APS News

April 2011 (Volume 20, Number 4)

Letters To the Editor

Others Contributed More than Van de Graaff to Electrostatic Accelerators

The column “This Month in Physics History” in the February APS News, which comments on the 1935 patent granted for the Van de Graaff generator, is a better example of the power of an eponym than it is of physics history. While the importance of Van de Graaff’s development of his method of generating high voltages by carrying charge to a terminal through charge sprayed on a continuous canvas belt is properly acknowledged, Van de Graaff’s early machines produced high voltages–and great pictures of lighting discharge and publicity–but not high energy beams. Hence those machines were not “accelerators” and were not useful in nuclear physics research.

The earliest application of the Van de Graaff potential generation mechanism to produce an accelerator was centered at the Department of Terrestrial Magnetism Laboratories in Washington where Tuve, Hafstad, and Dahl, Phys. Rev. 48, 315-337 (1935), describe their development of “electrostatic generators… used for the production of high energy protons and deuterons.” In that paper they reported that late in 1933 they succeeded in accelerating 20 microamp beams of protons to energies of over one MeV. In later papers they report using their electrostatic generator in important experiments bearing on the structure of protons and light nuclei.

Merle Tuve grew up in Canton, North Dakota, across the street from his best friend, Ernest Lawrence, both from Norwegian immigrant families (the name Lawrence was anglicized from Lavrens). Odd Dahl, physicist and arctic explorer, was Norwegian and returned to Norway a few years after the 1935 paper was published. Tuve was elected to the National Academy of Sciences in 1946.

The history of electrostatic accelerators continued with work by Ray Herb, elected to the National Academy of Sciences in 1955. Beginning in the late 1930s at Wisconsin, Herb’s machines produced highly controlled nearly mono-energetic proton beams up to energies of 4.5 MeV. The two generators which played an important role at Los Alamos during WWII were Herb’s machines brought from Wisconsin. As a graduate student and then junior faculty member at Wisconsin circa 1950 who worked with “the long tank”, a generator returned from Los Alamos, I recall, with amusement, that we always called the machine “the electrostatic generator”, never–bite-your-tongue–the Van de Graaff. And it was Ray Herb who developed in the 1960s the pelletron generators of which several hundred are in use today. The Pelletron potential generation mechanism is a kind of grandchild of Van de Graaff’s design where the high voltage is generated through the transfer of charge carried by belts of metal pellets connected with insulating nylon links.

So honor Van de Graaff! But honor Tuve, Herb, and others who contributed more to the development of the electrostatic generators that have played a central role in our understanding of the nucleus.

Robert K. Adair
Hamden, CT


It Pays to Keep Track of Units

The Back Page in the February APS News makes a hypothetical comparison as to which of two job candidates one would hire: what appears to be an American high school graduate at $17/hr and a more qualified foreign candidate eager to work for $1.50/hr. The comparison has little merit because the respective costs of living in the two candidates’ countries is not considered. Having only half the data makes the author’s conclusion suspect. The cost of living relative to the wage paid is an important consideration.

What the authors of the article, Rising Above the Gathering Storm, Revisited, are doing is to use only one coordinate system for comparison. There are two coordinate systems with different scales on their respective axes, one for the American candidate and one for the foreign candidate. When engineers do what the authors have done it causes space probes to crash into the planets upon which they were supposed to land softly. One cannot put the foreign candidate data on the American candidate’s coordinate system without scaling the numbers accordingly, and vice versa. Dimensional analysis used to be taught before we moved on to the “modern stuff”. Knowing what unit system one is working in has always had value until h = c = whatever = 1 came along.

Tom J. Gray
Corpus Christi, TX

Open Letter to APS President Barry Barish

In the January, 2011 issue of APS News, you responded to a question from the reporter as to what you considered the most pressing issue facing the physics community right now with the statement, “Research Funding.”

You and I have known each other for over fifty years, dating back to when we were both at the Lawrence Berkeley Laboratory conducting experimental research in elementary particle physics. I don’t believe that either of us would have given that response then and I still do not believe that your response would be appropriate today. It is one that I have heard repeatedly over the years, particularly by scientists who have moved into advisory and administrative responsibilities as they have aged. It misses the mark.

