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Nuclear Cross Section
Nuclear Cross Section
Published: 2014/04/14
Channel: AK LECTURES
Nuclear Cross Section & Specific Activity of Radioactive Substance
Nuclear Cross Section & Specific Activity of Radioactive Substance
Published: 2017/03/21
Channel: Priyanka Jain
Cross Section
Cross Section
Published: 2013/05/17
Channel: Jefferson Lab
Mod-01 Lec-30 Nuclear Reactions
Mod-01 Lec-30 Nuclear Reactions
Published: 2014/03/25
Channel: nptelhrd
Microscopic Cross Section Lesson
Microscopic Cross Section Lesson
Published: 2014/03/03
Channel: STS Defence
Cross section (physics)
Cross section (physics)
Published: 2016/01/22
Channel: WikiAudio
Nuclear Chemistry Geometric Cross Section
Nuclear Chemistry Geometric Cross Section
Published: 2017/12/13
Channel: Ajay Singh Guleria
DOE CSGF 2014: Cross Section Spatial Discretization for Nuclear Engineering Calculations
DOE CSGF 2014: Cross Section Spatial Discretization for Nuclear Engineering Calculations
Published: 2014/08/13
Channel: Krell Institute
KCNRP | Session 2 – Interaction of Neutrons with Matter
KCNRP | Session 2 – Interaction of Neutrons with Matter
Published: 2015/09/17
Channel: Nuclear and Plasma Sciences Society AlexSC
19: Scattering cross section
19: Scattering cross section
Published: 2012/11/14
Channel: NTNU openVideo
The collision cross-section explained
The collision cross-section explained
Published: 2013/03/08
Channel: Oxford Academic (Oxford University Press)
Fission cross section for fast neutrons inside JSI TRIGA Mark II reactor
Fission cross section for fast neutrons inside JSI TRIGA Mark II reactor
Published: 2013/11/05
Channel: triga JSI
JSI TRIGA Reactor - Fast neutron cross-section
JSI TRIGA Reactor - Fast neutron cross-section
Published: 2013/06/04
Channel: triga JSI
Lesson34: Neutron Capture
Lesson34: Neutron Capture
Published: 2013/04/22
Channel: Steve Spicklemire
Particle Physics – Probability and cross section
Particle Physics – Probability and cross section
Published: 2017/11/13
Channel: intrigano
Collision Cross Section Measurements for Food & Environmental Analysis
Collision Cross Section Measurements for Food & Environmental Analysis
Published: 2015/12/03
Channel: Waters Corporation
Cross section Meaning
Cross section Meaning
Published: 2015/04/18
Channel: SDictionary
What Do You Mean By Cross Section In Physics?
What Do You Mean By Cross Section In Physics?
Published: 2017/09/29
Channel: Ask Question II
Ad Fig. 15 9b Differential cross section for resonance scattering
Ad Fig. 15 9b Differential cross section for resonance scattering
Published: 2014/07/28
Channel: Picture Book of Quantum Mechanics
Mod-01 Lec-14 Scattering of nucleons
Mod-01 Lec-14 Scattering of nucleons
Published: 2014/03/25
Channel: nptelhrd
Nuclear Scattering & Spin
Nuclear Scattering & Spin
Published: 2014/07/25
Channel: DrPhysicsA
Nuclear Fission and Neutron Induced Fission Cross Sections A Nuclear Energy Agency Nuclear Data Comm
Nuclear Fission and Neutron Induced Fission Cross Sections A Nuclear Energy Agency Nuclear Data Comm
Published: 2016/10/20
Channel: McTeodor
Particle Physics – Rutherford cross section
Particle Physics – Rutherford cross section
Published: 2017/11/13
Channel: intrigano
Area of Cross Section
Area of Cross Section
Published: 2016/08/12
Channel: DeltaStep
Measuring the Neutrino Cross Section with Earth Absorption
Measuring the Neutrino Cross Section with Earth Absorption
Published: 2017/11/22
Channel: IceCube Neutrino Observatory
7 2 Definition of Cross Section
7 2 Definition of Cross Section
Published: 2015/03/13
Channel: ThePhysicsToday
Fission cross section for thermal neutrons inside JSI TRIGA Mark II reactor
