A new method for searching for the electric dipole moment (EDM) of the deuteron and other nuclei is presented. When trying to measure the EDM in a storage ring environment, magnetic dipole moment ...(MDM) spin precession due to machine imperfections becomes the primary source of systematic error. The proposed method aims at providing a solution to the machine imperfection problemas well as circumventing the geometric phase error. The method is based on estimating the combined MDM + EDM spin precession frequency, in which the MDM contribution is due only to field imperfections. The MDM term is canceled in the final statistic by adding frequency estimates from cycles with counter-circulating beams. Spin precession rate depends on the particle's effective Lorentz factor; the proposed method's core feature is a procedure for equalizing the effective Lorentz factors of the clockwise and counter-clockwise circulating beams, thus enabling the cancelation.
Abstract
The search for the Electric Dipole Moments (EDM) of charged particles in storage rings necessitates polarized beams with long Spin Coherence Time (SCT) of the circulating beam. The SCT is ...the time during which the RMS spread of the orientation of spins of all particles in the bunch reaches one radian. A long SCT is needed to observe the coherent effect of a polarization build-up induced by the EDM. For deuterons the SCT of 1000 s has been achieved at the COoler SYnchrotron COSY (Jülich, Germany). Accomplishing such long SCT for protons is far more challenging due to their higher anomalous magnetic moment, but essential for the planned EDM experiments. It has been shown that for protons the SCT is strongly influenced by nearby intrinsic and integer spin resonances. The strengths of the latter have been calculated for a typical optics setting of COSY and the overall influence on the SCT was predicted. In addition, the efficiency of proton spin flipping with an RF solenoid from initially vertical direction into the ring plane is also investigated.
Abstract
A distinctive feature of the ”Quasi-Frozen Spin” mode in the synchrotron is the installation of special elements with both electrical and magnetic fields on straight sections that compensate ...spin rotation from MDM on arcs. Moreover, due to the presence of the longitudinal emittance and the momentum spread inside the beam, spin rotation may occur incoherently. In order to suppress this effect, sextupoles are installed, which also affect the suppression of chromaticity.
Methods of increasing the transition energy for the proton option of the NICA collider are investigated. The method of superperiodic modulation of quadrupole gradients is applied. The selection of ...sextupoles is carried out to suppress the natural chromaticity and compensate for the sextupole component. The Twiss parameters for the proposed structures are given, as well as the dynamic apertures and working points are investigated.
Abstract
The dynamic of longitudinal motion in Barrier Bucket RF structure is considered. To preserve the stability of the proton beam during the acceleration to the experiment energy it is necessary ...to cross the transition energy and a rapid jump of transition energy is possible. The influence of the second-order slip factor is taking into account. The dynamic aperture is investigated for various gradients of focusing quadrupoles and corresponding working points which is necessary for transition crossing.
One of the possible arguments for violating CP invariance is the existence of non-vanishing electric dipole moments (EDM) of elementary particles. To search for EDM, it was proposed to create a ...special storage ring 1, which can implement the "frozen spin" mode. An advantage of the "quasi-frozen spin" 2 concept developed by us is the ability to adapt existing storage rings to search for the deuteron EDM, in particular the accelerator complex NICA in JINR (Dubna).
The spin-orbital dynamics at the COSY accelerator has been investigated. It has been shown in the numerical experiment that spin-decoherence of the beam is determined by the nonlinear part of the ...solution of the equation of synchronous acceleration principle. It has been shown that the effects of spin-decoherence are defined by the three parameters of the lattice: horizontal and vertical chromaticity, as well as the nonlinear momentum compaction factor.
The feasibility of manipulating the beam polarization axis in a spin-transparent storage ring by means of spin-navigating solenoids has been investigated. In particular, deuteron beam spin dynamics ...in the given lattice and the lattice’s properties with respect to beam depolarization via spin decoherence have been considered.
Abstract
Experiments with polarized beams for EDM search in the NICA accelerator complex implies the design of an additional ByPass channels. Such alternative channels will make possible to use NICA ...as a storage ring and get enough statistical data.
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