0
Nuclear Physics
Most commonly known for its applications in nuclear energy and nuclear weapons, Nuclear Physics also has applications in medicine and archaeology. This category is for questions about the branch of physics that deals with the study of the forces, reactions, and internal structures of atomic nuclei, Nuclear Physics.
3,164 Questions
How do the isotopes of an atom differ?
Isotopes of an atom have the same number of protons but different numbers of neutrons. This causes isotopes to have different atomic masses. The chemical properties of isotopes are usually identical, but physical properties such as nuclear stability and radioactive decay can vary.
What type of decay is involved when polonium -214 decays into lead -210?
Alpha decay is involved when polonium-214 decays into lead-210. In alpha decay, an alpha particle (2 protons and 2 neutrons) is emitted from the nucleus, reducing the atomic number by 2 and the mass number by 4.
What contains a heavy atom often used in nuclear fission reactions to produce thermal energy?
Uranium-235 is a heavy atom commonly used in nuclear fission reactions to produce thermal energy. When a uranium-235 atom absorbs a neutron, it becomes unstable and splits into two smaller atoms along with releasing energy and additional neutrons, which can trigger a chain reaction.
When a radioactive nucleus emits an alpha particle, it decreases by two protons and two neutrons. This results in a new nucleus with a lower atomic number by 2 and lower mass number by 4. The emitted alpha particle is a helium nucleus (2 protons and 2 neutrons) and carries a positive charge.
Is radiation stopped by anything?
It depends on the type of radiation.
Alpha can be stopped with a few inches of air, or even a sheet of paper.
Beta can be stopped with a sheet of metal.
Gamma and neutron takes lead and/or concrete, sometimes several feet.
Neutrinos can hardly be stopped by anything - they travel through the Earth with ease.
Does your collection of agates and jasper contain radioactive isotopes?
In all probability, yes. Uranium and its various daughter radionuclides are a natural part of the Earth, so everything of Earth origin, theoretically, has some uranium in it. Its just a matter of being able to detect it, because the levels in an individual sample will be very, very low, usually too low to detect.
How does the strong force keep the nucleus stable?
The strong nuclear force is an attractive force that counteracts (or rather balances-out) the repulsive coulomb force.
Forces can be modelled by an exchange of particles between the involved bodies. I think the particle responsible for the strong nuclear force is the gluon.
In a nucleus there should be a balance of protons and neutrons; too many protons and the repulsive force will be too high, too many neutrons and there won't be enough glue to go round.
What was Crookes atomic model called?
The Crookes atomic model is known as the plum pudding model. It was proposed by Sir William Crookes in 1904 and suggested that atoms are composed of a positively charged "pudding" with embedded negatively charged electrons.
Which penetrates farthest in an object Alpha particle or beta?
Not much. A sheet of paper will stop it. The alpha particle is two protons and two neutrons - a helium-4 nucleus. As radiation goes, it's big and fat, and it will "run into" stuff even if it's just flying through air. Depending on its energy, it can penetrate air, but not more than a few inches.
Why is americium used in gauges?
Americium 241 is an artificial isotope with a long half life - 432,2 years - and a gamma ray emitter. Being a strong gamma emitter it can be used for gamma radiography of materials and for thickness gauges.
Gamma radiation is measured in several different ways. You can use a geiger-muller detector running in avalanche mode; you can use an ion chamber in linear mode; you can use a photo scintillator running in either gross or window mode; and you can use a supercooled diode to detect it. These are just a few examples.
We don't really know how much gamma radiation at low levels can harm humans or pets. It is understood that a typical person receives about one millisievert per year from background radiation, with an additional one millisievert per year due to medical radiation. These levels are considered perfectly normal.
At higher doses, it becomes a little more certain, but it still requires a substantial amount of radiation to impact a person, on the order of 250 millisieverts before you can even detect changes in blood, and on the order of 1 sievert before significant, predictable impact.
No, the distance between Japan and Denver is such that, at that distance, there will be no measurable dose rate in Denver. However, you need to realize the distinction between radiation and radioactivity. Radiation is what comes out of radioactive material so, if the radioactive material stays in Japan, then the radiation will not be measurable outside of Japan. On the other hand, radioactive material, such as Cesium-137 and Iodine-131, both gamma emitters, can travel from Japan to Denver, even to the entire world. Problem (or salvation, depending on how you look at it) is that diffusion from the atmosphere will dilute the radioactive material so much that you still won't be able to detect it at any statistical confidence above the normal background radiation.
Yes, there are trace amounts of radioactive material coming in from flights out of Japan, and there are trace amounts in the atmosphere already reaching our west coast, but they are trace amounts that do not matter. Even in Japan, the risk is small so, by the time we reach Denver, there will be no significant risk.
Addendum:Denver lies east of The Nevada National Security Site (N2S2), essentially down wind. The significance of this is the largest nuclear test site in the continental US, and one of the largest nuclear detonation sites in the world resides at N2S2. From the 1950's into the 1990's, the US detonated over 1000 devices in the various test ranges at this site. N2S2 is one of the most radioactively contaminated sites in the world, much of the debris from detonations still lies on the surface of the desert there, free to be carried by the wind as far as it can go. The gamma emitter I-131 has been traced as far as the state of Maine as a direct result of nuclear detonations in the Nevada desert, and roughly 3% of all radioactive debris cast out by nuclear fissile detonations is I-131, a direct link to thyroid cancers.Summary, you have more to fear from the dust blown up from Nevada, than that kicked off the shoes of Japanese refugees.
