Radiation Detection Multi Channel Analyzer and a Phototube: The study of a flat panel scintillator Janet Sanford , Chri

1. Paddle (top view) 30cm 30cm Paddle Construction (side view) Acknowledgement: This work was supported by the National Science Foundation’s Research Experience for Undergraduates program.(CHE-0353724) • References: • Hamamatsu Phototube http://usa.hamamatsu.com/index.php?id=13195780&language=1& • Radioactive Sources http://www.spectrumtechniques.com/radioisotopes.htm • UCS 20 Spectrometer Multi Channel Analyzer http://www.spectrumtechniques.com/ucs20.htm • Physics Constants http://www.physics.nist.gov/ • Stopping Power Curves http://www.physics.nist.gov/PhysRefData/Star/Text/ESTAR.html • National Science Foundation Research Experiences for Undergraduates http://www.nsf.gov/funding/pgm_summ.jsp?pims_id=5517&from=fund Radiation Detection Multi Channel Analyzer and a Phototube: The study of a flat panel scintillator Janet Sanford , Chris George Advisor : Dr. Thomas Dooling How well do these detectors work? The following two tables show data from the multi channel analyzer for two different modes. Table 1 shows the energy curves for each of the four sources using the multi channel analog mode. This modeRecords energy data observed for a specific channel. Each of these runs are compared to a Monte Carlo Simulation. Table 2 shows each source using the multi channel scalar mode, which records data for each channel observed within a set time frame. Each graph is a comparison scale of each source at different positions above the paddle along with a background run. These are also compared with a Monte Carlo Simulation. A graph of the log of the average count versus distance is plotted to show the increase of sensitivity as the source nears the paddle Abstract: This experiment investigated the effectiveness and sensitivity of an inexpensive, handheld, flat paddle scintillator at detecting weak radioactive sources. The sources implored during this study were Strontium-90, Cesium-137, Thallium-204, and Cobalt-60 with activities per second of 0.1 μ Ci, 5.0 μ Ci, 1.0 μ Ci, and 1.0 μ Ci, respectively. The multi channel analyzer, along with a phototube were used in conjunction with the scintillator paddle for the source detection. The sources were placed at different distances away from the paddle and compared to a background run. Each of the detection runs were compared to a Monte Carlo Fortran Simulation run. These data runs are used to determine specific settings needed to make the Monte Carlo simulations more accurate. What purpose do these inexpensive radiation detection devices serve? These small devices provide preliminary detection of potentially harmful substances used in making dirty bombs or other explosives. These detectors are set up by hand and easy to use. They can provide post offices and other government agencies the opportunity to detect harmful radiation before the package reaches the public. If something is detected by these handheld detectors, that substance can be subjected to more extensive and accurate analysis. For example, the cost of detecting every package that comes through a post office everyday with a state-of-the-art radiation detector, is not efficient and very costly. By using the smaller, yet still sensitive detectors, the efficiency of detection will increase, while the price decreases. Results: The Monte Carlo program needs to be ran with higher statistical simulations. The higher statistical simulation will show the separation between distances more clearly. The Multi Channel scalar mode graphs, clearly show how effective the scintillator paddle detects sources with respect to distance above background noise. The positions (0,0,35) and (0,0,45) are noticeable above background in all sources, but only slightly in the Thallium 204. The position (0,0,15) and closer are the most noticeably detectable above all background noise. These handheld devices have proven to be effective in detecting everyday weak radiation sources, and therefore it can be assumed they will be able to detect sources of stronger energy. Table 1 Table 2 Each multi channel scalar graph shows the four sources at positions: (0,0,0); (0,0,3); (0,0,6); (0,0,9); (0,0,12); (0,0,15); (0,0,30); (0,0,45) The energy curves provide a way to calculate an equation for the Monte Carlo simulation. These curves also provide comparison for the fine detailing of the Fortran program. The idea behind the Monte Carlo program is to be able to predict what the sensitivity of a detector might be with given parameters of height, width, and length. The Monte Carlo program is providing the user with the basic shape that is seen from the raw data. One possible solution would be to run the Monte Carlo under much higher statistics. Another solution is to reconfigure the Monte Carlo’s calculations to provide more accurate data for comparison. Equipment Used Company: Hamamatsu Series: H5783/H6780 Dimensions: Length: 22.0 mm Width: 22.0 mm Height: 50.0 mm This phototube has an optimum Wavelength spectrum from 420 nm to 630 nm which falls in the visible light spectrum corresponding respectively to violet and orange light. PRICE : $ Company: Spectrum Techniques Cobalt 60 :Gamma Ray producer Activity per second: 1.0 µ Ci. Cesium 137: Beta Particle & Gamma Ray producer Activity per second: 5.0 µ Ci Strontium 90: Beta Particle producer Activity per second: 0.1 µ Ci Thallium 204: Beta Particle producer Activity per second: 1.0 µ Ci. PRICE : $250