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Artemis Spyrou, May 2, 2014, Slide 1
Artemis Spyrou
Three-body forces in two-neutron decay experiments: 26O
Workshop “Three-body forces: from matter to nuclei”, ECT*, Trento 2014
Artemis Spyrou, May 2, 2014, Slide 2
Overview
! Motivation ! Neutron-rich oxygen isotopes
! Experimental ! MoNA/Sweeper setup ! 2n decay of 26O
! 26O decay energy ! 26O half-life
! 3NF status and needs
Artemis Spyrou, May 2, 2014, Slide 3
Neutron Dripline
Stable
Transfer/Missing Mass
ȕ�'HOD\HG
5,�%HDPV�,QYDULDQW�0DVV
10Li
18B
10He
12Li
7H
9He
4H
28F 30F
25O
24N
21C
7He
13Be 16Be
16B
13Li
5H 6H
25N
26O 27O 28O
11Be 10Be 9Be 14Be 12Be
11B 10B 13B 14B 12B 15B 17B 21B 19B
13C 12C 15C 16C 18C 14C 17C 19C 20C 22C 10C 11C 9C
7Be
8B
7Li 6Li 8Li 11Li 9Li
4He 3He 5He 8He 6He
2H 1H 3H
13N 15N 16N 18N 14N 17N 19N 20N 12N 21N 22N 23N
13O 15O 16O 18O 14O 17O 19O 20O 21O 22O 23O 24O
18F 17F 19F 20F 21F 22F 23F 24F 25F 26F 27F 29F 31F
1n
9B
8Be 15Be
20B
Edge of nuclear landscape!
Baumann, Thoennessen, Spyrou, Rep. Prog. Phys. 75, 036301 (2012).!
Artemis Spyrou, May 2, 2014, Slide 4
Stable
Transfer/Missing Mass
ȕ�'HOD\HG
5,�%HDPV�,QYDULDQW�0DVV
10Li
18B
10He
12Li
7H
9He
4H
28F 30F
25O
24N
21C
7He
13Be 16Be
16B
13Li
5H 6H
25N
26O 27O 28O
11Be 10Be 9Be 14Be 12Be
11B 10B 13B 14B 12B 15B 17B 21B 19B
13C 12C 15C 16C 18C 14C 17C 19C 20C 22C 10C 11C 9C
7Be
8B
7Li 6Li 8Li 11Li 9Li
4He 3He 5He 8He 6He
2H 1H 3H
13N 15N 16N 18N 14N 17N 19N 20N 12N 21N 22N 23N
13O 15O 16O 18O 14O 17O 19O 20O 21O 22O 23O 24O
18F 17F 19F 20F 21F 22F 23F 24F 25F 26F 27F 29F 31F
1n
9B
8Be 15Be
20B
Neutron Dripline
Neutron - unbound states • Nuclear structure/Shell evolution/3NF • Halo Structures • 2n Decay (n-n correlations)
26O
Artemis Spyrou, May 2, 2014, Slide 5
Stable
Transfer/Missing Mass
ȕ�'HOD\HG
5,�%HDPV�,QYDULDQW�0DVV
10Li
18B
10He
12Li
7H
9He
4H
28F 30F
25O
24N
21C
7He
13Be 16Be
16B
13Li
5H 6H
25N
26O 27O 28O
11Be 10Be 9Be 14Be 12Be
11B 10B 13B 14B 12B 15B 17B 21B 19B
13C 12C 15C 16C 18C 14C 17C 19C 20C 22C 10C 11C 9C
7Be
8B
7Li 6Li 8Li 11Li 9Li
4He 3He 5He 8He 6He
2H 1H 3H
13N 15N 16N 18N 14N 17N 19N 20N 12N 21N 22N 23N
13O 15O 16O 18O 14O 17O 19O 20O 21O 22O 23O 24O
18F 17F 19F 20F 21F 22F 23F 24F 25F 26F 27F 29F 31F
1n
9B
8Be 15Be
20B
Neutron Dripline
26O
Oxygen: 8 protons+ 16 neutrons Fluorine: 9 protons + ≥ 22 neutrons
WHY ?
Artemis Spyrou, May 2, 2014, Slide 6
Spectroscopy of n-rich oxygen isotopes
28O ?!
Artemis Spyrou, May 2, 2014, Slide 7
unbo
und
boun
d 26O: Bound or Unbound?
o 26O largely unconstrained
o Theoretical predictions of the
S(2n) vary from -5 to +5 MeV
o experimental data needed for
comparing to theory
Theoretical predictions of 26O S(2n)
between 1987 to 2012
Artemis Spyrou, May 2, 2014, Slide 8
production target
final focus
Be 1316 mg/cm2
Al wedge
27F
26O experiment
48Ca
48Ca 140 MeV/u
Artemis Spyrou, May 2, 2014, Slide 9
26O experiment
n! 24O!n!
