Measurement of coherent elastic neutrino-nucleus scattering with ultra-radiopure NaI(Tl) crystals

点击翻译按钮获取中文摘要

A low-background voltage divider for 3-inch Hamamatsu R11065-20 photomultiplier (PMT) was developed to study non-linearity of the PMT output. Most radiopure electronic components for the divider were selected using a low-background high-purity germanium detector at the Kamioka underground laboratory. The PMT with the developed voltage divider was tested using　NaI(Tl) (sodium iodide) crystal in a low-background shielding at the Kamioka mine. The measurements demonstrated lower background levels in comparison to a same configuration with a standard voltage divider provided by Hamamatsu Photonics company. However, a strong saturation was observed for high energies. The problem was discussed with Hamamatsu Photonics company. A new voltage divider circuit will be developed in cooperation with a Hamamatsu personnel.A new 5-inch ultra-low-background NaI(Tl) detector was tested at the Kamioka underground laboratory. The detector calibration using 60Co, 133Ba and 137Cs sources was performed. The radiopurity of 5-inch NaI(Tl) crystal was measured in a low-background shielding at the Kamioka underground laboratory. Despite of a higher than expected contamination by 210Pb, the developed 5-inch NaI(Tl) crystal is an excellent detector to measure a coherent elastic neutrino-nucleus scattering.