In reply to Jones Beene's message of Tue, 12 Apr 2011 06:43:26 -0700: Hi, [snip] >In its simplest form, the 'Reifenschweiler effect' is a substantial >reduction of beta-decay due to cavity confinement. The decay rate of tritium >is reduced by more than 25% when the isotope is absorbed in 15 nm >titanium-clusters in a temperature window in between 160-275 C. At 360 C the >original radioactivity reappears. > >Why the temperature window, in a range where there is no phase-change in >titanium? Why the return to normality at higher temperature? How much >reduction occurs when going from 15 nm down to 5 nm? Does the effect work >with either Pd and Ni, or is it specific to Ti? Is the effect related to >HTSC in some mysterious way ? More questions than answers, as of now.
I would propose the following conventional explanation. The beta from T is very low energy. T as a hydrogen isotope is readily absorbed by Ti metal (in the form of a Hydride?). At temperatures between 160-275 ºC the heat speeds up the Hydride formation. When the T is inside the metal lattice, the electrons don't have enough "punch" to make it out of the lattice, and hence don't reach the detector, giving the appearance of reduced activity. When it's heated above 360 ºC the Hydride decomposes, and the T leaves the lattice, once again in gas form where it can again be readily detected. This hypothesis is readily falsified by starting with a fixed quantity of T in a sealed chamber, and observing the gas pressure as a function of temperature. Up to 275 ºC it should "decrease", then "increase" again above 360 ºC. (Note that it is necessary to mathematically compensate for the expected normal pressure rise due to heating of a gas in a fixed volume). The real question is more complicated. If maintained in the lattice for years, then heated well above 360 ºC does the radioactivity return to the level one would expect based upon the measured decay rate of T? Only that experiment will tell you whether or not the lattice confinement actually affected the decay rate. Regards, Robin van Spaandonk http://rvanspaa.freehostia.com/Project.html
