共查询到20条相似文献,搜索用时 15 毫秒
1.
A. V. Guskov 《Physics of Particles and Nuclei Letters》2010,7(3):192-200
The electromagnetic structure of charged pions can be described by the electric (απ) and magnetic (βπ) polarizabilities that depend on the rigidity of pion’s internal structure as a composite particle. It is shown that the
values of απ and βπ can be precisely measured via the Primakoff reaction π− + (A, Z) → π− + (A, Z) + γ in the COMPASS experiment at CERN. 相似文献
2.
Bourgeois P Sato Y Shaw J Alarcon R Bernstein AM Bertozzi W Botto T Calarco J Casagrande F Distler MO Dow K Farkondeh M Georgakopoulos S Gilad S Hicks R Holtrop M Hotta A Jiang X Karabarbounis A Kirkpatrick J Kowalski S Milner R Miskimen R Nakagawa I Papanicolas CN Sarty AJ Sirca S Six E Sparveris NF Stave S Stiliaris E Tamae T Tsentalovich G Tschalaer C Turchinetz W Zhou ZL Zwart T 《Physical review letters》2006,97(21):212001
The mean square polarizability radii of the proton have been measured for the first time in a virtual-Compton-scattering experiment performed at the MIT-Bates out-of-plane scattering facility. Response functions and polarizabilities obtained from a dispersion analysis of the data at Q2 = 0.057 GeV2/c2 are in agreement with O(p3) heavy baryon chiral perturbation theory. The data support the dominance of mesonic effects in the polarizabilities. 相似文献
3.
The measurement of the electromagnetic polarizabilities have been given extensive attention, which is also a fresh field of the experimental nuclear physics. Now we will use the method - the light nucleus scattered by the heavy nucleus at energies below the Coulomb barrier to precisely and systematically measure the polarizabilities of the light nucleus. We hope we can solve the inconsistency among the results of the 3He polarizabilities and extract the 4He polarizabilities by our experiment. It is useful to mention that our experiment now is a supplement to the future experiment on SLEGS. 相似文献
4.
The spin polarizabilities of the nucleon are fundamental structure constants which describe the response of the nucleon spin to an incident polarized photon. The most model-independent way to measure the nucleon spin polarizabilities is the Compton scattering with polarization degrees of freedom. Three Compton scattering asymmetries on the proton were measured in the Δ(1232) region using a polarized incident photon beam and a polarized (or unpolarized) proton target at the Mainz Microtron (MAMI). These asymmetries are sensitive to values of the spin polarizabilities. Fits to asymmetry data were performed using a dispersion model calculation, and a separation of all four proton spin-polarizabilities in the multipole basis was achieved. The values of the proton spin polarizabilities are presented. 相似文献
5.
The COMPASS experiment at CERN is investigating the nucleon spin structure in polarised deep inelastic muon scattering, mainly the gluon polarisation
. 相似文献
6.
F. Massmann 《The European physical journal. Special topics》2008,154(1):85-88
The paper presents the influence of the laser and
ultrasonic cutter on biological structures and some problems bound up with
the applications of lasers and ultrasounds in surgery. The advantages and
disadvantages of contact and noncontact applications of the Nd:YAG laser
were presented as well as the usefulness of the ultrasonic cutter for
selective cutting of various tissues. The benefits resulting from a combination of the two technologies were discussed, and
initial tests of
the laser-ultrasonic cutter operation were performed, pointing to the
possibility of improving the cutting of biological structures. 相似文献
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9.
S. Kümmel T. Berkus P.-G. Reinhard M. Brack 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,11(2):239-245
The static electric dipole polarizability of Na
N
clusters with even N has been calculated in a collective, axially averaged and a three-dimensional, finite-field approach for , including the ionic structure of the clusters. The validity of a collective model for the static response of small systems
is demonstrated. Our density functional calculations verify the trends and fine structure seen in a recent experiment. A pseudopotential
that reproduces the experimental bulk bond length and atomic energy levels leads to a substantial increase in the calculated
polarizabilities, in better agreement with experiment. We relate remaining differences in the magnitude of the theoretical
and experimental polarizabilities to the finite temperature present in the experiments.
Received 8 November 1999 相似文献
10.
11.
U.E. Schröder 《Nuclear Physics B》1980,166(1):103-112
The proper electric polarizabilities of the nucleon are calculated on the basis of the presently available experimental data on the total photoabsorption cross sections for proton and neutron. Surprisingly, the proper electric dipole polarizability of the neutron turns out to be somewhat larger than that of the proton. This is due to the very different properties of the corresponding electromagnetic form factors. 相似文献
12.
