학술논문
Experimental investigation of ground-state properties of $^7$H with transfer reactions
Document Type
Working Paper
Author
Caamaño, M.; Roger, T.; Moro, A. M.; Grinyer, G. F.; Pancin, J.; Bagchi, S.; Sambi, S.; Gibelin, J.; Fernandez-Dominguez, B.; Itagaki, N.; Benlliure, J.; Cortina-Gil, D.; Farget, F.; Jacquot, B.; Perez-Loureiro, D.; Pietras, B.; Raabe, R.; Ramos, D.; Tajes, C. Rodriguez; Savajols, H.; Vandebrouck, M.
Source
Subject
Language
Abstract
The properties of nuclei with extreme neutron-to-proton ratios, far from those naturally occurring on Earth, are key to understand nuclear forces and how nucleons hold together to form nuclei. $^7$H, with six neutrons and a single proton, is the nuclear system with the most unbalanced neutron-to-proton ratio known so far. However, its sheer existence and properties are still a challenge for experimental efforts and theoretical models. Here we report experimental evidences on the formation of $^7$H as a resonance, detected with independent observables, and the first measurement of the structure of its ground state. The resonance is found at $\sim$0.7 MeV above the $^3$H+4n mass, with a narrow width of $\sim$0.2 MeV and a $1/2^+$ spin and parity. These data are consistent with a $^7$H as a $^3$H core surrounded by an extended four-neutron halo, with a unique four-neutron decay and a relatively long half-life thanks to neutron pairing; a prime example of new phenomena occurring in what would be the most pure-neutron nuclear matter we can access in the laboratory.