density of total neutron cross-sections
Problems of energy resolutions together with difficulties of multilevel analysis make desirable the application of the statistical approach to the description of total cross-section irregularities for intermediate and fast neutrons. Total neutron cross-section probability distributions were found from the analysis of the transmission nonexponentiality. The results for intervals adopted in reactor calculations are compared with recommended values and with those found from high resolution measurements
Determination of molecular ionization cross sections in an ICR spectrometer
Ionization cross sections have been determined for simple gases at 75eV in an ICR spectrometer. Results obtained using a calibrated ion gauge as a pressure indicator yield values which are consistently higher than accepted values by as much as 15%. These results suggest that a more convenient way to measure pressure in ICR experiments might be to record the total ion current and to use the tabulated ionization cross sections where available
Burnup-dependent cross section data for research reactors
Studies currently in progress consider research and test reactors which commonly have burnups of 50 atom percent in 235-U and may reach as high a 70 atom percent. At these levels of burnup changes in cross-section data with burnup become significant. Some preliminary studies of these effects lead to the development of a modified version of REBUS-2 which supports changes in cross-section data with burnup. This version of REBUS-2 allows for changes in the cross-section data only at each time sub-interval in the problem, and these cross-section changes for capture and fission are based on a least squares polynomial fit as a function of burnup. In this paper an attempt is made to evaluate the importance of burnup dependent data for the various isotopes and/or groups, and to assess the accuracy of this method by comparing the REBUS-2 results with results obtained from PDQ-7. The 10 MW IAEA benchmark problem has been selected for this study. A description of the reactor and the XY model can be found in the IAEA Guidebook. The EPRI-CELL4 code was used to generate burnup dependent cross section data for use with both REBUS-2 and PDQ-7. Cross-section data were generated at 10 time steps to a burnup of approximately 50 atom percent in 235-U. The agreement between the PDQ-7 results and the REBUS-2 results with fitted burnup dependent cross-section data are quite good. Burnup dependent cross sections are essential for accurate estimates of cycle lengths and reactivities, and low order polynomial fits of capture and fission data for selected isotopes and energy groups can provide this capability
Unified approach to the multilevel parametrization of resonance cross sections
A combined method of parametrization in the resolved resonance region and an approach to modelling the resonance structure in the unresolved region are suggested. The most typical case for the resonances of the non fissile nuclei with one neutron channel (s-wave resonances or resonances of an arbitrary l and a zero spin of the target nucleus) are considered. It is shown that for such systems the total cross section as well as the absorption cross section can be expressed as ratios of sums of pole terms with respect to energy. The modeling of the resonance structure in the unresolved region is needed for the examination of the resonance self-shielding effects in reactor physics. In this region the analysis of the experimental data (average cross sections and average transmissions) permits the determination of only the average resonance parameters - the strength functions Sn, Sγ. And it is necessary to model the resonance cross sections structure and such models should give the correct average cross section and also conserve the information for the cross sections minima to which the values of the transmissions data are very sensitive
Porosity effects in the neutron total cross section of graphite
Graphite has been used in nuclear reactors since the birth of the nuclear industry due to its good performance as a neutron moderator material. Graphite is still an option as moderator for generation IV reactors due to its good mechanical and thermal properties at high operation temperatures. So, there has been renewed interest in a revision of the computer libraries used to describe the neutron cross section of graphite. For sub-thermal neutron energies, polycrystalline graphite shows a larger total cross section (between 4 and 8 barns) than predicted by existing theoretical models (0.2 barns). In order to investigate the origin of this discrepancy we measured the total cross section of graphite samples of three different origins, in the energy range from 0.001 eV to 10 eV. Different experimental arrangements and sample treatments were explored, to identify the effect of various experimental parameters on the total cross section measurement. The experiments showed that the increase in total cross section is due to neutrons scattered around the forward direction. We associate these small-angle scattered neutrons (SANS) to the porous structure of graphite, and formulate a very simple model to compute its contribution to the total cross section of the material. This results in an analytic expression that explicitly depends on the density and mean size of the pores, which can be easily incorporated in nuclear library codes.
Development of automatic cross section compilation system for MCNP
A development of a code system to automatically convert cross-sections for MCNP is in progress. The NJOY code is, in general, used to convert the data compiled in the ENDF format (Evaluated Nuclear Data Files by BNL) into the cross-section libraries required by various reactor physics codes. While the cross-section library: FSXLIB-J3R2 was already converted from the JENDL-3.2 version of Japanese Evaluated Nuclear Data Library for a continuous energy Monte Carlo code MCNP, the library keeps only the cross-sections at room temperature (300 K). According to the users requirements which want to have cross-sections at higher temperature, say 600 K or 900 K, a code system named 'autonj' is under development to provide a set of cross-section library of arbitrary temperature for the MCNP code. This system can accept any of data formats adopted JENDL that may not be treated by NJOY code. The input preparation that is repeatedly required at every nuclide on NJOY execution is greatly reduced by permitting the conversion process of as many nuclides as the user wants in one execution. A few MCNP runs were achieved for verification purpose by using two libraries FSXLIB-J3R2 and the output of autonj'. The almost identical MCNP results within the statistical errors show the 'autonj' output library is correct. In FY 1998, the system will be completed, and in FY 1999, the user's manual will be published. (K. Tsuchihashi)
Asymptotic behaviour of pion-pion total cross-sections
We derive a sum rule which shows that the Froissart-Martin bound for the asymptotic behaviour of the ππ total cross sections at high energies, if modulated by the Lukaszuk-Martin coefficient of the leading log2 s behaviour, cannot be an optimal bound in QCD. We next compute the total cross sections for π+π−, π±π0 and π0π0 scattering within the framework of the constituent chiral quark model (CχQM) in the limit of a large number of colours Nc and discuss their asymptotic behaviours. The same ππ cross sections are also discussed within the general framework of Large-Nc QCD and we show that it is possible to make an Ansatz for the isospin I=1 and I=0 spectrum which satisfy the Froissart-Martin bound with coefficients which, contrary to the Lukaszuk-Martin coefficient, are not singular in the chiral limit and have the correct Large-Nc counting. We finally propose a simple phenomenological model which matches the low energy behaviours of the σπ±π0total(s) cross section predicted by the CχQM with the high energy behaviour predicted by the Large-Nc Ansatz. The magnitude of these cross sections at very high energies is of the order of those observed for the pp and pp-bar scattering total cross sections
Studies of 54,56Fe Neutron Scattering Cross Sections
Hicks S. F.
2015-01-01
Full Text Available Elastic and inelastic neutron scattering differential cross sections and γ-ray production cross sections have been measured on 54,56Fe at several incident energies in the fast neutron region between 1.5 and 4.7 MeV. All measurements were completed at the University of Kentucky Accelerator Laboratory (UKAL using a 7-MV Model CN Van de Graaff accelerator, along with the neutron production and neutron and γ-ray detection systems located there. The facilities at UKAL allow the investigation of both elastic and inelastic scattering with nearly mono-energetic incident neutrons. Time-of-flight techniques were used to detect the scattered neutrons for the differential cross section measurements. The measured cross sections are important for fission reactor applications and also for testing global model calculations such as those found at ENDF, since describing both the elastic and inelastic scattering is important for determining the direct and compound components of the scattering mechanism. The γ-ray production cross sections are used to determine cross sections to unresolved levels in the neutron scattering experiments. Results from our measurements and comparisons to model calculations are presented.
Updating the IST-LISBON electron cross sections for nitrogen
Alves, L. L.; Sombreireiro, L.; Viegas, P.; Guerra, V.
2013-09-01
In this work we update the complete and consistent set of nitrogen (N2) electron-impact cross-section with the IST-LISBON database, available on the LXCat website. The update has extended, in energy scale up to 1 keV, the cross sections for effective momentum-transfer, excitation to electronic states and ionization. The set further accounts for excitation to rotational and vibrational excited states. Calculations using BOLSIG + with the new cross sections give swarm parameters in very good agreement with available experimental data for the reduced mobility, the characteristic energy and the reduced ionization coefficient, for a very extended E / N range up to 1000 Td. The influence of rotational excitations/de-excitations at low E / N and different rotational temperatures is discussed. A critical evaluation of similarities and differences with sets of N2 cross sections from other databases is carried out. Moreover, the procedure to de-convolute global cross sections into state-to-state vibrational level dependent cross sections is outlined and discussed. Work partially supported by FCT (Pest-OE/SADG/LA0010/2011).
Updated ozone absorption cross section will reduce air quality compliance
Sofen, E. D.; Evans, M. J.; Lewis, A. C.
2015-12-01
Photometric ozone measurements rely upon an accurate value of the ozone absorption cross section at 253.65 nm. This has recently been re-evaluated by Viallon et al. (2015) as 1.8 % smaller than the accepted value (Hearn, 1961) used for the preceding 50 years. Thus, ozone measurements that applied the older cross section systematically underestimate the amount of ozone in air. We correct the reported historical surface data from North America and Europe and find that this modest change in cross section has a significant impact on the number of locations that are out of compliance with air quality regulations if the air quality standards remain the same. We find 18, 23, and 20 % increases in the number of sites that are out of compliance with current US, Canadian, and European ozone air quality health standards for the year 2012. Should the new cross-section value be applied, it would impact attainment of air quality standards and compliance with relevant clean air acts, unless the air quality target values themselves were also changed proportionately. We draw attention to how a small change in gas metrology has a global impact on attainment and compliance with legal air quality standards. We suggest that further laboratory work to evaluate the new cross section is needed and suggest three possible technical and policy responses should the new cross section be adopted.
Calculation of the intermediate energy activation cross section
Furihata, Shiori; Yoshizawa, Nobuaki [Mitsubishi Research Inst., Inc., Tokyo (Japan)
1997-03-01
We discussed the activation cross section in order to predict accurately the activation of soil around an accelerator with high energy and strong intensity beam. For the assessment of the accuracy of activation cross sections estimated by a numerical model, we compared the calculated cross section with various experimental data, for Si(p,x){sup 22}Na, Al(p,x){sup 22}Na, Fe(p,x){sup 22}Na, Si(p,x){sup 7}Be, O(p,x){sup 3}H, Al(p,x){sup 3}H and Si(p,x){sup 3}H reactions. We used three computational codes, i.e., quantum molecular dynamics (QMD) plus statistical decay model (SDM), HETC-3STEP and the semiempirical method developed by Silberberg et.al. It is observed that the codes are accurate above 1GeV, except for {sup 7}Be production. We also discussed the difference between the activation cross sections of proton- and neutron-induced reaction. For the incident energy at 40MeV, it is found that {sup 3}H production cross sections of neutron-induced reaction are ten times as large as those of proton-induced reaction. It is also observed that the choice of the activation cross sections seriously affects to the estimate of saturated radioactivity, if the maximum energy of neutron flux is below 100MeV. (author)
Scruggs, T.; Moraguez, M.; Patankar, K.; Fitz-Coy, N.; Liou, J.-C.; Sorge, M.; Huynh, T.
2016-01-01
Debris fragments from the hypervelocity impact testing of DebriSat are being collected and characterized for use in updating existing satellite breakup models. One of the key parameters utilized in these models is the ballistic coefficient of the fragment which is directly related to its area-to-mass ratio. However, since the attitude of fragments varies during their orbital lifetime, it is customary to use the average cross-sectional area in the calculation of the area-to-mass ratio. The average cross-sectional area is defined as the average of the projected surface areas perpendicular to the direction of motion and has been shown to be equal to one-fourth of the total surface area of a convex object. Unfortunately, numerous fragments obtained from the DebriSat experiment show significant concavity (i.e., shadowing) and thus we have explored alternate methods for computing the average cross-sectional area of the fragments. An imaging system based on the volumetric reconstruction of a 3D object from multiple 2D photographs of the object was developed for use in determining the size characteristic (i.e., characteristics length) of the DebriSat fragments. For each fragment, the imaging system generates N number of images from varied azimuth and elevation angles and processes them using a space-carving algorithm to construct a 3D point cloud of the fragment. This paper describes two approaches for calculating the average cross-sectional area of debris fragments based on the 3D imager. Approach A utilizes the constructed 3D object to generate equally distributed cross-sectional area projections and then averages them to determine the average cross-sectional area. Approach B utilizes a weighted average of the area of the 2D photographs to directly compute the average cross-sectional area. A comparison of the accuracy and computational needs of each approach is described as well as preliminary results of an analysis to determine the "optimal" number of images needed for
Analysis and Design of Rectangular-Cross-Section Nozzles for Scramjet Engine Testing
Gaffney, Richard L., Jr.; Korte, John J.
2004-01-01
The flow in the square-cross-section Mach-6 nozzle used in the NASA Langley Research Center Arc-Heated Scramjet Test Facility has been analyzed using three-dimensional viscous CFD methods. The primary cause of the non-uniform flow exiting the nozzle is identified as cross-flow pressure gradients imposed on wall boundary layers. The cross-flow pressure gradients cause the boundary layer to roll up into counter-rotating vortex pairs on each of the four sides of the nozzle. These four vortex pairs produce significant non-uniformity in the nozzle-exit flow. In order to improve the quality of the test flow in the facility, two alternative nozzle designs (one axisymmetric and one rectangular with a 2-D contour) have been investigated. While the axisymmetric design produced the most uniform flow, the 2-D design also produced very good flow. The 2-D design was selected for further refinement, resulting in a new nozzle design which has been constructed and awaits calibration.
Photoionization cross-sections using the polarization propagator approach
It is shown that the imaginary part of the polarization propagator (PP), when computed at complex frequencies, w+i η, can be, in the limit η -> 0, directly related to the photoionization cross-section. Total photoionization cross-sections can be evaluated directly from the PP, and partial croos-sections can be computed from individual excitation frequencies and transition moments, using the spectral representation of the PP. For complex frequencies not only the real part of the PP but also its imaginary part is propotional to the complex dynamic polarizability. (Author)
Measurements of neutron cross sections of radioactive waste nuclides
Katoh, Toshio [Gifu College of Medical Technology, Seki, Gifu (Japan); Harada, Hideo; Nakamura, Shoji; Tanase, Masakazu; Hatsukawa, Yuichi
1998-01-01
Accurate nuclear reaction cross sections of radioactive fission products and transuranic elements are required for research on nuclear transmutation methods in nuclear waste management. Important fission products in the nuclear waste management are {sup 137}Cs, {sup 135}Cs, {sup 90}Sr, {sup 99}Tc and {sup 129}I because of their large fission yields and long half-lives. The present authors have measured the neutron capture cross sections and resonance integrals of {sup 137}Cs, {sup 90}Sr and {sup 99}Tc. The purpose of this study is to measure the neutron capture cross sections and resonance integrals of nuclides, {sup 129}I and {sup 135}Cs accurately. Preliminary experiments were performed by using Rikkyo University Reactor and JRR-3 reactor at Japan Atomic Energy Research Institute (JAERI). Then, it was decided to measure the cross section and resonance integral of {sup 135}Cs by using the JRR-3 Reactor because this measurement required a high flux reactor. On the other hand, those of {sup 129}I were measured at the Rikkyo Reactor because the product nuclides, {sup 130}I and {sup 130m}I, have short half-lives and this reactor is suitable for the study of short lived nuclide. In this report, the measurements of the cross section and resonance integral of {sup 135}Cs are described. To obtain reliable values of the cross section and resonance integral of {sup 135}Cs(n, {gamma}){sup 136}Cs reaction, a quadrupole mass spectrometer was used for the mass analysis of nuclide in the sample. A progress report on the cross section of {sup 134}Cs, a neighbour of {sup 135}Cs, is included in this report. A report on {sup 129}I will be presented in the Report on the Joint-Use of Rikkyo University Reactor. (author)
242Am/sup m/ fission cross section
The neutron-induced fission cross section of 242Am/sup m/ has been measured over the energy region from 10-3 eV to approx.20 MeV in a series of experiments utilizing a linac-produced ''white'' neutron source and a monoenergetic source of 14.1 MeV neutrons. The cross section was measured relative to that of 235U in the thermal (0.001 to approx.3 eV) and high energy (1 keV to approx.20 MeV) regions and normalized to the ENDF/B-V 235U(n,f) evaluated cross section. In the resonance energy region (0.5 eV to 10 keV) the neutron flux was measured using thin lithium glass scintillators and the relative cross section thus obtained was normalized to the thermal energy measurement. This procedure allowed a consistency check between the thermal and high energy data. The cross section data have a statistical accuracy of approx.0.5% at thermal energies and in the 1-MeV energy region, and a systematic uncertainty of approx.5%. We confirmed that 242Am/sup m/ has the largest thermal fission cross section known with a 2200 m/sec value of 6328 b. Results of a Breit-Wigner sum-of-single-levels analysis of 48 fission resonances up to 20 eV are presented and the connection of these resonance properties to the large thermal cross section is discussed. Our measurements are compared with previously reported results
Measurement of the 242Pu neutron capture cross section
Buckner, M. Q.; Wu, C. Y.; Henderson, R. A.; Bucher, B.; Bredeweg, T. A.; Baramsai, B.; Couture, A.; Jandel, M.; Mosby, S.; O'Donnell, J. M.; Ullmann, J. L.; Chyzh, A.; Dance Collaboration
2015-10-01
Precision (n,f) and (n, γ) cross sections are important for the network calculations of the radiochemical diagnostic chain for the U.S. DOE's Stockpile Stewardship Program. 242Pu(n, γ) cross section is relevant to the network calculations of Pu and Am. Additionally, new reactor concepts have catalyzed considerable interest in the measurement of improved cross sections for neutron-induced reactions on key actinides. To date, little or no experimental data has been reported on 242Pu(n, γ) for incident neutron energy below 50 keV. A new measurement of the 242Pu(n, γ) reaction was performed with the DANCE together with an improved PPAC for fission-fragment detection at LANSCE during FY14. The relative scale of the 242Pu(n, γ) cross section spans four orders of magnitude for incident neutron energies from thermal to ~ 30 keV. The absolute scale of the 242Pu(n, γ) cross section is set according to the measured 239Pu(n,f) resonance at 7.8 eV; the target was spiked with 239Pu for this measurement. The absolute 242Pu(n, γ) neutron capture cross section is ~ 30% higher than the cross section reported in ENDF for the 2.7 eV resonance. Latest results to be reported. Funded by U.S. DOE Contract No. DE-AC52-07NA27344 (LLNL) and DE-AC52-06NA25396 (LANL). U.S. DOE/NNSA Office of Defense Nuclear Nonproliferation Research and Development. Isotopes (ORNL).
2013-01-01
This Report summarizes the results of the activities in 2012 and the first half of 2013 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. This report follows the first working group report Handbook of LHC Higgs Cross Sections: 1. Inclusive Observables (CERN-2011-002) and the second working group report Handbook of LHC Higgs Cross...
Improved Actinide Neutron Capture Cross Sections Using Accelerator Mass Spectrometry
Bauder, W.; Pardo, R. C.; Kondev, F. G.; Kondrashev, S.; Nair, C.; Nusair, O.; Palchan, T.; Scott, R.; Seweryniak, D.; Vondrasek, R.; Collon, P.; Paul, M.; Youinou, G.; Salvatores, M.; Palmotti, G.; Berg, J.; Maddock, T.; Imel, G.
2014-09-01
The MANTRA (Measurement of Actinide Neutron TRAnsmutations) project will improve energy-integrated neutron capture cross section data across the actinide region. These data are incorporated into nuclear reactor models and are an important piece in understanding Generation IV reactor designs. We will infer the capture cross sections by measuring isotopic ratios from actinide samples, irradiated in the Advanced Test Reactor at INL, with Accelerator Mass Spectrometry (AMS) at ATLAS (ANL). The superior sensitivity of AMS allows us to extract multiple cross sections from a single sample. In order to analyze the large number of samples needed for MANTRA and to meet the goal of extracting multiple cross sections per sample, we have made a number of modifications to the AMS setup at ATLAS. In particular, we are developing a technique to inject solid material into the ECR with laser ablation. With laser ablation, we can better control material injection and potentially increase efficiency in the ECR, thus creating less contamination in the source and reducing cross talk. I will present work on the laser ablation system and preliminary results from our AMS measurements. The MANTRA (Measurement of Actinide Neutron TRAnsmutations) project will improve energy-integrated neutron capture cross section data across the actinide region. These data are incorporated into nuclear reactor models and are an important piece in understanding Generation IV reactor designs. We will infer the capture cross sections by measuring isotopic ratios from actinide samples, irradiated in the Advanced Test Reactor at INL, with Accelerator Mass Spectrometry (AMS) at ATLAS (ANL). The superior sensitivity of AMS allows us to extract multiple cross sections from a single sample. In order to analyze the large number of samples needed for MANTRA and to meet the goal of extracting multiple cross sections per sample, we have made a number of modifications to the AMS setup at ATLAS. In particular, we are
Randriam, Hugues
2011-01-01
Let X be an algebraic curve, defined over a perfect field, and G a divisor on X. If X has sufficiently many points, we show how to construct a divisor D on X such that l(2D-G)=0, of essentially any degree such that this is compatible the Riemann-Roch theorem. We also generalize this construction to the case of a finite number of constraints, l(k_i.D-G_i)=0, where |k_i|\\leq 2. Such a result was previously claimed by Shparlinski-Tsfasman-Vladut, in relation with the Chudnovsky-Chudnovsky method for estimating the bilinear complexity of the multiplication in finite fields based on interpolation on curves; unfortunately, as noted by Cascudo et al., their proof was flawed. So our work fixes the proof of Shparlinski-Tsfasman-Vladut and shows that their estimate m_q\\leq 2(1+1/(A(q)-1)) holds, at least when A(q)\\geq 5. We also fix a statement of Ballet that suffers from the same problem, and then we point out a few other possible applications.
EDDIX--a database of ionisation double differential cross sections.
MacGibbon, J H; Emerson, S; Liamsuwan, T; Nikjoo, H
2011-02-01
The use of Monte Carlo track structure is a choice method in biophysical modelling and calculations. To precisely model 3D and 4D tracks, the cross section for the ionisation by an incoming ion, double differential in the outgoing electron energy and angle, is required. However, the double differential cross section cannot be theoretically modelled over the full range of parameters. To address this issue, a database of all available experimental data has been constructed. Currently, the database of Experimental Double Differential Ionisation Cross sections (EDDIX) contains over 1200 digitalised experimentally measured datasets from the 1960s to present date, covering all available ion species (hydrogen to uranium) and all available target species. Double differential cross sections are also presented with the aid of an eight parameter functions fitted to the cross sections. The parameters include projectile species and charge, target nuclear charge and atomic mass, projectile atomic mass and energy, electron energy and deflection angle. It is planned to freely distribute EDDIX and make it available to the radiation research community for use in the analytical and numerical modelling of track structure. PMID:21113060
Electromagnetic Dissociation Cross Sections using Weisskopf-Ewing Theory
Adamczyk, Anne M.; Norbury, John W.
2011-01-01
It is important that accurate estimates of crew exposure to radiation are obtained for future long-term space missions. Presently, several space radiation transport codes exist to predict the radiation environment, all of which take as input particle interaction cross sections that describe the nuclear interactions between the particles and the shielding material. The space radiation transport code HZETRN uses the nuclear fragmentation model NUCFRG2 to calculate Electromagnetic Dissociation (EMD) cross sections. Currently, NUCFRG2 employs energy independent branching ratios to calculate these cross sections. Using Weisskopf-Ewing (WE) theory to calculate branching ratios, however, is more advantageous than the method currently employed in NUCFRG2. The WE theory can calculate not only neutron and proton emission, as in the energy independent branching ratio formalism used in NUCFRG2, but also deuteron, triton, helion, and alpha particle emission. These particles can contribute significantly to total exposure estimates. In this work, photonuclear cross sections are calculated using WE theory and the energy independent branching ratios used in NUCFRG2 and then compared to experimental data. It is found that the WE theory gives comparable, but mainly better agreement with data than the energy independent branching ratio. Furthermore, EMD cross sections for single neutron, proton, and alpha particle removal are calculated using WE theory and an energy independent branching ratio used in NUCFRG2 and compared to experimental data.
Experience With the SCALE Criticality Safety Cross Section Libraries
Bowman, S.M.
