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

Along the dripline from Z=0 to ….

Detection of Neutron Clusters

F. M. Marques et al., Phys. Rev. C65 (2002) 044006

14Be 10Be + 4n or 4n

F. M. Marques et al., Phys. Rev. C65 (2002) 044006

4n or not?

F. M. Marques et al., Phys. Rev. C65 (2002) 044006

Superheavy Hydrogen 5H

A. A. Korshennikov et al., Phys. Rev. Lett. 87 (2001) 092501

Observation of 10He

A. A. Korshennikov et al., Phys. Lett. B326 (1994) 31

N=7 and the Level Inversion in 11Be

Level Inversion of 11Be

Configurations of 10Li

s1/2 + p3/2

2- or 1-

p1/2+ p3/2

2+ or 1+

200

160

120

80

10 5 0

Indirect Measurements

ER(10Li) (MeV)

Cou

nts

H. G. Bohlen et al., Nucl. Phys. A616 (1997) 254c

16C(12C, 12N)10Li, ELab = 357 MeV

Invariant-Mass Spectroscopy

M. Zinser et al., Nucl. Phys. A619 (1997) 151

d/d

Td (

barn

/MeV

)Pb Target

C Target

Decay Energy (MeV)0 1 2 3

3

2

1

00.3

0.2

0.1

0.0

Relative Velocity Measurements

Experimental Setup

Detector

1 meter

O

Li

Neutron Detectors

BeTarget

O18

9

18

9 FragmentQuadrupole Doublet

Dipole

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

n

3H

6He8He

7Be

8Li 9Li

8B

9C

11Li

11Be10Be 12Be 14Be

12B 13B 14B 15B

10C 11C 15C14C 16C 18C17C 19C

17B

10Li

19B

p 2H

4He3He

6Li 7Li

9Be

10B 11B

12C 13C 20C 22C

16B13Be

7He

4H

Calibration Reaction

7He 6He + n

ER = 440±30 keV

Г = 160 ±30 keV

R.A. Kryger et al., Phys. Rev. C47 (1993) R2439

s-wave Strength in 10Li

p 67%1/2

s 33%1/2

Dec

ay P

roba

bili

ty

Cou

nts

MT et al., Phys. Rev. C59 (1999) 111

Virtual States

0 0.1 0.2 0.3 0.4 0.5M o m en tu m k [f m -1 ]

0.1

1

10

100

1000

W(k

) [

fm3 ]

9Be(12Be,9Li+n)XE s ,p ,d ( in itia l)= -3 .1 7 ,-3 .8 5 ,-4 .9 5 M eVl= 0 a s= -5 ,-1 0 ,-2 0 ,-5 0 f ml= 1 E 1 = 0 .1 , 0 .5 , 1 M eVl= 2 E 2 = 2 .0 M e V

N o I

N o I

E ħ2/2ma2

Scattering Length Calculations

EDecay (MeV)

Yie

ld (

arb

. un

its)

0

10

20

30

40

50

-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5

vn-vf (cm/ns)

0.1

1.0

0.0 0.2 0.4 0.6 0.8 1.0

Yie

ld (

arb

. un

its)

0

-2-1

-5

-10

-100

-30-20

-50

0-5

-10

-100

-30

-20

-50

Energy Relative velocity

9He

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

The N=7 Isotones

8 7 6 5 4 3 2Atom ic Num ber Z

-14

-12

-10

-8

-6

-4

-2

0

2

E*-

Sn

[M

eV]

14N 13C 12B 11Be 10Li 9He15O

0 10

r [fm ]

0 10 20 30 40

r [fm ]

0 10 20

r [fm ]

15O

11Be

10Li0.5 M eV

1/2+

1/2 -

Vanishing of the N = 8 Shell

9Be – 13C – 17O11Be – 15C

8Li – 12B – 16N

N=8

A. Ozawa et al., Phys. Rev. Lett. 84 (2000) 5493

Extension to Unbound Nuclei

10Li

9He and 13Be

A. Ozawa et al., Phys. Rev. Lett. 84 (2000) 5493

Halo Nucleus 11Li

“A nuclear helium atom…” held together by the attractive long-range-part of the NN force

