19 research outputs found
Relativistic effects and two-body currents in using out-of-plane detection
Measurements of the reaction were performed
using an 800-MeV polarized electron beam at the MIT-Bates Linear Accelerator
and with the out-of-plane magnetic spectrometers (OOPS). The
longitudinal-transverse, and , and the
transverse-transverse, , interference responses at a missing momentum
of 210 MeV/c were simultaneously extracted in the dip region at Q=0.15
(GeV/c). On comparison to models of deuteron electrodisintegration, the
data clearly reveal strong effects of relativity and final-state interactions,
and the importance of the two-body meson-exchange currents and isobar
configurations. We demonstrate that these effects can be disentangled and
studied by extracting the interference response functions using the novel
out-of-plane technique.Comment: 4 pages, 4 figures, and submitted to PRL for publicatio
Measurement of the Transverse-Longitudinal Cross Sections in the p (e,e'p)pi0 Reaction in the Delta Region
Accurate measurements of the p(e,e?p)pi0 reaction were performed at
Q^2=0.127(GeV/c)^2 in the Delta resonance energy region. The experiments at the
MIT-Bates Linear Accelerator used an 820 MeV polarized electron beam with the
out of plane magnetic spectrometer system (OOPS). In this paper we report the
first simultaneous determination of both the TL and TL? (``fifth" or polarized)
cross sections at low Q^{2} where the pion cloud contribution dominates the
quadrupole amplitudes (E2 and C2). The real and imaginary parts of the
transverse-longitudinal cross section provide both a sensitive determination of
the Coulomb quadrupole amplitude and a test of reaction calculations.
Comparisons with model calculations are presented. The empirical MAID
calculation gives the best overall agreement with this accurate data. The
parameters of this model for the values of the resonant multipoles are
|M_{1+}(I=3/2)|= (40.9 \pm 0.3)10^{-3}/m_pi, CMR= C2/M1= -6.5 \pm 0.3%,
EMR=E2/M1=-2.2 \pm 0.9%, where the errors are due to the experimental
uncertainties.Comment: 10 pages, 3 figures, minor corrections and addition
Measurement of the R response function for electroproduction at = 0.070 (GeV/c) in the transition}
Quadrupole amplitudes in the transition are associated
with the issue of nucleon deformation. A search for these small amplitudes has
been the focus of a series of measurements undertaken at Bates/MIT by the OOPS
collaboration. We report on results from H data obtained
at (GeV/c) and invariant mass of W=1155 MeV using the
out-of-plane detection technique with the OOPS spectrometers. The
and response functions were isolated.
These results, along with those of previous measurements at =1172 MeV and
(GeV/c), aim in elucidating the interplay between resonant and
non resonant amplitudes
Recent Measurements of gamma*N -> Delta Response Functions at Bates
A series of high precision measurements on the N ->Delta transition
involving polarized beams, out-of-plane detection and focal plane
polarimetry in the H((e) over bar, e’p)pi(0) and H((e) over bar,
e’pi(+))n channels have been pursued at Bates during the last three
years. They are geared towards the precise determination of the
quadrupole amplitudes in the N -> Delta transition and the isolation of
the coherent, competing processes at low Q(2)
RESONEUT: A detector system for spectroscopy with (d,n) reactions in inverse kinematics
The RESONEUT detector setup is described, which was developed for resonance spectroscopy using (d,n) reactions with radioactive beams in inverse kinematics and at energies around the Coulomb barrier. The goal of experiments with this setup is to determine the spectrum and proton-transfer strengths of the low-lying resonances, which have an impact on astrophysical reaction rates. The setup is optimized for l=0 proton transfers in inverse kinematics, for which most neutrons are emitted at backward angles with energies in the 80–300 keV range. The detector system is comprised of 9 p-terphenyl scintillators as neutron detectors, two annular silicon-strip detectors for light charged particles, one position-resolving gas ionization chamber for heavy ion detection, and a barrel of NaI-detectors for the detection of γ-rays. The detector commissioning and performance characteristics are described with an emphasis on the neutron-detector components
Ti decay and the neutrino capture cross section of Ar
International audienceTi decay was studied using the LISE3 spectrometer