[en] The angular distributions of protons channeled in a tilted <111> Si very thin crystal together with the corresponding rainbow patterns are considered. The proton energy is 10 MeV while the crystal thickness is 121.1 nm, corresponding to the reduced crystal thickness of 0.15. The tilt angle of the crystal is varied from zero up to the critical angle for channeling. The angular distributions were obtained using the numerical solution of the proton equations of motion and the computer simulation method. The rainbow lines were determined by applying the theory of crystal rainbows. The analysis has shown that the evolution of the angular distribution with the tilt angle can be fully explained by the evolution of the crystal rainbow. We have discovered that the crystal rainbow effect turns into the well-know doughnut effect in ion channeling for the larger values of the tilt angle. The interior of the doughnut is the analogue of the Alexander's dark band, which occurs in between the primary and secondary meteorological rainbows

[en] The program is an aid in the analysis of one-dimensional nuclear data (e.g., γ-ray spectra). It can however be used in all cases where histogram-type data with Poisson Statistics is analyzed. Interactive computation is employed. A portion of the data is displayed on a CRT-screen, the area of interest is indicated with the lightpen and various processing commands are executed by changing the state of the ACCUMULATOR SWITCHES. A log of all operations and results is printed on the teletype. Commands already programmed are: Control of I/O, polynomial fit to background, centroid and area of peaks, multiple (1 to 3) gaussian fit. The correct statistical errors are computed and printed along with the parameter values. (Auth.)

[en] In most nuclear physics calculations sets of real numbers are used (e.g. eigenvectors, coefficient vectors) which are characterized by a set of quantum numbers. For the fast retrieval of the vectors, the quantum numbers can usually be encoded to an index and the vectors stored in direct access files. This method, however, is costly in disc space, since the vectors have variable length. A solution is needed which will combine the fast retrieval characteristic of direct access with the economy of space of sequential access files. (orig.)

[en] In a space defined by several single-particle orbitals antisymmetric states for any n-fermion system can be expanded in terms of states which are antisymmetric only with respect to the first m and the last (n - m) particles. These (m, n - m) expansion coefficients, the generalized fractional parentage coefficients (gfpc), can then be used to determine easily the matrix elements of any m-body operator. The states are classified according to Csup(n) which denotes the distribution of the n particles among the orbitals, their total angular momentum J and isospin T and an index μ that distinguishes the orthogonal states that have the same Csup(n), J, T values. Program GFPC1 constructs the coefficients for m=1, the (1, n - 1) gfpc. It shares its long write-up with program GFPCM which calculates the (m, n - m) gfpc for 2<=m<=n. (orig.)

[en] A method for Cu and S profiling in patina layers was developed by applying a combination of nuclear reaction analysis (NRA) and Rutherford backscattering spectroscopy (RBS). The copper profiling was performed by using the 1327 keV γ-ray deexciting the third excited state to the ground state of ⁶³Cu produced by the reaction ⁶³Cu(p,p^'γ)⁶³Cu. For the determination of sulphur the 2230 keV γ-ray was used deexciting the first excited state to the ground state of ³²S formed through the reaction ³²S(p,p^'γ)³²S, which exhibits three sharp resonances at projectile energies 3.094, 3.195 and 3.379 MeV. The relevant cross-sections were measured in the energy range between 3.0 and 3.7 MeV in steps of 20 keV at 125 deg. to the incident proton beam direction. The technique was tested using artificially produced and natural copper patina layers. Supporting information on the depth distribution of the constituent elements of the patina samples was obtained by p-RBS (E_p: 1.5 MeV, θ: 160 deg.)

[en] Several SiC polytype crystals (namely 4H, 6H, 15R, 21R) were measured by means of pulsed-EPR and conventional CW-EPR spectroscopy. The experimental spectra were taken and analyzed. Computer simulations proved the existence of a strong signal originating from the high nitrogen dopant concentration. The results obtained are correlated with values existing in literature, concerning the two crucial channeling parameters, λ, the mean channeling distance and, α, the ratio of the stopping powers in the aligned and random mode for the same polytype structures. An attempt is also made to extend the study to other crystals and crystallographic structures

[en] The flux of the neutrons produced in a gas cell, via the D(d, n) reaction, was measured employing a silicon semiconductor detector. Monte Carlo techniques were used to simulate the energy distribution of the neutrons hitting the detector and the energy spectra induced by the neutrons in the silicon detector. The energy spectra were simulated using the neutron energy distribution obtained from the Monte Carlo calculation, and the pulse height defect values for the Si, Al and Mg ions calculated according to the nuclear stopping theory. The energy spectra thus simulated reproduced well the position and shape of the measured energy peaks in the silicon detector. (orig.)

[en] Reaction mechanisms populating the exit channels of the system ⁷Li+⁵¹V were studied at a beam energy of 18 MeV. Final nuclei were detected by their characteristic γ-rays. These γ-rays in coincidence with light charged particles were used to identify the reaction channels. Also forward-backward asymmetries of the coincident events gave a measure of the contribution of direct and compound reaction mechanisms. It was found that the dominant mechanism feeding channels with charged particles in the final state is direct transfer of a triton or α particle. (orig.)

[en] An ADC multiplexor is presented which interfaces four nuclear ADCs to the NE-9082 memory unit and through CAMAC to the RPIME-750 computer. Software aspects are also presented. (orig.)

[en] An interesting field of application of ion beam analysis techniques is the non-destructive examination of corrosion layers on cultural artifacts. This study is impeded by the non-uniformity of such layers, which renders the analysis difficult and requires the use of a combination of experimental techniques and analytical algorithms. In the present case, ancient glass fragments from Kenchreai, Greece, were analyzed with ion beam techniques, in order to examine the applicability of the latter to the characterization of the surface. The relative distribution of heavy components was determined by X-ray fluorescence. Nuclear reactions were used to determine the depth distribution of H, O, C and Si. Examination of the same samples with α-particles, indicates a depletion of silicon in the surface region of high hydrogen concentration, while the oxygen distribution is uniform. A detailed analysis, using the ²⁸Si(p, p) reaction, which resonates at 2.095 MeV, confirms the depletion and other non-uniformities in the silicon distribution