Mon·Oct 14, 2024Monday·October 14, 2024

1. 01*

   The fixed probe storage ring magnetometer for the Muon g-2 experiment at Fermi National Accelerator Laboratory

   Erik Swanson🇺🇸 · Martin Fertl🇩🇪 · Alejandro Garcia🇺🇸 · Cole Helling🇺🇸 · Ronaldo Ortez🇺🇸 · Rachel Osofsky🇺🇸 · David A. Peterson🇺🇸 · Rene Reimann🇩🇪 · Matthias W. Smith🇺🇸 · Tim D. Van Wechel🇺🇸

   The goal of the FNAL E989 experiment is to measure the muon magnetic anomaly to unprecedented accuracy and precision at the Fermi National Accelerator Laboratory. To meet this goal, the time and space averaged magnetic environment in the muon storage volume must be known to better than 70 ppb. A new pulsed proton nuclear magnetic resonance (NMR) magnetometer was designed and built at the University of Washington, Seattle to track the temporal stability of the 1.45T magnetic field in the muon storage ring at this precision. It consists of an array of 378 petroleum jelly based NMR probes that are embedded in the walls of muon storage ring vacuum chambers and custom electronics built with readily available modular radio frequency (RF) components. We give NMR probe construction details and describe the functions of the custom electronic subsystems. The excellent performance metrics of the magnetometer are discussed, where after 8 years of operation the median single shot resolution of the array of probes remains at 650 ppb.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2025)·4 citations
2. 02*

   Hole in the Deuteron

   Misak M Sargsian🇺🇸

   We introduce a new observable, $A_{node}$, that allows to isolate the node in the S-partial wave distribution of the deuteron in high $Q^2$ electro-disintegration processes with tensor polarized target. The node is a signature of nuclear repulsive core and represents a crucial test of its strength, size as well as the role of the relativistic and non-nucleonic effects in a deeply bound state. Within plane wave impulse approximation the node immitates a ``hole" through which incoming probe passes through without interaction. It is demonstrated that high $Q^2$ electro-disintegration processes due to their strong anisotropy of final state interaction effects, allow to gain an unprecedented access to the node, opening up a new venue in probing elusive dynamics of the nuclear repulsive core.

   ↳ nucl-thhep-phnucl-ex3 citations
3. 03*

   Entanglement and coherence of the wobbling mode

   Q. B. Chen🇨🇳 · S. Frauendorf

   The entanglement and coherence of the wobbling mode are studied in the framework of the particle plus triaxial rotor model for the one-quasiparticle nucleus ${}^{135}$Pr and the two-quasiparticles nucleus ${}^{130}$Ba. The focus lies on the coupling between the total and the particle angular momenta. Using the Schmidt decomposing, it is quantified in terms of the von Neumann entropy of the respective sub-systems, which measures their mutual entanglement. The entropy and the entanglement increase with spin $I$ and number of wobbling quanta $n$. The coherence of the wobbling mode is studied by means of the eigenstate decomposition of its reduced density matrix. To a good approximation, the probability distributions of the total angular momentum can be interpreted as the incoherent combination of the coherent contributions from the first two pairs of eigenvectors with the largest weight of the reduced density matrix. Decoherence measures are defined, which, in accordance, scatter between 0.1 to 0.2 at low spin and between 0.1 and 0.3 at high spin. Entanglement in the framework of the adiabatic approximation is further analyzed. In general, the coherent eigenstates of the effective collective Hamiltonian approximate the reduced density matrix with the limited accuracy of its pair of eigenstates with the largest weight. As the adiabatic approximation becomes more accurate with decreasing excitation energy, the probability distribution of the angle of the total angular momentum around a principal axis approaches the one of the full reduced density matrix. The $E2$ transition probabilities and spectroscopic quadrupole moments reflect this trend.

   ↳ nucl-thnucl-exPRC(2024)·10 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.