https://doi.org/10.1007/s100530050134
The two-photon 2s → 1s transition of the fully-ionized muonic boron migrating in helium
Department 52 (O-52)
Institute of General and Nuclear Physics,
Russian Research Centre "Kurchatov Institute",
123 182 Moscow, Russia
Corresponding author: a roman@cerber.polyn.kiae.su
Received:
21
October
1997
Revised:
16
January
1998
Accepted:
2
March
1998
Published online: 15 June 1998
In recent experiments performed at the Paul Scherrer Institute
(PSI) measurements were made of the yield 
of the two-photon 
transition
of the fully-ionized muonic boron formed and quenched in a gaseous
mixture of diborane B2H6 and helium. In the present work this yield
is calculated for an idealized case of a very low diborane density
when the main 2s state decay modes competing with the two-photon
transition are due to the electron transfer from helium to the μ-ion.
As the rate of this transfer depends strongly on
the relative velocity, a treatment is needed of the whole kinetics
of processes occurring with the μ-ion in helium. Accordingly, within the optical
model with a complex potential constructed before we
calculate cross-sections of the elastic scattering and electron transfer. Then the
time evolution of the μ-ion energy is considered and, finally, the
yield is calculated. It proves that at helium
pressures 
Torr this yield may be written in the
form: 
,
where the factor C is greater than unity and increases rapidly with the
initial energy E0 which the μ-ion has after its formation in the
diborane molecule. Thus measurement of the pressure dependence of allows E0 to be estimated. The results obtained make it possible
to suggest a similar parametrization of the PSI data.
PACS: 34.50.Bw – Energy loss and stopping power / 34.70.+e – Charge transfer / 36.10.Dr – Positronium, muonium, muonic atoms and molecules
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1998
