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Argonne National Laboratory is managed by The University of Chicago for the U.S. Department of Energy Birger Back Argonne National Laboratory The Radioactive Beam Program at Argonne 23 rd Winter Workshop on Nuclear Dynamics La Jolla, California March 11-19, 2006

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 2 Outline Physics Motivation for Radioactive Beams Past and Present Radioctive Beam Studies -Nuclear Astrophysics Studies (K.E.Rehm) -Light Nuclei & ab initio structure calculations (A.H.Wuosmaa) -Nuclear Charge radius of 6 He and 8 He (Z.-T. Lu et al.) Future Plans -CARIBU: Accelerated 254 Cf fission fragments (G. Savard) -Superconducting Solenoid Spectrometer (B.Back) -RIA ?

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 3 Important physics questions modification of nuclear structure in neutron-rich systems - shell-structure quenching - single particle structure near neutron-rich magic nuclei - pairing interaction in weakly-bound systems collective behavior in neutron-rich systems r-process path - ground-state information mass lifetime - neutron capture rate - fissionability of very heavy neutron-rich isotopes

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 4 Past and Present Radioactive Beam Studies -Nuclear Astrophysics Studies (K.E.Rehm) -Light Nuclei & ab initio structure calculations (A.H.Wuosmaa) -Nuclear Charge radius of 6 He and 8 He (Z.-T. Lu et al.)

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 5 ATLAS facility at Argonne CARIBU New addition being built Secondary beam production target Solenoid Spectrometer

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 6 In-flight radioactive beams at ANL: e.g. 6 He beams 7 Li from ATLAS 81 MeV 3 X particles/sec D 2 gas cell 7 Li + 6 He 7 Li 6 He Focusing solenoid Magnetic separator Rebunching resonator 7 Li + 6 He 7 Li *B. Harss, K. E. Rehm et al., Rev. Sci. Instrum. 71, 380 (2000) 10,000 pps Reaction: 7 Li+d => 3 He+ 6 He

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 7 Beams available “now” Beams available after CARIBU upgrade Radioactive beams at ATLAS

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 8 RIA beams – delayed ‘til 2011 (Bodman)

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 9 Past and Present Radioactive Beam Studies -Nuclear Astrophysics Studies (K.E.Rehm) -Light Nuclei & ab initio structure calculations (A.H.Wuosmaa) -Nuclear Charge radius of 6 He and 8 He (Z.-T. Lu et al.)

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory C( ) 16 O ANL: J. Greene, A. Hecht, D. Henderson, R. Janssens, C. L. Jiang, E. F. Moore, M. Notani*, R. C. Pardo, K. E. Rehm, G. Savard, J. P. Schiffer, B. Shumard, S. Sinha, X. D. Tang Hebrew University: M. Paul Northwestern University: L. Jisonna, R. E. Segel Ohio University: C. Brune University of North Carolina: A. Champagne Western Michigan University: A. Wuosmaa *supp. by JINA.. single most important nuclear physics uncertainty.. DoE Milestones: Reduce Uncertainties of the most crucial stellar evolution nuclear reactions (e.g. 12 C( ) 16 O) by a factor of two.

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 11 Need width of sub-threshold 1 - state to determins S-factor at Gamow window Obtain width from interference structure on low-energy side of above-threshold 1- state High intensity 16 N beam Detector with no -sensitivity Interference

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 12 Twin-Ionization Chamber Anode (Energy) Frisch grid (angle) Frisch grid E( ) 16 N(T ½ =7.1s) anode E( 12 C) cathode E ~ 1.82 MeV No radiation damage Available with large areas Improved homogeneity Practically no sensitivity to ’s No dead layer Smaller pulse height defects

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 13 Rotating wheel/cathode 4 Ionization chambers 16 N beam T ½ =7.1 s Stepping motor, encoder Experimental setup Rotating wheel, cathode

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory N 16 O 12 C+ first test results PRELIMINARY No background

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 15 Past and Present Radioactive Beam Studies -Nuclear Astrophysics Studies (K.E.Rehm) -Light Nuclei & ab initio structure calculations (A.H.Wuosmaa) -Nuclear Charge radius of 6 He and 8 He (Z.-T. Lu et al.)

