New way was found to increase the stability field of particle’s motion for 1,5 times at the NICA collider

News, 11 June 2019

A group of scientists from the Institute of Nuclear Physics SB RAS and the Joint Institute for Nuclear Research carried out the optimization of the dynamic aperture, i.e. the field of the stable motion of particles in the magnet structure of the NICA collider.

According to the calculations, it is possible to widen this area for 1,5-2 times. The results are published in the “Pepan letters” journal and have been presented at the International Machine Аdvisory Сommittee (MAC) on the NICA project. The work was conducted with the support of the Russian Science Foundation.

“The NICA collider is a unique facility,” Head of the Department of Superconducting Magnets and Technologies of the Laboratory of High Energy Physics Sergey Kostromin comments. “The magnet technology, small perimeter, demands to colliding beams: all this makes the machine complicated in terms of physics and accelerator technology. The effects of nonlinearity, such as fringed fields of quadrupole magnets, significantly influence the dynamics of circulating beams. A group of the collider’s developers also carries out similar calculations in JINR. We closely cooperated with the INP in this field. According to the results obtained by both groups, we will choose the configuration and settings of the system for correction of fringed fields influence in the collider.”

The dynamic aperture of particles in the NICA collider is affected by sextupole magnets, which correct a so-called natural chromatism, and nonlinear fringed fields of quadruple lenses. Particularly the latter ones turned out to be obstructions that limit the dynamic aperture of the NICA collider. Moreover, final focus lenses of beams before the collision point influence the most.

The authors of the article propose to add 8 octupole magnets to the accelerating structure of the NICA complex: to place two of them at each side from the collision point of beams, near lenses of final focus. Due to the author’s calculations, it will help to increase the field of the stable motion for 1,5-2 times. Octupole lenses have components of the field similar to fringed fields of quadruple lenses. If octupole lenses are selected in a certain way, then it will be possible to negate the harmful influence of edges of quadruple lenses on the field of the stable motion of the beam.