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TABLE OF CONTENTS
TABLE OF CONTENTS.......................................................................................
LIST OF
FIGURES................................................................................................
LIST OF GRAPHICS............................................................................................
CHAPTER I INTRODUCTION...........................................................................
A. Background....................................................................................................... B. Problem Formulation......................................................................................... C. Objective of Experiments.................................................................................. D. Benefits of Experimentation.............................................................................. CHAPTER II LITERATURE REVIEW.............................................................. CHAPTER III EXPERIMENTAL METHODS................................................ A. Place and Time of Implementation.................................................................. B. Tools and Material........................................................................................... C. Identification Variable..................................................................................... D. Definition Operational Variables.................................................................... E. Work Procedures............................................................................................. F. Working Principles.......................................................................................... G. Analysis Data Tecnique................................................................................... CHAPTER IV OBSERVATION RESULTS......................................................
A. Observations Results....................................................................................... B. Data Analisys.................................................................................................. C. Discussion....................................................................................................... CHAPTER V CONCLUSION............................................................................ A. Conclusion...................................................................................................... B. Suggestion....................................................................................................... BIBLIOGRAPHY................................................................................................
LIST OF FIGURE
Figure 2.1 Illustration of the penetrating power of alpha, beta and gamma particles................................................................................................. Figure 2.2 Detector tube and particle absorption analogy......................................
Graph 4.12 Logarithmic relationship between the average cps and the distance in the beta ray to the G-M tube................................. 33 Graph 4.13 Relationship between average CPS and distance in gamma rays........................................................................................ 34
CHAPTER I
INTRODUCTION
A. Background On February 24, 1896, Henri Becquerel reported the phenomenon of radioactivity to the Academy. However, the initial experimental results were negative. But when Becquerel used potassium uranyl sulfate K2UO2(SO4)22H2O, he eventually observed the phenomenon and reported it to the Academy on March 2, 1896. In his report, Becquerel wrote, ‘A photographic plate, gelatin with silver bromide, wrapped in a dark cloth, covered on one side with aluminum; if we expose it to full sunlight for a day, the photographic plate will not darken. But if we place it on the aluminum sheet, on the outside, covered with a layer of uranium salt and expose it to sunlight for a few hours, we will immediately see, after cleaning the photographic plate as usual, a black shadow of the crystal layer on the aluminum sheet. That Becquerel’s discovery was unexpected is implied in the next two paragraphs of the report. “I am firmly convinced that the following fact seems especially important to me and is beyond the phenomena expected to be observed: the same layer of crystals, placed on a photographic plate in the same way but kept in the dark, will also produce the same photographic print. I arrived at these observations after going through this activity: Based on the results of my previous experiments which I had prepared on Wednesday 26th and Thursday 27th February, and because on those days, the sun only appeared intermittently, I saved it again the experimental materials I had prepared into a dark drawer, leaving a layer of uranium salt nearby. Because
the sun didn’t shine after a few days, I then washed the photographic plate in the hope that there would be a faint image. The image was visible, but contrary to my expectations, it had a high intensity.” Becquerel continued his experiments in a completely dark place and still obtained the same results. This means that, in addition to X-rays, there are other types of rays that appear to be emitted without being caused by phosphorescent materials. In 1896, Becquerel continued research on these new rays. Also in March, Becquerel discovered that these rays could discharge an electroscope. This means that these rays cause the air to be conductive. Becquerel then discovered that all uranium mixtures, phosphorescent or not, that he had studied so far, emitted this light. He concluded that the pure metal uranium should emit the strongest radiation which was later proven through experiments. At the end of 1896, Becquerel reported on the absorbency of various materials against these rays. Although this phenomenon of radioactivity was discovered by Becquerel, the name radioactivity itself was given by Marie Curie, the discoverer of other radioactive elements besides uranium, namely polonium and radium. For this discovery of radioactivity, Antoine Henri Becquerel, together with husband and wife Pierre Curie and Marie Curie, were awarded the Nobel Prize in physics in 1903, five years before Becquerel died. B. Problem Formulation The problem formulation in this experiment is as follows:
- What are the radiation characteristics of some radioactive substances?
- How do the penetrating powers of β and γ rays compare?
- What is the ability of various materials to absorb radiation?
