Thanks. In addition to the cold trap technique which Russ George mentioned and offered to help with - there is this:
https://aip.scitation.org/doi/10.1063/1.1143286 “Separation of helium and deuterium peaks with a quadrupole mass spectrometer by using the second stability zone in the Mathieu diagram” From: Jed Rothwell JonesBeene wrote: Good point. Jed knows the details of the mass spec Mizuno had available, which was damaged in the earthquake. IIRC it was being repaired when the paper was written and its present status has not been reported. Perhaps he will comment on this. ULVAC quadrupole mass spectrometer: model YTP-50M. Built in precision meter, ULVAC, GCMT G-Tran ISG-1 I do not know if this has the umph to measure helium. It is working. The SEM is still busted and will take $20,000 or $30,000 to fix. Surely Mizuno was looking for helium before his lab was destroyed - so it is expected that he knows how to resolve the small mass difference. I do not know if he did this or not.
