[Phys-L] Re: Radioactive Bananas

[betwys1 at SBCGLOBAL.NET (Brian Whatcott)]

At 03:29 PM 10/30/2005, Mark Shapiro,  you wrote:

> If you want to check those bananas for K-40, be sure to take a good
> background spectrum with your NaI(Tl) or solid state detector, because
> there is K-40 in most cement and concrete.  Then subtract the background
> spectrum from the measurement that you take of the bananas.
>
> If you want some really radioactive food try Brazil nuts.  They are from
> trees that grow in Monazite sands that have a lot natural radioactivity.
> Typically, 1000 to 7000 pCi/kg of Ra-226 and daughters is found in
> Brazil nuts.
>
> By the way, bananas are not unusually high in K-40.  White potatoes have
> about the same amount of K-40.
>
> Dr. Mark H. Shapiro

Bob Hofstadter who developed the thallium activated sodium
  iodide scintillator approach from previous naphthalene
  scintillator work in Germany forty years ago, first applied
  a torch to a NaI sample to which he added a pinch of TI
  to produce a glaze who scintillation sensitivity was about
ten times greater than naphthalene.
  Lacking the means to buy a big crystal of this material
directly, I am inclined to repeat Hofstadter's route.

About bananas, if not potatoes, I abstracted this from the
article by Biever on p30 on, NewScientist, Oct 22 2005.

"It can happen at the port of NY, dozens of suspect
freight  containers may be opened only to reveal cat-litter,
ceramic tiles or bananas." [in a day]


Brian Whatcott    Altus OK    Eureka!