Fission cross section for thermal neutrons inside JSI TRIGA Mark II reactor
Published: 2013/11/05
Channel: triga JSI
PHYS3740 Lecture21-1 Rutherford Cross-Section
PHYS3740 Lecture21-1 Rutherford Cross-Section
Published: 2010/10/19
Channel: jmgerton
Cross section of a fruit fly embryo
Cross section of a fruit fly embryo
Published: 2012/02/16
Channel: reeveslab
UNM Phys 531 2011   Lec23   Saturation, photon scattering, cross sections
UNM Phys 531 2011 Lec23 Saturation, photon scattering, cross sections
Published: 2016/04/19
Channel: CosmoLearning
Extinction, Absorption and Scattering Cross Section using CST Studio
Extinction, Absorption and Scattering Cross Section using CST Studio
Published: 2017/02/16
Channel: ParsOptics Group
JSI TRIGA Reactor - Thermal neutron cross section
JSI TRIGA Reactor - Thermal neutron cross section
Published: 2013/06/04
Channel: triga JSI
第10講 Neutron Attenuation (A)
第10講 Neutron Attenuation (A)
Published: 2013/01/11
Channel: NTHUOCW
Neutron Cross Section Curves Neutron Cross Sections Series Volume 2 v  2
Neutron Cross Section Curves Neutron Cross Sections Series Volume 2 v 2
Published: 2016/10/11
Channel: Mrs. Almaș
20: Scattering cross section - Part 2
20: Scattering cross section - Part 2
Published: 2012/11/14
Channel: NTNU openVideo
Lateral and cross section nuclear cycles of a Drosophila embryo
Lateral and cross section nuclear cycles of a Drosophila embryo
Published: 2017/05/22
Channel: reeveslab
Fission cross section for epithemral neutrons inside JSI TRIGA Mark II reactor
Fission cross section for epithemral neutrons inside JSI TRIGA Mark II reactor
Published: 2013/11/05
Channel: triga JSI
Cross Sections
Cross Sections
Published: 2013/04/13
Channel: MathMeij
Lecture 24  Nuclear Reactions, Compound Nuclear Reactions, Direct Reactions
Lecture 24 Nuclear Reactions, Compound Nuclear Reactions, Direct Reactions
Published: 2015/03/05
Channel: ThePhysicsToday
Total Cross Sections for Reactions of High Energy Particles Including Elastic Topological Inclusive
Total Cross Sections for Reactions of High Energy Particles Including Elastic Topological Inclusive
Published: 2016/10/08
Channel: Iuliana Silva
The Uranium 235 Chain Reaction*Physics Made Fun
The Uranium 235 Chain Reaction*Physics Made Fun
Published: 2016/03/25
Channel: *29 INDIAN MILITARY INTELLIGENCE 29*
Cross section of a fruit fly embryo
Cross section of a fruit fly embryo
Published: 2011/01/29
Channel: thedu01
Barn (unit)
Barn (unit)
Published: 2014/11/04
Channel: Audiopedia
Neutron diffusion in a nuclear reactor
Neutron diffusion in a nuclear reactor
Published: 2017/02/16
Channel: Jan Leen Kloosterman
What Are The Control Rods In A Nuclear Reactor Made Of?
What Are The Control Rods In A Nuclear Reactor Made Of?
Published: 2017/08/23
Channel: Obu Obu
Aneutronic Nuclear Fusion Reactor + Engine Proposal
Aneutronic Nuclear Fusion Reactor + Engine Proposal
Published: 2013/05/31
Channel: Muon Ray
第01講 Introduction to Nuclear Safety (A)
第01講 Introduction to Nuclear Safety (A)
Published: 2013/04/08
Channel: NTHUOCW
3h57m40s21f Nuclear Cross-Sections - Big Dots and Small Dots - TR2016a
3h57m40s21f Nuclear Cross-Sections - Big Dots and Small Dots - TR2016a
Published: 2017/05/13
Channel: Thorium Remix
4h24m46s17f Xenon Most Common Fission Product - Absorbs Neutrons - Kills Fission - TR2016a
4h24m46s17f Xenon Most Common Fission Product - Absorbs Neutrons - Kills Fission - TR2016a
Published: 2017/05/14
Channel: Thorium Remix
第24講 Two-Group Calculation of Neutron Moderation (B)
第24講 Two-Group Calculation of Neutron Moderation (B)
Published: 2013/01/11
Channel: NTHUOCW
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WIKIPEDIA ARTICLE

