Search

The idea of the Electric Dipole Moment (EDM) search using the storage ring with polarized beam demands long Spin Coherence Time (SCT). It is the time during which the RMS spread of the orientation of spins of all particles in the bunch reaches one radian. Long SCT is needed to observe a coherent effect on polarization induced by the EDM. The possibility of getting a 1000 s SCT for deuterons has been shown experimentally at COoler SYnchrotron (COSY), accelerator at FZJ Jülich, Germany. Reaching high values of SCT for protons is more challenging due to a higher anomalous magnetic moment. Obtaining sufficient proton SCT is obligatory for planned EDM search experiments at COSY and the ProtoType EDM Ring (PTR). It has been shown that the second order momentum compaction factor (α 1) has to be optimized along with chromaticities (ξx, y ) to get high SCT. Three families of sextupoles have to be used. The optimal values of chromaticities and α 1 are discussed. The racetrack option of PTR is investigated.

The “frozen spin” method is based on the idea that at certain parameters of the ring, the particle spin rotates with the frequency of the momentum, creating conditions for the continuous growth of the electric dipole moment signal. The Nuclotron-based Ion Collider fAcility (NICA) is under construction in Joint Institute for Nuclear Research [1]. Since a straightforward implementation of the frozen spin regime at NICA is impossible, we suggest an alternative “quasi-frozen spin” concept. In this new regime, the reference particle’s spin-vector precesses with a spin phase advance π ⋅ γG/2 per beam revolution, locally recovering the longitudinal orientation at the location of the electric-magnetic elements, Wien filters, placed in the straight sections. In the deuterons case, thanks to the small magnetic anomaly G, the spin-vector continuously oscillates relative to the direction of the momentum-vector with a small amplitude of a few degrees and the expected EDM effect is reduced only by a few percent. In this paper, we study the spin-orbital motion with the aim of using the NICA collider to measure the EDM. We also comment on the potential of NICA as an axion antenna in both the quasi-frozen spin regime and beyond.

The general steps for the fabrication of a copper prototype of 325 MHz coaxial half-wave resonator (HWR) with β = 0.21 are presented and discussed in this work. The main features for the control of the electromagnetic properties during the manufacturing process of HWR are described in detail. The resonant frequency sensitivity to the accelerating gap and to the cavity height were experimentally estimated. Bead-pull measurements were performed and the electric field distribution along the beam axis of the manufactured cavity was estimated. The features of the cavity’s response in the critical coupling regime are analyzed. The experimental concept of a slow frequency tuning system (FTS) based on the moving plungers is proposed and tested. The tuning sensibility is experimentally estimated. The measured results agree with the simulations quite well, and the sensitivity for a single plunger configuration Δ f / Δ L = + 13 kHz mm−1 is achieved. The dynamic properties and operation algorithm of the FTS are studied and experimentally investigated.