Vol. 14, No. 2, July 2000 ACIPA Website: http://www.nscl.msu.edu/acipa/
AMERICAN CHAPTER OF THE INDIAN PHYSICS ASSOCIATION
NEWSLETTER
Editor: S.D. Mahanti
CONTENTS
Message from the President
Abhay Ashtekar, Pennsylvania State University
Announcements
S.D. Mahanti, Michigan State University
National Centre for Radio Astrophysics
Rajaram Nityananda, Centre Director, National Centre for Radio Astrophysics (NCRA)
P.O.Box 3, Ganeshkhind, PUNE 411007, INDIA rajaram@ncra.tifr.res.in
We Hear That ...
S.D. Mahanti, Michigan State University
LIST OF CURRENT OFFICE BEARERS
President: Abhay Ashtekar, Penn State University; ashtekar@cosmos.nirvana.phys.psu.edu
Executive Secretary: Alok Kumar, State University of New York, Oswego; kumar@oswego.edu
Editor: S.D. (Bhanu) Mahanti, Michigan State University; mahanti@pa.msu.edu
Treasurer: Sarada G. Rajeev, University of Rochester; rajeev@pas.rochester.edu
Webmaster: N. Anantaraman, Michigan State University; anantaraman@nscl.msu.edu
ADDRESS FOR CORRESPONDENCE
S. D. Mahanti, Department of Physics
Michigan State University
East Lansing, MI 48824
Phone: 517 355 9710; Fax: 517 353 4500
MESSAGE FROM THE PRESIDENT
Abhay Ashtekar
In the last (April 2000) newsletter, I had summarized our goals and plans for this year. I am now happy to report that the Executive Committee has continued to be very active and we are making good progress towards our goals. As you have probably noticed already, our website http://www.nscl.msu.edu/acipa/ has continued to grow with new pages and richer information. I wrote to the heads of some 25-30 academic institutions in India to enhance mutual interaction and most of them have responded enthusiastically. Several institutions now have a specific physicist assigned as a contact person with ACIPA who will keep us informed of the important scientific and administrative developments. Dr. Raman Anantaraman has kindly agreed to post this information on the web. Dr. Alok Kumar has aggressively pursued the educational initiatives in India and plans for workshops for College teachers in India are well under way.
The Chapter had an informal get-together during the APS April meeting in Long Breach, CA. Professor Rabindra Nath Mohapatra of the University of Maryland received the Distinguished Scientist Award and gave a stimulating review of his work on neutrino masses and the fundamental left-right symmetry in nature. During the meeting, there was an active exchange of ideas on plans that I had prepared in consultation with the Executive Committee. There was a strong support for the idea of instituting a new ACIPA award for a junior scientist. Some suggestions were made on raising funds and several of the leads are being currently pursued. There was also a long and highly productive session on nuclear non-proliferation, led by Professor Jeeva Anandan. It was heartening to see that Pakistani physicists also participated. This is very much in the spirit of ACIPA which serves physicists from the entire Indian subcontinent, living in North America. We very much hope to enhance this interaction. During the cold war, communication between scientists belonging to the two blocks was extremely helpful in the reduction of nuclear threat. Indian and Pakistani scientists could play a similar role now.
Several APS officials, including the President, Professor James Langer, and the Director of International Programs, Dr. Irving Lerch, participated in the session on nuclear issues and made valuable comments. Free scientific exchange is a high priority of the APS and they have been very active in fighting the sanctions imposed by the US government on scientific institutions in India and Pakistan. Dr. Lerch's office, in particular, has spearheaded efforts to help Indian scientists with visas for academic visits and conference participation in US. They know well the technical obstacles and ways of circumventing them. They can also advise scientists working in the US government laboratories who wish to visit academic institutions in India and encounter administrative difficulties from their own institutions here. Drs. Langer and Lerch will themselves visit several institutes in India in the Fall to enhance academic exchange between the two physics communities.
A group of physicists, presently numbering eleven, who have settled in India during the past decade after extended stays in the USA, have kindly agreed to be a contact group for persons in USA/Canada who are seriously exploring the possibility of returning to India to pursue a career in physics. The purpose of the contact group is to advice people about the general difficulties and good points about returning to India, based on their personal experience of doing research in both USA and India. The names and e-mail addresses of the contact group are posted at the ACIPA website. Any potential returnee who wishes to obtain advice should directly contact members of the contact group by email. The ACIPA has two requests: (a) that the potential returnee be considerate of the time the contact group is willing to spend in this cause; and (b) that, in order to increase the number in the contact group, we be informed of others who have returned to India for a physics career in the last decade.
