Experience with the NEG (Nonevaporable Getter) Strips at the Brookhaven Heavy Ion Transport Line

摘要

The AGS and the Tandem Van de Graaff, two valuable physics assets, are now jointed together by a transport line of 700 m in length. This line allows heavy ions from the Tandem, up to a fully striped silicon (M = 28) to be injected into the AGS and accelerated to energies of approximately 15 GeVamu. New areas of physics research at very high nuclear densities can now be studied using some of the extensive experimental facilities already existing at the AGS. With the addition of a booster synchrotron between the Tandem and the AGS, all heavier ions up to gold can also be accelerated. To minimize the beam loss due to charge exchange between the partially stripped heaviest ions (i.e. Au + 33 at 1 MeVamu) and the residual gas molecules, a vacuum of 10 /sup /minus/8/ Torr is required for this transport line. To achieve this vacuum, we have opted to use the combination of small ion pumps (20 1s diode type) and simple geometry was implemented which offers low cost (<$200m), easy installation and maintenance. Pressures of 10 /sup /minus/10/ and low 10 /sup /minus/9/ Torr have been maintained over the last two years following the initial activation. This paper describes the NEG strip system, and the experience obtained during the installation and the operation of this 700m heavy ion transport line. (ERA citation 13:034672)