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Shell evolution in the neutron rich N=20, N=28 and Z=28 regions

Shell evolution in the neutron rich N=20, N=28 and Z=28 regions from measurements of moments and spins. Gerda Neyens, IKS, K.U. Leuven, Belgium. Belgian Research Initiative on eXotic nuclei. Layout Introduction: * motivation * methods to measure moments

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Shell evolution in the neutron rich N=20, N=28 and Z=28 regions

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  1. Shell evolution in the neutron rich N=20, N=28 and Z=28 regions from measurements of moments and spins Gerda Neyens, IKS, K.U. Leuven, Belgium Belgian Research Initiative on eXotic nuclei

  2. Layout • Introduction: * motivation • * methods to measure moments • Recent experiments at ISOL and fragmentation facilities • Highlights from Island of inversion • Highlights from the Cu chain, from N=28 to N=46 • Highlights from the Ga chain, from N=26 to N=50 • Highlights from the N=28 region below Ca: Cl isotopes • Conclusions

  3. Nuclear moments near magic shells  very sensitive to nuclear wave function ! Magnetic moment of odd-even, even-odd and odd-odd isotopes (m=g.I) near closed shells:  g-factor is determined by the orbital occupied by unpaired valence protons and/or neutrons - depends on spin and orbital g-factors for protons and neutrons (gsp, glp, gsn, gln) - depends on orbital momentum l and spinj of orbit occupied by unpaired nucleons  sign of g sensitive to the parity of the wave function !! - g-factor is not depending on the number of unpaired nucleons in an orbit: g(jn) = g(j) • Comparing experimental and calculated g-factors: • - confirm the proposed wave function • - in some cases: assign spin and/or parity • - test the shell model interaction and used model space 57Cu = 40Ca + 9p+8n 57Cu = 56Ni + p

  4. Nuclear moments near magic shells  very sensitive to nuclear wave function ! Quadrupole moments of odd-even, even-odd and odd-odd isotopes  Q-moment is determined by the spin j and the <r2> of the orbit occupied by unpaired valence protons - neutrons are not charged  but induce core polarization through p-n interaction - more sensitive to collectivity in the wave function • Comparing experimental and calculated Q-moments near closed shells: • - probing the proton-neutron interaction • - study the softness of a core as a function of N and/or Z • - study effects of core polarization • - study shape coexistence in nuclei • - confirm the proposed wave function • - test the shell model interaction 57Cu = 40Ca + 9p+8n 57Cu = 56Ni + p

  5. Methods to measure moments, radii, spin: lifetime dependence / production method dependence Lifetime of the isomeric excited state / isotope ground state 1 ps 1 ns 1 ms 1 ms 1s • Laser spectroscopy methods • magnetic moment, • quadrupole moment, • charge radius, • spin • g-TDPAD on aligned beams • g-factor • quadrupole moment • Transient field method • g-factor • b-NMR/NQR on polarized nuclei • Nuclear Magnetic/Quadrupole Resonance • g-factor • quadrupole moment Fragmentation Fusion-evaporation ISOL methods

  6. IN-SOURCE LASER SPECTROSCOPY at ISOL-facilities: magnetic moment (with sign) and charge radii E.g. at ISOLDE: Cu hyperfine structure (HFS): Proton beam Hot cavity Source with UCx target ionisation step 2P1/2 I=6 F2 2S1/2 I=1 F1 to ISOLDE detection set-ups 68Cu Pulsed Dye Lasers for two(three) -step resonant laser ionization • Measure magnetic moment • and isotope shift (charge radii) • of very exotic isotopes (rate > 1/s)  possible to separate nuclear isomeric state (6-) from its ground state (1+)  produce isomeric radioactive beams

  7. COLLINEAR LASER SPECTROSCOPY at ISOL-facilities: magnetic and quadrupole moments (with sign), radii, spin E.g. at ISOLDE: COLLAPS Cu hyperfine structure: ~Q,m 2P3/2 F’i ion deflector F2 2S1/2 ~m,I F1 LASER beam 68Cu, I=1- Photon counts Cu+ beam from ISOLDE • Measure spin, magnetic moment • quadrupole moment • and isotope shift (charge radii) • of exotic isotopes (rate > 104/s)

