Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)1 Decay EURISOL María José García Borge Instituto de Estructura de la Materia, CSIC

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)2 Overview Halo structure Disappearance of magic numbers Exotic decays Asymmtries Order to Chaos Near the drip lines Desintegration  + -EC Desintegration  - Desintegration  Fission

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)3 Decay properties of exotic nuclei Selection rules: Fermi:  T=   J=0 ;  f =  i Gamow-Teller:  T=0±1;  J=0±1 ;  f =  i    + (C.E.) emission Reduced transition probability:  Global properties Short half-lives (  ms) 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 E,  Level density Spin, Isospin  -decay properties

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)4 Production Methods Pure beam High magnetic resolving power Full isotopic chain Very good beam quality Low energy  Point like sources  Short separation times (identification of very short T 1/2 species)  Direct determination of B.R.  High detection efficiency (implantation of the source)  Simultaneous measurement of many nuclei

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)5 Super-conducting solenoid B=3.5 Tesla State-of Art  p spectrum (  = 4 ISOL-Facilities 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 (Björn’s Talk)  Isospin mixing in Fermi decays  Configuration mixing  Level interferences  Spin assignment  Excitation energies Adelberger & García, Hyp. Int 129 (2000) 237 Bhattacharya & García in preparation

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)6 Development of Targets Studies possible due to the development of the right target VC-target CaO-target Equivalent setup And beam time ¡ Gain of a factor of 2400 in yield! 32 Ar

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)7 Fragmentation Facility /Two solutions Counts Energy (keV) Strong beta summing JC Thomas et al., Eur Phys J A 21 (2004) 419 Bhattacharya & García in preparation MSU 32 Ar GANIL

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)8 70 % of the decay PRC72 (2005) T 1/2 and E 2p compatible with Sequential & direct decay PRC76 (2007) R MSU PRL99 (2007) Miernik, Pfützner et al. Direct decay First Measurement of p-p correlation in 2p-radioactivity 2002

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)9 Transition from order to Chaos Very low Z  Broad States R-Matrix description: E,  Low Z  Narrow States Direct structure information Middle Z  High Density Narrow States Fluctuations  Porter Thomas Distribution

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)10 B.Jonson & K. Riisager, NPA693 (2001) 77 Beta delayed particle emitters Halo structure Disappearance of magic numbers Neutron Rich Nuclei

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)11 The Survival of Magic Numbers Number of Neutrons Number of Protons New Magic Number No Magic In discussion The shell structure and the associated gaps are different far from stability. Existence/survival of Magic Numbers depends on 1.The size of the gap 2.Structure of mean field near Fermi level (correlations np-nh The disappearance of Magic Numbers was first observed in 31,32 Mg. In N=8, 11 Li the gain in correlation is due to Pairing In N=20 and N= 28 the gain in correlations 2p-2h is due to cuadrupole interaction. The play of correlations can be so subtle that if one adds 2p to 32 Mg we have the double magic nucleus 34 Si.

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)12  -decay of halo nuclei  Halo can affect beta decay in different ways; the spatial extension of the halo state reduces the overlap with the daughter states.  Affect one transition or globally the B GT i.e. in the case of 11 Li T 1/2 and  -B.R.  (P 1/2 ) 2 < 50 %  The halo nucleons decay almost independently from the core, i.e. decay to the continuum: i. e.  d  Assuming halo state can be factorised (Nilsson et al, Hyp. Int 129 (2000) 67) β  halo state> = β (  halo>  core>) = ( β  halo> )  core> +  halo>( β  core>)  Similar decay pattern of the 2n-halo nucleus and its core

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)13 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p d 9 Li 11 Be ½+½+  ½-½-

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)14 βd- spectrum of 6 He E d (keV) 1000 Anthony et al., PRC 65 (2002) Intensity (decay -1 MeV -1 ) M.J.G. Borge et al., Nucl. Phys. A560 (1993) 664 Exploring w.f.  10 fm Zhukov et al., PRC47 (1993) 2937 D. Baye et al., Prog. Th. Phys. 91 (1994) 271 F.C. Baker, Phys. Lett. B 322 (1994) 17 βd- 6 He 11Li Q  d (Z,A) = – S 2n (MeV); 6 He, 8 He, 11 Li, 14 Be, 17 B..etc 6 He 6 Li  +d 

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)15 βd- spectrum of 11 TRIUMF Raabe et al, PRL submitted βd- 11 Li Baye PRC79(06) Zhukov PRC 52 (95)2461 Implantation in a thin, highly segmented silicon detector ISOL beams: intense, pure, good energy definition  control on the implantation Full energy of ions is measured High efficiency Precise normalisation Identification of channels through implantation-decay-decay correlations in each pixel Decay to the continuum Favoured

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)16 Polarized radioactive beams: 11 TRIUMF Hirayama, Phys. Lett. B 611 (2005) MeV 11 Be 10 Be 11 Li MeV o Spin polarized 11 Li beam o ,  n,  n coincidences o Spin and parities of 7 levels in 11 Be assigned. 3/2

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)17 Can the halo state wave function of 11 Li be factorised?  Study of the decay of 11 Li and 9 Li with emphasis in the highly excited states Factorisation holds for the 2n-halo 14 Be and its core 12 Be 14 Be < 4 % to bound states P n = 101  4 % Feeding to 1 + > 38 %; logft  P 2n + 3P 3n = 0.8  = 8 % Dufour et al., PLB206 (1988) 195 Belbot et al.,PRC56 (1997) 3038 Bergmann et al NPA658 (1999) 129 ¿ Similar decay pattern of halo nuclei & core ?

