Intense vacuum ultraviolet and infrared scintillation of liquid Ar-Xe mixtures

Abstract

Vacuum ultraviolet light emission from xenon-doped liquid argon is described in the context of liquid noble gas particle detectors. Xenon concentrations in liquid argon from 0.1 ppm to 1000 ppm were studied. The energy transfer from the second excimer continuum of argon (∼ 127 nm) to the second excimer continuum of xenon (∼ 174 nm) is observed by recording optical emission spectra. The transfer almost saturates at a xenon concentration of ∼10 ppm for which, in addition, an intense emission in the infrared at a peak wavelength of 1.17 µm with 13000 ± 4000 photons per MeV deposited by electrons had been found. The corresponding value for the VUV emission at a peak wavelength of 174 nm (second excimer continuum of xenon) is determined to be 20000±6000 photons per MeV electron energy deposited. Under these excitation conditions pure liquid argon emits 22000 ± 3000 photons per MeV electron energy deposited at a peak wavelength of 127 nm. An electron-beam induced emission spectrum for the 10 ppm Ar-Xe liquid mixture ranging from 115 nm to 3.5 µm is presented. VUV emission spectra from xenon-doped liquid argon with exponentially varied xenon concentrations from 0.1 ppm to 1000 ppm are also shown. Time structure measurements of the light emissions at well-defined wavelength positions in the vacuum ultraviolet as well as in the near-infrared are presented. PACS. 29.40.Mc Scintillation detectors -33.20.Ni Vacuum ultraviolet spectra -61.25.Bi Liquid noble gases arXiv:1511.07723v1 [physics.ins-det]

Fast component re-emission in Xe-doped liquid argon

“…The shape of averaged waveform has a simple hump structure described by two processes: transfer of excitation from Ar * 2 to Xe atoms with formation of Xe * 2 excited molecules (2.2) and the subsequent decay of those. Note, that there is an infrared emission from de-excitation of (ArXe) * molecules described in papers [17,32]. However, this infrared component is invisible with our PMT.…”

“…This improves position reconstruction since the re-emission occurs in the point of interaction.It was shown that gaseous xenon doped in LAr works as a volume-distributed WLS shifting the wave length from 128 nm to around 175 nm [14][15][16]. Currently several groups are studying its wavelength shifting parameters and the properties of the LAr+Xe mixture [17][18][19][20]. As shown previously [21], Xe doped in small concentrations (up to 260 ppm by mass) re-emits only the slow component of LAr scintillation.…”

“…The mixture with higher Xe concentration was prepared by adding a new portion of Xe to the existing mixture according to the described procedure. In this paper, the xenon concentration is presented in terms of gram/gram as used in previous studies by other groups [17,20]. The purification of the Ar or Ar+Xe mixture was performed in the gas phase during the liquefaction process using a Mykrolis1 gas filter.…”

Background discrimination for neutrinoless double beta decay in liquid xenon using Cherenkov light

“…Argon does have a "third continuum" in its emission spectrum that produces some light between the UV and IR [13] and no study has completely ruled out this mechanism in xenon. However, a study on xenon-doped argon [14] shows no scintillation between the UV and IR. Assuming the same holds true tering is neglected for photons with wavelengths greater than 436 nm as in those wavelengths the scattering length is much larger than the detector sizes simulated here.…”

Photon emission and atomic collision processes in two-phase argon doped with xenon and nitrogen

“…The excited N * 2 (C) states can be quenched in collisions with Ar and N 2 species in reaction (10) and (12); in particular reaction (10) competes with reaction (8) Fig. 1: Energy levels of the lower excited and ionized states relevant to the ternary mixture of Ar doped with Xe and N2 in the two-phase mode; these are shown for gaseous Ar [32], gaseous N2 [33,34], gaseous Xe [32], liquid Ar [19,[35][36][37][38] and Xe in liquid Ar [22,38]. For N2, the vibrational levels of the C 3 Πu, B 3 Πg and A 3 Σ + u molecular states, as well as the dissociation levels (N+N), are also shown (except those of the ground state X 1 Σ + g ).…”