2000-08-21
This report provides detailed information on the SCALE criticality safety cross-section libraries. Areas covered include the origins of the libraries, the data on which they are based, how they were generated, past experience and validations, and performance comparisons with measured critical experiments and numerical benchmarks. The performance of the SCALE criticality safety cross-section libraries on various types of fissile systems are examined in detail. Most of the performance areas are demonstrated by examining the performance of the libraries vs critical experiments to show general trends and weaknesses. In areas where directly applicable critical experiments do not exist, performance is examined based on the general knowledge of the strengths and weaknesses of the cross sections. In this case, the experience in the use of the cross sections and comparisons with the results of other libraries on the same systems are relied on for establishing acceptability of application of a particular SCALE library to a particular fissile system. This report should aid in establishing when a SCALE cross-section library would be expected to perform acceptably and where there are known or suspected deficiencies that would cause the calculations to be less reliable. To determine the acceptability of a library for a particular application, the calculational bias of the library should be established by directly applicable critical experiments.
Technical study on cross section measurement with Al activation
The method of Al activation relative measurement of cross section has been studied. The cross sections of 27Al(n,α)24Na have been measured in 13.4 MeV to 14.7 MeV. The PD-300 accelerator offered D-T neutron source. The distance from sample to Tritium target is 20 cm. It spent 5 h to radiate sample with neutron. The intensity of neutron source is monitored by the α-particles from the T(d, n) 4He reaction. The induced neutron energy is determined using ratio of Nb(n,2n) and Zr(n,2n) cross section. The activated gamma ray is measured using GEM60P HPGe detector. The results of 27Al(n, α)24Na cross sections are compared with the nuclear data standard, and the deviation is less than 1%. It showed that the method of Al activation relative measurement of cross section is credible. (authors)
Penning ionization cross sections of excited rare gas atoms
Electronic energy transfer processes involving excited rare gas atoms play one of the most important roles in ionized gas phenomena. Penning ionization is one of the well known electronic energy transfer processes and has been studied extensively both experimentally and theoretically. The present paper reports the deexcitation (Penning ionization) cross sections of metastable state helium He(23S) and radiative He(21P) atoms in collision with atoms and molecules, which have recently been obtained by the authors' group by using a pulse radiolysis method. Investigation is made of the selected deexcitation cross sections of He(23S) by atoms and molecules in the thermal collisional energy region. Results indicate that the cross sections are strongly dependent on the target molecule. The deexcitation probability of He(23S) per collision increases with the excess electronic energy of He(23S) above the ionization potential of the target atom or molecule. Another investigation, made on the deexcitation of He(21P), suggests that the deexcitation cross section for He(21P) by Ar is determined mainly by the Penning ionization cross section due to a dipole-dipole interaction. Penning ionization due to the dipole-dipole interaction is also important for deexcitation of He(21P) by the target molecules examined. (N.K.)
Measurement of the high Q2 neutral current DIS cross section at HERA
This thesis presents the measurement of high Q2 neutral current deep inelastic scattering (DIS) cross sections using e+p data taken with the ZEUS detector at a centre of mass energy of √(s) ∼ 318 GeV. The analysed data was recorded in the run period 1999/2000 and corresponds to an integrated luminosity of 63 pb-1. This high statistics data set allows the most precise look at the proton structure at length scales O(1/1000) of the proton radius to date. The single (dσ/dQ2, dσ/dy(Q2 > 400 GeV2), dσ/dx(Q2 > 400 GeV2), dσ/dx(Q2 > 2500 GeV2) and dσ/dx(Q2 > 10000 GeV2)) and double differential (d2σ/dxdQ2) cross section measurements were compared with Standard Model predictions obtained with CTEQ5D parton density functions (PDFs). They are able to describe the data towards the highest values of Q2. Furthermore precise systematic studies were performed which increased the general knowledge of the ZEUS detector and led to an improved understanding of the systematic uncertainties. By also analysing the e-p data set taken in the run period 1998/1999 the different contribution of the γ-Z0-interference to e-p and e+p cross section is presented and hence the structure function xF3 was extracted. This exciting measurement which gives direct access to the valence quarks, is up to now statistically limited. More precise measurements will be possible after the HERA upgrade when more luminosity will be available. To fully profit from the higher statistics the ZEUS experiment was improved by additional devices. The new microvertex detector is introduced together with a performance study of the silicon strip detectors used in a separate chapter. (orig.)
(n,α) reactions cross sections research at IPPE
During last few years systematic studies of (n,α) reactions cross sections on a set of nuclei for wide neutron energy region was carried out in IPPE. This research was done with new spectrometer based on an ionisation chamber with Frisch grid and a wave form digitizer. Both methods for gaseous and solid targets were developed. Information extracted from digital signals allows us to significantly decrease background from parasitic reactions and reach higher reliability for obtained cross section values. The description of experiment specialities and cross section measurement results for 16O(n,α), 14N(n,α), 14N(n,t), 20Ne(n,α), 36,40Ar(n,α), 10B(n,α) and 50Cr(n,α) reactions are given in the report
Inelastic cross sections for positron scattering from atomic hydrogen
Positronium formation (Ps) cross sections for positrons impinging on atomic hydrogen were measured in the impact energy range from 13eV to 255eV at the High Intensity Positron (HIP) beam at Brookhaven National Laboratory (BNL). The Ps-formation cross section was found to rise rapidly from the threshold at 6.8eV to a maximum value of (2.98 ± 0.18) x 10-16 cm2 for ∼ 15eV positrons. By 75eV it drops below the detection limit of 0.17 x 10-16 cm2 which is the present level of statistical uncertainty. The experiment was modified to enable the measurement of doubly differential scattering cross sections
Inelastic cross sections for positron scattering from atomic hydrogen
Weber, M.; Hofmann, A.; Raith, W.; Sperber, W. [Bielefeld Univ. (Germany). Fakultaet fuer Physik; Jacobsen, F.; Lynn, K.G. [Brookhaven National Lab., Upton, NY (United States)
1994-12-31
Positronium formation (Ps) cross sections for positrons impinging on atomic hydrogen were measured in the impact energy range from 13eV to 255eV at the High Intensity Positron (HIP) beam at Brookhaven National Laboratory (BNL). The Ps-formation cross section was found to rise rapidly from the threshold at 6.8eV to a maximum value of (2.98 {plus_minus} 0.18) {times} 10{sup {minus}16} cm{sup 2} for {approx} 15eV positrons. By 75eV it drops below the detection limit of 0.17 {times} 10{sup {minus}16} cm{sup 2} which is the present level of statistical uncertainty. The experiment was modified to enable the measurement of doubly differential scattering cross sections.
Integral test of fission-product cross sections
A test of more than 50 nuclides of the fission-product file of the JEF-1 data library has been performed, using integral data measured in Dutch, French and US facilities. Some results are given for the capture cross sections of the 40 most important fission products in a fast reactor. The inelastic scattering cross sections of many even-mass nuclides are systematically too low due to neglect of direct-collective effects. In lumped fission-product cross sections the uncertainties due to the release of gaseous products have been reduced by means of a new burn-up model with parameters tuned to leakage data of irradiated PHENIX fuel pins
High Energy Measurement of the Deuteron Photodisintegration Differential Cross Section
Elaine Schulte
2002-05-01
New measurements of the high energy deuteron photodisintegration differential cross section were made at the Thomas Jefferson National Accelerator Facility in Newport News, Virginia. Two experiments were performed. Experiment E96-003 was performed in experimental Hall C. The measurements were designed to extend the highest energy differential cross section values to 5.5 GeV incident photon energy at forward angles. This builds upon previous high energy measurements in which scaling consistent with the pQCD constituent counting rules was observed at 90 degrees and 70 degrees in the center of mass. From the new measurements, a threshold for the onset of constituent counting rule scaling seems present at transverse momentum approximately 1.3 GeV/c. The second experiment, E99-008, was performed in experimental Hall A. The measurements were designed to explore the angular distribution of the differential cross section at constant energy. The measurements were made symmetric about 90 degrees
Measurement of the ZZ production cross section with ATLAS
Ellinghaus, Frank; Schmitz, Simon; Tapprogge, Stefan [Institut fuer Physik, Johannes Gutenberg-Universitaet Mainz (Germany); Collaboration: ATLAS-Collaboration
2015-07-01
The study of the ZZ production has an excellent potential to test the electroweak sector of the Standard Model, where Z boson pairs can be produced via non-resonant processes or via Higgs decays. A deviation from the Standard Model expectation for the ZZ production cross section would be an indication for new physics. This could manifest itself in so called triple gauge couplings via ZZZ or ZZγ, which the Standard Model forbids at tree level. The measurement of the ZZ production cross section is based on an integrated luminosity of 20.3 fb{sup -1} of proton-proton collision data at √(s) = 8 TeV recorded with the ATLAS detector in 2012. Measurements of differential cross sections as well as searches for triple gauge couplings have been performed. This talk presents the measurement and analysis details of the ZZ production in the ZZ → 4l channel.
Cross section versus time delay and trapping probability
Luna-Acosta, G. A.; Fernández-Marín, A. A.; Méndez-Bermúdez, J. A.; Poli, Charles
2016-07-01
We study the behavior of the s-wave partial cross section σ (k), the Wigner-Smith time delay τ (k), and the trapping probability P (k) as function of the wave number k. The s-wave central square well is used for concreteness, simplicity, and to elucidate the controversy whether it shows true resonances. It is shown that, except for very sharp structures, the resonance part of the cross section, the trapping probability, and the time delay, reach their local maxima at different values of k. We show numerically that τ (k) > 0 at its local maxima, occurring just before the resonant part of the cross section reaches its local maxima. These results are discussed in the light of the standard definition of resonance.
Measurement of charm and beauty dijet cross sections in photoproduction
A measurement of charm and beauty dijet photoproduction cross sections at the ep collider HERA is presented. The positron data of the years 1999 and 2000 are analysed, corresponding to an integrated luminosity of 56.8 pb-1. Events are selected with two or more jets of transverse momentum ptjet1(2)>11(8) GeV in the central range of pseudo-rapidity -0.9jet1(2)γobs. Taking into account the theoretical uncertainties, the charm cross sections are consistent with a QCD calculation in next-to-leading order, while the predicted cross sections for beauty production are somewhat lower than the measurement. (orig.)
Fast-neutron total and scattering cross sections of niobium
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
Majorana Dark Matter Cross Sections with Nucleons at High Energies
Jeong, Yu Seon; Reno, Mary Hall
2012-01-01
Non-relativistic dark matter scattering with nucleons is constrained by direct detection experiments. We use the XENON constraints on the spin-independent and spin-dependent cross section for dark matter scattering with nucleons to constrain a hypothetical Majorana fermionic dark matter particle's couplings to the Higgs boson and Z boson. In the procedure we illustrate the change in the dark matter nucleon cross section as one goes from non-relativistic, coherent scattering to relativistic, incoherent scattering. While the Z invisible decay width excludes directly couplings of dark matter to ordinary matter, by introducing a light Z' portal to the dark sector, a relatively large dark matter nucleon cross section can be preserved even with accelerator experiment constraints for dark matter with a mass of ~10 GeV
Ionization cross sections for low energy electron transport
Seo, Hee; Saracco, Paolo; Kim, Chan Hyeong
2011-01-01
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.
The photon scattering cross-sections of atomic hydrogen
Grunefeld, Swaantje J; Cheng, Yongjun
2016-01-01
We present a unified view of the frequency dependence of the various scattering processes involved when a neutral hydrogen atom interacts with a monochromatic, linearly-polarized photon. A computational approach is employed of the atom trapped by a finite-sized-box due to a finite basis-set expansion, which generates a set of transition matrix elements between $E0$ pseudostates. We introduce a general computational methodology that enables the computation of the frequency-dependent dipole transition polarizability with one real and two different imaginary contributions. These dipole transition polarizabilities are related to the cross-sections of one-photon photoionization, Rayleigh, Raman, and Compton scattering. Our numerical calculations reveal individual Raman scattering cross-sections above threshold that can rapidly vanish and revive. Furthermore, our numerical Compton cross-sections do not overtly suffer from the infra-red divergence problem, and are three orders-of-magnitude higher than previous analy...
63Ni (n ,γ ) cross sections measured with DANCE
Weigand, M.; Bredeweg, T. A.; Couture, A.; Göbel, K.; Heftrich, T.; Jandel, M.; Käppeler, F.; Lederer, C.; Kivel, N.; Korschinek, G.; Krtička, M.; O'Donnell, J. M.; Ostermöller, J.; Plag, R.; Reifarth, R.; Schumann, D.; Ullmann, J. L.; Wallner, A.
2015-10-01
The neutron capture cross section of the s -process branch nucleus 63Ni affects the abundances of other nuclei in its region, especially 63Cu and 64Zn. In order to determine the energy-dependent neutron capture cross section in the astrophysical energy region, an experiment at the Los Alamos National Laboratory has been performed using the calorimetric 4 π BaF2 array DANCE. The (n ,γ ) cross section of 63Ni has been determined relative to the well-known 197Au standard with uncertainties below 15%. Various 63Ni resonances have been identified based on the Q value. Furthermore, the s -process sensitivity of the new values was analyzed with the new network calculation tool NETZ.
Proton-air and proton-proton cross sections
Ulrich Ralf
2013-06-01
Full Text Available Different attempts to measure hadronic cross sections with cosmic ray data are reviewed. The major results are compared to each other and the differences in the corresponding analyses are discussed. Besides some important differences, it is crucial to see that all analyses are based on the same fundamental relation of longitudinal air shower development to the observed fluctuation of experimental observables. Furthermore, the relation of the measured proton-air to the more fundamental proton-proton cross section is discussed. The current global picture combines hadronic proton-proton cross section data from accelerator and cosmic ray measurements and indicates a good consistency with predictions of models up to the highest energies.
Aerodynamic characteristics of bodies with rectangular cross section
Knoche, H. G.; Schamel, W.; Esch, H.; Schneider, W.
Systematic wind tunnel tests for a series of missile bodies were conducted by varying cross section shape and body length in the subsonic Mach number range and up to high angles of attack. Tests with a body-wing and a body-tail configuration were performed in order to investigate the body-wing and body-tail interference for bodies of revolution and bodies with rectangular cross section. At a constant angle of attack, the boxlike body supplies far more normal force than the body of revolution with the same cross section area. The boxlike body shows strong coupling effects between the pitch, yaw and roll. The interference effect of the wing and body can be described well, in the case of boxlike bodies with wings in high or low wing positions, by the known slender body interference factors, assuming the width of the box to be the diameter of an equivalent, axially symetrical body.
Electron impact double ionization cross sections of light elements
A simple user-friendly semiempirical model is proposed to calculate electron impact double ionization cross sections of He, Li, Li+, B+, C+, C3+, O, O2+, O3+, Ne, Ne+, Ne2+, Na, Mg, Al3+, S, and Arq+ (q equals 0 - 7) targets for the incident electron energies from threshold to 106 eV. The contributions in the total double ionization cross sections from the direct double ionization and inner-shell ionization processes are taken into account on the basis of experimental data considered. The results of the present analysis are compared with the available experimental data and theoretical calculations. The model is found successful for the description of experimental cross sections. Since, this model may be a prudent selection to meet the demand level in plasma modeling due to its simple inherent structure. (authors)
Photodetachment cross-section of the negatively charged hydrogen ion
Frolov, Alexei M
2015-01-01
Photodetachment cross-section $\\sigma_{ph}(p_e)$ of the negatively charged hydrogen ion H$^{-}$ is determined with the use of highly accurate variational wave functions constructed for this ion. Photodetachment cross-sections of the H$^{-}$ ion are also studied for very small and very large values of the photo-electron momentum $p_e$. Maximum of this cross-section has been evaluated to very high accuracy and we have found that $[\\sigma_{ph}(p_e)]_{\\max} \\approx$ 3.8627035742 $\\cdot 10^{-17}$ $cm^2$ at $p_e \\approx$ 0.113206(1) $a.u.$ Photodetachment of the H$^{-}$ ion at very small and very large $p_e$ values is also considered. Our method is based upon the Rayleigh's formula for spherical Bessel functions.
Near threshold photodetachment cross section of negative atomic oxygen ions
Wu Jian-Hua(吴建华); Yuan Jian-Min(袁建民); Vo Ky Lan
2003-01-01
A 40-target state close-coupling calculation for the photodetachment cross section of negative atomic oxygen near threshold is carried out with core-valence electron correlation by using the R-matrix method. It was shown that after considering the excitations of two electrons from the 2s shell, the electron affinity of O- (2s22p5 2po) agrees with the experimental result much better than that just considering the excitations of electrons only from the 2p shell as well as only one electron from the 2s shell. Total cross section as well as the main contribution of the ionization channels to the partial cross section are illustrated to show the structure near threshold clearly.
Differences between stellar and laboratory reaction cross sections
Rauscher, T
2010-01-01
Nuclear reactions proceed differently in stellar plasmas than in the laboratory due to the thermal effects in the plasma. On one hand, a target nucleus is bombarded by projectiles distributed in energy with a distribution defined by the plasma temperature. The most relevant energies are low by nuclear physics standards and thus require an improved description of low-energy properties, such as optical potentials, required for the calculation of reaction cross sections. Recent studies of low-energy cross sections suggest the necessity of a modification of the proton optical potential. On the other hand, target nuclei are in thermal equilibrium with the plasma and this modifies their reaction cross sections. It is generally expected that this modification is larger for endothermic reactions. We show that there are many exceptions to this rule.
Total Cross Section in $\\gamma\\gamma$ Collisions at LEP
Acciarri, M; Adriani, O; Aguilar-Benítez, M; Alcaraz, J; Alemanni, G; Allaby, James V; Aloisio, A; Alviggi, M G; Ambrosi, G; Anderhub, H; Andreev, V P; Angelescu, T; Anselmo, F; Arefev, A; Azemoon, T; Aziz, T; Bagnaia, P; Bajo, A; Baksay, L; Balandras, A; Baldew, S V; Todorova-Nová, S; Banerjee, Sw; Barczyk, A; Barillère, R; Bartalini, P; Basile, M; Batalova, N; Battiston, R; Bay, A; Becattini, F; Becker, U; Behner, F; Bellucci, L; Berbeco, R; Berdugo, J; Berges, P; Bertucci, B; Betev, B L; Bhattacharya, S; Biasini, M; Biland, A; Blaising, J J; Blyth, S C; Bobbink, Gerjan J; Böhm, A; Boldizsar, L; Borgia, B; Bourilkov, D; Bourquin, Maurice; Braccini, S; Branson, J G; Brochu, F; Buffini, A; Buijs, A; Burger, J D; Burger, W J; Cai, X D; Capell, M; Cara Romeo, G; Carlino, G; Cartacci, A M; Casaus, J; Castellini, G; Cavallari, F; Cavallo, N; Cecchi, C; Cerrada, M; Cesaroni, F; Chamizo-Llatas, M; Chang, Y H; Chaturvedi, U K; Chemarin, M; Chen, A; Chen, G; Chen, G M; Chen, H F; Chen, H S; Chiefari, G; Cifarelli, Luisa; Cindolo, F; Civinini, C; Clare, I; Clare, R; Coignet, G; Colino, N; Costantini, S; Cotorobai, F; de la Cruz, B; Csilling, Akos; Cucciarelli, S; Dai, T S; van Dalen, J A; D'Alessandro, R; De Asmundis, R; Déglon, P L; Degré, A; Deiters, K; Della Volpe, D; Delmeire, E; Denes, P; De Notaristefani, F; De Salvo, A; Diemoz, M; Dierckxsens, M; Van Dierendonck, D N; Dionisi, C; Dittmar, Michael; Dominguez, A; Doria, A; Dova, M T; Duchesneau, D; Dufournaud, D; Duinker, P; El-Mamouni, H; Engler, A; Eppling, F J; Erné, F C; Ewers, A; Extermann, Pierre; Fabre, M; Falagán, M A; Falciano, S; Favara, A; Fay, J; Fedin, O; Felcini, Marta; Ferguson, T; Fesefeldt, H S; Fiandrini, E; Field, J H; Filthaut, Frank; Fisher, P H; Fisk, I; Forconi, G; Freudenreich, Klaus; Furetta, C; Galaktionov, Yu; Ganguli, S N; García-Abia, P; Gataullin, M; Gau, S S; Gentile, S; Gheordanescu, N; Giagu, S; Gong, Z F; Grenier, G; Grimm, O; Grünewald, M W; Guida, M; van Gulik, R; Gupta, V K; Gurtu, A; Gutay, L J; Haas, D; Hasan, A; Hatzifotiadou, D; Hebbeker, T; Hervé, A; Hidas, P; Hirschfelder, J; Hofer, H; Holzner, G; Hoorani, H; Hou, S R; Hu, Y; Iashvili, I; Jin, B N; Jones, L W; de Jong, P; Josa-Mutuberria, I; Khan, R A; Käfer, D; Kaur, M; Kienzle-Focacci, M N; Kim, D; Kim, J K; Kirkby, Jasper; Kiss, D; Kittel, E W; Klimentov, A; König, A C; Kopal, M; Kopp, A; Koutsenko, V F; Kräber, M H; Krämer, R W; Krenz, W; Krüger, A; Kunin, A; Ladrón de Guevara, P; Laktineh, I; Landi, G; Lebeau, M; Lebedev, A; Lebrun, P; Lecomte, P; Lecoq, P; Le Coultre, P; Lee, H J; Le Goff, J M; Leiste, R; Levchenko, P M; Li Chuan; Likhoded, S A; Lin, C H; Lin, W T; Linde, Frank L; Lista, L; Liu, Z A; Lohmann, W; Longo, E; Lü, Y S; Lübelsmeyer, K; Luci, C; Luckey, D; Lugnier, L; Luminari, L; Lustermann, W; Ma Wen Gan; Maity, M; Malgeri, L; Malinin, A; Maña, C; Mangeol, D J J; Mans, J; Marian, G; Martin, J P; Marzano, F; Mazumdar, K; McNeil, R R; Mele, S; Merola, L; Meschini, M; Metzger, W J; Von der Mey, M; Mihul, A; Milcent, H; Mirabelli, G; Mnich, J; Mohanty, G B; Moulik, T; Muanza, G S; Muijs, A J M; Musicar, B; Musy, M; Napolitano, M; Nessi-Tedaldi, F; Newman, H; Niessen, T; Nisati, A; Nowak, H; Ofierzynski, R A; Organtini, G; Oulianov, A; Palomares, C; Pandoulas, D; Paoletti, S; Paolucci, P; Paramatti, R; Park, H K; Park, I H; Passaleva, G; Patricelli, S; Paul, T; Pauluzzi, M; Paus, C; Pauss, Felicitas; Pedace, M; Pensotti, S; Perret-Gallix, D; Petersen, B; Piccolo, D; Pierella, F; Pieri, M; Piroué, P A; Pistolesi, E; Plyaskin, V; Pohl, M; Pozhidaev, V; Postema, H; Pothier, J; Prokofiev, D O; Prokofev, D; Quartieri, J; Rahal-Callot, G; Rahaman, M A; Raics, P; Raja, N; Ramelli, R; Rancoita, P G; Ranieri, R; Raspereza, A V; Raven, G; Razis, P A; Ren, D; Rescigno, M; Reucroft, S; Riemann, S; Riles, K; Rodin, J; Roe, B P; Romero, L; Rosca, A; Rosier-Lees, S; Roth, S; Rosenbleck, C; Roux, B; Rubio, Juan Antonio; Ruggiero, G; Rykaczewski, H; Saremi, S; Sarkar, S; Salicio, J; Sánchez, E; Sanders, M P; Schäfer, C; Shchegelskii, V; Schmidt-Kärst, S; Schmitz, D; Schopper, Herwig Franz; Schotanus, D J; Schwering, G; Sciacca, C; Seganti, A; Servoli, L; Shevchenko, S; Shivarov, N; Shoutko, V; Shumilov, E; Shvorob, A V; Siedenburg, T; Son, D; Smith, B; Spillantini, P; Steuer, M; Stickland, D P; Stone, A; Stoyanov, B; Strässner, A; Sudhakar, K; Sultanov, G G; Sun, L Z; Sushkov, S V; Suter, H; Swain, J D; Szillási, Z; Sztaricskai, T; Tang, X W; Tauscher, Ludwig; Taylor, L; Tellili, B; Teyssier, D; Timmermans, C; Ting, Samuel C C; Ting, S M; Tonwar, S C; Tóth, J; Tully, C; Tung, K L; Uchida, Y; Ulbricht, J; Valente, E; Vesztergombi, G; Vetlitskii, I; Vicinanza, D; Viertel, Gert M; Villa, S; Vivargent, M; Vlachos, S; Vodopyanov, I; Vogel, H; Vogt, H; Vorobev, I; Vorobyov, A A; Vorvolakos, A; Wadhwa, M; Wallraff, W; Wang, M; Wang, X L; Wang, Z M; Weber, A; Weber, M; Wienemann, P; Wilkens, H; Wu, S X; Wynhoff, S; Xia, L; Xu, Z Z; Yamamoto, J; Yang, B Z; Yang, C G; Yang, H J; Yang, M; Ye, J B; Yeh, S C; Zalite, A; Zalite, Yu; Zhang, Z P; Zhu, G Y; Zhu, R Y; Zichichi, A; Zilizi, G; Zimmermann, B; Zöller, M
2001-01-01
The reaction e+e- -> e+e- gamma* gamma* -> e+e- hadrons for quasi-real photons is studied using data from root(s) = 183 GeV up to 202 GeV. Results on the total cross sections sigma(e+e- -> e+e- hadrons) and sigma(+e- gamma* gamma* -> e+e- hadrons) are given for the two-photon centre-of-mass energies 5 GeV < Wgammagamma < 185 GeV. The total cross section of two real photons is described by a Regge parametrisation. We observe a steeper rise with the two-photon centre-of-mass energy as compared to the hadron-hadron and the photon-proton cross sections. The data are also compared to the expectations of different theoretical models.
