n = z
DESCRIPTION
LOI for the AGATA-PRESPEC campaign, GSI Relativistic Coulomb excitation for probing special effects of neutron-proton correlations around 100 Sn B. C ederwall , R. Wadsworth, G. De France et al. N = Z. N=Z line coincides with doubly-magic core Single-particle states wrt 100 Sn core - PowerPoint PPT PresentationTRANSCRIPT
N =
Z
N=Z line coincides with doubly-magic core
Single-particle states wrt 100Sn core
Neutron-proton correlations in identical orbitals
Neutron-proton (isoscalar) pairing
Emergence of collectivity...
Bo Cederwall AGATA Physics WS, Istanbul May 2010
LOI for the AGATA-PRESPEC campaign, GSI
Relativistic Coulomb excitation for probing special effectsRelativistic Coulomb excitation for probing special effectsof neutron-proton correlations around of neutron-proton correlations around 100100SnSn
B. CB. Cederwallederwall, R. Wadsworth, G. De France et al., R. Wadsworth, G. De France et al.
Main physics aimsMain physics aims
• Verify IsoscalarVerify Isoscalar spin-aligned neutron-proton couplingspin-aligned neutron-proton coupling schemescheme in in 92 92PdPd ( (9696Cd)Cd)
• Investigate Collective strength in Investigate Collective strength in 106,108 106,108Te,Te, 112112XeXe
by by measuring measuring B(E2; 0B(E2; 0++→ 2→ 2++))
Builds on our spectroscopic work at GANIL and JYFLBuilds on our spectroscopic work at GANIL and JYFL
and theoretical calculations by J. Blomqvist, R. Liotta, C. Qi, D. Delion et al.and theoretical calculations by J. Blomqvist, R. Liotta, C. Qi, D. Delion et al.
Bo Cederwall AGATA Physics WS, Istanbul May 2010
When approaching N=Z, ”normal” pair correlations may remain or evenbe extended:
Near N=Z we can have T=1T=1, I=0I=0 (”isovector”) nnnn, pppp Cooper pairsas well as npnp Cooper pairs (neutrons and protons occupy identical orbits)
and/or: T=0, I=1... (”isoscalar”) np pairing T=0, I=1... (”isoscalar”) np pairing
Does T=0 pairing exist and, if so, how should it best be revealed?
The nature of nuclear pair correlationsand their effect on nuclei near N=Z
So far, the search for T=0 np pairing has focused on special features: - g.s. binding energies of odd-odd nuclei - high-spin properties of N=Z nuclei (delayed alignments?) - deuteron transfer reactions
Bo Cederwall AGATA Physics WS, Istanbul May 2010
The isoscalar (np) pair gap is predicted toincrease sharply as NZ
Calculation by W. Satula, R. WyssPhys. Rev. Lett. Vol. 86, 4488 (2001)
Bo Cederwall AGATA Physics WS, Istanbul May 2010
• Shell model calculations by J. Blomqvist et al. predict strong T=0 neutron-proton (np) correlations leading to an isoscalar spin-aligned np coupling scheme for N=Z nuclei close to 100Sn.
An ”unexpected effect” of the NSM appearing in this exotic region of the nuclear chart
• Evidence for onset of collectivity, possibly induced by np pairing*) in neutron deficient Te and Xe nuclei
• The proposed experiments aim to confirm these theoretical predictions by measuring B(E2;0+ 2+) values.
*) M. Sandzelius, B. Hadinia, B. Cederwall, et al., Phys. Rev. Lett. 99, 022501 (2007).QRPA + np pairing calculations by D.S. Delion, R. Liotta et al. , PRC in press
“New” effects of neutron-proton correlations around 100Sn
Bo Cederwall AGATA Physics WS, Istanbul May 2010
What is the g.s. structure of N=Z nuclei below What is the g.s. structure of N=Z nuclei below 100100Sn?Sn?
