Nuclear Physics

There is no way of knowing at our current level of physics understanding; we do not know what conditions prevailed at the time of the Big Bang, or what - if anything - preceded it. We don't even know if the concept of "before" makes any sense in terms of the Big Bang.

Aluminum-28 decays into stable silicon-28. Al-28's decay can be thought of in this way: One of the neutrons of Al-28 nucleus decays into an electron and a proton (the sum being electrically neutral). The high-speed electron is the beta particle that is net-released from the atom but the proton stays behind in the nucleus. But now, the number of protons in the nucleus has increased from 13 (in Al-28) to 14 (Si-28). So from this beta decay, an atom of unstable Al-28 lets fly a beta particle (high speed electron) but moves up one in the periodic table (to Si-28).

A plane including the direction of light propagation and the direction of electric field is called the "plane of vibration". The "plane of polarization" is a confinement of the electric/magnetic field vector to a given plane along the direction of propagation.

In the sun and other stars it occurs by protons reacting together to produce helium nuclei. See link below. On Earth experimenters are trying to fuse nuclei of deuterium and tritium as the best combination for success, but only very short (less than 1 second) bursts have so far been achieved.

An x-ray is a short wavelength, high frequency, high energy electromagnetic radiation lying between ultra-violet and gamma rays on the EM spectrum. Because they are so energetic, they can easily penetrate light materials (such as biological tissue), but are blocked by denser materials (such as metals or bone)

X-rays, which were discovered in 1895 by German physicist Wilhelm Röntgen. They are produced when high-speed electrons, accelerated by a high voltage, collide with nuclei in a metal target. The x-ray spectrum consists of a continuous bremsstrahlung emission, and characteristic, narrow emission lines which are specific to the material in the target.

When incident upon a surface, x-rays diffract, enabling us to determine properties of the material, such as its composition and structure.

Without the strong force, the nuclei of atoms would not be able to hold together. The strong force is responsible for binding protons and neutrons in the nucleus, preventing them from flying apart due to the electromagnetic repulsion of positively charged protons.

X-rays pass through soft tissue and are blocked by hard tissue, which means that the lump is harder than the rest of your lung. Cancer tissue is not necessarily harder than other tissue, so don't jump to that conclusion. What can be harder in the lung tissue is tubercles, which are small growths caused by tuberculosis. Of course, you should follow whatever your doctor says about this, not something off WikiAnswers.

Unstable nuclides undergo nuclear reactions in order to become more stable. These reactions involve the nucleus gaining or losing subatomic particles in an attempt to achieve a more favorable balance of protons and neutrons. By undergoing nuclear reactions, unstable nuclides can transform into more stable isotopes with lower energy states.

In order to be nuclear fuel in an conventional nuclear plant, the isotopes have to be capable of fission and have a critical mass. Of the potential fuels found in nature, only 235U has this capacity, and there is not enough of it in uranium ore to provide for fuel of a simple reactor without enrichment.

The half lives of two uranium isotopes most commonly found in nature are roughly 703,800,000, for 235U, which is 0.720% of what is found, and 4,468,900,000 years for 238U, which is 99.274%. The percentage of 235U is increased to about 4% or 5% for fuel in power plants. This means that even though uranium can have critical mass, it is not especially dangerously radioactive.

Critical mass is achievable because the uranium can produce a chain reaction in which the fission of one atom causes the fission of one or more other atoms. This happens because uranium occasionally undergo spontaneous fission instead of its normal alpha decay, producing neutrons in the process, and the neutrons can cause other atoms to undergo fission. If there is a sufficiently abundant supply of atoms capable of fission, the fission event produces on average more than one other fission event. As this continues, the speed of fission increases and a chain reaction follows, going on until the fuel runs out.

While the original uranium is not especially radioactive, the products of fission are. They cannot support fission, because they do not have sufficient mass, but their half lives are mostly very, very short. Each daughter atom of fission has a high probability of multiple decays during the first seconds of its existence. The isotopes with half lives of seconds or less are mostly gone by the time the fuel rod is removed from the reactor, but they are followed by isotopes with half lives ranging from days to years.

