Measurement of the tensor analyzing power A yy in the inelastic scattering of 4.5-GeV/c deuterons on beryllium at an angle of 80 mrad

The tensor analyzing power A _yy and the vector analyzing power A _y for the inelastic scattering of 4.5-GeV/c deuterons on beryllium nuclei at angle of about 80 mrad are measured in the vicinity of baryon-resonance excitation. These new data, presented as a function of t, comply well with the results of previous 4.5-, 5.5-, and 9-GeV/c measurements at zero angle in overlapping regions of t; all available data are described by a unified dependence on |t| upto about 0.9 (GeV/c)². The experimental results are compared with the results of calculations performed within the multiple-scattering model and the model involving omega-meson exchange in the t channel.     

Measurement of the tensor A yy and vector A y analyzing powers of the deuteron inelastic scattering of beryllium at 5.0 GeV/c and 178 mrad

Tensor A _yy and vector A _y analyzing powers in the inelastic scattering of deuterons with a momentum of 5.0 GeV/c on beryllium at an angle of 178 mrad in the vicinity of the excitation of baryonic resonances with masses up to ～ 1.8 GeV/c ² have been measured. The A _yy data are in good agreement with the previous data obtained at 4.5 and 5.5 GeV/c. The results of the experiment are compared with the predictions of the plane-wave impulse approximation and ω meson-exchange models.     

Measurement of the vector and tensor analyzing powers in dp elastic scattering at the energy of 880 MeV

The preliminary results on the angular distributions of the vector A _y and tensor A _yy , A _xx analyzing powers in dp elastic scattering at T _d = 880MeV are presented. A region of center-of-mass system angles from 60° to 140° is covered. The experimental data are compared with the preliminary calculations obtained within framework of different theoretical approaches. The experiment has been performed at the Internal Target Station at Nuclotron within the framework of the program on the study of light nuclei spin structure proposed at JINR (Russia) and RIBF (Japan).     

Angular dependences of the tensor analyzing powers in the dd → 3Hen reaction at intermediate energies

The tensor analyzing powers A _yy, A _xx, and A _xx in the dd → ³Hen reaction at intermediate energies are considered in the framework of the one-nucleon-exchange approximation. Their strong sensitivity to the ³He and deuteron spin structure at short distances is shown.     

Measurement of the absolute n p scattering differential cross section at 194 MeV

We describe a double-scattering experiment with a novel tagged neutron beam to measure differential cross sections for np backscattering to better than +/-2% absolute precision. The measurement focuses on angles and energies where the cross section magnitude and angle dependence constrain the charged pion-nucleon coupling constant, but existing data show serious discrepancies among themselves and with energy-dependent partial-wave analyses. The present results are in good accord with the partial-wave analyses, but deviate systematically from other recent measurements.     

Measurement of analyzing power for proton-carbon elastic scattering in the coulomb-nuclear interference region with a 22-GeV/c polarized proton beam

The analyzing power for proton-carbon elastic scattering in the Coulomb-nuclear interference region of momentum transfer, 9.0x10(-3)<-t<4.1x10(-2) (GeV/c)(2), was measured with a 21.7 GeV/c polarized proton beam at the Alternating Gradient Synchrotron of Brookhaven National Laboratory. The ratio of hadronic spin-flip to nonflip amplitude, r(5), was obtained from the analyzing power to be Rer(5)=0.088+/-0.058 and Imr(5)=-0.161+/-0.226.     

Measurement of the Tensor-Analyzing Power A yy in Deuteron Breakup at 4.5 GeV/c and 80 mr

 The tensor-analyzing power A _yy in inclusive breakup of 4.5 GeV/c deuterons on beryllium has been measured at ∼ 80 mr of the detected proton angle. The analyzing power remains positive up to the highest measured momentum of the proton, that is in definitive contradiction with the predictions of the existing models based on the standard deuteron wave functions. The results suggest that the deuteron structure at short distances may depend on more than one independent variable. E-mail address: ladygin@sunhe.jinr.ru Received October 2, 2001; accepted July 19, 2002     

Measurement of the total photon proton cross section and its decomposition at 200 GeV centre of mass energy

We present a new measurement of the total photoproduction cross section performed with the H1 detector at HERA. For an average centre of mass energy of 200 GeV a value of σ _tot ^λp =165±2±11μb has been obtained. A detailed analysis of the data in adequate kinematic regions enabled a decomposition of the total cross section in its elastic, single diffractive dissociation and remaining non-diffractive parts, based on safe assumptions on the double diffractive dissociation contribution. Supported by the Bundesministerium für Forschung und Technologie, FRG under contract numbers 6AC17P, 6AC47P, 6DO57I, 6HH17P, 6HH27I, 6HD17I, 6HD27I, 6KI17P, 6MP17I, and 6WT87P     

Measurement of theΞ - p elastic cross section at 102 and 135 GeV/c

TheΞ ^- p differential elastic cross section has been measured in the SPS hyperon beam at 102 and 135 GeV/c. In the range 0.012, thet distributions are found to be compatible with the formA exp(Bt) whereB is 7.7±0.4(GeV/c)^?2 at 102 GeV/c and 8.2 ±0.5(GeV/c)^?2 at 135 GeV/c. The corresponding total elastic cross sections areσ _el=4.9±0.7 mb andσ _el=5.6±0.9 mb, respectively. These results are compared with the predictions of phenomenological models.     