The conventional picture :The conventional picture :
ΨΨ=({νg =({νg 9/29/2-2-2}}0+0+))nn x ({πg x ({πg 9/29/2
-2-2}}0+0+))nn
This would lead to a normal seniority type spectrum of This would lead to a normal seniority type spectrum of low-lying excited stateslow-lying excited states
νg9/2-1
νg9/2-1
πg9/2-1
πg9/2-1
νg 9/2-1 νg 9/2
-1
πg9/2-1
πg9/2-1
100Sn
9292PdPd
For For 9292Pd and Pd and 9696Cd Cd neutrons and protonsneutrons and protonsmainly occupy the mainly occupy the g g 9/29/2 subshellsubshell
νg9/2-1
νg9/2-1
πg 9/2-1
πg 9/2-1
100Sn
9696CdCd
Bo Cederwall AGATA Physics WS, Istanbul May 2010
Shell Model calculations predict strong np interactionsShell Model calculations predict strong np interactions Transition to new spin-aligned T=0 np coupling scheme Transition to new spin-aligned T=0 np coupling scheme
for N=Z nuclei below for N=Z nuclei below 100100Sn (J. Blomqvist et al.)Sn (J. Blomqvist et al.)
ΨΨ=[({νg =[({νg 9/29/2-1 -1 xx πg πg 9/29/2
-1-1}}9+9+))22]]0+0+
x x [({νg [({νg 9/29/2-1 -1 xx πg πg 9/29/2
-1-1}}7+7+))22]]0+ 0+
100Sn
πg9/2-1 νg9/2
-1
νg9/2-1 πg9/2
-1
πg9/2-1νg9/2
-1
νg9/2-1
πg9/2-1
Model space: g9/2 (and f5/2 , p3/2 ,p½ )9292PdPd
Aligned np coupling:Aligned np coupling:
100Sn
πg9/2-1
νg9/2-1
νg9/2-1
πg9/2-1
9696CdCd
ΨΨ=[({νg =[({νg 9/29/2-1 -1 xx πg πg 9/29/2
-1-1}}9+9+))22]]0+0+
Bo Cederwall AGATA Physics WS, Istanbul May 2010
Pd level systematics near N=ZPd level systematics near N=Z
Shell model calculations by J. Blomqvist, R. Liotta, C. Qi
92Pd, theory 92Pd, exp 94Pd, exp94Pd, theory 96Pd, theory 96Pd, exp
Bo Cederwall AGATA Physics WS, Istanbul May 2010
Pd level systematics near N=ZPd level systematics near N=Z- effects of np interactions- effects of np interactions
Bo Cederwall AGATA Physics WS, Istanbul May 2010
Shell model calculations by J. Blomqvist, R. Liotta, C. Qi
New manifestation of T=0 np ”pairing”? New manifestation of T=0 np ”pairing”?
100Sn
l=6 l=6
l=8l=8
9292PdPd
Special deuteron-hole cluster like ground states imply significant deformation
”Nuclear belly dancers”
100Sn
l=8
l=8
9696CdCd
Bo Cederwall AGATA Physics WS, Istanbul May 2010
B(E2; 0B(E2; 0++ 2 2++) – sensitive probe of neutron-proton interactions) – sensitive probe of neutron-proton interactions
Bo Cederwall AGATA Physics WS, Istanbul May 2010 Shell model calculations by J. Blomqvist, R. Liotta, C. Qi
Enhanced collective strength at N=Z
Bo Cederwall AGATA Physics WS, Istanbul May 2010
Evidence for enhanced collectiveEvidence for enhanced collectivestrength in Te and Xe nuclei approaching N=Zstrength in Te and Xe nuclei approaching N=Z
TZ=1 nucleus 106Te : B. Hadinia, B. Cederwall et al., Phys. Rev. C 72, 041303 (2005)
Bo Cederwall AGATA Physics WS, Istanbul May 2010
Te experimental E(2+) and B(E2; 2+→ 0+)
TZ=1 nucleus 110Xe; M. Sandzelius, B. Hadinia,, B. Cederwall et al., Phys. Rev. Lett. 99, 022501 (2007)
Bo Cederwall AGATA Physics WS, Istanbul May 2010
Xe experimental E(2+) and B(E2; 2+→ 0+)
Taken from R.F. Casten, 2003 Taken from R.F. Casten, 2003
These trends can change with np pairing as N→Z !Enhancement of collectivity due to np (short-range) pairingcorrelations predicted in new calculations by D.S Delion, R. Liotta et al.
