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2021 ANS Winter Meeting and Technology Expo
November 30–December 3, 2021
Washington, DC|Washington Hilton
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RFP issued for Hanford’s integrated tank disposition contract
The Department of Energy’s Office of Environmental Management (EM) has issued a final request for proposal (RFP) for the Hanford Integrated Tank Disposition Contract, a 10-year, $45 billion deal to oversee waste tank operations at the DOE’s Hanford Site near Richland, Wash. Proposals are due by December 20.
Modeling Atoms : Mini Rutherford
Description: With the Mini Rutherford Activity, students deduce shapes and sizes of unseen objects by tracking the movements of objects they can see, in relation to the unseen object. By extension, this device is a useful analogy to Rutherford’s alpha scattering experiments and to atomic particle detection utilizing accelerators. (Since the particles are too small to be seen, it was necessary to deduce their sizes by other means in both of these instances.) This experiment is best used by students working in pairs.
Disciplinary Core Ideas (DCI, NGSS)5-PS1-1, MS-PS1-1, MS-PS1-4, HS-PS1-8
Time for Teacher Preparation40-60 minutes – To make the Rutherford boards40-60 minutes – To prepare for the classroom
Activity Time:40-60 minutes (1 Class Period)
Science and Engineering Practices (NGSS)
Cross Cutting Concepts (NGSS)
ObjectiveStudents will try to determine the shape of an unknown object by using the scientific thought process of creating a hypothesis, then testing it through inference. It is based upon the Rutherford Gold Foil Experiment where scientists discovered that the structure of the atom includes the nucleus in the center surrounded by electrons in empty space. It is a great introduction to the scientific process of deducing, forming scientific theories, and communicating with peers. It is also useful in the mathematics classroom by plotting the angles of incidence and reflection
BackgroundFrom 1911 to 1913, British physicists Geiger and Marsden, working in the laboratory of Ernest Rutherford, conducted experiments with beams of positively charged, alpha particles to penetrate gold, silver, and copper atoms. They observed that most of the alpha particles went directly through the foil. However, some particles were deflected and others recoiled back toward the source. Rutherford systematically investigated the results Geiger and Marsden obtained with alpha particles; Rutherford concludedthat most of the mass of an atom is concentrated in a small region in its center, now called the nucleus.
Fundamental Particles DetectionLight has a wavelength of 10-7 m. Light microscopes enable us to view parts of a cell as small as 10-6 m. Electron microscopes enable us to see an image with a wavelength as small as 10-9 m. With the help of scanning electron microscopes, we can see fuzzy images of atoms. To detect a smaller image, such as a fundamental particle, we need to produce particles with greater energy, and thus, a shorter wavelength. The smallest fundamental particle is less than 10-18 m in diameter! Although scientists have not yet been able to actually see fundamental particles, they can infer the presence of these particles by observing events and applying conservation laws of energy, momentum, electric charges, etc. One way to do this is with a particle accelerator. Essentially, aparticle accelerator works by shooting particles at high speed toward a target. When these bullet particles hit a target, a detector records the information about the resulting event.
Necessary Components for Particle Detection1. Bullet Particles. These can be either electrons, positrons (the anti-particle of an electron), or protons. The particlesare collected as follows:
2. An accelerator increases the speed of bullet particles to greater energy levels. The particles are accelerated with an electric field by riding on traveling electromagnetic (EM) waves. The EM waves are created in devices called klystrons, which are large microwave generators.
3. The steering device directs the bullet particles to their target. Magnets are used to steer the particles around a circular accelerator and to focus the particles so they will hit the target. The same magnets make positive and negative particles traveling in the same direction bend in opposite directions.
4. A target can be any solid, liquid, or gas, or another beam of particles.
5. A detector interprets the paths of the resulting particles once the bullet particles have collided with their target. Modern detectors have several layers, to detect the many particles produced in a collision event. A detector can be up to three stories tall. An advanced computer system is used to reconstruct the many paths of the particles detected in the layers associated with a collision. By viewing particle paths through each layer of the detector, scientists can determine the results of an event. Charged particles leave a track in the inner (tracking) layer of the detector. The positive or negative charge of the resulting particle can be determined by the direction it curves in a magnetic field. A particle with great momentum (speed x mass) will have a less curved path compared to one with less momentum. After a collision, electrons and protons will leave showers of particles in certain detector layers. Photons and neutrons travel a little further through the layers before their collisions create a shower of particles. Muons (one type of a fundamental particle), however, can be detected in the outer layer of a detector. They travel right through the inner layers with little or no interaction.
Teacher Lesson Plan:
TraditionalTo make Rutherford boards:Velcro, glue, or nail block shapes underneath the masonite boards. Note: Some hardware stores will cut shapes for you free of charge.
Potential Block Shapes:
Triangle, Square,Rhombus, Isosceles Trapezoid, Hexagon
Place the Rutherford boards on a large table or on the floor, obstructing the shapes from your students’ view. Place a pieceof paper on top of each Rutherford board. Beware: your students may be tempted to peek. The student activity, described in the accompanying worksheet, should take about five minutes to complete. The activity can be repeated several times during a class period, using different shapes and/or marbles each time. Some shapes are more difficult to detect than others.
