Measurements of extremely low radioactivity levels in BOREXINO

TL;DR

This paper details advanced techniques for measuring ultra-low radioisotope levels in the BOREXINO experiment, achieving record sensitivities through innovative spectrometry, radiochemical methods, and mass spectrometry.

Contribution

It introduces new ultra-sensitive measurement techniques and combines multiple methods to improve detection limits of radioisotopes in neutrino experiments.

Findings

Record low-level detection achieved for radioisotopes

Development of specialized low-background detectors

Enhanced radiochemical extraction methods

Abstract

The techniques researched, developed and applied towards the measurement of radioisotope concentrations at ultra-low levels in the real-time solar neutrino experiment BOREXINO at Gran Sasso are presented and illustrated with specific results of widespread interest. We report the use of low-level germanium gamma spectrometry, low-level miniaturized gas proportional counters and low background scintillation detectors developed in solar neutrino research. Each now sets records in its field. We additionally describe our techniques of radiochemical ultra-pure, few atom manipulations and extractions. Forefront measurements also result from the powerful combination of neutron activation and low-level counting. Finally, with our techniques and commercially available mass spectrometry and atomic absorption spectroscopy, new low-level detection limits for isotopes of interest are obtained.