Simulations
A variety of detailed numerical calculations is being carried out to optimize and characterize the system. These simulations are based on realistic magnetic fields and include the Lorentz force, energy loss, charge-exchanging collisions, and small-angle multiple-scattering.
Simulations are performed for key isotopes covering different elements and different magnetic rigidities.
Example of simulation results
These figures show the results of the simulation of 79Br ions with an energy of 100 MeV/nucleon incident on the solid degrader.
Figure 1: Typical trajectory of an ion being stopped inside the cyclotron gas stopper.
Figure 2: Distribution of the ions prior to being extracted with the RF carpet.
Figure 3: Kinetic energy of an ion as it slows down in the cyclotron gas stopper.
RF-Carpet
An rf-carpet and rf-ion guides guide the stopped ions quickly out of the cyclotron gas stopper. Simulations show that the extraction time is below 5 ms for a helium pressure of 10 mbar.
Figure 1: Schematic drawing of the cyclotron gas stopper extraction region.
Figure 2: Results from a SIMION calculation illustrating an ion approaching an rf-carpet with a 2-Tesla magnetic field perpendicular to its surface.
Operation of NSCL as a national user facility is supported by the Experimental Nuclear Physics Program of the U.S. National Science Foundation.