Search

An experiment EPECUR, aimed at the search of the cryptoexotic non-strange member of the pentaquark antidecuplet, started its operation at a pion beam line of the ITEP 10 GeV proton synchrotron. The invariant mass range of the interest (1610-1770) MeV will be scanned for a narrow state in the pion-proton and kaon-lambda systems in the formation-type experiment. The scan in the s-channel is supposed to be done by the variation of the incident pi- momentum and its measurement with the accuracy of up to 0.1% with a set of 1 mm pitch proportional chambers located in the first focus of the beam line. The reactions under the study will be identified by a magnetless spectrometer based on wire drift chambers with a hexagonal structure. Because the background suppression in this experiment depends on the angular resolution, the amount of matter in the chambers and setup is minimized to reduce multiple scattering. The differential cross section of the elastic pi-p-scattering on a liquid hydrogen target in the region of the diffractive minimum will be measured with statistical accuracy 0.5% in 1 MeV steps in terms of the invariant mass. For KLambda-production the total cross section will be measured with 1% statistical accuracy in the same steps. An important byproduct of this experiment will be a very accurate study of Lambda polarization. The setup was assembled and tested in December 2008 and in April 2009 we had the very first physics run. About 0.5x10^9 triggers were written to disk covering pion beam momentum range 940-1135 MeV/c., Comment: 4 pages, 4 figures, to appear in the proccedings of DSPIN'09, Dubna, Russia, Sep. 1-5, 2009

The asymmetry parameter P was measured for the elastic pion-proton scattering in the very backward angular region of theta_cm ~ 150-170^o at several pion beam energies in the invariant mass range containing most of the pion-proton resonances. The general goal of the experimental program was to provide new data for partial wave analyses in order to resolve their uncertainties in the baryon resonance region to allow the unambiguous baryon spectrum reconstructions. Until recently the parameter P was not measured in the examined domain that might be explained by the extremely low cross section. At the same time the predictions of various partial wave analyses are far from agreement in some kinematic areas and specifically those areas were chosen for the measurements where the disagreement is most pronouncing. The experiment was performed at the ITEP U-10 proton synchrotron, Moscow, by the ITEP-PNPI collaboration in the latest 5 years., Comment: 6 pages, 5 figures. to be submitted to the European Physical Journal

'EPECUR' experiment setup is under construction at the beam line 322 of the ITEP proton synchrotron. The experiment requires several large area drift chambers to provide reasonable acceptance and fine pitch proportional chambers for beam particle tracking with total number of electronic channels of about 7000. New compact and cost effective readout system for these gaseous detectors was designed, prototyped and tested in the latest two years based on the modern technologies in analog and digital electronics, as well as in data transfer protocols. Mass production of the proportional chamber electronics is close to the end, while the boards for the drift chambers are manufactured in the amount to equip one 8-plane module. The paper presents the functional description of the whole DAQ system and its main parts together with some of the test results as an illustration of the excellent performance of the system. The appendix contains specific information which may be useful for the system users or code developers., Comment: 27 pages, 14 figures

The ITEP-PNPI collaboration presents new results of the measurements of the spin rotation parameter A in the elastic scattering of negative pions on protons at P_beam=1.43 GeV/c. The results are compared to the predictions of several partial wave analyses. The experiment was performed at the ITEP proton synchrotron, Moscow., Comment: 4 pages, 5 figures

The main goal of this proposal is the search for a narrow cryptoexotic nucleon resonance by scanning of the pi- p system invariant mass in the region (1610-1770) MeV with the detection of pi- p and K Lambda decays. The scan is supposed to be done by the variation of the incident pi- momentum and its measurement with the accuracy of up to +-0.1% (better than 1 MeV in terms of the invariant mass in the whole energy range) with a set of proportional chambers located in the first focus of the magnetooptical channel. High sensitivity of the method to the resonance under search is shown. The secondary particles scattered from a liquid hydrogen target are detected by sets of the wire drift chambers equipped with modern electronics. The time scale of the project is about 3 years. The budget estimate including manpower, the apparatus and operation cost, is about 40 million rubles. The beam time required is (4-6) two week runs on "high" (10 GeV/c) flattop of the ITEP proton synchrotron., Comment: 16 pages, 10 figures. v2: an acknowledge added

The ITEP-PNPI collaboration presents the results of the measurements of the spin rotation parameter A in the elastic scattering of positive and negative pions on protons at P_beam = 1.62 GeV/c. The setup included a longitudinally-polarized proton target with superconductive magnet, multiwire spark chambers and a carbon polarimeter with thick filter. Results are compared to the predictions of partial wave analyses. The experiment was performed at the ITEP proton synchrotron, Moscow., Comment: 7 pages, 3 figures. To be published in Phys. Lett. B