arXiv subjects

A. Marusic

Publications and source records attributed to A. Marusic.

6 recordsLinked to original sources

arXiv2019

Measurement of the Spin Tune Using the Coherent Spin Motion of Polarized Proton in a Storage Ring

This paper reports the first spin tune measurement at high energies (24 GeV and 255 GeV) with a driven coherent spin motion. To maintain polarization in a polarized proton collider, it is important to know the spin tune of the polarized proton beam, which is defined as the number of full spin precessions per revolution. A nine-magnet spin flipper has demonstrated high spin-flip efficiency in the presence of two Siberian snakes [1]. The spin flipper drives a spin resonance with a given frequency (or tune) and strength. When the drive tune is close to the spin tune, the proton spin direction is not vertical anymore, but precesses around the vertical direction. By measuring the precession frequency of the horizontal component the spin tune can be precisely measured. A driven coherent spin motion and fast turn-by-turn polarization measurement are keys to the measurement. The vertical spin direction is restored after turning the spin flipper off and the polarization value is not affected by the measurement. The fact that this manipulation preserves the polarization makes it possible to measure the spin tune during operation of a high energy accelerator.

physics.acc-ph↗

arXiv2016

High energy Coulomb-scattered electrons for relativistic particle beam diagnostics

A new system used for monitoring energetic Coulomb-scattered electrons as the main diagnostic for accurately aligning the electron and ion beams in the new Relativistic Heavy Ion Collider (RHIC) electron lenses is described in detail. The theory of electron scattering from relativistic ions is developed and applied to the design and implementation of the system used to achieve and maintain the alignment. Commissioning with gold and 3He beams is then described as well as the successful utilization of the new system during the 2015 RHIC polarized proton run. Systematic errors of the new method are then estimated. Finally, some possible future applications of Coulomb-scattered electrons for beam diagnostics are briefly discussed.

physics.acc-ph↗

arXiv2004

Measurement of Inverse Pion Photoproduction at Energies Spanning the N(1440) Resonance

Differential cross sections for the process pi^- p -> gamma n have been measured at Brookhaven National Laboratory's Alternating Gradient Synchrotron with the Crystal Ball multiphoton spectrometer. Measurements were made at 18 pion momenta from 238 to 748 MeV/c, corresponding to E_gamma for the inverse reaction from 285 to 769 MeV. The data have been used to evaluate the gamma n multipoles in the vicinity of the N(1440) resonance. We compare our data and multipoles to previous determinations. A new three-parameter SAID fit yields 36 +/- 7 (GeV)^-1/2 X 10^-3 for the A^n_1/2 amplitude of the P_11.

nucl-ex↗

arXiv2004

Does the Sigma(1580)3/2- resonance exist?

Precise new data for the reaction $K^- p \to π^0 Λ$ are presented in the c.m. energy range 1565 to 1600 MeV. Our analysis of these data sheds new light on claims for the $Σ(1580){3/2}^-$ resonance, which (if it exists with the specified quantum numbers) must be an exotic baryon because of its very low mass. Our results show no evidence for this state.

nucl-ex↗

arXiv2001

RHIC Power Supply Ramp Diagnostics*

Reliable and reproducible performance of the more than 800 Relativistic Heavy Ion Collider (RHIC) magnet power supplies is essential to successful RHIC operation. In order to support power supply commissioning, a system was developed to capture detailed power supply measurements from all the RHIC ring power supplies during acceleration ramps. Diagnostic tools were developed to allow experts to assess ramp reproducibility and rapidly identify problems. The system has now become a routine part of RHIC operations, with data captured for every acceleration ramp. This paper describes the RHIC power supply ramp diagnostic system and considers its impact on RHIC operations.

physics.acc-ph↗

arXiv2001

Post Mortem System - Playback of the RHIC Collider

A Post Mortem System was developed for the Relativistic Heavy Ion Collider at Brookhaven National Laboratory to provide a playback of the collider state at the time of a beam abort, quench, or other failure event. Post Mortem data is used to provide diagnostics about the failure and to improve future stores. This data is read from hardware buffers and is written directly to the main file system by Accelerator Device Objects in the front-end computers. The Post Mortem System has facilitated analysis of loss monitor and power supply data, such as beam loss during magnet quenches, dump kicker misfires and power supply malfunctions. System details and recent operating experience will be discussed.

physics.acc-ph↗