The H7 system was populated in the H2(He8,He3)H7 reaction with a 26 AMeV He8 beam. The H7 missing mass energy spectrum, the H3 energy and angular distributions in the H7 decay frame were ...reconstructed. The H7 missing mass spectrum shows a peak, which can be interpreted either as unresolved 5/2+ and 3/2+ doublet or one of these states at 6.5(5) MeV. The data also provide indications of the 1/2+ ground state of H7 located at 1.8(5) MeV with quite a low population cross section of ∼25 μb/sr within angular range θc.m.≃(17°-27°).
Knowledge of the low-lying monopole strength in C12—the Hoyle state in particular—is crucial for our understanding of both the astrophysically important 3α reaction and of α-particle clustering. ...Multiple theoretical models have predicted a breathing mode of the Hoyle State at Ex≈9 MeV, corresponding to a radial in-phase oscillation of the underlying α clusters. The C12(α,α′)C12 and C14(p,t)C12 reactions were employed to populate states in 12C in order to search for this predicted breathing mode. A self-consistent, simultaneous analysis of the inclusive spectra with R-matrix lineshapes, together with angular distributions of charged-particle decay, yielded clear evidence for excess monopole strength at Ex≈9 MeV which is highly collective. Reproduction of the experimentally observed inclusive yields using a fit, with consistent population ratios for the various broad states, required an additional source of monopole strength. The interpretation of this additional monopole resonance as the breathing-mode excitation of the Hoyle state would provide evidence supporting a D3h symmetry for the Hoyle state itself. The excess monopole strength may complicate analysis of the properties of the Hoyle state, modifying the temperature dependence of the 3α rate at T9≳2 and ultimately, the predicted nucleosynthesis in explosive stars.
The proton and deuteron pickup reactions
and
were studied with the
radioactive beam produced by the new fragment separator ACCULINNA-2 at FLNR, JINR. These measurements were initially motivated as ...the test reactions intended for the elucidation of results obtained in the study of the extremely neutron-rich
H and
H systems created in the
and
reactions with the use of the same setup. In the
reaction the
Li ground-state (
) and its first excited state (2.69 MeV,
) were identified in the low-energy region of its excitation spectrum. The differential cross sections for the
population were extracted at the forward center-of-mass angles (
) and compared with the FRESCO calculations. Spectroscopic factor of
, derived by a model suggesting the
clustering was found in accord with the experimental data. The energy spectrum of
Li populated in the
reaction shows the strong peak which corresponds to the excitation of the second excited state of
Li (2.25 MeV,
). The fact that the ground and the first excited states of
Li were not observed in this reaction is consistent with the shell-model structure of the nuclei involved.
Setup fitting the requirements for the detailed study of the five-body decay of the
7
H nucleus obtained as a result of the proton transfer from the
8
He projectiles to the deuterium target nuclei is ...being built at the radioactive beam line of ACCULINNA-2 separator in the G.N. Flerov Laboratory of Nuclear Reactions. Described here is the assembly of 100 BC-404 plastic scintillators, intended for neutron detection, the annular Si detector telescope for the
3
He recoils, and the detector array providing the Δ
E
–
E
-TOF registration of
3
H nuclei emitted at the
7
H decay. Results obtained by the Monte Carlo simulations made for the energy values and flight passes of all these particles are given together with the luminosity expected for the discussed experiments.
The main presynaptic mechanisms of synaptic plasticity are generally believed to consist of changes in the numbers of neurotransmitter quanta released in response to a nerve spike (the quantum ...composition of postsynaptic responses) and quantum size. However, studies in recent years have demonstrated the existence of a further, previously unconsidered but effective mechanism modulating the synaptic transmission of excitation, which is associated with changes in the secretion time course (kinetics) of the release of the individual quanta forming the multiquantum postsynaptic response. This review discusses current data (including our own results) on the kinetics of the evoked release of neurotransmitter quanta from motor nerve endings in peripheral synapses, the mechanisms of its modulation, and quantitative methods for its analysis.
Quasi-elastic, multi-nucleon transfer reactions induced by the radioactive-ion beams with energy 4–6 MeV/u allow one to produce moderately excited neutron-rich nuclei with atomic numbers
. This ...offers a new approach to the study of the so far unknown nuclei in the neighborhood of the recently discovered island of super-heavy elements and to the acquirement of new data specifying significant fission characteristics of the actinide nuclei appearing in the r-process nucleosythesis.
Myelinated fibers and myelin-forming cells in the spinal cord at the L3–L5 level were studied in C57BL/6N mice that had spent 30 days in space. Signs of destruction of myelin in different areas of ...white matter, reduction of the thickness of myelin sheath and axon diameter, decreased number of myelin-forming cells were detected in “flight” mice. The stay of mice in space during 30 days had a negative impact on the structure of myelinated fibers and caused reduced expression of the markers myelin-forming cells. These findings can complement the pathogenetic picture of the development of hypogravity motor syndrome.
The one-neutron transfer
2
H(
9
Li,
p
)
10
Li reaction has been investigated at 29
A
MeV incident energy at the ACCULINNA-2 facility (Flerov Laboratory of Nuclear Reactions, Joint Institute for ...Nuclear Research). The setup has been used in order to detect the recoil protons at backward angles in coincidences with the outgoing
9
Li and neutrons from the
10
Li decay at forward angles. This setup allows to study the
10
Li emitted in the crucial region at forward angles in the center of mass. The preliminary results in the part of the analysis of double proton–
9
Li coincidence are reported.
Investigation of the
7
H-system in the experiment conducted at the fragment separator ACCULINNA-2 in the
8
He(
2
H,
3
He)
7
H reaction requires to detect the recoil
3
He ions with energy down to 6 ...MeV. For this purpose two
particle telescopes are used, with each telescope having in front a thin (20-μm) Si strip detector (
). The maps of thickness heterogeneity of the thin detectors were determined by measuring the energy losses of the
226
Ra α-particles. The adopted thickness normalization method provides a good identification of the
3
He nuclei being recorded in the presence of a high
4
He background. Two approaches were used for calculating the energy losses of the identified
3
He and
4
He reaction ejectiles and reconstructing their energy values available at the exit from the deuterium target. The developed techniques were applied for the
7
H missing-mass reconstruction.
The commissioning of the new fragment separator ACCULINNA-2 at FLNR JINR is accomplished. The separator is destined to expand the possibilities in studies of dripline nuclei performed with the exotic ...secondary radioactive ion beams (RIBs) at energies of (5 - 50) AMeV. The projected high transmission and purification level were confirmed experimentally for a number of RIBs in the last two years. The ACCULINNA-2 setup will become a backbone facility at FLNR for the research in the field of light exotic nuclei. This report shows the current status of the separator, describes the obtained RIBs parameters and first experiments as well, provides the overview of the developing detection, monitoring and control subsystems.
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