Congresso del Dipartimento di Fisica Highlights in Physics

Congresso del Dipartimento di Fisica Highlights in Physics 2005 11– 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

Shell structure in nuclei • Structure of doubly magic nuclei Test of (new)symmetries Nuclei at the drip lines • Very large proton-neutron asymmetries Nuclear shapes • New Resonant excitation modes • Exotic shapes and isomers • Neutron, Proton Decay • Hyperdeformation +. • Coexistence and transitions . . Heavy Nuclei Shell stabilization Shell evolution a SUPER Heavy itand n g co Proton number n I a r r Te s es c ro P rp ss oce r P r Fe Neutron number Developement of radioactive beams to access exotic nuclei

The ISOL production Method Isotope Separation On Line Life-time > 100 ms projectile 1 Ge. V/u p, . . C… Heavy Ions • • (very) Thick targets Stopped reaction products “Chemistry” dependence (extraction) High quality post-accelerated RIB beam

In-flight or Fragmentation Method complementare insieme con ISOL • Heavy ion production beam BEAM TARGET Fragments • “Thin” target • • RIB utilizes production beam momentum No species dependence “Fast” measurements “in flight” Projectile Fragmentation and Fission Ge. V/u Ion Source For short lifetimes <1 ms

Types of reactions used for „in flight g-spectroscopy“ • Relativistic Coulomb excitation (large cross section of ca. 100 mb & thick targets) - first excited 2+states => B(E 2) - excitation of Giant Resonances • Secondary fragmentation - excited states at higher spins and higher excitation energy

Relativistic Coulomb Scattering of neutron rich isotopes Primary Beam 86 Kr (109 pps) 400… 700 Me. V/u HECTOR INCOMING Ca Ar K Cl S P Si Al Mg Na DE (~ 103 pps) 100 Me. V/u OUTGOING POSITION Z=20 37 Ca (85 %) Selection, identification and tracking E of the Isotop cocktail Z=19 2*103 p/sec 38 Ca (<1 %) 36 K (14 %) + timegate

RISING detectors v/c fino a 0. 8 Target : Au or Be Bea m Milano

RISING detectors v/c fino a 0. 8 After doppler correction Phys. Lett. B 622(2005)29 • collettivita’ (B(E 2) dello stato 2+ nel 56 Cr e’ minore di quella dei nuclei vicini • Evidenza della chiusura di una nuova sottoshell a N=32 ?

Future RIB facilities in Italy, Europe, WORLDWIDE Next step: Next generation spectrometers based on years of worldwide R&D • Higher efficiency • Higher selectivity, sensitivity • Higher position resolution For measuring gamma rays Is needed !!! Segmentation of the HPGe detector cristals and gamma-ray tracking àAGATA the ultimate gamma-ray spectrometer

Basic ingredients of AGATA 1 Highly segmented HPGe detectors Identified interaction points Milano AGATA group (x, y, z, E, t)i 4 Reconstruction of tracks evaluating permutations of interaction points · Pulse Shape Analysis to decompose recorded waves · 3 2 Digital electronics to record and process segment signals Milano AGATA group Reconstructed gamma-rays See poster

AGATA Advanced GAmma Tracking Array 4 p- Array of segmented HPGe 180 hexagonal crystals 3 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 off ? 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 Germanium Water/Ice Encapsulation technique on Mars ? INTEGRAL SATELLITE - INTERNATIONAL GAMMA RAY ASTROPHYSICS LABORATORY Mars Odyssey Gamma-Ray Spectrometer

Milano Nuclear Structure Group