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Topic: Neutron


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In the News (Fri 17 Nov 17)

  
  Neutron - Wikipedia, the free encyclopedia
Although the neutron has zero net charge, it may interact electromagnetically in two ways: first, the neutron has a magnetic moment of the same order as the proton; second, it is composed of electrically charged quarks.
Neutrons that elastically scatter off atoms can create an ionization track that is detectable, but the experiments are not as simple to carry out; other means for detecting neutrons, consisting of allowing them to interact with atomic nuclei, are more commonly used.
One use of neutron emitters is the detection of light nuclei, particularly the hydrogen found in water molecules.
en.wikipedia.org /wiki/Neutron   (1262 words)

  
 Neutron - MSN Encarta
Neutron, electrically neutral elementary particle that is part of the nucleus of the atom.
The neutron is also affected by the weak nuclear force, an interaction among the building blocks of the neutron that causes the neutron to decay, or break apart.
The neutrons are responsible for the remaining mass of the atom.
encarta.msn.com /encyclopedia_761565664/Neutron.html   (1492 words)

  
 [No title]   (Site not responding. Last check: 2007-10-22)
Outside the nucleus, neutrons are unstable and have a half-life of about 15 minutes, decaying by emitting an electron and antineutrino to become a proton.
Although atoms in their normal state are also uncharged, they are ten thousand times larger than a neutron and consist of a complex system of negatively charged electrons widely spaced around a positively charged nucleus.
The neutron, however, is unaffected by such forces; it is affected only by the very short-range strong nuclear force which comes into play when the neutron comes very close indeed to an atomic nucleus.
wikiwhat.com /encyclopedia/n/ne/neutron.html   (785 words)

  
 AllRefer.com - neutron (Physics) - Encyclopedia
The electron-scattering experiments of Robert Hofstadter indicate that the neutron, like the proton, is surrounded by a cloud of pions; protons and neutrons are bound together in nuclei by the exchange of virtual pions.
The neutron and the proton are regarded by physicists as two aspects or states of a single entity, the nucleon.
The field of neutron optics is concerned with such topics as the diffraction and polarization of beams of neutrons.
reference.allrefer.com /encyclopedia/N/neutron.html   (356 words)

  
 [No title]
The neutron is a powerful tool for the study of condensed matter (solids and liquids) in the world around us, having significant advantages over other forms of radiation in the study of microscopic structure and dynamics.
Neutrons are stable when bound in an atomic nucleus, whilst having a mean lifetime of approximately 1000 seconds as a free particle.
Neutrons had then been known as building blocks in the atomic nucleus for more than a decade (Nobel Prize to Chadwick in 1935 for their discovery).
www.isis.rl.ac.uk /aboutIsis/whatisaNeutron.htm   (733 words)

  
 Neutron spectra
The distribution of neutron energies in a reactor differs from the fission neutron spectrum due to the slowing down of neutrons in elastic and inelastic collisions with fuel, coolant and construction material.
The median fission neutron energy is 1.6 MeV for Pu-239, and the average energy is 2.1 MeV.
Consequently, the average neutron energy in the nitride core is as large as 160 MeV, with a median energy of 220 keV.
www.neutron.kth.se /courses/transmutation/Spectra/Spectra.html   (1210 words)

  
 Neutron Stars
Although most neutron stars have been discovered as radio pulsars, the vast majority of the energy emitted by neutron stars is in very high energy photons (X-rays and Gamma-rays, with the highest energies exceeding 100 MeV) rather than radio waves.
If the neutron star gets such a high kick velocity, this suggests that there is something unsymmetric in the explosion itself that sends the crushed core of the star in a particular direction with high velocity.
This purported neutron star is also of interest because analysis of the atomic composition of the supernova remnant (using optical spectra) in comparison with stellar evolution models suggests that the mass of the progenitor star that produced the supernova was 25 solar masses.
csep10.phys.utk.edu /astr162/lect/neutron/neutron.html   (596 words)

  
 SPACE.com -- Neutron Star Collisions Common, Study Suggests
Theory says the two newfound neutron stars are already warping the fabric of space, generating gravitational waves that propagate like ripples on a pond.
Neutron stars are stuffed almost entirely with neutrons, subatomic particles that can huddle extremely close together.
Another pair of known neutron stars is destined for calamity in 320 million years, forming the limited basis for estimates of how often the events occur.
www.space.com /scienceastronomy/neutron_stars_031203.html   (985 words)

