Accelerator Technology at NSCL

Background

The use of accelerators in basic and applied research as well as in medical applications has blossomed since the discovery of X-rays in the late 19th century. For basic research, accelerators are most commonly used in high-energy physics and nuclear physics. For example, at the European center for high-energy physics (CERN) just outside the city of Geneva, the accelerators occupy a circle more than 5 miles in diameter. However, the largest number of accelerators are built for medical uses, cancer therapy, radioisotope production, etc. It is very likely that a hospital near you uses some kind of accelerator.

The trim coils of the K500 cyclotron with current leads. more

The purpose of accelerators in basic research is to accelerate ions or electrons to high speed and then collide these beams of energetic particles with a fixed target (or sometimes another counter-rotating beam). By studying the products of these collisions scientists can learn a great deal about the properties of the nucleus of the atom and the forces that keep it together.

Although dwarfed in size by the large high-energy physics accelerators, medical accelerators range from table-top devices (electron linacs) to very large facilities like Loma Linda in California and HIMAC in Japan. These accelerators produce energetic beams of electrons, protons, neutrons, or heavier ions to treat cancer patients.

The Role of NSCL

NSCL has a long tradition of accelerator expertise, starting in the early 1960's with the design and construction of a 50 MeV proton cyclotron. This cyclotron had a very precise beam used to do detailed measurements in nuclear physics. In the early 1970's, superconducting technology had developed to a point where it was feasible to build a more compact—and less expensive—accelerator using superconducting coils at liquid helium temperature. At these temperatures some materials lose their resistivity, and it is possible to produce high magnetic fields, necessary to contain the accelerated beams, with no power consumption.

In 1981 the world's first superconducting cyclotron (K500) was operated at NSCL. It was followed in 1988 by a larger cyclotron (K1200) of similar design. These two cyclotrons are now used in a coupled mode, in which the beam from the first machine is further accelerated in the second one, for nuclear physics research. These beams are also used to study the effect of cosmic rays in electronic devices in satellites, and on humans during long space-flight missions, to Mars, for example.

NSCL staff also designed and built a superconducting cyclotron used to accelerate deuterons—hydrogen ions with an extra neutron—to produce neutrons. These neutrons are used for treatment of cancer patients at the Harper Hospital in Detroit. NSCL-developed superconducting cyclotron technology is now being used to build a highly cost-effective and compact 250 MeV cyclotron for cancer therapy.