Kavli Affiliate: Masaki Yamashita
| First 5 Authors: Kazufumi Sato, Masaki Yamashita, Koichi Ichimura, Yoshitaka Itow, Shingo Kazama
| Summary:
The idea of a hermetic quartz chamber in a dual-phase xenon time projection
chamber (TPC) has the potential to improve the detector sensitivity for direct
dark matter searches in the future. A major challenge facing TPC detectors in
future dark matter experiments will be the reduction of the internal background
such as $^{222}$Rn and the deterioration of the ionization signal due to
electronegative impurities. The hermetic quartz chamber can isolate the TPC’s
sensitive volume from external interference and is thus expected to prevent
contamination caused by the radioactive and electronegative impurities, which
originate from outer detector materials. At the Kamioka Observatory in Japan,
we developed a TPC with a quartz chamber that contains a $phi 48 times 58$ mm
volume of liquid xenon. At this development stage, we did not aim at the
perfect hermeticity of the quartz chamber. Our aim here is twofold: first, to
demonstrate via the use of a calibration source that the presence of quartz
materials in the TPC does not impact its operation; and second, to perform
quantitative measurements of the TPC’s characteristics. We successfully
measured electron drift velocities of 1.2–1.7 mm/$mu$s in liquid xenon under
electric fields ranging from 75–384 V/cm, and also observed small S2 signals
produced by a single ionized electron with a light yield of 16.5 $pm$ 0.5 PE.
These results were consistent with the expected values; therefore, our
demonstrations provide a proof of principle for TPCs incorporating a quartz
chamber.
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