  8. 34Al g factor NMR-magnet b- detectors B RF-coil Implantation crystal Nuclear Magnetic/Quadrupole Resonance (b-NMR) at ISOL or fragmentation facility: g-factor or Q-moment (no sign) of ground startes Implant the polarized radioactive beam in a crystal (unequal population of m-levels) and apply static field B 2. Apply a radiofrequency field Brf, with frequency nrf If nrf = nL= g mNB/h population equalized (P=0) 3. Measure the asymmetry of emitted b-particles as function of the applied frequency m=2 m=1 I=2 Radioactive beam m=0 hnL m=-1 Zeeman splitting of nuclear quantum levels in static magnetic field B m=-2

  9. TDPAD-magnet det 1 det 2 B J Zor g XLAB t=0 t t=0 Time Differential Perturbed Angular Distribution (TDPAD) at fragmentation facility: g-factor or Q-moment (no sign) of ms isomeric states Implant the aligned radioactive beam in a crystal 2. Perturbation of spin-orientation due to static field B or electric field gradient in the crystal 3. Measure the anisotropy of isomeric g-decay as a function of time since implantation: use ion-g correlation method Period of R(t)  Larmor or quadrupole frequency

  10. Recent experiments The COLLAPS collaboration at CERN-ISOLDE Mainz – Heidelberg – Leuven – Manchester - … - collinear laser spectroscopy on bunched beams: I, m, Q measured 61Cu - 75Cu (Z=29, from N=32 to N=46) odd-even and odd-odd 67Ga - 81Ga (Z=31, from N=36 to N=50) odd-even and odd-odd - b-NMR and laser spectroscopy on laser-polarized beams: I, g, m measured 21Mg - 33Mg (Z=12, from N=9 to N=21) even-odd only The b-NMR collaboration at LISE-GANIL Leuven – GANIL – Bruyères-le-Chatel – Tokyo … - b-NMR spectroscopy on reaction-polarized beams: |g| and |Q| measured, I deduced 31Al-34Al (Z=13, from N=18 to N=21) odd-even and odd-odd 44Cl (Z=17, N=27) Others: - in-source laser spectroscopy at LISOL@CRC Louvain-la-Neuve: 57Cu (m) - TDPAD on isomeric states at GANIL: 43mS (Z=16, N=27) (|g|)

  11. S 36 P 35 Si Si Si Si Si Si Si Si Si 29 30 31 32 33 34 35 36 37 Al Al Al Al Al Al Al Al Al 28 29 30 31 32 33 34 35 36 Mg Mg Mg Mg Mg Mg Mg Mg Mg 27 28 29 30 31 32 33 34 35 Na Na Na Na Na Na Na Na Na 26 27 28 29 30 31 32 33 34 Ne Ne Ne Ne Ne Ne Ne 25 26 27 28 29 30 32 F F F F F 22 24 25 26 27 29 16 18 20 The “island of inversion” active neutron orbits around N=20 p3/2 f7/2 fp-shell 20 14 d3/2 s1/2 13 sd-shell d5/2 12 8 emptying pd5/2 11 influence of particle-hole excitations in the ground state wave functions ? pf 20 approaching N=20 Experimental challenge: how large is this ‘region of inversion’ ? Study transition region  difficult to make theoretical predictions ! sd

  12. b asymmetry B (gauss) g-factors of Al isotopes ground states dominated by pd5/2-1 P. Himpe et al., Phys. Lett. B 643 (2006) 257–262 Z=13: hole in pd5/2 orbital  Ip = 5/2+ expected for odd-Al isotopes  wave function and spin confirmed by g-factor through comparison with calculated m=g.I in sd-shell model (USD – 0p0h) sdf7/2p3/2 shell model space - SDPF-M (MCSM, mixed) - sdpf-interaction (2p2h) (free-nucleon g-factors) 33Al(Si) Conclusion for 33Al (N=20):  small (<25-30 %) intruder admixture in the 33Al ground state. Y. Utsuno et al., PRC 64, 011301R, 2001

