1 / 23

N=28, Shell Closure and Shapes

N=28, Shell Closure and Shapes. L. Gaudefroy CEA/DIF – Bruyères-le-Châtel. Courtesy of M. Rejmund. LEA - COLLIGA – Catania : 13-16 October 2008. N=28. f 5/2. f 5/2. p 1/2. p 1/2. p 3/2. p 3/2. f 7/2. f 7/2. F. Nowacki and A. Poves from ArXiv. S. Péru et al. EPJA 9, 35 ( 2000 ).

randi
Download Presentation

N=28, Shell Closure and Shapes

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. N=28, Shell Closure and Shapes L. Gaudefroy CEA/DIF – Bruyères-le-Châtel Courtesy of M. Rejmund LEA - COLLIGA – Catania : 13-16 October 2008

  2. N=28 f5/2 f5/2 p1/2 p1/2 p3/2 p3/2 f7/2 f7/2 F. Nowacki and A. Poves from ArXiv S. Péru et al. EPJA 9, 35 (2000) d3/2 d3/2 s1/2 s1/2 d5/2 d5/2 Shell Structure Shell Structure N=28 Ca Full Ar Experimental difficulty Proton removal in p(s1/2 & d3/2) S N/Z 28 20 20 20 28 8 40 Si Empty • 1st magic number originating from SO interaction • Evolution of SO with isospin • Role of pn interaction on structure fp Without SO interaction First evidence for shell erosion : b-decay studies around 44S => Unexpected deformations requiered to reproduced T1/2 O. Sorlin et al. PRC 47, 2941 (1993) sd

  3. N=28 -E(2+) = 1577 keV H. Scheit et al. PRL 77, 3967 (1996) -E(2+) = 1297 keV T. Glasmacher et al. PLB 395, 163 (1997) -E(2+) = 1330 keV S. Grévy et al. EPJ A 25 (2005) -E(2+) = keV B. Bastin, S. Grévy et al. PRL 99 (2007) 2+ 0+ : 770 ± 20 keV NEW Progressive erosion of the gap predicted in both MF and SM frameworks

  4. In this talk Empty Full p(s1/2 & d3/2) Ar Ca Si S Def. Spher. Part I : -Study of the 46Ar(d,p) reaction. -Reduction of N=28 Gap -Reduction of SO splittings -Density dependence of SO & tensor L. Gaudefroy et al. – PRL 97, 092501 (2006) A. Signoracci & B.A. Brown – PRL 99, 099201 (2007) L. Gaudefroy et al. – PRL 99, 099202 (2007) -Study of the 44Ar(d,p) reaction. Part II : g-factor measurement in 43S.

  5. 44Ar(d,p)45Ar : Principle p d d MUST 8 modules Si 960 strips X-Y qp,Ep qp, Ep SPEG Spectro. Exotic beam 44Ar @ 10 MeV.A Ep CATS Beam tracking SPIRAL/GANIL CD2 45Ar 44Ar qp Study of the fp single particle states at N=28 (d,p) transfer reaction f5/2 p1/2 p3/2 28 f7/2 44Ar26 45Ar27

  6. 44Ar(d,p)45Ar : Results 600 400 200 0 E (MeV) 5 • lfrom the shape • C2S from the relative normalisation

  7. 44Ar(d,p)45Ar : Exp. vs Theorie 3/2 3.90 2020 2+ x 7/2- 7/2 2.10 0 47Ca27 Code ANTOINE : E. Caurier & F. Nowacki Interaction sdpf: S. Nummela et al. PRC63 (2001) 45Ar27 Satisfactory agreement

  8. 47Ca27 & 45Ar27 : Shell Model 3/2 3.90 2020 7/2 3/2 1.08 2.10 0 1420 47Ca27 np3/2 20 d3/2 2+ x nf7/2 3/2 0.76 s1/2 550 7/2 1.52 0 d5/2 45Ar27 p Increase of correlations already at Z=18

