Is there something wrong with the Spallation Neutron Source?
DOI: 10.1063/PT.5.010133
Before becoming Physics Today‘s online editor in May of 2010, I ran the magazine’s Search and Discovery department. In that job, my prime directive was to find and write about the most interesting and important research in physics and its related sciences. My biggest worry was that I’d overlook a major discovery—not a Higgs boson or room-temperature superconductivity, which would get instant and voluminous press coverage, but something like asymptotic freedom or giant magnetoresistance , which didn’t.
Asymptotic freedom and GMR earned their discoverers Nobel prizes decades after the original papers were published. Finding such significant work when it first appears in print is tough for a science journalist, but not impossible. You need good contacts in the physics community, a willingness to pore through lists of preprints, and a familiarity with the big unsolved problems in science.
Less effort is required in the case of major new facilities. After NASA launched the Chandra X-ray Observatory in July 1999, I knew I wouldn’t have to wait long before a newsworthy result appeared. To justify the expense of launching and operating a space observatory, the instruments onboard must be much better than their predecessors. My first Chandra story , about the cosmic x-ray background, appeared in May 2000.
The Spallation Neutron Source at Oak Ridge National Laboratory in Tennessee is the world’s most powerful neutron source. Unlike some other big projects, the SNS was completed on time, in June 2006, and slightly under budget at $1.405 billion. One month earlier, in an article for Physics Today, SNS director Thomas Mason, introduced the new facility:
A negatively charged hydrogen ion accelerates down a linac to nearly a billion electron volts—90% of the speed of light—and punches through graphite foil that strips off the ion’s two orbiting electrons. The resulting proton enters a ring where it and other protons are stored and accumulated into pulses that are fired at 60 Hz toward a vessel of liquid mercury. In a process known as spallation, the protons collide with atomic nuclei in the heavy metal and knock out short, intense pulses of neutrons. Those neutrons are then guided through as many as 24 beamlines to the myriad instruments and detectors used for experiments.
That’s the vision behind the Spallation Neutron Source (SNS), a $1.4 billion facility nearing completion at Oak Ridge National Laboratory (ORNL). Currently in its testing phase, the facility is expected to produce the most intense pulsed neutron beams in the world, with each pulse yielding neutron fluxes estimated at 20 to 100 times the peak intensity obtainable from fission reactors. Materials of ever-increasing complexity are key elements of today’s technologies and underpin the world’s industrial and economic development. Consequently, the spallation source will surely find broad applicability in fields far beyond the condensed matter systems to which neutron scattering has traditionally been applied.
Now, six years after SNS made its first neutrons, I’m wondering if there’s something wrong with it. In particular, I’m wondering where the science is.
The SNS is hardly unproductive, as the long and diverse list of research published in 2010 demonstrates. Still, none of those 2010 papers were published in Nature or Science and just one appeared in Nature Physics.
To get a sense of how SNS compares with other spallation sources, I took advantage of the full-text search option on the Physical Review website. My search for the phrase “spallation neutron source” in all 11 Physical Review journals published last year yielded 51 hits.
Not all the hits corresponded to research that made use of spallation neutrons. Some papers were theoretical predictions; some were about the neutron sources themselves; and some were relevant to, but not about, research at neutron sources. Because the search looked for any occurrence of “spallation neutron source,” papers by SNS staffers, even if they weren’t about research done with the SNS, generated hits.
The results surprised me. By my count, the SNS yielded 5 PR papers, but two other spallation neutron sources, ISIS at the Rutherford Appleton Laboratory in the UK (7 papers) and SINQ at the Paul Scherrer Institute in Switzerland (13 papers), were more productive.
Science also has a full-text search option. In that journal, the only occurrences of “spallation neutron source” in research papers corresponded to two studies that appeared in 2008. Both reported results on the heavy-fermion superconductor cerium-cobalt-indium derived at SINQ.
The US paid $1.4 billion for the SNS, a facility whose publicity brochure says, “The capabilities of the SNS will enable scientific breakthroughs that will enrich our lives in ways we haven’t even imagined.”
I admit that the title of this post is deliberately provocative, but it’s also intended as an open question: Is there something wrong with the SNS?
