Speaker
Description
Some WIMP dark matter experiments use liquid argon (LAr) as the target material for its high
scintillation light yield and good background discrimination. Particle interactions in the LAr produce
scintillation light at 128 nm which must go through a wavelength shifting (WLS) material to be
detected by standard photomultiplier tubes. Tetraphenyl-butadiene (TPB) is a common WLS for LAr
based detectors, including DEAP-3600, due to its high light yield and fast scintillation time.
Pyrene-polystyrene thin films have been proposed as a complementary WLS for rejection of
pathological backgrounds in the detector because it has a long scintillation time and high light yield
relative to TPB. Light from particle interactions that reach the pyrene coating will produce a pulse
signature distinct from interactions of light with TPB.
We present the characterization of the fluorescence properties of these pyrene coatings, such as the
light yield, fluorescence time, and spectra, as a function of temperature. These measurements were
taken at the Queen’s University optical cryogenic test facility to characterize these films down to 4 K.