Given the task definition and input, reply with output. In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.

The ISIS and SNS facilities produce these particles using spallation, and a nonzero electric dipole moment would imply the violation of CPT theorem. Certain objects composed of these particles obey the Tolman-Oppeheimer-Volkov limit, whose antiparticle having a mass of 940 MeV was discovered by Bruce Cork. When free, this particle has a lifetime of about 15 minutes and decays into an antineutrino, an electron and a proton, and it is a baryon made up of two down quarks and one up quark. Discovered by James Chadwick, for 10 points, identify this neutral subatomic particle.
Science