arXiv subjects
Publications and source records attributed to Yu. A. Plis.
Single spin asymmetry in inclusive $π^0$-production was measured in the polarized target fragmentation region using 50 GeV proton beam. The asymmetry is in agreement with asymmetry measurements in the polarized beam fragmentation region carried out at higher energies. The measurement completed 30-years history of polarized measurements at the PROZA setup.
The first stage of the proposed polarization program SPASCHARM includes the measurements of the single-spin asymmetry (SSA) in exclusive and inclusive reactions with production of stable hadrons and the light meson and baryon resonances.In this study we foresee of using the variety of the unpolarized beams (pions, kaons, protons and antiprotons) in the energy range of 30-60 GeV. The polarized proton and deuteron targets will be used for revealing the flavor and isotopic spin dependencies of the polarization phenomena. The neutral and charged particles in the final state will be detected.
It is proposed to develop a source of polarized ^3He^{++} ions for the JINR Accelerator Complex on the basis of its polarized deuteron source by feeding its radio-frequency dissociator with ^3He gas to produce metastable atoms, using an existing sextupole magnet and adding a low-field rf transition units. The radio-frequency transitions of the atomic states of helium-3 in the metastable state are studied. The Schroedinger equations in the uncoupled basis |ψ_e,ψ_h> and also in the basis of stationary states are received. Results of computer simulations agree with published data. The possibility to use two types of the weak field transitions in the helium-3 with different frequencies to get positive or negative values of the helion polarization is shown.
Single-spin asymmetries $A_N$ in reactions p+p(pol)->π^0 + X and π^-+p(pol)->π^0 + X at 50 and 40 GeV/c respectively behave in drastically different ways in function of transverse momentum in the central region. At the same time $A_N$ in the polarized proton fragmentation region of these reactions are practically coinciding. Our new data on the analyzing power at 50 GeV/c in the polarized proton fragmentation region in reaction p+p(pol)->π^0 + X confirm this conclusion with better statistics and coincide with our previous data at 70 GeV/c for the same reaction.
The new polarization program SPASCHARM is being prepared in Protvino. The program has two stages. The first stage is dedicated to single-spin asymmetries in the production of miscellaneous light resonances with the use of 34 GeV $π^-$-beam. Inclusive and exclusive reactions will be studied simultaneously. The second stage is dedicated to single-spin and double-spin asymmetries in charmonium production with the use of 70 GeV polarized proton beam which will allow us to understand charmonium hadronic production mechanism and make gluon polarization $Δg(x)$ extraction at large $x$.
The talk continues the series of Single Spin Asymmetry (SSA) $π^0$ inclusive measurements carried out at Protvino 70 GeV accelerator. The asymmetry in the polarized target fragmentation region grows up in absolute value with $\xf$ decreasing and equals to $(-16 \pm 5)%$ at $-0.4<\xf<-0.25$. The result of the current experiment is in agreement with the universal threshold in pion asymmetries.
A new measurement of $Δσ_T$ for polarized neutrons transmitted through a polarized proton target at 16.2 MeV has been made. A polarized neutron beam was obtained from the $^{3}\rm{H}(d,\vec n)^{4}\rm{He}$ reaction; proton polarization over 90\% was achieved in a frozen spin target of 20 cm$^3$ volume. The measurement yielded the value $Δσ_T=(-126\pm21\pm14)$ mb. The result of a simple phase shift analysis for the $^3S_1-^3D_1$ mixing parameter $ε_1$ is presented and compared with the theoretical potential model predictions.