Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio 2007 Estudio experimental de la Estructura Nuclear: Modos Exóticos de Desintegración Mª José García Borge

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio 2007 The Nuclear landscape Decay + -EC Decay - Decay Fission 256 stable nuclei Terra Incógnita 4 o-o 157 e-e 104e-o Near de Drip-line Halo structure Re-ordering of shells gaps Beta asymmetry Exotic decays Order to Chaos

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio 2007 Beta decay Studies Transport system target Ion source Mass Separator recoil. β γ + ZANZAN Z-1 A N+1 γ γ Accelerator

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio 2007 Producción de Núcleos Exóticos p 1GeV p n F r + espalación 1 1 L i X + + fragmentación C s Y + + fisión

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio 2007 Energy: 1 GeV (1.4 GeV) Pulse frequency: 1.2 s Intensity: 3.2x10 13 protons per pulse I (average): 2 A Firenze, 6 March 2006 Target + Ion Source Separator Isotope Separator on CERN

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio 2007 Nuclear Stability BE(A,Z) = ZMpc 2 + NMnc 2 – M( A Z X N )c 2 Using the Bethe-Weizsäcker ec. for BE(A,Z) M( A Z X N )c 2 = ZMpc 2 + NMnc 2 - a v A + a s A 2/3 + a c Z(Z-1)A -1/3 + a A (A-2Z) 2 /A - a p A -1/2 Odd-A-impar 1 Stable nucleus The rest Even-A 2 parabolas For each A Parabolic behaviour with Z x = M n c 2 -a v + a A + a s A 1/3 M( A Z X N )c 2 = xA + yZ + zZ 2 + 0( ) y = (M p -M n )c 2 - 4a A - a c A 1/3 z = a c A 1/3 + 4a A /A

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio 2007 Decay properties of exotic nuclei Selection rules: Fermi: T= J=0 ; f = i Gamow-Teller: T=0±1; J=0±1 ; f = i Very Selective probe Reduced transition probability: Global properties Short half-lives ( 10ms) High Q values Low S p/n values -delayed particle emission 1916 Rutherford & Wood [Philos. Mag. 31 (1916) 379] 1963 Barton & Bell identified 25 Si as p Particle energy spectrum determined by 2 factors 1-intensity of -decay branches from precursor to the emitter 2-probability of emission by proton rather gamma

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio 2007 Beta Delayed Proton Emission (TODAY) Today more than 134 precursor known Properties well understood This spectroscopic tool is often the only way to identify exotic nuclei Data provide large spectroscopic information Level density Spin, isospin Width & density -decay properties In 33 Ar low level density, spectrum marked for proton peaks Cut off at low energy at the Coulomb barrier IAS (only in precursors with T Z - 3/2) In the rest bellshape spectrum with superimpose peak structure no individual transition rather cluster of them atributed to Porter-Thomas fluctuations Emitter even-even Q EC and B p large populate high excited states rather smooth spectrum Emitter even-odd B p low proton emitted from low states fluctuations more pronunced Notice differences IAS

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio 2007 Electron-Neutrino Correlations ( p emitters) E p (MeV) 33 Ar p-spectrum free of -summing 32 Ar E p (MeV) Study of the proton line shape Physics beyond the SM Isospin mixing in Fermi decays Configuration mixing Level interferences Spin assignment Excitation energies Schardt & Riisager, Z. Phys. A 345 (1993) 265 Adelberger & Garcia, Hyp. Int 129 (2000) 237 Instead of detecting the neutrino 32 Ar 32 Cl 31 S+p The proton has info about the 32 Cl recoil (Doppler)

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio 2007 Production of neutron deficient GANIL In-flight production allowed to extract very short species. Beams of 16 0, 36 Ar, 40 Ca, 58 Ni, 70 Ge & 78 Kr on secondary targets p, 2p in the sd-, pf-shell has been produced by fragmentation reaction at GANIL using the LISE-spectrometer 2p Radioactivity

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio 2007 Analysis of -protons data Counts Energy (keV) Strong beta summing Experiment Theory 21 Mg

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio 2007 = 4.8 (4) % Mirror Asymmetry & Systematics Average asymmetry : 11 (1) % in the 1p shell (A<17) 0 (1) % in the (2s,1d) shell (17<A<40) Allowed Gamow-Teller transitions (log(ft)<6) 17 couples of nuclei 46 mirror transitions Thomas et al., AIP Conf. Proc 681, p : n p + e - + np ft - + : p n + e + + E.C. : p + e - n + np ft + = nuc + SCC

