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The conventional Wien filter is a device with orthogonal static magnetic and electric fields, often used for velocity separation of charged particles. Here we describe the electromagnetic design calculations for a novel waveguide RF Wien filter that will be employed to solely manipulate the spins of protons or deuterons at frequencies of about 0.1–2 MHz at the COoler SYnchrotron COSY at Jülich. The device will be used in a future experiment that aims at measuring the proton and deuteron electric dipole moments, which are expected to be very small. Their determination, however, would have a huge impact on our understanding of the universe. [ABSTRACT FROM AUTHOR]

Abstract: The polarized ion source at the COSY facility in the research center Jülich, Germany, delivered for first experiments polarized deuterons. Some of the developments for the delivery of vector and tensor-polarized deuterons are presented. For polarized protons injected into COSY a new record for polarization of was achieved. Five different states of deuteron beams with up to vector polarization were delivered for an experiment studying spin manipulation in synchrotrons. [Copyright &y& Elsevier]

The Institut für Kernphysik of the Forschungszentrum Jülich GmbH has been designing and developing a new injector for the cooler synchrotron COSY. To reach the set goal, the projected linac injector will have to be equipped with new ion sources. One ion source will deliver unpolarized; the other polarized H- or D- pulsed beams in the mA range having an energy of 25 keV. Pulses of up to 500 μs in width and repetition rates up to 2 Hz are foreseen. Several arrangements of the ion sources and the low energy beam transport system have been investigated. The principles guiding the layout of the low energy beam transport are discussed. First operational results of the source for unpolarized H- and D- are discussed. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Cross sections of proton-induced nuclear reactions on enriched 86 Sr target were measured by the activation technique up to proton energies of 44 MeV. The isomeric cross-section ratios for 86 m , g Y and 85 m , g Y as a function of projectile energy were deduced from their measured data. The present experimental data for the nuclear reaction products, namely 86 m Y, 86 g + xm Y, 85 m Y, 85 g Y, 84 Rb and 83 Rb were compared with the results of nuclear model calculations using the code TALYS, which combines the statistical, precompound, and direct interactions. In general, the experimental cross-section data as well as the isomeric cross-section ratios are reproduced well by the model calculations, provided the input model parameters are properly chosen and the level structure of the product nucleus is thoughtfully considered. The quality of the agreement between experimental data and model calculations was numerically quantified. For products formed via emission of a light complex particle as well as multi-nucleons (e.g., α and 2p2n), the contribution of the latter process starts increasing when its energy threshold is crossed. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports deuteron vector and tensor beam polarization measurements taken to investigate the systematic variations due to geometric beam misalignments and high data rates. The experiments used the In-Beam Polarimeter at the KVI-Groningen and the EDDA detector at the Cooler Synchrotron COSY at Jülich. By measuring with very high statistical precision, the contributions that are second-order in the systematic errors become apparent. By calibrating the sensitivity of the polarimeter to such errors, it becomes possible to obtain information from the raw count rate values on the size of the errors and to use this information to correct the polarization measurements. During the experiment, it was possible to demonstrate that corrections were satisfactory at the level of 10−5 for deliberately large errors. This may facilitate the real time observation of vector polarization changes smaller than 10−6 in a search for an electric dipole moment using a storage ring. [Copyright &y& Elsevier]

Abstract: The angular distributions of the unpolarised differential cross section and tensor analysing power of the reaction have been measured at an excess energy of 16.6 MeV. The ambiguities in the partial-wave description of these data are made explicit by using the invariant amplitude decomposition. This allows the magnitude of the s-wave amplitude to be extracted and compared with results published at lower energies. In this way, firmer bounds could be obtained on the scattering length of the ηα system. The results do not, however, unambiguously prove the existence of a quasi-bound ηα state. [Copyright &y& Elsevier]

