The Study Of Polarization Acceleration Scheme In The EicC/BRing

The polarized Electron-Ion Collider(EIC)is an ideal tool for exploring the structure of proton spin.In order to carry out fundamental scientific frontier research on the internal structure of nuclei in the sea quark energy region,a highly polarized Electronion collider in China(Eic C)is proposed by the Institute of Modern Physics,Chinese Academy of Sciences(IMP)with a center of mass energy of 15-20 Ge V while ensuring an average polarization for electrons and protons of about 80% and 70%,respectively.Maintaining the polarization is one of the key techniques in the Eic C.In spinrelated physics experiments,the effective brightness is the product of the brightness,the electron polarization,and the proton polarization.The proton beams with 70% average polarization allows the brightness to be used efficiently.In order to maintain high polarization,spin dynamics simulations and Siberian snake design are necessary.The strong depolarization resonance in a ring is the main limitation for the preparation of high-energy highly polarized proton beams.In order to determine whether it is necessary to insert a device to maintain the polarization into the BRing,the evaluation of intrinsic and imperfection depolarization resonances of the BRing is presented.The final polarization of the polarized proton beam after crossing the depolarization resonance has been calculated by a self-developed multiparticle spin-tracking program and theoretical formulations.The constant field solenoid Siberian snake is a new promising solution to maintain the beam polarization.The effect of the constant strength solenoid Siberian snake to avoid the depolarization resonance has been experimentally demonstrated.However,the BRing is an accelerator with the fast ramping rate of the dipole field 12 T/s utilizing non-resonant power supply.The magnetic field ramping rate required to keep the polarization loss to within 10% are too large.It is not suitable for the BRing.In contrast,the constant field solenoid Siberian Snake has much lower hardware requirements.A solenoid with an integration field of 0.942 Tm is installed at the electron cooling insertion of the BRing and the vertical tune of the BRing is set to 9.98.It will allow the polarization loss of the polarized proton beam injected in the optimum injection spin direction to be controlled to less than 10%,meeting the requirement of providing a 70%polarization proton beam for collision in the Eic C.