Dilip Kumar Das-Gupta

Dilip Kumar Das-Gupta, an eminent applied physicist in the field of dielectric materials, died on 5 January 2002 in Bangor, Wales, following a brief illness.Das-Gupta was born on 16 September 1928 in Barisal, India. In 1949, he graduated from the University of Calcutta with a first-class honors BSc degree in physics. That same year, he obtained an MSc degree in radio physics from the university and then subsequently emigrated to England, where he worked as an electronics engineer, research engineer, and deputy chief instrumentation engineer for industrial companies in Cambridge and London until 1960.From 1955 to 1960, in parallel with his job in industry, Das-Gupta pursued research at the University of London’s Birkbeck College, where he earned his PhD in nuclear physics in 1962. From 1960 until 1965, he was a full-time research fellow in Birkbeck’s physics department and worked on an absolute determination of internal-conversion electron energies of thorium B (lead-212).In 1965, Das-Gupta was appointed lecturer at the school of electronic engineering science of the University College of North Wales in Bangor (UCNW). There, he immediately started research on the dynamics and heat transfer in fluidized beds (freely supported solid particles in a fluid). During the 1970s, he began research on the physics of dielectric polymers. Within a few years, he became a leading expert on charge trapping and conduction in insulating polymers and on piezo- and pyroelectric polymers—a new field that had begun only a few years before. In a seminal 1977 paper in Applied Physics Letters, he reported changes in the x-ray diffraction patterns of polyvinylidene fluoride caused by corona charging. This work led to the discovery of a new electric-field–induced crystalline phase of this semicrystalline ferroelectric polymer. The findings, as well as his systematic use of corona poling and structure analysis, resulted in seminal publications on the link between the morphology and the ferro-, pyro-, and piezoelectricity of polyvinylidene fluoride and its copolymers. Starting in 1979, Das-Gupta engaged in a series of highly successful research visits to several foreign laboratories. He became a consultant to the department of electrical engineering at the University of Southern California in Los Angeles, where he worked on conduction mechanisms in insulating polymers. During the decades that followed, he collaborated closely with colleagues in Australia, Brazil, Canada, China, Germany, Greece, Hong Kong, Israel, Italy, Portugal, Russia, Spain, and the US. In his collaboration with colleagues from industry, independent laboratories, and universities, and in his own work, Das-Gupta—a true applied physicist—maintained a good balance between the fundamental and engineering aspects of research and technology.In 1982, Das-Gupta was promoted to reader at UCNW. During 1980, together with one of us (Lang), he introduced the laser intensity modulation method (LIMM), a nondestructive pyroelectric technique for probing space-charge and dipole-polarization distributions in dielectric films. Several laboratories around the world now use this low-cost, high-resolution technique. Das-Gupta continued to refine the LIMM, in particular through careful direct comparisons with related experimental methods.Das-Gupta’s outstanding scientific achievements were acknowledged through many honors. In 1989, he was elected as a fellow of both the UK’s Institution of Electrical Engineers and Institute of Physics. In 1994, he was elected a fellow of the Institute of Electrical and Electronics Engineers. Das-Gupta formally retired in 1993, but was subsequently appointed honorary research fellow by UCNW (now called the University of Wales in Bangor). He continued and even increased his very fruitful research—in particular, his dedicated work with young talented scientists from all over the world. During the 1990s, he became one of the leading experts on polymer-ceramic composites and contributed often-quoted review articles to journals and books. His advanced materials characterization group at the university’s school of informatics continues to study materials for high-energy storage, smart ferroelectric-polymer composite sensors, electrical and dielectric properties of chemically treated polymers, dielectric spectroscopy of polymers and ceramic-polymer composites, and AC-field aging of power cables in humid environments. Das-Gupta’s unexpected death left much of this promising research only partly completed.Das-Gupta consistently supported and encouraged students and young colleagues. For many years, he was involved in a European Socrates/ Erasmus network and hosted, in his laboratory, students from all over Europe. His deep understanding of philosophy and culture and his sensitivity for others’ feelings and thoughts were as important as his scientific excellence in making him a very successful teacher and promoter of students and scientists worldwide. Many of the students later had the privilege to become his friends and colleagues. Many of them will continue to promote science in research and teaching in his style, and will remember his generous and open personality with fondness.Das-Gupta had the rare gift of combining scientific excellence and exactness with personal warmth, deep understanding, and a wonderful sense of humor. We all miss him and offer our sympathy to his family. Dilip Kumar Das-gupta PPT|High resolution© 2002 American Institute of Physics.

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