Some studies of T = 32 states in 17F

Measurements have been made of some parameters of the second and sixth $\text{T =}\text{3}\text{2}$ states in ¹⁷F. For the second state, the resonance energy was found to be E_p = 12.707 ± 0.001 MeV (E_n = 12.550±0.001 MeV), which agrees with and improves on the accuracy of earlier work. For the sixth $\text{T =}\text{3}\text{2}$ state, at E_p = 14.435 MeV, the γ-decay was determined to be predominantly γ₀ with a branch to the first excited state of Γ(γ₁)/Γ(γ₀) ≦ 0.14. Together with other work, this determines J^π to be $\text{3}\text{2}{}^{\mathrm{?}}$. The capture strength is found to be (2J + 1)Γ_pΓ_γ/Γ = 11.4 ± 2.6 eV.     

Observation of a narrow resonance near the pp threshold

Annihilation and elastic cross-sections of $\text{p}$p have been measured between 400 and 850 MeV/c. In both cross-sections a resonance is observed at a mass of 1939 ± 3 MeV. For its natural width τ ? 4 MeV is obtained.     

Evidence for two narrow pp resonances at 2020 MeV and 2200 MeV

From the study of the reaction $\text{π}{}^{\mathrm{?}}\text{p→p}{}_{\mathrm{F}}\text{p}\text{p}\text{π}{}^{\mathrm{?}}$ using a fast proton (p_F) trigger device in the CERN Omega spectrometer, we find evidence for two narrow $\text{p}\text{p}$ states produced mainly in association with a Δ° (1232) and a N° (1520). The statistical significance of each peak is greater than 6 standard deviations. Masses and natural widths of these resonances are respectively M = 2020 ± 3 MeV, Λ₁ = 24 ± 12 MeV and M₂ = 2204 ± 5 MeV, Λ₂ = 16_?16⁺²⁰ MeV. Our data are consistent with a small production of the narrow ～ 1935 MeV resonance already reported. Production cross sections for these new $\text{p}\text{p}$ resonances are given.     

Proton spectra from the 6,7Li(γ,p) 5,6He reactions at Eγ = 60 MeV

The ${}^{\mathrm{6,7}}\text{Li}\text{(γ,}\text{p}\text{)}$ reactions have been investigated for E_γ = 60 MeV. Excitation of residual (1p)^?1 and (1s)^?1 hole states is evident from the proton spectra measured at ?_p = 45°. The data are compared with a theoretical calculation which includes short-range correlations.     

The analyzing power Aγ(θ) for the elastic scattering of 12 MeV neutrons from deuterons

The analyzing power A_γ(θ) was obtained at 10° intervals between 30° (lab) to 120° (lab) for ²H(n, n)²H at 12.0 MeV. The polarized neutron beam employed in the measurement was obtained by using neutrons emitted at 0° from the polarization transfer reaction ${}^2\text{H}\text{(}\text{d}\text{,}\text{n}\text{)}{}^3\text{He}$. The accuracy in the A_γ(θ) values that was achieved ranged from ± 0.006 to ± 0.013. Comparison of the data to A_γ(θ) results obtained at 12 MeV for the charge symmetric reaction ²H(p, p)²H shows that the two A_γ(θ) distributions are equal to within the above accuracy.     

Observation of a KK enhancement at 1.85 GeV in the reaction K−p → KKΛ at 8.25 GeV/c

In a high statistics $\text{(}\text{～150 eV}\text{μb}\text{)}$ bubble chamber experiment on K^?p interactions at 8.25 $\text{GeV}\text{c}$, the study of the reaction K^?p → KKΛ provides evidence for an enhancement in the KK system with a mass of (1850 ± 10) MeV and a width of (80_?30⁺⁴⁰) MeV. Its possible identification with the missing isosinglet of the 3^? nonet is discussed. A K¹$\text{K}$ decay mode is also observed.     

Jψ radiative decays into ππγ and KKγ

The radiative decays of $\text{J}\text{ψ}$ into f/γ, f′γ, ππγ and KKγ have been measured using the double arm spectrometer DASP at DORIS. We find B(J/φ→fγ)=(J/φ→fγ)/(J/φ→all)=(0.9±0.3)×10^?3 to (1.5±0.4)×10^?3 depending on the multi- pole mode of the $\text{J}\text{ψ}$ decay and that $\text{B(}\text{J}\text{/φ→}\text{f}\text{′γ)}\text{B(}\text{J}\text{/γ→}\text{f}\text{γ)?}\text{1}\text{3}$.     

Observation of a narrow pp enhancement at 1940 MeV

A narrow enhancement is observed in $\text{p}\text{p}$ states produced inclusively in proton-proton interactions at 93 GeV. The mass 1940 ± 1 MeV is consistent with that of the S(1936).     

Isomers in the N = 83 nucleus 149Dy

Energy levels in the N = 83 nucleus ¹⁴⁹Dy were studied by the reaction ¹⁵²Gd(α, 7n) at 106 MeV bombarding energy using in-beam γ-ray spectroscopy methods. The measurements identified three isomers in this nucleus, at 1073 keV (13 ± 3 ns), at 2700±150keV (5 μs < T_{$\text{1}\text{2}$} < 0.5 s), and above 3.5 MeV (50 ± 15 ns). The low-lying isomer is interpreted as i_{$\text{13}\text{2}$}. The configuration $\text{27}\text{2}$^?(πh_{$\text{11}\text{2}$}²)₁₀₊ ×vf_{$\text{7}\text{2}$} is suggested for the state at 2.7 MeV.     