Measurement of the analyzing power in the Primakoff process with a high-energy polarized proton beam
Carey DC Coleman RN Corcoran MD Cossairt JD Derevschikov AA Grosnick DP Hill D Imai K Konaka A Kuroda K Lehar F de Lesquen A Lopiano D Luehring FC Maki T Makino S Masaike A Matulenko YA Meschanin AP Michalowicz A Miller DH Miyake K Nagamine T Nakano T Nessi-Tedaldi F Nessi M Nguyen C Nurushev SB Ohashi Y Pauletta G Penzo A Phillips GC Read AL Roberts JB van Rossum L Salvato G Schiavon P Shima T Solovyanov VL Spinka H Stanek RW Takashima R Takeutchi F Tamura N Tanaka N Underwood DG Vasiliev AN 《Physical review letters》1990,64(4):357-360
13.
G. M. Gurevich 《Physics of Atomic Nuclei》2014,77(1):110-116
Spin polarizabilities are as-yet experimentally unknown fundamental structure constants that describe the response of the nucleon spin to the action of a changing electromagnetic field. The A2 Collaboration at the Institute for Nuclear Physics in Mainz (Institut für Kernphysik, Mainz) performed the first measurements of the energy and angular dependences of spin asymmetries of the cross section for doubly polarized (polarized-photon beam incident to a polarized proton target) Compton effect in the Δ-resonance region, these asymmetries being sensitive to values of the spin polarizabilities. The preparation of spin-asymmetry measurements at energies below the pion-production threshold with an active (scintillating) polarized target is in progress. These measurements will make it possible to determine individual spin polarizabilities of the proton in a model-independent way. 相似文献
14.
P. Janssens 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):610-612
Virtual Compton scattering off the proton has been studied at Q
2 = 0.33 (GeV/c)2 at the MAMI accelerator in Mainz (Germany). The goal of the experiment is to measure the generalized polarizabilities (GPs)
of the proton using the double polarized e
p→e'
p'γ reaction. This paper reports the measurement of the unpolarized photon electroproduction cross-section for the new data and
the extraction of two linear combinations of GPs, which are essential for the analysis of the double spin asymmetry. 相似文献
15.
The experimental and theoretical work carried out on electric and magnetic polarizabilities of a nucleon is reviewed. The
results of an exactly solvable one-dimensional chiral bag model predicts correct signs and order of magnitudes of polarizabilities
supporting the approximations used in their realistic calculations. 相似文献
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17.
Utilizing terahertz time domain spectroscopy, we have characterized the electromagnetic response of a planar array of split ring resonators (SRRs) fabricated upon a high resistivity GaAs substrate. The measured frequency dependent magnetic and electric resonances are in excellent agreement with theory and simulation. For two polarizations, the SRRs yield a negative electric response (epsilon < 0). We demonstrate, for the first time, dynamical control of the electrical response of the SRRs through photoexcitation of free carriers in the substrate. An excited carrier density of approximately 4 x 10(16) cm(-3) is sufficient to short the gap of the SRRs, thereby turning off the electric resonance, demonstrating the potential of such structures as terahertz switches. Because of the universality of metamaterial response over many decades of frequency, these results have implications for other regions of the electromagnetic spectrum. 相似文献
18.
G. M. Gurevich 《Physics of Particles and Nuclei Letters》2014,11(1):31-35
The static (electric and magnetic) polarizabilities of the proton are known from measurements of low-energy Compton scattering of real photons. However, no experimental data are so far available about its spin polarizabilities, which describe the response of the proton spin to a varying electromagnetic field. These fundamental structure constants can be obtained in the most model-independent way from measurements of double-polarized Compton scattering at energies below the pion threshold using a polarized photon beam and a polarized proton target. An active polarized target based on polystyrene doped with a scintillator allows recoil protons to be detected directly in the target material, background from the coherent Compton effect on heavier nuclei (12C etc.) to be eliminated and precise data on spin polarizabilities to be obtained. 相似文献
19.
Yu. M. Antipov V. A. Batarin V. A. Bessubov N. P. Budanov Yu. P. Gorin S. P. Denisov I. V. Kotov P. A. Kulinich A. A. Lebedev G. V. Micelmacher A. G. Olshevski A. I. Petrukhin S. A. Polovnikov V. N. Roinishvili D. A. Stoyanova V. I. Travkin 《Zeitschrift fur Physik C Particles and Fields》1985,26(4):495-497
20.
A. J. Silenko 《Physics of Particles and Nuclei Letters》2014,11(6):720-721
The electric and magnetic polarizabilities of pointlike spin-1/2 particles with an anomalous magnetic moment (AMM) are calculated by the transformation of an initial Hamiltonian into the Foldy-Wouthuysen (FW) representation. Corresponding results for spin-1/2 and spin-1 particles are compared. 相似文献