Quadrupole collectivityQuadrupole collectivityThe traditional view of the mechanism behind deformation and collectivity: long range np QQ
interactions
Bo Cederwall AGATA Physics WS, Istanbul May 2010
New QRPA + np pairing calculations predict New QRPA + np pairing calculations predict enhanced collectivity near the N=Z=50 double shell enhanced collectivity near the N=Z=50 double shell
closure induced by np pairing correlations (D.S. closure induced by np pairing correlations (D.S. Delion, R. Liotta Delion, R. Liotta et alet al.).)
p-h excitationsinduced by np pairing
Strong decrease in E(2+)with increasing Δpn
Much smaller effectfrom long-range QQ np int.
Bo Cederwall AGATA Physics WS, Istanbul May 2010
Shell model calculations for light Te isotopes indicate Shell model calculations for light Te isotopes indicate that configuration mixing due to the monopole that configuration mixing due to the monopole
tensor tensor force between primarily the proton 0gforce between primarily the proton 0g7/27/2 and and neutron 1dneutron 1d5/25/2 orbitals orbitals can induce enhanced can induce enhanced
collectivity (C. Qi, R. Liotta collectivity (C. Qi, R. Liotta et alet al.).)
Bo Cederwall AGATA Physics WS, Istanbul May 2010
Octupole deformation and correlations near N=Z
34
56
88
134
202
56112
56 Ba
“Doubly-magic octupole-deformed”nucleus predicted by theory
Strong octupole correlations are expectedin nuclei where normal-parity single-particlestates and intruder states differing byΔl = Δj = 3 are near the Fermi surface.
Coherent octupole correlations forneutrons and protons should occurnear N=Z.
Can we observe additional enhancementdue to dynamic np correlations ?
Next to 112Ba (accessible with current technology?) 110Xe56 and 109I56 might have the largest octupole stability.
Enhanced octupole correlations in light Te-Xe nuclei
J.F. Smith et al.Phys. Lett B523, 13 (2001) (Gammasphere)
G. de Angelis et al.Phys. Lett B535, 153 (2002) (Euroball)
G.F. Lane et al.Phys. Rev. C57, R1022 (1998) (Gammasphere)
Bo Cederwall AGATA Physics WS, Istanbul May 2010
• Measure B(E2; 0Measure B(E2; 0++22++) for isotopic chain ) for isotopic chain 92,94,9692,94,96PdPd (from N=Z to N=50 closed shell)(from N=Z to N=50 closed shell)
• Measure E(2Measure E(2++) for ) for 9696Cd and B(E2; 0Cd and B(E2; 0++22++) for ) for 96,9896,98CdCd (from N=Z to N=50 closed shell) (from N=Z to N=50 closed shell)
• Search for decay of 16Search for decay of 16++ spin trap isomer for spin trap isomer for 9696CdCd
Confirm spin-aligned neutron-proton coupling scheme andcharacterize np interactions (T=0/T=1)
• Measure E(2Measure E(2++) for ) for 106106Te and B(E2; 0Te and B(E2; 0++22++) for ) for 106,108106,108Te, Te, 112112XeXe
Measure and characterize collective strength
Proposed ExperimentsProposed Experiments
Bo Cederwall AGATA Physics WS, Istanbul May 2010
