共查询到20条相似文献,搜索用时 31 毫秒
1.
A. Ya. Silenko 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2012,6(1):176-181
General relations describing the spin dynamics of beams of nuclei with initial tensor and vector polarizations have been derived
upon planar channeling in bent crystals. The performed analysis indicates that the vector polarization effect predicted by
Baryshevsky and Sokolsky can be detected, occurring upon the planar channeling of a beam of nuclei with initial tensor polarization.
The planar channeling of a beam of nuclei with initial tensor and vector polarizations can be used to determine the quadrupole
moments of unstable nuclei with small lifetimes, up to 10−7 s. The quadrupole moments of nuclei with lifetimes of about 10−7 s cannot be measured via known methods, including optical methods. 相似文献
2.
P. Lievens R. E. Silverans L. Vermeeren E. Arnold W. Borchers W. Neu R. Neugart K. Wendt F. Buchinger E. B. Ramsey G. Ulm 《Hyperfine Interactions》1990,59(1-4):161-164
Nuclear spins, moments and mean square charge radii of78–100Sr have been obtained by fast ion-beam collinear laserspectroscopy. The experiments performed at ISOLDE have been extended
to include99Sr, measured by a non-optical detection scheme with a two-step optical pumping sequence. The results for the strongly deformed
isotopes are discussed in the frame of the particle-plus-deformed core model. 相似文献
3.
Magnetic moments of decuplet baryons have been calculated in a relativistic independent quark model with a phenomenological
potential in equally mixed scalar-vector harmonic form. Such a model has been successful in describing wide ranging hadronic
phenomena in mesonic and baryonic sectors. Using the solutions of the constituent quark orbitals with the model parameters
taken from its earlier applications, the magnetic moments of decuplet baryons Δ++ and Ω− have been obtained which are in good agreement with the available experimental data. However, the agreement is found to be
much better when the magnetic moment ratios such as μδ++/μ
p and μΩ-/μΛ are considered. Model predictions for the magnetic moments of other decuplet baryons together with the charge radii have
also been calculated which may be verified in future experiments. 相似文献
4.
Xianwen Zhang 《Journal of statistical physics》2010,141(3):566-588
Global-in-time existence of weak solutions to the Cauchy problem of the three dimensional Vlasov-Poisson-BGK system is shown
for initial data belonging to the space L
p
(ℝ3×ℝ3) with p>9 and having finite second order velocity moments. This result solves partially the well-posed problem for the Vlasov-Poisson-BGK
system proposed by B. Perthame: “Higher moments for kinetic equations: the Vlasov-Poisson and Fokker-Planck cases,” Math.
Meth. Appl. Sci. 13:441–452, 1990. 相似文献
5.
K. Azizi 《The European Physical Journal C - Particles and Fields》2009,61(2):311-319
Due to the very short life time of the Δ baryons, a direct measurement on the electromagnetic moments of these systems is almost impossible in the experiment and
can only be done indirectly. Although only for the magnetic dipole moments of Δ
++ and Δ
+ systems there are some experimental data, the theoretical, phenomenological and lattice calculations could play crucial role.
In the present work, the magnetic dipole (μ
Δ
), electric quadrupole (Q
Δ
) and magnetic octupole (O
Δ
) moments of these baryons are computed within the light cone QCD sum rules. The results are compared with the predictions
of the other phenomenological approaches, lattice QCD and existing experimental data. 相似文献
6.
