The simplest of all antiatoms to fabricate is antihydrogen, composed of only a single positron and antiproton. This makes it the easiest complex system to study when it comes to symmetry between matter and antimatter. The Antiproton Decelerator at CERN is used to produce antiprotons and antiatoms. It works by firing high energy protons into a block of high density metal which then produces a range of secondary particles with high energy antiprotons among them. Strong electric fields are used to slow down these antiprotons (hence why its called a decelerator) so that they can be used in experiments. All aspects of antihydrogen are put under scrutiny such as band structure, band splitting, overall neutrality as well as the charge to mass ratio and magnetic moment of the antiproton. If even a small discrepancy could be found, despite how unlikely it seems at the moment, it would be the most revolutionary discovery in the last 50 years.
Back in 1855 a mathematical physicist turned doctor, called Adolf Eugen Fick, created what is now known as Fick’s laws of diffusion. The first is simply that the the diffusive flux is proportional to the concentration gradient and the second is that the rate of concentration change is proportional to the derivative of the concentration gradient. Later the same conclusion was reached when applying the method of random walks to particles in suspension and the final result was reached where the mean squared displacement of a particle is proportional to the time since it stared to move. This is considered the standard description of the diffusion process:
〈 χ2 〉 ∝ t
Resistance is actually quite a complicated thing to explain properly but the basic explanation that it is the effect of the material getting in the electrons way will suffice here. This theory describes electrons as having mean free paths through the metal, average distances they will travel before colliding with an an element of the lattice and being scattered forced to change momentum. Now ballistic electrons are those that exist in a material which have such low electrical resistivity that the mean free path of the electron is longer than the material that its travelling in. This means the electrons will only scatter and change direction when they meet the edge of the wire for instance, unable to escape due to the work function they ricochet back into the metal and continue on their elongated path until reaching another boundary.
I have written a post before about the initiation and development of lightning in clouds. This previous piece of writing focuses on the photographic evidence provided as a way of analysing lightning production while this current study focuses more on looking at accompanying events to lightning storms to see if current theories hold up. To this day we still do not know what physical mechanism lies behind lightning production in thunderclouds and we also don’t know why different types of lightning leaders (channels of ionised air which lightning will follow) are created and then propagate. Considering that lightning is not a very rare natural occurrence its creation has been described as “probably one of the biggest mysteries in the atmospheric sciences.”
Over a year ago in a weekly roundup I vaguely mentioned the hypothetical particle called the axion. This particle is the end result of a series of theories to explain the possible asymmetry between real and antimatter during interactions of the weak force. The primary search for these particles is the CERN Axion Solar Telescope (CAST) which, as axions are believed to be created in stars, constantly monitors the sun. Using a massive superconducting magnet axions will hopefully be converted into X-rays which can then be much more easily detected. The exact specifications of the telescope are often altered in order to look in different mass and energy ranges. In the most recent data gathering session from 2013 to 2015 they actually repeated a previous search done nearly a decade earlier but now with the sensitivity improved three times over the already considerable amount. The range of interest for this study was between two and seven keV and the count rate was recorded for the various energy X-rays induced by the incoming particles.
When high temperatures are reached electrons, that are normally held by electromagnetism, are liberated and the gas turns into a plasma. In a similar way, although quarks cannot exist independently (they have to be at least paired with one other quark) when the temperature is raised to 1000 MeV per particle, which is about a hundred trillion (short scale) kelvin, quarks and gluons can be liberated and so exist not confined, but still as a unified mass. This state is normally created through the collision of very heavy nuclei travelling very fast.
When an ion is produced by ionising radiation this is normally considered the end of the story at least from the perspective of the ion. The radiation goes flying off and the ion goes to destroy some DNA or something similar. In reality the situation is a bit more complicated than that. The ion, almost always positive, interacts with the electrons in whatever medium it’s found itself in leading to it losing energy. These interactions result in many electrons, called secondary electrons, gaining the energy to ionise the surroundings. This means that following the path of the primary radiation there is a cloud of secondary ionisations called the track structure as represented on the diagram: