Fusion, resonances and scattering in 12C+12C reaction
B Sahu; S K Agarwalla; C S Shastry
2003-07-01
The variation of fusion cross-section (fus) with energy in the 12C+12C collision is linked to the underlying resonance phenomenon through the behavior of reaction cross-section (r) of which fus is taken as a part. The calculation of fus is done through an energy-dependent imaginary potential in the optical model potential (OMP). Through dispersion relation, such an imaginary potential gives rise to energy-dependent real potential which is incorporated in the OMP. In our calculation, a form of potential for the nuclear part which has a soft repulsive in-built core is introduced based on similar works done earlier. The calculated results of fus are used to explain the oscillatory structure, astrophysical -factor and the decreasing trend at higher energies of the experimental fus data in the case of 12C+12C system with remarkable success. The potential used for fusion calculation is tested for ﬁtting elastic scattering data at some energies and is found good in forward angles. Further improvement of the ﬁtting of these data is obtained by incorporating a coupling potential in the surface region. About twenty resonances are observed in our calculation in the speciﬁc partial waves and some of them are found close to the experimentally identiﬁed resonances in 12C+12C reaction. Thus, we provide an integrated and comprehensive analysis of fusion, resonance and scattering data in the best studied case of 12C+12C reaction within the framework of optical potential model.
Resonant behavior of the elastic 12C-16O scattering
The angular distributions for 12C-16O elastic scattering at Tandem energies were measured for low energy steps (320keV c.m.) with an excitation function. The shape of the cross section, especially the oscillation phase, presents few changes in the regions where theta 150 deg; on the other hand very fast changes in the form are observed as a function of energy, in the intermediate region. The excitation function shows the existence of three resonances
YANG Yong-Xu; LI Qing-Run; ZHAO Wei-Qin
2002-01-01
Based on the analyses of the elastic angular distributions,an energy-dependent folding potential for the 12C+12C system is established.This potential has a deep real part,and can reasonably well describe the resonant structure in the 12C+12C elastic scattering in the low-energy region of 10 ～ 70 MeV.
$^{-} - {}^{12}C$ elastic scattering above the resonance using diffraction model
M R Arafah
2008-01-01
Phenomenological analysis of the $^{-}- ^{12}C$ elastic scattering differential cross-section at 400, 486, 500, 584, 663, 672 and 766 MeV is presented. The analysis is made in the diffraction model framework using the recently proposed parametrization of the phase-shift function. Good description of the experimental data is achieved at all energies. Microscopic interpretation of the parameters of the phase-shift function is provided in terms of Helm's model density parameters.
Levels in 13N examined by 12C+p elastic resonance scattering with thick target
无
2008-01-01
The elastic resonance scattering of 12C+p has been studied in inverse kinematics via a novel thick target method at GIRAFFE facility of HI-13 tandem accelerator laboratory,Beijing.The recoil protons were measured by a △E-E counter telescope based on a large area double-sided silicon strip detector at laboratory angles around θ0=15°.The excitation function for 12C(p,p)elastic scattering has been obtained over a wide energy range of Ec.m.=0.31-3.45 MeV,which was explained quite well by the R-matrix calculation with known resonance parameters of the first three levels in 13N nucleus.Thus it is demonstrated that the present setup can be directly applied to the study of elastic resonance scattering with secondary radioactive beams.
Spectroscopy of 16O using α + 12C resonant scattering in inverse kinematics
A measurement of α + 12C resonant scattering in inverse kinematics has been performed using resonant scattering with a gas target. The main advantage of this is that unlike previous experiments [1-3] where an excitation function of 16O was scanned using many different beam energies, a He gas target allows a range of resonances in 16O to be traced out as the 12C nuclei loose energy in the target. As such, many resonances can be obtained at single beam energy, without significant loss in the quality of data compared with that of a normal kinematics experiment. Beam energies of 46, 52, 56 and 63 MeV were used to populate resonances in the excitation energy range of 11.6 to 22.9 MeV in 16O. The angular distributions of the elastic scattering were measured at zero degrees, using an array of segmented silicon strip detectors with a minimum range of 0o to 30o in the centre-of-mass. The spins of 8 resonances between 14.01 and 18.47 MeV were obtained, confirming spin assignments made using elastic scattering in normal kinematics. An R-matrix analysis of the data was performed which indicates that the present understanding of 16O, in this region, is good but not complete.(author)
{sup 12}C+p resonant elastic scattering in the Maya active target
Sambi, S.; Raabe, R.; Flavigny, F.; Khodery, M. [KU Leuven, Instituut voor Kern- en Stralingsfysica, Physics Department, Leuven (Belgium); Borge, M.J.G. [CERN, PH Department, Geneva (Switzerland); Caamano, M.; Fernandez-Dominguez, B. [Universidade de Santiago de Compostela, Department of Particle Physics, Santiago de Compostela (Spain); Damoy, S.; Grinyer, G.F.; Pancin, J.; Perez-Loureiro, D.; Roger, T. [CEA/DSM - CNRS/IN2P3, Grand Accelerateur National d' Ion Lourds (GANIL), Caen (France); Fynbo, H. [Aarhus University, Department of Physics and Astronomy, Aarhus (Denmark); Gibelin, J. [Universite de Caen, CNRS/IN2P3, LPC Caen, ENSICAEN, Caen Cedex (France); Heinz, A.; Jonson, B.; Nilsson, T.; Thies, R. [Chalmers University of Technology, Department of Physics, Goteborg (Sweden); Orlandi, R. [KU Leuven, Instituut voor Kern- en Stralingsfysica, Physics Department, Leuven (Belgium); Instituto de Estructura de la Materia CSIC, Madrid (Spain); JAEA, ASRC, Tokai-mura (Japan); Randisi, G. [KU Leuven, Instituut voor Kern- en Stralingsfysica, Physics Department, Leuven (Belgium); CEA/DSM - CNRS/IN2P3, Grand Accelerateur National d' Ion Lourds (GANIL), Caen (France); Ribeiro, G.; Tengblad, O. [Instituto de Estructura de la Materia CSIC, Madrid (Spain); Suzuki, D. [Universite Paris-Sud, Institut de Physique Nucleaire, CNRS/IN2P3, Orsay (France); Datta, U. [Saha Institute of Nuclear Physics, Kolkata (India)
2015-03-01
In a proof-of-principle measurement, the Maya active target detector was employed for a {sup 12}C(p, p) resonant elastic scattering experiment in inverse kinematics. The excitation energy region from 0 to 3MeV above the proton breakup threshold in {sup 13}N was investigated in a single measurement. By using the capability of the detector to localize the reaction vertex and record the tracks of the recoiling protons, data covering a large solid angle could be utilized, at the same time keeping an energy resolution comparable with that of direct-kinematics measurements. The excitation spectrum in {sup 13}N was fitted using the R-matrix formalism. The level parameters extracted are in good agreement with previous studies. The active target proved its potential for the study of resonant elastic scattering in inverse kinematics with radioactive beams, when detection efficiency is of primary importance. (orig.)
Photon scattering from 12C and 4He nuclei near the Δ(1232) resonance
Igarashi, R.; Bergstrom, J. C.; Caplan, H. S.; Doss, K. G. E.; Hallin, E. L.; Skopik, D. M.; Delli Carpini, D.; Booth, E. C.; McIntyre, E. K.; Miller, J. P.; Lucas, M. A.; MacGibbon, B. E.; Nathan, A. M.; Wells, D.
1995-08-01
Angular distributions for photon scattering from 12C and 4He have been measured using continuous wave bremsstrahlung from the Saskatchewan Accelerator Laboratory pulse stretcher ring. Data for carbon were taken at 158.8, 195.2, 197.2, 247.2, and 290.2 MeV end-point energies, and for helium were taken at an end-point energy of 158.8 MeV. A large NaI(Tl) gamma ray spectrometer with 1.7% resolution was used to detect the scattered photons at laboratory scattering angles ranging from 20° to 150°. The excellent energy resolution of the NaI detector allowed a separation of elastic from inelastic photon scattering for the first time at these energies. The angular distributions for elastic scattering are in only fair agreement with delta-hole theory and theory based on the optical theorem at forward angles, and completely disagree with theory at backward angles. Measured cross sections for inelastic scattering leading to the 4.43 MeV state in carbon are small compared to the elastic scattering at forward angles, but are dominant at backward angles. This experiment is the first to separate elastic from inelastic photon scattering at these energies.
Photon scattering from 12C and 4He nuclei near the Δ(1232) resonance
Angular distributions for photon scattering from 12C and 4He have been measured using continuous wave bremsstrahlung from the Saskatchewan Accelerator Laboratory pulse stretcher ring. Data for carbon were taken at 158.8, 195.2, 197.2, 247.2, and 290.2 MeV end-point energies, and for helium were taken at an end-point energy of 158.8 MeV. A large NaI(Tl) gamma ray spectrometer with 1.7% resolution was used to detect the scattered photons at laboratory scattering angles ranging from 20 degree to 150 degree. The excellent energy resolution of the NaI detector allowed a separation of elastic from inelastic photon scattering for the first time at these energies. The angular distributions for elastic scattering are in only fair agreement with delta-hole theory and theory based on the optical theorem at forward angles, and completely disagree with theory at backward angles. Measured cross sections for inelastic scattering leading to the 4.43 MeV state in carbon are small compared to the elastic scattering at forward angles, but are dominant at backward angles. This experiment is the first to separate elastic from inelastic photon scattering at these energies
Microscopic analysis of t+12C scattering
Optical model calculations with double-folded microscopic real central and spin-orbit potentials and an imaginary Woods-Saxon potential have been carried out for previously reported t+12C and 58Ni elastic scattering data. The t+12C calculations are not able to reproduce the changes in the measured analyzing powers as a function of bombarding energy, whereas they do describe the t+58Ni data. This analysis suggests that information about the cluster-core t+12C spin-orbit potential, necessary for cluster structure calculations, cannot be determined without considerably more data. Three-particle-transfer reactions leading to 15N show numerous structures that could appear in the t+12C entrance channel. Excitation functions are needed for both the elastic and 4.43 MeV first excited state in 12C if this scattering is to be understood
12C + 12C resonances by a molecular model
Resonances observed in the 12C + 12C collisions are studied with a molecular model. At high spins J = 12–16, a stable dinuclear configuration is found to be an equator- equator touching one as is obtained in the 28Si + 28Si system. With K-quantum number being specified as rotation-vibration model, normal modes have been solved around the equilibrium, firstly. Furthermore, Coriolis coupling has been investigated by diagonalization among low- lying normal-mode states with K = 0 and K-excitation. It is found that the Coriolis coupling introduces about 30% of K-mixing into the K = 0 molecular ground states of J = 12–16. The analyses of the angular momentum coupling show up a dominance of the lowest L in the inelastic channel of the molecular ground state newly obtained. Thus alignments appear strongly in the inelastic channel, which is in agreement with the explanation by the band crossing model. Discussion is given on ''why disalignments appear in the 28Si + 28Si system, in contrast to the above results''
Angular correlation measurements for {sup 12}C{sup 12}C,{sup 12}C{sup 12}C 3{sup -} scattering
Wuosmaa, A.H.; Betts, R.R.; Freer, M.
1995-08-01
Previous studies of inelastic {sup 12}C + {sup 12}C scattering to a variety of final states identified significant resonance behavior in a number of different reaction channels. These resonances can be interpreted as either potential scattering resonances, or as population of cluster structures in the compound nucleus {sup 24}Mg, or as some interplay between the two mechanisms. Currently, for many of these resonances the situation remains unclear. One example is a large peak observed in the excitation function for the 3{sup -} - g.s. excitation, identified in previous work performed at the Daresbury Laboratory in England. This peak is observed at the same center-of-mass energy as one observed in the O{sub 2}{sup +}-O{sub 2}{sup +} inelastic scattering channel. That structure was suggested to correspond to exotic deformed configurations in the compound nucleus {sup 24}Mg. As the peak in the 3{sup -} + g.s. exit channel occurs at precisely the same energy as the purported resonance, it is tempting to associate the two. Before such an association can be confirmed or ruled out, further information must be obtained about the 3{sup -} + g.s. structure. In particular, it is important to determine the angular momenta that dominate the 3{sup -} + g.s. structure.
Solving the 12C+12C scattering puzzle: is there the '4th elephant'?
Differential cross sections of the 12C+12C and the 13C+12C elastic scattering were measured at the projectile energies 240 MeV (12C) and 250 MeV (13C) up to the largest angles. The positions of the 1st Airy minima known from the former experiments were confirmed.
