AP-Seminare

Measurement of the Bound-State Beta Decay of Bare 205Tl81+ IonsONLINE ONLY

by Ragandeep Singh Sidhu (GSI)

Europe/Berlin
384 670 6358 (Zoom)

384 670 6358

Zoom

Zoom-Meeting https://gsi-fair.zoom.us/j/3846706358 Meeting-ID: 384 670 6358 by phone: +49 695 050 2596 Deutschland +49 69 7104 9922 Deutschland +49 30 5679 5800 Deutschland
Description

Ever since the construction of Experimental Storage Ring (ESR), measurement of the bound-state beta decay of 205Tl81+ ions was one of the main physics cases to be performed. Bound-state beta decay (βb), accompanied by the emission of a monochromatic anti-neutrino, was first predicted by Daudel et al. [1] in 1947 and the first direct observation of the βb decay was done in 1992 by Jung et al. [2] at the ESR in GSI, Darmstadt.
The measurement of the bound-state beta decay of fully-ionized 205Tl ions contains two very strong physics motivation cases. One is linked with the LOREX [3] project (acronym of LORandite EXperiment) wherein the measurement is needed to determine the matrix element for the pp-solar neutrino capture by the ground state of 205Tl to the 2.3 keV excited state in 205Pb. This capture reaction has by far the lowest threshold (Eve>53 keV) and is thus of utmost significance for extending the neutrino flux to lower energies. The second physics case is associated with the 205Pb/205Tl pair as a s-process cosmochronometer. In stellar medium, 205Tl can exist in ionized form and βb decay to the first excited state of 205Pb can counter-balance the reduction of 205Pb ions due to electron capture process. The measurement is crucial for the clarification of the fate of 205Pb in the early solar system.
In this seminar talk, results from the first direct measurement of the most awaited and novel experiment will be reported. The experiment was finally performed in March-April this year, after a long wait of almost three decades, amidst of corona crisis by employing the unique accelerator facility at GSI.

 

References
[1] R. Daudel, M. Jean and M. Lecoin, J. Phys. Radium 8, 238 (1947).
[2] M. Jung et al., Phys. Rev. Lett. 69, 15 (1992).
[3] M.K. Pavicevic et al., Nucl. Instr. and Meth. A 621, 282 (2010).