Nobody downloaded yet

Positron Annihilation - Essay Example

Comments (1) Cite this document
Summary
When a low energy positron collides with a low energy electron, there is an emittance of two gamma rays in the opposite direction. This phenomenon, also called positron annihilation, results in two gamma rays at 180° and with 0.511 MeV of energy moving in opposite directions…
Download full paperFile format: .doc, available for editing
GRAB THE BEST PAPER97.7% of users find it useful
Positron Annihilation
Read TextPreview

Extract of sample
"Positron Annihilation"

Download file to see previous pages The gamma rays released can be detected and measured. A source of positrons and a detector for gamma radiation is required to study positron annihilation. The positron annihilation experiment involves the use of two detectors placed at an angle anywhere between 160-200°. 22Na and 60Co are used in the experiment. The scintillation detectors are used not only for the detection but also measurement of gamma radiation. Electronic counters are used for investigating the annihilation events. The observations made regarding the annihilation events in case of 22Na were found to be in agreement with theoretical considerations. The angular distribution of gamma rays from a 60Co source was also investigated. This part of the experiment provided rather convoluted information. The gamma rays resulting from annihilation events were found to be more spread rather than peaked. Such a behavior can be attributed to the changes in the angular momentum of the 60Co nucleus as it progresses through its unstable, excited state. Observations made in this experiment are in agreement with theoretical observations. The experiment demonstrates back-to-back emission of annihilation photons, peaking at 180°. The coincidence events for 22Na were found to be more reliable than for 60Co.
Introduction.
Collision of a low energy positron by an electron of low energy results in their annihilation, causing the production of gamma ray photons. They are responsible for carrying away the momentum and energy of the pair. e? + e+ > ? + ? These photon rays do not have enough mass and energy to result in the production of heavier particles. The process of positron annihilation satisfies certain laws of conservation such as the conservation of electric charge, conservation of total energy, and conservation of momentum (both linear and angular). The conservation of linear momentum and energy does not accommodate the creation of one photon but rather two gamma rays. The two gamma rays ensuing from the positron annihilation move in the opposite direction. The energy possessed by these two gamma rays is approximately 0.511 MeV (Mega electron Volts). Figure 1: Feynman diagram of positron annihilation (Booklet, 2012) The two gamma rays are created because there is no momentum in the system during annihilation as both the electron and the positron come to rest for a short moment. The momentum of the system cannot be conserved if only one proton is created in the process. The collective amount of 1.022 MeV energy of the two gamma rays that are moving in opposite directions satisfies the conservation of the momentum and energy. The positron used in the annihilation process is often obtained from the decay of a proton into a neutron, resulting in the release of a positron and a neutrino. Figure 2: Emission of positron and its annihilation (PET, 2007) The gamma rays released in the process of positron annihilation are both detectable and measurable. Time coincidence counting is a technique that is employed for studying radioactive materials. With this technique, radioactive materials can be detected and identified. The disintegration rates of the radioactive materials can also be calibrated with this technique. The absolute activity of the materials can be measured by counting the radiation events occurring in the radioactive material. The radiation could comprise of beta and gamma rays and can be easily measured using the technique. During the decay of an unstable nucleus, several photons may be emitted in a cascade. 60Co nucleus is one such example. In 22Na, the decay product, which is a positron, annihilates in the source itself. To induce positron annihilation or study it, there is a need for a positron emitter. Various materials have been used ...Download file to see next pagesRead More
Cite this document
  • APA
  • MLA
  • CHICAGO
(“Positron Annihilation Essay Example | Topics and Well Written Essays - 2500 words”, n.d.)
Positron Annihilation Essay Example | Topics and Well Written Essays - 2500 words. Retrieved from https://studentshare.org/physics/1403482-positron-annihilation
(Positron Annihilation Essay Example | Topics and Well Written Essays - 2500 Words)
Positron Annihilation Essay Example | Topics and Well Written Essays - 2500 Words. https://studentshare.org/physics/1403482-positron-annihilation.
“Positron Annihilation Essay Example | Topics and Well Written Essays - 2500 Words”, n.d. https://studentshare.org/physics/1403482-positron-annihilation.
  • Cited: 0 times
Comments (1)
Click to create a comment or rate a document
ot
ottis25 added comment 6 days ago
Student rated this paper as
This essay was always my weak point. I could never complete it well. Still, after I found this particular essay, I understood how it should be completed. So, I performed my research afterward and completed the essay in several hours, instead of days as it was previously.
CHECK THESE SAMPLES - THEY ALSO FIT YOUR TOPIC
Norman Friedman. The Waters of Annihilation: Symbols and Double Vision in To the Lighthouse
...?Summary of Norman Friedman, “The Waters of Annihilation: Symbols and Double Vision in ‘To the Lighthouse’.” Norman Friedman’s article (1975) on Virgnia Woolf’s novel To the Lighthouse (1927) is a work of literary criticism which seeks to interpret and explain aspects of this celebrated work of fiction. As the title of the article suggests, it has two main objectives. The first objective is an attempt to illuminate one of the main themes of the book, which is indicated in the phrase “The Waters of Annihilation.” The phrase is a quotation from chapter seven of the novel itself, describing the thought processes of the character Lily as she reflects on how her attitudes are changing towards Mrs Ramsay. The second...
