Abstract
What individual discovered the electron with the help of their group of British physicists in the late 1800's?
Electron
List of Dutch inventions and discoveries History of subatomic physics Jules Fejer Lepton Oops-Leon
List_of_Dutch_inventions_and_discoveries-Electron_spin_(1925) History_of_subatomic_physics-First_subatomic_particles Jules_Fejer-Abstract Lepton-History Oops-Leon-Abstract
In 1925, Dutch physicists George Eugene Uhlenbeck and Samuel Goudsmit co-discovered the concept of electron spin, which posits an intrinsic angular momentum for all electrons. 
From atoms to nucleons. First subatomic particles. However, near the end of 19th century, physicists discovered that Dalton's atoms are not, in fact, the fundamental particles of nature, but conglomerates of even smaller particles. Electron was discovered between 1879 and 1897 in works of William Crookes, Arthur Schuster, J. J. Thomson, and other physicists; its charge was carefully measured by Robert Andrews Millikan and Harvey Fletcher in their oil drop experiment of 1909. Physicists theorized that negatively-charged electrons are constituent part of "atoms", along with some (yet unknown) positively-charged substance, and it was later confirmed. Electron became the first elementary, truly fundamental particle discovered. Studies of the "radioactivity", that soon revealed the phenomenon of radioactive decay, provided another argument against considering chemical elements as fundamental nature's elements. Despite these discoveries, the term "atom" stuck to Dalton's (chemical) atoms and now denotes the smallest particle of a chemical element, not something really indivisible. 
Jules Fejer (January 22, 1914 - December 21, 2002) was a Hungarian physicist. Fejer was born in Budapest, Austria-Hungary. In the late 1950s he wrote a fundamental paper on incoherent backscatter, explaining why the width of the backscattered echo was determined primarily by the ion thermal velocity rather than by the electron thermal velocity. He was a one of a group of ionospheric physicists brought together by Henry G. Booker to start what became the Electrical and Computer Engineering department at the University of California, San Diego. He was elected a Fellow of the American Geophysical Union in 1990 and continued work with graduate students until 1995. 
The first lepton identified was the electron, discovered by J.J. Thomson and his team of British physicists in 1897. Then in 1930 Wolfgang Pauli postulated the electron neutrino to preserve conservation of energy, conservation of momentum, and conservation of angular momentum in beta decay. Pauli theorized that an undetected particle was carrying away the difference between the energy, momentum, and angular momentum of the initial and observed final particles. The electron neutrino was simply called the neutrino, as it was not yet known that neutrinos came in different flavours (or different "generations"). Nearly 40 years after the discovery of the electron, the muon was discovered by Carl D. Anderson in 1936. Due to its mass, it was initially categorized as a meson rather than a lepton. It later became clear that the muon was much more similar to the electron than to mesons, as muons do not undergo the strong interaction, and thus the muon was reclassified: electrons, muons, and the (electron) neutrino were grouped into a new group of particles – the leptons. In 1962 Leon M. Lederman, Melvin Schwartz and Jack Steinberger showed that more than one type of neutrino exists by first detecting interactions of the muon neutrino, which earned them the 1988 Nobel Prize, although by then the different flavours of neutrino had already been theorized. The tau was first detected in a series of experiments between 1974 and 1977 by Martin Lewis Perl with his colleagues at the SLAC LBL group. Like the electron and the muon, it too was expected to have an associated neutrino. The first evidence for tau neutrinos came from the observation of "missing" energy and momentum in tau decay, analogous to the "missing" energy and momentum in beta decay leading to the discovery of the electron neutrino. The first detection of tau neutrino interactions was announced in 2000 by the DONUT collaboration at Fermilab, making it the latest particle of the Standard Model to have been directly observed, apart from the Higgs boson, which probably has been discovered in 2012. Although all present data is consistent with three generations of leptons, some particle physicists are searching for a fourth generation. The current lower limit on the mass of such a fourth charged lepton is , while its associated neutrino would have a mass of at least . 
Oops-Leon is the name given by particle physicists to what was thought to be a new subatomic particle "discovered" at Fermilab in 1976. The E288 collaboration, a group of physicists led by Leon Lederman who worked on the E288 particle detector, announced that a particle with a mass of about 6.0 GeV, which decayed into an electron and a positron, was being produced by the Fermilab particle accelerator. The particle's initial name was the greek letter Upsilon (formula_1). After taking further data, the group discovered that this particle did not actually exist, and the "discovery" was named "Oops-Leon" as a pun on the original name (mispronounced ) and the first name of the E288 collaboration leader. The original publication was based on an apparent peak (resonance) in a histogram of the invariant mass of electron-positron pairs produced by protons colliding with a stationary beryllium target, implying the existence of a particle with a mass of 6 GeV which was being produced and decaying into two leptons. An analysis showed that there was "less than one chance in fifty" that the apparent resonance was simply the result of a coincidence. Subsequent data collected by the same experiment in 1977 revealed that the resonance had been such a coincidence after all. However, a new resonance at 9.5 GeV was discovered using the same basic logic and greater statistical certainty, and the name was reused (see Upsilon particle). Today's commonly accepted standard for announcing the discovery of a particle is that the number of observed events is 5 standard deviations (σ) above the expected level of the background. Since for a normal distribution of data, the measured number of events will fall within 5σ over 99.9999% of the time, this means a less than one in a million chance that a statistical fluctuation would cause the apparent resonance. Using this standard, the Oops-Leon "discovery" would never have been published. 