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

4 Position Reconstruction of Scintillation Events
The scintillator decay time was measured in laboratory experiments for excitation by alpha
and beta particles (see table 4.1 and also fig. 5.2). The emission spectrum of the BOREXINO
scintillator is shown in fig. 4.1.
particle excitation (ns) (ns) (ns) (ns) Õ Õ Õ Õ
¬ and ­ 3.57 17.61 59.50 - 0.895 0.063 0.042 -
« 3.25 13.49 59.95 279.1 0.63 0.178 0.119 0.073
Table 4.1: The decay times and the relative quantities of the decay components of the liquid
scintillator È ÈÈÇ Ð .
Absorption and Light Scattering
The attenuation length for È ÈÈÇ Ð and for pure PC was obtained by measuring
the absorption of a monochromatic light beam propagating along the x direction using a
spectrometer and defining £ according to
Á Ü Á Ü£
As shown in figure 4.2, interaction with the fluor is the most probable process for photons having
wavelengths shorter than about 370 nm while photons with higher wavelengths preferably
interact with the solvent. The photons absorbed by the fluor are reemitted isotropically with a
48
Figure 4.2: Attenuation length of PC and ÈÈÇ Ð , calculated from the measured extinction
coefficients [Ali00].