First RIA Summer School on Exotic Beam Physics, August 12-17, Michael Thoennessen, NSCL/MSU. Lecture 1: Limits of Stability 1 A = 21

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Limits of Stability At the moment we are limited in our view of the atomic nucleus Proton Drip Line?

RIA Will Greatly Expand Our Horizons The march of time for The Table of Isotopes What is an exotic nucleus?

found in nature 16 neutrons 6 protons (carbon) 22 C Radioactive, at the limit of nuclear binding

1 Limits of Stability At the moment we are limited in our view of the atomic nucleus Proton Drip Line? Known Nuclei Heavy Elements? Fission Limit? Some Basic Nuclear Property Neutron Drip Line? RIA Will Greatly Expand Our Horizons The march of time for The Table of Isotopes What is an exotic nucleus? Neutron and Proton Dripline Normal Nucleus: Exotic Nucleus: A = 21 6 neutrons 6 protons (carbon) 12 C Stable, found in nature 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 Lecture 1: Limits of Stability 1

Isospin T z = (N-Z)/2 One thing we thought we knew about nuclei A = 21 A Z 21 C15 6 21 21 21 21 21 21 21 21 C15 Mg 6 7 N14 O F Ne Na 13Al 8 13 9 12 11 11 12 9 8 T +9/2 +7/2 +5/2 +3/2 +1/2 1/2 3/2 5/2

2 Isospin T z = (N-Z)/2 One thing we thought we knew about nuclei A = 21 A Z 21 C C15 Mg 6 7 N14 O F Ne Na 13Al T +9/2 +7/2 +5/2 +3/2 +1/2 1/2 3/2 5/2 Z Neutron rich N Proton rich 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 Mass Predictions Textbooks: R = r 0 A1/3 0 A I. Tanihata Model Difference (MeV) S p = 0 r-process S n = Known Masses N (Z=55) M. Huhta How to reach the Driplines Transfer Reactions Transfer reactions (light nuclei) Fusion-evaporation (proton dripline) Fission (neutron dripline) Fragmentation Target fragmentation Projectile fragmentation Lecture 1: Limits of Stability 2

Fusion Evaporation Fission 292 MeV 54 Fe + 92 Mo 146 Er(p4n) 141 Ho 402 MeV 78 Kr

Seweryniak et al., Phys. Rev. Lett. 86 1458 (2001) K.H. Schmidt et al.

Fragmentation Projectile Fragmentation Random removal of protons and neutrons from

collisions hot participant zone projectile fragment projectile target Cooling by

3 Fusion Evaporation Fission 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) K.H. Schmidt et al., Model predictions of the fission-product yields for 238 U (2001) Target Fragmentation Projectile Fragmentation Random removal of protons and neutrons from heavy target nuclei by energetic light projectiles (pre-equilibrium and equilibrium emissions). Random removal of protons and neutrons from heavy projectile in peripheral collisions hot participant zone projectile fragment projectile target Cooling by evaporation. projectile fragment Rare Isotope Accelerator (RIA) Optimum Production Mechanism ISOL Task Force Report: Lecture 1: Limits of Stability 3

Production Yields Fast Beams at RIA 90 Fast Beams at RIA 80 70 400 MeV/u 0 kw Proton Number 60 50 > 12

40 60 80 0 120 140 Cheng-Lie Jiang Neutron Number (A-Z) Plans/Projects at Fragmentation Facilities

for Particle Beams--- Projectile Fragmentation Yields from Fragmentation 80.

Suitable for short-lived isotopes (T 1/2 > -6 s).

particle detection from strong forward focusing Low-energy beams are difficult. Z 70.0 60.0 50.0 40.

4 Production Yields Fast Beams at RIA 90 Fast Beams at RIA MeV/u 0 kw Proton Number > Ions/s Proton-drip line Neutron-drip line r-process Cheng-Lie Jiang Neutron Number (A-Z) Plans/Projects at Fragmentation Facilities Comparison of Rare Isotope Intensities The K500 K1200 Project RIKEN RI BEAM FACTORY ---A Dream Factory for Particle Beams--- Projectile Fragmentation Yields from Fragmentation 80.0 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 > -6 s). Increased luminosity from the use of thick secondary targets (by up to a factor of,000) Efficient particle detection from strong forward focusing Low-energy beams are difficult. Z Region of Known Nuclei rp-process path N (A-Z) r-process path > RI yield in ions/s Lecture 1: Limits of Stability 4

V/nucleon 40% speed of light 278,000,000 mph 9Be S. Nagamiya and D.J.M.

5 Michael Thoennessen, Fragmentation Reaction Geometry Dominates at high energies 18O 0 σgeom = π b2 (1 - Vc/E) [π r02 ( AT 1/3 + AB 1/3 -a)2 ] ( 1 - Vc / E ) t = --22 sec d = - fm beam 9Be b<rt+ rb target t = -5x-23 sec d = -5 fm 18O a 80 MeV/nucleon 40% speed of light 278,000,000 mph 9Be S. Nagamiya and D.J.M., LBL-461 (1980) Production of 11Li Definitions/Numbers t = 0 sec d = 0 fm 1pnA, 80 MeV/nucleon, 18O, 8+ 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 t = -22 sec d = fm 11Li Production of Fragments Beam Intensity Particle Current: Electrical Current: Particles: Power: 1pnA 8enA 6.25x9/s 1.44W Overview of the Fragment Separation Technique 86Kr 14+ ~pna 18O 80 MeV/nucleon 8 pµa ECR 14 MeV/A 86Kr MeV/A 0 pna (1.3 kw power) 86Kr 14+ ~0 11Li or ~1/9 11Li/18O 8 msr p/p = 5% Wedge location D = 5 cm/% R = 2500 p/ p 65% of the 78Ni is transmitted Example: 86Kr 78Ni, NSCL at full beam power Lecture 1: Limits of Stability 5

Program LISE Beyond the Driplines!! LISE: Ligne d Ions Super Epluchés (Line of Super Stripped Ions) http://www.nscl.msu.

!! The techniques employed here are ideal for studying these unbound states and it is suggested that the introduction be changed to reflect this

6 x -22 s Definition of Radioactivity Lifetimes/Decay-Widths should lead to to lifetimes longer than -12-12 sec, a possible lower limit for for

6 Program LISE Beyond the Driplines!! LISE: Ligne d Ions Super Epluchés (Line of Super Stripped Ions) New Helium Atom!! What is a Particle? A. Korsheninnikov et al., Phys. Lett. 326B 31 (1994) He: Γ 1.2 MeV or T 1/2 5.5 x -22 s!!! 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 -22 s Definition of Radioactivity Lifetimes/Decay-Widths should lead to to lifetimes longer than sec, a possible lower limit for for the the process to to be be called radioactivity. Joseph Cerny and J. C. Hardy, Annu. Rev. Nucl. Part. Sci. 27, 333 (1977) Lecture 1: Limits of Stability 6

7 Timescales Limit of Stability -- Superheavies Complete Fusion 266 Mt Fundamental limitations: -- reaction dynamics, b~0 -- arithmetic of Z & N Synthesis of Heavy Elements Nuclear Structure Production of longer lived neutron rich isotopes Connection to newly synthesized elements U. Müller et al., Phys. Rev. C30, 1199 (1984) Lecture 1: Limits of Stability 7

EXPLORATIONS ALONG THE NEUTRON DRIPLINE

EXPLORATIONS ALONG THE NEUTRON DRIPLINE M. THOENNESSEN Department of Physics & Astronomy and National Superconducting Cyclotron Laboratory Michigan State University, East Lansing, MI 48824, USA Abstract.