INT October 28, 2004Mihai Horoi - Central Michigan Univ1 New Approaches for Spin- and Parity-Dependent Shell Model Nuclear Level Density Mihai Horoi, Department of Physics, Central Michigan University, Mount Pleasant, Michigan 48859, USA Support from NSF grant PHY is acknowledged
INT October 28, 2004Mihai Horoi - Central Michigan Univ2 Plan of the Talk Part I: Methods for Shell Model NLD –Motivation –Sum on partitions vs moments of the whole density –Exponential Convergence Method –Fixed-J Configuration Centroids and Widths –Energy-Dependent Cutoff Description –PRC 67, (2003), PRC 69, (2004) Part II: Methods of Removal of the Center-of-Mass Spurious Contribution
INT October 28, 2004Mihai Horoi - Central Michigan Univ3 Hauser and Feshbach, Phys. Rev 87, 366 (1952)
INT October 28, 2004Mihai Horoi - Central Michigan Univ4 The Back-Shifted Fermi Gas Model for Nuclear Level Density
INT October 28, 2004Mihai Horoi - Central Michigan Univ5 A.Adams, G.Mitchell, J.F. Shriner Phys.Lett, B422, 13(1998) 26 Al sd-shell model, USD interaction
INT October 28, 2004Mihai Horoi - Central Michigan Univ6 Data: Table of Isotopes Theory: sd-shell model + USD interaction 28 Si: positive parity
INT October 28, 2004Mihai Horoi - Central Michigan Univ7 p ’s sd ’s pf ’s pf 5/2 -g 9/ Example: 76 Sr PRL 92, pf 5/2 -g 9/2 dimension 11,090,052,440 CMichSM code - m-scheme dimension 250,000,000 on one-processor machine Lanczos iterations/week
INT October 28, 2004Mihai Horoi - Central Michigan Univ8 12 particles in sd model space
INT October 28, 2004Mihai Horoi - Central Michigan Univ9 Nuclear Shell Model d = 2 (2 j + 1)
INT October 28, 2004Mihai Horoi - Central Michigan Univ10 Sum on Partitions vs Moments of the Whole Distribution 6 particles in pf 5/2 -g 9/2 New interaction A. Lisetskiy et al. PRC 2004
INT October 28, 2004Mihai Horoi - Central Michigan Univ11 12 particles in sd model space
INT October 28, 2004Mihai Horoi - Central Michigan Univ12 12 particles in sd model space
INT October 28, 2004Mihai Horoi - Central Michigan Univ13 6 particles in p-sd model space
INT October 28, 2004Mihai Horoi - Central Michigan Univ14 Exponential Convergence Method
INT October 28, 2004Mihai Horoi - Central Michigan Univ15 Exponential Convergence Method for fp-nuclei
INT October 28, 2004Mihai Horoi - Central Michigan Univ16 Exponential Convergence Method for fp-nuclei Central Michigan Shell Model (CMichSM) code Exact: MeV
INT October 28, 2004Mihai Horoi - Central Michigan Univ17 r,s,.. – orbits, not states
INT October 28, 2004Mihai Horoi - Central Michigan Univ18 Fixed J Configura tion Centroids and Widths C. Jacquemin, Z. Phys. A 303, 135 (1981)
INT October 28, 2004Mihai Horoi - Central Michigan Univ19 Shell Model vs Fixed-J Centroids and Widths Density of States 28 Si: 12 particles in sd, Tz=0
INT October 28, 2004Mihai Horoi - Central Michigan Univ20 Shell Model vs Fixed-J Centroids and Widths Density of States 28 Si: 12 particles in sd, Tz=0
INT October 28, 2004Mihai Horoi - Central Michigan Univ21 Spin Cutoff Factor Zeroth-Order: S.S.M. Wong, Nuclear Spectroscopy, Oxford 1986, p. 45, Si: 12 particles in sd, Tz=0
INT October 28, 2004Mihai Horoi - Central Michigan Univ22 Shell Model 28 Si: 12 particles in sd, Tz=0
INT October 28, 2004Mihai Horoi - Central Michigan Univ23 Shell Model 28 Si: 12 particles in sd, Tz=0
