Airborne Radioactivity By Beth Harmony
Reasons for the experiment: Radiation is something that we are constantly being bombarded with from all directions. By taking a sample of the air, using a piece of filter paper, the amount of radiation that we breathe in can be estimated. The most common radiation that we are bombarded with is from radon 222, which comes up from the ground. Lead 214 is a byproduct of the decay of radon 222, and is also heavy enough to get caught in the filter paper, making it a good candidate to look at. How the experiment was done: A 62 cpm vacuum, with a piece of filter paper in it, was placed in three different rooms, and ran for an hour and 20 minutes. The filter paper was then placed over a germanium detector, which detects gamma radiation. The detector was run for 20 minutes, and then the peaks were analyzed. Each peak is associated with a specific energy, and, in most cases, is unique to a single element. By looking at the peaks that are associated with lead 214, the amount of micro Ci/ml, the amount of radiation in each milliliter, could be determined.
Source: Los Alamos Science
Uranium 238 Decay Series Source: Cutnell and Johnson
Source: Los Alamos Science
Low Level Lab Sample Live time 1191 seconds
Chalk Hill Sample taken live time 1218 seconds
Keck Laboratory Sample taken live time 1218 sec.
isotope Pb-214 gamma energy Raw Counts micro Ci/m (keV) under peak Low Level Lab Sample E-11 Chalk Hill Sample E-11 Keck Lab Sample E-11 Detector Efficiency = 2.93%
Lead-214 Atomic N o.RadionuclideClass Table 1 Occupational Values Table 2 Effluent Concentrations Table 3 Releases to Sewers Col. 1Col. 2Col. 3Col. 1Col. 2 Oral Inge stio n ALI (µCi ) Inhalation Air (µCi/ ml) Water (µCi/ ml) Monthly Average Concentr ation (µCi/ml) ALI ( µ C i ) DAC (µC i/m l) 82Lead D, all compounds9E+38E+23E-71E-91E-41E-3 NRC Limits on Lead-214
Source: Radiological Health Handbook
Germanium Detector (red cover) Air filter paper (on lab book – darker circle)
Air sampling tool with clean white filter paper