physics loi for neda valencia 4 november 2010 r. wadsworth university of york, g. de angelis infn...
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Physics LOI for NEDA
Valencia 4 November 2010
R. Wadsworth University of York , G. de Angelis INFN LNL
NEDA LOI Istanbul 19 june 2009
SPES LOI LNL 15 november 2010
LOI SPIRAL2 Phase 2 17 December 2010
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Spes – LNL Radioactive Ion Beam Spes – LNL Radioactive Ion Beam FacilityFacility
Radioactive beams of species with lifetimes in excess of several days can be efficiently generated by irradiating target materials with a 40-50 MeV proton beam for a time sufficiently long for secular equilibrium to transpire followed by a transfer of the target to the ion source (Batch Mode).
• Particles: H- / D- / He2+/ HH+
• Variable Energy : 15 MeV 70 MeV
• Performances: 750µA H- 70MeV 35µA He2+ 70MeV
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Light RIBs at SPES
• A/Z t1/2(s) A/Z t1/2(s) • 6He 3.0 0.81 9Be(n,) 8B 1.6 0.77 12C(p,n)• 8Li 2.7 0.84 11B(n,) 10C 1.7 19.3 11B(p,2n)• 9Li 3.0 0.18 11B(n,3He) 11C 1.8 1224 11B(p,n)• 11Be 2.8 13.8 11B(n,p) 13N 1.9 598 13C(p,n)• 16N 2.3 7.13 16O(n,p) 14O 1.8 70.6 14N(p,n)• 18N 2.6 0.62 18O(n,p) 15O 1.9 122 15N(p,n)• 19O 2.4 26.9 19F(n,p) 18Ne 1.8 1.67 19F(p,2n)• 20O 2.5 13.5 19F(n,) 19Ne 1.9 17.3 19F(p,n)• 23Ne 2.3 37.2 24Mg(n,2p) 35Ar 1.9 1.77 35Cl(p,n)• 25Ne 2.5 0.60 26Mg(n,2p) 34Ar 1.9 0.60 35Cl(p,2n)• 25Na 2.3 59.1 25Mg(n,p)• 26Na 2.4 1.08 26Mg(n,p)
Halo nuclei
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44Ti
44Sc
44Ti
t1/2=60 y
t1/2=3.92 h
44Ca11
57
+
+
Batch mode
Target: monoisotopicReaction: 45Sc(p,2n)
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68Ge
68Ga
68Ge
t1/2=288 d
t1/2=68.3 m
68Zn10
77
+
+
Target: natural GaReaction: 69,71Ga(p,2,4n)
Batch mode
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82Sr
82Rb
82Sr
t1/2=25.5 d
t1/2=1.27 m
82Kr77 6
+
+
Target: naturalReaction: 85,87Rb(p,xn)
Contaminationfrom 85Sr
Batch mode
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natRb natGa Ag
Water flow ~ 1L/s
I = 350 A 55 MeV
I = 350 A 20 MeV
Multi-target production
Parallel 82Sr (p6n), 68Ge (p,4n) and 44Ti(p,2n) production
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Silber orCopperbacking
plateL=2mm
350 A proton beamto be dissipated:
70 MeV
24000 W
Water coolingL=10mm
Target layer0.86 mm
Beam area0.78 cm2
Cooling Area 1 cm2
Assuming Twater=200
Sc melting point 15390
Qconv= hA(T1-T2) or h = Q/[A(T1-T2)]
h = 24000 W/(1cm2) (900-20C) = 27.3 Wcm-2C-1
Film Heat density to be removed
Discontinuity among layers neglected
Water cooling
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Laminar flow Re 1000 Turbulent flow Re 5000
Turbulent flow more effectiveIn removing heat:Net mass transfer
Prandtl number: Pr=Cp/k Cp heat capacity viscosity k thermal conductivity
Nusselt number: Nu=hx/k h film heat density x significant distance
Ratio between viscous to the heat transfer properties
Ratio between heat transported by convection and heat transported by conduction
Reynolds number: Re=xV/ V velocity of the bulk fluid
Ratio of inertial forces to the viscous forces
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Thermal water conditions• Nu=hx/k=27.3x1/0.00604=4520
kwater=0.00604 W cm-1K-1
• Pr=Cp/k=4.179 x 0.8513/0.0604=58.9water=0.008513 gcm-1s-1
• Nu=0.332 Re1/2Pr1/2 Re=xV/=3.15 106
V = 2.7 104 cm s-1 If internal volume =0.5 x 2 cm2
water flux 27 L/s too much!
