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Title: Measurements of the Total-Cross-Section Difference {delta}{sigma}{sub L}(np) at 1.39, 1.69, 1.89, and 1.99 GeV

Abstract

New accurate data of the neutron-proton spin-dependent total-cross-section difference {delta}{sigma}{sub L}(np) at the neutron-beam kinetic energies 1.39, 1.69, 1.89, and 1.99 GeV are presented. In general, these data complete the measurements of energy dependence of {delta}{sigma}{sub L}(np) over the Dubna Synchrophasotron energy region. Measurements were carried out at the Synchrophasotron of the Veksler and Baldin Laboratory of High Energies of the Joint Institute for Nuclear Research. The quasi-monochromatic neutron beam was produced by breakup of extracted polarized deuterons. The deuteron (and hence neutron) polarization direction was flipped every accelerator burst. The initial transverse (with respect to beam momentum) neutron polarization was changed to a longitudinal one and longitudinally polarized neutrons were transmitted through the large proton longitudinally polarized target. The target polarization direction was inverted after one to two days of measurements. Four different combinations of the beam and target parallel and antiparallel polarization directions, both oriented along the neutron-beam momentum, were used at each energy. A fast decrease in -{delta}{sigma}{sub L}(np) with increasing energy above 1.1 GeV and a structure in the energy dependence around 1.8 GeV, first observed from our previous data, seem to be well revealed. The new results are also compared with model predictions and withmore » phase-shift analysis fits. The {delta}{sigma}{sub L} quantities for isosinglet state I = 0, deduced from the measured {delta}{sigma}{sub L}(np) values and known {delta}{sigma}{sub L}(pp) data, are also given. The results of the measurements of unpolarized total cross sections {sigma}{sub 0tot}(np) at 1.3, 1.4, and 1.5 GeV and {sigma}{sub 0tot}(nC) at 1.4 and 1.5 GeV are presented as well. These data were obtained using the same apparatus and high-intensity unpolarized deuteron beams extracted either from the Synchrophasotron or from the Nuclotron.« less

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;  [1]
  1. Veksler and Baldin Laboratory of High Energies, Joint Institute for Nuclear Research, Dubna, Moscow oblast, 141980 (Russian Federation) [and others
Publication Date:
OSTI Identifier:
20692902
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Atomic Nuclei; Journal Volume: 68; Journal Issue: 11; Other Information: Translated from Yadernaya Fizika, ISSN 0044-0027, 68, 1858-1873 (No. 11, 2005); DOI: 10.1134/1.2131111; (c) 2005 Pleiades Publishing, Inc; Country of input: International Atomic Energy Agency (IAEA); TN:
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; DEUTERON BEAMS; DEUTERONS; DUBNA; ENERGY DEPENDENCE; GEV RANGE; PHASE SHIFT; POLARIZATION; POLARIZED TARGETS; PROTON-NEUTRON INTERACTIONS; PROTONS; SPIN; TOTAL CROSS SECTIONS