I will close with two announcements related to students. First, please send Professor Alok Kumar, who is in charge of the educational initiatives, information on students of Indian origin who will receive their Ph.D.s this year, particularly a short description of their thesis work and the position they will assume after receiving their degree. Finally, I am very pleased to announce that, at the APS April 2000 meeting in Long Beach, Mr. Govind Krishnaswami of the University of Rochester received the prestigious Leroy Apker award of the APS for 1999 for his undergraduate work on hadronic structure functions. This work was done under the supervision of Professor S. Rajeev, the ACIPA treasurer, who continues to advise Mr. Krishnaswami for his Ph.D. work. Our hearty congratulations to both!
ANNOUNCEMENTS
S. D. Mahanti
We are sad to announce the untimely deaths of two well-known physicists. Professor Chanchal K Majumdar, the ex-Director of S.N. Bose Center for Basic Sciences, Calcutta passed away on June 20, 2000. We are publishing an obituary written by Professor Sushanta Dattagupta, the current Director of the Centre, in this issue. Professor Nimai Chand Mukhopadhyay of Rensselaer Polytechnic Institute, Troy, New York passed away on May 15, 2000. Professor Mukhopadhyay completed his B.Sc. from Ramakrishna Mission College, Narendrapur, West Bengal in 1963, and M.Sc. from Calcutta University in 1965. He then joined University of Chicago as a graduate student and completed his Ph.D. on a theoretical study of muonic atoms in 1972. He was among the first batch of physicists to become a Life Member of the ACIPA. He was attached to various social and philanthropic activities of the R. K. Mission and provided continuous funding for the education of a few poor students at the Narendrapur school and college.
In the 31st International Physics Olympiad (IPhO-2000), which was held in Leicester, UK in July 2000, the Indian team secured two gold medals, two bronze medals, and one honorable mention. Their unofficial overall position was third behind China and Russia.
The current issue presents an article on the National Centre for Radio Astrophysics at Pune by Dr. Rajaram Nityananda, the Director of the Centre.
We end by mentioning three crucial points.
NATIONAL CENTRE FOR RADIO ASTROPHYSICS
Rajaram Nityananda
The National Center for Radio Astrophysics (NCRA) at Pune was set up in 1992 largely to build, exploit, and run the Giant Metrewave Radio Telescope (GMRT) which is located at Khodad, about 80 km north of Pune. The GMRT has the largest collecting area of any array-type (synthesis) radio telescope in the world operating at metre wavelengths. Full utilization will need a large number of national and international users, which is expected because of its unique observational capabilities. The group at NCRA also pursues radio astronomical research with international facilities and its own telescope in Ootacamund (Ooty) in southern India, the main areas of interest being cosmology, normal and active galaxies, interstellar and interplanetary gas and plasma, and pulsars. There are about twenty academic members including students, around thirty scientific staff and a somewhat larger number of supporting technical staff.
Figure 1
One of the thirty 45 m diameter GMRT antennas. Note the almost transparent mesh which makes the structure light and reduces wind load, while preserving full reflectivity at metre wavelengths.
Historically, NCRA emerged from the radio astronomy group set up by the Tata Institute of Fundamental Research (TIFR) at Mumbai under the leadership of Prof. Govind Swarup, who returned to India after working in the field at Stanford University and other places. The group built a radio telescope at Kalyan near Mumbai, used between 1965 and 1968 for studying radio emission from the sun. The group then moved to Ooty, in the Nilgiri mountain range in Tamil Nadu and undertook the construction of a very novel radio telescope. The telescope was a parabolic cylinder 530m long and 30m broad and was built on a carefully chosen hill whose slope was such that the long axis of the telescope was parallel to the axis of rotation of the earth. This meant that the telescope could track a celestial source by uniform rotation along a single axis. The Ooty Radio Telescope (ORT), which operated at 325 MHz (90cm), was mainly intended to exploit the technique of lunar occultation to study active galaxies, which are strong emitters of radio waves. These galaxies are such bright radio sources that one can detect them out to cosmological distances. To obtain an angular resolution of two arc seconds (needed for such studies), at this wavelength one would normally need a telescope a hundred kilometers in size. But by studying the diffraction pattern produced by a source when it is covered or uncovered by the edge of the moon one could obtain information on the structure of the source on angular scales as small as two arc seconds. The ORT came into operation in the early seventies, and for more than a decade from then it produced a substantial body of work on the fine structure of radio galaxies. These studies played a key role in establishing the strong evolution of the physical properties of radio galaxies with cosmic epoch. In addition to lunar occultation studies, the large effective area (of around eight thousand square meters) made the ORT useful in the study of pulsars, interplanetary scintillation, and line radiation.
