New this year: Our gamma ray detector has very much improved resolution thanks to a preamplifier exchange.
Applied Nuclear Chemistry & Physics Lab
Welcome! These experiments are an introduction to radioactivity, to radiation safety, to techniques for detecting alpha, beta, and gamma radiations, and to the use of radioactive tracers. You will learn neutron activation analysis using our neutron source and the Washington State University reactor at Pullman, Washington, where student hair samples are irradiated, shipped back to the Sonoma State University Nuclear Lab, and analyzed for trace elements. You will sample the natural background radiation. Three beta or gamma tracer experiments are planned. Two utilize our Wallac-LKB Liquid Scintillation Counter. Another involves the uptake of I-131 by the thyroid.
There are seven equally weighted experiments with two weeks scheduled for each at first. There are two orientation weeks and one summary week. On Tuesdays at 1:00 p.m. a laboratory lecture/discussion will take place in a separate room pertaining to one of the experiments. The laboratory is undertaken in the Darwin 10 complex for three groups of two during the following three hours. There may be a second section Wednesday afternoon that can accommodate three more groups of two.
Prerequisites: Physics 216, Concurrent or prior enrollment in Physics 481.
A book with laboratory instructions will be on sale at the bookstore in August.
Tuesday, September 3: Orientation. Laboratory safety. Familiarization with alpha, beta, and gamma radiation and our survey equipment. Hands on demonstration of our gamma detector. Short write up in laboratory book.
Tuesday, September 10: Safety Orientation with Dan Crocker. Good radiochemistry laboratory practices, liquid scintillation counter use respecting other users, procedures for handling beta emitters. Waste handling. Demonstration of neutron exposure procedures. Safety Quiz. Use this time to familiarize yourself with the laboratory and your first experiment. Continue thinking safety and upgrade your safety habits during the entire semester.
Introductory Experiments: six Tuesdays, September 17 - October 22
1. Alpha particle detection using room temperature silicon semiconductor detectors. Second week: Analysis of a particulate sample from air for natural alpha emitters.
2. Beta particle detection using a liquid scintillation counter. Characteristics of C-14, H-3, and I-125. Radiocarbon dating limits with the apparatus. Second week: preparation and verification of a dilution series to obtain varying concentrations of P-32. Use of Micropipettes.
3. Gamma ray detection using our germanium semiconductor detector. Detector calibration. Use of Nuclide Navigator. The natural gamma background in the room. Second week: neutron activation of unknowns.
Neutron Activation Experiments: three weeks, October 29 - November 12
7. Neutron activation and the saturation factor. Gamma counting with a Sodium Iodide detector. Maximum activity limits.
5. The Hot Hair Laboratory. We will ship to Pullman, Washington 0.3 gram hair samples for irradiation in their reactor. Upon return we will count them for longer half life components. An analysis program runs under Windows on the local IBM PC
Thyroid Uptake and Uranium in luggage experiments. Three weeks November 19 – December 3
6. The Hot Thyroid Laboratory. November 19 -26. Measurement of the uptake of I-131 by the thyroid. Each group will measure the thyroid on a different day. Combining the data over two weeks will allow a biological half life determination. Comparison will be made to human data obtained from a successful thyroid ablation performed by local doctors on one of our staff.
7. Alpha Particle Induced X-ray Fluorescence. November 19 – December 3. Alpha particles from the decay of U-238 fluoresce other nearby U-238 nuclei. These Uranium X-rays are detected and used to fluoresce other materials. Detection procedures for Uranium and Plutonium in luggage.
(Alternate experiment: Measuring the ratio of thermal to fast neutrons in our exposure facility.)
A field trip to a low level counting laboratory in Berkeley may be arranged in place of one laboratory.
8. Summary of detection methods used – lecture only December 10. Demonstration of our neutron meter, our ion chamber meter, and our newly acquired low level gamma meter.
A laboratory notebook is required and is good practice for industry. Laboratory reports are in the notebook. The raw data is included without recopying. An organized results table is appreciated. Reports handed in within one week of completion of the experiment will receive the maximum grade. Later = 10% grade reduction. Hand in your notebook within one week, and you will get more timely feedback. I will try for two-day turnaround.
Each report should be brief and to the point. The following is a guide:
|A short statement of purpose ||1 pt|
|A drawing of the equipment sufficient to hook it up again. ||1 pt|
| Procedure: Your original laboratory data.||2 pts|
|Analysis which can be done in the lab book if space is left. Calculations. Copies of any computer results, and graphs as appropriate, with comments on what they mean. A result table is appreciated. Cut with scissors and tape pages in to minimize hand copying. ||3 pts|
|Conclusions reflecting the statement of purpose. When appropriate, present the results in a table. For example, list the elements you found in an unknown with the gamma rays you base your conclusion on.||3 pts|
|Questions in the laboratory handout should be answered.|| |