The design and parameters of the polarized-beam facility at U-70 proton synchrotron of NRC Kurchatov Institute - IHEP are presented. The new beamline 24A will provide the polarized proton and antiproton beams for carrying out the rich physics program of the SPASCHARM experiment for comprehensive studies of spin phenomena in a wide spectrum of hadronic reactions in the energy range of 10-45 GeV.
New crystal technique - array of bent strips and a fan-type reflector, based on thin straight plates - have been used for research of extraction and collimation a circulating beam in the U-70 accelerator at the energy 50 GeV and 1.3 GeV. It is shown,
that new devices can effectively steer a beam in a wide energy range. For protons with energy 50 GeV efficiency of extraction and collimation about 90 % has been achieved which is record for this method. Reduction of particle losses in 2-3 times was observed also in accelerator at application of different crystals in comparison with the usual one-stage collimation scheme of beam with a steel absorber.
This paper presents the physical background for particle extraction from IHEP accelerator using short bent silicon crystals, analyses the results of the studies, considers in detail the regime of simultaneous work of crystal extraction and several in
ternal targets. It is experimentally shown that the use of short crystals allows the extraction of beams with intensity of 10e12 proton/cycle with efficiency of 85%.
The article presents an overview of the results obtained at U-70 accelerator of IHEP to use bent crystals for beam control of high energy protons. Considerable attention is paid to practical application of crystals to create new modes of beam extract
ion from the accelerator to ensure experiments on high energy physics. It was shown that with the crystal deflectors the efficiency reached ~ 90% with intensity up to 10^12 protons per cycle of U-70. The results of experiments on the use of crystals to enhance the effectiveness of the absorption of the unused beam, as well as the use of crystals for collimation of beam halo are presented. Perspectives to use of bent crystals to extract low energy light ions from U-70 are also discussed.
This report overviews studies accomplished in the U70 proton synchrotron of IHEP-Protvino during the recent two decades. Major attention is paid to a routine application of bent crystals for beam extraction from the machine. It has been confirmed exp
erimentally that efficiency of beam extraction with a crystal deflector of around 85% is well feasible for a proton beam with intensity up to 1012 protons per cycle. Another trend is to use bent crystals for halo collimation in a high energy collider. New promising options emerge for, say, LHC and ILC based on the volume reflection effect, which has been discovered recently in machine study runs at U70 of IHEP (50 GeV) and SPS of CERN (400 GeV).
The only comparative study of the inclusive pion single-spin asymmetries produced in the interactions of the polarized protons and antiprotons in collisions with unpolarized proton was carried out at E-704 experiment. Significant asymmetries were fou
nd at large $x_{F}$ and middle $p_{T}$, $pi^{+}$ and $pi^{0}$ asymmetries have positive signs while $pi^{-}$ has negative one in the $p^{uparrow}+p$ collisions, while in the $bar{p}^{uparrow}+p$ interactions the $pi^{-}$ and $pi^{0}$ asymmetries have positive signs while $pi^{+}$ has negative sign. Similar experimental study can be done in the SPASCHARM experiment at U-70 accelerator at IHEP for various secondary particles with the use of 16 GeV polarized proton and antiproton beams.