اما مكتشف البوزيترون وهو نقيض الالكترون فهو
كارل دافيد أندرسن وعلى الرغم انه لا يعرف متى مات ابوه لكننا نعرف ان اباه انفصل عن امه عندما كان كارل في سن 18 عشرة وهي السن التي تيتم فيها معظم المخترعون امثال جوتنبرغ وجيمس واط.





(بالإنجليزية: Carl David Anderson‏)


فلكي وفيزيائي أمريكي من مواليد نيويورك عاش بين سنة 1905-1991م.


إنجازاته
درس أشعة غاما والأشعة الكونية واكتشف سنة 1932م البوزيترون (الإلكترون المضاد) واستطاع هو وآخر (مشاركة) أن يبرهنا على وجود الميزون عمليا.


حياته



كان أستاذا للفيزياء في سنة 1939م بمعهد كاليفورنيا للتكنولوجيا, نال جائزة نوبل سنة 1936ممشاركة مع فيكتور هس.

البوزيترون Positron جُسيم أولي لا يدخل في تكوين المادة العادية، في نواة الذرة والنيوترون، ويعتبر الجسيم المُضاد للإلكترون أو نقيض الإلكترون. وهو يتطابق مع الإلكترون في الصفات والخصائص الفيزيائية كافةً، فيما عدا الشحنة الكهربائية؛ إذ يحمل البوزيترون شحنة كهربائية موجبة مساوية لشحنة الإلكترون، ولكن على عكس الإلكترون الذي يحمل شحنة كهربائية سالبة.، في حال اصطدام البوزيترون بالإلكترون يحدث ما يعرف بإبادة إلكترون-بوزيترون أي يتحولان إلي شعاعين من أشعة جاما. أي يتحولان إلى طاقة ويظهران على هيئة موجتين كهرومغناطيسيتين لهما نفس التردد. والبوزيترون هو اختصار لكلمة (Positive Electron)

Anderson, Carl David
Complete Dictionary of Scientific Biography | 2008 | COPYRIGHT 2008 Charles Scribner's Sons. (Hide copyright information) Copyright