Neutrons are an essential tool in science and research for probing the structure and dynamics of matter from the mesoscale to the picoscale and from seconds to femtoseconds. Responding to this situation, the Jülich Centre for Neutron Science (JCNS) has an ongoing project towards the development and design of compact accelerator driven high brilliance neutron sources using nuclear reactions with low energy protons as an efficient and cost-effective alternative to current low and medium flux reactor and spallation sources [[1]]. The project is to deliver a High Brilliance neutron Source (HBS), where a compact neutron production system and a compact moderator system produce a field of thermal and cold neutrons with high brilliance which can efficiently be extracted into an optimized neutron transport system. In reactor based or spallation neutron sources, typically one single cold moderator is installed, which is designed to provide one specific neutron spectrum, but feeds several instruments that may have different spectral requirements. [Extracted from the article]

We present new measurements of cumulative cross sections for the production of 139 Ce and 149 Tb by proton-induced spallation of tantalum foil targets at different proton energies between 300 and 1700 MeV, using the COSY synchrotron at FZ Jülich. Those measurements are presented in the context of the production of medically-relevant radioisotopes for medical applications. [ABSTRACT FROM AUTHOR]

Abstract New precise unpolarised differential cross sections of deuteron–proton elastic scattering have been measured at 16 different deuteron beam momenta between p d = 3120.17 MeV / c and p d = 3204.16 MeV / c at the COoler SYnchrotron COSY of the Forschungszentrum Jülich. The data, which were taken using the magnetic spectrometer ANKE, cover the equivalent range in proton kinetic energies from T p = 882.2 MeV to T p = 918.3 MeV. The experimental results are analysed theoretically using the Glauber diffraction model with accurate nucleon–nucleon input. The theoretical cross section at T p = 900 MeV agrees very well with the experimental one at low momentum transfers t. There are, however, significant deviations for | t | > 0.2 (GeV / c) 2 that must be investigated further. [ABSTRACT FROM AUTHOR]

The vector ( A y d ) and tensor ( A x x and A y y ) analysing powers in deuteron–proton elastic scattering have been measured in the forward hemisphere at deuteron kinetic energies of T d = 1.2 GeV and 2.27 GeV using the ANKE spectrometer at the COSY storage ring. The results are compared with other experimental data and with predictions made within the framework of Glauber multiple scattering theory. [ABSTRACT FROM AUTHOR]

For the measurement of the electric dipole moment of protons and deuterons, a novel waveguide RF Wien filter has been designed and will soon be integrated at the COoler SYnchrotron at Jülich. The device operates at the harmonic frequencies of the spin motion. It is based on a waveguide structure that is capable of fulfilling the Wien filter condition ( E → ⊥ B → ) by design . The full-wave calculations demonstrated that the waveguide RF Wien filter is able to generate high-quality RF electric and magnetic fields. In reality, mechanical tolerances and misalignments decrease the simulated field quality, and it is therefore important to consider them in the simulations. In particular, for the electric dipole moment measurement, it is important to quantify the field errors systematically. Since Monte-Carlo simulations are computationally very expensive, we discuss here an efficient surrogate modeling scheme based on the Polynomial Chaos Expansion method to compute the field quality in the presence of tolerances and misalignments and subsequently to perform the sensitivity analysis at zero additional computational cost. [ABSTRACT FROM AUTHOR]

Values of the proton analysing power in the p d → He 3 π 0 / H 3 π + reactions at 350–360 MeV per nucleon were obtained by using a polarised proton beam incident on a deuterium cluster-jet target and with a polarised deuteron beam incident on a target cell filled with polarised hydrogen. These results have a much larger angular coverage than existing data. First measurements are also presented of the deuteron vector analysing power and the deuteron–proton spin correlations. Data were also obtained on the deuteron–proton spin correlation and proton analysing power at small angles at 600 MeV per nucleon, though the angular coverage at this energy was much more restricted even when using a deuteron beam. By combining the extrapolated values of the spin correlations to the forward or backward directions with published measurements of the deuteron tensor analysing powers, the relative phases between the two non-vanishing amplitudes were evaluated. [ABSTRACT FROM AUTHOR]

The differential cross section for proton–proton elastic scattering has been measured at a beam kinetic energy of 1.0 GeV and in 200 MeV steps from 1.6 to 2.8 GeV for centre-of-mass angles in the range from 12°–16° to 25°–30°, depending on the energy. A precision in the overall normalisation of typically 3% was achieved by studying the energy losses of the circulating beam of the COSY storage ring as it passed repeatedly through the windowless hydrogen target of the ANKE magnetic spectrometer. It is shown that the data have a significant impact upon the results of a partial wave analysis. After extrapolating the differential cross sections to the forward direction, the results are broadly compatible with the predictions of forward dispersion relations. [ABSTRACT FROM AUTHOR]

