68 research outputs found
Cooling of Sr to high phase-space density by laser and sympathetic cooling in isotopic mixtures
Based on an experimental study of two-body and three-body collisions in
ultracold strontium samples, a novel optical-sympathetic cooling method in
isotopic mixtures is demonstrated. Without evaporative cooling, a phase-space
density of is obtained with a high spatial density that should
allow to overcome the difficulties encountered so far to reach quantum
degeneracy for Sr atoms.Comment: 5 pages, 4 figure
Atom made from charged elementary black hole
It is believed that there may have been a large number of black holes formed
in the very early universe. These would have quantised masses. A charged
``elementary black hole'' (with the minimum possible mass) can capture
electrons, protons and other charged particles to form a ``black hole atom''.
We find the spectrum of such an object with a view to laboratory and
astronomical observation of them, and estimate the lifetime of the bound
states. There is no limit to the charge of the black hole, which gives us the
possibility of observing Z>137 bound states and transitions at the lower
continuum. Negatively charged black holes can capture protons. For Z>1, the
orbiting protons will coalesce to form a nucleus (after beta-decay of some
protons to neutrons), with a stability curve different to that of free nuclei.
In this system there is also the distinct possibility of single quark capture.
This leads to the formation of a coloured black hole that plays the role of an
extremely heavy quark interacting strongly with the other two quarks. Finally
we consider atoms formed with much larger black holes.Comment: 22 pages, 4 figure
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