In the mid and late eighties, the group started working on the GMRT. Most of the group moved to Pune by the early nineties to work on this project. The GMRT is an aperture synthesis telescope, i.e. it achieves high angular resolution by sparsely distributing its antennas over a large geographical area, which defines the equivalent single antenna for purposes of angular resolution. The GMRT has 30 antennas each 45m in diameter, which are spread over an area about 25km across. For comparison, the Very Large Array (VLA) in New Mexico (USA), commissioned in 1980 consists of 27 antennas each 25m in diameter. The VLA operates primarily at wavelengths of 21 cm and shorter; 21cm is of course the wavelength of the hydrogen ground state hyperfine transition at 1420 MHz. Since hydrogen is by far the most abundant element in the universe, the 21cm line is an obvious astronomical probe. The GMRT operates primarily at wavelengths of 21 cm and longer.
The emphasis on longer wavelengths makes the GMRT complementary to the existing major facilities in the world. The very large collecting area of the telescope makes the GMRT ideal for studies of redshifted neutral hydrogen, i.e. gas whose emission/absorption is received at longer wavelengths than 21cm because of the expansion of the universe during the journey between the hydrogen gas cloud and us. For example, hydrogen radiation emitted when the universe was four and half times smaller than now (and only about ten per cent of its present age) would be received by us at a wavelength of 90cm. According to our current understanding, the formation of galaxies and other large scale structures occurred about this time, i.e. when the universe was 10% of its current age.
Optimizing the telescope performance at meter wavelengths allowed the use of a wire mesh as a reflector. This greatly reduces the dead and wind load. A novel telescope design, which takes advantage of this low load on the support structure, was employed resulting in a significant reduction in the cost without compromise on the performance at meter wavelengths. The final cost was approximately fifteen million dollars for the thirty large antennas and all associated electronics and infrastructure. The experience with the ORT had created a body of people familiar with both the astronomy which could be done at these long wavelengths and the technologies needed to construct such an instrument. However, there were many things which were being done for the first time in the country, and this undoubtedly contributed to the long time it has taken to bring the GMRT to its present status.
Currently, the GMRT is operational in one 16 MHz sideband and astronomical observations at 21-30 cm, 49 cm, and at 90 cm have been carried out for almost a year now, with typically twenty or more antennas giving data at any one time. There are ongoing efforts to bring in the second sideband, to include the 2 meter band, and to increase uptime and reliability. Extensive study and control of systematics to go towards the sensitivity limit set by collecting area and receiver noise is a major priority. This last task becomes more complicated as one goes to longer wavelengths due to the earth’s ionosphere (right now under the malevolent influence of the solar maximum) and man-made radio frequency interference (RFI). Not surprisingly, therefore, this process has been more rapid at the shorter wavelength bands. Current astronomical observations usually involve a member of the group or an experienced user. It is expected that more general use, with a significant international component, will commence in 2001.
Radio astronomy is increasingly becoming one part of a multiwavelength view of the universe, and astronomers have therefore moved to extensive collaborations and the use of international facilities. The work at NCRA also reflects this trend. As envisaged, India will not only be a country which exploits astronomical facilities elsewhere but also offers a unique, albeit specialized facility to radio astronomers everywhere. Setting up the instrument has been a major preoccupation of NCRA and its operation, maintenance and improvement will naturally be as well. But NCRA is also a group addressing a range of problems relating to galaxy formation, pulsars, interstellar gas and magnetic fields, and many other areas, using the GMRT and other facilities. The astronomy and the instrument call for people with a wide range of skills ranging over basic physics, astronomy, electromagnetics, signal and image processing, state of the art analogue and digital electronics, and large scale special and general purpose computation. Accordingly, NCRA offers a wide range of opportunities on different timescales- short term projects for students of science and engineering and other visitors, predoctoral and postdoctoral fellowships, and of course the possibility of entry as faculty for those who are already established in research and have overlapping interests. We strongly hope that the next generation will find NCRA's special combination of astronomy, physics, engineering, and computation as appealing as the current one. More details can be found at our web page www.ncra.tifr.res.in
Figure 2
An image of the supernova remnant W44 made with the GMRT at a wavelength of 90 cm. The material from the exploding star has interacted with the interstellar gas and magnetic field to produce the radio emission. Image courtesy S.Bhatnagar, pre-publicaton.
CHANCHAL KUMAR MAJUMDAR (1938-2000) — AN OBITUARY
Sushanta Dattagupta
Chanchal Kumar Majumdar, an exceptionally gifted condensed matter physicist, passed away in Calcutta on 20 June 2000. His death was so unexpected that it came as a rude shock to the scientific community.
