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Topic: Cross section


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In the News (Thu 23 May 19)

  
  Scattering Cross Section
The concept of cross section, as its name suggests, is that of effective area for collision.
The units of cross section are then area units, but for nuclear scattering the effective area is on the order of the cross sectional area of a nucleus.
The cross section in barns for alpha scattering above a selected angle is a standard part of the analysis of Rutherford scattering.
hyperphysics.phy-astr.gsu.edu /hbase/nuclear/crosec.html   (530 words)

  
 PlanetMath: section of a fiber bundle   (Site not responding. Last check: 2007-10-20)
its tangent bundle, a (smooth) section of this bundle is precisely a (smooth) tangent vector field.
The answer is yes, for example, in the case of a trivial vector bundle, but in general it depends on the topology of the spaces involved.
This is version 7 of section of a fiber bundle, born on 2003-02-10, modified 2004-06-19.
planetmath.org /encyclopedia/CrossSection2.html   (349 words)

  
 Cross section   (Site not responding. Last check: 2007-10-20)
In geometry a cross section is the intersection of a body in 3-dimensional space a plane or of a body in space with a line etc. More plainly cutting an object into slices one gets parallel cross sections.
A cross section is a common method depicting the internal arrangement of a 3-dimensional in two dimensions.
Thus for slow neutrons by the (n gamma) reaction the cross in some cases is as much as 000 barns while the cross sections for by gamma-ray absorption are in the neighborhood 0.001 barns.
www.freeglossary.com /Cross_section   (751 words)

  
 Oilfield Glossary: Term 'cross section'
Cross sections are useful for displaying the types and orientations of subsurface structures and formations.
The macroscopic cross section, which is the product of the microscopic cross section and the number of particles per unit volume, has units of inverse length.
Cross sections for most reactions are determined experimentally and depend on the type of interaction, the material and the energy of the incident particle.
www.glossary.oilfield.slb.com /Display.cfm?Term=cross+section   (149 words)

  
 Section Method   (Site not responding. Last check: 2007-10-20)
In the physical sciences, the term cross section is used to describe a slice perpendicular to an axis of an object.
For a solid whose cross sections are the same shape and size, the volume of the solid is computed as the product of the area of the cross section times the height of the object.
The volume of a general cylinder is the area of the cross section S that is translated times the distance through which the cross section is translated.
astro.temple.edu /~dhill001/sectionmethod/sectionmethod.html   (883 words)

  
 Normal pinyon pine needle - cross section   (Site not responding. Last check: 2007-10-20)
Cross section of a normal pinyon pine (Pinus edulis needle.
Round galls and normal needles of the same age were fixed and prepared for sectioning according to the procedures of Sass (1958).
After sectioning at 25 um, the material was stained with 1% saffranin-O for 30 min then dehydrated in 95% ethanol and stained with 0.6% acid fast green for 30 sec.
www.wcrl.ars.usda.gov /cec/lab/needle.htm   (78 words)

  
 crosssection
The concept of cross section is the crucial key that opens the communication between the real world of experiment and the abstract, idealized world of theoretical models.
The cross section is the probability that an interaction will occur between a projectile particle-say, a proton that has been accelerated in the Tevatron-and a target particle, which could be an antiproton, or perhaps a proton or neutron in a piece of metal foil.
The cross section for large-angle scattering is the fraction of alpha particles that bounce back from the target, divided by the density of nuclei in the target and the target thickness.
www-ed.fnal.gov /painless/htmls/cross.html   (594 words)

  
 Oil and Gas Research
Southwest-northeast cross section in the Illinois Basin: southeastern flank of Ozark Dome, Missouri, to southern Illinois.
West-east cross section in the Illinois Basin: Ozark Dome, Missouri, to Rough Creek Graben, western Kentucky.1992.
Structural cross section of the Paleozoic rocks in Illinois, Wayne County to Stephenson County.
www.isgs.uiuc.edu /oilgas/crossect.html   (421 words)

  
 Cross
The microscopic cross section may also be regarded as the effective area the nucleus presents to the neutron for the particular reaction.
The macroscopic cross section is the probability of a given reaction occurring per unit travel of the neutron.
This region is frequently referred to as the "1/v region," because the absorption cross section is proportional to 1/v, which is the reciprocal of neutron velocity.
www.tpub.com /doenuclearphys/nuclearphysics39.htm   (1107 words)

  
 § 14. cross section. 2. Style. The American Heritage Book of English Usage. 1996
Informally, we speak of a cross section of a population even if the group chosen is not statistically representative of the population as a whole.
Thus you might say You meet a cross section of Americans when you travel by interstate bus, even though it is clear that some types of Americans are likely to be underrepresented among the people who ride interstate buses.
When cross section is used in reference to the samples used in surveys and other investigations, the presumption is usually that the group has been chosen so as to be representative of the larger population, and here you must be more careful.
www.bartleby.com /64/C002/014.html   (190 words)

