celeratorceleratorThe photograph shows the beam end of the old Van de Graaff accelerator that we had from about 1965 to 1990.
History
Union College obtained it's first nuclear particle accelerator in about 1965 with a grant from the Atomic Energy Commission. Porfessors Goble, Schwarz, and Pilcher were instrumental in writing the proposal and geting the machine installed. It was a High Voltage Engineering 400 KeV Van de Graaff machine capable of currents in excess of 100 micro-amperes. The original purpose was to accelerate deuterons into a tritium target, and so produce 14 MeV neutrons. The neutrons were used to study short-halflife isotopes.
When I took over the machine in about 1970, focus shifted to other uses such as PIXE
(proton induced x-ray emission), elastic scattering, and occasionally 
channeling and RBS
(Rutherford backscattering) studies. We had a lot of fun with that accelerator over
the years. Many students did senior projects ranging from the development of
auxillary circuits to channeling to PIXE.
Recognizing the shortcomings of using 400 KeV protons (in particular for PIXE and RBS work), the department decided in about 1990 to acquire a new accelerator. The effort was spearheaded and the proposal was written by David Peak. Some college funds were used to match NSF funds, and so we were successful in getting the new accelerator installed.
The Pelletron
The new machine (color picture on the left) is a small tandem electrostatic accelerator made by the National
Electrostatics Corporation. It operates at a potential of up to 1.1 MV, producing
protons of up to 2.2 MeV in energy, and alpha 
particles of up to 3.3 MeV of energy.
The beams currents typically run to something between 50 and 100 nano-amps.
It has been a pretty reliable machine over the years. Typical maintenence usually
rebuilding the ion source once a year, and replacing the bearings of one of the
turbo-molecular pumps (they seem to last about 18 months or so). Scott
LaBrake is now doing the accelerator.
Applications
We have used this accelerator several ways in recent years. We usually do one experiment in our "modern physics" course. This is often a PIXE experiment, but we have sometime done the "Rutherford" scattering experiment in which the angular distribution of the scattered particles (protons or alpha) is measured. Also, we have used the accelerator for two experiments in our junior lab course. In addition, we have often had studentts doing senior projects. The last project (1997-1998) was done by Emily Schwartz using PIXE to analyze sediment from the Mohawk River.
The color photograph on the right shows the scattering chamber used since 1965 for scattering experiments such as RBS studies of thin films. A Faraday cup is attached to the end line. When we do PIXE (proton induced X-ray excitation) we replace the faraday cup with a small chamber. The X-ray detector (in the background at the left edge of the photograph) is placed beneath.
This page by jonesc@union.edu