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The nuclear cross section of a nucleus is used to characterize the probability that a nuclear reaction will occur. The concept of a nuclear cross section can be quantified physically in terms of "characteristic area" where a larger area means a larger probability of interaction. The standard unit for measuring a nuclear cross section (denoted as σ) is the barn, which is equal to 10−28 m² or 10−24 cm². Cross sections can be measured for all possible interaction processes together, in which case they are called total cross sections, or for specific processes, distinguishing elastic scattering and inelastic scattering; of the latter, amongst neutron cross sections the absorption cross sections are of particular interest.

In nuclear physics it is conventional to consider the impinging particles as point particles having negligible diameter. Cross sections can be computed for any sort of process, such as capture scattering, production of neutrons, etc. In many cases, the number of particles emitted or scattered in nuclear processes is not measured directly; one merely measures the attenuation produced in a parallel beam of incident particles by the interposition of a known thickness of a particular material. The cross section obtained in this way is called the total cross section and is usually denoted by a σ or σT.

Typical nuclear radii are of the order 10−14 m. Assuming spherical shape, we therefore expect the cross sections for nuclear reactions to be of the order of πr ² or 10−28 m² (i.e. 1 barn). Observed cross sections vary enormously - for example, slow neutrons absorbed by the (n, ) reaction show a cross section much higher than 1,000 barns in some cases (boron-10, cadmium-113, and xenon-135), while the cross sections for transmutations by gamma-ray absorption are in the region of 0.001 barn.

Macroscopic cross section[edit]

Nuclear cross sections are used in determining the nuclear reaction rate, and are governed by the reaction rate equation for a particular set of particles (usually viewed as a "beam and target" thought experiment where one particle or nucleus is the "target" [typically at rest] and the other is treated as a "beam" [projectile with a given energy]).

For neutron interactions incident upon a thin sheet of material (ideally made of a single type of isotope), the nuclear reaction rate equation is written as:

where:

  •  : number of reactions of type x, units: [1/time/volume]
  •  : beam flux, units: [1/area/time]
  •  : microscopic cross section for reaction , units: [area] (usually barns or cm2).
  •  : density of atoms in the target in units of [1/volume]
  • : macroscopic cross-section [1/length]

Types of reactions frequently encountered are s: scattering, : radiative capture, a: absorption (radiative capture belongs to this type), f: fission, the corresponding notation for cross-sections being: , , , etc. A special case is the total cross-section , which gives the probability of a neutron to undergo any sort of reaction ().

Formally, the equation above defines the macroscopic neutron cross-section (for reaction x) as the proportionality constant between a neutron flux incident on a (thin) piece of material and the number of reactions that occur (per unit volume) in that material. The distinction between macroscopic and microscopic cross-section is that the former is a property of a specific lump of material (with its density), while the latter is an intrinsic property of a type of nuclei.

See also[edit]

References[edit]

  • Nuclear Reactor Analysis by James J. Duderstadt and Louis J. Hamilton - Published by John Wiley & Sons, Inc.
  • Perkins, Donald H. (1999). Introduction to High Energy Physics. Cambridge University Press. ISBN 0-521-62196-8. 
  • Mubarakmand, Samar; Masud Ahmad; M. Anwar; M.S. Chaudhry (1977). "Cross-section measurements with a neutron generator". The Nucleus. Nilore, Islamabad: PINSTECH. 42 (1-2): 115–185. 

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