Experimental detailsExperimental details
Projectile fragmentation FRS – AGATA – LYCCAProjectile fragmentation FRS – AGATA – LYCCA92-9692-96Pd: LISE++ calc for primary beam Pd: LISE++ calc for primary beam 106106CdCd
Ebeam = 650 MeV/u Ibeam = 1 pnA
S4 ion and γγ-ion ratesSetting 1: optimizing for 92PdSetting 2: optimizing for 94PdAssume 15% AGATA pp efficiency, σ(Coulex) from DWEIKO
Bo Cederwall AGATA Physics WS, Istanbul May 2010
Setting 92Pd 94Pd 96Pd
S4(s-1)
γ-ion (per day)
S4(s-1)
γ-ion (per day)
S4(s-1)
γ-ion (per day)
1 1.6 200 8.0 1000 - -
2 - - 1000 1.2·105 300 3.8·104
Experimental details, ct’dExperimental details, ct’d
Projectile fragmentation FRS – AGATA – LYCCAProjectile fragmentation FRS – AGATA – LYCCA96-9896-98Cd: LISE++ calc for primary beam Cd: LISE++ calc for primary beam 112112SnSn
Ebeam = 650 MeV/u Ibeam = 1 pnA
S4 ion and γγ-ion ratesSetting optimized for 96Cd
Assume 15% AGATA pp efficiency, σ(Coulex) from DWEIKO
Bo Cederwall AGATA Physics WS, Istanbul May 2010
96Cd 98Cd
S4(s-1)
γ-ion (per day)
S4(s-1)
γ-ion (per day)
0.1 13 4.0 500
Experimental details, ctd’Experimental details, ctd’
Projectile fragmentation FRS – AGATA – LYCCAProjectile fragmentation FRS – AGATA – LYCCA106,108106,108Te, Te, 112,114112,114Xe : LISE++ calc for primary beam Xe : LISE++ calc for primary beam 144144SmSm
Ebeam = 950 MeV/u Ibeam = 1 pnA
S4 ion and γγ-ion ratesSetting 1: optimizing for 106Te
Setting 2: optimizing for 112XeAssume 15% AGATA pp efficiency, σ(Coulex) from DWEIKO
Bo Cederwall AGATA Physics WS, Istanbul May 2010
Setting 106Te 108Te 112Xe 114Xe
S4(s-1)
γ-ion (per day)
S4(s-1)
γ-ion (per day)
S4(s-1)
γ-ion (per day)
S4(s-1)
γ-ion (per day)
1 0.2 25 20 2.4·103 - - -
2 - - - - 30 3.6·103 1.0·103 1.2·105
Backup slidesBackup slides
Bo Cederwall AGATA Physics WS, Istanbul May 2010
9292Pd analysis (prel) Pd analysis (prel) γγγγ2n2n
Three Three γγ rays firmly identified, mutually concident rays firmly identified, mutually concident
γ -gated on 2+- 0+
γ -gated on 6+- 4+
6+- 4+
2+- 0+4+- 2+
4+- 2+
Bo Cederwall AGATA Physics WS, Istanbul May 2010
92.94,9692.94,96Pd levels and the role of T=0 np interactions at N=Z Pd levels and the role of T=0 np interactions at N=Z
Bo Cederwall AGATA Physics WS, Istanbul May 2010
92Pd theofull np
92Pd theono np
92Pd T=0
92Pd T=1
96Pd theo
96Pd exp
96,9896,98CdCd
Shell model calculations by . Blomqvist, R. Liotta, C. Qi et al.
Bo Cederwall AGATA Physics WS, Istanbul May 2010
Pd level systematics near N=ZPd level systematics near N=Z
Shell model calculations by J. Blomqvist, R. Liotta, C. Qi
Bo Cederwall AGATA Physics WS, Istanbul May 2010
96,9896,98Cd level and the role of T=0 np interactions at N=Z Cd level and the role of T=0 np interactions at N=Z
96Cd theofull np
96Cd theono np
96Cd T=0
96Cd T=1
98Cd theo 98Cd
Bo Cederwall AGATA Physics WS, Istanbul May 2010