A Tribute to Debendra Mohan Bose – The Unknown Indian Who missed the Nobel Prize

Debendra Mohan Bose was a great genius who made the country proud with his path breaking scientific work. Debendra Mohan Bose, a silent worker and a strikingly handsome figure, was honored in India and recognized abroad for pioneering researches in the field of cosmic rays, artificial radioactivity and neutron physics. He is also remembered as the scientist who more than once came close to making major breakthroughs that later won the Nobel Prize.

Debendra Mohan Bose

Debendra Mohan Bose

Born on 26 November 1885, Bose’s father was a homeopathic physician. His uncle, Anand Mohan Bose, was the first Indian Wrangler in Mathematical Tripos from Cambridge. Bose was the nephew of Acharya Jagadish Chandra Bose, the first modern scientist of India who lived in the same house with Debendra’s family. In fact, after the untimely death of his father Debendra was educated under the supervision of Jagadish himself.

Initially, Debendra enrolled for a degree in engineering in Sibpore Bengal Engineering College but a severe attack of malaria put an end to his pursuit of engineering. At the suggestion of Rabindranath Tagore, the Nobel laureate and a close friend of Jagadish, Debendra entered the Presidency College to study Physics. With a first class first he completed his MA in Physics in 1906. Later, he went to study in London and acquired both B.Sc. and ARCS diploma from the University of London.

Returning home, he got an appointment in the City College as a lecturer. From there he moved to the newly built University College of Science at Rajabazar accepting the Rash Behari Ghosh professorship in 1914. In the same year he was awarded the Ghosh Travel Fellowship for studies abroad and Debendra chose Berlin.

He joined the laboratory of Prof E. Regener. But then the First World War broke out and Debendra was interned in Germany. It was an era of great insights into the atom. He had earlier worked at the Cavendish Laboratory where the great J.J. Thomson was his guide. In the same laboratory worked C.T.R. Wilson who won the Nobel Prize for developing the cloud chamber that detected sub­atomic particles.

Now in Regener’s laboratory he worked on the development of a new type of Wilson Chamber for recording the tracks of ionizing alpha and beta particles from radioactive sources. His earlier training at the Cavendish laboratory came in handy here. He was successful in photographing the tracks of recoil protons produced during the passage of fast moving alpha particles in hydrogen filled chamber. The work helped in formulating a scheme for collisions among such particles. Bose also started photographing the recoil tracks of delta particles whose discovery was made at that time by Bumstead.

However, he was permitted to submit his findings only after the end of the war. The results of his investigations were published in 1916 in the famous journal Physikalische Zeitschrift. It was only a preliminary account. The full paper was published in 1922 in another famous journal Zeitschrift fur Physik. Later on scientists in this field concluded that Debendra Mohan had actually obtained the first photographic records of artificial disintegration.

World Wars have been important to Debendra Mohan’s work in a peculiar way. The Second World War broke out in 1939. This time, of course, he was in his own country doing research freely. Between 1939 and 1942 he with Biva Choudhuri exposed a large number of photo plates in the mountainous regions of Darjeeling. The idea was actually given by a famous scientist, Walter Bothe. He had asked Debendra Mohan to consider photographic emulsion as a continuously active cloud chamber where tracks are automatically registered and stored permanently.

Debendra Mohan and Biva Chaudhuri observed a number of long curved ionizing tracks that appeared to be different from those due to alphas or protons. In fact, they were looking at the first tracks of meson whose discovery was later announced by C.F. Powell. It happened in the closing year of the war – 1945. Two years later Powell announced the existence of two kinds of mesons, mu meson and pi meson. He received Nobel Prize for his discovery.

In fact, Powell followed the same method of determining the mass of mesons that was followed by Bose and Chaudhuri. However, the duo failed to attain success for a number of reasons. One was that Biva Chaudhuri had left for Blackett’s laboratory in England in 1945. Secondly, standard emulsions were not available in India and it proved to be a great stumbling block for the experiment. Powell, on the other hand, had induced M/s. Ilford Limited of England to produce improved plates and this put him in an advantageous position. He went on to win the Nobel Prize for his discovery of the development of the photographic method of studying nuclear processes and for the resulting discovery of the pion (pi-meson), a heavy subatomic particle.

Early 20th century Indian scientists. Sitting (from left): Meghnad Saha (1893-1956, astrophysicist), Acharya Jagadish Chandra Bose (1858-1937, polymath), Jnan Chandra Ghosh (chemist). Standing (from left): Snehamay Dutta (physicist), Satyendra Nath Bose (1894-1974, quantum physicist), Debendra Mohan Bose (1885-1975,  particle physicist), Nikhil Ranjan Sen (mathematical physicist), Jnanendra Nath Mukherjee (1893-1983, colloid chemist), Nagendra Chandra Nag (chemist). These scientists were part of the Bengal Renaissance, a general increase in literary and scientific achievement in India in the late 19th and early 20th century.

Early 20th century Indian scientists. Sitting (from left): Meghnad Saha (1893-1956, astrophysicist), Acharya Jagadish Chandra Bose (1858-1937, polymath), Jnan Chandra Ghosh (chemist). Standing (from left): Snehamay Dutta (physicist), Satyendra Nath Bose (1894-1974, quantum physicist), Debendra Mohan Bose (1885-1975, particle physicist), Nikhil Ranjan Sen (mathematical physicist), Jnanendra Nath Mukherjee (1893-1983, colloid chemist), Nagendra Chandra Nag (chemist). These scientists were part of the Bengal Renaissance, a general increase in literary and scientific achievement in India in the late 19th and early 20th century.

However, Powell was magnanimous in acknowledging the priority of Bose and Chaudhuri’s work. In ‘The Study of Elementary Particles by the Photographic Method’ he wrote, “In 1941, Bose and Choudhuri had pointed it out that it is possible, in principle, to distinguish between the tracks of protons and mesons in an emulsion. The method was based on the difference for a given value of the residual range, in the momenta of particles of different mass. This has the consequence that the ‘scattering’ of the particles will be different; the smaller its mass, the more the track of a particle deviates from a straight line as it approaches the end of its range. Bose and Choudhuri exposed ‘half-tone’ plates at mountain altitudes and examined the scattering of the resulting tracks. They concluded that many of the charged particles arrested in their plates were lighter than protons, their mean mass being 200 me… the physical basis of their method was correct, and their work represents the first approach to the ‘scattering method’ of determining momenta of charged particles by observation of their tracks in emulsion.”

Bose did not stop at identifying subatomic particles. Like his uncle his researches branched out into different fields. He succeeded J.C. Bose as Director of the Bose Institute and was successful in establishing new branches of study such as Microbiology in the Institute. He also trained and inspired a generation of scientists at the Bose Institute.

Due to exposure to several cultural figures during his childhood, Bose evinced keen interest in social and cultural matters. He was closely associated with the management of the City College and served the Viswabharati University as its treasurer. He was one of the editors- in-chief of A Concise History of Science in India, a publication of the Indian National Science Academy (INSA).

Prof. Bose was in the habit of taking long walks. But while in Germany he started suffering from arthritis. Gradually this put an end to his walks. Eventually failing health forced Bose to take retirement from the Institute. He passed away in the morning hours of 2 June 1975.

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