For those interested in following along at home, we provide below the data we have collected. Air samples were collected on air filters in the UW Physics building. The flow rate sampled by an individual filter was measured to be 143,000 cubic meters per day, which is approximately 10 times higher than a typical box fan. The filters are 80% efficient for particles of size 5 microns and 60% for particles of size 2 microns. The filters are exposed for approximately one day each, and then bagged, crushed, and inserted into a lead shield containing a p-type point contact germanium detector (PPC2). Data were recorded continuously in one hour runs and processed in realtime. Additionally, we have taken several hours of data with just the detector in the shield (no samples) to measure the background, as well as data with a 152 Eu source to calibrate the detector efficiency and geometrical acceptance.
Below we provide data files for the samples as they arrive, along with the background measurement above. To compare between data files you need to account for the duration of the run (i.e., scale each distribution by 1/collection_time).
|PH1||23||3/16 (10 am) - 3/17 (12 pm)|
|PH2||13||3/17 (12 pm) - 3/18 (2 pm)|
|PH3||24||3/18 (2 pm) - 3/19 (9:30 am)||
|PH4||21||3/19 (9:30 am) - 3/20 (11 am)|
|PH5||19||3/20 (11 am) - 3/21 (1:30 pm)|
Current lab setup. Shielded germanium detector and data acquisition hardware.