A method to polarise antiprotons in storage rings and create polarised antineutrons

An intense circularely polarised photon beam interacts with a cooled antiproton beam in a storage ring. Due to spin dependent absorption cross sections for the reaction gamma+antiproton > pi- + antineutron a built-up of polarisation of the stored antiprotons takes place. Figures-of-merit around 0.1 can be reached in principle over a wide range of antiproton energies. In this process antineutrons with Polarisation > 70% emerge. The method is presented for the case of 300 MeV/c cooled antiproton beam

Measurement of Partial-Wave Contributions in pp --> pp pi^0

We report a measurement of the spin-dependent total cross section ratios delta_sigma_T/sigma_tot and delta_sigma_L/sigma_tot of the pp --> pp pi^0 reaction between 325 MeV and 400 MeV. The experiment was carried out with a polarized internal target in a storage ring. Non-vertical beam polarization was obtained by the use of solenoidal spin rotators. Near threshold, the knowledge of both spin-dependent total cross sections is sufficient to deduce the strength of certain participating partial waves, free of any model.Comment: 6 pages, 4 figure

How to measure the parity of the Θ+\Theta^+ in p⃗p⃗\vec p\vec p collisions

Triggered by a recent paper by Thomas, Hicks and Hosaka, we investigate which observables can be used to determine the parity of the $\Theta^+$ from the reaction $\vec p\vec p \to \Sigma^+\Theta^+$ near its production threshold. In particular, we show that the sign of the spin correlation coefficient $A_{xx}$ for small excess energies yields the negative of the parity of the $\Theta^+$. The argument relies solely on the Pauli principle and parity conservation and is therefore model--independent.Comment: References completed, discussion on possible influence of background added; conclusions unchange

Initial singlet and triplet spin state contributions to pp -> pp pi0

The PINTEX facility at the IUCF Cooler ring, dedicated to the study of spin dependence in nucleon-nucleon interactions, has been used to measure polarization observables of the reaction pp -> pp pi0 at beam energies between 325 and 400 MeV. The stored polarized proton beam had spin projections both in the longitudinal and the transverse directions with respect to the beam momentum. We report here on the measurements of the relative transverse and longitudinal spin-dependent cross sections, deltasigma_T/sigma_tot and deltasigma_L/sigma_tot, and how from these observables the initial spin singlet and triplet cross sections are obtained. Considering angular momentum states less or equal to one, the contribution of the Ps partial waves to the cross section can be extracted.Comment: Contribution to PANIC99, XVth Particles and Nuclei International Conference, June 10-16, 1999, Uppsala, Sweden. Latex, 5 pages, 3 figure

Effect of pancreatic and/or renal transplantation on diabetic autonomic neuropathy

Thirty-nine Type 1 (insulin-dependent) diabetic patients were studied prospectively after simultaneous pancreas and kidney (n=26) and kidney grafting alone (n=13) by measuring heart rate variation during various manoeuvers and answering a standardized questionnaire every 6 to 12 months post-transplant. While age, duration of diabetes, and serum creatinine (168.1±35.4 vs 132.7±17.7 mgrmol/l) were comparable, haemoglobin A1 levels were significantly lower (6.6±0.2 vs 8.5±0.3%; p<0.01) and the mean observation time longer (35±2 vs 25±3 months; p<0.05) in the pancreas recipients when compared with kidney transplanted patients. Heart rate variation during deep breathing, lying/standing and Valsalva manoeuver were very similar in both groups initially and did not improve during follow-up. However, there was a significant reduction in heart rate in the pancreas recipient group. Autonomic symptoms of the gastrointestinal and thermoregulatory system improved more in the pancreas grafted subjects, while hypoglycaemia unawareness deteriorated in the kidney recipients. This study suggests that long-term normoglycaemia by successful pancreatic grafting is able to halt the progression of autonomic dysfunction

Analyzing Powers and Spin Correlation Coefficients for p+d Elastic Scattering at 135 and 200 MeV

The proton and deuteron analyzing powers and 10 of the possible 12 spin correlation coefficients have been measured for p+d elastic scattering at proton bombarding energies of 135 and 200 MeV. The results are compared with Faddeev calculations using two different NN potentials. The qualitative features of the extensive data set on the spin dependence in p+d elastic scattering over a wide range of angles presented here are remarkably well explained by two-nucleon force predictions without inclusion of a three-nucleon force. The remaining discrepancies are, in general, not alleviated when theoretical three-nucleon forces are included in the calculations.Comment: 43 pages, 12 figures, accepted for publication by Phys. Rev.

Spin dependence of the antinucleon-nucleon interaction

The status of our present knowledge on the antinucleon-nucleon interaction at low and medium energies is discussed. Special emphasis is put on aspects related to its spin dependence which are relevant for experiments planned by the PAX collaboration. Predictions for the spin-dependent antiproton-proton cross sections sigma_1 and sigma_2 are presented, utilizing antinucleon-nucleon potential models developed by the Juelich group, and compared to results based on the amplitudes of the Nijmegen partial-wave analysis.Comment: 8 pages, 4 figures, to appear in the proceedings of the 19th International Spin Physics Symposium, September 27 - October 2, 2010, Juelich, German

Dependence of pp->pp pi0 near Threshold on the Spin of the Colliding Nucleons

A polarized internal atomic hydrogen target and a stored, polarized beam are used to measure the spin-dependent total cross section Delta_sigma_T/sigma_tot, as well as the polar integrals of the spin correlation coefficient combination A_xx-A_yy, and the analyzing power A_y for pp-> pp pi0 at four bombarding energies between 325 and 400 MeV. This experiment is made possible by the use of a cooled beam in a storage ring. The polarization observables are used to study the contribution from individual partial waves.Comment: 6 pages, 1 table, 4 figures, corrected equations 2 and

Spin correlations in p⃗p⃗→pnπ+\vec{p}\vec{p}\to pn\pi^{+} pion production near threshold

A first measurement of longitudinal as well as transverse spin correlation coefficients for the reaction $\vec{p}\vec{p}\to pn\pi^+$ was made using a polarized proton target and a polarized proton beam. We report kinematically complete measurements for this reaction at 325, 350, 375 and 400 MeV beam energy. The spin correlation coefficients $A_{xx}+A_{yy}, A_{xx}-A_{yy}, A_{zz}, A_{xz},$ and the analyzing power $A_{y},$ as well as angular distributions for $\sigma(\theta_{\pi})$ and the polarization observables $A_{ij}(\theta_{\pi})$ were extracted. Partial wave cross sections for dominant transition channels were obtained from a partial wave analysis that included the transitions with final state angular momenta of $l\leq 1$. The measurements of the ${\vec{p}\vec{p}\to pn\pi^{+}}$ polarization observables are compared with the predictions from the J\"ulich meson exchange model. The agreement is very good at 325 MeV, but it deteriorates increasingly for the higher energies. At all energies agreement with the model is better than for the reaction ${\vec{p}\vec{p}\to pp\pi^{0}}$.Comment: Preprint, 21 pp, submitted to Phys. Rev. C. Keywords: Mesons, Polarization, Spin Correlations, Few body system