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

- Rn degassing of liquid scintillator;
- water extraction of liquid scintillator.
6.3 The PXE Tests in the CTF
Module-0 comprises two 7 ton storage tanks (EP tanks), two 1 ton process tanks (buffer tanks),
equipped with nitrogen spargers at the bottom and spray nozzles at the top (for a turbulent
injection of liquid together with nitrogen gas, e.g. for a water extraction), two bellows teflon
pumps, two flowmeters, several Millipore filters (0.5, 0.1 and 0.05 micron) and one 70 l column
purification unit (see fig. 6.3). For BOREXINO a second column is planned which can be
operated in parallel or in line with the existing one. All the parts are connected to the upper and
the lower manifold of the Module-0, which are linked by several bridges. This design allows
a maximal flexibility of the flow path. All tanks, tubes, valves and filter housings are made
up of electropolished stainless steel, the pumps and filters are made from teflon. Connections
to the CTF Inner Vessel, the water plant, and the nitrogen plant are provided; foreseen are
connections to the BOREXINO storage area, buffer and Inner Vessel. A detailed description of
the system can be found in [Sch99c], [Har97].
The column consists of a large electropolished chamber of 1.5 m length and 25 cm diameter.
At the bottom is a filter plate with 14 teflon filter elements (47 mm), that are sandwiched
between two stainless steel plates with an array of machined holes (0.5 cm diameter). The
column has operated with an inlet pressure from 2.5 to 3.5 bar and flow rates of up to 1 ton
Figure 6.4: Sketch of the column purification process with following Rn degassing.
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