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)18 A = 9 isobar Nyman et al., NPA 510 (1990) 189Mikolas et al., PRC 37 (1988) 766 F. Ajzenberg-Selove, NPA 490 (1988) 1 δ ≈ 3 δ=1.2±0.5 δ ≈ 0  = 3.4(7)  = 0.032(3) 5/  = (15)% NP A692(2001)427PLB576 (2003)55 (1/2,5/2) - (1/2) - 3/2 -

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)19 Charged particle emission in the 11 Li-decay  Current knowledge:  Four decay channels  Two states in 11 Be: 10.6 and 18.3 MeV.  Theory: SM predicts B(GT) strength distribution peaks between 15 and 20 MeV.  Experiment:  doppler broadening suggests significant (6%) feeding of states in this region. T. Suzuki and T. Otsuka, PRC 56(1997)847 H.O.U. Fynbo et al., NPA736 (2004)39 ?

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)20 Analysis techniques Energy & momentum conservation Momentum reconstruction Excitation energy of the 1-2 system: 6 He+  +n Deadlayer and carbon-foil energy losses corrected  -background subtraction: E front - E back  40 keV 11 Li Beam 60  g/cm 2

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)21 Charged Particle Coincidences M. Langevin et al., NPA 366(1981) 449 E D2 +E D4 D2D4 127º - 180º

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)22 Evidence of decay through the 7 He resonance 127º - 180º d  10 cm d  8.5 cm E 11 Be E’ 6 He+  +n Q1Q1 Q2Q He(gs) Contribution of a new decay channel. Contribution of a state at 16.3 MeV (  1 MeV) ). In agreement with theoretical expectations and previous  -experiment Preliminary

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)23 Universal set-up for spectroscopy studies 1.2m 3m 7 x BC501 Liquid scintillator 15 cm x 30 cm Gamma detection 3 Glover (4xHPGe)  Ge 2m Set up: Cube of DSSSD 4-6 Segmented HPGe TAS Good scheme for Neutron detection Fast Scintillators for T 1/2 Neutron Detection Need to be improved!!

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)24 EURISOL Production of new isotopes  New s.p. energies at large N/Z  T 1/2 and Pn-values of new isotopes Proton drip line and N=Z nuclei Spectroscopy beyond the drip line Proton-neutron pairing Isospin Symmetry Isospin Mixing GT and Fermi  -decays Order to chaos  p /   ratios Shell drip lines  Changes in the (effective) interaction  New “islands” of inversion N=Z

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)25 12 C from the  -decays of 12 N and 12 B , B N 1 + Decay mechanism ? Spin ? ++ -- 0 +, 1 +, 2 + levels selected

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)26  12 N/ 12 B Magnet p/d 12 N/ 12 B+X 12 C/ 11 B IGISOL All 3  events 3  ’s, Channel 8 Be(0 + ) excluded 91 (2003) Fynbo et al., PRL 91 (2003) Fynbo et al., NPA738 (2004) 59 Diget et al, NPA760 (2005) 3 Fynbo et al., Nature 433 (2005) , 2+0+,

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)27

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)28  E stage 1 µm E stage 400 ± 15 µm Charged Particle Identification: monolithic Si telescope 64 telescopes á 7 mm readout channels multiplexed to 1 ADC. The Solid Angle is 20% of the DSSSD but needs 4 times more electronic-channels! 256 detector elements á 9 mm 2 32 readout channels 64 ch: PA + TFA + CFD + A + trigger EE E To distinguish low energy charged particle: p, d, t, , 6 He

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)29 Determination of beta half-lives in complex background conditions Produced Implanted  The time sequence of fragment implantation and β detection are simulated according to the experimental conditions leaving two free parameters: the lifetimes and the efficiency  The code produces time-correlation spectra in forward- and backward-time direction.  Half-life determination of several new Re, 199,200 Os and 199,202 Ir isotopes relevant for the r-process.  With some modifications the method can be used for continuous beams. T. Kurtukian et al, NIM, submmitted. only pause Monte Carlo Simulations

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)30  = 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. 235  - : n → p + e - + np ft -  + : p → n + e + + E.C. : p + e - → n + np ft +  =  nuc +  SCC

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)31 Beta feeding to the MeV region in 9 Be Fit of the high energy peak gating on the 5 He(3/2 - ) channel MeV state  91±10% MeV state  9 % (e,p)-scattering on 9 Be assumed J = 7/2 Only the participation of the MeV state in 9 Be for the beta feeding is considered

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)32 Q  =20.4 MeV T 1/2 =8.5 ms 11 Be 10 Be+n 9 Be+2n 6 He+  +n 2  +3n 8 Li+t 9 Li+d 0.50 MeV 7.31 MeV 7.90 MeV 8.98 MeV MeV MeV  & n Charged particles (and n) Charged particles 11 Li 20.43/2 -  8 Li+t Li+d 17.9  -decay of 11 Li 97%  3%  0.3% 11 Be 01/ Be Be 7.33/2 - n   1/2 - 6 He+  +n  +3n 8.9 n 11 Be 01/2 +

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)33 11 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 Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)34 Exotic Radioactivities 2p-radioactivity (Z,N)  2p + (Z-2,N) 1p-radioactivity (Z,N)  p + (Z-1,N) Fe Zn Ni

Grupo de Física Nuclear Experimental IEMIEM CSIC Florence, January 2008 M.J.G. Borge, IEM, CSIC, Madrid (Spain)35 Halo nuclei Energy threshold effect Highlight by nuclear reactions Effects in beta decay 6 Li 7 Li 8 Li 9 Li 11 Li Tanihata, 1985