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PubblicatoGiorgia Di matteo Modificato 9 anni fa
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Journey Along the Neutron Dripline &Production: transfer, fission, fragmentation &Predicted vanishing of the shells has major influence… &Proof of existence is easy, 2 or 3 is sufficient &Proof of non-existence is much more difficult &“Nuclei” beyond the dripline
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Along the dripline from Z=0 to ….
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Detection of Neutron Clusters F. M. Marques et al., Phys. Rev. C65 (2002) 044006
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14 Be 10 Be + 4n or 4 n F. M. Marques et al., Phys. Rev. C65 (2002) 044006
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4 n or not? F. M. Marques et al., Phys. Rev. C65 (2002) 044006
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Superheavy Hydrogen 5 H A. A. Korshennikov et al., Phys. Rev. Lett. 87 (2001) 092501
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Observation of 10 He A. A. Korshennikov et al., Phys. Lett. B326 (1994) 31
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N=7 and the Level Inversion in 11 Be
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Level Inversion of 11 Be
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Configurations of 10 Li s 1/2 + p 3/2 2 - or 1 - p 1/2 + p 3/2 2 + or 1 +
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200 160 120 80 10 5 0 Indirect Measurements E R ( 10 Li) (MeV) Counts H. G. Bohlen et al., Nucl. Phys. A616 (1997) 254c 16 C( 12 C, 12 N) 10 Li, E Lab = 357 MeV
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Invariant-Mass Spectroscopy M. Zinser et al., Nucl. Phys. A619 (1997) 151 d /dT d (barn/MeV) Pb Target C Target Decay Energy (MeV) 0 1 2 3 32103210 0.3 0.2 0.1 0.0
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Relative Velocity Measurements
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Experimental Setup
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A = (N/Z=2) +1 Nuclei
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Calibration Reaction 7 He 6 He + n E R = 440±30 keV Г = 160 ±30 keV R.A. Kryger et al., Phys. Rev. C47 (1993) R2439
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s-wave Strength in 10 Li MT et al., Phys. Rev. C59 (1999) 111
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Virtual States E ħ 2 /2ma 2
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Scattering Length Calculations EnergyRelative velocity
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9 He L. Chen et al., Phys. Lett. B505 (2001)
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The N=7 Isotones
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Vanishing of the N = 8 Shell 9 Be – 13 C – 17 O 11 Be – 15 C 8 Li – 12 B – 16 N N=8 A. Ozawa et al., Phys. Rev. Lett. 84 (2000) 5493
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Extension to Unbound Nuclei 10 Li 9 He and 13 Be A. Ozawa et al., Phys. Rev. Lett. 84 (2000) 5493
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Halo Nucleus 11 Li “A nuclear helium atom…” held together by the attractive long-range-part of the NN force
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The Earth Apollo 17 Crew, NASA http://antwrp.gsfc.nasa.gov/apod/ap010204.html
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RMS-Radii of Lithium Isotopes R rms (fm)
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Neutron 9 Li Borromean Nucleus: 11 Li Heiko Scheit Neutron
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Unbound Subsystems n 9 Li n nn 10 Li Di-neutron
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Origin of the Borromean Rings Il collegio fu costruito su un'area di case e terreni in parte già appartenenti alla famiglia Borromeo su progetto dell'architetto Pellegrino Pellegrini figlio di Tibaldo (1527- 1596); la fama della costruzione di questo "palazzo per la Sapienza" inizia con il Vasari nella seconda edizione delle Vite del 1568. VISITA VIRTUALE DEL COLLEGIO http://borromeo.unipv.it/visita.htm