Citation Formats

Sharov, V.I., Anischenko, N.G., Averichev, S.A., Bartenev, V.D., Blinov, N.A., Borzunov, Yu.T., Chernykh, E.V., Chumakov, V.F., Dolgii, S.A., Fimushkin, V.V., Golovanov, L.B., Kirillov, A.D., Komogorov, E.V., Kovalenko, A.D., Krasnov, V.A., Ladygin, V.P., Liburg, M.Yu., Livanov, A.N., Maniakov, P.K., and Matyushevsky, E.A. Measurements of the Total-Cross-Section Difference {delta}{sigma}{sub L}(np) at 1.39, 1.69, 1.89, and 1.99 GeV. United States: N. p., 2005. Web. doi:10.1134/1.2131111.
Sharov, V.I., Anischenko, N.G., Averichev, S.A., Bartenev, V.D., Blinov, N.A., Borzunov, Yu.T., Chernykh, E.V., Chumakov, V.F., Dolgii, S.A., Fimushkin, V.V., Golovanov, L.B., Kirillov, A.D., Komogorov, E.V., Kovalenko, A.D., Krasnov, V.A., Ladygin, V.P., Liburg, M.Yu., Livanov, A.N., Maniakov, P.K., & Matyushevsky, E.A. Measurements of the Total-Cross-Section Difference {delta}{sigma}{sub L}(np) at 1.39, 1.69, 1.89, and 1.99 GeV. United States. doi:10.1134/1.2131111.
Sharov, V.I., Anischenko, N.G., Averichev, S.A., Bartenev, V.D., Blinov, N.A., Borzunov, Yu.T., Chernykh, E.V., Chumakov, V.F., Dolgii, S.A., Fimushkin, V.V., Golovanov, L.B., Kirillov, A.D., Komogorov, E.V., Kovalenko, A.D., Krasnov, V.A., Ladygin, V.P., Liburg, M.Yu., Livanov, A.N., Maniakov, P.K., and Matyushevsky, E.A. Tue . "Measurements of the Total-Cross-Section Difference {delta}{sigma}{sub L}(np) at 1.39, 1.69, 1.89, and 1.99 GeV". United States. doi:10.1134/1.2131111.
@article{osti_20692902,
title = {Measurements of the Total-Cross-Section Difference {delta}{sigma}{sub L}(np) at 1.39, 1.69, 1.89, and 1.99 GeV},
author = {Sharov, V.I. and Anischenko, N.G. and Averichev, S.A. and Bartenev, V.D. and Blinov, N.A. and Borzunov, Yu.T. and Chernykh, E.V. and Chumakov, V.F. and Dolgii, S.A. and Fimushkin, V.V. and Golovanov, L.B. and Kirillov, A.D. and Komogorov, E.V. and Kovalenko, A.D. and Krasnov, V.A. and Ladygin, V.P. and Liburg, M.Yu. and Livanov, A.N. and Maniakov, P.K. and Matyushevsky, E.A.},
abstractNote = {New accurate data of the neutron-proton spin-dependent total-cross-section difference {delta}{sigma}{sub L}(np) at the neutron-beam kinetic energies 1.39, 1.69, 1.89, and 1.99 GeV are presented. In general, these data complete the measurements of energy dependence of {delta}{sigma}{sub L}(np) over the Dubna Synchrophasotron energy region. Measurements were carried out at the Synchrophasotron of the Veksler and Baldin Laboratory of High Energies of the Joint Institute for Nuclear Research. The quasi-monochromatic neutron beam was produced by breakup of extracted polarized deuterons. The deuteron (and hence neutron) polarization direction was flipped every accelerator burst. The initial transverse (with respect to beam momentum) neutron polarization was changed to a longitudinal one and longitudinally polarized neutrons were transmitted through the large proton longitudinally polarized target. The target polarization direction was inverted after one to two days of measurements. Four different combinations of the beam and target parallel and antiparallel polarization directions, both oriented along the neutron-beam momentum, were used at each energy. A fast decrease in -{delta}{sigma}{sub L}(np) with increasing energy above 1.1 GeV and a structure in the energy dependence around 1.8 GeV, first observed from our previous data, seem to be well revealed. The new results are also compared with model predictions and with phase-shift analysis fits. The {delta}{sigma}{sub L} quantities for isosinglet state I = 0, deduced from the measured {delta}{sigma}{sub L}(np) values and known {delta}{sigma}{sub L}(pp) data, are also given. The results of the measurements of unpolarized total cross sections {sigma}{sub 0tot}(np) at 1.3, 1.4, and 1.5 GeV and {sigma}{sub 0tot}(nC) at 1.4 and 1.5 GeV are presented as well. These data were obtained using the same apparatus and high-intensity unpolarized deuteron beams extracted either from the Synchrophasotron or from the Nuclotron.},
doi = {10.1134/1.2131111},
journal = {Physics of Atomic Nuclei},
number = 11,
volume = 68,
place = {United States},
year = {Tue Nov 01 00:00:00 EST 2005},
month = {Tue Nov 01 00:00:00 EST 2005}
}
