I. Physics overview - cartoon II. Experimental logic (TAMU & NSCL) & physics example III. Technology that makes it work IV. A = 8 8 C 6 Be + (2p) +2p + (2p) : 2p-2p & Isospin symmetry breaking 8 B IAS 6 Li IAS + 2p : First IAS IAS 2p decay V. A = 12 12 C Hoyle and 3 - decay : Exclusively through 8 Be g.s. 12 O : A new mass and width 12 N IAS 10 B IAS +2p : Second IASIAS 2p decay + IMME VI. Miscellaneous A new state in 9 Li : Part of IAS analog of 9 He ?? VII. Summary R. J. Charity, M. Jager, J. Manfredi, K. Mercurio, R. Shane, T. Wiser, J. Elson, L. G. Sobotka [WU] WU + NSCL + TAMU + WMU LGS: NN2012 1 out of 25 Continuum spectroscopy of light nuclei studied via high-order correlations 1 Related talk this afternoon by RJC
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I. Physics overview - cartoonII. Experimental logic (TAMU & NSCL) & physics exampleIII. Technology that makes it work IV. A = 8 8C 6Be + (2p) +2p + (2p) : 2p-2p & Isospin symmetry breaking
8BIAS6LiIAS + 2p : First IAS IAS 2p decayV. A = 12 12C Hoyle and 3- decay : Exclusively through 8Beg.s. 12O : A new mass and width 12NIAS 10BIAS +2p : Second IAS IAS 2p decay + IMMEVI. Miscellaneous A new state in 9Li : Part of IAS analog of 9He ??VII. Summary
R. J. Charity, M. Jager, J. Manfredi, K. Mercurio, R. Shane, T. Wiser, J. Elson, L. G. Sobotka [WU]
WU + NSCL + TAMU + WMULGS: NN2012
1 out of 25
Continuum spectroscopy of light nuclei studiedvia high-order correlations
1
Related talk this afternoon by RJC
I. Physics overview
1. Multiple proton decay at the drip-line Pushing nuclear structure into the continuum
2. Improve/complete isospin multiplets
3. 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 e
P CorrelationsSecrets told in mass anddecay correlations
Your place or mine ?
2
8He 8C
A = 8 2p d
ecay
New
type
2p d
ecay
New
mas
s
Momentum Achromat Recoil Separator (MARS)
Scale (meters)
0 5
15 MeV/amu
B10
H GasTargetP = 1.7 atmT = 77 K
2
Velocit
y Filter
10.7 MeV/amu > 99.5%
10C Emittance
Slits
DP SlitsFaraday Cup
Q5Q4
D3
V1
D2S1 Q3 D1 Q2
Q1T
SW2 QY QX
SW1
From enriched CarboraneC2[10B10]H12
II. Experimental logic: Example #1 TAMU using K500 cyclotron and the MARS separator
ECRsource
K-500 cyc
E* = ETKE – Qgg
(t1/2 = 19.3 s)
2*105/s
A 4-particle correlation experiment !
E* (parent) = “POP” – mass
(p,n)
Inelastic excitation
Primary reaction
Secondary reaction
Time, Energy, and Particle resolving “CAMERA” with 4k pixels
1p decay is ALLOWED by energy but FORBIDDEN by isospin.
1p and 1n isospin ALLOWED decays are energy FORBIDDEN.
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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. In first-order perturbation theory or if charge dep. forces only two-body
the masses should if fit with a quadratic IMME.
3. The need for dTz3 and eTz
4 terms isospin symmetry breaking. (This statement is not invertible!)
New since last fit - ours - previous fit used wrong mass uncertainty*.
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*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).
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 8Be*
The fit (RESIDUALS) are there 0+’s up here with small energy denominators?
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TClassic case of isospin mixing
V. The A=12 Isobar Energy Diagram
T=2
T=1
T=0
TZ = 2 TZ = 1 TZ = 0 TZ = -1 TZ = -2
12Og.s.12NIAS
12CIAS12BIAS.
12Beg.s
1. Energy unknown
2. 12Og.s.:
Width controversy
4. Unusual decay of
3- or
0+ Hoyle ?
3. Second pair of isospin clones of 2p decays:
12Og.s. And 12NIAS
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How does Hoyle state decay?