(b. New York, New York, 3 September 1905; d. San Marino, California, 11 January 1991)
antimatter,physics, positron.
Anderson was awarded the Nobel Prize in Physics in 1936 for the discovery of antimatter, in particular the positive electron, or positron. Just one year later, he was promoted to associate professor of physics at the California Institute of Technology (Caltech), in Pasadena, California, and in 1939 he became a full professor.
Winning the Nobel Prize came as a considerable surprise to Anderson. Unbeknownst to him he had been nominated for it by Caltech’s chief administrative officer and unofficial president Robert A. Millikan (himself a physics laureate in 1923), and Anderson had to borrow $500 from Millikan just to be able to go to Stockholm and get his share of the award, which amounted to $20,000. He shared the prize with Victor Franz Hess of the University of Innsbruck, who was honored for his work in cosmic rays.
Anderson was a quiet, unassuming man. As a graduate student at Caltech, he signed up to take a course in quantum theory from the theoretical physicist J. Robert Oppenheimer, who was then dividing his time between the physics departments at Caltech and the University of California, Berkeley. About forty people were following the course. Oppenheimer, who was not yet the eloquent speaker he would later become, would mumble his way through lectures, writing a squiggle, or part of an equation, on whatever part of the board happened to be handy. It was all too much for Anderson, who went to see Oppenheimer to tell him he was dropping the course. Anderson later recalled the incident in his autobiography, reporting that Oppenheimer urged him to stay, promising that by the end of the term “everything will be all right” (Anderson, 1999, p. 18). When he asked why it was so important that he not drop the course, he was told it was because he was the only registered student.
Anderson was born in New York City in 1905, the only child of Carl David Anderson, a chef, and Emma Adolfina Ajaxson, both of whom grew up on farms near Stockholm and came to America around 1900, in their late teens. (Their son, Carl, learned Swedish at home, and was able to converse with the king of Sweden comfortably in that language when he accepted his Nobel Prize in Stockholm at the age of thirty-one.) In 1912 the family moved to Los Angeles, where Anderson attended grade school and Los Angeles Polytechnic High School, from which he graduated in 1923. By then his parents had separated and he continued to live at home with his mother for many years. In 1923 he enrolled at Caltech, hoping to become an electrical engineer, but in his sophomore year a course in modern physics with Ira Bowen turned him into physics major.
Discovery of the Positron. After receiving his BS in 1927, Anderson remained on campus as a graduate student, working under Millikan on the emission of electrons induced by bombarding various gases with x-rays. He received his PhD magna cum laude in 1930 and stayed on at Caltech as a research fellow, working with Millikan on cosmic rays. Initially, Millikan had urged him to go elsewhere to broaden his research experience, and, accordingly, Anderson had applied for and won a National Research Council fellowship to work under Arthur H. Compton at the University of Chicago. But Millikan then had a change of heart and convinced Anderson to stay on at Caltech, where Anderson spent his entire career.
Millikan’s newfound interest in the study of cosmic rays accounted for his sudden determination to hang on to the talented Anderson. Millikan was convinced (inaccurately, as it turned out) that cosmic rays, a term that he himself coined in 1925 for the penetrating radiation bombarding Earth from all directions, were the birth pangs of new elements being formed out in space. In order to prove this hypothesis, he needed accurate measurements of their energies. He established three research efforts at Caltech in the new field, each using a different type of detector: one under Victor Neher using electroscopes, one under William Pickering using Geiger counters, and one under Anderson using cloud chambers in a magnetic field. Anderson’s investigations paid off almost immediately, but not exactly as Millikan had foreseen.
Anderson built his magnetic cloud chamber (designed entirely by him) in the Guggenheim Aeronautical Laboratory on the Caltech campus, where the generator that powered the wind tunnel provided enough electricity to handle 600 kilowatts. The giant magnet, which took Anderson many months to build, consisted of eight hundred turns of copper tubing laboriously wound into two coils welded together to carry electrical current and cooling water. In a cloud chamber, a supersaturated vapor is caused, by a sudden change in pressure, to form visible droplets on the track left behind by a fast moving charged particle. A handmade camera inserted in a square hole at one end of the magnetic pole piece allowed Anderson to record the curved tracks of condensation left by an electron or any other charged particle. Incoming cosmic-ray particles entering the field would curve to the left if they were negatively charged or to the right if they were positive. In the very first experiments in 1931 and 1932, Anderson saw the deflected tracks of as many positive as negative cosmic-ray particles. At this time, scientists had identified two elementary particles of matter: negatively charged electrons, and positively charged nuclei. Anderson and Millikan initially disagreed over whether the vivid tracks they observed in Anderson’s much-improved cloud chamber were actually negative charges moving downward (Millikan’s view) or positives moving upward (Anderson’s view), but Anderson finally settled the question by placing a lead plate in the path of the particles. They would have more energy and therefore less curvature before passing through the plate than after, when they would be slower and therefore curve more. On 2 August 1932, these efforts were rewarded by a clear track left by a particle moving upward through the plate and curving to the left, meaning it was positively charged, but with a degree of ionization in the cloud chamber gas that indicated that the particle had the mass of an electron. This event marked the entirely unexpected discovery of the positive electron.
One month later, pushed by Millikan to establish the priority of his findings quickly, Anderson published a brief report on “The Apparent Existence of Easily Deflectable Positives,” in Science; the definitive results and famous photograph (“it’s got to be a positive electron,” Anderson later recalled thinking) appeared in Physical Review in 1933. The physics world expressed skepticism. However, a relativistic theory by the Cambridge University theorist Paul A. M. Dirac, published in 1930, had predicted the existence of a positive electron, and the evidence on Anderson’s photographic plate was unimpeachable. Anderson’s result was soon confirmed by Dirac’s Cambridge colleagues Paul M. S. Blackett and Giuseppe P. S. Occhialini, who in a March 1933 paper in the Proceedings of the Royal Society reported similar results and proposed the mechanism of pair production to account for their existence. They postulated that when an energetic gamma ray was converted into matter, it would emit a negatively charged electron, balanced by Dirac’s positively charged positron (as the positive electron came to be called). Asked once by an interviewer if Dirac’s theory had influenced the direction of his research, Anderson replied, “I don’t know whether the existence of Dirac’s work had any effect at all on the work I was doing. I was looking at the cloud chamber data and going by that.”
James Chadwick reported the discovery of the neutron in 1932. With the neutron and the positron as two new fundamental particles of matter, the physics world suddenly looked considerably more complicated than it had previously seemed, a trend that has continued to the present day.