J. Ulbricht

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.

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.

A study of the dimensional stability of the AMS silicon tracker

The Alpha Magnetic Spectrometer (AMS) is designed as an independent module for installation on the International Space Station (ISS) for an operational period of 3 years. The AMS is the first cosmic ray spectrometer equipped with a large area silicon tracker . A preliminary version of the detector was flown on the NASA space shuttle Discovery during June 2–12, 1998. Results for the dimensional stability of the silicon tracker planes based on the flight data, and the metrology data recorded before and after the flight, are presented.

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.

The L3 vertex detector: design and performance

Abstract The L3 vertex detector is comprised of the time expansion chamber (TEC), the Z -chamber and a layer of plastic scintillating fibers. The TEC has shown a high spatial resolution and an excellent multi-track reconstruction capability at LEP luminosity. The Z -chamber provides information about the z -coordinates of the tracks and the fibers are used for calibrating the drift velocity with a high precision. A description of the L3 vertex detector, its readout and data acquisition and its performance during the 1990 LEP running period is presented in this paper.

A silicon microstrip tracker in space: Experience with the AMS silicon tracker on STS-91

SummaryThe Alpha Magnetic Spectrometer (AMS) is designed as an independent module for installation on the International Space Station (ISS) in the year 2003 for an operational period of three years. The principal scientific objectives include the searches for antimatter and dark matter in cosmic rays. The AMS tracker uses silicon microstrip sensors to reconstruct charged-particle trajectories. A first version of the AMS, equipped with 2.1 m2 of silicon sensors and a permanent magnet, was flown on the NASA space shuttle Discovery duringJune 2–12, 1998. In this contribution, we describe the detector and present results of the tracker performance duringthe flight.

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.