The tensor analysing power component T 21 of the exclusive π - - meson photoproduction on deuteron in the resonance region. V.N.Stibunov 1, L.M. Barkov 2, V.F.Dmitriev 2, B.A. Lazarenko 2, A.Yu. Loginov 1, S.I. Mishnev 2, D.M. Nikolenko 2, A.V. Osipov 1, I.A. Rachek 2, R. Sh. Sadykov 2, Yu.V. Shestakov 2, A.A. Sidorov 1, D.K. Toporkov 2 and S.A. Zevakov 2. 1 Nuclear Physics Institute of Tomsk Polytechnical University, Tomsk, Russia 2 Budker Institute of Nuclear Physics, Novosibirsk, Russia SPIN’2008

V.N. Stibunov, NPI TPU, Tomsk. SPIN'2008, UVA Introduction We present the experimental and calculated data about the tensor analysing power component T 21 of the  d  pp  - reaction in the photon energy range ( ) MeV. The experimental results were obtained on the internal polarized deuterium target of the Novosibirsk electron storage ring VEPP-3. The experimental setup registrated two protons in coincidence for the proton energy interval ( ) MeV and for proton angle interval (45 o – 90 o ). We have measured the tensor target asymmetries of the reaction  d  pp  - in the experiment where kinematics are completely defined. The goal of this experiment consists in getting of a better knowledge of the properties of the NN,  NN and ∆N systems.

V.N. Stibunov, NPI TPU, Tomsk. SPIN'2008, UVA3 VEPP-3 storage ring Orbit length: 74,4 m Electron energy: 0,35 – 2 GeV Electron current: up to 150 mA Beam life time: 8000 sec

V.N. Stibunov, NPI TPU, Tomsk. SPIN'2008, UVA4 General view of the target system at VEPP-3 storage ring SC – storage cell CP – cryopump HM – holding field magnet IP – ion pump GP – getter pump QM – quadrupole magnet ABS – atomic beam source BRP – Breit-Rabi polarimeter QMA – quadrupole magnet analyser

V.N. Stibunov, NPI TPU, Tomsk. SPIN'2008, UVA5 Target storage cell The cell was coated with drifilm to inhibit atom depolarization during collisions with the cell walls. The polarized beam from the ABS is injected into an open-ended, T-shaped storage cell with elliptical cross section 13  24mm Cooling the cell with liquid nitrogen further increased the density, to achieve an estimated target thickness of  8  at/cm 2 The direction of the polarization axis was fixed by a megnetic holding field H, varied along the storage cell within the interval 88 — 95 mT

V.N. Stibunov, NPI TPU, Tomsk. SPIN'2008, UVA6 Cryogenic atomic beam source for polarized deuterium target S1  S5 – superconducting sextupoles; MFT/SFT – medium/strong field transition; The flux of deuteron polarized atoms – 8,2  at/sec; Tensor polarization, P zz  98%; Vector polarization, P z = 0;

V.N. Stibunov, NPI TPU, Tomsk. SPIN'2008, UVA7 Schematic overview of the particle detection system Total electron beam current integral collected: 566 kC

V.N. Stibunov, NPI TPU, Tomsk. SPIN'2008, UVA8 Low-Q polarimeter at VEPP-3

V.N. Stibunov, NPI TPU, Tomsk. SPIN'2008, UVA9 Cross section

V.N. Stibunov, NPI TPU, Tomsk. SPIN'2008, UVA10 Tensor target asymmetry

V.N. Stibunov, NPI TPU, Tomsk. SPIN'2008, UVA11 Selection of  d  pp  - events the proton vertexes  7mm from beam line (  E, E) analysis in hadron telescopes complanar events (   12 o )

V.N. Stibunov, NPI TPU, Tomsk. SPIN'2008, UVA12 Calculation of the polarization observables and differential cross section

V.N. Stibunov, NPI TPU, Tomsk. SPIN'2008, UVA13 Results on T 21 measurement total amplitude plane wave approximation experiment

V.N. Stibunov, NPI TPU, Tomsk. SPIN'2008, UVA14 Results on T 21 measurement total amplitude plane wave approximation experiment

V.N. Stibunov, NPI TPU, Tomsk. SPIN'2008, UVA Summary 1.The T 21 -component of the tensor analysing power of the reaction  d  pp  - has been obtained at the photon energy range ( ) MeV. 2.Dependences of the T 21 -component from a photon energy, from the momenta, angles of the emitted particles and from effective masses of the pp, p , pp  - systems have been obtained. 3.Theoretical calculations with taking into account  N and NN rescattering give only qualitative consent with the experimental results. 4.Difference (more than 3  ) of the theoretical and experimental results are exists both in broad interval of the change variables, and in narrow interval, comparable to accuracy of the measurement. 5.Our Collaboration conducts preparation of the new experiments for the pion photoproduction research on the tensor polarized deuterons: in the other kinematical regions; by the tagged photons; the two-spin experiments. We work with variants of theoretical calculations which include excitation of the dibarion resonances in the pion photoproduction on the tensor polarized deuterons