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MEASUREMENT OF HELIUM DIFFUSION IN ZIRCON AT LOW TEMPERATURES
Lead Researcher: Dr. John Baumgardner
The most powerful line of experimental evidence supporting the RATE conclusion that billions of years of accelerated nuclear decay occurred during extremely brief episodes in the earth’s past involved the careful measurement of the helium diffusion rate in zircon crystals extracted from drill core from granitic basement rock in northern New Mexico. Those measurements showed that the measured high levels of retention of radiogenic helium in the zircons could not possibly persist for more than about 6,000 years, given the high helium diffusion rates measured for those tiny crystals. Note that helium arises from the alpha particles produced as uranium and thorium decay to lead. An alpha particle, consisting of two protons and two neutrons, acquires two electrons to become a neutral helium atom when it comes to rest in the surrounding medium. The measured amount of radiogenic helium matched closely the amount of radiogenic lead that also was present in the crystals. The glaring problem with that finding was that the decay rate for uranium to lead, as measured today in the laboratory, yielded an age for the zircons of some 1.5 billion years, while the measured helium diffusion rate constrained the time span to only 6,000, a huge disparity. Two other RATE projects pointed strongly to the conclusion that the younger age is indeed the correct one. Because the implications of this finding are so profound, there is obvious motivation to confirm it for other rock formations. Two members of the original RATE team, Andrew Snelling and John Baumgardner, have collected rock samples and isolated the zircons from these samples and are ready to have the helium diffusion rates measured for these zircons. The measurement involves determining the amount of helium diffused from the sample over a specified time interval with the temperature held constant. The temperature is then stepped in 50 °C steps over a range from 450 °C down to 150 °C and back to 450 °C again. Since the diffusion rate varies exponentially with absolute temperature, some of the lower temperature steps may require several hours. The estimated cost for diffusion measurements for each of these samples is $15,000 for a total cost of $30,000. The challenge is finding a laboratory able and willing to undertake these measurements. See http://www.icr.org/i/pdf/technical/Young-Helium-Diffusion-Age-of-Zircons.pdf for a summary of the RATE project that performed the original zircon helium diffusion measurements.
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