  13. quadrupole moments of 31,33Al  more sensitive to neutron excitations M. De Rydt et al., PLB 678, 344 (2009)  Q(31Al) Error bars smaller than dot size ! 31Al(Al203) T. Nagatomo, et al., EPJA 42, 383–385 (2009)  Q(33Al) … to be continued ! 2p-2h Calculations in sdp3/2f7/2-shell: * SDPF-M interaction (MCSM) Otsuka, Utsuno et al., private communication * sdpf-NR interaction (ANTOINE code) Nummela et al., PRC63 (2001) exp nQ(kHz) 0p-0h • very good agreement for 27,31Al • with proton effective charge : • ep = 1.1 e • neutron effective charge: • en = 0.5e • 33Al has a mixed g.s. configuration: • n(sd)-2(fp)2 contribution in wave function ! • To determine amount of mixing: • need more precise Q-moment value ! • Experiment at GANIL, july 2010

  14. Fitted effective charges using static Q-moments M. De Rydt et al., PLB 678, 344 (2009) Compare Qexpof sd-shell isotopes (errors smaller than dot-size) with calculated values in sdp3/2f7/2-space using sdpf-NR effective interaction odd-Z quadrupole moments epeff=1.3e M. Depuydt, M. De Rydt, G. Neyens, to be published 33 sd-shell Q-moments sdpf-U effective interaction (Nowacki and Poves, PRC79, 014310 (2009)) c2=3.4 epeff=1.1e • sd-shell proton effective charge: ep = 1.12 e • neutron effective charge: en= 0.45 e c2=1.5

  15. nd3/2 + nf7/2 - g-factor (+ sign) and spin of the 31,33Mg ground state G. Neyens et al., PRL 94, 022501 (2005) D. Yordanov et al., PRL 99, 212501 (2007) 20 • Measured spin 31Mg and 33Mg • From sign of g-factor  parity • 31Mg, Ip = 1/2+ n(sd)-3 (fp)2 • 33Mg, Ip = 3/2- n(sd)-2(fp)3 • pure 2p-2h intruder ground states ! Al Al Al Al Al Al Al Al Al 28 29 30 31 32 33 34 35 36 Mg Mg Mg Mg Mg Mg Mg Mg Mg 27 28 29 30 31 32 33 34 35 REAL ground state configurations: Normal ground state configurations: 31Mg (N=19) 31Mg (N=19) 33Mg (N=21) 33Mg (N=21) pf f7/2 Ip=1/2+ Ip=3/2- 20 20 20 20 Ip=3/2+ Ip=7/2- d3/2 d3/2 n(s1/2-1)(d3/22)0(fp)20 n(d3/2-2)0(f7/2,s=3)33/2 sd n(d3/2-2)0(f2)0p3/2 [n(d3/2-1)p(sd)2+]1/2(fp)20

  16. Debate on the 33Mg ground state parity gexp(33Mg) = - 0.4971(4) g -0.51 +0.56 -0.21 -1.98 -1.72 Interpretation in Nilsson Model: 31Mg ground state: build on ½+[200] g= -1.72 (exp=-1.7671) 33Mg ground state: and on 3/2-[321] g= -0.21 (exp= -0.4971) 3/2-[330] g= -0.51 (exp= -0.4971)

