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Journey Along the Neutron Dripline &Production: transfer, fission, fragmentation &Predicted vanishing of the shells has major influence… &Proof of existence.

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Presentazione sul tema: "Journey Along the Neutron Dripline &Production: transfer, fission, fragmentation &Predicted vanishing of the shells has major influence… &Proof of existence."— Transcript della presentazione:

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2 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

3 Along the dripline from Z=0 to ….

4 Detection of Neutron Clusters F. M. Marques et al., Phys. Rev. C65 (2002)

5 14 Be  10 Be + 4n or 4 n F. M. Marques et al., Phys. Rev. C65 (2002)

6 4 n or not? F. M. Marques et al., Phys. Rev. C65 (2002)

7 Superheavy Hydrogen 5 H A. A. Korshennikov et al., Phys. Rev. Lett. 87 (2001)

8 Observation of 10 He A. A. Korshennikov et al., Phys. Lett. B326 (1994) 31

9 N=7 and the Level Inversion in 11 Be

10 Level Inversion of 11 Be

11 Configurations of 10 Li  s 1/2 +  p 3/2  2 - or 1 - p 1/2 +  p 3/2  2 + or 1 +

12 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

13 Invariant-Mass Spectroscopy M. Zinser et al., Nucl. Phys. A619 (1997) 151 d  /dT d (barn/MeV) Pb Target C Target Decay Energy (MeV)

14 Relative Velocity Measurements

15 Experimental Setup

16 A = (N/Z=2) +1 Nuclei

17 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

18 s-wave Strength in 10 Li MT et al., Phys. Rev. C59 (1999) 111

19 Virtual States E  ħ 2 /2ma 2

20 Scattering Length Calculations EnergyRelative velocity

21 9 He L. Chen et al., Phys. Lett. B505 (2001)

22 The N=7 Isotones

23 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

24 Extension to Unbound Nuclei 10 Li 9 He and 13 Be A. Ozawa et al., Phys. Rev. Lett. 84 (2000) 5493

25 Halo Nucleus 11 Li “A nuclear helium atom…” held together by the attractive long-range-part of the NN force

26 The Earth Apollo 17 Crew, NASA

27 RMS-Radii of Lithium Isotopes R rms (fm)

28 Neutron 9 Li Borromean Nucleus: 11 Li Heiko Scheit Neutron

29 Unbound Subsystems n 9 Li n nn  10 Li  Di-neutron

30 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 ( ); la fama della costruzione di questo "palazzo per la Sapienza" inizia con il Vasari nella seconda edizione delle Vite del VISITA VIRTUALE DEL COLLEGIO

31 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. V. Maddalena

32 DNA Borromean Rings Title frame by Scott Kim From the video "Not Knot" Copyright 1990 by the Geometry Center, University of Minnesota EMSL Collaboratory William R. Wiley Environmental Molecular Sciences Laboratory Pacific Northwest National Laboratory (PNNL), Richland, Washington Prof. Nadrian C. Seeman, Department of Chemistry New York University Knot Theory Symbol for Collaborations

33 More Borromean Rings Paul Bourke Brain Dynamics Research Laboratory Melbourne, Australia John Robinson, The University of Wales, Bango Mike Bailey, San Diego Supercomputer Center Art Telemanufacturing Geometry

34 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

35 Brunnian Links Robert Scharein Department of Computer Science University of British Columbia

36 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)

37 Ground State of 13 Be

38 13 Be Relative Velocity Spectrum s-wave, a s = -20fm d-wave, E Decay = 2MeV Background

39 Could 16 Be be bound? 2n Separation Energy 1n Separation Energy 16 Be: Constant Z (=4) Extrapolation 16 Be ??

40 16 Be : Constant N (=12) Extrapolation 2n Separation Energy1n Separation Energy No 16 Be

41 16 Be: Constant A (=16) Extrapolation 2n Separation Energy 1n Separation Energy 16 Be

42 Shell Model Calculation 16 Be ?? 19 B and 22 C are bound B.A. Brown, private communications

43 Previous Measurements H. Sakurai et al., Phys. Lett. 448B, 180 (1999) A.C. Muller and R. Anne, NIM B56, 557 (1991) 16 Be ??

44 Coupled Cyclotron Facility at the NSCL 40 Ar MeV/A 140 MeV/A 4.9  A 1.0  A 470nA 280nA 6.0 Tm 40 Ar Ar 18+

45 No Evidence for 16 Be 16 Be is not bound

46 Neutron Radioactivity First Observation of  -delayed Two-Neutron Radioactivity L.C. Carraze et al., Phys. Rev. Lett. 43 (1979) Be+2n 10 Be+n 11 Be 11 Li -- n 2n T 1/2 =8.7ms

47 Search for Neutron Radioactivity 16 B 

48 V (MeV) Centrifugal (l=2) Radius (fm) Nuclear Total 16 B Potential E = 10 keV  T 1/2 = 3.7· s E = 1 keV  T 1/2 = 1.1· s

49 16 B Lifetime Measurements 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

50 Lifetime of 16 B Direct Lifetime Measurements: Time of Flight Indirect Measurement: width of state  < 200 keV with:  = ħ   2· s Possible range for the 16 B lifetime

51 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

52 Production of 16 B 16 C + Target  15 B + p 17 C + Target  16 B + p

53 Energy Spectra 16 C + Target  15 B + p 17 C + Target  16 B + p

54 New Limits for 16 B Possible range for the 16 B lifetime  Reduction of almost 2 orders of magnitude New results

55 New Shell Structure? Z=8 N=8 N=16 ? N=20 ??

56 Evidence for N=16 Shell A. Ozawa et al., Phys. Rev. Lett. 84 (2000) 5493

57 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 , 2001, Maui, Hawaii

58 Search for 26 O D. Guillemaud-Mueller, et al. Phys. Rev. C41 (1990) 937 M. Fauerbach, et al. Phys. Rev. C53 (1996) O

59 Search for 28 O / Existence of 31 F H. Sakurai et al., Phys. Lett. 448B, 180 (1999)

60 2n Separation Energy Systematics Fe Cs 5056

61 Two-Neutron Separation Energies

62 Double Magic 78 Ni

63 Search for 78 Ni V.A. Rubchenya and J. Äystö, Nucl. Phys. A701 (2002) 127c Experimental Limit 0.1 μb Calculation 1 nb

64 Observation of 78 Ni M. Bernas et al., Phys. Lett. B415 (1997) nb

65 Identification of New Isotopes Ionization Chamber J. Benlliure et al. Nucl. Phys. A660 (1999) U Fragmentation 950 MeV/u Time of Flight Ion start stop  E (Ionization chamber or Si) Total Energy

66 Fission of Fission Fragments??


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