57 research outputs found
Quark-model study of few-baryon systems
We review the application of non-relativistic constituent quark models to
study one, two and three non-strange baryon systems. We present results for the
baryon spectra, potentials and observables of the NN, N,
and NN systems, and also for the binding energies of three
non-strange baryon systems. We make emphasis on observable effects related to
quark antisymmetry and its interplay with quark dynamics.Comment: 82 pages, 36 figures, 18 tables. Accepted for publication in Reports
on Progress in Physic
Spin tune mapping as a novel tool to probe the spin dynamics in storage rings
Precision experiments, such as the search for electric dipole moments of
charged particles using storage rings, demand for an understanding of the spin
dynamics with unprecedented accuracy. The ultimate aim is to measure the
electric dipole moments with a sensitivity up to 15 orders in magnitude better
than the magnetic dipole moment of the stored particles. This formidable task
requires an understanding of the background to the signal of the electric
dipole from rotations of the spins in the spurious magnetic fields of a storage
ring. One of the observables, especially sensitive to the imperfection magnetic
fields in the ring is the angular orientation of stable spin axis. Up to now,
the stable spin axis has never been determined experimentally, and in addition,
the JEDI collaboration for the first time succeeded to quantify the background
signals that stem from false rotations of the magnetic dipole moments in the
horizontal and longitudinal imperfection magnetic fields of the storage ring.
To this end, we developed a new method based on the spin tune response of a
machine to artificially applied longitudinal magnetic fields. This novel
technique, called \textit{spin tune mapping}, emerges as a very powerful tool
to probe the spin dynamics in storage rings. The technique was experimentally
tested in 2014 at the cooler synchrotron COSY, and for the first time, the
angular orientation of the stable spin axis at two different locations in the
ring has been determined to an unprecedented accuracy of better than
rad.Comment: 32 pages, 15 figures, 7 table
Phase Measurement for Driven Spin Oscillations in a Storage Ring
This paper reports the first simultaneous measurement of the horizontal and
vertical components of the polarization vector in a storage ring under the
influence of a radio frequency (rf) solenoid. The experiments were performed at
the Cooler Synchrotron COSY in J\"ulich using a vector polarized, bunched
deuteron beam. Using the new spin feedback system, we
set the initial phase difference between the solenoid field and the precession
of the polarization vector to a predefined value. The feedback system was then
switched off, allowing the phase difference to change over time, and the
solenoid was switched on to rotate the polarization vector. We observed an
oscillation of the vertical polarization component and the phase difference.
The oscillations can be described using an analytical model. The results of
this experiment also apply to other rf devices with horizontal magnetic fields,
such as Wien filters. The precise manipulation of particle spins in storage
rings is a prerequisite for measuring the electric dipole moment (EDM) of
charged particles
Determination of Deuteron Beam Polarizations at COSY
The vector and tensor polarizations of a deuteron beam have been measured
using elastic deuteron-carbon scattering at 75.6 MeV and deuteron-proton
scattering at 270 MeV. After acceleration to 1170 MeV inside the COSY ring, the
polarizations of the deuterons were checked by studying a variety of nuclear
reactions using a cluster target at the ANKE magnet spectrometer placed at an
internal target position of the storage ring. All these measurements were
consistent with the absence of depolarization during acceleration and provide a
number of secondary standards that can be used in subsequent experiments at the
facility.Comment: 12 pages, 13 figure
Phase locking the spin precession in a storage ring
This letter reports the successful use of feedback from a spin polarization
measurement to the revolution frequency of a 0.97 GeV/ bunched and polarized
deuteron beam in the Cooler Synchrotron (COSY) storage ring in order to control
both the precession rate ( kHz) and the phase of the horizontal
polarization component. Real time synchronization with a radio frequency (rf)
solenoid made possible the rotation of the polarization out of the horizontal
plane, yielding a demonstration of the feedback method to manipulate the
polarization. In particular, the rotation rate shows a sinusoidal function of
the horizontal polarization phase (relative to the rf solenoid), which was
controlled to within a one standard deviation range of rad. The
minimum possible adjustment was 3.7 mHz out of a revolution frequency of 753
kHz, which changes the precession rate by 26 mrad/s. Such a capability meets a
requirement for the use of storage rings to look for an intrinsic electric
dipole moment of charged particles
Measurement of the Spin-Dependence of the pbar-p Interaction at the AD-Ring
We propose to use an internal polarized hydrogen storage cell gas target in
the AD ring to determine for the first time the two total spin-dependent pbar-p
cross sections sigma_1 and sigma_2 at antiproton beam energies in the range
from 50 to 450 MeV. The data obtained are of interest by themselves for the
general theory of pbar-p interactions since they will provide a first
experimental constraint of the spin-spin dependence of the nucleon-antinucleon
potential in the energy range of interest. In addition, measurements of the
polarization buildup of stored antiprotons are required to define the optimum
parameters of a future, dedicated Antiproton Polarizer Ring (APR), intended to
feed a double-polarized asymmetric pbar-p collider with polarized antiprotons.
Such a machine has recently been proposed by the PAX collaboration for the new
Facility for Antiproton and Ion Research (FAIR) at GSI in Darmstadt, Germany.
The availability of an intense stored beam of polarized antiprotons will
provide access to a wealth of single- and double-spin observables, thereby
opening a new window on QCD spin physics.Comment: 51 pages, 23 figures, proposal submitted to the SPS committee of CER
Measurement of deuteron carbon vector analyzing powers in the kinetic energy range 170-380 MeV
A measurement of vector analyzing powers in elastic deuteron-carbon
scattering has been performed at the Cooler Synchrotron COSY of
Forschungszentrum J\"ulich, Germany. Seven kinetic beam energies between 170
and 380 MeV have been used. A vector-polarized beam from a polarized deuteron
source was injected, accelerated to the final desired energy and stored in
COSY. A thin needle-shaped diamond strip was used as a carbon target, onto
which the beam was slowly steered. Elastically scattered deuterons were
identified in the forward direction using various layers of scintillators and
straw tubes. Where data exist in the literature (at 200 and 270 MeV), excellent
agreement of the angular shape was found. The beam polarization of the
presented data was deduced by fitting the absolute scale of the analyzing power
to these references. Our results extend the world data set and are necessary
for polarimetry of future electric dipole moment searches at storage rings.
They will as well serve as an input for theoretical description of polarized
hadron-hadron scattering
Measurement of the analyzing powers in (p)over-right-arrowd elastic and (p)over-right-arrown quasi-elastic scattering at small angles
The analyzing powers in proton-deuteron elastic and proton-neutron quasi-elastic scattering
have been measured at small angles using a polarized proton beam at the COSY storage ring incident on
an unpolarized deuterium target. The data were taken at 796 MeV and five higher energies from 1600 MeV
to 2400 MeV. The analyzing power in pd elastic scattering was studied by detecting the low energy recoil
deuteron in telescopes placed symmetrically in the COSY plane to the left and right of the beam whereas
for pn quasi-elastic scattering a low energy proton was registered in one of the telescopes in coincidence with
a fast scattered proton measured in the ANKE magnetic spectrometer. Though the experiment explores
new domains, the results are consistent with the limited published information
- …