The Belle detector operated at KEKb B-factory in 1999-2010 was one of the most remarkable experiments in the field of elementary particle physics of the last decades. The B-factories results on CP-violation in B-mesons prove the validity of the CKM mechanism, which inventors, M.Kobayashi and T.Maskawa, won the Nobel Prize in physics in 2008. Belle was not successful only in CP-violation studies. The huge amount of the data collected by the Belle detector (1 billion BB-pairs) allows to made a number of discoveries in hadron spectroscopy. More than 10 new charmonium-like states were discoveries including puzzling X(3872) state and new charged charmonium-like Z-resonances which do not fit conventional charmonium model.
The Belle successor, Belle 2 collaboration, is aimed to operate the Belle 2 detector at SuperKEKb factory at 20 times higher luminosity. Increased luminosity imposes new requirements on the detector elements: they have to survive at higher radiation levels, operate at higher loads and at higher backgrounds.
The Belle K-long and muon system based on the resistive plate chambers (RPC) technology works well during all data taking period, however at Belle 2 environments its performance decreases to negligible level due to increasing load and high neutron background. To sustain detector operation it will be replaced by the new system based on the scintillation strips read-out by silicon photomultipliers (SiPM). The latter technology allows not only reach time resolution at level of 1ns but also perform the amplitude measurements. Nowadays the production of the new EKLM system's elements is finished, they are installled to the detector. Cosmic tests of the new system will be started this winter.