PL B 2011Claimed 7.5 +- 4.0 %Hoyle 3 equal-energy ’s
Our data – clean selection of Hoyle from 3 reconstruction
?
17
12C (3-) 8Beg.s. + The “Ghost Peak” line shape is expected from R-matrix calc.
b) Gate on Hoyle and ConstructErms = [ <E2> - <E>2 ]1/2 Compare to simulations
Equal Energy
Hoyle8Beg.s.
Equal Energy (UPPER LIMIT) = 0.45% 17 times lower than Raduta et al. value
a) Gate on 3- and generate 8Be* spectrum (choose smallest E*)
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Gat
ed d
ata R-matrix
12C (Hoyle) 8Be g.s. +
A = 12 data onusing 13O @ TAMU
12O10C +2p
12N* 10B* +2p
New mass & width 12O, < 72 keV Old 400-600 keV
Complete quintet
A = 12No evidence (from IMME) of isospin sym. breaking.However Some symmetry breaking effects not captured by IMME.
13O -n 12O 10C + 2p 13O -p 12N*10B*+2p T = 2 1 T = 2 1
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Known
Known
New
Narrower
New
Narro
wer 2nd case IASIAS 2p
12N
13N
The new class of 2p emitters IAS IAS
A = 8: NSCL 8Cgs & 8BIAS IMME & correlations
?
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A = 16: NSCL16Negs & 16FIAS A = 12: TAMU
12Ogs & 12NIAS IMME
A = 9
9He might have the (7th) last odd n in the second s state. If so the gd.st. spin is ½+
n p
Tz = +5/2 +3/2 +1/2 -1/2 -3/2 -5/2
9He9Li (IAS) - part of it
T = 1/2
T = 3/2
T = 5/2
3 6 6 3
2 7
4 55 4
VI. Misc.Little known about A = 9 sextet
21
?
2nd s ?
Known
6Li*
And 7He analog in 7LiIAS
(I = 3/2-, T=3/2)
Unknown9He analog in 9LiIAS (I = 1/2+, T = 5/2) ?Its ~600 keV lower than “expected”. from 6,7,8He - 6,7,8Li*.
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
Secondary beam of 12Be (t1/2 = 24 ms)Smash it up
Look in debris using particle-particle correlations
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Isospin 2-state mixing for 9LiIAS pair of mixed levels* like
b) bspace,spin,T = 3/2) ) space,spin, T = 3/2 + 5/2)
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T = 5/2
T = 3/2
I = 1/2+
I = 1/2+
I = 1/2+
I = 1/2+
T = 3/2 + 5/2
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 !
Observed ?
a
b
Same space, spin, ~ E mix
* Suggested by John Millener
Summary1. 8C (6Be) +2p (+2p) +2p
$ First concatenated 2p decays, new 8C mass
2. 8BIAS 6Li IAS + 2p $ First example of IAS IAS 2p decay
3. Evidence for isospin symmetry breaking in A = 8 but not A =12
4. New mass & width for 12O. $ Width (UL!) much smaller
5. 12NIAS 10B IAS + 2p $ Second IASIAS 2p decay
6. 12C* Hoyle & 3- decays BOTH 99+% through 8Beg.s.
7. Part of isospin mixed analog of 9Heg.s. (~ 9LiIAS) ?? Thank you for your attention
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+ 1(p – p)
–
+ 4(p – 0 %
35%
17%
And the rest ?
Some correlations unavoidable !
A “menage a quatre”state.
– 6Be
p– 9Be*
VII. Second curiosityAnother new state in 10C* at E*= 9.7 MeV
17 % + 35 % boring, but the other 50 % displays a highly unusual & highly (4-body) correlated decay
1(p-p) + 4(p-5Li 8Be(2
9Bgs X
25
Technology and light-nuclei continuum spectroscopy papers using HiRA (mostly) + HINP (always)
Technology: G. L. Engel, et al., NIM A 573, 418 (2007). HINPM. S. Wallace et al., NIM A 583, 302 (2007) HIRA
G. L. Engel, et al., NIM A 612, 161 (2009). PSD improvements ported to HINP G. L. Engel, et al., NIM A 652, 462 (2011). HINP + PSD
6Be: L.V. Grigorenko, et al., Phys. Rev. C 80, 034602 (2009). L.V. Grigorenko, et al., Phys. Lett. B 677, 30 (2009).
