Emilio Gino Segre

1. Emilio Gino Segre • Davin Dimas Pagan • West Chester University - This slide show is a biography of Emilio SegreIt was made for the spring 2013 Modern Physics (PHY 240) class at West Chester University Picture: http://www.mphpa.org/classic/NPO/Nobel.htm

2. Emilio Segre is famous for the 1959 Nobel Prize he was awarded for the discovery of the antiproton. This presentation will focus on : • Family Background Emilio Segrè's Nobel medal. • Education • Scientific contributions

3. Family Background Segre was born in Tivoli, Rome on January 30, 1905 • He is the youngest of three brothers, both of which were over 10yrs older • His oldest Brother became an engineer and another was an expert in Roman Law His father did not go to college but successfully ran a paper company that made the family wealthy by the time Emilio was born His uncles went to college and were well respected in the community. His mother’s side of the family was also very well educated • (one brother had exceptionally well math skills and close friends with the famous mathematician Vito Volterra and another brother studied law and ran an extremely successful real-estate company) Emilio Segrè  at age 3, 1908

4. Scientific Interest At a young age he would become fascinated with physics His Uncle Gino was the first influential scientific person he met He taught and exemplified Segre the required qualities for anyone studying science “working ones head, honesty, patience, stamina, precision, and devotion” Segre was given and enjoyed reading books describing how to build various object as soon as he learned to read. At the age of 7, he already wrote down and tried experiments that he read in books or observed from his brother who was studying chemistry • He was most fascinated by experiments involving color change "All the colors are: The colors are of the rainbow. These colors can be obtained by passing sunlight through a pitcher filled with water or by passing sunlight through a prism. However, by passing the sun through the pitcher one does not obtain the colors in columns but in arcs, one within [the other]." Emilio, age seven.

5. High School He moved to Rome for high school He would rather learn in a very thorough way than briefly learning multiple topic... especially in for physics class He excelled in his math classes • Was bored in most classes and if permitted, would read math books in those classes He would read his older brothers’ advanced math and engineering books Interactions between classmates when he found himself (lacking rhetorical skills) unable to defend his opposing opinion taught him “distinguish between well-founded conclusions and those that prevail only through skilled advocacy”

6. College First choose engineering as a major by “process of elimination” He enjoyed studying math and other subjects in the first two years at the university a lot more then high school because it was more challenging In his third year, he was done with the preliminary classes (of physics, math, and chemistry) and transferred to an Engineering school • He found the engineering classes to be boring and less “imaginative” In 1927, through close friends and colleges, he was introduced and formed a relationship with Enrico Fermi • Fermi was a internationally known physicist who was most likely the only person in Italy, at the time, that had a clear and up to date understanding of modern physics Enrico Fermi, about 1928

7. College Through the friendship of Fermi, Emilio attended the International Physics Conference • Also in attendance were other famous physicians such as Plank, Rutherford, Bohr, Millikan, Pauli, and Heisenberg International Physics Conference at Como, 1927.Emilio is at the far left. (Lawrence Berkeley Laboratory) Attending this conference persuaded him switch from engineering to physics Fermi began to privately tutor him on many of the modern advancements • Later, other friends of Emilio would join He obtained his physics doctorate just one year after switching the major

8. Fermi never allowed Emilio or any other student to publish a paper containing insignificant results Emilio would publish a few papers concerning different aspects of physics closely related to Fermi’s studies • Many started off with Fermi explaining quantum ideas and theories leaving Emilio to find applications of them • One paper contained results of a often quoted paper that was done later done, in more detail, by Eugene Wigner and Victor Weisskopf Emilio would often be entrusted to write the papers that he and Fermi co-authored Emilio’s father would often tell say Emilio was living “off of Fermi’s crumbs” • Something Emilio would never forget for he knew it to be true

9. Fermi would discus many ideas with Emilio including the new ideas of radioactive isotopes using neutrons In 1938 Emilio would migrate and work in the U.S. at the Berkeley Radiation Laboratory • Due to Nazi’s influences, Emilio was forced to stay in the U.S M. Stanley Livingston and Ernest O. Lawrence with the 27-inch cyclotron (Lawrence Berkeley Laboratory) At the Berkeley Lab, Emilio would discover element 43 (technetium), 85 (astatine), and Plutonium 239 Through Fermi, Emilio would help in the Manhattan Project in Los Alamos • The properties of Plutonium 239 were discussed by him and Fermi and thought to be an alternative to Uranium 235 for use in the atomic bomb • Plutonium 239 was eventually used in the Trinity test and later “Fat Man” (the atomic bomb dropped over Nagaski) First atomic bomb explosion at Jornada del Muerto near Alamogordo on July 16, 1945. (Los Alamos Scientific Laboratory)

