M. Sarmiento

Evidence for ηη resonances in antiproton-proton annihilations at 2950 < s < 3620 MeV

Abstract We present the first high-statistics study of the ηη system over the mass range 1000–3000 MeV/c2. The experiment was performed at the Fermilab Antiproton Accumulator, and the data sample consists of six-photon final states produced in antiproton-proton annihilations at s in the range 2950–3620 MeV. We find evidence for three states with masses 1488 ± 10 MeV/c2, 1748 ± 10 MeV/c2 and 2104 ± 20 MeV/c2 respectively.

Study of the chi(1) and chi(2) charmonium states formed in anti-p p annihilations

We report on a study of the χ1(3P1) and χ2(3P2) 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 χ1 and 585 χ2 events we find Mχ1 = (3510.53±0.13) MeV/c2, Mχ2 = (3556.15±0.14) MeV/c2, Γχ1 = (0.88±0.14) MeV and Γχ2 = (1.98±0.18) MeV. From our measurement of the quantity Γ(R → pp) × BR(R → Jψ → e+ e−), using known branching ratios, we obtain Λ(χ1 → pp) = (69±13) eV and Λ(χ2 → pp) = (180±31) eV.

Longitudinal response functions for 40Ca from quasi-elastic electron scattering

Abstract Longitudinal response functions were extracted from quasi-elastic electron scattering data on 40 Ca at angles of 45.5°, 90°, and 140° with bombarding energies ranging from 130 to 840 MeV and for constant three-momentum transfers of 300, 330, 370, 410 and 450 MeV/ c . Contrary to previously reported results, the present longitudinal response functions show no more than 20% missing strength when compared to the relativistic Fermi gas model. Calculations employing wavefunctions generated from a relativistic Hartree potential and using an effective momentum approximation yield results that are in much closer agreement with the experimental data and indicate essentially no longitudinal suppression.

Precision measurements of antiproton-proton forward elastic scattering parameters in the 3.7 to 6.2 GeV/c region

Abstract Differential cross sections for p p elastic scattering have been measured for very small momentum transfers at six different incident antiproton momenta in the range 3.7 to 6.2 GeV/c by the detection of recoil protons at scattering angles close to 90°. Forward scattering parameters σ T , b , and ϱ have been determined. For the ϱ-parameter, up to an order of magnitude higher level of precision has been achieved compared to that in earlier experiments. It is found that existing dispersion theory predictions are in disagreement with our results for the ϱ-parameter.

Production of the f2 (1520) resonance in antiproton—proton annihilations at s = 2980 and MeV☆

Abstract We present measurements of the 2π0 mass spectrum in proton—antiproton annihilations. The f2 (1520) resonance is strongly produced in the 3π0 channel. Its production along with an η is observed, but strongly suppressed. Other features are seen in the data, including the f2 (1270) and structures at 2000 MeV/c2 and above.

A pp̄ luminosity monitor for Fermilab experiment E760

Abstract The design and performance of the luminosity monitor for Fermilab experiment E760, in which the circulating antiproton beam in the FNAL antiproton accumulator intersects a hydrogen gas-jet target, is described. Absolute luminosity monitoring at the level of ±0.8% (statistical) ±2.1% (systematic) is achieved. The luminosity monitor also enables forward scattering parameters to be measured for momenta in the 3–8 GeV range with greater precision than achieved before.

Evidence for ηη resonances in antiproton-proton annihilations at

Abstract We present the first high-statistics study of the ηη system over the mass range 1000–3000 MeV/c2. The experiment was performed at the Fermilab Antiproton Accumulator, and the data sample consists of six-photon final states produced in antiproton-proton annihilations at s in the range 2950–3620 MeV. We find evidence for three states with masses 1488 ± 10 MeV/c2, 1748 ± 10 MeV/c2 and 2104 ± 20 MeV/c2 respectively.

Charmonium spectroscopy in p̄p annihilations

This paper presents the experimental status of charmonium spectroscopy and describes the technique of cc formation in pp annihilations used by the experiment E760 at Fermilab. Results from 1990 data taking are reported.

Experimental determination of the proton electromagnetic form factor at Q2=12.4(GeV/c)2

The value of the proton form factor in the time‐like region has been determined at Q2=12.4(GeV/c)2. We have selected events pp→e+e− from the data collected in an experiment performed at the Antiproton Accumulator Ring at Fermilab and, assuming the validity of the ‖GE‖≊0 hypotesis, we have found ‖GM‖=.034±.017 and σTOT(pp→e+e−)=10±5pb.

Quasielastic electron scattering from {sup 40}Ca

Differential cross sections for quasielastic electron scattering on {sup 40}Ca have been measured at laboratory scattering angles of 45.5{degree}, 90{degree}, and 140{degree} with bombarding energies ranging from 130 to 840 MeV. Transverse and longitudinal response functions have been extracted for momentum transfers from 300 to 500 MeV/c. Contrary to some previously reported results, the total observed longitudinal strength agrees with the relativistic Fermi gas prediction to within {plus_minus}18{percent}. {copyright} {ital 1997} {ital The American Physical Society}