Subatomic particles, also called subatomic particles, refer to the structural ratioatomSmaller particles.All atoms are composed of smaller "subatomic" particles, includingElectronics、protonAndneutron[1]。In general, subatomic particles may be electrons, neutrons, protons, mesons, quarks, gluons, photons, etc.
Subatomic particle - internal structure model diagram
Subatomic particles, also called subatomic particles, refer to the structural ratioatomSmaller particles.It includes atomic components such asElectronics、protonandneutron, particles caused by radiation and scattering such asphoton、neutrinoandMuon , and many other exotic particles.In general, subatomic particles may be electrons, neutrons, protonsmeson、quark、Gluon, photons, and so on.[2]
Subatomic particle
The research of modern particle physics focuses on subatomic particles.Strictly speaking, the term "particle" is imprecise. All objects studied in particle physics follow the rules of quantum mechanics, and they all show thatWave particle dualityAccording to different experimental conditions, they show the characteristics of particles or waves.In physical theory, they are neither particles nor waves, and theorists useHilbert spaceFor detailed theoretical basis, see Quantum Field Theory.But according to the convention of particle physics, these objects are still called "particles" in this article, although these particles also have wave characteristics.
All known elementary particles can be used asStandard modelOfQuantum field theoryTo describe.The Standard Model is the best theory in particle physics. It contains 47 basic particles, which can combine to form more complex particles.However, most particle physicists believe that it is still an imperfect theory, and a more basic theory has yet to be discovered.The neutrino static mass discovered during this period is not zero, which is the first experimental observation that deviates from the standard model.
Particle physics has a great impact on the philosophy of science. Some particle physicists still adhere to the reductionism, which has been criticized by many philosophers and scientists.
Development history
Announce
edit
By 1920, scientists had known that every atom was composed of a nucleus and electrons, and the positively charged nucleus was surrounded by a negatively charged electron cloud.Atoms are not "basic particles" - the most basic materials that make up matter, and can no longer be separated into smaller particles.Soon, scientists continued to find particles smaller than atoms, making people more in-depth understanding of the micro world.
Ernest, a British physicist of New Zealand originrutherford(1871-1937) When bombarding nitrogen atoms with alpha particles (helium nuclei), it was found that the hydrogen nucleus was released, that is, the nitrogen nucleus must contain hydrogen nuclei.In 1920, Luther Fujian proposed to name the released hydrogen nucleus "proton" (from the Greek word "protos", meaning "first").The mass of the proton is 1836.12 times that of the electron.Most of the mass of an atom is occupied by the nucleus.In the same year, Rutherford proposed that the nucleus, which is much heavier than the hydrogen atom, also contains particles without charge.
Rutherford has been professor of physics at Cambridge University since 1919Cavendish Laboratory Director of.Rutherford still focused on bombarding different kinds of atomic nuclei with alpha particles (helium nuclei).In 1925, British physicist Patrick Blakett (1897-1974), under the guidance of Rutherford, improved the cloud chamber, invented by Scottish physicist Wilson (1869-1959) in 1911, into a device that can record the disintegration of atoms.However, the energy of alpha particle is not enough to bombard the atomic nucleus with larger mass into fragments. Therefore, the atomic nucleus with larger mass needs to be bombarded with more energetic particles.In 1932, British physicist John Caucroft (1897-1967) and Irish physicist Ernest Walton (1903-1995) built the world's firstParticle accelerator, use the strong magnetic field generated by the electromagnet to accelerate the proton, and then directly bombard the target.
In the 1920s, German physicist Walter Porter (1891-1957) led a team of scientists in Berlin to carry out a series of scientific experiments. They bombarded the nuclei of several lighter elements with alpha particles, including beryllium, boron and lithium.In 1930, they found that the bombardment of atomic nuclei would produce high-energy penetrating radiation. At first, these scientists thought it was a kind of gamma ray radiation, but the penetration of this radiation was stronger than any gamma ray radiation they had ever seen.
In 1932, French physicists Jolio Curie and his wife, Irene Jolio Curie (1897-1956) and Frederick Jolio Curie (1900-1958), discovered that when alpha particles bombarded paraffin or other similar hydrocarbons (composed of hydrogen and carbon elements), they would emit protons with high energy.Further research on this phenomenon has led scientists to question more and more the so-called y-ray inference observed by Porter.James Chadwick (1891-1974), a British physicist, confirmed in the Cavendish laboratory that the radiation produced by bombarding atomic nuclei could not be gamma rays. He also pointed out that the particles contained in the radiation had the same mass as the protons, but were not charged.Chadwick believed that this new particle was a proton bound in an electron (hydrogen atom). When he bombarded the boron atom with a known atomic weight with an alpha particle, he could calculate the mass of this particle - the particle was 1.0087 atomic mass units, slightly larger than the proton (1.007276 mass units).Because the particle is not charged, it is called a neutron.Inside the nucleus, the neutron is very stable, but outside the nucleus, the neutron will decay into a proton, an electron, and an anti neutrino.Protons and neutrons form the nucleus of an atom and together are called nucleons.
Wolfgang Pauli (1900-1958) was one of the greatest physicists in the 20th century. In 1930, Pauli studied beta rays -- a stream of electrons emitted by unstable atoms. These electrons seemed to lose some energy, but no one could find out why the electrons lost energy,This is contradictory to one of the basic physical laws that energy cannot be created and lost out of nothing.In order to solve this mystery, Pauli proposed that beta radiation also contains a previously unknown particle, which is neither charged nor massless at rest.Italian physicist Enrique Fermi (1901-1954) confirmed the existence of this particle in 1934 and called it neutrino.
britainTheoretical physicistPauldirac (1902-1984) made important contributions to the development of quantum electrodynamics.In the late 1920s, theoretical physicists were very interested in the study of electrons. Dirac was not satisfied with the description of electrons made by Werner Heisenberg (1901-1976), a German physicist, so he put forward his own expression of electrons - Dirac equation, and proposed the possibility of electrons being positively charged.In 1932, American physicist Carl Anderson (1805-1991) discovered the existence of this particle.In 1933, Patrick Blakett also independently discovered this kind of particle.Later, such particles were called positrons.Positron is the first antimatter particle found.
In 1937, Anderson cooperated with graduate student Thain Niedermeier (1907-1988) to discover muon, an extremely unstable particle similar to electron, but with a mass more than 200 times that of electron.[3]
New findings
Announce
edit
On September 22, 2011, scientists from the European Particle Physics Laboratory measured that the movement speed exceededlight speedIf the discovery is confirmed, it will overturnEinsteinOfrelativityThat is the basis of the physics community.At first, scientists were deeply suspicious of this phenomenon, but after many careful tests, all processes were error free.
In 1905,EinsteinAccording to the special theory of relativityvacuumIn the environment, no matter in the universe can move faster than the speed of light.This has become the theoretical basis for people to understand the universe and timeModern PhysicsIt is one of the theoretical foundations of.If we really prove thisSuperluminal speedPhenomenon is of great significance, and the whole theoretical system of physics may be rebuilt due to it.
But the final error of the experiment was the technical error of the measuring personnel.The world announced the experimental error on June 8, 2012.