The production of non-ϕK+K− pairs by protons at 2.83 GeV kinetic energy on C, Cu, Ag, and Au targets has been investigated by using the COSY-ANKE magnetic spectrometer. The K− momentum dependence of the differential cross section has been measured for laboratory polar angles θK± ≤ 12∘ over the 0.2-0.9 GeV/c range. The comparison of the data with detailed model calculations indicates an attractive K−-nucleus potential of about −60 MeV at normal nuclear matter density at a mean momentum of 0.5 GeV/c. However, this approach has difficulty in reproducing the smallness of the observed cross sections at low-K− momenta. [ABSTRACT FROM AUTHOR]

The charge exchange of vector polarised deuterons on a polarised hydrogen target has been studied in a high statistics experiment at the COSY-ANKE facility at a deuteron beam energy of T d = 726 MeV . By selecting two fast protons at low relative energy E p p , the measured analysing powers and spin correlations are sensitive to interference terms between specific neutron–proton charge-exchange amplitudes at a neutron kinetic energy of T n ≈ 1 2 T d = 363 MeV . An impulse approximation calculation, which takes into account corrections due to the angular distribution in the diproton, describes reasonably the dependence of the data on both E p p and the momentum transfer. This lends broad support to the current neutron–proton partial wave solution that was used in the estimation. [ABSTRACT FROM AUTHOR]

The vector and tensor analysing powers, A y and A y y , of the p d → → n { p p } s charge-exchange reaction have been measured at a beam energy of 600 MeV at the COSY-ANKE facility by using an unpolarised proton beam incident on an internal storage cell target filled with polarised deuterium gas. The low energy recoiling protons were measured in a pair of silicon tracking telescopes placed on either side of the target. Putting a cut of 3 MeV on the diproton excitation energy ensured that the two protons were dominantly in the S 0 1 state, here denoted by { p p } s . The polarisation of the deuterium gas was established through measurements in parallel of proton–deuteron elastic scattering. By analysing events where both protons entered the same telescope, the charge-exchange reaction was measured for momentum transfers q ≥ 160 MeV / c . These data provide a good continuation of the earlier results at q ≤ 140 MeV / c obtained with a polarised deuteron beam. They are also consistent with impulse approximation predictions with little sign evident for any modifications due to multiple scatterings. These successful results confirm that the ANKE deuteron charge-exchange programme can be extended to much higher energies with a polarised deuterium target than can be achieved with a polarised deuteron beam. [ABSTRACT FROM AUTHOR]

The proton analysing power in p → p elastic scattering has been measured at small angles at COSY-ANKE at 796 MeV and five other beam energies between 1.6 and 2.4 GeV using a polarised proton beam. The asymmetries obtained by detecting the fast proton in the ANKE forward detector or the slow recoil proton in a silicon tracking telescope are completely consistent. Although the analysing power results agree well with the many published data at 796 MeV, and also with the most recent partial wave solution at this energy, the ANKE data at the higher energies lie well above the predictions of this solution at small angles. An updated phase shift analysis that uses the ANKE results together with the World data leads to a much better description of these new measurements. [ABSTRACT FROM AUTHOR]

Abstract: The deuteron tensor analysing power of the reaction has been measured at the COSY-ANKE facility in small steps in excess energy Q up to . Despite the square of the production amplitude varying by over a factor of five through this range, shows little energy dependence. This is evidence that the final state interaction causing the energy variation is not influenced by the spin configuration in the entrance channel. The weak angular dependence observed for provides useful insight into the amplitude structure near threshold. [Copyright &y& Elsevier]

Abstract: The transverse spin correlations and in the reaction have been measured for the first time in quasi-free kinematics at the COSY-ANKE facility using a polarised deuteron beam incident on a polarised hydrogen cell target. The results obtained for neutron energies close to 353 MeV and 600 MeV are in good agreement with the partial wave analysis of data on the isospin-related reaction, though the present results cover kinematic regions that are largely absent from existing data sets. [Copyright &y& Elsevier]

