Exotic dancing on the
bridge between driplines
TAMU – JBN
A few comments on JBN  LGS
First conversation  Asilomar CA 1980(?) – a DNP meeting
(LGM said ~ “go sit at his table – you can learn from him”)
The conversation has been unbroken for over three decades.
JBN expertise
Fusion, fission, HI reaction dynamics, SHE, EOS and Laser experiments
His work characterized by: BREATH, DEPTH, BOLDNESS
– he did not do what others were doing.
Equally impressive (and rare these days) is his calm and modest nature.
He has held the torch high of one of the most successful sub fields of science:
 NUCLEAR CHEMISTY
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NUCLEAR CHEMISTRY
Why do I say …Nuclear chemistry is one of THE most successful fields in all of
science ? With so few practitioners it has given birth to many subfields!
Radioactive decay and nuclear medicine  M. Curie and Irene Curie
Fission
Hahn and Strassman
Photosynthesis and biological tracers
 S. Ruben and M. Kamen
Transuranics
 Wahl, Kennedy and Seaborg, followed by many
Nucleosynthesis ideas
 C. Coryell (before B2FH !)
Isotope chemistry and chemical reaction dynamics  H. Urey and J. Bigeleisen
Neutrino Astro “physics” – looking inside the sun  Ray Davis
Large-molecule Mass spec.
 Ron Macfarlane
Positron-Emission Tomography  M. Phelps, E. Hoffman, J. Fowler….
Dinosour extinction
 F. Asaro (and Luis and Walter Alvarez)
Atmospheric chemistry
 S. Rowland
Nuclear Chemistry offers a license to be to bold.. What has Joe done with his?
HI reaction dynamics, EOS (Low Den  RHIC) & Laser experiments
Doing experiments and analyses that others did not do/could not imagine
Lets talk about a few things JBN left for us peons to do…
 JBN
2
Exotic Dancing on the Bridge between driplines.
1. Overview of physics and experimental logic
2. The structure of 11Li from its analogs
3.
A=8
8C  6Be + (2p) a +2p + (2p) : 2p-2p & Isospin symmetry breaking
8B
6
: First IAS  IAS 2p decay
IAS LiIAS + 2p
4. A = 12
12C Hoyle and 3- a decay
12O
12N
10B
IAS 
IAS +2p
12N (2-) new width
: Exclusively through 8Beg.s.
: A new mass and width
: Second IAS IAS 2p decay + IMME
: reduced “RAP” rate
5. Many new states, for example…
 9Li (E* = 14.1 MeV), 10B(E*= 20.4 MeV)  Parts of analog structures ?
 13O(E* ~< 3 MeV) 3 states now known with E* < first in mirror 13B
3
I. Physics overview
1.
2.
3.
Multiple proton decay at the drip-line Continuum nuclear structure
Improve/complete isospin multiplets
Hopefully peering in at nucleon-nucleon correlations (in the medium)
by “pushing” Fermi surface to (or into) the continuum.
A=8
8He
N Correlations
??
Secrets told in
mass and re
8C
Your
place or
mine ?
? ? ? ?
P Correlations
Secrets told in mass and
decay correlations
4
From enriched
Carborane
C2[10B10]H12
I. Experimental
logic
Momentum
Achromat
Recoil Separator
 TAMU using K500 cyclotron and the MARS separator
(MARS)
r
it
Secondary
loc
e
V
reaction
ilte
F
y
S1
D2
V1
Q5
10
C
Q3
D1 Q2
DP Slits
Faraday Cup
D3
Inelastic
excitation
10.7 MeV/amu
> 99.5%
2*105/s
Emittance
Slits
0
Q1
T
SW
2
SW1
QY Q
X
H2 Gas
Target
P = 1.7 atm
T = 77 K
Q4
(t1/2 = 19.3 s)
ECR
source
Primary reaction
(p,n)
K-500
cyc
10
B
15 MeV/amu
5
Scale (meters)
E* (parent) = “POP” – D mass
A 4-particle correlation experiment !
 Time, Energy, and Particle resolving “CAMERA” with 4k pixels 
E* = ETKE – Qgg
5
Determined the decay
paths for known and two
new levels in 10C using….
2,3 - particle
intermediates
4-particle (aapp)
4-particle and sub event
(2- and 3-particle)
energy correlations.
9.7
Also disproved a level claimed
by others at 4.2 MeV.
The other group later
retracted their claim.