  17. p3/2 28 28 Ip=7/2- f7/2 f7/2 20 20 Ip=3/2+ d3/2 s1/2 sd p3/2 • normal ground state in 33Mg • same g-factor (particle in f7/2) as 35Si 1p1h intruder ground state in 33Mg  same g-factor as 33Si Parity of the 33Mg ground state: 3/2+ or 3/2- ? Compare to g-factors of isotones with similar configuration: 3/2+: hole in d3/2 orbit (1h-2p configuration)3/2-: particles in fp-shell (2h-3p configuration) N=19 isotone: 33Si N=21 isotone: 35Si S 36 p=- P 35 Si Si Si 33 34 35 p=+ Al Al Al 32 33 34 Mg Mg Mg 31 32 33 20 21 19 g(35Si) = -0.47 g(33Si) = +0.76 • 2p2h ground state in 33Mg • similar g-factor as 35Si (3 particles in f7/2) • (f7/2)33/2 • 2 neutron holes in sd act as spectators (paired) gexp(33Mg) = -0.4971(4) gsdpf(3/2+) = +0.78 (1w) gsdpf(3/2-) = -0.47 (2w) G. Neyens et al., PRL 94, 022501 (2005) D. Yordanov et al., PRL 99, 212501 (2007) D. Yordanov et al., PRL 104, 129201 (2010)

  18. Summary: “island of inversion” around 32Mg Present status of the “Island of inversion” as deduced from static and dynamic moments measurements P. Himpe et al., Phys. Lett. B. 658, 203 (2008) All intruder g.s. configurations are of the 2p-2h type !! (two neutrons excited across N=20) Utsuno et al., PRC70,0044307,2004

  19. Evolution of the proton single particle states above Z=28 79Cu 78Cu 77Cu 61Cu 62Cu 78Ni 77Ni 76Ni 82Ga 77Ga 79Ga 81Ga 78Ga 66Ga 68Ga 69Ga 71Ga 72Ga 74Ga 76Ga 67Ga 70Ga 73Ga 80Ga 44 75Ga 44 65Zn 67Zn 68Zn 70Zn 71Zn 73Zn 75Zn 64Zn 66Zn 69Zn 72Zn 74Zn 64Cu 66Cu 68Cu 69Cu 71Cu 72Cu 74Cu 76Cu 63Cu 65Cu 67Cu 70Cu 73Cu 75Cu 64Ni 65Ni 66Ni 67Ni 68Ni 69Ni 70Ni 71Ni 72Ni 73Ni 74Ni 75Ni Z=28 n(p3/2,f5/2p1/2) n1g9/2 N=40 46 48 N=50 1/2- 5/2- Evolution of the experimental 5/2- and 1/2- energies in Cu isotopes pp1/2 200 ns pf5/2 1.5 ms 3/2- 75Cu 71Cu 59Cu 67Cu 57Cu 61Cu 63Cu 65Cu 69Cu 73Cu pp3/2 N=28 N=40 Stefanescu et al., PRL 100, 112502 (2008) J.M. Daugas, Ph.D. Thesis, GANIL S. Franchoo et al., PRC 64, 054308 (2001) Steep decrease of the 5/2- and 1/2- levels when ng9/2 is filled Experiment: g.s. spin assigned up to 73Cu (3/2-) from b-decay

  20. Ground state spin of 71,73,75Cu K.T. Flanagan et al., PRL 103, 142501 (2009) • g.s. spins measured with laser spectroscopy • spins assigned to isomeric levels in 75Cu • (based on measured lifetimes – Daugas, PhD Thesis) 73Cu, I=3/2 • Theory reproduces lowering of 5/2- correctly • theory overestimates the 1/2- energy • by ~300 keV in 73Cu and 75Cu !!! 75Cu, I=5/2 Model space: 56Ni core + f5/2 p3/2 p1/2 g9/2 Effective interaction: Lisetsky and Brown based on A. F. Lisetskiy et al., Phys. Rev. C 70, 044314 (2004) JJ44b, Brown

  21. Energy levels of odd-Cu isotopes beyond N=40 Calculations: Model space (56Ni core) + f5/2 p3/2 p1/2g9/2 Effective Interactions: * JUN45, Honma et al., PRC80, 064323, 2009 N=40 • Above N=40: • 5/2- level rather OK • ½- > 800 keV too high 3

