When high energy alpha-particle (${}_2{}^4\mathrm{He}$) pass through nitrogen gas, an isotope of oxygen is formed with the emission of particles named x. The nuclear reaction is ${}_7{}^{14}\mathrm{N}+{}_2{}^4\mathrm{He}\to {}_8{}^{17}\mathrm{O}+\mathrm{x}$
What is the name of x?