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Piano nobile Sala bianca Sala minore superiore, essa deve il suo nome alle pareti non affrescate. Il motivo decorativo della finta tappezzeria è costituito dai tre anelli intrecciati indicanti il legame inscindibile tra le famiglie Borromeo, Visconti e Sforza. Già originariamente adibita a concerti vocali e strumentali secondo le indicazioni del 1592 date da Federico Borromeo, costituì sala di ricevimento del principe patrono, tuttora comunica tramite doppie porte con l'appartamento poi ristrutturato a camere per studenti negli anni sessanta. Di queste stanze riservate ai soggiorni pavesi rimane interamente affrescata con decorazione ottocentesca la camera da letto. In questo secolo e fino agli anni della ristrutturazione l'appartamento del Patrono ospitò la biblioteca, la sala bianca ne fu sala di consultazione, di questa antica funzione sono rimasti gli armadi bassi per conservare le annate delle riviste. Translation: The decorative motif of the fake drapery is constituted by the three connected rings, indicating the indestructible link between Borromeo, Visconti and Sforza families. http://borromeo.unipv.it/visita.htm, V. Maddalena
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DNA Borromean Rings Title frame by Scott Kim From the video "Not Knot" Copyright 1990 by the Geometry Center, University of Minnesota http://www.geom.umn.edu EMSL Collaboratory William R. Wiley Environmental Molecular Sciences Laboratory Pacific Northwest National Laboratory (PNNL), Richland, Washington http://www.emsl.pnl.gov:2080/docs/collab/ Prof. Nadrian C. Seeman, Department of Chemistry New York University http://seemanlab4.chem.nyu.edu/borro.html Knot Theory Symbol for Collaborations
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More Borromean Rings Paul Bourke Brain Dynamics Research Laboratory Melbourne, Australia http://www.mhri.edu.au/~pdb/geometry/borromean/ John Robinson, The University of Wales, Bango http://www.bangor.ac.uk/SculMath/image/symbscul.htm Mike Bailey, San Diego Supercomputer Center http://www.sdsc.edu/GatherScatter/GSspring95/gsspring_a17.html Art Telemanufacturing Geometry
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Other Usage of the Rings Recognizing the Importance of Undergraduate Science Education, Robert C. Hilborn, APS News February 1997 Undergraduate Science Education Pre-College Science Education Graduate Education and Research
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Brunnian Links http://www.cs.ubc.ca/nest/imager/contributions/scharein/brunnian/brun6-rem3.mpg Robert Scharein Department of Computer Science University of British Columbia http://www.cs.ubc.ca/nest/imager/contributions/scharein/brunnian/brunnian.html
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Determination of Dripline… Evidence for Particle Instability of 13 Be and 14 Be A.G.Artukh, V.V.Avdeichikov, J.Ero, G.F.Gridnev, V.L.Mikheev, V.V.Volkov, J.Wilczynski Phys.Lett. 33B, 407 (1970) Discovery of Two Isotopes, 14 Be and 17 B, at the Limits of Particle Stability J.D.Bowman, A.M.Poskanzer, R.G.Korteling, G.W.Butler Phys.Rev.Lett. 31, 614 (1973)
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Ground State of 13 Be
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13 Be Relative Velocity Spectrum s-wave, a s = -20fm d-wave, E Decay = 2MeV Background
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Could 16 Be be bound? 2n Separation Energy 1n Separation Energy 16 Be: Constant Z (=4) Extrapolation 16 Be ??
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16 Be : Constant N (=12) Extrapolation 2n Separation Energy1n Separation Energy No 16 Be
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16 Be: Constant A (=16) Extrapolation 2n Separation Energy 1n Separation Energy 16 Be
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Shell Model Calculation 16 Be ?? 19 B and 22 C are bound B.A. Brown, private communications
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Previous Measurements H. Sakurai et al., Phys. Lett. 448B, 180 (1999) A.C. Muller and R. Anne, NIM B56, 557 (1991) 16 Be ??
