Presentation on theme: "First Results from the Stopped RISING Campaign at GSI: The Mapping of Isomeric Decays in Highly Exotic Nuclei Paddy Regan (for the Stopped Beam Rising."— Presentation transcript:
First Results from the Stopped RISING Campaign at GSI: The Mapping of Isomeric Decays in Highly Exotic Nuclei Paddy Regan (for the Stopped Beam Rising Collaboration) Dept. of Physics, University of Surrey Guildford, Surrey, GU2 7XH, UK email@example.com
RISING = Rare ISotope INvestigations at GSI 3 major ‘campaigns’ so far using 15 EUROBALL Clover germanium dets. 1) ‘Fast’ (in-beam) Campaign 2) gRISING Campaign 3) ‘Stopped’ (isomer) Campaign
primary beam Pb @ 1GeV/u Production target Central focus, S2 Final focus, S4 E(Z 2 ) catcher degrader dipole, B scint MW=x,y scint (veto) Use FRS@GSI or LISE3@GANIL to ID nuclei. Transport some in isomeric states (TOF~ x00ns). Stop and correlate isomeric decays with nuclei id. eg. R. Grzywacz et al. Phys. Rev. C55 (1997) p1126 ⇨ LISE C. Chandler et al. Phys. Rev. C61 (2000) 044309 ⇨ LISE M. Pfützner et al. Phys. Lett. B444 (1998) p32 ⇨ FRS Zs. Podolyak et al. Phys. Lett. B491 (2000) p225 ⇨ FRS M. Pfützner et al. Phys Rev. C65 (2002) 064604 ⇨ FRS M. Caamano et al., Eur.Phys. J. A23 (2005) p201 ⇨ FRS In-Flight Technique Using Projectile Fragmentation
Produce many exotic nuclei: Stopped them to study both 1) Isomer decays (10ns-1ms) 2) Beta decays (20ms - 10s) 73 Kr 82 Nb 92 Mo@ GANIL Blank and Regan, Physics World Jan. 2000
( g 9/2 ) -2 I=8 + + g 9/2 ) -2 I=8 + + ( g 9/2 ) -2,4 I=14 + g 9/2 ) -2,4 I=14 + Can use known isomers with 100% cascade decays to give detector response over full energy range…. S. Pietri et al., Nucl. Inst. Meth. B. in press. (2007)
S. Pietri et al., in press NIM B (2007) High granularity of RISING reduces ‘prompt flash’ problems…. 7 / 105… DGF timing of flash, comparable to former ‘analog’ timing.
S. Pietri et al., in press, Acta Phys. Pol. B (2007)
Physics aims and regions for the Stopped RISING Campaigns (2006)
What is an isomer ? Metastable (long-lived) nuclear excited state. ‘Long-lived’ could mean ~10 -19 seconds, shape isomers in -cluster resonances or ~10 15 years 180 Ta 9 - ->1 + decay. Why/when do you get isomers? (i) large change in spin (‘spin-trap’) (ii) small transition energy between states (seniority isomers) (iii) dramatic change in structure/shape (fission isomers) and/or underlying symmetry (K-isomers) What do isomers tell you ? Isomers occur due to single particle structure. Transitions are hindered between states with very different structures (note, this is not case for seniority isomers).
From P.M.Walker and G.D.Dracoulis, Physics World Feb. 1994
decay to states in 208 Pb. 212 Po, high-spin - decaying yrast trap. (also proton decaying isomers, e.g, 53 Co PLB33 (1970) 281ff. E0 (ec) decay 74 Kr, shape isomer High-spin, yrast-trap (E3) in 212 Fr K-isomer in 178 Hf
Main Aim: Observe I =10 + isomer in 54 Ni (Isomer already known in mirror, 54 Fe) Fragmentation of 600 MeV/A 58 Ni beam (D.Rudolph et al.)
Z. Janas et al., Phys. Rev. Lett. 82 (1999) 295 N=Z crossed proton drip line around A~80
T=0, 1 Competition in Deformed N=Z odd-odd Nuclei Use projectile fragmentation to populate exotic N=Z=41,43 nuclei 82 Nb, 86 Tc. Measure gammas from isomeric decays. Construct (partial) decay schemes Look for energy competition between T=1 (I =0 + ) and T=0 (I =1 + ?) lowest states.
Structure of Odd-Odd N=Z Nuclei Even-even core plus one valence proton and one valence neutron in equivalent orbits Neutron-Proton PairingT=1 and T=0Residual InteractionsGround state angular momentum can be 0 +, J min or J max
New Data point ? T=1: I =0 + T=0 : I =1 + or (2j) + E (T=0 – T=1) (keV)
Number of levels below 1 MeV in odd-odd nuclei D.G. Jenkins, et.al. Phys. Rev. C65, 064307 (2002) T=1 pairing gap ? T=0 pairing…. Low-lying I =1 + states expected… is there any evidence ? ‘yrastness’ problem in well deformed systems…
Match energies to Isobaric Analogue States in the Tz=1/2 isobars. Level Structures
Match energies to Isobaric Analogue States in the Tz=1/2 isobars. Level Structures Calculation by H. Grawe (GSI) only using p 1/2 and g 9/2. Full Calculation could (should) also include: f 5/2, p 3/2, d 5/2, g 7/2.