Reduce volume of the cooling water (increase the flow velocity) and increase surface area (incline the target to beam)
=780 L=5 Volum 0.2 cm2 Flux1,1 L/s
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Heat Transfer from Ag/Cu layer• Qcond= -kA(T1-T2)/x
T1-T 2= Qx/kA =24000x0.2/[4.03x1cm2]= 1191K 900 C
=780 T1-T2= Qx/kA = 24000x0.2/[4.03x5] = 238 K
Maximum cross section (p,2n) at 20 MeV Q = 20 x 350 = 7000 W
• Qcond= -kA(T1-T2)/x
T1-T2= Qx/kA = 10500x0.043/[0.31x1cm2] = 1456K1160 C
=780 T1-T2= Qx/kA = 10500x0.043/[0.31x5] = 291 K
Heat Transfer from target layer
kAg,Cu=4.03 Wm-1C-1
kTi=0.31 Wm-1C-1
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Silverbacking
plateL=2mm
=780
45Sc0.2 mm
Ag (Melting point 1235 K)
Water flow ~ 1L/s
Cross section45Sc(p,2n)
32 mb at 22 MeV(Phys. Rev. C 54, 2047 (96))
63 mb at 30 MeV(Nucl. Phys. A150, 11 (70))
I = 350 A
Q(t)=(6.022 1023 /A) x h x x I = 3.6 1011 atoms/sFor 10 days irradiation t1/2 = 60 y
N = Q/(1-e -t ) = 3 1017 atoms 44Ti corresponding toI=108 atoms/s without chemical separation.
44Ti production
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Chemical separationprovided by the productionof radioisotopes
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RIB in batch mode
• 9Be(p,p2n)7Be (53.2 d)
• 46Ti(p,p2n)44Ti (63 y)
• 58Ni(p,p2n)56Ni (6.1d)
• 70Ge(p,p2n)68Ge (288 d)
• 74Se(p,p2n)72Se (8.5 d)
• 84Sr(p,p2n)82Sr (25.5 d)
• 90Zr(p,p2n)88Zr(83.4 d)
Intensities ~ 107-109
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Defining the Physics• Nuclear Astrophysics
– Element abundances in the Inhomogeneous Bib Bang Model (Weizmann, Soreq, GANIL, York collaboration)
– Isospin effects on the symmetry energy and stellar collaps
• Nuclear Reactions– Level densities of neutron rich nuclei (Naples,
Bordeaux, Debrecen, LNL, Florence collaboration)– Fission dynamics of neutron-rich intermediate fissility
systems• Nuclear Structure
– Probe of the T=0 correlations in N=Z nuclei: The structure of 92Pd
– Coulomb Energy Differences in isobaric multiplets: T=0 versus T=1 states
– Coulomb Energy Differences and Nuclear Shapes– Low-lying collective modes in proton rich nuclei
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rapid proton capture,
Reaction Paths in Nuclear Astrophysics
Nuclear Astrophysics : Element abundances in the Inhomogeneous Bib Bang Model
(Weizmann, Soreq, GANIL, York collaboration)
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Letter of Intent for the proposed “Neutron Wall” at SPIRAL-II
Measurement of the 8Li(,n) 11B ReactionMichael Hass
for theWeizmann-Soreq-GANIL-York collaboration
We propose to study the 4He(8Li,n)11B reaction using 8Li beams at SPIRAL-II. The R&D efforts to produce unsurpassed intense beams of 8Li at SPIRAL-II may result in 8Li very well becoming one of the first radioactive beams to be used at SPIRAL-II. This fact, together with the unique performance of the proposed neutron wall and of other ancillary charge-particle detectors will provide an ideal experimental setup for such studies. The data thus obtained should clarify the poorly known cross section for this reaction, which is important for several scenarios in the field of explosive nucleo-synthesis.