  9. More exotic N=27 isotones E = ESPE + EMono + EMulti Correl HF-MF Orbits S. Péru et al. EPJA 9, 35 (2000) EMulti (MeV) Z Ca 2 Ar 9 S 12 Si 15 L. Gaudefroy et al. PRC 78, 034307 (2007)

  10. g-factor measurement in 43S f5/2 p1/2 d3/2 p3/2 16 s1/2 7/2- 28 14 d5/2 f7/2 n p 488ns (3/2-) 3/2- 320 (7/2-) 43S -Mass measurement at GANIL: F. Sarazin et al. PRL 84, 5062 (2000) => Low lying isomeric state g factor of the isomeric state : -Direct detemination of spin/parity. -Test the WF of the state. m = g I

  11. Principle H = - µ B H = g.I B R(t) = A cos(wt+f) w = -gB B I(t) R(t) G - B G + B t t Fragmentation : ~300 43S/sec LISE@GANIL

  12. Results Exp gs Schmidt gSchmidt = ± 2ℓ+1 f7/2 -0.546 (j=ℓ ±1/2) -0.317 p3/2 -1.275 gs=-3.826

  13. Experiment vs. Theories f5/2 p1/2 p3/2 f7/2 d3/2 s1/2 d5/2 Part. Rotor Particule.+Rotor 20 20 Valence space -K=1/2 decoupled band. GS deformed band: b=+0.35 7/2- (isom.) not in this band Rather spherical Code ANTOINE : Caurier & Nowacki - Strasbourg

  14. Experiment vs. Theories Mean Field : -HFB – Gogny D1S -Blocking -GCM + GOA Ground State: -K=1/2 (from p3/2) -b=0.37 -Decoupling parameter & Inertia parameter=> in agreement with PR States from f7/2 orbit: -Within 400keV -Around b=0 L. Gaudefroy et al. To be submitted to Phys. Rev. Lett.

  15. Conclusion Part I : 44Ar(d,p) -Structure of 45Ar already points toward an increase of correlations. -SM description of N=27 isotones showing the evolution of multipolar energy. -Agreement with mean field description in this mass region. Part II : g-factor of 43mS -Direct evidence of config. inversion f7/2-p3/2 -Successfully interpreted with 3 models -Deformed ground state K=1/2 band -Rather spherical isomeric state

  16. Collaboration France : CEA-Bruyères-le-châtel, IPNO, GANIL, CEA-Saclay, CSNSM, CENBG, IReS, LPSC Bulgaria : Faculty of Physics Germany : Universität Mainz Hungary : INR Israel : Weizmann Institute Japan : Riken USA : FSU Russia : FLNR/JINR

  17. Conclusions Z=20 Z=18 Z=16 Z=14

  18. Perspectives 43S Z=20 Z=18 N=28 Z=16 Z=14 Même phénomène dans 41Si => 42Si déformé 44S 45S 43P 41Si 43Si 42Si • Hypothèse: • Bandes de rotation partout! • Décrire la structure de ces noyaux dans un cadre SM Travail en cours avec T. Faul L. Gaudefroy et al. soumis à PRC

  19. p1/2 f5/2 p3/2 f7/2 46Ar28 18 Fermi 28 d3/2 s1/2 n

  20. Polarisation du coeur f5/2 fp p1/2 p3/2 f7/2 Without SO interaction d3/2 sd s1/2 d5/2 Shell Structure 20 28 20 8 40

  21. 43S vs 44S (7/2-) -1n 7/2- 3/2- 43S q(01+,3/2) = q(02+,3/2) = 0.5 q = |<Yf| a(nlj) | Yi>|2 q(01+,7/2) = 2q(02+,7/2) = 0.4 0+ 2+ E0 0+ 44S S. Grévy et al. EPJ A 25 (2005) Si coexistence de forme dans 44S : cf. le tableau Recouvrements compatibles avec mixing important entre deux états 0+ (Sphér.  Déform.)

  22. Principe de l’expérience Faisceau primaire : 48Ca @ 60 A.MeV Système de détection Cible : Be

More Related