SNEAP 2000 Lab Report



Reporting period October 1999 thru October 2000  
Tom J. Gray and Robert D. Krause

James R. Macdonald Laboratory
Kansas State University
Manhattan, KS 66506-2604

Tandem Operations

This report covers the period of October 1999 - October 2000 for the James R. Macdonald Laboratory at Kansas State University. Throughout this period we have been extremely busy with new installations, modifications, unscheduled openings, etc.

In January, 2000 our EN tandem charging belt broke. This was a difficult time because we had anticipated this belt would last until the arrival of our new NEC pelletron system in March. We were however able to borrow a used EN charging belt from the Weizmann Institute in Israel. This allowed research faculty and students to finish experiments until the new pelletron system arrived. In late March, 2000 the new NEC pelletron system arrived, installation was completed and acceptance tests were finished by April 19. This NEC pelletron system has given us vastly improved beam stability. The tandem terminal gas stripper was converted to a recirculating stripper with the installation of an Alcatel 5150 turbo pump driven by the three-phase georator of the pelletron system.

During this reporting period the tandem has logged 2,092 hours of actual beam time operation. The total amount of down time was approximately five weeks due to the pelletron installation, broken charging belt and the terminal turbo installation.

We have experienced increasing problems with aging laboratory equipment for which there are no longer spare parts or replacements. As time goes on this is an increasing problem.

Ion Sources

The EN tandem Van de Graaff accelerator is injected by two different ion sources. The Middelton high intensity sputter source operates 90% of the time, and the diode ion source is used the remaining 10% of the time. The diode source is used to produce primarily beams of hydrogen and fluorine. The Middelton source is used to produce primarily beams of hydrogen, boron, carbon, oxygen, fluorine, magnesium, silicon, chlorine, copper and iodine.


The Linac was used to provide bunched beam switch time widths >= 250 ps for timing experiments and accelerated Mg beams for an Auger electron experiment. A Linac new computer control system based upon the ATLAS experience is approaching completion. We anticipate installation of this new system during early 2001. A recirculating differentially-pumped gas stripper has been installed for post stripping of beams prior to beam analysis by the Linac 90 degree magnet. This gas stripper is in addition to the capability for foil post-stripping of beams from the Linac. A new UHV target chamber for COLTRIMS experiments is currently being installed on the first switching magnet for the Linac. The prebuncher for the pulsed beam system was rebuilt to address low Q problems that impacted prebuncher performance. The LHe refrigeration system continues to operate with minimal maintenance. We operate the refrigerator continuously for Linac cooling and to provide LHe for the cryogenic electron beam ion source in the laboratory. The Sullair compressor currently has 84593 hours of operation. We continue to run the LHe refrigerator without LN2 precool.


This work was supported by the Division of Chemical Sciences, Office of Basic Energy Sciences, Office of Energy Research, U.S. Department of Energy.


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