Michael Hass - 8Li(,n)11B
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Fig. 1 Experimental data available in the literature
Fig. 2 States in 12B that are in the region of interest for cosmological (and stellar) environment(s) at temperatures of ~ 1 GK
Michael Hass - 8Li(,n)11B
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Expected Yields for a BeO target:SARAF (40 MeV, 2 mA): 8∙1012
[6He/sec]SPIRAL2 (40 MeV, 5 mA): 2∙1013
[6He/sec]
Expected Yields for a BN target:SARAF (40 MeV, 2 mA): 2∙1012
[8Li/sec]
SPIRAL2 (40 MeV, 5 mA): 5∙1012 [8Li/sec]Michael Hass - 8Li(,n)11B
11B
Under current R&D:
• Diffusion and effusion in the material• Ionization and extraction• Choice of ion source
11B(n,a)8Li5 1012 pps
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Fig. 3 The proposed experimental setup.
Issues for consideration
• 8Li@SPIRALII The present scheme uses the 11B(n,a)8Li reaction with secondary neutrons from the initial 5 mA, 40 MeV d beam with a porous BN target. Post-acceleration. Energy degrader.
• The neutron wall
• Charge particle (11B) detection
Michael Hass - 8Li(,n)11B
Neutron (energy) + charge particle detections
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Why is it important to study the symmetry energy ?
Esym=bsym(T)(N-Z)2/A
• As a part of the nuclear Equation Of State it may influence the mechanism of Supernova explosion
• General theoretical agreement on its temperature dependence (LRT+QRPA vs. large scale SMMC)
• Possible consequences of T dependence of Esym on core-collapse Supernova events
• Effects enhanced by the instrinsic isospin dependence of Esym
Fusion-evaporation reactions: Esym affects the particle B.E.
(Naples, Debrecen, LNL, Florence collaboration)
Isospin effects on the symmetry energy and stellar collapse
A. Di N
itto
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SYMMETRY ENERGY
m(T) 0 < T < 3 MeV - 98Mo, 64Zn, 64Ni
-LRT – QRPA
Decrease of the effective mass Increase of Esym
Esym(T)= bsym(T) x (N-Z)2/A
bsym(T)=bsym(0)+(h2ko2m/6mk)[m(T)-1 – m(0)-1]
m(T)=m + [m(0) – m]exp(-T/To)
Framework: Dynamical ShellModel
Hartree-Fock Coupling single particle statesto suface vibrations
Nucleon effective mass
m
mmm k
A. Di N
itto
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Nuclear Reaction Mechanisms:
Evaporative neutron emission as a probe for the level density of hot neutron-rich compound nuclei (Naples, Bordeaux, Debrecen, LNL, Florence collaboration)
Neutron energy and multiplicity information + Charged particle information + gamma ray information
A. Di N
itto
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0 1 2 3 4 5 6
100
101
102
103
Co
un
ts
En,cm(MeV)
Standard N-Z Z-Zo
0 1 2 3 4 5 6
100
101
102
103
Co
un
ts
En,cm (MeV)
Standard N-Z Z-Zo
Isospin effects on the level density parameter aStudy with RIB’s from SPIRAL2
A strong sensitivity on isospin is also expected for the evaporation residue yields
Experimental setup: NEDA coupled to the gamma ray spectrometers EXOGAMor AGATA and/or the spectrometer VAMOS. (NEDA: TOF Measurements 3% resolution, energy threshold 1 MeV). Lcp could be also measured by Diamant.
