共查询到20条相似文献,搜索用时 15 毫秒
1.
Different momentum space Faddeev-like equations and their solutions for the radiative pd-capture and the three-nucleon photodisintegration of 3He are presented. Applications are based on the AV18 nucleon-nucleon and the Urbana IX three-nucleon forces. Meson exchange currents are included using the Siegert theorem. A very good agreement has been found in all cases indicating the reliability of the used numerical methods. Predictions for cross-sections and polarization observables in the pd-capture and the complete three-nucleon breakup of 3He at different incoming-deuteron/photon energies are presented. 相似文献
2.
Pierre-Jean Nacher Eric Stoltz Geneviève Tastevin 《Czechoslovak Journal of Physics》1996,46(6):3025-3032
Laser optical pumping in low magnetic field provides very high nuclear polarizations in gaseous helium mixtures, and is used to prepare polarized liquid. Wall relaxation in glass cells is effiently reduced using cesium coatings, and bulk longitudinal relaxation times are measured. In highly magnetized samples, dipolar fields control the spin dynamics in anisotropic volumes and weak external magnetic field inhomogeneities. Long lived magnetostatic modes are observed by pulsed NMR. Detailed analysis of their frequency and damping gives information on magnetization density and spin diffusion coefficient in polarized mixtures. Experiments are performed above 0.2 K on mixtures with3He concentrations of order a few percents or larger. When phase separation occurs, the3He-rich phase retains a high polarization. 相似文献
3.
N. G. Peresadko Yu. A. Alexandrov S. G. Gerasimov V. A. Dronov V. G. Larionova A. V. Pisetskaya E. I. Tamm V. N. Fetisov S. P. Kharlamov L. N. Shesterkina 《Physics of Atomic Nuclei》2010,73(11):1942-1947
In a track nuclear photoemulsion exposed to a beam of 7Li nuclei accelerated to a momentum of 3 GeV/c per nucleon at the synchrophasotron of the Joint Institute for Nuclear Research (JINR, Dubna), 13 events in which 7Li nuclei interacting with protons break up into 3H and 4He fragments were detected among 3730 inelastic-interaction events. For this fragmentation channel, the cross section was
found to be 8 ± 2 mb. The average value of the fragment total transverse momentum was 214 ± 5 MeV/c. This value exceeds markedly the average value of the transverse-momentum transfer in the coherent dissociation of 7Li nuclei on track-emulsion nuclei (166±5MeV/c). The recoil-proton transverse momentum was on average 98% of the total proton momentum. The longitudinal-momentum distribution
of protons was characterized by a variance of 16 MeV/c and a mean value of 37 ± 2MeV/c. 相似文献
4.
A. V. Dolbin V. B. Esel’son V. G. Gavrilko V. G. Manzhelii N. A. Vinnikov S. N. Popov 《JETP Letters》2011,93(10):577-579
The kinetics of the sorption and subsequent desorption of gaseous 3He in a C60 fullerite powder has been studied in the temperature range of 2–292 K. The temperature dependences of the diffusion coefficients
of 3He and 4He impurities in fullerite have been plotted using the measured characteristic times of filling of octahedral and tetrahedral
interstices, as well as previous data. These temperature dependences of the diffusion coefficients of 3He and 4He impurities in fullerite are qualitatively similar. A decrease in the temperature from 292 to 79 K is accompanied by a decrease
in the diffusion coefficients, which corresponds to the dominance of the thermally activated diffusion of helium isotopes
in fullerite. A further decrease in the temperature to 8–10 K leads to an increase in the diffusion coefficients by more than
an order of magnitude. The diffusion coefficients of 3He and 4He are independent of the temperature below 8 K, indicating the tunnel character of the diffusion of helium in C60 fullerite. The isotope effect is manifested in the difference between the absolute values of the diffusion coefficients of
3He and 4He atoms at the same temperatures. 相似文献
5.
