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Beta decay around 64 Cr

Beta decay around 64 Cr. 1) 2 + in 64 Cr. 2) Isomers in 64,66 Mn. 3) 0 + 2 in 66 Fe and isomers in 63,65 Cr. Collectivity in neutron rich N=40 nuclei. 65 Fe. 66 Fe. 67 Fe. 64 Mn. 65 Mn. 66 Mn. 61 Cr. 62 Cr. 63 Cr. 64 Cr. 60 Cr. 65 Cr. 60 V. 61 V. 62 V. 63 V. 64 V. N=40.

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Beta decay around 64 Cr

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  1. Beta decay around 64Cr 1) 2+ in 64Cr 2) Isomers in 64,66Mn 3) 0+2 in 66Fe and isomers in 63,65Cr. Collectivity in neutron rich N=40 nuclei 65Fe 66Fe 67Fe 64Mn 65Mn 66Mn 61Cr 62Cr 63Cr 64Cr 60Cr 65Cr 60V 61V 62V 63V 64V N=40 • decay 64V->64Cr. 64,66mMn produced via fragmentation: decay viag and e-. If low lying 0+2 state=> might be isomer. Isomers present in all N=39 and 41 isotones (from Z=28), why not observed at Z=24? GANIL, March 25th 2010

  2. Experimental method Be : 200 mm 58Ni : 105mm D2 D1 DE ; Si Caviar 86Kr 58Mev.u 4mAe C E; DSSD 2) Selection : LISE Spectro. + Slits + Wedge 3) Identification : Br (caviar) + DE-E + DE-ToF 4 Ge-detectors 4) Detectionb-g: DSSD + Ge detectors Flight Path : From Lise target to 1st focal point  200ns (T1/2~70ns) Detection : 1) g-decay from isomeric states (produced via fragmentation) 2) b-decay of the implanted ions (position correlations in the DSSD) 3) g-decay (prompt/delayed) following the b-decay 1) Production : 86Kr + 58Ni (Lise target Pos.)

  3. Production rates 65Fe 66Fe 67Fe 3x10-4pps 64Mn 65Mn 66Mn 1x10-2pps 61Cr 62Cr 63Cr 64Cr 60Cr 65Cr 60V 61V 62V 63V 64V 2x10-1pps N=40 Low stat. Experiment: Need for as clean as possible data (bckgd issue). Few counts per second expected (<10) => Difficulty to make sure tuning is ok. *) 1st run on 64Mn. (up to 10-20pps)? *) Then move on 64V (20Ut’s = 230 counts => about 10 g’s). Tuning of Lise MUST be quick.

  4. Data analysis Online • Particle Id. • g calibrated. • Implantation profile in DSSD • Timing g (either following b or HI) • No need for half-life reconstruction online (not possible?). Offline Online + half-life reconstruction.

  5. Acq electronics 1) Caviar 2) Si detectors: 64 Strips => 2ADCs 3) 4 Ge (among which 1 Clover) => 7 Chan. 4) Timing e-: Centrum + SMC (beam on/off) 5) Timing g: TAC (1µs) 6) Scalers for Si & Ge 3 ADC 1 TDC 2 U2M Everything in D4 => Noise + Number of chan.

  6. Logic (General) *) b Up to 1MeV Max Reset Preamp. 200mV/MeV =>Provides Ee- + Xb (Trig2) Si 500µ Single Sided Si 1500µ Double Sided Si 1000µ Single Sided DE. 1.5GeV Rear face (Trig1) *) Implant.: 1.5GeV Preamp. 2mV/MeV =>Provides Eion + Yion + saturation on Xi => Provides Yb => Provides Yb

  7. Logic (Electronic) 500µ 1000µ Ge 1500µ Reset pream (14MeV) Reseting time: 20µs. 200mV/MeV Spectr. Ampli Caen (16 Chan) ADC ADC Out E Out E *10 Signal inversion? Linear fifo S Low Thresh. Discri. Triggers: DE + Sb DSSD Read E & time of Ge for each trigger. Electronics for HI: standard. Electronics for b:

  8. Nuclear Structure Towards 28Ni50 (Exp.) N=50 g9/2 N=40 f5/2 p3/2 S. Franchoo et al. PRL 81, 3100 (1998) Z=28 f7/2 Inversion ofpf5/2-pp3/2 states? p n Search for low lying states in 75,77Cu. 75Cu 77Cu Towards N=50  filling of the g9/2 orbits 10 neutronsinteracting withpfp orbitals Cu isotopes (N>40) : 1 proton outside Z=28 core interacting with g9/2 neutrons