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio 2007 Spectroscopy studies wuth -p isotopes Studied Macroscopy Properties : T 1/2, P p Spectroscopy: Partial Decay scheme IAS Identification IMME T 1/2 = (20.8 ± 0.3) ms P p = (79.0 ± 2.7) % 43 Cr Spectroscopy of Neutron Deficient nuclei 22 < Z < Cr M(A,T,Tz) = a() +b()Tz + c()Tz 2 +

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio 2007 Exotic Radioactivities 2p-radioactivity (Z,N) 2p + (Z-2,N) 1p-radioactivity (Z,N) p + (Z-1,N)

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio Proton Radioactivity Proton-radioactivity from gs determine the limit for neutron deficient nuclei Q p = ( M Z+1 – M Z – m p – m e ) c 2 > 0 Q p = BE Z – BE Z+1 > 0 (Qp ( 151 Lu) = 1241 keV) Emission of protons only from odd-Z [50-83] The sensitivity of T 1/2 to angular momentum permit to assign the orbital from which the proton is emitted. As protons are detected with high efficiency, proton emitters are used to identify nuclei in Recoil Decay Tagging (RDT). The observation of protons from 151 Lu & 147 Tm fixed the proton drip-line of this region (GSI, 1981)

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio 2007 Proton emitters known today Known proton emitters Proton emitting from isomers and g.s. Fine structure in proton emitters In the 90´s explosion of information on proton radioactivity Theoretical models are able to reproduce the systematic of p-decay spectroscopic factors for a wide range of spherical nuclei sensitive test of Shell Model at the edge of stability p-emission from highly deformed nuclei has been observed and decay rates explained assuming Nilsson states

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio 2007 Direct two proton radioactivity Predicted in 1960 [Vitali & Goldanskii, Nucl. Phys. 19 (60)482;27(61)648] General property of light nuclei with even number of protons ( Z=10 to Z=50 ) close to the proton instability limit Origin pairing force Easier to eject a pair of protons from a nucleus than to break the pair apart If B p,odd <0 B p,even =E pair +B p,odd =E pair -|B p,odd | B p,even >0 2p-radioactivity 2p-radioactivity is a 3 body problem Penetration through Coulomb barrier lead to strong energy and angular correlations Interesting because the correlation between emitted protons can give yield information on the nature of their transition within and outside the nucleus Z=2m+2Z=2m+1Z=2m E pp =|B p,odd |-B p,even B p,odd B p,even Pairing 2p SpSp S 2p Known: 6 Be 2p + p + 5 Li ( = 1.5 MeV) p + How does it decay?

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio 2007 Direct Two-Proton Emission Candidates The discovery of direct g.s. 2p-decay has been hampered by 1-the stringent energetic requirement (S p >0, S 2p <0) 2-need to detect low energy protons (in light nuclei, coulomb barrier low) Use of the Garvey and Kelson mass formula for mirror nuclei [Phys. Rev. Lett 16 (1966) 197] Assumption: charge symmetry of nuclear forces Independent particle picture Accuracy in M 200 keV Correction by Thomas Ehrmann Shift effect S (negative separation energy for the unbound individual particle state). S = (0.28(9))xS (where S is Sp>0 or S 2p < 0) Comay, Kelson &Zidon [ADNDT 39(1988)251] Candidates for 2p radioactivity S p S 2p S 2p + ST 1/2 (ms) 22 Si (?)6(3) 31 Ar (7) 39 Ti (7) 42 Cr Fe Ni Zn

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio 2007 Giovinazzo et al., PRL 89 (2002)

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio 2007 Giovinazzo et.al. Phys Rev Lett. 89(2002)102501

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio 2007 Status of 2p-radiaoctivity Agreement with 3-body model for p-wave emission 45 Fe Blank et al., PRL 94 (2005) Giovinazzo et al., PRL 89 (2002) (6) % 2p E 2p = 1.154(16) MeV 87(13) % 2p E 2p = 1.48(2) MeV 54 Zn Next Steps: Search for new two-proton emitters 48 Ni, 59 Ge ….. Detailed study of the decay process Measurement of proton-proton correlation: p-p angle Individual proton energies Modelling of the 2p resonance GANIL Fragmentation reactions 58 Ni-beam 45 Fe 54 Zn Dossat, PRC, submitted