R. Kalpakchieva V. A. Maslov R. A. Astabatian A. A. Kulko S. M. Lukyanov E. R. Markarian Yu. Ts. Oganessian Yu. E. Penionzhkevich N. K. Skobelev Yu. G. Sobolev 《Physics of Atomic Nuclei》2007,70(4):619-625
Experimental data on the momentum distributions of 4He nuclei originating from 6He and 6Li breakup on various targets are presented over a wide beam energy range. The experiment with 6He was performed at the DRIBs accelerator complex for radioactive beams at the Joint Institute for Nuclear Research (JINR, Dubna). The intensity of the 6He beam used was 5 × 106 particles per second and its energy was 10 MeV per nucleon. The momentum distributions of breakup products were measured by means of the MSP-144 magnetic spectrometer. The distribution width was shown to be virtually independent of the target mass. A small value of this width, σ ~ 28 MeV/c, confirms the presence of a halo in 6He. The measurements performed with 6Li beams of energy 18 and 46 MeV per nucleon at the U-400M accelerator yielded a width value of σ ~ 50 MeV/c for the momentum distributions of 4He nuclei, which is intermediate between that for 6He and those for stable nuclei. A compilation of the widths of the momentum distributions of fragments originating from the breakup of various nuclei is presented versus the binding energy of one or two neutrons in these nuclei, the target mass and the projectile energy. 相似文献
6.
Within the framework of the single-channel approximation, an {αtd} model of the 9
Be nucleus is presented. A comparative analysis of the t 6
Li wave functions describing relative motion of bound states constructed in {ααn} and {αtd} cluster representations is carried out on the example of calculations of the 9
Be(γ,t0)6
Li process characteristics.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 85–89, January, 2008. 相似文献
7.
V. L. Tsymbalenko 《JETP Letters》2003,78(8):493-496
The kinetics of formation of an anomalous phase from a solution with a small 3He impurity was studied in the temperature range 0.2–0.7 K up to a supersaturation of ~30 mbar. The phase diagram was determined for normal and anomalous growths. It is found that, in the presence of impurities, the formation of a fast-growing state is retarded. This experimental fact indicates that the dissipative processes in fluids have an appreciable effect on the phase formation kinetics. The retardation is, possibly, caused by the direct interaction of an impurity with the crystal surface. 相似文献
8.
Awad A. Ibraheem 《Physics of Atomic Nuclei》2016,79(5):686-693
Elastic scattering of 4He+40Ca and 4He+44Ti reactions at backward angles has been analyzed using two differentmodels, microscopic and semimicroscopic folding potentials. The derived real potentials supplemented with phenomenological Woods–Saxon imaginary potentials, provide good agreement with the experimental data at energy Ec.m. = 21.8 MeV without need to renormalize the potentials. Coupledchannels calculations are used to extract the inelastic scattering cross section to the low-lying state 2+ (1.083 MeV) of 44Ti. The deformation length is obtained and compared with the electromagnetic measurement values as well as those obtained from previous studies. 相似文献
9.
10.
S. A. Rodenko I. K. Troitskaya A. G. Mayorov V. V. Malakhov 《Physics of Atomic Nuclei》2018,81(5):634-637
In the period from 2006 to 2016, experiments based on the use of the PAMELA and ARINA spectrometers and aimed at detecting cosmic rays were performed on board the RESURS-DK1 satellite. Although the main goal of these experiments was to study the galactic component of cosmic rays, the instruments in question also detected, over a broad energy range, solar particles accelerated in powerful explosive processes on the Sun (solar flares). A list of solar events in which the PAMELA and ARINA spectrometers detected, in various years of their operation, an increase in the intensities of fluxes of solar protons whose energies were above 45 MeV is presented among other things. 相似文献
11.
N. G. Peresad’ko V. N. Fetisov Yu. A. Aleksandrov S. G. Gerasimov V. A. Dronov V. G. Larionova E. I. Tamm S. P. Kharlamov 《JETP Letters》2008,88(2):75-79
The differential cross section in the transverse momentum Q and a total cross section of (31 ± 4) mb for the coherent dissociation of a 3-A-Ge V/c 7Li nucleus through the 3H + 4He channel have been measured on emulsion nuclei. The observed Q dependence of the cross section is explained by the predominant supposition of the nuclear diffraction patterns on light (C, N, O) and heavy (Br, Ag) emulsion nuclei. The contributions to the cross section from nuclear diffraction (Q ≤ 400 Me V/c) and Coulomb (Q ≤ 50 Me V/c) dissociations are calculated to be 40.7 and 4 mb, respectively. 相似文献
12.