- What is the relationship between the distance of a radioactive source and source activity? C. Objective of Experiments There are objectives that must be achieved in this experiment, namely as follows:
- Investigate the radiation characteristics of several radioactive substances.
- Investigate and compare the penetrating power of light and.
CHAPTER II
THEORETICAL BASIS
Radioactivity refers to the ability of unstable atomic nuclei to emit radiation and transform into stable atomic nuclei. This process is known as decay and unstable atomic nuclei are referred to as radionuclides. Substances that contain radionuclides are called radioactive substances. Decay occurs when an unstable atomic nucleus changes into a different atomic nucleus or when a radioactive element changes into a different element (Santiani, 2011: 19). Radioactivity is the process of decay of radioactive materials that occurs when atomic nuclei interact with matter in nature. As a result, radiation in the form of radioactive rays is emitted (Sumardi, 2022: 498). Radiation is a process in which energy is transmitted or emitted through space or objects in the form of high-speed particles or electromagnetic waves that have the potential to cause long-term damage. Radiation can occur in ionizing or non- ionizing form. Radioactive materials are materials that produce ionizing radiation and can be measured in units of sieverts (Sv). Ionizing radiation occurs when the radiation energy is high enough to displace electrons in atoms, thereby creating charged particles such as ions. This radiation is produced by atoms that are unstable and have excess energy, mass, or both. These atoms release this excess energy to achieve stability. Types of ionizing radiation include alpha, beta, and gamma particles (Ariastuti et al., 2023: 110-111). Alpha rays are a type of particle radiation that has a positive charge. Alpha ray particles have the same characteristics as helium-4 nuclei, with a charge of +2e and a mass 4 times the mass of a hydrogen atom. Alpha particles are the heaviest particles produced by radioactive substances. Alpha rays are emitted from atomic nuclei at a speed of about 1/10 the speed of light. Because they have a large mass, alpha rays have the weakest penetrating power compared to other types of radioactive radiation. Alpha rays can only penetrate a few centimeters of air and cannot penetrate the skin. Alpha rays can be stopped by a plain sheet of paper. When alpha rays collide with molecules in the medium they travel through,
they immediately lose their energy. This collision causes the medium through which it passes to experience ionization. As a result, the alpha particle captures 2 electrons and turns into a helium atom. (Santiani, 2011: 33-34). Beta particles (β) have the same mass as electrons, which are smaller than alpha particles (α), so they have less ionizing power. Beta decay produces a new nuclide that has the same mass number as the original radionuclide, forming a radionuclide isobar. Therefore, the mass of beta particles in decay is negligible. Beta decay can occur in the form of positive beta (e+) or negative beta (e-) as well as electron capture. When beta particles interact with matter, the direction of movement of the particles can change or bend (Maharani et al., 2023: 192-193). According to Santiani (2011: 35-36) Gamma rays are a type of electromagnetic radiation that has high energy, no charge, and no mass. Apart from alpha and beta rays, there are also X-rays and positron rays emitted by artificial radioactive substances. The energy of gamma rays is greater than beta and alpha rays. Alpha particles have the lowest radiation energy. Gamma rays are emitted by unstable atomic nuclei in an excited state, and by emitting gamma rays, the atomic nuclei change to stable nuclei without changing the atomic number or mass number. Alpha particles cannot penetrate paper, beta particles cannot penetrate aluminum plates. To stop gamma rays, a thick layer of metal is needed, but because absorption is exponential, it is possible that a small fraction of gamma rays can penetrate the metal plate. Figure 2.1 Illustration of the penetrating power of alpha, beta and gamma particles
ionize the atoms or gas molecules in the tube. The released electrons and positrons will then form electron pairs, which can be used by detectors to measure the characteristics and properties of electron-positron pairs and calculate the energy lost when interacting with matter (Maharani, et al., 2023: 195). Figure 2.2 Detector tube and particle absorption analogy (Sumber: Maharani, et al., 2023: 195) The inverse-square law for light intensity states that the intensity of illumination is inversely proportional to the square of the distance from the light source. Based on research results regarding the relationship between light intensity and beam distance, this law states that if the beam distance is farther, the intensity of the light received will be smaller. Conversely, if the emission distance is shorter, the intensity of the light received will be greater. (Simatupang, 2023: 6088).