Thermal performance of nuclear fuel rod with a Jacobian elliptic cross sectional form
Boiling water reactors, BWR, commercially use fuel rods with a circular cross section. Set the operational conditions as well as the distribution of these rods, a specific power is established. Changing this form while conserving the cross sectional area may deliver a better performance. This fact is investigated here for a family of elliptic forms, in a thermal sense, using the finite element method. Two limiting values are considered: the melting temperature of the fuel and the critical flux rate. For 2 d models, gains of the order of twenty percent in performance are estimated. It is also perceived the advantage of this alteration in other form of reactor, and discussed means of addressing other aspects of the problem. (author)
Optimization of multi-group cross sections for fast reactor analysis
The selection of the number of broad energy groups, collapsed broad energy group boundaries, and their associated evaluation into collapsed macroscopic cross sections from a general 238-group ENDF/B-VII library dramatically impacted the k eigenvalue for fast reactor analysis. An analysis was undertaken to assess the minimum number of energy groups that would preserve problem physics; this involved studies using the 3D deterministic transport parallel code PENTRAN, the 2D deterministic transport code SCALE6.1, the Monte Carlo based MCNP5 code, and the YGROUP cross section collapsing tool on a spatially discretized MOX fuel pin comprised of 21% PUO2-UO2 with sodium coolant. The various cases resulted in a few hundred pcm difference between cross section libraries that included the 238 multi-group reference, and cross sections rendered using various reaction and adjoint weighted cross sections rendered by the YGROUP tool, and a reference continuous energy MCNP case. Particular emphasis was placed on the higher energies characteristic of fission neutrons in a fast spectrum; adjoint computations were performed to determine the average per-group adjoint fission importance for the MOX fuel pin. This study concluded that at least 10 energy groups for neutron transport calculations are required to accurately predict the eigenvalue for a fast reactor system to within 250 pcm of the 238 group case. In addition, the cross section collapsing/weighting schemes within YGROUP that provided a collapsed library rendering eigenvalues closest to the reference were the contribution collapsed, reaction rate weighted scheme. A brief analysis on homogenization of the MOX fuel pin is also provided, although more work is in progress in this area. (authors)
The 233Pa fission cross-section measurement and evaluation
233Pa is a conspicuous example of strongly discrepant data in the accepted nuclear data evaluations. The precise knowledge of the neutron-induced reaction cross-section of this highly β-active nuclide (T1/2 = 27.0 d) is essential for the successful implementation of the thorium-based fuel cycle in advanced nuclear applications. The reactions involving 233Pa are responsible for the balance of nuclei as well as the average number of prompt fission neutrons in a contemplated reactor scenario. In an IAEA report, it is stated that there is a need to know the 233Pa(n, f) cross-section with an accuracy of 20%. The different evaluated neutron data libraries show, however, a difference of a factor of two for this cross-section. It has previously been deemed not feasible to measure this reaction directly due to its short half-life, high radioactivity and the in-growth of the daughter product 233U. Hence, the entries in the neutron libraries are based on theoretical predictions, which explains the large discrepancies. As reported recently the neutron-induced fission cross-section of 233Pa has been measured for the first time directly with mono-energetic neutrons from 1.0 to 3.0 MeV at the Van-de-Graaff facility of the IRMM. In the meantime, during two further measurement campaigns, the energy range has been extended up to 8.5 MeV. The experimental results will be presented together with recent model calculations of the fission cross-section applying the statistical model code STATIS, which improve the cross-section evaluation up to the second chance fission threshold. (authors)
Measurements of minor actinides cross sections for transmutation
The existing reactors produce two kinds of nuclear waste: the fission products and heavy nuclei beyond uranium called minor actinides (Americium and Curium isotopes). Two options are considered: storage in deep geological site and/or transmutation by fast neutron induced fission. These studies involve many neutron data. Unfortunately, these data bases have still many shortcomings to achieve reliable results. The aim of these measurements is to update nuclear data and complement them. We have measured the fission cross section of 243Am (7370 y) in reference to the (n,p) elastic scattering to provide new data in a range of fast neutrons (1-8 MeV). A statistical model has been developed to describe the reaction 243Am (n,f). Moreover, the cross sections from the following reactions have been be extracted from these calculations: inelastic scattering 243Am (n,n') and radiative capture 243Am (n,γ) cross sections. The direct measurements of neutron cross sections are often a challenge considering the short half-lives of minor actinides. To overcome this problem, a surrogate method using transfer reactions has been used to study few isotopes of curium. The reactions 243Am (3He, d)244Cm, 243Am (3He, t)243Cm and 243Am (3He, α)242Am allowed to measure the fission probabilities of 243,244Cm and 242Am. The fission cross sections of 242,243Cm (162,9 d, 28,5 y) and 241Am (431 y) have been obtained by multiplying these fission probabilities by the calculated compound nuclear neutron cross section relative to each channel. For each measurement, an accurate assessment of the errors was realized through variance-covariance studies. For measurements of the reaction 243Am(n,f), the analysis of error correlations allowed to interpret the scope of these measures within the existing measurements. (author)
Cross section library based discrepancies in MCNP criticality calculations
In nuclear engineering several reactor physics problems can be approached using Monte Carlo neutron transport techniques, which usually give reliable results when properly used. The quality of the results is largely determined by the accuracy of the geometry model and the statistical uncertainty of the Monte Carlo calculation. There is, however, another potential source of error, namely the cross section data used with the Monte Carlo codes. It has been shown in several studies that there may be significant discrepancies between results calculated using cross section libraries based on different evaluated nuclear data files. These discrepancies are well known to the evaluators of nuclear data but less acknowledged by reactor physicists, who often rely on a single cross section library in their calculations. In this study, discrepancies originating from base nuclear data were investigated in a systematic manner using the MCNP4C code. Calculations on simplified UOX and MOX fuelled LWR lattices were carried out using cross section libraries based on ENDF/B-VI.8, JEFF-3.0, JENDL-3.3, JEF-2.2 and JENDL-3.2 evaluated data files. The neutron spectrum of the system was varied over a wide range by changing the ratio of hydrogen to heavy metal atoms. The essential isotopes underlying the discrepancies were identified and the roles of fission and absorption cross sections of the most important nuclides assessed. The results confirm that there are large systematic differences up to a few per cent in the multiplication factors of LWR lattices. The discrepancies are strongly dependent on material compositions and neutron spectra, and largely originate from U-238 and the primary fissile isotopes. It is concluded that these discrepancies should be taken into account in all reactor physics calculations, and that reactor physicists should not rely on results based on a single cross section library. (author)
The present study deals with recent numerical results from on-going research conducted at ONERA/DMAE regarding the prediction of transonic flows, for which shock wave/boundary layer interaction is important. When this interaction is strong enough (M ≥ 1.3), shock induced oscillations (SIO) appear at the suction side of the airfoil and lead to the formation of unsteady separated areas. The main issue is then to perform unsteady computations applying appropriate turbulence modelling and relevant boundary conditions with respect to the test case. Computations were performed with the ONERA elsA software and the URANS-type approach, closure relationships being achieved from transport-equation models. Applications are provided for the OAT15A airfoil data base, well documented for unsteady CFD validation (mean and r.m.s. pressure, phase-averaged LDA data, ...). In this paper, the capabilities of turbulence models are evaluated with two 2D URANS strategies, under free-stream or confined conditions. The latter takes into account the adaptive upper and lower wind-tunnel walls. A complete 3D URANS simulation was then performed to demonstrate the real impact of all lateral wind-tunnel walls on such a flow
Revised transport cross-sections for the WIMS library
WIMS transport cross-sections above 4 eV are formed by a column-sum correction in which an assumed current spectrum is used to weight the P1 scattering data for a given isotope. Revised weighting spectra lead to improved transport cross-sections for the principal moderators: the effect on calculations of k-infinity is small but leakage calculations, for the homogenised cell, are now in close agreement with corresponding B1 calculations using explicit P1 data. Energy condensation of the B0 (transport corrected) equations appears to be more valid than the procedure used to condense the B1 equations. (author)
Kriging approach for the experimental cross-section covariances estimation
In the classical use of a generalized χ2 to determine the evaluated cross section uncertainty, we need the covariance matrix of the experimental cross sections. The usual propagation error method to estimate the covariances is hardly usable and the lack of data prevents from using the direct empirical estimator. We propose in this paper to apply the kriging method which allows to estimate the covariances via the distances between the points and with some assumptions on the covariance matrix structure. All the results are illustrated with the 2555Mn nucleus measurements. (authors)
Testing weak cross-sectional dependence in large panels
Pesaran, Hashem
2012-01-01
This paper considers testing the hypothesis that errors in a panel data model are weakly cross sectionally dependent, using the exponent of cross-sectional dependence , introduced recently in Bailey, Kapetanios and Pesaran (2012). It is shown that the implicit null of the CD test depends on the relative expansion rates of N and T. When T = O , for some , then the implicit null of the CD test is given by , which gives , when N and T tend to infinity at the same rate such that T/N , with being...
High-mass dijet cross sections in photoproduction at HERA
Abe, T; Adamczyk, L; Adamus, M; Aghuzumtsyan, G; Ahn, S H; Antonioli, P; Antonov, A; Arneodo, M; Bailey, D S; Bamberger, A; Barakbaev, A N; Barbagli, G; Barbi, M; Bari, G; Barreiro, F; Bartsch, D; Bashkirov, V; Basile, M; Bauerdick, L A T; Bednarek, B; Behrens, U; Bell, M; Bellagamba, L; Benen, A; Bertolin, A; Bhadra, S; Bodmann, B; Bokel, C; Boogert, S; Boos, E G; Borras, K; Boscherini, D; Breitweg, J; Brock, I; Brook, N H; Brugnera, R; Brümmer, N; Bruni, A; Bruni, G; Bussey, P J; Butterworth, J M; Bylsma, B; Caldwell, A; Capua, M; Cara Romeo, G; Carli, T; Carlin, R; Cartiglia, N; Catterall, C D; Chapin, D; Chekanov, S; Chiochia, V; Chwastowski, J; Ciborowski, J; Ciesielski, R; Cifarelli, Luisa; Cindolo, F; Cirio, R; Cloth, P; Coldewey, C; Cole, J E; Collins-Tooth, C; Contin, A; Cooper-Sarkar, A M; Coppola, N; Cormack, C; Corradi, M; Corriveau, F; Costa, M; Crittenden, J; Cross, R; D'Agostini, Giulio; Dagan, S; Dal Corso, F; Danilov, P; Dannheim, D; De Pasquale, S; Dementiev, R K; Derrick, M; Deshpande, Abhay A; Desler, K; Devenish, R C E; Dhawan, S; Dolgoshein, B A; Doyle, A T; Drews, G; Durkin, L S; Dusini, S; Eisenberg, Y; Engelen, J; Ermolov, P F; Eskreys, Andrzej; Ferrando, J; Ferrero, M I; Figiel, J; Filges, D; Foster, B; Foudas, C; Fourletov, S; Fourletova, J; Fox-Murphy, A; Fricke, U; Fusayasu, T; Gabareen, A; Galea, R; Gallo, E; García, G; Garfagnini, A; Geiser, A; Genta, C; Gialas, I; Gilmore, J; Ginsburg, C M; Giusti, P; Gladilin, L K; Gladkov, D; Glasman, C; Göbel, F; Goers, S; Golubkov, Yu A; Goncalo, R; González, O; Göttlicher, P; Grabowska-Bold, I; Graciani, R; Grijpink, S; Grzelak, G; Gwenlan, C; Haas, T; Hain, W; Hall-Wilton, R; Hamatsu, R; Hanlon, S; Hart, J C; Hartmann, H; Hartner, G F; Hayes, M E; Heaphy, E A; Heath, G P; Heath, H F; Helbich, M; Heusch, C A; Hilger, E; Hillert, S; Hirose, T; Hochman, D; Holm, U; Hughes, V W; Iacobucci, G; Iga, Y; Inuzuka, M; Irrgang, P; Jakob, H P; Jelen, K; Jeoung, H Y; Jones, T W; Kananov, S; Kappes, A; Karshon, U; Katkov, I I; Katz, U F; Kcira, D; Kerger, R; Khein, L A; Kim, C L; Kim, J Y; Kind, O; Kisielewska, D; Kitamura, S; Klimek, K; Koffeman, E; Kohno, T; Kooijman, P; Koop, T; Korotkova, N A; Korzhavina, I A; Kotanski, A; Kötz, U; Kowal, A M; Kowal, M; Kowalski, H; Kowalski, T; Krakauer, D A; Kreisel, A; Kuze, M; Kuzmin, V A; Labarga, L; Labes, H; Lammers, S; Lane, J B; Lee, J H; Lee, S B; Lee, S W; Lelas, D; Levchenko, B B; Levi, G; Levman, G M; Levy, A; Lightwood, M S; Lim, H; Lim, I T; Limentani, S; Ling, T Y; Liu, X; Löhr, B; Lohrmann, E; Long, K R; Longhin, A; Lopez-Duran Viani, A; Lukina, O Yu; Lupi, A; Ma, K J; Maddox, E; Magill, S; Mankel, R; Margotti, A; Marini, G; Markun, P; Martens, J; Martin, J F; Martínez, M; Maselli, S; Massam, Thomas; Mastroberardino, A; Matsushita, T; Matsuzawa, K; Mattingly, M C K; McCubbin, N A; Mellado, B; Menary, S R; Metlica, F; Meyer, A; Milite, M; Miller, D B; Mindur, B; Mirea, A; Monaco, V; Moritz, M; Musgrave, B; Nagano, K; Nania, R; Nigro, A; Nishimura, T; Notz, D; Nowak, R J; Ochs, A; Oh, B Y; Olkiewicz, K; Pac, M Y; Padhi, S; Paganis, S; Palmonari, F; Parenti, A; Park, I H; Park, S K; Paul, E; Pavel, N; Pawlak, J M; Pelfer, P G; Pellegrino, A; Peroni, C; Pesci, A; Petrucci, M C; Plucinsky, P P; Pokrovskiy, N S; Polini, A; Posocco, M; Proskuryakov, A S; Przybycien, M B; Raach, H; Rautenberg, J; Redondo, I; Reeder, D D; Renner, R; Repond, J; Rigby, M; Robins, S; Rodrigues, E; Rulikowska-Zarebska, E; Ruske, O; Ruspa, M; Sabetfakhri, A; Sacchi, R; Salehi, H; Sar, G; Saull, P R B; Savin, A A; Saxon, D H; Schagen, S; Schioppa, M; Schlenstedt, S; Schmidke, W B; Schneekloth, U; Schnurbusch, H; Sciulli, F; Scott, J; Selonke, F; Shche, L M; Skillicorn, I O; Slominski, W; Smalska, B; Smith, W H; Soares, M; Solano, A; Solomin, A N; Son, D; Sosnovtsev, V V; Saint-Laurent, M G; Staiano, A; Stairs, D G; Stanco, L; Standage, J; Stifutkin, A; Stonjek, S; Stopa, P; Straub, P B; Suchkov, S; Surrow, B; Susinno, G; Suszycki, L; Sutton, M R; Sztuk, J; Szuba, D; Szuba, J; Tandler, J; Tapper, A D; Tapper, R J; Tassi, E; Terron, J; Tiecke, H G; Tokushuku, K; Tsurugai, T; Tuning, N; Turcato, M; Tymieniecka, T; Ukleja, A; Ukleja, J; Umemori, K; Vázquez, M; Velthuis, J J; Vlasov, N N; Voss, K C; Walczak, R; Walker, R; Weber, A; Wessoleck, H; West, B J; Whitmore, J J; Wichmann, R; Wick, K; Wiggers, L; Wing, M; Wolf, G; Wölfle, S; Yamada, S; Yamashita, T; Yamazaki, Y; Yoshida, R; Youngman, C; Za, L; Zakrzewski, J A; Zeuner, W; Zhautykov, B O; Zichichi, A; Ziegler, A; Zotkin, S A; De Wolf, E; Del Peso, J
2002-01-01
Dijet differential cross sections for the reaction e+p -> e+ + jet + jet + X in the photoproduction regime have been measured with the ZEUS detector at HERA using an integrated luminosity of 42.7 pb**{-1}. The cross sections are given for photon-proton centre-of-mass energies in the range 134 e+ Z0 X} < 5.9 pb. Upper limits on the photoproduction of new heavy resonances decaying into two jets are also presented for masses in the range between 60 GeV and 155 GeV.
Controlling inclusive cross sections in parton shower + matrix element merging
Plaetzer, Simon
2012-11-15
We propose an extension of matrix element plus parton shower merging at tree level to preserve inclusive cross sections obtained from the merged and showered sample. Implementing this constraint generates approximate next-to-leading order (NLO) contributions similar to the LoopSim approach. We then show how full NLO, or in principle even higher order, corrections can be added consistently, including constraints on inclusive cross sections to account for yet missing parton shower accuracy at higher logarithmic order. We also show how NLO accuracy below the merging scale can be obtained.
Inactivation cross section of yeast cells irradiated by heavy ions
无
1999-01-01
Inactivation cross sections for haploid yeast cell strain211a have been calculated as 1-hit detector based on the tracktheory in an extended target mode and a numerical calculation ofradial dose distribution. In the calculations, characteristic dose D0 is a fitted parameter which is obtained to be 42 Gy, and "radius"of hypothetical target a0 is chosen to be 0.5μm which is about the sizeof nucleus of yeast cells for obtaining an overall agreement withexperimental cross sections. The results of the calculations are inagreement with the experimental data in high LET (linear energy transfer) including the thindown region.
Modelling of reaction cross sections and prompt neutron emission
Oberstedt S.
2010-10-01
Full Text Available Accurate nuclear data concerning reaction cross sections and the emission of prompt fission neutrons (i.e. multiplicity and spectra as well as other fission fragment data are of great importance for reactor physics design, especially for the new Generation IV nuclear energy systems. During the past years for several actinides (238U(n, f and 237Np(n, f both the reaction cross sections and prompt neutron multiplicities and spectra have been calculated within the frame of the EFNUDAT project.
SU-E-I-43: Photoelectric Cross Section Revisited
Purpose: The importance of the precision in photoelectric cross-section value increases for recent developed technology such as dual energy computed tomography, in which some reconstruction algorithms require the energy dependence of the photo-absorption in each material composition of human being. In this study, we revisited the photoelectric cross-section calculation by self-consistent relativistic Hartree-Fock (HF) atomic model and compared with that widely distributed as “XCOM database” in National Institute of Standards and Technology, which was evaluated with localdensity approximation for electron-exchange (Fock)z potential. Methods: The photoelectric cross section can be calculated with the electron wave functions in initial atomic state (bound electron) and final continuum state (photoelectron). These electron states were constructed based on the selfconsistent HF calculation, where the repulsive Coulomb potential from the electron charge distribution (Hartree term) and the electron exchange potential with full electromagnetic interaction (Fock term) were included for the electron-electron interaction. The photoelectric cross sections were evaluated for He (Z=2), Be (Z=4), C (Z=6), O (Z=8), and Ne (Z=10) in energy range of 10keV to 1MeV. The Result was compared with XCOM database. Results: The difference of the photoelectric cross section between the present calculation and XCOM database was 8% at a maximum (in 10keV for Be). The agreement tends to be better as the atomic number increases. The contribution from each atomic shell has a considerable discrepancy with XCOM database except for K-shell. However, because the photoelectric cross section arising from K-shell is dominant, the net photoelectric cross section was almost insensitive to the different handling in Fock potential. Conclusion: The photoelectric cross-section program has been developed based on the fully self-consistent relativistic HF atomic model. Due to small effect on the Fock
Reaction cross sections of hypernuclei and the shrinkage effect
Akaishi, T
2013-01-01
We calculate the reaction cross sections for $^6{\\rm Li}$ and $^7_{\\Lambda}{\\rm Li}$ on a $^{12}{\\rm C}$ target at $100\\,{\\rm MeV/nucleon}$ using the Glauber theory. To this end, we assume a two-body cluster structure for $^6$Li and $^7_{\\Lambda}{\\rm Li}$, and employ the few-body treatment of the Glauber theory, that is beyond the well known optical limit approximation. We show that the reaction cross section for $^7_{\\Lambda}{\\rm Li}$ is smaller than that for $^6$Li by about 4\\%, reflecting the shrinkage effect of the $\\Lambda$ particle.
Charged particle cross-section data and their systematization
The reaction cross-sections and the thick target yields of (α,αxn) and (α,xn), induced by the alpha particles from the Buenos Aires 60 inch synchrocyclotron for Cu, Y, Zr, Rh, Te, Ta, Au and Pb were obtained. The ''stocked foil'' method was applied. The ''nuclear spin density'' parameter was determined using a phenomenological approximation from the cross section data for 181Ta(α,n) reaction producing isomeric pairs of sup(184m)Re and sup(184g)Re. The systematic behaviour of the present result and the results of other authors were demonstrated
Electron transport in silicon nanowires having different cross-sections
Muscato Orazio
2016-06-01
Full Text Available Transport phenomena in silicon nanowires with different cross-section are investigated using an Extended Hydrodynamic model, coupled to the Schrödinger-Poisson system. The model has been formulated by closing the moment system derived from the Boltzmann equation on the basis of the maximum entropy principle of Extended Thermodynamics, obtaining explicit closure relations for the high-order fluxes and the production terms. Scattering of electrons with acoustic and non polar optical phonons have been taken into account. The bulk mobility is evaluated for square and equilateral triangle cross-sections of the wire.
Update to the R33 cross section file format
In September 1991, in response to the workshop on cross sections for Ion Beam Analysis (IBA) held in Namur (July 1991, Nuclear Instruments and Methods B66(1992)), a simple ascii format was proposed to facilitate transfer and collation of nuclear reaction cross section data for Ion Beam Analysis (IBA) and especially for Nuclear Reaction Analysis (NRA). Although intended only as a discussion document, the ascii format - referred to as the R33 (Report 33) format - has become a de facto standard. In the decade since this first proposal there have been spectacular advances in computing power and in software usability, however the cross-platform compatibility of the ascii character set has ensured that the need for an ascii format remains. Nuclear reaction cross section data for Nuclear Reaction analysis has been collected and archived on internet web sites over the last decade. This data has largely been entered in the R33 format, although there is a series of elastic cross sections that are expressed as the ratio to the corresponding Rutherford cross sections that have been entered in a format referred to as RTR (ratio to Rutherford). During this time the R33 format has been modified and added to - firstly to take into account angular distributions, which were not catered for in the first proposal, and more recently to cater for elastic cross sections expressed as the ratio-to- Rutherford, which it is useful to have for some elastic scattering programs. It is thus timely to formally update the R33 format. There also exists the large nuclear cross section data collections of the Nuclear Data Network - of which the core centres are the OECD NEA Nuclear Data Bank, the IAEA Nuclear Data Section, the Brookhaven National Laboratory National Nuclear Data Centre and CJD IPPE Obninsk, Russia. The R33 format is now proposed to become a legal computational format for the NDN. It is thus also necessary to provide an updated formal definition of the R33 format in order to provide
Photon gluon fusion cross sections at HERA energy
Engelen, J. J.; Dejong, S. J.; Poletiek, M.; Vermaseren, J. A. M.