What would my response have been? Mine would have been, “Excellence of Ideas”.

As you know, just about 25 years after the establishment of the NSF, I spent eight years of my career there, between 1972 and 1980, as Program Director for Elementary Particle Physics. One of the very first things I learned was from the charter, which placed prime importance on the need for excellence when funding science. I adopted that belief early in my tenure and have held it ever since.

At the time, NSF was almost inconsequential in the funding of particle physics, and aside from supporting the operation of the 12 GeV electron synchrotron, the program was rather non-descript and only a tiny fraction the size of the Atomic Energy Commission’s.

The scientific community had a great deal of difficulty in accepting a meaningful role for the NSF in its support of outstanding science and not infrequently acted imprudently in judging the value of NSF proposals to achieving understanding in the field. Probably the most notable example of that attitude was the review, conducted by the Future Facilities Panel at Woods Hole, Massachusetts in 1974, of the Cornell CESR proposal to convert the synchrotron to an electron-positron collider.

I believe you were one of the panelists, and I am sure that you recall the Panel’s decision to recommend not funding that proposal under any funding scenario. Later, the Panel introduced a fourth scenario, labeled “Blue Skies” under which it supported the proposal.

The rationale for not supporting what was widely viewed by the panelists as an excellent proposal was that there wasn’t enough money to support two electron-positron colliders, (the other being PEP, the SLAC 15 GeV x 15 GeV collider). This was a phony argument; the real rationale was political.

The bottom line is that the NSF did provide support for CESR, which turned out to be the nation’s premier facility for a 30-year period when it essentially dominated publications on the properties of b quark states.

At that time, the NSF funded another proposal, from the University of Utah, called the Fly’s Eye, which relied upon observing fluorescence caused by high-energy cosmic rays interacting with nitrogen atoms of the earth’s atmosphere. That experiment evolved into Hi-Res and became a world-class effort of high renown.

These efforts did not require an infusion of lots of new money and were achieved at least in part via a redirection of program funds. When I informed a Nobel Prize winner that funding for his proposed program was scheduled to be reduced, I was told I was the worst program officer that he had ever encountered in all of his dealings with federal agencies. Others accused me of not being truthful in stating the proposal’s funding.

In closing, I would like to take issue with one of your other statements, “Probably the most urgent issue is for constituent scientists to make contact with the new members of Congress to talk to them about how valuable basic science is to the future of the country”. I feel this approach is being naive and further tends to promote the use of “pork” to get financial support in the form of “earmarks.” All too often, I have found those approaches to be counterproductive to getting the best research supported and to end up being wasteful and poorly designed and planned.

I think a debate on the funding of science may be long overdue. If you feel such an initiative might be appropriate, I would be willing to participate.

Sincerely yours,

Alexander Abashian
Ruckersville, VA

Barry Barish Responds:

I welcome Al Abashian's reaction to my question and answer interview published in the January 2011 APS News, but do not agree with a couple of his major points.

In particular, Abashian took issue with my calling “research funding” the most pressing issue facing the physics community, and he gives several examples (in hindsight) where more judicious choices could have been made, presumably replacing our need for increased funding. Of course, it goes without saying that we can always improve our priority setting. The peer review process we use serves us very well, but it is far from perfect. Nevertheless, even in Abashian’s own field of particle physics, the lack of U.S. research investment is resulting in the premier new facilities moving abroad, the LHC at CERN in Europe, two new B-factories in Japan and Italy, and the Tevatron at Fermilab being shut down despite significant discovery opportunities. In Astrophysics, despite dramatic discoveries of recent years and the highly regarded ASTRO2010 report, the highest priority future dark energy mission cannot be funded in the near future by NASA and DoE. We certainly don’t lack for good ideas, excellent projects or priority setting in the U.S. We do lack research support!

Abashian also disagrees with my plea that constituent scientists make contact with their new members of Congress. My point is a very simple one and has nothing to do with “pork” or “earmarks.” Our Congress has few scientists in its ranks, yet they make many decisions involving science and technology. Scientists must discuss these issues with them, if we are to have an informed Congress.

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Editor: Alan Chodos