Exotic dancing on the bridge between driplines tamu jbn
This presentation is the property of its rightful owner.
Sponsored Links
1 / 32

Exotic dancing on the bridge between driplines TAMU – JBN PowerPoint PPT Presentation

  • Uploaded on
  • Presentation posted in: General

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

Download Presentation

Exotic dancing on the bridge between driplines TAMU – JBN

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript

Exotic dancing on the bridge between driplinesTAMU – 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:



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…

Exotic Dancing on the Bridge between driplines.

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 8BIAS6LiIAS + 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

I. Physics overview

2p decay

New mass

2p decay

New type

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.

N Correlations


Secrets told in

mass and re





P Correlations

Secrets told in mass and

decay correlations

From enriched



I. Experimental logic TAMU using K500 cyclotron and the MARS separator



Primary reaction








(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 

2,3 - particle 4-particle (aapp)


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.

Isospin primer

  • Ifisospin is a good quantum number, in the absence of Coulomb forces

  •  the energies of a multiplet should be independent of Tz.

  • If charge dep. forces only two-body

  •  the masses should if fit with a quadratic IMME.

  • 3. This equation allows for M as n  p (as Mn>Mp)

  • and M 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.

2. Consider the Multiplet that includes 11Li:

A = 11 Sextet T=5/2, J=3/2-

11B → 2p+9Li (decay branch)

Unfinished Bridge

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



T=3/2, J=1/2+,quartet

one-nucleon halo



T=1/2, J=3/2-, doublet (used as reference)

12Be(p,2n)11B at E/A = 50 MeV

@NSCL with HiRA array.



Masses show the effect of the extended halo.

Consistent with 11Li halo wavefunctions calculated by Hagino + Sagawa PRC 72 (2005) 044321

Can extrapolate to masses of proton-rich members of the sextet.



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).

3. 8C decay

Peak / bkg

1 / 5

T = 2




T = 1



7Be beam

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.



9C beam

Excitation energy (MeV)

8B reconstruction from 6Li+p+p

TOP 9C  8Cgdst (0+, T=2) +nBOT9C  8BIAS (0+, T=2) +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).

Confirmation of Isospin symmetry breaking in A = 8


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).

We have actually found two cases of this new class of 2p emitters: IAS  IAS

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




5. The A=12 Isobar Energy Diagram

b) Energy


c)Width controversy

d) Second pair of isospin clones of 2p decays:

12Og.s. And 12NIAS

  • a) Decays of

  • 3- or

  • …..

  • 0+ Hoyle

  • Both studied in

  • high statistics and excellent E resolution.

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*)



Gated data

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  1

A = 12 data onusing 13O @ TAMU

Known +


New mass & width 12O, G < 72 keV Old 400-600 keV


Complete quintet


2nd case IASIAS 2p




12O10C + 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).

Returning to the same A = 12 2p experiment, we found….

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.

 Thomas-Ehrman physics.

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.

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  11Ogs and 11NIAS  5 members of A = 11 sextet containing 11Ligs.

  •  Answer several decades old question on “particle-assisted Hoyle-state decay” [OHIO]

  • Ask me PLEASE ASK ME

  • What is the structure of some of the new states we found[TAMU]

  • e.g. 9Li (14.1 MeV)  part of analog structure of 9Hegs??

  • e.g. 10B (20.4 MeV)  part of analog structure ??

  • P Elastic scattering from 14O [14N(p,n)] and 20O [22Ne(-,2p)] [TAMU]

    • Really important for the DOM

    • stot(n) on stable but rare isotopes [LANSCE]

    • Photorespiration and drought[WU]


A. The “Hoyle” picture:a sequence of improbable events



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)

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)

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

Hard. WHY

The Hoyle state structure is VERY different than that

of the ground state and so the WF overlaps are small  small s


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’?

  • ONLY to confirm that the HOYLE was formed.

  • But IF the HOYLE is formed 9996 times/10,000 it decays 12C*  8Be + a  (a + a) + a

    That is

    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


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.


Secondary beam of 12Be (t1/2 = 24 ms)Smash it upLook in debris using particle-particle correlations




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.

 John Millener

Isospin 2-state mixing for 9LiIAS pair of mixed levels* like8BeIAS pair of T = 0+1 levels?

Shell-model statesPhysical 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+

Observed ?

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 8C mass and uncertainty+ since last fit new 8He mass and correct error in previous fit.

  • Ifisospin is a good quantum number, in the absence of Coulomb forces

  •  the energies of a multiplet should be independent of Tz.

  • 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*.


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).

2. Prototype 3-body decay: 6Be  a + 2pONLY 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).

B. Dispersive Optical Model - DOM



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

One stop,

fit of DSP data

Liquid scint

n-g separation

2.5 % rms deviation from literature

Used at: NSCL, TAMU, ORNL,


1000’s of channels in a suitcase

Used at: Wash. U. & LANL

1000’s of channels in a suitcase

Used at: LANSCE

C. Misc topicsGEMINI 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


 RJC  2 PRC papers

Below phase transition

It does not matter

Above phase transition

they diverge.

Divergence will be model


 LGS  1 PRC paper

IMP  11.98 m2

CM (0hw)  8.96

(e,e’)  5.3

ERPA  ~ 6.1

 LGS  1 PRC paper

  • Login