Quasifission at extreme sub-barrier energies

With the quantum diffusion approach the behavior of the capture cross-section is investigated in the reactions $^{92,94}$Mo + $^{92,94}$Mo, $^{100}$Ru + $^{100}$Ru, $^{104}$Pd + $^{104}$Pd, and $^{78}$Kr + $^{112}$Sn at deep sub-barrier energies which are lower than the ground state energies of the compound nuclei. Because the capture cross section is the sum of the complete fusion and quasifission cross sections, and the complete fusion cross section is zero at these sub-barrier energies, one can study experimentally the unique quasifission process in these reactions after the capture.Comment: 3 pages, 3 figure

Non-Markovian dynamics with fermions

Employing the quadratic fermionic Hamiltonians for the collective and internal subsystems with a linear coupling, we studied the role of fermionic statistics on the dynamics of the collective motion. The transport coefficients are discussed as well as the associated fluctuation-dissipation relation. Due to different nature of the particles, the path to equilibrium is slightly affected. However, in the weak coupling regime, the time-scale for approaching equilibrium is found to be globally unchanged. The Pauli-blocking effect can modify the usual picture in open quantum system. In some limits, contrary to boson, this effect can strongly hinder the influence of the bath by blocking the interacting channels.Comment: 13 pages, 6 figures. Submitted to PR

Neutron pair transfer in sub-barrier capture process

The sub-barrier capture reactions following the neutron pair transfer are proposed to be used for the indirect study of neutron-neutron correlation in the surface region of nucleus. The strong effect of the dineutron-like clusters transfer stemming from the surface of magic and non-magic nuclei $^{18}$O, $^{48}$Ca, $^{64}$Ni, $^{94,96}$Mo, $^{100,102,104}$Ru, $^{104,106,108}$Pd, and $^{112,114,116,118,120,124,132}$Sn is demonstrated. The dominance of two-neutron transfer channel at the vicinity of the Coulomb barrier is further supported by time-dependent mean-field approaches.Comment: 17 pages, 7 figures, accepted in PR

Disagreement between capture probabilities extracted from capture and quasi-elastic backscattering excitation functions

Experimental quasi-elastic backscattering and capture (fusion) excitation functions are usually used to extract the s-wave capture probabilities for the heavy-ion reactions. We investigated the $^{16}$O+$^{120}$Sn,$^{144}$Sm,$^{208}$Pb systems at energies near and below the corresponding Coulomb barriers and concluded that the probabilities extracted from quasi-elastic data are much larger than the ones extracted from fusion excitation functions at sub and deep-sub barrier energies. This seems to be a reasonable explanation for the known disagreement observed in literature for the nuclear potential diffuseness derived from both methods.Comment: 9 pages, 3 figure

The genus Crataegus (Rosaceae) in Armenia (an updated review)

The Rosaceae family plays a leading role in the dendroflora of Armenia. The Pyrus, Sorbus, Crataegus, Cotoneaster, Rubus and Rosa genera representing the family are of great importance in Armenia in the formation of various plant coexistences. With its species composition and taxonomic diversity, Crataegus is one of the largest genera in the Rosaceae family. Growing in Armenia in low, medium and high mountain zones, Crataegus has a great role in the formation of dendroflora: they are an important element of a number of forest coexistences, form a sub-forest with other representatives of dendroflora, grow in arid sparse forests, scrub, shoreline areas of mountain rivers. Crataegus is a valuable plant resource. Some species produce tasty and nutritious fruits that are rich in sugars, organic acids, mineral salts and vitamins. Since ancient times, the people of Armenia have used it in food and folk medicine, for example there is a decoction of hawthorn root and bark dyed threads. Currently, Crataegus has great economic importance. Drought-resistant and frost-resistant species are used as grafts for obtaining high-value varieties of apple, pear, and quince, decorative species are suitable for greening cities and settlements, creating living fences. Furniture and carpentry tools are made from its hard and strong natural wood. Due to their hardiness, some species of Crataegus are promising for the creation of arid arboretums in the lower and middle mountain zones of Armenia. In Armenia the genus Crataegus is represented by 23 species belonging to three sections: Crataegus, Pentagynae C. K. Schneid. and Azaroli Loud. Species C. ulotricha Pojark. ex Gladkova, C. razdanica Pojark. ex Sargsyan, C. gabrielianae Pojark. ex Sargsyan, C. susanykleinae Gabrieljan et Sargsyan and C. gregorianii Gabrielian et Sargsyan are endemic to Armenia. An updated key is provided to identify species based on new data. Altitudinal and geographical distribution of species, habitat, flowering and fruiting time are given

Sub-barrier capture reactions with 16,18^{16,18}O and 40,48^{40,48}Ca beams

Various sub-barrier capture reactions with beams $^{16,18}$O and $^{40,48}$Ca are treated within the quantum diffusion approach. The role of neutron transfer in these capture reactions is discussed. The quasielastic and capture barrier distributions are analyzed and compared with the recent experimental data.Comment: 8 pages, 9 figures, will be published in EPJA. arXiv admin note: substantial text overlap with arXiv:1211.433