Development of low-background CsI(T) crystals for WIMP search

Search for solar axions with CsI(Tl) crystal detectors

“…Major internal backgrounds for β-decays in our CsI(Tl) crystals are 137 Cs (Q=1175.6 keV), 134 Cs (Q=2058.7 keV) and 87 Rb (Q=282 keV). The energy spectra from those radioisotopes are flat in our search region, 2 keV to 12 keV, as from Compton-scattered γ rays in the MD events [31,32]. Therefore we expect that the MD energy spectrum is similar to the R e − spectrum in the SD sample.…”

“…Since an axion would give rise to an electron-like signal with a hit in only a single detectormodule, only SD events were selected as axion candidate events. The SD events include surface α events (S α ) and electron recoil events (R e − ) from Compton scattered γ rays and β decays in the crystal bulk [31,32]. The S α events come from decays of radioactive isotopes which contaminate the surfaces of the crystals or the surrounding materials.…”

Study of fast neutron detector for COSINE-100 experiment

“…The α-α coincidence between 222 Rn and 218 Po decay and β -α coincidence between 214 Bi to 214 Po decay can be identified because of their fast lifetimes [7,12]. Fig.…”

Construction of Neutron Detector for the COSINE-100 experiment

“…To understand the background level, another detector with 10 times large in volume is installed inside the KIMS-CsI test facility at the Y2L [3]. An available polyethylene shielding maybe good enough to prevent external neutrons.…”

“…Therefore understanding alpha background for NMD is important. To understand background, detector filled with UGF having mass 0.66 kg is installed inside the KIMS-CsI shielding test facility at the Y2L [3]. The alpha energy distribution from the detector is as shown in figure 6.…”