Who discovered mass spectroscopy?

Mass spectroscopy/spectrometry was developed overtime in a series of steps with contributions from different scientists. The first mass spectrometer, which was known as a parabola spectrograph, was created in 1912 by British physicist J.J. Thomson. He utilized the mass spectrometer to reveal the first evidence of the existence of nonradioactive isotopes. The instrument used a gas discharge tube to generate ions, which were then passed through magnetic and parallel electric fields. The ions were then deflected into parabolic trajectories, and then detected on a photographic plate. Thomson worked alongside chemistry and physicist Francis Aston, who won the Nobel Peace Prize in 1922 for his discovery of the mass spectrograph, and isotopes in many non-radioactive elements. Electron ionization was first described in 1918 by Arthur J. Dempster. It was the first mass spectrometer that used positive rays to determine the ratio of the m/z of various substances.