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Isospin primer
1. If isospin is a good quantum number, in the absence of Coulomb forces
 the energies of a multiplet should be independent of Tz.
2. If charge dep. forces only two-body
 the masses should if fit with a quadratic IMME.
3. This equation allows for M
and
M
as n  p (as Mn>Mp)
as n p (due to Coulomb repulsion)
If you need more terms, isospin symmetry is violated.
4. Specifically, the need for dTz3 and eTz4 terms  isospin symmetry breaking.
(This statement is not invertible!)
5. IF you know 3 masses of a 2T+1 multiplet, the (quadratic) IMME provides a
prediction of the masses of ALL members of the multiplet.
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2. Consider the Multiplet that includes 11Li:
A = 11 Sextet T=5/2, J=3/211B
Unfinished Bridge
→ 2p+9Li (decay branch)
DIAS in 11B
E*=33.6 MeV
G=306(182) keV
Isospin-allowed 2p decay possible
IAS known (RIKEN 1997) p+n decay
Known particle-stable
T=5/2, J=3/2-,
sextet
two-nucleon halo
11O
11N
12Be(p,2n)11B
at E/A = 50 MeV
@NSCL with HiRA array.
11Li
T=3/2, J=1/2+,quartet
one-nucleon halo
11Be
T=1/2, J=3/2-, doublet (used as reference)
11C
11B
8
Masses show the effect of the extended halo.
Consistent with 11Li halo wavefunctions calculated by Hagino + Sagawa
Can extrapolate to masses of proton-rich members of the sextet.
p
PRC 72 (2005) 044321
n
Calc.
Exp.
DVC(11B-11Be) = 1.375 1.389(20) MeV
DVC(11Be-11Li) = 1.797 1.69(8)
R.J. Charity, et al., Phys. Rev. C 86 041307(R) (2012).
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3. 8C decay
Peak / bkg
1 / 5
a-p-p
from
a-p-p-p-p
T=2
T=1
a-p-p
from
7Be beam
a-p-p-p-p
from
9C beam
Excitation energy (MeV)
T=0
6Be is the (7 zs) intermediate, i.e.
8B  [6Be] + 2p + [a +2p] +2p
We studied the 3-body correlation for
6Be decay AND the 3-body
correlations for 8C decay.
In ~ 1/3 of the events only ONE of the
six combinations lies in the 6Be peak.
For these events we can assign
protons to first and second steps.
 enhancement at small rel. mom.
10
TOP 9C  8Cgdst (0+, T=2) +n
BOT 9C  8BIAS (0+, T=2) +p
8B
reconstruction from 6Li+p+p
g
6Li
IAS
 Ligs + gamma
1p or n decays are forbidden by either
energy or isospin
R. J. Charity, et al., Phys. Rev. C 82, 041304(R) (2010).
K. Brown, et al., Phys. Rev. C in preparation (2013).
1
Confirmation of Isospin symmetry breaking in A = 8
The fit (RESIDUALS)
Needs d(Tz)3 term (as do A = 9 & 32)
Does not need an e4 term.
? Reason ?
Classic case of
isospin mixing
T
Perhaps isospin mixing in T = 2 like
T = 0 + 1 in 12C 
R. J. Charity, et al., Phys. Rev. C. 84, 051308 (R) (2011).
12
We have actually
found two cases of
this new class of 2p
emitters: IAS  IAS
A = 8: NSCL
8C
8
gs & BIAS  IMME
?
A = 12: TAMU
12O
12N
gs &
IAS  IMME
A = 16: NSCL
16Ne
16F
gs but NOT
IAS
13
14
5. The A=12 Isobar Energy Diagram
12Be
g.s
12B
IAS.
12C
IAS
TZ = 2
TZ = 1
TZ = 0
12N
IAS
TZ = -1
12O
g.s.
TZ = -2
b) Energy
unknown
c) Width
controversy
T=2
a) Decays of
d) Second pair of isospin
clones of 2p decays:
 3- or
12O
…..
 0+ Hoyle
T=1
Both studied in
high statistics
and excellent E
resolution.
T=0
g.s.
And
12N
IAS
i) Gate on Hoyle and
Construct a rms energy
Erms = [ <E2> - <E>2 ]1/2
Compare to simulations
How do Hoyle and 3- states a decay?
Equal Energy
ii) Gate on 3- and
generate 8Be* spectrum
(choose smallest E*)
Hoyle8Beg.s.
