Blewett, John Paul, 1910-2000.
nuclear physicist and
particle accelerator designerJohn Paul Blewett, 89, Physicist And Designer of Accelerators
By WOLFGANG SAXON
New York TimesJohn Paul Blewett, a nuclear physicist who played a significant role in the development of particle accelerators, died at a hospital in Chapel Hill, N.C., on April 7. He was 89. A Chapel Hill resident, he had lived in Manhattan and New Suffolk, N.Y.
Dr. Blewett retired in 1978 as a senior physicist at the Brookhaven National Laboratory on Long Island, which he joined in 1947 to take part in building its proton synchrotron. Known as the Cosmotron, it went into operation in 1952 and was the world's most powerful energy accelerator.
Dr. Blewett then began the design study for the 33-billion electron volt Alternating Gradient Synchrotron, operating since 1960. Later he directed design studies for improving it, and toward the development of more powerful accelerators. He was a consultant on accelerator technology to the French Atomic Energy Commission and CERN, the European particle physics laboratory. After retiring from Brookhaven, he was an adviser on a synchrotron light source to the government of Taiwan.
Dr. Blewett was born in Toronto. He received a degree in physics and mathematics from the University of Toronto in 1932, and a master's in physics in 1933. In 1936 he received a Ph.D. in physics at Princeton.
He joined the research laboratory of the General Electric Company in Schenectady, N.Y., in 1937. There he made the first direct observation of synchrotron radiation -- the electromagnetic radiation given off when high-energy particles are accelerated in a strong magnetic field -- and its experimental verification in 1945.
He was a fellow of the American Physical Society, which awarded him its Robert R. Wilson Prize in 1993.
Survivors include his wife, Joan Warnow-Blewett; two stepdaughters, Dr. Tandy Warnow of Austin, Tex., and Dr. Kimmen Sjolander of Lafayette, Calif.; a stepson, Paul Warnow of San Francisco; and a sister, Constance Blewett of Toronto.
John Paul Blewett, a key figure in the development of particle accelerators, died of acute pancreatitis in Chapel Hill, North Carolina, on 7 April 2000.
Blewett was born in Toronto on 12 April 1910. He earned his bachelor's (1932) and master's (1933) degrees in physics at the University of Toronto and his PhD in physics from Princeton University in 1936. After receiving his doctorate, he spent a year at the Cavendish Laboratory in Cambridge, England, working under Ernest Rutherford, Mark Oliphant, and others on range-energy relations for alpha particles, among other projects.
From 1937 to 1946, Blewett worked in the research laboratory of the General Electric Co in Schenectady, New York. During that period, Donald Kerst built a 20-MeV betatron at GE in 1941, and, in 1945, Ernest Charlton and William Westendorp built a record-breaking 100-MeV betatron at GE, achieving by far the highest particle energy in the world. About the same time, Blewett came across a paper by Russian physicists Dimitri Iwanenko and Isaak Ya. Pomeranchuk, in which they pointed out that high-energy electron beams circulating in a betatron would lose some energy by radiation. After performing some calculations, Blewett concluded that the radiation would indeed be significant and would make it difficult to build machines for higher energy. He predicted that the radiation would cause the orbit of the new betatron to shrink--and indeed it was found to shrink by precisely the amount Blewett had calculated. This was the first observation of what is now known as synchrotron radiation.
Next, following a visit by Edwin McMillan from the Radiation Laboratory at the University of California, Berkeley, in 1945, Blewett and colleagues decided to use McMillan's new synchrotron idea to build what they hoped would be the first operating synchrotron--a 70-MeV machine--before McMillan himself could finish his 300-MeV synchrotron. Blewett and colleagues' synchrotron was finished by 1947; however, the honor of being the first to demonstrate the principle had gone to Frank Goward and D. E. Barnes in England, who had converted a small betatron to synchrotron operation. The new machine, unlike the 100-MeV betatron, had a transparent vacuum chamber, and the radiation turned out to be visible.
