Luis Walter Alvarez <13 June 1911 - September 1, 1988) was an American experimental physician, inventor and professor who was awarded the Nobel Prize in Physics in 1968. The American Journal of Physics commented, "Luis Alvarez is wrong one of the most brilliant and productive experimental physicists of the twentieth century. "
After receiving his PhD from the University of Chicago in 1936, Alvarez worked for Ernest Lawrence at the Radiation Laboratory at the University of California at Berkeley. Alvarez designed a series of experiments to observe the capture of K-electrons in a radioactive nucleus, predicted by the beta decay theory but has never been observed before. He produced tritium using a cyclotron and measured his lifetime. In collaboration with Felix Bloch, he measured the magnetic moment of the neutron.
In 1940, Alvarez joined the Radiation Laboratory (MIT), where he contributed to a number of World War II radar projects, ranging from early repairs to the identification of friend or enemy (IFF) flare radar, now called a transponder, to a system known as VIXEN to prevent enemy submarines from realizing that they have been discovered by new airborne microwave radars. An enemy submarine will wait until the radar signal gets stronger and then submerge itself, escape the attack. But the VIXEN sends radar signals whose power is the cube distance to the submarine so that when they approach the submarine, the signal - measured by the sub - gets weaker, and the submarine assumes the plane is further away. and not drowning. The most familiar radar system by Alvarez and who has played a major role in aviation, especially in post-war Berlin air transport, is the Ground Controlled Approach (GCA). Alvarez spent several months at the University of Chicago working on a nuclear reactor for Enrico Fermi before coming to Los Alamos to work for Robert Oppenheimer on the Manhattan project. Alvarez works on the design of explosive lenses, and the development of a bursting bridgewire detonator. As a member of the Alberta Project, he observed the Trinity nuclear test of the B-29 Superfortress, and then the Hiroshima bombing of B-29 The Great Artiste .
After the war, Alvarez was involved in the design of a liquid hydrogen bubble chamber that allowed his team to take millions of photos of particle interactions, develop complex computer systems to measure and analyze these interactions, and discover the whole family of new particles and resonance states. This work resulted in him being awarded the Nobel Prize in 1968. He was involved in a project for an Egyptian pyramid x-ray to search for unknown rooms. With his son, geologist Walter Alvarez, he developed the Alvarez hypothesis proposing that the extinction event that wiped out the dinosaurs was the result of asteroid impacts.
Alvarez is a member of JASON's Defense Advisory Group, Bohemian Club, and Republicans.
Video Luis Walter Alvarez
Kehidupan awal
Luis Walter Alvarez was born in San Francisco on June 13, 1911, the second child and the eldest son of Walter C. Alvarez, a physician, and his wife Harriet nà © Ã… © e Smyth, and granddaughter of Luis F. ÃÆ' lvarez, a temporary physician in Spain, then Cuba, and finally the United States, which invented a better method for diagnosing macular leprosy. She has an older sister, Gladys, a younger brother, Bob, and a younger sister, Bernice. Her aunt, Mabel Alvarez, is a California artist specializing in oil paintings.
He studied at Madison School in San Francisco from 1918 to 1924, and later the San Francisco Polytechnic School. In 1926, his father became a researcher at the Mayo Clinic, and his family moved to Rochester, Minnesota, where Alvarez studied at Rochester High School. He always hopes to attend the University of California, but at the instigation of his teacher in Rochester, he went to the University of Chicago, where he received his bachelor degree in 1932, his master's degree in 1934, and a PhD in 1936. As a scholar, Phi Gamma Delta. As a scholar he moved to Gamma Alpha.
In 1932, as a graduate student in Chicago, he found physics there and had a rare opportunity to use the equipment of the legendary physicist Albert A. Michelson. Alvarez also built the Geiger calculating tube equipment arranged as a cosmic ray telescope, and under the supervision of his faculty adviser Arthur Compton, conducted an experiment in Mexico City to measure the so-called East-West effects of cosmic rays. Observing more incoming radiation from the west, Alvarez concluded that primary cosmic rays are positively charged. Compton submitted the resulting paper to Physical Review , with the name Alvarez at the top.
He's an agnostic.
Maps Luis Walter Alvarez
Initial work
Alvarez's sister, Gladys, worked for Ernest Lawrence as part-time secretary, and called Alvarez to Lawrence. Lawrence then invited Alvarez to attend the Century of Progress exhibition in Chicago with him. After completing his oral examination in 1936, Alvarez, now engaged to marry Geraldine Smithwick, asked his sister to see if Lawrence had a job available at the Radiation Laboratory. A telegram soon came from Gladys with a job offer from Lawrence. It started a long relationship with the University of California, Berkeley. Alvarez and Smithwick married in one of the chapels at the University of Chicago and then headed for California. They have two children, Walter and Jean. They divorced in 1957. On December 28, 1958, he married Janet L. Landis, and had two more children, Donald and Helen.
