the RHIC storage ring. The first stage for ions is the electron beam ion source (EBIS), while for protons, the linear accelerator (Linac) is used. As an example, gold nuclei leaving the EBIS have a kinetic energy of per nucleon and have an electric charge Q = +32 (32 of 79 electrons stripped from the gold atom). The particles are then accelerated by the Booster synchrotron to per nucleon, which injects the projectile now with Q = +77 into the Alternating Gradient Synchrotron (AGS), before they finally reach per nucleon and are injected in a Q = +79 state (no electrons left) into the RHIC storage ring over the AGS-to-RHIC Transfer Line (AtR). To date the types of particle combinations explored at RHIC are , , , , , , , , , and . The projectiles typically travel at a speed of 99.995% of the speed of light. For collisions, the center-of-mass energy is typically per nucleon-pair, and was as low as per nucleon-pair. An average luminosity of was targeted during the planning. The current average luminosity of the collider has reached , 44 times the design value. The heavy ion luminosity is substantially increased through stochastic cooling. One unique characteristic of RHIC is its capability to collide polarized protons. RHIC holds the record of highest energy polarized proton beams. Polarized protons are injected into RHIC and preserve this state throughout the energy ramp. This is a difficult task that is accomplished with the aid of corkscrew magnetics called 'Siberian snakes' (in RHIC a chain 4 helical dipole magnets). The corkscrew induces the magnetic field to spiral along the direction of the beam Run-9 achieved center-of-mass energy of on 12 February 2009. In Run-13 the average luminosity of the collider reached , with a time and intensity averaged polarization of 52%. AC dipoles have been used in non-linear machine diagnostics for the first time in RHIC. The experiments There is one detector currently operating at RHIC: STAR (6 o'clock, and near the AGS-to-RHIC Transfer Line). PHENIX (8 o'clock) took last data in 2016. PHOBOS (10 o'clock) completed its operation in 2005, and BRAHMS (2 o'clock) in 2006. A new detector sPHENIX is under construction in the old PHENIX hall and is expected to begin collecting data in 2023. Among the two larger detectors, STAR is aimed at the detection of hadrons with its system of time projection chambers covering