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[en] The paper presents new experimental data on the spin rotation parameter A obtained recently by ITEP-PNPI collaboration at the ITEP accelerator. The set of measurements was performed in carefully chosen critical points with precision sufficient for choosing the correct branches of partial wave analyses. The data for both π+ and π- scattering at 1.0, 1.43 and 1.62 GeV/c is included. The influence of the measurements on the baryon resonance properties is also discussed. (author)
[en] Double spin effects in polarized pp-elastic scattering in the Coulomb nuclear interference (CNI) region are sensitive to small contributions to the nuclear amplitude in addition to Pomeron exchange dominating at high energies. Measurements of double spin asymmetries require external luminosity normalization using collision counts for all spin combinations. Several possible sources of such data from various STAR subsystems were thoroughly analyzed to make the best choice. BBC arrays were found to be free of double spin effects to the level of ∼ 2 × 10−4 thus leading to the systematic uncertainty ∼10−3 in the value of (A NN + A SS )/2.
[en] The electronics of the data acquisition system based on silicon photomultipliers is briefly described. The elements and modules of the system were designed and constructed at ITEP especially for the DANSS detector. Examples of digitized signals obtained with the presented electronic modules and selected results on processing of the DANSS engineering data-taking run in spring 2016 are given.
[en] Elastic scattering of polarized protons at small four momentum transfer squared t is described by interference of Coulomb and nuclear amplitudes. Coulomb amplitude is well calculable by QED and such interference provides a unique opportunity to study the nuclear amplitude. At high energies this amplitude is believed to be dominated by Pomeron exchange. Measurement of asymmetries can provide evidence for contribution of other Reggeons, including hypothetical Odderon. Polarized proton collider at RHIC facility is a perfect place for such experiment.A one-week dedicated run with special beam optics in June 2009 allowed us to collect statistics of more than 30 millions of elastic triggers with transversely polarized beams in the -t range 0.005-0.035 (GeV/c)2 at √(s) = 200 GeV. In this paper we present preliminary results of single and double transverse spin asymmetries.
[en] The RHIC polarized proton complex utilizes polarimeters in each of the Blue and Yellow beams that measure the beam polarization through the p-Carbon elastic scattering process in the Coulomb Nuclear Interference kinematic region. This along with a Polarized Hydrogen Jet Target that utilizes the proton-proton elastic scattering process to first measure the analyzing power of the reaction and using the reverse process to measure the beam polarization. The latter is used to calibrate the p-Carbon polarimeters at the desired beam energy. In Run 9 RHIC ran with beams at center-of-mass energies of 200 and 500 GeV respectively. The higher beam intensities as well as the fact that the 250 GeV beam size is much smaller than that at 100 GeV resulted in significantly higher rates seen by the polarimeters and led to observed instability. In this paper, we will discuss the problems encountered and the tests that were carried out using the AGS as a proxy in an attempt to solve the problems and the path forward we took towards the upcoming polarized proton Run11.
[en] Analysis of PC polarimeter data at √s = 200 and 500 GeV from Run9 is presented. Final polarization results, fill-by-fill, for blue and yellow beams, as to be used by RHIC experiments (in collisions) are released and collected in http://www4.rcf.bnl.gov/cnipol/pubdocs/Run09Offline/. Global relative systematic uncertainties (delta)P/P (to be considered as correlated from fill to fill) are 4.7% for 100 GeV beams, and 8.3% (12.1%) for blue (yellow) 250 GeV beams. For a product of two beam polarizations PB · PY (used in double spin asymmetry measurements) the relative uncertainty (delta)(PB · PY)/(PB · PY) 8.8% for 100 GeV beams and 18.5% for 250 GeV beams. For the average between two beam polarization (PB + PY)/2 (used in single spin asymmetry measurements, when data from two polarized beams are combined) the relative uncertainty is 4.4% for 100 GeV beams and 9.2% for 250 GeV beams. Larger uncertainties for 250 GeV beams relate to significant rate related systematic effects experienced in the first part of Run9 (due to thicker targets used and smaller trans. beam size at higher beam energy).
[en] In this note we will discuss the analysis of RHIC run 08 pC data that were collected during February 14 - March 10, 2008. An analysis method that is similar to Run 05 and Run 06 was adopted for Run 08 analysis (except few minor changes, which are described below). A detailed analysis note and a NIM article that describe the pC analysis procedure (for run 05 and run 06) can be found elsewhere. In brief, the analysis consists of calibrating the detectors, determining energy corrections ('dead layers'), determining good runs and extracting the polarization from data.
[en] Proton polarization measurements in the AGS (Alternate Gradient Synchrotron) and RHIC (Relativistic Heavy Ion Collider) are based on proton-carbon(pC) and proton-proton elastic scattering in the Coulomb Nuclear Interference (CNI) region. The CNI polarimeters are the essential tools for polarized proton acceleration setup and operation. High intensity recoil nuclei from the scattering of the circulating proton beam in the thin carbon target is efficiently utilized in the silicon strip detectors and data acquisition system, which is capable to analyze the event rate up to a few millions/second. This makes it possible for the fast, practically non-destructive polarization measurements. The polarization measurement on the beam energy ramp was implemented in AGS and RHIC, providing locations of polarization losses. Polarimeter operation in the scanning mode also gives polarization profile and beam profile (including bunch by bunch values for the later one). This paper summarizes the recent modifications. Results of polarization measurements are also discussed
[en] The RHIC polarized proton collider employs polarimeters in each of the Blue and Yellow rings that utilize the analyzing power in p-Carbon elastic scattering in the Coulomb Nuclear Interference region to measure the absolute beam polarization. These are calibrated by the polarized Hydrogen Jet Target that measures the absolute beam polarization in pp elastic scattering in the CNI region. This paper describes the status and performance of these polarimeters in the FY09 run which included both a 250 GeV/c and 100 GeV/c physics data taking periods. We will describe some of the difficulties encountered and the efforts underway to improve the performance in better energy resolution, rate handling capability, and reduced systematic uncertainties.