Re: impurity capture

[Tom Banks <tbanks@socrates.berkeley.edu>]

> I checked your revision note. Basically I get the same results,
> some issues with the atomic/molecular normalization still need
> discussion. See
> http://www.npl.uiuc.edu/twiki/bin/view/Main/ImpurityFormalismPK

Dear Bernhard et al.,

during today's teleconference discussion about Peter's recent check of my
revised high-Z numbers (see link above), the issue of molecular vs. atomic
concentrations once again reared its ugly head.  Although we have not had
much time yet to read over and think about Peter's latest calculations, it
would appear that factors of 2 discrepancies are again involved.  Namely,
when treating H2O, Peter argues to divide the transfer rate by 2 (see page
4 of his notebook)

  http://www.npl.uiuc.edu/twiki/pub/Main/ImpurityFormalismPK/purity06a.pdf

while your "Oeff" table entry (which I took from page 5 of your Run9
presentation)

  http://weak0.physics.berkeley.edu/weakint/research/muons/private/bernhard/Run9_Impurity-Report-28-4-06.pdf

multiplies the transfer rate by a factor of 2.  Thus Peter's theoretical
yields and Berkeley's theoretical yields for H2O and Oeff are off by a
factor of ~4.  Although this does not ultimately affect our delta_r/Y
values (by much), it is relevant when attempting to make connections
between yields and concentrations, etc., so this isn't an entirely
academic exercise.

So, Bernhard, can you clarify your reasoning for us, or point us towards
an existing explanation of your notation?  When you write "Oeff," that's
referring to the atomic concentration of oxygen in water molecules, is it
not?  We know that you spent a good deal of time thinking about the high-Z
impurity situation, so we figure you probably have good reasons for
handling things the way you did.

Thanks,
Tom