Beam cooling by frictional forces: Monte Carlo calculations and design studies

Simulation Study of Frictional Cooling for True Muonium Production

“…These processes may become very harmful at such low energies as used in frictional cooling. The actual applications of frictional cooling in experiments are realized with a strong solenoidal field which could focus the muon beams into a small spatial area [8]. The present studies would add the comprehensive ideas for frictional cooling to be minimized in emittance density distribution even without solenoidal magnetic field.…”

“…There are practical questions about the applicability of this technique to the low energy muon beams with improved qualities because multiple scattering in moderator deteriorates longitudinal cooling [8]. Thus, several experiments such as the POP (Proof of Principle) experiment had been performed and a significant increase was observed in spectral density with a time of flight technique [9], and other experiment exploited dissociated H 2 + beam by alpha particles emitted from radio activities.…”

Frictional cooling of positively charged particles

“…Straggling of energy losses to the medium prevent a beam from becoming truly mono-energetic in a frictional cooling scheme, inducing a spread of the beam energy around T eq . A study of the frictional cooling of µ − in [4] found that the spread of the energy distribution of a cooled beam is independent of the beam's initial spread and, as table 1 shows, decreases with increasing gradient of the stopping power. In the table, the gradient is calculated from the parameterization of the stopping power for hydrogen on µ − from [8], using the measured parameters given in the paper.…”

“…When the reverse is true, the particle is decelerated. At the kinetic energies where the two powers are Table 1: Energy spreads of frictionally cooled beams of µ − in H 2 gas from [4] and µ + in He; and gradient of the stopping power of H 2 on µ − from the parameterization in [8] equal, particles are at an energy equilibrium. If the stopping power is greater than the accelerating power at energies above this equilibrium point and vice versa below it, then the point is stable and attractive.…”

“…Simulations of frictional cooling [4] show that it can achieve the desired emittance reduction and potentially produce high-luminosity muon beams [3]. Previous work on frictional cooling, including both simulation and experiment [5], focused on cooling µ − beams and assumed the cooling mechanism would be identical for µ + beams.…”