The National Superconducting Cyclotron State University

Transcription

1 The National Superconducting Cyclotron State University U.S. flagship user facility for rare isotope research and education in nuclear science, astro-nuclear physics, accelerator physics, and societal applications Betty Tsang, Asy-EOS Slide 1

2 Betty Tsang, Asy-EOS Slide 2

3 Michigan State University Betty Tsang, Asy-EOS Slide 3

4 Facility for Rare Isotope Beams (FRIB) FRIB will provide intense beams of rare isotopes (that is, short-lived nuclei not normally found on Earth). FRIB will enable scientists to make discoveries about the properties of these rare isotopes in order to better understand the physics of nuclei, nuclear astrophysics, fundamental interactions, and applications for society. Betty Tsang, Asy-EOS Slide 4

5 282 employees, including 24 faculty, 46 graduate, and 51 undergraduate students. (as of March 05) 489 employees, including 40 faculty, 64 graduate and 70 undergraduate students as of August 16, 2011 Betty Tsang, Asy-EOS Slide 5

6 Facility for Rare Isotope Beams (FRIB) FRIB will provide intense beams of rare isotopes (that is, short-lived nuclei not normally found on Earth). FRIB will enable scientists to make discoveries about the properties of these rare isotopes in order to better understand the physics of nuclei, nuclear astrophysics, fundamental interactions, and applications for society. Betty Tsang, Asy-EOS Slide 6

7 Graffiti Art, Dequindre Cut, Detroit, August, 2012 Artist: Kobie Solomon Betty Tsang, Asy-EOS Slide 7

8 Nuclear Equation of State E/A (,) = E/A (,0) + 2 S() = ( n - p )/ ( n + p ) = (N-Z)/A Research with rare isotope beams Nuclear Structure What is the nature of the nuclear force that binds protons and neutrons into stable nuclei and rare isotopes? Nuclear Astrophysics What is the nature of neutron stars and dense nuclear matter? What is the origin of elements heavier than iron in the cosmos? What are the nuclear reactions that drive stars and stellar explosions? Tests of Fundamental Symmetries Why is there now more matter than antimatter in the universe? Betty Tsang, Asy-EOS Slide 8

9 Nuclear Equation of State E/A (,) = E/A (,0) + 2 S() = ( n - p )/ ( n + p ) = (N-Z)/A Research with rare isotope beams Nuclear Structure What is the nature of the nuclear force that binds protons and neutrons into stable nuclei and rare isotopes? Nuclear Astrophysics What is the nature of neutron stars and dense nuclear matter? What is the origin of elements heavier than iron in the cosmos? What are the nuclear reactions that drive stars and stellar explosions? Tests of Fundamental Symmetries Why is there now more matter than antimatter in the universe? Betty Tsang, Asy-EOS Slide 9

10 E/A (, ) = E/A (,0) + 2 S() EoS of asymmetric matter = ( n - p )/ ( n + p ) = (N-Z)/A1 Constraints from Heavy Ion Collisions (HIC) B.A. Brown,PRL85(2000)5296 Tsang et al,prl102,122701(2009) The symmetry energy influences many properties of neutron stars: Radii, moments of inertia Cooling rates Phase transitions in interior The symmetry energy dominates the uncertainty in the n-matter EOS. E sym S o L B K sym 18 B Betty Tsang, Asy-EOS Slide 10

11 Consistent Constraints on Symmetry Energy from different experiments HIC is a viable probe Isobaric Analogue States NPA 818, 36 (2009) HIC: heavy ion collisions; PRL 102,122701(2009) Finite Droplet Range Model PRL108,052501(2012) p elastic scattering PRC82,044611(2010) Pygmy Dipole Resonances PRC 81, (2010) neutron-star radius PRL108,01102(2012) E sym S o L B K sym 18 B Tsang et al. C 86, (2012) Betty Tsang, Asy-EOS Slide 11