Blewett missed the first visual observation of the synchrotron in 1947 because he had left GE. He and Hildred Blewett, an accelerator physicist who was his wife at the time, joined the new Brookhaven National Laboratory on Long Island. Unfortunately, when they arrived at BNL, the security authorities of the US Atomic Energy Commission barred them from going to work. Apparently, a friend of Blewett's from earlier days had been arrested in Canada and charged with transmitting secret information to the USSR (a charge that was later dismissed). That association made Blewett and Hildred "security risks," and they had to cool their heels for six months before obtaining the necessary clearance to join the BNL staff.
Blewett's first major project at BNL was to participate in the design and construction of a new particle accelerator that aimed to extend the energy of available accelerated particles not just incrementally, but by a leap of an order of magnitude to 3 GeV (three billion electron volts). This proton synchrotron was called the Cosmotron because it got into the energy range of cosmic rays. Blewett took charge of the design and construction of the magnet and the radio-frequency accelerating system. He devised the structure of the Cosmotron's relatively compact C-section magnet. A major problem with the acceleration system was that, with a reasonable injection energy, the frequency would have to increase by a factor of 10 during the acceleration cycle, a range much larger than could be easily handled by devices such as mechanically-varying capacitors. Blewett decided to use ferrite--then a new material--in the accelerating cavities; this was a far more elegant and efficient solution to the modulation problem.
In 1952, the Cosmotron came into operation as the world's first billion-volt machine. A group of BNL physicists, with Blewett at the forefront, then came up with the alternating-gradient or "strong-focusing" method, which promised to make it possible for accelerators to go up at least into the 30-GeV range. Blewett saw that this technique would also solve a serious dilemma in the design of proton linear accelerators, in which the acceleration process was inherently defocusing, and focusing had previously been achieved only by the inelegant method of having grids intrude into the aperture, inevitably killing a large part of the beam while it was being accelerated. Replacing the grids with quadrupoles was a huge improvement.
When the new European high-energy physics laboratory, CERN, was proposed in 1952, a group of physicists from several European countries visited BNL and inquired about the possibility of building a machine like the Cosmotron, only a bit bigger. Learning of the ideas that had just come up at BNL, the European physicists decided to build a strong-focusing synchrotron of 25-30 GeV in Europe. This group invited Blewett and Hildred to join them to help with the new laboratory. Because CERN was split among working groups in several European locations, pending a move to Geneva where the lab was to be established, Blewett and Hildred went to Bergen, Norway, to join in the effort to create CERN's centerpiece: the proton synchrotron. They contributed to the initial design and pushed to have everything moved to Geneva, where construction for the lab began at the end of 1953.
At BNL in early 1954, the Alternating Gradient Synchrotron was approved for construction. Ken Green was in charge and Blewett was the deputy. In 1960, a 33-GeV proton beam was attained, setting yet another world record for energy. This achievement was the impetus for a study on how far one could go toward even higher energies. Blewett and Luke Yuan joined in an intensive study of the possibilities of proton synchrotrons up to 1000 GeV. That study led to the proposal for ISABELLE, a proton collider of 200-400 GeV at BNL, which was started, then abandoned, and finally reincarnated in the form of the Relativistic Heavy Ion Collider.
In 1962, Blewett, together with Stanley Livingston of MIT, published Particle Accelerators (McGraw-Hill, 1962), which summarized the development in the field up to that time. In 1970, Blewett founded the journal Particle Accelerators, for which he was the first editor.
Blewett continued as deputy chairman of the accelerator department until 1973. He then worked as a special assistant to the director until 1978, when he retired. During his "retirement," he returned to an early interest--synchrotron radiation. He took part in initiating the proposal to build the National Synchrotron Light Source at BNL, the first machine built explicitly for the purpose of producing synchrotron radiation as a tool for studies in condensed matter physics, chemistry, biology, and engineering. He also was a consultant to the Synchrotron Radiation Research Center in Taiwan. In 1993, Blewett was awarded the Robert R. Wilson Prize by the American Physical Society.
Blewett enjoyed sailing and gardening with his second wife of 17 years, Joan Warnow-Blewett, who recently retired as the associate director of the History Center at the American Institute of Physics.
