Gamma rays how does it work

This object is among the most distant objects ever detected. Scientists can use gamma rays to determine the elements on other planets. When struck by cosmic rays, chemical elements in soils and rocks emit uniquely identifiable signatures of energy in the form of gamma rays. These data can help scientists look for geologically important elements such as hydrogen, magnesium, silicon, oxygen, iron, titanium, sodium, and calcium. The gamma-ray spectrometer on NASA's Mars Odyssey Orbiter detects and maps these signatures, such as this map below showing hydrogen concentrations of Martian surface soils.

Gamma rays also stream from stars, supernovas, pulsars, and black hole accretion disks to wash our sky with gamma-ray light. These gamma-ray streams were imaged using NASA's Fermi gamma-ray space telescope to map out the Milky Way galaxy by creating a full degree view of the galaxy from our perspective here on Earth. The composite image below of the Cas A supernova remnant shows the full spectrum in one image.

Gamma rays from Fermi are shown in magenta; x-rays from the Chandra Observatory are blue and green. The visible light data captured by the Hubble space telescope are displayed in yellow. Infrared data from the Spitzer space telescope are shown in red; and radio data from the Very Large Array are displayed in orange. Gamma Rays. The gamma radiations are constituted by photons, characterized by their energy, inversely proportional to their wavelength.

The gamma rays come from the nuclei during the nuclear reactions, it is monoenergetics for a given characteristic reaction. Natural gamma radiation sources can be easily divided into three groups according to their origin. The first group includes potassium 40 K with a half-life of 1.

The second group includes radioactive isotopes from the first group. Those have half-lives ranging from small fractions of a second to 10 4 to 10 5 years.

The third group will include it isotopes created by external causes, such as the interaction of cosmic rays with the earth and its atmosphere. Such media are extremely rare, and this process is not fundamental to the production of this radiation.

Inverse Compton effect: During a collision with low energy photon, a relativistic electron can transfer to it a significant part of its energy, the photon can then have an energy of MeV.

The Synchrotron radiation: A relativistic electron spiraling through the force lines of a magnetic field radiates electromagnetic energy. But, by radiating the electrons lose energy: their lives are therefore limited. Bremsstrahlung or braking radiation: An electron passing near a nucleus is influenced by its Coulombian field.

The deceleration of the electron is accompanied by a loss of energy in the form of gamma radiation when the electron has a relativistic speed. Collision between a proton and an antiproton; if the antimatter exists in the Universe, the observation of the gamma radiation produced is a method for detecting it. Nucleus de-excitation: Just like an atom or a molecule, a nucleus has energy levels whose transitions between the least excited levels give rise to gamma radiation. Such nucleus de-excitation may occur either during the interaction of a nucleus with neutrinos or during certain thermonuclear reactions.

Unlike charged particles that gradually loses up their energy to matter, when gamma rays traverse matter, some are absorbed, some pass through without interaction, and some are scattered as lower energy photons. Electromagnetic radiation vanishes brutally as a result of interaction. We can no longer talk about a slowdown.

We have to introduce the attenuation notion. Although a large number of possible interaction mechanisms are known, when monoenergetic gamma rays are attenuated in the matter, only four major effects are important: photoelectric effect, Compton effect, elastic or Rayleigh scattering and pair production with a threshold energy of keV.

The probability which has a photon of energy given to undergo an interaction during the penetrating in a given material is represented by the attenuation coefficient for this material absorber. The more range of gamma rays in the absorber is long, the more the interaction probability increases. The attenuation coefficient is the sum of coefficients of the various interaction modes Compton, photoelectric, pair production , the proportion of each of these effects varying with the radiation energy and nature of the absorber.

The total linear attenuation coefficient can be decomposed into the contributions from each above described mode of photon interaction as:. Although linear attenuation coefficients are convenient for engineering applications and shielding calculations, they are proportional to the density of the absorber, which depends on the physical state of the material.

The mass attenuation coefficient of a compound or a mixture can be, therefore, calculated from the mass attenuation coefficient of the components [ 1 ]. Figure 1 shows the linear attenuation of solid sodium iodide, a common material used in gamma-ray detectors. Linear attenuation coefficient of NaI showing contributions from photoelectric absorption, Compton scattering, and pair production [ 2 ]. His relation is:. The linear attenuation coefficient is inversely proportional to a quantity called a half-value layer HVL , which is the material thickness needed to attenuate the intensity of the incident photon beam to half of its original value.

From Eq. The HVL of a given material thus characterizes the quality penetrance or hardness of a gamma beam. Figure 2 shows the relationship between the linear attenuation coefficient and the HVL for a soft tissue [ 3 ]. Relationship between the linear attenuation coefficient and the HVL for a soft tissue.

Apart from the use of nuclear energy for the supply of electricity, the applications of radioactivity are numerous in many areas: medical physics, earth sciences, industry and preservation of cultural heritage.

The properties used for these various applications are: Time decline of radioactivity. A few months after the discovery of X-rays, there is over a century, it has become clear that biological action radiation could be used in the treatment of cancers. Cancers cells divided more quickly are more sensitive, than normal cells to ionizing radiation. By sending these cells a certain dose of radiation, it is possible to kill them and eliminate the tumor.

Irradiation of surgical and food material: Irradiation is a privileged means to destroy micro-organisms fungi, bacteria, virus…. As a result, many applications radiation exists for sterilization of objects. If you could see gamma-rays, these two spinning neutron stars or pulsars would be among the brightest objects in the sky.

This computer processed image shows the Crab Nebula pulsar below and right of center and the Geminga pulsar above and left of center in the "light" of gamma-rays. The Crab nebula, shown also in the visible light image, was created by a supernova that brightened the night sky in A. In , astronomers detected the remnant core of that star; a rapidly rotating, magnetic pulsar flashing every 0. Perhaps the most spectacular discovery in gamma-ray astronomy came in the late s and early s.

Detectors on board the Vela satellite series, originally military satellites, began to record bursts of gamma-rays -- not from Earth, but from deep space! Today, these gamma-ray bursts, which happen at least once a day, are seen to last for fractions of a second to minutes, popping off like cosmic flashbulbs from unexpected directions, flickering, and then fading after briefly dominating the gamma-ray sky.

Gamma-ray bursts can release more energy in 10 seconds than the Sun will emit in its entire 10 billion-year lifetime! So far, it appears that all of the bursts we have observed have come from outside the Milky Way Galaxy. Energy is released because the combined mass of the resulting particles is less than the mass of the original heavy nucleus. Other sources of gamma rays are alpha decay and gamma decay.

Alpha decay occurs when a heavy nucleus gives off a helium-4 nucleus, reducing its atomic number by 2 and its atomic weight by 4. This process can leave the nucleus with excess energy, which is emitted in the form of a gamma ray. Gamma decay occurs when there is too much energy in the nucleus of an atom, causing it to emit a gamma ray without changing its charge or mass composition. Gamma rays are sometimes used to treat cancerous tumors in the body by damaging the DNA of the tumor cells.

However, great care must be taken, because gamma-rays can also damage the DNA of surrounding healthy tissue cells. One way to maximize the dosage to cancer cells while minimizing the exposure to healthy tissues is to direct multiple gamma-ray beams from a linear accelerator, or linac, onto the target region from many different directions. This is the operating principle of CyberKnife and Gamma Knife therapies. Gamma Knife radiosurgery uses specialized equipment to focus close to tiny beams of radiation on a tumor or other target in the brain.

Each individual beam has very little effect on the brain tissue it passes through, but a strong dose of radiation is delivered at the point where the beams meet, according to Mayo Clinic.