1988-01-01
Cross sections for heavy flavor production through photon gluon fusion in electron proton collisions are presented. The electron photon vertex is taken into account explicitly, and the Q sq of the exchanged photon ranges from nearly zero (almost real photon) to the kinematically allowed maximum. The QCD scale is set by the mass of the produced quarks. The formalism is also applicable to the production of light quarks as long as the invariant mass of the pair is sufficiently high, so cross sections for u anti-u, d anti-d, and s anti-s production are also given.
Total cross section of electron scattering by fluorocarbon molecules
Yamada, T [Department of Electrical Engineering and Electronics, Daido Institute of Technology, 10-3 Takiharu-cho, Minami-ku, Nagoya 457-8530 (Japan); Ushiroda, S [Department of Electrical Engineering and Electronics, Toyota College of Technology, 2-1 Eisei-cho, Toyota-Shi 471-8525 (Japan); Kondo, Y [Kaela Research and Development Corporation, Incubation Office No 2 in Nagoya Institute of Technology, Gokiso-cho, Shouwa-ku, Nagoya 466-8555 (Japan)
2008-12-14
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 (CCl{sub 2}F{sub 2}), hydrochlorofluorocarbon (CHClF{sub 2}), perfluoropropane (C{sub 3}F{sub 8}), perfluoro-n-pentane (C{sub 5}F{sub 12}), perfluoro-n-hexane (C{sub 6}F{sub 14}) and perfluoro-n-octane (C{sub 8}F{sub 18}) were obtained experimentally and compared with the values obtained from a theoretical calculation and semi-empirical model calculation.
Evaluation of neutron resonance cross section data at GELINA
BECKER BJÖRN; Capote, R; EMILIANI FEDERICA; Guber, K. H.; HEYSE JAN; KAUWENBERGHS KIM JOSEPHA; Kopecky, Stefan; LAMPOUDIS CHRISTOS; Massimi, C.; MONDELAERS Willy; Moxon, M.; Noguere, G.; Plompen, Arjan; PRONAYEV V.; SIEGLER Peter
2013-01-01
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 resonanc...
Fast-neutron scattering cross sections of elemental zirconium
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
Evaluation of the 238U neutron total cross section
Experimental energy-averaged neutron total cross sections of 238U were evaluated from 0.044 to 20.0 MeV using regorous numerical methods. The evaluated results are presented together with the associated uncertainties and correlation matrix. They indicate that this energy-averaged neutron total cross section is known to better than 1% over wide energy regions. There are somwewhat larger uncertainties at low energies (e.g., less than or equal to 0.2 MeV), near 8 MeV and above 15 MeV. The present evaluation is compard with values given in ENDF/B-V
Top quark pair cross section measurements in CMS
Brochero Cifuentes, Javier Andres
2016-01-01
This document presents the latest results in the measurement of the top-quark pair production cross section obtained with data collected by the CMS detector at LHC accelerator. The analyses are performed in the dilepton, single lepton and full hadronic decay modes. Additionally to the inclusive measurements of $\\mathrm{\\sigma_{\\mathrm{t\\bar{t}}}}$ at 7, 8 and 13$\\mathrm{\\;TeV}$, the CMS collaboration provides for the first time the cross section at 5.02$\\mathrm{\\;TeV}$. Results are confronted with the latest and most precise theoretical calculations.
Cross Section and Experimental Data Analysis Using EViews
Agung, I Gusti Ngurah
2011-01-01
A practical guide to selecting and applying the most appropriate model for analysis of cross section data using EViews. " This book is a reflection of the vast experience and knowledge of the author. It is a useful reference for students and practitioners dealing with cross sectional data analysis ... The strength of the book lies in its wealth of material and well structured guidelines ..." Prof. Yohanes Eko Riyanto , Nanyang Technological University, Singapore. " This is superb and brilliant. Prof. Agung has skilfully transformed his best experiences into new knowledge ... creating a new way
Total photoproduction cross section at very high energy
In this paper we apply to the photoproduction total cross section a model we have proposed for purely hadronic processes and which is based on QCD mini-jets and soft gluon re-summation. We compare the predictions of our model with the HERA data as well as with other models. For cosmic rays, our model predicts substantially higher cross sections at TeV energies than models based on factorization, but lower than models based on mini-jets alone, without soft gluons. We discuss the origin of this difference. (orig.)
Precision measurement of cross sections by isomer ratio method
A possibility of determining the cross sections of isomer states measuring the ratio of yields of ground and isomer states (or σm/σg cross section ratio) by γ spectroscopy methods is investigated. Isomer ratio (IR) for 185Re(γ, n)184mgRe, 181Ta(α, n)184mgRe, 82Se(γ, n)81mSe and 39K(γ, n)38mgK reactions are studied. The IR determination error makes up several per cents. 6 refs.; 4 figs.; 1 tab
The absolute threshold photodetachment cross-section of Al-
The total absolute photodetachment cross-section of the aluminum anion, Al-, is calculated in the threshold spectral region for photons of wave numbers 3400 - 3650cm-1 using the zero-core contribution (ZCC) model. A computer least-squares curve fit is used to test the validity of the Wigner threshold law and the deviation from recent experimental measurements of the relative photodetachment cross-section. It is found that the best agreements is achieved with a smaller core radius rο=1.60 Angstrom rather than the value of 1.82 Angstrom used earlier. (authors). 22 refs., 5 figs., 1 tab
Photon-photon cross sections in the resonance region
Possible contributions to the photon-photon cross section in the region where the vector dominated thresholds are closed are evaluated. All two body processes diagonal and off diagonal are summed explicitly and the multibody processes are calculated by a method introduced previously. It is found that, excluding s-channel resonances, the cross section is very small for all channels, and purely real except for resonances. It is concluded that the possibility of studying s-channel resonances in electron colliding machines is probably far better than it was believed. These possibilities are discussed in a separate paper. (author)
Neutrino absorption cross sections in 16O and 40Ar
Recently the study of total cross sections in the neutrino (antineutrino) - nucleus reactions has been done for the lepton detection particularly for the nuclear targets used in various ongoing atmospheric neutrino experiments at IMB, Superkamiokande, and ICARUS. The inclusive cross sections have been studied for these reactions using local density approximations (LDA) for the neutrinos moving in the nuclear medium and taking into account the renormalization of weak coupling constants due to the presence of strongly interacting nucleons in the nuclear medium and compared with the calculations done in Fermi gas model (FGM)
Medium effects in the nucleon- nucleus reaction cross-section
The nucleon-nucleus reaction cross-section, σR , has been calculated using Gabblers multiple scattering theory in its optical limit, A medium modified nuclear phase shift function has been obtained for nucleon-nucleus scattering using a medium two body scattering amplitude. In the present calculations, the Coulomb modified Glauber model is used. Also different forms of Gaussian density distribution, for the target nucleus, are used. A comparison of medium modified calculations with the corresponding experimental data has shown that application of the medium effect in the total reaction cross- section plays an important role for low values of energy
Inactivation cross section of yeast cells irradiation by heavy ions
Inactivation cross sections for haploid yeast cell strain 211a have been calculated as 1-hit detector based on the track theory in an extended target mode and a numerical calculation of radial dose distribution. In the calculations, characteristic dose D0 is a fitted parameter which is obtained to be 42 Gy, and 'radius' of hypothetical target a0 is chosen to be 0.5 μm which is about the size of nucleus of yeast cells for obtaining an overall agreement with experimental cross sections. The results of the calculations are in agreement with the experimental data in high LET (linear energy transfer) including the thin down region
Total cross section of electron scattering by fluorocarbon molecules
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.
Activities of the JILA Atomic Collisions Cross Sections Data Center
The JILA Atomic Collisions Cross Sections Data Center compiles, critically evaluates, and reviews cross sections and rates for low energy (<100 keV) collisions of electrons, photons, and heavy particles with atoms, ions, and simple molecules. Reports are prepared which provide easily accessible recommended data with error limits, list the fundamental literature related to specific topics, identify regions where data are missing, and point out inconsistencies in existing data. The general methodology used in producing evaluated compilations is described. Recently completed projects and work in progress are reported
Approximate formulas for total cross section for moderately small eikonal
Kisselev, A V
2016-01-01
The eikonal representation for the total cross section is considered. The approximate formulas for a moderately small eikonal are derived. In contrast to the standard eikonal integrals, they contain no Bessel functions, and, hence, no rapidly oscillating integrands. The formulas obtained are applied to numerical evaluations of the total cross section for a number of particular expressions for the eikonal. It is shown that for pure imaginary eikonals the relative error of O(10^(-5)) can be achieved. Also two improper triple integrals are analytically calculated.
International evaluation cooperation Subgroup 7: Multigroup cross section processing
Roussin, R.W.; White, J.E. (Oak Ridge National Lab., TN (USA)); Sartori, E. (NEA Data Bank, 91 - Gif-sur-Yvette (France)); Panini, G. (ENEA, Bologna (Italy)); MacFarlane, R. (Los Alamos National Lab., NM (USA)); Muir, D. (International Atomic Energy Agency, Vienna (Austria). Nuclear Data Section); Mattes, M. (Stuttgart Univ. (Germany, F.R.). Inst. fuer Kernenergetik und Energiesysteme); Hasegawa, I
1991-01-01
The chairmen of the ENDF/B, JEF, EFF, and JENDL evaluated data files adopted a proposal to develop a fine-group processed cross section library based on the VITAMIN'' concept. The authors listed above, with support from others, are participating in this project. The end result will be a pseudo-problem-independent fine-group cross section library generated from the latest evaluated data in ENDF/B-VI, JEF-2, EFF-2, and JENDL-3. Initial applications of the library will be for shielding, fast reactor physics, and fusion neutronics. Progress made to date will be discussed. 8 refs.
Cross section model and scattering law of liquid water for design of a cold neutron source
A cross section model for cold neutron scattering in light water is developed, which describes various molecular motions inherent to hydrogen-bonded water molecules especially in terms of jump- and rotational-diffusion processes. Inter- and intra-molecular vibrations are also included. A systematic analysis is performed of a velocity autocorrelation function, a generalized frequency distribution and double-differential and total cross sections. Good agreement with the results of computer molecular dynamics and neutron scattering experiments is found. A wide range of cross section evaluation for neutron energies from 0.1 μeV to 10 eV and liquid temperatures between the melting and boiling points is performed. This permits us to generate such low-energy neutron cross section libraries as group constants set and scattering law for ultra-cold, very-cold, cold and thermal neutrons. Together with the libraries for liquid 4He, H2, D2 and solid and liquid CH4, a powerful tool for design of an advanced low-energy neutron source is now ready for use. (author)
High resolution measurements of the Am241(n,2n) reaction cross section
Sage, C.; Semkova, V.; Bouland, O.; Dessagne, P.; Fernandez, A.; Gunsing, F.; Nästren, C.; Noguère, G.; Ottmar, H.; Plompen, A. J. M.; Romain, P.; Rudolf, G.; Somers, J.; Wastin, F.
2010-06-01
Measurements of the Am241(n,2n) reaction cross section have been performed at the Joint Research Centre (JRC) Geel in the frame of a collaboration between the European Commission (EC) JRC and French laboratories from CNRS and the Commissariat à L’Energie Atomique (CEA) Cadarache. Raw material coming from the Atalante facility of CEA Marcoule has been transformed by JRC Karlsruhe into suitable Am241O2 samples embedded in Al2O3 matrices specifically designed for these measurements. The irradiations were carried out at the 7-MV Van de Graaff accelerator. The Am241(n,2n) reaction cross section was determined relative to the Al27(n,α)Na24 standard cross section. The measurements were performed in four sessions, using quasi-mono-energetic neutrons with energies ranging from 8 to 21 MeV produced via the H2(d,n)He3 and the H3(d,n)He4 reactions. The induced activity was measured by standard γ-ray spectrometry using a high-purity germanium detector. Below 15 MeV, the present results are in agreement with data obtained earlier. Above 15 MeV, these measurements allowed the experimental investigation of the Am241(n,2n) reaction cross section for the first time. The present data are in good agreement with predictions obtained with the talys code that uses an optical and fission model developed at CEA.
Chan, Kenneth H.; Chan, Andrew C.; Fried, William A.; Simon, Jacob C.; Darling, Cynthia L.; Fried, Daniel
2013-01-01
Several studies have demonstrated the potential of cross-polarization optical coherence tomography (CP-OCT) to quantify the severity of early caries lesions (tooth decay) on tooth surfaces. The purpose of this study is to show that 2D images of the lesion depth and the integrated reflectivity can be used to accurately represent the severity of early lesions. Simulated early lesions of varying severity were produced on tooth samples using simulated lesion models. Methods were developed to conv...
Ute Weckmann; A. Jung; T. Branch; Oliver Ritter
2007-01-01
Two of the Earth´s largest geophysical anomalies, the Beattie Magnetic Anomaly (BMA) and the Southern Cape Conductive Belt (SCCB) extend across the southern African continent for more than 1000 km in an east-west direction. Based on previous electrical and magnetometer array measurements it is believed that both anomalies have a common crustal source with a width of 50 km represented by serpentinized palaeo-oceanic srust. New two-dimensional (2D) electrical conductivity models along a profile...
Measurement of high-Q2 charged current cross sections in e+p deep inelastic scattering at HERA
Cross sections for charged current deep inelastic scattering have been measured in e+p collisions at a center-of-mass energy of 318 GeV. The data collected with the ZEUS detector at HERA in the running periods 1999 and 2000 correspond to an integrated luminosity of 61 pb-1. Single differential cross sections dσ/dQ2, dσ/dx and dσ/dy have been measured for Q2>200 GeV2, as well as the double differential reduced cross section d2σ/dxdQ2 in the kinematic range 280 GeV222 and 0.008 -p charged current deep inelastic scattering cross sections. The helicity structure is investigated in particular. The mass of the space-like W boson propagator has been determined from a fit to dσ/dQ2. (orig.)
Displacement cross sections and PKA spectra: tables and applications
Damage energy cross sections to 20 MeV are given for aluminum, vanadium, chromium, iron, nickel, copper, zirconium, niobium, molybdenum, tantalum, tungsten, lead, and 18Cr10Ni stainless steel. They are based on ENDF/B-IV nuclear data and the Lindhard energy partition model. Primary knockon atom (PKA) spectra are given for aluminum, iron, niobium, tantalum, and lead for neutron energies up to 15 MeV at approximately one-quarter lethargy intervals. The contributions of various reactions to both the displacement cross sections (taken to be proportional to the damage energy cross sections) and the PKA spectra are presented graphically. Spectral-averaged values of the displacement cross sections are given for several spectra, including approximate maps for the Experimental Breeder Reactor-II (EBR-II) and several positions in the Fast Test Reactor (FTR). Flux values are included to permit estimation of displacement rates. Graphs show integral PKA spectra for the five metals listed above for neutron spectra corresponding to locations in the EBR-II, the High Flux Isotope Reactor (HFIR), and a conceptual fusion reactor (UWMAK-I). Detailed calculations are given only for cases not previously documented. Uncertainty estimates are included
Mid-infrared absorption cross sections for acetone (propanone)
Infrared absorption cross sections for acetone (propanone) have been determined in the 830-1950 cm-1 spectral region from spectra recorded using a high-resolution FTIR spectrometer (Bruker IFS 125HR) and a multipass cell with a maximum optical path length of 19.3 m. The spectra of mixtures of acetone with dry synthetic air were recorded at 0.015 cm-1 resolution (calculated as 0.9/MOPD using the Bruker definition of resolution) at a number of temperatures between 194 and 251 K and pressures appropriate for atmospheric conditions. Intensities were calibrated using three acetone spectra (recorded at 278, 293 and 323 K) taken from the Pacific Northwest National Laboratory (PNNL) IR database. The new absorption cross sections have been combined with previous high spectral resolution results to create a more complete set of acetone absorption cross sections appropriate for atmospheric remote sensing. These cross sections will provide an accurate basis for upper tropospheric/lower stratospheric retrievals of acetone in the mid-infrared spectral region from ACE and MIPAS satellite data.
Neutron cross sections at 14 MeV
Neutron activation cross sections on Nd isotopes at 14 MeV were measured using the Ge(Li) gamma-ray spectroscopy. The nonlinear least square method was used for resolving the gamma spectra. The results obtained are discussed in detail and compared with theoretical results on other isotopes
Cross-sectional investigation of HEMS activities in Europe
Di Bartolomeo, Stefano; Gava, Paolo; Truhlář, Anatolij;
2014-01-01
OBJECTIVES: To gather information on helicopter emergency medical services (HEMSs) activities across Europe. METHODS: Cross-sectional data-collection on daily (15 November 2013) activities of a sample of European HEMSs. A web-based questionnaire with both open and closed questions was used, devel...
Elemental composition of paint cross sections by nuclear microprobe analysis
Physico-chemical characterization of pigments used in artistic painting give precious indications on age of paintings and sometimes on geographical origin of ores. After recalling the principle of protons microprobe, first results obtained by microanalysis of painting cross sections for non destructive microanalysis of impurities in white lead are given
Longitudinal cross section and asymmetries for jets in leptoproduction
We have calculated the longitudinal and other polarization dependent cross sections for jet production in deep inelastic electron-proton scattering up to order αs of the quark-gluon coupling constant and compared them with estimates of the non-perturbative contributions. (orig.)
State-selective radiative recombination cross sections of argon ions
The n-, (n,l)- and fine-structure level state-selective radiative recombinations (RR) cross sections of argon ions Ar18+,Ar13+,Ar7+ and Ar+ are obtained with the semi-classical Kramer formula, the relativistic self-consistent field (RSCF) method and the relativistic configuration interaction (RCI) method. It is found that for the highly charged ions with few electrons, the cross sections calculated with these three methods are in good agreement with each other. But as the number of electrons increases, the Kramer formula deviates from the RSCF and RCI results. For instance, when the energy of the incident electron is larger than 100 eV, the n-state selective cross sections of Ar7+ calculated from the Kramer formula are underestimated for more than 50%. The RSCF results are in general agreement with the RCI results. However, for the low charged ions, a clear distinction appears due to the strong configuration interaction, especially near the Cooper minimum. The n-resolved (n≤10) and total Maxwellian averaged rate coefficients are calculated, and the analytic fitting parameters are also provided. -- Highlights: ► The RR cross sections of Ar18+, Ar13+, Ar7+ and Ar+ are obtained. ► The Kramer formula, the relativistic self-consistent field and RCI methods are used. ► Results from three methods are compared with each other.
Measurement of antiproton-proton cross sections at low momenta
The present thesis describes an experiment which serves for the study of the antiproton-proton interaction at laboratory momenta between 150 MeV/c and 600 MeV/c. The arrangement permits the measurement of differential cross sections of the elastic scattering and the charge-exchange reaction as well as the cross section of the annihilation into charged and neutral pions. By the availability of an intense beam with low momentum uncertainty from the LEAR storage ring for low energy antiprotons at CERN a clear improvement of the measurement accuracy compared to earlier experiments at separated antiproton beams can be reached. A prototype of the antineutron calorimeter used for the measurement of the angular distribution of the charge-exchange reaction was subjected to a careful test in a separated beam. The results were compared with the results of a Monte-Carlo simulation of the antineutron detection. The cross sections measured in two beam periods in November and December 1983 are consistent with the published data in the hitherto available momentum range above about 350 MeV/c. Especially in the cross section of the annihilation into charged pions a statistically significant signal at a mass of 1937 MeV/c2 appears. However further measurements are necessary to study all systematic causes of errors. (orig.)
Annual Cross-Sectional Study of Nurse-Sensitive Problems
Færch, Jane; Tewes, Marianne; Overgaard, Dorthe;
2015-01-01
A cross-sectional evaluation of nurse-sensitive problems in hospitalized patients is conducted once per year to monitor patient problems identified by nurses, whether nurses implement interventions to overcome the problems, and if the problems are solved. This article describes a systematic metho...
Accurate momentum transfer cross section for the attractive Yukawa potential
Khrapak, S. A., E-mail: Sergey.Khrapak@dlr.de [Forschungsgruppe Komplexe Plasmen, Deutsches Zentrum für Luft- und Raumfahrt, Oberpfaffenhofen (Germany)
2014-04-15
Accurate expression for the momentum transfer cross section for the attractive Yukawa potential is proposed. This simple analytic expression agrees with the numerical results better than to within ±2% in the regime relevant for ion-particle collisions in complex (dusty) plasmas.
Inelastic neutron scattering cross section in ferromagnetic nanowires
This article presents the first theoretical study of the inelastic neutron cross section in arrays of cylindrical ferromagnetic nanowires. The recently developed dipolar-exchange theory of spin-wave excitations in such wires is used. Results are represented for the few lowest bulk quantized spin-wave modes of different forms
Ratio of the hydrogen and manganese cross sections
A summary of the results of measurements of hydrogen to manganese cross section ratios are tabulated using weighted fits to the experimental data. Comparison of results using volumetric, gravimetric, and densimetric concentration measurements with and without contaminant corrections indicates that the methods are capable of equal accuracy
Systematic analysis of reaction cross sections of carbon isotopes
Horiuchi, W; Kohama, A; Suzuki, Y
2006-01-01
We systematically analyze total reaction cross sections of carbon isotopes with N=6--16 on a $^{12}$C target for wide range of incident energy. The intrinsic structure of the carbon isotope is described by a Slater determinant generated from a phenomenological mean-field potential, which reasonably well reproduces the ground state properties for most of the even $N$ isotopes. We need separate studies not only for odd nuclei but also for $^{16}$C and $^{22}$C. The density of the carbon isotope is constructed by eliminating the effect of the center of mass motion. For the calculations of the cross sections, we take two schemes: one is the Glauber approximation, and the other is the eikonal model using a global optical potential. We find that both of the schemes successfully reproduce low and high incident energy data on the cross sections of $^{12}$C, $^{13}$C and $^{16}$C on $^{12}$C. The calculated reaction cross sections of $^{15}$C are found to be considerably smaller than the empirical values observed at l...
Plots of the experimental and evaluated photoneutron cross-sections
Graphical plots of experimental data of photon induced nuclear reaction cross-sections are given for many elements and isotopes. The numerical data were taken from the international EXFOR data library which is available from the nuclear data centers. For selected nuclides evaluated data have been included in the plots. (author). Refs, 3 tabs
Absolute photoionization cross-section of the propargyl radical
Savee, John D.; Welz, Oliver; Taatjes, Craig A.; Osborn, David L. [Sandia National Laboratories, Combustion Research Facility, Livermore, California 94551 (United States); Soorkia, Satchin [Institut des Sciences Moleculaires d' Orsay, Universite Paris-Sud 11, Orsay (France); Selby, Talitha M. [Department of Chemistry, University of Wisconsin, Washington County Campus, West Bend, Wisconsin 53095 (United States)
2012-04-07
Using synchrotron-generated vacuum-ultraviolet radiation and multiplexed time-resolved photoionization mass spectrometry we have measured the absolute photoionization cross-section for the propargyl (C{sub 3}H{sub 3}) radical, {sigma}{sub propargyl}{sup ion}(E), relative to the known absolute cross-section of the methyl (CH{sub 3}) radical. We generated a stoichiometric 1:1 ratio of C{sub 3}H{sub 3} : CH{sub 3} from 193 nm photolysis of two different C{sub 4}H{sub 6} isomers (1-butyne and 1,3-butadiene). Photolysis of 1-butyne yielded values of {sigma}{sub propargyl}{sup ion}(10.213 eV)=(26.1{+-}4.2) Mb and {sigma}{sub propargyl}{sup ion}(10.413 eV)=(23.4{+-}3.2) Mb, whereas photolysis of 1,3-butadiene yielded values of {sigma}{sub propargyl}{sup ion}(10.213 eV)=(23.6{+-}3.6) Mb and {sigma}{sub propargyl}{sup ion}(10.413 eV)=(25.1{+-}3.5) Mb. These measurements place our relative photoionization cross-section spectrum for propargyl on an absolute scale between 8.6 and 10.5 eV. The cross-section derived from our results is approximately a factor of three larger than previous determinations.