Abstract: The charge-exchange break-up of polarised deuterons , where the final diproton system has a very low excitation energy and hence is mainly in the state, is a powerful tool to probe the spin-flip terms in the proton–neutron charge-exchange scattering. Recent measurements with the ANKE spectrometer at the COSY storage ring at 1.6, 1.8, and 2.27 GeV have extended these studies into the pion-production regime in order to investigate the mechanism for the excitation of the isobar in the reaction. Values of the differential cross section and two deuteron tensor analysing powers, and , have been extracted as functions of the momentum transfer to the diproton or the invariant mass of the unobserved system X. The unpolarised cross section in the high region is well described in a model that includes only direct excitation of the Δ isobar through undistorted one pion exchange. However, the cross section is grossly underestimated for low , even when Δ excitation in the projectile deuteron is included in the calculation. Furthermore, direct Δ production through one pion exchange only reproduces the angular dependence of the difference between the two tensor analysing powers. [Copyright &y& Elsevier]

The transverse spin correlations Ax,x and Ay,y have been measured in the dp→pspec{pp}sp- reaction at COSY-ANKE at 353 MeV per nucleon. Here {pp}s denotes a proton-proton pair with low excitation energy, which is dominantly in the ¹S0 state. By measuring three protons in the final state it was possible to extract events where there was a spectator proton pspec so that the reaction could be interpreted in terms of quasifree n p→{pp}sp-. The proton and neutron analyzing powers in this reaction were also deduced from this data set by averaging over the polarizations of the deuteron beam and hydrogen target, respectively. The values of Ay were shown to be consistent with a refined analysis of our earlier results obtained with a polarized proton incident on a deuterium target. Taking these data in combination with our previous measurements of the differential cross sections and analyzing powers in the p p→{pp}s p° reaction, a more robust partial wave decomposition was achieved. Three different acceptable solutions were found, and the only way of resolving this ambiguity without further theoretical input would be through a measurement of the mixed spin-correlation parameter Ax,z. [ABSTRACT FROM AUTHOR]

The pp → ppK⁺K⁻ reaction was measured below the threshold at a beam energy of 2.568 GeV using the COSY-ANKE magnetic spectrometer. By assuming that the four-body phase space is distorted only by the product of two-body final-state interactions, fits to a variety of one-dimensional distributions permit the evaluation of differential and total cross sections. The shapes of the distributions in the Kp and Kpp invariant masses are reproduced only if the K⁻p interaction is even stronger than that found at higher energy. The cusp effect in the K⁺K⁻ distribution at the K°K° threshold is much more clear and some evidence is also found for coupling between the K⁻p and K°n channels. However, the energy dependence of the total cross section cannot be reproduced by considering only a simple product of such pairwise final-state interactions. [ABSTRACT FROM AUTHOR]

Abstract: The PAX Collaboration has successfully performed a spin-filtering experiment with protons at the COSY-ring. The measurement allowed the determination of the spin-dependent polarizing cross section, that compares well with the theoretical prediction from the nucleon–nucleon potential. The test confirms that spin-filtering can be adopted as a method to polarize a stored beam and that the present interpretation of the mechanism in terms of the proton–proton interaction is correct. The outcome of the experiment is of utmost importance in view of the possible application of the method to polarize a beam of stored antiprotons. [Copyright &y& Elsevier]

Abstract: The differential cross section and analysing power of the reaction have been measured at COSY-ANKE at 353 MeV. The final proton pair was detected at very low excitation energy, leading to an S-wave diproton, denoted here as . The angular dependence of both and can be described in terms of s- and d-wave pion production. By using phase information from elastic pp scattering, unique solutions are derived for the corresponding amplitudes only as a result of the combined analysis of both experimental observables. The large d-wave term thus obtained is important for the tests of the current state-of-the-art chiral perturbation theory approach. The amplitudes will also help towards determining the isospin dependence of pion production in nucleon–nucleon collisions with diproton formation. [Copyright &y& Elsevier]