Equal Energy (UPPER LIMIT) = 0.45%
17 times lower than Raduta et al. value
12C
(3-) 8Beg.s. + a ~100.%
The “Ghost Peak” line shape is expected from R-matrix calc.
12C
(Hoyle)  8Be g.s. + a > 99.5 %
J. Manfredi, et al., Phys. Rev. C 85, 037603 (2012).
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A = 12 data on
using 13O @ TAMU
12N
13N
13O
 -n  12O 10C + 2p
T=2 1
13O
 -p 12N*10B*+2p
T=2  1
Known +
2nd case IASIAS 2p
Known
12O10C
+ 2p
12N*
New mass & width 12O, G < 72 keV Old 400-600 keV
&
Complete quintet
10B* + 2p
Quadratic IMME  perfect
No evidence of isospin sym. breaking @ A = 12
M. Jager, et al., Phys. Rev. C 86, 011304 (R) (2012).
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Returning to the same A = 12 2p experiment, we found….
New 12N 2- width
new states in 13O
Results:
a) New width of 2- in12N (~ ½ NNDC value ) leads to reduced 11C(p,g) rate, 26% at T9 = 0.2;
Greater reduction at higher T, less reduction at lower T. 
b) Now 3 excited states in 13O below first excited state in mirror 13B.
 Thomas-Ehrman physics.
L. G. Sobotka, et al., Phys. Rev. C 87, 054329 (2013).
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Summary
Wealth of new information on light nuclei
Complete 3-body decay PS for 6Be.
Found Analog of 11Li in 11B.
IAS IAS 2p decays.
Hoyle and 3- decay in12C
Found isospin symmetry breaking in A = 8 but not in A = 12.
Many new levels and properties, e.g. 12N and 13O, the former with NA significance.
Future plans
Compare the Phase-Space population of PAIRS of 2p emitters, (same T, different Tz).
[NSCL]
We think we can get the mass of TWO more members of the T = 5/2, A = 11 sextet
[NSCL]
16O  13O  -2n, -np  11O and 11N
11
 5 members of A = 11 sextet containing Ligs.
gs
IAS
 Answer several decades old question on “particle-assisted Hoyle-state decay”
Ask me PLEASE ASK ME
[OHIO]
 What is the structure of some of the new states we found
e.g. 9Li (14.1 MeV)  part of analog structure of 9Hegs??
e.g. 10B (20.4 MeV)  part of analog structure ??
[TAMU]
P Elastic scattering from 14O [14N(p,n)] and 20O [22Ne(-,2p)]
Really important for the DOM
[TAMU]
stot(n) on stable but rare isotopes
[LANSCE]
Photorespiration and drought
[WU]
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END
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A. The “Hoyle” picture:
a sequence of improbable events
9996/10000
Width (ev)
Lifetime (s)
5.5
120 x 10-18
4/10000
8.5
77 x 10-18
Decay of Hoyle state
formation of Hoyle state
(tail of exponential Maxwell-Boltzmann distribution)
B. The Old unresolved issue
The decay of an ISOLATED 12C* is well studied and as represented. BUT
in hot and dense stars there is another process that can deexcite 12C* ineastic UPSCATTERING.
12C*
+ n or p or a (low energy)  12C + n or p or a (high energy)
12C
12C
This can lead to either
gs or
4.44
Either way C has been made.
All mechanics is time reversal invariant.
So all you need to know are the cross sections for
12C
12C
gs + n 
7.65 + n’ and
12C
12C
4.44 + n 
7.65 + n’.
The latter cannot be measured and the former is
Hard. WHY
The Hoyle state structure is VERY different than that
of the ground state and so the WF overlaps are small  small s
(n,n’)
Previous (n,n’) measurements
Elastic cross section large
Cross section to 2+ large, 3- medium
Cross section to Hoyle small
What is the point of measuring n’?
1. ONLY to confirm that the HOYLE was formed.
2. But IF the HOYLE is formed 9996 times/10,000 it
decays 12C*  8Be + a  (a + a) + a
a
12C*
That is
a
a
3. Forget looking for n’  just look for 8Be-a “Y” track.
Why has it not been done before?
Because the range in condensed matter is microns.
The total decay energy is only 287 keV.
 AT-TPC to the rescue
BUT now AT-TPC’s exist
Idea:
shoot n’s just above threshold into AT-TPC running with isobutane (C4H10(g))
and look for 8Be-alpha signature.
s(n,p) is well known, will lead to single-ended tracks and thus is an internal calibration
Running just above the 3- leads to another check that s (n,n’) can be extracted.
