Poulomee Ghosh
INTERNSHIPS and PROJECTS
​Investigating Electrical Transients in CMS GEM Detectors: Ensuring Stability in LV Board Design, (May-July, 2019)
CERN, Espl. des Particules 1, 1211 Meyrin, Switzerland.
As part of the Compact Muon Solenoid (CMS) collaboration at CERN, a study was conducted on the occurrence and characteristics of voltage transients in the Low Voltage (LV) board of the Gas Electron Multiplier (GEM) detector. The project was aimed at improving the stability and protection of sensitive front-end electronics used in high-energy physics experiments.
Transient events were captured and analyzed using high-bandwidth oscilloscopes and precision data acquisition systems. Various operating scenarios were simulated, and transient behaviors were examined under different load switching patterns and grounding configurations. Special attention was given to the role of decoupling capacitors, PCB layout constraints, and current draw fluctuations, which were identified as contributing factors to voltage instability.
Through this study, key vulnerabilities were highlighted, and recommendations were proposed to mitigate noise and ensure robust operation of GEM detectors in radiation-prone environments. The findings were intended to support the development of more reliable detector electronics for future CMS upgrades.
Supervisor: Dr. Archana Sharma and Dr. Martina Rassegotti
A Study on Linear Complexity in Shift Register Sequences, (May-June 2018)
IIT Guwahati, Assam, India, 781031.
A detailed study was carried out on the linear complexity of sequences generated by feedback shift registers (FSRs), with a focus on cryptographically significant structures. The project involved analyzing both linear feedback shift registers (LFSRs) and nonlinearly filtered FSRs, particularly those generating Groth sequences—a class known for their high linear complexity.
To assess the unpredictability of generated binary sequences, the Berlekamp-Massey algorithm was utilized for computing the minimum degree of LFSRs capable of reproducing a given sequence. Furthermore, complex Groth sequences were constructed using Langford Arrangements, which define second-order product layers in the non-linear Boolean function space.
The study was extended to general feedback registers with arbitrary feedforward functions, where the notion of strong and weak linear complexity was explored. A key contribution of the project was demonstrating how a nonlinear register could be embedded into a larger linear structure, thereby bounding its strong linear complexity and improving its theoretical security against linear attacks.
Supervisor: Dr. Srinivasan Krishnaswamy
Co-Supervisor: Dr. Suman Roy
Studies on Interfering Signals in the Measurement of partial Discharge on Condition Monitoring Electrical Apparatus, (August, 2019-June, 2020)
NIT Durgapur, West Bengal, India, 713209
As part of the final year undergraduate project, a comprehensive frequency-domain analysis was conducted on high-speed transients arising from various electrical events such as partial discharges, relay switching, and inverter-fed motor operations. Signals were captured under diverse industrial conditions and were processed using Fast Fourier Transform (FFT) and Welch’s Power Spectral Density estimation to evaluate their spectral characteristics.
The study involved the classification of transient signals originating from power line communication relays, on-off switching events, and noise contamination, along with radiated RF emissions from induction motors operating at different speeds. Each signal was characterized based on its amplitude spectrum and spectral density, enabling the identification of signature frequency patterns.
A key contribution of the project was the development of a MATLAB-based framework that automated the signal processing pipeline—from raw data acquisition to frequency-domain feature extraction. The resulting insights were intended to support condition monitoring and fault detection in high-frequency power electronics and rotating machines.
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Fig. 3. (a) Simulink model for generating switching transient, and (b) FFT of different RF pulse, as experimented.
Supervisor: Dr. Chiranjib Koley