Narrow Results

A fundamental breakthrough which opened the way to the realization of the Borexino detector was the demonstration of exceptionally low, unprecedented radioactive contaminations in the liquid scintillator, obtained with its pilot prototype Counting Test Facility. Though of limited dimension, with its 4.8 m³ of active liquid core, CTF has however been a key milestone not only for Borexino, but also for the entire field of the ultra-low background searches. Here, we succinctly remind the motivations, which concurred to lay down the project, as well as the specific radiopurity challenge, which guided the design. After the description of the technical elements of the detector, the main outcomes are summarized, both regarding optical and purity scintillator properties, with special emphasis on the exceptional achievements in term of ultra-low traces of radioactive contaminants. The discussion is completed with the description of how CTF was employed for the pre-qualification of the entire inventory of the Borexino scintillator, confirming also in the final phase of its life its essential role for the success of the overall Borexino solar neutrino program.

Borexino achieved radiopurity world records. During each phase of the Experiment, starting from the fabrication up to the commissioning, various techniques to reach this important result have been adopted. A special care has been taken in the material screening and selection, in the component cleaning and installation and in the scintillator purification and handling. In this paper, the installation part will be described.

The Borexino experiment for solar neutrino physics and other rare phenomena requires an extremely low radioactive background to disentangle the very few events due to neutrino interactions. Therefore, the Borexino scintillator has to satisfy the most stringent radiopurity requirements, being about eight orders of magnitude less radioactive than an ordinary material. This was achieved by means of scintillator purification techniques and of a special care during all the production, handling and procurement of the scintillator solvent. This paper describes the methodology and the quality control procedures that were employed during the production, handling and shipping of the solvent.

Water Purification is often an important methodological tool in low radioactivity experiments. A variety of techniques have been exploited in the frame of the Borexino experiment to the goal of using water as a high purity shielding and as a reagent for cleaning and purification processes. This paper describes the water purification strategies and the purification results obtained in Borexino.

Water purification is an important technique in high-mass low radioactivity experiments in modern physics. Water is frequently used both as a shielding and as the sensitive part of a particle detector in underground arrangements, especially in the frame of Astroparticle Physics studies. In this paper, I will describe the main purification techniques and discuss some of its performances.