Yu. B. Gurov M. N. Behr D. V. Aleshkin B. A. Chernyshev S. V. Lapushkin P. V. Morokhov V. A. Pechkurov N. O. Poroshin V. G. Sandukovsky M. V. Tel’kushev 《The European Physical Journal A - Hadrons and Nuclei》2005,24(2):231-236
The superheavy hydrogen isotopes 4H and 5H have been investigated in the stopped pion absorption on 9Be. Three states of 4H were proposed in the reaction channel 9Be( { - }, dt)X. Four states of 5H were proposed in the reaction channels 9Be({ - }, pt)X and 9Be({ - }, dt)X. The excited states of 5H can decay into free nucleons. 相似文献
13.
E. N. Elekina A. A. Krutov A. P. Martynenko 《Physics of Particles and Nuclei Letters》2011,8(4):331-336
On the basis of quasi-potential approach to the bound state problem in QED we calculate the vacuum polarization, recoil and
structure corrections of orders α5 and α6 to the fine splitting interval ΔE
fs = E(2P
3/2) − E(2P
1/2) in muonic 24He ion. The resulting value ΔE
fs = 146180.68 μeV provides reliable guideline in performing a comparison with the relevant experimental data. 相似文献
14.
A. F. Andreev L. A. Melnikovsky 《Journal of Experimental and Theoretical Physics》2017,124(6):920-923
The conditions for applicability of the mean field theory for describing the thermodynamics of the surface of 4He crystals are investigated based on analysis of experimental data. It is found that although the faceting phase transition itself is a Berezinsky–Kosterlitz–Thouless phase transition, the thermodynamic potential outside a narrow neighborhood of the transition temperature can be expanded into a series in terms of the Landau theory of second-order phase transitions. 相似文献
15.
16.
A. Duisebayev B. A. Duisebayev T. K. Zholdybayev B. M. Sadykov K. M. Ismailov E. I. Kabin 《Bulletin of the Russian Academy of Sciences: Physics》2016,80(8):894-897
The inclusive spectra of light charged particles formed upon interaction between 50.5 MeV 3Не ions and 27Al nuclei are studied. The experimental results are analyzed using the exciton model of nucleus decay, with the PRECO-2006 code describing the transition of an excited system to equilibrium state. The contributions from composite, pre-equilibrium, and direct processes of integral cross section formation are calculated. Determination of these mechanisms is of interest to both fundamental nuclear physics and different areas of application, particularly the nuclear transmutation of long-lived radioactive contamination. 相似文献
17.
S. M. Taova L. N. Generalov V. A. Zherebtsov 《Bulletin of the Russian Academy of Sciences: Physics》2018,82(6):626-631
procedure is considered for analyzing 3H(t,2n)4He reaction proceeding in a gas environment with regard to electron screening [1–4]. Results from such an analysis are presented. An electron screening potential of 121 eV is obtained. The magnitude of this potential is three times higher than the one given in [5]. Starting with a 100 eV energy of particle interaction the cross sections of 3H(t,2n)4He reaction are calculated using the above potential. The reaction rates are calculated using the evaluated cross sections in the lowenergy region. Enhancement factors for cross sections and reaction rates are defined. 相似文献
18.
We present the elastic scattering of the 6He+208Pb and the 6He+197Au systems at the laboratory energy of E
lab=27 MeV within the framework of the McIntyre parametrization, and systematically investigate χ
2/N analysis of both systems to obtain an excellent agreement between the theoretical results and the experimental data. We find
large diffusivity parameters indicating long range absorption mechanisms. We also show that both systems lack both the nuclear
and the Coulomb rainbow scattering for obtained S-matrix parameters. 相似文献
19.
The mechanism of transition between bcc and hcp phases, which is applicable to both classical and quantum crystals, has been considered at the microscopic level. The relative orientations of the lattices that provide coherent phase matching are specified. It is suggested that phase boundaries are coherent and atomic displacements do not exceed the unit-cell size. A new order parameter—relative displacement of atomic layers—is introduced. The phase boundary is described within the double-and triple-well potential models. The relationship of the lattice constant and barrier height with the parameters of these potentials has been found, as well as the shape and energy of the phase boundary. A mechanism leading to a decrease in the barrier height for the phase boundary in a quantum crystal is proposed. This mechanism makes it possible to explain the results of recent experimental investigations of the nucleation occurring during the bcc-hcp transition in solid 4He. 相似文献