Energetically matched IAS PSM calculation Large Isomeric Ratio (~70%) But… The lifetime is longer than expected: τ exp = 133 (20) ns W.E. = 0.00146 ns Axially deformed: K is a good quantum number 124keV M1, ΔK=5, F ν = 10.8 K isomerism on the N=Z line at the proton dripline! The Structure of 82 Nb
Projected Shell Model Calculations by Yang Sun (University of Notre Dame)
86 Tc - Multipolarity from Intensity Balance 86 Tc, 81keV: 3.49 (80) 82 Nb, 124keV: 0.33 (30) Use Intensity Balance to determine Conversion Coefficient: I Tot =I (1+ Tot ) ‘missing’ intensity due to IC.
The Structure of 86 Tc Energetically matched to IAS Use Intensity balance to measure α = E2 6 + from 5 / 2 + 7 / 2  Softer shape, moving into transitional region. S.L.Tabor and G.Z.Soloman, J.Phys.G, 25, p763 (1999)
Summary Experimental data from 2006 passive stopper experiments –N~Z isomers, isospin symmetry/pairing studies around 56 Ni (Dirk Rudolph) and highly deformed A~80 regions. –N~126, high spins ( 148 Tb), K-isomers ( 190 W)…(Zsolt Podolyak) –Reaction mechanism studies of ‘cold knockout’ to ( h 11/2 ) -2, I =10 + seniority isomers (Jeff Tostevin et al.,) –Neutron-rich ~ 132 Sn nuclei with 136 Xe fragmentation (Andrea Jungclaus) and 238 U projectile fission (Magda Gorska/Marek Pfuztner) under analysis. r-process path isomers –A~110 fission fragment isomers (Alison Bruce) ‘Active Stopper’ campaign (2007) –3 x 5cm x 5cm DSSSD: correlated -delayed gammas… –N~126 neutron-rich to 170 Dy valence max. (March 2007)
First Results from the Stopped RISING Campaign at GSI: The Mapping of Isomeric Decays in Highly Exotic Nuclei P.H.Regan 1, A.B.Garnsworthy 1,2, S.J.Steer 1, S.Pietri 1, Zs.Podolyák 1, D.Rudolph 3, M.Górska 4, L.Caceres 4,5, E.Werner- Malento 4,6, J.Gerl 4, H.J.Wollersheim 4, F.Becker 4, P.Bednarczyk 4, P.D.Doornenbal 4, H.Geissel 4, H. Grawe 4, J.Grębosz 4,7, R.Hoischen 3, A.Kelic 4, I.Kojouharov 4, N.Kurz 4, F.Montes 4, W.Prokopowicz 4, T.Saito 4, H.Schaffner 4, S.Tashenov 4, A.Heinz 2, M.Pfützner 6, T.Kurtukian-Nieto 8, G.Benzoni 9, M.Hellström 2, A.Jungclaus 5, L.-L.Andersson 3, L.Atanasova 10, D.L.Balabanski 11, M.A.Bentley 12, B.Blank 13, A.Blazhev 14, C.Brandau 1,4, J.Brown 12, A.M.Bruce 15, F.Camera 9, W.N.Catford 1, I.J.Cullen 1, Zs.Dombradi 16, E.Estevez 8, C.Fahlander 3, W.Gelletly 1, G.Ilie 14, E.K.Johansson 3, J.Jolie 14, G.A.Jones 1, M.Kmiecik 7, F.G.Kondev 17, S. Lalkovski 10,15, Z.Liu 1, A.Maj 7, S.Myalski 7, S.Schwertel 18, T.Shizuma 1,19, A.J.Simons 1, P.M.Walker 1, O. Wieland 9 1 Dept. of Physics, University of Surrey, Guildford, GU2 7XH, UK 2 WNSL, Yale University, New Haven, CT 06520-8124, USA 3 Department of Physics, Lund University, S-22100 Lund, Sweden 4 GSI, Planckstrasse 1, D-64291, Darmstadt, Germany 5 Departamento de Fisica Teórica, Universidad Autonoma de Madrid, E-28049, Madrid, Spain 6 IEP Warsaw University, Hoźa 69, PL-00-681 7 The Henryk Niewodniczański Institute of NuclearPhysics, PL-31-342, Kraków, Poland 8 Universidad de Santiago de Compostela, E-15706, Santiago de Compostela, Spain 9 INFN, Universitá degli Studi di Milano, I-20133, Milano, Italy 10 Faculty of Physics, University of Sofia, BG-1164, Bulgaria & The Institute for Nuclear Research, Bulgarian Academy of Science, BG-1784, Sofia, Bulgaria 11 Dipartimento di Fisica, Universit ´a di Camerino, I-62032, Italy 12 Dept. of Physics, University of York, Heslington, York, Y01 5DD, UK 13 CENBG, le Haut Vigneau, Bordeaux, F-33175, Gradignan Cedex, France 14 IKP, Universit¨at zu Köln, D-50937, Köln, Germany 15 School of Engineering, University of Brighton, Brighton, BN2 4GJ, UK 16 Institute for Nuclear Research, Debrecen, H-4001, Hungary 17 Nuclear Engineering Division, Argonne National Laboratory, Argonne IL-60439, USA 18 Physik Department E12, Technische Universität München, Garching, Germany 19 Japan Atomic Energy Agency, Kyoto, 619-0215, Japan