Radioactivity


 * RADIOACTIVITY**

How detection of radioactivity may be used to protect humans and the environment. What is radioactivity? Radioactivity is the spontaneous disintegration of certain nuclei to produce energetic emissions. The two main types of radioactive emissions are called alpha and Beta radiation. After a radioactive nucleus decays by alpha or beta decay, it may be left in an excited state. Gamma rays (which are a type of electromagnetic radiation) are emitted in order to de-excite the excited nucleus. So, commonly radioactivity in used to describe the emission of alpha, beta and gamma radiation. Because of the energy of these radiations, they may cause damage to biological systems such as humans.There is natural radioactivity as well as cosmic radiation in the environment. This is called natural background radiation. When looking for radiation sources in the environment, one must take into account the natural background radiation. The radiations described above – alpha, beta and gamma rays – can be blocked by various types of materials. Alpha and beta particles because of their electrical charge and lower energies they do not penetrate deeply into most materials. For example, a sheet of paper may be used to shield most alpha particles. Gamma rays on the other hand, are electromagnetic radiation without electrical charge; therefore, gammas penetrate materials more deeply than alpha and beta particles. This means that gamma radiation in the environment pose a greater risk to humans because they can penetrate through the skin, whereas alphas and betas cannot penetrate through the skin. Therefore, in this research project, we have decided to focus on the detection of gamma rays since they pose the greater threat in terms of external environmental exposure. 1. First, go the park and hide the different radiation sources in various locations. We went to the Park and hid our radiation sources in various locations in the Park. 2. Then, go far from the places that the radiation sources were hidden and measure the natural background radiation of the park; 3. Then record the background does rate ;We recorded the Background dose rate; 4. Systematically measure around the park and compare measure dose rate with the background dose rate. 5. If the measured dose rate is significantly higher than the background dose, dig around the area to reveal the radiation source. 6. Go back to the school to investigate the radioactivity around the school environment. 7. Measure the dose rate outside the school environment. 8. Make a map of each floor in the school and the rooms inside the school. Measure the radiation levels in each room of the school. 9. Use a vacuum pump to collect dust outside the school to see if the dust contains radioactivity. 10. Before, one looks at the radioactivity of the dust one should graph the background radiation of the room one is conducting the experiments it. 11. Carry out the investigation of the radiation in dust overnight. The detector should be connected to a graphing machine. 12. The graphing machine should plot the count rate against time at one minute intervals. Thus, observing the exponential decay of radioactivity. 13. When, one comes back to the school one should make one more table. This table should be the lifetime of the dust measured for radioactivity. 14. Analise, the graphs and the results.
 * Research Question:**
 * Introduction:**
 * Experimental Design**
 * Experimental equipment:**
 * Sodium Iodide Gamma-ray detector;
 * Geiger-Muller counter;
 * Uranium ore (Radiation source);
 * Lantern Mantel (Radiation source emitting from Thorium 232)
 * Other Radiation sources from the Physics Laboratory
 * Vacuum pump
 * Experimental procedure:**

Natural radiation Background in the school; Map of school rooms showing radiation levels.
 * Experimental Results:**

Radiation levels of radioactive sources used in the experiment; Radiation Source || Dose Rate nSv/h || Comments || Uranium ore || 500 || Source of radiation measured: Radon 226 which is a daughter of U238. || Lantern Mantel || 700 || Source of radiation: Thorium 232 ||

The first graph is the graph of the background radiation of the physics lab in Danube International School. The graph shows the radiation counts per minute. This was done over a period of 5 minutes. There are about 10 counts per minute in the background graph. The Second Graph is a life time graph of the radiation decay of the dust. This was done over a 30 minute period. This graph shows the radiation counts per minute with the radiation source dust, while the previous graph did not show this. The lifetime graph shows the half- life and this is graphed. The curve is an exponential curve and the formula for this is on the graph. There are 3-4 counts per minute.
 * Graphs**


 * Analysis of Results and Conclusions:**
 * Radioactive decay is a statistical process. When measurements are taken – whether it is length, weight, volume etc…there are always errors. Sometimes the error is from the measuring instrument, sometimes it is from humans, sometimes it is from both.
 * In the same way, when we measure radioactive counts, there are errors. One of the errors is the statistical error in the counts due to the unpredictability of when and how the material decays. This statistical error is the square root of the counts. So if we take a count rate of 100 counts, the error will be 10 counts (which is the square root of 100). This means that the count could be number from 90 to 110.
 * Looking at the counts in the various rooms in the school, it is clear that they are all the same (statistically). Therefore, we can say that all the rooms in the school have the natural background. There are no hidden radiation sources (such as radioactive building materials) in the school. The school is safe.

[1] However, note that if someone eats an alpha source, the damage is great because of the electrical charge of the alphas.

