A new method to determine the spin tune is described and tested. In an ideal planar magnetic ring, the spin tune-defined as the number of spin precessions per turn-is given by ν(s)=γG (γ is the ...Lorentz factor, G the gyromagnetic anomaly). At 970 MeV/c, the deuteron spins coherently precess at a frequency of ≈120 kHz in the Cooler Synchrotron COSY. The spin tune is deduced from the up-down asymmetry of deuteron-carbon scattering. In a time interval of 2.6 s, the spin tune was determined with a precision of the order 10^{-8}, and to 1×10^{-10} for a continuous 100 s accelerator cycle. This renders the presented method a new precision tool for accelerator physics; controlling the spin motion of particles to high precision is mandatory, in particular, for the measurement of electric dipole moments of charged particles in a storage ring.
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The energy dependence of the total cross section for the
pp→
pK
+
Λ reaction was measured in the threshold region covering the excess energy range up to 7 MeV.
Existing model calculations describe ...the slope of the measured cross sections well, but are too low by a factor of two to three in rate.
The data were used for a precise determination of the beam momentum of the COSY-synchrotron.
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Exclusive and kinematically complete high-statistics measurements of the basic double-pionic fusion reactions pn→dπ0π0, pn→dπ+π− and pp→dπ+π0 have been carried out simultaneously over the energy ...region of the ABC effect using the WASA detector setup at COSY. Whereas the isoscalar reaction part given by the dπ0π0 channel exhibits the ABC effect, i.e. a low-mass enhancement in the ππ-invariant mass distribution, as well as the associated resonance structure in the total cross section, the isovector part given by the dπ+π0 channel shows a smooth behavior consistent with the conventional t-channel ΔΔ process. The dπ+π− data are very well reproduced by combining the data for isovector and isoscalar contributions, if the kinematical consequences of the isospin violation due to different masses for charged and neutral pions are taken into account.
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Determination of deuteron beam polarizations at COSY Chiladze, D.; Kacharava, A.; Rathmann, F. ...
Physical review special topics. PRST-AB. Accelerators and beams,
05/2006, Volume:
9, Issue:
5
Journal Article
Peer reviewed
Open access
The vector (Pz ) and tensor (Pzz ) polarizations of a deuteron beam have been measured using elastic deuteron–carbon scattering at 75.6 MeV and deuteron-proton scattering at 270 MeV. After ...acceleration to 1170 MeV inside the COSY storage ring, the polarizations of the deuterons were remeasured by studying the analyzing powers of a variety of nuclear reactions. For this purpose a hydrogen cluster target was employed at the ANKE magnetic spectrometer, which is situated at an internal target position in the ring. The overall precisions obtained were about 4% for both Pz and Pzz . Though all the measurements were consistent with the absence of depolarization during acceleration, only an upper limit of about 6% could be placed on such an effect.
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A study of the deuteron breakup reaction pd→(pp)n with forward emission of a fast proton pair with small excitation energy Epp< 3 MeV has been performed using the ANKE spectrometer at COSY-Jülich. An ...exclusive measurement was carried out at six proton-beam energies Tp= 0.6, 0.7, 0.8, 0.95, 1.35 and 1.9 GeV by reconstructing the momenta of the two protons. The differential cross section of the breakup reaction, averaged up to 8° over the cm polar angle of the total momentum of the pp pairs, has been obtained. Since the kinematics of this process is quite similar to that of backward elastic pd→dp scattering, the results are compared to calculations based on a theoretical model previously applied to the pd→dp process.
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The presently world largest data sample for π0→γe+e− decays studies containing nearly 5×105 events was collected using the WASA detector at COSY. A search for a dark photon U produced in the ...π0→γU→γe+e− decay from the pp→ppπ0 reaction was carried out. An upper limit on the square of the U−γ mixing strength parameter ϵ2 of 5×10−6 at 90% CL was obtained for the mass range 20 MeV<MU<100 MeV. This result together with other recent experimental limits significantly reduces the MUvs. ϵ2 parameter space which could explain the presently seen deviation between the Standard Model prediction and the direct measurement of the anomalous magnetic moment of the muon.
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