At the Radiation Laboratory he worked with the experimental team Lawrence, supported by a group of theoretical physicists led by Robert Oppenheimer. Alvarez designed a series of experiments to observe the capture of K-electrons in radioactive nuclei, predicted by the beta decay theory but never observed. Using a magnet to wipe out positrons and electrons from their radioactive sources, he designed a special purpose Geiger counter to detect only "soft" X rays from K capture. He published the results in Physical Review in 1937.
When deuterium (hydrogen-2) is bombarded with deuterium, the fusion reaction produces tritium (hydrogen-3) plus proton or helium-3 plus neutrons ( 2 2 H
-> 3 H
p or 3 He < span>
n ). It is one of the most basic fusion reactions, and the foundations of thermonuclear weapons and current research on nuclear fusion are under control. At that time the stability of these two reaction products was unknown, but based on existing theory, Hans Bethe thought that tritium would be stable and helium-3 was unstable. Alvarez proved the opposite by using his knowledge of the details of the 60-inch cyclotron operation. He sets the machine to accelerate double ionized helium-3 atoms and is able to get accelerated ion beams, thus using the cyclotron as a kind of super mass spectrometer. Because accelerated helium comes from deep gas wells that have been millions of years old, the helium-3 component must be stable. After that Alvarez produces radioactive tritium using cyclotron and 2 H
2 H
reaction and measure its lifespan.
In 1938, again using his knowledge of the cyclotron and creating what is now known as the time-of-flight technique, Alvarez created mono-energetic rays from thermal neutrons. With this he initiated a series of long experiments, collaborating with Felix Bloch, to measure the magnetic moment of the neutrons. Their results from ? 0 = 1,93 Ã, Â ± 0,02Ã,? N , published in 1940, was a major advance over previous work.
World War II
Radiation Laboratory
The British Tadal Mission to the United States in 1940 showed to leading American scientists the successful application of magnetron cavities to produce short pulsed radar pulses. The National Defense Research Committee, established just months earlier by President Franklin Roosevelt, created a central national laboratory at the Massachusetts Institute of Technology (MIT) for the purpose of developing military radar microwave applications. Lawrence immediately recruited his best "cyclotroneers", among them Alvarez, who joined this new laboratory, known as the Radiation Laboratory, on November 11, 1940. Alvarez contributed to a number of radar projects, from early improvements to Identification of Friends or Enemies (IFF) radar, now called transponders, to systems known as VIXEN to prevent enemy submarines from realizing that they have been discovered by new air-conditioning radars.
One of the first projects was to build equipment for the transition from the British longwave radar to the new microwave-centimeter-radar radar made possible by magnetron cavities. In working on the Microwave Early Warning system (MEW), Alvarez creates a linear dipole array antenna that not only pushes unwanted holes from the radiation field but can also be scanned electronically without the need for mechanical scanning. This is a first phase-phased antenna, and Alvarez uses it not only in MEW but in two additional radar systems. Antenna allows Eagle precision bombing radar to support precision bombing in bad weather or through the cloud. Completed rather late in the war; although a number of B-29s are equipped with an Eagle and it works well, it's too late to make a lot of difference.
The most familiar radar system by Alvarez and who has played a major role in aviation, especially in post-war Berlin air transport, is the Ground Controlled Approach (GCA). Using Alvarez's dipole antenna to achieve very high angle resolution, the GCA allows ground radar operators to observe special precision displays to guide the landing aircraft to the runway by sending verbal commands to the pilot. The system is simple, straightforward, and works well, even with untrained pilots. It was so successful that the military continued to use it for many years after the war, and it was still used in some countries in the 1980s. Alvarez was awarded the Collier Trophy of the National Aeronautical Association in 1945 "for his outstanding initiative and prominence in the concept and development of Ground Control Approach system for safe plane landing under all weather and traffic conditions".
Alvarez spent the summer of 1943 in England to test GCA, landing planes that returned from combat in bad weather, and also trained the British in the use of the system. While there he met young Arthur C. Clarke, who was a RAF radar technician. Clarke then uses his experience at a radar research station as the basis for the Glide Path novel, which contains a disguised version of Alvarez. Clarke and Alvarez develop long-term friendships.
Manhattan Project
In the fall of 1943, Alvarez returned to the United States with an offer from Robert Oppenheimer to work at Los Alamos on the Manhattan project. But Oppenheimer suggested that he spend the first few months at the University of Chicago to work with Enrico Fermi before coming to Los Alamos. During these months General Leslie Groves asked Alvarez to think of a way for the US to know whether Germany operates any nuclear reactor, and, if yes, where they are. Alvarez suggested that the aircraft could carry a system to detect the radioactive gas produced by the reactor, especially xenon 133. It was flying over Germany, but did not detect radioactive xenon because Germany did not build reactors capable of chain reactions. This is the first idea of ​​monitoring fission products for intelligence gathering. That will be very important after the war.
