Development of a Liquid Scintillator and of Data ... - Borexino - Infn

2 The Borexino Experiment
2.3.2 Ancillary Systems
Scintillator Purification and Fluid Handling System
The system to store, handle and purify the 300 tons of PC scintillator and 1000 tons of PC
buffer consists of a storage area for the scintillator and the concentrated fluor and quencher
solutions, several purification systems, and detector filling systems for BOREXINO and the
Counting Test Facility (CTF) (see fig. 2.7).
The purification system is composed of five separate units to apply different purification
methods to the scintillator: sub-micron filtration to remove dust particles, water extraction
to remove ionizable elements like metals, vacuum distillation to remove low volatility contaminants
like dust particles and degraded solvent molecules, nitrogen stripping to remove
gaseous impurities ( Rn, Kr) and water dissolved in the scintillator, and solid column purification
to remove polar impurities. The method of column purification will be described in
more detail in chapter 6. A complete description of the purification system can be found in
[Ben98, Sch99c].
The purification plants are designed to carry out the purification prior to and during the filling
operations. Continuous on-line purification of the scintillator as a whole is provided, if necessary,
though the hope is that this procedure will not be required in BOREXINO. The PC used
for the scintillator will be delivered well in advance of the filling operation. It will be tested in
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W: movable crane
H: tunnel walls of the hall C
CR: clean room of the CTF
LHS: liquid handling system
BOREXINO
S: storage vessel area for the liquid scintillator
LHS
BB: big building with electronic equipment, clean rooms etc.
CTF
Figure 2.7: Layout of the BOREXINO installations in hall C.