In 1977, when I joined the Tata Institute of Fundamental Research (TIFR), Prof. Rajasekaran had already moved from TIFR to Madras University. My initial research project involved constructing a specialized experiment at Kolar Gold Fields (KGF) to further investigate some peculiar events known as "Kolar Events." These events, previously detected during the late 1960s neutrino experiments at KGF, seemed to involve long-lived massive particles decaying in the air. To comprehend the possible theoretical interpretation of these events, my thesis advisor, Prof. V. S. Narasimham, suggested that I study a paper by Prof. G. Rajasekaran and Prof. K. V. L. Sarma, who had proposed an explanation for the Kolar Events. This was the first scientific paper that I read with great interest.
However, as my focus soon shifted to the establishment of the Proton Decay Experiment, I could not complete the investigation of Prof. Rajasekaran's interpretation of the Kolar Events. On the contrary, my interaction with Prof. Rajasekaran began to grow as Mumbai University appointed him the examiner for my thesis. To conduct my thesis viva, Prof. Rajasekaran decided to evaluate me at the KGF Proton Decay experimental site, located 2.3 kilometers underground. This unconventional setting probably made me the first Ph.D. student in the world to defend his thesis at such depth. On the flip side, the University of Mumbai's thesis cell faced difficulties in determining the travel allowance and remuneration for a thesis examiner conducting an examination underground. So, he became the only thesis examiner who never received any remuneration for conducting a thesis viva.
Prof. Rajasekaran was a theoretical physicist, and undoubtedly, his colleagues in the field will extensively discuss his contributions to theoretical physics, particularly in particle physics theory. However, what I would like to highlight is his unwavering conviction regarding the necessity of establishing experimental science projects in India. He firmly believed that Indian science could not progress without the implementation of large-scale experimental facilities. While those of us involved in the KGF Proton Decay experiments almost lost hope for the advancement of our field in India, Prof. Rajasekaran kept the flame of optimism alive. He organized numerous meetings to emphasize the requirement for a significant experimental facility dedicated to particle physics research in India. Under his guidance, the idea for the India-based Neutrino Observatory (INO) facility took shape during the 2001 WHEPP Workshop held at the Institute of Mathematical Sciences (IMSc). Eventually, the focus settled on the ICAL experiment.
Over the next twenty years, I collaborated closely with Prof. Rajasekaran on all aspects of the INO project. This involved selecting suitable sites, encouraging universities and IITs to participate in INO's research and development activities, establishing INO Graduate Schools, and tirelessly seeking support from science administrators, politicians, and even activists. We endeavored to convince everyone about the significance of INO for the scientific growth of India. Prof. Rajasekaran led us all from the front, displaying a profound passion for the cause. At the INO collaboration meetings, he could be found engaging most with the younger generation of students and post-doctoral researchers. During outreach programs, he discussed neutrinos with the general public with the same enthusiasm as he did with his colleagues and collaborators.
I must emphasize that this period marked the most thrilling phase of my entire academic career—working closely with Prof. Rajasekaran on the INO project. Together, we experienced the joy of making progress while facing the challenges head-on. His relentless dedication to experimental physics and his ability to inspire others have left an indelible mark on the field in India. Prof. Rajasekaran's legacy will endure as a catalyst for scientific exploration and he will be remembered as a champion of experimental science in the country.
A profound homage to the indomitable spirit of Prof. G. Rajasekaran would be to ardently dedicate ourselves to the realization of the India-based neutrino observatory project—a vision he has tirelessly pursued over the years.
Prof. Rajasekaran handing over the INO project report to Dr. Anil Kakodkar, then Chairman AEC and Secretary DAE.
Prof. G. Rajasekaran visiting one of the possible INO sites for close inspection
Prof. G. Rajasekaran and his colleagues discussing INO project with former president of India Dr. A. P. J. Kalam
Advising on intricacies of life to a colleague who is turning 60.