Limits of Stability Neutron Drip Line? Proton Drip Line? Known Nuclei Heavy Elements? Fission Limit?

At the moment we are limited in our view of the atomic nucleus Some Basic Nuclear Property

RIA Will Greatly Expand Our Horizons

The march of time for The Table of Isotopes

What is an exotic nucleus? Normal Nucleus: 6 neutrons 6 protons (carbon) 12 C Stable, found in nature Exotic Nucleus: 16 neutrons 6 protons (carbon) 22 C Radioactive, at the limit of nuclear binding Characteristics of exotic nuclei: Excess of neutrons or protons, short half-life, neutron or proton dominated surface, low binding

Neutron and Proton Dripline A = 21

Isospin T z = (N-Z)/2 A = 21 T Z +9/2 +7/2 +5/2 +3/2 +1/2 –1/2 –3/2 –5/2 8 Al Mg Na Ne F O N C C 15 A Z N Neutron richProton rich

One thing we thought we knew about nuclei Nuclear properties are parameterized by the mass number A, for example the radius: R = 1.2 A 1/3 (Equation 1.3) (DeShalit and Feshbach, Theoretical Nuclear Physics, 1974 Wiley) Charge number Z and neutron number N are ignored.

Nuclear Radii Textbooks: R = r 0 A 1/3 I. Tanihata

Mass Predictions Model Difference (MeV) N (Z=55) S p = 0 S n = 0r-process Known Masses M. Huhta

How to reach the Driplines &Transfer reactions (light nuclei) &Fusion-evaporation (proton dripline) &Fission (neutron dripline) &Fragmentation  Target fragmentation  Projectile fragmentation &Transfer reactions (light nuclei) &Fusion-evaporation (proton dripline) &Fission (neutron dripline) &Fragmentation  Target fragmentation  Projectile fragmentation

Transfer Reactions

Fusion Evaporation 292 MeV 54 Fe + 92 Mo  146 Er(p4n) 141 Ho 402 MeV 78 Kr + 58 Ni  136 Gd(p4n) 131 Eu A.A. Sonzogni et al., Phys. Rev. Lett (1999) D. Seweryniak et al., Phys. Rev. Lett (2001)

Fission K.H. Schmidt et al., Model predictions of the fission-product yields for 238 U (2001)

Target Fragmentation Random removal of protons and neutrons from heavy target nuclei by energetic light projectiles (pre-equilibrium and equilibrium emissions).

Projectile Fragmentation Random removal of protons and neutrons from heavy projectile in peripheral collisions Cooling by evaporation. hot participant zone projectile fragment projectile target projectile fragment

Rare Isotope Accelerator (RIA)

Optimum Production Mechanism ISOL Task Force Report:

Production Yields

Fast Beams at RIA

Plans/Projects at Fragmentation Facilities RIKEN RI BEAM FACTORY ---A Dream Factory for Particle Beams--- The K500  K1200 Project

Comparison of Rare Isotope Intensities

Projectile Fragmentation &High-energy beams (E/A > 50 MeV) of modest beam quality. &Physical method of separation, no chemistry. &Suitable for short-lived isotopes (T 1/2 > s). &Increased luminosity from the use of thick secondary targets (by up to a factor of 10,000) &Efficient particle detection from strong forward focusing &Low-energy beams are difficult.

Yields from Fragmentation

S. Nagamiya and D.J.M., LBL (1980)  geom =  b 2 (1 - Vc/E) [  r 0 2 ( A T 1/3 + A B 1/3 -a) 2 ] ( 1 - Vc / E ) Geometry Dominates at high energies 0 b<r T + r B a

Fragmentation Reaction 18 O beam 9 Be target 18 O 9 Be 80 MeV/nucleon 40% speed of light 278,000,000 mph t = sec d = -10 fm ’’ t = -5x sec d = -5 fm

Production of 11 Li t = 0 sec d = 0 fm t = sec d = 10 fm 11 Li

Definitions/Numbers Energy Energy per nucleon: 80 A MeV Total energy: 1440 MeV Momentum: 7096 MeV/c Velocity: 11.7 cm/ns 0.39 c Rigidity: (p/q) 2.96 Tm Beam Intensity Particle Current: 1pnA Electrical Current: 8enA Particles: 6.25x10 9 /s Power: 1.44W 1pnA, 80 MeV/nucleon, 18 O, 8 +

Production of Fragments ~10pnA 18 O 80 MeV/nucleon ~ Li or ~1/ Li/ 18 O

Overview of the Fragment Separation Technique Wedge location D = 5 cm/% R = 2500 p/  p 86 Kr p  A ECR 86 Kr MeV/A 86 Kr MeV/A 100 pnA (1.3 kW power) 8 msr  p/p = 5% Example: 86 Kr  78 Ni, NSCL at full beam power 65% of the 78 Ni is transmitted

Program LISE LISE: Ligne d’Ions Super Epluchés (Line of Super Stripped Ions)

Beyond the Driplines!!

New Helium Atom !! A. Korsheninnikov et al., Phys. Lett. 326B 31 (1994) 10 He: Γ≤ 1.2 MeV or T 1/2 ≥ 5.5 x s !!!

What is a Particle? “… The techniques employed here are ideal for studying these unbound states and it is suggested that the introduction be changed to reflect this distinction between radioactivity and just unbound states. …” Referee, Phys. Rev. Lett. R. A. Kryger et al., Phys. Rev. Lett (1994) 12 O: Γ = 784(45) keV or T 1/2 = 3.6 x s

Definition of Radioactivity Joseph Cerny and J. C. Hardy, Annu. Rev. Nucl. Part. Sci. 27, 333 (1977) “…should lead to lifetimes longer than sec, a possible lower limit for the process to be called radioactivity.” “…should lead to lifetimes longer than sec, a possible lower limit for the process to be called radioactivity.”

Lifetimes/Decay-Widths

Timescales

Limit of Stability -- Superheavies

Complete Fusion Fundamental limitations: -- reaction dynamics, b~0 -- arithmetic of Z & N

266 Mt

Synthesis of Heavy Elements Production of longer lived neutron rich isotopes Connection to newly synthesized elements

Nuclear “Structure” U. Müller et al., Phys. Rev. C30, 1199 (1984)