QTC input has three gain ranges – "Small", "Medium" and "Large" – the resolutions for each are shown in Table. For each range, analog to digital conversion is conducted separately, but the only range used is that with the highest resolution that is not being saturated. The overall charge dynamic range of the QTC is 0.2–2500 pC, five times larger than the old . The charge and timing resolution of the QBEE at the single photoelectron level is 0.1 photoelectrons and 0.3 ns respectively, both are better than the intrinsic resolution of the 20-in. PMTs used in SK. The QBEE achieves good charge linearity over a wide dynamic range. The integrated charge linearity of the electronics is better than 1%. The thresholds of the discriminators in the QTC are set to −0.69 mV (equivalent to 0.25 photoelectron, which is the same as for SK-III). This threshold was chosen to replicate the behavior of the detector during its previous ATM-based phases. SuperKGd Gadolinium will be introduced into the Super-Kamiokande tank in late 2019, and begin operation in later 2019 or early 2020. This is known as the SK-Gd project (other names include SuperKGd, SUPERK-GD, and similar names). Nuclear fusion in the Sun and other stars turns protons into neutrons with the emission of neutrinos. Beta decay in the Earth and in supernovas turns neutrons into protons with the emission of anti-neutrinos. The Super-Kamiokande detects electrons knocked off a water molecule producing a flash of blue Cherenkov light, and these are produced both by neutrinos and antineutrinos. A rarer instance is when an antineutrino interacts with a proton in water to produce a neutron and a positron. Gadolinium has an affinity for neutrons and produces a bright flash of gamma rays when it absorbs one. Adding gadolinium to the Super-Kamiokande allows it to distinguish between neutrinos and antineutrinos. Antineutrinos produce a double flash of light about 30 microseconds apart, first when the neutrino hits a proton and second when gadolinium absorbs a neutron. The brightness of the first flash allows physicists to distinguish between low energy antineutrinos from the Earth and high energy antineutrinos from supernovas. In addition to observing neutrinos from distant supernovas, the Super-Kamiokande will be able to set off an alarm to inform astronomers around the world of the presence of a supernova in the Milky Way within one second of it occurring. The biggest challenge was whether the