  
 Cross section   (Site not responding. Last check: 2007-10-20)
In geometry, a cross section is the intersection of a body in 3-dimensional space with aplane, or of a body in 2-dimensional space with a line, etc. More plainly, when cutting an object into slices one gets manyparallel cross sections.
In nuclear physics, it is found convenient to express probabilityof a particular event by a cross section.
Thus for slow neutrons absorbed by the (n,gamma) reaction the cross section in some cases is as much as 1,000 barns, while the cross sections for transmutations bygamma-ray absorption are in the neighborhood of 0.001 barns.
www.therfcc.org /cross-section-30089.html   (436 words)

  
 Physics Help and Math Help - Physics Forums - View Single Post - Absorption Cross Section
The cross section is conceptually the area a nucleus presents to a target, having units of length squared.
The cross section (sigma) is usually referred to as a microscopic cross section as it is independent of material properties.
The macroscopic cross section (capital sigma or sometimes mu) is the product of the number density A (units of m^-3) and the microscopic cross section (units of m^2) giving units of inverse length (m^-1).
www.physicsforums.com /showpost.php?p=148068&postcount=2   (255 words)

  
 Definition: radar cross section   (Site not responding. Last check: 2007-10-20)
radar cross section: An expression of the extent to which an object, i.e., a target, reflects radar pulses, usually with respect to their point of origin.
Note: The radar cross section of an aircraft can vary by a factor of over 100, depending on the aspect angle of the aircraft to the radar transmitter.
Radar reflection off the nose of the aircraft usually represents the smallest radar cross section, while a broadside presentation to the signal produces the greatest cross section.
www.atis.org /tg2k/_radar_cross_section.html   (114 words)

  
 Definition of Scattering Cross Section
A cross section depends on the types of particles involved and usually depends on the energy of the particles in the beam.
In general, the cross section is the effective area of the collision region.
This equation reproduces the correct result for the cross section in the classical case where B and T are balls and defines the cross section for the general situation.
www.jupiterscientific.org /sciinfo/crosssection.html   (946 words)

  
 Structural Cross Sections of Paleozoic Rocks in the Illinois Basin   (Site not responding. Last check: 2007-10-20)
Most of the sections radiate from the UNOCAL 1 Cisne drill hole in Wayne County, Illinois, near the approximate center of the basin.
The cross section will also be useful to anyone exploring for oil or gas accumulations in the area.
Cross section in preparation by Martin C. Noger and James A. Drahovzal at the Kentucky Geological Survey:
www.uky.edu /KGS/emsweb/xsection/ilbxsect.html   (271 words)

  
 Neutron Capture and Cross   (Site not responding. Last check: 2007-10-20)
When the capture cross section is less than the geometric cross section, the neutron is less likely to be captured than to make contact.
The cross section for neutrino capture (which is even less likely) would be smaller.
Tim Mooney ======================================================== The concept of a "cross section" is somewhat of a mis-nomer.
www.newton.dep.anl.gov /askasci/phy00/phy00464.htm   (369 words)

  
 First CDF Measurement of the Inclusive Jet Cross Section in Run II   (Site not responding. Last check: 2007-10-20)
The first preliminary measurement of the inclusive jet cross section is shown compared to the NLO QCD expectation determined using the CTEQ 6.1 parameterization of the parton density functions.
The variation in the cross section due to the 5% energy scale uncertainty is shown as the band.
The error on the cross section ratio resulting from the 5% energy scale uncertainty is shown as the band.
ncdf76.fnal.gov /%7Echlebana/qcd/ana/incJet/bless   (617 words)

  
 Absorption Cross Section
The numerical value of the cross section depends upon the properties of the interacting projectile and target, the strength of the forces they can exert on each other, and the velocity of the projectile (wavelength if the particle is a photon).
The cross section will, in turn, depend upon the wavelength of the photons, perhaps upon their polarization, and upon the kind and state of the target atom or molecule.
The cross section you have determined is the cross section for absorbing light of wavelength 632.8 nm by copper ions dissolved in water.
www4.ncsu.edu /~mowat/H&M_WebSite/Absorption/CrossSection.html   (998 words)

  
 The Golden Section and The human body
The Golden Section, also known as Phi, is manifested in the structure of the human body.
The head forms a golden rectangle with the eyes at its midpoint.The mouth and nose are each placed at golden sections of the distance between the eyes and the bottom of the chin.Phi defines the dimensions of the human profile.
The sectioned portions of the magenta line determine the position of the nose and the hairline.
milan.milanovic.org /math/english/golden/golden2.html   (561 words)

  
 Cross Section Of A Trenc - BigWalk.co.uk   (Site not responding. Last check: 2007-10-20)
From just the basics to finding out information about cross section of a trenc, the team has set up the directory so that you could quickly seek the information you might desire from our extensive range of cross section of a trenc web pages.
On the offchance you were looking for text about cross section of a trenc, the team that built BIGWalk have set up the system that allows you to rapidly look for what you may need from our extensive list of cross section of a trenc pages.
Amicus's section for workers in the voluntary and non-profit sector.
www.bigwalk.co.uk /directory/_cross_section_of_a_trench   (503 words)

