Emilio Gino SegreDavin 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

This presentation will focus on :

• Family Background

• Education

• Scientific contributions

Emilio Segre is famous for the 1959 Nobel Prize he was awarded for the discovery of

the antiproton.

Emilio Segrè's Nobel medal.

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 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

His oldest Brother became an engineer and another was an expert in Roman Law

Emilio Segrè  at age 3, 1908 (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)

Scientific Interest

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"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.

He was most fascinated by experiments involving color change

At a young age he would become fascinated with physics

His Uncle Gino was the first influential scientific person he metHe taught and exemplified Segre the required qualities for anyone studying science “working ones head, honesty, patience, stamina,

precision, and devotion”

High School

He moved to Rome for high school

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

He would rather learn in a very thorough way than briefly learning multiple topic...

especially in for physics class

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”

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

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

Attending this conference persuaded him switch from engineering to physics

College

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

International Physics Conference at Como, 1927.Emilio is at the far left. (Lawrence Berkeley Laboratory)

Emilio would publish a few papers concerning different aspects of physics closely related to Fermi’s studies

One paper contained results of a often quoted paper that was done later done, in more detail, by Eugene Wigner and Victor Weisskopf

Many started off with Fermi explaining quantum ideas and theories leaving Emilio to find applications of them

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

Fermi never allowed Emilio or any other student to publish a paper containing insignificant

results

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

At the Berkeley Lab, Emilio would discover element 43 (technetium), 85

(astatine), and Plutonium 239

‣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

Through Fermi, Emilio would help in the Manhattan Project in Los Alamos

‣Plutonium 239 was eventually used in the Trinity test and later “Fat Man” (the atomic bomb

dropped over Nagaski)

M. Stanley Livingston and Ernest O. Lawrence with the 27-inch cyclotron(Lawrence Berkeley Laboratory)

First atomic bomb explosion at Jornada del Muerto near Alamogordo onJuly 16, 1945. (Los Alamos Scientific Laboratory)

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

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 measuredSegre’s teams decided on momentum and velocity

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.”

His team expected to see the signature star image of an annihilation event if an the detected particle was actually an antiproton

The experiment

The experiments began the first week of August 1955 and lasted until mid September

Antiproton Emulsion Star, 1955.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.)

“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.”

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

Sources

Used for the information of his childhood and life after the nobel prize

For the explanation of the Dirac equations

For information on his nobel prize winning experiment

For information of Los Alamos & the atomic bomb

For information on the atomic bomb and discovery of the anti proton

The colored pictured was from http://www.lbl.gov/Science-Articles/Archive/sabl/2005/October/01-antiproton.html

A mind always in motion: the autobiography of Emilio Segrè

Day of Trinity by Lamont, Lansing 1965, 1st ed

From x-rays to quarks: modern physicists and their discoveries

http://quantummechanics.ucsd.edu/ph130a/130_notes/node45.html

http://www.lbl.gov/Science-Articles/Archive/sabl/2005/October/01-antiproton.html

All pictures except for the colored picture on slide 13 came from A mind always in motion: the autobiography of Emilio Segrè