gamma

SMK-SMAK Bogor

Gamma Rays

Ade syifa maulida; Ayu lintang cahyani; Bahtiar Rifai; Carolus Ivander

3/5/2015

Foreword

Praise and Gratitude Author be to Almighty God's because of an abundance of grace and the blessings of him so we can finish this paper on time. This paper discusses GAMMA RAYS.

In preparing this paper, the author faced a lot of challenges and obstacles but with the help of various parties, it can be overcome. So, the authors thank profusely to all those who have helped in the preparation of this paper, may they get rewarded from Almighty God.

The author realizes that this paper is still far from perfection both of form and material preparation. Criticism from readers are expected so the authors for further refinement of paper.

Hopefully, this paper can provide a benefit to us all.

Bogor, March 2015.

Authors.

Definition

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

A.    Radioactive Decay

The Standard Model explains why some particles decay into other particles. In nuclear decay, an atomic nucleus can split into smaller nuclei. This makes sense: a bunch of protons and neutrons divide into smaller bunches of protons and neutrons. But the decay of a fundamental particle cannot mean splitting into its constituents, because "fundamental" means it has no constituents. Here, particle decay refers to the transformation of a fundamental particle into other fundamental particles. This type of decay is strange, because the end products are not pieces of the starting particle, but totally new particles.

Nuclear Decay

Particle Decay

In this section we will discuss the types of decay, how they happen, and under what circumstances a decay will or will not happen.

B.    Electron Positron Annihilation

Annihilations are of course not decays, but they too occur via virtual particles. In an annihilation a matter and an antimatter particle completely annihilate into energy.

That is, they interact with each other, converting the energy of their previous existence into a very energetic force carrier particle (a gluon, W/Z, or photon). These force carriers, in turn, are transformed into other particles. Quite often, physicists will annihilate two particles at tremendous energies in order to create new, massive particles.

Characteristic of Gamma Rays

—  Radiation of short wavelength and high frequency

—  Not deflected in a magnetic field

—  The greatest energy

—  The strongest  penetration

Radiation of short wavelength and high frequency

Wavelength

•       Gamma rays typically have wavelengths less than 10 picometers (10⁻¹² meter), which is less than the diameter of an atom.

•       Gamma rays are electromagnetic wave which have the highest frequency and the shortest wave

•       This wave has the big energy and can through metal and concrete

Frequency

•       Gamma rays typically have frequencies above 10 exahertz (or >10¹⁹ Hz), and therefore have energies above 100 keV

Sources

Natural Sources

•       Natural sources of gamma rays on Earth include gamma decay from naturally occurring radioisotopes such as potassium-40, and also as a secondary radiation from various atmospheric interactions with cosmic ray particles. Some rare terrestrial natural sources that produce gamma rays that are not of a nuclear origin, are lightning strikes and terrestrial gamma-ray flashes, which produce high energy emissions from natural high-energy voltages. Gamma rays are produced by a number of astronomical processes in which very high-energy electrons are produced. Such electrons produce secondary gamma rays by the mechanisms of bremsstrahlung, inverse Compton scattering and synchrotron radiation. A large fraction of such astronomical gamma rays are screened by Earth's atmosphere and must be detected by spacecraft. Notable artificial sources of gamma rays include fission such as occurs in nuclear reactors, and high energy physics experiments, such as neutral pion decay and nuclear fusion

Astronomical Processes

Gamma-rays from the great beyond

When gamma-rays slam into Earth's upper atmosphere, they emit a faint, blue light. Astronomers can then use this brief burst of light to trace the rays back to some of the most violent phenomena in the universe, including winds streaming off of pulsars and supernova remnants.

In the new study, researchers used the High Energy Stereoscopic System (HESS) — four 13-meter (43 feet) telescopes in Namibia, Africa — to observe the largest star-forming region within the LMC. Over the course of 210 hours, the images lit up with a faint blue light, every photon revealing a single gamma-ray, traceable back to three distinct sources in the LMC.  

"So far, we only knew individual sources in the Milky Way, or observed emission from entire galaxies," Ohm told Space.com in an email. "This is the first time that we discovered more than just one stellar-type gamma-ray source in an external galaxy."

All three sources are related to supernovas, the dramatic explosions of massive stars ending their lives. When a supernova explodes, the outer layers of the expanding material crash into nearby gas and dust, driving a tremendous shock wave. Electrons and other charged particles, accelerated in the rapidly expanding wave, emit gamma-rays.

This image shows an optical view of the Large Magellanic Cloud, a dwarf galaxy neighor of the Milky Way, with H.E.S.S. telescope sky maps showing bright gamma-ray sources found in a new survey.
Credit: H.E.S.S. Collaboration, Optical image: SkyView, A. Mellinger

 

Inventors :

Antoine Henri Becquerel

It was the month of February in the year of 1896. Antoine Henri Becquerel, a French scientist, was conducting an experiment which started with the exposure of a uranium-bearing crystal to sunlight. Once the crystal had sat in the sunshine for a while, he placed it on a photographic plate. As he had anticipated, the crystal produced its image on the plate. Becquerel theorized that the absorbed energy of the sun was being released by the uranium in the form of x-rays.

Further testing of this theory had to be put off for a few days because the sky had clouded up and the sun had disappeared. For the next couple of days he left his sample of uranium in a closed drawer along with the photographic plate.

When the weather had cleared, he returned to the drawer to retrieve his gear. He was surprised to find that the crystal had left a clear, strong image on the photographic plate.

