The Jülich Electric Dipole moment Investigation (JEDI) collaboration aims at a direct measurement of the Electric Dipole Moment (EDM) of protons and deuterons using a storage ring. The measurement is based on a polarization measurement. In order to reach highest accuracy, one has to know the exact trajectory through the magnets, especially the quadrupoles, to avoid the influence of magnetic fields on the polarization vector. In this paper, the development of a beam-based alignment technique is described that was developed and implemented at the COoler SYnchrotron (COSY) at Forschungszentrum Jülich. Well aligned quadrupoles permit one to absolutely calibrate the Beam Position Monitors (BPMs). The method is based on the fact that a particle beam, which does not pass through the center of a quadrupole, experiences a deflection. The precision reached by the method is approximately 40μm. Some consequences for the design of a new high precision storage ring for EDM mesasurements are discussed.
A calorimetric polarimeter based on inorganic LYSO scintillators is described. It has been designed for use in a storage ring to search for electric dipole moments (EDM) of charged particles such as the proton and deuteron. Its development and first use was on the Cooler Synchrotron (COSY) at the Forschungszentrum Jülich with 0.97 GeV/c polarized deuterons, a particle and energy suitable for an EDM search. The search requires a polarimeter with high efficiency, large analyzing power, and stable operating characteristics. With typical beam momenta of about 1 GeV/c, the scattering of protons or deuterons from a carbon target into forward angles becomes a nearly optimal choice of an analyzing reaction. The polarimeter described here consists of 52 LYSO detector modules, arranged in 4 symmetric blocks (up, down, left, right) for energy determination behind plastic scintillators for particle identification via energy loss. The commissioning results of the current setup demonstrate that the polarimeter is ready to be employed in a first direct measurement for an EDM on the deuteron, which is planned at COSY.
Various scenarios of measurements of Electric Dipole Moment (EDM) of light hadrons with the use of a storage ring were proposed. Most of these methods are based on the measurement of the vertical spin component for an initially horizontal polarized beam. Since the expected EDM effect is very small, one has to payattention to various sources of systematic uncertainties. One of the most important sources are misalignments of the magnets forming the storage ring lattice, which may produce an effect that mimics an EDM. This false signal could be much larger than the expected EDM signal, even for very small magnet misalignments. This paper describes a novel method for the determination of the contribution of magnets misalignments to the expected EDM signal. It is shown that the magnitude of this effect could be estimated via a Fourier analysis of the time-dependent vertical polarization. This could be achieved by sampling the vertical polarization with a frequency larger than the beam revolution frequency, which corresponds to polarization measurements in at least two positions in the storage ring. The presented method can be applied to any scenario proposed for EDM measurements using a storage ring.
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