CHARMONIUM SPECTROSCOPY FROM RADIATIVE DECAYS OF THE J/PSI AND PSI'.

摘要

The Crystal Ball NaI(Tl) detector was used to study the photon spectra from the following inclusive charmonium decays:; e('+)e('-) (--->) J/PSI(3095) (--->) GAMMA + Hadrons; e('+)e('-) (--->) PSIPRIME(3684) (--->) GAMMA + Hadrons; Data were collected at the Stanford Linear Accelerator Center's electron-positron colliding beam machine, SPEAR, intermittently over a two and half year period, beginning at the end of 1978. The Cystal Ball detector consists of a highly segmented array of 732 NaI(Tl) crystals (16 radiation lengths) covering about 98% of 4 pi steradians, and is used to measure the photon energies, directions, and lateral shower distributions. Centrally located spark and proportional chambers are used for charged particle recognition. As a result, this detector is excellently suited for studying the radiative transitions among the charmonium family of states: (i) from PSIPRIME(3684) to the triplet P states, CHI(3415), CHI(3510), and CHI(3550); (ii) from PSIPRIME(3684) and J/PSI(3095) to the singlet S state ETAc(2984); and (iii) from PSIPRIME(3684) to the radially excited singlet S state ETAc'(3592).; The analysis of 1,800,000 PSIPRIME(3684) and 2,200,000 J/PSI(3095) decays yields the following spectrum of states: CHI0(3418), CHI1(3512), CHI2(3558), ETAc(2984), and ETAc'(3592), each with a (+OR-)4 MeV error on its mass. The branching ratios are measured to be: B(PSIPRIME(3684)(--->)GAMMA+CHIJ) = (9.9(+OR-)0.5(+OR-)0.8)%, (9.0(+OR-)0.5(+OR-)0.7)%, and (8.0(+OR-)0.5(+OR-)0.7)%, for J = 0, 1, 2, respectively; B(PSIPRIME(3684)(--->)GAMMA+ETAc) = (0.28(+OR-)0.06)% and B(J/PSI(3095)(--->)GAMMA+ETAc) = (1.27(+OR-)0.36)%; and B(PSIPRIME(3684)(--->)GAMMA+ETAc') = (0.5-1.2)% at the 90% confidence level. Values for the natural line widths are obtained: Width(CHIJ) = (13.5-20.4) MeV, )GAMMA(+OR-)CHIJ) times B(CHIJ(--->)GAMMA+J/PSI(3095)) were measured for J = 1 and 2 to be: (2.56(+OR-)0.12(+OR-)0.20)% and (0.99(+OR-)0.10(+OR-)0.08)%, respectively. No signal was seen for the J = 0 transition, with an upper limit above its previously measured product branching ratio. The results of this analysis are compared with the predictions of the charmonium models.