Strong evidence for 9N and the limits of existence of atomic nuclei

TL;DR

This paper presents strong evidence for the existence of the exotic isotope 9N, which has an extreme proton-to-neutron ratio and may be the first known five-proton emitter, highlighting the limits of nuclear stability.

Contribution

It provides experimental evidence for 9N, an extremely proton-rich isotope, and discusses its potential as the first five-proton emitter, expanding understanding of nuclear boundaries.

Findings

Evidence of 9N confirmed through invariant-mass spectrum analysis.

Decay spectrum shows two peaks consistent with theoretical models.

Possibility of a single resonance peak remains unresolved.

Abstract

The boundaries of the Chart of Nuclides contain exotic isotopes that possess extreme proton-toneutron asymmetries. Here we report on strong evidence of 9N, one of the most exotic proton-rich isotopes where more than one half of its constitute nucleons are unbound. With seven protons and two neutrons, this extremely proton-rich system would represent the first-known example of a ground-state five-proton emitter. The invariant-mass spectrum of its decay products can be fit with two peaks whose energies are consistent with the theoretical predictions of an open-quantum-system approach, however we cannot rule out the possibility that only a single resonance-like peak is present in the spectrum.