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 16 Example: 7 He (Wuosmaa et al., PRC 72, (2005) 7 He: -Unbound neutrons – halos – significant current interest -Theories generally agree but uncertainty in experimental results -Where is the 1 st excited state? Is there one? What is it’s spin? Can be studied with (d,p) reactions using unstable beams

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 17 Annular proton detectors lab ~ 3.5 sr lab =109 o -159 o Forward-angle E E detectors lab =1 o -7 o CD 2 target 540 g/cm 2 Au Monitor target Monitor E E telescope Beam axis 6 He proton 4,6 He Our secondary-beam intensities are ~1-5X10 4 particles/sec Event rate for 10 mb/sr ~ counts/hour Experimental setup

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 18 Efficiency corrected data Calibration Reaction 2 H( 7 Li,p) 8 Li showing empirical background 2 H( 6 He,p) 7 He Fit with ground state, broad resonance, background 7 He data with fit including state with E X =600 keV, =750 keV, Strength with expected spectroscopic factor

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 19 Past and Present Radioactive Beam Studies -Nuclear Astrophysics Studies (K.E.Rehm) -Light Nuclei & ab initio structure calculations (A.H.Wuosmaa) -Nuclear Charge radius of 6 He and 8 He (Z.-T. Lu et al.) -L.-B. Wang,UIUC -APS/DNP Thesis prize (2006)

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 20 Charge Radii Measurements Methods of measuring nuclear radii (interaction radii, matter radii, charge radii) Nuclear scattering – model dependent Electron scattering – stable isotope only Muonic atom spectroscopy – stable isotope only Atomic isotope shift RMS point proton radii (fm) from theory and experiment G.D. Alkhazov et al., Phys. Rev. Lett. 78, 2313 (1997); D. Shiner et al., Phys. Rev. Lett. 74, 3553 (1995). 6 He

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 21 Experimental Setup - Schematic Photon Counter RF discharge Kr, 4 He 6 He He* Zeeman Slower MOT Transversal Cooling 389 nm1083 nm 6 He Produced Kr or 4 He Carrier gas Mixing chamber 389 nm 2S-2P, 1083 nm 2S-3P, 389 nm ATLAS 12 C( 7 Li, 6 He) 13 N 7 Li 3+ : 100 pnA, 60 MeV 6 He extracted: ~ 10 6 s -1 6 He trapped: ~ s -1

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 22 Single Atom Spectroscopy ~ He atoms in one hour April 6, He 6 He

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 23 Reaction collision Elastic collision Atomic isotope shift Cluster models No-core shell model Quantum MC Experiments Theories A Proving Ground for Nuclear Structure Theories L.-B. Wang et al., Phys. Rev. Lett. 93, (2004) (Nucl-ex/ ) First model- independent determination Pieper&Wiringa 05 (AV18+IL2)

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 24 Outline Physics Motivation for Radioactive Beams Past and Present Radioctive Beam Studies -Nuclear Astrophysics Studies (K.E.Rehm) -Light Nuclei & ab initio structure calculations (A.H.Wuosmaa) -Nuclear Charge radius of 6 He and 8 He (Z.-T. Lu et al.) Future Plans -CARIBU: Accelerated 254 Cf fission fragments (G. Savard) -Superconducting Solenoid Spectrometer -RIA ?

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 25 Neutron-rich ions for free – 252 Cf spontaneous fission r-process path 1 Ci 252 Cf source about 20% of total activity extracted as ions works for all species large improvement over existing ISOL based facilities

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 26 CARIBU – new building under construction Courtesy: R. Pardo

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 27 CARIBU: Gas cell RFQ cooler ECR Charge breeder Courtesy: R. Pardo 252 Cf source

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 28 Yields for Representative Species Calculated maximum beam intensities for a 1 Ci 252 Cf fission source using expected efficiencies. IsotopeHalf-life (s) Low-Energy Beam Yield (s -1 ) Accelerated Beam Yield (s -1 ) 104 Zr1.26.0x x Ba x x Ba4.05.5x x Sn x x Sn40.3.7x x Xe x x Mo2.86.2x x Mo0.53.3x x10 2

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 29 Outline Physics Motivation for Radioactive Beams Past and Present Radioctive Beam Studies -Nuclear Astrophysics Studies (K.E.Rehm) -Light Nuclei & ab initio structure calculations (A.H.Wuosmaa) -Nuclear Charge radius of 6 He and 8 He (Z.-T. Lu et al.) Future Plans -CARIBU: Accelerated 254 Cf fission fragments (G. Savard) -Superconducting Solenoid Spectrometer -RIA ?

