K. Elsener

Comparison of a nearly complete pd elastic scattering data set with Faddeev calculations

Abstract Angular distributions of the cross section, analyzing powers and polarization transfer coefficients of pd elastic scattering have been measured at a proton laboratory energy of 10 MeV. Of the 23 determined observables 19 quantities are independent and constitute a nearly complete experiment. They provide information on different aspects of the NN interaction. The data set is compared with Faddeev calculations using an NN interaction in a separable representation. Excellent to satisfactory agreement is observed for most observables. No basic objections could be found for the use of separable potentials, considering the on- and off-shell behaviour and the sensitivity of the measured quantities.

Evidence for N-N off-shell effects in the polarization transfer coefficients of p-d elastic scattering

Abstract Measurements of the polarization transfer coefficients K y y ′ , K x x ′ and K z x ′ for the 2 H( →p , →p ) 2 H elastic scattering at E p = 10 MeV are reported in the angular range between θ cm = 30° and 120°. These second order polarization observables are compared with Faddeev calculations. They depend largely on the details of the S-wave interactions and the results are sensitive to the choice of their form factors, i.e. to properties of the off-shell behaviour.

A set of high efficiency proton polarimeters for proton energies between 2 and 20 MeV

Abstract The design, the calibration and the performance of a set of high efficiency proton polarimeters for double scattering experiments with polarized beams is described. The usable energy range extends from 2 MeV to about 20 MeV. The polarimeters are based on the scattering of protonsfrom 28 Si, 12 C and 4 He. A figure of merit η · A 2 between 0.1 × 10 −5 and 1.3 × 10 −5 is observed. The spectra of the proton detectors show a very small background so that an accurate determination of the polarization of the scattered protons can be obtained.

Investigation of parity violation in 19F

Abstract The parity violating asymmetry Aγ of the radiation from the first excited state of polarized 19F∗ (110 keV) has been measured with particular care to avoid systematical errors and is found to be Aγ = −(4.5 ± 3.6) × 10−5. This value is several times smaller than the predictions of theoretical calculations based on the Weinberg-Salam theory.

Parity nonconservation in 19F nuclei

Abstract The parity nonconserving asymmetry A γ in the decay of polarized 19 F ∗ (110keV) nuclei has been measured. A value of A γ = − (6.83 ± 2.11) · 10 −5 (total error) was found. Systematic errors are extensively investigated and found to be small. The absolute normalization is given by the 19 F ∗ polarization, which is found to be P F = −0.52 ± 0.08 in a separate experiment, using a calibrated Compton polarimeter. The new result A γ ( 19 F) is compared to earlier experiments and recent theoretical calculations. From an analysis including 18 F and 21 Ne results, constraints on the weak meson-nucleon coupling constants ƒ π and h 0 ρ are deduced. Agreement with calculations based on the standard electroweak theory and QCD is found.

A polarimeter for vector- and tensor-polarized deuterons for use in polarization transfer experiments

Abstract The design, calibration and performance of a deuteron polarimeter for general double scattering experiments with polarized beams is described. The polarimeter is based on the 3He(d,p)4 He reaction, and has 25 available detector positions to analyze 2 vector- and 5 tensor-moments simultaneously. It has been calibrated in the energy range between 4 and 12 MeV deuteron energy, without reaching its limiting energies. The relatively high efficiency of approximately 2 × 105 is of particular interest for polarization transfer experiments.

Test of nucleon-nucleon interaction by polarization transfer in the three-nucleon system

Abstract Measurements of three vector-to-vector and seven vector-to-tensor polarization transfer coefficients of the 2 H 1 H elastic scattering at E p = 10 MeV are reported in the angular range between θ cm = 92° and 180°. These second-order observ are compared with Faddeev calculations. It is shown that the vector-to-tensor components depend largely on the details of the N-N P-wave interaction.

New constraints on D-state contributions to the trinucleon wave functions

Abstract Cross-section and polarization data of the 4 He(d, 3 He) 3 H reaction measured at 5 energies have been analysed. The vertex constants for the neutron transfer G n , the proton transfer G p and the asymptotic normalization constant C s 2 , for the S-state of the 3 H wave function have been determined. New constraints on the D- to S-state asymptotic normalization ratio η t , and η 3 He for the triton and 3 He wave functions are obtained from the tensor analyzing powers. The method of the analytic extrapolation in the angular variable to the transfer poles was used. Implications of this method and its application are discussed. Criteria for the reliability of the results are presented. The result of the analysis is C s 2 = 2.95 ±0.15, η t = 0.050 ± 0.006 and η 3 He = 0.035 ± 0.006. The ratio η t / η 3 He shows a significant deviation from unity suggesting a substantial isospin breaking effect.

An intensity and polarization profile monitor for low energy polarized proton beams

Abstract A monitor for polarized proton beams at energies above 3 MeV is described. It provides information on intensity and polarization profiles of the beam as well as on characteristics of beam modulations. Extensive experience with this monitor has been obtained at E p = 5 MeV. Results are discussed in the context of a parity violation experiment using a 5 MeV polarized proton beam. Accurate new measurements of the 12 C( p , p) 12 C analysing power show the usefulness of this monitor at other energies.

Absolute calibration of a compton polarimeter for 110 keV γ-rays

Abstract The absolute calibration of a transmission type Compton polarimeter for 110 keV γ-rays, used in a 19 F ∗ parity violation experiment, is described. The circularly polarized γ-radiation (129 keV) from a cooled 191 Ir source was used. The counting rate asymmetry obtained by reversing the magnetic field in the polarimeter yielded an analyzing power of | A Cp (110 keV)|=(2.53±0.11) × 10 −3 .