The Earth

Apollo 17 Crew, NASA

http://antwrp.gsfc.nasa.gov/apod/ap010204.html

RMS-Radii of Lithium Isotopes

Rrm

s (fm

)

Neutron

9Li

Borromean Nucleus: 11Li

Heiko Scheit

Neutron

Unbound Subsystems

n

9Li

n

9Li

n n

10Li 10Li 10Li 10Li Di-neutron Di-neutron

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

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

DNA

Borromean Rings

Title frame by Scott KimFrom the video "Not Knot"Copyright 1990 by the Geometry Center,University of Minnesotahttp://www.geom.umn.edu

EMSL CollaboratoryWilliam R. Wiley Environmental Molecular Sciences LaboratoryPacific Northwest National Laboratory (PNNL), Richland, Washingtonhttp://www.emsl.pnl.gov:2080/docs/collab/

Prof. Nadrian C. Seeman, Department of Chemistry New York Universityhttp://seemanlab4.chem.nyu.edu/borro.html

Knot Theory

Symbol forCollaborations

More Borromean Rings

Paul BourkeBrain Dynamics Research LaboratoryMelbourne, Australiahttp://www.mhri.edu.au/~pdb/geometry/borromean/

John Robinson, The University of Wales, Bangohttp://www.bangor.ac.uk/SculMath/image/symbscul.htm

Mike Bailey,San Diego Supercomputer Centerhttp://www.sdsc.edu/GatherScatter/GSspring95/gsspring_a17.html

Art

Telemanufacturing

Geometry

Other Usage of the Rings

Recognizing the Importance of Undergraduate Science Education,Robert C. Hilborn, APS News February 1997

UndergraduateScience EducationPre-College

Science Education

Graduate Educationand Research

Brunnian Links

http://www.cs.ubc.ca/nest/imager/contributions/scharein/brunnian/brun6-rem3.mpg

Robert SchareinDepartment of Computer ScienceUniversity of British Columbiahttp://www.cs.ubc.ca/nest/imager/contributions/scharein/brunnian/brunnian.html

Determination of Dripline…

Evidence for Particle Instability of 13Be and 14Be

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, 14Be and 17B, at the Limits of Particle Stability

J.D.Bowman, A.M.Poskanzer, R.G.Korteling, G.W.Butler

Phys.Rev.Lett. 31, 614 (1973)

Ground State of 13Be

13Be Relative Velocity Spectrum

s-wave, as = -20fm

d-wave,EDecay = 2MeV

Background

v - v (cm /n s)n f

Cou

nts

0

1 0 0

2 0 0

3 0 0

4 0 0

5 0 0

-3 .0 -2 .0 -1 .0 0 .0 1 .0 2 .0 3 .0

Could 16Be be bound?

-202468

1012141618

6 8 10 12 14 16A

1n 2

n Se

para

tion

Ene

rgie

s (M

eV)

2n Separation Energy 1n Separation Energy

16Be: Constant Z (=4) Extrapolation

16Be ??

16Be : Constant N (=12) Extrapolation

-505

10152025303540

3 4 5 6 7 8 9 10 11 12 13

Z

1n 2

n S

epar

atio

n E

ner

gie

s (M

eV)

2n Separation Energy 1n Separation Energy

No 16Be

16Be: Constant A (=16) Extrapolation

-5

0

5

10

15

20

25

30

3 4 5 6 7 8 9 10

Z

1n 2

n S

epar

atio

n E

ner

gies

(M

eV)

2n Separation Energy 1n Separation Energy

16Be

Shell Model Calculation

16Be ?? 19B and 22C are boundB.A. Brown, private communications

Previous Measurements

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

16Be ??