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 30 Measured quantities Flight time: T flight =T cyc Position:z Energy:E lab Solenoidal spectrometer A new concept for studying light-ion reactions Derived quantities Part. ID: m/q Energy:E cm Angle: cm Field: 5 Tesla ParticleT cyc (ns) p13.1 d, 26.2 t He19.7 p,d,t, 3 He, Heavy-Ion Inverse kinematics Strong MRI magnet

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 31 p( 44 Ti,p’) 44 Ti kinematics E lab =50 keV z=1 mm T flight =1 ns E lab =50 keV =1 deg p (degrees) E p (MeV) =60 o z=25 cm Simulation E p (MeV) z p (cm)

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 32 Acceptance -acceptance: ~100% ( ,E lab ) acceptance depends on solenoid geometry and magnetic field strength With the target located at the center of a 150 cm long solenoid of 50 cm bore the acceptance is shown here. The lower energy cut-off arises from the outer diam. of the Si detector and its proximity to the target (5cm) Acceptance can be optimized to specific reaction by moving target and Si detectors along beam axis

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 33 Advantages of Solenoid Spectrometer Automatic particle I.D. Excellent center-of-mass energy resolution Large acceptance and solid angle Simple detector and electronics - few channels Excellent center-of-mass angle resolution Suppression of backgrounds

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 34 Physics opportunities Single particle structure - Mapping out the single-particle strength near closed shells Astrophysics - Studies of the s, r, and rp-processes using (d,p) and ( 3 He,d) reactions on radioactive nuclei Pair transfer - Probing the nature of pair correlations in a new domain away from stability using (p,t), (t,p), and ( 3 He,p) reactions Inelastic scattering - Study collective aspects of nuclear structure in radioactive species using p, , and other light particles Knockout reactions - Study of deep-lying particle orbits via (p,2p) reactions Surrogate reactions - Simulation of n-capture cross section on short-lived isotopes by comparison to (d,p) reactions. Needed for stockpile stewardship program

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 35 Summary - Conclusions Present: Argonne has a substantial radioactive beam program -Nuclear Astrophysics -Structure of light nuclei – GFMC ab-initio theory -Laser spectroscopy – nuclear charge radii -Other Future: -CARIBU – weak but very neutron-rich beams -New Solenoid Spectrometer -RIA??? -National Academy of Science – Rare Isotope Science Assessment Committee – see

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 36 Atomic Isotope Shift Isotope Shift dn = dn MS + dn FS Field shift: due to nucleus size FS Z D[ (0)] 2 Measured Calculated Measured Derived IS(2 3 S P 2 ) = 43, (16) ( He4 - He6 ) MHz ---- G. W. F. Drake, Nucl. Phys. A737c, 25 (2004) dn MS Mass shift: due to nucleus recoil Gordon Drake, High precision theory of atomic helium, Phys. Scripta T83: 83 (1999) e-e- e-e- e-e-

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 37 Layout Solenoid:50 cm bore x 150 cm long superconducting 5.0 Tesla axial field Cryo-coolers Target:1 mm thick cooled gas target w. Ti windows Si-detectors:12 pos. sensitive Si detectors 1x10 cm Recoil detectors: E-E Si array for A<20 recoils Ionization chamber for heavier recoils Solenoid Si-detector array Target wheel/cell Vacuum chamber

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 38 (d,p) Angular Distributions 2 H( 8 Li,p) 9 Li DWBA calculations, QMC predictions, no normalization 2 H( 6 He,p) 7 He g.s. DWBA calculations QMC calculations Optical-model parameters from Schiffer et al, PRC 164

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 39 sun novae neutron-star supernovae Supermassive stars 8 B( ) 2 C(p, ) 8 B Na(p, ) 18 Ne 15 O( ) 19 Ne 17 F(p, ) 14 O Ni(p, ) 57 Cu Ti( p) 47 V Nuclear Astrophysics with Radioactive Beams: PRL 84, 1651(2000) PRL 80, 676(1998) PRL 82, 3964(1999) PRC 65, (2002) PRC 67, (2003) PRC 67, (2003) PRL 91, (2003) NPA 734, 615(2004) C( ) 16 O massive stars

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Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 40 Energy Level Fits +2n 6 He+2n 8 He+2n S. Pieper and R. Wiringa

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