Martin Lewis Perl facts for kids
Quick facts for kids
Martin Lewis Perl
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| Born | June 24, 1927 New York City, New York
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| Died | September 30, 2014 (aged 87) |
| Nationality | American |
| Alma mater | New York University Tandon School of Engineering and Columbia University |
| Known for | Tau lepton |
| Children | Jed Perl |
| Awards | Nobel Prize in Physics in 1995 |
| Scientific career | |
| Fields | Physics |
| Institutions | University of Michigan Stanford Linear Accelerator Center (SLAC) University of Liverpool |
| Doctoral advisor | I. I. Rabi |
| Doctoral students | Samuel C. C. Ting  |
Martin Lewis Perl (born June 24, 1927 – died September 30, 2014) was an American physicist and chemical engineer. He won the Nobel Prize in Physics in 1995. He received this award for finding a new tiny particle called the tau lepton.
Contents
Life and Career
Martin Perl was born in New York City, New York. His parents, Fay and Oscar Perl, were Jewish immigrants from the Polish area of Russia. His mother was a secretary and bookkeeper. His father sold stationery and started a printing company.
Early Education and Work
In 1948, Perl graduated from Brooklyn Polytechnic Institute. This school is now known as NYU-Tandon. He earned a degree in chemical engineering.
After college, Perl worked for the General Electric Company. He was a chemical engineer in a factory that made electron vacuum tubes. To understand how these tubes worked, he took classes in atomic physics and advanced math. This made him very interested in physics. In 1950, he decided to become a physics student.
University Studies
Perl earned his Ph.D. from Columbia University in 1955. His professor, I.I. Rabi, guided his research. Rabi had won the Nobel Prize in Physics in 1944. Perl's research looked at how sodium atoms behave. He used a special method that Rabi had developed.
After getting his Ph.D., Perl worked at the University of Michigan for eight years. He studied strong interactions, which are forces between tiny particles. He used tools like bubble chambers and spark chambers to study how particles called pions and neutrons interacted with protons. While at Michigan, Perl helped guide Samuel C. C. Ting, who later won the Nobel Prize in Physics in 1976.
Moving to SLAC
Perl wanted to study simpler interactions between particles. So, in 1963, he moved to the Stanford Linear Accelerator Center (SLAC) in California. This center was still being built. He was very curious about the muon, another tiny particle. He wondered why it was so much heavier than an electron but acted almost the same. He also wanted to know why it decayed in a certain way.
Perl decided to look for answers by doing experiments with high-energy charged leptons. He also thought about finding a third type of lepton. He planned to do this by crashing electrons and positrons together.
Later Life and Legacy
Martin Perl was one of 20 American Nobel Prize winners in Physics who signed a letter in 2008. They asked President George W. Bush to provide more money for basic science research. They wanted to help important science groups like the Department of Energy and the National Science Foundation.
Perl passed away on September 30, 2014, at the age of 87. He had a heart attack at Stanford University Hospital. His son, Jed Perl, is a writer and art critic.
Discovery of the Tau Particle
The tau (τ) is a tiny particle, much like an electron. It has a negative electric charge and a spin of one-half. However, it is about 3,477 times heavier than an electron. The tau is part of a group of particles called leptons, which also includes the electron, the muon, and three kinds of neutrinos.
How the Tau was Found
Martin Perl and his team first found the tau particle between 1974 and 1977. They did their experiments at the SLAC-LBL group. They used a new machine at SLAC called SPEAR. SPEAR could smash electrons and positrons together at very high energies. This allowed them to create tau and antitau particles.
The tau particle only lives for a tiny fraction of a second (about 2.9 x 10-13 seconds). This means it decays very quickly, within a few millimeters of where it was created. So, Perl and his team could not see the tau directly. Instead, they found unusual events. They saw an electron and a muon appear, or a positron and an antimuon, but nothing else that they expected.
They observed 64 events where:
- A positron and an electron crashed.
- An electron (or positron) and a muon (or antimuon) appeared.
- At least two other particles were not seen.
They knew there had to be at least two unseen particles because energy and momentum were not balanced with just one. No other known particles like muons, electrons, photons, or hadrons were detected.
Perl and his team suggested that these events were caused by a new pair of particles being created and then quickly decaying:
- A positron and an electron crash.
- They create an antitau and a tau particle.
- The antitau and tau then decay into an electron (or positron), a muon (or antimuon), and four neutrinos.
It was tricky to confirm this, because the energy needed to make the tau pair was similar to the energy needed to make other known particles called D mesons. But later work at DESY-Hamburg and with another detector at SPEAR confirmed the tau's mass and spin.
The symbol τ comes from the Greek word τρίτον (triton), which means "third." This is because the tau was the third charged lepton discovered.
Nobel Prize and Later Career
In 1995, Martin Perl won the Nobel Prize in Physics. He shared the prize with Frederick Reines. The award was given for their important experiments in lepton physics. Perl received half of the prize for finding the tau lepton. Reines received his share for detecting the neutrino.
In 1996, Perl published a book called Reflections on Experimental Science. It included his thoughts, scientific papers, and memories.
He also became a visiting professor at the University of Liverpool. He was on the board of advisors for Scientists and Engineers for America. This group works to support good science in the American government. In 1996, he received the Golden Plate Award from the American Academy of Achievement. In 2009, the University of Belgrade gave him an honorary doctorate degree.
See also
In Spanish: Martin Lewis Perl para niños
- List of Jewish Nobel laureates
