A. Itano

Construction of tensor exchange amplitudes in KN and KN CEX reactions

Abstract K + n charge exchange (CEX) polarization data obtained recently by the Saclay group at CERN are supplemented by differential cross-section data and by information on K − p CEX, and used to construct tensor exchange non-flip and flip components T 0 and T 1 of the s -channel helicity amplitudes directly from data at 6 GeV/ c and for | t | ⩽ 0.9. Vector exchange amplitudes are assumed to be known from π N scattering. The sensitivity of solutions to the uncertainties in the input data is examined in great detail. In general we find a unique solution for all t . We observe new features in the t -structure of non-flip and flip amplitudes. Re T 0 Re T 0 have simple zeros at t ≈ −0.45 and t ≈ −0.65. Im T 0 has a dip or a double zero at t ≈ −0.16 and a double zero structure at t ≈ −0.45. Im T 1 has two simple zeros at t ≈ −0.45 and t ≈ −0.70. Violations of weak EXD in both amplitudes correspond to a lower A 2 trajectory by approximately Δα ≈ 0.1. If certain conditions are satisfied by the input data, a discrete ambiguity exists in the solutions for | t | ⩾ 0.55 and this possibility is also carefully examined.

Apparatus for two-body scattering experiments at 6 and 12 GeV/c with the CERN polarized deuteron target

Abstract An apparatus was built for an experiment with the CERN polarized deuteron target measuring the polarization in K + n ↑ → K ° p . The detectors and the available acquisition capacity were simultaneously used to take data on several other reactions.

Polarization measurements in π+ p and K+ p elastic scattering at 6 and 12 GeV/c with the CERN polarized deuteron target

Abstract The polarization in π + p → π + p and K + p → K + p has been measured at 6 and 12 GeV/ c in the four-momentum transfer interval 0.1 ⩽ | t | ⩽ 2.0 (GeV/ c ) 2 by scattering on protons of a polarized deuteron target. Comparison with existing results obtained with polarized proton targets shows good general agreement and no evidence for asymmetry effects due to the presence of the spectator neutron. For K + p elastic scattering polarization the experiment yields improved statistics, especially at 6 GeV/ c

Polarization measurements in K+n charge exchange at 6 and 12 GeV/c

The polarization in K+n↑ → K0p has been measured at 6 and 12 GeV/c in the interval 0.1 < |t| < 1.0 using a polarized deuteron target. The results are compared to predictions from SU(3), exchange degeneracy (EXD) and line reserval, and from various phenomenological models.

Polarization measurement in pion-nucleon charge exchange π+n ↑ → π0p at 6GeV/c

SummaryThe polarization in pion-nucleon charge exchange was measured at 6 GeV/c incident momentum for 0.1 (GeV/c)2 < |t| < 1.6 (GeV/c)2. Using the channel π+ n ↑ → π0p allowed precise measurement of the recoil proton for good rejection of inelastic events. The results are compared with previous experiments using channel π−p ↑ with or without detection of the recoil neutron.RiassuntoÈ stata misurata la polarizzazione nello scambio di carica tra pione e nucleone ad un impulso incidente di 6 GeV/c per 0.1(GeV)2 < |t| < 1.6(GeV/c)2. Usando il canale π+n ↑ → π0p si è arrivati ad una misurazione precisa del protone di rinculo per una buona reiezione di eventi anelastici. Si confrontano i risultati con gli esperimenti precedenti usando il canale π−p ↑ con o senza la rivelazione del neutrone di rinculo.РеэюмеИэмеряется поляриэация в процессе пион-нуклонной переэарядки при начальном импульсе 6ГзВ/с для 0.1 |t| <1.6 (ГзВ/с)2. Испольэование канала π+n ↑ ⇒ π0p поэволяет точно иэмерить протон отдачи для отбрасывания неупругих событий. Полученные реэультаты сравниваются с предыдушими зкспериментами с испольэованием канала π−p ↑ c или беэ детектирования нейтрона отдачи.

Study of Reaction K+N↑ → K+π-P using a Transversely Polarized Deuteron Target

The reaction K+n → K+π-p has been measured at CERN-PS using the CERN transversely polarized deuteron target at 5.98 and 11.85 GeV/c incident momentum. The data are analysed in the dimeson mass region 0.812 ≤ m(K+π-) ≤ 0.972 GeV and momentum transfer 0.1 ≤ |t| ≤ 1.0 (GeV/c)2 with the assumption that only S- and P- waves contribute. We present the first measurement of the 9 target polarization dependent observables. The 5 polarization independent observables are in agreement with existing data. The improved statistics permits verification of additive quark model predictions with better precision.

Measurement of the Reactions K+n → K+π− p and π+n →π+ π −p at 6 and 12 GeV/c on a Transversely Polarized Deuteron Target

The experiment studies the pion production reactions K+n →K+π∓p and π+ n →π+π∓p on neutrons polarized transversely to the beam direction. The events are described by the variables (s, m, t, ψ,θ,φ where s is the center of mass energy squared, t is the four-momentum transfer squared and m is the invariant mass of the (Kπ) or (ππ) system in the final state. The angle ψ defines the normal to the production plane with respect to the direction of the target polarization. The angles (θ, φ) describe the direction of the positive particle in the (K+π−) or (π+π−) rest frame. The analysis is carried out in both the s- and t-channel frames of the dimeson. Information on the amplitudes, at given values of (s, t, m), is contained in the cross sections d2σ/(dtdm) and in the angular distributions d3σ/(dψdθdφ). At dimeson invariant masses of m ≲ l GeV all partial waves with angular momentum J ≥ 2 are small. The eight complex nucleon trans- versity amplitudes describing S- arid P-wave interaction can be determined - except for the absolute phase and one of the relative phases - from the distribution in (ψ, θ, φ) on a transversely polarized target. The missing relative phase can be obtained only by measuring also the recoil nucleon polarization.

Amplitude Analysis in π+n → π+π−p and K+n → K+π−p Reactions at 6 GeV/c

The construction of amplitudes directly from experimental data (i. e. amplitude analysis) provides model independent information on their t-structure and energy dependence. Scattering experiments with polarized beams and/or targets are required to obtain the necessary set of complete data. The amplitude analysis was first possible for πN two-body scattering at 6 GeV/c (1) and it allowed the isolation of p-exchange amplitudes. Later the measurement of K n CEX polarization at 6 GeV/c (2) allowed the construction of A2-exchange amplitudes in KN two-body scattering at 6 GeV/c (3) which showed unexpected features in their t-structure. Similarly motivated experiments in NN scattering (4) revealed large A1-exchange which had been for long assumed to be a negligible contribution.