The neutron is a subatomic particle, symbol
n
or
n0
, which has a neutral charge, and a mass slightly greater than that of a proton. Protons and neutrons constitute the nuclei of atoms. Since protons and neutrons behave similarly within the nucleus, they are both referred to as nucleons. Nucleons have a mass of approximately one atomic mass unit, or dalton, symbol Da. Their properties and interactions are described by nuclear physics. Protons and neutrons are not elementary particles; each is composed of three quarks.
Nuclear physics is the field of physics that studies atomic nuclei and their constituents and interactions, in addition to the study of other forms of nuclear matter.
In physics and chemistry, a nucleon is either a proton or a neutron, considered in its role as a component of an atomic nucleus. The number of nucleons in a nucleus defines the atom's mass number.
In particle physics, annihilation is the process that occurs when a subatomic particle collides with its respective antiparticle to produce other particles, such as an electron colliding with a positron to produce two photons. The total energy and momentum of the initial pair are conserved in the process and distributed among a set of other particles in the final state. Antiparticles have exactly opposite additive quantum numbers from particles, so the sums of all quantum numbers of such an original pair are zero. Hence, any set of particles may be produced whose total quantum numbers are also zero as long as conservation of energy, conservation of momentum, and conservation of spin are obeyed.
In nuclear physics and nuclear chemistry, a nuclear reaction is a process in which two nuclei, or a nucleus and an external subatomic particle, collide to produce one or more new nuclides. Thus, a nuclear reaction must cause a transformation of at least one nuclide to another. If a nucleus interacts with another nucleus or particle and they then separate without changing the nature of any nuclide, the process is simply referred to as a type of nuclear scattering, rather than a nuclear reaction.
In chemistry, nuclear physics, and particle physics, inelastic scattering is a process in which the kinetic energy of a particle or a system of particles changes after a collision. Formally, the kinetic energy of the incident particle is not conserved. In an inelastic scattering process, some of the energy of the incident particle is lost or increased. Although inelastic scattering is historically related to the concept of inelastic collision in dynamics, the two concepts are quite distinct; inelastic collision in dynamics refers to processes in which the total macroscopic kinetic energy is not conserved. In general, scattering due to inelastic collisions will be inelastic, but, since elastic collisions often transfer kinetic energy between particles, scattering due to elastic collisions can also be inelastic, as in Compton scattering meaning the two particles in the collision transfer energy causing a loss of energy in one particle.
The nuclear force is a force that acts between hadrons, most commonly observed between protons and neutrons of atoms. Neutrons and protons, both nucleons, are affected by the nuclear force almost identically. Since protons have charge +1 e, they experience an electric force that tends to push them apart, but at short range the attractive nuclear force is strong enough to overcome the electrostatic force. The nuclear force binds nucleons into atomic nuclei.
Thomas Jefferson National Accelerator Facility (TJNAF), commonly called Jefferson Lab or JLab, is a US Department of Energy National Laboratory located in Newport News, Virginia.
ALICE is one of nine detector experiments at the Large Hadron Collider at CERN. The other eight are: ATLAS, CMS, TOTEM, LHCb, LHCf, MoEDAL, FASER and SND@LHC.
GlueX is a particle physics experiment located at the Thomas Jefferson National Accelerator Facility (JLab) accelerator in Newport News, Virginia. Its primary purpose is to better understand the nature of confinement in quantum chromodynamics (QCD) by identifying a spectrum of hybrid and exotic mesons generated by the excitation of the gluonic field binding the quarks. Such mesonic states are predicted to exist outside of the well-established quark model, but none have been definitively identified by previous experiments. A broad high-statistics survey of known light mesons up to and including the is also underway.
The Mainz Microtron, abbreviated MAMI, is a microtron which provides a continuous wave, high intensity, polarized electron beam with an energy up to 1.6 GeV. MAMI is the core of an experimental facility for particle, nuclear and X-ray radiation physics at the Johannes Gutenberg University in Mainz (Germany). It is one of the largest campus-based accelerator facilities for basic research in Europe. The experiments at MAMI are performed by about 200 physicists of many countries organized in international collaborations.