Spin alignment and resonances in the system 12C+12C - a study with a 4π gamma-spectrometer
In order to characterize the resonance behaviour of 12C+12C in the rotational degrees of freedom in the present thesis the alignment of the intrinsic spin(s) in the reactions 12C12C → 12C+12C* (2+, 4.44 MeV) and 12C+12C → 12C*(2+)+12C*(2+) was studied for nine incident energies in the range 19.29 ≤ Ec.m. ≤ 34.65 MeV in dependence on the scattering angle 400 c.m. ≤ 900. From the position-sensitive detection of the particle-particle coincident 4.44-MeV photons by the Darmstadt-Heidelberg crystal-ball spectrometer the scattering amplitudes characterized by the spin-orientation quantum number m for the single-inelastic scattering could be determined nearly completely. Their angular dependence was subjected to a partial wave analysis as its result the angular-momentum distribution is obtained as function of the incident energy and the m quantum number. For the double-inelastic 12C+12C scattering from the 2-photon intensity distribution the probabilities of the correlated alignment of both fragment spins were derived. (orig./HSI)
/sup 12/C+ /sup 12/C elastic scattering excitation functions and phase shift analysis
Ledoux, R.J.; Bechara, M.J.; Ordonez, C.E.; Al-Juwair, H.A.; Cosman, E.R.
1983-03-01
The /sup 12/C+ /sup 12/C elastic scattering has been measured for E/sub c.m./ = 14.6--31.3 MeV, theta/sub c.m./ = 30/sup 0/--110/sup 0/. The elastic data have been analyzed via a phase shift analysis, enabling the extraction of model independent sets of phase shift parameters. The extracted J/sup ..pi../ values for the intermediate structure resonances at E/sub c.m./ = 18.4, 19.3, and 20.3 MeV are 12/sup +/, 12/sup +/, and 12/sup +/ or 14/sup +/, respectively. The questions of ambiguities in the phase shift analysis and the comparison with J/sup ..pi../ values deduced from other experiments are discussed. Evidence is presented for the existence of gross structure resonances. The elastic scattering has also been analyzed using the sum-of-differences method to directly extract the total reaction cross section. The results of these analyses are compared to existing models of the origin of intermediate structure resonances.
Is there a giant monopole resonance in 12C
Arguments that the 0+ (Esub(x)=20.3 MeV) state recently found in 12C can be interpreted as a giant resonance are given. The calculations of differential cross sections of the 0+ state excitation in elastic and inelastic scattering of 3He, 4He and 6Li on 12C and compared with experimental data. Using transition densities calculated in the hyperspherical function method it is shown that in the framework of the collective model this single state exhausts the monopole energy weighted sum rules
The Ec.m.=32.5 MeV resonance in 12C+12C
It has been suggested that the resonance found at Ec.m. = 32.5 MeV in an inelastic channel of 12C + 12C corresponds to a sic alpha-particle chain state. Re-examining our earlier data on this system a resonance is observed at the same energy in another outgoing channel, 16O + 8Be, which is not expected to resonate for such a configuration. We observe similar angular distributions but an appreciably narrower width than that measured in the inelastic channel. (authors). 11 refs., 2 figs
Bosted, P E; Amarian, M; Anefalos, S; Anghinolfi, M; Asryan, G; Avakian, H; Bagdasaryan, H; Baillie, N; Ball, J P; Baltzell, N A; Barrow, S; Batourine, V; Battaglieri, M; Beard, K; Bedlinskiy, I; Bektasoglu, M; Bellis, M; Benmouna, N; Biselli, A S; Bonner, B E; Bouchigny, S; Boiarinov, S; Bradford, R; Branford, D; Brooks, W K; Bültmann, S; Burkert, V D; Butuceanu, C; Calarco, J R; Careccia, S L; Carman, D S; Carnahan, B; Cazes, A; Chen, S; Cole, P L; Collins, P; Coltharp, P; Cords, D; Corvisiero, P; Crabb, D; Crannell, H; Credé, V; Cummings, J P; De Masi, R; De Vita, R; De Sanctis, E; Degtyarenko, P V; Denizli, H; Dennis, L; Deur, A; Djalali, C; Dodge, G E; Donnelly, J; Doughty, D; Dragovitsch, P; Dugger, M; Dharmawardane, K V; Dytman, S; Dzyubak, O P; Egiyan, H; Egiyan, K S; Elouadrhiri, L; Eugenio, P; Fatemi, R; Fedotov, G; Feuerbach, R J; Forest, T A; Fradi, A; Funsten, H; Garçon, M; Gavalian, G; Gilfoyle, G P; Giovanetti, K L; Girod, F X; Goetz, J T; Golovatch, E; Gothe, R W; Griffioen, K A; Guidal, M; Guillo, M; Guler, N; Guo, L; Gyurjyan, V; Hadjidakis, C; Hafidi, K; Hakobyan, R S; Hardie, J; Heddle, D; Hersman, F W; Hicks, K; Hleiqawi, I; Holtrop, M; Huertas, M; Hyde-Wright, C E; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Isupov, E L; Ito, M M; Jenkins, D; Jo, H S; Joo, K; Jüngst, H G; Kalantarians, N; Keith, C; Kellie, J D; Khandaker, M; Kim, K Y; Kim, K; Kim, W; Klein, A; Klein, F J; Klusman, M; Kossov, M; Kramer, L H; Kubarovski, V; Kühn, J; Kuhn, S E; Kuleshov, S V; Lachniet, J; Laget, J M; Langheinrich, J; Lawrence, D; Ji Li; Lima, A C S; Livingston, K; Lü, H; Lukashin, K; MacCormick, M; Markov, N; McAleer, S; McKinnon, B; McNabb, J W C; Mecking, B A; Mestayer, M D; Meyer, C A; Mibe, T; Mikhailov, K; Minehart, R; Mirazita, M; Miskimen, R; Mokeev, V; Morand, L; Morrow, S A; Moteabbed, M; Müller, J; Mutchler, G S; Nadel-Turonski, P; Nasseripour, R; Niccolai, S; Niculescu, G; Niculescu, I; Niczyporuk, B B; Niroula, M R; Niyazov, R A; Nozar, M; O'Rielly, G V; Osipenko, M; Ostrovidov, A I; Park, K; Pasyuk, E; Paterson, C; Philips, S A; Pierce, J; Pivnyuk, N; Pocanic, D; Pogorelko, O; Polli, E; Pozdniakov, S; Preedom, B M; Price, J W; Prok, Y; Protopopescu, D; Qin, L M; Raue, B A; Riccardi, G; Ricco, G; Ripani, M; Rosner, G; Rossi, P; Rowntree, D; Rubin, P D; Sabati, F; Salgado, C; Santoro, J P; Sapunenko, V; Schumacher, R A; Serov, V S; Sharabyan, Yu G; Shaw, J; Shvedunov, N V; Skabelin, A V; Smith, E S; Smith, L C; Sober, D I; Stavinsky, A; Stepanyan, S S; Stepanyan, S; Stokes, B E; Stoler, P; Strauch, S; Suleiman, R; Taiuti, M; Taylor, S; Tedeschi, D J; Thoma, U; Tkabladze, A; Tkachenko, S; Todor, L; Ungaro, M; Vineyard, M F; Vlassov, A V; Weinstein, L B; Weygand, D P; Williams, M; Wolin, E; Wood, M H; Yegneswaran, A; Yun, J; Zana, L; Zhang, J; Zhao, B; Zhao, Z
2007-01-01
The ratio of inclusive electron scattering cross sections for 15N/12C was determined in the kinematic range 0.8
Neutrino neutral-current elastic scattering on 12C
Butkevich, A. V.; Perevalov, D.
2011-01-01
The neutral current elastic scattering of neutrinos on Carbon and $CH_2$ targets is computed using the relativistic distorted-wave impulse approximation with relativistic optical potential. Results for exclusive and inclusive neutrino reactions on ${}^{12}$C target are presented. We show that the nuclear effects on the shape of four-momentum transferred squared distribution $d\\sigma/dQ^2_{QE}$ in neutrino neutral-current and charged-current quasi-elastic scattering are similar. We also calcul...
Scattering of polarized tritons by 9Be and 12C
The differential cross section and the analyzing power A/sub y/ for 9Be(t,t)9Be and 12C(t,t)12C elastic scattering have been measured at 15 and 17 MeV over the angular range theta/sub lab/ = 17.5--165.00. The data in the forward hemisphere have been analyzed with a standard optical model. A large depth and conventional geometry parameters for the spin-orbit potential have been found. The results of the present analysis are in general agreement with previous work involving polarized tritons scattered from heavy target nuclei and show important differences from investigations of the scattering of polarized helions on light nuclei
Alpha-particle momentum distributions from 12C decaying resonances
The computed α particle momentum distributions from the decay of low-lying 12C resonances are shown. The wave function of the decaying fragments is computed by means of the complex scaled hyperspherical adiabatic expansion method. The large-distance part of the wave functions is crucial and has to be accurately calculated. We discuss energy distributions, angular distributions and Dalitz plots for the 4+, 1+ and 4- states of 12C. (author)
Dispersion effects in elastic electron scattering from 12C
The results of an experiment, especially designed to investigate to what extent dispersion effects contribute to the reaction mechanism of elastic electron scattering from 12C, are presented and discussed. Particular attention is given to the discussion of corrections to parameters used in the calculation of the cross section. Tables of the resulting cross sections are given for the ground state and for the 2+ and 0+ states at, respectively, 4.439 and 7.655 MeV. The one-photon exchange approximation for elastic electron scattering from 12C is investigated by testing the energy dependence of the form factor in the region of the first diffraction minimum. The energy dependence observed is interpreted in terms of dispersion effects. 109 refs.; 33 figs.; 14 tabs
Full text: The fulfillment of planned works on measurements of differential cross sections of elastic scattering of protons on nuclear 12C at the energy region of 350†1050 keV suggests the preparation of thin self - supporting carbon target. The self - supporting target is necessary in order to perform investigations in the total angular range. In the future last data will be used in order to determine optical potentials and scattering phases for this nuclear in the energy range of astrophysical interest. There was prepared target layer of the 12C with natural composition of carbon and of thickness of 17.4 μg/cm2. The spraying was conducted in the vacuum evaporation installation (VUP - 4) by an electron bombardment method. Carbon was sprayed on a glass plate with previously deposited of layer salt. After a heating during 12 hours at the temperature of 150 oC the film of carbon was floated from glass plate and self - supporting target has been picked up on the specially prepared target frame. In order to determine thickness of target there was used the resonance chamber, installed in the protons channel of the accelerator RAC - 2 - 1 (INP NNC RK), with the help of which there was measured energy loss of the protons beam during the passage through target, disposed in the central chamber. For this purpose there was used the reaction 27Al(p,γ)28Si with narrow resonance with ER = 992 keV and with detection of gamma-quanta with Eγ = 1779 keV. On shift of the resonance ER=992 keV in the reaction 27Al(p,γ)28Si, which takes place owing to protons energy loss in the thickness of carbon film, and using table values of brake quantities S(Ep)[MeV·cm2/g] [1], there was determined thickness of this fine film. Such the method allows to determine thicknesses of films in the interval of (10 † 100) mcg/cm2 with the accuracy of not worse than 5%. In the present work there were carried out measurements of angular distributions of cross sections of the elastic scattering 12C
An orthogonality condition model treatment of elastic and inelastic (α, 12C) scattering
Elastic and inelastic scattering of α-particles on the deformed nucleus 12C are investigated in the range of incident α-particle energies of 9 to 11 MeV by using the coupled-channel method with orthogonality condition. A doubly folded potential generated by the shell model wave functions of the α-particle and the deformed nucleus 12C is employed for the relative motion between the α-particle and 12C. Good agreement between theory and experiment is obtained for the elastic and inelastic angular distributions and the resonance structures. It is found, from the Born series expansion of the T-matrix, that the orthogonality constraint stresses the effects of the channel-coupling between the elastic and inelastic processes, and it indicates that the DWBA does not work well in this system. (author)
Resonant and nonresonant behavior of the heavy-ion reaction 14C + 12C
The 14C + 12C reaction has been studied by a kinematic coincidence technique at 13 incident energies ranging from Ec.m.=19.35 to 24.9 MeV. The resonances previously reported from γ-ray yield measurements were observed in the equivalent excitation functions, as well as in the large angle elastic scattering data, of the present measurements. Spin assignments were made to the two resonances in this energy range. These resonances are members of a band with angular momenta several units larger than the grazing values corresponding to 14C and 12C orbiting about each other at a distance significantly outside the strong absorption radius. Other structures which were observed were unrelated to the resonant behavior. (author) 22 refs.; 14 figs
The α8Be cluster model for 02+ resonance of 12C
The two-cluster α + 8Be is used for description of 02+ resonance of 12C nucleus. The equation for relative motion of clusters is derived from the s-wave differential Faddeev equations of the three-α-cluster system. For these aim a simple version of the resonating-group method is applied. A phenomenological potential is employed for description of αα interaction. The three-body potential which binds 3α system ensures the existence of a resonance state in the α + 9Be scattering. The results of our calculations are compared with the results of other authors
Probing the isoscalar excitations of 12C with inelastic alpha scattering
The robust (spin and isospin zero) α-particle remains one of the best projectiles to probe the nuclear isoscalar excitations. In the present work, a microscopic folding model analysis of the α+12C inelastic scattering to the 2+ (4.44 MeV), 0+ (7.65 MeV), 3- (9.64 MeV), 0+ (10.3 MeV) and 1- (10.84 MeV) states in 12C has been performed using the 3-α resonating group method wave functions. The isoscalar transition strengths of these states were carefully studied based on the coupled-channel analysis using the microscopic folded form factors. A correlation between the weak binding and/or short lifetime of the excited state and absorption in the exit channel of inelastic scattering has been established. (author)
Quantum partner-dance in the 12C + 12C system yields sub-Coulomb fusion resonances
A preliminary study of the 12C + 12C sub-Coulomb fusion reaction using the time-dependent wave-packet method is presented. The theoretical sub-Coulomb fusion resonances seem to correspond well with observations. The present method might be a more suitable tool for expanding the cross-section predictions towards lower energies than the commonly used potential-model approximation.
Resonance states in 16O + 16O, 12C + 16O, + 16O and + 12C with modified Morse potentials
B Sahu; L Satpathy
2008-05-01
The resonance states in 16O + 16O, 12C + 16O, + 16O and + 12C are described using modified Morse potential proposed earlier whose success has already been demon-strated in the case of 12C + 12C system. The general validity of such a potential with long range, shallow depth and repulsive soft core determined from the resonance data itself is being examined through the present study of the resonances in the above four systems. In each system, the experimental data of a large number of states have been successfully described with a modified Morse potential. The success points out a common mechanism of the origin of these states, and reaffirms authentically the diatomic-like rotational and vibrational picture of the nuclear molecular resonances proposed previously. The close resemblance between the physics of diatomic molecules and nuclear molecular resonances extending to the level of potential which is Morse type in both the cases - although belong to two different areas of physics - is further strengthened through the present study.
The 90deg excitation function for elastic 12C+12C scattering. The importance of Airy elephants
The 90deg excitation function for elastic 12C+12C scattering, at laboratory energies between the Coulomb barrier and 130 MeV, exhibits a complex structure of peaks and valleys whose nature has remained an unsolved mystery for more than 20 years. The problem has primarily been caused by the difficulty of choosing from a plethora of discretely ambiguous optical potentials. However, data accumulated above 150 MeV over the last decade have determined unique potentials at these higher energies, and the requirement of continuity downward in energy has recently permitted the determination of a unique set of potentials for angular distributions at energies below 130 MeV, where the excitation-function data exist. These new potentials are used to provide a mean-field (i.e., nonresonant) interpretation of the structure in the 12C+12C 90deg excitation function between 70 and 130 MeV. Its most prominent minima are found to be Airy minima from nuclear rainbows, with the remaining structure arising primarily from more elementary optical phenomena related to Fraunhofer diffraction. These same potentials are also successful in explaining the details of excitation functions measured very recently at other angles by Morsad. (orig.)
Measurement of resonances in 12 C + 4 He through inverse kinematics with thick targets
The excitation function of elastic scattering for the system 12 C + 4 He to energy from 0.5 to 3.5 MeV in the center of mass system (c.m.) was measured. We use a gassy thick target and the technique of inverse kinematics which allows to make measurements at 180 degrees in c.m. Using the R matrix theory those was deduced parameters of the resonances and the results were compared with measurements reported in the literature made with other techniques. (Author)
The 12C + 12C reaction is important to understand the nuclear burning in stellar evolution. In this work, we calculate the 12C + 12C microscopic potential based on the effective nucleon-nucleon (NN) interaction and the wave functions of interaction nuclei. The Optical Model analysis for elastic scattering angular distributions of 12C + 12C system at energies near to the Coulomb barrier agrees well with the experimental data, which makes sure the applicability of our obtained potential. The Barrier Penetration Model (BPM) and WKB approximation are applied to estimate the astrophysical S factor, which is reasonable to measurement results. (author)
Microscopic description of the elastic and inelastic 16O+12C scattering
The elastic and inelastic 16O+12C scattering data were described the optical model and DWBA calculations using the folded potential based on the CDM3Y6 interaction and the collective transition densities. The strong nuclear rainbow patterns were expressed in the refractive elastic 16O+12C scattering data at Elab=200, 230 and 260 MeV. The nuclear rainbow patterns in the inelastic 16O+12C scattering was expressed very weakly because of suppression of the strong absorption of optical potential in the exit channel. (author)
Phenomenological local potentials for π-+12C scattering from 120 to 766 MeV
Pion-nucleus scattering cross sections are calculated by solving a Schroedinger equation reduced from the Klein-Gordon equation. Local potentials are assumed, and phenomenological potential parameters are searched energy-dependently for a π-+12C system so as to reproduce not only elastic differential cross sections but also total elastic, reaction and total cross sections at 13 pion incident energies from 120 to 766 MeV. The real and imaginary parts of the local potentials thus obtained are shown to satisfy the dispersion relation. The imaginary part of the potentials as a function of the pion energy is found to peak near the Δ(1232)-resonance energy. The strong absorption radius of the pion projectile with incident energies near the Δ-resonance region is found to be about 1.6A1/3 fm, which is consistent with previous studies of the region where the decay of the Δ takes place in nuclei. The phenomenological local potentials are then compared with the local potentials exactly phase-shift equivalent to Kisslinger potentials for pion energies near the Δ-resonance. (author)
Isoscalar monopole and dipole excitations of cluster states and giant resonances in 12C
Kanada-En'yo, Yoshiko
2016-05-01
The isoscalar monopole (ISM) and dipole (ISD) excitations in 12C are investigated theoretically with the shifted antisymmetrized molecular dynamics (AMD) plus 3 α -cluster generator coordinate method (GCM). The small-amplitude vibration modes are described by coherent one-particle one-hole excitations expressed by a small shift of single-nucleon Gaussian wave functions within the AMD framework, whereas the large-amplitude cluster modes are incorporated by superposing 3 α -cluster wave functions in the GCM. The coupling of the excitations in the intrinsic frame with the rotation and parity transformation is taken into account microscopically by the angular-momentum and parity projections. The present a calculation that describes the ISM and ISD excitations over a wide energy region covering cluster modes in the low-energy region and the giant resonances in the high-energy region, although the quantitative description of the high-energy part is not satisfactory. The low-energy ISM and ISD strengths of the cluster modes are enhanced by the distance motion between α clusters, and they split into a couple of states because of the angular motion of α clusters. The low-energy ISM strengths exhaust 26% of the energy-weighted sum rule, which is consistent with the experimental data for the 12C(02+; 7.65 MeV) and 12C(03+; 10.3 MeV) measured by (e ,e') ,(α ,α') , and (6Li,6Li' ) scatterings. In the calculated low-energy ISD strengths, two 1- states (the 11- and 12- states) with the significant strengths are obtained over E =10 -15 MeV. The results indicate that the ISD excitations can be a good probe to experimentally search for new cluster states such as the 12C(12-) obtained in the present calculation.
Ledoux, R.J.; Ordonez, C.E.; Bechara, M.J.; Al-Juwair, H.A.; Lavelle, G.; Cosman, E.R.
1984-09-01
Excitation functions of the /sup 12/C(/sup 12/C, ..cap alpha..)/sup 20/Ne reaction were measured at Theta/sub lab/ = 7.5/sup 0/ between E/sub c.m./ = 14-40 MeV and angular distributions were measured from E/sub c.m./ = 17.8 to 20.6 MeV. Summed yields reveal prominent intermediate structure resonances over the entire range which correlate well to resonances previously observed in elastic data. The resonances show enhanced decays to excited rotational bands in /sup 20/Ne with reduced widths comparable to those for the elastic channel and an order of magnitude greater than those for the /sup 20/Ne ground state band. A discussion is given of the resonances as shape-isomeric states in a shell model secondary minimum in /sup 24/Mg, and of the selective alpha decay as being transitions to states of related configuration in /sup 20/Ne.
Ledoux, R.J.; Ordoez, C.E.; Bechara, M.J.; Al-Juwair, H.A.; Lavelle, G.; Cosman, E.R.
1984-09-01
Excitation functions of the /sup 12/C(/sup 12/C,..cap alpha..) /sup 20/Ne reaction were measured at theta/sub lab/ = 7.5/sup 0/ between E/sub c.m./ = 14--40 MeV and angular distributions were measured from E/sub c.m./ = 17.8 to 20.6 MeV. Summed yields reveal prominent intermediate structure resonances over the entire range which correlate well to resonances previously observed in elastic data. The resonances show enhanced decays to excited rotational bands in /sup 20/Ne with reduced widths comparable to those for the elastic channel and an order of magnitude greater than those for the /sup 20/Ne ground state band. A discussion is given of the resonances as shape-isomeric states in a shell model secondary minimum in /sup 24/Mg, and of the selective alpha decay as being transitions to states of related configuration in /sup 20/Ne.
A procedure to connect a model-independent phase-shift analysis with the solution of the inverse quantum scattering problem has been developed and applied to experimental differential cross sections of 12C+12C elastic scattering in the energy range Ec.m.=8--12 MeV. The minimization of the error square function χ2 is performed with respect to the spectral coefficients involved in the inverse procedure. Input quantities are measured differential cross sections; output results are complex potentials. The real part of the potentials, so obtained, is characterized by a pronounced minimum value of -(7--14) MeV at relative distances in the range 2.4--3 fm and by a Coulomb barrier of height 6--7 MeV in the outer region around r∼8--9 fm. In addition a second minimum, very shallow or vanishing at some incident energies, is found to exist in the region 5--6 fm. The imaginary part of the potential exhibits positive maxima in those regions of radial distances where the real part has minimum values indicating a possible feedback effect of flux to the elastic channel. The overall energy dependence of the potentials shows a shape transition resulting in diminishing the outer potential minimum between Ec.m. of 9 and 12 MeV. The inverted (real) potentials yield phase shifts of π/2 in those partial waves where resonances are known to exist. The procedure is tested by recalculating differential cross sections from the inverted energy-dependent potentials with the result that consistent agreement with the experimental input data is found
Refractive effects and Airy structure in inelastic $^{16}$O+$^{12}$C rainbow scattering
Ohkubo, S; Ogloblin, A A; Gloukhov, Yu A; Dem'yanova, A S; Trzaska, W H
2014-01-01
Inelastic $^{16}$O +$^{12}$C rainbow scattering to the $2^+$ (4.44 MeV) state of $^{12}$C was measured at the incident energies, $E_L$ = 170, 181, 200, 260 and 281 MeV. A systematic analysis of the experimental angular distributions was performed using the coupled channels method with an extended double folding potential derived from realistic wave functions for $^{12}$C and $^{16}$O calculated with a microscopic $\\alpha$ cluster model and a finite-range density-dependent nucleon-nucleon force.The coupled channels analysis of the measured inelastic scattering data shows consistently some Airy-like structure in the inelastic scattering cross sections for the first $2^+$ state of $^{12}$C, which is somewhat obscured and still not clearly visible in the measured data. The Airy minimum was identified from the analysis and the systematic energy evolution of the Airy structure was studied. The Airy minimum in inelastic scattering is found to be shifted backward compared with that in elastic scattering.
