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Neutron Numbers 8, 20 and 28 Were Considered As Magic Over Several Decades

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Neutron Numbers 8, 20 and 28 Were Considered As Magic Over Several Decades Introduction to nuclear physics with accelerated beams O. Sorlin (GANIL) What are limits of stability ? Which new phenomena emerge at the drip lines (halo, clustering, breaking mirror symetry… ) ? How do nuclear structure and shape evolve along the chart of nuclides ? How does nuclear structure change with Temperature and Spin value ? How to unify nuclear structure and reaction approaches ? How to probe the density and isospin dependence of the nuclear equation of state ? What are nuclear processes that drive the evolution of stars and galaxies in the universe ? How / where are nuclei synthesized in the universe ? Find a universal interaction, based on fundamental principles, that can model nuclear structure and reactions in nuclei and in stars (i.e. from the fm to 104 km, over 1022 orders of magnitude) Scientific council IN2P3- June 26th Accelerators, reactions and instrumentation Detectors: Charged particles: GRIT, ACTAR-TPC g-rays: AGATA, nu-ball, PARIS Facilities: spectrometer GANIL, GSI, Dubna, RIKEN, Licorne Neutron wall Stable / radioactive beams EXPAND 5 - 500 MeV/A Reactions: Fusion, transfer, Fission, knockout... A wide variety of phenemona to understand Magic nuclei Fission, pear shapes GDR Soft GMR n p Implantation Residual nuclei b, a-decay, isomeric decay Exotic decays 2n halo molecular cluster rotation- deformation Scientific council IN2P3- June 26th Nuclear physics impact many astrophysical processes X-ray bursts normal star H surface Neutron star Neutron star merger Price & Rossworg ) r s r s Abundance ( solar Sneden & Cowan 2003 Log Mass Number H. Schatz (2016) Nuclear astrophysics Energy profile of X-ray burst and nuclear physics X-ray bursts X-ray burst normal star Neutron star 10s (p,g) (a,p) b- 3a Departure from Hot CNO cycle depends crucially on 15O(a,g)19Ne reaction It is followed by (a,p), (p,g) reactions and b-decays Determination of the 15O(a,g)19Ne reaction rate Cyburt et al. ApJ 830 (2016) 15O + a 19Ne +g mainly through 3/2+ Ga + erg/s) 3/2 S NA<sv> wg [MeV] exp (-11.6 Ea[MeV]/T9) 38 15O+a a (x 10 G g wg = (2Jr+1)/2(2JT+1) x Ga Gg/(Ga+Gg) Branching Ga and Gg are needed 1/2+ 19Ne Luminosity time(s) MUGAST / AGATA array Use 15O (7Li,t) 19Ne transfer reaction to simulate a capture 15O (4.7 MeV/A) beam at 107pps from SPIRAL1 Tritons in segmented charged particle detector (MUGAST) g-rays in high efficiency/resolution (AGATA) Recoil 19Ne at focal plane of VAMOS spectrometer World-leading experience in charged-particle arrays -> GRIT Diget et al., To be performed at GANIL/VAMOS July 2019 See talk Beaumel Magic nuclei and shell evolution far from stabilty Magic numbers in the valley of stability The neutron numbers 8, 20 and 28 were considered as magic over several decades -> large gap between occupied and valence states 68Ni 40 Increase of 2+ energy at N= 8, 20,28 40 Ca 4000 3500 48 48 Ca Ca 8O 3500 6000 3000 3000 16 ) O 2500 2500 keV 4000 2000 ) ( ) + 2000 6C Ca 1500 20 Ca E(2 14Si 1500 20 2000 1000 16S 1000 500 500 0 0 0 4 6 8 10 12 12 16 20 24 22 24 26 28 30 Neutron Number Neutron Number Neutron Number Assuming our world was more neutron-rich While removing protons, the same loss of magicity occurs for all magic numbers role of proton-neutron interactions, poorly known far from stability 78Ni While deformation appears at relatively low energy, the measured 2+ of 78Ni reveals that magicity is kept at N=50 64Cr Taniuchi et al. Nature 569 (2019) 40 No sign of shell closure and magic nuclei 42 4000 Si 3500 3500 32Mg 6000 3000 3000 12Be ) 2500 8O 2500 keV 4000 2000 ) ( ) + 2000 1500 E(2 4Be 1500 2000 1000 10Ne 1000 500 12Mg 14Si 500 0 0 4 6 8 10 12 12 16 20 24 0 Neutron Number Neutron Number 22 24 26 28 30 Neutron Number Shell evolution and transfer reactions The change of magicity comes from the reduction of shell gaps and increase of correlations Probe the evolution of proton and neutron orbits far from stability using various transfer reactions 132Sn r process Shell gap Shell gap Understand shell evolution at N=82 below 132Sn for the building of the r process peak Need of charged particle detectors, gamma-arrays, as well as cryogenic targets in same cases See talk Beaumel Super Heavy Elements Motivation for studying super-heavy elements Discover the heaviest elements whose location is likely connected to spherical shell gaps whose location is unknown (Z=114, 120, 126 ?) Study their decay properties: a & fission competition Study the structure of the heavy nuclei: - Ascertain the discovery of SHE - Confront experiment to models for better predictivility of shell structure in the region Motivation for studying super-heavy elements Identify orbits in deformed nuclei to trace back to the amplitudes of the spherical shell gaps protons 126 120 7/2-[514] f5/2 (MeV) 114 108 1/2-[521] f7/2 energy 102 i13/2 100 3/2-[521] h 9/2 96 particle - 7/2+[633] 82 Single 254No 254No Quadrupole deformation Spectroscopy of the very heavy