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The Science of RIA

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The Science of RIA The Science of RIA Brad Sherrill Why build a high-power, heavy-ion LINAC? • Introduction • The intellectual challenges addressed by RIA (Nuclei, Chemical History of the Universe, Fundamental Symmetries) • Production of rare isotopes – options and considerations • What does SRF technology and the RIA concept make possible? • Summary LINAC 2004 We don’t know nuclei that well – Binding Energies Sp = 0 r-process Sn = 0 10 Models 8 Today exp 6 DusCZ Molal eV) 4 ComKZ SatNa M 2 Tachi SpaJo 0 JaneMass rence ( MassJane e Duflo f -2 LZe76 -4 known masses Pearson FRDM93 TF94 odel dif -6 DuZu94 m -8 -10 50 60 70 80 90 100 110 120 130 140 G. Bollen N (Z = 55) LINAC 2004 An Example of a Nuclear Halo A scaled cartoon 1 fm Halo Nucleus Normal Nucleus Two effects : QM penetration (halo) and a difference in proton and neutron Fermi levels (skins) LINAC 2004 NRC Report: Connecting Quarks to the Cosmos Eleven Science Questions for the New Century (2003) – National Academy Study, M. Turner Chair — What is dark matter? — What is the nature of the dark energy? — How did the Universe begin? — Did Einstein have the last word on gravity? — What are the masses of the neutrinos and how have they shaped the evolution of the universe? — How do cosmic accelerators work and what are they accelerating? — Are protons unstable? — Are there new states of matter at exceedingly high density and temperature? — Are there additional space-time dimensions? 9How were the heavy elements from iron to uranium made? — Is a new theory of matter and light needed at the highest energies? NEW: US Interagency Task Force stated that Underground Lab, RIA, RHIC II are needed to meet these goals. http://www.ostp.gov/ LINAC 2004 Rapid Neutron Capture Process (r-process) How were the heavy elements from iron to uranium made? Two possibilities (there are others): Woosley … Thieleman … LINAC 2004 Importance of Nuclear Physics in the r-process In r-process model calculations nuclear shell structure is important. 101 Shell gap reduced Α ν post- 100 processing e c signature ? -1 n 10 a Qian, d n -2 Haxton u 10 Ab -3 10 Full shell gap 10-4 100 120 140 160 180 200 220 A Dobaczewski, Nazarewicz, Kratz, … Question:Question: Is Is this this difference difference due due to to shell shell quenching quenching for for neutron-richneutron-rich nuclei, nuclei, or or a a problem problem with with astrophysical astrophysical model? model? LINAC 2004 Possibilities to study r-process nuclei Needed Data for r-process nuclei: 0 5 s 2 e •Masses c n • Decay properties a • Level structure bund • n capture rates (indirectly) a 0 0 100 2 98 ss 96 e 94 c 92 o 90 88 pr 86 84 188 190 - 186 r 82 80 78 184 180 182 76 178 0 176 5 74 164 166 168 170 172 174 1 72 162 70 160 68 158 66 156 154 64 152 150 62 140 142 144 146 148 1 1 60 138 134 136 0 58 130 132 0 0 128 1 56 0 54 126 1 -1 124 52 122 120 0 50 116 118 1 -2 48 0 112 114 110 0 3 0 1 46 - 108 1 106 44 0 104 100 102 42 1 98 96 40 92 94 N=126 38 88 90 86 36 84 82 34 80 78 32 74 76 30 72 70 28 66 68 64 26 62 N=82 28 60 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 LINAC 2004 Summary of the scientific justification for JWST • What is the shape of the Universe? • How do galaxies evolve? • How do stars and planetary systems form and interact? • How did the Universe build up it present elemental/chemical composition? James Webb Space Telescope NASA/EESC/CSA • What is dark matter? http://ngst.gsfc.nasa.gov/science/ScienceGoals.htm LINAC 2004 The Active Universe- Gamma Ray Astronomy M.Wiescher 1 MeV-30 MeV γ-Radiation in Galactic Survey (26Al Half life: 700,0000 years) 44Ti in Supernova Cas-A Location 1.157 MeV γ-radiation (Half life: 60 years) LINAC 2004 Observation of 26Al Demonstrates Nucleosynthesis N. Prantzos, Astonomy & Astro 420 (2004) The observation indicates 2 solar masses of 26Al produced per My (1.5x1042 atoms/s). How? • Type II Supernovae 60 26 Fe/ Al ratio is a problem measured by RHESSI to be 0.16 (predicted >0.4) 59 59 Fe(n,γ) is critical but Fe is radioactive • Novae • Wolf-Rayet Stars Needed: Better observations and better nucleosynthesis calculations LINAC 2004 Rare Isotopes and Fundamental Symmetries QWeak An example of the E158 so called running ? of fundamental constants. Prediction of the Standard Electro- Weak Theory G. Sprouce Rare-isotope facilities provide a credible path to necessary improvements on parity non-conservation in atoms. LINAC 2004 Radioactive Beam Production Mechanisms • Projectile Fragmentation/Fission beam Fragment Separator Driver Accelerator beam target Beams