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


p + p  2+ or 1+
1/2
3/2
s + p  2- or 11/2
3/2
Indirect Measurements
16C(12C, 12N)10Li,
200
ELab = 357 MeV
160
120
80
10
5
0
ER(10Li) (MeV)
H. G. Bohlen et al., Nucl. Phys. A616 (1997) 254c
ds/dTd (barn/MeV)
Invariant-Mass Spectroscopy
3
Pb Target
2
1
0
0.3
C Target
0.2
0.1
0.0
0
1
2
3
Decay Energy (MeV)
M. Zinser et al., Nucl. Phys. A619 (1997) 151
Relative Velocity Measurements
Experimental Setup
18
18
Quadrupole
Doublet
O
9
Be
Target
Dipole
9
Li
O
Fragment
Detector
Neutron
Detectors
1 meter
A = (N/Z=2) +1 Nuclei
9
10
C
C
11
8
10
B
B
7
9
Be
7
Li
He
p
2
H
n
4
3
H
Li
6
He
4
H
12
C
11
B
10
13
C
12
B
11
14
C
13
B
12
Be Be Be Be
6
3
C
8
Li
9
Li
8
7
He He He
10
Li
11
Li
15
C
14
13
B
16
C
15
14
B
Be Be
17
C
16
B
18
C
17
B
19
C
20
C
19
B
22
C
Calibration Reaction
7He
 6He + n
ER = 440±30 keV
Г = 160 ±30 keV
R.A. Kryger et al., Phys. Rev. C47 (1993) R2439
Decay Probability
Counts
s-wave Strength in 10Li
p1/2 67%
s 1/2 33%
MT et al., Phys. Rev. C59 (1999) 111
Virtual States
1000
9Be(12Be,9Li+n)X
Es,p,d(initial)= -3.17,-3.85,-4.95 MeV
l=0 as= -5,-10,-20,-50 f m
l=1 E1= 0.1, 0.5, 1 MeV
l=2 E2=2.0 MeV
W(k) [f m3]
100
E  ħ2/2ma2
NoI
10
1
NoI
0.1
0
0.1
0.2
0.3
Momentum k [f m-1]
0.4
0.5
Scattering Length Calculations
Energy
50
Relative velocity
-100
Yield (arb. units)
Yield (arb. units)
-100
-50
1.0
-30
-20
-10
-5
-2
0.1
40
-50
30
-30
20
-20
-1
0
10
-10
-5
0.0
0.2
0.4
0.6
E Decay (MeV)
0.8
1.0
0
-1.5
0
-1.0
-0.5
0.0
0.5
v n -v f (cm/ns)
1.0
1.5
9He
L. Chen et al., Phys. Lett. B505 (2001)
The N=7 Isotones
14
15
O
2
N
13
C
12
B
10
9
Li
11
Be
He
0
15
O
E*- Sn [MeV]
-2
r [fm]
10
-4
0
11
Be
-6
r [fm]
1/2+
0
-8
10
20
-10
10
Li
-12
0.5 MeV
1/2r [fm]
-14
0
8
7
10
6
5
4
Atomic Number Z
20
30
3
40
2
Vanishing of the N = 8 Shell
N=8
9Be
– 13C – 17O
11Be
8Li
– 15C
– 12B – 16N
A. Ozawa et al., Phys. Rev. Lett. 84 (2000) 5493
Extension to Unbound Nuclei
9He
and 13Be
10Li
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
Rrms (fm)
RMS-Radii of Lithium Isotopes
Borromean Nucleus: 11Li
Neutron
Neutron
9Li
Heiko Scheit
Unbound Subsystems
n
n
9Li
 10Li
9Li
 10Li
n
n
 Di-neutron
Origin of the Borromean Rings
VISITA VIRTUALE DEL COLLEGIO
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 (15271596); la fama della costruzione di questo "palazzo per la
Sapienza" inizia con il Vasari nella seconda edizione delle
Vite del 1568.
http://borromeo.unipv.it/visita.htm
Translation:
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.
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
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
Prof. Nadrian C. Seeman,
Department of Chemistry
New York University
http://seemanlab4.chem.nyu.edu/borro.html
Knot Theory
Symbol for
Collaborations
EMSL Collaboratory
William R. Wiley Environmental Molecular Sciences Laboratory
Pacific Northwest National Laboratory (PNNL), Richland, Washington
http://www.emsl.pnl.gov:2080/docs/collab/
DNA
More Borromean Rings
Telemanufacturing
Mike Bailey,
San Diego Supercomputer Center
http://www.sdsc.edu/GatherScatter/GSspring95/gsspring_a17.html
Art
Geometry
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
Other Usage of the Rings
Pre-College
Science Education
Undergraduate
Science Education
Graduate Education
and Research
Recognizing the Importance of Undergraduate Science Education,
Robert C. Hilborn, APS News February 1997
Brunnian Links
Robert Scharein
Department of Computer Science
University of British Columbia
http://www.cs.ubc.ca/nest/imager/contributions/scharein/brunnian/brunnian.html
http://www.cs.ubc.ca/nest/imager/contributions/scharein/brunnian/brun6-rem3.mpg
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
500
s-wave, as = -20fm
Counts
400
300
d-wave,
EDecay = 2MeV
200
100
0
-3.0
Background
-2.0
-1.0
0.0
1.0
vn - vf (cm/ns)
2.0
3.0
Could 16Be be bound?