Abstract: In order to test chiral perturbation theory and establish links between p-wave pion production in nucleon–nucleon collisions and low energy three-nucleon scattering, an extensive programme of experiments on pion production is currently underway at COSY-ANKE. The final proton pair is measured at very low excitation energy, leading to an S-wave diproton, denoted here as . By using a deuterium target we have obtained data on the differential cross section and analysing power of the quasi-free reaction at 353 MeV. The spectator proton was either measured directly in silicon tracking telescopes or reconstructed using the momentum of a detected . Both observables can be described in terms of s-, p-, and d-wave pion production amplitudes. Taken together with the analogous data on the reaction, full partial wave decompositions of both processes were carried out. [Copyright &y& Elsevier]

Differential and total cross sections for the pp → ppK+K- reaction have been measured at a proton beam energy of 2.83 GeV using the COSY-ANKE magnetic spectrometer. Detailed model descriptions fitted to a variety of one-dimensional distributions permit the separation of the pp → ppφ cross section from that of non-φ production. The differential spectra show that higher partial waves represent the majority of the pp → ppφ total cross section at an excess energy of 76 MeV, whose energy dependence would then seem to require some s-wave 4>p enhancement near threshold. The non-φ data can be described in terms of the combined effects of two-body final state interactions using the same effective scattering parameters determined from lower energy data. [ABSTRACT FROM AUTHOR]

The production of cp mesons in proton collisions with C, Cu, Ag, and Au targets has been studied via the φ → K+K- decay at an incident beam energy of 2.83 GeV using the ANKE detector system at COSY. For the first time, the momentum dependence of the nuclear transparency ratio, the in-medium &pji; width, and the differential cross section for φ-meson production at forward angles have been determined for these targets over the momentum range of 0.6-1.6 GeV/c. There are indications of a significant momentum dependence in the value of the extracted φ width, which corresponds to an effective φN absorption cross section in the range of 14-21 mb. [ABSTRACT FROM AUTHOR]

The ratios of the cross sections for ϕ-meson production induced by 2.83-GeV protons on Cu, Ag, and Au nuclei to the respective cross section for C nuclei were measured at the ANKE-COSY facility in the momentum range of 0.6-1.6 GeV/ c and the angular range of 0°-8°. The product ϕ mesons were identified by their decay ϕ → K K. The procedure used to separate kaon pairs was described in detail, and all sources of the background and their contribution to the resulting error in the values found for the above cross-section ratios were analyzed. The A dependence of the cross section for ϕ-meson production was shown to obey the A law. The total width of the ϕ meson at a normal nuclear density was extracted from a comparison of the measured cross-section ratios with the results of calculations based on two theoretical models. The resulting width value exceeds substantially both the vacuum width and the width expected in the absence of the nuclear-matter effect on the properties of the ϕ meson. [ABSTRACT FROM AUTHOR]

Abstract: The production of ϕ mesons in the collisions of 2.83 GeV protons with C, Cu, Ag, and Au at forward angles has been measured via the decay using the COSY-ANKE magnetic spectrometer. The ϕ meson production cross section follows a target mass dependence of in the momentum region of 0.6–1.6 GeV/c. The comparison of the data with model calculations suggests that the in-medium ϕ width is about an order of magnitude larger than its free value. [Copyright &y& Elsevier]

For the Time Reversal Invariance experiment at COSY (TRIC) that had been proposed at the Forschungszentrum Jülich a novel technique for measuring total cross sections in internal experiments was developed and the achievable precision of this measuring technique was tested. The experimental idea constitutes a true P-even T-odd null test of TRI. In order to compare to the theoretical upper bound from edm measurements (Haxton and Höring, Nucl Phys A560:469, 1993), the TRI violating observable A y, xz in proton-deuteron forward scattering has to be measured with an accuracy of 10 − 6. An internal TRI experiment can determine the total cross section via the optical theorem by measuring the forward scattering amplitude. In contrast to external experiments, the only calibrated device that is needed is a precise beam current transformer (BCT). The feasibility of an internal TRI experiment was tested at COSY in a measurement of A y, y in p-p scattering, since these values are known. The analysis of the data showed the presence of unexpected large 1/ f noise contributions, which eventually reduced the achievable accuracy by a factor 3. The origin of the 1/ f noise was traced and found to be the Barkhausen noise from the ferrite-core of the BCT. A global weighted fitting technique based on a modified Wiener-Khinchin method was applied to suppress the influence of the 1/ f noise. [ABSTRACT FROM AUTHOR]

