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理研 RI ビームファクトリー（ RIBF ） での r 過程原子核の実験的研究の可能性 本林 透 理研仁科センター

理研 RI ビームファクトリー（ RIBF ） での r 過程原子核の実験的研究の可能性 本林 透 理研仁科センター. Note: RI beams in RIBF are very fast. stopped or degraded indirect methods nuclear structure (more indirect). Fast RI beams - RIPS. v ~0.3 c. v ~0.6 c. RIBF new facility. RI beams (<5 AMeV) - CRIB.

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理研 RI ビームファクトリー（ RIBF ） での r 過程原子核の実験的研究の可能性 本林 透 理研仁科センター

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  1. 理研 RI ビームファクトリー（RIBF）での r過程原子核の実験的研究の可能性 本林透 理研仁科センター Note: RI beams in RIBF are very fast. stopped or degraded indirect methods nuclear structure (more indirect) RIKEN

  2. Fast RI beams - RIPS v~0.3c v~0.6c RIBF new facility RI beams (<5 AMeV) - CRIB 1st beam in Dec. 2006 U beam in Mar. 2007 RI beams with U-fission: Mar 2007 - v~0.1c CNS RIBF: Accelerator Complex in RIKEN Nishina Center SHE (Z=110, 111, 112, 113) - GARIS ~5 MeV/nucleon pol. d beams SHARAQ, ….. UT 135 MeV/nucleon for light nuclei (1986-) to be or being built 350 MeV/nucleon up to U RIKEN

  3. RIBF can go further (furthest) from the stability valley. Produced at RIBF with intensity > 1 particle/day Projectile fragmentation In-flight U fission / fragmentation stable known found at RIKEN predicted magic numbers r-process RIKEN

  4. High precision measurements Basic parameters for r-process ☆ Half-lives（Ｔ1/2)  abundance  process speed ☆ Cross sections  location of the path Masses (A, Qβ) Resonances Continuum ☆b-delayed neutron（Pn）  final abundances Theory ☆ n process Thousands of nuclei along r-process Very low production yield RIKEN Nisimura, RIKEN (modified)

  5. Experimental information Nuclear structure • Half lives T1/2 • Level : e.g.E(2+) • n emission prob. (Pn) • Mass <= direct, Q • Cross sections • indirect • GT/ spin-dipole strength Systematic Study Shell quenching ? Deformation ? Fate of magic numbers • Appearance / Disappearance Feedback to Nuclear Theory Inputs Supernova simulation r-Process network calculation RIKEN Nisimura, RIKEN (modified)

  6. How ? method equipment RIKEN

  7. b-decay measurements – halflife, Pn spectroscopic studies (fast / stopped beams) - first experiments at the RIBF new facility BigRIPS + Zero Degree spectrometer RIKEN

  8. Zero-degree spectrometer γ particle ID / momentum analysis e.g.Doppler shifted g-ray measurements with identification of products (angle-integrated cross section) Multi-function BT line Medium resolution p/Dp ~2000 - 4000 pacc ±3% Commissioning in Oct. 2008 131Sn 132Sn 133Sn GRAPE (Ge) DALI2 (NaI) 132Sn b / isomer Spectroscopy without 2ndary target RIKEN γdetector From BigRIPS

  9. N=126 T1/2=1sec N=82 T1/2=1sec Half-life (T1/2) measurements Cal. by H.Koura, et al. (278113) T1/2=1sec N=50 • Half-life measurement • one month operation with 238U (1pnA) fission products • 40 isotopes ( N~50) • 70 isotopes (N ~ 80) RIKEN Nisimura, RIKEN (modified)

