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Science Program Upgrade Plans

Explore the latest scientific accomplishments and upgrade plans in the field of nuclear science and accelerator technology. Discover opportunities at HRIBF and various research facilities. Investigate the evolution of shell structure in neutron-rich nuclei and the influence of neutron excess on fusion reactions.

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Science Program Upgrade Plans

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  1. Science Program Upgrade Plans Witold Nazarewicz Ganil, June’07 • Scientific accomplishments • Opportunities

  2. HRIBF in 2006 25MV Tandem Electrostatic Accelerator Injector for Radioactive Ion Species 1 (IRIS1) Stable Ion Injector (ISIS) Oak Ridge Isochronous Cyclotron (ORIC) Enge Spectrograph Daresbury Recoil Separator (DRS) High Power Target Laboratory (HPTL) Recoil Mass Spectrometer (RMS) On-Line Test Facility (OLTF)

  3. The first transfer measurements on N~82 nuclei on / near r-process path 132Sn(d,p)133Sn K. Jones 130Sn(d,p)131Sn - R. Kozub et al. 132Sn(d,p)133Sn - K.L. Jones et al. 134Te(d,p)135Te - S.D. Pain et al. • yields, angular distributions of low-lying states measured • first observation of p1/2 state in 133Sn • three other states in 133Sn measured, calibrated with 130Te(d,p) • evidence for numerous states in 131Sn never seen before • evidence that the f5/2 level in 135Te is at a significantly higher energy

  4. Superallowed -decay 109Xe →105Te →101Sn a Old standard (different shell structure for neutrons and protons) 213Po 209Pb • rp-process termination • en route to 104Te → 100Sn a 208Pb 208Pb a + n + + n New standard (the same shell structure for neutrons and protons) (5/2+) 620  70 ns a 100Sn 100Sn a n + + + n 105Te53 52 a 105Te 101Sn l=0 Identification at HRIBF of fastest known alpha decays: Ea = 4.703 keV (5/2+) 1.9 s S. Liddick et al., PRL 97,082501(2006) d2(105Te)/d2(213Po) =2.4(3) 101Sn51 50

  5. The evolution of shell structure in very neutron-rich nuclei beyond the N=50 shell closure b-decay studies around 78Ni with postaccelerated (3 MeV/u) pure neutron-rich RIBs beam T1/2 (s) main results 76Cu 0.65 bn-branching ratio Ibn 77Cu 0.46 Ibn, n- levels in N=47 77Zn 78Cu 0.35 Ibn, Ip of 78Cu49 revised 79Cu 0.19 bngdecay observed first time 83Ga 0.30 bng,bg, ns1/2 in N=51 83Ge 84Ga 0.08 2+ in N=52 84Ge 85Ga ??? rate of 0.1pps… • t1/2 & n rates for many r process nuclei are accessible • Energy levels test evolving nuclear structure • Range out unwanted high-Z contamination with high pressure & tape transport • Absolute beta-delayed neutron branching ratios for 76-79Cu and 83-84Ga • Identification of new excited states in 77Zn, 78Zn, 82Ge, 83Ge, and 84Ge • Systematics of single particle levels (e.g. neutron s1/2) near doubly magic 78Ni Winger et al.

  6. Observation of fusion enhancement at sub-barrier energies in 132,134Sn+64Ni • Probing the influence of neutron excess on fusion at and below the Coulomb barrier • Large sub-barrier fusion enhancement has been observed • Inelastic excitation and neutron transfer play an important role in the observed fusion enhancement • Important for superheavy element synthesis • ERs made with 132,134Sn cannot be made with stable Sn Shapira et al., Eur. Phys. J. A 25, s01, 241 (2005) Liang et al., PRL 91, 15271 (2003); PRC 75, 054607 (2007)

  7. -decay of 109I and the rp-process Astrophysical relevance : C.Mazzocchi, …, H.Schatz,…PRL 98,212501 (2007) a p 109I → 105Sb →104Sn • No observable proton emission from 105Sb • The rp-process termination cycle starts at 105Sn • If 104Sb is much more proton bound than predicted (strong odd-even effect) it may start at 103Sn ! Sn-Sb-Te cycle ~10-2% Q=3918(21) keV Qp(105Sb)=356(22) keV ≠491(15) keV ? search for112Cs weak a-decay : SP of 108I and 104Sb rp-process termination H.Schatz et al., PRL86 (2001)