84Ge + 4He
134Sn + 4He
n
n
Observables
- xn channels)
- n en. spectra
- ER yields
A. Di N
itto
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Fission dynamics of neutron-rich intermediate fissility systems (under study)
Open questions in fission dynamics: Fission delay, nature of dissipation (one or two body) and its dependence on temperature and nuclear deformation
Systems of intermediate fissility (A 150): possibility to measure observables in both fission and evaporation residue channels
Fission BarrierBf (L=50 )
(MeV)
n- Prescissionmultiplicity
Mn
Fission time <Tfiss>
(10-21 s)
124Ce 16.3 0.046 61
144Ce 29.7 2.1 103
Measurements on nuclei with the same Z and different isospin allow to Study of the role of isospin in fission dynamics:
230 MeV 32S + 92Mo Lcrit = 74 750 MeV 118Pd + 26Mg Lcrit = 81 Ex122 MeV
Preliminary results from a dynamical model based on three dimensional Langevin equations
Experimental setup: NEDA coupled to fission fragment detectors
A. Di N
itto
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Nuclear Structure : N=Z nuclei
Probe of the T=0 correlations in N=Z nuclei: The structure of 92Pd
Coulomb Energy Differences in isobaric multiplets: T=0 versus T=1 states
Coulomb Energy Differences and Nuclear Shapes
Shape phase transitions in nuclei
Nuclear structure in the 100Sn region (batch mode)
Low-lying collective modes in proton rich nuclei
G. de France
A. Gottardo, M. Palacz
A. Pipidis
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Probe of the T=0 correlations in N=Z nuclei: The structure of 92Pd
(LNL, Stockholm, York collaboration)
Neutron multiplicity information + charged particle + gamma ray information
G. de France
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G. de France
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Coulomb Energy differences in isobaric multiplets: T=0 versus T=1 states
(Sofia, Padova, York, Ganil, LNL collaboration)
Neutron multiplicity ( and energy) information +Charged particle + gamma ray informations
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Need for an Isospin Breaking NN term
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Description of Coulomb effects
CmCMC VVV
Multipole term
Monopole term Vcm= εll + εls + VCr
Coulomb contribution between valence protons
Radial term: radius R changes with J
orbital single-particle shift for proton
spin-orbit single-particle shift (EM pot.)
l.s
dr
dV
rcmgg C
Nlsls
1
4
1)(
22
keVNA
NNllZcsll )2/3(
)]3()1(2[5.43/1
12/13
R
ZZeVCr
)1(
5
3 2
Zuker et al,(2002)Ekman et al, (2004)Bentley,Lenzi, (2007)
VCM
VCr
εll
εls
Shell model calculation
Spin alignment
Isospin Breaking NN term in the fp region
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fpg mass region
R. Orlandi et al., PRL103,052501(2009)
As)(E*Se)(E*MED 6767JJJ
Coulomb and isospin nonconserving NN interaction break charge symmetry
Mirror Energy Differences (MED)
D. G. Jenkins et al., PRC64,064311(2001)G. de Angelis, Prog. Part. Nucl. Phys. 59, 409 (2007)
Good charge symmetry ?
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MED
orbital
spin-orbit
radial
multipole
Apparently no need of an Isospin Breaking NN term in the fpg shell!
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Example: Electromagnetic Transition Probabilities
If Isospin Symmetry is valid:
E1 (T=0) transitions in N=Z nuclei are forbidden
E1 transition in mirror pairs have identical strength(higher sensitivity due to interference)
Crucial Probe of the isospin symmetry and of its validity with increasing A and Z
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Observation of a forbidden E1 transition in 64Ge
64 32 32
64Ge
EUROBALL IV + Plunger experiment
E. Farnea et al. Phys. Lett. 551B, 56 (2003)
forbidden E1?
