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.
A low-energy spin-physics program is being developed at the COSY storage ring. To support the planned experimental activities, several experimental tools for polarized beams and targets have been ...developed. The paper presents the physics case and the readiness of the setup for its realization.
Six cropping populations, three variety mixtures and one diversity population were developed from winter wheat varieties and studied for physical, compositional and end-use quality traits for three ...years (2011–2013) under different European climatic and management conditions in order to study the stability of these traits resulted by the genetic diversity. The beneficial compositional and nutritional properties of the populations were assessed, while variation and stability of the traits were analysed statistically. No significant differences were found among the populations in low-input and organic management farming systems in the physical, compositional and processing properties, but there was a difference in the stability of these traits. Most of the populations showed higher stability than the control wheat variety, and populations developed earlier had higher stability than those developed later. Furthermore, some populations were found to be especially unstable for some traits at certain sites (mostly at Austrian, Swiss and UK organic sites). Protein content of the populations was high (13.0–14.7%) without significant difference among them, but there was significant variation in their gluten content (28–36%) and arabinoxylan content (14.6–20.3 mg/g). The most outstanding population for both protein and arabinoxylan content was a Hungarian cropping population named ELIT-CCP. It was concluded that the diversity found in the mixtures and CCPs have stabilizing effect on the quality parameters, but a higher stability was observed under low-input than under organic conditions. These results could be beneficial not only for breeders but also for the consumers in the long run.
The present paper focuses on numerical investigations of mixed lubrication phenomena. Generally minimized for sliding systems, this type of lubricated contact is essential to ensure the original ...basic function of a lubricated friction system. As analyses of such a contact are hardly possible with experimental facilities, the finite element method was chosen to model the occurring friction phenomena at the micro-scale. A three-dimensional model is implemented considering two lubricated real rough bodies, Bowden and Tabor adhesion model and heat generation occurring in the solid–solid contact. Present analysis gives an overview on how surface roughness and machining direction influence the friction behavior as well as the contact and fluid pressure fields in mixed lubricated systems. First results are in accordance with the literature but therefore require the use of a statistical approach to deliver quantitative results in adequation with real systems.
► Modelling of mixed lubrication effects by means of the finite element method. ► Importation of rough bodies into finite element software. ► Impact of the machining direction in mixed lubricated systems. ► Adhesion phenomena of Bowden and Tabor. ► Temperature evolution in the solid–solid contact interface.
The paper describes the commissioning of the experimental equipment and the machine studies required for the first spin-filtering experiment with protons at a beam kinetic energy of 49.3 MeV in COSY. ...The implementation of a low-β insertion made it possible to achieve beam lifetimes of τb=8000s in the presence of a dense polarized hydrogen storage-cell target of areal density dt=(5.5±0.2)×1013atoms/cm2. The developed techniques can be directly applied to antiproton machines and allow the determination of the spin-dependent p¯p cross sections via spin filtering.
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 nucleonanucleon 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 protonaproton 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.
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 Td=726 MeV. By ...selecting two fast protons at low relative energy Epp, 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 Tn≈12Td=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 Epp and the momentum transfer. This lends broad support to the current neutron–proton partial wave solution that was used in the estimation.
The vector and tensor analysing powers, Ay and Ayy, of the pd→→n{pp}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 S01 state, here denoted by {pp}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.
Test of Time-Reversal Invariance at COSY (TRIC) Eversheim, D; Valdau, Yu; Lorentz, B
International journal of modern physics. Conference series,
2016, Letnik:
40, Številka:
1
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
At the Cooler Synchrotron COSY a novel (P-even, T-odd) null test of time-reversal invariance to an accuracy of 10
−
6
is planned as an internal target transmission experiment. The parity conserving ...time-reversal violating observable is the total cross-section asymmetry A
y,xz
. This quantity is measured using a polarized proton beam with an energy of 135 MeV and an internal tensor polarized deuteron target from the PAX atomic beam source. The reaction rate will be determined by the lifetime of the beam. Consequently, the accuracy of the current measurement of the circulating proton beam is crucial for this experiment. Thus, the cooler synchroton ring serves as an ideal forward spectrometer, as a detector, and an accelerator.
PDF
