My Scientific Journey

People ask me about my specialization as Physicist.  I believe that Physics is the mother of all sciences, therefore I never limited myself to Physics only.  I applied the concepts of physics to learn many other subjects.  During the development of Yog Science, I studied Neuroscience, Physiology, Molecular Cell Biology and Psychology.  I believe that if a person can understand the concepts of Physics, he is capable to understand all the subjects.  While studying particle Physics and Quantum Electrodynamics in Delhi University I wanted to become a theoretical Physicist and I was fascinated by wave-particle duality.  I realized by that time that Physics is about the behavior of matter and it is not about the nature of matter, therefore, I wanted to pursue research in this field.

My seconbd favourite subject is Electronics but I never thought for a carrier in Electronics and it was my hobby.  My father was a technician of Milk Pasteurisation Plant and he used to repair circuit boards of the plants.  So there were many electronic components available to me such as relays, coies, super enameled of copper wires.  Therefore, I got an opportunity of making small projects for science exhibition of school at the age of 13.  after joining Bhabha Atomic Research Centre (BARC), I worked in the field of Mossbauer Spectroscopy.  In the year 1977 it was a relatively new field of research and commercial set up for Mossbauer spectroscopy was not available.  I got the opportunity to improve a crude setup, that was already working.  The data acquition process was very slow and it used to take weeks to collect sizeable amount of data before the analysis could be possible.  I utilized the spare time to develop a microprocessor- based data acquisition system for this set-up. 

Then I participated in a project of developing a model of magnetically levitated train with a traction by linear motor.  In this motor one component of magnetic force was for levitation and another for the traction.  I developed the control system for powering the electromagnets by sensing the position of magnets.  A joint paper on this work was published in IEEE, control and instrumentation.  Later I used the idea of switching of linear array of electromagnets to develop a circular motor.  This was perhaps the first brushless DC motor driven by a power control circuit.  This was my expertise in Electrical Engineering.

After completing this project, I was associated in the field of Gamma Ray Astronomy.  A burst of Gamma rays from outer space falls on entire earth and it generates visible light by interaction with atmosphere.  In order to detect the light emitted by Gamma ray burst at least three photomultiplier tube are installed in three far off countries.  If a light pulse is detected simultaneously at three stations then it is identified as a Gamma ray pulse.  The clock of the station was manually synchronized by a common time signal broadcast by a radio station.  (The atomic clocks, that is used to send time data on mobile network were not available at that time).  The manual synchronization introduced an error of a fraction of a second in the clock of the station.  I developed a circuit to synchronise the clock automatically with an error of a millisecond.  I also completed a theoretical work in this field that eliminated the need for three stations.  I calculated a profile of light pulse received at the photomultiplier tube.  I divided the sky into infinitesimally thin annular rings whose radius increase continuously.  The intensity of light started at the centre just above the photomultiplier was maximum and intensity decreases as we move to outer annular rings.  In this way I calculated the exact shape of light pulse produced by Gamma ray burst.  The photomultiplier is a very sensitive device which detects all sort of light pulses generated in sky such as one generated by the trail of a meter.  But the light pulse generated by Gamma ray can be identified by its specific shape calculated by me.

In 1987 I came to RRCAT (then CAT) to work on a project, Indus-I which is a Synchroton Radiation Source (SRS).  In this project, electrons are injected into an electron accelerator called booster ring to attain an energy of 700 Mev.  Then the electrons are extracted from booster ring to inject into storage ring where the synchrotron light is generated at the bends of electron trajectory.  This operation required a momentary deflection of electrons by electromagnets.  I developed the pulsed power supplies to generate a pulse of magnetic field when electrons reach the magnet.  In one of the magnets peak current requirement was 5000A.  This required a robust mechanical design to counter huge force of repulsion due to the current.  In another power supply a current of 1200A was switched in 30 nanoseconds.  The stability requirement of peak current was in ppm and time accuracy to synchronise the pulse with the position of electrons was few nanosecond which was a challenge 25 years ago.  All pulse supply generated huge electromagnetic interference (EMI) that needed to be suppressed as it would lead to malfunction of other subsystems of the project.

I also worked on Beam Position Monitoring system to monitor the position of electron beam in vacuum chamber.  I calculated the signal produced by the electron beam at the sensing electrodes.  After that I designed and developed front and electronics, this required designing of amplifiers of very high gain to amply the signals of less than one microvolt and storing the signal in flash memories using very fast ADC.

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