Extraction of thermalized projectile fragments from gas

The NSCL gas cell and quadrupole ion-guide system has been used to study the thermalization of fast nuclear reaction products in a buffer gas. The fraction of radioactive ions that can be extracted from the gas cell is dramatically suppressed by space charge created by the stopping ions. The results of a review of the ion yields from the NSCL and from other gas cells from the literature with different sizes and different incident particle energies shows an overall consistency with a dramatic decline in extraction efficiency at high ionization rates.