As a result of his radio work and several months spent with Fermi, Alvarez arrived at Los Alamos in the spring of 1944, slower than many of his contemporaries. The work on the "Little Boy" (uranium bomb) is so remote that Alvarez is involved in the design of "Fat Men" (plutonium bombs). The technique used for uranium, which forces two sub-critical masses together using weapon types, will not work with plutonium because high levels of spontaneous neutrons will cause fission as soon as the two sections are close to each other, so heat and expansion will force a separate system before much energy is released. It was decided to use almost critical plutonium fields and compress them quickly with explosives into a much smaller and denser nucleus, a technical challenge at the time.
To create the symmetrical explosion required to compress the plutonium core with the required density, thirty-two explosive charges should be simultaneously detonated around the spherical core. Using a conventional explosive technique with an explosive cap, progress towards achieving simultaneity into a small, disappointing microsecond fraction. Alvarez directed his graduate student Lawrence H. Johnston to use a large capacitor to send a high-voltage charge directly to each explosive lens, replacing the explosive cap with an exploding bridgewire detonator. The exploding cable blew thirty-two payloads into a few tenths of a microsecond. This discovery is very important for the success of nuclear weapons of explosive type. He also oversees the RaLa Experiment. Alvarez later wrote that:
With modern weapon-grade uranium, the neutron level of the background is so low that terrorists, if they have such material, will have a good chance of producing a high-yield explosion simply by dropping half of the material into the other half. Most people do not seem to realize that if a separate U-235 is near, it is a trivial job to trigger a nuclear explosion, whereas if only plutonium is available, making it explosive is the most difficult technical work I know of.
Back to work with Johnston, Alvarez's last task for the Manhattan Project was to develop a set of calibrated microphones/transmitters to be deployed from an airplane to measure the force of the explosive wave from atomic explosions, allowing scientists to calculate bomb energy. He observed the Trinity nuclear test from B-29 Superfortress which also brought fellow Project Alberta members Harold Agnew and Deak Parsons.
Fly on B-29 Superfortress The Great Artiste in formation with Enola Gay, Alvarez and Johnston measured the effects of the Little Boy bomb blast dropped on Hiroshima. A few days later, again flying in The Great Artiste , Johnston used the same equipment to measure Nagasaki's explosive strength.
Space bubble
Returning to University of California as a full professor, Alvarez has many ideas on how to use his wartime radar knowledge to improve particle accelerators. Although some of these are fruitful, the "big idea" is now coming from Edwin McMillan with the concept of phase stability that causes synchrocyclotron. Improving and extending this concept, Lawrence's team will build the world's largest proton accelerator, Bevatron, which began operating in 1954. Although Bevatron can generate many attractive particles, especially in secondary collisions, this complex interaction is difficult to do. detect and analyze at that time.
Seizing on new developments to visualize the particle traces, made by Donald Glaser and known as bubble spaces, Alvarez realizes the device is just what is needed, if only it can be made to function with liquid hydrogen. The hydrogen nuclei, which are the protons, make the simplest and most desirable target for interaction with the particles produced by Bevatron. He started a development program to build a series of small spaces, and fought for the device for Ernest Lawrence.
The Glaser device is a small glass cylinder ( 1 cm ÃÆ'â € "2 cm ) filled with ether. By suddenly reducing the pressure on the appliance, the liquid can be placed into a super-hot heat, which will boil along the disturbed path of the passing particle. Glaser is able to maintain a superheated state for several seconds before spontaneous boiling occurs. Alvarez's team built 1.5-inch, 2.5-inch, 4-inch, 10-inch and 15-inch chambers using liquid hydrogen, and made of metal with glass windows, so the tracks could be photographed. Space can be cycled in sync with the accelerator beam, images can be taken, and space recompressed in time for the next beam cycle.
The program builds a liquid hydrogen bubble space of nearly 7 feet (2 meters) long, employs dozens of physicists and graduate students along with hundreds of engineers and technicians, takes millions of photo particle interactions, develops computer systems for measuring and analyzing interactions, and discovering new particle families and state of resonance. This work resulted in a Nobel Prize in Physics for Alvarez in 1968, "For a decisive contribution to elementary particle physics, in particular the discovery of a large number of resonance states, made possible through the development of techniques using hydrogen bubble chamber and data analysis.