T2K is a particle physics experiment studying the oscillations of the accelerator neutrinos. The experiment is conducted in Japan by the international cooperation of about 500 physicists and engineers with over 60 research institutions from several countries from Europe, Asia and North America and it is a recognized CERN experiment (RE13). T2K collected data within its first phase of operation from 2010 till 2021. The second phase of data taking is expected to start in 2023 and last until commencement of the successor of T2K – the Hyper-Kamiokande experiment in 2027.
DAPHNE was designed by the DAPNIA department of the Commissariat à l'Energie Atomique, in collaboration with the Istituto Nazionale di Fisica Nucleare. The original purpose of the detector was to explore the quantum chromodynamics (QCD) properties of nucleons. To explore these properties, excitation states of the nuclei require to be measured. These excited states of nucleons decay via the emission of light mesons such as pions (π), eta mesons (η) or kaons (K). Various models exist that describe the correlation between the observed reactions, the excited states and QCD.
A nuclear emulsion plate is a type of particle detector first used in nuclear and particle physics experiments in the early decades of the 20th century. It is a modified form of photographic plate that can be used to record and investigate fast charged particles like alpha-particles, nucleons, leptons or mesons. After exposing and developing the emulsion, single particle tracks can be observed and measured using a microscope.
The NA58 experiment, or COMPASS is a 60-metre-long fixed-target experiment at the M2 beam line of the SPS at CERN. The experimental hall is located at the CERN North Area, close to the French village of Prévessin-Moëns. The experiment is a two-staged spectrometer with numerous tracking detectors, particle identification and calorimetry. The physics results are extracted by recording and analysing the final states of the scattering processes.
The EMC effect is the surprising observation that the cross section for deep inelastic scattering from an atomic nucleus is different from that of the same number of free protons and neutrons. From this observation, it can be inferred that the quark momentum distributions in nucleons bound inside nuclei are different from those of free nucleons. This effect was first observed in 1983 at CERN by the European Muon Collaboration, hence the name "EMC effect". It was unexpected, since the average binding energy of protons and neutrons inside nuclei is insignificant when compared to the energy transferred in deep inelastic scattering reactions that probe quark distributions. While over 1000 scientific papers have been written on the topic and numerous hypotheses have been proposed, no definitive explanation for the cause of the effect has been confirmed. Determining the origin of the EMC effect is one of the major unsolved problems in the field of nuclear physics.
The rms charge radius is a measure of the size of an atomic nucleus, particularly the proton distribution. The proton radius is approximately one femtometre = 10−15 metres. It can be measured by the scattering of electrons by the nucleus. Relative changes in the mean squared nuclear charge distribution can be precisely measured with atomic spectroscopy.
The idea that matter consists of smaller particles and that there exists a limited number of sorts of primary, smallest particles in nature has existed in natural philosophy at least since the 6th century BC. Such ideas gained physical credibility beginning in the 19th century, but the concept of "elementary particle" underwent some changes in its meaning: notably, modern physics no longer deems elementary particles indestructible. Even elementary particles can decay or collide destructively; they can cease to exist and create (other) particles in result.
Volker D. Burkert is a German physicist, academic and researcher. He is a Principal Staff Scientist at the Thomas Jefferson National Accelerator Facility at Jefferson Lab (JLab) in Newport News, Virginia (USA). He has made major contributions to the design of the CEBAF Large Acceptance Spectrometer (CLAS) that made it suitable for high luminosity operation in experiments studying spin-polarized electron scattering.
The nucleon magnetic moments are the intrinsic magnetic dipole moments of the proton and neutron, symbols μp and μn. The nucleus of an atom comprises protons and neutrons, both nucleons that behave as small magnets. Their magnetic strengths are measured by their magnetic moments. The nucleons interact with normal matter through either the nuclear force or their magnetic moments, with the charged proton also interacting by the Coulomb force.