Polarized proton beam acceleration at the Nuclotron with the use of the solenoid Siberian Snake
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olarized Proton Beam Acceleration at the Nuclotron with the Use of the Solenoid Siberian Snake1 Yu. N. Filatovb, A. D. Kovalenkoa, A. V. Butenkoa, A. M. Kondratenkoc, M. A. Kondratenkoc, and V. A. Mikhaylova aJoint
Institute for Nuclear Research, Dubna, 141980 Russia Moscow Institute of Physics and Technology, Dolgoprudny, 141700 Russia cScientific and Technical Laboratory “Zaryad”, Novosibirsk, 630090 Russia b
Abstract—The possibility of polarized protons acceleration up to 6 GeV at the Nuclotron is analyzed. Proton beam acceleration by application of full and partial Siberian Snakes are considered. Compensation of the betatron coupling introduced by the solenoids is done by a compact insert of quadrupoles with a certain sym metry of their tilt angles around the orbit direction. Such a scheme has a shorter total length of the quadru poles than the known compensation schemes. The Snakes installed within one, 3.2 m long, or two, 2 × 3.2 m long, straight sections of the Nuclotron lattice are considered. DOI: 10.1134/S1063779614010274 1
In papers [1, 2] the problems of polarized deuteron and proton beam acceleration at the JINR Nuclotron were considered. It have been shown that acceleration of polarized protons meet big problems due to numer ous spin resonances. In this paper the application of Siberian Snake in the Nuclotron up to energy of 6 GeV is considered. Solving this problem will make it possi ble to use the Nuclotron as the NICA collider injector in polarized proton mode and to increase substantially the intensity of polarized proton beam for fixed target experiments. The calculations are shown, the main reason of the beam depolarization in the “proton case” is coming from the effect of spin resonances crossing. The dependences of the linear spin resonances strength normalized to the value wd = 7.3 × 10–4, which corre sponds to complete depolarization at the Nuclotron guiding magnetic field ramp dB/dt = 1 T/s, on the beam kinetic energy are presented in Fig. 1. Three areas are marked at each plot corresponding to “fast” (under dashed line), “adiabatic” (above the solid line) and “intermediate crossing” (between dashed and solid lines). Dangerous resonances are in intermediate area, they are marked with black points [2]. At the maximum kinetic energy of 5 GeV there are 4 integer, 2 nonsuperperiodic and 2 coupling danger ous resonances. To preserve polarization it is possible to use a sole noidal Siberian Snake which allow to avoid the closed orbit displacement. The maximum magnetic field integral of the Snake depends on the particle momen 1 The article is published in the original.
tum and approximately equal to 21 T m at γ = 6, where γ is Lorenzfactor. It is not necessary to use a full Snake to suppress the influence of spin resonances. One can use partial Snake, which requires less longitudinal magnetic field integral. The spin tune ν depends both on energy and on spin rotation angle in the solenoid ϕz when the lon gitudinal field introduced in the synchrotron straight section ϕ cos ( πν ) = cos
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