  9. Nuclear Structure Towards 28Ni50 (Theo.) M O D E L S H E L L N. A. Smirnova et al., PRC69, 044306 (2004) A.F. Lisetskiy et al., PRC70, 044314 (2004) EPJA25, s01,95 (2005) T. Nikšić et al., PRC71 (2005) 014308 F I E L D M E A N Structure of Cu isotopes : Recent theoretical interest : Shell Model and Mean Field Depending on the model/approach crossing 3/2-1 – 5/2-1 in 73Cu to 79Cu… Need of experimental evidences on the crossing of pf5/2 – pp3/2 orbits

  10. Nuclear Structure Towards 28Ni50 J.-M. Daugas PhD thesis@GANIL (1999) 86Kr on Ni target 75Cu Counts • 75Cu : • Isomeric states • g-spectroscopy only • No spin assignments Proposed experiment : bg-spectro. E Publi. : Phys. Lett. B 476 (2000) 213 – 78Zn • As compared to Daugas et al. • Tuned for more exotic species • Beam twice more intense • Improved g-efficiency • - b+gdecay selection rules • - Sensitive to isomeric states • - Population of 5/2- and 7/2- states (among others) Triggered other studies : b-decay or isomers Phys. Rev. C 68 (2003) 044304 – b-decay 72Co Eur. Phys. Journ. A 20 (2004) 109 – Isom. 76Ni Eur. Phys. Journ. A 22 (2004) 455 – b-decay 71,73Co T1/2 > 1ms Possible isomer Experimental difficulties : 1) Numerous isomeric states 2)Low production rates 80Ga 81Ga 82Ga 78Ga 79Ga < 1ms 77Zn 78Zn 79Zn 80Zn 81Zn < 200ns 73Cu 74Cu 75Cu 76Cu 77Cu 78Cu 79Cu 72Cu 71Ni 72Ni 73Ni 74Ni 75Ni 76Ni 77Ni 78Ni 69Ni 70Ni  Z=28  73Co 74Co 69Co 70Co 71Co 72Co N=50 67Fe 68Fe 69Fe 70Fe 71Fe 66Mn 67Mn 68Mn

  11. Beam Time Request 80Ga 81Ga 82Ga Rates 77Zn 78Zn 79Zn 80Zn 81Zn 73Cu 74Cu 75Cu 76Cu 77Cu 78Cu 79Cu 71Ni 72Ni 73Ni 74Ni 75Ni 76Ni 77Ni 78Ni  Z=28  73Co 74Co 69Co 70Co 71Co 72Co N=50 67Fe 68Fe 69Fe 70Fe 71Fe ≥3.10-1 pps 66Mn 67Mn 68Mn 1-3.10-1 pps 10-2-10-1 pps 10-3-10-2 pps * eb~85% (measured) eg~10% @ 500keV (simulated) b feeding 5% (assumed from systematic) * Lower limits • Structure of transmitted nuclei • - b decay half-lives (New *, Improved ) • Isomeric states (T1/2, Jp) • - States fed via b-decay (Jp) • Deduced level schemes using gg-coincidences • 21 UT’s required • + • 3 UT’s for identification & calibrations Total : 24 UT’s

  12. Spectroscopy of Cu isotopes b-decay of Ni isotopes Direct feeding of 5/2- and 7/2- states + side feeding from higher lying states Observed g-transitions ~ 0.5 – 1.0 MeV

  13. Isomer in 77Cu? Theory 3/2- 5/2- HFB-D1S + blocking : Cu isotopes Experiment 3/2- 5/2- ? 73 75 77 79 81 83 69 71 A

  14. Gamma efficiency Efficiency [%] Energy [keV] Geant4 Simulations [B. Rossé] 20 Config. Daugas et al. 2 Coax + 1 Clover + 1LEPS 10 Proposed Config. 3 Coax + 1LEPS + 00 Coax 5 Enhanced efficiency up to 150keV. Expected efficiency below 150keV : at least same as Daugas et al.

  15. Experimental details Implantation Strip g b Correlation Strips E 1- DE-E + DE-TOF : Id 2- Spatial correlations b-Ion: bckgd subtraction DE 3- Time correlations : g line assignment

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