Paper Example on Radioactivity

Abstract

The aim of this research was to find out whether the problems occurring during the measurement of background radiation and its evaluation is related to the dosimeters, or in incorrect measurement, incorrect calculations or incorrect interpretation of results. In order to achieve this aim, background radiation was measured and evaluated using all the available dosimeters - possible problems with calibration - at the same place in completely different days. The influence of environment on the measured values were also evaluated using the measured at three different locations several times. The results show differences in dosimeter readings for the different locations. While calibration problems are possible, the differences are more likely to be due to the environmental factors such as humidity, temperature, and ambient atmospheric pressure as well as external factors like the tram.

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Introduction

Radioactivity, the act of spontaneous release of radiation by an unstable atomic nucleus, is a widespread activity that occurs both naturally and artificially (Mann et al., 1991p.4). Various types of this spontaneous activity (known as decay) result in different types of emissions such as alpha, beta, and gamma particles. An alpha particle is made up of two protons and two neutrons (i.e. identical to a helium nucleus). The nucleus initially discards the alpha particle by quantum mechanical processes and then is repelled further by electromagnetism because both the nucleus and the alpha particle have the same charge (positively charged). Quantum mechanical processes alter the original atom into a different element. Because the atom discards a particle, its atomic number is decreased by two and the mass number by four. For instance, uranium-238 decays to thorium-234. The resulting isotope may also be radioactive otherwise known as a radioisotope which decays further by either beta decay or gamma decay. Beta decay results from the transformation of an excess neutron into an electron, a proton, a positron, a neutron, a neutrino, or an antineutrino. When a nucleus undergoes alpha or beta decay, it is left with excess energy i.e. it is in an excited state. The nucleus of this excited atom loses the excess energy by emitting a gamma ray. Gamma radiation is more penetrating than the alpha and beta radiation and can penetrate through several centimeters of lead. The radiation with the second most penetrating power is beta radiation. However, while alpha has the least penetration, it also does the most damage to materials it interacts with. The figure below shows the different modes of radioactivity.

Radiations in the higher frequency spectrum such as beta and gamma particles are ionizing radiations i.e. carries enough energy such that upon interaction with an atom it liberates tightly bound electrons from the orbit of the atom thereby ionizing or charging it. Because they carry energy, these particles can charge atoms as they interact with them either directly (through alpha and beta particles) or indirectly (charged particles release energized particles of the medium) via coulombic forces. These properties of ionizing radiations are widely applied to diagnostic radiation and radiotherapy in nuclear medicine. They are also applied in nuclear power production.

However, the ionization is also known to cause adverse health effects as they are risk factors for cancer. In particular, radioactive emissions may cause irreversible changes to the genetic constitution (DNA) as shown in the Hiroshima and Nagasaki bombing victims. Specifically, exposure above the recommended irradiation levels is associated with risk of mainly cancer and leukemia. Therefore, it is important to monitor the levels of radiation in the environment to ensure public safety from the destructive effects of ionizing radiation. Dosimeters are the devices used to detect and measure the levels of radiation, which are in turn influenced by various technical, environmental, and human factors. As such, dosimetric precision and accuracy is critical in determining the amount of radiation dose received from background radiation exposure.

Aim of the Study

The aim of this study was to measure the background radiation in the environment using different dosimeters. By taking several measurements using the same type of dosimetric devices, a more accurate value of background radiation can be determined through computation of average values. The study also demonstrates how environmental factors affect radiation measurement as well as explains methods of reducing measurement errors.

Literature Review

Ionization RadiationIonizing radiation refers to the radiation that carries enough energy such that upon interaction with an atom it liberates tightly bound electrons from the orbit of the atom thereby ionizing or charging it (Stathakis, 2010 p.1375). Ionizing radiation generally occurs in two forms i.e. particles and waves. There are various forms of electromagnetic radiation including radio waves, heat waves, infrared light, visible light, ultraviolet light, X rays and Gamma rays (Khan and Gibbons, 2014 p.12). Not all electromagnetic radiations are ionizing. In fact, only those with a high frequency such as X-ray and Gamma rays cause an ionizing effect because short wavelength, high-frequency waves carry high energy than the long wavelength, low-frequency waves.

There is a great variety of ionizing radiations. Most of the more familiar types such as radio waves and visible light exhibit "wave-like" behavior in their interaction with matter (Khan and Gibbons,2014 p.12). Electromagnetic radiation occurs in the form of a wave packet called a photon. However, particulate radiation consists of atomic or subatomic particles such as electrons and protons that carry energy in the form of kinetic energy (Charlesby, 2013p.6). In other words, the electromagnetic radiation traveling through space at the speed of light carries energy by oscillating electrical and magnetic fields.

Ionizing radiation can charge atoms either directly or indirectly. Direct ionization takes place through alpha and beta particles because they carry a charge and interact directly with electrons of the atoms through coulombic forces (Ott et al., 2014 p.374). Therefore, direct ionization is attributed to electrons, protons, alpha particles and heavy ions (Popruzhenko, 2014). However, electromagnetic radiation from neutral particles can ionize matter indirectly because it does not carry an electrical charge (Marcu, bezak, & Allen, 2014). The resulting ionization is due to the charged particles that are produced during collisions with the nucleus of the atom. Indirect ionization occurs in two steps whereby first, the charged particles are released into the medium (photons release electrons or positrons, neutrons release protons or heavier ions), and then the released charged particles deposit energy into the medium through direct Coulombic interactions with orbital electrons of the atoms in the medium (Tawaraet al, 1987). Gamma and X rays also do not carry any electric charge and interact with electrons through coulombic forces thereby ionizing matter indirectly (Bushberg et al., 2011 p.30).

Both directly and indirectly ionizing radiations are increasingly applied in medical therapy mainly for malignant disease (Bushberget al. 2011 p.899). Diagnostic radiology, radiotherapy, and nuclear medicine use ionizing radiation to diagnose and treat diseases. The most commonly used types of ionization photon radiation in medicine include characteristic X rays, Bremsstrahlung, rays, and annihilation quanta. X rays result from the movement of electrons between atomic shells, rays result from nuclear transitions, Bremsstrahlung result from electron-nucleus Coulombic interactions, and annihilation quanta arise from positron-electron annihilation.

Radioactivity

Radioactivity refers to the spontaneous release of radiation by an unstable atomic nucleus (Mann et al., 1991 p.4). This act of releasing some energy occurs in order to achieve a more stable configuration (Mann et al., 1991 p.5). A nucleus that has...