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Physics LOI for NEDA

Physics LOI for NEDA. Valencia 4 November 2010. NEDA LOI Istanbul 19 june 2009. SPES LOI LNL 15 november 2010. LOI SPIRAL2 Phase 2 17 December 2010. R. Wadsworth University of York , G. de Angelis INFN LNL. Spes – LNL Radioactive Ion Beam Facility.

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Physics LOI for NEDA

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  1. Physics LOI for NEDA Valencia 4 November 2010 NEDA LOI Istanbul 19 june 2009 SPES LOI LNL 15 november 2010 LOI SPIRAL2 Phase 2 17 December 2010 R. Wadsworth University of York , G. de Angelis INFN LNL

  2. Spes – LNL Radioactive Ion Beam Facility 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+ • VariableEnergy : 15 MeV  70 MeV • Performances: • 750µA H- 70MeV • 35µA He2+ 70MeV

  3. Light RIBs at SPES Halo nuclei • 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)

  4. t1/2=60 y 44Ti + t1/2=3.92 h 44Sc + 1157 44Ca 44Ti Target: monoisotopic Reaction: 45Sc(p,2n) Batch mode

  5. t1/2=288 d 68Ge + t1/2=68.3 m 68Ga + 1077 68Zn 68Ge Target: natural Ga Reaction: 69,71Ga(p,2,4n) Batch mode

  6. t1/2=25.5 d 82Sr + t1/2=1.27 m 82Rb + 776 82Kr 82Sr Contamination from 85Sr Target: natural Reaction: 85,87Rb(p,xn) Batch mode

  7. Multi-target production Water flow ~ 1L/s I = 350 A 55 MeV I = 350 A 20 MeV natRb natGa Ag Parallel 82Sr (p6n), 68Ge (p,4n) and 44Ti(p,2n) production

  8. Beam area 0.78 cm2 Silber or Copper backing plate L=2mm 350 A proton beam to be dissipated: 70 MeV 24000 W Water cooling L=10mm Discontinuity among layers neglected Cooling Area 1 cm2 Target layer 0.86 mm 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 Water cooling Film Heat density to be removed

  9. Turbulent flow more effective In removing heat: Net mass transfer Laminar flow Re  1000 Turbulent flow Re  5000 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

  10. 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=58.9 water=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 waterflux 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 Flux1,1 L/s

  11. Heat Transfer from Ag/Cu layer kAg,Cu=4.03 Wm-1C-1 • 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] = 1456K1160 C =780 T1-T2= Qx/kA = 10500x0.043/[0.31x5] = 291 K Heat Transfer from target layer kTi=0.31 Wm-1C-1

  12. 44Ti production Silver backing plate L=2mm Water flow ~ 1L/s Cross section 45Sc(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 =780 45Sc 0.2 mm Ag (Melting point 1235 K) Q(t)=(6.022 1023 /A) x h x  x I = 3.6 1011 atoms/s For 10 days irradiation t1/2 = 60 y N = Q/(1-e -t ) = 3 1017 atoms44Ti corresponding to I=108 atoms/s without chemical separation.

  13. Chemical separation provided by the production of radioisotopes

  14. 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

  15. 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

  16. Reaction Paths in Nuclear Astrophysics rapid proton capture, Nuclear Astrophysics : • Element abundances in the Inhomogeneous Bib Bang Model • (Weizmann, Soreq, GANIL, York collaboration)

  17. Letter of Intent for the proposed “Neutron Wall” at SPIRAL-II Measurement of the 8Li(a,n) 11B Reaction Michael Hass for the Weizmann-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(a,n)11B

  18. Fig. 2 States in 12B that are in the region of interest for cosmological (and stellar) environment(s) at temperatures of ~ 1 GK Fig. 1 Experimental data available in the literature Michael Hass - 8Li(a,n)11B

  19. 11B 11B(n,a)8Li 5 1012 pps • Under current R&D: • Diffusion and effusion in the material • Ionization and extraction • Choice of ion source 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(a,n)11B

  20. Neutron (energy) + charge particle detections • 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 Fig. 3 The proposed experimental setup. Michael Hass - 8Li(a,n)11B

  21. Isospin effects on the symmetry energy and stellar collapse Why is it important to study the symmetry energy ? (Naples, Debrecen, LNL, Florence collaboration) • 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 A. Di Nitto Fusion-evaporation reactions: Esym affects the particle B.E.

