The first decades of the 20th century saw intense activity in the study of the structure of the atom. Observation of radioactive decay and interaction of particle beams with matter allowed physicists to make fundamental discoveries. At the same time, thanks to the study of cosmic radiation, it was possible to observe particles until then unknown. Technological development subsequently facilitated the construction of accelerators, machines that increase the energy of the particles making them travel to near the speed of light, the maximum speed possible for any kind of body. The use of accelerators has permitted exploration of the fundamental constituents of atomic nuclei and the creation of new forms of matter. In linear accelerators, particles are made to collide with a fixed target, while in circular accelerators two particle beams accelerated in opposite directions collide with each other. The quantity of energy that the particles have acquired before impact are converted into other forms of matter thanks to the interaction, thus making it possible to observe new particles.
KLOE-2 is the main experiment of the Frascati National Laboratories and represents the continuation of the KLOE experiment, upgraded with new detectors, concentrates of state of the art technology to improve its discovery potential.
There is strong astrophysical evidence that most of the matter making up the Universe is not “ordinary matter” (i.e. it is not constituted by particles described by the Standard Model). The most popular hypothesis among physicists is that it consists of a new kind of matter, electrically neutral and stable, which does not interact (at all or very weakly) with ordinary matter and therefore does not produce electromagnetic radiation, i.e. it is “dark”.
ATLAS is the largest piece of equipment at LHC, with a length of 26 m and a maximum diameter of 22 m. These dimensions are dictated by the high performance required of the equipment, which has the objective of a detailed and thorough examination of the processes involving the Higgs boson and the systematic study of the properties of heavy b e t quarks, which will be produced with high frequency in proton-proton collisions.
Belle II is the natural continuation of the Belle and BaBar experiments started about 20 years ago at the KEKB (Tsukuba, Japan) and PEP-II (Stanford,U SA) B-factories, respectively. These two experiments have discovered CP violation in the B meson system, confirmed the Cabibbo-Kobayashi-Maskawa quark mixing mechanism and completed an extensive programme of physical measurements of flavour, by studying both particles containing beauty or charm quarks as well as τ leptons.
The BESIII experiment, operational since 2008, measures the characteristics of events produced in the annihilation of electrons and positrons colliding in the BEPCII (acronym of Beijing Electron Positron Collider) accelerator, at the IHEP laboratory in Beijing. The BEPCII collider runs at a total energy between 2 and 4.2 GeV, the region in which particles with c (charm) quarks are produced with high frequency.
The CDF has achieved many important results. The most famous in 1994: on 26 April the CDF collaboration announced the first evidence of the top quark. 2006 was the year of another important discovery: the oscillation of the Bs meson. In 2008 the great news: the prestigious “Panofsky 2009” prize of the American Physical Society went to the two Italians, Aldo Menzione and Luciano Ristori, leaders of crucial projects for the above-mentioned discoveries: the SVX silicon vertex detector and the SVT super-processor.
CMS (Compact Muon Solenoid) is one of 4 experiments placed along the LHC beam. In 2012 it announced the discovery of the Higgs boson, the so-called “God particle”. This discovery earned the Nobel Prize for the physicists who predicted it some 50 years earlier. The main line of research of CMS are physical phenomena not predicted by the Standard Model but by its possible extensions, such as Supersymmetry.
There are two ways to search for new physics: one aims to increase the available energy to produce and observe new particles (a famous example of this “discovery” physics is the search for the Higgs boson at the LHC); the other aims to measure processes that have never been observed, being extremely rare, and compare them with the theoretical predictions, NA62 has in fact the primary purpose of searching for new physics by measuring a rare decay of the K meson.
The Frascati National Laboratories are participating in the design and construction of the Mu2e experiment at the Fermilab in the United States, scheduled to start in 2020. According to the Standard Model, muons decay into electrons through a 3-stage process: μ– → e–anti-νeνμ, in which the total lepton number between initial and final state is preserved. The Mu2e (pronounced Mu To e) experiment researches the process of direct conversion of a muon into an electron in the presence of an aluminium nucleus.
Particle physics today is in a very particular situation: all particles of the Standard Model have been discovered and the mass value of the Higgs and top are such that the Standard Model could be a valid theory up to the Planck mass.
In high-energy and particle physics success of experimental research is largely dependent on the quality of charged particles beam shaping during its both acceleration and injection in storage rings. To control the beams of charged particles, electromagnetic fields of different origin and configurations are typically applied. A common technique is based on the use of the electromagnetic field of the dipoles, quadrupoles, wigglers etc. of giant sizes (several meters for LHC), as well as bulky collimators.
The g-2 experiment, under construction at the Fermilab laboratory (Chicago-IL, USA), has the objective of measuring the magnetic anomaly of the muon with a precision of 1.6×10–10 (0.14 parts per million), such as to allow a very stringent test of the Standard Model. It will require a data sample 20 times more extensive than the previous experiment at Brookhaven National Laboratory and reduction by a factor of 3 of the uncertainty of the systematic effects.
LHCb is an experiment dedicated to the study of particles containing the b quark. These particles will be produced in large quantities in proton interactions in the LHC. They will always be produced in pairs: one particle containing the b quark and the other containing the b antiquark. The study of certain decays of these particles – which occur very rarely – may provide an explanation of the mechanism responsible for the fact that we live in a universe of matter and not antimatter.