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Nuclear Structure Now (precision and discovery)
C.J.(Kim) ListerLister@anl.gov
2C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
Our Nuclear Domain
3C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
RIBF@RIKEN
FAIR@GSI
FRIB@MSU
4C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
A different view of our nuclear world
5C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
Ab-initio Greens Functional Monte Carlo Calculations
Pieper and Wiringa (ANL)
Described in
NP A751 516c (2005)
6C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
Neutron Stars
7C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
Testing Ab-Initio Calculations
8C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
RMS Radii of 6,8He
6He
P.Mueller et. al (ANL)
9C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
RMS Radii of 6,8He
L.-B. Wang et al., PRL 93, 142501 (2004)
P. Mueller et al., PRL 99, 252501 (2007).
After some convergence issues were resolved, predictions of charge radii very good, ~ 1%
…..matter radii not quite so good.
10C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
Transfer ReactionsANL-UWM CollaborationA. H. Wuosmaa et. al. PRL94 082592 and PRC72 061301(R) 2005
Example: 6He(d,p)7He
Issues: How reliable are calculations of unbound states?
Is there a low lying state below 1MeV?
Sn=0.533 l=1 p3/2
No renormalization
to QMC calculations
Data
Fit to g.s. and Ex=2.25,=3.0 MeV state
11C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
Transfer ReactionsCompare: 6He(d,p)7He and 8Li(d,3He)7He
Issues: Is spectroscopy of broad resonances possible?
Yes!!Using selective in both population and decay
channels
1/2 -
5/2-
12C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
The Special Case of Beryllium Nuclei
13C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
Key Issues: Microscopically, how do the neutrons really form a potential to bind the nucleus? Is it the same for all states?
14C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
Investigating 8Be
Upshot: Test of electromagnetic decay from unbound resonance
Experiment
Ab-Initio Theory
4211 825)24:2( fmeEB
424.02.18)24:2( fmeEB
…..Here in Mumbai!!
15C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
The Bound States of 10Be
0+
2+
2+1-
10Be
5958
2589
25905960
3367E2
E1E1E2
M1/E2
2- 62632895
0+ 61792811
219E1
6812 9Be+n
16C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
4211 )10(5.10)02;2( fmeEB
4211 )30(89.7)02;2( fmeEB
4212 )26(08.2)02;2( fmeEB
10Be Data Compilation
GFMC TheoryQ ≤ 0
Q ≥ 04212 )10(9.6)22;2( fmeEB
A=10 nuclei provide a sensitive test of GFMC
S.C. Pieper, K. Varga and R.B. Wiringa, Phys. Rev. C 66, 044310 (2002).
Very sensitive to the effects
of 3-body correlations.
8.3)02:2(
)02:2(
12
11
EB
EBR
17C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
Ken Nollett (ANL) and Brent Graner (UC) visulization of 10Be J=21 state (2008)
The Ab-Initio projection of T=0 and T=1 density
18C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
The Traditional Shell Model (1956+++)
Kurath, Cohen and Kurath, Millener and Kurath, Millener and Warburton
R=11.3
19C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
10Be : A popular nucleus)02;2( 11
EB )02;2( 12 EB
(e2fm4)RatioAuthor
Okabe MO 11.26 0.44 25.6
Caurier NCSM 6.58 0.13 49.5
Itagaki TMO 11.8 0.70 16.9
Navratil NCSM 5.4 0.17 32.7
Arai MCM 4.8 0.10 48.0
Wiringa GFMC 7.89(30) 2.08(26) 3.8
EXPT 10.5(1.0) ?? ??
NCSM : No-core shell model, E. Caurier et al., Phys. Rev. C 66, 024314 (2002). MO : Molecular orbit model, N. Itagaki and S. Okabe, Phys. Rev. C 61, 044306 (2000).
MCM : Microscopic cluster model, K. Arai, Phys. Rev. C 69, 014309 (2004). TMO : Triaxial Molecular Orbital, N. Itagaki et al., Phys. Rev. C 65, 044302 (2002).
GFMC : Greens Functional Monte Carlo, R. Wiringa and S. Pierper et al., Private Communication.
(e2fm4) Calc.
20C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
E.K. Warburton et al., Phys. Rev. 129, 2180 (1963).
E.K. Warburton et al., Phys. Rev. 148, 1072 (1966).
G.C. Morrison et al., - unpublished (1965).
T.R. Fisher et al., Phys. Rev. 176, 1130 (1968).
Evaluated = 180(18) fsAll DSAM measurements
Previously measured DSAM J=21 lifetime in 10BeSystematic problems of:-
•Initial recoil velocity ill-defined
•Stopping powers poorly known
•Very slow recoils
•State feeding poorly known
•Detector angle poorly defined
At the time these measurements WERE cutting edge and provided discriminating tests of the (new) intermediate-coupling shell model (Kurath et al 1958) .