Further evidence for a dynamically generated secondary bow in $^{13}$C+$^{12}$C rainbow scattering
Ohkubo, S; Ogloblin, A A
2015-01-01
The existence of a secondary bow is confirmed for 13C+12C nuclear rainbow scattering in addition to the 16O+12C system. This is found by studying the experimental angular distribution of 13C+12C scattering at the incident 13C energy $E_L$=250 MeV with an extended double folding (EDF) model that describes all the diagonal and off-diagonal coupling potentials derived from the microscopic wave functions for 12C using a density-dependent nucleon-nucleon force. The Airy minimum at \\theta$ $\\approx$70$^\\circ$, which is not reproduced by a conventional folding potential, is revealed to be a secondary bow generated dynamically by a coupling to the excited state 2+ (4.44 MeV) of 12C. The essential importance of the quadruple {\\it Y2} term (reorientation term) of potential of the excited state 2+ of 12C for the emergence of a secondary bow is found. The mechanism of the secondary bow is intuitively explained by showing how the trajectories are refracted dynamically into the classically forbidden angular region beyond t...
Quasi-bound alpha resonant states populated by the 12C(6Li, d) reaction
Full text: The alpha cluster phenomenon in the light nuclei structure has been the subject of a long time investigation since the proposal of the Ikeda diagrams [1]. The main purpose of the research program in progress is the investigation of this phenomenon in (xα) and (xα+n) nuclei through the (6Li, d) alpha transfer reaction [2-4]. Alpha resonant states around the (4α) threshold in the nucleus 16O are the focus of the present contribution. In fact, the importance of these resonances at the elements production in stars is recognized, as primarily pointed out by Hoyle in 12C [6]. The existence of a rotational band with the α +12 C (Hoyle) cluster state structure was recently demonstrated by Ohkubo and Hirabayashi [6]. In order to explore this region of interest, measurements of the 12C(6Li, d)16O reaction up to 17 MeV of excitation at an incident energy of 25.5 MeV, have been performed employing the Sao Paulo Pelletron-Enge Split-Pole facility and the nuclear emulsion detection technique (plates Fuji G6B, 50 μm thick). Spectra associated with six scattering angles, from 5 deg to 29 deg in the laboratory frame, each one 50 cm along the focal surface, were measured. Several narrow resonances with a quasi-bound behavior embedded in the continuum were detected and the resolution of 25 keV allowed for the separation of doublets not resolved before [7,8]. The absolute cross sections and the respective deuteron angular distributions were determined and the analysis is in progress. [1] K. Ikeda et al., Prog. Theor. Phys. Suppl. E 68, 464 (1968); H. Horiuchi, K. Ikeda, and Y. Suzuki, ibid. 44, 225 (1978). [2] M.R.D.Rodrigues et al., in12th International Conference on Nuclear Reaction Mechanism, Varenna, Italy, edited by F. Cerutti and A. Ferrari , CERN Proceedings, 2010-2, pp. 331- 335. [3] T. Borello-Lewin et al., Proceedings of SOTANCP2, Brussels, Belgium 2010, edited by P. Descouvemount et al., Int. J. Mod. Mod. Phys E 20, 1018-1021 (2011). [4] T. Borello-Lewin et
Scattering resonances in graphene
Nazarov, V. U.; Silkin, V. M.; Krasovskii, E. E.
2012-01-01
We address the two-dimensional band-structure of graphene above the vacuum level in the context of discrete states immersed in the three-dimensional continuum. Scattering resonances are discovered that originate from the coupling of the in-plane and perpendicular motions, as elucidated by the analysis of an exactly solvable model. Some of the resonances turn into true bound states at high-symmetry $\\kv$ vectors. {\\it Ab initio} scattering theory verifies the existence of the resonances in rea...
Elastic scattering of 3He by 12C at 40.9 MeV energy
The elastic scattering of 40.9 MeV 3He-particles from 12C was investigated in the framework of the simple one-channel optical model. An overall good fit could be obtained. The ambiguities of the real central potential are discussed. (author)
Study of elastic and inelastic scattering of 12C on 40Ca and 48Ca
Angular distributions in elastic and inelastic scattering of 12C on 40Ca and 48Ca at 34.6 MeV (c.m.) were measured. The experimental results are presented and discussed using the optical model and the semi-classical analysis
Elastic scattering of 6He from 12C at 38.3 MeV/nucleon
DONG Hong-Fei; MA Yin-Qun; MA Zhong-Yu
2009-01-01
The microscopic optical potential of nucleus-nucleus interaction is presented via a folding method with the isospin dependent complex nucleon-nuclear potential, which is first calculated in the framework of the Dirac-Bruecker-Hartree-Fock approach. The elastic scattering data of 6He at 229.8 MeV on 12C target are analyzed within the standard optical model. To take account of the breakup effect of 6He in the reaction an enhancing factor 3 on the imaginary potential is introduced. The calculated 6He+12C elastic scattering differential cross section is in good agreement with the experimental data. Comparisons with results in the double-folded model based on the M3Y nucleon-nucleon effective interaction and the few the body Glauber-model calculations are discussed. Our parameter free model should be of value in the description of nucleus-nucleus scattering, especially unstable nucleus-nucleus systems.
Excitation function of elastic scattering on 12C + 4He system, at low energies
Interactions in the 12C + 4He system are of great interest in astrophysics and to help determine the relative abundances of elements in stars, at the end of helium burning [1, 2]. The Instituto Nacional de Investigaciones Nucleares (ININ) in Mexico, have made measurements of elastic scattering for this system, using the inverse kinematics method with thick white gas [3, 4], for E CM (0.5 - 4 MeV) θ CM = 180o. In this work we obtain excitation functions of elastic scattering of 12C + 4He system with angular and energy dependence; ECM = 0.5 - 4 MeV and θCM 100o -170o.Using inverse kinematics method with thick white gas and energy loss tables. (Author)
4.2 GeV α-12C Elastic Scattering Based on α-Particle Model
YANG Yong-Xu; LU Xiao; LI Qing-Run
2008-01-01
Based on the a-particle model of 12C nucleus, the differential cross sections for α-12 C elastic scattering at incident energy of 4.2 GeV have been calculated within the framework of Glauber multiple scattering theory. The results show that the main features of the measured angular distribution of the cross sections can be reasonably described. The parameterizedα-α scattering amplitude, which is the basic input to construct the α-12C scattering Glauber amplitude in the a-particle model, is obtained by fitting the α-α scattering data.
Elastic scattering and total reaction cross sections for 8Li+12C
Full text: The elastic scattering angular distribution for 8Li on 12C has been measured at ELAB= 23.9 MeV with 8Li radioactive nuclear beam produced by the Radioactive Ion Beams in Brazil facility (RIBRAS). This angular distribution was analysed in terms of optical model with Woods-Saxon and double-folding Sao Paulo potentials. The roles of the breakup and inelastic channels were also investigated with cluster folding and deformed potentials, respectively, through coupled channels calculations. The angular distributions for the proton-transfer 12C(8Li,9Be)11B reaction was also measured at the same energy, simultaneously with the elastic scattering. The spectroscopic factor for the 9Be I 8Li+p> bound system was obtained through DWBA (Distorted-Wave Born Approximation) calculations with the code Fresco, and compared with shell model calculations and other experimental values. The spectroscopic factor obtained was used for normalization of the capture reaction cross section 8Li(p, gamma)9Begs. The depth of the scattered potential obtained was 40,1 +- 1,6 MeV. The astrophysical S-factor curves and the reaction rate for the capture reaction 8Li(p,gamma)9Begs were calculated. Total reaction cross sections for the present system were also extracted from the elastic scattering analysis. A systematic of the reduced reaction cross section obtained from the present and published data on 6;7;8Li isotopes on 12C was performed as a function of energy. (author)
A fully microscopic model of 200 MeV proton-12C elastic and inelastic scattering
An effective two nucleon (NN) interaction in the nuclear medium is defined from an accurate mapping of the NN g matrices obtained by solving the Brueckner-Bethe-Goldstone equations for infinite nuclear matter. That effective interaction is used in a fully microscopic calculation of the nonlocal effective proton-12C interaction from which are obtained predictions of the differential cross section and analysing power for 200 MeV elastic scattering. The relative motion wave functions so found are used as the distorted waves in a distorted wave approximation (DWA) study of select inelastic scattering events. The effective NN interaction is used as the transition operator in those calculations. The relevant nuclear spectroscopy for the elastic and DWA (p, p') calculations is found from a full (0 + 2) ℎω shell model evaluation of the positive parity states while a restricted (1 + 3)ℎω has been used to give the negative parity states. Results are compared with those of the 0p-shell model of Cohen and Kurath or with those based upon axially symmetric, projected Hartree-Fock calculations. The diverse structure model wave functions are assessed by using them in calculations to compare with measured longitudinal, transverse electric and transverse magnetic form factors from electron scattering to many of the excited states of 12C. Using those models of the structure of 12C in the completely microscopic model of the elastic and inelastic scattering of 200 MeV protons, good fits have been found to the cross section and analysing power data. 50 refs., 3 tabs., 20 figs
Studies of elastic scattering and cross sections of the 12C + 28Si system
Angular distributions of the elastic scattering of the system 12C+28Si were measured at the energies ECM = 14.70; 16.08; 18.90; 20,97; 21.87 MeV, in the angular range 150 ≤ θCM ≤ 1700, with angular steps of 10. Other seven angular distributions measured by Villari, Ost and Cheng at energies ECM = 17.50; 19.60; 20.30; 22.40; 23.80; 24.50 and 25.20 MeV, have also been used in our analysis. The angular distributions have been reproduced by optical model calculations and new optical potentials for the system 12C+28Si were obtained. Calculations of the total reaction cross section from the elastic scattering data using a model independent method were done. The results were compared with fusion cross section data and with total reaction cross sections obtained via optical model calculations. Finally experimental angular distributions were analysed by phase shift analysis and the problem of unicity and ambiguities of the scattering matrix S(l) was discussed. (author)
Neutral weak-current two-body contributions in inclusive scattering from {sup 12}C
Lovato, Alessandro [ANL; Gandolfi, Stefano [LANL; Carlson, Joseph [LANL; Pieper, S. C. [ANL; Schiavilla, Rocco [JLAB, ODU
2014-05-01
An {\\it ab initio} calculation of the sum rules of the neutral weak response functions in $^{12}$C is reported, based on a realistic Hamiltonian, including two- and three-nucleon potentials, and on realistic currents, consisting of one- and two-body terms. We find that the sum rules of the response functions associated with the longitudinal and transverse components of the (space-like) neutral current are largest and that a significant portion ($\\simeq 30$\\%) of the calculated strength is due to two-body terms. This fact may have implications for the MiniBooNE and other neutrino quasi-elastic scattering data on nuclei.
Compton scattering from 12C using tagged photons in the energy range 65 - 115 MeV
Myers, L S; Preston, M F; Anderson, M D; Annand, J R M; Boselli, M; Briscoe, W J; Brudvik, J; Capone, J I; Feldman, G; Fissum, K G; Hansen, K; Henshaw, S S; Isaksson, L; Jebali, R; Kovash, M A; Lewis, K; Lundin, M; MacGregor, I J D; Middleton, D G; Mittelberger, D E; Murray, M; Nathan, A M; Nutbeam, S; O'Rielly, G V; Schröder, B; Seitz, B; Stave, S C; Weller, H R
2014-01-01
Elastic scattering of photons from 12C has been investigated using quasi-monoenergetic tagged photons with energies in the range 65 - 115 MeV at laboratory angles of 60 deg, 120 deg, and 150 deg at the Tagged-Photon Facility at the MAX IV Laboratory in Lund, Sweden. A phenomenological model was employed to provide an estimate of the sensitivity of the 12C(g,g)12C cross section to the bound-nucleon polarizabilities.
16O resonances near 4α threshold through 12C(6Li,d) reaction
Several narrow alpha resonant 16O states were detected through the 12C(6Li,d) reaction, in the range of 13.5 to 17.5 MeV of excitation energy. The reaction was measured at a bombarding energy of 25.5 MeV employing the São Paulo Pelletron-Enge-Spectrograph facility and the nuclear emulsion technique. Experimental angular distributions associated with natural parity quasi-bound states around the 4α threshold are presented and compared to DWBA predictions. The upper limit for the resonance widths obtained is near the energy resolution (15 keV)
Elastic Neutron Scattering at 96 MeV from {sup 12}C and {sup 208}Pb
Klug, J.; Blomgren, J.; Atac, A. [and others
2003-04-01
A facility for detection of scattered neutrons in the energy interval 50-130 MeV, SCANDAL (SCAttered Nucleon Detection AssembLy), has recently been installed at the 20-180 MeV neutron beam line of the The Svedberg Laboratory, Uppsala. Elastic neutron scattering from {sup 12}C and {sup 208}Pb has been studied at 96 MeV in the 10-70 deg interval. The achieved energy resolution, 3.7 MeV, is about an order of magnitude better than for any previous experiment above 65 MeV incident energy. The present experiment represents the highest neutron energy where the ground state has been resolved from the first excited state in neutron scattering. A novel method for normalization of the absolute scale of the cross section has been used. The estimated uncertainty, 3 %, is unprecedented for a neutron-induced differential cross section measurement on a nuclear target. The results are compared with modern optical model predictions, based on phenomenology or microscopic nuclear theory.
