scholarly journals Alternating-parity bands of U236,238 and Pu238,240 in a particle-number-conserving method based on the cranked shell model

2020 ◽  
Vol 102 (6) ◽  
Author(s):  
Xiao-Tao He ◽  
Yu-Chun Li
Keyword(s):  
Shell Model ◽  
Particle Number

PARTICLE-NUMBER CONSERVING TREATMENT FOR THE GROUND STATE BANDS IN EVEN-EVEN TRANSFERMIUM NUCLEI

2008 ◽  
Vol 17 (supp01) ◽  
pp. 208-218 ◽  
Author(s):  
XIAO-TAO HE ◽  
ZHONG-ZHOU REN
Keyword(s):  
Angular Momentum ◽  
Shell Model ◽  
Single Particle ◽  
Ground State ◽  
Particle Number ◽  
Rotational Frequency ◽  
Moment Of Inertia ◽  
Particle Level ◽  
Pairing Correlations ◽  
Band Crossing

The ground state bands observed in even-even transfermium nuclei 250 Fm and 252,254 No are investigated by the cranked shell model with the particle-number conserving treatment for the monopole and quadrupole pairing correlations. The experimental variations of the kinematic moment of inertia with rotational frequency are reproduced very well in our calculation. Our results show bankbendings of [Formula: see text] at ħω ≈ 0.275 and 0.300 MeV in 252 No and 254 No , respectively. The detailed information about the contribution to alignment from each cranked single particle level exhibits that the backbending is mainly due to the rapidly aligned angular momentum of proton 1j15/2 [770]1/2 pairs and neutron 2h11/2 [761]3/2, 1j15/2 [734]9/2 pairs the band crossing.

THE HIGHER TAMM–DANCOFF APPROXIMATION: THEORETICAL CONTEXT AND PHENOMENOLOGICAL ASPECTS

2008 ◽  
Vol 17 (01) ◽  
pp. 228-239 ◽  
Author(s):  
PHILIPPE QUENTIN ◽  
HOUDA NAIDJA ◽  
LUDOVIC BONNEAU ◽  
JOHANN BARTEL ◽  
HA THUY LONG
Keyword(s):  
Shell Model ◽  
Quadrupole Interaction ◽  
Particle Number ◽  
Proton Proton ◽  
Hartree Fock ◽  
Pairing Correlations ◽  
Key Aspects ◽  
Proton Pairing ◽  
Theoretical Foundations ◽  
Model Approach

We present the key aspects of the theoretical foundations of the Higher Tamm–Dancoff Approximation which can be interpreted as a truncated shell-model approach based on a Hartree–Fock solution, ensuring the conservation of the particle number. Then we discuss some phenomenological aspects of the residual interactions used, namely the delta interaction to describe the neutron–neutron and proton–proton pairing correlations and the quadrupole–quadrupole interaction to describe vibrational correlations.

Unbiased estimation of particle number and sizes using the new stereological tools: the disector, the fractionator, the selector, and the nucleator — or just point-sampled intercepts

1988 ◽  
Vol 46 ◽  
pp. 428-429
Author(s):  
H.J.G. Gundersen
Keyword(s):  
Particle Number ◽  
Small Distance ◽  
Parallel Plane ◽  
Unbiased Estimation ◽  
Severe Problem ◽  
New Era ◽  
Size And Shape ◽  
Distinct Property ◽  
Sectioned Tissue

Previously, all stereological estimation of particle number and sizes were based on models and notoriously gave biased results, were very inefficient to use and difficult to justify. For all references to old methods and a direct comparison with unbiased methods see recent reviews.The publication in 1984 of the DISECTOR, the first unbiased stereological probe for sampling and counting 3—D objects irrespective of their size and shape, signalled the new era in stereology — and give rise to a number of remarkably simple and efficient techniques based on its distinct property: It is the only known way to obtain an unbiased sample of 3-D objects (cells, organelles, etc). The principle is simple: within a 2-D unbiased frame count or sample only cells which are not hit by a parallel plane at a known, small distance h.The area of the frame and h must be known, which might sometimes in itself be a problem, albeit usually a small one. A more severe problem may arise because these constants are known at the scale of the fixed, embedded and sectioned tissue which is often shrunken considerably.

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