Potassium-48

The decay of ⁴⁸K has been studied for the first time. This activity was produced by means of the ⁴⁸Ca(n,p) reaction with 14 MeV neutrons. A group of five levels in ⁴⁸Ca near 7 MeV accounts for ∽ 75% of the ⁴⁸K β-decay strength.     

Simple Zeros of the Riemann Zeta-Function

Assuming the Riemann Hypothesis, Montgomery showed by meansof his pair correlation method that at least two-thirds of thezeros of Riemann's zeta-function are simple. Later he and Taylorimproved this to 67.25 percent and, more recently, Cheer andGoldston increased the percentage to 67.2753. Here we proveby a new method that if the Riemann and Generalized LindelöofHypotheses hold, then at least 70.3704 percent of the zerosare simple and at least 84.5679 percent are distinct. Our methoduses mean value estimates for various functions defined by Dirichletseries sampled at the zeros of the Riemann zeta-function. 1991Mathematics Subject Classification: 11M26.     

Existence and Uniqueness of Fixed Points for Markov Operators and Markov Processes

This paper concerns a Markov operator T on a space L₁, and aMarkov process P which defines a Markov operator on a spaceM of finite signed measures. For T, the paper presents necessaryand sufficient conditions for:

a the existence of invariant probabilitydensities (IPDs)

b the existence of strictly positive IPDs,and

c the existence and uniqueness of IPDs.

Similar resultson invariant probability measures for P are presented. The basicapproach is to pose a fixed-point problem as the problem ofsolving a certain linear equation in a suitable Banach space,and then obtain necessary and sufficient conditions for thisequation to have a solution. 1991 Mathematics Subject Classification:60J05, 47B65, 47N30.     

库仑加线性位基态解析解

应用新发展的单一轨迹积分方法求解库仑加线性位的基态量子波函数,得到基态能量和波函数的一般解析表达式,并讨论了解的收敛性.应用此方法讨论了重夸克偶素系统.     

A comparison between shell-model configuration mixing calculations and the MCHF model in the ground state rotational spectra of 20Ne, 22Ne and 24Mg

Shell-model and multi-configuration Hartree-Fock (MCHF) calculations in an $\text{Od}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{-1s}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ oscillator basis are compared for ²⁰Ne, ²²Ne and ²⁴Mg. The similarity of the calculated results in the two models shows that the MCHF method is a very good approximation to the shell-model calculations.     

Population of high spin states in 22Na by means of the 10B(16O, α) reaction

Strong selectivity has been observed in the population of states in ²²Na up to high excitation energies. Angular distributions were measured, and a comparison with Hauser-Feshbach calculations allow us to select strong candidates for the high-spin members of the K^π = 3⁺, T = 0 and K^π = 0⁺, T = 0 bands in ²²Na.