The P̄ANDA Experiment at FAIR

Sfienti, C.; Peters, K.; Credé, V.; Eugenio, P.; Ostrovidov, A. I.

doi:10.1063/1.3483305

Cited by 1 publication

(2 citation statements)

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“…This further strengthen the case for measuring two neutron-rich (doubly-magic) nuclei on opposite ends of the nuclear chart. Also shown in the plot are the projected error bars for PREX-II (±0.06 fm), CREX (±0.02 fm) [8], and for a possible measurement at the Mainz Energy-Recovering Superconducting Accelerator (MESA) Facility in Mainz (±0.03 fm) [9]. Finally, we note that although most of the models displayed in the figure predict accurately the binding energy and charge radii of a variety of nuclei, they are unable to agree on whether 48 Ca or 208 Pb has the larger neutron skin.…”

Section: Neutron Skinsmentioning

confidence: 99%

“…The strong correlation of 0.979 suggests that a laboratory observable such as r 208 skin may serve as a proxy for a fundamental property of the EOS. Also shown in the plot are anticipated errors for PREX-II and for the corresponding experiment at the proposed MESA facility [9]. An experiment with such a small error bar could significantly constrain the slope of the symmetry energy.…”

Section: Neutron Starsmentioning

confidence: 99%

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Neutron skins and neutron stars

Piekarewicz¹

2013

AIP Conference Proceedings

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Abstract. The neutron-skin thickness of heavy nuclei provides a fundamental link to the equation of state of neutron-rich matter, and hence to the properties of neutron stars. The Lead Radius Experiment ("PREX") at Jefferson Laboratory has recently provided the first model-independence evidence on the existence of a neutron-rich skin in 208 Pb. In this contribution we examine how the increased accuracy in the determination of neutron skins expected from the commissioning of intense polarized electron beams may impact the physics of neutron stars.Keywords: Neutron distributions, neutron stars PACS: 21.10. Gv, 21.65.Cd, 25.30.Bf, 26.60.Kp NEUTRON SKINSThe Lead Radius EXperiment ("PREX") at the Jefferson Laboratory has used parity-violating electron scattering to probe the weak-charge density of 208 Pb [1,2]. Given that the weak charge of the neutron is much larger than that of the proton, parity-violating electron scattering provides a clean probe of neutron densities that is free from strong-interaction uncertainties [3]. By invoking some mild assumptions, PREX provided the first largely modelindependent determination of the neutron radius (R n ) of 208 Pb. Since charge radii of stable nuclei are known with exquisite accuracy [4], PREX effectively provided the first clean evidence in favor of a neutron-rich skin in 208 Pb [1, 2]:(1)Although PREX demonstrated excellent control of systematic errors, unforeseen technical problems resulted in time losses that significantly compromised the statistical accuracy of the measurement. Fortunately, the PREX collaboration has made a successful proposal for additional beam time, so that the original 1% goal (±0.06 fm) may be attained [5]. Given that PREX demonstrated that model-independent measurements of weak-charge densities are now feasible, it is pertinent to ask whether a measurement in a different neutron-rich nucleus could prove advantageous. Indeed, the case of 48 Ca seems particularly attractive for several reasons. First, 48 Ca is a doubly-magic nucleus that is already within the reach of ab-initio calculations [6]. Thus, the Calcium Radius EXperiment ("CREX") could provide a critical bridge between ab-initio approaches and density-functional theory, that remains as the sole theoretical alternative for the calculation of the properties of medium to heavy nuclei. Second, by providing this kind of bridge, CREX will help elucidate the character of the three-nucleon force, which plays a critical role in determining the limits of nuclear existence. Finally, CREX together with PREX-II will provide calibrated anchors for hadronic measurement of neutron skins at radioactive beam facilities. In essence, PREX-II in combination with CREX will place much-needed constrains on the poorly-known isovector sector of the nuclear energy density functional, namely, that sector in which protons and neutrons contribute with opposite sign. Note that a typical example of such a quantity is the isovector density ρ 1 = ρ p −ρ n which-unlike the isoscalar density ρ 0 = ρ p +ρ n -is fair...

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Section: Neutron Skinsmentioning

confidence: 99%

Section: Neutron Starsmentioning

confidence: 99%