The most famous equation of perhaps the entirety of physics history: E = mc2. The simple statement that energy is inherently connected to mass. There are many caveats and extensions that can be understood but the basics is just that. A particle will have an energy that is stored partly as mass and partly as kinetic energy. In nuclear reactions we have discovered processes which ultimately lose some amount of mass, this is converted into energy with explosive potential (as the equation tells us that every kilogram of mass will provide c2 Joule worth of energy). The process can also work in reverse. Provide a photon with enough energy and it could very well produce mass in the form of an electron and a positron most commonly.
Muons are like electrons, but heavier. That is possibly the best description of them possible in so few words. Muons have a negative charge equivalent to an electrons, a spin of ±1/2 and can be found in many of the same Feynman diagrams as the electrons. This make their heaviness their defining characteristic as they have a mass 207 times greater than an electron’s. Of course this means it’s harder to accelerate a muon to particular speed but once it’s there, it’s unlikely to be stopped as easily as an electron. The transmissivity of a muon beam is considerably greater than that of an electron beam or an X-ray (their higher mass results in less deacceleration so less energy radiated). This means imaging of incredibly dense materials such as subterranean rocks or nuclear waste can be performed where an electron only method would struggle.
Ion acceleration in principal is quite easy to explain. Ions are charged and so will inevitably gain energy if an electric field is allowed to accelerate them. Inside time of flight mass spectrometers a type of ion acceleration takes place as the positive ions are pulled towards a negative plate (and end up shooting through a hole in the middle of it) so that there mass can be determined based on how long it took them to reach the detector. Of course there are more advanced methods of ion acceleration than this. Laser acceleration of ion beams has become quite the developed process.
Antihydrogen, made from a single antiproton and single positron, is the simplest antiatom that can be created. As tests are constantly going on to try and find some asymmetry between matter and antimatter there is always a demand for antihydrogen to be experimented with. Of course the production is hard enough as it involves trying to create and then bind two significantly different particles but afterwards containment is also an issue as the antihydrogen threatens to annihilate any matter it touches.
Using electromagnetic radiation to probe matter is such an inherent part of physics that it comes up in every branch and every subject. Whether it’s the interaction between charges, understanding crystal structures, monitoring chemical reactions or logging the compounds found in foodstuff there is always spectroscopy. One of more common techniques is called pump-probe spectroscopy. A laser pulse of only a few hundred femtoseconds is split into two sections. The stronger is sent first and is called the pump and it is this pump which excites the matter being studied into a energetic state. Then along comes the probe pulse which records various optical properties of the matter. Normally the delay on the probe is varied in order to see how the relaxation occurs in the material.
Stopping power is the ability of a material to slow down charged particles (stopping power is only used for charged particles) passing through it by removing their energy through interactions with the particles in the material. In the early 1930s a physicist named Hans Bethe developed the Bethe formula for calculating the average energy loss over a distance within a material:
where me and e are the mass and charge of an electron; I is the average potential of the electrons in the material and n is their number density; and v and z both refer to the particle being retarded, being velocity and charge respectively (it should also be noted that this is a simplification for a non relativistic particle. Electrons and fast moving particles require corrections to the above formula). Continue reading Calculating Distance Over Which Charged Particles Pause
As is mentioned quite concisely in this page on waves, waves that meet each other undergo superposition and either constructive or destructive interference. This can be seen straight from Maxwell’s equations and so for a long time this was not questioned. It was eventually discovered that it is actually possible for photons to collide with each other in an effect called light by light scattering. According to particle physics such an interaction where two photons end up bouncing off each other is controlled by the W± bosons. Despite considerable effort being exerted from some very powerful lasers there has still not been direct observational evidence of elastic light by light scattering. Most of the information for its existence has come from parallel observations involving the anomalous values of the magnetic moment in electrons and muons.