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Simulation of Nuclear Recoils due to Supernova Neutrino-induced Neutrons in Liquid Xenon Detectors

Neutrinos from supernova (SN) bursts can give rise to detectable number of nuclear recoil (NR) events through the coherent elastic neutrino-nucleus scattering (CE$ν$NS) process in large scale liquid xenon detectors designed for direct dark matter search, depending on the SN progenitor mass and distance. Here we show that in addition to the direct NR events due to CE$ν$NS process, the SN neutrinos can give rise to additional nuclear recoils due to the elastic scattering of neutrons produced through inelastic interaction of the neutrinos with the xenon nuclei. We find that the contribution of the supernova neutrino-induced neutrons ($ν$I$n$) can significantly modify the total xenon NR spectrum at large recoil energies compared to that expected from the CE$ν$NS process alone. Moreover, for recoil energies $\gtrsim20$ keV, dominant contribution is obtained from the ($ν$I$n$) events. We numerically calculate the observable S1 and S2 signals due to both CE$ν$NS and $ν$I$n$ processes for a typical liquid xenon based detector, accounting for the multiple scattering effects of the neutrons in the case of $ν$I$n$, and find that sufficiently large signal events, those with S1$\gtrsim$50 photo-electrons (PE) and S2$\gtrsim$2300 PE, come mainly from the $ν$I$n$ scatterings.