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Rewriting nuclear physics books. Jose Javier Valiente Dobón Laboratori Nazionali di Legnaro (INFN), Italia. Unraveling the nuclear many-body problem. J π. …. Nuclear moments. γ energy. Radii. Cross sections σ. Spectroscopic factors. Transition probability : B(M1), B(E2), etc.
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Rewriting nuclear physics books Jose Javier Valiente Dobón Laboratori Nazionali di Legnaro (INFN), Italia
Unravelingthe nuclear many-bodyproblem Jπ … Nuclearmoments γ energy Radii Cross sections σ Spectroscopic factors Transitionprobability: B(M1), B(E2), etc • Stablebeams: LNL-INFN (Italia), LNS-INFN (Italia), GANIL (France) • Radioactivebeams: ISOLDE (CERN), RIKEN (Japan), MSU (USA), GANIL-SPIRAL1 (France), CERN-ISOLDE (Switzerland), GSI (Germany), SPES (LNL)
J J j j j j 8+ 21/2 6+ 4+ 13/2 2+ 0+ 7/2 147Gd 158Er Many-bodyquantalsystems E(MeV) Near Spherical Deformed Single-particlebehaviour. Collectivebehaviour. Nuclei are many-bodyquantalsystemsconsistingonmanynucleons, up to 300, resultingon a richvariety of quantum phenomena.
NOBEL 1963 Maria GoeppertMayer 1906 - 1972 PR75, 1969 (1949) J. Hans D. Jensen (1907 – 1973) PR75, 1766 (1949) “On closed shells in nuclei” Mayer et al., PR75, 1969 (1949) & Jensen et al., PR75 1766 (1949)
Signature of magicity High excitationenergy of the 2+ state. Large B(E2) Small B(E2) Small B(E2)
B(E2) values Indication of shell gaps B(E2: Ji→Jf) = 1/(2Ji +1)‹ψf ||E2|| ψi›2 Z=20 Z=28
Electromagnetic radiation • Electromagneticradiation: consistsof oscillatingelectric and magneticfields • Oscillantingcharge Eoscill. Boscill. • Oscillating moment or current Boscill. Eoscill. Radiationtype E Radiationtype M Angularmomentum and parity: conservationbetweenradiantsystem and radiationfield (photon) Photon: angular moment L (L > 0) (do not exist photons with L = 0) L = 1 dipole L = 2 quadrupole L = 3 ottupole L = 4 esadecapole General radiation: EL o ML (E1, E2,….) (M1, M2, …) IfIi and If are the angulamomentum of the nuclearstatesinitial and final then
Anti-Compton Raggio gamma GAMMASPHERE Cristalli di germanio GASP Gamma Spectrometers LNL Gamma spectrometersbased on detectors suppressed by anti Compton ANL
AntiCompton shield low Z=32 →Compton scattering dominates above 180 keV → peak–to–total ratio ~20–30% (even for large crystals) • To improve the response function in the 70’s was developed the anti-Compton shield. • For large volume crystals Peak/Total ratio improved from ~20% to ~60% • Drawback: part of the solid angle is used by the shield detector BGO (AntiCompton)
Evolution of the γ spectrometers History of the spectroscopy: Rotational band of 156Dy The technicaldevelopmenthasallowedus to reach a deeperunderstanding of the nucleus. Time AGATA @ LNL GRETINA @ LBNL
How to create exotic nuclear matter? • Stable beams • Transfer reactions (d,p - d,t – α,t, …) • • Fusion-evaporation (proton dripline) • • Deep inelastic reactions (towards neutron drip line) • Fission (towards neutron drip line) • Radioactive beams • • Fragmentation (proton and neutron drip line) • Isotope Separation On Line (ISOL) (238U fission towards neutron drip line) • Di Pietro • R. Raabe
1 2 3 4 n Reaction fusion-evaporation a p An example: Fusion-evaporation • Nuclear reaction: fusion-evaporation • The radiation emitted during the decay process reveals the fundamental excitations of atomic nuclei : collective properties, single-particle degrees of freedom, pairing correlations, etc . • Our microscope is the gamma spectrometer + ancillary detectors
Neutron detectors • Di Pietro has explained already the detectors for charged particles While bound neutrons in stable nuclei are stable, free neutrons are unstable they undergo beta decay with a lifetime of just under 15 minutes No electriccharge no directatomicionization onlycollisions and reactions with nuclei 10-6 weakerabsorptionthanchargedparticles • The processeswilldepend on the availableenergy: • En ~1/40 eV (=KBT) Slow diffusion, capture by nuclei • En < 10 MeVElasticscattering, capture, nuclearreactions/excitation • En > 10 MeVElastic+Inelasticscattering, variousnuclearreactions
Spectrometers for heavy ions Magnetic separation : qvB = mv2/r Magnetic rigidity Br = mv/q = p/q where B is magnetic field, ρ is the curvature radius, p is momentum, v is velocity and q is charge of the particle A dipole magnet is the ion-optical equivalent of a prism Large magnetic spectrometers to identify in A, Z and β event by event. Need of accurate deetctors for heavy ions Gas detectors
Nuove frontiere: il vostro futuro … Proton drip line Superheavy Neutrondrip line • Quali sono i limiti dell'esistenza della materia nucleare: posizione delle drip-lines? • Come si sviluppano le nuove zone di deformazione e i nuovi numeri magici? • Quali fenomeni emergono nei nuclei debolmente legati? • Il modello a shell potrà rappresentare anche per il futuro un framework teorico capace di spiegare allo stesso tempo sia i sistemi nucleari a pochi corpi che quelli a molti corpi? • inclusione di una forza a 3 corpi • Accoppiamento con il continuo • Necessità di consistenza dei calcoli di struttura con quelli di meccanismi di reazione • Gli sviluppi e i progressi della struttura nucleare sono importanti ed essenziali per altri campi come ad esempio l’astrofisica nucleare.
Some books of interest (exp.): • Radiation Detection and measurement G.F. Knoll – John Wiley & Sons Inc. • Introductory Nuclear Physics K.S. Krane - John Wiley & Sons Inc. • In-beam gamma-ray spectroscopy H. Morinaga and T. Yamazaki – North-Holand publishing company • Nuclear structure from a simple perspective R. Casten – Oxford University press • Nuclear structure A. Bohr and B. Mottelson - Benjamin, Reading, MA, 1975, Vol. I and II.