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Coupled Cyclotron Facility at the NSCL 40 Ar 7+ 12.3 MeV/A 140 MeV/A 4.9 A 1.0 A 470nA 280nA 6.0 Tm 40 Ar 7+ 40 Ar 18+
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No Evidence for 16 Be 16 Be is not bound
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Neutron Radioactivity First Observation of -delayed Two-Neutron Radioactivity L.C. Carraze et al., Phys. Rev. Lett. 43 (1979) 1652 9 Be+2n 10 Be+n 11 Be 11 Li -- n 2n T 1/2 =8.7ms
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Search for Neutron Radioactivity 16 B
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V (MeV) Centrifugal (l=2) Radius (fm) -40 -20 0 20 10 15 -60 60 40 5 Nuclear Total 16 B Potential E = 10 keV T 1/2 = 3.7·10 -16 s E = 1 keV T 1/2 = 1.1·10 -13 s
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16 B Lifetime Measurements 13 14 15 16 17 H. G. Bohlen et al., Nucl. Phys. A583 (1995) 775 J. D. Bowman et al., Phys. Rev. C9 (1974) 836 M. Langevin et al., Phys. Lett. 150B (1985) 71
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Lifetime of 16 B 10 -9 10 -10 10 -11 10 -12 10 -13 10 -14 10 -15 10 -16 10 -17 10 -18 10 -19 10 -20 10 -21 10 -7 10 -8 Direct Lifetime Measurements: Time of Flight Indirect Measurement: width of state < 200 keV with: = ħ 2·10 -21 s Possible range for the 16 B lifetime
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Stopping of Fragments 16 C + 12 C 15 B 17 C + 12 C 16 B Beams of 17 C, 16 C Secondary Target: 114 mg/cm 2 12 C 5cm Si- E Si-E
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Production of 16 B 16 C + Target 15 B + p 17 C + Target 16 B + p
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Energy Spectra 16 C + Target 15 B + p 17 C + Target 16 B + p
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New Limits for 16 B 10 -9 10 -10 10 -11 10 -12 10 -13 10 -14 10 -15 10 -16 10 -17 10 -18 10 -19 10 -20 10 -21 10 -7 10 -8 Possible range for the 16 B lifetime Reduction of almost 2 orders of magnitude New results
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New Shell Structure? Z=8 N=8 N=16 ? N=20 ??
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Evidence for N=16 Shell A. Ozawa et al., Phys. Rev. Lett. 84 (2000) 5493
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Search for 21 B Session SD - Nuclear Structure IV: Light Nuclei. ORAL session, Saturday morning, October 20 Illima, Outrigger Wailea Resort [SD.007] Search for 21 B Y. Yamaguchi, T. Suzuki, T. Izumikawa, T. Kato, Y. Kawamura (Niigata University, Japan), A. Ozawa, T. Yamaguchi, T. Zheng, R. Kanungo, T.Ohnishi, T. Suda, I. Tanihata, K. Yoshida (RIKEN, Japan), S. Momota (Kochi University of Technology, Japan), K. Kimura (Nagasaki Institute of Applied Science, Japan) We performed search for 21 B with a 95A MeV beam of 40 Ar for the first time. Recently, we observed that a new magic number N=16 appears in very neutron-rich nuclei so that the very neutron-rich 21 B may be bound. The production cross section of A B isotopes (A = 15,17,19,21) on Be and Ta targets have been measured through projectile fragmentation. Particles were identified by the time of flight (TOF), the energy loss (ΔE), and the magnetic rigidity (Bρ) using the fragment separator RIPS at RIKEN. We observed no event of 21 B. The upper limit for the production cross section as well as the comparison with the empirical parametrization code (EPAX) will be presented. First Joint Meeting of the Nuclear Physicists of the American and Japanese Physical Societies, October 17 - 20, 2001, Maui, Hawaii
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Search for 26 O D. Guillemaud-Mueller, et al. Phys. Rev. C41 (1990) 937 M. Fauerbach, et al. Phys. Rev. C53 (1996) 647 26 O
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Search for 28 O / Existence of 31 F H. Sakurai et al., Phys. Lett. 448B, 180 (1999)
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2n Separation Energy Systematics Fe Cs 5056
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Two-Neutron Separation Energies
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Double Magic 78 Ni
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Search for 78 Ni V.A. Rubchenya and J. Äystö, Nucl. Phys. A701 (2002) 127c Experimental Limit 0.1 μb Calculation 1 nb
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Observation of 78 Ni M. Bernas et al., Phys. Lett. B415 (1997) 111 0.3 nb
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Identification of New Isotopes Ionization Chamber J. Benlliure et al. Nucl. Phys. A660 (1999) 87 238 U Fragmentation 950 MeV/u Time of Flight Ion start stop E (Ionization chamber or Si) Total Energy
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Fission of Fission Fragments??
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