Measurement of the Analyzing Power in $\vec{p}d\to (pp)n$ \\with a Fast Forward ${}^1{S}_0$--Diproton

Abstract

A measurement of the analyzing power $A_y$ of the $\vec{p}d\to (pp)+n$ reaction was carried out at beam energies of 0.5 and 0.8 GeV by detection of a fast forward proton pair of small excitation energy $E_{pp}<3$ MeV. The kinematically complete experiment made use of the ANKE spectrometer at the internal beam of COSY and a deuterium cluster--jet target. For the first time the $S$--wave dominance in the fast diproton is experimentally demonstrated in this reaction. While at $T_p=0.8$ GeV the measured analyzing power $A_y$ vanishes, it reaches almost unity at $T_p=0.5$ GeV for neutrons scattered at ${\theta }_n^{c.m.}=167^{\circ }$. The results are compared with a model taking into account one--nucleon exchange, single scattering and $\Delta$ (1232) excitation in the intermediate state. The model describes fairly well the unpolarized cross section obtained earlier by us and the analyzing power at 0.8 GeV, it fails to reproduce the angular dependence of $A_y$ at 0.5 GeV.

arXiv comment4 pages, 4 figures, 1 table

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Cited by in corpus (6)

• Determination of Deuteron Beam Polarizations at COSY
• Spin-isospin selectivity in three-nucleon forces
• Production of the 1S0 diproton in the pp -> pp pi0 reaction at 0.8 GeV
• Energy dependence of forward 1S0 diproton production in the pp -> pp pi0 reaction
• Measurement of the analysing power in proton-proton elastic scattering at small angles
• Spin observables of the reactions NN -> DeltaN and pd -> Delta (pp)(1S0) in collinear kinematics