INT October 28, 2004Mihai Horoi - Central Michigan Univ24 Zeroth-Order 28 Si: 12 particles in sd, Tz=0
INT October 28, 2004Mihai Horoi - Central Michigan Univ25 Zeroth-Order 28 Si: 12 particles in sd, Tz=0
INT October 28, 2004Mihai Horoi - Central Michigan Univ26 Summary of Part I Shell Model NLD look very promising, at least up to the particle emission threshold. More comparison with experimental data necessary. J-dependent SM NLD are very accurately described by a sum of finite range Gaussians with fixed-J centroids and widths, if one knows with good precision the energy of g.s. and yrast states. We derived explicit expression to calculate fixed-J centroids and widths. Exponential Convergence Method (ECM) proves to be a very powerful tool for finding yrast and non-yrast energies, by doing shell model calculations in truncated model spaces. J-dependent SM NLD are reasonably well described by spin cutoff formula with exact cutoff factor, except for higher J’s, but not very well described by spin cutoff formula with zeroth-order cutoff factor. Improvement in estimating cutoff factor requires knowledge of higher order moments.
INT October 28, 2004Mihai Horoi - Central Michigan Univ27 The Center-of-Mass Problem nucl-th/
INT October 28, 2004Mihai Horoi - Central Michigan Univ28 Nuclear Shell Model N
INT October 28, 2004Mihai Horoi - Central Michigan Univ29 The Center-of-Mass Problem
INT October 28, 2004Mihai Horoi - Central Michigan Univ30 No E (MeV) Ex (MeV) J T No E (MeV) Ex (MeV) J T p-sd s-p-sd 2 particles 6 particles N = 1
INT October 28, 2004Mihai Horoi - Central Michigan Univ31 Dimensions of Nonspurious Spaces Example: s-p-sd, 6 particles J N=1(K=1) N=0 0 4 = = = = =1 0 Total 26
INT October 28, 2004Mihai Horoi - Central Michigan Univ32
INT October 28, 2004Mihai Horoi - Central Michigan Univ33 C. Jacquemin, Z. Phys. A 303, 135 (1981) Fixed J Restricted Configura tion Widths
INT October 28, 2004Mihai Horoi - Central Michigan Univ34
INT October 28, 2004Mihai Horoi - Central Michigan Univ35 N Nonspurious Level Density
INT October 28, 2004Mihai Horoi - Central Michigan Univ36 20 Ne: 20 particles in s-p-sd-pf shell model space
INT October 28, 2004Mihai Horoi - Central Michigan Univ37 20 Ne: 20 particles in s-p-sd-pf shell model space
INT October 28, 2004Mihai Horoi - Central Michigan Univ38 20 Ne: 20 particles in s-p-sd-pf shell model space
INT October 28, 2004Mihai Horoi - Central Michigan Univ39 Nonspurious Level Density: (0+2)
INT October 28, 2004Mihai Horoi - Central Michigan Univ40 10 B: 10 particles in s-p-sd-pf shell model space
INT October 28, 2004Mihai Horoi - Central Michigan Univ41 10 B: 10 particles in s-p-sd-pf shell model space
INT October 28, 2004Mihai Horoi - Central Michigan Univ42 Nonspurious Level Density: General
INT October 28, 2004Mihai Horoi - Central Michigan Univ43 Summary We derived explicit expressions to calculate fixed- J centroids and widths for restricted set of configurations, such N configurations We found recursive formulae to calculate the dimensions of nospurious spaces We found recursive formulae for calculating exactly the nonspurious level density when one knows the level density for a restricted set of configurations, such N configurations Using our method of calculating the level density for restricted set of configurations we can calculate very accurately the nonspurious level density