Development of new trigger electronics for the ALPACA experiment

The ALPACA experiment is a new air-shower array experiment in Bolivia, with high sensitivity for gamma rays above 100 TeV. The prototype of the array, ALPAQUITA, is currently fully operational, with about $1/4$ of the total area of the full array. With the goal of enabling the future extension of the array to Mega ALPACA, which requires covering an area of 1 km² and its is composed of $1477$ detectors, we have started developing a new triger system using modern programmable logic devices (FPGA+CPU) and considering a distributed architecture. In this paper, we will present a Monte Carlo study to evaluate the basic requirements for the trigger electronics of Mega ALPACA and the basic idea for the design of the new trigger.