What is needed is a happy balance where you are soaking up just as many neutrons as are being generated all the time.
However, if you have something like heavy water or graphite that will slow down neutrons and an absorber like cadmium, you can alter the speed of the reaction.
All you need is a few more neutrons around, giving you a k-factor of 1.
In both of them you have neutrons tearing around, some of them hitting nuclei and starting new neutrons going.
Too much damping material will absorb too many neutrons and the reaction will stop.
Neutron Bombardment As soon as neutrons were discovered, it seemed to physicists that they had another possible bombarding particle of extraordinary properties.
For still more massive nuclei containing a larger number of protons, no amount of neutronsis sufficient to keep the assembly stable.
Within a few months of their discovery, energetic neutrons were being used to bring about nuclear reactions.
Furthermore because of the large cross sections involved, thermal neutronsmissed far less frequently than high-energy charged particles did.
Of course, there was the difficulty that neutrons couldn’t be slowed down once they were formed, and as formed they generally had too much energy (according to the new way of looking at things).
It was very easy to switch from the latter theory to the former, if one simply remembered to pair the electrons thought to be in the nucleus with protons and give the name neutrons to these combinations.
Before neutrons could be used, however low-energy and however sure to hit, they had to be produced; and in order to produce neutrons they had to be knocked out of nuclei by bombardment with high-energy protons or some other such method.
If the nucleus contains only protons and neutrons and no electrons, where does the beta particle come from?
The energy formed by the neutrons was at first never more than the tiniest fraction of the energies that went into forming the neutrons in the first place.
Suppose we consider the neutronsas proton-electron combinations.
It is the number of protons plus neutrons in the nucleus.
Within many nuclei, the neutrons are quite stable and do not break up as they do in isolation.
He quickly noted how large nuclear cross sections became when thermal neutrons were the bombarding particles.
At first the number of neutrons required is roughly equal to the number of protons.
There was scarcely any reactive thrust more efficient than that of neutrons hurled at almost the speed of light.
Since we have beams of massiveneutrons from the Midas Touch weapons?
Short, rocketlike bursts of heavy neutrons from their Midas Touch cylinders provided the reaction or kick to get them into the swiftest vertical currents.
The aura of neutrons thrown out only by scattered filaments was probably not of continuous intensity.
Hovering over the vast shape, Ed felt the hard, stinging punch of a few scattered neutrons hitting his body before he ventured too close.
During the first few seconds, a nuclear blast vomited gamma radiation and neutrons in all directions.
It would provide some neutrons to start the chain reaction.
He must have taken enough roentgens of gamma and neutrons to reach or exceed the median-lethal dose.
During the first few seconds, a nuclear blast sprayed gamma radiation andneutrons in all directions.
Many radioisotopes are produced by bombarding suitable targets with neutrons now readily available inside atomic reactors.
Enrico Fermi, an Italian physicist, seized upon the idea of using the newly discovered neutron (an electrically neutral particle) and showed that bombardment with neutrons also could induce radioactivity in a target substance.
This treatment is accomplished by placing the head of the patient in a beam of slow neutrons emerging from a nuclear reactor a few minutes after the boron-10 compound has been injected into a vein.
Boron-10 absorbs slow neutrons readily, and becomes boron-11, which disintegrates almost immediately into alpha particles and a lithium isotope.
Slow neutrons pass through the human body with very little damage, so a fairly strong dose of them can be safely applied to the head.
Since the chemical behavior of an element depends upon its electrons’ electrical charges, extra neutrons (which do not have an electrical charge) may affect the mass of an atom without disturbing its chemical properties.
The weight, or mass, of an atom is due chiefly to its protons and neutrons because the mass of its electrons is negligible.
Beta decay occurs in nuclei with a greater proportion ofneutrons than is normal for the number of protons.
The instability of the nuclei of the heavy atoms is related to the ratio of the number of neutrons to the number of protons in the nuclei.
Loss of an alpha particle from a nucleus lowers the mass number (the total of protons and neutrons) of the parent nucleus by four and the atomic number (the number of protons) by two; the number of neutrons also is reduced by two.