Deep spallation cross sections in high energy protons - uranium interactions
Cross sections of deep spallation products - from phosphorus to hafnium - formed in uranium by high energy protons (Ep > or approx. 10 GeV) have been calculated with a simple semi-empirical formula. The results are in excellent agreement with experimental data. (orig.)
Absolute cross-section of turbojet aviation engine calculation
Ryabokon, Evgen
2012-01-01
The calculation method of three-dimensional model of turbojet aviation engine is offered, thus the form of turbine vanes with spiralling is described like parametric surface. The method allows make the calculation of absolute cross-section (ACS) of turbojet aviation engines with different geometrical parameters. The calculation results of ACS of aviation engine are presented.
Top quark production cross-section at the Tevatron Collider
Ranjan, Kirti; /Delhi U. /Fermilab
2005-06-01
We present the preliminary results of the t{bar t} pair production cross-section measurements and the single top quark exclusion limits carried out by the D0 and the CDF collaborations in Run II of the Tevatron. The dataset for the various measurements ranges from 140 pb{sup -1} to 350 pb{sup -1}.
Measurement, calculation and evaluation of photon production cross-sections
The meeting proceedings were divided into three sessions devoted to the following topics: Experimental measurement and techniques (3 papers), calculation of photon cross-sections (9 papers), and evaluation (2 papers). A separate abstract was prepared for each of these papers. Refs, figs and tabs
Total cross section of ultra-relativistic heavy ion collisions
A possible increase of nuclear cross section at ultra-relativistic energies is suggested. Such an increase is expected to start much earlier than in the case of proton-proton reactions due to more diffused nuclear surface compared to that of proton. Experimental data seem to be consistent with this picture. (author)
Cross-sectional imaging patterns of desmoplastic fibroma
Mahnken, A.H.; Nolte-Ernsting, C.C.; Wildberger, J.E.; Guenther, R.W. [Dept. of Diagnostic Radiology, University Hospital, University of Technology, Aachen (Germany); Wirtz, D.C. [Dept. of Orthopaedics, University Hospital, University of Technology, Aachen (Germany)
2001-07-01
The aim of this study was to work out the cross-sectional imaging characteristics of desmoplastic fibroma (DF). In 3 patients with histologically proven DF, the imaging characteristics obtained with cross-sectional techniques were reviewed retrospectively. Radiographs and CT scans were available in all patients, and plain and contrast-enhanced MR examinations in 2 patients. Compared with conventional radiographs, CT allowed more accurate assessment of the extent of bone destruction including cortical breakthrough and articular invasion. Intramedullary tumor growth and soft tissue extension was best detected with MRI. Apart from heterogeneity on MR images, DF displayed nonspecific low signal intensity on unenhanced T1-weighted images and an intermediate to high signal intensity including areas of low intensity on T2-weighted images. Desmoplastic fibroma showed a distinct, inhomogeneous gadolinium enhancement. Although cross-sectional imaging features of DF are nonspecific, some MR characteristics, such as inhomogeneous contrast enhancement and the presence of low-intensity regions on T2-weighted images, are helpful in determining the differential diagnosis. Cross-sectional imaging of DF is useful for local staging of the tumor because it provides valuable information about the extent of bone destruction as well as medullary and extraosseous spread. (orig.)
Double differential cross sections for methane molecules at intermediate energies
Double differential cross sections (DDCS) can be obtained by the measurements of energy and angular distributions of one of the two outgoing electrons by a detector. In this pespective, we used methane molecule as a target that is reasonable to expect to understand ionization mechanisms of polyatomic molecular systems.
Single top cross section and properties measurements in CMS
Komm, Matthias
2016-01-01
Single top quarks can be produced via the t, tW, and s channel. Studying these processes provides a test of the theory of electroweak interactions involving heavy quarks. Recent results on cross section and property measurements in pp collisions by the CMS collaboration at center-of-mass energies of 7, 8, and 13 TeV are reviewed.
Recent integral cross section validation measurements at the ASP facility
Packer, L.W., E-mail: lee.packer@ccfe.ac.uk [Culham Centre for Fusion Energy, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB (United Kingdom); Hughes, S. [AWE, Aldermaston, Reading, Berkshire RG7 4PR (United Kingdom); Gilbert, M.; Lilley, S.; Pampin, R. [Culham Centre for Fusion Energy, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB (United Kingdom)
2013-10-15
Highlights: • Recent results of integral cross section measurements at ASP obtained using high purity elemental are detailed. • Details of the data processing tools and method are included which allows to preserve reaction product decay information. • C/E plots for measurements taken for number of reactions and the European Activation File 2010 cross section evaluation. • New integral data included for Ti-46(n,p)Sc-46m. -- Abstract: This work presents new integral data measured at the ASP 14 MeV neutron irradiation facility at Aldermaston in the UK, which has recently become available for fusion-related work through the CCFE materials programme. Measurements of reaction products from activation experiments using elemental foils were carried out using gamma spectrometry in a high efficiency, high-purity germanium (HPGe) detector and associated digital signal processing hardware. Following irradiation and rapid extraction to the measurement cell, gamma emissions were acquired with both energy and time bins. Integral cross section and half-life data have been derived from these measurements. Selected integral cross section values are presented from the measurement campaigns. Details of the data processing approach and outputs generated are highlighted for measurement of the {sup 186}W(n,2n){sup 185m}W reaction—a selected short-lived reaction resulting from W foil irradiations; C/E results are reported along with the associated uncertainties and compared using the SAFEPAQ-II tool against existing available data.
Event history analysis and the cross-section
Keiding, Niels
2006-01-01
Examples are given of problems in event history analysis, where several time origins (generating calendar time, age, disease duration, time on study, etc.) are considered simultaneously. The focus is on complex sampling patterns generated around a cross-section. A basic tool is the Lexis diagram....
Commentary: Mediation Analysis, Causal Process, and Cross-Sectional Data
Shrout, Patrick E.
2011-01-01
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…
Evaluation of the neutron cross sections for Pu-240
The present evaluation is proposed to supersede the ENDF/B-V, Revision 2 file for 240Pu. In this work, resonance parameters, cross sections, energy distributions, and angular distributions have been modified. These changes are outlined in detail and appropriate references included. 37 refs., 21 figs., 2 tabs
Capital yields assessment trough cross section production function
Kodera, Jan; Pánková, V.
2001-01-01
Roč. 8, č. 14 (2001), s. 79-87. ISSN 1212-074X R&D Projects: GA ČR GA402/00/0439 Institutional research plan: AV0Z1075907 Keywords : yield of capital * cross-section production function * maximisation of profit Subject RIV: AH - Economics
(, 3) Differential cross section of He (21) and He (23)
Kshamata Muktavat; M K Srivastava
2002-01-01
The angular distribution of the ﬁve-fold differential cross section for the electron impact double ionization of He (21 ) and He (23 ) has been studied. The kinematical conditions for maxima/minima in the angular distribution for the two cases have been compared. The two-step process for the double ionization is found to contribute very little in the triplet case.
Alternating series fit to the total cross sections
It is show by a simple Regge-type fit suggested recently by Donnachie and Landshoff that the universal pomeron contribution to various total cross sections may be represented by an alternating series a - b log s + c (log s)2 corresponding to a series of Regge multipoles. (author). 9 refs., 5 tabs., 5 figs
Neutron capture cross sections of 151,153Eu
The neutron capture cross section of 151,153Eu nuclei was measured using the Detector for Advanced Neutron Capture Experiments (DANCE) at the Los Alamos Neutron Science Center (LANSCE). Neutrons were produced at the Lujan Neutron Scattering Center and their energies were determined by the time-of-flight technique. The relative yield versus neutron incident energy from 0.1 eV to 2.0 keV for both 151Eu(n,) and 153Eu(n,) reactions was derived from events gated on the total energy and multiplicity measured by the DANCE array. The absolute cross section was determined by scaling the relative yield to the measured cross sections of well-known resonances. The shape of the yield curve agrees well with previous measurements in the resonance region for both 151Eu and 153Eu capture cross sections. New data are reported for neutron incident energies between 100 eV and 2.0 keV. The trend of data in the 0.3 keV to 2.0 keV region of neutron incident energy is consistent with the ENDF/BVI and the measurements of Macklin and Young. Crucial skills, acquired from these measurements in the early implementation of DANCE, are important to plan future experiments, which will yield results up to a few hundred keV neutron incident energy
Measurement of the cross sections of the minor transactinium isotopes
Measurements of neutron cross sections of the minor transactinium isotopes performed since the 1975 IAEA meeting on transactinium isotope nuclear data are reviewed. Some of the recent developments in experimental techniques are briefly described. As two specific examples measurements on 241Am and 230Th(n,f) are discussed in some detail
Electron scattering cross sections pertinent to electron microscopy
Some elements of the physics that determine cross sections are discussed, and various sources of data are indicated that should be useful for analytical microscopy. Atoms, molecules, and to some extent, solids are considered. Inelastic and elastic scattering of electrons and some solid-state effects are treated. 30 references
Generation of neutron scattering cross sections for silicon dioxide
A set of neutron scattering cross sections for silicon and oxygen bound in silicon dioxide were generated and validated. The cross sections were generated in the ACE format for MCNP using the nuclear data processing system NJOY, and the validation was done with published experimental data. This cross section library was applied to the calculation of five critical configurations published in the benchmark Critical Experiments with Heterogeneous Compositions of Highly Enriched Uranium, Silicon Dioxide and Polyethylene. The original calculations did not use the thermal scattering libraries generated in this work and presented significant differences with the experimental results. For this reason, the newly generated library was added to the input and the multiplication factor for each configuration was recomputed. The utilization of the thermal scattering libraries did not result in an improvement of the computational results. Based on this we conclude that integral experiments to validate this type of thermal cross sections need to be designed with a higher influence of thermal scattering in the measured result, and the experiments have to be performed under more controlled conditions.
C+C Fusion Cross Sections Measurements for Nuclear Astrophysics
Almaraz-Calderon, S.; Carnelli, P. F. F.; Rehm, K. E.; Albers, M.; Alcorta, M.; Bertone, P. F.; Digiovine, B.; Esbensen, H.; Fernandez Niello, J. O.; Henderson, D.; Jiang, C. L.; Lai, J.; Marley, S. T.; Nusair, O.; Palchan-Hazan, T.; Pardo, R. C.; Paul, M.; Ugalde, C.
2015-06-01
Total fusion cross section of carbon isotopes were obtained using the newly developed MUSIC detector. MUSIC is a highly efficient, active target-detector system designed to measure fusion excitation functions with radioactive beams. The present measurements are relevant for understanding x-ray superbursts. The results of the first MUSIC campaign as well as the astrophysical implications are presented in this work.
Neutron cross section covariances in the resolved resonance region.
Herman,M.; Mughabghab, S.F.; Oblozinsky, P.; Pigni, M.T.; Rochman, D.
2008-04-01
We present a detailed analysis of the impact of resonance parameter uncertainties on covariances for neutron capture and fission cross sections in the resolved resonance region. Our analysis uses the uncertainties available in the recently published Atlas of Neutron Resonances employing the Multi-Level Breit-Wigner formalism. We consider uncertainties on resonance energies along with those on neutron-, radiative-, and fission-widths and examine their impact on cross section uncertainties and correlations. We also study the effect of the resonance parameter correlations deduced from capture and fission kernels and illustrate our approach on several practical examples. We show that uncertainties of neutron-, radiative- and fission-widths are important, while the uncertainties of resonance energies can be effectively neglected. We conclude that the correlations between neutron and radiative (fission) widths should be taken into account. The multi-group cross section uncertainties can be properly generated from both the resonance parameter covariance format MF32 and the cross section covariance format MF33, though the use of MF32 is more straightforward and hence preferable.
Electron-metastable-helium differential and integral cross sections
The differential and integral cross sections for the excitation of the 23P and the 33L (L≡ S, P and D) states of He from the metastable 23S state are calculated using the semiclassical multichannel eikonal theory with a nine-channel basis set. Comparison is made with recent experimental results. (Author)
Testing of cross section libraries on zirconium benchmarks
Highlights: ► Calculations with ENDF/B-VII.0 nuclear data overpredict keff of Zr benchmarks. ► TRIGA criticality benchmark sensitive to Zr data. ► Zr scattering cross section responsible for differences in keff. ► Need for new experimental data on Zr cross sections. - Abstract: In this paper we investigate the influence of various up-to-date nuclear data libraries, such as ENDF/B-VI.6, ENDF/B-VII.0 and JEFF 3.1, on the multiplication factor of the TRIGA benchmark with fuel made of enriched uranium and zirconium hydride and SB light-water reactor benchmarks with fuel made of fissile material in zirconium matrix. The calculations are performed with the Monte Carlo computer code MCNP. Differences of ∼600 pcm in keff are observed for the benchmark model of the TRIGA reactor, while there are practically no differences in the kinf of the fuel. Therefore, an investigation is performed also for hypothetical homogeneous and heterogeneous systems with different leakage. The uncertainty analysis shows that the most important contributors to the difference in keff are the Zr isotopes (especially 90Zr and 91Zr) and thermal scattering data for H and Zr in ZrH. As the differences in keff due to the use of different cross section libraries are relatively large, there is certainly a need for a review of the evaluated cross section data of the zirconium isotopes.
Compound-nuclear reaction cross sections via surrogate reactions
The surrogate reaction method is an indirect technique for determining cross sections for nuclear reactions that proceed through a well-defined compound nucleus. In this method, the same compound nucleus is produced by an alternate ('surrogate') reaction and its decay products measured. The assumptions underlying the method are examined for the special case of 235U(n, f)
Uptake of atmospheric molecules by ice nanoparticles: Pickup cross sections
Lengyel, J.; Kočišek, J.; Poterya, V.; Pysanenko, A.; Svrčková, P.; Fárník, M.; Zaouris, D. K.; Fedor, J.
2012-07-01
Uptake of several atmospheric molecules on free ice nanoparticles was investigated. Typical examples were chosen: water, methane, NOx species (NO, NO2), hydrogen halides (HCl, HBr), and volatile organic compounds (CH3OH, CH3CH2OH). The cross sections for pickup of these molecules on ice nanoparticles (H2O)N with the mean size of bar{N} ≈ 260 (diameter ˜2.3 nm) were measured in a molecular beam experiment. These cross sections were determined from the cluster beam velocity decrease due to the momentum transfer during the pickup process. For water molecules molecular dynamics simulations were performed to learn the details of the pickup process. The experimental results for water are in good agreement with the simulations. The pickup cross sections of ice particles of several nanometers in diameter can be more than 3 times larger than the geometrical cross sections of these particles. This can have significant consequences in modelling of atmospheric ice nanoparticles, e.g., their growth.
Microscopic approach for the description of neutron cross section fluctuations
In the frame of the shell model approach to nuclear reactions, the elastic, inelastic and total cross section fluctuations are analyzed taking into account the structure of the nucleus under investigation (compound nucleus, doorway states, collective states). For the case of overlapping compound nucleus resonances a modified Hauser-Feshbach formula, which is assymetric relative to the inelastic and elastic channels, is obtained. (author)
Applications of cross sections for electron-molecule collision processes
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
Measurement of MA fission cross sections at YAYOI
Ohkawachi, Yasushi; Ohki, Shigeo; Wakabayashi, Toshio [Power Reactor and Nuclear Fuel Development Corp., Oarai, Ibaraki (Japan). Oarai Engineering Center
1998-03-01
Fission cross section ratios of minor actinide nuclides (Am-241, Am-243) relative to U-235 in the fast neutron energy region have been measured using a back-to-back (BTB) fission chamber at YAYOI fast neutron source reactor. A small BTB fission chamber was developed to measure the fission cross section ratios in the center of the core at YAYOI reactor. Dependence of the fission cross section ratios on neutron spectra was investigated by changing the position of the detector in the reactor core. The measurement results were compared with the fission cross sections in the JENDL-3.2, ENDF/B-VI and JEF-2.2 libraries. It was found that calculated values of Am-241 using the JENDL-3.2, ENDF/B-VI and JEF-2.2 data are lower by about 15% than the measured value in the center of the core (the neutron average energy is 1.44E+6(eV)). And, good agreement can be seen the measured value and calculated value of Am-243 using the JENDL-3.2 data in the center of the core (the neutron average energy is 1.44E+6)(eV), but calculated values of Am-243 using the ENDF/B-VI and JEF-2.2 data are lower by 11% and 13% than the measured value. (author)
Elastic differential cross sections for electron collisions with polyatomic molecules
Experimental data for electron-polyatomic molecule collisions are reviewed in connection with fusion and processing plasmas, as well as with the associated environmental issues. The electron scattering experiments for differential cross section (DCS) measurements for various processes, such as elastic scattering, have been performed across a broad range of energies (1-100 eV), mainly, at Sophia University since 1978, and some done under the collaborations with the Australian National University, Flinders University, and the Chungnam National University. As a benchmark cross section, elastic DCS are essential for the absolute scale conversion of inelastic DCS, as well as for testing computational methods. The need for cross-section data for a wide variety of molecular species is also discussed, because there is an urgent need to develop an international program to provide the scientific and technological communities with authoritative cross sections for electron-molecule interactions. Note that the detailed comparison with other data available is not given here. Ruther, other available data can be found in the references we cite. This course of action was adopted to keep this report to a sensible length, so that only our numerical data is provided here. (author)
Measurement of inclusive jet cross sections in photoproduction at HERA
Adloff, C; Andrieu, B; Anthonis, T; Astvatsatourov, A; Babaev, A; Bähr, J; Baranov, P S; Barrelet, E; Bartel, Wulfrin; Baumgartner, S; Becker, J; Beckingham, M; Beglarian, A; Behnke, O; Belousov, A; Berger, C; Berndt, T; Bizot, J C; Böhme, J; Boudry, V; Braunschweig, W; Brisson, V; Broker, H B; Brown, D P; Bruncko, Dusan; Büsser, F W; Bunyatyan, A; Burrage, A; Buschhorn, G; Bystritskaya, L; Campbell, A J; Caron, S; Cassol-Brunner, F; Chekelian, V; Clarke, D; Collard, Caroline; Contreras, J G; Coppens, Y R; Coughlan, J A; Cousinou, M C; Cox, B E; Cozzika, G; Cvach, J; Dainton, J B; Dau, W D; Daum, K; Davidsson, M; Delcourt, B; Delerue, N; Demirchyan, R A; de Roeck, A; De Wolf, E A; Diaconu, C A; Dingfelder, J; Dixon, P; Dodonov, V; Dowell, John D; Dubak, A; Duprel, C; Eckerlin, G; Eckstein, D; Efremenko, V; Egli, S; Eichler, R; Eisele, Franz; Eisenhandler, Eric F; Ellerbrock, M; Elsen, E; Erdmann, M; Erdmann, W; Faulkner, P J W; Favart, L; Fedotov, A; Felst, R; Ferencei, J; Ferron, S; Fleischer, M; Fleischmann, P; Fleming, Y H; Flucke, G; Flügge, G; Fomenko, A; Foresti, I; Formánek, J; Franke, G; Frising, G; Gabathuler, Erwin; Gabathuler, K; Garvey, J; Gassner, J; Gayler, J; Gerhards, R; Gerlich, C; Ghazaryan, S; Görlich, L; Gogitidze, N; Grab, C; Grabskii, V; Grässler, Herbert; Greenshaw, T; Grindhammer, G; Haidt, Dieter; Hajduk, L; Haller, J; Heinemann, B; Heinzelmann, G; Henderson, R C W; Hengstmann, S; Henschel, H; Henshaw, O; Heremans, R; Herrera-Corral, G; Herynek, I; Hildebrandt, M; Hilgers, M; Hiller, K H; Hladky, J; Hoting, P; Hoffmann, D; Horisberger, R P; Hovhannisyan, A V; Ibbotson, M; Issever, C; Jacquet, M; Jaffré, M; Janauschek, L; Janssen, X; Jemanov, V; Jönsson, L B; Johnson, C; Johnson, D P; Jones, M A S; Jung, H; Kant, D; Kapichine, M; Karlsson, M; Karschnick, O; Katzy, J; Keil, F; Keller, N; Kennedy, J; Kenyon, Ian Richard; Kiesling, C; Kjellberg, P; Klein, M; Kleinwort, C; Kluge, T; Knies, G; Koblitz, B; Kolya, S D; Korbel, V; Kostka, P; Koutouev, R; Koutov, A; Kroseberg, J; Krüger, K; Kuhr, T; Lamb, D; Landon, M P J; Lange, W; Lastoviicka, T; Laycock, P; Lebailly, E; Lebedev, A; Leiner, B; Lemrani, R; Lendermann, V; Levonian, S; List, B; Lobodzinska, E; Lobodzinski, B; Loginov, A; Loktionova, N A; Lubimov, V; Lüders, S; Lüke, D; Lytkin, L; Malden, N; Malinovskii, E I; Mangano, S; Marage, P; Marks, J; Marshall, R; Martyn, H U; Martyniak, J; Maxfield, S J; Meer, D; Mehta, A; Meier, K; Meyer, A B; Meyer, H; Meyer, J; Michine, S; Mikocki, S; Milstead, D; Mohrdieck, S; Mondragón, M N; Moreau, F; Morozov, A; Morris, J V; Müller, K; Murn, P; Nagovizin, V; Naroska, Beate; Naumann, J; Naumann, T; Newman, P R; Niebergall, F; Niebuhr, C B; Nix, O; Nowak, G; Nozicka, M; Olivier, B; Olsson, J E; Ozerov, D; Panassik, V; Pascaud, C; Patel, G D; Peez, M; Pérez, E; Petrukhin, A; Phillips, J P; Pitzl, D; Pöschl, R; Potachnikova, I; Povh, B; Rauschenberger, J; Reimer, P; Reisert, B; Risler, C; Rizvi, E; Robmann, P; Roosen, R; Rostovtsev, A A; Rusakov, S V; Rybicki, K; Sankey, D P C; Sauvan, E; Schatzel, S; Scheins, J; Schilling, F P; Schleper, P; Schmidt, D; Schmidt, S; Schmitt, S; Schneider, M; Schoeffel, L; Schöning, A; Schörner-Sadenius, T; Schröder, V; Schultz-Coulon, H C; Schwanenberger, C; Sedlak, K; Sefkow, F; Shevyakov, I; Shtarkov, L N; Sirois, Y; Sloan, Terence; Smirnov, P; Soloviev, Yu; South, D; Spaskov, V N; Specka, A E; Spitzer, H; Stamen, R; Stella, B; Stiewe, J; Strauch, I; Straumann, U; Chechelnitskii, S; Thompson, G; Thompson, P D; Tomasz, F; Traynor, D; Truöl, P; Tsipolitis, G; Tsurin, I; Turnau, J; Turney, J E; Tzamariudaki, E; Uraev, A; Urban, M; Usik, A; Valkár, S; Valkárová, A; Vallée, C; Van Mechelen, P; Vargas-Trevino, A; Vasilev, S; Vazdik, Ya A; Veelken, C; Vest, A; Vichnevski, A; Volchinski, V; Wacker, K; Wagner, J; Wallny, R; Waugh, B; Weber, G; Weber, R; Wegener, D; Werner, C; Werner, N; Wessels, M; Wiesand, S; Winde, M; Winter, G G; Wissing, C; Wobisch, M; Woerling, E E; Wünsch, E; Wyatt, A C; Zácek, J; Zaleisak, J; Zhang, Z; Zhokin, A; Zomer, F; Zur Nedden, M
2003-01-01
Inclusive jet cross sections are measured in photoproduction at HERA using the H1 detector. The data sample of e+ p -> e+ + jet + X events in the kinematic range of photon virtualities Q^2 < 1 GeV^2 and photon-proton centre-of-mass energies 95 < W_gammap < 285 GeV represents an integrated luminosity of 24.1 pb^-1. Jets are defined using the inclusive k_T algorithm. Single- and multi-differential cross sections are measured as functions of jet transverse energy E_T^jet and pseudorapidity \\eta^jet in the domain 5 < E_T^jet < 75 GeV and -1 < \\eta^jet < 2.5. The cross sections are found to be in good agreement with next-to-leading order perturbative QCD calculations corrected for fragmentation and underlying event effects. The cross section differential in E_T^jet, which varies by six orders of magnitude over the measured range, is compared with similar distributions from p pbar colliders at equal and higher energies.
