Muon Cooling via Ionization and Tests of Muon Acceleration Cavities

Don Hartill, Mentor

High energy muons can be used to produce a very intense well defined 
neutrino beam and possibly a very high energy high luminosity collider.  
Key to this possibility is a method of cooling (reducing the six 
dimensional phase space) the muon beam by ionization whereby ionization 
energy loss in a low-Z absorber reduces the beam energy in all three 
coordinates followed by an acceleration in only the longitudinal 
coordinate.  The transverse size of the beam is thereby reduced while 
maintaining the energy of the muon beam. Unfortunately, straggling in 
the energy loss process causes the longitudinal phase space to increase 
leading to significant particle loss during cooling.  Initial results 
from simulations carried out this past year indicate that by suitable 
manipulation of the phase of the accelerating cavities, this effect 
can be significantly reduced or eliminated.  The REU student would 
continue this work to confirm its effectiveness and explore the ultimate 
reduction in six dimensional phase space using this approach.  

In addition, the student would assist in the testing of two 500 MHz 
superconducting rf cavities that are prototypes of the cavities that 
would be needed to accelerate the muons to high energy after they 
were successfully cooled.  Assisting with these tests would represent 
about 30% of the student's activity during the summer.