ULTRAHIGH-ENERGY COSMIC-RAY COMPOSITION FROM SURFACE AIR SHOWER AND UNDERGROUND MUON MEASUREMENTS AT SOUDAN-2

The Soudan 2 experiment has performed time-coincident cosmic ray air shower and underground muon measurements. Comparisons to Monte Carlo predictions show that such measurements can make statistically significant tests of the primary composition in the knee region of the cosmic ray spectrum. The results do not support any significant increase in the average primary mass with energy in the range of similar to 10(4) TeV per nucleus. Some systematic uncertainties remain, however, particularly in the Monte Carlo modeling of the cosmic ray shower

PROTON ELECTROMAGNETIC FORM-FACTORS IN THE TIME-LIKE REGION FROM 8.9 TO 13.0 GEV(2) RID C-5223-2009

Cross sections for the reaction ppBAR --> e+e- have been measured at s = 8.9, 12.4, and 13.0 GeV2. The cross sections have been analyzed to obtain the proton electromagnetic form factors in the timelike region. We find that G(M)(q2) is-proportional-to q-4alpha(s)2(q2) for q2 greater-than-or-equal-to 5 (GeV/c)2

STUDY OF THE ANGULAR-DISTRIBUTION OF THE REACTION (P)OVER-BARP-]CHI-C2-]J/PSI-GAMMA-]E+E-GAMMA RID C-5223-2009

We report on a study of the angular distribution in the reaction ppBAR --> chi(c2) --> J/psi gamma --> e+e-gamma. Using a sample of 1904 events, we find that the contribution of helicity zero in the formation process is B-0(2) < 0.22 (90% C.L.), and that the normalized quadrupole amplitude in the radiative decay is a2 = -0.14 +/- 0.06. The normalized radiative decay octupole amplitude a3 is found to be consistent with zero

PROTON ELECTROMAGNETIC FORM-FACTORS IN THE TIME-LIKE REGION FROM 8.9 TO 13.0 GEV(2) RID C-5223-2009

Cross sections for the reaction ppBAR --> e+e- have been measured at s = 8.9, 12.4, and 13.0 GeV2. The cross sections have been analyzed to obtain the proton electromagnetic form factors in the timelike region. We find that G(M)(q2) is-proportional-to q-4alpha(s)2(q2) for q2 greater-than-or-equal-to 5 (GeV/c)2

STUDY OF THE CHI-1 AND CHI-2 CHARMONIUM STATES FORMED IN (P)BAR-P ANNIHILATIONS

We report on a study of the chi-1(P-3(1)) and chi-2(P-3(2)) states of charmonium formed in antiproton-proton annihilations. An energy scan through the resonances, performed with a very narrow momentum-band beam of antiprotons intersecting a hydrogen jet target, enables us to perform very precise measurements of the mass and the total width of the two resonances. From a sample of 513-chi-1 and 585-chi-2 events, we find M(chi-1) = (3510.53 +/- 0. 13) MeV/c2, M(chi-2) = (3556.15 +/- 0.14) MeV/c2, GAMMA(chi-1) = (0-88 +/- 0.14) MeV and GAMMA(chi-2) = (1.98 +/- 0.18) MeV. From our measurement of the quantity GAMMA(R --> ppBAR) X BR(R --> J/psi-gamma) x BR(J/psi --> e+ e-), using known branching ratios, we obtain GAMMA(chi-1 --> ppBAR) = (69 +/- 13) eV and GAMMA(chi-2 --> ppBAR) = (180 +/- 31) eV