From: eaglesondouglas@gmail.com   
      
   I am currently looking at the technology for home Radon testing.   
   I am not currently at the point of reporting the topic, but am   
   impressed at the alpha track etching polymer sensors. But they   
   seem to have a need for a minimum exposure time of three months.   
   Some kind of sensitivity issue, I believe, in order to sense   
   the 4pCi/liter maximum allowed home Radon level.   
      
   At one time I looked at the NIST Radon releasing Radium sources.   
   They were to be placed in an air volume enclosure to cause a   
   predictable Radon concentration.  My thinking now is how to   
   increase the alpha sensor sensitivity.  As a partial solution   
   I designed a special Radon release system.   
      
   It is a vacuum gas release system. The Radon source is put in   
   a vacuum chamber, like a belljar. The radon gas release will   
   be the only alteration of the jar pressure.  This means the   
   size of alpha sensed volume is the whole belljar.  The alphas   
   have the capacity to traverse the whole jar vacuum.   
      
   This concept, I believe, at least allows high precision alpha   
   sensor quality assurance testing.   
      
   My next question is the lower limit of detection problem.   
   How many tracks are found in a sensor readout?  And what   
   is a sensor background?  If the alpha tracks begin the second   
   a polymer is extruded, is there a process of nullifying air   
   contact in the handling?  They are shipped in vacuum bags for   
   this reason.  But what happens during construction and assembly?   
   And what happens during the return of the sensor to the   
   analysis lab.   
      
   The concepts indicates to me that the 3 month signal is   
   required to "over shadow"  the background signal.  The time   
   of post handling(return to lab) is several days, just what is   
   desired as the fast sensing use of such of such a sensor.   
   Truly turning off an alpha sensor is something like putting   
   it in a liquid filled vial.  Maybe liquid delivery and   
   liquid return could lower the detection limit?   
      
   It is not unreasonable to simply ship and receive and return   
   ship using a water filled vial.  Sensor air drying on exposure   
   should not be a significant con-founder.   
      
   A deeper question>  I once tried to make alpha and proton sensors   
   using solid nematic crystal films.  The concept being to heat the   
   crystal film and subject it to an intense rotating magnetic field.   
   My failed test did indicate that a large trial by error recipe could   
   be discovered.  Proton sensing remains a true goal of mine.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)