  8. International Perspective (cont.) HRIBF, 78Cu ~ 1.5-3 pps: ~ 19 hours counting ! g-energy Example: b-decay of 238U fission products (Rykaczewski) Postaccelerated, separated with high-resolution and ranged-out beams 76Cu (0.64 s) : 150 - 300 pps 77Cu (0.47 s) : 15-25 pps 78Cu (0.34 s) : 1.5-3 pps 79Cu (0.19 s) : 0.13-0.2 pps 83Ga (0.31 s) : 30-60 pps 84Ga (0.085 s) : 1.5 pps 85Ga ( ??? ) : 0.12 pps HRIBF Cu rates are about 30-50 times higher in comparison to 86Kr fragmentation at NSCL (Ni,Co,Fe rates are better at NSCL) HRIBF Ga rates are about 30-60 times higher in comparison to the non-accelerated ion rates at PARRNe (Orsay, France) EPJ A28, 307,2006 Leuven – ISOLDE PR C71,054307,2005 78Cu b-decay g-g 78Cu : 78Ga ~ 1 :10 78Cu :78Ga ~ 1:10 000

  9. 3000 134Sn/s Coulomb excitation in n-rich systemsPioneering Coulomb excitation of beams of radioactive isotopes of Ge, Sn, Sb, Te • Probing the evolution of collective motion in neutron-rich nuclei • Increasingly larger contributions of neutrons to B(E2) values above 132Sn • Recoil-in-Vacuum technique used to measure the g-factor for the first 2+ state in 132Te: Stone et al., PRL 94, 192501 (2005) Padilla-Rodal et al. Phys. Rev. Lett. 94, 122501 (2005) Yu et al., Eur. Phys. J. A 25, s01, 395 (2005) Radford et al., Nucl. Phys. A752, 264c (2005) Varner et al., Eur. Phys. J. A 25, s01, 391 (2005) Baktash et al., to be published

  10. First Constraint on Very Low Temperature 18F(p, )15O reaction rate in Novae Kozub et al., PRC 71 (2005) 032801 Off resonance measurements provided first constraints on interference in the 18F+p system. HRIBF measurements reduced uncertainty in 18F(p,)15O rate reduced by ~30x 18F is -potentially important source of g-rays from novae -target of billion dollar orbiting telescopes The understanding of 18F(p,a)15O reaction crucial 18F(p,)15O Chae et al., PRC 74 (2006) 012801. Bardayan et al., PRL 89 (2002) 262501.

  11. 150 100 50 7Be H2 gas 20 15 10 5 0 7Be(p,p0)7Be cm=128 Solar Physics: Understanding 8B and the solar thermonuclear7Be(p,)8B reaction Measurements of 7Be+p elastic & inelastic scattering have improved our understanding of the 8Be level structure d/d (mb/sr) 7Be(p,p1)7Be* cm=124 First statistically significant direct measurements of the 7Be(p,)8B cross section using a 7Be beam are testing systematic uncertainties in the 7Be(p,)8B cross section Ecm (MeV) 8B 4+ Daresbury Recoil Separator 5+ ionization chamber

  12. “Best studied” deformed proton emitters 141gsHo and 141mHo Excited states in 141Ho from GS+FMA exp ! 7.4(3)ms ~1.7% Both measured properties of 141mHo decay, the decay rate (factor 2-3 too large) and fine structure (factor 5 too small) call for a change in our understanding of the 141mHo (and 141gsHo) wave function • 141Ho is 20 neutrons away from stable 161Ho • Tensor interaction plays a role in proton-rich systems

  13. Future Science Program(details in the Strategic Plan!) • Future research at HRIBF includes studies of: • Exotic nuclei near shell closures (such as 78Ni, 82Ge, 100Sn, and 132Sn), which have a direct bearing on the shell-model description of the nucleus and the origin of heavy elements. • Properties of neutron-rich unstable nuclei and their reactions to find the way to synthesis of the heaviest nuclei and to improve our understanding of supernovae and red giant stars. • Two-neutron transfer in neutron-rich nuclei: probing the particle-particle channel • Superallowed alpha decays and cluster decays above 100Sn • Proton- and alpha-induced reactions on, and the properties of, proton-rich radioactive nuclei to understand element synthesis and energy generation in stellar explosions. • Systematic studies of magnetic moments using RIV and transient field method • Solar neutrino flux using radioactive 7Be beam • Studies of molecular states in light nuclei with the 10Be beam • HRIBF’s science for the benefit of society (the opportunity for advances in other scientific fields and applied technologies) • Accelerator Mass Spectrometry program centered around the 25-MV tandem • Applications of 7Be in life sciences

