MINOS is a new apparatus dedicated to in-beam nuclear structure experiments with low-intensity exotic beams at energies above 150 MeV/nucleon. It is intended to provide increased luminosity compared ...to standard solid-target experiments in hydrogen-induced studies, while simultaneously improving experimental resolution. This work exposes the concept of the device developed at the CEA in France and reviews in detail the associated recent technical advances. MINOS is composed of a thick finger-shaped liquid hydrogen target, from 50 to 200 mm thick, combined with a compact time projection chamber serving as a vertex tracker, the first of its kind in low-energy nuclear physics. This innovative setup offers access to the first spectroscopy of a new range of very exotic nuclei beyond our current reach. An exciting program on the search for new 2 sub(1) super(+) states in neutron-rich even-even nuclei, spectroscopy of unbound oxygen nuclei and di-neutron correlations in Borromean nuclei will be performed with MINOS at the RIKEN Radioactive Isotope Beam Factory in Japan over the next few years. MINOS is funded by the European Research Council.
Excited states of ^78^Ni has been investigated at the RIBF by measuring their de-excitation !LaTeX$\gamma$-rays after one and two proton knock-out reactions from ^79^Cu and ^80^Zn beams, ...respectively, selected in the BigRIPS fragment separator. To achieve a high !LaTeX$\gamma$-ray yield, the detection system is comprised of a 10 cm-thick liquid hydrogen target with a recoil proton tracking system MINOS and a large NaI(Tl) based !LaTeX$\gamma$-ray detection array DALI2. In this presentation, the structure of ^78^Ni will be discussed with comparing the deduced exclusive reaction cross-sections to the reaction models combined with large scale shell model calculations.
Nuclear magic numbers correspond to fully occupied energy shells of protons or neutrons inside atomic nuclei. Doubly magic nuclei, with magic numbers for both protons and neutrons, are spherical and ...extremely rare across the nuclear landscape. Although the sequence of magic numbers is well established for stable nuclei, experimental evidence has revealed modifications for nuclei with a large asymmetry between proton and neutron numbers. Here we provide a spectroscopic study of the doubly magic nucleus .sup.78Ni, which contains fourteen neutrons more than the heaviest stable nickel isotope. We provide direct evidence of its doubly magic nature, which is also predicted by ab initio calculations based on chiral effective-field theory interactions and the quasi-particle random-phase approximation. Our results also indicate the breakdown of the neutron magic number 50 and proton magic number 28 beyond this stronghold, caused by a competing deformed structure. State-of-the-art phenomenological shell-model calculations reproduce this shape coexistence, predicting a rapid transition from spherical to deformed ground states, with .sup.78Ni as the turning point.
We report on the first γ-ray spectroscopy of 51,53K produced via the 52,54Ca(p,2p) reactions at ∼250 MeV/nucleon. Unambiguous final-state angular-momentum assignments were achieved for beam ...intensities down to few particles per second by using a new technique based on reaction vertex tracking combined with a thick liquid-hydrogen target. Through γ-ray spectroscopy and exclusive parallel momentum distribution analysis, 3/2+ ground states and 1/2+ first excited states in 51,53K were established quantifying the natural ordering of the 1d3/2 and 2s1/2 proton-hole states that are restored at N = 32 and 34. State-of-the-art ab initio calculations and shell-model calculations with improved phenomenological effective interactions reproduce the present data and predict consistently the increase of the E(1/21+) - E(3/21+) energy differences towards N = 40.
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