A. A. Akunets S. S. Anan’ev Yu. L. Bakshaev P. I. Blinov V. A. Bryzgunov A. S. Chernenko S. A. Dan’ko E. D. Kazakov V. D. Korolev B. R. Meshcherov S. L. Nedoseev V. G. Pimenov E. A. Smirnova G. I. Ustroev V. V. Vikhrev I. V. Volobuyev A. A. Zelenin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(2):499-502
On the S-300 installation at currents up to 2 MA with rise time 100 ns, the investigation of the formation process of high-temperature
plasma in fast Z-pinch was carried out. The central part of the loads was made from agar-agar and represented a deuterated
polyethylene cylinder with small density 50 and 75 mg/sm3 and 1–2 mm diameter. On the ICT images, obtained in optical and soft X-ray range of a spectrum with 3–5 ns exposition, it
is visible that on the axis of the polyethylene cylinder at the current`s rise time a cord is formed and it is separated into
bright formations. They were observed on a background of a luminous area which occupied the initial neck volume. On time-integrated
pinhole pictures obtained in SXR range (E > 1–4 keV), hot points with minimal size of 50 microns were registered. From the
chronograms results, obtained by means of the optical high-speed-streak camera mount along the neck axis with time resolution
< 1 ns, it follows that luminous formations arise sequentially during the different time moments (in 10–30 ns). Occurrence
of luminous formations was accompanied by X-ray radiation occurrence with energy E > 1 keV with short duration of 2–4 ns.
Simultaneously with X-ray radiation neutrons with the maximal yield of 4.5×109 were registered. The average energy measured in 4 directions under angles with an axis of: 0○ (above the anode), 90○, 180○ (under the cathode) and 270○, were accordingly: 2.4±0.2, 2.5±0.1, 2.5±0.1, 2.5±0.1 MeV. 相似文献
7.
A transmission γ-ray circular polarimeter has been developed for the measurement of the sign of magnetic moments of radioactive
nuclei with low-temperature nuclear orientation. The signs of the magnetic moments were determined for 30h193Os (+), 4.9s191mIr (+), 74 d192Ir (+), 19h194Ir (+) and 4.0 d195mPt (−). 相似文献
8.
Principles and applications are described for a form of Doppler-free optical double resonance spectroscopy which uses amplitude
modulation sidebands (v
L
±v) imposed on a single laser frequency (v
L
). The sidebands are generated by passing the carrier radiationv
L
through an electro-optic modulator, driven at a radiofrequency ν, which enables the intensity and polarization characteristics
of the emerging radiation to be varied for enhancement of selected double-resonance processes. The technique has been applied
to infrared-infrared double-resonance studies of the Stark effects of a variety of molecules—13CH3F,12CH3F, PH3,15NH3, GeH4, SiH4, and CH3D—for which physical results are presented and discussed. These results include determination of extremely small electric
dipole moments (10−3–10−5 debye) for GeH4 and CH3D and, for the dipole moment of PH3, a vibrational state dependence which is extremely small (Δμ=0.0028(5) debye for ∣Δv
2∣=1) and a rotational state dependence which is of an unexpected sign. The spectra recorded in some cases display unusual
polarization and optical saturation effects which deviate markedly from the predictions of a simple three-wave polarization
theory. 相似文献
9.
F. Le Blanc L. Cabaret J.E. Crawford S. Essabaa V. Fedoseyev W. Geithner J. Genevey M. Girod R. Horn G. Huber S. Kappertz J. Lassen J.K.P. Lee G. Le Scornet V. Mishin R. Neugart J. Obert J. Oms A. Ouchrif S. Peru J. Pinard H. Ravn B. Roussière J. Sauvage D. Verney 《The European Physical Journal A - Hadrons and Nuclei》2002,15(1-2):49-51
Laser spectroscopy measurements have been carried out on the very neutron-rich tin isotopes with the COMPLIS experimental
setup. Using the 5s
25p
23
P
0 → 5s
25p6s
3
P
1 optical transition, hyperfine spectra of 126-132Sn and 125m, 127m, 129m-131mSn where recorded for the first time. The variation of the mean-square charge radius ( δ〈r
2〉) between these nuclei and nuclear moments of the isomers and the odd isotopes were thus measured. An odd-even staggering
which inverts at A = 130 is clearly observed. This indicates a small appearance of a plateau on the δ〈r
2〉 which has to be confirmed by measuring the isotope shift beyond A = 132.
Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002
RID="a"
ID="a"e-mail: leblanc@ipno.in2p3.fr 相似文献
10.
