El INCLUSIVE SPECTRA OF CHARGED HADRONS FROM ; I , AND iI ' DECAYS

The inclusive charged hadron momentum spectra from the $ and $' decays produced in e+ecoilisions at SPEAR are presented, The data were obtained with a small solid-angle, single-arm magnetic spectrometer with good particle identification abilities centered at 90 degrees with respect to the beams. The particle-separated invariant cross sections are compared with data from e+ecollisions at 6 = 4.8 and 7.3 GeV, obtained with the same spectrometer, in order to observe the difference between hadron production at the resonances and in the continuum. (To be published in Physical Review D) * Work supported in part by the Department of Energy, contract DE-AC03-76SF00515, by the National Science Foundation, contracts ‘PIPS 71-02657 and PHY 76-06642, and by the Istituto Nazionale di Fisica Nucleare. INTRODUCTION AND APPARATUS Both psion production and non-resonant hadron production t in e e annihil ation takeRlace through the one-photon channel; but while away from resonancejhadrons are produced predominantly through the two-quark decays of the vitual photon, most of the hadron decays of the $ are though to proceed through gluons 1 . It is interesting to compare hadron spectra at the $ and I$' with hadron spectra at non-resonant energies. In the paper we shall present inclusive charged hadron spectra for the decay of $ (3095) and 9' (3684) produced in esecollisions, obtained with the Maryland-Pavia-Princeton spectrometer at SPEAR. We shall compare these results to spectra obtained with the same spectrometer at /'? = 4.8 GeV and V% = 7.3 GeV “3 . The experimental apparatus is shown in Figure la and lb. It consisted of a magnetic spectrometer complemented by a central detector surrounding the interaction region, shower counters and hadron filters. The main characteristics of the spectrometer are: . 1) Separation of hadrons from leptons using back-to-back shower counters and hadron filters. 2) Hadron identification using a combinat .ion of a propane-fil ed threshold Cerenkov counter and of a time-of-flight (TOF) system. 3) A large magnetic field integral permitting good momentum The shower counter behind the magnet contained seven radiat on length of resolution. lead sandwiched with five layers of scintillator, each divided vertically into four counters, while the counter on the opposite side of the interaction region consisted of ten radiation lengths of sodium iodide supplemented by seven radiation length of lead-scintillator sandwich. Located behind each shower counter was a hadron filter composec! of 6.8 collision lengths of iron interleaved with three layers of scintillation counters.