3 Pages(750 words)Essay
Relevance of Combining MRI and PET Modalities
...as disadvantages, it is seen that the former overweighs the latter, thus it becomes clear that combining the two modalities into a single system is highly relevant in the modern clinical sphere. Definitions: Magnetic Resonance Imaging is among the most popularly deployed clinical diagnostic tools, which works by making use of a “strong magnetic field” to produce “high- resolution anatomical information with excellent soft-tissue contrast” (Metcalfe et al 2013: 2). Positron Emission Tomography is the method that determines “biochemical and physiological processes in vivo” in a quantitative way with the help of “radiopharmaceuticals labeled with positron emitting radionuclides as 11C, 13N, 15O and 18F and by...
8 Pages(2000 words)Essay
Antimatter
...is, however, that antimatter cannot simply be harvested or mined. It has to be made, and making it requires vastly more energy than annihilating it produces. All the antimatter produced at CERN in a year would provide barely enough energy to power a light bulb for a few seconds." (Gordon Fraser) Antimatter Applications Antimatter may be the stuff of science fiction but at laboratories like CERN it is a commonplace tool for research. In hospitals and industry too, antimatter is in everyday use for diagnosis. Positron Emission Tomography, PET, for example relies on antimatter. It works by attaching radioactive atoms that emit positrons - anti-electrons - to biological tracer molecules that find...
4 Pages(1000 words)Essay
Brain Imaging Technologies
...BRAIN IMAGING TECHNOLOGIES SUBMITTED INTRODUCTION Brain imaging technologies are used to measure brain activity. This paper brings to light Positron Emission Tomography (PET) scanning, a sophisticated imaging technique alongside functional Magnetic Resonance Imaging (MRI) technique, event related potential, single cell recording, visual-spatial sketchpad and central executive. The capability to image the human body, equally to spot disease and direct surgery, has become cardinal to the implementation of medicine. In the resulting time, radiology has burgeoned to cover the use of many faces of electromagnetic radiation in making increasingly dominant diagnostic images of the body and diseases. The variety of energies and...
7 Pages(1750 words)Essay
Positron emission tomography
...Introduction to PET Positron emission tomography (PET) is a nuclear medication imaging method that generates a three-dimensional representation or image of functional development in the body. The arrangement detects couple of gamma rays emitted circuitously by a positron-emitting radionuclide also known as tracer, which is then commenced into the body on an organically active molecule. Three-dimensional imagery of tracer absorption within the body is then assembled by computer analysis. In recent scanners, three dimensional imaging is often attained with the support of a CT X-ray scan performed on the patient for the duration of the same session, in the similar machine (H.Jadvar, 2004). Positron...
4 Pages(1000 words)Essay
Positron Emission Tomography
...Emission Tomography (ET) Emission Tomography is a medical imaging branch that comprises of Position Emission Tomography Techniques (PETT) and the Single Photon Emission Computed Tomography (SPECT). The Emission Tomography images the characteristics of a physiological body by use of radioactive materials. For example, the metabolism of glucose, concentration of receptors and the flow of blood in the body can be spatially distributed by the Emission Tomography. In addition, Emission Tomography is used to locate areas affected by coronary artery in the heart, to identify tumors in the body, and to analyze drug’s influence in the brains of persons. Radionuclide Imaging Principles Emission Tomography is applicable in the diagnosis of human... Tomography...
1 Pages(250 words)Essay
Positron emission tomography
...to be halved. Positrons refer to the subatomic molecules that are equal in mass to an electron with characteristic of carrying a positive charge. When the positron decay (β+), its nuclei changes one of the core protons (p) to a neutron (n), while emitting positron (β+) to attain a positively charged nature referred to as neutrino (ν). Upon the release from the initial nucleus, the high positron moves across a few millimeters through the tissue until it attains thermalization, during the acquisition of thermal energy, the positrons arrive at thermal energies. They begin connecting with electrons either through annihilation that produce two 511 keV...
10 Pages(2500 words)Essay
The Issue of Death
...unconsciousness as a result of failing to become self-conscious during the prior time to sleep. Death is equally the same as sleeping with the only variance resulting from one degree evidenced through the failure of regaining unconsciousness. A counter argument to the concept that death is the same as sleep or a form of deep sleep attributes death as annihilation to indicate a form of extinction, eradication or a form of extermination. The concept of annihilation towards death is considered basing on the fact that unlike sleeping where the person awakes, it never happens with a dead person. Once death strikes, the person is no longer there and it is impossible to regain the earlier form of that person. If in...
2 Pages(500 words)Essay
Skills Available For Acquisition and Career Building Strategies in Directing a Film
9 Pages(2250 words)Case Study
The Life Cycle of the Photon
5 Pages(1250 words)Research Paper
sponsored ads
We use cookies to create the best experience for you. Keep on browsing if you are OK with that, or find out how to manage cookies.
Let us find you another Essay on topic Positron Annihilation for FREE!
logo footer
Contact us:
+16312120006
Contact Us Now
FREE Mobile Apps:
  • StudentShare App Store
  • StudentShare Google play
  • About StudentShare
  • Testimonials
  • FAQ
  • Blog
  • Free Essays
  • New Essays
  • Essays
  • Miscellaneous
  • The Newest Essay Topics
  • Index samples by all dates
Join us:
Contact Us