How could this be? There was no source of energy to produce the image! What Becquerel had discovered was that a piece of mineral which contained uranium could produce it's image on a photographic plate in the absence of light. What he had discovered was radioactivity! He attributed this phenomenon to spontaneous emission by the uranium. From hiss experiment,he speculated that the radiation is stronger than the X ray

Paul Ulrich Villard                       

Gamma ray is discovered by French chemist and physicist, Paul Ulrich Villard  in 1900 while studying the radiation emanating from Radium, Polonium and Uranium. He finds that gamma-ray can not be deflected by magnetic fields.

Physicist and chemist Marie Curie was awarded two Nobel Prizes, the first one for her research on radiation and the second one for discovering and studying polonium and radium. She discovered that the strength of the radiation produced by uranium can be measured accurately, establishing a relationship between the intensity of radiation and the amount of uranium contained by the studied compound.

Gamma Ray Mechanism

Radioactive Decay

Alpha Decay (α)

Alpha decay is a type of radioactive decay in which an atomic nucleus emmits an alpha particle and thereby tranforms or ‘decays’ into an atom with a mass number that is reduced by 4 and an atomic number that is reduced by 2.

Alpha particles consist of two protons and two neutrons bound together into a particle identical to a helium nucleus. Its charge is +2 (missing two electrons). It has a kinetic energy about 5 MeV and a velocity of 5% the speed of light.

Alpha decay happens with the following equation:

^A_ZX à ^(A-4)_(Z-2) Y* + ⁴₂α

* = atom is left in an excited state.

Beta Decay (β)

Beta decay is a type of radioactive decay in which a proton is transformed into a neutron, or vice versa, inside an atomic nucleus. This process allows the atom to move closer to the optimal ratio of protons and neutrons. As a result of this transformation, the nucleus emits a detectable beta particle, which is an electron or positron.

The energy released in a typical β-decay compared with alpha emission is very low, with the energy of a single electron being in the order of 1eV (1.6 X 10^-19 J). Most of this energy is in the form of the kinetic energy of the emitted electron

There are two types of beta decay, known as beta minus and beta plus.

Beta minus (β-)

Beta minus (β⁻) decay produces an electron and electron antineutrino.

^A_ZX à ^A_(Z+1) Y* + e- + v + β-

Beta plus (β+)

Beta plus (β⁺) decay produces a positron and electron neutrino; β⁺ decay is thus also known as positron emission.

^A_ZX à ^A_(Z-1) Y* + e+ + v + β+

Gamma Decay

An excited nucleus can decay by the emission of an α or β particle. The daughter nucleus that results is usually left in an excited state. It can then decay to a lower energy state by emitting a gamma ray photon, in a process called gamma decay.

1.    Alpha decay

²³⁸₉₂U à ²³⁴₉₀Th* + ⁴₂α

²³⁴₉₀Th* à ²³⁴₉₀Th + γ

First, ²³⁸₉₂U decays to excited ²³⁴₉₀Th by alpha decay by emmision of alpha particle. Then excited ²³⁴₉₀Th decays to the ground state by emmiting gamma rays.

2.    Beta minus

²³⁸₉₂U à ²³⁸₉₃ Np* + e- + v + β-

²³⁸₉₃ Np* à ²³⁸₉₃ Np + γ

First, ²³⁸₉₂U decays to excited ²³⁸₉₃Np by alpha decay by emmision of positron. Then excited ²³⁸₉₃Np  decays to the ground state by emmiting gamma rays.

3.    Beta plus

²³⁸₉₂ U à ²³⁸₉₁ Pa* + e+ + v + β+

²³⁸₉₁ Pa* à ²³⁸₉₁ Pa + γ

First, ²³⁸₉₂U decays to excited ²³⁸₉₁ Pa by alpha decay by emmision of positron. Then excited ²³⁸₉₁ Pa decays to the ground state by emmiting gamma rays.

Electron-positron Annihilation

Electron–positron annihilation occurs when an electron (e−) and a positron (e+, the electron's antiparticle) collide. The result of the collision is the annihilation of the electron and positron, and the creation of gamma ray photons.

Electron-positron Annihilation equation:

e− + e+ → γ 

Application

There are many aplication of gamma rays like:

Fermi Gamma ray space telescope

Compton gamma ray observatory

Energetic gamma ray experiment telescope

Mutation gen of sorghum

Gamma camera

Description for gamma camera:

·         Definition

Gamma Camera Equipment is a tool used in nuclear medical depiction or called by nuclear medicine , to see and analyze or diagnose overview of the human body by detecting the radiation beam from a radio isotope that is inserted into the patient's body

·         Main parts

Gamma Camera Equipment consists of three main parts: the detection , imaging parts and mechanical parts . Detection section consists of crystal scintillator detector NaI ( Tl ) , the initial amplifier and signal processing part , of this section resulting weighted signal position X , Y and Z. The imaging section consists of interface modules and software acquisitions in the computer.  mechanical part consists of several mechanical systems and mechanical propulsion control .

·         Method

o   First,patient  are given clinical management base on the case he felt, then the patient will be placed on the patient table , detector will be directed to the organ examined .

o   The detector will detect particle radiation that emitted by the isotope that accumulate in the organs .

o   Pulse electricity generated by the detector will be amplified by the amplifier circuit early , by the pulse signal processing section in the form of weighted signal -dimensional position X and Y.

o   So  the pulse energy that correspond to the weight of the isotopes are passed , by engineering logic is formed into a signal pulse signal Z. X , Y and Z was generated , is fed to the input interface module imaging to be converted into digital signals that can be understood by software acquisitions on the computer .

o   The results of the data recording will be imaged by acquisition software Medic view be patient organ image , then the image of this organ performed using analysis  , image data processing , file storage , reporting and sending files to physicians and other parts for further treatment .

Conclusion

References