Elastic Neutron Scattering at 96 MeV from 12C and 208Pb
A facility for detection of scattered neutrons in the energy interval 50-130 MeV, SCANDAL (SCAttered Nucleon Detection AssembLy), has recently been installed at the 20-180 MeV neutron beam line of the The Svedberg Laboratory, Uppsala. Elastic neutron scattering from 12C and 208Pb has been studied at 96 MeV in the 10-70 deg interval. The achieved energy resolution, 3.7 MeV, is about an order of magnitude better than for any previous experiment above 65 MeV incident energy. The present experiment represents the highest neutron energy where the ground state has been resolved from the first excited state in neutron scattering. A novel method for normalization of the absolute scale of the cross section has been used. The estimated uncertainty, 3 %, is unprecedented for a neutron-induced differential cross section measurement on a nuclear target. The results are compared with modern optical model predictions, based on phenomenology or microscopic nuclear theory
Using a partial wave analysis the angular distributions measured for the reactions 11B (p,p') 11B* and 11B (p,a) 8Be in the energy range from 4.5 to 7.5 MeV the resonance states of 12C were determined including level widths, spin, parity, and isopin. (HSI)
He, W B; Cao, X G; Cai, X Z; Zhang, G Q
2014-01-01
It is studied how the $\\alpha$ cluster degrees of freedom, such as $\\alpha$ clustering configurations close to the $\\alpha$ decay threshold in $^{12}$C and $^{16}$O, including the linear chain, triangle, square, kite, and tetrahedron, affect nuclear collective vibrations with a microscopic dynamical approach, which can describe properties of nuclear ground states well across the nuclide chart and reproduce the standard giant dipole resonance (GDR) of $^{16}$O quite nicely. It is found that the GDR spectrum is highly fragmented into several apparent peaks due to the $\\alpha$ structure. The different $\\alpha$ cluster configurations in $^{12}$C and $^{16}$O have corresponding characteristic spectra of GDR. The number and centroid energies of peaks in the GDR spectra can be reasonably explained by the geometrical and dynamical symmetries of $\\alpha$ clustering configurations. Therefore, the GDR can be regarded as a very effective probe to diagnose the different $\\alpha$ cluster configurations in light nuclei.
Investigation of 16O+12C refractive elastic scattering using the α-cluster model potential
Differential cross-section of the 16O+12C elastic scattering at Elab = 132, 181, 200, 260, 300, 608 and 1503MeV has been reanalyzed in the framework of double-folding cluster (DFC1) potential over a wide angular range which cover both diffractive and refractive regions. Based upon the α-cluster structure of both colliding nuclei, the real DFC1 optical potential has been generated by using α-α effective interaction and new cluster modified Gaussian (CMGD) of target and projectile has also been extracted. Successful descriptions of the data were obtained over the full measured angular range at all considered energies. The results have been compared with the findings obtained by using the phenomenological approach as well as experimental data. Furthermore, the consistency between the real and imaginary volume integrals is checked by the dispersion relation and the total reaction cross-section has also been investigated. (orig.)
Ou, I.; Yamada, Y.; Mori, T.; Yano, T.; Sakuda, M. [Department of Physics, Okayama University, Okayama 700-8530 (Japan); Tamii, A.; Suzuki, T.; Yosoi, M.; Aoi, N.; Ideguchi, E.; Hashimoto, T.; Miki, K.; Ito, T.; Iwamoto, C.; Yamamoto, T. [Research Center for Nuclear Physics (RCNP), Osaka University, Ibaraki, Osaka 567-0047 (Japan); Akimune, H. [Department of Physics, Konan University, Okamoto 8-9-1, Higashinada, Kobe 658-8501 (Japan)
2015-05-15
We propose to measure the γ-ray emission probability from excited states above 5 MeV including giant resonance of {sup 16}O and {sup 12}C as a function of excitation energy in 1-MeV step. Here, we measure both the excitation energy (E{sub x}=5-30MeV) at the forward scattering angles (0°-3°) of the {sup 16}O, {sup 12}C (p, p’) reaction using Grand-Raiden Spectrometer and the energy of γ-rays (E{sub γ}) using an array of NaI(Tl) counters. The purpose of the experiment is to provide the basic and important information not only for the γ-ray production from primary neutral-current neutrino-oxygen (-carbon) interactions but also for that from the secondary hadronic (neutron-oxygen and -carbon) interactions.
We propose to measure the γ-ray emission probability from excited states above 5 MeV including giant resonance of 16O and 12C as a function of excitation energy in 1-MeV step. Here, we measure both the excitation energy (Ex=5-30MeV) at the forward scattering angles (0°-3°) of the 16O, 12C (p, p’) reaction using Grand-Raiden Spectrometer and the energy of γ-rays (Eγ) using an array of NaI(Tl) counters. The purpose of the experiment is to provide the basic and important information not only for the γ-ray production from primary neutral-current neutrino-oxygen (-carbon) interactions but also for that from the secondary hadronic (neutron-oxygen and -carbon) interactions
Inelastic proton scattering at 30--40 MeV from 12C
Elastic and inelastic proton differential cross sections for excitation of the following levels of 12C: 21+(4.43 MeV), 41+(14.08 MeV), 02+(7.65 MeV), and 31-(9.64 MeV) have been measured at three incident energies between 30 and 40 MeV. The data have been described by coupled channel calculations and form factors obtained by coupling surface vibrations to static deformations. The reproduction of the 02+ state data, if this state is assumed to be a β-vibrational state, requires a quadrupole β-vibrational amplitude which is 57% of the static quadrupole deformation and a mixing of the breathing mode of the nucleus with an amplitude that would correspond to about 1% of the E0 energy weighted sum rule. For the 31- state it is found that the performed calculations are sensitive to the K projection, with the angular distribution of the 31- state being better fitted assuming K/sup π/ = 3- band. Coupled channel calculations using microscopic form factors obtained from wave functions generated using the resonating group method have also been performed and are compared to the experimental data
Quasi-bound alpha resonant states populated by the {sup 12}C({sup 6}Li, d) reaction
Rodrigues, M.R.D.; Borello-Lewin, T.; Miyake, H.; Horodynski-Matsushigue, L.B.; Duarte, J.L.M.; Rodrigues, C.L.; Souza, M.A. [Universidade de Sao Paulo (IF/USP), SP (Brazil). Inst. de Fisica; Cunsolo, A.; Cappuzzello, F.; Foti, A.; Agodi, C.; Cavallaro, M. [Istituto Nazionale di Fisica Nucleare (LNS/INFN), Catania (Italy). Lab. Nazionali del Sud; Ukita, G.M. [Universidade de Santo Amaro (UNISA), Sao Paulo, SP (Brazil). Faculdade de Psicologia
2012-07-01
Full text: The alpha cluster phenomenon in the light nuclei structure has been the subject of a long time investigation since the proposal of the Ikeda diagrams [1]. The main purpose of the research program in progress is the investigation of this phenomenon in (x{alpha}) and (x{alpha}+n) nuclei through the ({sup 6}Li, d) alpha transfer reaction [2-4]. Alpha resonant states around the (4{alpha}) threshold in the nucleus {sup 16}O are the focus of the present contribution. In fact, the importance of these resonances at the elements production in stars is recognized, as primarily pointed out by Hoyle in {sup 12}C [6]. The existence of a rotational band with the {alpha} +{sup 12} C (Hoyle) cluster state structure was recently demonstrated by Ohkubo and Hirabayashi [6]. In order to explore this region of interest, measurements of the {sup 12}C({sup 6}Li, d){sup 16}O reaction up to 17 MeV of excitation at an incident energy of 25.5 MeV, have been performed employing the Sao Paulo Pelletron-Enge Split-Pole facility and the nuclear emulsion detection technique (plates Fuji G6B, 50 {mu}m thick). Spectra associated with six scattering angles, from 5 deg to 29 deg in the laboratory frame, each one 50 cm along the focal surface, were measured. Several narrow resonances with a quasi-bound behavior embedded in the continuum were detected and the resolution of 25 keV allowed for the separation of doublets not resolved before [7,8]. The absolute cross sections and the respective deuteron angular distributions were determined and the analysis is in progress. [1] K. Ikeda et al., Prog. Theor. Phys. Suppl. E 68, 464 (1968); H. Horiuchi, K. Ikeda, and Y. Suzuki, ibid. 44, 225 (1978). [2] M.R.D.Rodrigues et al., in12th International Conference on Nuclear Reaction Mechanism, Varenna, Italy, edited by F. Cerutti and A. Ferrari , CERN Proceedings, 2010-2, pp. 331- 335. [3] T. Borello-Lewin et al., Proceedings of SOTANCP2, Brussels, Belgium 2010, edited by P. Descouvemount et al., Int. J
Resonantly scattering crystals and surfaces
We examine coherence effects from forming a crystal of resonant scatterers by generalising the Fano model for autoionising resonances in electron scattering from atoms to a lattice of such scatterers. (We have in mind the case of neutron scattering from nuclei.) We solve this problem to yield two branches to the dispersion relation for the neutron in general and three when the resonance coincides with a Brillouin Zone boundary. The 'width' of the resonance is enhanced over the isolated nucleus, the best candidate for observation being the 2eV 185Re resonance near the Bragg condition. We use these results to calculate the reflection coefficient from a surface, revealing total external reflection near resonance. We discuss experimental feasibility in both the neutron and electron cases. (author)
Diffraction scattering of 7Be and 8B on 12C taking into account the coulomb interaction
The differential cross sections for scattering of 7Be and 8B nuclei on 12C nuclei are calculated in the framework of general theory of diffraction interactions of nuclei consisting of two charged weakly-bound clusters. Available experimental data are analyzed. (author)
Quasi-Elastic Scattering of 16C from 12C at 47.5 MeV/Nucleon
FAN Feng-Ying; ZHENG Tao; YE Yan-Lin; JIANG Dong-Xing; HUA Hui; LI Zhi-Huan; GE Yu-Cheng; LI Xiang-Qing; LOU Jian-Ling; SHI Fan; LV Lin-Hui; CAO Zhong-Xin; NIE Peng-Xuan; LI Qi-Te; SONG Yu-Shou; LU Fei; XU Hu-Shan; HU Zheng-Guo; WANG Meng; ZHANG Xue-Ying; LI Chen; CHEN Ruo-Fu; TANG Bin; XU Zhi-Guo; YUE Ke; ZHANG Ya-Peng; ZANG Yong-Dong; ZHANG Xue-Heng; YAO Xiang-Wu; CHEN Jin-Da; TU Xiao-Lin; ZHANG Jie; WU Da-Peng; BAI Zhen
2009-01-01
Differential cross sections for the quasi-elastic scattering of 16C at 47.5 MeV/nucleon from 12C target are measured.Coupled-channels calculations are carried out and the optical potential parameters are obtained by fitting the experimental angular distribution.
Elastic and inelastic scattering of 800 MeV/c K+- mesons from 12C and 40Ca
Methods and results of an experiment to study the scattering of 800 MeV/c K+- mesons from 12C and 40Ca are presented. The reactions under study include: the four elastic scattering reactions 12C(K+-,K+-) and 40Ca(K+-,K+-), and the four inelastic scattering reactions, 12C(K+-.K+-') to the J/sup P/ = 2+ 4.43 MeV and J/sup P/ = 3- states. The experimental data were obtained using the Hyper-Nuclear Spectrometer and the Low Energy Separated Beam (LESB I) at the Alternating Gradient Synchrotron (AGS) of Brookhaven Laboratory (BNL). Calculations using the program PIRK, an optical potential code, are compared to the elastic data. The results of a second set of calculations, using Glauber theory are also presented. Both sets of calculations use as input: the results of partial wave analyses of kaon nucleon scattering data, and nuclear shapes as determined from the results of electron nucleus scattering experiments. The agreement between the experimental data and the theoretical predictions is reasonable over the angular range of the data, with the exception of Glauber calculations of the K+ elastic scattering. In those cases, the eikonal approximation proves to be a poor approximation. Smaller discrepancies are found in some other cases, indicating the possible need for more sophisticated calculations
Scattering of solitons on resonance
Kiselev, O M; Glebov, S. G.