Abstract: We discuss polarizing a proton beam in a storage ring, either by selective removal or by spin flip of the stored ions. Prompted by recent, conflicting calculations, we have carried out a measurement of the spin-flip cross section in low-energy electron–proton scattering. The experiment uses the cooling electron beam at COSY as an electron target. The measured cross sections are too small for making spin flip a viable tool in polarizing a stored beam. This invalidates a recent proposal to use co-moving polarized positrons to polarize a stored antiproton beam. [Copyright &y& Elsevier]

Recently published excitation functions in proton-proton ( pp) elastic scattering observables in the laboratory energy range 0.5-2.5GeV provide an excellent data base to establish firm upper limits on the elasticities ηel = Γel/Γtot of possible isovector resonant contributions to the nucleon-nucleon ( NN) system. Such contributions have been predicted to arise from dibaryonic states, with c.m. masses between 2.1-2.9GeV/c2, but have not been confirmed experimentally. A method to determine quantitatively the maximum value of ηel compatible with experimental data is presented. We use energy-dependent phase shift fits to the pp data base to model the non-resonant interaction. Based upon the differential cross-section data measured by the EDDA Collaboration an unbiased statistical test is constructed to obtain upper limits on ηel, that exclude larger values with a 99% confidence level. Results in the c.m. mass range 2.05-2.85GeV/c2 and total widths of 10-100MeV/c2 in the partial waves 1 S 0, 1 D 2, 3 P 0, 3 P 1, and 3 F 3 are presented and discussed. [ABSTRACT FROM AUTHOR]

Excitation functionsAN(plab,Tc.m.) of the analyzing power in elastic proton-proton scattering have been measured in an internal target experiment at the Cooler Synchrotron COSY with an unpolarized proton beam and a polarized atomic hydrogen target. Data were taken continuously during the acceleration and deceleration for proton kinetic energiesTlab (momentaplab) between 0.45 and 2.5 GeV (1.0 and 3.3 GeV/c) and scattering angles 30° ? Tc.m. ? 90°. The results provide excitation functions and angular distributions of high precision and internal consistency. The data can be used as calibration standard between 0.45 and 2.5 GeV. They have significant impact on phase shift solutions, in particular on the spin triplet phase shifts between 1.0 and 1.8 GeV. [ABSTRACT FROM AUTHOR]

We have measured differential cross-sections forelastic scattering with internal fiber targets in the recirculating beam of the proton synchrotron COSY. Measurements were made continuously during acceleration for projectile kinetic energies between 0.23 and 2.59 GeV in the angular range. Details of the apparatus and the data analysis are given and the resulting excitation functions and angular distributions presented. The precision of each data point is typically better than 4%, and a relative normalization uncertainty of only 2.5% within an excitation function has been reached. The impact on phase shift analysis as well as upper bounds on possible resonant contributions in lower partial waves are discussed. [ABSTRACT FROM AUTHOR]

At the Cooler-Synchrotron COSY/Jülich polarized and unpolarized elastic proton-proton scattering has been investigated with the EDDA-Experiment in the energy range (Tp&ssymp; 0.5-2.5 GeV). By taking scattering data during the acceleration of the beam with a large-acceptance (θc.m.&ssymp; 300° 90°) detector, precise excitation functions for differential cross-section and analyzing power have been measured in small energy steps with consistent normalization with respect to luminosity and polarization. These data have helped to improve the determination of phase-shifts at higher energies and impose tight quantitative upper bounds on possible resonant contributions to pp elastic scattering, as they might arise from exotic 6-quark configurations. Recently, with polarized beam and target, the spin-correlation parameters ANN, A33, and ASL have been determined at 10 energies between 0.8 and 2.5 GeV. The observable A33 has been measured the first time above 800 MeV and our results are in sharp contrast to phase-shift predictions at higher energies. [ABSTRACT FROM AUTHOR]