Charmonium spectroscopy from radiative decays of the J/psi and psi'
The Crystal Ball NaI(T1) detector was used to study the photon spectra from the following inclusive charmonium decays: e/sup +/e/sup -/ ..-->.. J/psi ..-->.. ..gamma.. + hadrons and e/sup +/e/sup -/ ..-->.. psi' ..-->.. ..gamma.. + hadrons. Data were collected at the Stanford Linear Accelerator Center's electron-positron colliding beam machine, SPEAR. The Crystal Ball detector consists of a highly segmented array of 732 NaI(T1) crystals (16 radiation lengths) covering approx. = 98% of 4..pi.. steradians, and is used to measure the photon energies, directions, and lateral shower distributions. This detector is excellently suited for studying the radiative transitions among the charmonium family of states: (1) from psi' to the triplet P states, chi(3415), chi (3510), chi(3550); (2) from psi' and J/psi to the singlet S state eta/sub c/(2984); and (3) from psi' to the radially excited singlet S state eta'/sub c/(3592). The analysis of 1.8 x 10/sup 6/ psi' and 2.2 x 10/sup 6/ J/psi decays yields the following spectrum of states: chi/sub 0/(3418), chi/sub 1/(3512), chi/sub 2/(3558), eta/sub c/(2984), and eta'/sub c/(3592), each with a +-4 meV error on its mass. The branching ratios are measured to be: B(psi' ..-->.. ..gamma.. chi/sub 0/ /sub 1/ /sub 2/) = (9.9 +- 0.5 +- 0.8)%, (9.0 +- 0.5 +- 0.7)%, and (8.0 +- 0.5 +- 0.7)%, respectively; B(psi' ..-->.. ..gamma.. eta/sub c/) = 0.28 +- 0.06)% and B(J/psi ..-->.. ..gamma.. eta/sub c/) = 1.27 +- 0.36)%; and B(psi' ..-->.. ..gamma.. eta'/sub c/) = (0.5-1.2)% at the 90% confidence level. Values for the natural line widths are obtained: GAMMA(chi/sub 0/ /sub 1/ /sub 2/) = (13.5-20.4) MeV, < 3.8 MeV, (0.85-4.9) MeV, respectively (90% C.L.); GAMMA(eta/sub c/) = 11.5 +4.5/-4.0) MeV; and GAMMA(eta'/sub c/) < 7 MeV (90% C.L.). Cascade product branching ratios B(psi' ..-->.. ..gamma.. chi/sub J/).B(chi/sub J/ ..-->.. ..gamma..J/psi) were measured for J = 1 and 2 to be: (2.56 +- 0.12 +- 0.20)% and (0.99 +- 0.10 +- 0.08)% respectively. No signal was seen for the J = 0 transition.
- Research Organization:
- Stanford Linear Accelerator Center, CA (USA)
- DOE Contract Number:
- AC03-76SF00515
- OSTI ID:
- 6237411
- Report Number(s):
- SLAC-255; ON: DE83011922
- Country of Publication:
- United States
- Language:
- English
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Charmonium spectroscopy from inclusive psi' and J/psi radiative decays
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Related Subjects
645104* -- High Energy Physics-- Particle Interactions & Properties-Experimental-- Strong Meson-Induced Interactions-- (-1987)
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
BOSONS
BRANCHING RATIO
CHARMONIUM
CHI RESONANCES
CHI-3500 RESONANCES
CHI-3550 RESONANCES
DATA
ELECTRON-POSITRON INTERACTIONS
ELEMENTARY PARTICLES
ENERGY SPECTRA
ETA-700 RESONANCES
EXPERIMENTAL DATA
HADRONS
INFORMATION
INTERACTIONS
LEPTON-LEPTON INTERACTIONS
LINE WIDTHS
MASS SPECTRA
MASSLESS PARTICLES
MEASURING INSTRUMENTS
MESON RESONANCES
MESONS
MONTE CARLO METHOD
NAI DETECTORS
NUMERICAL DATA
PARTICLE INTERACTIONS
PARTICLE PROPERTIES
PARTICLE STRUCTURE
PHOTONS
PSI RESONANCES
PSI-3105 RESONANCES
PSI-3695 RESONANCES
QUARKONIUM
RADIATION DETECTORS
RADIATIVE DECAY
RESONANCE PARTICLES
SCINTILLATION COUNTERS
SOLID SCINTILLATION DETECTORS
SPEAR
SPECTRA
STORAGE RINGS
VECTOR MESONS