Precision Measurement of 11Li moments: Influence of Halo Neutrons on the 9Li Core

TL;DR

This study precisely measures the electric quadrupole and magnetic moments of the 11Li halo nucleus, revealing significant insights into how halo neutrons influence the core's properties and challenging existing nuclear models.

Contribution

It provides high-precision measurements of 11Li moments and compares these results with various nuclear models, highlighting discrepancies and the need for improved theories.

Findings

Measured quadrupole moment: 33.3(5) mb

Measured magnetic moment: 3.6712(3) μ_N

Observed an 8.8(1.5)% increase in quadrupole moment compared to 9Li

Abstract

The electric quadrupole moment and the magnetic moment of the 11Li halo nucleus have been measured with more than an order of magnitude higher precision than before, |Q| = 33.3(5)mb and mu=3.6712(3)mu_N, revealing a 8.8(1.5)% increase of the quadrupole moment relative to that of 9Li. This result is compared to various models that aim at describing the halo properties. In the shell model an increased quadrupole moment points to a significant occupation of the 1d orbits, whereas in a simple halo picture this can be explained by relating the quadrupole moments of the proton distribution to the charge radii. Advanced models so far fail to reproduce simultaneously the trends observed in the radii and quadrupole moments of the lithium isotopes.