About SNS

Keeping it fresh

Partnering with industry keeps new tech flowing


Optical fibers sprout from photomultiplier tubes in a cross-fiber neutron detector. Photo: Jason RichardsOptical fibers sprout from photomultiplier tubes in a cross-fiber neutron detector. Photo: Jason Richards (hi-res image)

ORNL is teaming up with PartTec, an Indiana-based scientific equipment manufacturer, to make the most of the world’s premiere neutron scattering research facility, the laboratory’s  Spallation Neutron Source. SNS researchers use the phenomenon of neutron scattering to reveal the inner structure of a range of materials, from metals to microbes. They do this by aiming a beam of neutrons at a sample of material and then measuring exactly how the direction and speed of these minute particles change as they strike and pass through the sample.

The key to recording, analyzing and ultimately understanding the results of these collisions lies in a piece of equipment called ascintillation detector, which intercepts neutrons shortly after they exit the sample. When a neutron strikes the detector, it produces electric signals that are fed into a data collection system. Analysis of the information enables researchers to determine where the neutrons struck the detector, and the pattern and intensity of the impacts tell them quite a bit about the internal structure of the sample material. Thoroughly investigating the structure of a sample in this way can involve collecting data from many millions of neutrons.

Partners in science

PartTec’s role in supporting the laboratory’s neutron scattering inquiries has been to help the SNS ramp up production of detectors needed for experiments on two of the spallation source’s key instruments.
According to SNS instrument development scientist Richard Riedel, PartTec originally specialized in building detectors for high energy physics research facilities but eventually branched out in toneutron detectors as well.  Several years ago, when a team of ORNL researchers was running experiments on the University of Indiana’s pulsed neutron source, they got to know the PartTec staff members who were working on the facility’s detectors.  

At the time, the SNS detector development group was building prototypes for the detectors that would be installed on the spallation source’s POWGEN and VULCAN instruments.  However, the number of detectors that would be needed to fully equip these instruments was greater than the small group could handle. “When we saw PartTec’s work at UI, we decided to ask them to help us manufacture these units,” Riedel says. “We knew the level of subtlety required to build this sort of instrument was very high—not just any manufacturer could do it.”

PartTec is currently involved in manufacturing two different detectors for the SNS. One of these, the latest addition to the facility’s analytical repertoire, is a next-generation cross-fiber detector.“Originally PartTec provided only a portion of each detector,” Riedel says, “but that worked out so well that they now manufacture the whole instrument.”

The cross-fiber detector uses a woven optical fiber assembly to carry light created by neutron strikes from the scintillator to a bank of photomultiplier tubes for amplification and analysis. Riedel notes that the optical fiber assembly on this detector is “more sophisticated, but less complex,” than that of similar detectors—using one-tenth as many fibers, to achieve similar results. The detector’s “woven” arrangement of fibers combined with the sophistication of the software that interprets the data they gather,  enables it to do more with less.

The other focus of the ORNL-PartTec detector collaboration is an updated “Anger” detector, named after its inventor, University of California scientist Hal Anger. The Anger detector, which has a much higher resolution than the cross-fiber instrument, detects incoming neutrons using a scintillating glass plate. As is the case in the cross fiber detector, light resulting from neutrons striking the scintillator is boosted and analyzed by photomultiplier tubes and then passed along to a data collection system.
Although they both employ scintillators to detect incoming neutrons, the two detectors are designed for use with different kinds of samples. Anger detectors are often used when a tightly focused pattern is anticipated—like those that result from the analysis of a single crystal. The cross-fiber detector, on the other hand, is tailored to detect the more diffuse, ring-shaped patterns that are characteristic of analyses of powders and larger samples.

Riedel recalls that, at first, PartTec was involved only in making the electronic circuit boards for the Anger detector. “Each detector contains about 20,000 components,” he says. “PartTec started out providing just the circuitry, but now we’re talking about having them manufacture the entire detector for us.”

Keeping it fresh

Partnering with industry on detector manufacturing helps to ensure that a fresh stream of technology flows into the private sector.  This also frees up laboratory scientists to concentrate on pushing detector design beyond the state of the art.

An example of this sort of innovation can be seen in the improvements the collaboration has made to the design of the cross-fiber detector—particularly to the woven optical fiber assembly. “Similar detectors designed in Europe to serve the same purpose are much more complex,” Riedel says. “We refined the design, and now some European neutron scattering facilities are interested in buying PartTec detectors. PartTec has been instrumental in helping improve the manufacturing process as well as providing improvements in key parameters such as detector efficiency.”

Riedel notes that the detector development group handed off the technology behind their previous generation of gas-filled detectors to General Electric, their manufacturing partner at the time. The laboratory’s collaboration with PartTec has been similarly beneficial.

“The relationship with PartTec has been good for us because it allows us to focus on advancing the technology, rather than on manufacturing,” Riedel says. As a result, the latest generation of instruments produced by this collaboration is faster, more accurate, and integrates better with state-of-the-art computer hardware.

The relationship has also paid dividends to PartTec. Interest in their detectors has come from both international research facilities and the US military as well as from organizations that monitor the transportation of fissionable material.“This is been a good partnership,” Riedel says. “PartTec is easy to work with, and they’re very interested in building collaborative relationships.”

 -  Jim Pearce,  July 01, 2013

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