Heavy Residue Isoscaling as a Probe of the Process of N/Z Equilibration

The isotopic and isobaric scaling behavior of the yield ratios of heavy projectile residues from the collisions of 25 MeV/nucleon 86Kr projectiles on 124Sn and 112Sn targets is investigated and shown to provide information on the process of N/Z equilibration occurring between the projectile and the target. The logarithmic slopes $\alpha$ and $\beta^{'}$ of the residue yield ratios with respect to residue neutron number N and neutron excess N--Z are obtained as a function of the atomic number Z and mass number A, respectively, whereas excitation energies are deduced from velocities. The relation of the isoscaling parameters $\alpha$ and $\beta^{'}$ with the N/Z of the primary (excited) projectile fragments is employed to gain access to the degree of N/Z equilibration prior to fragmentation as a function of excitation energy. A monotonic relation between the N/Z difference of fragmenting quasiprojectiles and their excitation energy is obtained indicating that N/Z equilibrium is approached at the highest observed excitation energies. Simulations with a deep-inelastic transfer model are in overall agreement with the isoscaling conclusions. The present residue isoscaling approach to N/Z equilibration offers an attractive tool of isospin and reaction dynamics studies in collisions involving beams of stable or rare isotopes.Comment: 15 pages, 4 figures, submitted to Phys. Lett.

Investigation of refractory dielectric for integrated circuits Second quarterly report, Dec. 1968

Process development for chemical deposition of aluminum oxide films as refractory dielectrics for integrated circuit

Investigation of refractory dielectric for integrated circuits Third quarterly report, Feb. 1969

Research and development on refractory dielectrics for integrated circuit

Efficient Optimization of Performance Measures by Classifier Adaptation

In practical applications, machine learning algorithms are often needed to learn classifiers that optimize domain specific performance measures. Previously, the research has focused on learning the needed classifier in isolation, yet learning nonlinear classifier for nonlinear and nonsmooth performance measures is still hard. In this paper, rather than learning the needed classifier by optimizing specific performance measure directly, we circumvent this problem by proposing a novel two-step approach called as CAPO, namely to first train nonlinear auxiliary classifiers with existing learning methods, and then to adapt auxiliary classifiers for specific performance measures. In the first step, auxiliary classifiers can be obtained efficiently by taking off-the-shelf learning algorithms. For the second step, we show that the classifier adaptation problem can be reduced to a quadratic program problem, which is similar to linear SVMperf and can be efficiently solved. By exploiting nonlinear auxiliary classifiers, CAPO can generate nonlinear classifier which optimizes a large variety of performance measures including all the performance measure based on the contingency table and AUC, whilst keeping high computational efficiency. Empirical studies show that CAPO is effective and of high computational efficiency, and even it is more efficient than linear SVMperf.Comment: 30 pages, 5 figures, to appear in IEEE Transactions on Pattern Analysis and Machine Intelligence, 201

Effects of momentum-dependent symmetry potential on heavy-ion collisions induced by neutron-rich nuclei

Using an isospin- and momentum-dependent transport model we study effects of the momentum-dependent symmetry potential on heavy-ion collisions induced by neutron-rich nuclei. It is found that symmetry potentials with and without the momentum-dependence but corresponding to the same density-dependent symmetry energy $E_{sym}(\rho)$ lead to significantly different predictions on several $E_{sym}(\rho)$-sensitive experimental observables especially for energetic nucleons. The momentum- and density-dependence of the symmetry potential have to be determined simultaneously in order to extract the $E_{sym}(\rho)$ accurately. The isospin asymmetry of midrapidity nucleons at high transverse momenta is particularly sensitive to the momentum-dependence of the symmetry potential. It is thus very useful for investigating accurately the equation of state of dense neutron-rich matter.Comment: The version to appear in Nucl. Phys. A. A paragraph and a figure on neutron and proton effective masses in neutron-rich matter are adde

Modeling the optical constants of wide-bandgap materials

Calculations of the optical constants of hexagonal GaN (in the range 1-10 eV), InN (in the range 2-20 eV), A1N (in the range 6-20 eV) and 6H-SiC (in the range 1-30 eV) for the component perpendicular to the c axis are presented. The employed model is modified Adachi's model of the optical properties of semiconductors. In the employed model, damping constant rdescribing broadening phenomenon is replaced with the frequency dependent expression 1(w). In such a manner, type of broadening represents adjustable parameter of the model, allowing broadening to vary over a range of functions with similar kernels but different wings. Excellent agreement with experimental data is obtained for all investigated materials. Obtained relative rms errors for the real and imaginary parts of the index of refraction are equal to 3.5% and 5.2% for 6HSiC in the 1-30 eV range, 1 .7% and 4.1% for GaN in the 1.5-10 eV range, 1.2% and 2.5% for InN in the 2-10 eV range and 1 .5% and 1.9% for A1N in the 6-20 eV range.published_or_final_versio