Speaker
Description
High precision experiments using muons ($\mu^{+}$) and muonium atoms
($\mu^{+} e^{-}$) provide unique opportunities to test the fundamentals
of the Standard Model in a second-generation, fully-leptonic
environment, putting a broad spectrum of BSM scenarios within the reach
of next generation experiments. Such experiments include the search for
the muon electric dipole moment, measurements of the muon $g-2$, laser
spectroscopy of muonium and gravitational equivalence principle tests
using muonium. Such experiments would benefit greatly from an intense,
high quality and low energy muon beam.
At the Paul Scherrer Institute, a novel phase space compression scheme
(muCool) has been developed, which would produce such a beam, reducing
the phase space of a standard muon beam by ten orders of magnitude at
$10^{-3}$ efficiency, for a $10^7$ boost in brightness. The muon beam is
stopped in cryogenic helium gas, and using complex electric and magnetic
fields in combination with a gas density gradient the muons are steered
to a mm-size spot, where they have an eV energy spread. From here, they
are extracted through a small orifice into a vacuum and into a magnetic
field free region. The process takes less than 10 $\mu$s, critical to
achieving a good efficiency considering the short 2.2 $\mu$s muon
lifetime.
Several key steps in the phase space compression scheme within gas has
been demonstrated with high efficiency during several measurements at
the PSI muon facility. In this talk, the working principle of the
device, the results of recent measurements and prospects for the future
will be presented.
This work is supported by SNF grant 200020_172639.
| Working group | WG4 |
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