Gamma Rays?

Question

What are the uses and applications of them. How do gamma rays affect our every day lives?

Answer 1

Gamma rays (often denoted by the Greek letter gamma, γ) are an energetic form of electromagnetic radiation produced by radioactive decay or other nuclear or subatomic processes such as electron-positron annihilation.

Uses:

The powerful nature of gamma rays have made them useful in the sterilization of medical equipment by killing bacteria. They are also used to kill bacteria and insects in foodstuffs, particularly meat, marshmallows, pie, eggs, and vegetables, to maintain freshness.

Due to their tissue penetrating property, gamma rays / X-rays have a wide variety of medical uses such as in CT Scans and radiation therapy (see X-ray). However, as a form of ionizing radiation they have the ability to effect molecular changes, particularly to DNA, giving them the potential to cause cancer.

Despite their cancer-causing properties, gamma rays are also used to treat some types of cancer. In the procedure called gamma-knife surgery, multiple concentrated beams of gamma rays are directed on the growth in order to kill the cancerous cells. The beams are aimed from different angles to focus the radiation on the growth while minimising damage to the surrounding tissues.

Gamma rays are also used for diagnostic purposes in nuclear medicine. Several gamma-emitting radioisotopes are used, one of which is technetium-99m. When administered to a patient, a gamma camera can be used to form an image of the radioisotope's distribution by detecting the gamma radiation emitted. Such a technique can be employed to diagnose a wide range of conditions (e.g. spread of cancer to the bones).

Gamma ray detectors are also starting to be used in Pakistan as part of the Container Security Initiative (CSI). These US$5 million machines are advertised to scan 30 containers per hour. The objective of this technique is to pre-screen merchant ship containers before they enter U.S. ports.

Answer 2

Gamma rays are very energetic photons, with energies between 1 MeV - 10 GeV. One of astronomy's most exciting branches, gamma ray astronomy provides a tool to observe the most dynamic, highest energy processes in the universe. However, for several reasons, it is also among the least well explored.
The first reason is that gamma ray observations must be done above this atmosphere. This is because gamma rays interact strongly with atmospheric particles. In addition, some gamma rays are actually produced in the atmosphere by cosmic ray interactions.

Another reason for the slow developement of gamma ray astronomy is that, while their energies are higher, gamma ray photons are much rarer than lower energy photons. Extremely sensitive instruments and long integration times are needed to detect sources.

The third complication of gamma ray observing is that there is abundant gamma ray emission from cosmic ray interactions with material in our own galaxy. In many regions, this diffuse emission is much greater than source fluxes. Maps of this emission have been made, but because gamma ray astronomy is such a young field, the maps have large errors and undergo constant revisions.

One instrument which is attempting to combat these difficulties is the Compton Gamma Ray Observatory. This instrument was launched in April of 1991 and, in its roughly 5 years of operation, has increased our knowledge of gamma ray astronomy by several orders of magnitude. There are 4 instruments aboard this observatory. COMPTEL, which detects gamma rays betwen 0.7 and 30 MeV, is the lowest energy intrument. OSSE, the Orientation Scintillation Spectronometer Experiment, is sensitive to gamma rays in the energy range 0.05 - 10 MeV. EGRET, the Energetic Gamma Ray Experiment Telescope, detects gamma rays in the energy range 20 MeV - 30 GeV. The final instrument aboard the observatory, BATSE (Burst and Transient Source Experiment), is sensitive to transient events with energies between 0.02 and 100 MeV.

In its first few years of operation, the EGRET instrument completed an entire sky survey, which detected 128 sources. Some of these objects have been identified with known sources. The LMC is the only 'normal' galaxy detected by EGRET. However, 50 EGRET sources have been identified as active galactic nuclei (AGN). These galaxies are much more luminous than normal galaxies and emit a much higher proportion of radiation at high energies. It's possible that these objects are powered by supermassive black holes, but the exact emission mechanisms that make them so much different from normal galaxies are unclear. Only 5 of the roughly 700 known pulsars have been detected by EGRET. Because pulsar emission mechanisms are somewhat of a mystery, it is not clear what makes these 5 pulsars special. They are all relatively young, implying that a pulsar's gamma ray luminosity declines with age. Finally, there are 72 unidentified EGRET sources. The properties of some of these are like those of AGN, while others seem more similar to pulsars. Some unidentified sources can not be easily identified with either of these source populations.

Answer 3

They are mainly used in cancer imaging with a device called PET (positron electron tomography) using the emission of gamma rays emitted by artificial elements introduced in tumors.
They can also be used as curating devices for cancer as the gamma-rays emitted by a cobalt Co 60 apparatus
However, usually, they are harmful since their radioactivity so their use is limited to serious diseases