Neutron imaging is a widely accepted method of imaging within the aerospace, aviation and nuclear communities for examination of engine O-rings, detection of corrosion material within sealed units, and observation of water behavior in plants and soils. The use of neutrons in these applications is due largely to how the neutron interactions with atomic particles within the atom. Neutrons are uncharged particles and attenuation with material not related to density. This means that materials with high-z like lead, steel and bone are easy for neutrons to penetrate and high contrast pictures can be obtain.
On the contrary neutrons react readily with lighter elements that have a higher number of nuclei’s per unit area. An element like boron will create absorption, making it an effective shielding material, while hydrogen based molecules, like water and graphite create a large amount of neutron scatter.
Creating a neutron image consists of a collimated neutron beam that is transported through an object and recorded on an image plate. When neutrons travel through an object a percentage of them are removed from the beam through scatter or absorption interacts. The output signal from the image plate is an image representing the interior structure of the object. The amount of absorption or scatter is dependent on the law of radiation attenuation.
Next week, students at Lowell High School will be evaluating the contrast and spatial resolution of neutron images taken within the Umass Lowell Research Reactor. Image quality will be measured utilizing Matlab’s picture quality evaluation system, providing a comprehensive review of the file. Pictures of both biological and non-biological material will be compared to demonstrate the effects of neutron scatter and absorption on images taken with two different camera systems within the reactor.
Industrial gamma radiography is an effective method of using gamma-emitting radioisotopes to test for cracks, defects and occlusions in pipes and welds without the need for conventional power sources. The process was established more than 50 years ago and has proven to be an important tool for non-destructive testing in remote locations. Historically, 192-Iridium, 60-Cobalt, 169-Ytterbium and 170-Thulium have been used in gamma radiography, with 192-Iridium and 60-Cobalt being the most common isotopes. Recently the isotope 75-Selenium has become available for industrial gamma radiography, and its use has been increasing significantly for examining metals ranging from 5mm to 30mm in thickness. The increased use of 75-Selenium is due to a lower photon energy range which improves operator safety and produces higher image quality for metals of thicknesses between 5 and 30mm.
Though there are significant benefits to using 75-Selenium, calculating accurate exposure rates can be difficult, owing to the fact that over two thirds of the decay energy of 75-Selenium is emitted in the form of photons of less than 12KeV, making accounting for attenuation of photons through source encapsulation a complex process. As such, there have been many discrepancies observed in reported Air Kerma rate constants for 75-Selenium; an issue which could lead to exposure rate miscalculations and have dangerous consequences.
Some of my recent research has focused on this issue and has led to a pending publication through the journal Applied Radiation and Isotopes. My research uses a Monte Carlo particle transport simulator to determine an appropriate exposure rate constant for 75-Selenium. This rate constant accounts for attenuation caused by 0.1mm source encapsulations and proves that this thickness will absorb 67% of the energy of a typical source. It was found that these results agree with three other publications determining 75-Selenium exposure rate constants by other methods. With an established rate constant the research also analyzes shielding systems commonly used in 75-Selenium radiography. By measuring transmission through various thicknesses of shielding the simulations provide attenuation curves for assessing risks due to 75-Selenium.
When you think of salt, bananas or brick walls, do you think of radiation? How many people know that everyone is exposed to radiation on a daily basis? Whether its patasium-40 or urianum-235 everyday everyone is exposed to some amount of radiation. During Friday’s presentation to my 9th grade class I brought in a GM detector and household items which contain radiation. During the presentation I explained what background radiation is and how good we as physicists are at measuring radioactive decays. Then I demonstrated how sources like salt, smoke detectors, and an old fashion festaware plate are constantly emitting natural radiation that can be measured above background levels.
During an informal conversation with students, I asked them how familiar they were with excel. I was shock that most of the students had never heard of excel, let alone used it for projects and homework. During Friday’s lecture, I showed students how I use excel as a tool for organizing and graphing information gathered during research. Using my computer and an overhead projector I reviewed a series of worksheets that I created for tracking absorbed dose from scanned EPT2 film exposed to an experimental Iridium brachytherapy seed.
In the presentation I talked to each class about some of the equations, series, graphs and sorting options I used regularly to organize my information. Since all of the classes are working on understanding different types of trend-lines, I was able to correlate my presentation with examples from their text book.
How much does it cost to live for one year? Should I buy lunch or brown bag it? Do I need a new pair of shoes or should I wear my old ones for another month? These are questions adults think about everyday but few high-school students realize what they actually mean. Often caught up in day to day activities like classes, sports and social events, many high school students inspire to live prosperously but lack the knowledge of what it takes to get there. My presentation to the students today illustrated how costs associated with having a house, mortgage, car and retirement plan relates to doing well in school and obtaining a quality education.
Hi All,
Tomorrow will be my fourth day teaching 9th grade algebra at Lowell High School and overall the experience has been excellent. For the past two weeks I have been working two days per week, Tuesday and Friday, helping with four different classes. While each class has its differences, most of the students are easy to talk to and are willing to learn.
All the classes are currently working on understanding basic fundamental concepts of algebra; orders of operations, interpreting word problems and writing expressions with variables. The math levels within the classroom vary significantly. The most challenging part of the job some far has been trying to push the students that grasp the concepts while helping the students who are clearly struggling.
Tomorrow, I hope to talk to each class for about 15 minutes and present my research. For those of you who I dont know as well, my research is focused on neutron radiography. I hope that showing the students pictures of the Umass Lowell 1mega watt research reactor, the objects we are imaging through.
Today was the first day of the GK-12 workshop. The focus of today’s workshop stressed ‘inquiry-based learning and teaching techniques’. Through the use of video, written packets and a group focused demonstration the instructors, Pat and Paula were successful at presenting techniques for actively engaging students. Some of the points I took away from the presentation are as follows.
a. Know your students – Build a personal relationship with each student and know their learning styles.
b. Preparation – Preparing for classes is 90% of the job. Have an objective and method for achieving it is critical.
c. Use Critical Thinking Questions – Using open ended questions can help create an effective learning atmosphere that builds problem solving skills.
d. Heterogeneous Grouping – Group students with different abilities.
e. Vocabulary – Definitions should be taught after concepts are presented.
Some of the question I have going forward are:
1. What are some effective methods for dealing with out of line students?
2. Can we see examples of effective lesson plans?
3. Are there support systems in place for students struggling in specific subject areas?
4. Functionally, how is the high school system set up? What are the requirements for a student to graduate?
Thanks so much for spending the time to talk to us today.
Respectfully,
Blake Currier
Uncategorized | blakecurrier | 
February 14, 2012 2:36 pm | 
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