But now we need better!
21C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
F. Sarazin et al., Phys. Rev. C 70, 031302(R) (2004)….-decay at ISAC / TRIUMF
11Li β-delayed 1-n emissionLine shape depends on
Energies and intensities of all neutron branches feeding the level
Lifetime of the level
Angular correlation between gamma ray and neutron
Y. Hirayama et. al. Phys Lets B611 239 (2005)…..polarized -decay at ISAC/TRIUMF (high stats)
22C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
The Doppler Shift Attenuation Method
(DSAM)
23C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
The Doppler Shift Attenuation Method
v0
E = Eo {1 + (v0/c)Cos}
v(t)
Free Space
Stopping E = Eo {1 + F(t)Cos}
log(
F()
1
0Actually, recoils are sufficiently swift (v/c ~6%) that 2nd order relativistic is correction needed
24C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
What SRIM shows us
J.F. Ziegler, J.P. Biersack and M.D. Ziegler http://www.srim.org
SLOW Ions…. 1 MeV 10Be in 100g/cm2 Li on 6mg/cm2 Au
FAST Ions…. 15 MeV 10Be in 100g/cm2 Li on 6mg/cm2 Au
(99.99% electronic stopping)
25C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
DSAM*
DSAM done properly:-
2-body kinematics
High recoil velocity
Well defined recoil direction
Well defined gamma direction
Control of state population
7Li(7Li,)10Be at 10 MeV
α 10Be
10Be (g.s) = 18.2 MeV10Be* (3.3) = 16.5 MeV10Be* (5.9) = 15.0 MeV
E.A. McCutchan et. al. (ANL)
26C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
Etot in Ion Chamber
ΔE
Recoil - Gated Data3 mg/cm2 Cu backing
12
A=10 q=3 selected with FMA
Recoil-gamma time
27C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
Extracting the lifetime from mean
N
1 2 3
time
time
’s weighted by # of decays at given time t
determines weight
Ideally you want all decays in the stopping material
But…• Need some finite thickness of production material
• Need nuclei to recoil out of target
1
Cou
nts
Energy
3
2C
ount
s
Energy
2
28C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
Results (1): First excited State with J=2+ at 3367 keV7Li
7Li
7Li
66g/cm2 7Li on 6.95mg/cm2 Au
115g/cm2 7Li on 2.69mg/cm2 Au
288g/cm2 7LiF2 on 2.48mg/cm2 Cu
fs
fs
+200-100
fs
+100-60
29C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
Traditional DSAM analysis……and GS alignment
cos1
1 2
oEE
100 g/cm2 7Li on 2.33 mg/cm2 Au
30C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
Results so far for 3369keV J=2 state
31C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
The Bound States of 10Be
0+
2+
2+1-
10Be
5958
2589
25905960
3367E2
E1E1E2
M1/E2
2- 62632895
0+ 61792811
219E1
6812 9Be+n
32C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
Some Detective Work Required
I1 11-
I2 22+
I2 22+
Is it possible to untangle the two-line J=1-,2+ mess?
The states are only 1.8keV apart and have similar, short lifetimes
33C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
What we have learned so far
34C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
First J = 2+ state in 10Be
4211 )10(5.10)02;2( fmeEB
NNDC transition strength was
4211 )5(2.9)02;2( fmeEB
Our new transition strength
sysstat )8()5(205
4211 )30(89.7)02;2( fmeEB
Ab-initio transition strength
4221 )40(97.9)022:2( fmeEB
Note: The predicted ab-initio summed E2 decay strength is:
35C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
Second J = 2+ state in 10Be
NoneNNDC lifetime
fs)10(59This work
Theory seems to have much too much mixing of J=2+ states. The original GFMC with V18 and IL2 three body force predicted R=3.8
fs(??)89Sarazin et. al.
422 )3(11.0)02:2( fmeEB
)16(78)02:2(
)02:2(
2
1
EB
EBRatio
Much smaller than GFMC which initially predicted 2.08(26) e2fm4
36C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
Lessons Learned
We set out to test a model that was thought to be good at the <10% level.
Tests were for calc. stability & validating 3-body forces.
We Found:
Good agreement in absolute binding energy of the ground state. Modest agreement in the binding energies of the excited states (correct ordering, too close in energy)
Good agreement in the total collectivity, without resorting to any effective charges. Modest agreement in the distribution of strength.
37C.J. (Kim) Lister:- Frontiers In Gamma Spectroscopy 2009, Mumbai INDIA
Conclusions for 10Be In Experiment
We have made a precise measurement of the lifetime of the first excited state in 10Be. Reliable <5% DSAM IS possible.
We have determined the ratio R, which shows there is very little mixing between first and second J=2 states.
In Theory
We need to reconcile the differences:
Does the experimental distribution of B(E2) strength allow us to constrain the models of 3-body forces?
YES, but reveals more work is needed
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