  22. Magnetic moments of odd-Cu isotopes from N=28 to N=46 K.T. Flanagan et al., PRL 103, 142501 (2009) T. Cocolios et al., PRL 103, 102501 (2009) Calculations: Model space (56Ni core) + f5/2 p3/2 p1/2g9/2 Effective Interactions: (JUN45, Honma et al., PRC80, 064323, 2009) * jj44b, Brown, private communication Conclusions: 69Cu magnetic moment very close to the reduced single particle value (2) used gs = 0.7 gsfree(56Ni core, no f7/2) (3) Towards N=28: both p and n f7/2 core excitations needed to reproduce core softness (GXPF1 gives perfect agreement)! (4) Beyond N=40: * 75Cu, 5/2 g-factor well reproduced (because nearly pure pf5/2 wave function) * 71,73Cu, 3/2 values largely overestimated  need more mixing with (pf5/22+)3/2

  23. Quadrupole moments of odd-Cu isotopes from N=32 to N=46 jj44b interaction: 56Ni core (N=Z=28) neutrons up to N=50  single particle value Qsp(pp3/2) is reached at the borders of the model space (N=28, N=50)  increase of Q-moments for 3/2 and 5/2 states towards mid-shell (normal behaviour between shells) • Q-moment of 69Cu very close to that of single particle value: • N=40 behaves as a ‘magic’ gap • reason: not ‘energy’ gap • parity change pf (neg) to g9/2(pos) • The model reproduces extremely well the Cu quadrupole moments around N=40. • Deviation in 61Cu significant ? Signature of breakdown of magicity of 56Ni core ? • 75Cu Q-moment in agreement with that for a 5/2- configuration !!

  24. 1/2 32P3/2 3/2 7/2 I (72,74Cu) = 2 m < 0 3/2 32S1/2 most intense line 5/2 Ground state spin of 72,74Cu, sign of m K.T. Flanagan et al., in preparation 72Cu, I=2 • Ground state spin 72,74Cu is I=2, • with more than 4 sigma • confidence level 74Cu, I=2 Ratio of A-factors should be constant, if the hyperfine structure is fitted with correct spin value (input in fit: I, Au, Ad, Bu, IS) 5/2

  25. 1g9/2 1g9/2 40 40 2p1/2 2p1/2 1f5/2 1f5/2 2p3/2 2p3/2 Ground state parity and structure of 72Cu 72Cu  expected low-energy levels: use Paar’s rule N=43 (pp3/2 np1/2-1g9/24)  (1,2)+  neutron excitation across N=40 Z=29 (pf5/2 ng9/23)  (2,…,7)-  proton excited to the f5/2 orbital (pp3/2 ng9/23)  (3,4,5,6)- J.C. Thomas et al., PRC74, 054309, 2006 2+ (1+) 376 431 Ground state has spin I=2  But what is the parity ?? 1+ 418 2- 387 t1/2=1.76ms (6-) 270 (4-) ?? 219 5- 235 • Can we assign parity • based on measured • magnetic moment ? • m = -1.3451(6) mN (3-) 137 4- 140 6- 16 (2) 0 0 3- Realistic interaction Experiment

  26. Ground state parity and structure of 72Cu: Ip = 2- !! Use additivity rules for proton-neutron configurations: Main negative parity configuration: m(pf5/2 ng9/23; 2-) mfree(2-) = -2.13 mN memp(2-) = -1.94 mN Main positive parity configuration:m(pp3/2 np1/2-1g9/24; 2+) mfree(2+) = +4.44 mN memp (2+) = +1.44 mN Conclusion: the measured SIGN of the moment, m = -1.3451(6) mN, is crucial to decide on the parity !  in absolute value it is in agreement with 2+ however, a negative sign is only compatible with a proton in f5/2 orbital 2+ (1+) 376 431 1+ 418 2- 387 t1/2=1.76ms (6-) 270 (4-) 219 5- 235 (3-) 137 4- 140 6- 16 (2-) 0 0 3- Realistic interaction Experiment

