beta decay around 64 cr ganil, march 25 th 2010 62 v 63 v 64 v 60 v 61 v 63 cr 64 cr 65 cr 61 cr 62...
DESCRIPTION
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.TRANSCRIPT
Beta decay around 64Cr
GANIL, March 25th 2010
62V 63V 64V60V 61V
63Cr 64Cr 65Cr61Cr 62Cr60Cr
64Mn 65Mn 66Mn
65Fe 67Fe 1) 2+ in 64Cr
N=40
2) Isomers in 64,66Mn
66Fe
3) 0+2 in 66Fe and isomers in 63,65Cr.
Collectivity in neutron rich N=40 nuclei
decay 64V->64Cr.64,66mMn produced via fragmentation: decay via 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?
Experimental method
D2D1
86Kr58Mev.u
4Ae
58Ni : 105m
C
1) Production : 86Kr + 58Ni (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-detectors4) Detection - : DSSD + Ge detectors
Flight Path : From Lise target to 1st focal point 200ns (T1/2~70ns)
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
62V 63V 64V60V 61V
63Cr 64Cr 65Cr61Cr 62Cr60Cr
64Mn 65Mn 66Mn
65Fe 67Fe
N=40
66Fe 3x10-4pps
1x10-2pps
2x10-1pps
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 ’s).
Tuning of Lise MUST be quick.
Data analysis
1) Particle Id.2) calibrated.3) Implantation profile in DSSD4) 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 ADC1 TDC2 U2M
Everything in D4 => Noise + Number of chan.
Logic (General)
Si 500µSingle Sided
Si 1500µDouble Sided
Si 1000µSingle Sided
*) Implant.: 1.5GeV Preamp. 2mV/MeV
=>Provides Eion + Yion+ saturation on Xi
E. 1.5GeVRear face(Trig1)
*) Up to 1MeV MaxReset Preamp. 200mV/MeV
=>Provides Ee- + X
(Trig2)
=> Provides Y => Provides Y
Logic (Electronic)Triggers: E + DSSD
Read E & time of Ge for each trigger.
Electronics for HI: standard.
Electronics for
1500µReset pream (14MeV)Reseting time: 20µs.
200mV/MeVSpectr. Ampli
Caen (16 Chan)Out E ADC
OutE *10
Linear fifoSignal inversion?
Low Thresh. Discri.
500µ1000µ
Ge
ADC
Nuclear Structure Towards 28Ni50 (Exp.)
f7/2
f5/2p3/2
g9/2
Z=28
N=40
N=50
Cu isotopes (N>40) :1 proton outside Z=28 core interacting with g9/2 neutrons
Towards N=50 filling of the g9/2 orbits10 neutrons interacting with fp orbitals
S. Franchoo et al. PRL 81, 3100 (1998)
Inversion of f5/2-p3/2 states?
Search for low lying states in 75,77Cu.
75Cu 77Cu
Need of experimental evidences on the crossing of f/2 – p3/2 orbits
Nuclear Structure Towards 28Ni50 (Theo.)Structure of Cu isotopes :
Recent theoretical interest : Shell Model and Mean Field
N. A. Smirnova et al., PRC69, 044306 (2004) A.F. Lisetskiy et al., PRC70, 044314 (2004)EPJA25, s01,95 (2005)
SHELL
MODEL
MEAN
FIELD
T. Nikšić et al., PRC71 (2005) 014308
Depending on the model/approachcrossing 3/2-
1 – 5/2-1 in 73Cu to 79Cu…
Nuclear Structure Towards 28Ni50
> 1s< 1s< 200ns
66Mn 67Mn 68Mn
68Fe 69Fe 70Fe
69Co 70Co 71Co 72Co
71Ni 72Ni 73Ni 74Ni73Co
67Fe
73Cu 74Cu 75Cu 76Cu 77Cu 78Cu 79Cu
81Zn77Zn 78Zn 79Zn 80Zn
82Ga80Ga 81Ga
Z=28
N=5071Fe
72Cu70Ni69Ni
79Ga78GaPossibleisomer
74Co
75Ni 76Ni 77Ni 78Ni
T1/2
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 thesis@GANIL (1999)86Kr on Ni target
75Cu :• Isomeric states• -spectroscopy only• No spin assignments
Coun
ts
E
75Cu
Triggered other studies : -decay or isomers Phys. Rev. C 68 (2003) 044304 – -decay 72Co
Eur. Phys. Journ. A 20 (2004) 109 – Isom. 76Ni Eur. Phys. Journ. A 22 (2004) 455 – -decay 71,73Co
Publi. :Phys. Lett. B 476 (2000) 213 – 78Zn
Beam Time Request
Structure of transmitted nuclei
- decay half-lives (New *, Improved )-Isomeric states (T1/2, 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
75Cu 1115 110 67576Cu 1570 155 95077Cu 890 90 61075Ni 360 36 21576Ni 76 7 4577Ni 9 - 5
66Mn 67Mn 68Mn
68Fe 69Fe 70Fe
69Co 70Co 71Co 72Co
71Ni 72Ni 73Ni 74Ni
73Co 74Co
75Ni76Ni 77Ni
67Fe
73Cu 74Cu 75Cu 76Cu 77Cu 78Cu 79Cu
78Ni
81Zn77Zn 78Zn 79Zn 80Zn
82Ga80Ga 81Ga
Z=28
N=50
71Fe
≥3.10-1 pps
1-3.10-1 pps
10-2-10-1 pps
10-3-10-2 pps
Rates
~85% (measured)~10% @ 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 77Cu?
HFB-D1S + blocking : Cu isotopes
3/2-5/2-
Experiment3/2-5/2-
Theory
?
69 71 73 75 77 79 81 A83
Gamma efficiency
Geant4 Simulations [B. Rossé]
Energy [keV]
Efficiency [%]
10
5
20
Config. Daugas et al.2 Coax + 1 Clover + 1LEPS
Proposed Config.3 Coax + 1LEPS + 00 Coax
Enhanced efficiency up to 150keV.Expected efficiency below 150keV : at least same as Daugas et al.
Experimental details
E
E
Implantation Strip
Correlation Strips
1- E-E + E-TOF : Id
2- Spatial correlations -Ion: bckgd subtraction
3- Time correlations : line assignment