We derive the LO DGLAP evolution equation for the full Mellin moments of the first moment of the nonsinglet parton distribution truncated at x0. This “moment of moment” approach allows one to determine the small-x0 behaviour of the truncated first moment. We compare our predictions to results obtained from x-space solutions for parton distributions with use of the Chebyshev-polynomial method and to solutions of the evolution equations for the truncated moments proposed by other authors. The comparison is performed for different input parametrisations for 10-5≤x0≤0.1 and 1≤Q2≤100 GeV2. We give an example of an application to the determination of the contribution to the Bjorken sum rule. PACS 12.38.Bx; 11.55.Hx 相似文献
11.
E. F. Jones P. M. Gore S. J. Zhu J. H. Hamilton A. V. Ramayya J. K. Hwang R. Q. Xu L. M. Yang K. Li Z. Jiang Z. Zhang S. D. Xiao X. Q. Zhang W. C. Ma J. D. Cole M. W. Drigert I. Y. Lee J. O. Rasmussen Y. X. Luo M. A. Stoyer 《Physics of Atomic Nuclei》2006,69(7):1198-1203
We have used our analysis of γ-γ-γ data (5.7 × 1011 triples and higher folds) taken with Gammasphere from prompt γ rays emitted in the spontaneous fission of 252Cf to study the collective bands in 104,106,108Mo. The one-phonon and two-phonon γ-vibrational bands and known two-quasiparticle bands in neutron-rich 104,106Mo were extended to higher spins. The one-and two-phonon γ-vibrational bands have remarkably close energies for transitions from the same spin states and identical moments of inertia.
Several new bands are observed and are proposed as quasiparticle bands in 104,106Mo, along with the first β-type vibrational band in 106Mo. The quasiparticle bands have essentially constant moments of inertia near the rigid-body value that indicate blocking
of the pairing interaction. Candidates for chiral doublet bands in 106Mo are strong. These are the first reported chiral vibrational bands in an even-even nucleus.
The text was submitted by the authors in English. 相似文献
12.
B. D. D. Singleton P. M. Walker A. Bhagwat S. S. Al-Ghamdi C. G. Barham I. S. Grant A. G. Griffiths J. Rikovska N. J. Stone 《Hyperfine Interactions》1992,75(1-4):471-479
Low-temperature nuclear orientation measurements made on-line at the SERC Daresbury Laboratory on142m
Eu,141m
Sm, and141Pm, with known magnetic dipole moments, have yielded the magnitude of the hyperfine fields of these isotopes in an iron host
lattice. Thus measurements for the isotopes139, 138Eu,139m
Sm, and138Pm yielded values for the respective magnetic moments. Limits on the thermal relaxation times of Eu and Sm isotopes in Fe
were also deduced. The results for138Eu appear to contradict the earlier πh11/2⊗νh11/2 ground-state configuration assignment. 相似文献
13.
The DPAC technique was applied to measure the quadrupole moments of the 300 ps, 5/2− states in75,77As. The isotopes were implanted in α-Ga. The following results were obtained: Q(5/2−)=30(10) fm2 for75As, and Q(5/2−)<75 fm2 for77As. 相似文献
14.
Assuming that the anomalous magnetic moment interaction has the formaT
1
1
+bT
2
2
+cT
4
4
+sT
α
α
in SU(4), which may arise due to symmetry breaking or some other dynamical effects, we have obtained the magnetic moments
and the transition moments of the ordinary and charmed baryons. 相似文献
15.
Magdalena Kowalska 《Hyperfine Interactions》2006,171(1-3):167-172
Collinear laser spectroscopy and β-NMR spectroscopy with optical pumping were applied at ISOLDE/CERN to measure for the first time the magnetic moments of neutron-rich
27Mg, 29Mg, 31Mg and 33Mg, along with the spins of the two latter. The magnetic moment of 27Mg was derived from its hyperfine structure detected in UV fluorescent light, whereas the nuclear magnetic resonance observed
in β-decay asymmetry from a polarised ensemble of nuclei gave the magnetic moment of 29Mg. For 31Mg and 33Mg, the hyperfine structure and nuclear magnetic resonance gave the spin and the magnetic moment. The preliminary results
for 27Mg and 29Mg are consistent with a large neutron shell gap at N=20, whereas data on 31Mg show that for this nucleus N=20 is not a magic number, which is also the case for 33Mg, based on preliminary analysis. Thus, the two latter isotopes belong to the “island of inversion.”