Cross-sectional study of health effects of cryolite production
Friis, Henrik; Clausen, J; Gyntelberg, F
1989-01-01
A cross-sectional health study of 101 cryolite workers was performed, using spirometry and a questionnaire. Multiple regression analysis revealed a significant correlation between the index of smoking and a decrease in FEV1 (per cent). There was no significant correlation between work...
Skin Diseases: Cross-section of human skin
Skip Navigation Bar Home Current Issue Past Issues Skin Diseases Cross-section of human skin Past Issues / Fall 2008 Table of Contents For ... Logical Images, Inc. I n the areas of skin health and skin diseases, the NIH's National Institute ...
Analytical formulas for elastic neutrino-fermion scattering cross sections
Linder, J
2005-01-01
In this paper, we give a detailed and pedagogical derivation of cross sections for elastic eutrino-fermion scattering reactions. These are evaluated in the limit where the neutrino mass is neglible compared to the incoming momentum. Basic knowledge of QFT is assumed.
Accurate momentum transfer cross section for the attractive Yukawa potential
Khrapak, Sergey
2014-01-01
Accurate expression for the momentum transfer cross section for the attractive Yukawa potential is proposed. This simple analytic expression agrees with the numerical results better than to within 2% in the regime relevant for ion-particle collisions in complex (dusty) plasmas.
Accurate momentum transfer cross section for the attractive Yukawa potential
Khrapak, S. A.
2014-01-01
Accurate expression for the momentum transfer cross section for the attractive Yukawa potential is proposed. This simple analytic expression agrees with the numerical results better than to within $\\pm 2\\%$ in the regime relevant for ion-particle collisions in complex (dusty) plasmas.
Photon-Photon total inelastic cross-section
Corsetti, A; Godbole, RM; Pancheri, G.
1997-01-01
We discuss predictions for the total inelastic gamma-gamma cross-section and their model dependence on the input parameters. We compare results from a simple extension of the Regge Pomeron exchange model as well as predictions from the eikonalized mini-jet model with recent LEP data.
C+C Fusion Cross Sections Measurements for Nuclear Astrophysics
Total fusion cross section of carbon isotopes were obtained using the newly developed MUSIC detector. MUSIC is a highly efficient, active target-detector system designed to measure fusion excitation functions with radioactive beams. The present measurements are relevant for understanding x-ray superbursts. The results of the first MUSIC campaign as well as the astrophysical implications are presented in this work
Recent progress in fast neutron activation cross section data
A brief review is given of some significant investigations performed during the past few years in the area of fast neutron activation cross sections that may be relevant for the use of nuclear techniques in the exploration of mineral resources, in process and quality control in industry as well as for general analytical purposes. Differential capture cross sections are considered for the natural elements or isotopes of Fe, Cu, Se, Y, Nb, Cd, In, Gd, W, Os and Au. Some of the data are compared with statistical model calculations. Experimental and evaluated average cross sections for capture and threshold reactions in the spontaneous fission neutron field of 252Cf are reviewed taking into account the elements or isotopes of Mg, Al, Si, S, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Sr, Zr, Nb, Cd, In, Ba, Ta and Au. A summary of recent studies of differential cross sections for threshold reactions comprises data on Al, Si, S, Ti, Fe, Co, Ni, Cu, Zn, Zr, Nb, Ta, W and Au. Besides experimental investigations, evaluations and theoretical model calculations are considered. Cross sections at 14 MeV and in the region around this energy are reviewed for Na, Mg, Al, Cl, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Br, Sr, Zr, Nb, In, Er, Yb, Ta, W, Os, Ir, Au and Pb. Particular emphasis is laid on (n,p), (n,2n) and (n,α) reactions. (n,n') reactions are allowed for if the half-life of the metastable state excited permits elemental analyses by common experimental techniques. (orig.)
Recent progress in fast neutron activation cross section data
A brief review is given of some significant investigations performed during the past few years in the area of fast neutron activation cross sections that may be relevant for the use of nuclear techniques in the exploration of mineral resources, in process and quality control in industry as well as for general analytical purposes. Differential capture cross sections are considered for the natural elements or isotopes of Fe, Cu, Se, Y, Nb, Cd, In, Gd, W, Os and Au. Some of the data are compared with statistical model calculations. Experimental and evaluated average cross sections for capture and threshold reactions in the spontaneous fission neutron field of 252Cf are reviewed taking into account the elements or isotopes of Mg, Al, Si, S, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Sr, Zr, Nb, Cd, In, Ba, Ta and Au. A summary of recent studies of differential cross sections for threshold reactions comprises data on Al, Si, S, Ti, Fe, Co, Ni, Cu, Zn, Zr, Nb, Ta, W and Au. Besides experimental investigations, evaluations and theoretical model calculations are considered. Cross sections at 14 MeV and in the region around this energy are reviewed for Na, Mg, Al, Cl, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Br, Sr, Zr, Nb, In, Er, Yb, Ta, W, Os, Ir, Au and Pb. Particular emphasis is laid on (n,p), (n,2n) and (n,α) reactions. (n,n') reactions are allowed for if the half-life of the metastable state excited permits elemental analyses by common experimental techniques. (author)
Displacement cross section and DPA calculations using NMTC/JAERI
A new function calculating displacement cross sections using the Lindhard-Robinson model is implemented in the nucleon-meson transport code NMTC/JAERI. The nucleon-nucleus cross sections in the energy region above 950 MeV and the angular distribution data of elastic scattering are also modified to evaluate the displacement cross sections as accurate as possible. The displacement cross sections of Cr, Fe Ni, and type 316 stainless steel are calculated with the updated version of NMTC/JAERI. It is confirmed that the calculated displacement cross sections caused by the elastic scattering connect smoothly with the value of the JENDL PKA File at 20 MeV. With these calculation values, the displacement per atoms (DPA) in the beam window and target vessel of a mercury target are estimated in a framework of the neutronics design study of the spallation target bombarded with 1.5 GeV protons with a power of 5 MW. The following three beam conditions are selected in this calculation; (a) uniform distribution with average current density of 48 μA/cm2, (b) parabolic distribution with average current density of 48 μA/cm2, and (c) that with average current density of 24 μA/cm2. The DPAs are estimated as (a) 68, (b) 114, and (c) 70 DPA/yr at the beam windows, and (a) 41, (b) 52, and (c) 37 DPA/yr at the target vessel for the three cases, respectively. It is found that the DPAs obtained in this study are almost the same as the results of other design studies for spallation neutron source facilities. (author)
Burcharth, Hans F.; Meinert, Palle; Andersen, Thomas Lykke
This report present the results of 2D physical model tests (length scale 1:50) carried out in a waveflume at Dept. of Civil Engineering, Aalborg University (AAU). The objective of the tests was: To identify cross section design which restrict the overtopping to acceptable levels and to record the...
Quantifying and predicting interpretational uncertainty in cross-sections
Randle, Charles; Bond, Clare; Monaghan, Alison; Lark, Murray
2015-04-01
Cross-sections are often constructed from data to create a visual impression of the geologist's interpretation of the sub-surface geology. However as with all interpretations, this vision of the sub-surface geology is uncertain. We have designed and carried out an experiment with the aim of quantifying the uncertainty in geological cross-sections created by experts interpreting borehole data. By analysing different attributes of the data and interpretations we reflect on the main controls on uncertainty. A group of ten expert modellers at the British Geological Survey were asked to interpret an 11.4 km long cross-section from south-east Glasgow, UK. The data provided consisted of map and borehole data of the superficial deposits and shallow bedrock. Each modeller had a unique set of 11 boreholes removed from their dataset, to which their interpretations of the top of the bedrock were compared. This methodology allowed quantification of how far from the 'correct answer' each interpretation is at 11 points along each interpreted cross-section line; through comparison of the interpreted and actual bedrock elevations in the boreholes. This resulted in the collection of 110 measurements of the error to use in further analysis. To determine the potential control on uncertainty various attributes relating to the modeller, the interpretation and the data were recorded. Modellers were asked to fill out a questionnaire asking for information; such as how much 3D modelling experience they had, and how long it took them to complete the interpretation. They were also asked to record their confidence in their interpretations graphically, in the form of a confidence level drawn onto the cross-section. Initial analysis showed the majority of the experts' interpreted bedrock elevations within 5 metres of those recorded in the withheld boreholes. Their distribution is peaked and symmetrical about a mean of zero, indicating that there was no tendency for the experts to either under
Fission fragment angular distributions and fission cross section validation
The present knowledge of angular distributions of neutron-induced fission is limited to a maximal energy of 15 MeV, with large discrepancies around 14 MeV. Only 238U and 232Th have been investigated up to 100 MeV in a single experiment. The n-TOF Collaboration performed the fission cross section measurement of several actinides (232Th, 235U, 238U, 234U, 237Np) at the n-TOF facility using an experimental set-up made of Parallel Plate Avalanche Counters (PPAC), extending the energy domain of the incident neutron above hundreds of MeV. The method based on the detection of the 2 fragments in coincidence allowed to clearly disentangle the fission reactions among other types of reactions occurring in the spallation domain. I will show the methods we used to reconstruct the full angular resolution by the tracking of fission fragments. Below 10 MeV our results are consistent with existing data. For example in the case of 232Th, below 10 MeV the results show clearly the variation occurring at the first (1 MeV) and second (7 MeV) chance fission, corresponding to transition states of given J and K (total spin and its projection on the fission axis), and a much more accurate energy dependence at the 3. chance threshold (14 MeV) has been obtained. In the spallation domain, above 30 MeV we confirm the high anisotropy revealed in 232Th by the single existing data set. I'll discuss the implications of this finding, related to the low anisotropy exhibited in proton-induced fission. I also explore the critical experiments which is valuable checks of nuclear data. The 237Np neutron-induced fission cross section has recently been measured in a large energy range (from eV to GeV) at the n-TOF facility at CERN. When compared to previous measurements, the n-TOF fission cross section appears to be higher by 5-7 % beyond the fission threshold. To check the relevance of n-TOF data, we simulate a criticality experiment performed at Los Alamos with a 6 kg sphere of 237Np. This sphere was
Fully hadronic tt cross section with the ATLAS detector
Coccaro, Andrea; collaboration, on behalf of the ATLAS
2013-01-01
A measurement of the tt production cross section in the all-hadronic decay mode is presented using 4.7 fb-1 of proton-proton collisions at a centre of mass energy of 7 TeV collected by the ATLAS experiment in 2011. Events are selected using a multi-jet trigger. Kinematic and b-tagging requirements are then applied to identify tt event candidates. A kinematic fit reconstructs the event topology of the final state extracting the top-quark mass which is then used to measure the production cross ...
Measurements of neutral current deep inelastic scattering of protons colliding with longitudinally polarized positrons, performed with data recorded in years 2006 and 2007 with the ZEUS detector, corresponding to an integrated luminosity of L=113.3 pb-1, are presented. The single-differential cross sections dσ/dQ2, dσ/dx, dσ/dy and the double-differential reduced cross section σ were measured in the kinematic region of 18522 and y+ and the generalized structure function x F3 were extracted. All measurements agree well with the predictions of the Standard Model. (orig.)
Dugan, J. V., Jr.; Canright, R. B., Jr.
1972-01-01
The numerical capture cross section is calculated from the capture ratio, defined as the fraction of trajectories reaching a prescribed minimum separation of 3 A. The calculated capture cross sections for a rotational temperature of 77 K suggest large reaction cross sections in 80 K experiments for the large dipole-moment target, methyl cyanide.
Mid-IR Absorption Cross-Section Measurements of Hydrocarbons
Alrefae, Majed Abdullah
2013-05-01
Laser diagnostics are fast-response, non-intrusive and species-specific tools perfectly applicable for studying combustion processes. Quantitative measurements of species concentration and temperature require spectroscopic data to be well-known at combustion-relevant conditions. Absorption cross-section is an important spectroscopic quantity and has direct relation to the species concentration. In this work, the absorption cross-sections of basic hydrocarbons are measured using Fourier Transform Infrared (FTIR) spectrometer, tunable Difference Frequency Generation laser and fixed wavelength helium-neon laser. The studied species are methane, methanol, acetylene, ethylene, ethane, ethanol, propylene, propane, 1-butene, n-butane, n-pentane, n-hexane, and n-heptane. The Fourier Transform Infrared (FTIR) spectrometer is used for the measurements of the absorption cross-sections and the integrated band intensities of the 13 hydrocarbons. The spectral region of the spectra is 2800 – 3400 cm-1 (2.9 – 3.6 μm) and the temperature range is 673 – 1100 K. These valuable data provide huge opportunities to select interference-free wavelengths for measuring time-histories of a specific species in a shock tube or other combustion systems. Such measurements can allow developing/improving chemical kinetics mechanisms by experimentally determining reaction rates. The Difference Frequency Generation (DFG) laser is a narrow line-width, tunable laser in the 3.35 – 3.53 μm wavelength region which contains strong absorption features for most hydrocarbons due to the fundamental C-H vibrating stretch. The absorption cross-sections of propylene are measured at seven different wavelengths using the DFG laser. The temperature range is 296 – 460 K which is reached using a Reflex Cell. The DFG laser is very attractive for kinetic studies in the shock tube because of its fast time response and the potential possibility of making species-specific measurements. The Fixed wavelength
Zhao, Juan
2013-04-01
We investigated spin-orbit-induced intersystem crossing effects in the title reaction by the time-dependent wave-packet method combined with an extended split operator scheme. We performed non-adiabatic calculations of the fine-structure-resolved cross section and adiabatic calculations of integral cross section. The calculations are based on the potential energy surfaces of 3A' and the two degenerate 3A'' states [S. Rogers, D. Wang, A. Kuppermann, and S. Walch, J. Phys. Chem. A 104, 2308 (2000)], 10.1021/jp992985g, together with the spin-orbit coupling matrix [B. Maiti and G. C. Schatz, J. Chem. Phys. 119, 12360 (2003)], 10.1063/1.1623481 and singlet 1A' potential energy surface [J. Dobbyn and P. J. Knowles, Faraday Discuss. 110, 247 (1998)]. The results of the O(3P) + D2 are similar to those of the O(3P) + H2 reaction. The product spin state-resolved reaction cross section and the total reaction cross section both show that the adiabatic channel is dominant in all cases, and the non-adiabatic channels have cross sections of several orders of magnitude smaller than the adiabatic channels at high collision energy. Although the cross sections caused by the intersystem crossing effects in the O(3P) + D2 reaction are larger than those in the O(3P) + H2 reaction, the differences in non-adiabaticity between these two reaction systems are quite modest. Based on the results of the O(3P) + H2 reaction, we can predict that the influence of spin-orbit on the total reaction cross sections of the O(3P) + D2 reaction is also insignificant. However, these non-adiabatic effects can be reflected in the presence of some forward-scattering in the angular distribution for the OD product.
Developing Scientific Reasoning Through Drawing Cross-Sections
Hannula, K. A.
2012-12-01
Cross-sections and 3D models of subsurface geology are typically based on incomplete information (whether surface geologic mapping, well logs, or geophysical data). Creating and evaluating those models requires spatial and quantitative thinking skills (including penetrative thinking, understanding of horizontality, mental rotation and animation, and scaling). However, evaluating the reasonableness of a cross-section or 3D structural model also requires consideration of multiple possible geometries and geologic histories. Teaching students to create good models requires application of the scientific methods of the geosciences (such as evaluation of multiple hypotheses and combining evidence from multiple techniques). Teaching these critical thinking skills, especially combined with teaching spatial thinking skills, is challenging. My Structural Geology and Advanced Structural Geology courses have taken two different approaches to developing both the abilities to visualize and to test multiple models. In the final project in Structural Geology (a 3rd year course with a pre-requisite sophomore mapping course), students create a viable cross-section across part of the Wyoming thrust belt by hand, based on a published 1:62,500 geologic map. The cross-section must meet a number of geometric criteria (such as the template constraint), but is not required to balance. Each student tries many potential geometries while trying to find a viable solution. In most cases, the students don't visualize the implications of the geometries that they try, but have to draw them and then erase their work if it does not meet the criteria for validity. The Advanced Structural Geology course used Midland Valley's Move suite to test the cross-sections that they made in Structural Geology, mostly using the flexural slip unfolding algorithm and testing whether the resulting line lengths balanced. In both exercises, students seemed more confident in the quality of their cross-sections when the
Importance of neutron cross-sections for transmutation
Accurate neutron cross-section data is fundamental to the reliable design of any transmutation device, and, in particular, of an accelerator-driven system (ADS). Calculations of the behaviour of the core depend strongly on the cross-section data: parameters such as the multiplication coefficient, power densities or reactivity may vary significantly depending on the nuclear-data (ND) library used. These potential discrepancies justify the need to improve the present data for several isotopes and reaction channels, for a wide range of neutron energies from thermal to high-energy. This paper follows on from work performed in the context of the nTOF-ND-ADS project of the EURATOM 5th framework program, where a preliminary analysis of the effects of different cross-section data was carried out using the Monte Carlo code package FLUKA-EAMC. That study was based on the Pb-Bi cooled 80 MWth energy-amplifier prototype, and included comparison of parameters such as source multiplication coefficient ksrc, neutron spectra, neutron balance and one-group cross-sections for different isotopes using different nuclear-data evaluations. The present work expands this analysis to other isotopes of interest such as 233U, 243Am, 244,245Cm and the long-lived fission fragments (LLFFs) 99Tc and 129I. A direct comparison of nuclear-data libraries to indicate the spread between values was performed. The paper also extends the sensitivity analysis of the parameters mentioned above to moderated systems, such as TRADE (triga accelerator-driven experiment): a 1 MW triga reactor coupled with a 110-140 MeV-2 mA proton cyclotron. Study of the discrepancies in the thermal and epithermal regions is essential for the design of systems for the transmutation of LLFF (transmutation by adiabatic resonance crossing, TARC) and also important for minor actinides (MAs) for which sub-threshold fission should not be neglected. These studies highlight the relative importance of different isotopes and assess the
Vortex breakdown in closed containers with polygonal cross sections
Naumov, I. V., E-mail: naumov@itp.nsc.ru; Dvoynishnikov, S. V.; Kabardin, I. K.; Tsoy, M. A. [Kutateladze Institute of Thermophysic SB RAS, Novosibirsk 630090 (Russian Federation)
2015-12-15
The vortex breakdown bubble in the confined flow generated by a rotating lid in closed containers with polygonal cross sections was analysed both experimentally and numerically for the height/radius aspect ratio equal to 2. The stagnation point locations of the breakdown bubble emergence and the corresponding Reynolds number were determined experimentally and in addition computed numerically by STAR-CCM+ CFD software for square, pentagonal, hexagonal, and octagonal cross section configurations. The flow pattern and the velocity were observed and measured by combining the seeding particle visualization and the temporal accuracy of laser Doppler anemometry. The vortex breakdown size and position on the container axis were determined for Reynolds numbers, ranging from 1450 to 2400. The obtained results were compared with the flow structure in the closed container of cubical and cylindrical configurations. It is shown that the measured evolution of steady vortex breakdown is in close agreement with the numerical results.
Cross-Section Measurements with the Radioactive Isotope Accelerator (RIA)
RIA will produce beams of exotic nuclei of unprecedented luminosity. Preliminary studies of the feasibility of measuring cross-sections of interest to the science based stockpile stewardship (SBSS) program will be presented, and several experimental techniques will be discussed. Cross-section modeling attempts for the A = 95 mass region will be shown. In addition, several radioactive isotopes could be collected for target production or medical isotope purposes while the main in-beam experiments are running. The inclusion of a broad range mass analyzer (BRAMA) capability at RIA will enable more effective utilization of the facility, enabling the performance of multiple experiments at the same time. This option will be briefly discussed
Cross-Section Measurements with the Radioactive Isotope Accelerator (ria)
Stoyer, M. A.; Moody, K. J.; Wild, J. F.; Patin, J. B.; Shaughnessy, D. A.; Stoyer, N. J.; Harris, L. J.
2003-10-01
RIA will produce beams of exotic nuclei of unprecedented luminosity. Preliminary studies of the feasibility of measuring cross-sections of interest to the science based stockpile stewardship (SBSS) program will be presented, and several experimental techniques will be discussed. Cross-section modeling attempts for the A = 95 mass region will be shown. In addition, several radioactive isotopes could be collected for target production or medical isotope purposes while the main in-beam experiments are running. The inclusion of a broad range mass analyzer (BRAMA) capability at RIA will enable more effective utilization of the facility, enabling the performance of multiple experiments at the same time. This option will be briefly discussed.
Cross-Section Measurements with the Radioactive Isotope Accelerator (RIA)
Stoyer, M A; Moody, K J; Wild, J F; Patin, J B; Shaughnessy, D A; Stoyer, N J; Harris, L J
2002-11-19
RIA will produce beams of exotic nuclei of unprecedented luminosity. Preliminary studies of the feasibility of measuring cross-sections of interest to the science based stockpile stewardship (SBSS) program will be presented, and several experimental techniques will be discussed. Cross-section modeling attempts for the A = 95 mass region will be shown. In addition, several radioactive isotopes could be collected for target production or medical isotope purposes while the main in-beam experiments are running. The inclusion of a broad range mass analyzer (BRAMA) capability at RIA will enable more effective utilization of the facility, enabling the performance of multiple experiments at the same time. This option will be briefly discussed.
Improved estimate of the cross section for inverse beta decay
Ankowski, Artur M
2016-01-01
The hypothesis of the conserved vector current, relating the vector weak and isovector electromagnetic currents, plays a fundamental role in quantitative description of neutrino interactions. Despite being experimentally confirmed with great precision, it is not fully implemented in existing calculations of the cross section for inverse beta decay, the dominant mechanism of antineutrino scattering at energies below a few tens of MeV. In this article, I estimate the corresponding cross section and its uncertainty, ensuring conservation of the vector current. While converging to previous calculations at energies of several MeV, the obtained result is appreciably lower and predicts more directional positron production near the reaction threshold. These findings suggest that in the current estimate of the flux of geologically produced antineutrinos the 232Th and 238U components may be underestimated by 6.1 and 3.7%, respectively. The proposed search for light sterile neutrinos using a 144Ce--144Pr source is predi...
Higgs Boson Cross Section from CTEQ-TEA Global Analysis
Dulat, Sayipjamal; Gao, Jun; Huston, Joey; Nadolsky, Pavel; Pumplin, Jon; Schmidt, Carl; Stump, Daniel; Yuan, C -P
2013-01-01
We study the uncertainties of the Higgs boson production cross section through the gluon fusion subprocess at the LHC (with $\\sqrt s=7, 8$ and $14$ TeV) arising from the uncertainties of the parton distribution functions (PDFs) and of the value of the strong coupling constant $\\alpha_s(M_Z)$. These uncertainties are computed by two complementary approaches, based on the Hessian and the Lagrange Multiplier methods within the CTEQ-TEA global analysis framework. We find that their predictions for the Higgs boson cross section are in good agreement. Furthermore, the result of the Lagrange Multiplier method supports the prescriptions we have previously provided for using the Hessian method to calculate the combined PDF and $\\alpha_s$ uncertainties, and to estimate the uncertainties at the $68%$ confidence level by scaling them from the 90% confidence level.
On a relation between production processes and total cross sections
Munier, Stephane
2013-01-01
Perturbative QCD is the appropriate tool to describe many important properties of the inclusive observables measured at electron-proton (or ion) colliders, such as the energy dependence of the total cross sections in well-chosen kinematical regions. This is because the electron may effectively be replaced by its cloud of photons, whose virtualities provide a hard scale that enables perturbative expansions. At hadron colliders instead, there is no hard scale in the initial state. Therefore, the observables one may compute perturbatively involve the production of jets, and thus belong to a quite different class of observables. However, it turns out that there is a formal relation between production processes and total cross sections, enabling one to apply calculations of the latter to the former. We review this relation, and present our recent proof that it holds at next-to-leading order (in the BFKL sense).