12 Proton Number Z E/A (, ) = E/A (,0) + 2 S() EoS of asymmetric matter = ( n - p )/ ( n + p ) = (N-Z)/A1 Isospin degree of freedom B a Aa A Z( Z 1) a C 2/3 V S 1/ 3 2 A ( A 2Z) a sym A Constraints from Heavy Ion Collisions (HIC) Tsang et al,prl102,122701(2009) Neutron Number N To improve experimental constraints: : constraints mainly obtained from ID : Increase the (A-2Z) 2 /A; RI beams : Identify new observables : remeasure n/p ratios Betty Tsang, Asy-EOS Slide 12

13 NSCL Experiment 07038: Precision Measurement of Isospin Diffusion Talk by J.R. Winkelbauer Investigates the density-dependence of the nuclear symmetry energy using isospin diffusion from residues new observable 112,118,124 Sn+ 112,118,124 Sn Collisions Combines the MSU Miniball, the LASSA Array, & S800 Spectrograph Incoming Beam, 70 MeV/u Beam-like fragments 10<Z<50 Betty Tsang, Asy-EOS Slide 13

14 Isospin diffusion experiments with RIB Betty Tsang, Asy-EOS Slide 14

15 Isospin Diffusion Experimental Setup at RIKEN BigRIPS Zero Degree Spectrometer WU microball Target 15 Betty Tsang, Asy-EOS Slide 15

16 Physics at high density I???? B.A. Brown,PRL85(2000)5296 B. Liu Tsang et al. et PRC 65(2002) al,prl102,122701(2009) Large uncertainties in the symmetry energy high density. At < 0 density, mass splitting increase with density and asymmetry Betty Tsang, Asy-EOS Slide 16

17 nucleon effective masses from n/p ratios miniball n-wall LASSA Use n/p spectral ratios and double ratios to probe m n * and m p * and E sym 124 Sn+ 124 Sn; 112 Sn+ 112 Sn,E/A=120 MeV (Coupland, Youngs) 48 Ca+ 124 Sn; 40 Ca 112 Sn,E/A=140 MeV (Hodges, Rachel) Sn+Sn, E/A=120 MeV Coupland et al, Zhang, private communications Betty Tsang, Asy-EOS Slide 17

18 Large scintillation arrays at great distance (TOF) Experimental challenges in detecting n and p yield γ 50 MeV Small Si-CsI arrays close to target (DE-E) protons H n 120 MeV q CM (deg) neutrons Rejected He TOF E CM (MeV) Many more particles detected by the neutron detectors in 124 Sn+ 124 Sn reactions than n s Different coverage in geometry and energy for particles Betty Tsang, Asy-EOS Slide 18

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20 Symmetry Energy Project: International collaboration to determine the symmetry energy over a range of densities RIBF 12, FRIB 20,RISP? GSI 11 FAIR Betty Tsang, Asy-EOS Slide 20

21 ASY-EOS May AMeV 96 Zr AMeV 96 Ru AMeV ~ 5x10 7 Events for each system Beam Line Krakow array Chimera TofWall MicroBall target Russotto & Lemmon Shadow Bar Land (not splitted) Betty Tsang, Asy-EOS Slide 21

22 To probe symmetry energy at > 0 with sub-threshold pions from HIC B.A. Brown,PRL85(2000)5296 Tsang et al,prl102,122701(2009) 124 Sn+ 124 Sn E lab =120 MeV/A b = 1fm BUU from: Danielewicz, NPA673, 375 (2000). Bickley et al., private comm. (2009) New observables: p - /p + ratio New detectors: SAMURARI- Time Projection Chamber Active Target -Time Projection Chamber Betty Tsang, Asy-EOS Slide 22

23 SAMURAI-TPC Time-projection chamber (TPC) will sit within SAMURAI dipole magnet Auxiliary detectors for heavy-ions and neutrons, and trigger Nebula (neutron array) SAMURAI-TPC Hodoscope beam SAMURAI dipole magnet and vacuum chamber Drawing courtesy of T. Betty Tsang, Asy-EOS Slide 23