  10. 86Kr/136Xe/238U 1pmA 86Kr/136Xe/238U 1pmA N=82 N=82 Z=82 Z=82 N=50 N=50 N=28 N=28 N=126 N=126 Z=50 Z=50 N=20 N=20 r-process waiting points corresponding to r-process abundance peak Z=28 Z=28 Z=20 Z=20 • Calculation uses • 86Kr + Be Fragmentation EPAX2 • 136Xe + Be Fragmentation EPAX2 • 238U + Be Fragmentation EPAX2 • Fission DATA@GSI (limited) • 238U + Pb Fragmentation EPAX2 • Fission ABLABRA Estimated beam intensity at BigRIPS 86Kr/136Xe/238U 1pA 86Kr/136Xe/238U 1pmA 1,000 more new isotopes ! r-process waiting points corresponding to r-process abundance peak RIKEN • Calculation uses • 86Kr + Be Fragmentation EPAX2 • 136Xe + Be Fragmentation EPAX2 • 238U + Be Fragmentation EPAX2 • Fission DATA@GSI (limited) • 238U + Pb Fragmentation EPAX2 • Fission ABLABRA Aoi, RIKEN (modified)

  11. 86Kr/136Xe/238U 1pmA 86Kr/136Xe/238U 1pmA N=82 N=82 Z=82 Z=82 N=50 N=50 N=28 N=28 N=126 N=126 Z=50 Z=50 N=20 N=20 r-process waiting points corresponding to r-process abundance peak Z=28 Z=28 Z=20 Z=20 • Calculation uses • 86Kr + Be Fragmentation EPAX2 • 136Xe + Be Fragmentation EPAX2 • 238U + Be Fragmentation EPAX2 • Fission DATA@GSI (limited) • 238U + Pb Fragmentation EPAX2 • Fission ABLABRA Estimated beam intensity at BigRIPS Estimated beam intensity at BigRIPS 86Kr/136Xe/238U 1pA 86Kr/136Xe/238U 1pmA r-process A~130 ~78Ni ~54CaN=34 Island of Inversion PAC-approved studies RIKEN • Calculation uses • 86Kr + Be Fragmentation EPAX2 • 136Xe + Be Fragmentation EPAX2 • 238U + Be Fragmentation EPAX2 • Fission DATA@GSI (limited) • 238U + Pb Fragmentation EPAX2 • Fission ABLABRA Aoi, RIKEN (modified)

  12. r-process r-process Structure study of neutron-rich nuclei beyond 132Sn Physics Motivation 1. Comprehensive understanding of known exotic structure --- Breaking of Grodzins’ rule More neutron rich nucei? 2. Explore unknown exotic structure --- Breaking of N=82 or Z=50 magicity? * Strong Isospin dependent interaction? T.Otsuka et al., PRL97(06)162501. * Weak binding J. Dobaczewski et al., PRC53(96)2809. * ls-force, Neutron Skin …. 3. r-process RIKEN AOI, N., RIKEN Waiting point approximation . Using KUTY Private comm. with Dr. Y. Mochizuki.

  13. r-process r-process B.Chen et al., PLB355(95)37. Structure study of neutron-rich nuclei beyond 132Sn AOI, N., RIKEN Physics Motivation 1. Comprehensive understanding of known exotic structure --- Breaking of Grodzins’ rule More neutron rich nucei? 2. Explore unknown exotic structure --- Breaking of N=82 or Z=50 magicity? * Strong Isospin dependent interaction? T.Otsuka et al., PRL97(06)162501. * Weak binding J. Dobaczewski et al., PRC53(96)2809. * ls-force, Neutron Skin …. 3. r-process RIKEN Waiting point approximation . Using KUTY Private comm. with Dr. Y. Mochizuki.

  14. Cross sections - next step indirect determination – light nuclei, drip line, closed shell Coulomb dissociation, breakup (ANC), transfer mass – heavy nuclei BigRIPS + Zero Degree spectrometer SAMURAI SlowRI SHARAQ Rare RI (mass) Ring RIKEN

  15. (n,) (or (p,)) of astrophysical interest resonant direct (continuum) resonant A+n A+1 level density: low light nuclei closed shell near the drip line resonant (statistical) Direct measurement of   (almost) impossible Indirect methods Coulomb dissociation, ANC, (d,p) …. level density: high heavier nuclei RIKEN mass, optical potential, …

  16. High-energy photon production by fast Coulomb excitation (dissociation) virtual photon large cross section thick target charged particle detection field strength time frequency cgs13