2004-01-01
We investigate a propagation of solitons for nonlinear Schrodinger equation under small driving force. The driving force passes the resonance. The process of scattering on the resonance leads to changing of number of solitons. After the resonance the number of solitons depends on the amplitude of the driving force.
(π±, π±' N) reactions on 12C and 208Pb near the giant resonance region
Angular distributions for the 12C(π±, π±' p) and 208Pb(π±, π±' p or n) reactions near the giant resonance region have been measured at Tπ = 180 MeV, and found different between π+ and π- data. This observation is interpreted as evidence for different excitation mechanisms dominating the π--nucleus and π+-nucleus interactions in the giant resonance region of these targets. A comparison with the single-nucleon knock-out distorted-wave impulse approximation calculations shows, even though these calculations underestimate (π±, π±' N) data for both targets, the dominance of direct process for (π+, π+' p) or (π-, π-' n) in contrast to (π-, π-' p) or (π+, π+' n). In the (π+, π+' p) reaction proton-proton hole states are excited directly and appear to have a large probability for direct decay with escape width, whereas in (π-, π-' p) the preferentially excited neutron-neutron hole doorway states couple to resonance states and decay with spreading width. This interpretation led us to suggest that the ratio of cross-sections for inelastic scattering to the giant resonance region should be written in terms of an incoherent sum of cross-sections to neutron and proton doorway states. In a heavy nucleus such as 208Pb, neutron and proton doorway states. In a heavy nucleus such as 208Pb, neutron and proton doorway states contribute incoherently because the different decay processes do not populate the same final states of the residual nucleus
I Ahmad; M R Arafah
2006-03-01
Elastic scattering of 800 MeV/c pions by 12C has been studied in the diffraction model with a view to determine pion optical potential by the method of inversion. Finding an earlier diffraction model analysis to be deficient in some respects, we propose a Glauber model based parametrization for the elastic -matrix and show that it provides an exceedingly good fit to the pion-carbon data. The proposed elastic -matrix gives a closed expression for the pion-12C optical potential by the method of inversion in the high energy approximation.
Quasi-elastic scattering of 6He, 7Be, and 8B nuclei by 12C nuclei
Kovalchuk, V I
2016-01-01
The observed cross sections of quasi-elastic scattering of 6He, 7Be, and 8B nuclei by 12C nuclei are described within the framework of the diffraction nuclear model and the model of nucleus-nucleus scattering in the high-energy approximation with a double folding potential, for intermediate energies of the incident particles. The calculations make use of realistic distributions of nucleon densities and take account of the Coulomb interaction and inelastic scattering with excitation of low-lying collective states of the target.
Isoscalar monopole and dipole excitations of cluster states and giant resonances in $^{12}$C
Kanada-En'yo, Yoshiko
2015-01-01
The isoscalar monopole(ISM) and dipole(ISD) excitations in $^{12}$C are theoretically investigated with the shifted antisymmetrized molecular dynamics(AMD) plus $3\\alpha$-cluster generator coordinate method(GCM). The small amplitude vibration modes are described by coherent one-particle one-hole excitations expressed by small shift of single-nucleon Gaussian wave functions within the AMD framework, whereas the large amplitude cluster modes are incorporated by superposing $3\\alpha$-cluster wave functions in the GCM. The coupling of the excitations in the intrinsic frame with the rotation and parity transformation is taken into account microscopically by the angular-momentum and parity projections. The present calculation describes the ISM and ISD excitations in a wide energy region covering cluster modes in the low-energy region and the giant resonances in the high-energy region, though the quantitative description of the high-energy part is not satisfactory. The low-energy ISM and ISD strengths of the cluster...
Nanocatalytic resonance scattering spectral analysis
无
2010-01-01
The resonance scattering spectral technique has been established using the synchronous scanning technique on spectrofluorometry.Because of its advantages of simplicity,rapidity and sensitivity,it has been widely applied to analyses of proteins,nucleic acids and inorganic ions.This paper summarizes the application of immunonanogold and aptamer modified nanogold(AptAu) catalytic resonance scattering spectral technique in combination with the work of our group,citing 53 references.
Local and non-local equivalent potentials for p-12C scattering
Lovell, A.; Amos, K.
2000-01-01
A Newton-Sabatier fixed energy inversion scheme has been used to equate inherently non-local p-${}^{12}$C potentials at a variety of energies to pion threshold, with exactly phase equivalent local ones. Those energy dependent local potentials then have been recast in the form of non-local Frahn-Lemmer interactions.
We measured six fairly complete angular distributions of elastic, inelastic and α-transfer reactions of the 12C+24Mg system ar Ecm = 25.2 MeV. We performed coupled channels calculations using the Algebraic Scattering Theory with nuclear algebraic potential derived from nuclear phase shifts and using available structure informations for the inelastic coupling strengths. The back angle rise in the elastic cross section is fully explained by the couplings between elastic and transfer channels. (author)
Measurement of spectra of (e,e') scattering on 9Be and 12C nuclei in inelastic region at Q22/c2
The spectra of the (e,e')-scattering on 9Be and 12C nuclei in the region of quasielastic scattering and Δ33-resonance production at angles 16 and 18 deg and primary electron energies from 1.45 GeV to 2.13 GeV are measured. A model-independent account of radiative distortions at energies 1.93 and 2.13 GeV is made. A comparison with the nuclear shell model calculations is made. The experimental data are obtained at the Erevan electron synchrotron. The background conditions are improved and the energy coverage of the set-up is enlarged by the improvement of the extraction path and pulse hodoscope of the spectrometer. 13 refs.; 5 figs
Polarized Elastic Fast-Neutron Scattering off 12C in the Lower MeV-Range. I. Experimental Part
Practical as well as more fundamental interest in low-energy n-12C elastic scattering motivated the execution of comprehensive polarization studies between 1.062 and 2.243 MeV. Seven complete polarization angular distributions were obtained from experimental finite-geometry left-right ratios at each energy observed at six or seven laboratory scattering angles between 30 and 129 deg, using polarized fast-neutrons emitted at θi 50 (lab. syst.) from the 7Li(p, n) 7Be-reaction. Proper corrections were applied for finite geometry and polarized multiple-scattering effects as well as for the presence of the first-excited state group of fast-neutrons in the incident beams. The magnitude of the polarization effects are sufficiently large to ensure the potentialities of 12C as an acceptable fast-neutron polarization analyser in the energy range under consideration. Furthermore, on the basis of the above-mentioned polarization data as well as on the basis of total and differential scattering cross section data available in current literature reliable phase shifts were determined. These phase shifts are only in partial agreement with the ones of Wills, Jr. et al. , and in definite disagreement with the extrapolated phases of Meier, Scherrer, and Trumpy. Their energy variations will be predicted in the theoretical part of this contribution
Measurement of quasi-elastic 12C(p,2p) scattering at high momentum transfer
Mardor, Y.; Aclander, J.; Alster, J.; Barton, D; Bunce, G.; Carroll, A.; Christensen, N.; Courant, H.; Durrant, S.; Gushue, S.; Heppelmann, S.; Kosonovsky, E.; Mardor, I.; Marshak, M.; Makdisi, Y.
1997-01-01
We measured the high-momentum quasi-elastic 12C(p,2p) reaction (at center of mass angle near 90 degrees) for 6 and 7.5 GeV/c incident protons. The three-momentum components of both final state protons were measured and the missing energy and momentum of the target proton in the nucleus were determined. The validity of the quasi-elastic picture was verified up to Fermi momenta of about 450 MeV/c, where it might be questionable. Transverse and longitudinal Fermi momentum distributions of the ta...
A fully microscopic model of 200 MeV proton-{sup 12}C elastic and inelastic scattering
Karataglidis, S.; Dortmans, P.J.; Amos, K.; de Swiniarski, R.
1996-03-01
An effective two nucleon (NN) interaction in the nuclear medium is defined from an accurate mapping of the NN g matrices obtained by solving the Brueckner-Bethe-Goldstone equations for infinite nuclear matter. That effective interaction is used in a fully microscopic calculation of the nonlocal effective proton-{sup 12}C interaction from which are obtained predictions of the differential cross section and analysing power for 200 MeV elastic scattering. The relative motion wave functions so found are used as the distorted waves in a distorted wave approximation (DWA) study of select inelastic scattering events. The effective NN interaction is used as the transition operator in those calculations. The relevant nuclear spectroscopy for the elastic and DWA (p, p`) calculations is found from a full (0 + 2) {Dirac_h}{omega} shell model evaluation of the positive parity states while a restricted (1 + 3){Dirac_h}{omega} has been used to give the negative parity states. Results are compared with those of the 0p-shell model of Cohen and Kurath or with those based upon axially symmetric, projected Hartree-Fock calculations. The diverse structure model wave functions are assessed by using them in calculations to compare with measured longitudinal, transverse electric and transverse magnetic form factors from electron scattering to many of the excited states of {sup 12}C. Using those models of the structure of {sup 12}C in the completely microscopic model of the elastic and inelastic scattering of 200 MeV protons, good fits have been found to the cross section and analysing power data. 50 refs., 3 tabs., 20 figs.
Elastic scattering of intermediate energy protons on 4He and 12C
The elastic angular distribution and polarization of 1.04 GeV protons on 4He and 12C have been analysed using the recently proposed correlated expansion for the Glauber amplitude by retaining terms up to three-body density only. The calculations include Coulomb and spin effects. Using realistic form factors for target nuclei it is found that we need to consider only up to the second-order density term to provide a satisfactory explanation of both kinds of experimental data in the available momentum transfer region. The contribution of the three-body density term is only marginal except in 4He differential cross-section in the c.m. angular range 4500. (author)
Neutron scattering from 12C in the few-MeV region
Neutron total cross sections of natural carbon are deduced from the observed transmission of approximately monoenergetic neutrons through carbon samples of varying thickness. The measurements extend from approximately equal to 0.1 to 4.5 MeV with resolutions of approximately equal to 2 to 100 keV. Neutron differential-elastic-scattering cross sections of natural carbon are measured from 1.5 to 4.0 MeV at incident-neutron energy intervals of approximately less than 100 keV, over an angular range of approximately equal to 20 to 1600 and with energy resolutions of 20 to 50 keV. The experimental results are interpreted in terms of a multilevel R-function analysis. Results are compared with the large body of measured and evaluated neutron total and scattering cross sections and scattered neutron polarizations reported in the literature. It is suggested that the observed neutron total and scattering cross sections of carbon are physically consistent and suitable for use as a reference standard in experimental studies of neutron processes. The R-function description should provide a convenient description of neutron total and scattering cross sections of carbon as a function of both angle and energy. 88 references
Well-verified models for elastic and inelastic scattering of fast neutrons (and protons) from 12C and 16O are translated into a useful form for transport, dosimetry, and scintillator response calculations. The information presented here is complementary to published calculations of secondary-particle production by incident neutrons in the energy region 15 ≤ En ≤ 60 MeV. Tables are given of Legendre expansion coefficients derived from fits to experimental cross sections at incident neutron energies En = 18-26 MeV and from fits to model predictions for 30- to 60-MeV neutrons. 11 refs., 8 tabs
{sup 16}O resonances near 4α threshold through {sup 12}C({sup 6}Li,d) reaction
Rodrigues, M. R. D.; Borello-Lewin, T.; Miyake, H.; Horodynski-Matsushigue, L. B.; Duarte, J. L. M.; Rodrigues, C. L.; Faria, P. Neto de [Instituto de Física, Universidade de São Paulo, Caixa Postal 66318, CEP 05314-970, São Paulo, SP (Brazil); Cunsolo, A.; Cappuzzello, F.; Foti, A.; Agodi, C.; Cavallaro, M. [INFN - Laboratori Nazionali del Sud, Via S. Sofia 62, 95125 Catania (Italy); Napoli, M. di; Ukita, G. M. [Faculdade de Psicologia, Universidade de Santo Amaro, R. Prof. Eneas da Siqueira Neto, 340, CEP 04829-300, São Paulo, SP (Brazil)
2014-11-11
Several narrow alpha resonant {sup 16}O states were detected through the {sup 12}C({sup 6}Li,d) reaction, in the range of 13.5 to 17.5 MeV of excitation energy. The reaction was measured at a bombarding energy of 25.5 MeV employing the São Paulo Pelletron-Enge-Spectrograph facility and the nuclear emulsion technique. Experimental angular distributions associated with natural parity quasi-bound states around the 4α threshold are presented and compared to DWBA predictions. The upper limit for the resonance widths obtained is near the energy resolution (15 keV)
Couture, Aaron Joseph [Los Alamos National Laboratory; Detwiler, Rebecca [UNIV OF FL; Gorres, Joachim [UNIV OF NOTRE DAME; Stech, Edward J [UNIV OF NOTRE DAME; Ugalde, Claudio [UNIV OF NOTRE DAME; Wiescher, Michael C F [UNIV OF NOTRE DAME; Heil, Michael [GSI DARMSTADT; Kappeler, Franz [FORSCHUNGSZENTRUM KARLSRUHE; Azuma, Richard E [UNIV OF TORONTO; Buchmann, Lothar [TRIUMF
2009-01-01
Recent global analyses of {sup 12}C({alpha},{gamma}){sup 16}O have incorporated both elastic-scallering and {beta}-decay data in addition to direct measurements. In that context, it has been shown that an improvement in the available elastic-scallering data could help determine the contribution of the two subthreshold states, 6.92(2{sup +}) and 7.12(1{sup -}) MeV, and with excellent statistics could restrict resonance parameters above the threshold. To this end angular distributions of {sup 12}C({alpha}, {alpha}){sup 12}C in the {alpha}-energy range of 2.6-8.2 MeV, at angles from 24 to 166 have been measured at the University of Notre Dame using an array of 32 silicon detectors. Details of the experiment are reported. In the present analysis, the phase shifts have been determined from our previously reported R-matrix fit to these data. The uncertainties in the R-matrix phase shifts ({ell} = 0...6) are derived by a new Monte Carlo analysis technique as described in the article. We provide these phase shifts here for general use, in particular for the improved analysis and extrapolation of the {alpha} radiative capture to low energies.
