The Relativistic Heavy Ion Collider (RHIC) Run 24 was 27 weeks, operating with collisions at the STAR and sPHENIX detectors. The secondary running mode was gold at 100 GeV/u, where there was 3 weeks of operation. The goals of this run were to: reach an intensity of 1.8e9 ions/bunch and fully commission the 56 MHz cavity, ensure sPHENIX systems are ready for Run25,and deliver 1-2e9 minimum bias events for STAR. Beam was delayed 1 week due to two simultaneous failures of essential kicker systems: an AGS extraction bump power supply, and the yellow RHIC abort kicker. Elevated backgrounds at sPHENIX’s MAPS-based VerTeX (MVTX) detector required extensive studies and diagnostics. With a combination of local steering at sPHENIX and a large amplitude bump in the sector 10 and 12 arcs, the background levels with 12 bunches were reduced by a factor of 18. STAR was able to collect over 1.5e9 minimum bias events and the 56 MHz cavity was operated near its full voltage at 700 kV with 1.3e9 ions/bunch. This paper provides a summary of the run and details of the background studies.

Local coupling correction in Interaction Regions (IRs) and global coupling correction based on Base-Band Tune (BBQ) measurement have been performed routinely for RHIC operation. However, one still observes significant residual local coupling measured by beam position data. For the Electron-Ion Collider (EIC) project, betatron decoupling for the hadron beam needs to be improved to maintain a large horizontal to vertical beam emittance ratio (12:1). In this paper, we will analyze the cause for noticeable residual coupling in RHIC and propose an integrated local and global betatron coupling correction based on beam position measurements. We will also present experimental results from ML-based optimization of the local and global coupling in RHIC.

One of the issues that the AuAu 100 GeV physics program in 2024 in RHIC encountered was background in the sPHENIX MVTX detector, which causes autorecoveries and preventing continuous data taking. Beam studies and track simulations performed to understand the source of the background and potential measures to control it have led to the conclusion that off-momentum particle loss was an issue. This article will focus on a proposal of a momentum collimator in warm sections in RHIC to control the MVTX background. We will elaborate the selection of the locations for the collimator, the strategy of generating substantial horizontal dispersion there, the required additional powering scheme for selected quads and the optimization of the figure-of-merit for momentum collimation.

Single-sextupole and single-octupole lattices ``exhibit .. all the typical properties of more complicated mappings and dynamical issues'', including horizontal resonances of all orders $N$ with island tunes $Q_I$. In general both island tune response spectra and tune modulation drive spectra have multiple lines. Stable motion in transverse phase space is compromised when a pair of drive and response lines align. This vulnerability is illustrated by realistic examples from the Relativistic Heavy Ion Collider.

An Accelerator Physics Experiment (APEX) was conducted in the Relativistic Heavy Ion Collider (RHIC) to verify the formation, rotation, and size of resonance islands.The experiment provides lattice parameters to be used to facilitate an alternative method of transition crossing in the Hadron Storage Ring (HSR) of the Electron Ion Collider (EIC) project by producing a non-adiabatic kick to the off-axis beam within the island to displace the beam to the central closed orbit across transition. Proton beam was injected directly into an octupolar field driven stable resonance island in RHIC. This paper describes the procedures used to perform this Resonance Island Injection (RII) and discusses the experimental results.

A stored proton beam may become unstable when the horizontal tune slowly approaches a quarter integer resonance.This paper discusses this phenomenon in the context of an Accelerator Physics Experiment that was conducted in the Relativistic Heavy Ion Collider, in which the horizontal tune was ramped through a fractional tune of 0.75 in the presence of strong octupolar fields.

This paper presents turn-by-turn observations of internal and external filamentation within the Poincare contours of a fourth order resonance during an Accelerator Physics Experiment (APEX) in the Relativistic Heavy Ion Collider (RHIC). Beam position monitors measured the turn-by-turn evolution of the center-of-charge of the captured beam. The fraction of beam outside the island soon comes to contribute marginally to the center-of-charge signal. Simulation results are compared with experimental data.

Two types of beam abort mechanisms, namely, the External Abort System and the Internal Abort System for the Electron Ion Collider (EIC) Electron Storage Ring (ESR) are devised, designed and compared. Both mechanisms will be located in the Interaction region 2 (IR2). The External Abort System utilizes the ISABELLE Spectrometer tunnel to facilitate an extraction beamline and a beam dump, and the Internal Abort System generates a local orbit bump within the storage ring lattice to guide the electron beam into the beam dump. This article discusses the design of both systems, including the orbit bump design and ESR lattice modification, the resonant AC dipole design for the Internal Abort System, lattice simulation, the beam dump design and simulations using FLUKA, beampipe vacuum and impedance considerations near the beam dump.