Bush in May 2008, urging him to "reverse the damage done to basic science research in the Fiscal Year 2008 Omnibus Appropriations Bill" by requesting additional emergency funding for the Department of Energy's Office of Science, the National Science Foundation, and the National Institute of Standards and Technology. He died after a heart attack at Stanford University Hospital on September 30, 2014 at the age of 87. His son, Jed Perl, is an author and art critic for The New Republic. Discovery of the tau particle The tau lepton (τ, also called the tau particle, tauon or simply tau) is an elementary particle similar to the electron, with negative electric charge and a spin of , but with 3477 times the mass. Together with the electron, the muon, and the three neutrinos, it is classified as a lepton. The tau was first detected in a series of experiments between 1974 and 1977 by Perl with his colleagues at the SLAC-LBL group. Their equipment consisted of SLAC's then-new – colliding ring, called SPEAR, and the LBL magnetic detector. They could detect and distinguish between leptons, hadrons and photons. SPEAR was able to collide electrons and positrons at higher energies than had previously been possible, initially at up to 4.8 GeV and eventually at 8 GeV, energies high enough to lead to the production of a tau/antitau pair. The tau has a lifetime of only and so these particles decayed within a few millimetres of the collision. Hence Perl and his coworkers did not detect the tau directly, but rather discovered anomalous events where they detected either an electron and a muon, or a positron and an antimuon: The need for at least two undetected particles was shown by the inability to conserve energy and momentum with only one. However, no other muons, electrons, photons, or hadrons were detected. It was proposed that this event was the production and subsequent decay of a new particle pair: + → + → + + 4 This was difficult to verify, because the energy to produce the pair is similar to the threshold for D meson production. Work done at DESY-Hamburg, and with the Direct Electron Counter (DELCO) at SPEAR, subsequently established the mass and spin of the tau. The symbol τ was derived from the Greek τρίτον (triton, meaning "third" in English), since it was the third charged lepton discovered. Nobel Prize and later