  22. SYMMETRY ENERGY Framework: Dynamical Shell Model Hartree-Fock Coupling single particle states to suface vibrations Nucleon effective mass A. Di Nitto mw(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)[mw(T)-1 –mw(0)-1] mw(T)=m + [mw(0) – m]exp(-T/To)

  23. A. Di Nitto 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

  24. Isospin effects on the level density parameter a Study with RIB’s from SPIRAL2 • Observables • - s(xn channels) • n en. spectra • - ER yields n 84Ge + 4He A. Di Nitto n 134Sn + 4He A strong sensitivity on isospin is also expected for the evaporation residue yields Experimental setup: NEDA coupled to the gamma ray spectrometers EXOGAM or AGATA and/or the spectrometer VAMOS. (NEDA: TOF Measurements 3% resolution, energy threshold  1 MeV). Lcp could be also measured by Diamant.

  25. 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 Measurements on nuclei with the same Z and different isospin allow to Study of the role of isospin in fission dynamics: A. Di Nitto Preliminary results from a dynamical model based on three dimensional Langevin equations 230 MeV 32S +92Mo Lcrit = 74  750 MeV 118Pd + 26Mg Lcrit =81  Ex122 MeV Experimental setup: NEDA coupled to fission fragment detectors

  26. 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

  27. 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

  28. G. de France

  29. 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

  30. Need for an Isospin Breaking NN term

  31. Description of Coulomb effects Zuker et al,(2002) Ekman et al, (2004) Bentley,Lenzi, (2007) VCM Multipole term Coulomb contribution between valence protons Spin alignment Monopole term Vcm= εll + εls + VCr εll orbital single-particle shift for proton Shell model calculation εls spin-orbit single-particle shift (EM pot.) Isospin Breaking NN term in the fp region Radial term: radius R changes with J VCr

  32. fpg mass region Coulomb and isospin nonconserving NN interaction break charge symmetry R. Orlandi et al., PRL103,052501(2009) Good charge symmetry ? Mirror Energy Differences (MED) D. G. Jenkins et al., PRC64,064311(2001) G. de Angelis, Prog. Part. Nucl. Phys. 59, 409 (2007)

  33. MED radial orbital multipole spin-orbit Apparently no need of an Isospin Breaking NN term in the fpg shell!

  34. 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

  35. 64 32 32 64Ge Dobaczewski and Hamamoto Phys. Lett. B345 181 (1995) Electromagnetic Transition Probabilities Observation of a forbidden E1 transition in 64Ge forbidden E1? EUROBALL IV + Plunger experiment E. Farnea et al. Phys. Lett. 551B, 56 (2003) 32S+40Ca 125 MeV

  36. Isospin Mixing in Mirror Pairs 1) Charge invariance of the nuclear interaction In the validity of isospin symmetry 2) Long-wavelength approximation B(E1) strengths are identical in T=1/2 mirror pairs • 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) B(E1) = BIS(E1) + BIV(E1) J. Ekman et al. PRL 92, 132502 (2004)

  37. 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

  38. Coulomb Energy Differences and Nuclear Shapes (York, LNL, Padova, Sofia collaboration) Neutron multiplicity information, charged particle and gamma information

  39. Z+1 Z+½ Z N=Z Z-1 Z-½ 36 70Kr 35 70Br N=Z 70Se 34 34 35 36 N = Z Nuclei and Mirror Symmetry According to the Pauli principle protons and neutrons behave identically Only strong interaction In reality T = 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.

  40. 74Kr   Shape Coexistence in Mass 70 M. Bender et al., PRC 74, 024312 (2006) M. Girod oblate prolate Prolate ground state

  41. Shape effects 66As 66As data suggests that A=70 CED data is unique ! G deAngelis et al., to be published GAMMASPHERE, Neutron shell, Microball: 40Ca(32S,αpn) @ 90 MeV Target: 550μg/cm2 on 10mg/cm2 Au

  42. Shape effects Excited 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-existence n-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.

  43. Shape effects Calculations by A Pertrovici 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!

  44. P2+ is function of • transitional matrix element B(E2) • diagonal matrix element Q0 Mf If Ii Coulomb Excitation of 70Se at REX-ISOLDE • 70Se on 104Pd at 2.94 MeV/u • integral measurement • excitation probability via normalization to known 104Pd • one measurement, • but two unknowns ! A.M. Hurst et al., PRL 98, 072501 (2007)

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