Wavelength Shifter in Water Cherenkov Detectors
- E. Heiberg and J. Marshall, Rev. Sci. Instrum. 27 (1956) 618 Early work at the University of Chicago. A
lucite chamber, a bit like micro-K but with only
one 5-inch tube, is used to detect Cherenkov light from cosmic
ray muons. The device is operated with the PMT at the bottom and
at the top... with the PMT at the bottom, the pulse-height from
muons is about an order of magnitude higher than with the PMT at the
top, for pure water, due to the directionality of Cherenkov
radiation. Then five different compounds are added, to the water,
two of which enhance light output by a modest factor
of 1.2-1.3. These two also reduce the
directionality of the light output, so in the end the pulse-height
with the PMT at the top grows to about 2/3 of that seen with the
PMT at the bottom.
- Bezaguet et al., Nucl. Instrum. Meth. 158 (1979) 303 Work at CERN. Now the radiator is water in a box that is painted
white, and so directionality from the Cherenkov radiation
is lost even for pure water. They see a factor of 3.8 increase
in pulseheight when on of the waveshifters from Heiberg and Marshall
is added! Perhaps this improvement is a consequence of the change
from a lucite/TIR box to a white light integration box.
- G. Van Ginkel, Int. J. Appl. Radiat. Isot. 31 (1980) 307 Work at Utrecht. Cherenkov light from phosphorus-32 beta decay
betas in small vials of water + waveshifter is measured, and characterized
in terms of an overall efficiency for phosphorus-32. Some new
waveshifters, beta methyl umbelliferon and esculin are evaluated.
- Badino et al., Nucl. Instrum. Meth. 185 (1981) 587 Work by a Italian/Brazilian Group. The idea was to add one wave-shifter
explored by Heiberg and Marshall, amino-G, to water and see how the the
of Cherenkov radiation was influenced. The test detector was painted
very black and emphasized directionality, so a pulse-height increase
of 1.2 was found. Probably if a white-painted light integration box
were used, a pulseheight increase of a factor of 3-4 would have been seen.
- Bem et al., J. Radioanalytical Chem. (1983) 69
Polish work trying out more waveshifters in non-water matrices.
Betas from phosphorus-32 and chlorine-36 are used, and
salicylic acid is studied as a waveshifter.
- Gebicki et al., Int. J. Appl. Radiat. Isot. 31 (1984) 1133 Polish work. Cherenkov light from chlorine-36 beta decay
betas in small vials of various matrices (including water) + waveshifter is measured, and characterized in terms of an overall efficiency for chlorine-36.
Salicylamide is highlighted.
- Dai et al., Nucl. Instrum. Meth. in Phys. Res. A (2008) 290 Very recent work at Carleton in Canada. New wave-shifters
were evaluated for addition to SNO, and as much as a factor of 4 pulse-height
increase was deduced in a little muon setup. Their favorite wave-shifter
is Carbostyril 124, which they used at a relatively high concentration
of 15.4 ppm. They calculated that a concentration of only 0.5 ppm would
have been sufficient, however. They also suggested the use of
Alexa Fluor 350,
although they did not test it.