Neutron Spectroscopic Factors from transfer reactions for Z=3-28 - PowerPoint PPT Presentation

Neutron Spectroscopic Factors from transfer reactions for Z=3-28 isotopes Kernz08 Dec 1-5, 2008 Betty Tsang The National Superconducting Cyclotron Laboratory @Michigan State University

Properties of valence nucleons  Spectroscopic factor (SF) Experimental SF : measures the orbital  d configuration of the valence ( )  EX d  nucleons. S  gs d ( )  RM Independent Particle Model d (IPM), SF represents how good can we describe the nucleus as a single particle plus a core. S Orbital description  exp 1 is accurate S IPM Valence nucleon S  exp occupies more 1 S than one orbit IPM  LBSM .

Properties of valence nucleons  Spectroscopic factor (SF) Experimental SF : measures the orbital  d configuration of the valence ( )  EX d  nucleons. S  gs d ( )  RM Large Basis Shell Model (LB- d SM), SF can be used to test the interactions used in SM. S Orbital description  exp 1 is accurate S  SM LB S Improvement in  exp 1 S interactions?  SM LB

Problems with previous experimental SF Example: 1 f 7/2 neutron SF in 41 Ca = 40 Ca+n Measurements in (d,p) and (p,d) reactions 600 600 500 No. of papers 400 SF SM =1.00 300 300 200 100 0 50’s 60’s 70’s 80’s 90’s 2000- 1 2 3 4 5 6 Decade Spectroscopic factor  reflects the properties of valence neutron  constant value independent of incident energy Large fluctuations : Consequence of using different codes, optical model potentials and parameters in the reaction model  cannot constrain the physics Important to have systematic approach  consistent spectroscopic factors

14 C(d,p) 15 C Goss, PRC12,1730 (1975) E d =14 MeV E d =16 MeV SF=0.88 Cecil, NPA255,345 (1975) E d =17 MeV The data differ by factor of 2 but SF’s are nearly SF=0.99 the same by varying the Murillo, input parameters!! NPA579, 125 (1994) SF=1.03

Discrepancies between data sets Quoted experimental uncertainties are 6-20% J. P. Schiffer et al., Phys. Rev. 164, 1274 (1967) J. P. Schiffer et al., Phys. Rev. 164, 1274 (1967). Z. H. Liu et al., Phys. Rev. C 64, 034312 (2001). Z. H. Liu et al., Phys. Rev. C 64, 034312 (2001). J. Lang et al., Nucl. Phys. A477, 77 (1988). D.Fick, J,NUK,19,693 (1974) (EXFOR). U.Schmidt-Rohr et al., Nucl. Phys. 53, 77 (1964). Quality control from independent measurements

Systematic methods for consistent spectroscopic factors       d d      SF EXP       d d J. Lee et al, Phys. Rev. C75 (2007) 064320 EXP Theo ADWA  Johnson- Soper (JS) Adiabatic Approximation to take care of d-break-up effects  Use global p and d optical potential with standardized parameters (CH89)  Include finite range & non- locality corrections  n-potential : Woods-Saxon shape r o =1.25 & a o =0.65 fm; depth adjusted to reproduce experimental binding energy.  Compute with TWOFNR code TWOFNR from Jeff Tostevin (University of Surrey)

Compare with LB-Shell Model (Oxbash, B.A. Brown) Austern’s values were predicted 40 years ago Good agreement with most isotopes M.B. Tsang, et al, PRL95, 222501 (2005).

Ground State Neutron Spectroscopic Factors for Ni isotopes • 56 Ni core, in fpg model Ground-state SFs for Ni space • New T=1 effective interaction (derived for heavy Ni isotopes) --XT • 40 Ca core, in fp model space • GXPF1A, KB3G interaction • No 56 Ni shell closure requirement  calculations with truncated basis are wrong.  GXPF1A + complete basis calculation is in best agreement with the data *Linear lines are the least square fits of the linear correlations between data and predictions.

SF determinations need to be better than a factor of 2 F. Montes, MSU X-ray burst light curves from Change in light curve by 10% if rate of 27 P(p, g ) 28 S is GS 1826-24 – observation uncertain --10% changed by factor of 2. Biggest uncertainty: excited-state SF

Excited-state Spectroscopic Factors of sd shell nuclei Analyzed ~ 794 angular distributions Excited-state SFs of rare nuclei: • rp process calculations • X-ray burst simulations Not available in experiment  from SM predictions g.s. g.s.  SFs for excited states are very small (< 0.1) 17 O, 18 O, 17 O, 18 O, Ex.  Test the predictive power of 21 Ne, 21 Ne, 24 Na, 24 Na, Shell Model 25 Mg , 27 Mg, 25 Mg , 27 Mg,  Use nuclei in sd shell where 29 Si, 31 Si, 29 Si, 31 Si, the interaction (USDA/USDB) 33 S, 35 S, 33 S, 35 S, is well understood. (32 P, 36 Cl, 37 Ar) (32 P, 36 Cl, 37 Ar) Z Agreement with Shell Model better than 30% S.C. Su (Chinese University of Hong Kong) – 06’ SURE program N paper in preparation

