Congresso del Dipartimento di Fisica Highlights in Physics –14 October 2005, Dipartimento di Fisica, Università di Milano Study of exotic nuclei with radioactive beams O. Wieland Dipartimento di Fisica, Università di Milano; INFN – Sezione di Milano Nuclear physics under extreme conditions How exotic nuclei are produced and measured Milano University and INFN Milano A.Bracco, G.Benzoni, N.Blasi, F.Camera, S.Leoni, B.Million, M.Pignanelli,O.Wieland
Neutron number Proton number Terra Incognita Fe r-Process rp-Process Nuclei at the drip lines Very large proton-neutron asymmetries New Resonant excitation modes Neutron, Proton Decay Shell structure in nuclei Structure of doubly magic nuclei Test of (new)symmetries +... Nuclear shapes Exotic shapes and isomers Hyperdeformation Coexistence and transitions Heavy Nuclei Shell stabilization Shell evolution and SUPER Heavy Developement of radioactive beams to access exotic nuclei
The ISOL production Method (very) Thick targets Stopped reaction products “Chemistry” dependence (extraction) High quality post-accelerated RIB beam Life-time > 100 ms 1 GeV/u p,.. C… Heavy Ions projectile Isotope Separation On Line
Ion Source In-flight or Fragmentation Method Heavy ion production beam “Thin” target RIB utilizes production beam momentum No species dependence “Fast” measurements “in flight” Projectile Fragmentation and Fission BEAM TARGET Fragments For short lifetimes <1 s GeV/u complementare insieme con ISOL
Types of reactions used for „in flight -spectroscopy“ Relativistic Coulomb excitation (large cross section of ca. 100 mb & thick targets) - first excited 2 + states => B(E2) - excitation of Giant Resonances Secondary fragmentation - excited states at higher spins and higher excitation energy
EE E K Cl Ar P S Ca Si Mg Na Al HECTOR Relativistic Coulomb Scattering of neutron rich isotopes Primary Beam 86 Kr (10 9 pps) 400…700 MeV/u (~ 10 3 pps) 100 MeV/u 37 Ca (85 %) 2*10 3 p/sec 36 K ( 14 %) 38 Ca ( <1 %) Z=19 Z=20 INCOMINGOUTGOING POSITION + timegate Selection, identification and tracking of the Isotop cocktail
RISING detectors v/c fino a 0.8 Target : Au or Be Beam Milano
RISING detectors v/c fino a 0.8 collettivita’ (B(E2) dello stato 2 + nel 56 Cr e’ minore di quella dei nuclei vicini Evidenza della chiusura di una nuova sottoshell a N=32 ? Phys.Lett.B622(2005)29 After doppler correction
Future RIB facilities in Italy, Europe, WORLDWIDE Next step: Next generation spectrometers based on years of worldwide R&D Segmentation of the HPGe detector cristals and gamma-ray tracking AGATA the ultimate gamma-ray spectrometer Higher efficiency Higher selectivity,sensitivity Higher position resolution For measuring gamma rays Is needed !!! Next generation spectrometer based on gamma-ray tracking Based on years of worldwide R&D No suppression shields 4 germanium array Very high efficiency and spectrum quality Stable, radioactive beams, low-high velocities
Basic ingredients of AGATA Pulse Shape Analysis to decompose recorded waves Highly segmented HPGe detectors · · Identified interaction points (x,y,z,E,t) i Reconstruction of tracks evaluating permutations of interaction points Digital electronics to record and process segment signals Reconstructed gamma-rays Milano AGATA group See poster
AGATA Advanced GAmma Tracking Array 4 - Array of segmented HPGe 180 hexagonal crystals3 shapes each crystal is segmented in 36 sectors each crystal is encapsulated 60 triple-clusters all equal Inner radius (Ge) 23.5 cm Solid angle coverage 82 % More than 6000 segments Amount of germanium 362 kg v/c=45% Lots of technological development has to be done
SPIN benefits other than intellectual, cultural, scientifical, philosophical, … Medicine (tracking new imaging techniques, low irradiation methods) National Safety (tracking source location) Environment science non destructive analysis space science off ? Mars Odyssey Gamma-Ray Spectrometer Water/Ice on Mars ? INTEGRAL SATELLITE - INTERNATIONAL GAMMA RAY ASTROPHYSICS LABORATORY Germanium Encapsulation technique
Milano Nuclear Structure Group