24 Heavy Ion Collisions at high density with RIB Betty Tsang, Asy-EOS Slide 24

25 Importance of 3-body neutron-neutron force in the Equation of State of pure neutron matter Summary of 208 Pb n-skin thickness constraints neutron star Model calculations with and without 3nn forces: BHF: PRC80, (2009) Brueckner-Hartree-Fock DBHF: arxiv: Dirac Brueckner-Hartree-Fock CEFT :PRL105,161102(2010) Chiral Effective Field Theory QMC :PRC85,032801R(2012) Quantum Monte Carlo Tsang et al.prc (in print) arxiv: Betty Tsang, Asy-EOS Slide 25

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27 Study of Fission barriers of exotic nuclei with AT-TPC & PAT-TPC Provide constraints for fission cycling, beta-delayed and neutrino-induced fission contributions to r-process yields Extrapolations of ground state and fission saddle point binding energies away from the valley of stability Measurements of the excitation functions of fission cross-sections of exotic nuclei p+ 195 Tlfission at E/A=75, 65, 55, 50, 40, 35 MeV (NSCL#12014) etc. Corona Ring Beam Entrance Field Cage Endplate 6 He+ 4 He Micromegas Cathode Voltage Feed-through Betty Tsang, Asy-EOS Slide 27

28 Active Target -Time Projection Chamber Lead PI :W. Mittig; Project leader: D. Bazin; Co-PI: W. Lynch Broad innovative scientific program. Two alternate modes of operation Fixed Target Mode with solid target inside chamber: 4p tracking of charged particles allows full event characterization Active Target Mode: Chamber gas acts as both detector and target (H 2, D 2, 3 He, Ne, etc.) Provides a thick target for low intensity beams while retaining high resolution and efficiency AT-TPC will allow inverse kinematics studies in astrophysical, resonant, transfer, breakup, fusion, fission reactions and to study the EOS using giant resonances and heavy ion reactions. AT-TPC will make use of the full range of beam energies and intensities available from the CCF and ReA3 and extend the scientific reach of both. Betty Tsang, Asy-EOS Slide 28

29 Summary HiRA provides capabilities to use transfer reactions to investigate single particle levels in exotic nuclei from fast beams. Charged particle decay spectroscopy reveals structure and decay modes at the proton drip-line. Consistent constraints on the symmetry energy at sub-saturation densities with different experiments suggest that heavy ion collisions provide a good probe at high density.. Experiments to measure constraints on the symmetry energy above saturation densities have started with n/p ratios and will continue with pion and flow measurements with the AT-TPC The AT-TPC and its prototype have a broad science program to study fission barriers of exotic nuclei, transfer reactions, isobaric analog and cluster states and giant resonanes. The AT-TPC will be ready for experiments with ReA3. Betty Tsang, Asy-EOS Slide 29

30 Nuclear Structure studies with Transfer Reactions single partilcle structure of unstable nuclei pf shell 2p 3/2 N=28 gap Spectroscopy of N=27 isotones 1f 7/2 N=20 gap 2p 3/2 1d 3/2 2s 1/2 1f 7/2 2s 1/2 1d 3/2 H( 46 Ar,d) 45 Ar H( 56 Ni,d) 55 Ni (Sanetullaev, PhD, 2011) Betty Tsang, Asy-EOS Slide 30

31 Nuclear Reactions To study nuclear structure and the equation state of nuclear matter Faculty: Lynch, Mittig, Tsang, Westfall Detectors: HiRA, neutron wall, AT-TPC & its prototype Transfer reactions: What are the properties of single particle orbits? Decay spectroscopy of Nuclei at the drip-lines: What is their structure and how do they decay? Fission Barriers of exotic nuclei: How to extrapolate the Fission Barriers for nuclei relevant to the r- process? What is the EoS of Asymmetric Matter? Sub-saturation densities Supra-saturation densities Betty Tsang, Asy-EOS Slide 31