Genesis of this idea
Sam Austin corned me at MSU saying …..
“Lee your clever & you have done n experiments… can figure out a
way to measure this…..”
After some thought, I said
“Sam, this is how to do it ….and they guy 2 doors down from you has
the device to do it” all we need to do is take it to a n – lab.
They guy two doors down, Wolfi Mittig, said – “lets do it.”
Now WE need to do it.
References
Secondary beam of 12Be (t1/2 = 24 ms)
Smash it up
Look in debris using particle-particle correlations
Known
6Li*
And
7He
analog in 7LiIAS
(I = 3/2-, T=3/2)
Unknown
9He analog in 9Li
+
IAS (I = 1/2 , T = 5/2) ?
Its ~600 keV lower than “expected”.
Could be of mixed isospin: T = 5/2 + 3/2
With almost pure 8He x p (1s1/2 character)
with s- Coulomb shift.
 John Millener
26
Isospin 2-state mixing for 9LiIAS  pair of mixed levels*
like
8Be
IAS  pair of T = 0+1 levels?
Shell-model states
a) Fa(space,spin,T = 5/2, IAS)
b) Fb(space,spin,T = 3/2)
Physical States
a) Fa(space,spin, T= 3/2 + 5/2)
b) Fb(space,spin, T = 3/2 + 5/2)
Same space, spin, ~ E  mix
Ip = 1/2+
Ip = 1/2+
a
b
T = 5/2
T = 3/2
* Suggested by John Millener
Ip
=
1/2+
Ip = 1/2+
a
b
T = 3/2 + 5/2
Observed ?
T = 3/2 + 5/2
IF the lower state were almost pure
| 8Heg.s. x 1s1/2(p) >
It would explain the LOW Coulomb energy !
27
New 8C mass and uncertainty
+ since last fit
new 8He mass and correct error in previous fit.
1. If isospin is a good quantum number, in the absence of Coulomb forces
 the energies of a multiplet should be independent of Tz.
2. If charge dep. forces only two-body
 the masses should if fit with a quadratic IMME.
3. The need for dTz3 and eTz4 terms  isospin symmetry breaking. (This statement is not invertible!)
New since last fit - ours - previous fit used wrong mass uncertainty*.
*NOTE:
Previous work suggested isospin symmetry breaking in A = 8, but they used an uncertainty of the 8LiIAS
energy 10x too small. Confirmed with authors.
J. Britz, A. Pape, and M.S. Antony, Atomic Data and nuclear Data Tables 69, 125 (1998).
28
2. Prototype 3-body decay: 6Be  a + 2p
ONLY case with statistics to fill full Jacobi map.
We now have maps for both gs and 2+ decay
The correlation data for both gs and 2+ agree with 3-body QM
treatment with proper asymptotic (3-body Coul.) forms.
I. A. Egorova, et al., Phys. Rev. Lett. 109, 202502 (2012).
29
B. Dispersive Optical Model - DOM
g9/2
g9/2
J. M. Mueller, et al., Phys. Rev. C 83, 064505 (2011), a 31 pg paper !
30
D. Technology
1. ASIC for Si strip detectors
G. Engel, et al., NIMS A652, 462 (2011).
R. Shane, et al., NIMS A614, 468 (2010).
2. ASIC for PSD capable scintillators
3. DSP method for stot(n)
Dense stops in
one macro pulse
One stop,
fit of DSP data
Liquid scint
n-g separation
2.5 % rms deviation from literature
Used at: NSCL, TAMU, ORNL,
LSU/FSU, RIKEN, ND,
1000’s of channels in a suitcase
Used at: Wash. U. & LANL
1000’s of channels in a suitcase
Used at: LANSCE
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C. Misc topics
GEMINI
Hasy vs Easy
M1 (48Ca)
It is not always clear if
experimental work extracts
the asymmetry Energy
or Enthalpy
Light nuclei do not need a(E*)
Heavy nuclei do need a(E*)
The latter needed to understand
survival against fission.
An angular momentum dependence
of the yrast energy slightly weaker
than predicted by Sierk are needed.
Another paper describes coupling
of GEMINI to INC.
 RJC  2 PRC papers
Below phase transition
It does not matter
Above phase transition
they diverge.
Divergence will be model
dependent.
 LGS  1 PRC paper
IMP
 11.98 m2
CM (0hw)  8.96
(e,e’)
 5.3
ERPA
 ~ 6.1
 LGS  1 PRC paper
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