Real-to-imaginary ratio of the pp forward elastic scattering amplitude in the momentum range between 180 and 590 MeV/c

The real-to-imaginary ratio of the $\text{p}\text{p}$ forward elastic scattering amplitude has been measured at the LEAR facility of CERN by the Coulomb-nuclear interference method at seven beam momenta between 181 and 590 MeV/c. The ratio is positive at 590 MeV/c, becomes negative below 500 MeV/c, reaches a minimum at 260 MeV/c and then crosses zero again at about 230 MeV/c.     

Analyzing powers and cross sections in elastic p-d scattering at 65 MeV

Analyzing powers and differential cross sections for $\text{p}\text{-}\text{d}$ elastic scattering have been measured at 64.8 MeV. The angular distributions cover center-of-mass angles between 8° and 169°. The relative uncertainties of the analyzing power measurement are typically ± 0.005 at c.m. angles less than 80° and are in general ± 0.015 at the remaining angles. The absolute scale of the analyzing power measurement has an uncertainty of ± 0.013. The data are compared with three-body calculations based on the Faddeev theory. In contrast with the differential cross sections, the analyzing powers could not be reproduced without the D-wave nucleon-nucleon interactions.     

The 2425 keV state in 21Na as a subtreshold resonance in 20Ne (p,γ)21 Na

The high-energy tail of the $\text{J}{}^{\mathrm{\pi }}\text{=}\text{1}\text{2}{}^{\mathrm{+}}$, 2425 keV state in ²¹Na, bound by 7 keV against proton decay, has been observed in the ²⁰Ne (p,γ)²¹Na reaction at E_p=0.5?1.5 MeV. The observed excitation function is consistent with a single-level Breit-Wigner shape with Γ_γ=0.31±0.07 eV at E_x = 2425 keV.     

Measurement of the g-factor and lifetime of the first-excited state of 20O

The g-factor and mean lifetime of the first-excited 2⁺ state at 1.67 MeV in ²⁰O have been determined by means of a plunger set-up. The state was populated by the ³H(¹⁸O, pγ)²⁰O reaction at $\text{E(}{}^{18}\text{O}\text{) = 24.5}\text{MeV}$. The analysis of p-γ anisotropies as a function of flight path of the recoiling ion in vacuum leads to a value for the g-factor of |g| = 0.352±0.015 and to a mean life of τ = 10.7±0.4 ps.     

Measurement of the g-factor and mean lifetime of the 13C(52+1) state

The g-factor and mean life of the $\text{5}\text{2}{}^{\mathrm{+}}{}_1$ state at 3.85 MeV in ¹³C have been determined by a recoil-into-vacuum plunger measurement. The state was populated by the ²H(¹²C, p) reaction at E = 15.0 MeV. The analysis of the time-differential deorientation effect on the p-γ angular correlation leads to a g-factor of $\text{¦g¦ = 0.558 ± 0.015}$. For the mean lifetime a value of τ = 12.2 ± 0.4ps is obtained.     

Large-pT direct photon production and opposite-side photon-hadron correlations in QCD

Direct photon production in p-p, π-p and $\text{p}\text{-}\text{p}$ collisions at large transverse momenta (p_T) is studied in QCD and compared with existing data. Apart from the quark-gluon and quark-antiquark contributions, corrections due to bremsstrahlung of photons (q+q→q+q+γ) and to partons' intrinsic transverse momenta are taken into account. It is shown that p+p→γ+X provides one of the best determinations of the gluon distribution in the proton. Hadron production with an opposite-side large-p_T photon trigger is also studied. It is shown that the difference between the momentum sharing (x_e) distributions of π^?+p→γ+π^±+X and π⁺+p →γ+π^±+X (or of $\text{p}\text{+}\text{p}\text{→γ+π}{}^{\mathrm{\pm }}\text{+}\text{X}$ and p+p→γ+π^±+X) provides a good determinati on of the gluon fragmentation to a pion.     

Analysis of topological cross sections in pp interactions at 22.4 GeVc

The multiplicity distribution for 11558 events in $\text{p}\text{p}$ interactions at 22.4 $\text{GeV}\text{c}$ was analyzed. The average charged multiplicity 〈n_ch〉 for inelastic events was found to be 4.69 ±0.05 and $\text{〈n}{}_{\mathrm{ch}}\text{〉}\text{D=2.04 ± 0.05}$. The early KNO scaling of normalized topological cross sections has been tested.     

An I = 1 enhancement at a mass of 1550 MeV in the (Λπ) and (Σπ)-systems

Evidence is presented for an I = 1 enhancement observed in the reactions K^?p→Λ(Σ)K⁰₁K^±π^? at $\text{4.2}\text{GeV}\text{c}$ inciden momentum. The mass and width of the proposed new Y¹ are, respectively, (1553 ± 7) MeV) and (80 ± 30) MeV. A decay branching ratio $\text{Σπ}\text{(Σπ + Λπ)}\text{= (35 ± 12)\%}$ is also obtained.     

Partial-wave analysis of the reaction K−p → K Δ (1230) in the energy region 1915–2170 MeV

A partial-wave analysis has been carried out on the reaction K^?p → K^?Δ⁺(1230) → → K^?pπ⁰ in the centre of mass energy region 1915–2170 MeV. The ∑(2030) is observed with an amplitude at resonance of 0.16 ± 0.03. Strong formation of the $\text{3}\text{2}{}^{\mathrm{?}}\text{∑(1940)}$ is also indicated.     

Study of pp elastic scattering in the momentum range 374–680 MeV/c

$\text{p}\text{p}$ elastic total and differential cross sections were measured at 17 incident momenta in the range 374–680 MeV/c. No prominent feature was seen in them to clearly indicate the existence of the S-meson. There is, however, a small enhancement at the S-meson mass, which is equivalent to the elastic total cross section of 4.6 ± 2.1 mb. The behavior of the Legendre expansion coefficients of the angular distributions with incident momentum agrees well the predictions of the OBE model of Bryan and Phillips.