  
 Neutron   (Site not responding. Last check: 2007-10-22)
Outside the neutrons are unstable and have a half-life of about 15 minutes decaying by an electron and antineutrino to become a proton.
The characteristic of neutrons which most differentiates from other common subatomic particles is the fact that they are This property of neutrons delayed their discovery them very penetrating makes it impossible to them directly and makes them very important agents in nuclear change.
Although atoms in their normal state are uncharged they are ten thousand times larger a neutron and consist of a complex of negatively charged electrons widely spaced around a positively charged nucleus.
www.freeglossary.com /Neutron   (1064 words)

  
 Neutron Vision
Passing neutrons through a pinhole creates a tightly collimated beam, while refraction from a suitable crystal--separating wavelengths a bit like a prism--can yield neutrons of a single energy or wavelength.
Neutrons from a 2-centimeter-wide beam first hit a coarse grating, which creates a series of bright neutron "lines." Each neutron line acts independently as a single "coherent" source of waves, like light from a pinhole used in classic optics experiments, because the slits are widely spaced (several millimeters apart).
Neutron refraction can cleanly distinguish between, say, titanium and molybdenum, even though their absorption of neutrons is similar.
focus.aps.org /story/v17/st20   (687 words)

  
 neutron
Neutron guides work exactly like fiber optic guides—they are rectangular conduits, typically, 5 × 10 centimeters (2 × 4 inches), whose inside surfaces may be coated with multiple layers of nickel that will reflect any neutrons that strike the surface at a glancing angle, if they are not traveling too fast.
Neutrons are electrically neutral, but their impact on research has been positive.
Neutron scattering investigations show that in healthy bones, collagen molecules form a regular nearby periodic array with an average spacing of about 1.5 nanometers, and minerals deposit in spaces along this array every 87 nanometers.
www.ornl.gov /info/ornlreview/rev29-12/text/neutron.htm   (2999 words)

  
 neutron bomb Encyclopedia Palamito : definitions, references, summaries, and best informations of online knowledge™   (Site not responding. Last check: 2007-10-22)
A neutron bomb is a type of nuclear weapon specifically designed to release a...
neutron bombs are impractical because of their cost: A neutron bomb...
The neutron bomb delivers blast and heat effects that are confined to an area of only a few hundred yards in...
www.palamito.com /neutron_bomb_1.htm   (144 words)

  
 Neutron Interferometer and Optics Facility
The Neutron Interferometry and Optics Facility (NIOF) located in the NIST Center for Neutron Research Guide Hall is one of the world's premier user facilities for neutron interferometry and related neutron optical measurements.
Neutron interferometry is ideal for making accurate measurements of the nuclear scattering properties of elements and isotopes.
In particular, neutron phase contrast imaging, three-dimensional neutron tomography, and single crystal diffractometers are being developed for the study of structural and bulk properties of materials.
www.physics.nist.gov /MajResFac/InterFer/text.html   (387 words)

  
 Lives and Deaths of Stars
Neutrons can be packed much closer together than electrons so even though a neutron star is more massive than a white dwarf, it is only about the size of a city.
Even though it is over 660,000 K, the neutron star is close to the limit of HST's detectors because it is at most 27 kilometers across.
Neutron stars would pulsate too quickly because of their huge density, so pulsars must pulsate by a different way than normal variable stars.
www.astronomynotes.com /evolutn/s12.htm   (1226 words)

  
 what is a neutron bomb?
Armor can absorb neutrons and neutron energy, thus reducing the neutron radiation to which the tank crew is exposed, but this offset to some extent by the fact that armor can also react harmfully with neutrons.
The neutron bomb delivers blast and heat effects that are confined to an area of only a few hundred yards in radius.
Because of its short-range destructiveness and the absence of long-range effect, the neutron bomb would be highly effective against tank and infantry formations on the battlefield but would not endanger cities or other population centres only a few miles away.
www.manuelsweb.com /neutronbomb.htm   (378 words)

  
 Protons and neutrons
The neutron is a baryon and is considered to be composed of two down quarks and one up quark.
The decay of the neutron is associated with a quark transformation in which a down quark is converted to an up by the weak interaction.
The decay of the neutron is a good example of the observations which led to the discovery of the neutrino.
hyperphysics.phy-astr.gsu.edu /hbase/particles/proton.html   (1082 words)

