Arthur Maghakian - 1995


Inclusive photon differential cross section in proton-antiproton collisions at 1.8 TeV


We now know that the proton is not an elementary particle: it is made out of quarks held together by gluons. But how are the quarks and gluons put together? While still at Yerevan University in Armenia, Arthur Maghakian wondered about the mysteries hidden inside the proton, and understanding the proton structure became his passion and his thesis topic. Otherwise, he is quite a normal person!

How does one look inside the proton? It is quite simple: create a beam of antiprotons, set them in orbit in a giant particle accelerator together with a beam of protons circulating in the opposite direction, accelerate the two beams to exteremely high energies and bring them to a head-on collision. Such collisions recreate conditions that existed close to the time the Universe was born, and like in the beginning, there is light! The collisions between the quarks and gluons of the proton and antiproton create high energy photons (particles of light). By measuring the angle and energy of these photons, one gets a picture of where exactly they come from, a picture of the quark and gluon structure of the proton. Seeing is believing! But unfortunately, since a picture is a thousand words, it cannot be described here. Arthur found some discrepancy from expectations in the energy distribution of the gluons in the proton, which triggered an ongoing intense theoretical debate.

One may ask: what benefits will knowledge of the structure of the proton bring to society? We don't really know, perhaps because we lack people with the foresight of Demokritos, who, when asked by his funding agency about the possible applications of atoms to medicine, he gave two examples: MRI and computerized laser surgery ...but that, he added reluctantly, is still a couple of thousand years away! Anyhow, we already know that at least one person, Arthur, has experienced the joy of discovery, which is the highest reward that comes from knowledge!

Arthur came to America with his parents, who are here today, his sister, and his wife Christina, who as of last year is another physics student in our Lab. A child born to the happy couple while at Rockefeller, Jessica, has already started using computers and, no doubt, one day she will try to find what is inside of what is inside the proton!

Arthur is staying with us for another year to complete a project that he has already started. Mr. President, it is with great pleasure and pride that I present to you Arthur Maghakian for the Degree of Doctor of Philosophy.