  • A measurement of [Delta][sigma][sub [ital L]]([ital np]), the difference between neutron-proton total cross sections for pure longitudinal spin states, is described. Data were taken at LAMPF for five neutron beam kinetic energies: 484, 568, 634, 720, and 788 MeV. The statistical errors are in the range of 0.64--1.35 mb. Various sources of systematic effects were investigated and are described. Overall systematic errors are estimated to be on the order of 0.5 mb and include an estimate for the uncertainty in the neutron beam polarization. The [Delta][sigma][sub [ital L]] results are consistent with previous results from PSI and Saclay. These data,more » when combined with other results and fitted to a Breit-Wigner curve, are consistent with an elastic [ital I]=0 resonance with mass 2214[plus minus]15 (stat) [plus minus]6 (syst) MeV and width 75[plus minus]21[plus minus]12 MeV. Because of a lack of [Delta][sigma][sub [ital T]]([ital np]) data between 500 and 800 MeV, it is not possible to differentiate between a singlet or coupled-triplet partial wave being responsible.« less
  • We present results of the total cross section difference {triangle}{sigma} {sub T} (np) obtained in transmission measurements at the energies 0.86, 0.88, 0.91 and 0.94 GeV. The SATURNE II polarized beam of free neutrons obtained from the break-up of polarized deuterons was transmitted through the polarized Saclay frozen-spin proton target. The beam and target polarizations were oriented in the vertical direction. The present results agree with previous SATURNE measurements and improve the amplitude analysis 4-n the forward direction.
  • The data from measurements of the total-cross-section differences ..delta..sigma/sub T/ and ..delta..sigma/sub L/ for p-p scattering and the spin-averaged total cross sections are analyzed to determine the singlet (sigma/sub s/ /sup T/) and (sigma/sub t/ /sup T/) cross sections. The structures observed in ..delta..sigma/sub T/ and ..delta..sigma/sub L/ near 1.3 GeV/c are found to result primarily from increases in sigma/sub s/ /sup T/ and sigma/sub t/ /sup T/. These increases are shown to be consistent with the Mandelstam model of pion production. No resonantlike behavior is required to describe the structures in ..delta..sigma/sub T/ and ..delta..sigma/sub L/.
  • A measurement off {Delta}{sigma}{sub L}(np), the difference between neutron-proton total cross sections in pure longitudinal spin states, is described. The results will help determine the isospin-zero (I = 0) scattering amplitudes, which are not well known above laboratory energies of 500 MeV, whereas the isospin-one (I = 1) amplitudes are fairly well-determined to 1 GeV. Data points were taken at the Los Alamos Meson Physics Facility (LAMPF) at Los Alamos, New Mexico, for five neutron beam energies: 484, 568, 634,720 and 788 MeV; they are the first in this energy range. Polarized neutrons were produced by charge-exchange of polarized protonsmore » on a liquid deuterium target (LD{sub 2}). Large-volume neutron counters detected the neutrons that passed through a polarized proton target. The counters subtended a range of solid angles large enough to allow extrapolation of the scattered neutrons to 0{degree}. Two modifications to the LAMPF accelerator system which were made for this work are described. They included a beam buncher,'' which modified the normal rf-time structure of the proton beam and allowed for the selection of peak-energy neutrons by time-of-flight means, and a computerized beam steering program, which reduced systematic effects due to beam motion at the LD{sub 2} target. The experimental values of {Delta}{sigma}{sub L}(np) are found to be consistent with other np data, including preliminary data from SIN and Saclay, but not with some results from Argonne which used a polarized proton beam and a polarized deuteron target. The I = 0 component was extracted from {Delta}{sigma}{sub L}(np) using existing pp data (I = 1), with the unexpected result that {Delta}{sigma}{sub L}(I = 0) was found to be essentially identical in shape to {Delta}{sigma}{sub L}(I = 1). The significance of this is not yet understood.« less
  • The difference ..delta..sigma/sub T/ = sigma(arrow-downup-arrow)-sigma(up-arrowup-arrow) between the proton-proton total cross sections for protons in pure transverse-spin states, was measured at incident momenta 0.8 to 2.5 GeV/c in experiments performed at the Los Alamos Clinton P. Anderson Meson Physics Facility and the Argonne Zero Gradient Synchrotron. In agreement with other data, peaks were observed at center-of-mass energies of 2.14 and 2.43 GeV/c/sup 2/, where /sup 1/D/sub 2/ and /sup 1/G/sub 4/ dibaryon resonances have been proposed.