On the distribution of the fluctuating reaction cross section

Exact formula for the statistical distribution function of the fluctuating cross section is presented. Comparison with the results obtained from the approximate formula shows that such a formula can be used for calculation of the cumulative distribution function in the range of its values from 0.01 to 0.99

Parametrization of cross sections for neutron interaction with 1^{1}H, 2^{2}H and 12^{12}C nuclei at energies between 20 and 90 MeV

The experimental data for neutron interaction with $^{1}$H, $^{2}$H and $^{12}$C nuclei are parametrized in energy range 20 to 90 MeV. The energy dependence of the total and reaction cross section is represented in the form of a series of orthogonal polynomials. The logarithm of differential cross section for the angular distribution is expressed as a linear combination of Legendre polynomials with the energy dependence of their coefficients described by a series of orthogonal polynomials

Investigation of nucleon - unbound states in 29 Si and 29 P by the reaction 28 Si (d, pn)

The deuteron break-up reaction is a good tool to study nucleon unbound states o f atomic nuclei [1, 2]. In the present paper we are studying the proton unbound states o f 29P and the neutron unbound states o f 29Si via the 28Si(d, p n )28Si reaction. The experimental results and an analysis limited to the most prominent peaks in the spectra o f this reaction were published in an earlier work [3], Now an extended analysis is presented, based on the “ summed spectra” method [4] which enables us to identify even weak states in complicated spectra

Study of the mechanism of the five-nucleon transfer reaction 12^{12}C(13^{13}C, 8^{8}Be)17^{17}O

Excitation functions (E$_{cm}$ = 13.4 - 16.8 MeV) and angular distributions (E$_{cm}$ = 13.8 and 16.38 MeV) of $^{12}$C($^{13}$C, $^{8}$Be)$^{17}$O reaction have been measured and analysed by means of statistical and direct reaction mechanism models. The direct reaction analysis includes one and two step processes. For this purpose measurements and analyses were also performed for the reactions $^{12}$C($^{13}$C, $^{9}$Be)$^{16}$O (at E$_{cm}$ = 13.8 MeV) and $^{16}$O($^{9}$Be, $^{8}$Be)$^{17}$O (at E$_{cm}$ = 10.3 and 12.8 MeV). The results were used to estimate the magnitude of the direct two-step (n-$^{4}$He) and ($^{4}$He-n) transfers in the $^{12}$C($^{13}$C, $^{8}$Be)$^{17}$O reaction. These two-step transfers as well as the compound nucleus mechanism, account only for approximately 10% of the experimental cross sections. Thus a dominance of the one-step five-nucleon transfer is concluded. Estimates of the direct $^{5}$He-cluster transfer describe the data qualitatively

Search for the 3He-eta bound state at COSY-11

We have measured excitation function for dp -> ppp_pi- reaction near the eta production threshold. We observe an enhancement of the counting rate above the threshold which can originate from the production of the eta meson in the reaction dp -> 3He eta and its subsequent absorption on neutron in the 3He nucleus leading to creation of the p_pi- pair.Comment: Presented at 10th International Workshop on Meson Production, Properties and Interaction (MESON 2008), Cracow, Poland, 6 - 10 June 2008, 4 pages, 4 figures,references adde

On the invariance equation for two-variable weighted nonsymmetric Bajraktarevi\'c means

The purpose of this paper is to investigate the invariance of the arithmetic mean with respect to two weighted Bajraktarevi\'c means, i.e., to solve the functional equation $$\bigg(\frac{f}{g}\bigg)^{\!\!-1}\!\!\bigg(\frac{tf(x)+sf(y)}{tg(x)+sg(y)}\bigg) +\bigg(\frac{h}{k}\bigg)^{\!\!-1}\!\!\bigg(\frac{sh(x)+th(y)}{sk(x)+tk(y)}\bigg)=x+y \qquad(x,y\in I),$$ where $f,g,h,k:I\to\mathbb{R}$ are unknown continuous functions such that $g,k$ are nowhere zero on $I$, the ratio functions $f/g$, $h/k$ are strictly monotone on $I$, and $t,s\in\mathbb{R}_+$ are constants different from each other. By the main result of this paper, the solutions of the above invariance equation can be expressed either in terms of hyperbolic functions or in terms of trigonometric functions and an additional weight function. For the necessity part of this result, we will assume that $f,g,h,k:I\to\mathbb{R}$ are four times continuously differentiable

Isospin dependence of the eta' meson production in nucleon--nucleon collisions

According to the quark model, the masses of eta and eta' mesons should be almost equal. However, the empirical values of these masses differ by more than the factor of two. Similarly, though the almost the same quark-antiquark content, the total cross section for the creation of these mesons close to the kinematical thresholds in the pp --> ppX reaction differs significantly. Using the COSY-11 detection setup we intend to determine whether this difference will also be so significant in the case of the production of these mesons in the proton-neutron scattering. Additionally, the comparison of the pp --> pp eta' and pn --> pn eta' total cross sections will allow to learn about the production of the eta' meson in the channels of isospin I = 0 and I = 1 and to investigate aspects of the gluonium component of the eta' meson.Comment: Presented at LEAP05: International conference on Low Energy Antiproton Physics, Bonn - Juelich, Germany, May 16-22, 200

Isospin dependence of the eta prime meson production in nucleon-nucleon collisions

A comparison of the close-to-threshold total cross section for the eta prime production in pp --> pp eta prime and pn --> pn eta prime reactions constitutes a tool to investigate the eta prime meson structure and the reaction mechanism in the channels of isospin I=0 and I=1 and may provide insight into the flavour-singlet (perhaps also into gluonium) content of the eta prime meson. In this contribution we present preliminary results of measurement of the quasi-free production of the eta prime meson in the proton-neutron collisions conducted using the COSY-11 facility.Comment: Presented at 10th International Workshop on Meson Production, Properties and Interaction (MESON 2008), Cracow, Poland, 6 - 10 June 200

COSY-11: an experimental facility for studying meson production in free and quasi-free nucleon-nucleon collisions

The COSY-11 experimental setup is an internal facility installed at the COoler SYnchrotron COSY in Juelich. It allows to investigate meson production in free and quasi-free nucleon-nucleon collisions, eg. pp --> pp meson and pd --> p_sp np meson reactions. Drift chambers and scintillators permit to measure outgoing protons, separated in magnetic field of COSY-11 dipole. Neutrons are registered in the neutron modular detector installed downstream the beam. Recently, the experimental setup has been extended with spectator detector, deuteron drift chamber and polarization monitoring system, and since then meson production can be investigated also as a function of spin and isospin of colliding nucleons.Comment: Presented at LEAP05: International conference on Low Energy Antiproton Physics, Bonn - Juelich, Germany, May 16-22, 200