  14. Provides travel and local support for U.S. participants to JUSTIPEN. Fully funded in FY07…. (about 25 visits and 2-3 long term— 3 month -- visits). www.phys.utk.edu/JUSTIPEN Initial Steering Committee: Takaharu Otsuka (Managing Director, U. Tokyo) David Dean (Associate Director, ORNL) Tohru Motobayshi (Associate Director, RIKEN) Witek Nazarewicz (UT/ORNL) Baha Balantekin (University of Wisconsin) Hiashi Horiuchi (Kyoto University) Hideyuki Sakai (University of Tokyo) Richard Casten (Yale University) Vanderbilt – 6 April 2007

  15. STATUS: FUNDED • State of TN: $250,000 • University of TN: $ 37,500 • Vanderbilt Univ: $ 37,500 • ORNL $ 75,000 • TOTAL: $400,000 • Business model: • Enable enhancement of RIB • research at HRIBF through • theory visitors; enable international • RIB theory program • Infrastructure supported by • UT and ORNL Physics Division. • Three proposals sold the concept: • 1. JUSTIPEN (closed the deal) • 2. SciDAC (2005/6) • 3. initial topical center idea (2003) • Joe Hamilton, Carrol Bingham, Witek • Nazarewicz, and DJD obtained funding. Vanderbilt – 6 April 2007

  16. An Upgrade to HRIBF:RIB production by photofission Improvement vs. HRIBF Yields grey = stable • Can enhance HRIBF neutron-rich yields by a large factor very cost-effectively • Implement a ~100kW turn key electron accelerator with energy in range 12 to 50 MeV • Photofission Driver • A minimum fission yield of 1013 f/s can be achieved with present target technology for Ee>20 MeV– larger with advanced target • Factors well over 103 for enhancement of very neutron rich species • A lower cost facility can be built with 100 kW, Ee~12 MeV driver. • can achieve ~2x1012 f/s with existing targets (5x reduction in yield compared to ≥ 25 MeV e) 1013ph-f/s 10 mA 40 MeV p

  17. Ge Photofission Yields Photofission is “cooler” than proton-induced fission, thus yield curve is more neutron-rich Sn

  18. Science highlights with Photofission Driver • Will test the evolution of nuclear structure to the extremes of isospin • Will improve our understanding of the origins of the heavy elements Evolution of structure: Coulex, moment measurements, transfer at 132Sn & beyond Collective properties in extended neutron radii: Coulomb excitation near 96Kr Evolution of structure near 78Ni: Transfer reactions, Coulex, moment measurements Reaction mechanisms for the formation of superheavy nuclei Decay properties of nuclei at the limits: Crucial for understanding the formation of elements from iron to uranium

  19. Over 17 units sold, including ISOMEDIX (USA) STUDER (SWITZERLAND) A.E.0.I.( IRAN) ENUSA (SPAIN) ECI (BELGIUM) RISTRON (GERMANY) HOSPAL (ITALY) IBA RhodotronElectron AcceleratorWilling to scale their 10 MeV, 20mA unit (shown) to 25 MeV

  20. Electron Beam Facility Elevation

  21. Coulex (1-step) Accessible at HRIBF Accessible w e-machine

  22. Multi-step Coulex Accessible at HRIBF Accessible w e-machine

  23. g-factor Measurements Accessible at HRIBF Accessible w e-mach

  24. Transfer reaction studies Accessible at HRIBF Accessible with e-machine

  25. Two possibilities Single (80 kW, 12.5 MeV) Vs. Dual Rhodatrons (60-100 kW, 25 MeV) 5x more RIBs with two Rhodatrons Classic case of capital cost vs yields of RIBs Cost $23M for 1-Rhodatron version $34M for 2-Rhodatron version Schedule 3-4 years required CD-n sequence must be followed E-Machine Cost and Schedule

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