Field Trip- January 2008


When rock collecting in Missouri turns from rock picks to ice picks, we search for easier prospecting grounds.

This January it was Puerto Vallarta, Jalisco, Mexico.

From Pto Vall, we journeyed by boat and then horseback to the Sierra Madre Occidental Mountains rain forest, where collecting was enjoyable and easy.

A little snorkeling along the way!

Members of our group were from Cuba, Venezuela, Canada and Germany.

Iguanas are everywhere!


Saddle up!

 Cross the river into the jungle.

The instrument of choice for radiation surveying was one of my PM1703M pocket scintillators.


Back to the beach for a siesta under the palm trees.





Gamma studies were performed on the airplane from zero to 33,000 feet, on a metal boat in Pacific Ocean's Bahía de Banderas, on a fiberglass boat out in the Pacific, and of course on the ground in the rain forest. Members of out group came from Canada, Cuba, Germany, Russia and Venezuela.
Some very interesting radiation facts were observed and will be reported in full on the link site soon as I can get them all typed up.
Mainly we wanted to see how low we can get the background radiation to read out in the ocean, away from metal and rocks. With the normal background on the beach at 12 to 16 uR/H, the fiberglass boat was the lowest achievable at only 2 uR/H. We were far enough out to be completely out of range of background from rocks, and the readings were steady enough to indicate that the Radon and daughters in the wind were not much of a factor either, leaving radiation from our own bodies, and Cosmic Rays as the only significant source.
Speaking of Cosmic Rays, we did a Gamma Survey starting at the PVR airport on the ground at almost zero elevation  ( 8 uR/H) up to 33,000 feet ( 26 to 28 uR/H) and back down to about 500 feet at STL. Paying particular attention to the decent stage, from the peak of high 20's, one could observe the rate falling off steadily according to altitude, but not all the way down to ground level. At what I estimate to be 4000 to 5000 feet, the readings leveled off and failed to decline significantly from there to the ground at STL and 4 uR/H.

The conclusion is that at a certain altitude, there is already enough air above you to attenuate or convert most of the easily measured Cosmic rays. Later we envision a field trip to the top of Pikes Peak, loaded with more equipment to make even more measurements, including neutron survey vs. altitude.
Anyone having ideas for similar field trips, send your suggestions and plane tickets to me.
Have fun
George Dowell