  27. Ground state spins in odd-Ga isotopes 61Cu 62Cu 79Cu 78Cu 77Cu 76Ni 77Ni 78Ni 77Ga 79Ga 81Ga 78Ga 66Ga 68Ga 69Ga 71Ga 72Ga 74Ga 76Ga 67Ga 70Ga 73Ga 80Ga 44 75Ga 44 82Ga 65Zn 67Zn 68Zn 70Zn 71Zn 73Zn 75Zn 64Zn 66Zn 69Zn 72Zn 74Zn 64Cu 66Cu 68Cu 69Cu 71Cu 72Cu 74Cu 76Cu 63Cu 65Cu 67Cu 70Cu 73Cu 75Cu Z=28 64Ni 65Ni 66Ni 67Ni 68Ni 69Ni 70Ni 71Ni 72Ni 73Ni 74Ni 75Ni n(p3/2,f5/2p1/2) n1g9/2 N=40 46 48 N=50 Normal ground state configuration of odd-Ga isotopes: (pp3/2)3 3/2- Prior to our work: firmly assigned 3/2- value up to 75Ga tentatively assigned 3/2- for 77,79Ga no assignment for 81Ga This work: measured all g.s. spins from 67Ga up to 81Ga !! B. Cheal et al., submitted PRL Spin changes in 73Ga (I=1/2) and 81Ga (I=5/2) !!  Need the magnetic and quadrupole moment to understand this structure change !

  28. Odd-Ga level systematics N=46 N=38 I. Stefanescuet al. PRC 79, 064302 (2009) N=44 N=40 Dip in 9/2+ energy at 73Ga (N=42) (intruder pg9/2 leading to onset of deformation around neutron mid-shell at N = 42) N=42 • No low-lying spin-1/2 state observed in 73Ga before. • 3/2- seen in 73Ga seen in (p,t) reaction study (Vergnes et al., PRC19, 1276, 1971) •  ½- g.s. must be near-degenerate with this 3/2- state (less than 1 keV according to Stefanescu)!!

  29. g-factors of odd-Ga isotopes B. Cheal et al., submitted to PRL g-factors • g.s. wave function dominated by unpaired pp3/2, in 67,69,71Ga and in 75,77Ga • g.s. dominated by odd pf5/2 configurations in 81Ga, having spin 5/2, but also in 79Ga having spin 3/2 • 79Ga: mixed p(p3/22f5/2)2+ and p(f5/23, s=3)3/2 • g.s very mixed in 73Ga: p(p3/23, s=3)1/2 with pp1/2 and pf5/22+ • the 73Ga g.s. g-factor gexp=0.418(4) is very close to gR ~ Z/A ~ 0.44) I=5/2 I=3/2 I=1/2 N=50 N=40

  30. quadrupole moments of odd-Ga isotopes B. Cheal et al., PRL submitted • Shape changes • (1) around 73Ga • Below N=42 (36,38,40): Q > 0 • main configuration: Q(p3/23) = Q(p3/2-1 ) • (hole configuration has a positive Q-moment) Qs • Above N=42 (44,46) : Q < 0 • main configuration: p3/2+1 (f5/2p1/2)2 • (particle configuration has a negative Q-moment) N=50 N=40 (2) In 79Ga positive Q-moment and protons mostly in f5/2 from measured g-factor  mixing between (pp3/2p(f5/2)2)3/2 (this does not give correct moments) (f5/2)33/2 (gives correct moments  leading term) (3) In 81Ga slightly negative Q-moment (particle-like): 3 p in f5/2 coupling to 5/2  Q=0

  31. Comparing magnetic moments to JUN45 and jj44b B. Cheal et al., submitted to PRL JUN45 jj44b Second 3/2- in calculations !!  Both interactions predict g.s. structure of 79Ga around 250-300 keV !

  32. Comparing quadrupole moments to JUN45 and jj4b B. Cheal et al., submitted to PRL JUN45 jj4b ep=1.5e en=0.5e Second 3/2- in calculations !! Conclusions: (1) jj44b has better overall agreement for the magnetic moments ! (2) in jj44b the quadrupole moment of 69Ga and 71Ga has wrong sign  too fast emptying of the p3/2 orbital ?

  33. Comparing experimental levels to JUN45 and jj4b Real ground state: m and Q reproduced ! Real ground state ??? NO, magnetic moment not reproduced!