32S+40Ca 125 MeV
Electromagnetic Transition Probabilities
Dobaczewski and HamamotoPhys. Lett. B345 181 (1995)
Dobaczewski and HamamotoPhys. Lett. B345 181 (1995)
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Isospin mixing via the IVGMR provides an induced isoscalar component
In mirror T=0 transitions• Isovector terms have opposite sign • Isoscalar terms have equal sign
B(E1) = BIS(E1) – BIV(E1)
J. Ekman et al. PRL 92, 132502 (2004)
B(E1) strengths are identical in T=1/2 mirror pairs
B(E1) = BIS(E1) + BIV(E1)
Isospin Mixing in Mirror Pairs
In the validity of isospin symmetry
1) Charge invariance of the nuclear interaction
2) Long-wavelength approximation
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N=Z nuclei: Reactions with RIBS
• 34Ar (108pps) + 40Ca (105-120 MeV)– 69Br + p 1 mb – 71Kr + 2pn 5 mb– 68Br + pn 0.2 mb– 72Rb + pn 0.1 mb
• 58Cu + 28Si (~200 MeV)– 81Nb + n 0.1 mb
• 56Ni + 28Si (~200 MeV) – 79Zr + n 0.2 mb
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Coulomb Energy Differences and Nuclear Shapes
(York, LNL, Padova, Sofia collaboration)
Neutron multiplicity information, charged particle and gamma information
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N = ZN = Z Nuclei and Mirror Symmetry Nuclei and Mirror Symmetry
In reality
According to the Pauli principle
protons and neutrons behave identically
Only strong interaction
Z
Z+1
Z-1
Z+½
Z-½
N=ZT = 1/2 Mirrors exchange the valence proton and neutron.
T = 1 Mirrors exchange two valence protons and neutrons on both sides of a odd-odd N = Z.
N=Z
35
36
35 36
70Br
34
34
70Se
70Kr
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Shape Coexistence in Mass 70Shape Coexistence in Mass 70
oblate prolate
74Kr
M. GirodM. Bender et al., PRC 74, 024312 (2006)
Prolate ground state
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Shape effects
G deAngelis et al., to be publishedGAMMASPHERE, Neutron shell, Microball: 40Ca(32S,αpn) @ 90 MeVTarget: 550μg/cm2 on 10mg/cm2 Au
66As66As data suggests that A=70 CED data is unique !
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Shape effectsExcited VAMPIR Model (A Petrovici et al Nucl Phys A483, 317 (1988))
Beyond mean-field approach with symmetry projection
Successfully used to describe analogue states in mass 70 region, Petrovici et al., Nucl Phys A728, 396 (2003)
Takes into account:Oblate/ prolate shape co-existencen-p pairing correlations in both the T=0 and T=1 channels
Calculations performed using the isospin symmetric G matrix based on Bonn A potential and Coulomb interaction between the valence protons.
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Shape effects SPIN
Nucleus Wavefn 0+ 2+ 4+ 6+
66As Obl(Prol) 16(84) 30(70) 19(81) 5(95)
66Ge 20(80) 39(61) 33(67) 9(91)
70Br 36(64) 41(59) 41(59) 20(80)
70Se 57(43) 59(41) 64(36) 39(61)
For the A=82,86 nuclei a prolate component dominates for all yrast states with amplitude >90% A Petrovici, J Phys G37 064036 (2010)
For isobaric triplets, generally assumed that the nuclei have identical shape. Calcs suggest this may not be true for the mass 70 systems!
Calculations by
A Pertrovici
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Coulomb Excitation of Coulomb Excitation of 7070Se at REX-ISOLDESe at REX-ISOLDE
70Se on 104Pd at 2.94 MeV/u integral measurement excitation probability via normalization to known 104Pd
A.M. Hurst et al., PRL 98, 072501 (2007)
P2+ is function of transitional matrix element B(E2) diagonal matrix element Q0
If
Ii
Mf one measurement, but two unknowns !