Introduction of surrogate approach for determining nuclear reaction cross sections
The surrogate nuclear reaction approach plays an important role in the determination of nuclear reaction cross sections that are difficult to be measured directly. In this paper, we investigate its basis, factors affecting its accuracy, and its three variants: the external surrogate ratio method (ESRM), the internal surrogate ratio method (ISRM) and the hybrid surrogate ratio method (HSRM). Each method was described, and their applications or experimental tests were given, from which we could see their respective advantages and disadvantages. And it is found that the spin-parity mismatch, or the (weak) Weisskopf-Ewing limit equivalently, is an inherent limitation of the approach. It is also seen that the surrogate approach can reach a high accuracy, so it is a good indirect approach when the nuclear reaction cross sections are unavailable to be measured directly. (authors)
Fully hadronic ttbar cross section measurement with ATLAS detector
Bertella, C; The ATLAS collaboration
2011-01-01
The top quark pair production cross section in the fully hadronic final state is characterized by a six jet topology, two of which could be identified as originating from a b-quark using ATLAS b-tagging algorithms. Compared to other decay channels, this final state presents an advantageous larger branching ratio; on the other hand it suffers from a very large QCD multi-jet background, generally difficult to estimate from Monte Carlo simulation and therefore evaluated using data-driven techniques. It is essential, to efficiently trigger on these fully hadronic ttbar events, to use dedicated triggers. An overview of the analysis for ttbar production cross section measurement in the fully hadronic final state and the state-of-the-art of the b-jet trigger performance estimation are presented in this contribution.
Isotope Dependence of Superheavy Nucleus Formation Cross Section
LIU Zu-Hua; BAG Jing-Dong
2006-01-01
The dynamical process in the superheavy nucleus synthesis is studied on the basis of the two-dimensional Smolu-chowski equation. Special attention is paid to the isotope dependence of the cross section for the superheavy nucleus formation by means of making a comparison among the reaction systems of 54Fe + 204Pb, 56Fe + 206Pb, and 58Fe + 208Pb. It is found by this comparison that the formation cross section is very sensitive to the conditional saddle-point height and the neutron separation energy of the compound nucleus. Reaction systems with lower height of conditional saddle-point and smaller neutron separation energy are more favourable for the synthesis of the superheavy nucleus.
Accurate Development of Thermal Neutron Scattering Cross Section Libraries
Hawari, Ayman; Dunn, Michael
2014-06-10
The objective of this project is to develop a holistic (fundamental and accurate) approach for generating thermal neutron scattering cross section libraries for a collection of important enutron moderators and reflectors. The primary components of this approach are the physcial accuracy and completeness of the generated data libraries. Consequently, for the first time, thermal neutron scattering cross section data libraries will be generated that are based on accurate theoretical models, that are carefully benchmarked against experimental and computational data, and that contain complete covariance information that can be used in propagating the data uncertainties through the various components of the nuclear design and execution process. To achieve this objective, computational and experimental investigations will be performed on a carefully selected subset of materials that play a key role in all stages of the nuclear fuel cycle.
Vortex breakdown in closed containers with polygonal cross sections
The vortex breakdown bubble in the confined flow generated by a rotating lid in closed containers with polygonal cross sections was analysed both experimentally and numerically for the height/radius aspect ratio equal to 2. The stagnation point locations of the breakdown bubble emergence and the corresponding Reynolds number were determined experimentally and in addition computed numerically by STAR-CCM+ CFD software for square, pentagonal, hexagonal, and octagonal cross section configurations. The flow pattern and the velocity were observed and measured by combining the seeding particle visualization and the temporal accuracy of laser Doppler anemometry. The vortex breakdown size and position on the container axis were determined for Reynolds numbers, ranging from 1450 to 2400. The obtained results were compared with the flow structure in the closed container of cubical and cylindrical configurations. It is shown that the measured evolution of steady vortex breakdown is in close agreement with the numerical results
Unfolding the Boosted Top Quark Differential Cross Section
Berish, Danielle; Bellis, Matthew
2014-03-01
The high energy of the Large Hadron Collider at CERN makes possible the measurement of differential cross sections of the production of the top quark at higher momentum than previous studies. This provides a probe for tests of new physics. We used data from the CMS detector from the 2012, 8 TeV run. In these studies it is important to properly correct for efficiency and bias by using an unfolding process. We present a test of the robustness of the RooUnfold package, both the procedure in general and more specifically as it applies to the top quark measurement. The current status of the differential cross section measurement will be presented. This work was supported in part by NSF grant PHY-1307562.
Neutron Capture Cross Sections of 236U and 234U
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-π 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
Barrier Distributions and Systematics of Fusion- and Capture Cross Sections
Siwek-Wilczynska, K; Wilczynski, J
2003-01-01
Methods of predicting ''capture'' cross sections, i.e. , cross sections for sticking of two colliding nuclei after overcoming the interaction barrier, are presented. Close links between the capture excitation functions and smearing of the interaction barrier are discussed. By using a new ''polynomial fit'' method of determining d sup 2 (E sigma)/dE sup 2 values, the barrier distributions have been directly deduced for several precisely measured fusion excitation functions found in the literature, and compared with results of standard ''point difference'' method. Existing data on near-barrier fusion- and capture excitation functions for about 50 medium and heavy nucleus-nucleus systems have been analyzed using a simple formula obtained assuming Gaussian shape of the barrier distribution. Systematics of the barrier distribution parameters, the mean barrier and width of the distribution, are presented and proposed to be used together with the closed-form ''error function formula'' for predicting unknown capture ...
Titanium-I: fast neutron cross section measurements
Energy averaged total neutron cross sections are measured from approximately 1.0 to 4.5 MeV with few percent statistical accuracies. Differential elastic neutron scattering angular distributions are measured from 1.5 to 4.0 MeV at incident neutron energy intervals of less than or equal to 0.2 MeV. Differential cross sections for the inelastic neutron excitation of ''states'' at 158 +- 26, 891 +- 8, 984 +- 15, 1428 +- 39, 1541 +- 30, 1670 +- 80, 2007 +- 8, 2304 +- 22, 2424 +- 16, and 2615 +- 10 keV are measured for incident neutron energies from 1.5 to 4.0 MeV. Additional ''states'' are observed at approximately 2845 and 3009 keV. An energy-averaged optical-statistical model is deduced from the measured values and the implications of its use in the context of the strong fluctuating structure is discussed
Multigroup cross sections of resonant nuclei considering moderator mass differences
The multigroup constants library MGCL in the nuclear criticality safety evaluation code system JACS has been produced by the Bondarenko method to treat self-shielding effects. For estimating errors of this treatment, the multigroup cross sections of MGCL are compared with those obtained by precise treatment, i.e. with the weighted cross sections by ultra-fine spectra of neutron. The precise calculations are made for homogeneous mixtures of a resonant nucleus (235U, 238U, 239Pu, 240Pu, 242Pu or 56Fe) and a fictitious moderator nucleus with mass number 1, 12 or 200. The ultra-fine spectrum is calculated by the RABBLE code. Distinct differences are found in the self-shielding factors by comparisons between both treatments. Moreover, as the mass number increases, depressions of the self-shielding factor at the resonance peaks and its enhancements at the window of resonances are observed. (author)
Near-Field Cross Section Imaging of Wideband Millimeter Wave
Kan Yingzhi
2016-01-01
Full Text Available Near-field millimeter wave imaging has been a hot topic recent years for its importance applications in the area of anti-terrorism. The penetrating characteristic of millimeter wave is of significant importance to security, such as the concealed weapons detection, ground-penetrating radar imaging, through-barrier imaging and so on. Cross section imaging is a basic aspect for near-field millimeter wave imaging, which includes antenna array distribution and wideband signal processing. This paper utilizes back projection method in space area to realize ultra-band nearfield cross section imaging. We induce two dimensional direction integral formulas to obtain the reconstruction image of the near-field imaging area, and the simulation results validate the effectiveness of this imaging algorithm.
On the Wong cross section and fusion oscillations
Rowley, N
2015-01-01
We re-examine the well-known Wong formula for heavy-ion fusion cross sections. Although this celebrated formula yields almost exact results for single-channel calculations for relatively heavy systems such as $^{16}$O+$^{144}$Sm, it tends to overestimate the cross section for light systems such as $^{12}$C+$^{12}$C. We generalise the formula to take account of the energy dependence of the barrier parameters and show that the energy-dependent version gives results practically indistinguishable from a full quantal calculation. We then examine the deviations arising from the discrete nature of the intervening angular momenta, whose effect can lead to an oscillatory contribution to the excitation function. We recall some compact, analytic expressions for these oscillations, and highlight the important physical parameters that give rise to them. Oscillations in symmetric systems are discussed, as are systems where the target and projectile identities can be exchanged via a strong transfer channel.
Elastic breakup cross sections of well-bound nucleons
Wimmer, K; Gade, A; Tostevin, J A; Baugher, T; Chajecki, Z; Coupland, D; Famiano, M A; Ghosh, T K; Howard, G F Grinyer M E; Kilburn, M; Lynch, W G; Manning, B; Meierbachtol, K; Quarterman, P; Ratkiewicz, A; Sanetullaev, A; Showalter, R H; Stroberg, S R; Tsang, M B; Weisshaar, D; Winkelbauer, J; Winkler, R; Youngs, M
2014-01-01
The 9Be(28Mg,27Na) one-proton removal reaction with a large proton separation energy of Sp(28Mg)=16.79 MeV is studied at intermediate beam energy. Coincidences of the bound 27Na residues with protons and other light charged particles are measured. These data are analyzed to determine the percentage contributions to the proton removal cross section from the elastic and inelastic nucleon removal mechanisms. These deduced contributions are compared with the eikonal reaction model predictions and with the previously measured data for reactions involving the re- moval of more weakly-bound protons from lighter nuclei. The role of transitions of the proton between different bound single-particle configurations upon the elastic breakup cross section is also quantified in this well-bound case. The measured and calculated elastic breakup fractions are found to be in good agreement.
Evaluation of Neutron Resonance Cross Section Data at GELINA
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
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.
Fast-neutron scattering cross sections of elemental silver
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 1600. 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
Benchmark calculations of 150-group cross section library for LMR's
For the purpose of diversification of selection of cross section library for neutron calculation of LMR, the 150 multi-group cross section library was generated from ENDF-VI release. The set was then examined by analyzing measured reactivity quantities such as control rod worth, Doppler effect and sodium void effect for BFS critical assemblies that we obtained through the critical experiment plan for developing the KALIMER core design. The calculated results based on 9 group structure using the new set were also compared with those of JEF set based on the same group structure and compared with those of the same set based on 25 group structure to find the proper group structure. ENDF-VI-based set shows a small deviation in predicting measured integral quantities in comparison with the previous set and a small group effect
Cross sections for bremsstrahlung production and electron-impact ionization
Electron transport codes require extensive information on the cross sections that govern electron interactions with the atoms that make up the medium. These processes include bremsstrahlung production in the atomic field, excitation and ionization of atomic electrons, and elastic scattering by screened atomic nuclei. These fundamental processes are of basic interest in many fields, but their inclusion in general purpose Monte Carlo transport codes imposes the requirement that reasonably accurate cross-section data be available over a very wide range of energies and for virtually any material. In this chapter, the author discusses two of these processes: bremsstrahlung production and electron-impact ionization. Both of these interactions result in the production of secondary radiations that can be important in radiation transport calculations
Deuterium target data and precision neutrino-nucleus cross sections
Meyer, Aaron S; Gran, Richard; Hill, Richard J
2016-01-01
Amplitudes derived from scattering data on elementary targets are basic inputs to neutrino-nucleus cross section predictions. A prominent example is the isovector axial nucleon form factor, $F_A(q^2)$, which controls charged current signal processes at accelerator-based neutrino oscillation experiments. Previous extractions of $F_A$ from neutrino-deuteron scattering data rely on a dipole shape assumption that introduces an unquantified error. A new analysis of world data for neutrino-deuteron scattering is performed using a model-independent, and systematically improvable, representation of $F_A$. A complete error budget for the nucleon isovector axial radius leads to $r_A^2=0.46(22) \\,{\\rm fm}^2$, with a much larger uncertainty than determined in the original analyses. The quasielastic neutrino-neutron cross section is determined as $\\sigma(\
Precision predictions of exclusive jet cross sections at the LHC
Gangal, Shireen
2015-10-15
With the discovery of the Higgs boson, a central objective of the LHC Higgs program is to study its properties in detail by exploring different production and decay channels. This requires precise theoretical predictions of inclusive cross sections as well as differential and exclusive cross sections. In this thesis, we study perturbative uncertainties in the fixed-order (FO) predictions of exclusive jet cross sections and obtain resummed predictions for a new class of rapidity-dependent jet veto observables, focusing on Higgs production via gluon gluon fusion (ggF) at the LHC. Experimental analyses at the LHC often use jet binning and jet selection cuts to distinguish between different Higgs production mechanisms and to separate signal from backgrounds. Such jet vetoes and jet selection cuts induce Sudakov logarithms of the ratio of the veto scale and the hard scale in the process. In the limit of very tight jet vetoes, these logarithms can become large and introduce large uncertainties in the FO predictions of cross sections. By resumming these large logarithms to all orders, the perturbative uncertainties can be considerably reduced. Whether in FO or resummed predictions, a consistent treatment of uncertainties in different jet bins is required. In the first part of the thesis, we studied in detail the perturbative uncertainties in the NLO predictions for pp→H+2-jets via ggF for the vector boson fusion (VBF) selection cuts used by ATLAS and CMS in their H→γγ analyses. Our study shows that, while applying strong restrictions on additional emissions is expected to increase the sensitivity to the VBF signal and reduce the ggF contribution, it is not necessarily beneficial for distinguishing the VBF and ggF production modes because of the quickly increasing ggF uncertainties. In the second part of the thesis, we introduce rapidity-dependent jet veto observables for which the transverse momentum of a jet is weighted by a smooth function of the jet rapidity
Precision predictions of exclusive jet cross sections at the LHC
With the discovery of the Higgs boson, a central objective of the LHC Higgs program is to study its properties in detail by exploring different production and decay channels. This requires precise theoretical predictions of inclusive cross sections as well as differential and exclusive cross sections. In this thesis, we study perturbative uncertainties in the fixed-order (FO) predictions of exclusive jet cross sections and obtain resummed predictions for a new class of rapidity-dependent jet veto observables, focusing on Higgs production via gluon gluon fusion (ggF) at the LHC. Experimental analyses at the LHC often use jet binning and jet selection cuts to distinguish between different Higgs production mechanisms and to separate signal from backgrounds. Such jet vetoes and jet selection cuts induce Sudakov logarithms of the ratio of the veto scale and the hard scale in the process. In the limit of very tight jet vetoes, these logarithms can become large and introduce large uncertainties in the FO predictions of cross sections. By resumming these large logarithms to all orders, the perturbative uncertainties can be considerably reduced. Whether in FO or resummed predictions, a consistent treatment of uncertainties in different jet bins is required. In the first part of the thesis, we studied in detail the perturbative uncertainties in the NLO predictions for pp→H+2-jets via ggF for the vector boson fusion (VBF) selection cuts used by ATLAS and CMS in their H→γγ analyses. Our study shows that, while applying strong restrictions on additional emissions is expected to increase the sensitivity to the VBF signal and reduce the ggF contribution, it is not necessarily beneficial for distinguishing the VBF and ggF production modes because of the quickly increasing ggF uncertainties. In the second part of the thesis, we introduce rapidity-dependent jet veto observables for which the transverse momentum of a jet is weighted by a smooth function of the jet rapidity
Cross section generation for LWR pin lattices simulations
Velasquez, Carlos E.; Macedo, Anderson A.P.; Cardoso, Fabiano S.; Pereira, Claubia; Veloso, Maria Auxiliadora F.; Costa, Antonella L. [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil); Instituto Nacional de Ciencia e Tecnologia de Reatores Nucleares Inovadores/CNPq, Brasilia, DF (Brazil); Barros, Graiciany de P. [Comissao Nacional de Energia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil)
2015-07-01
The majority of the neutron data library provided with the MCNP code is set at room temperature. Therefore, it is important to generate continuous energy cross section library for MCNP code for different temperatures. To evaluate the methodology used, the criticality calculations obtained using MCNP with the cross section generated at DEN/UFMG, are compared with the criticality data from the International Handbook of Evaluated Reactor Physics Benchmarks Experiments about the PIN lattices for light water reactors. It was used nuclear data from the ENDF-VII.1, JEFF-3.1 and TENDL-2014, which were processed using the NJOY99 code for different energies and temperatures. This code provides the nuclear data in ACE libraries, which then are added to MCNP libraries to perform the simulations. The results indicate the methodology efficiency developed by DEN/UFMG. (author)
Formulating analytic expressions for atomic collision cross sections
Methods to formulate analytic expression for atomic collision cross sections as a function of projectile energy are described on the basis of the experiences of the data compilation work for more than 20 years. Topics considered are the choice of appropriate functional forms for the expressions and optimization of adjustable parameters. To make extrapolation possible, functions to be used should have the form with reasonable asymptotic behavior. In this respect, modified Green-McNeal formulas have been found useful for various atomic collision cross sections. For ionization processes, a modified Lotz formula has often given a good fit. The ALESQ code for least-squares fits has been convenient to optimize adjustable parameters in analytic expressions. (author)
Measurement of the cross-sections of radioactive Ba isotopes
The radioactive Ba isotopes are produced in the interaction of 60 MeV/u 18O with 232Th. Ba is separated from thorium and complex reaction product mixture by BaCl2 precipitation and purified. 133Ba is used as the tracer to determine chemical yield of Ba. The Ba fraction is measured by off-line gamma-ray spectroscopy. The formation cross-sections of the individual Ba isotope is calculated from the intensities of gamma-ray peaks of each Ba isotope as well as relative nuclear data. The results show the n-deficient Ba isotopes still have higher formation cross-sections under the conditions of intermediate energy projectile and thick targets
Optical Conductivity of Metal Nanowires with Elliptical Cross Section
A.V. Korotun
2015-12-01
Full Text Available In this paper, the conductivity tensor diagonal components of elliptical wire have been calculated in the model of free-electron with the use the boundary shape perturbation method with due regard for the size dependence of the Fermi energy. The effect of the cross-sectional geometry and matter of the wires on the frequency dependence of the real and imaginary parts of the optical conductivity has been investigated.
Grit and Work Engagement: A Cross-Sectional Study
Yuhei Suzuki; Dai Tamesue; Kentaro Asahi; Yoshiki Ishikawa
2015-01-01
Grit, defined as perseverance of effort and consistency of interest, has attracted attention as a predictor of success in various fields beyond IQ and the Big Five personality dimension of Conscientiousness. The purpose of the current study was to examine previously uninvestigated questions regarding grit using a cross-sectional design among a large number of working adults in Japan. First, we tested geographical generalizability of associations between grit and orientations towards happiness...
NURSE STAFFING AND MEDICATION ERRORS: CROSS SECTIONAL OR LONGITUDINAL RELATIONSHIPS?
Mark, Barbara A.; Belyea, Michael
2009-01-01
We used autoregressive latent trajectory (ALT) modeling to examine the relationship between change in nurse staffing and change in medication errors over 6 months in 284 general medical-surgical nursing units. We also investigated the impact of select hospital and nursing unit characteristics on the baseline level and rate of change in medication errors. We found essentially no support for a nurse staffing – medication error relationship either cross-sectionally or longitudinally. Few hospita...
Cross-sectional study of malocclusion in Spanish children
Almerich Silla, José Manuel; Montiel Company, José María; Bellot Arcís, Carlos; Puertes Fernández, Neus
2014-01-01
Objectives: This study was conducted to determine the orthodontic treatment need of the child population of the Valencia region of Spain, employing the DAI and the IOTN, to examine the relations between treatment need, socio-economic data and gender and to assess the diagnostic agreement between the two indices. Study Design: A cross-sectional descriptive study was conducted in a random representative sample of the schoolchild population of the Valencia region of Spain. The sample size was a ...
Neutron removal cross section as a measure of neutron skin
D. Q. Fang; Y. G. Ma; Cai, X. Z.(Shanghai Institute of Applied Physics, Chinese Academy of Sciences, 201800, Shanghai, China); Tian, W.D.; Wang, H. W.
2010-01-01
We study the relation between neutron removal cross section ($\\sigma_{-N}$) and neutron skin thickness for finite neutron rich nuclei using the statistical abrasion ablation (SAA) model. Different sizes of neutron skin are obtained by adjusting the diffuseness parameter of neutrons in the Fermi distribution. It is demonstrated that there is a good linear correlation between $\\sigma_{-N}$ and the neutron skin thickness for neutron rich nuclei. Further analysis suggests that the relative increa...
Resonance averaged channel radiative neutron capture cross sections
In order to apply Lane amd Lynn's channel capture model in calculations with a realistic optical model potential, we have derived an approximate wave function for the entrance channel in the neutron-nucleus reaction, based on the intermediate interaction model. It is valid in the exterior region as well as the region near the nuclear surface, ans is expressed in terms of the wave function and reactance matrix of the optical model and of the near-resonance parameters. With this formalism the averaged channel radiative neutron capture cross section in the resonance region is written as the sum of three terms. The first two terms correspond to contribution of the optical model real and imaginary parts respectively, and together can be regarded as the radiative capture of the shape elastic wave. The third term is a fluctuation term, corresponding to the radiative capture of the compound elastic wave in the exterior region. On applying this theory in the resonance region, we obtain an expression for the average valence radiative width similar to that of Lane and Mughabghab. We have investigated the magnitude and energy dependence of the three terms as a function of the neutron incident energy. Calculated results for 98Mo and 55Mn show that the averaged channel radiative capture cross section in the giant resonance region of the neutron strength function may account for a considerable fraction of the total (n, γ) cross section; at lower neutron energies a large part of this channel capture arises from the fluctuation term. We have also calculated the partial capture cross section in 98Mo and 55Mn at 2.4 keV and 24 keV, respectively, and compared the 98Mo results with the experimental data. (orig.)
Electron-impact excitation cross sections for neon
An analytic atomic independent particle model adjusted to experimental single-particle energy levels is used to generate wavefunctions for the excited states of neon. Using these wavefunctions in conjunction with the Born approximation and the Russell-Saunders LS-coupling scheme, a calculation is presented of generalized oscillator strengths and cross sections for electron-impact excitation of neon from the 2p6(1S0) ground state. (author)
Inclusive jet cross section in neutral current deep inelastic scattering
The differential inclusive jet cross sections for the reaction ep → e + jet + X have been measured by the ZEUS detector at HERA for Q2 > 125 (500,1000, 2000) GeV2. The sample of analysed events corresponds to an integrated luminosity of 42.5 pb-1. Jets were identified in the laboratory frame using kT cluster algorithm. Jets were required to have axis in the pseudorapidity range -1 T and Q2
Cross-Sectional Serological Survey of Human Fascioliasis in Haiti
Agnamey, P.; Fortes-Lopes, E.; Raccurt, C. P.; Boncy, J.; Totet, A.
2012-01-01
Fasciola hepatica, the aetiological agent of fascioliasis in the Caribbean region, occurs throughout the major islands of the Greater Antilles and in localised zones on two islands (Martinique and Saint Lucia) of the Lesser Antilles. However, apart from Puerto Rico, information regarding human fascioliasis in islands of the Caribbean is out of date or unavailable, or even nonexistent as in Haiti. The authors conducted a retrospective, cross-sectional serological survey in Port-au-Prince using...
Radar cross section (RCS) simulation for wind turbines
Ton, Cuong
2013-01-01
Wind-turbine power provides energy-independence and greenhouse-gas reduction benefits, but if wind turbines are built near military and commercial radar and communication installations, they can cause degradation in the systems performance. The purpose of this research is to study the radar cross section (RCS) of a wind turbine and assess its effect on the performance of radar and communication systems. In this research, some basic scattering characteristics of wind turbines are discussed. Se...
New approaches to the determination of the total cross section
Selyugin, O. V.
2001-01-01
New methods have been developed for extracting the parameters of diffraction scattering amplitude, $\\sigma_{tot}$ and $\\rho=Re F_N/Im F_N$, from experimental data. The latter determines these parameters with less errors and without the knowledge of the normalization coefficient. The impact of additional information from the measurement of the spin-dependence cross section on the determination of the basic characteristic of elastic scattering amplitude is examined. The new form of the connecti...