  
 Glossary Item - Neutron
Neutrons are uncharged particles found within atomic nuclei.
Experiments done at the Stanford Linear Accelerator Center in the late 1960's and early 1970's showed that neutrons are made from other particles called quarks.
Neutrons are made from one 'up' quark and two 'down' quarks.
education.jlab.org /glossary/neutron.html   (52 words)

  
 ESA - Integral - Three satellites needed to bring out ‘shy star’
The neutron star, called IGR J16283-4838, is an ultra-dense ‘ember’ of an exploded star and was first seen by Integral on 7 April 2005.
Neutron stars are the core remains of ‘supernovae’, exploded stars once about ten times as massive as our Sun.
Neutron stars such as IGR J16283-4838 are often part of binary systems, orbiting a normal star.
www.esa.int /SPECIALS/Integral/SEMSOI6DIAE_0.html   (733 words)

  
 SPACE.com -- Neutron Stars Shed Light on Black Holes
NEUTRON STAR: Gas from a companion star flows down onto the neutron star instead of a fl hole.
But while neutron stars wear their characteristics on their sleeves, fl holes theoretically hide everything in a dark warp of space-time.
Neutron stars and fl holes are both thought to be collapsed stars.
www.space.com /scienceastronomy/astronomy/death_spiral_sidebar_010111.html   (827 words)

  
 A Science Odyssey: People and Discoveries: Chadwick discovers the neutron
He was able to determine that the neutron did exist and that its mass was about 0.1 percent more than the proton's.
His findings were quickly accepted and Werner Heisenberg then showed that the neutron could not be a proton-electron pairing, but had to be its own unique particle -- the third piece of the atom to be found.
Before long, neutron bombardment was applied to the uranium atom, splitting its nucleus and releasing the huge amounts of energy predicted by Einstein's equation E = mc
www.pbs.org /wgbh/aso/databank/entries/dp32ne.html   (506 words)

  
 Neutron Stars and Pulsars - Introduction
Neutron stars are about 20 km in diameter and have the mass of about 1.4 times that of our Sun.
Pulsars are spinning neutron stars that have jets of particles moving almost at the speed of light streaming out above their magnetic poles.
Neutron stars for which we see such pulses are called "pulsars", or sometimes "spin-powered pulsars," indicating that the source of energy is the rotation of the neutron star.
imagine.gsfc.nasa.gov /docs/science/know_l1/pulsars.html   (745 words)

  
 Neutron stars
The strongest inferred neutron star fields are nearly a hundred trillion times stronger than Earth's fields, and even the feeblest neutron star magnetic fields are a hundred million times Earth's, which is a hundred times stronger that any steady field we can generate in a laboratory.
Neutron stars are believed to form in supernovae such as the one that formed the Crab Nebula (or check out this cool X-ray image of the nebula, from the Chandra X-ray Observatory).
Neutrons were discovered in 1932, and very shortly afterward (in 1934) a suggestion was made by Walter Baade and Fritz Zwicky that neutron stars were formed in supernovae.
www.astro.umd.edu /~miller/nstar.html   (6455 words)

  
 NIU Institute for Neutron Therapy   (Site not responding. Last check: 2007-10-22)
Neutrons are more effective at killing tumors than conventional radiation therapy.
Cure rate depends on the type of cells in the tumor (histology), the size of the tumor (stage and/or grade), whether the tumor has spread to other parts of the body (metastasis), and the patient's general health.
Neutron therapy may be appropriate for other sites but has not been proven to be better than standard radiotherapy for sites other than the ones listed above.
www.neutrontherapy.niu.edu /neutrontherapy/candidate/index.shtml   (143 words)

  
 Robin Keir's home page - Software - Neutron   (Site not responding. Last check: 2007-10-22)
Neutron is a very simple and small time synchronizing program that retrieves the accurate time from one of several specialized time servers on the Internet.
It is also possible to have the program automatically exit after the time has been set and so is ideal for placing a shortcut in your Startup folder to sync your clock when your computer is started.
Neutron uses the standard Time protocol (TCP or UDP port 37).
keir.net /neutron.html   (364 words)

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