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PhD Ceremony Bodhaditya Santra

18 January 2013

On 18 January, Bodhaditya Santra will defend his thesis 'Precision spectroscopy of neutral radium: towards searches for permanent electric dipole moments'.

Location: Academy Building, Broerstraat 5, Groningen

Time: 11:00 hrs.

Promotores: K. Jungmann, L.Willmann

Precision spectroscopy of neutral radium: towards searches for permanent electric dipole moments

Searches for non-zero permanent Electric Dipole Moments (EDM) of fundamental particles provide one promising approach for testing the range of validity of fundamental symmetries. An EDM can arise from the known CP-violation within the Standard Model (SM). However it is lower by several order of magnitude compared to the sensitivity of current and proposed EDM searches. In order to push the EDM limit towards the SM prediction and beyond we have to explore the sensitivity of experiments which depends on various issues.

This thesis describes a new experimental approach to search for an EDM in radium which provides the highest possible sensitivity in such systems. The sensitivity depend on the particular isotope and the atomic state considered. Production of rare isotopes of radium with 1/2 nuclear spin and study the atomic physics properties such as, absolute frequency measurement of the strongest laser cooling transition and most suitable transition for trapping the radium atoms are the main challenges of this thesis work. The challenge is accomplished by successful operation of effusive atomic beam of the isotope 225Ra, production of thermal 213Ra atoms and absolute frequency measurement of the main cooling transition 7s2 1S0 - 7s7p 1P1 and trapping transition 7s2 1S0 - 7s7p 3P1 with an accuracy better than 5 MHz. The hyperfine structure interval of the 7s7p 1P1 level is also determined with an accuracy better than 4 MHz which is in good agreement with previous measurement at the ISOLDE facility at CERN. Further, a strategy based on two-photon Raman transition is demonstrated with barium atoms for sensitive probing of the metastable D stated in radium. These measurements provide indispensable input to investigate SM predictions and beyond by means of observing an EDM in optically trapped radium atoms.

Bodhaditya Santra (India, 1985) studied Physics at the Indian Institute of Technology Kharagdur. His research was financied by FOM. Santra will continue his carees as a postdoc researcher at the TU Kaiserslautern.

Last modified:25 January 2019 11.18 a.m.
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