Artemis Spyrou, May 2, 2014, Slide 10
Experiment
Previous MoNA Experiment: Hoffman et al. PRL 2008 Measured g.s. of 25O @ 770 keV
Current work: Presence of low-energy neutrons
Dashed-lines CSM predictions Volya & Zelevinsky PRL 2005
Artemis Spyrou, May 2, 2014, Slide 11
Ground state of 26O Lunderberg, DeYoung, Kohley, et al., PRL 108, 102501 (2012).
Causality cuts: • Δv = 7 cm/ns • Δd = 25 cm
Cross Talk: Single neutron interacting twice (false 2n signal).
26O unbound by < 200 keV
Artemis Spyrou, May 2, 2014, Slide 12
unbo
und
boun
d 26O: Bound or Unbound?
o 26O unbound by <200 keV
26O unbound by <50 keV
C. Caesar, PRC 88 (2013) 034313
Artemis Spyrou, May 2, 2014, Slide 13
26O and Three-body forces
Otsuka et al. PRL. 105, 032501 (2010).!
Cipollone et al. PRL 111, 062501 (2013).!
Self-consistent!Green’s function!
Hergert et al. PRL 110, 242501 (2013).!
IM-SRG!In-medium similarity!
renormalization group!
Hagen et al. PRL 108, 242501 (2012).!
Coupled-cluster!
Holt et al. EPJA 49, 39 (2013).!C. Caesar, PRC 88 (2013) 034313!
Shell model!
Artemis Spyrou, May 2, 2014, Slide 14
26O and Three-body forces
Otsuka et al. PRL. 105, 032501 (2010).!
Cipollone et al. PRL 111, 062501 (2013).!
Self-consistent!Green’s function!
Hergert et al. PRL 110, 242501 (2013).!
IM-SRG!In-medium similarity!
renormalization group!
Hagen et al. PRL 108, 242501 (2012).!
Coupled-cluster!
Holt et al. EPJA 49, 39 (2013).!
A. Ekstrom, et al., PRL 110 (2013)192502!
C. Caesar, PRC 88 (2013) 034313!
Shell model!
Artemis Spyrou, May 2, 2014, Slide 15
2n radioactivity
Grigorenko et al. PRC 84, 021303(R) (2011)
~10-14 s!
• Pfutzner et al. (2012): T1/2 > 10-14 s (10 fs) - Emission of particle from atomic nucleus - K-shell vacancy half-life of carbon atom 2 x 10-14 s - Width (G) is 0.03 eV, which is about room temp • Cerny & Hardy (1977): T1/2 > 10-12 s (1ps) • IUPAC, discovery of element: T1/2 > 10-14s (10 fs) - Around the time for nucleus to acquire outer electrons
Artemis Spyrou, May 2, 2014, Slide 16
R3B-LAND results
C. Caesar & R3B Collaboration, Phys. Rev. C 88, 034313 (2013) L.V. Grigorenko et al., Phys. Rev. C 84 (2011) 021303
2σ limit Erel < 120 keV
Lifetime limit: t < 5.7 ns 2σ limit = 11.8 ns
Artemis Spyrou, May 2, 2014, Slide 17
Half-life measurement
increased lifetime = reduced velocity neutrons!
Vrel = Vn - Vfrag!
Gated on 26O G.S.!
Unbinned maximum likelihood technique!
Kohley et al., Phys. Rev. Lett. 110 (2012) 152501
82% C.L. for possible finite two-neutron radioactivity lifetime!
Lifetime: T1/2 = 4.5+1.1 (stat.) ±3 (syst) ps!−1.5!
Artemis Spyrou, May 2, 2014, Slide 18
New Lifetime calculations
L.V. Grigorenko, I.G. Mukha, and M.V. Zhukov, PRL (2013)
“realistic theoretical limits”
Realistic energy limit ET < 1 keV
Improve Edecay constraints
Artemis Spyrou, May 2, 2014, Slide 19
Status + Needs
Experiment 1. Improve the 26O constraints on decay
energy and half-life 2. Measure 28O!!!!
Theory 1. Optimized 2N vs 3N 2. Reliable 28O predictions 3. 26O – width/half-life
Artemis Spyrou, May 2, 2014, Slide 20
Thanks
Thomas Baumann Daniel Bazin Michael Jones Zach Kohley Anthony Kuchera Jenna Smith Michael Thoennessen
Theory Alex Brown Jeff Tostevin Alexander Volya
Hope College: E. Lunderberg P. A. DeYoung