NGSS InquiryExplain Rutherford’s experiment. Tell students that they will design their own experiment, using rolling marbles as alpha particles to discover the shape of a hidden geometric shape, which simulates the nucleus. You might suggest that the students experiment with rolling a marble at different angles at a straight surface and seeing the different ways the marble deflects.
Using the Rutherford boards:Middle SchoolPart 1
Working in small groups, roll one of the marbles at the hidden object underneath the Rutherford board while one student draws the marble’s path in, and the deflected path out, on the piece of paper placed on the Rutherford board. Map the paths of the marbles that do not deflect or deflect slightly, as well. Make sure you roll the marble fast enough so that it makes a clean shot in and out.
Repeat Step 1 as many times as needed to define the outline of the hidden shape, using the same size marble each time. Make sure you roll the marble from many points on each side of the board.
Once you are satisfied that you know the shape of the object under the Rutherford board, draw the shape onto the piece of paper. (You might want to trace the shape from the paper with the outline formed by the collision paths).
Before looking at the actual block shape, show your instructor the shape you have drawn. Then look at the block underneath the Rutherford board, and discuss any parts of the shape you have drawn that are ill-determined.
Part 2: Have the instructor place a different block back under the Rutherford board (or switch boards if they are permanently attached). Place a clean sheet of paper on the top of the Rutherford board and repeat the procedure (Steps 1-4).
High SchoolRepeat steps 1-5 as per the Middle School procedure. Place the Rutherford board on a large piece of butcher paper, and then have the students record the shapes on the large paper. Do not put the paper on the board so that students must infer the shape from the surrounding angles of incidence/reflection.
Disciplinary Core Ideas (DCI, NGSS):5-PS1-1, MS-PS1-1, MS-PS1-4, HS-PS1-8, HS-PS4-2, HS-PS4-5
Time for Teacher Preparation:30-60 minutes – To gather materials and set-up
Activity Time:30-60 Minutes (1 Class Period)
Science and Engineering Practices (NGSS):
Cross Cutting Concepts (NGSS):
Background:Radioactive elements continually undergo a process of radioactive decay during which their nuclei emit high-speed particles and rays. These are much too small to be seen under a microscope. The Cloud Chamber was invented by an English physicist, C. T. R. Wilson, in 1911. It is an instrument designed for the study of the trails of radioactive emissions. The investigation is accomplished in the following way. First, the air must be saturated with water or alcohol vapor. When the high-energy particles flow through the air, electrons are knocked loose from some of the atoms and form ions. Ions act as excellent centers for condensation. This condensation, however, must be stimulated by cooling the air. The water vapor or alcohol condenses on the ions, leaving a vapor tail which clearly reveals the path of the ray.
Cloud chambers detect the paths taken by ionizing radiation. Much like the vapor trail of a jet airplane, the tracks in a cloud chamber mark where ionizing radiation has been traveling. The radiation itself is not visible. Radioactive materials are one source of ionizing radiation. Three types of rays are given off by a radioactive element. They are alpha particles (positive nuclei of helium atoms traveling at high speed), beta particles (high-speed, negative electrons), and gamma rays (electromagnetic waves similar to X-rays). Most of the tracks will be about one-half inch long and quite sharp. These are made by alpha radiation. Occasionally you will see some twisting, circling tracks that are so faint that they are difficult to see. These are caused by beta radiation.
Making Atoms Visible : Cloud ChamberDescription:Allow students to visualize and understand ionizing radiation.Grade Level:5-12Disciplinary Core Ideas (DCI, NGSS):5-PS1-1, MS-PS1-1, MS-PS1-4, HS-PS1-8, HS-PS4-2, HS-PS4-5Time for Teacher Preparation:30-60 minutes – To gather materials and set-upActivity Time:30-60 Minutes (1 Class Period)Materials:
Teacher Lesson Plan
Note: You can use radioisotope disks in each chamber in lieu of Coleman lantern mantle pieces. By providing Alpha, Beta, and Gamma sources , students will find that only the Alpha and Beta sources will produce tracks. This is because Gamma radiation is electromagnetic radiation not particles, and it’s the particles moving through the alcohol cloud that makes the tracks.
NGSS Guided InquiryGive the students radioactive samples and ask them to reduce/block the radiation to normal background levels with things they find in the classroom.
Explain about the different types of radiation and radioactivity. Tell students to design their own experiment, to detect different types of radiation, and then share their results with the class.
Student ProcedureObserve the vapor trails produced within the cloud chamber and answer the questions provided by your teacher.
Note: You can use radioisotope disks in each chamber in lieu of Coleman lantern mantle pieces. By providing Alpha, Beta, and Gamma sources , students will find that only the Alpha and Beta sources will produce tracks. This is because Gamma radiation is electromagnetic radiation not particles, and it’s the particles moving through the alcohol cloud that make the tracks.
