Eur. Phys. J. Special Topics 150, 265-267 (2007)
https://doi.org/10.1140/epjst/e2007-00319-0

Efficient and fast thermalization of Rare Isotope Beam from projectile fragmentation

The cyclotron gas stopper project at the NSCL

¹ National Superconducting Cyclotron Laboratory NSCL, Michigan State University, East Lansing, MI, 48824-1321, USA
² Department of Physics & Astronomy, Michigan State University, East Lansing, MI, 48824-1321, USA
³ Department of Chemistry, Michigan State University, East Lansing, MI, 48824-1321, USA
⁴ RIKEN, 2-1 Hirosawa, Wako, Saitama, Japan

Corresponding author: bollen@nscl.msu.edu

Received: 31 January 2007
Published online: 8 December 2007

Abstract

Gas stopping is the method of choice for converting rare isotope beams obtained via projectile fragmentation and in-flight separation into low-energy beams. Current gas stopper systems for high-energy beams are based on linear gas cells filled with 0.1–1 bar of helium. While successful for a number of experiments, they are limited in the maximum beam rates that can be used and exhibit long extraction times that can lead to decay losses for very short-lived isotopes. To avoid these limitations, a new type of gas stopper is being developed at the NSCL/MSU based on a cyclotron-type magnet with a stopping chamber filled with helium buffer gas at low pressure. RF-guiding techniques are used to extract the thermalized ions from the central region.