Hot items answers

["Dale E. Boyce" <dale@radpro.uchicago.edu>]

I received several guesses from people on ranking the watch, fiestaware,
etc.  So far no one has scored 100% though some were close.  The
answers are:

#1  The Rolex watch reads 50,000 cpm with an Hp190 end window GM.
    The radium in the dial and hands has radiation damaged the face
    of the watch, turning it from white to brown.

#2  The Fiestaware reads 5,000 cpm and also makes a good alpha check source.
    Give yourself full credit if you switched 1 and 2 since I didn't
    specify total or specific activity.

#3  The soil from Chernobyl <~ 100 cpm above background with the HP190
    About half the sample came from the Chernobyl site and half from
    Prypiat.  The person who took the sample said that they got readings
    of about 1 mrem by digging down a few inches and placing the probe
    in the hole.  1 mrem is about 2400 cpm with an HP190.

#4  The mushrooms.  Most plants concentrate CS-137 from the evironment
    and mushrooms evaporate a lot of water.  These particular mushrooms
    had the added advantage of growing in a bog about 500 km from
    Chernobyl.  They are about 1 nCi per gram of Cs-137.

#5  The graphite.  Reactor graphite is highly purified and made from
    petroleum so even the C-14 is dead.  I have had the opportunity
    to analyze some very heavily irradiated graphite and was able to
    detect Ba-133 and a few rare earths.  This particular graphite
    does show any of the activation products.  The only activity
    detected was less than a picocurie total of Cs-137.  Specific
    activity is of the order of 10 femtocuries per gram.  This sample
    was found on the ground within a year post Chernobyl by a divinity
    student.  The student became concern that it appeared to be graphite 
    and was near where CP-2 (Chicago Pile 2) once stood.  So he brought 
    it to me.

    Presumably, the graphite sample was contaminated by fallout, possibly
    Chernobyl, possibly left overs from the atmospheric testing.  Typical
    soil concentrations of Cs-137 are between 0.1 and a few pCi/g.

Dale Boyce
dale@radpro.uchicago.edu