Here is a short summary of the work for which the IPA Rahul Basu Memorial award for 2022 was given.
The awardees:
Dr. Anupam Ray, Tata Institute of Fundamental Research, Mumbai Thesis Title: Unravelling the Mystery of Dark Matter with Stars & Black Holes.
Dr. Anuparam Ray won the award for his important contributions to astroparticle physics. Anupam improved the formalism of dark matter capture in stars using multiple scattering techniques. He also studied the possibility that neutron stars could transmute into light black holes. One of the remarkable results he found was that asymmetric dark matter could accumulate inside neutron stars and transmute them into a low-mass black hole. These transmuted black holes could be lighter than allowed by the naive Chandrasekhar limit, and could find relevance for the unusual mass-gap objects being seen by LIGO. Another interesting direction in his work was the calculation of neutrino based constraints on the abundance of light primordial black holes.
Dr. Shubham Pandey, Indian Institute of Science Education and research Pune
Thesis title: Performance of High Granularity Calorimeter prototypes for the CMS HL-LHC upgrade in beam test experiments at CERN.
Dr Shubham Pandey was a part of the efforts towards preparations for beam test experiments and data taking at CERN for high luminosity LHC operations.
He provided the first set of calibrations of calorimeters using muons in the beam test experiments, which led to alignment corrections and signal to noise studies. His analysis of pion data led to an algorithm which performed well across the full energy scale used in the experiment. His work superceded previous results and led to the identification of lacuna in calibration and resolved discrepancies in the scale, leading to improved final results. His thesis constitutes an important reference document for new analysers.
The runners up:
Dr. Biswajit Sahoo, Harish-Chandra Research Institute, Prayagraj. Thesis title: Classical and Quantum Subleading Soft Theorem in Four Spacetime Dimensions.
Dr Biswajit and collaborators gave a proof of the a multiple soft graviton theorem in a general theory of matter coupled to graviton fields. He also verified this for a special case. They further extended this to the quantum version of the soft graviton theorem, and found logarithmic corrections similar to those found earlier for the classical case. He also added the case of electromagnetic radiation. Here, these logarithmic corrections determine the late time tail of the gravitational radiation emitted during any scattering or explosion, and could be observed in future gravitational wave experiments. Further analysis of these corrections was carried out via classical analysis.
To summarise, Dr Biswajit's thesis contained very sophisticated technical analysis with consequences which can in principle be tested in the classical limits and in experiments.
Dr. Samir Banik, National Institute of Science Education and Research, Bhubaneswar
Thesis title: Search for Lightly Ionizing Particles in SuperCDMS and simulation of neutron
backgrounds.
Dr Samir Banik's work is a very important contribution towards detectors of very low energies where lightly ionising particles can exhibit fractional charge. The thesis developed suitable modules in GEANT4 which is a universal simulation tool for nuclear and particle physics.
The simulation work done here is to be integrated in the official GEANT4 toolkit in future.
This was a highly commendable contribution. In addition, the thesis set very strong limits for fractional charges. These results provide an important step towards search of light charged particles and design of dark matter detectors in India.
It was a great pleasure to listen to the awardees present their work, exactly one year ago at IISER Mohali.
The depth and breadth of the thesis nominated and awarded speaks for the high level at which research is carried out in Particle Physics in the country.
Grateful thanks to the award committee and others who did the gruelling work of reading the 20+ nominations and narrowing them to 4, and also to the Indian Physics Association for administering this award.
This (much delayed) blog post is by Neelima Gupte and Sumathi Rao.