Magdalena Kowalska for the IS 427 collaboration at ISOLDE/CERN. 相似文献
16.
N. A. Nemkovich H. Detert V. Schmitt Yu. V. Kruchenok 《Journal of Applied Spectroscopy》2012,79(3):353-359
Absorption and fluorescence spectra of octupolar centrosymmetric oligophenylenevinylene dyes (E,E)-bis[2-(4-hexyloxyphenyl)ethenyl]-(E,E)-3,6-bis-[2-(4-N,N-dipropylaminophenyl)ethenyl]pyrazine and (E,E,E,E)-2,3,5,6- tetra-[2-(4-hexyloxyphenyl)ethenyl]pyrazine were measured in various solvents. An electro-optical absorption method was used to determine their dipole moments as μ g = 6.1∙10–30 and 3.4∙10–30 C∙m in the equilibrium ground state and the increased values ∆ a μ = 11.9∙10–30 and 8.2∙10–30 C∙m upon excitation into a Franck–Condon state. Quantum-chemical calculations showed that the molecules had non-planar configurations. The π,π-conjugated system was localized on the most planar part of the molecule that was responsible for light absorption in the range 300–450 nm due to a change in the geometry of the molecules in the ground state. Localized excitation of the molecules caused their dipole moments ∆ a μ to change significantly. 相似文献
17.
The high-velocity distribution of a two-dimensional dilute gas of Maxwell molecules under uniform shear flow is studied. First
we analyze the shear-rate dependence of the eigenvalues governing the time evolution of the velocity moments derived from
the Boltzmann equation. As in the three-dimensional case discussed by us previously, all the moments of degreek⩾4 diverge for shear rates larger than a critical valuea
c
(k)
, which behaves for largek asa
c
(k)
∼k
−1. This divergence is consistent with an algebraic tail of the formf(V) ∼V
−4-σ(a), where σ is a decreasing function of the shear rate. This expectation is confirmed by a Monte Carlo simulation of the Boltzmann
equation far from equilibrium. 相似文献
18.
A. V. Bobylev 《Journal of statistical physics》1996,88(5-6):1183-1214
Some inequalities for the Boltzmann collision integral are proved. These inequalities can be considered as a generalization
of the well-known Povzner inequality. The inequalities are used to obtain estimates of moments of the solution to the spatially
homogeneous Boltzmann equation for a wide class of intermolecular forces. We obtain simple necessary and sufficient conditions
(on the potential) for the uniform boundedness of all moments. For potentials with compact support the following statement
is proved: if all moments of the initial distribution function are bounded by the corresponding moments of the MaxwellianA exp(−Bv
2), then all moments of the solution are bounded by the corresponding moments of the other MaxwellianA
1 exp[−B
1(t)v
2] for anyt > 0; moreoverB(t) = const for hard spheres. An estimate for a collision frequency is also obtained. 相似文献
19.
Vacuum-deposited perylene-3,4,9,10-tetracarboxylic acid dianhydride thin films are investigated by IR-spectropolarimetry with
variable incident angle of plane-polarized radiation. Anisotropy of absorption bands in the region 700–900 cm−1 is detected. Absorption bands in the subregions 728–736 and 806–810 cm−1 are shown to be of triplet nature with orthogonally oriented dipole moments within the triplet. 相似文献
20.
The magnetic moments of uncharmed and charmed baryons are considered to arise through single-quark and two-quark transitions
in a quark model. The magnetic moment operator is taken to transform as:T
β
α
˜aT
1
1
, +bT
2
2
+cT
3
3
+dT
4
4
, whereT
β
α
are members of SU(4)20′-plet. The assumption, that the magnetic moment operator obtains contribution from the single and two-quark transitions, yields
good results for the magnetic moment values of uncharmed baryons. Magnetic moments of charmed baryons can be expressed in
terms of one parameter. 相似文献