T. Reichelt

Experimental investigation of deuteron photodisintegration in the δ-resonance region

Abstract Differential cross sections for the deuteron photodisintegration process were measured for photon energies between 200 and 440 MeV using the tagged photon beam facility of the Bonn 500 MeV synchrotron. At eight angles between 18° and 145° charged particles were detected simultaneously in time-of-flight spectrometers consisting of scintillation counters. Above the resonance region the measured cross sections agree fairly well with earlier results, whereas there are larger discrepancies at low photon energies.

Measurement of the two-body photodisintegration of3He in the?(1236) resonance region

The3He(γ, p)d reaction has been measured in the photon energy region between 200 MeV and 450 MeV at proton c.m. angles between 20° and 150°.Protons and deuterons were detected in coincidence with two time-of-flight spectrometers consisting of scintillation counters; both particles were identified and their energies and angles were measured.The angular distributions show a strong forward peak. The differential cross sections fall off with increasing photon energy without showing a significant influence of theΔ resonance.

Measurement of the polarization of a pulsed electron beam with a Møller polarimeter in the coincidence mode

Abstract The Moller polarimeter at the Bates Linear Accelerator Center was used to measure the polarization of an 868-MeV electron beam with a duty cycle of 0.8%. Longitudinally polarized electrons in the beam were scattered from polarized atomic electrons in an FeCo foil, and the helicity-dependent scattering asymmetry was measured by detecting both electrons in coincidence with a pair of Cherenkov counters located symmetrically on either side of the beam. From the measured asymmetry, the beam polarization was inferred to be (42.4 ± 1.7 ± 1.2)%, where the first uncertainty is statistical and the second is systematic.

Elastic photoproduction of charged pions on 3He and 3H in the Δ(1232) resonance region

Abstract Photoproduction of charged pions on 3 He and 3 H has been measured in the Δ(1232)-resonance region. Differential cross sections are presented as functions of the photon energy at fixed momentum transfer and compared to experimental data and theoretical calculations.

Measurement of coherent pion-photoproduction on the 3He/3H isodoublet

Abstract Neutral and charged pion-photo production on 3 H and 3 He nuclei have been observed in the Δ (1232) resonance region. Resonance averaged cross-sections are presented as functions of momentum transfer.

Measurement of coherent π0 photoproduction on3He and3H in the resonance region

Neutral pion photoproduction has been measured on3He and3H nuclei in theΔ(1232) resonance region. Resonance averaged cross-sections are presented as a function of momentum transfer and compared to theoretical calculations.

Measurement of the neutron electric form factor via recoil polarimetry

Abstract.The ratio Gen/Gmn of the electric to the magnetic form factor of the neutron has been measured by analyzing the polarization of the recoiling neutron in quasi-elastic scattering of longitudinally polarized electrons from deuterium at the Q2 values of 0.45, 1.15, and 1.47 (GeV/c)2. The experiment has been performed in Hall C of the Thomas Jefferson National Accelerator Facility. With Gmn being known Gen can be deduced. The preliminary results show that the lowest Q2 points follow the Galster parametrization and that the 1.47 (GeV/c)2 point rises above this parametrization.

Electrodisintegration of the deuteron in the Δ-resonance region

Abstract A study of deuteron electrodisintegration has been performed as the first experiment at the new Bonn 3.5 GeV electron strecher and accelerator ELSA. This process was measured at an average four-momentum transfer Q2 = 0.122 (GeV/c)2 in the invariant hadron mass range of 2.02 – 2.30 GeV. The outgoing proton was detected in coincidence with the scattered electron at three different adjustments of the spectrometer (θplab = 44°, 56°, 68°). The measured differential cross sections show the influence of the excitation of the Δ(1232) resonance in the deuteron. The experimental results are compared to theoretical calculations which include meson exchange currents, final-state interactions and isobar currents.

Measurement of the reaction 3H(γ, π−)3He with position sensitive detectors☆

Abstract A solid state detector telescope has been built to detect the recoil nuclei in the reaction 3 H( γ , π − ) 3 He; the differential cross section is presented as a function of photon energy for a fixed momentum transfer of q 2 = 4.2 fm −2 . The quality of the data shows that the detector telescope is also well suited for measuring the coherent π 0 photoproduction.

Coherentπ0 photoproduction on12C,13C and16O in theΔ (1232) resonance region

Abstractπ0 photoproduction has been measured on12C,13C and16O in theΔ-resonance region. By limiting the acceptance of theπ0 spectrometer to small angles (Θ≦10°), only the coherent channel could contribute. The data show a broadening of the resonance width whereas the peak energy remains essentially unchanged. Theoretical calculations give considerably lower values compared with our data.