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Lifetime of the 2Lifetime of the 2++ state in state in 7070SeSeMarch 2007GASP and Köln Plunger at Legnaro
40Ca(36Ar,2p)70Se40Ca(36Ar,4p)72Se
[1] J. Heese et al., Z. Phys. A 325, 45 (1986)[2] J. Ljungvall et al., PRL 100, 102502 (2008)
old [1]
(ps)
new [2]
(ps)
B(E2;) (e2fm4)
70Se
2+ 1.5(3)
3.2(2) 342(19)
4+ 1.4(3)
1.4(1) 370(24)
6+ 3.9(9)
1.9(3) 530(96)
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ConsequencesConsequences
new lifetime measurementJ. Ljungvall et al. PRL 100,102502 (2008)
Prolate
Oblate
lifetime measurement
= 1.5(3) ps
J. Heese et al., Z. Phys. A 325, 45 (1986)
)65(615.00)2(2 11 EM
*
Lifetime measurements in the other members of the isobaricmultiplet: 70Br, 70Kr
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N=Z nuclei: Reactions with RIBS
• 34Ar (108), 30S (107)+ 40Ca (105-120 MeV)– 70Br, 65As + 3pn 1 mb – 71Kr, 67Se + 2pn 5 mb– 68Br, 64As + pn 0.2 mb– 72Rb, 68Br + pn 0.1 mb
• 58Cu + 28Si (~200 MeV)– 81Nb + n 0.1 mb
• 56Ni + 28Si (~200 MeV) – 79Zr + n 0.2 mb
A=64, 68 T=1 triplet
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Nuclear Structure :Low-lying collective modes in proton rich nuclei
Valencia, INFN LNL , Paris, INFN MI collaboration.
Neutron multiplicity (and energy), charged particle and High energy gamma information
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34Ar + 16O 44Cr + 2n
34Ar 108 pps
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Dipole Excitations towards the Proton Drip-Line
CENTROID ENERGY OF THE LOW-LYING STRENGTH
CENTROID ENERGY OF THE LOW-LYING STRENGTH
LOW-LYING TRANSITION STRENGTH B(E1)
LOW-LYING TRANSITION STRENGTH B(E1)
PROTON PYGMY DIPOLE RESONANCE
PROTON PYGMY DIPOLE RESONANCE
Paar, Vretenar, Ring, Phys. Rev. Lett. 94, 182501 (2005)
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Dipole Excitations towards the Proton Drip-Line
CENTROID ENERGY OF THE LOW-LYING STRENGTH
CENTROID ENERGY OF THE LOW-LYING STRENGTH
LOW-LYING TRANSITION STRENGTH B(E1)
LOW-LYING TRANSITION STRENGTH B(E1)
PROTON PYGMY DIPOLE RESONANCE
PROTON PYGMY DIPOLE RESONANCE
Paar, Vretenar, Ring, Phys. Rev. Lett. 94, 182501 (2005)
24Mg(p,p2n) 22Mg
22Mg + 16O 32Ar + 2n 22Mg 108 pps
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Isobaric Analog - Spin-Isospin resonances and the neutron distribution in the Sn isotopes
The predicted reduction in the spin-orbit term in the nuclear force with increasing neutron excess is believed, together with the tensor component of the residual nucleon nucleon interaction, to be the main origin of the changes in the single particle energies of intruder states and of the shell quenching effects.
Valencia, LNL, Saclay
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Difference in slope between of the neutron and proton density distributions through the excitation energies of the Gamow-Teller resonances relative to the isobaric analog states. Nucleons with spin-up and spin-down oscillate either in phase (spin scalar S=0 mode) or out of phase (spin vector S=1 mode). The spin vector, or spin-flip excitations can be of isoscalar ( S=1, T=0 ) or isovector ( S=1, T=1 ) nature. The Gamow-Teller resonance is the collective spin-isospin oscillation with the excess neutrons coherently changing the direction of their spin and isospin without changing their orbital motion (GTR) Jp=1+. The Isobaric Analogue State does not require the spin-flip ( i.e. S=0 ) ( IAS ) Jp=0+. The Wigner SU(4) symmetry implies the degeneracy of the GTR and IAS. It is broken by the spin-orbit term of the effective nuclear potential.
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Charge exchange reactions in inverse kinematics (p,n) with RIB for different isotopic chains:Es. neutron rich Sn isotopesResonance energy from the neutron spectrum, 5%-10% energy resolution should be sufficient
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Thanks for attention
• Present LOIs still under development
• Please join LOIs or present new ones
• Upgrading of the physics case is on the way (following presentations)
• Definition of the “day one” experiments