A STUDY OF PROPERTIES OF AN IONIZATION SPECTROMETER WITH 10-GEV/C 20.5-GE V/C AND 28-GEV/C INCIDENT PROTONS

Results of calibration measurements of an ionization spectrometer with 10, 20.5 and 28 GeV/c protons are presented. An ionization spectrometer has been employed in several successful balloon flights in combination with spark chambers and different target materials to study high energy cosmic rays. A brief description of the apparatus is given along with details of the balloon flights as well as the exposures at the Brookhaven AGS. The calibration measurements show that it is possible to measure the energy of high energy particles with an ionization spectrometer which is only three interaction lengths deep. A linear dependence has been found to exist between the primary energy and the mean of the measured ionization loss, as well as between primary energy and the mean of the maximum of the measured ionization loss for particles whose first interaction was in the spectrometer. However, this linear relationship does not hold for particles which undergo their first interaction in a target above the spectrometer. For incident protons which interact in the top layer of the spectrometer, the accuracy of the energy determination is +60% and -30%; +50% and -30%; +50% and -25%; at 10, 20.5 and 28 GeV/c, respectively. An attempt has been made to simulate alpha-particle interactions in the spectrometer by using combinations of separate proton events. It is shown that the accuracy of the energy determination for these simulated alpha particles is +50% and -28%; +44% and -26%; +44% and -25%, respectively, for kinetic energies of 9, 19.5 and 27 GeV/nucleon. © 1969.