C. Schweizer

Phase-shift analysis of d-α elastic scattering between 3 and 43 MeV

Abstract Phase shifts for d-α elastic scattering have been extracted from differential cross sections and the vector and tensor analysing powers of 4He( d , d)4He scattering in the energy range from 3 to 17 MeV. The angular momenta were restricted to L ≦ 4 and mixing parameters e1 and e2. Good fits could be obtained to nearly all the experimental data analysed. The total reaction cross section and polarization-transfer coefficients were predicted and compared with the measured data; satisfactory agreement was found within the experimental errors. Evidence for a new resonance was found between 11 and 15 MeV.

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.

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.

A high-efficiency polarimeter for the measurement of the deuteron tensor polarization t20inπ+-d scattering

Abstract We describe the design and the calibration of a high-efficiency polarimeter which is sensitive to the deuteron tensor polarization t 20 and capable of working in a high background. The polarimeter is based on the 3 He(d,p) 4 He reaction, calibrated in the energy range between 10 and 36 MeV; it has an average efficiency of 0.7 × 10 −4 and an average analyzing power of T 20 = −0.5. The use of this polarimeter to measure the tensor polarization t 20 of the recoil deuterons in π + -d elastic scattering is described.

Evidence for dibaryon resonances from the measurement of the tensor polarization t20 in π+−d scattering

The tensor polarization t20 of π+−d elastic scattering has been measured at 117 MeV, 134 MeV, 142 MeV and 151 MeV as a function of scattering angle. While at 134 MeV a strong and oscillatory behaviour prevails over the angular range measured (100−180° c.m.), a considerable flattening of this structure is observed at 117 MeV and 151 MeV. This energy dependence and other observations are believed to manifest evidence for the presence of nonconventional dynamics in this energy region.