Re: impurity capture

[Claude Petitjean <claude.petitjean@psi.ch>]

Dear friends,

unfortunately, I missed yesterdays teleconf, because I did'nt manage to 
dial in. (Do not
know the reason.)

My opinion on the Oxygen issue is the following:
In the line "O" from Toms and Peters table, the transfer rate 
(lambda_pZ) is in my view
correct, since Werthmueller et al. measured several mixtures H_2 + O_2, 
where the
ratio of densities phi was equal to the ratio's of partial pressures or 
atomic concentrations
or molecular concentrations - and phi is well defined as being 1  if 
4.25 E+22 nuclei
are present in 1 cm^3.

The line "O_eff" is misleading or at least very confusing. It lacks a 
precise
definition and should therefore be removed from the table and from our 
discussions.
Naively, I would believe that if for water the molecular ratio (phi = 
n_H2O / n_H2)
would be used as phi, then only half as many Oxygen nuclei would be 
present and
therefore the transfer rate would be half and not twice as much.
But the conventional phi definition is atomic and we should stick to that!

Is this proposal (to forget about the O_eff line) appeasing anyone of you?

With best regards

Claude


Tom Banks wrote:

>>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
>  
>