CHAPTER III
EXPERIMENTAL METHODS
A. Place and Time of Implementation This radioactive substance activity experiment was carried out on Saturday, March 16Th^ 2024, in the morning at 01.00 until finished. B. Tools and Materials The tools and materials used in this radioactive substance activity experiment are as follows.
- Sample Holder (10 positions) (1 piece)
- Cable for G.M. (BNC/BNC Connectors) (1 piece)
- Geiger Muller tube (1 piece)
- Aluminum Barrier Set (4 pieces)
- Lead Barrier Set (4 pieces)
- Ratemeter ST360 (1 piece)
- Gamma & Beta Radioactive Sources (2 pieces)
- Screw Micrometer (1 piece)
- Sample Holder (1 piece)
- Rulers (1 piece) C. Identification Variable Activity I. Get to know radioactive substances
- Control Variables : Distance to radiation source (cm), Voltage (V)
- Manipulated Variable : Type of Radiation Source (Beta and Gamma)
- Response Variable : Number of counts per second (cps) Activity II. Measuring the Penetrating Power of Beta and Gamma Rays
- Control Variables : Barrier Type (Al and Pb), Source Type Radiation (Beta), Source Type Radiation (Gamma), and Voltage (V)
- Manipulated Variable : Thickness of Barrier Material (mm)
- Response Variable : Number of counts per second (cps) Activity III. Law of Square Reciprocity
- Determines the voltage to be used. Activity 1. Determine the Activity of Radioactive Substance
- Place the beta radiation source on the sample rack 2.
- Press the star button on the ratemeter and it will display the data then record the data.
- Repeat until you get 30 records.
- Then replace the radiation source with a gamma radiation source, doing the same as Step 2-3.
- Repeat steps 1-4 without using a radiation source, so the holder sample is empty.
- Click reset. Activity 2. Measure the Penetrating Power of Beta (β) and Gamma Rays (γ)
- Place the beta radiation source on the sample rack 2.
- Choose a barrier material, namely aluminum, starting from the thinnest and place it on sample rack 1, before measuring the thickness of aluminum using a micrometer of couplers.
- Then click the star button until it displays data on the ratemeter then record the results of the data.
- Repeat steps 2-3 replacing the aluminum material with another thickness.
- Repeat Steps 2-4 by replacing the aluminum material with lead
- Repeat activities 1-5 using a gamma radiation source.
- Click reset. Acitivity 3. Inverse square law
- Place the beta radiation source on the sample rack 1.
- Measure the distance of the sample from the end of the G-M tube using the bar.
- Then click the star button until it displays data on the ratemeter then record the results of the data.
- Repeat Steps 1-3 by changing the position of the sample rack 4 times.
- Repeat Steps 1-4 using a gamma radiation source F. Work Principle The working principle of activating radioactive substances is in the Muller
Geiger Detector which functions as a radiation detector through ion pairs in the Muller Geiger tube containing gas. In the Geiger Muller detector there are two materials, namely the wall of the Geiger Muller tube which is the cathode and has a negative charge and the Geiger Muller wire which is the anode and has a positive charge. In the tube, ionization of the gas has occurred because the Geiger Muller tube is given a voltage of 900 Volts. By applying voltage to the Muller alarm detector, an ionization process will occur which produces positive and negative ions. Positive ions will be attracted to the cathode and negative ions will be attracted to the anode. And in the Muller shock tube, the ion withdrawal process occurs before the particles enter the Muller shock detector. And after that, for example, an alpha particle that has positive ions and negative ions will enter the Geiger Muller tube, this will cause the positive ions to be attracted by the negatively charged cathode and the negative ions will be attracted by the positively charged anode. Then all the positive ions will be drawn into the Geiger Muller tube and the negative ions will gather at the cathode and then come out of the Geiger Muller detector into electrons or electric current and go to the rattemeter and then be translated into the number of counts that will be read on the rattmeter then the count results will be clearer than rattemeter will be read on the computer. G. Data Analysis Tecnique Activity 1.
- Histogram graph of experiments carried out for the three radiations.