10. The Antiproton The first idea of an antiproton was conceived from the Dirac equations • Equations similar to the Schrodinger equations to wave functions for half spin particles The Dirac equations would lead to the assumption of anti-matter Emilio, thinking about the wrongly predicted from the Dirac equation magnetic moment of proton, sought a way to experimentally prove the existence of the anti-proton

11. Emilio and Owen Chamberlain knew that the antiproton would not be found the same way as the positron was (using cosmic rays) • The instead created an accelerator that can accelerate up to 6Gev • simultaneous creation of a proton or a neutron (2Gev), the best approach for making 2 billion electron volts available would be to strike a stationary target of neutrons with a beam of protons accelerated to about 6 billion electron volts of energy. After building the accelerator, they needed to think of a way to measure and identify it • For every antiproton created, 40,000 other particles would also come into existence; within about a 10 millionth of a second after it appears, an antiproton would come into contact with a proton and be annihilated. To identify the antiproton, at least two independent qualities would have to be measured • Segre’s teams decided on momentum and velocity

12. To measure momentum, his team used a system of magnetic quadrupole lenses • “The idea was to set up the system so that only particles of a certain momentum interval could pass through. As the Bevatron's proton beam struck a copper block target, fragments from collisions with nuclei would emerge in all directions. While most of these fragments were lost, some would pass through the system. For specifically defined values of momentum, the negative particles among these system-captured fragments would be deflected by the magnetic lenses into and through collimator apertures.” To measure velocity, used to separate the antiprotons from negatively charged pions, his team had combination of scintillation counters and a pair of Cerenkov detectors. • “The scintillation counters were used to time the flight of particles between two sheets of scintillators spaced 12 meters apart and signals from the two scintillators were set up to coincide only if they came from an antiproton.” Text His team expected to see the signature star image of an annihilation event if an the detected particle was actually an antiproton

13. The experiment The experiments began the first week of August 1955 and lasted until mid September “Subsequent analysis of the emulsion-stack images revealed the signature annihilation star that confirmed the discovery. In all, Segrè and Chamberlain and their group counted a total of 60 antiprotons, produced during a run that lasted approximately seven hours.” An antiproton (blue) enters a bubble chamber from bottom left and strikes a proton. The released energy creates four positive pions (red) and four negative pions (green). The yellow streak at the far right is a muon, a decay product of the adjacent pion. (The dark blue curlicues are low-energy electrons knocked from atoms, not involved with the antiproton.) Antiproton Emulsion Star, 1955.

14. The search for the antiproton was a success! • This lead Segrè and Chamberlain to win the Nobel Prize in 1959 Emilio would eventually go back to Rome as a physics professor At the age of 84, he died His constant note taking and “tirelessly obsession with accuracy and truth” left many historical accounts and books of the 20th century physics and physicists • Five of which are in the WCU library: From x-rays to quarks: modern physicists and their discoveries, A mind always in motion: the autobiography of Emilio Segrè, From falling bodies to radio waves: classical physicists and their discoveries, Enrico Fermi: physicist, Nuclei and particles: an introduction to nuclear and subnuclear physics

15. Sources A mind always in motion: the autobiography of Emilio Segrè • Used for the information of his childhood and life after the nobel prize Day of Trinity by Lamont, Lansing 1965, 1st ed • For information of Los Alamos & the atomic bomb From x-rays to quarks: modern physicists and their discoveries • For information on the atomic bomb and discovery of the anti proton http://quantummechanics.ucsd.edu/ph130a/130_notes/node45.html • For the explanation of the Dirac equations http://www.lbl.gov/Science-Articles/Archive/sabl/2005/October/01-antiproton.html • For information on his nobel prize winning experiment All pictures except for the colored picture on slide 13 came from A mind always in motion: the autobiography of Emilio Segrè The colored pictured was from http://www.lbl.gov/Science-Articles/Archive/sabl/2005/October/01-antiproton.html