Charge exchange reactions on light and heavy ion beams are of interest in the production of new isotopes, and for studying the properties of radioactive and stable atomic nuclei. A charge exchange ...reaction (
3
He,
t
) has advantages over other types of reactions, due to much easier identification of charged particles
t
. The cross sections of reactions on
3
He reach hundreds of mbarn at an energy of the bombarding beam near the Coulomb barrier. These reactions result in excitation of the isobar analog and other single particle states in residual nuclei.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Abstract
Laser-produced plasmas are bright, short sources of x-rays commonly used for time-resolved imaging and spectroscopy. Their usage implies accurate knowledge of laser-to-x-ray conversion ...efficiency (CE), spectrum, photon yield and angular distribution. Here, we report on soft x-ray emission in the direction close to the target normal from a thin Si foil irradiated by a sub-PW picosecond laser pulse. These absolute measurements cover a continuous and broad spectral range that extends from 4.75 to 7.3 Å (1.7–2.6 keV). The x-ray spectrum consists of spectral line transitions from highly charged ions and broadband emission with contributions from recombination and free-free processes that occur when electrons decelerate in plasma electromagnetic fields. Angular distribution of the emission was investigated via particle-in-cell simulations, which allowed to estimate the yield into the full solid angle. We find that experimental and simulation estimations of laser to free-free emission CE are in good agreement.
The results of experiments performed at a high-resolution magnetic spectrometer (MAVR) are presented. The differential production cross sections for oxygen isotopes in the
Ta reaction at the ...projectile energy of 10 MeV per nucleon were measured at the MAVR facility. The yield of reaction products is analyzed theoretically in the finite-range distorted-wave Born approximation (FR-DWBA method) by means of the FRESCO code. The theoretical differential cross sections are calculated for sequential neutron transfer. The contributions of the mechanisms of sequential neutron transfer and dineutron-cluster transfer to the production cross sections for the neutron-rich oxygen isotopes
O are studied.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Experiments devoted to studying cross sections for fusion and transfer reactions induced by the interaction of beams of halo-like (
6
He), cluster (
6
Li and
7
Li), and loosely bound (
3
He) nuclei ...with nuclei of light and heavy elements are described. The cross sections obtained experimentally for such reactions are analyzed. Special features in the behavior of the cross sections for the formation of evaporation residues and products of transfer reactions at energies in the vicinity of the Coulomb barrier are revealed. In particular, an increase in the cross sections for fusion and transfer reactions involving halo-like nuclei and proceeding at energies in the subbarrier region is observed. The cross sections for neutron-transfer and light-cluster-transfer reactions reachmaximum values at an energy in the vicinity of the Coulomb barrier for the reaction being considered.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
A project of the high-resolution magnetic analyzer MAVR is proposed. The analyzer will comprise new magnetic optical and detecting systems for separation and identification of reaction products in a ...wide range of masses (5-150) and charges (1-60). The magnetic optical system consists of the MSP-144 magnet and a doublet of quadrupole lenses. This will allow the solid angle of the spectrometer to be increased by an order of magnitude up to 30 msr. The magnetic analyzer will have a high momentum resolution (10-4) and high focal-plane dispersion (1.9 m). It will allow products of nuclear reactions at energies up to 30 MeV nucleon to be detected with the charge resolution ∼1 60. Implementation of the project is divided into two stages: conversion of the magnetic analyzer proper and construction of the nuclear reaction products identification system. The MULTI detecting system is being developed for the MAVR magnetic analyzer to allow detection of nuclear reaction products and their identification by charge Q, atomic number Z, and mass A with a high absolute accuracy. The identification will be performed by measuring the energy loss (ΔE), time of flight (TOF), and total kinetic energy (TKE) of reaction products. The particle trajectories in the analyzer will also be determined using the drift chamber developed jointly with GANIL. The MAVR analyzer will operate in both primary beams of heavy ions and beams of radioactive nuclei produced by the U400 - U400M acceleration complex. It will also be used for measuring energy spectra of nuclear reaction products and as an energy monochromator.
Calculations of production cross sections for isotopes
194
Au in the
3
He +
194
Pt reaction and
45
Ti in the
3
He +
45
Sc reaction are performed, based on the solution to a time-dependent Schrödinger ...equation in combination with calculations in the statistical model using the computational code of the NRV data base. The experimental differences in the near-barrier energy dependences of the isotope production cross sections in these reactions are explained by the difference between the proton and neutron shells of the target nuclei, and by the different evolutions of the probability density for protons of the projectile nucleus and neutrons of the target nuclei in collisions.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Theoretical description of the experimental data on the formation of various isotopes in reactions (3He+194Pt) and (3He+45Sc) requires taking into account neutron and proton transfer channels, as ...well as fusion-evaporation channels. To calculate the probabilities of nucleon transfer as well as transfer cross sections the time-dependent Schrodinger equation (TDSE) has been solved numerically. Fusion- evaporation was taken into account using the statistical model code of the NRV web knowledge base. Results of calculations are in agreement with experimental data.
Experimental cross sections for formation of isotopes 44,46 Sc - in reaction ( 3 He + 45 Sc), 46 Sc - in reaction ( 6 He + 45 Sc), 65 Zn - in reaction ( 3 He + 64 Zn), 196,198 Au - in reactions ( 3,6 ...He + 197 Au) have been analyzed within the TDSE approach for the external neutrons of 3,6 He, 45 Sc and 197 Au nuclei. Fusion-evaporation was taken into account using the NRV evaporation code. Results of calculation demonstrate overall satisfactory agreement with the experimental data
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