16Be:
Constant Z (=4) Extrapolation
1n 2n Separation Energies
(MeV)
2n Separation Energy
1n Separation Energy
18
16
14
12
10
8
6
4
2
0
-2
16Be
6
8
10
12
A
14
16
??
16Be
: Constant N (=12) Extrapolation
1n 2n Separation Energies
(MeV)
2n Separation Energy
1n Separation Energy
40
35
30
25
20
15
10
5
0
-5
3
4
5
6
No 16Be
7
8
Z
9 10 11 12 13
16Be:
Constant A (=16) Extrapolation
1n Separation Energy
1n 2n Separation Energies
(MeV)
2n Separation Energy
30
25
20
15
10
5
0
-5
3
4
5
16Be
6
7
Z
8
9
10
Shell Model Calculation
B.A. Brown, private communications
16Be
??
19B
and 22C are bound
Previous Measurements
16Be
H. Sakurai et al., Phys. Lett. 448B, 180 (1999)
??
A.C. Muller and R. Anne, NIM B56, 557 (1991)
Coupled Cyclotron Facility at the NSCL
40Ar7+
4.9A
40Ar18+
40Ar7+
140 MeV/A
470nA
280nA
1.0A
12.3 MeV/A
6.0 Tm
No Evidence for 16Be
16Be
is not bound
Neutron Radioactivity
First Observation of b-delayed Two-Neutron Radioactivity
T1/2=8.7ms
b-
11Li
2n
n
9Be+2n
10Be+n
11Be
L.C. Carraze et al., Phys. Rev. Lett. 43 (1979) 1652
Search for Neutron Radioactivity
16B
Last neutron
1 p3/
2
1 s1/2
2s1/ 1d 5/ 2
2 1p
1/2
1p3/2
1s1/2


16B
Potential
60
40
Centrifugal (l=2)
20
0
Total
15
10
Radius (fm)
5
-20
-40
-60
20
Nuclear
E = 10 keV  T1/2 = 3.7·10-16s
E = 1 keV  T1/2 = 1.1·10-13s
16B
13 14 15
16
Lifetime Measurements
M. Langevin et al.,
Phys. Lett. 150B (1985) 71
17
J. D. Bowman et al.,
Phys. Rev. C9 (1974) 836
H. G. Bohlen et al.,
Nucl. Phys. A583 (1995) 775
Lifetime of 16B
10-7
10-8
10-9
10-11
10-10
10-13
10-12
10-15
10-14
10-17
10-16
10-19
10-18
10-21
10-20
Possible range for the 16B lifetime
Direct Lifetime
Measurements:
Time of Flight
Indirect Measurement:
width of state G < 200 keV
with: Gt = ħ  t2·10-21s
Stopping of Fragments
Secondary Target:
114 mg/cm2 12C
Si-E
Si-E
Beams of
16C
17C, 16C
+ 12C  15B
5cm
17C
+ 12C  16B
Production of 16B
+ Target  15B + p
17C
40
13
15
B
Counts
Counts
16C
B
30
120
90
10
30
20
40
60
Mass (arb. units)
80
B
B
60
0
15
13
20
0
+ Target  16B + p
00
16
20
40
B
60
Mass (arb. units)
80
Energy Spectra
+ Target  15B + p
15
17C
Counts
Counts
16C
15
10
10
5
5
600
650
700
750
Energy (MeV)
+ Target  16B + p
600
650
700
750
Energy (MeV)
800
New Limits for 16B
10-7
10-9
10-8
10-11
10-10
10-13
10-12
10-15
10-14
10-17
10-16
10-19
10-18
10-21
10-20
Possible range for the 16B lifetime
New results
 Reduction of almost 2 orders of magnitude
New Shell Structure?
Z=8
??
N=20
N=16 ?
N=8
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 21B
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 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
26O
14
Be
17
B
20
Counts
10 3
C
10 2
23
N
29
10 1
D. Guillemaud-Mueller, et al. Phys. Rev. C41 (1990) 937
M. Fauerbach, et al. Phys. Rev. C53 (1996) 647
F 32
Ne 35Na
26
O
4
5
6
7
8
9
10
11
Z
Search for 28O / Existence of 31F
H. Sakurai et al., Phys. Lett. 448B, 180 (1999)
2n Separation Energy Systematics
Cs
Fe
shell closure
50
subshell
56
deformation
Two-Neutron Separation Energies
Double Magic 78Ni
Search for 78Ni
Experimental Limit
0.1 μb
Calculation
1 nb
V.A. Rubchenya and J. Äystö, Nucl. Phys. A701 (2002) 127c
Observation of 78Ni
0.3 nb
M. Bernas et al., Phys. Lett. B415 (1997) 111
Identification of New Isotopes
E (Ionization chamber or Si)
Ion
stop
start
Total Energy
Ionization Chamber
238U
Fragmentation
950 MeV/u
Time of Flight
J. Benlliure et al.
Nucl. Phys. A660 (1999) 87
Fission of Fission Fragments??
80.0
70.0
60.0
Region of
Known Nuclei
r-process
path
Z
50.0
40.0
rp-process
path
30.0
RI yield
in ions/s
20.0
10.0
0.0
0.0
20.0
40.0
60.0
80.0
N (A-Z)
100.0
>1012
1010
108
106
104
102
1
.01
10-4
10-6
120.0
140.0