We present a concept for control of the ion polarization, called a transparent spin method. The spin transparency is achieved by designing such a synchrotron structure that the net spin rotation ...angle in one particle turn is zero. The polarization direction of any ions including deuterons can be efficiently controlled using weak quasistatic fields. These fields allow for dynamic adjustment of the polarization direction during an experiment. The main features of the transparent spin method are illustrated in a figure-eight collider. The results are relevant to the electron-ion collider considered in the U.S., the nuclotron-based ion collider facility constructed in Russia, and a polarized electron-ion collider planned in China.
Small perturbative fields in a synchrotron influence both the spin and orbital motion of a stored beam. Their effect on the beam polarization consists of two contributions, a direct kick and an ...effect of the ring lattice due to orbit perturbation. Spin response function is an analytic technique to account for both contributions. We develop such a technique for the spin-transparent synchrotrons where the design spin motion is degenerate. Several perspective applications are illustrated or discussed. In particular, we consider the questions of the influence of lattice imperfections on the spin dynamics and spin manipulation during an experiment. The presented results are of a direct relevance to NICA (JINR), RHIC (BNL), EIC (BNL) and other existing and future colliders when they arranged with polarization control in the spin-transparent mode.
Hadron polarization control schemes for Spin Transparent (ST) synchrotrons are analyzed. The spin dynamics and beam polarization in such synchrotrons are controlled by spin navigators (SN) which are ...special small insertions of weak magnetic fields. An SN stabilizes the beam polarization and allows for setting any desirable spin orientation at an interaction point in the operational regime, including a frequent spin flip. We present a general approach to design of SNs. We distinguish different types of SNs, namely, those not causing closed orbit perturbation as well as those producing local and global orbit distortions. In the second case, the concept of the spin response function in an ST synchrotron is applied and expanded to reveal the effect of the SN strength enhancement by magnetic lattice of the synchrotron. We provide conceptual schemes for SN designs using longitudinal and transverse magnetic fields allowing for polarization control at low as well as high energies. We also develop the ST concept for ultra-high energies. This development may enable and stimulate interest in polarized beam experiments in possible polarized collider projects such as Large Hadron Collider (LHC), Future Circular Collider (FCC) and Super Proton Proton Collider (SPPC).
We propose a system to produce multiple spin reversals of a polarized proton beam based on orbit-steerer dipoles already installed in the Nuclotron, a superconducting synchrotron at the Joint ...Institute for Nuclear Research, when the latter operates in the spin-transparency regime. The beam momentum of 3.54 GeV/
c
corresponds to the integer spin resonance
. We report the results of numerical simulation of the proton spin dynamics pertinent to the acceleration up to
, including the adiabatic capture of spins by navigators and the subsequent multiple spin flips. A feasibility of the pilot experiment to verify our approach with the current magnetic lattice of the Nuclotron is discussed. To preserve the beam polarization during the crossing of integer resonances we propose to employ intentional resonance-strength enhancements effected by controlled variations of the beam orbit during acceleration.
A spin navigator based on correcting dipoles has been proposed to manipulate the directions of protons spins in experiments at the Nuclotron synchrotron (JINR, Dubna). The polarization is controlled ...by means of the controllable distortion of the beam closed orbit by correcting dipoles, which ensures the significant enhancement of the action of the navigator on the spins of particles. A method has been proposed to measure the coherent effect of the lattice imperfection on the spin dynamics by the navigator. An idea of a spin compensator based on correcting dipoles is presented, which allows one to eliminate the effect of the lattice imperfection on the polarization. The proposed navigator and spin compensator make it possible to perform a series of experiments at the Nuclotron to verify a new polarization control technique called the spin transparency mode. The results are relevant for experiments with polarized beams in the spin transparency regime at the NICA (Dubna, Russia) and EIC (Brookhaven, United States) and the COSY synchrotron (Julich, Germany).
The figure-8-shaped ion collider ring of Jefferson Lab Electron-Ion Collider (JLEIC) is transparent to the spin. It allows one to preserve proton and deuteron polarizations using weak stabilizing ...solenoids when accelerating the beam up to 100 GeV/c. When the stabilizing solenoids are introduced into the collider's lattice, the particle spins precess about a spin field, which consists of the field induced by the stabilizing solenoids and the zero-integer spin resonance strength. During acceleration of the beam, the induced spin field is maintained constant while the resonance strength experiences significant changes in the regions of "interference peaks". The beam polarization depends on the field ramp rate of the arc magnets. Its component along the spin field is preserved if acceleration is adiabatic. We present the results of our theoretical analysis and numerical modeling of the spin dynamics during acceleration of protons and deuterons in the JLEIC ion collider ring. We demonstrate high stability of the deuteron polarization in figure-8 accelerators. We analyze a change in the beam polarization when crossing the transition energy.
For experiments with polarized protons and deuterons, the NICA collider is planned to be used in the transparent spin mode, which is provided by two solenoid snakes. The required direction of ...polarization in the SPD detector is set by "spin navigators", which are insertions that rotate the spins at small angles. The polarization outside the SPD detector is determined by arc dipoles and the placement of snake solenoids in the collider. The kinematics of beam polarization is calculated when vertical, longitudinal or radial polarization is set in the SPD detector for different schemes of placement of snake solenoids. The results are relevant to solve the problems of injection and polarimetry for conducting experiments with polarized beams in the spin transparency mode.
The spin response function is determined by a collider's magnetic lattice and allows one to account for contributions of perturbing fields to spin resonance strengths. The depolarizing effect of an ...incoming beam depends significantly on the response function value at the interaction point (IP). We present an analytic calculation of the response function for protons and deuterons at the IP of Jefferson Lab Electron Ion Collider (JLEIC) over its whole momentum range. We find a good agreement of the analytic calculation with our numerical modeling results obtained using a spin tracking code, Zgoubi.
Two solenoid Siberian Snakes are required to obtain ion polarization in spin transparency mode of the NICA collider. The snake solenoids with a total field integral of 2×50 T·m are placed into the ...straight sections of the NICA collider. It allows one to control polarization of protons and deuterons up to 13.5 GeV/c and 4 GeV/c respectively. The snakes introduce a strong betatron oscillation coupling. The calculations of orbital parameters of proton and deuteron beams in the NICA collider with solenoid Snakes are presented.
To preserve proton polarization in the Nuclotron up to 13.5 GeV/c, it is enough to use a partial solenoid snake with maximal field integral of 25 Tm that allows one to eliminate crossings of the most ...dangerous intrinsic and integer spin resonances. The insertion of weak field integral is sufficient to preserve the proton polarization up to 3.4 GeV/c. This momentum corresponds to the first intrinsic resonance. To preserve polarization during crossings of five integer spin resonances, it is possible to choose crossing rates that correspond to either the fast or the slow resonance crossings. Another possibility is a deliberate increasing of the resonance strength. To eliminate depolarization during protons injection into the Nuclotron, a scheme of matching of the polarization with a vertical direction is presented. During the run in February-March 2017, the three measurements of the proton polarization at kinetic energies of 0.5 GeV, 1 GeV and 2 GeV were made that allow one to obtain the integer spin resonances strengths.
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