used without stopping Post Acceleration Gas cell catcher/ion source beam • Target Spallation and fragmentation Target/Ion Source target LINAC Post Acceleration • Neutron induced fission (2-step target) Neutrons LINAC Post Acceleration LINAC 2004 Optimum Mechanism for each Isotope Optimum production method for low-energy beams Standard ISOL technique Two-step fission In-flight fission + gas cell Fragmentation + gas cell Most facilities use only one production method. LINAC 2004 Requirements • Production cross sections for the interesting nuclei at the limits of stability are low (fb), thus as high as possible primary beam intensities are needed. Uranium Luminosity = 1 pb-1s-1 • There is no overall optimum production mechanism – we would like have access to all. • Secondary beams from 60 kV to 1 GeV/u are needed to extract the science. Solution: SRF technology – Primary, high intensity, linear accelerator and efficient secondary accelerator LINAC 2004 Rare Isotope Accelerator - RIA • Efficient acceleration of elements up to uranium at 2.4x1013/s and E > 400 MeV/nucleon. Beam power of 400 kW. • Possibility to optimize the production method for a given nuclide. • Secondary beams at energies from 60 kV to 400 MeV/u . Schematic of the RIA Concept LINAC 2004 Artist’s Conception of RIA at ANL LINAC 2004 RIA SRF Cavities – All Tested by 2003 Legnaro MSU ßopt=0.49 805 MHz MSU/JLAB ßopt=0.63 805 MHz MSU SNS ßopt=0.83 805 MHz SNS ßopt=0.041 ßopt=0.085 ßopt=0.285 80.5 MHz 80.5 MHz 322 MHz LINAC 2004 β=0.49 Cryomodule Prototype (THP70) NSCL LINAC 2004 Tests of Nuclear Models – Binding Energies Sp = 0 r-process Sn = 0 10 8 Today exp 6 DusCZ Molal eV) 4 ComKZ SatNa M 2 Tachi SpaJo 0 JaneMass rence ( MassJane e Duflo f -2 LZe76 -4 known masses Pearson FRDM93 TF94 odel dif -6 DuZu94 m -8 -10 50 60 70 80 90 100 110 120 130 140 G. Bollen N (Z = 55) 100/d – 400 kW HI LINAC 2004 Changes in nuclear shell structure for n-rich nuclei J. Dobaczewski and W. The nuclear mean field Nazarewicz 126126 p1/2 h f5/2 potential is dependent 9/2 3p i f5/2 13/2 N=5 2f p3/2 on the number and type p1/2 h9/2 p3/2 f f7/2 of nucleons present in 7/2 1h h 8282 11/ d the nucleus. 2 3/2 g7/2 3s h11/2 s1/2 d3/2 N=4 2d g7/2 s1/2 d5/2 Shell structure for very d5/2 1g 5050 asymmetric nuclear g9/2 g9/2 matter will be different nono ssppinin veryvery didiffusffusee orbitorbit aroundaround tthhee than for normal N=Z ssuurfacerface harmonicharmonic exoticexotic nuclei/nuclei/ valleyvalley ofof nuclear material. neneutronutron dripdrip lineline oscillatooscillatorr hypernucleihypernuclei ββ-stability-stability Phil. Trans. R. Soc. Lond. A 356, 2007 (1998) LINAC 2004 S (MeV) 2n Weakening ofShell StructureinExoticNuclei 12 16 20 24 0 4 8 1.2 pprrototoondndriripplliinene 68 62 PROTON NUMBER HRIBF Present 56 N / Z 1 .5 50 N=80 N=86 N=84 N=82 1.8 44 RIA .01/s limit 2 .1 38 2.4 neneuuttrorondndriripp lliinene W. Nazarewicz J. Dobaczewski A 356,2007(1998) Phil. Trans.R. Soc.Lond. a nd LINAC 2004 Extreme Halos Reachable at RIA Example: 42Mg Theory BA Brown 10 0.50 42Mg - 40Mg Difference 0.40 Neutron 0.30 Proton 0.20 x density 2 0.10 1 r π 4 0.00 -0.10 0 5 10 15 20 Radius 0.1 x density (nucleons/fm) 2 r Neutron π 4 Proton 0.01 05101520 Radius (fm) Science: Pairing in low-density material - Interaction with continuum states - Efimov States - Reactions LINAC 2004 Nuclear Science needs to study n/p degree of freedom Approach Very hard Necessary to know what effective RIA-Fair-ISAC interactions operate in nuclei LINAC 2004 Nuclear Microphysics of the Universe X-ray burst (RXTE) RIA intensities (nuc/s) 4U1728-34 > 1012 102 331 1010 10-2 ) z 106 10-6 H ( y 330 c n e p process u q 329 e r F 328 r process 327 Nova (Chandra) 10 15 20 Time (s) Ne V382 Vel ss e Metal poor halo star c o (Keck, HST) r p p r 10 20 30 Wavelength (Α) Supernova (HST) EC protons crust processes neutrons E0102-72.3 Big Bang (WMAP) LINAC 2004 What is Unique about the RIA linac? • Possibility to optimize the production method • Multiple charge state acceleration – 400kW beam power – highest efficiency for rare stable isotope acceleration, e.g., 48Ca, 124Sn (this can yield gains of 100 to 1000) • Intense Uranium Beams at 400 MeV/u and 400 kW • Liquid Li production target + fragment separator + gas catcher system – Ability to handle 400 kW beams – Precision reaccelerated beams without chemical or half-life dependence – Same setup for all elements with short development times • 2.1 GeV 3He ( 1 GeV protons) at 400 kW intensity for ISOL targets LINAC 2004 Summary • The science of rare isotope facilities: • Nature of nucleonic matter – nuclei with special features (e.g.
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