32 Looking forward to the AT-TPC at ReA3 Prototype (½ scale) AT-TPC NIMA660,64(2011) NIMA, (2012) Corona Ring Beam Entrance Field Cage Cathode Voltage Feed-through 6 He+ 4 He Micromegas Endplate Scientific programs for AT- TPC and its prototype: Transfer Reactions to measure SF s, ANC s Neutron particle states in neutron rich exotic nuclei using (d,p). Proton particle states in protonrich nuclei using ( 3 He,d). Isobaric Analog Resonances: A Z(p,p) Probe structure of states in A+1 Z: determine E *, J, L, SF s Cluster states in the continuum. Fission Barriers of exotic nuclei etc. Betty Tsang, Asy-EOS Slide 32

33 Experiments with AT-TPC Prototype Prototype (½ scale) AT-TPC NIMA660,64(2011) NIMA (in print) Corona Ring Beam Entrance Field Cage Endplate a+ 6 He a + 6 He a+ 6 He a + 6 He * a+2n 6 He+ 4 He Micromegas Cathode Voltage Feed-through Experiments at Notre Dame: - 6 He+ 4 He ( 10 Be decay spectroscopy) - 10 Be+ 4 He ( 14 C decay spectroscopy) - 6 He+ 40 Ar (complete and incomplete fusion) Betty Tsang, Asy-EOS Slide 33

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35 Decay spectroscopy for dripline nuclei Decay of proton unbound nuclei explosive hydrogen burning in X-ray bursts 69 Br p+ 68 Se waiting point. (Rogers, PhD 2009; PRL106, (2011) ) 73 Rb p+ 72 Kr, (NSCL#10015) Other programs: 8 C g.s. 2p+2p+a 8 B IAS 2p+ 6 Li IAS + (NSCL#10001) 16 Ne and 16 F IAS, (NSCL#11001) Betty Tsang, Asy-EOS Slide 35

36 Hubble ST Proton Number Z Strategies used to study the symmetry energy with Heavy Ion collisions below E/A=100 MeV Isospin degree of freedom B a Aa A Z( Z 1) a C 2/3 V S 1/ 3 2 A ( A 2Z) a sym A Neutron Number N Crab Pulsar Vary the N/Z compositions of projectile and targets 124 Sn+ 124 Sn, 124 Sn+ 112 Sn, 112 Sn+ 124 Sn, 112 Sn+ 112 Sn Measure N/Z compositions of emitted particles n & p yields isotopes yields: isospin diffusion Simulate collisions with transport theory Find the symmetry energy density dependence that describes the data. Constrain the relevant input transport variables. Betty Tsang, Asy-EOS Slide 36

37 Hubble ST Proton Number Z Strategies used to study the symmetry energy with Heavy Ion collisions below E/A=100 MeV Isospin degree of freedom B a Aa A Z( Z 1) a C 2/3 V S 1/ 3 2 A ( A 2Z) a sym A Neutron Number N Crab Pulsar Vary the N/Z compositions of projectile and targets 124 Sn+ 124 Sn, 124 Sn+ 112 Sn, 112 Sn+ 124 Sn, 112 Sn+ 112 Sn Measure N/Z compositions of emitted particles n & p yields isotopes yields: isospin diffusion Simulate collisions with transport theory Find the symmetry energy density dependence that describes the data. Constrain the relevant input transport variables. Betty Tsang, Asy-EOS Slide 37

38 2. Proposed Experimental Set up Microball from WU Chamber from RIKEN Scintillator & degrader foil ladder Betty Tsang, Asy-EOS Slide 38

39 Heavy Ion Collisions at high density with RIB B. Liu et al. PRC 65(2002) E/A (, ) = E/A (,0) + 2 S() = ( n - p )/ ( n + p ) = (N-Z)/A?? B.A. Brown,PRL85(2000)5296 Tsang et al,prl102,122701(2009) At < 0 density, consistent constraints Effect of mass splitting increase with density and asymmetry Large uncertainties in the symmetry energy high density. Betty Tsang, Asy-EOS Slide 39

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