|
|
“Neutrinos” Neutrinos are many particles, which make up this vast universe that we live in. In addition, they are also one of the most mysterious because of how little we know about them. Neutrinos could be compared to the make up of an electron, with one crucial difference: neutrinos are neutral particles, meaning they do not carry any electrical charge. Because of this difference, they are not affected by the electromagnetic forces, which act on electrons. However, they do have a weakness; a “weak” sub-atomic force of much shorter range than electromagnetism. This enables them to pass through great distances in matter without being affected by it. Although misunderstood my most of mankind, it has been discovered that neutrinos have mass, and that they also interact gravitationally with other massive particles, but gravity is by far the weakest of the forces (Casper). The mass of electron neutrinos is measured in tritium beta decay experiments. The decay results in a 3-helium, electron, and an electron antineutrino. I neutrinos have a non-zero mass, the spectrum of the electrons is deformed at the high-energy part, i.e. the neutrino mass determines the maximum energy of emitted electrons. To be a bit more precise, the experiments measure the neutrino mass squared. When taken at the face value, all results point to a negative mass squared. This is most likely due to a systematic error, and actually two running experiments, known as Mainz and Troitsk, have been able to measure physically acceptable values (pdg). The Majorana mass is measured by double beta decay experiments. These experiments utilize a nucleid that is steady in normal beta decay but can decay by a double weak interaction process that changes the charge of the nucleus by two units. Two neutrinos are emitted in such a decay. Though, a vertex with no neutrinos is possible if the neutrinos have Majorana mass.
|