Coupled Cyclotron Facility at the NSCL

40Ar7+

12.3 MeV/A140 MeV/A

4.9A

1.0A470nA

280nA

6.0 Tm

40Ar7+

40Ar18+

No Evidence for 16Be

16Be is not bound 16Be is not bound

Neutron Radioactivity

First Observation of -delayed Two-Neutron Radioactivity

L.C. Carraze et al., Phys. Rev. Lett. 43 (1979) 1652

9Be+2n

10Be+n11Be

11Li-

n2n

T1/2=8.7ms

Search for Neutron Radioactivity

16B

1 2 s

/ 1

3 2

p /

11

2 s

/ 2

1 2 s

/ 1

1 2 p

/ 1

3 2 p

/ 1

5 2 /

d 1

Last neutron

V (

MeV

) Centrifugal (l=2)

Radius (fm)

-40

-20

0

20

2010 15

-60

60

40

5

Nuclear

Total

16B Potential

E = 10 keV T1/2 = 3.7·10-16sE = 1 keV T1/2 = 1.1·10-13s

16B 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

Lifetime of 16B

10-9

10-10

10-11

10-12

10-13

10-14

10-15

10-16

10-17

10-18

10-19

10-20

10-2110-7

10-8

Direct LifetimeMeasurements:Time of Flight

Indirect Measurement:width of state < 200 keV

with: = ħ 2·10-21s

Possible range for the 16B lifetime

Stopping of Fragments

16C + 12C 15B 17C + 12C 16B

Beams of 17C, 16C

Secondary Target:114 mg/cm2 12C

5cm

Si-E Si-E

Production of 16B

13 B 15B

0

20

30

40

10

0 20 40 60 80Mass (arb. units)

Cou

nts

16C + Target 15B + p16C + Target 15B + p 17C + Target 16B + p17C + Target 16B + p

13B 15B

16B

Mass (arb. units)

0

30

60

90

120

Cou

nts

0 20 40 60 80

Energy Spectra

16C + Target 15B + p16C + Target 15B + p

600 650 700 750Energy (MeV)

5

10

15

Cou

nts

17C + Target 16B + p17C + Target 16B + p

Cou

nts

Energy (MeV)

5

10

15

600 650 700 750 800

New Limits for 16B

10-9

10-10

10-11

10-12

10-13

10-14

10-15

10-16

10-17

10-18

10-19

10-20

10-2110-7

10-8

Possible range for the 16B lifetime

Reduction of almost 2 orders of magnitude

New results

New Shell Structure?

Z=8

N=8

N=16 ?

N=20

??

Evidence for N=16 Shell

A. Ozawa et al., Phys. Rev. Lett. 84 (2000) 5493

Search for 21B

Session SD - Nuclear Structure IV: Light Nuclei.

ORAL session, Saturday morning, October 20

Illima, Outrigger Wailea Resort

[SD.007] Search for 21BY. 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 21B with a 95A MeV beam of 40Ar 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 21B may be bound. The production cross section of AB 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 21B. 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

Search for 26O

Cou

nts

Z

4 98765 1 0 11

1 0 1

1 0 3

1 0 2

C2 0

N2 3

B1 7B e1 4

O2 6F2 9

N e3 2N a3 5

D. Guillemaud-Mueller, et al. Phys. Rev. C41 (1990) 937M. Fauerbach, et al. Phys. Rev. C53 (1996) 647

26O

Search for 28O / Existence of 31F

H. Sakurai et al., Phys. Lett. 448B, 180 (1999)

2n Separation Energy Systematics

shell closure subshell deformation

Fe

Cs

50 56

Two-Neutron Separation Energies

Double Magic 78Ni

Search for 78Ni

V.A. Rubchenya and J. Äystö, Nucl. Phys. A701 (2002) 127c

Experimental Limit

0.1 μb

Calculation

1 nb

Observation of 78Ni

M. Bernas et al., Phys. Lett. B415 (1997) 111

0.3 nb

Identification of New IsotopesIo

niza

tion

Cha

mbe

r

J. Benlliure et al. Nucl. Phys. A660 (1999) 87

238UFragmentation950 MeV/u

Time of Flight

Ion

start stop

E (Ionization chamber or Si)

Total Energy

Fission of Fission Fragments??

0.0 20.0 40.0 60.0 80.0 100.0 120.0 140.0N (A-Z)

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

Z

r-processpath

rp-processpath

RI yield in ions/s

>1012

1010

108

102

1.0110-4

10-6

106

104

R e g io n o fK n o w n N u c le i