Measurement and MIA analysis of the neutron differential cross section and polarization in the α-D break-up at 33 MeV c.m.

Differential cross sections at 0° and 20° and polarizations at 20° have been measured for the ²H(α, n) αp reaction at E_α = 100 MeV and the ⁴He(d, n) αp reaction at E_d = 50 MeV. Data have been analyzed by the Modified Impulse Approximation (MIA). Satisfactory agreement was obtained but some discrepancy remained in the analysis of polarization data.     

Cross section and analyzing powers for the reaction pd→3He + γ at intermediate energies

We report the results of measurements of the differential cross section and analyzing power for the reaction pd → γ³He at six energies in the range 200 < E_p < 500 MeV. The cross-section data are in good agreement with the most recent results for the inverse process assuming detailed balance; thus no evidence for time-reversal violation is inferred. In addition, the shapes of the measured angular distributions are in general overall accord with those measured in the photodisintegration reaction. The data are compared with several theoretical calculations showing inclusion of meson-exchange current contributions to be important in reproducing the measured cross section. The analyzing powers measured at E_p = 500 MeV are not yet explained by microscopic models.     

Measurement of analyzing power for the reaction \vec p + CH_2 at polarized proton momentum of 7.5 GeV/c (ALPOM2 proposal)

An accurate data base for the analyzing power of thick CH₂ analyzers for high energy protons has been at the basis of several research efforts in a number of laboratories. Starting in the late eighties such data were collected at SATURNE in Saclay, and with the Synchrophasotron in Dubna, and led to an extensive program of study of polarization phenomena in pd interaction, either backward elastic scattering or breakup [1–6]. At about the same time it became evident that measuring polarization observables in elastic ep was going to be the best approach to determine the form factors of the proton, G _Ep and G _Mp , as had been predicted by Akhiezer and Rekalo [7].     

Measurement of the proton total reaction cross section for 159Tb, 181Ta and 197Au between 20 and 48 MeV

Proton total reaction cross sections have been measured for the nuclei ¹⁵⁹Tb, ¹⁸¹Ta and ¹⁹⁷Au at seven proton energies between 20 and 48 MeV using an attenuation technique. The experimentally determined energy dependence of the total reaction cross sections is compared with results obtained for black nucleus and optical model calculations.     

Measurement and QCD analysis of the diffractive deep-inelastic scattering cross section at HERA

A detailed analysis is presented of the diffractive deep-inelastic scattering process ep→eXY, where Y is a proton or a low mass proton excitation carrying a fraction 1-x_IP>0.95 of the incident proton longitudinal momentum and the squared four-momentum transfer at the proton vertex satisfies |t|<1 GeV². Using data taken by the H1 experiment, the cross section is measured for photon virtualities in the range 3.5≤Q²≤1600 GeV², triple differentially in x_IP, Q² and β=x/x_IP, where x is the Bjorken scaling variable. At low x_IP, the data are consistent with a factorisable x_IP dependence, which can be described by the exchange of an effective pomeron trajectory with intercept α_IP(0)=1.118±0.008(exp.)^+0.029 _-0.010(model). Diffractive parton distribution functions and their uncertainties are determined from a next-to-leading order DGLAP QCD analysis of the Q² and β dependences of the cross section. The resulting gluon distribution carries an integrated fraction of around 70% of the exchanged momentum in the Q² range studied. Total and differential cross sections are also measured for the diffractive charged current process e⁺p→ν̄_eXY and are found to be well described by predictions based on the diffractive parton distributions. The ratio of the diffractive to the inclusive neutral current ep cross sections is studied. Over most of the kinematic range, this ratio shows no significant dependence on Q² at fixed x_IP and x or on x at fixed Q² and β.     

Measurement of the differential cross section and of the polarization parameter in pp elastic scattering at 200 GeV/c

Data are given for the polarization parameter and for the differential cross section in pp elastic scattering at 200 GeV/c, in the range $\text{0.5 ??t ? 4.0}\text{GeV}{}^2$. The polarization changes sign in the dip region, as already observed at 150 GeV/c.     

Measurement of the differential cross section and the spin-correlation parameters P,A and R in the backward peak of π−p→K0Λ at 5 GeV/c

We present measurements for the baryon-exchange reaction π^?p→ΛK⁰ at 5 GeV/c over the range ?u<2(GeV/c)². The differential cross section is obtained from events produced on a liquid hydrogen target. These data are combined with events produced on a butanol polarized target and the parameters P, A, and R are then determined from an analysis of the decay angular distribution of the forward-going Λ. From our data it is possible to determine the magnitudes and the relative phase of the two invariant amplitudes A′ and B. The consequences for the ratio B/A′ are discussed in detail.