  34. N=28 N=20 40S 39P 35P 41Ca 39Ar 38Cl 37S 39Cl 38S 37P 36P 41Ar 40Cl 39S 38P 43K 42K 41Cl 42S 45Ca 42Ar 43P 46K 43Ar 42Cl 41S 40P 45K 44Ar 44K 43Cl 41P 47Ca 45Ar 44Cl 43S 42P 47K 46Ar 45Cl 44S 40Ar 44Ca 43Ca 42Ca 40Ca 36S 37Cl 38Ar 41K 40K 39K 48Ca 46Ca Z=20 39Ca 38K 37Ar 36Cl 35S 34P nf7/2 np3/2 Reduction of the N=28 gap below 48Ca Evidence for N=28 gap reduction below 48Ca, in - in Ar isotopes - in S isotopes N=27 isotones Experimental 7/2- and 3/2- np3/2 • From Gaudefroy et al., PRL 102 (2009): • 7/2- isomer in 43S is dominated by nf7/2(from g-factor) • very good agreement with sdpf-U interaction • suggested g.s. of 43S: a collective 3/2- state • dominated by np3/2 nf7/2 • 44Cl between 45Ar and 43S

  35. Z=20 pd3/2 ps1/2 nf7/2 Near-degeneracy of ps1/2 and pd3/2 near N=28 43Cl and 45Cl have probably 1/2+ ground state (A. Gade, PRC 74(2006)034322) 44Cl is in between 43Cl and 45Cl 44Cl ground state presumably dominated by πs1/2 configurations N=22 N=24 N=26 N=28 • Hardly no experimental information available on 44Cl • knock-out reaction from 45Cl (PRC79, 2009) suggests 2- g.s. with significant contribution from np3/2 in the wave function • no excited states known. Normal 44Cl g.s. configuration = (pd3/2nf7/2-1) 2,3,4,5- Mixed with (pd3/2np3/2) 0,1,2,3- (ps1/2np3/2) 1,2- • pushes 2- down in energy • lowers the g-factor

  36. g-factor and g.s. structure of 44Cl • Fragmentation of 48Ca beam, 2 mA • select polarized beams at LISE-GANIL • for b-Nuclear Magnetic Resonance b-NMR on 44Cl(NaCl) |g|=0.27487(16) b-asymmetry M. De Rydt et al., PRC 81, 034308 (2010) Calculation: sdpf-U interaction (Nowacki and Poves, PRC79 (2009)) protons in sd orbits neutrons in pf orbits gseff=0.75gs GOOD AGREEMENT : Ground state spin 2 confirmed VERY MIXED WAVE FUNCTION CONFIRMED

  37. Conclusions (1) Knowing magnetic moments and quadrupole moments in a series of isotopes or isotones is extremely helpful to understand the structural changes in isotopes far from stability ! (2) Measurements of the g.s. spin is needed in these exotic regions, because theories are not sufficiently well developed to make predictions ! (3) Measured g.s. spin values are crucial for further assigning spins of excited levels. (4) Measuring the sign of the g-factor (magnetic moment) is crucial for interpretation of the mixed g.s. structures (less critical for isomeric states that are mostly of single particle nature)

  38. 34Al g factor M. De Rydt et al., PLB 678, 344 (2009) 31Al(Al203) T. Nagatomo, H. Ueno et al., preliminary 33Al NQR P. Himpe et al., Phys. Lett. B 643 (2006) 257–262 nQ(kHz)

  39. Energy levels of odd-Cu isotopes from N=28 to N=50 N=40 N=28 • Below N=40: • 5/2- level ~500 keV high • ½- rather OK, not in 57Cu • Above N=40: • 5/2- level rather OK • ½- > 800 keV too high • Below N=40: • 5/2- level in 57Cu too low ! • 5/2- level ~ 200 keV too low • ½- rather OK • Above N=40: • 5/2- level rather OK • ½- bit too high in 73,75Cu 3

  40. Energy levels Cu isotopes beyond N=42 (pf5/2ng9/2)2-7 (pp3/2ng9/2)3-6

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