Cecil Powell - Collected Quotes

"Coming out of space and incident on the high atmosphere, there is a thin rain of charged particles known as the primary cosmic radiation." (Cecil Powell, "The Cosmic Radiation", [Nobel lecture] 1950)

"For the investigation of the cosmic radiation, it is necessary to solve two principal technical problems: First, to detect the radiation, to determine the masses, energy and transformation properties of the particles of which it is composed, and to study the nuclear transmutations which they produce. Second, to develop methods of making such observations throughout the atmosphere and at depths underground." (Cecil Powell, "The Cosmic Radiation", [Nobel lecture] 1950)

"In the first class are found the trigger mechanisms such as the Geiger counter and the scintillation counter. Such devices record the instants of pas sage of individual particles through the apparatus. Their most important advantages are (a) that they allow observations to be made of great statistical weight; and (b) that the relationship in time of the instants of passage of associated particles can be established. With modern instruments of this type, the time interval between the arrival of two charged particles can be  measured even although this is as small as one or two hundredths of a micro second. These devices have made possible contributions of the greatest importance to our knowledge of the subject, and they have proved especially valuable when the nature of the physical processes being studied has been well understood." (Cecil Powell, "The Cosmic Radiation", [Nobel lecture] 1950)

"In the second class of detectors are the devices for making manifest the tracks of particles; namely, the Wilson expansion chamber and the photo graphic plate. These instruments have the particular advantage, amongst others, that they allow a direct and detailed insight into the physical pro cesses which accompany the passage of charged particles through matter. On the other hand, it is arduous to employ them to obtain observations of great statistical weight. The two classes of instruments thus provide complemen tary information, and each has made a decisive contribution." (Cecil Powell, "The Cosmic Radiation", [Nobel lecture] 1950)

"The detailed study of the 'mass spectrum' of the incoming nuclei has an important bearing on the problem of the origin of the primary particles; but it is complicated by the fact that, because of their large charge, the particles rapidly lose energy in the atmosphere by making atomic and nuclear collisions." (Cecil Powell, "The Cosmic Radiation", [Nobel lecture] 1950)

"Today the study of the cosmic radiation is, in essence, the study of nuclear physics of the extreme high-energy region. Although the number of in coming particles is very small in comparison with those which are produced by the great machines, most of them are much more energetic than any which we can yet generate artificially; and in nuclear collisions they produce effects which cannot be simulated in the laboratory. The study of the resulting transmutations is therefore complementary to that which can be made at lower energies with the aid of the cyclotrons and synchrotrons." (Cecil Powell, "The Cosmic Radiation", [Nobel lecture] 1950)

"We are only at the beginning of our penetration into what appears to be a rich field of discovery. Already, however, it seems certain that our present theoretical approach has been limited by lack of essential information; and that the world of the mesons is far more complex than has hitherto been visualized in the most brilliant theoretical speculations. The fast protons and α-particles generated by the cyclotrons are not sufficiently energetic to pro duce these more massive mesons, but this may become possible when the proton synchrotrons now under construction come into operation." (Cecil Powell, "The Cosmic Radiation", [Nobel lecture] 1950)