Application: Determination of Spin assignments from Systematics J π assignment 27 Mg (NUDAT): 5.627;3/2 + (5/2) (3/2,5/2) + Expt SM 3.491;3/2 + 5.454, 3/2 5.627 (3/2,5/2) 4.15;5/2 + 5.404, 5/2 S.C. Su (Chinese University of Hong Kong) – 06’ SURE program, Paper in preparation

Z Comparison with Large-Basis Shell Model (Oxbash) and Independent Particle Model (IPM) for Ca isotopes, 40 Ca – 48 Ca M.B. Tsang, et al, PRL95, 222501 (2005). N IPM predictions: Assume Spherical core + Maximal pairing S  g.s. n for even n  n 1   S 1 for odd n  2 j 1  SF’s of 40 Ca- 48 Ca isotopes agree very well with IPM  Good agreement with LB-SM  The 1f 7/2 valance neutrons in Ca isotopes are good single particles with spherical 40 Ca core.

Neutron Spectroscopic Factor – Ca, Ti, Cr isotopes Agreement with shell model generally better than a factor of 2 Phoenix Dai (Chinese University of Hong Kong) – 07’ SURE program Large fragmentation of states spreading over the energy space in experiment, but shell model predicts mainly single particle states

Fragmentation of the single particle strength for N=27 and N=29 The fragmentation is more obvious when we compare the N=27 and N=29 isotones Fragmentation of the levels increases when more protons are added Calculations of SFs for Ti and Cr  Time consuming • using FPD6PN in MSU_HPC by Hang Liu (Oxbash) • using GXPF1A by M. Horoi (m-matrix code -- Antoine )  similar results Phoenix Dai – DNP 07’ -- CEU poster section (DA00017)

Neutron Spectroscopic Factors for Ni isotopes M. Horoi GXPF1A XT Complete basis states predicted < 3MeV • GXFP1A with full fp model space • XT interaction provides a fast does not require 56 Ni shell closure way to predict the spectroscopic  CPU intensive properties of these nuclei. SF values agree to factor of 2  cannot distinguish between two interactions Data uncertainties: 20-30 %  Interactions for gfp shell still need improvements

Measurements of Spectroscopic Factors Lapikas, NPA 553 , 297c (1993) Gade, PRL 93 , 042501 (2004) Nucleon knockout (e,e’p) Tsang et al, PRL 95 , 222501 (2005)

Quenching observed from (e,e’p) and knockout reactions J. Lee et al, Phys. Rev. C 73 , 044608 (2006) G.J.Kramer et al., Nucl. Phys. A 679, 267 (2001) ( e,e’p ): Proton SF values deduced from nuclei near closed shells are suppressed by As long as a systematic approach is 30-40% compared to IPM used, relative SF can be obtained reliably over a wide range of nuclei  Correlation is beyond the residual interactions employed in the shell model.

Reduced spectroscopic factors from transfer reactions n-rich p-rich • Consistent with proton SF studied with (e,e’p) reactions

Neutron transfer reactions for neutron rich and proton rich Ar isotopes NSCL Expt 05133 (Oct19-30, 2007) J. Lee et al, Phys. Rev. C 73 , 044608 (2006) n-rich p-rich Inverse kinematics at 35MeV/u: p( 34 Ar,d) 33 Ar & p( 46 Ar,d) 45 Ar 34 Ar

Expt 05133 : Neutron transfer reactions for neutron rich and proton rich Ar isotopes Inverse kinematics at 33 MeV/A: p( 34 Ar,d) 33 Ar & p( 46 Ar,d) 45 Ar Schematics of setup with HiRA and S800

4x CsI(Tl) 4cm Si-E 1.5 mm Si- D E 65 m m pixel 32 strips v (front) 32 strips h. (back) PID from previous experiment 32 strips v. (front) Beam High resolution in energy, position and dE-E. • 20 Telescopes • 62.3 x 62.3 mm 2 Active Area • strip pitch 1.8 mm • 1024 Pixels per telescope

HiRA collaborators NSCL Bill Lynch; Betty Tsang; Vladimir Henzl ; Daniela Henzlova; Andy Rogers; Micha Kilburn; Sun Zhiyu; Alisher Sanetullaev; Daniel Coupland; Mike Youngs; Jenny Lee; Daniel Bazin; Mauricio Portillo; Marc Hausmann; Len Morris WU in St. Louis Lee Sobotka; Bob Charity; Jon Elson Indiana University Romualdo Desouza; Sylvie Hudan Western Michigan University Mike Famiano; Alan Wousma LANL Mark Wallace ORNL Dan Shapira Rutgers University Jolie Cizewski; Bill Peters; Patrick O'Malley University of Tennesee Kate Jones; Kyle Schmitt; Andy Chae; Brian Moazen INFN, Catania, Italy Giuseppe Verde