Search for the Cryptoexotic Member of the Baryon Antidecuplet 1/2+ in the Reactions pi- p --> pi- p and pi- p --> K L

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 adde

Backward asymmetry measurements in the elastic pion-proton scattering at resonance energies

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 Journa

ПРИМЕНЕНИ Е MN(II)-ТРАНС-1,2-ДИАМИНОЦИКЛОГЕКСАН-N,N,N',N'-ТЕТРААЦЕТАТА ДЛЯ ПАРАМАГНИТНОГО КОНТРАСТИРОВАНИЯ МЕНИНГИОМ ГОЛОВНОГО МОЗГА У СОБАК

Aim of research. We have evaluated the abilities of new original paramagnetic contrast agent Mn-DCTA (0,5 mol solution of Manganese(II) complex with trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetate, registered trade mark Cyclomang) for contrast-enhanced imaging of brain meningeomas in dogs.Material and methods. Twelve animals were included, all with brain tumors reveald during out-patient veterinary examinations. In ten of twelve the diagnosis was verified later by pathomorphologic study. The cerebral MRI has been carred out as set of axial, sagittal and coronal slices as thin as three to five mm, covering all the volume of brain.The scanning parameters in T1-weighted spin-ech mode were as follows: TR = 400–500 ms, TE = 15–20 ms, the dose of injected paramagnetic was standardised as 1 mmol per 10 kg of body weight. For quantitative analysis the index of enhancement was calculated.Results. In all cases the sure enhancement with clear visualization of cerebral tumor was obtained due to highly intensive uptake of Mn-DCTA to the tumor tissue. When evaluated quantitatively the uptake of Mn-DCTA to the tumor gave the index of enhancement in T1-weighted spin-echo mode as high as IE = 1,72 ± 0,18 for the central parts of tumor and IE = 2,08 ± 0,23 for the peripheral ones, where as in control animals it was far below these values. Intravenous injection of Mn-DCTA to dogs with cerebral tumors did not induce any detectable pathologic or even physiologic effects.Conclusion. Henceforth we conclude the Mn-DCTA provides highly available methodologically simple imaging of cerebral meningeomas and can be thought out as promising paramagnetic agent for clinical magnetic resonance imaging in humans.Цель исследования. Выполнено экспериментальное исследование возможностей нового оригинального отечественного парамагнетика Mn-ДЦТА (0,5 моль раствора комплекса марганца (II) с транс-1,2-диаминоциклогексан-N,N,N',N'-тетрауксусной кислотой, зарегистрированное название «Цикломанг») для контрастированной магнитно-резонасной томографической визуализации опухолей головного мозга в эксперименте.Материал и методы. В исследование включены 12 собак с выявленными в ходе ветеринарного обследования менингеальными опухолями головного мозга. Магнитно-резонасная томография (МРТ) головного мозга срезами по 3–5 мм выполнялась в аксиальных, фронтальных и сагиттальных плоскостях, в Т1-взвешенном режиме, с использованием параметров TR = 400–500 мс, TE = 15–20 мс, при введении парамагнетика в стандартной дозировке 1 ммоль на 10 кг массы тела животного. По данным количественной обработки Т1-взв. изображений до введения парамагнетика и спустя 5–9 мин после него рассчитывался индекс усиления (ИУ).Результаты. Во всех случаях достигалась уверенная визуализация опухолевого поражения головного мозга, с высокоинтенсивным контрастированием его за счет накопления в опухоли Mn-ДЦТА. При количественной оценке накопления парамагнетика в опухоли ИУ в Т1-взв. режиме составил 1,67 ± 0,23 для центральных отделов опухоли и 2,08 ± 0,22 – для периферических. В нормальных тканях поглощения парамагнетика Mn-ДЦТА не отмечалось. Введение парамагнетика собакам не сопровождалось какими-либо патологическими или физиологическими реакциями.Заключение. Таким образом, Mn-ДЦТА обеспечивает контрастированную МРТ-визуализацию менингеальных опухолей головного мозга и может рассматриваться как перспективный парамагнитный контраст для клинической визуализации в МРТ

Event-by-event fluctuations at SPS

Results on event-by-event fluctuations of the mean transverse momentum and net charge in Pb-Au collisions, measured by the CERES Collaboration at CERN-SPS, are presented. We discuss the centrality and beam energy dependence and compare our data to cascade calculations.Comment: 4 pages, 4 figures, proceedings to INPC2004 Goteborg, Swede

Modification of the rho meson detected by low-mass electron-positron pairs in central Pb-Au collisions at 158 A GeV/c

We present a measurement of $e^+e^-$ pair production in central Pb-Au collisions at 158$A$ GeV/$c$. As reported earlier, a significant excess of the $e^+e^-$ pair yield over the expectation from hadron decays is observed. The improved mass resolution of the present data set, recorded with the upgraded CERES experiment at the CERN-SPS, allows for a comparison of the data with different theoretical approaches. The data clearly favor a substantial in-medium broadening of the $\rho$ spectral function over a density-dependent shift of the $\rho$ pole mass. The in-medium broadening model implies that baryon induced interactions are the key mechanism to in-medium modifications of the $\rho$-meson in the hot fireball at SPS energy.Comment: Revised versio

Flow and non-flow event anisotropies at the SPS

A study of differential elliptic event anisotropies (v_2) of charged particles and high-pt pions in 158 AGeV/c Pb+Au collisions is presented. Results from correlations with respect to the event plane and from two-particle azimuthal correlations are compared. The latter give systematically higher v_2 values at pt>1.2GeV/c providing possibly an evidence of a non-flow semihard component.Comment: 4 pages, 6 figures, Quark Matter 2002, Nantes, to appear in Nucl. Phys.