The decay of short term fission products happens so rapidly that even in the absence of fission, the rods need special cooling for several years. As the decay continues, the half lives of the remaining isotopes get longer, until the atoms of isotopes with short half lives are mostly gone, at which point the rods can be removed to longer term storage.

Medium term fission products have half lives of 10 to 90 years, making them very radioactive. Nuclear waste needs centuries of storage just because of these. And long term fission fragments have half lives that range from 211 to 80,000,000 years.

It has been calculated that the time it takes for spent fuel to decay to the level of radioactivity of naturally occurring uranium ore is about 6,000,000 years.

Neutron radiation increases the atomic number of the donating atom by one. This occurs when a neutron is absorbed by an atom, causing it to become unstable and undergo beta decay, which results in an increase in atomic number.

Radioactive waste is actually the fumes that come off of uranium when we use it. It is placed deep in the earth's crust, so as not to harm humans. It lasts forever.

Update: u-238's half-life is 4.5 billion years. That means it takes 4.5 billion years for 1 lbs of u-238 to become .5 lbs and so on. But it never really goes away : ) hence "Matter cannot be created nor destroyed"-first law of thermodynamics

Generally gamma radiation is the most penetrating one, but it is also least ionising. I don't quite understand what you mean by saying "Nuclide" radiation. Nuclides are generally isotopes, not radiation. Nuclides (isotopes) don't have to be radioactive, but the isotopes that lie outside the curve of stability (function of the number of proton and the number of neutrons in a particular nucleus) are unstable and do decay (are radioactive)

An alpha particle is a helium-4 nucleus, and contains two protons and two neutrons. Therefore, the original nucleus will have two protons and two neutrons less. Its atomic number will be two less, and its atomic mass will be 4 less.

An atomic bomb is an example of the weak nuclear force because it involves the transformation of neutrons into protons and vice versa within the atomic nucleus, a process mediated by the weak nuclear force. This transformation releases a massive amount of energy, contributing to the destructive power of the atomic bomb.

alpha

Alpha radiation is the most ionizing of the three radiations but can fortunately be stopped by a few centimetres of air or a thin sheet of paper. Beta and especially Gamma are less ionising but are more penetrative and therefore can cause damage while on the outside of the body (whereas alpha will only really cause damage inside).

Hydrogen is used in nuclear fission as a moderator to slow down neutrons produced during the fission process, making them more likely to interact with other fissile nuclei to sustain the chain reaction. Water containing hydrogen atoms, such as heavy water (deuterium oxide) or light water (H2O), is commonly used as a moderator in nuclear reactors.

100Fm254 .........> 98Cf250 + 2He4

Heat is produced by the recoil (kinetic energy) of the fission fragments, when they are stopped in the fuel material

The gamma ray is not a particle but is just an EM wave that transmits energy.

Generally no radiation is safe. You cannot "inject" radiation into anything because it is the product of various unstable nuclei decaying. Alpha radiation is much more ionising than gamma, but much less penetrating than it. That makes it more dangerous if it is inside your body; it can be stopped by skin. Therefore you would have to swallow a sample of a radioactive material. However, gamma radiation is always emitted together with alpha or beta radiation.

Alpha and Beta radiations are not very strong and are blocked even by our clothes

but gamma radiation is highly ionizing and requires protection at large.

It is highly ionizing and once coming in contact with the body, it can produce cellular reactions and could cause genetic mutations.

^ sorry but thats wrong...

actually gamma is less ionising than alpha and beta. just saying...

-Djsaf

Alpha radiation is used in various applications, such as smoke detectors and some types of cancer treatment, because it is highly ionizing and has a short range in tissue. This makes it effective in targeting and destroying specific cells while minimizing damage to surrounding healthy tissue.

Yes, the proton is a nucleon. The term nucleon is used to speak of component particles of the nucleus of an atom. That means either a proton or a neutron. The term nucleon can be applied to either the proton or neutron when speaking of these particles as building blocks of atomic nuclei. Use the link to the related question below for more information.