Neutron - Revision history

KevinYager: /* Wavelength */

2015-01-26T20:03:47Z

‎Wavelength

KevinYager at 18:56, 16 December 2014

2014-12-16T18:56:56Z

KevinYager at 17:47, 4 December 2014

2014-12-04T17:47:33Z

KevinYager: /* See Also */

2014-12-04T17:35:32Z

‎See Also

KevinYager at 17:34, 4 December 2014

2014-12-04T17:34:20Z

KevinYager: Created page with "'''Neutrons''' are subatomic particles with no electric charge. Along with protons, they form the nuclei of atoms. Like all particles, neutrons behave as waves..."

2014-12-04T17:05:29Z

Created page with "'''Neutrons''' are subatomic particles with no electric charge. Along with protons, they form the nuclei of atoms. Like all particles, neutrons behave as waves..."

New page

'''Neutrons''' are subatomic particles with no electric charge. Along with protons, they form the nuclei of atoms. Like all particles, neutrons behave as [[wave packet|waves]]; thus beams of neutrons can be used for [[scattering]] experiments (e.g. [[SANS]]).

[[X-rays]] interact predominantly through a material's electrons (one can imagine the oscillating E-field of the incident x-ray photons driving oscillations in the electron clouds). Thus, x-ray scattering probes the realspace electron-density distribution. Neutrons, on the other hand, do not interact with charges. Instead, neutrons The interaction between a neutron and matter is regulated by

==Generating Neutron Beams==
TBD

==See Also==
* [[http://en.wikipedia.org/wiki/Neutron|Wikipedia: Neutron]]

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 </math>
 where ''k'' is Boltzmann's constant (1.3806488×10<sup>−23</sup> m<sup>2</sup> kg s<sup>−2</sup> K<sup>−1</sup>)
 ==See Also==
 * [http://en.wikipedia.org/wiki/Neutron Wikipedia: Neutron]
 * [http://www.ill.eu/quick-links/publications/ Neutron data booklet]: Tabulates fundamental properties of neutron interactions with matter; also provides useful equations.

@@ Line 1: / Line 1: @@
 '''Neutrons''' are subatomic particles with no electric charge. Along with protons, they form the nuclei of atoms. Like all particles, neutrons behave as [[wave packet|waves]]; thus beams of neutrons can be used for [[scattering]] experiments (e.g. [[SANS]]). In fact, there are neutron analogues of most light or x-ray methods (including [[diffraction]], [[reflectivity]], [[inelastic scattering]], etc.). The unique properties of neutrons also make possible some methods not possible with other probes (e.g. [[neutron spin echo]]).
-[[X-rays]] interact predominantly through a material's electrons (one can imagine the oscillating E-field of the incident x-ray photons driving oscillations in the electron clouds). Thus, x-ray scattering probes the realspace electron-density distribution. Neutrons, on the other hand, do not interact with charges. Instead, neutrons interact with atomic nuclei (with the [[Origin_of_neutron_scattering_lengths|potential-well]] defined by the nuclear energy states). The neutron scattering power of each element is given by the [[neutron scattering lengths]]. The scattering power for a given material is then given by the [[Scattering Length Density]] (SLD), which accounts for the atoms present, as well as their volume-density.
+[[X-rays]] interact predominantly through a material's electrons (one can imagine the oscillating E-field of the incident x-ray photons driving oscillations in the electron clouds). Thus, x-ray scattering probes the [[realspace]] [[electron-density distribution]]. Neutrons, on the other hand, do not interact with charges. Instead, neutrons interact with atomic nuclei (with the [[Origin_of_neutron_scattering_lengths|potential-well]] defined by the nuclear energy states). The neutron scattering power of each element is given by the [[neutron scattering lengths]]. The scattering power for a given material is then given by the [[Scattering Length Density]] (SLD), which accounts for the atoms present, as well as their volume-density.
 [[Image:Output-elements.png|500px|thumb|right|Neutron scattering lengths as a function of element.]]

