Speaker
Description
Low-energy antimuons (positive muons) facilitate experiments in the field of fundamental particle physics, especially those involving formation of muonium atoms for QED tests and gravitational experiments. Current sources of muons suffer from large spatial and momentum spread, with transverse sizes on the ~cm scale, which limits the precision of previously mentioned experiments, while cooling techniques available for muons are limited due to their relatively short lifetime (~2.2 μs). Formation of low-energy microbeams of positive muons would pave a way for novel experiments testing the Standard Model, for example searches for the muon electric dipole moment; additionally, finding practical applications in the muon-spin resonance (μSR) technique for characterising magnetic properties of various classes of materials.
In the muCool experiment at Paul Scherrer Institute we are developing a novel concept of phase-space cooling of positive muon beams. Muons of a few MeV are stopped in a cryogenic target with a vertical density gradient of helium gas, and temporarily confined in a homogenous magnetic field combined with a complex electric field. By spatially tuning muons’ collisional frequency with helium atoms, we engineer muons’ drift directions inside the gas target, which leads to transverse and longitudinal compression to the sub-mm size and cooling to few eV energies. Consequently, muons are extracted to the vacuum via windowless orifice, demonstrating the feasibility of generating a low-energy and high-brightness source of positive muons. Future steps will involve re-acceleration to keV energies and extraction out of the high magnetic field region to provide novel high quality muon beams to experiments. Tunable energy range at the acceleration stage, together with future High Intensity Muon Beam (HIMB) upgrades of the CHRISP facility at PSI, will pave a pathway to new generation precision measurements and development of new imaging technologies.
| Academic level | Postdoctoral researcher |
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