The detailed study of the pion-nucleus scattering in the range of the Δ(3.3) resonance permits statements on the behaviour of a strong resonance in the surrounding nuclear medium and raises by this the question for the importance of subnuclear degrees of freedom in the nucleus. In the present thesis the pion-nucleus reaction mechanism was studied by means of pion-γ-angular correlation measurements on the 12C(2+, 4.4 MeV) state. The experiments were performed at the Swiss Institute for Nuclear Research. The scattered pions were detected by the SUSI spectrometer to which in coincidence six NaI detectors for the detection of the emitted γ-quanta were operated. For the momentum transfer q = 0.47 fm-1 and pion incident energies of 116, 140, 162, 180, and 226 MeV respectively for the momentum transfer q = 0.85 fm-1 and incident energies of 116, 162, and 226 MeV values of the angular correlation function for in the mean each 16 γ emission angles within and beyond the reaction plane were determined. The measurement results are compared with DWIA calculations in the static limit and in the Δ-hole model. In the static limit the transition is described starting from the free pion-nucleon process whereby the dynamics of the intermediate Δ-resonance are suppressed. The Δ-hole model yields an additional microscopical description for the propagation of the Δ-resonance. The static model cannot reproduce the energy slope of the correlation function for q = 0.47 fm-1 while the Δ-hole model achieves a very good agreement. The experiment shows by this that the description of the pion-nucleus scattering in the resonance range requires the regard of medium effects especially from the Δ propagation. (orig.)
Quasi-free scattering off 12C in inverse kinematics at the R3B/LAND-setup
An important part of the physics program at the future R3B (Reactions with Relativistic Radioactive Beams) experiment at FAIR will be based on the study of proton-induced reactions in a kinematical complete measurement. These are in particular the quasi-free scattering processes of the type (p,2p), (p,pn), (p,pα) etc, which will be used to investigate the single-particle and cluster structure of neutron-proton asymmetric nuclei and the role of nucleon-nucleon correlations in nuclei. A prototype setup for the detection of high-energy protons in (p,2p) reactions in coincidence with forward emitted light particles and heavy fragments has been built based on an array of Si micro-strip detectors for tracking and thick NaI scintillators for energy measurements. A 12C beam has been chosen for the bench-mark experiment since its structure is well known, and results from proton- as well as electron-induced knockout reactions are available. First results on two-proton angular correlations and momentum distributions of the knocked-out protons inside 12C are discussed as well as the excitation energy spectrum of the residual 11B nuclei.
Elastic and inelastic scattering of 400 MeV polarised deuterons on 12C, 24Mg, 40Ca nuclei
This research thesis is based on an experiment of scattering of polarised 400 MeV deuterons on 12C, 24Mg, 40Ca nuclei, performed on the Saturne accelerator. The measured observables are the non-polarised cross section, and the powers of vector and tensor analysis. The author describes the experiment running and the installation, presents the various devices from source to detection and acquisition by the computer system. He reports the experiment compilation: reading of magnetic tapes, assessment and taking into account of the different experimental parameters. The calculation of scattering observables (cross section and powers of analysis) is performed by using experimental data. Spectra of these observables are represented for the different excited states of nuclei, after, should the occasion arise, Gaussian decomposition or background subtraction. The author reports the analysis of the obtained results. Results obtained for the three nuclei are compared between each other, and with scattering data for protons at similar energies which have already been measured. An analysis with a microscopic model is performed and the predictions of this model are compared with the obtained results
Hassanain, Mahmoud A. [King Khalid University, Department of Physics, Abha (Saudi Arabia); Assiut University, Department of Physics, New-Valley Faculty of Science, Assiut (Egypt)
2016-01-15
Differential cross-section of the {sup 16}O+{sup 12}C elastic scattering at E{sub lab} = 132, 181, 200, 260, 300, 608 and 1503MeV has been reanalyzed in the framework of double-folding cluster (DFC1) potential over a wide angular range which cover both diffractive and refractive regions. Based upon the α-cluster structure of both colliding nuclei, the real DFC1 optical potential has been generated by using α-α effective interaction and new cluster modified Gaussian (CMGD) of target and projectile has also been extracted. Successful descriptions of the data were obtained over the full measured angular range at all considered energies. The results have been compared with the findings obtained by using the phenomenological approach as well as experimental data. Furthermore, the consistency between the real and imaginary volume integrals is checked by the dispersion relation and the total reaction cross-section has also been investigated. (orig.)
Isotopic 13C/12C effect on the resonant Raman spectrum of twisted bilayer graphene
del Corro, E.; Kalbáč, Martin; Fantini, C.; Frank, Otakar; Pimenta, M. A.
2013-01-01
Roč. 88, č. 15 (2013), s. 155436. ISSN 1098-0121 R&D Projects: GA MŠk LL1301 Institutional support: RVO:61388955 Keywords : substrate * spectroscopy * scattering Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.664, year: 2013
Hamada, Sh; Burtebayev, N; Ohkubo, S
2013-01-01
Angular distributions for elastic and inelastic scattering of $^3$He from $^{12}$C were measured at energies 50.5 and 60 MeV. The Airy minimum of the prerainbow scattering was clearly observed in the angular distributions for the 0$_2^+$ (7.65 MeV) state of $^{12}$C (Hoyle state). The experimental results were analyzed with a coupled channels method with double folding potentials derived from the microscopic wave functions for the ground 0$_1^+$, 2$^+$ (4.44 MeV), 3$^-$ (9.64 MeV) and 0$_2^+$ states. The analysis supports the view that the Hoyle state is a three alpha particle condensate with a large radius of dilute matter distribution.
The triple alpha reaction rate and the 2$^+$ resonances in $^{12}$C
de Diego, R; Fedorov, D V; ~Jensen, A S
2010-01-01
The triple alpha rate is obtained from the three-body bound and continuum states computed in a large box. The results from this genuine full three-body calculation are compared with standard reference rates obtained by two sequential two-body processes. The fairly good agreement relies on two different assumptions about the lowest $2^+$ resonance energy. With the same $2^+$ energy the rates from the full three-body calculation are smaller than those of the standard reference. We discuss the rate dependence on the experimentally unknown $2^+$ energy. Substantial deviations from previous results appear for temperatures above $3$~GK.
Reinhardt, Tobias P; Bemmerer, Daniel; Stöckel, Klaus; Wagner, Louis
2016-01-01
Resonant nuclear reactions are a powerful tool for the determination of the amount and profile of hydrogen in thin layers of material. Usually, this tool requires the use of a standard of well-known composition. The present work, by contrast, deals with standard-less hydrogen depth profiling. This approach requires precise nuclear data, e.g. on the widely used $^{1}$H($^{15}$N,$\\alpha\\gamma$)$^{12}$C reaction, resonant at 6.4\\,MeV $^{15}$N beam energy. Here, the strongly anisotropic angular distribution of the emitted $\\gamma$-rays from this resonance has been re-measured, resolving a previous discrepancy. Coefficients of (0.38$\\pm$0.04) and (0.80$\\pm$0.04) have been deduced for the second and fourth order Legendre polynomials, respectively. In addition, the resonance strength has been re-evaluated to (25.0$\\pm$1.5)\\,eV, 10\\% higher than previously reported. A simple working formula for the hydrogen concentration is given for cases with known $\\gamma$-ray detection efficiency. Finally, the absolute approach i...
Absolute hydrogen depth profiling using the resonant 1H(15N, αγ)12C nuclear reaction
Reinhardt, Tobias P.; Akhmadaliev, Shavkat; Bemmerer, Daniel; Stöckel, Klaus; Wagner, Louis
2016-08-01
Resonant nuclear reactions are a powerful tool for the determination of the amount and profile of hydrogen in thin layers of material. Usually, this tool requires the use of a standard of well-known composition. The present work, by contrast, deals with standard-less hydrogen depth profiling. This approach requires precise nuclear data, e.g. on the widely used 1 H(15 N, αγ)12 C reaction, resonant at 6.4 MeV 15 N beam energy. Here, the strongly anisotropic angular distribution of the emitted γ -rays from this resonance has been re-measured, resolving a previous discrepancy. Coefficients of (0.38 ± 0.04) and (0.80 ± 0.04) have been deduced for the second and fourth order Legendre polynomials, respectively. In addition, the resonance strength has been re-evaluated to (25.0 ± 1.5) eV, 10% higher than previously reported. A simple working formula for the hydrogen concentration is given for cases with known γ -ray detection efficiency. Finally, the absolute approach is illustrated using two examples.
Cascades of Fano resonances in Mie scattering
Rybin, M. V.; Sinev, I. S.; Samusev, K. B.; Limonov, M. F.
2014-03-01
The interference nature of resonant Mie scattering, which is described within the Fano model, has been demonstrated. The interference is caused by interaction of an incident electromagnetic wave with reemitted waves that correspond to eigenmodes of a scattering particle. Mie scattering due to the interference can be represented in the form of cascades of resonance lines of different shapes, each of which is described by the classical Fano formula. The effect is observed in resonant light scattering by an arbitrary body of revolution and discussed in detail using the example of scattering by an infinite homogeneous dielectric cylinder.
Systematic study on nuclear resonant scattering
New resonant scattering effect of thermal neutron capture gamma rays from Ti and Fe on Sb, Cu, Se and Ce target were observed. These results together with those published by other authors are summarized and discussed in terms of a possible systematic search for new resonant scattering effects
Hamada, Sh; Burtebayev, N [Kazakh National University, Almaty (Kazakhstan); Gridnev, K A [St Petersburg University, St Petersburg (Russian Federation); Amangeldi, N, E-mail: Sh.m.hamada@gmail.com [Eurasia National University, Astana (Kazakhstan)
2011-10-15
The angular distribution for the elastic scattering of {sup 16}O, {sup 14}N and {sup 12}C on {sup 27}Al was measured at an energy of 1.75 MeV per nucleon in the DC-60 INP NNC (Institute of Nuclear Physics, National Nuclear Centre) cyclotron located in Astana in order to study the elastic scattering mechanism in these nuclear systems. The experimental results were analyzed with the help of the optical potential code SPI-GENOA. Good agreement between the experimental data and the theoretical calculations was obtained by using suitable optical potential parameters. The elastic scattering of {sup 16}O, {sup 14}N and {sup 12}C on {sup 27}Al does not reveal any unusual features or threshold anomaly at this energy.