- Maximum activity and average activity from each source, as well as the standard deviation, are measured by the results obtained
- Form of distribution of radiation from the activity of radioactive substances. Activity 2
- Graph of the relationship between barrier thickness and average CPS for each source
- Types of radiation that have large penetrating power, and those that have low penetrating power
CHAPTER IV
OBSERVATION RESULT
A. Observation Result Activity 1. Determine the Activity of Radioactive Substance Table 1. The Relationship Between Radiation Source and Average CPS Beta Radiation Source : Strontium-90 (Sr-90) Gamma Radiation Source : Barium-133 (Ba-133) Beta radiation sources Gamma radiation sources Background radiation (CPS) (CPS) (CPS) 65 68 59 5 9 0 1 3 1 65 71 57 4 6 5 1 1 1 57 54 51 7 7 7 2 4 1 59 62 43 5 3 9 0 0 0 60 68 61 1 5 7 0 1 2 66 58 60 8 6 6 3 0 0 59 76 72 3 7 4 2 1 0 56 61 67 4 7 6 0 0 1 88 72 53 6 4 13 0 0 1 57 62 59 4 6 10 1 2 1 Maximum cps 88 Maximum cps 13 Maximum cps 4 Average cps 62,2 Average cps 5,8 Average cps 1 Standard Deviation 8, Standard Deviation
Standard Deviation
Activity 2. Measure the Penetrating Power of Beta (β) and Gamma Rays (ɣ)
- Beta Radiation Beta Radiation Source : Strontium-90 (Sr-90) Half Life : 28,8 Years Initial Activity : 0,1 μ Ci
Unhindered Activity : 62, Table 2. 1. Beta (β) Sr-90 Penetrating Power of Aluminium (AI) a. Types of barriers : Aluminium Thick = (G)
|0,510 ± 0,005| mm
Thick = (H)
|1,540 ± 0,005| mm
Thick = (N)
|2,250 ± 0,005| mm
Thick = (P)
|3,150 ± 0,005| mm
Average cps 34,06 Average cps 6,77 Average cps 1,9 Average cps
Standard deviation 5,3 Standard deviation 2,66 Standard deviation 1,56 Standard deviation
Tabel 2.2 Beta (β) Sr-90 Penetrating Power of lead (Pb) a. Types of barriers : Lead Thick = (Q)
|1,550 ± 0,005| mm
Thick = (R)
|2,160 ± 0,005| mm
Thick = (S)
|3,200 ± 0,005| mm
Thick = (T)
|7,090 ± 0,005| mm
Standard deviation 2,7 Standard deviation 2,67 Standard deviation 2,98 Standard deviation
Tabel 2.4 Gamma (β) ray Penetrating Force with Lead (Pb) b. Types of barriers : Lead (Pb) Thick = (Q)
|1,550 ± 0,005| mm
Thick = (R)
|2,160 ± 0,005| mm
Thick = (S)
|3,200 ± 0,005| mm
Thick = (T)
|7,090 ± 0,005| mm
Average cps 3,1 Average cps 2,63 Average cps 1,57 Average cps
Standar deviation 1,86 Standar deviation 1,24 Standar deviation 1,38 Standar deviation
Activity 3. Inervse of law square Tabel 3.1 Distance Relationship with Beta (β) Light Activity Beta radiation sources Distance (D) =
|2,20 ± 0,05| cm
Distance (D) =
|3,10 ± 0,05| cm
Distance (D) =
|4.20 ± 0,05| cm
Distance (D) =
|5,30 ± 0,05| cm
Distance (D) =
|2,20 ± 0,05| cm
Distance (D) =
|3,10 ± 0,05| cm
Distance (D) =
|4.20 ± 0,05| cm
Distance (D) =
|5,30 ± 0,05| cm
Average cps
Average cps
Average cps
Average cps
Standard deviation
Standard deviation
Standard deviation
Standard deviation
Tabel 3.2 Relationship of Distance with Gamma (β) Ray Activity Gamma radiation sources Distance (D) =
|2,20 ± 0,05| cm
Distance (D) =
|3,10 ± 0,05| cm
Distance (D) =
|4.20 ± 0,05| cm
Distance (D) =
|5,30 ± 0,05| cm
Average cps
Average cps
Average cps
Average cps
Standard deviation
Standard deviation
Standard deviation
Standard deviation