Post Discussion/Effective Teaching Strategies
Differentiated Learning/ Enrichment
Disciplinary Core Ideas (DCI, NGSS)5-PS1-1, MS-PS1-1, MS-PS1-4, HS-PS1-8, HS-PS4-2, HS-PS4-5
Time for Teacher Preparation30-60 minutes – To gather materials and set-up
Activity Time:30-60 minutes (1 Class Period)Materials
ObjectiveMake a simple instrument to detect static electricity and radiation.
BackgroundAn electroscope is a very simple instrument that is used to detect the presence and magnitude of electric charge on a body such as static electricity. The type of electroscope detailed in this experiment is called a pith-ball electroscope. It was invented in 1754 by John Canton. The ball was originally made out of a spongy plant material called pith. Any lightweight nonconductive material, such as aluminum foil, can work as a pith ball. The pith ball is charged by touching it to a charged object. Since the ball is nonconductive and the electrons are not free to leave the atoms and move around the ball, when the charged ball is near a positively charged body, or source, the negatively charged electrons are attracted to it and the ball moves towards the source. Conversely, a negatively charged source will repel the electrons, and therefore the ball. Electroscopes can also be used to detect ionizing radiation. In this case, the radiation ionizes the air to be more positively or negatively charged depending on the type of radiation, and the ball will either be attracted or repelled by the source. This is how electroscopes can be used for detecting x-rays, cosmic rays, and radiation from radioactive material.
NGSS Guided Inquiry
Data CollectionStudents should record which objects hold a charge and which do not
Assessment IdeasHave students use electroscopes to discern between radioactive sources and nonradioactive sources.
Differentiated Learning/EnrichmentHave students compare radioactivity of different sources.
Disciplinary Core Ideas (DCI)3-5ETS1-2, MS-ESS1-4, HS-ESS1-6
Time for Teacher Preparation40-60 minutes – To gather materials
Science and Engineering Practices
Cross Cutting Concepts
ObjectivesStudents try to model radioactive decay by using the scientific thought process of creating a hypothesis, then testing it through inference. It is a great introduction to the scientific process of deducing, forming scientific theories, and communicating withpeers. It is also useful in the mathematics classroom by the process of graphing the data.
Students should begin to see the pattern that each time they “take a half-life,” about half of the surrogate radioactive material becomes stable. Students then should be able to see the connection between the M&M’s and Puzzle Pieces and radioactive elements in archaeological samples. Seeing this connection will help students to understand how scientists can determine the age of a sample by looking at the amount of radioactive material in the sample.
BackgroundHalf-LifeIf two nuclei have different masses, but the same atomic number, those nuclei are considered to be isotopes. Isotopes have the same chemical properties, but different physical properties. An example of isotopes is carbon, which has three main isotopes, carbon-12, carbon-13 and carbon-14. All three isotopes have the same atomic number of 6, but have different numbers of neutrons. Carbon-14 has 2 more neutrons than carbon-12 and 1 more than carbon-13, both of which are stable. Carbon-14 is radioactive and undergoes radioactive decay.
Radioactive materials contain some nuclei that are stable and other nuclei that are unstable. Not all of the atoms of a radioactive isotope (radioisotope) decay at the same time. Rather, the atoms decay at a rate that is characteristic to the isotope. The rate of decay is a fixed rate called a half-life.
The half-life of a radioactive isotope refers to the amount of time required for half of a quantity of a radioactive isotope to decay. Carbon-14 has a half-life of 5730 years, which means that if you take one gram of carbon-14, half of it will decay in 5730 years. Different isotopes have different half-lives.
The ratio of the amounts of carbon-12 to carbon-14 in a human is the same as in every other living thing. After death, the carbon-14 decays and is not replaced. The carbon-14 decays, with its half-life of 5,730 years, while the amount of carbon-12 remains constant in the sample. By looking at the ratio of carbon-12 to carbon-14 in the sample and comparing it to the ratio in a living organism, it is possible to determine the age of a formerly living thing. Radiocarbon dates do not tell archaeologists exactly how old an artifact is, but they can date the sample within a few hundred years of the age.
M&M’s® (or Pennies or Puzzle Pieces)
NGSS Guided InquiryExplain about radiation and half-lives of isotopes. Tell students to design their own experiment, using paper, M&M’s®, Pennies, other 2 sided material or Licorice as a radioactive material undergoing decay to discover the nature of the half-life of that material.
You might suggest that the students experiment with their graphing results to see if trends begin to form.
M&M’s® (or pennies or puzzle pieces)
Data CollectionStudent Data Collection Sheets
Post Discussion/Effective Teaching StrategiesQuestions provided on theStudent Data Collection Sheets
ObjectivesStudents model the exponential nature of radioactive decay by using the scientific thought process of creating a hypothesis, then testing it through inference, and applying computational thinking. It is a great introduction to the scientific process of deducing, forming scientific theories, and communicating with peers. It is also useful in the mathematics classroom by the process of visualizing data.
Students should begin to see the the exponential nature of radioactive decay regardless of the length of an element's half-life.
Last modified July 17, 2020, 3:49pm CDT