He was appointed chairman of the freshman admissions committee and chairman of the division of physics, mathematics, and astronomy from until his retirement in Angeles, and Carl found himself helping to support the family. In retrospect, he said that he was amazed that his mother was able to do so well on so little money. Carl married Lorraine Bergman in It was her second marriage. Her three-year-old son Marshall David was immediately adopted by Carl. Another son, David Anderson, was born in Marshall is now a computer mathematician and David is an engineer. The Anderson family lived in San Marino, not far from Caltech.
Lorraine passed away in All of Carl's professional career was at Caltech. He was a teaching fellow —30 , research fellow —33 , assistant professor —37 , associate professor —39 , and a full professor after He retired in and in was made the Board of Trustees professor of physics emeritus. In , when he was awarded the Nobel Prize, he was an assistant professor. He shared the Nobel Prize with Victor Hess, who had first measured cosmic radiation in Carl used half of his money to cover his mother's medical expenses and invested the balance in California real estate.
In his Nobel lecture Carl described how he obtained his first cosmic ray tracks in A preliminary report published in indicated that energies in excess of a billion electron volts were involved, and that approximately equal numbers of positives and negatives appeared in these cosmic ray showers.
Even the relatively low energy positives, those with energy less than mev had the same ionization track density as the negatives. The key photograph had a positive particle entering the plate with 68 mev and leaving it with 28 mev. Had this particle been a proton its range in the gas of the chamber would have been at least ten times smaller than the actual path. Anderson's data from his Pike's Peak and Panama experiments encouraged him to conclude his Nobel lecture as follows:.
These highly penetrating particles, although not free positive and negative electrons, appear to consist of both positive and negative particles of unit electric charge, and will provide interesting material for future study. Within a few months it was obvious that a new particle with mass intermediate between electron and proton was needed to explain the data. Carl enjoyed teaching, and enjoyed research as an individual effort. He was not interested in being part of a large team. His Nobel Prize, of course, exposed him to many calls for public appearances and speeches.
He did not enjoy this exposure. Peter, Minn. Carl was not particularly interested in politics, although he did sign a petition prepared by Tommy Lauritsen of the physics department against the testing of hydrogen bombs. About ten faculty members signed, but the Caltech administration officially stated this was not Caltech policy.
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Apparently, there were no repercussions against any of the signatories. Carl's graduate student Seth Neddermeyer may have registered as a communist at one time, but neither Carl nor Seth played an active role in any political campaign or movement. Outside of his professional interests Carl was most interested in automobiles and auto racing. He was also a radio ham call sign W6KGR. He listed his recreations as "tennis, mountains, desert, music.
He was honored to be seated at a table with the Swedish ambassador's wife on his right, Mrs. Ernest Hemmingway on his left, the President next to Mrs. Hemmingway, and Mrs. George Marshall on the President's right.
Carl recalled the President's comment that this was the greatest gathering of talent at a White House dinner since Thomas Jefferson dined there alone. The dinner was on the same day that Linus Pauling had picketed the White House. In the reception line Mrs.
Kennedy commented to Pauling that she wished he wouldn't picket, because when that happened Caroline would ask, "What has Daddy done wrong now? The period from to was a very fruitful one for particle physics.
Radiation damage in protein crystallography at X-ray free-electron lasers
Not only were new fundamental particles discovered, but they also induced radioactivity and, of course, nuclear fission. Studies of natural radioactivity and of cosmic. Bombarding the atom with high-energy particles or photons broke up the nucleus and produced new nuclei. By most of the great collection of stable and unstable nuclei that we now know had been found. In retrospect Anderson's achievement was due in part to R. Millikan's intuition that the study of cosmic rays was important and that Anderson had the experimental ability to build a superior cloud chamber.
The intellectual climate at Caltech encouraged the young physicist. This was still the period when physics was being done with ''love and string and sealing wax. Anderson's "anti-matter" was the first step that led to an understanding of the atomic nucleus. Science Free positive electrons resulting from the impacts upon atomic nuclei of the photons for Th C".
Millikan, S. Neddermeyer, and W. The mechanism of cosmic ray counter action. With S. Energy spectra of positrons ejected by artificially stimulated radioactive substances. Cloud chamber observations of cosmic-rays at meter elevation and near sea level.here
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Browse All Figures Return to Figure. Previous Figure Next Figure. Journal list menu Journal. However, if Coulomb interactions in the electron beam could be mitigated at this energy, allowing formation of a beam diameter equal to that of the virus, with the same number of incident electrons, the number of electrons scattered in a direct hit rises to about 50 , which may be sufficient to allow orientation-determination, merging of successive shots, phasing of data and reconstruction into a three-dimensional image density map , if background is not limiting.
The use of much higher beam energies, where electric and magnetic forces within the beam tend to cancel, is a field of active research. Simulations Graves, predict that about 20 electrons would actually remain in the focus of a 7 MeV beam at nm diameter, resulting in about electrons elastically scattered by the virus. The greater number of photons scattered than electrons is primarily due to the gain of the X-ray laser, despite the much larger electron scattering cross section.
In both methods, the most challenging experimental difficulty is achieving a high percentage of direct hits on a hydrated sample with a beam diameter about equal to the particle diameter Ekeberg et al. Unlike X-rays, the electron charge results in strong Coulomb repulsion effects in an electron beam which introduces both unwanted additional beam divergence destroying spatial coherence and unwanted additional energy spread Boersch effect, destroying temporal coherence in the beam.
While these effects are negligible at the current densities used in conventional TEM e.
This mode does not depend on stimulated emission or use a cavity as for a conventional optical laser, but does amplify noise fluctuations, and is considered a laser because it provides gain.
Related The Space-Distribution of the Photo-Electrons Ejected by X-Rays
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