New focus for ORNL

A new Oak Ridge National Laboratory initiative will consolidate and expand the lab’s research and development efforts in radiation detection technologies.

The goal of the new Center for Radiation Detection Materials and Systems (CRDMS) is to establish ORNL as the USA‘s central national laboratory for innovation and development in the field of radiation detection materials and systems.

“This centre takes what is currently a collection of relatively independent projects and pulls them together into a program with more focus on major goals,” said Centre Director Lynn Boatner. “It will co-ordinate and concentrate our efforts by bringing together ORNL physicists, chemists, materials scientists, crystal growers, nuclear engineers, and electrical and electronics engineers.”

“There is a lot of expertise here, but we have lacked a cohesive program. Now, in place of individual proposals and relatively small projects, we plan to take on more global challenges,” continued Boatner, a materials physicist in ORNL’s Condensed Matter Sciences Division and an ORNL Corporate Fellow.

Radiation detection research at ORNL began with reactor and physics instrumentation developed here in the early 1940’s. Today, ORNL is said to be a leader in the technology behind radiation detectors that use scintillators, which are high-density crystal, glass, or polymeric materials that give off photons of light when exposed to radiation. The photons are then amplified and converted to electrons which produce an electrical signal that is measured to give a radiation detection reading.

Radiation detectors are fabricated from a variety of materials and include materials like germanium and cadmium zinc telluride and scintillators such as lanthanum bromide and lutetium silicate. Materials’ properties vary widely: germanium detectors have excellent energy resolution but must operate at cryogenic temperatures, while scintillators operate at room temperature but generally have poor energy resolution.

The new centre will focus on new crystal growth, fabrication, and characterisation methods, continuing ORNL’s record of scintillator materials development via crystal growth, hot pressing, glass synthesis, sol-gel processes, and other novel methods, Boatner said.

Hot pressing uses pressure and heat to mould ceramic powders to form high-density bodies with controlled microstructures. In sol-gel chemistry, nanoparticles are formed in a liquid phase, condensed into a gel, and dried at low temperatures. The process allows scientists to change the structure of the material at the nanoscale and create ceramics at near-room temperature.

At ORNL, Boatner and colleagues are using a hot press-based process to develop a more versatile, faster way to produce large inorganic scintillators by first synthesising zinc oxide nanoparticles doped with gallium.

Boatner added that the new centre will hone technologies to detect illicit nuclear threats such as “dirty bombs,” locate stolen nuclear weapons, and verify international agreements to dismantle and convert nuclear warheads into fuel for US nuclear power plants.