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio 2007 An Exotic Nucleus: Z=18, N=13 Q = 18.5 MeV

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio 2007 Emisión retardada de 2-protones Predicho en 1980 [Goldanskii, JETP Lett. 32 (1980) 554] 3 modos de desintegración: Emision secuencial. E1, E2 ind. Picos, E2 ensanchado por retroceso Emisión casi isótropica Emision di-protonica E1 E2, anchos Gran correlacion angular Emision democratica E1 E2, anchos Cierta correlacion angular

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio 2007 Experimento 1995

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio 2007 Experimento 1997 Yield2 atom/s Solid angle % 1p 23.7 % 2p 5.2 % 3p 1.3 %

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio 2007 IAS 2p/ 1p (IAS) 9 31 the dripline: 18p + 13n Unique Spectroscopic Information Q 2p E IAS = 12322(2)(50) keV Q EC = E IAS + Ec - np Ec =7045 keV Q EC = 18490(110) keV f(E IAS )t IAS = 6145(4) s / [B(F) + B(GT)] b.r.(IAS) = T 1/2 / t IAS B(F) = [T(T+1)-T zi T zf ] if = 5 Expected b.r. (IAS) = 4.35(31)% Experimentally: b.r. (IAS) = 4.25(30) %

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio delayed 2p emission from 31 Ar 1

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio Ar -2p emitter Decay of IAS through 2p emission Diagonal from decays via single intermediate state from many initial states fed in beta-decay 1p- spectrum. 2p-spectrum

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio 2007 Gamow-Teller 2p-transition Kinematics of sequential emission 2 He branch present at some level ? 1st emitted 2nd emitted 30 S* 29 P Isospin allowed transitions increasing # of intermediate states possible

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio 2007 Surprise at the neutron drip line 1985, First experiments with radioactive nuclear beams, Berkeley (USA) Tanihata R( 11 Li) = 3.30(24) fm 11 Li Be, C and Al 6 Li 7 Li 8 Li 9 Li 11 Li ¿Why is the mass radius so large? Deuterio Tanihata, 1985

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio 2007 Experimental Studies at the drip line Spins Moments Spins Moments Elastic Scattering Elastic Scattering Momentum Distributions Momentum Distributions Reaction Cross Sections Reaction Cross Sections Beta Decay Beta Decay Unbound Nuclei Unbound Nuclei Masses

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio 2007 Beta decay of an exotic nuclei 10 Be+n Be+2n Be 20.6 Energías (MeV) 3/2 - 8 Li+t Even a neutron rich - nuclei emit charged particles! 2 +3n T 1/2 = 8 ms Li+d p d 9 Li 11 Be ½+½ ½-½-

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio 2007 Beta-delayed deuterons E d (keV) Intensity (decay -1 MeV -1 ) M.J.G. Borge et al., Nucl. Phys. A560 (1993) 664 F.C. Baker, Phys. Lett. B 322 (1994) 17 D. Baye et al., Prog. Th. Phys. 91 (1994) 271 M.V. Zhukov et al., PRC47 (1993) 2937 Q d = – S 2n MeV 6 He 6 Li +d Anthony et al., PRC 65 (2002) Exploring w.f. 10 fm

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio Li, gamma rays 11 Be 320 keV M.J.G. Borge et al., PRC55 (97) R8 N. Aoi et al., NPA616 (97) 181c D. Morrisey et al., NPA627 (97) 222 Q = MeV, T 1/2 = 8.2 ms b(320) = 6.3(6) % log ft = 5.73 (1s 1/2 ) 2 /(0p 1/2 ) 2 ~1 ½-½- ½+½+

Grupo de Física Nuclear Experimental IEMIEM CSIC Curso de Doctorado Estructura Nuclear M.J.G. Borge, IEM, CSIC 8 Junio Li (284 MeV/u) + C 9 Li + GSI 10 Li 9 Li n2n2 (1s 1/2 ) 2 = 45(10) % in the 11 Li g.s Single-particle momentum distributions, Hankel functions H. Simon et al., PRL 83 (1999) 496 n1n1