C.A. Whitten

A proton and neutron beam polarimeter at SATURNE II

Abstract A beam polarimeter using CH 2 and carbon targets has been used to measure proton and neutron beam polarization in the energy range 0.4–2.8 GeV in one of the beam lines at the SATURNE II accelerator. The analyzing power for np-scattering is calibrated against the known analyzing power for pp-scattering by using the polarized deuteron beam to measure simultaneously the asymmetries for scattering of quasifree protons and neutrons in the deuterons. A low level of systematic errors is achieved by pulse to pulse polarization reversal at the ion source of the accelerator, and by measuring left and right scattering simultaneously. The detailed operation procedure and the beam polarizations measured during all experiments from 1981 to 1984 are presented.

Elastic differential cross sections and analyzing powers for p+40,42,44,48Ca at 0.8 GeV☆

Abstract Differential cross sections and analyzing powers for the elastic scattering of 800 MeV polarized protons from 40,42,44,48Ca are reported. A first-order, spin-dependent KMT optical potential analysis is presented from which the rms radii of the neutron densities are deduced. A comparison of these results with other determinations and with various theoretical predictions is given.

Elastic scattering of 0.8-GeV protons from C12, Ni58, and Pb208

Differential cross sections for elastic scattering of 0.8-GeV protons from /sup 12/C, /sup 58/Ni, and /sup 208/Pb have been measured. Preliminary analysis of the data in terms of the Kerman-McManus-Thaler formalism with spin-dependent nucleon-nucleon amplitudes shows sensitivity to details of proton and neutron matter distributions.

Measurement of the total cross section difference ΔσT(pp) in the energy range from 0.43 to 2.4 GeV

Abstract The SATURNE II polarized proton beam and the Saclay frozen spin polarized proton target were used to measure the total cross section difference Δσ T = −2 σ 1 tot at 26 energies between 0.43 and 2.4 GeV. Here Δσ T is the total cross section difference for transverse beam and target spins parallel and antiparallel, respectively, and σ 1tot is one of spin-dependent terms in the total cross section σ tot . The energy dependence of Δσ T below 1 GeV shows similar structures as for Δσ L . An additional minimum appears at about 1.3 GeV, which involves a structure in singlet spin partial waves.

Study of the (p, np̃) reaction on the isotopes of tin☆

Abstract The cross sections for the (p, np) reaction, where the isobaric analogue state excited in the (p, n) charge exchange reaction decays by proton (p) emission, have been measured for the ten stable isotopes of tin. These cross sections show effects due to the neutron decay channel, decay kinematics, and the nuclear structure of the target ground state.

0.8 GeV p + Pb 208 elastic scattering and the quantity Δ r np

Analyses of 0.8 and 1 GeV p+/sup 208/Pb elastic angular distribution data have obtained neutron-proton root-mean-square radius differences (..delta..r/sub n/p) which are not consistent. Therefore, the 0.8 GeV experiment was repeated using a high resolution spectrometer. The new higher precision data are consistent with the older data, apart from a 15% overall normalization difference. A second order Kerman-McManus-Thaler optical model analysis of the new data, using a model-independent neutron density, yields ..delta..r/sub n/p=0.14 +- 0.04 fm, in good agreement with the most recent result obtained (0.16 +- 0.05 fm) from a similar analysis of the older 0.8 GeV data. In addition, the elastic angular distribution was extended to 42.5/sup 0/ center of mass in order to explore the momentum transfer region from 3.5 to 5.3 fm/sup -1/. Although the familiar diffraction pattern persists to 42.5/sup 0/, it was not possible within the framework of our application of the Kerman-McManus-Thaler optical model to fit the data even qualitatively at the larger momentum transfers.

Measurement of the pp analyzing power Aoono in a large angular region between 0.88 and 2.7 GeV

Abstract The pp analyzing power was measured using the SATURNE II polarized proton beam and the Saclay frozen spin polarized target. The measurements at 0.88 and 1.1 GeV were carried out in the angular region θ CM from 28° to ≅50° and complete our previous measurements from 45 ° to 90°. Above 1.1 GeV the measurements presented here cover both regions, extending from θ CM = 28° (at the lower energies) or θ CM = 18° (at the higher energies) to θ CM > 90°. The shape of the angular distribution A oono ( pp ) = ƒ(θ CM ) changes considerably with increasing energy. The new data show the onset of a characteristic t -dependence of the analyzing power, with a minimum at − t ≅ 1.0 (GeV/ c ) 2 followed by a second maximum at − t ≅ 1.5 (GeV/ c ) 2 . This structure is present at all energies, from kinematic threshold to 200 GeV.

Elastic differential cross sections and analyzing powers for p + 54Fe, 58,64Ni at 800 MeV

Abstract Elastic scattering analyzing powers and differential cross sections for 800 MeV → p + 54Fe, 58,64Ni are reported. An approximately mode-independent technique is used to extract information concerning the neutron density distributions of these nuclei.

Analysis of elastic scattering of 0.8 GeV polarized protons from 116Sn and 124Sn

Abstract Differential cross section and analyzing power data for elastic scattering of 0.8 GeV polarized protons from 116Sn and 124Sn are analyzed in terms of a spin-dependent Kerman-McManus-Thaler formalism. Neutron matter densities and rms radii are deduced with careful attention to sources of error, and found to be in good agreement with Hartree-Fock predictions.

The Movable Polarized Target as a Basic Equipment for High-Energy Spin Physics Experiments at the Jinr-Dubna Accelerator Complex

Abstract A movable polarized proton target is planned to be installed in polarized beams of the Synchrophasotron-Nuclotron complex in order to carry out a spin physics experimental program at Dubna. The project is described and the first proposed experiments are discussed.