Theory of neutron resonance cross sections for safety applications
Neutron resonances exert a strong influence on the behaviour of nuclear reactors, especially on their response to the temperature changes accompanying power excursions, and also on the efficiency of shielding materials. The relevant theory of neutron resonance cross sections including the practically important approximations is reviewed, both for the resolved and the unresolved resonance region. Numerical techniques for Doppler broadening of resonances are presented, and the construction of group constants and especially of self-shielding factors for neutronics calculations is outlined. (orig.)
Inclusive parton cross sections in photoproduction and photon structure
Ahmed, T; Andrieu, B; Appuhn, R D; Arpagaus, M; Aïd, S; Babaev, A; Ban, Y; Baranov, P S; Barrelet, E; Bartel, Wulfrin; Barth, Monique; Bassler, U; Beck, H P; Behrend, H J; Belousov, A; Berger, C; Bergstein, H; Bernardi, G; Bernet, R; Bertrand-Coremans, G H; Besançon, M; Beyer, R; Biddulph, P; Bispham, P; Bizot, J C; Blobel, Volker; Borras, K; Botterweck, F; Boudry, V; Braemer, A; Brasse, F W; Braunschweig, W; Brisson, V; Bruncko, Dusan; Brune, C R; Buchholz, R; Buniatian, A Yu; Burke, S; Burton, M; Buschhorn, G W; Bán, J; Bähr, J; Büngener, L; Bürger, J; Büsser, F W; Campbell, A J; Carli, T; Charles, F; Charlet, M; Chernyshov, V; Clarke, D; Clegg, A B; Clerbaux, B; Colombo, M G; Contreras, J G; Cormack, C; Coughlan, J A; Courau, A; Coutures, C; Cozzika, G; Criegee, L; Cussans, D G; Cvach, J; Dagoret, S; Dainton, J B; Dau, W D; Daum, K; David, M; De Wolf, E A; Del Buono, L; Delcourt, B; Di Nezza, P; Dollfus, C; Dowell, John D; Dreis, H B; Droutskoi, A; Duboc, J; Duhm, H; Düllmann, D; Dünger, O; Ebert, J; Ebert, T R; Eckerlin, G; Efremenko, V; Egli, S; Eichenberger, S; Eichler, R; Eisele, Franz; Eisenhandler, Eric F; Ellison, R J; Elsen, E E; Erdmann, M; Erdmann, W; Erlichmann, H; Evrard, E; Favart, L; Fedotov, A; Feeken, D; Felst, R; Feltesse, Joel; Ferencei, J; Ferrarotto, F; Flamm, K; Fleischer, M; Flieser, M; Flügge, G; Fomenko, A; Fominykh, B A; Forbush, M; Formánek, J; Foster, J M; Franke, G; Fretwurst, E; Gabathuler, Erwin; Gabathuler, K; Gamerdinger, K; Garvey, J; Gayler, J; Gebauer, M; Gellrich, A; Genzel, H; Gerhards, R; Goerlach, U; Gogitidze, N; Goldberg, M; Goldner, D; González-Pineiro, B; Gorelov, I V; Goritchev, P A; Grab, C; Greenshaw, T J; Grindhammer, G; Gruber, A; Gruber, C; Grässler, Herbert; Grässler, R; Görlich, L; Haack, J; Haidt, Dieter; Hajduk, L; Hamon, O; Hampel, M; Hanlon, E M; Hapke, M; Haynes, W J; Heatherington, J; Heinzelmann, G; Henderson, R C W; Henschel, H; Herynek, I; Hess, M F; Hildesheim, W; Hill, P; Hiller, K H; Hilton, C D; Hladky, J; Hoeger, K C; Horisberger, R P; Hudgson, V L; Huet, Patrick; Hufnagel, H; Höppner, M; Hütte, M; Ibbotson, M; Itterbeck, H; Jabiol, M A; Jacholkowska, A; Jacobsson, C; Jaffré, M; Janoth, J; Jansen, T; Johnson, D P; Johnson, L; Jung, H; Jönsson, L B; Kalmus, Peter I P; Kant, D; Kaschowitz, R; Kasselmann, P; Kathage, U; Katzy, J M; Kaufmann, H H; Kazarian, S; Kenyon, Ian Richard; Kermiche, S; Keuker, C; Kiesling, C; Klein, M; Kleinwort, C; Knies, G; Ko, W; Kolanoski, H; Kole, F; Kolya, S D; Korbel, V; Korn, M; Kostka, P; Kotelnikov, S K; Krasny, M W; Krehbiel, H; Krämerkämper, T; Krücker, D; Krüger, U P; Krüner-Marquis, U; Kubenka, J P; Kuhlen, M; Kurca, T; Kurzhöfer, J; Kuznik, B; Köhler, T; Köhne, J H; Küster, H; Lacour, D; Lamarche, F; Lander, R; Landon, M P J; Lange, W; Lanius, P; Laporte, J F; Lebedev, A; Leverenz, C; Levonian, S; Ley, C; Lindner, A; Lindström, G; Link, J; Linsel, F; Lipinski, J; List, B; Lobo, G; Loch, P; Lohmander, H; Lomas, J W; Lubimov, V; López, G C; Lüke, D; Magnussen, N; Malinovskii, E I; Mani, S; Maracek, R; Marage, P; Marks, J; Marshall, R; Martens, J; Martin, R D; Martyn, H U; Martyniak, J; Masson, S; Mavroidis, A; Maxfield, S J; McMahon, S J; Mehta, A; Meier, K; Mercer, D; Merz, T; Meyer, C A; Meyer, H; Meyer, J; Migliori, A; Mikocki, S; Milstead, D; Moreau, F; Morris, J V; Mroczko, E; Murín, P; Müller, G; Müller, K; Nagovitsin, V; Nahnhauer, R; Naroska, Beate; Naumann, T; Newman, P R; Newton, D; Neyret, D; Nguyen, H K; Nicholls, T C; Niebergall, F; Niebuhr, C B; Niedzballa, C; Nisius, R; Nowak, G; Noyes, G W; Nyberg-Werther, M; Oakden, M N; Oberlack, H; Obrock, U; Olsson, J E; Ozerov, D; Panaro, E; Panitch, A; Pascaud, C; Patel, G D; Peppel, E; Phillips, J P; Pichler, C; Pieuchot, A; Pitzl, D; Pope, G; Prell, S; Prosi, R; Pérez, E; Rabbertz, K; Raupach, F; Reimer, P; Reinshagen, S; Ribarics, P; Rick, Hartmut; Riech, V; Riedlberger, J; Riess, S; Rietz, M; Rizvi, E; Robertson, S M; Robmann, P; Roloff, H E; Roosen, R; Rosenbauer, K; Rostovtsev, A A; Rouse, F; Royon, C; Rusakov, S V; Rybicki, K; Rylko, R; Rädel, G; Rüter, K; Sahlmann, N; Salesch, S G; Sankey, D P C; Schacht, P; Schiek, S; Schleper, P; Schmidt, C; Schmidt, D; Schmidt, G; Schröder, V; Schuhmann, E; Schwab, B; Schwind, A; Schöning, A; Sefkow, F; Seidel, M; Sell, R; Semenov, A A; Shekelian, V I; Shevyakov, I; Shooshtari, H; Shtarkov, L N; Siegmon, G; Siewert, U; Sirois, Y; Skillicorn, Ian O; Smirnov, P; Smith, J R; Solochenko, V; Soloviev, Yu V; Spiekermann, J; Spielman, S; Spitzer, H; Starosta, R; Steenbock, M; Steffen, P; Steinberg, R; Stella, B; Stephens, K; Stier, J; Stiewe, J; Stolze, K; Strachota, J; Straumann, U; Struczinski, W; Stösslein, U; Sutton, J P; Sánchez, E; Tapprogge, Stefan; Thiebaux, C; Thompson, G; Truöl, P; Turnau, J; Tutas, J; Uelkes, P; Usik, A; Valkár, S; Valkárová, A; Vallée, C; Van Esch, P; Van Mechelen, P; Vartapetian, A H; Vazdik, Ya A; Verrecchia, P; Villet, G; Wacker, K; Wagener, A; Wagener, M; Walker, I W; Walther, A; Weber, G; Weber, M; Wegener, D; Wegner, A; Wellisch, H P; West, L R; Willard, S; Winde, M; Winter, G G; Wittek, C; Wright, A E; Wulff, N; Wünsch, E; Yiou, T P; Zarbock, D; Zhang, Z; Zhokin, A S; Zimmer, M; Zimmermann, W; Zomer, F; Zuber, K; Zácek, J; de Roeck, A; von Schlippe, W
1995-01-01
Photoproduction of 2-jet events is studied with the H1 detector at HERA. Parton cross sections are extracted from the data by an unfolding method using leading order parton-jet correlations of a QCD generator. The gluon distribution in the photon is derived in the fractional momentum range 0.04\\le x_\\gamma \\le 1 at the average factorization scale 75 GeV^2.
Fusion cross sections from Los Alamos R-matrix analyses
We have been using R-matrix theory many years at Los Alamos to describe reactions in light systems, especially those containing fusion reactions. The theory is ideally suited for describing the resonances that are usually seen in light-element reactions, and at the same time it builds in the correct energy dependence of the transition matrix elements at low energies by making explicit use of the solutions for the external parts of the interaction. Thus, the method gives reliable extrapolations to low energies for both neutron- and charged-particle-induced reactions. We will present here the results of analysis that have been done, or are in progress, for reactions in the four- and five-nucleon systems, containing the fusion reactions of major interest: T(d,n)4He, 3He,D(d, p)T, and D(d,n)3He. These analyses contain all possible types of data that have been measured for the two-body reactions of these systems, a method that we have found crucial for determining their true resonant structures, and for ensuring reliable R-matrix interpolations and extrapolations of even the cross-section data. Integrated cross sections will be presented in the form of astrophysical S-functions, as functions of center-of-mass energy, in order that their low energy behavior might be better displayed. In addition to the R-matrix results, we will also show earlier cross-section parametrizations by Duane and Peres that still are used widely within the function reactor community. Some severe shortcomings of these earlier data sets are revealed by comparison with modern measurements and with the R-matrix calculations. More details about these comparisons and useful representations of the R-matrix cross sections and their associated reactivities () recommended for use in fusion reactor design are given in a paper by Bosch and Hale has been submitted for publication
Employee engagement within the NHS: a cross-sectional study
Yadava Bapurao Jeve; Christna Oppenhemier; Justin Konje
2015-01-01
Background Employee engagement is the emotional commitment of the employee towards the organisation. We aimed to analyse baseline work engagement using Utrecht Work Engagement Scale (UWES) at a teaching hospital. Methods We have conducted a cross-sectional study within the National Health Service (NHS) Teaching Hospital in the UK. All participants were working age population from both genders directly employed by the hospital. UWES has three constituting dimensions of work e...
C+C Fusion Cross Sections Measurements for Nuclear Astrophysics
Almaraz-Calderon S.
2015-01-01
Full Text Available Total fusion cross section of carbon isotopes were obtained using the newly developed MUSIC detector. MUSIC is a highly efficient, active target-detector system designed to measure fusion excitation functions with radioactive beams. The present measurements are relevant for understanding x-ray superbursts. The results of the first MUSIC campaign as well as the astrophysical implications are presented in this work.
Stress in medical students: A cross sectional study
Chauhan, Hiteshkumar Muktilal; Shah, Hirendra R; Chauhan, Sumitraben Hiteshkumar; Chaudhary, Sucheta M
2014-01-01
Background & Objectives: Stress occurs when pressure is greater than resources available. Medical education has many factors causing stress among the medical students. This study was conducted to find out the prevalence of stress among medical students and to know the factors causing stress in them.Methods: This is a cross sectional study, conducted on the Ist MBBS to III/IInd MBBS students of B. J. Medical College, Ahmedabad, using a semistructured self administered questionnaire, in Oct...
Measurement of Charmonium Production Cross Section at LHCb
Frosini, M
2010-01-01
The great abundance of charmonium states, collected from the start up of LHC, allows to study its production mechanism. In particular the total and differential $J/\\psi$ production cross section are measured in the transverse momentum range [0;10] GeV/$c$ and in the pseudorapidity range $y \\in$ [2.5;4]. The measurements are performed disentagling the prompt (direct production in $pp$ collisions and feed down from excited charmonium states) and delayed ($b$-hadron decays products) component.
Calculation of light nucleus reaction cross sections in Geant4
Uzhinsky, V.
2012-01-01
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.
Cross section data for production of diagnostic and therapeutic radionuclides
The status of nuclear reaction cross section data for production of medically interesting radionuclides is discussed. The needs for short- and long-term investigations are considered. Whereas short-term investigations refer to improvements in the utilization of known radionuclides, long-term studies pertain to the development of new radionuclides. The major interest is directed to longer-lived β+ emitters and low-range radiation emitting therapeutic radionuclides. Some challenges involved in the relevant nuclear data work are outlined. (author)
Cross sections for low-energy $\\pi^-\\gamma$ reactions
Kaiser, N.(Physik Department T39, Technische Universität München, Garching, D-85747, Germany); Friedrich, J. M.
2008-01-01
We review the cross sections for low-energy $\\pi^- \\gamma$ reactions in the framework of chiral perturbation theory. Charged pion Compton scattering, $\\pi^- \\gamma\\to \\pi^-\\gamma$, is considered up to one-loop order where the pion's internal structure enters through the difference of the electric and magnetic pion polarizability, $\\alpha_\\pi - \\beta_\\pi$. The ongoing COMPASS experiment aims at measuring this important structure constant with high statistics using the Primakoff effect. In the ...
Top quark pair production cross section at the Tevatron
Cortiana, Giorgio; /INFN, Padua /Padua U.
2008-04-01
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.
Nuclear Astrophysics and Neutron Cross Section Measurements Using the ORELA
This is the final report for a research program which has been continuously supported by the AEC, ERDA, or USDOE since 1973. The neutron total and capture cross sections for n + 88Sr have been measured over the neutron energy range 100 eV to 1 MeV. The report briefly summaries our results and the importance of this work for nucleosynthesis and the optical model
Cross-Section of Option Returns and Volatility
Goyal, Amit; Saretto, Alessio
2008-01-01
We study the cross-section of stock option return by constructing decile portfolios of straddles and delta-hedged calls and puts based on sorting stocks on the difference between historical realized volatility and at-the-money implied volatility. We find that a zero-cost trading strategy that is long (short) in the portfolio with a large positive (negative) difference between these two volatility measures produces an economically and statistically significant average monthly return. The resul...
Proton-air and proton-proton cross sections
Ulrich Ralf
2013-01-01
Different attempts to measure hadronic cross sections with cosmic ray data are reviewed. The major results are compared to each other and the differences in the corresponding analyses are discussed. Besides some important differences, it is crucial to see that all analyses are based on the same fundamental relation of longitudinal air shower development to the observed fluctuation of experimental observables. Furthermore, the relation of the measured proton-air to the more fundamental proton-...
Cross sections and kinematics of proton induced fragmentation of carbon
Streibel, T.; Roecher, H.; Huentrup, G.; Heinrich, W. [Siegen Univ. (Germany). Dept. of Physics
1997-09-01
Charge changing fragmentation cross sections for C at a proton energy of about 70 MeV were measured. The discrepancies between measurement and model predictions indicate the necessity of further investigations. We have also measured distributions of fragment emission angles which can be described using a model with a momentum transfer to the fragmenting nucleus. The developed model leads to predictions for momentum distributions of proton induced target fragments of C at small energies. (orig.)
Validation of the Dosimetry Cross Sections by Integral Experiments
Full text: A new version of the dosimetry library IRDFF has been released from the IAEA, featuring more reactions (compared to the older IRDF-2002), an extended energy range to 60 MeV, re-evaluation of several reaction channels with greatly improved covariance information, etc. The aim of the present CRP is the validation of the IRDFF library in order to enhance its reliability for the purposes it serves. Reaction rate measurements in well-defined neutron fields are a common method of validating the cross sections. This technique has been implemented to some extent in the preparation of the IRDFF library from the published data, namely the use of the published average cross sections in the 252Cf spontaneous fission neutron spectrum, thermal cross sections and resonance integrals. There is synergy with the community performing neutron activation analysis by the k0 standardisation technique. To some extent the k0 database has been used for a preliminary validation of the capture reactions in the IRDFF library, but one has to be very careful about the definition of the constants since the interpretation and the derivation of the commonly-used constants is often misleading. The proposed contribution of the Jozef Stefan Institute (JSI) is on the consistent definitions of the constants that allow unique interpretation of the measured reaction rate ratios (particularly for the capture reactions), together with advanced analysis techniques including Monte Carlo simulations of the experiments. The contribution can include the codes that are used at (JSI) for the purpose, namely the GRUPINT code for the analysis of measured reaction rate rations and spectrum unfolding and the RRUNC code for the calculation of the uncertainties in the calculated reaction rates due to the uncertainties in the cross sections and in the neutron spectrum. (author)
The Hadronic Cross-Section in the Resonance Energy Region
Portoles, J.; Ruiz-Femenia, P. D.
2003-01-01
We study the hadronic vacuum polarization in the resonance energy region, using the framework given by the Resonance Effective Theory of QCD. We consider the incorporation of vector-pseudoscalar meson loops that give, inclusively, three and four pseudoscalar meson cuts. After resummation we achieve a QCD-based inclusive parameterization of the correlator, hence of the hadronic cross-section in the energy region populated by resonances.
Antimicrobial therapy in obesity: a multicentre cross-sectional study
Charani, Esmita; Gharbi, Myriam; Frost, Gary; Drumright, Lydia; Holmes, Alison
2015-01-01
Objectives Evidence indicates a relationship between obesity and infection. We assessed the prevalence of obesity in hospitalized patients and evaluated its impact on antimicrobial management. Methods Three National Health Service hospitals in London in 2011–12 were included in a cross-sectional study. Data from all adult admissions units and medical and surgical wards were collected. Patient data were collected from the medication charts and nursing and medical notes. Antimicrobial therapy w...
The physics of neutrino cross sections: theoretical studies
Alvarez-Ruso, Luis
2016-01-01
The present status of neutrino cross section physics is reviewed focusing on the recent theoretical developments in quasielastic scattering, multi-nucleon contributions to the inclusive scattering and pion production on nucleons and nuclei. A good understanding of these processes is crucial to meet the precision needs of neutrino oscillation experiments. Some of the challenges that arise in the consistent description of MiniBooNE and MINERvA recent data are discussed.
Depression among Ethiopian Adults: Cross-Sectional Study
Molla, Getasew Legas; Sebhat, Haregwoin Mulat; Hussen, Zebiba Nasir; Mekonen, Amsalu Belete; Mersha, Wubalem Fekadu; Yimer, Tesfa Mekonen
2016-01-01
Background. Depression is one of the most common mental disorders worldwide and is the second leading cause of disability and major contributor to suicide. Methods. Community based cross-sectional study was conducted among 779 adults residing in Northwest Ethiopia. Multistage cluster sampling technique was used to select study participants. Depression was measured by Patient Health Questionnaire (PHQ-9). Bivariate as well as multivariate logistic regressions were used to identify associated f...
Overview of recent U235 neutron cross section evaluation work
Lubitz, C. [Lockheed Martin Corp., Schenectady, NY (United States)
1998-10-01
This report is an overview (through 1997) of the U235 neutron cross section evaluation work at Oak Ridge National Laboratory (ORNL), AEA Technology (Harwell) and Lockheed Martin Corp.-Schenectady (LMS), which has influenced, or appeared in, ENDF/B-VI through Release 5. The discussion is restricted to the thermal and resolved resonance regions, apart from some questions about the unresolved region which still need investigation. The important role which benchmark testing has played will be touched on.
Neutron Cross-Section Measurements on Structural Materials at ORELA
Neutron capture experiments, using isotopically enriched and natural samples of chromium and titanium, were performed on flight paths 6 and 7 at the 40 m flight station of ORELA. The experimental data were acquired using a pair of deuterated benzene detectors employing the now well-established pulse-height-weighting technique. These data were complemented by new total cross-section measurements where no useful previous data were available.
Inclusive jet cross-section measurement at CDF
Norniella, Olga; /Barcelona, IFAE
2007-05-01
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.
Eating patterns of Turkish adolescents: a cross-sectional survey
Hayran Osman; Vitrinel Ayça; Tektaş Simge; Tilev Sırma; Yıldız Anıl; Tanrıöver Özlem; İzbirak Güldal; Akan Hülya; Akman Mehmet
2010-01-01
Abstract Background Adolescence is a crucial period for development of dietary behaviors that continue into adulthood and influence the risk of chronic diseases later in life. The aim of this study was to determine the eating patterns of adolescents' and their compliance with the Food Guide Pyramid. Methods 625 students, aged between 11-15 years, from an elementary school in Istanbul, Turkey were enrolled in this cross-sectional survey. A questionnaire of eating patterns (QEP) was administere...
Cross Section Fluctuations and Chaoticity in Heavy-Ion Dynamics
Rapisarda, A.
1992-01-01
Cross section fluctuations in nuclear scattering are briefly reviewed in order to show the main important features. Then chaotic scattering is introduced by means of a very simple model. It is shown that chaoticity produces the same kind of irregular fluctuations observed in light heavy--ion collisions. The transition from order to chaos allows a new general framework for a deeper understanding of reaction mechanisms.
Reaction Cross Section in Heavy-Ion Collisions
Wong, Cheuk-Yin
2012-01-01
Previously a compact formula for total reaction cross section for heavy-ion collisions as a function of energy was obtained by treating the angular momentum $l$ as a continuous variable. The accuracy of the continuum approximation is assessed and corrections are evaluated. The accuracy of the compact equation can be improved by a simple modification, if a higher accuracy is required. Simple rules to determine the barrier heights and the penetration probability for the $l$ partial wave from ex...
A global reference for caesarean section rates (C-Model): a multicountry cross-sectional study
Souza, JP; Betran, AP; Dumont, A; de Mucio, B.; Gibbs Pickens, CM; Deneux-Tharaux, C.; Ortiz-Panozo, E; Sullivan, E; Ota, E.; Togoobaatar, G; Carroli, G; Knight, H; Zhang, J.; Cecatti, JG; Vogel, JP
2015-01-01
ObjectiveTo generate a global reference for caesarean section (CS) rates at health facilities. DesignCross-sectional study. SettingHealth facilities from 43 countries. Population/SampleThirty eight thousand three hundred and twenty-four women giving birth from 22 countries for model building and 10045875 women giving birth from 43 countries for model testing. MethodsWe hypothesised that mathematical models could determine the relationship between clinical-obstetric characteristics and CS. The...
Fission cross section uncertainties with the NIFFTE TPC
Sangiorgio, Samuele; Niffte Collaboration
2014-09-01
Nuclear data such as neutron-induced fission cross sections play a fundamental role in nuclear energy and defense applications. In recent years, understanding of these systems has become increasingly dependent upon advanced simulation and modeling, where uncertainties in nuclear data propagate in the expected performances of existing and future systems. It is important therefore that uncertainties in nuclear data are minimized and fully understood. For this reason, the Neutron Induced Fission Fragment Tracking Experiment (NIFFTE) uses a Time Projection Chamber (TPC) to measure energy-differential (n,f) cross sections with unprecedented precision. The presentation will discuss how the capabilities of the NIFFTE TPC allow to directly measures systematic uncertainties in fission cross sections, in particular for what concerns fission-fragment identification, and target and beam uniformity. Preliminary results from recent analysis of 238U/235U and 239Pu/235U data collected with the TPC will be presented. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Neutron Capture Cross Sections for the Weak s Process
Heil, M; Kaeppeler, F; Gallino, R; Pignatari, M; Uberseder, E
2009-01-01
In past decades a lot of progress has been made towards understanding the main s-process component that takes place in thermally pulsing Asymptotic Giant Branch (AGB) stars. During this process about half of the heavy elements, mainly between 90=8Msolar) and is much less understood. A better characterization of the weak s component would help disentangle the various contributions to element production in this region. For this purpose, a series of measurements of neutron-capture cross sections have been performed on medium-mass nuclei at the 3.7-MV Van de Graaff accelerator at FZK using the activation method. Also, neutron captures on abundant light elements with A<56 play an important role for s-process nucleosynthesis, since they act as neutron poisons and affect the stellar neutron balance. New results are presented for the (n,g) cross sections of 41K and 45Sc, and revisions are reported for a number of cross sections based on improved spectroscopic information.