Ernest D. Courant
Brookhaven National Laboratory
Upton, New York
Blewett Had Help With GE Synchrotron
Ernest Courant's obituary of John Paul Blewett (Physics Today, February 2001, page 76) erroneously credits Blewett with initiating the project at the General Electric Research Laboratory to construct a 70-MeV synchrotron. As I recall after over a half-century, Blewett's work while he was at GE was mainly with radar equipment, although he was an interested observer of the accelerator work and did help with the synchrotron orbit calculations. The project was initiated and directed by Herbert C. Pollock, who, with that accelerator, first actually observed "white" synchrotron radiation and measured its spectrum.1,2 The choice of 70 MeV was based on the availability of a suitable magnet, one that had been developed by Willem Westendorp for a 50-MeV biased betatron.
As an active witness of those events, I provided the data interpreted by Blewett as evidence that the 100-MeV betatron orbit was contracting due to radiation loss3 (there was another plausible interpretation) and, on the occasion of Pollock's visual observation, suggested that the light from the synchrotron beam might be polarized. Confirmation of the suggestion proved that Blewett's interpretation of the betatron's orbit contraction was correct (see "The Discovery of Synchrotron Radiation," Physics Today, January 1975, page 9*). That took place after Blewett had left the company.
It is unfortunate that both Blewett and Pollock (also recently deceased) were never appropriately honored for their discovery of synchrotron radiation, which has made so much basic and applied science possible.
I appreciate the helpful comments Courant offered on my letter.
References
1. H. C. Pollock, Amer. J. Phys. 51 (3), 278 (1983).
2. F. R. Elder, R. V. Langmuir, A. M. Gurewitsch, H. C. Pollock, Phys. Rev. 71, 827 (1947).
3. J. P. Blewett, Phys. Rev. 69, 87 (1946).Physics Today References
January 1975, page 9George C. Baldwin
(baldwingeorgec@qwest.com)
Santa Fe, New Mexico
John P. Blewett
(1910-2000)
Long time IEEE Member and Fellow (A’43, M’55, SM’56, F’64, LF’78) John Blewett died on April 7, 2000, just a few days before his 90th birthday. Over his lifetime, Dr. Blewett made many outstanding contributions to Particle Accelerator Physics and Technology and was a true pioneer of the field. He was an active IEEE member serving a term as an elected member of the IEEE-NPSS ADCOM and was awarded the Centennial and Millennium medals.Major revolutionary contributions were:
In 1945 he predicted and in 1947 observed synchrotron radiation from a circularly confined electron beam.
He first applied Alternating Gradient Focusing to Linear Accelerators thereby achieving immense increases in beam intensity.
He was a significant player in the building of the first alternating gradient synchrotrons, both the AGS at Brookhaven and the PS at CERN.
Among many other contributions were those to the development of split-anode magnetrons, microwave systems and low energy betatrons and synchrotrons.
John obtained his MA in physics form the University of Toronto and his PhD from Princeton University. He spent a year in the Cavendish Laboratory under Lord Rutherford. The General Electric Company then employed him for the next 10 years. It was at G.E. that his synchrotron radiation work took place and establishes him as one of the founders of synchrotron light sources. He then moved to Brookhaven National Laboratory for the remainder of his career. It was there that he made most of his major contributions to the rapidly burgeoning field of high-energy accelerators both circular and linear and storage rings.
He coauthored, with M. Stanley Livingston, one of the first comprehensive text books on the theory and technology of particle accelerators and was the founding editor of the periodical publication “Particle Accelerators” (G&B publishers). As a sought after consultant and advisor, his influence was significant in many existing accelerators and synchrotron light sources. In 1976 he received the IEEE-NPSS Merit award and in 1993 he was awarded the Robert R. Wilson prize of the American Physical Society. In addition to his IEEE Fellowship, he was a Fellow of the APS and the AAAS.
Those of us who were privileged to know John found him to be a very warm and engaging person.
This rememberance of John Blewett was prepared by Matt Allen at SLAC, 2575 Sand Hill Road, Mail Stop 24, Menlo Park, CA 94025; Phone: +1 650-926-2820; Fax: +1 650 926- 8657; E-mail: matallen@slac.stanford.edu
