Experiments related to Crystalline Beams are in the phase
of rapid expansion. Until recently, only some aspects and
neccessary technologies were examined.
Theoretical advances ,
success with experiments involving neccessary cooling techniques
and high interest for this topic caused several European goverments
to invest in building machines particularly for the Crystalline
Beam investigation. As most focused projects one can mention
ASTRID in Denmark and CRYSTAL in Italy.
However, Crystalline Beam is NOT YET OBSERVED phenomenon.
Best "approximations" we did observe are the ordered states of ions
confined in Pauli traps:
However, Crystalline Beam is NOT YET OBSERVED phenomenon. Best "approximations" we did observe are the ordered states of ions confined in Pauli traps:
In such a small ring it is much easier to observe structure similar to the actual Crystalline Beam expected in the larger machines under construction. Laser cooling was used in this system, too.
As a result of experiments with above mentioned quadrupole stroage ring, group from the Max Planck Institute in Germany have observed the following crystalline structures of Mg ions. Depending on the number of ions "forced" to "cohabitate" the ring, structures varied from the simple (low density) string to the helical structures (at higher densities). Order of particle separation is similar to a Pauli trap case. Micromotion is absent.
There are many related topics which need investigation before we succesfully construct "working crystalline beam" machine. Questions about the limits of laser (and other) cooling mechanisms, space-charge influence on the emmitance and tune shifts caused by it, general particle stability questions (extreme stability is needed and not many experimental data is known about effects of such common accelerator design issues as impedance, rf buckets, nonlinear elements, etc., at such extreme conditions.
This was compilation of the data from Crystalline Beams and Related Issues book, edited by D.Maletic and A.G.Ruggiero. For more info consult the source.