@@ Line 1: / Line 1: @@
 '''Neutrons''' are subatomic particles with no electric charge. Along with protons, they form the nuclei of atoms. Like all particles, neutrons behave as [[wave packet|waves]]; thus beams of neutrons can be used for [[scattering]] experiments (e.g. [[SANS]]). In fact, there are neutron analogues of most light or x-ray methods (including [[diffraction]], [[reflectivity]], [[inelastic scattering]], etc.). The unique properties of neutrons also make possible some methods not possible with other probes (e.g. [[neutron spin echo]]).
-[[X-rays]] interact predominantly through a material's electrons (one can imagine the oscillating E-field of the incident x-ray photons driving oscillations in the electron clouds). Thus, x-ray scattering probes the realspace electron-density distribution. Neutrons, on the other hand, do not interact with charges. Instead, neutrons interact with atomic nuclei (with the [[Origin_of_neutron_scattering_lengths|potential-well]] defined by the nuclear energy states). The neutron scattering power of each element is given by the [[neutron scattering lengths]]. The scattering power for a given material is then given by the [[scattering length density]] (SLD), which accounts for the atoms present, as well as their volume-density.
+[[X-rays]] interact predominantly through a material's electrons (one can imagine the oscillating E-field of the incident x-ray photons driving oscillations in the electron clouds). Thus, x-ray scattering probes the realspace electron-density distribution. Neutrons, on the other hand, do not interact with charges. Instead, neutrons interact with atomic nuclei (with the [[Origin_of_neutron_scattering_lengths|potential-well]] defined by the nuclear energy states). The neutron scattering power of each element is given by the [[neutron scattering lengths]]. The scattering power for a given material is then given by the [[Scattering Length Density]] (SLD), which accounts for the atoms present, as well as their volume-density.
 [[Image:Output-elements.png|500px|thumb|right|Neutron scattering lengths as a function of element.]]
@@ Line 11: / Line 11: @@
 * '''Reactor source''': A nuclear reactor can be used as a neutron source. Small ports ('holes') in the reactor's shield-wall allow neutrons to escape, which are then directed, using neutron-shielded guides, towards different experimental endstations. The wavelengths of the exiting neutrons are dictated by their velocities; i.e. their temperature. The thermal spectrum can be tuned by using a 'moderator' with which the neutrons collide, bringing them to a desired temperature. A monochromator can be used to select a particular neutron wavelength (e.g. a diffraction crystal, or a velocity-selector). One thus obtains a neutron-beam that can be used for various experiments. Research reactors need not be particularly large (<100 MW); they are much smaller than power-plant reactors (~1,000 MW).
 * '''Spallation source''': A particle accelerator can also be used to generate neutrons. For instance, at SNS, a ~1 GeV proton beam is fired at a liquid mercury target (60 Hz). The proton-nuclear collisions release neutrons across a broad range of energies. Instead of using a monochromator, spallation sources typically exploit the fact that the neutrons arrive in pulses (owing to the original pulsed proton source). In particular, they use 'time-of-flight' detection, where the wavelength of any detected neutron is inferred based on its arrival time. Thus the wavelength spread is used to provide an inherent and measurable spread in the data (e.g. in a TOF SANS instrument, the scattering from a single pulse yields data across a range of ''[[q]]''-values).
 ==See Also==
 * [http://en.wikipedia.org/wiki/Neutron Wikipedia: Neutron]
 * [http://www.ill.eu/quick-links/publications/ Neutron data booklet]: Tabulates fundamental properties of neutron interactions with matter; also provides useful equations.

@@ Line 13: / Line 13: @@
 ==See Also==
-* [http://en.wikipedia.org/wiki/Neutron|Wikipedia: Neutron]
+* [http://en.wikipedia.org/wiki/Neutron Wikipedia: Neutron]
 * [http://www.ill.eu/quick-links/publications/ Neutron data booklet]: Tabulates fundamental properties of neutron interactions with matter; also provides useful equations.