Dear colleagues!
The natural level of
tritium in water is about 7.4*10-6 Bq/g. It means that tritium atomic fraction is 6.2*10-20.
Assuming the same tritium
concentration in initial gas and that we can concentrate it by a factor of 50, the
maximum tritium level about 3*10-18 in
a sample from the reboiler is expected.
I would like to know exactly
the AMS measurement sensitivity to tritium but I doubt whether the influence of
such low tritium content on deuterium measurement is possible (if only initial
gas will be contaminated by tritium). If you do not know the origin of initial hydrogen
gas (which will be taken for the calibration procedure) it is good idea to
check it on tritium content just in a case.
On the other hand perhaps
it should be estimated whether tritium labeling (with measuring in water by Liquid
Scintillation Counter method) can give more accurate result for concentration
factor?
Best regards,
Oleg
From:
vasillie@googlemail.com [mailto:vasillie@googlemail.com] On Behalf Of Alexander Vasilyev
Sent: Tuesday, November 28, 2006
19:30
To: Peter Kammel
Cc: Alexei Vorobyov; claude
petitjean; Francoise Mulhauser; Malte Hildebrandt; Marat Vznuzdaev; Oleg
Fedorchenko; Peter Kravtsov; Victor Trofimov; Semenchuk
Subject: Re: D2 measurements
Dear Peter.
Thanks for the carefull checking in details. It will help to avoid mistakes.
On 11/28/06, Peter
Kammel < kammel@npl.uiuc.edu>
wrote:
iv) A significant uncertainty in your error estimation
comes
from the AMS measurement. We are all extremely
impressed by
the 0.2 ppm uncertainty quoted by the ETH group, but
hope
to get more details how they achieve this, in
particular
regarding the sample preparation.
This is the main error. Perhaps possible to minimize it. But it does not depend
from us.
v) Finally, as an aside, I was wondering whether we
can check the system
by analyzing for tritium. I remember that AMS
is extremely sensitive
to tritium. I am sure Oleg knows whether there is
enough tritium
in hydrogen to be sensitive?
This is question to Oleg. But when we clean water from heavy water
we kill TO2 at all! To my mind we do not have sensible
quantity of
tritium and impossible to make QUANTITIVE measurements.
Apart from this technical remarks, let me emphasize that the deuterium
calibration is of key importance.
- It will eliminate an important systematics in the final MuCap result.
- Trace deuterium detection (with pdm fusion) was a main item in our
CRDF proposal. I am perfectly willing to give up my pdm idea, if
we can provide <0.1 ppm deuterium diagnostics with your
proposed
method.
- It is a beautiful method, pushing the current technological limits.
So we should definitely
perform this task.
With best regards
Peter
With best regards Sasha.
--
Vasilyev Alexander
Petersburg Nuclear Physics Institute,
Laboratory of Cryogenic and Superconductive Technique.