nucleus 254No g e- 208Pb(48Ca,2n)254No g g e- at the target Two isomers discovered (study at the focal plane) 254No recoil-gated254No recoil-gated et al., PRL. 97 PRL. al., et (2006) Herzberg et al., Nature442 al., et Herzberg (2006) Tandel unpublished, see also: S.Eeckhaudt,P.T.Greenlees et al.,EPJA 26 (2005) 227 254No 266 ms decay 184 ms decay 266ms isomer-gated Combine in-beam and delayed spectroscopy C. Gray-Jones, PhD theis (2008) Spectroscopy of very heavy nuclei at Dubna Spectroscopy of very heavy nuclei at Dubna K=8 8- 1293 KeV 266 ms Band on top of 8- isomer not observed in g-ray spectrum p2 or n2 state ? H.L. Liu et al., PRC 89 PRC (2014)al., et Liu H.L. Spectroscopy of very heavy nuclei at Dubna K=8 8- 1293 KeV 266 ms Band on top of 8- isomer not observed in g-ray spectrum p2 or n2 state ? H.L. Liu et al., PRC 89 PRC (2014)al., et Liu H.L. See talk Hauschild Hyperfine splitting in 253No: I(253No)=9/2 gK=-0.22(5) (confirming results from prompt & decay spectroscopy of 253No) Laser spectroscopy of the long-lived 8- isomer foreseen in 2020 @ GSI/SHIP S. Raeder et la., PRL 120 (2018) (2018) 120 PRL la., et Raeder S. See talk Jurado / Lescene Spectroscopy of very heavy nuclei at Dubna K=(16) Experiment planned end of 2019 @ Dubna (16+) 2.5 MeV 184 ms -> shed light on nature of the short-lived isomer K=8 8- 1293 KeV 266 ms Band on top of 8- isomer not observed in g-ray spectrum p2 or n2 state ? H.L. Liu et al., PRC 89 PRC (2014)al., et Liu H.L. See talk Hauschild Hyperfine splitting in 253No: I(253No)=9/2 gK=-0.22(5) (confirming results from prompt & decay spectroscopy of 253No) Laser spectroscopy of the long-lived 8- isomer foreseen in 2020 @ GSI/SHIP S. Raeder et la., PRL 120 (2018) (2018) 120 PRL la., et Raeder S. See talk Jurado / Lescene Nuclear fission Licorne (nu-ball), SOFIA & Cryring@GSI, GANIL/VAMOS Selected features related to fission Fission yields needed for societal applications Fission allows to produce neutron-rich nuclei at high J Fission competes with the synthesis of the heaviest and hyperdeformed nuclei (see talk Hauschild) prep et al.et in Evolution of fission yields show that: - Fission is mostly asymmetric Vassh - No yield enhancement at (magic) Z=50 - One fragment keeps the same Z ! Amount of Lanthanide produced in Binary Neutron Stars depends on the fission yields of very heavy nuclei No fully microscopic description so far The dynamics of nuclear fission Fission barriers probability energy Atomic number Z Fission 238U(3He,4He) n-induced JEFF Potential n-induced JENDL n-induced ENDF Elongation E* 237U (MeV) Mass number A Fission probabilities Fission-fragment yields -Sensitive to structural -Sensitive to evolution from the evolution to fission barrier barrier to scission -Most direct way to determine Nature , 564 (2018) -Role of shell effects and pairing at fission barriers extreme deformation -Neutron-induced fission cross Cimenel -The decay of the fission sections are highly important , fragments determine the residual for societal applications power of a nuclear reactor in an Scamps accidental configuration. High-precision decay-probability measurements at CRYRING Fission- Target-like fragments Dipole Beam: 107-108 stored 238 92+ 20° U at 10 A MeV Dipole Gas-jet 13 2 Target D2 10 /cm • Beam cooling & ultra-thin gas-jet target Excellent energy and position resolution of the beam, negligible straggling effects Unreacted beam Beam • Pure targets & beams 10 A •E* resolution ~200 keV, ≈100% efficiency Beam-like MeV nuclei • Simultaneous measurement of fission, g- and n- emission probabilities of many short-lived nuclei see talk Jurado High-precision fission-fragment yields with SOFIA A. Chatillon et al. Phys. Rev. C 99 (2019) 054628 E. Pellereau et al. Phys. Rev.C 95 (2017) 054603 Average neutron multiplicity • Outstanding Z and A resolution • Full identification of both fragments event-by-even • Measurement of prompt neutron mult. with Z & N UNIQUE • Access to a wide range of exotic fissioning systems See talk Jurado Nuclear deformation > Shell evolution > Hyperdeformation Nuclear shapes and deformation at N=60 Zr rotor spherical Energy (eV) 98Zr et et al., PRL 117 (2016) 110Zr Energy (meV) 100 Togashi Zr Energy (keV) GANIL/ VAMOS Does deformation persist at N=60 at Z=36 ? Zr rotor spherical Energy (eV) et et al., PRL 117 (2016) Energy (meV) Togashi Specific role of the tensor g9/2 - g7/2 pn interactions to induce deformation Energy (keV) et et al, PRL 117 (2017) Dudouet 100 200 300 400 500 600 700 800 900 Energy (keV) See Grévy Search for hyperdeformation in atomic nuclei Find the best way to produce a maximally elongated nucleus -> high angular momentum Competition between hyperdeformation / Jacobi shapes / fission Find a needle in a haystack -> requires extremely high sensitivity Expected gain in sensitivity with AGATA 4p See talk Lopez-Martens Soft and giant excitations in nuclei > Symmetry energy > Nuclear matter incompressibility Pigmy and giant dipole excitations in neutron-rich nuclei PDR GDR core n skin n p Challenges: Prove the appearance of PDR at large N/Z (few cases so far) ) Prove its E1 character.
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