  
 Measurement of the Top Quark Cross Section
Cross sections are discussed in terms of the area of overlap of the interacting fields of the particles in proximity of each other.
Current theory allows prediction of the cross section in terms of the top quark's mass, which is not predicted and must be measured as well.
Studies of the top quark will be a "top" priority, and with our cross section measurement in hand we can now reliably estimate that we will have tens of times more statistics in our data sample enabling precision study of this heavyweight member of the quark family.
www-d0.fnal.gov /public/pubs/topxsec_prl_sum.html   (1018 words)

  
 Hypercube Vertex First Sections   (Site not responding. Last check: 2007-10-20)
To understand the images below, it may be helpful to visualize a series of cross sections produced by bisecting a cube with a plane perpendicular to the diagonal of the cube.
The first cross section (not shown here, see animation) is a point or the first vertex of the hypercube.
From here, the cross sections repeat the first half of the series, except that they are reversed from there conterparts.
users.adelphia.net /~eswab/hcubsect.htm   (598 words)

  
 How do I annotate the horizontal axis within a cross-section? - applies to: RockWorks2004 RockWorks2002 RockWorks99 ...
During the construction of a cross section within RockWorks, you have the option of adding vertical scale bars and/or reference lines.
With the cross section displayed on the screen in a RockPlot window, choose the Annotate command from the Utilities menu.
If, in the Create Cross Section window, you have set a vertical exaggeration to a number other than "1", then the horizontal distance units will not be correctly represented.
www.rockware.com /support/questions/annotate_horizontal_surface_in_crosssection.html   (373 words)

  
 FindLaw for Legal Professionals - Case Law, Federal and State Resources, Forms, and Code
But Taylor's claim is that he was constitutionally entitled to a jury drawn from a venire constituting a fair cross section of the community and that the jury that tried him was not such a jury by reason of the exclusion of women.
The Sixth Amendment requirement of a fair cross section on the venire is a means of assuring, not a representative jury (which the Constitution does not demand), but an impartial one (which it does).
If the goal of the Sixth Amendment is representation of a fair cross section of the community on the petit jury, then intentionally using peremptory challenges to exclude any identifiable group should be impermissible - which would, as we said in Lockhart, "likely require the elimination of peremptory challenges." 476 U.S., at 178.
caselaw.lp.findlaw.com /cgi-bin/getcase.pl?navby=volpage&court=us&vol=493&page=479   (13978 words)

  
 Geologic cross sections   (Site not responding. Last check: 2007-10-20)
These diagrams present key elements of Minnesota's geology in the form of simplified cross sections that extend from the north-central to the southeastern part of the state.
Section C: Bedrock units showing subdivisions based on both age and geologic characteristics; for example, different types of rocks that formed or were altered during a regional event in the geologic history are grouped together.
On the left (north) side of the cross sections are various Archean (about 2.7 billion years old) rock units.
www.geo.umn.edu /mgs/xsections/sect.html   (535 words)

  
 J/Psi Preprints
We calculate the cross section for q(\bar q)g-production in diffractive DIS with finite fermion masses and zero momentum transfer.
The dipole cross section calculated with the unintegrated gluon density of the nucleon substantially differs from the well-known perturbative form $\sigma_{dip} \sim b^2$ for $b > 0.3$fm, where $b$ is the transverse separation of the dipole.
We evaluate the cross sections for the dissociation of J/psi and Upsilon in collision with pion as a function of the temperature of the hadron medium, using the quark-interchange model of Barnes and Swanson.
www.slac.stanford.edu /exp/e160/jpsi_refs.html   (11737 words)

  
 The Fibonacci Numbers and Golden section in Nature - 1
The outer crossing point will be about 1.6 times as far from the centre as the next inner point on the line where the shell crosses it.
She also has published several posters, including one on the golden section suitable for a classroom or your study room wall.
There is a wonderful section on equations of pretty curves, some simple, some not so simple, that are a challenge to draw even if we do use spreadsheets to plot them now.
www.mcs.surrey.ac.uk /Personal/R.Knott/Fibonacci/fibnat.html   (6623 words)

  
 Introductory Biology: Lab 9 for 71.125 - Shoot, Stem and Secondary Growth
In sectional view the very young leaves appear to be long and narrow but they soon develop, on a miniature scale the characteristic shape of the mature leaves.
Examine an internodal cross section of a typical dicot stem (Helianthus)
Examine an internodal cross section of a typical monocot stem (Zea)
www.umanitoba.ca /Biology/lab9/biolab9_4.html   (702 words)

  
 Basic Histology -- Smooth Muscle, Cross Section   (Site not responding. Last check: 2007-10-20)
When smooth muscle is cut in cross section, you will see the smooth muscle cell nuclei as round purple-staining masses within pink-staining fibers.
Spotting blood vessels is easy when smooth muscle is cut in cross section.
This is smooth muscle, cut in cross section.
www.pathguy.com /histo/057.htm   (75 words)

  
 III.6 Calculation of beam cross sections
The calculation of beam cross section properties for complex geometrical shapes requires the resolution of equations with partial derivatives.
The calculation of beam cross-section properties is explained in section III.6.2.
The definition of the class is given in the header file ``beamSection.h'' (section III.6.1).
users.skynet.be /keyFE2/manual/III_6_Calculation_beam_cros.html   (127 words)

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