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

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

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

Data analysis 1)Particle Id.  calibrated. 3)Implantation profile in DSSD 4)Timing  (either following  or HI) No need for half-life reconstruction online (not possible?). Online Online + half-life reconstruction. Offline

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  : TAC (1µs) 6) Scalers for Si & Ge 3 ADC 1 TDC 2 U2M Everything in D4 => Noise + Number of chan.

Logic (General) Si 500µ Single Sided Si 1500µ Double Sided Si 1000µ Single Sided *) Implant.: 1.5GeV Preamp. 2mV/MeV =>Provides E ion + Y ion + saturation on X i  E. 1.5GeV Rear face (Trig1) *)  Up to 1MeV Max Reset Preamp. 200mV/MeV =>Provides E e- + X  (Trig2) => Provides Y 

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

Nuclear Structure Towards 28 Ni 50 (Exp.) f 7/2 f 5/2 p 3/2 g 9/2 Z=28 N=40 N=50  Cu isotopes (N>40) : 1 proton outside Z=28 core interacting with g 9/2 neutrons Towards N=50  filling of the g 9/2 orbits 10 neutrons interacting with  fp orbitals S. Franchoo et al. PRL 81, 3100 (1998) Inversion of  f 5/2 -  p 3/2 states? Search for low lying states in 75,77 Cu. 75 Cu 77 Cu

Need of experimental evidences on the crossing of  f  /2 –  p 3/2 orbits Nuclear Structure Towards 28 Ni 50 (Theo.) Structure of Cu isotopes : Recent theoretical interest : Shell Model and Mean Field N. A. Smirnova et al., PRC69, (2004)A.F. Lisetskiy et al., PRC70, (2004) EPJA25, s01,95 (2005) SHELLSHELL MODELMODEL MEANMEAN FIELDFIELD T. Nikšić et al., PRC71 (2005) Depending on the model/approach crossing 3/2 - 1 – 5/2 - 1 in 73 Cu to 79 Cu…

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

Beam Time Request Structure of transmitted nuclei -  decay half-lives (New *, Improved ) -Isomeric states (T 1/2, J  ) - States fed via  -decay (J  ) Deduced level schemes using  -coincidences 21 UT’s required + 3 UT’s for identification & calibrations Total : 24 UT’s   -   Isom 75 Cu Cu Cu Ni Ni Ni Mn 67 Mn 68 Mn 68 Fe 69 Fe 70 Fe 69 Co 70 Co 71 Co 72 Co 71 Ni 72 Ni 73 Ni 74 Ni 73 Co 74 Co 75 Ni 76 Ni 77 Ni 67 Fe 73 Cu 74 Cu 75 Cu 76 Cu 77 Cu 78 Cu 79 Cu 78 Ni 81 Zn 77 Zn 78 Zn 79 Zn 80 Zn 82 Ga 80 Ga 81 Ga  Z=28  N=50 71 Fe ≥ pps pps pps pps Rates   ~85% (measured)   500keV (simulated)  feeding 5% (assumed from systematic) * * Lower limits

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

Isomer in 77 Cu? HFB-D1S + blocking : Cu isotopes 3/2- 5/2- Experiment 3/2- 5/2- Theory ? A 83

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

Experimental details EE E Implantation Strip Correlation Strips 1-  E-E +  E-TOF : Id 2- Spatial correlations  -Ion: bckgd subtraction 3- Time correlations :  line assignment 