8C and 8BIAS : R. J. Charity, et al., Phys. Rev. C 82, 041304(R) (2010). + misc R. J. Charity, et al., Phys. Rev. C 84, 014320 (2011). 10C: R. J. Charity, et al., Phys. Rev. C 75, 051304(R) (2007). K. Mercurio, et al., Phys. Rev. C 78, 031602(R) (2008). R. J. Charity, et al., Phys. Rev. C 80, 024306 (2009).
T = 5/211Li,11Be,11B R.J. Charity, et al., in preparation (2012).
12C (Hoyle) J. Manfredi, et al., Phys. Rev. C 85, 037603 (2012). 12O + 12NIAS M. Jager, et al., Phys. Rev. C in press (R) (2012). 12Be: R. J. Charity, et al., Phys. Rev. C 76, 064313 (2007).
Misc (inc. 9Li”IAS”): R. J. Charity, et al., Phys. Rev. C 78, 054307 (2008).
Isospin symmetry breaking: R. J. Charity, et al., Phys. Rev. C. 84, 051308 (R) (2011).
26
How does Hoyle state decay? PL B 2011Claimed 7.5 +- 4.0 %Hoyle 3 equal-energy ’s
Their data Hoyle background from 3 reconstruction Our data~ 10 % background ~ 0.2 % background
?
27
Variables needed to describe 3-body decayDOF counting
Prototype : 6Be + 2p1. Total momentum variables = 3x3
=92. Center of mass of no interest -33. For a spin 0 (actually <=1/2) sys. Euler ang. not needed -3 4. If you know the total decay energy, you can …… -1
_______
TOTAL
2
Energy variable = fraction E in p-p rel. motion = frac. E in core – p
There are two physically instructive sets of variables. The Jacobi …… (A matter of perspective)
“T” and “Y”__systemsEx Ep-p/Etot Ep-core/Etot
fraction of Etot in: pp p core
p-p to 2p-core core-p to p
28
7Be 6Be + n 3-body decay Theory gets
1) 6Begs energy, 2) 6Begs widthand now 3) Jacobi maps
“Coulomb holes” conspicuous in both theory and exp.
Energy variable = fraction of E in p-p rel. motion
= frac. E in core – p
Theory (Grigorenko et al.) nicely reproduces data.Theory has …. p – p potential, p – potential + 3-body term.
Now analyzing decay from 2+….
IV.
29
Projections on Jacobi coordinates
Conclusions:1.Reproduced by 3-body QM model2.Potential intermediate plays no role3.NO (significant) “di-protron” enhancement
FromY intermediate not biasing decay (if sequential bimodal) Thus NOT sequential but 3-body.(Some call decays with very wide intermediates “democratic”.)
T little “diproton” enhancement.
30
Comparison to Kryger et al.
1995
Nucleus 12O (1) 12O (2) 12N (1) 12N (2)
ET [MeV] 1.638(24) 3.606(60) 1.165(29) ~3.17
E* [MeV] 0 1.968(52) 12.196(29) ~14.20
ΔM [MeV] 31.914(24) 33.872(6) 29.534(29) ~31.54
Γ [keV] <72 475(110) <110
Jπ 0+ (2+,0+) 0+
12O Kinetic Energy Spectrum
12N Kinetic Energy Spectrum
31
32
33
10C experiments at TAMUset of 4 dE (64 um) - E (1500 um) Si telescopes
~ 400 Si ch
ASICsOutside vacuum
Beam
34
1st
2nd
Clean 1-step 3-body decay
Dissected steps from -p-p-p-p
35
What can be said about the influence of the potentialIntermediates?
Examine the Jacobi projections of 8C decay.
IF 7B played a role it would drive Ex(Y) bimodal.It does not.
Red 6Be~ uniform 3-body
Fromintermediate not biasing decay
But now there is a“diproton” enhancement.
Alex Brown can explain the width of the 8Cgs with a “diproton” R-matrix model. 36
Reports Progress of Physics 8, 274 (1941)
A comment on the origin of the concept of isospin
The beginnings in
Fully developed by
After the war Feenberg WU
Also Wigner, E., 1937 a. Phys. Rev. 51, 106. Wigner, E., 1937 b. Phys. Rev. 51,947. Wigner, E., 1939. Phys. Rev. 56, 519.