Speaker
Description
COSINE-100 and ANAIS-112 are rejecting the annual modulating signal of DAMA/LIBRA. However, their background is higher than that of DAMA/LIBRA.
It is essential to verify the seasonal variations using NaI(Tl) detectors, which have a lower background than DAMA/LIBRA.
PICOLON (Pure Inorganic Crystal Observatory for LOw-energy Neutr(al)ino) aims to search for cosmic dark matter by high purity NaI(Tl) scintillator.
We developed a highly pure NaI(Tl) crystal by hybrid purification method.
Our purification method was the optimized combination of recrystallization and resin methods.
The recent result of $^{210}$Pb in our NaI(Tl) is less than 5.7 $\mu$Bq/kg.
The low-background measurement with highly radiopure NaI(Tl) is ongoing in Kamioka Underground Laboratory, Tohoku University.
The present detector consists of two prototype detectors, each mass is 1.3 kg.
The NaI(Tl) detector was installed into the pure copper shield and lead shield.
The sensitivity for annual modulating signals and finding dark matter particles will be discussed.
Reference: K.Fushimi et al., Prog. Theor. Exp. Phys. 2021, 043F01, DOI: 10.1093/ptep/ptab020
