W.H.A. Hesselink

Single-spin asymmetries in semi-inclusive deep-inelastic scattering on a transversely polarized hydrogen target

Single-spin asymmetries for semi-inclusive electroproduction of charged pions in deep-inelastic scattering of positrons are measured for the first time with transverse target polarization. The asymmetry depends on the azimuthal angles of both the pion (

Collective bands in even mass Sn isotopes

\phi

Single-spin azimuthal asymmetries in electroproduction of neutral pions in semi-inclusive deep-inelastic scattering

) and the target spin axis (

Hadron formation in deep-inelastic positron scattering in a nuclear environment.

\phi_S

Neutron excitations in even mass Sn nuclei

) about the virtual photon direction and relative to the lepton scattering plane. The extracted Fourier component

High-spin neutron excitations in neutron-deficient even-mass Pb isotopes

\cmpi

Evidence for a Transverse Single-Spin Asymmetry in Leptoproduction of pi+pi- Pairs

is a signal of the previously unmeasured quark transversity distribution, in conjunction with the so-called Collins fragmentation function, also unknown. The Fourier component

PROTON PARTICLE-HOLE STATES AND COLLECTIVE EXCITATIONS IN PB-196

\smpi

Charged particle emission following the absorption of stopped π− in 12C, 59Co and 197Au☆

of the asymmetry arises from a correlation between the transverse polarization of the target nucleon and the intrinsic transverse momentum of quarks, as represented by the previously unmeasured Sivers distribution function. Evidence for both signals is observed, but the Sivers asymmetry may be affected by exclusive vector meson production

The level structure of 156Gd studied by means of the (α, 2nγ) reaction

Abstract Positive parity bands in 112, 114, 116, 118Sn have been excited up to levels with spin and parity Jπ = 12+ using Cd(α, 2nγ)Sn reactions. The experiments consisted of γ-ray excitation function, γ-γ coincidence, lifetime, γ-ray angular distribution, γ-ray linear polarization and conversion electron measurements. The observed bands show strong resemblances with ground-state bands of transitional nuclei in this mass region. It is pointed out that the Jπ = 0+ band-heads originate from 2p-2h excitations in the Z = 50 proton shell. The excitation energies of the band-heads are calculated by means of the macroscopic-microscopic renormalization method. Pair correlations between the 2h and 2p configurations are included separately in a phenomenological way by taking into account the pairing energies of the Cd and Te ground states with respect to the Sn ground state.