Aachen 2019 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 56: Neutrino-Detektoren II

T 56.3: Vortrag

Mittwoch, 27. März 2019, 16:30–16:45, S07

α/β discrimination techniques in Borexino — •Sale-Iti Kroon, Zara Bagdasarian, Sindhujha Kumaran, Livia Ludhova, Ömer Penek, Mariia Redchuk, and Yu Xu — Forschungszentrum Jülich, Jülich, Germany

Borexino is a liquid scintillator detector located in the Laboratori Nazionali del Gran Sasso, Italy whose main goal is the measurement of low-energy solar neutrinos. The first complete measurement of all the components of the pp-chain was performed with Borexino detector. In contrast, neutrinos from the CNO fusion cycle, expected to contribute less than 1% to the total solar power, have not been observed yet.

The observation of CNO solar neutrinos even in an ultra-pure liquid scintillator detector is challenging because of the similar spectral shapes of the signal due to CNO neutrinos and the 210Bi background. 210Bi from the 238U chain undergoes β- decay to 210Po and 210Po undergoes α-decay into stable 206Pb. As a part of the 238U decay chain, ideally, 210Bi would be in secular equilibrium with its daughter, 210Po. Unfortunately, due to convective motions inside the detector, 210Po can be introduced into the fiducial volume from peripheral sources. To prevent this, in 2015 the detector has been thermally insulated from its surroundings. Moreover, a large effort is dedicated towards linking the "easy-to-determine" 210Po alpha-decay activity to that of 210Bi. This can be achieved using different alpha/beta discrimination techniques. This study concentrates on testing and evaluation of several pulse-shape variables developed in Borexino analysis.