Ph.D. Thesis Colloquium
DEPARTMENT OF INSTRUMENTATION AND APPLIED PHYSICS
Ph.D. Thesis Colloquium
NAME OF THE CANDIDATE : Miss. Puspita Ray
DEGREE : Ph.D.
TITLE OF THE THESIS : Studies on Thick GEM UV Photon Detector,
SUPERVISOR : Prof. K. Rajanna & Prof. S. Asokan.
DATE & TIME : Wednesday, 17th July 2019 at 03.30 PM
VENUE : Seminar Hall, Dept. of Instrumentation and Applied
Large area photodetectors with single photon counting ability motivates to develop gaseous photomultiplier (GPM), that combine thin film photocathode with electron multipliers for efficient detection of UV photon. This involves extensive research on photocathode preparation, characterization and photoemission properties of UV photocathodes; detector’s operating parameters which influence avalanche process, electron transport properties and hence performance of the detector. THGEM based photomultipliers offer high gain, fast response, high rate capability and affordable costs with large detection area and efficient detection of light at single photon level and is therefore motivation for studying such detector and related technologies.
In this thesis, a detailed study that concerns the development and performance of UV photon detector, realized by coupling THGEM with semi-transparent CsI photocathode is presented. The initial part of the thesis contains simulation studies carried out to understand the effect of gas properties and geometrical parameters of THGEM on detector’s performance. CsI photocathode, used to convert UV photon into electron is prepared and characterized. The challenges such as humid air exposure and damages due to electron bombardment faced during characterization are discussed here. The effect of substrate heating, during CsI film deposition, in enhancing the efficiency and increased surface area coverage, and their optical and photoemission properties are discussed here.
A major portion of the thesis focuses on the single electron spectrum obtained from the detector realized by coupling THGEM in double-stage mode with semi-transparent photocathode. The dependence of electron spectra on operating parameters such as drift field, multiplication voltage and transfer field is studied in detail. Simulations were carried out to interpret the experimental observations. In the next section of the thesis, position sensing capability of the THGEM UV detector has been explored. Detailed simulation study enables to optimize the parameters affecting spatial resolution for a given THGEM based imaging detector. Last section of the thesis deals with electroluminescence light produced in THGEM in order to build position sensitive and large area UV detector with optical readout. The study reported here enhances understanding of THGEM based UV detectors enabling us to develop highly sensitive UV detectors for variety of applications in particle physics and astronomy.
ALL ARE WELCOME
Date(s) - 17/07/2019
3:30 pm - 4:30 pm
Seminar Hall, Dept. of Instrumentation and Applied Physics
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