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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 Slide 2 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 ? Slide 3 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 Slide 4 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.) Slide 5 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 Slide 6 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 10 11 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 Slide 7 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 Slide 8 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) Slide 9 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.) Slide 10 Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 10 12 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. Slide 11 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 Slide 12 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 =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 Slide 13 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 =7.1 s Stepping motor, encoder Experimental setup Rotating wheel, cathode Slide 14 Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 14 16 N 16 O 12 C+ first test results PRELIMINARY No background Slide 15 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.) Slide 16 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, 061301 (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 its spin? Can be studied with (d,p) reactions using unstable beams Slide 17 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 ~ 10-50 counts/hour Experimental setup Slide 18 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 Slide 19 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) Slide 20 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 Slide 21 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: ~ 10 -2 s -1 Slide 22 Pioneering Science and Technology Winter Workshop on Nuclear Dynamics, LaJolla March 11-19, 2006 B.B.Back, Argonne National Laboratory 22 Single Atom Spectroscopy ~ 150 6 He atoms in one hour April 6, 2004 4 He 6 He Slide 23 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, 142501 (2004) (Nucl-ex/0408008) First model- independent determination Pieper&Wiringa 05 (AV18+IL2) Slide 24 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 ? Slide 25 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 Slide 26 Pioneering Science and Technology Winter Wo