Radiation dosimeter is the calculation of how much radiation is absorbed as a result of exposure to different types of radiation, and the effect that this has on different parts of the body. This depends on the type of radiation which is (α, β, γ, and X). Exposure is a measure of ionizing radiation you would be exposed to in a particular environment, based on the number of ions produced by kilogram in the air. This quantity is on used for X, and γ.
 * Radiation in medicine (Physics Point of View)**

X = Q/m Q = the total charge of all the positive ions produced m = the mass of air in the room Unit = C kg-1 Different types of radiation have different biological effects, the absorbed dose is the multiplied by a factor that is independent on the type of radiation. α is the most damaging, so the factor is 20, where for β, γ, and X are 1. This factor is called the QUALITY FACTOR.
 * Source || Dose mSv ||
 * Background Dose in 1 year || 3 ||
 * Ankle X ray || 0.02 ||
 * CT scan of head || 2 ||
 * Barium meal || 8 ||

Absorbed Dose (D) formula D = E/m E = Total energy absorbed m = Mass of tissue Unit = J Kg-1 Dose Equivalent (H) formula

H = Q x D Q = Quality Factor D = Absorbed Dose Unit = J Kg-1 (Sv)

Sources IB physics HL book (Medical physics)

Mutations occur randomly, that is to say that any gene can undergo mutation at any time. The rates at which mutations occur vary between organisms. Mutation rate can be significantly increased by the effects of high energy electromagnetic radiation such as ultra-violet light X-rays and gamma rays. High energy particles, such as a and β particles, neutrons and cosmic radiation, are also mutagenic, that is cause mutations. A variety of chemical Hyde, cochineal, certain constituents of tobacco and an increasing number of drugs, food preservatives and pesticides, have been shown to be mutagenic. High energy radiation from a radioactive material or from X-rays is absorbed by the atoms in water molecules surrounding the DNA. This energy is transferred to the electrons which then fly away from the atom. Left behind is a free radical, which is a highly dangerous and highly reactive molecule that attacks the DNA molecule and alters it in many ways. Radiation can also cause double strand breaks in the DNA molecule, which the cell's repair mechanisms cannot put right. At high radiation doses, mutations (defined as damage to cellular DNA), can occur in cells of the embryo or fetus. As a consequence, developmental abnormalities or cancer may develop. Such occurrences are unusual (for instance in a pregnant cancer patient given radiation treatments). At low doses that are encountered in almost all medical x-ray and nuclear medicine procedures, the probability of inducing mutations in cells in the developing embryo or fetus is so small that risks of developmental abnormalities from radiation exposure are insignificant. There is some evidence that even the small doses used in diagnostic x-ray procedures may increase the risk of leukemia and other childhood cancers. However a causal link between diagnostic radiation exposure of the embryo/fetus and childhood cancer has not been established. Although diagnostic x-ray and nuclear medicine procedures pose little, if any, risk to the embryo/fetus, it is generally recommended that diagnostic radiation tests be postponed during pregnancy if possible to avoid any unnecessary risk.
 * Mutagens**

Mutations in DNA sequences generally occur through one of two processes:
 * 1) DNA damage from environmental agents such as ultraviolet light (sunshine), nuclear radiation or certain chemicals
 * 2) Mistakes that occur when a cell copies its DNA in preparation for cell division.

1. DNA damage from environmental agents
Ultraviolet light, nuclear radiation, and certain chemicals can damage DNA by altering nucleotide bases so that they look like other nucleotide bases. When the DNA strands are separated and copied, the altered base will pair with an incorrect base and cause a mutation. In the example below a "modified" G now pairs with T, instead of forming a normal pair with C.
 * Modifying nucleotide bases**

Environmental agents such as nuclear radiation can damage DNA by breaking the bonds between oxygens (O) and phosphate groups (P). Breaking the phosphate backbone of DNA within a gene creates a mutated form of the gene. It is possible that the mutated gene will produce a protein that functions differently. Cells with broken DNA will attempt to fix the broken ends by joining these free ends to other pieces of DNA within the cell. This creates a type of mutation called "trans-location." If a trans-location breakpoints occur within or near a gene, that gene's function may be affected.
 * Breaking the phosphate backbone**

2. Mistakes created during DNA duplication
Prior to cell division, each cell must duplicate its entire DNA sequence. This process is called DNA replication. DNA replication begins when a protein called DNA helicase separates the DNA molecule into two strands.

Next, a protein called DNA polymerase copies each strand of DNA to create two double-stranded DNA molecules.

