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
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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 JBN
Lets talk about a few things JBN left for us peons to do…
1. Overview of physics and experimental logic2. The structure of 11Li from its analogs3. A = 88C 6Be + (2p) a +2p + (2p) : 2p-2p & Isospin symmetry breaking 8BIAS6LiIAS + 2p : First IAS IAS 2p decay4. A = 1212C Hoyle and 3- a decay : Exclusively through 8Beg.s.12O : A new mass and width12NIAS 10BIAS +2p : Second IAS IAS 2p decay + IMME12N (2-) new width : reduced “RAP” rate5. 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
A = 8
Your place or mine ?
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.
Secrets told in
mass and re
Secrets told in mass and
C2[10B10]H12I. Experimental logic TAMU using K500 cyclotron and the MARS separator
(t1/2 = 19.3 s)
E* (parent) = “POP” – D mass
A 4-particle correlation experiment !
E* = ETKE – Qgg
Time, Energy, and Particle resolving “CAMERA” with 4k pixels
Determined the decay paths for known and two new levels in 10C using….4-particle and sub event (2- and 3-particle) energy correlations.
Also disproved a level claimed
by others at 4.2 MeV.
The other group later
retracted their claim.
2. Consider the Multiplet that includes 11Li:
A = 11 Sextet T=5/2, J=3/2-
11B → 2p+9Li (decay branch)
DIAS in 11B
Isospin-allowed 2p decay possible
IAS known (RIKEN 1997) p+n decay
T=5/2, J=3/2-, sextet
T=1/2, J=3/2-, doublet (used as reference)
12Be(p,2n)11B at E/A = 50 MeV
@NSCL with HiRA array.
Consistent with 11Li halo wavefunctions calculated by Hagino + Sagawa PRC 72 (2005) 044321
Can extrapolate to masses of proton-rich members of the sextet.
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).
3. 8C decay
Peak / bkg
1 / 5
T = 2
T = 1
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.
Excitation energy (MeV)
8B reconstruction from 6Li+p+p
6LiIAS 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).
The fit (RESIDUALS)
Needs d(Tz)3 term (as do A = 9 & 32)
Does not need an e4 term.
? Reason ?
Perhaps isospin mixing in T = 2 like
T = 0 + 1 in 12C
Classic case of isospin mixing
R. J. Charity, et al., Phys. Rev. C. 84, 051308 (R) (2011).
A = 8: NSCL
8Cgs & 8BIAS IMME
A = 16: NSCL
16Negs but NOT 16FIAS
A = 12: TAMU
12Ogs & 12NIAS IMME
TZ = 2
TZ = 1
TZ = 0
TZ = -1
TZ = -2
T=05. The A=12 Isobar Energy Diagram
d) Second pair of isospin clones of 2p decays:
12Og.s. And 12NIAS
Construct a rms energy
Erms = [ <E2> - <E>2 ]1/2
Compare to simulations
How do Hoyle and 3- states a decay?
ii) Gate on 3- and
generate 8Be* spectrum
(choose smallest E*)
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).
13O -n 12O 10C + 2p 13O -p 12N*10B*+2p
T = 2 1 T = 2 1A = 12 data onusing 13O @ TAMU
New mass & width 12O, G < 72 keV Old 400-600 keV
2nd case IASIAS 2p
12O10C + 2p
12N* 10B* + 2p
Quadratic IMME perfect
No evidence of isospin sym. breaking @ A = 12
M. Jager, et al., Phys. Rev. C 86, 011304 (R) (2012).
New 12N 2- width new states in 13O
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.
L. G. Sobotka, et al.,Phys. Rev. C 87, 054329 (2013).
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.
Width (ev) 5.5 8.5
Lifetime (s) 120 x 10-18 77 x 10-18
Decay of Hoyle state
formation of Hoyle state
(tail of exponential Maxwell-Boltzmann distribution)
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)
This can lead to either 12Cgs or 12C4.44
Either way C has been made.
All mechanics is time reversal invariant.
So all you need to know are the cross sections for
12Cgs + n 12C7.65 + n’ and
12C4.44 + n 12C7.65 + n’.
The latter cannot be measured and the former is
The Hoyle state structure is VERY different than that
of the ground state and so the WF overlaps are small small s
Elastic cross section large
Cross section to 2+ large, 3- medium
Cross section to Hoyle small
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
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.
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.
7He analog in 7LiIAS
(I = 3/2-, T=3/2)
9He analog in 9LiIAS (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.
Shell-model states Physical States
a) Fa(space,spin,T = 5/2, IAS) a) Fa(space,spin, T= 3/2 + 5/2)
b) Fb(space,spin,T = 3/2) b) Fb(space,spin, T = 3/2 + 5/2)
Same space, spin, ~ E mix
T = 3/2 + 5/2
T = 3/2 + 5/2
T = 5/2
T = 3/2
Ip = 1/2+
Ip = 1/2+
Ip = 1/2+
Ip = 1/2+
IF the lower state were almost pure
| 8Heg.s. x 1s1/2(p) >
It would explain the LOW Coulomb energy !
* Suggested by John Millener
New since last fit - ours - previous fit used wrong mass uncertainty*.
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).
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).
J. M. Mueller, et al., Phys. Rev. C 83, 064505(2011), a 31 pg paper !
G. Engel, et al., NIMS A652, 462(2011).
R. Shane, et al., NIMS A614, 468 (2010).D. Technology
1. ASIC for Si strip detectors 2. ASIC for PSD capable scintillators 3. DSP method for stot(n)
Dense stops in
one macro pulse
fit of DSP data
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
It is not always clear if
experimental work extracts
the asymmetry Energy
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
Divergence will be model
LGS 1 PRC paper
IMP 11.98 m2
CM (0hw) 8.96
ERPA ~ 6.1
LGS 1 PRC paper