Majumdar had a brilliant academic record in Krishnanagar and Calcutta. Subsequently he obtained his doctoral degree in physics from University of California, La Jolla (now San Diego) in 1965 under the supervision of Walter Kohn who went on to win the Nobel prize in Chemistry in the nineties. With Kohn, he proved a theorem (the Kohn-Majumdar theorem) on the continuity of the bound and unbound states of the Fermi gas. From 1965 to 1966, Majumdar held a post-doctoral position in Carnegie Institute of Technology (now called Carnegie-Mellon University), Pittsburgh before joining the Tata Institute of Fundamental Research (TIFR) in Mumbai. From TIFR, he had another post-doctoral stint in the University of Manchester. In Pittsburgh and Manchester, Majumdar came in contact with stalwarts like James S. Langer and Sam F. Edwards, though he chose to work independently on the analytic properties of the Onsager solution of the Ising model and non-exponential stress relaxation in glass.
TIFR days were the most productive for Majumdar. He had a group of several bright students and with them he tackled a variety of problems with deep mathematical insight. They include magnon bound state equation, Heisenberg antiferromagnetic chain with known ground state, the critical isotherm of the Ising model and of the Lennard—Jones gas, the band structure of cerium, spin waves in finite magnetic chains, etc. It is interesting to note that during those days in India, what we know now as condensed matter physics was dominated by lattice dynamics. Majumdar was a rare exception amongst his peers. He was well-versed in then-current subjects of statistical mechanics and critical point phenomena, and their applications to electron states and magnetic properties of solids.
Perhaps the most important contribution of Majumdar, for which he is internationally known, is the work (with Dipan Ghosh in 1969) on the exact enumeration of the ground state of an anti-ferromagnetic chain, with specially ascribed values for nearest and next nearest neighbor interactions. This work on what is now part of the folklore as Majumdar-Ghosh Hamiltonian is a wonderful illustration, as it were, of how open-ended basic research can be. Almost two decades later the model led to a prototype "resonating valence bond" state, in the context of high temperature superconductivity. One other point is noteworthy here. The years 1965 to 1975 had not yet seen the growth of computational physics as is extant in India today; Majumdar indeed was a pioneer computational physicist in our country. In 1976, he was awarded the Shanti Swarup Bhatnagar prize in Physical Sciences, an in the same year was elected Fellow of the Indian Academy of Sciences.
The decade from 1976 to 1986 marked a new phase in Majumdar’s life. As Palit Professor of Physics in Science College of Calcutta University and Head of Magnetism/Solid State Physics Department of Indian Association for the Cultivation of Sciences (IACS), he devoted himself to education, teaching, and curriculum development. In addition, he switched interest to down-to-earth experimental studies, applying his early work (1965-1970) in the theory of positron annihilation spectroscopy to radiation damage, and also involving Mossbauer spectroscopy of corrosion and inhibition of iron ores in eastern India. His other experimental contribution included the enhancement of the critical temperature of high temperature superconductor due to alpha particle bombardment. Many of these experiments were carried out by Majumdar’s collaborators and students at the Palit Laboratory, IACS and Variable Energy Cyclotron Centre. He was elected to the Fellowship of Indian National Science Academy (INSA) in 1982.
The final phase (1987-1999) of Majumdar’s professional life began when he was appointed the Founder Director of the newly established Satyendranath Bose National Centre for Basic Sciences. This period saw him in the role of an institution-builder. He devoted himself tirelessly to the development of infrastructure facilities of the new center. He also lent active support to various workshops, seminars and conferences organized in the center by different national bodies as well as teachers’ training programmes.
Chanchal Kumar Majumdar was a versatile individual. An evidence of his enigmatic dexterity is the project he undertook in 1992 on the simulation of fluid flow on the Hoogly Estuary by parallel programming. The word "Chanchal" in Bengali means restless. He no doubt had a restless mind. After retiring as Director of the Bose Centre in February 1999, he took up the position of an INSA Senior Scientist at the Indian Statistical Institute from March 1999 and started working on "History of Science". Majumdar’s sudden death has snatched away at an early age a truly extraordinary personality.
WE HEAR THAT ...
S.D. Mahanti
Professor Sajeev John, of the University of Toronto, has received a Guggenheim Fellowship this year. The fellowship will allow him to study Photonic band-gap materials.
Dr. V. C. Sahni is the new Director of the Physics Group at Bhaba Atomic Research Centre (BARC), Mumbai. A condensed matter theorist with a strong interest in superconductivity experiments, Dr. Sahni was previously the Head of the Technical Physics and Prototype Engineering Division at BARC.
INFORMATION SHEET
Please print out this form, fill it, and return it along with your Annual Membership fee of US $ 15 (students $10) for the calendar year 2000 or of US $ 150.00 for Life Membership. We strongly encourage our members to become Life Members. The payment should be made in the form of a personal check payable to "American Chapter of the IPA" and mailed to Dr. Sarada Rajeev, Department of Physics and Astronomy, University of Rochester, Rochester, New York, 14627-0171. If you wish to support our Scholarship Fund for physics undergraduates in India, please include your contribution in your check. Canadian members are requested to send the subscription in the form of a money order, bank draft, or personal check involving US funds.
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