Does the beta particle increase or decrase mass?
The beta particle decreases mass because it is an electron emitted from a nucleus during beta decay. The process of emitting a beta particle can result in the conversion of a neutron into a proton, leading to a decrease in the mass number of the nucleus.
Where did the first self-substaining nuclear fission chain reaction occur?
The first self-sustaining nuclear fission chain reaction occurred at the University of Chicago's Stagg Field on December 2, 1942, as part of the Manhattan Project. Physicist Enrico Fermi led the team of scientists that successfully achieved this milestone in nuclear physics and engineering.
How is knowing the half-life of atoms useful?
Knowing the half-life of radioisotopes is useful for many reasons. We can look at a few examples to see why.
If we have radioactive material, we need to know the half-life to know how long it is dangerous. This applies to fission products inside spent nuclear fuel. This fuel generates heat long after it has been removed from a reactor, and we have to store this stuff securely for many human lifetimes. Fission products of uranium and plutonium are super nasty, and they must be kept out of harm's way.
Knowing the half-life of a certain material can allow us to date things that are old. Radiocarbon (carbon-14) is used to date things like skeletons or plant materials that archaeologists have recovered. We can also use something like uranium-lead to date rock structures back millions and even billions of years.
There is a broad range of radioisotopes that we find in use in the medical field, and we need to know the half-lives of them. We might select a short-lived radioisotope to act as a tracer for medical imaging. A medical staff member will inject a patient or will have him ingest this substance, and then medical professionals take pictures. Knowing the half-life allows us to prepare the material closely enough to the time of use so that it is "potent" enough for the application. In another use, a radioactive isotope will be implanted to irradiate a tumor in a patient. The half-life of the material must be known and coupled to the amount of the substance used to calculate dosage to a patient.
Is Tyvek a gamma radiation blocker?
No, Tyvek is not a good gamma ray blocker. We know that Tyvek is HDPE (high-density polyethylene), and KDPE is a hydrocarbon. Even though it is "high density" material, it is only high density compared to other poly plastics. The best gamma ray blockers are materials with high mass. Atoms with high atomic numbers and high density are the ones we need to block gamma rays. Carbon and hydrogen don't fit the bill. Tyvek is a poor choice for gamma ray shielding.
What is a good choice for gamma ray shielding? We might choose lead 'cause it's cheap and easy to use as well as a good gamma blocker. Certainly concrete and dirt work fairly well as we can get a lot of that stuff together to provide gamma shielding.
Why is lise meitners contribution significant?
She did the chemical analysis that proved that neutrons had produced atomic fission in uranium.
When Fermi had done the same experiment the year before he incorrectly identified the fission products as transuranic elements, as he had no chemist as good as Meitner to analyze his samples.
Why are lighter elements used in fusion reactions?
Because their binding energy is greater than that of their products, thus permitting an energy release.
This is the same reason heavier elements are used in fission reactions.
The range of elements from iron to lead has the lowest binding energy.
What is made up of a neutron a proton and a surrounding cloud of orbiting electrons?
An atom is made up of a neutron, a proton, and a surrounding cloud of orbiting electrons. The nucleus of the atom contains the neutrons and protons, while the electrons occupy the electron cloud surrounding the nucleus.
What happens to a radioactive person?
Although all people do contain a small amount of radioactive isotopes in their bodes, making them slightly radioactive, it is not nearly a large enough dose to have any noticeable effects. But if you mean a person who is highly radioactive, then the most likely way for that to happen is if a radioactive substance were to enter that person's body. The effects of that would depend on the dose and the substance. For instance, plutonium, which emits alpha, beta and gamma rays causes radiation sickness and an increased chance of cancer. And radium which emits more alpha rays then beta or gamma rays and is much more radioactive then plutonium causing much the same effects and decays into radium. As radium is chemically similar to calcium, it can cause great harm by replacing calcium in the persons bones.
How does nuclear radiation effect the ocean?
Nuclear radiation doesn't affect the ocean itself, but the animals that live there. Just like any living thing, if an ocean animal is exposed to high level of radiations it might develop mutations, and/or cancer, leading to a painful death.
Where does neptunium fit on the periodic table?
Neptunium is a radioactive actinide element with the atomic number 93. It is situated in the actinide series of the periodic table, which is the row below the lanthanide series, between uranium and plutonium.
What uses a controlled nuclear chain reaction?
The most promising equipment is the Tokamak, which is a circular toroidal chamber in which the gaseous plasma is circulated and heated, and constrained by magnetic fields. This was developed initially in the Soviet Union but has been adopted in several countries as a research and development tool. Up to now the best results have come from the JET (Joint European Torus) at Culham UK. A larger version is to be built in France called ITER, but it will be years before it is built and being used. You can find ITER and JET on Wikipedia and other websites .
All of them - alpha - beta - neutron - visible light - are examples of nuclear radiation.
How much would still remain in 30 minutes if you had a 5 - grm sample of lawrencium?
Lawrencium has a half-life of about 215 minutes. After 30 minutes, about 85% of the original sample would remain. Therefore, approximately 4.25 grams of lawrencium would still be present in a 5-gram sample after 30 minutes.
