LB Thesis Outline
Abstract
Photon Activation Analysis functions as a way to quantify isotopic concentrations in a certain material. This information is very useful when trying to find potential contaminants within a sample. Selenium, when ingested in large amounts, is harmful as it is a toxic substance. When applying PAA, one of the most important pieces of the investigation is ensuring that isotopes within a sample are detectable i.e. how active does a sample have to be to detect the isotopes of interest? Soil was gathered and targets were created with 50%, 10%, 1%, and 0.1% concentration by mass of selenium which was introduced to the soil during the target creation. The targets were irradiated using the Linear Accelerator at the Idaho Accelerator Center with a beam energy of 32 MeV. Once active, the spectral data was gathered using a high purity germanium detector.
- Give results of signal to noise ratio plot (Experimental MDA)*
Theory
Experimental Setup
Give beam parameters, include schematic of the experimental setup (xfig),include pictures of accelerator and W/Al Radiator. Give GPS coordinates for soil gathered.
Target Information
a schematic of the target is shown below:
| Sample | Soil Mass (g) | Inner Se Mass (g) | Outer Se Mass (g) | Front Outer Nickel Foil (g) | Front Inner Nickel Foil (g) | Rear Inner Nickel Foil (g) | Rear Outer Nickel Foil (g) |
| 50% Sample | 0.4921 | 0.5145 | 0.0900 | 1.5535 | 0.3956 | 0.3050 | 1.6140 |
| 10% Sample | 4.9921 | 0.5142 | 0.1245 | 1.3310 | 0.3592 | 0.2768 | 1.2196 |
| 1% Sample | 10.2403 | 0.0954 | 0.0914 | 3.4274 | 1.8672 | 1.7220 | 3.4887 |
| 0.1% Sample | 100.1242 | 0.1074 | 0.1042 | 1.3911 | 0.4467 | 0.2548 | 1.3804 |
DAQ
Detector Efficiencies
Calibration Method
When using the HpGe detector, the energy isn't directly given due to the fact that the energy deposited by the photon into the crystal is converted into an ADC channel number. The energy calibration is quite simple. By using calibrated sources with known activities, dates of activation, and energy lines, one can place the calibrated source in front of the HpGe detector and find which channel number corresponds to the energy line of interest. This would be a single data point in your calibration. To ensure that the calibration is of a high quality, take several sources with several different energy lines that span the channel range of the detector and compare the channel number to the energy. Once this information has been found, simply make a file with the energy the line was supposed to be, the channel number, and the standard deviation from a Gaussian fit and plot the points. Once the points are plotted a linear fit can be done to find exactly how the energy lines deviate from the raw channel number.
Data/Error Analysis
LB Thesis Thin Window Analysis
Conclusion
Appendices
- Include arrays of plots similar to analysis pages?
- Include ROOT macros?
- Include runlists?