  17. Invariant mass measurement - Coulomb dissociation for astrophysical (p,) reactions applicablet to (n,g) 26Si 27P beam 50 - 90 MeV/nucleon DALI g ray - bound states HODO 27P 27P* 26Si DErel : Independent of DEin RIKEN

  18. breakup happens here (p,g) happens here ANC in peripheral reactions: radiative proton capture, breakup and transfer Shape in asymptotic region given by Whittaker fct. Only normalization (ANC) unknown and needed! Trache, TAMU (modified)

  19. Breakup reactions for nuclear astrophysics Example: 8B 7Be (g.s / 1/2-) Momentum distributions → nlj Cross section→ ANC (only!!!) Gamma rays → config mixing BigRIPS + Zero Degree Need: Vp-target & Vcore-target and reaction mechanism model Trache, TAMU (modified)

  20. TRIAC – Tokai Radioactive Ion Accelerator Complex direct measurements of (d,p) etc for light unstable nuclei (d,p)  (n,g) around waiting points RIBF: degraded beams RIKEN Miyatake, TRIAC (modified)

  21. RIBF current and future plans SAMURAI (multi-particle) 2011 - use of IRC beams (moments, applications) SCRIT (e-RI) zero degree (spectrometer) new injector fRC SRC IRC BigRIPS Rare RI Ring (mass) Yamaguchi 135 MeV/nucleon for light nuclei 350 MeV/nucleon up to U SHARAQ (UT) (high-resolution Missing mass) 2008 (end) - Slow RI (gas stopper) RIKEN

  22. SAMURAI７ Tohoku (Kobayashi), TiTech, Kyoto, … RIKEN collaboration constructed in 2008-2011 super conducting magnet (3T) RI beam （from BigRIPS ） return yoke pole（2m dia.) Large solid-angle spectrometer particle correlation unbound sates (p,2p) astrophy. (p,), (n,) nucl. matter SAMURAI7 (Superconducting Analyzer for MUlti Particles from RAdioIsotope Beams with 7 Tm) coil vac. chamber target n turn table n-detector focal plane det. heavy projectile fragment p RIKEN

  23. ☆ Cross sections – heavy nuclei  location of the path Masses (A, Qβ) しかし….. RIKEN

  24. SLOWRI RF carpent RF carpent RIKEN (M. Wada) Universal slow RI beam production based on the rf ion guide method No Chemical Processes in Production & Separation No Isobar No Isotone Contamination trap laser MRTOF mass <=> ISOL Isotope separator slow RI beam ＳＰＩＧ RF ion guide cell RF carpet Ion trap colinierear laser MR TOF RIKEN

  25. Rare RI ring Tsukuba (Ozawa), … - RIKEN collaboration Isochronous ring with individual injection mass measurement for short-lived rarely-produced nuclei Yamaguchi ~100% injection < 100 s-1 particle ID kicker magnet Mass m/m~10-6* Beta decay, … Isochronous ring ＲＩ （from BigRIPS） * 200 keV for A=200 RIKEN

  26. Hauser Feshbach formula a + A  C  b + B (C: compound nucleus) ____ ____ a b ☆ Cross sections  location of the path Masses (A, Qβ) C formation resonant (statistical) Toptical pot. / fusion (partial) s experimental challenge !? c.f. isospin dependence in opt. pot. (Goliery) RIKEN

  27. RIBF (new facility) high-intensity (80 kW max.) fast H.I. beams (up to U) wide range of RI beam production first beam: Dec. 28, 2006, 27Al, 345 MeV/nucleon first result: 125Pd , end of May 2007 w. 1/100,000 U-intensity 2008 beam development (intensity, specy, ..) several PAC-approved experiments (48Ca campaign) ZeroDegree (with BigRIPS) in operation SHARAQ (high resolution) comissioning SAMURAI (large acceptance) construction (- 2011) various experimental equipments are planned PAC NP-PAC（Nucl. Phys., with CNS): twice a year 4th: 20-21 Nov. 2008 internatinal users meeting: 22 Nov. 2008 Visit http://www.nishina.riken.jp/UsersGuide/Nuclear/ # budget (5 months operation in FY 2008) Current intensity  extension of “standard” studies Examination of nucl. phys. inputs to ..

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