UV quantum efficiencies of organic fluors

Characterization of UV-enhanced SiPMs for imaging in a high pressure xenon electroluminescent TPC

“…from about 3% to about 18%. This value is compatible with the TPB conversion efficiency close to 90% reported in the literature [26], [27] for the deposited thickness considered. Indeed, considering the PDE close to 50% of the standard SiPMs at 430 nm (wavelength of the re-emitted photons), the effective detection efficiency of the coated SiPMs is about 22% if we assume 90% conversion efficiency of the TPB and 50% reemission onto the SiPM surface.…”

“…Indeed, one or two fluorescent photons may be emitted isotropically by the TPB molecules as a consequence of the absorption of a UV incident photon. This effect, observed and reported in [26], increases the micro-cells occupancy per incident photon, which inhibits the simultaneous detection of an increasing number of incident photons.…”

“…This limitation is overcome by shifting the VUV scintillation to the visible light with Tetraphenylbutadiene (TPB), an organic compound that can be deposited by vacuum-evaporation on the active area of the photosensors. The molecules of this compound absorb the short wavelength photons (< 340 nm) and re-emit them in the blue (peak at 430 nm) with an efficiency above 90% for areal densities below 0.15 mg/cm 2 [26]. The SiPMs used for the NEXT tracking system (Hamamatsu S10362-11-50P) were coated with TPB of 0.1 mg/cm 2 areal density, which corresponds to a thickness of 130 ± 10 nm, following the protocol described in [20].…”

Further studies of proportional electroluminescence in two-phase argon

“…In particular, PMT QE averaged over the WLS emission spectrum is < QE >= 26.6%, PMT QE averaged over the N 2 2PS emission spectrum and convoluted with the WLS hemispherical transmittance is < QE >= 5.1% and MPPC PDE averaged over the N 2 2PS emission spectrum and convoluted with the acrylic plate transmittance is < PDE >= 18.1%. Also, we used CE = 0.58 around 128 nm [23], CE = 0.40 at 300-400 nm [22][23][24] and CE = 0 above 400 nm.…”

Liquid noble gas detectors for low energy particle physics

“…For example, p-terphenyl emits mostly between 280 nm and 350 nm, diphenyloxazolyl-benzene (POPOP) shifts the light to the region 340-420 nm, diphenyloxazole (PPO) emits between 305 nm and 365 nm [229]. Tetraphenyl butadiene (TPB), which emits in the blue wavelength region from 400 to 470 nm [230,231,232], is a popular choice for large liquid argon detectors [233,234]. A more complete list of wavelength shifting materials can be found in [9, p.76].…”