Mutations result when the DNA polymerase makes a mistake, which happens about once every 100,000,000 bases. Actually, the number of mistakes that remain incorporated into the DNA is even lower than this because cells contain special DNA repair proteins that fix many of the mistakes in the DNA that are caused by mutagens. The repair proteins see which nucleotides are paired incorrectly, and then change the wrong base to the right one.

http://learn.genetics.utah.edu/archive/sloozeworm/mutationbg.html


 * Environmental system society Point of View**

Radiation has always been a natural part of the environment. Most public attention is given to the category of radiation known as ‘ionizing radiation’. By ionizing radiation we mean radiation with sufficiently high energy to tear off electrons from atoms. Such radiation is emitted with the decay of radioactive nuclei, which may occur during nuclei reactions in the sun or nuclear reactors. It can also be produced by various types of equipment used for diagnostic radiology and radiotherapy. The most common types of ionizing radiation are: α : alpha β : beta and γ : gamma. Alpha radiation consists of positively charged helium nuclei; these are relatively large particles consisting of two protons and two neutrons. Because of its size and its electrical charge even a sheet of paper or human skin is enough to stop alpha radiation completely. It travels no more than a few centimeters in the air. Beta radiation made up of electrons has a lower mass than those particles that make up alpha radiation. Beta radiation generally has a much longer range. The glasses and thick clothing are enough to block it completely. Gamma rays and X-rays are electromagnetic radiations similar to radio-waves and visible light, but with much shorter wave length. Gamma rays are produced by the rearrangement of particles and the atomic nuclei and X-rays. By the deceleration of charged particles or the transition of electrons and atoms gamma rays usually have higher energy than X-rays and both have a much greater ability to penetrate matter than alpha and beta radiation. Gamma rays are only blocked to a minimum extent by the human body and its speed only decreases insignificantly when traveling through air.

The Dominic contribution to the radiation dozes which the general public is exposed to, come from sources we have very little power to influence. Radiation in housing comes mainly from the radioactive substances and soil and building materials. Building materials and soil often contain radio (a product of the radioactive decay of uranium). With the decay of radium, radon gases from which can penetrate into the houses. Each Swede is exposed to an average of 5 mSv of radiation. Each year the majority (about 65%) comes from radon within the housing. Medical exposes especially diagnostic radiology account from nearly 15% of the annual radiation doze. The medical use of ionizing radiation is of a great importance. Approximately every second speed is examined using X-rays each year. Also ionizing radiation is used in examinations and radiation therapy. However the doze of natural radiation depends on where you are. People who live high above sea level may receive larger dozes from outer space than the others. Only 20% comes from these natural background sources.

Physics
 * Nuclear Fission**
 * Uranium is the raw material
 * Radioactive
 * Split in nuclear reactors by bombarding it with neutrons
 * Uranium
 * Plutonium and other elements
 * 80 years left to mine uranium at current rates
 * Effect on lifestyle if we have no uranium
 * Our power source will be gone
 * Where will the energy come from?
 * Small mass of radioactivity produced
 * Measuring Radioactivity
 * The radioactivity of a substance is measured by how many decays per unit time occur
 * Radioactivity
 * It is found that nuclei with mass numbers greater then about 100 spontaneously decay into other types of nuclei. Such nuclei are said to be radioactive


 * Nucleus can lose energy by emitting radiation
 * Three types of ionizing radiation : Alpha, Beta, Gamma
 * Gamma is a form of electromagnetic radiation
 * This is what the machine measure a Gamma Rays
 * Particles in nucleus do not change, they just lose energy
 * Nucleus decays a Photon emitted
 * Frequency of gamma photons high
 * Gamma Energy
 * Gamma photons are releases when the nucleus is left in an excited state after another form of radiation
 * Half- Life
 * The time taken for half of the nuclei in a sample to decay
 * If one have 100 nuclei in a sample and 50 decay in one second. Then, the half life is 1 second.
 * Rate of decay proportional to the number of nuclei.


 * The Exponential Decay Equation
 * The rate of decay is proportional to the number of nuclei that is not decayed
 * The decay constant lambda tells us how quickly the material will decay
 * The half – life is the time taken for the number of nuclei to decay to the original value

Chemistry

radioisotope to decay products
 * Gamma radiation: This is the high-energy electromagnetic radiation that comes from radioisotope
 * Ex. Light is low electromagnetic radiation
 * Gamma rays are often emitted along with alpha or beta radiation by the nuclei disintegrating radioactive atoms
 * No mass and no electrical charge. Thus, gamma radiation does not change atomic number or mass number of atom
 * Gamma rays most penetrating type of radiation
 * Stability of nucleus depends on its neutron to proton ratio
 * Unstable nuclei undergo spontaneous radioactive decay
 * The type of decay that occur depends on the neutron to proton ration of the unstable nucleus
 * Half Life
 * Time required for one half of nuclei of
 * In the first half life half of the radioactive atoms would have decayed into atoms ad a new elements. The other half would still be unchanged. After the second half life, one quarter of the original radioactive atoms will remain.

=Group Members:= Iyone Aya Faisal Denise Ali