KELP STUDY from LOPEZ ISLAND COLLECTED AUG 9, 2014
This kelp sample was gathered on August 9, 2014 off Lopez Island from the Straight of Juan De Fuca in the Puget Sound. The person gathering it had counted it at 123cpm and a few days later Mimi’s Geiger counter showed it reading 80 cpm with a stable background of 31-32 cpm. The sample testing for the gamma spectrometer was on Aug 16th, 2014. We knew there was a radioisotope source since the readings from the Geiger counter were still reading higher than background and therefore were probably not from Radon. The scintillation detector found a background within its lead shield just previous to the kelp count, at 5.5 pulses per second. The pulse count per second for the kelp was 6.3. Outside the lead shield, there is a pulse per second of 6.7 to 7.1.
Throughout the 10 hour count subtracting background, there is only one well developed peak. This peak is for Sodium 22, Na 22. Na 22 is a natural radioisotope of cosmogenic sources. Sodium is the most common element in salt water: NaCl, sodium chloride.
The Na 22 peak at 1274.54 KeV . is the only well formed peak. The actual energy is 1275.5 KeV, 186 samples, and counts per second in 10 hours are 0.00516.
Cosmogenic nuclides- Physics. What are cosmogenic nuclides? Cosmogenic nuclides are isotopes that are produced by interaction of cosmic rays with the nucleus of the atom.