Nuclear emulsion
Encyclopedia
In a Particle
Particle physics
Particle physics is a branch of physics that studies the existence and interactions of particles that are the constituents of what is usually referred to as matter or radiation. In current understanding, particles are excitations of quantum fields and interact following their dynamics...

 and Nuclear physics
Nuclear physics
Nuclear physics is the field of physics that studies the building blocks and interactions of atomic nuclei. The most commonly known applications of nuclear physics are nuclear power generation and nuclear weapons technology, but the research has provided application in many fields, including those...

, a nuclear emulsion plate is a photographic plate
Photographic plate
Photographic plates preceded photographic film as a means of photography. A light-sensitive emulsion of silver salts was applied to a glass plate. This form of photographic material largely faded from the consumer market in the early years of the 20th century, as more convenient and less fragile...

 with a particularly thick emulsion layer and with a very uniform grain size. Like bubble chamber
Bubble chamber
A bubble chamber is a vessel filled with a superheated transparent liquid used to detect electrically charged particles moving through it. It was invented in 1952 by Donald A. Glaser, for which he was awarded the 1960 Nobel Prize in Physics...

s, cloud chamber
Cloud chamber
The cloud chamber, also known as the Wilson chamber, is a particle detector used for detecting ionizing radiation. In its most basic form, a cloud chamber is a sealed environment containing a supersaturated vapor of water or alcohol. When a charged particle interacts with the mixture, it ionizes it...

s, and wire chambers nuclear emulsion plates record the tracks of charged particles passing through. They are compact, have high density and produce a cumulative record, but have the disadvantage that the plates must be developed before the tracks can be observed.

Nuclear emulsions can be used to record and investigate fast charged particles like nucleon
Nucleon
In physics, a nucleon is a collective name for two particles: the neutron and the proton. These are the two constituents of the atomic nucleus. Until the 1960s, the nucleons were thought to be elementary particles...

s or meson
Meson
In particle physics, mesons are subatomic particles composed of one quark and one antiquark, bound together by the strong interaction. Because mesons are composed of sub-particles, they have a physical size, with a radius roughly one femtometer: 10−15 m, which is about the size of a proton...

s. After exposing and developing the plate, single particle tracks can be observed and measured using a microscope. In 1966, Ishfaq Ahmad
Ishfaq Ahmad
Ishfaq Ahmad , D.Sc., Minister of State, SI, HI, NI, FPAS, is a Pakistani nuclear physicist, and well-known educationist and academic from Pakistan...

 made further advances in the field, and proposed the inelastic collision of β−
Beta particle
Beta particles are high-energy, high-speed electrons or positrons emitted by certain types of radioactive nuclei such as potassium-40. The beta particles emitted are a form of ionizing radiation also known as beta rays. The production of beta particles is termed beta decay...

 between the heavy nuclei and the light-wave interference, using the particle detectors at CERN, can results in heavy absorption of multiple pion in a complex energy-particle.

In 1937, Marietta Blau
Marietta Blau
Marietta Blau was an Austrian physicist. After having obtained the general certificate of education from the girls' high school run by the Association for the Extended Education of Women, she studied physics and mathematics at the University of Vienna from 1914 to 1918; her Ph. D...

 and Hertha Wambacher
Hertha Wambacher
Hertha Wambacher was an Austrian physicist. After having obtained the general certificate of education from the girls' high school run by the Association for the Extended Education of Women in 1922, she studied first chemistry, then physics at the University of Vienna.Wambacher's dissertation at...

 discovered nuclear disintegration stars due to spallation
Spallation
In general, spallation is a process in which fragments of material are ejected from a body due to impact or stress. In the context of impact mechanics it describes ejection or vaporization of material from a target during impact by a projectile...

 in nuclear emulsions that had been exposed to cosmic radiation at a height of 2,300 metres (≈7,500 feet) above sea level.

Using nuclear emulsions exposed on high mountains, Cecil Frank Powell
Cecil Frank Powell
Cecil Frank Powell, FRS was a British physicist, and Nobel Prize in Physics laureate for his development of the photographic method of studying nuclear processes and for the resulting discovery of the pion , a heavy subatomic particle.Powell was born in Tonbridge, Kent, England, the son of a local...

 and coworkers discovered the pion
Pion
In particle physics, a pion is any of three subatomic particles: , , and . Pions are the lightest mesons and they play an important role in explaining the low-energy properties of the strong nuclear force....

in 1947.

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