Isotopes of a given element have an identical number of protons but different numbers of neutrons in their nuclei.
An alpha particle is identical with the nucleus of a helium atom and has two neutrons and two protons bundled together.
In a nucleus with a low ratio of neutrons to protons, the nucleus captures one of its own orbital electrons.
Such a shield will stop all the GAMMA RAYS coming from radioactive contamination in the laboratory and much of the cosmic radiation; high-energy cosmic rays and all neutrons still will get through.
The nucleus of every atom (except hydrogen) contains one or more neutrons and one or more protons.
Neutrons that have had their speed reduced by passing through a moderator (graphite, for example) which is built into every reactor to accomplish this very thing.
U), because slow neutrons do not produce fissions in ²³⁸U.
Of course, when the target is removed from the reactor, the number of radioactive atoms begins to decrease according to the characteristic half-life of the nuclide.
Time of decay (hours)”] The radioactive decay curve of sodium-24.
Then you place each card, in turn, on a holder close to the gamma-ray detector for a period of 10 minutes.
Here all the elements are arranged in a periodic table.
The beam of neutrons is turned on for 35 to 40 seconds.
A neutron moderator slows down the neutrons and thus makes them more likely to activate the calcium in the bones.
In the most common type of activation analysis, the neutron bombardment of a sample is performed in a nuclear reactor where the neutrons that strike the target atoms have been slowed down so that they have very little energy of motion.
Bombard with neutrons for about 3 hours in a reactor.
This picture, which is in the collection of the Smithsonian Institution, was exposed to neutrons in a nuclear reactor and then placed in contact with modern photographic film.
The irradiation is resumed so that a uniform dose of neutrons bombards the patient from both front and back.
A source of neutrons to activate the material and a gamma-ray spectrometer to measure the radiation from the material afterwards.
The patient is standing on a turntable that is rotated 180 degrees after half the irradiation is completed so that the dose of neutrons is uniformly distributed to the front and the back of the patient.
That ship that attacked us, attacked with a neutron gun, a gun that shot neutrons through the hull of our ship as easily as protons pass through open space.
Those neutrons killed off four of the crew, and spared us only because we happened to be behind the water tanks.
Neutrons aren't used in any process I've run across.
Into the bargain, his radio was after us, and his neutronsnaturally carried energy.
This was a supply of small nuclei that did not absorb neutrons readily, but absorbed some of the energy of collision and slowed down any neutron that struck it.
What if uranium fission also producedneutrons as well as being initiated by a neutron?
For instance, suppose that neutrons are used to bombard hydrogen-1, which then captures one of the neutrons.
Because it has added a neutron, it has too many neutrons for stability.
Fermi had found that slow neutrons, which had very little energy, were easily absorbed by atomic nuclei—more easily than fast neutrons were absorbed, and certainly more easily than charged particles were.
But what would happen if each of the 2 neutrons that emerged from the original target nucleus struck new nuclei and forced the emission of a pair of neutrons from each.
There would now be a total of 4 neutrons flying about and if each struck new nuclei there would next be 8 neutrons and so on.
Would not the neutrons produced serve to initiate new fissions that would produce new neutrons and so on endlessly?
There are over 100 isotopes that will absorb neutrons and end by becoming an isotope of an element one higher in the atomic number scale.
Then, too, the neutronsreleased by fission were pretty energetic.
Or suppose the enriched uranium were arranged in loosely packed pieces to begin with so that the flying neutrons were in open air too often to maintain the chain reaction.
A large fraction of the gamma rays is emitted in the first few microseconds (millionths of a second) of the atomic explosion, together with neutrons which are also produced in the nuclear fission.
Fourteen percent as nuclear radiation, 4 percent as initial ionizing radiation composed of neutrons and gamma rays emitted within the first minute after detonation, and 10 percent as residual nuclear radiation (fallout).
The initial burst is characterized byneutrons and gamma rays while the residual radiation is primarily alpha, beta, and gamma rays.
However, neutrons have significant mass and interact with the nuclei of atoms, severely disrupting atomic structures.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "neutrons" in a variety of sentences. We hope that you will now be able to make sentences using this word.