Scientific Detective
In 1964, Alvarez proposed what is known as the High Altitude Particle Physics Experiment (HAPPE), which was originally conceived as a large superconducting magnet that was brought to a high altitude by a balloon to study the interaction of very high energy particles. In time the focus of the experiment changed on the study of cosmology and the role of particle and radiation in the early universe. This work is a major undertaking, carrying high-altitude detectors with high-altitude balloon flight and high flying U-2 aircraft, and the early predecessors of COBE-born satellite experiments on cosmic background radiation (which resulted in awards from 2006). The Nobel Prize, shared by George Smoot and John Mather.)
Alvarez proposed a Muon tomography in 1965 to search the Egyptian pyramids for an unknown room. Using natural cosmic rays, the plan is to place a splash room, standard equipment in high-energy particle physics today, under the second pyramid of Chephren in a known space. By measuring the level of cosmic ray counting in various directions, the detector will reveal a vacuum in the layered rock structure.
Alvarez assembled teams of physicists and archaeologists from the United States and Egypt, recording equipment was built and experiments carried out, though it was disrupted by the Six Day War of 1967. Starting after the war, the effort continued, recording and analyzing cosmic rays that penetrated until 1969 when Alvarez reported to American Physical Society that no rooms were found in 19% of the pyramid surveyed.
In November 1966 Life published a series of photos of the film that Abraham Zapruder took from the Kennedy assassination. Alvarez, an optician and photoanalysis, became interested in the pictures and began to learn what can be learned from the film. Alvarez pointed out both in theory and experiment that the back flick of the President's head was completely consistent with his shot from behind. He also investigated the timing of shots and shock waves that plagued the camera, and the speed of the cameras, pointing out a number of things photographed or ignored by FBI photo analysts. He produced a paper intended as a tutorial, with informal advice for physicists intending to get to the truth.
Dinosaur extinction
In 1980 Alvarez and his son, geologist Walter Alvarez, along with nuclear scientists Frank Asaro and Helen Michel, "discovered a catastrophe that really shook the Earth and is one of the great discoveries of Earth's history".
During the 1970s, Walter Alvarez conducted geological research in central Italy. There he found outcrops on the canyon walls whose limestone layers included layers above and below the Cretaceous-Paleogene limits. Right on the boundary is a thin layer of clay. Walter told his father that the layer marked where the dinosaurs and many more became extinct and no one knew why, or what the clay was - it was a great mystery and he intended to finish it.
Alvarez has access to nuclear chemists at the Lawrence Berkeley Laboratory and can work with Frank Asaro and Helen Michel, who use neutron activation analysis techniques. In 1980, Alvarez, Alvarez, Asaro, and Michel published a seminal paper proposing an extraterrestrial cause for Cretaceous-Paleogene extinction (later called Cretaceous-Tertiary extinction). In the years following the publication of their article, the clay was also found to contain soot, glass balls, shaken quartz crystals, microscopic diamonds, and rare minerals formed only under large temperature and pressure conditions.
The 1980 paper publication brings criticism from the geological community, and the often fierce scientific debate takes place. Ten years later, and after Alvarez's death, evidence of a large impact crater called Chicxulub was discovered off the coast of Mexico, providing support for the theory. Other researchers later found that the final Cretaceous extinction of dinosaurs may have occurred rapidly in geological terms, for thousands of years, rather than millions of years as had been previously thought. Others continue to study the causes of alternative extinctions such as the increase in volcanism, particularly the large Deccan Traps eruptions that occur around the same time, and climate change, examining fossil records. However, on March 4, 2010, a panel of 41 scientists agreed that the impact of the Chicxulub asteroid triggered mass extinctions.
Flights
In his autobiography, Alvarez said, "I consider myself to have two separate careers, one in science and one in flight, I have found two things that are just as profitable." An important contributor to this is his flying pleasure. He studied flying in 1933, then gained instruments and multi-engine ratings. Over the next 50 years he collected over 1000 hours of flight time, mostly as a pilot in command. He said, "I found some satisfying activities like being a pilot in charge of my passenger's life."
Alvarez made many professional contributions to the airline. During World War II he led the development of various aviation-related technologies. Some of his projects are described above, including the Ground Controlled Approach (GCA) where he was awarded the Collier Trophy in 1945. He also holds a basic patent for radar transponders, for which he grants the US government $ 1 rights.
Later in his career Alvarez served on several high-level advisory committees related to civil and military aviation. These include the Federal Aviation Administration task group on future air navigation and air traffic control systems, the Military Science Advisory Committee, the Aircraft Panel, and a committee that studies how the scientific community can help improve the ability of the United States in the fight against non-nuclear war.
Flight responsibility Alvarez brings many adventures. For example, while working at GCA he became the first civilian to fly with a low approach with his outlook cockpit hampered. He also flew many military aircraft from co-pilot seats, including the B-29 Superfortress and Lockheed F-104 Starfighter. In addition, he survived the accident during World War II as a passenger in Miles Master.
Death
Source of the article : Wikipedia
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