The angular distribution for the elastic scattering of 16O, 14N and 12C on 27Al was measured at an energy of 1.75 MeV per nucleon in the DC-60 INP NNC (Institute of Nuclear Physics, National Nuclear Centre) cyclotron located in Astana in order to study the elastic scattering mechanism in these nuclear systems. The experimental results were analyzed with the help of the optical potential code SPI-GENOA. Good agreement between the experimental data and the theoretical calculations was obtained by using suitable optical potential parameters. The elastic scattering of 16O, 14N and 12C on 27Al does not reveal any unusual features or threshold anomaly at this energy.
Resonances in Positron-Mg Scattering
PENG Yue; CHENG Cheng; ZHOU Ya-Jun
2007-01-01
We present the results for resonances in positron-Mg scattering at low impact energy (0-5.0eV) by using the momentum space coupled-channel optical (CCO) method in momentum space. The S-partial wave resonance at 3.880eV, P-partial wave resonance at 4.020eV, and D-partial wave resonance at 4.267eV are found.
The Ohio University Beam Swinger provides a high resolution, low back-ground time-of-flight facility for the measurement of elastic and inelastic neutron scattering. It has been used to obtain a comprehensive set of differential scattering cross sections for 12C, 14N, 16O and 40Ca between 18 and 26 MeV. The elastic cross sections can be used directly to obtain partial kerma factors and, combined with the known total cross sections, provide accurate values for the reaction cross sections. Angular distributions have been measured for inelastic scattering from all the nuclear levels that cannot decay by particle emission thus providing (by subtraction) a limit on the sum of all charged-particle producing reactions. The integrated cross sections for inelastic scattering from some particle-unstable states in 12C are in excellent agreement with the cross sections for three-body breakup obtained by Antolkovic et al. The differential data have been used, together with higher energy proton scattering data to produce energy-dependent optical model parameters for each of these nuclei in the energy range 20-60 MeV. It has been found that the elastic differential cross sections at theta > 1000 for 12C, 14N and 16O cannot be well described by a spherical optical model. Explicit consideration of coupled-channel effects, and in the case of 12C, deformation of the ground state, improves the agreement between calculation and experiment. Heavy ion recoil kerma factors and reaction cross sections have been obtained for each element and compared with previous calculations and measurements
Resonant electron scattering by graphene antidot
Zagorodnev, I. V.; Devizorova, Zh. A.; Enaldiev, V. V.
2015-01-01
The edge states which were observed on a linear edge of graphene may also persist on a curved edge. We calculate the elastic transport scattering cross section on a graphene nanohole supporting the edge states. Resonant peaks in the gate voltage dependence of conductivity of graphene with such nanoholes are obtained. Position and height of the resonances are determined by the localization depth of the quasibound edge states, and width -- by their lifetime. The scattering amplitude near the re...
Wilson, David J. [Old Dominion University, Norfolk, VA
2014-06-23
We have obtained clear signals of resonances in coupled-channel pi K - eta K scattering. Using distillation and a large basis of operators we are able to extract a precise spectrum of energy levels using the variational method. These energies are analysed using inelastic extensions of the Luescher method to obtain scattering amplitudes that clearly describe S, P and D wave resonances, corresponding to the physical K_0^*(1430), the K^*(892) and the K_2^*(1430).
Medium modified effective two nucleon interactions are defined for protons incident upon 12C with energies in the range 200 to 800 MeV. Those effective interactions have been folded with the ground state density to specify nonlocal optical potentials that were then used to analyse the elastic scattering differential cross sections and analysing powers. A select set of isoscalar and isovector, positive and negative parity, inelastic proton scattering transitions have also been analysed using the same (microscopic) optical models to define the distorted wave functions needed in Distorted Wave Approximation calculations of the associated differential cross sections and analysing powers. All results are compared with ones found using the Love-Franey effective interactions. The nuclear structure relating to these transitions was chosen from (0+2) ℎω and (1+3)ℎω shell model calculations of the positive and negative parity spectra of 12C respectively. 21 refs., 12 figs
Resonances in Positron-He Scattering
XIAO Dan; JIANG Ping-Hui; ZHOU Ya-Jun
2007-01-01
We present the results for resonances in positron-He scattering at low impact energy (19.3-24.0eV) by using the momentum space coupled-channel optical (CCO) method. The S-partial wave resonance at 20.16eV is found for the first time.
Measurements of the neutron scattering cross sections for 12C, 16O, 40Ca and 56Fe at 14.2 MeV
Double different cross sections and energy-integrated differential ones for elastic and inelastic scattering from 12C, 16O, 40Ca, and 56Fe at 14.2 MeV have been measured at forward angles from 10O to 70O in 10O steps. The experimental data have been compared with the predictions of JENDL-3 as well as those of optical model and DWBA calculations. (author)
We investigated the in-medium effect by density-dependent axial and weak-vector form factors on muon-neutrino (νμ) and anti-muon-neutrino ( ν-bar μ) scattering in the quasi-elastic (QE) region from nucleons (N*) bound in a nucleus or immersed in a nuclear medium via neutral current (NC) and charged current (CC). For the density-dependent form factors, we exploited a quark–meson-coupling (QMC) model. We found that the νμ( ν-bar μ)−N∗ scattering cross sections via NC in the QE region usually decrease with an increased medium density, while those using CC were increased. However, their rate of change was sensitive to the four-momentum transfer given to a bound nucleon through scattering. We compared these results obtained by the elementary process corrected by the in-medium effect to the BNL and MiniBooNE data, which measured νμ scattering cross sections per nucleon through νμ – 12C scattering in 12C composite targets. The incident energy range was 550 ν12C, we exploited the QMC form factors evaluated at ρ=0.5ρo, where the normal density ρo∼0.15 fm−3. The strangeness contributions in NC scattering are also incorporated into the form factors for comparison with experimental data. Our numerical results show that most of the experimental data can be explained in a satisfactory manner by the density-dependent elementary process, but there are some remaining deviations resulting from the nuclear structure, particularly in the low and high momentum-transfer regions. (paper)
Multi-cluster problems: resonances, scattering and condensed states
This talk is mainly concerned with many-body resonances in nuclear physics. We extensively discuss the structure and reactions of multi-cluster systems using the complex scaling method (CSM). We expound three interesting problems in recent studies of multi-cluster systems. First, we discuss four- and five-body resonances in A=7 (7He, 7B) and A=8 (8He, 8C) systems, respectively. The observed states are well explained and many additional states are predicted. Second, the Coulomb breakup reactions of two-neutron halo nuclei and the α-d scattering are investigated using a three-body model with CSM. Finally, we discuss the α-condensate-like states and their symplectic excitation properties in three- and four-α models for 12C and 16O, respectively.
Hadron scattering and resonances in QCD
Dudek, Jozef J.
2016-05-01
I describe how hadron-hadron scattering amplitudes are related to the eigenstates of QCD in a finite cubic volume. The discrete spectrum of such eigenstates can be determined from correlation functions computed using lattice QCD, and the corresponding scattering amplitudes extracted. I review results from the Hadron Spectrum Collaboration who have used these finite volume methods to study ππ elastic scattering, including the ρ resonance, as well as coupled-channel π >K, ηK scattering. Ongoing calculations are advertised and the outlook for finite volume approaches is presented.
Hadron scattering and resonances in QCD
Dudek, Jozef J. [Old Dominion Univ., Norfolk, VA (United States)
2016-05-01
I describe how hadron-hadron scattering amplitudes are related to the eigenstates of QCD in a finite cubic volume. The discrete spectrum of such eigenstates can be determined from correlation functions computed using lattice QCD, and the corresponding scattering amplitudes extracted. I review results from the Hadron Spectrum Collaboration who have used these finite volume methods to study pi pi elastic scattering, including the rho resonance, as well as coupled-channel pi K, eta K scattering. Ongoing calculations are advertised and the outlook for finite volume approaches is presented.
A note on the use/determination of relative alpha scattering phases in the 12C(α,γ)16O reaction
A new experiment to determine the thermonuclear cross section of the 12C(α,γ)16O reaction has been performed in regular kinematics using an intense α-particle beam. In this experiment a 4π-detector setup has been used for the first time to measure all angles of each γ-angular distribution simultaneously. The 12C targets were isotopically enriched by magnetic separation during implantation. The depth profiles of the implanted carbon in the 12C targets have been determined by Rutherford backscattering for purposes of cross section normalization and absolute determination of the E1- and E2-S-factors. Angular distributions have been measured. From these distributions, astrophysical E1- and E2-S-factor functions vs. energy have been calculated, both of which are indispensable for modelling of this reaction and the extrapolation towards lower energies. The separation of the E1- and E2-S-capture channels has been done both by taking the phase value φ12 as a free parameter and by fixing it using the results of elastic α-particle scattering on 12C in the same energy range. The precision and accuracy of these new measurements make it possible to distinguish between the two methods of analysis. Preliminary values of S-factors extrapolated to 300 keV will be presented. (author)
Csedreki, L., E-mail: csedreki@atomki.mta.hu [Institute for Nuclear Research, Hungarian Academy of Sciences, MTA Atomki, H-4001 Debrecen, P.O. Box 51 (Hungary); Szíki, G.Á. [University of Debrecen, Faculty of Engineering, Department of Basic Technical Studies, H-4028 Debrecen, Ótemető u. 2-4 (Hungary); Szikszai, Z. [Institute for Nuclear Research, Hungarian Academy of Sciences, MTA Atomki, H-4001 Debrecen, P.O. Box 51 (Hungary); Kocsis, I. [University of Debrecen, Faculty of Engineering, Department of Basic Technical Studies, H-4028 Debrecen, Ótemető u. 2-4 (Hungary)
2015-01-01
The observed resonance parameters of the {sup 12}C(d,pγ){sup 13}C reaction in the vicinity of 1450 keV deuteron energy have been determined in a thorough procedure, fitting our recent experimental excitation curve, as well as earlier literature data with the Root Software Package. The resulting energy and width (FWHM) of resonance are 1445.8 ± 0.2 keV and 5.3 ± 0.4 keV, respectively. We propose the application of this resonance as a precise and simple method for accelerator energy calibration when performing DIGE analysis.
Bystritsky, V. M.; Grozdanov, D. N.; Zontikov, A. O.; Kopach, Yu. N.; Rogov, Yu. N.; Ruskov, I. N.; Sadovsky, A. B.; Skoy, V. R.; Barmakov, Yu. N.; Bogolyubov, E. P.; Ryzhkov, V. I.; Yurkov, D. I.
2016-07-01
The work is devoted to measuring the angular distribution of 4.43-MeV γ-rays produced in inelastic scattering of 14.1-MeV neutrons by 12C nuclei. A portable ING-27 neutron generator (designed and fabricated at VNIIA, Moscow) with a built-in 64-pixel silicon α-detector was used as a source of tagged neutrons. The γ-rays of characteristic nuclear radiation from 12C were detected with a spectrometric system that consisted of 22 γ-detectors based on NaI(Tl) crystals arranged around the carbon target. The measured angular distribution of 4.43-MeV γ-rays is analyzed and compared with the results of other published experimental works.
Elastic scattering for 16O + 12C at 140 MeV and 218 MeV
In this work, angular distribution of cross sections have been measured for 12C(16O,16O)12C at two energies. The measurements were carried out in 0.50 intervals between 50-19.50C (lab.) at 140 MeV, 4.50-14.50 at 218 MeV. An optical model analysis of these strong structure angular distributions was done. Good fits of the data were obtained using the optical model search code GENOA with a full Woods-Saxon potential form. This yielded parameters subject to considerable ambiguities as it is known to occur for strongly absorbed particles. These ambiguities were explored in detail and it was found that both the real and the imaginary parts present some characteristics that have been found before for the real potential (as Igo relation for continous ambiguities and the fact that potentials with different diffusivities tend to have the same value at the strong absorption radii). It was found, among other results, that the real volume integral, the mean square radius, as well as the total reaction cross section (σsub(r)) cannot be determined unambiguously. A strong correlation was found between σsub(r) and the imaginary diffusivity. A systematic study of how the variation of the potential parameters affects the angular distribution is presented and some features of the diffraction structure of the angular distribution are discussed. (author)
Inelastic scattering in resonant tunneling
Wingreen, Ned S.; Jacobsen, Karsten Wedel; Wilkins, John W.
1989-01-01
The exact resonant-tunneling transmission probability for an electron interacting with phonons is presented in the limit that the elastic coupling to the leads is independent of energy. The phonons produce transmission sidebands but do not affect the integrated transmission probability or the...
Resonance scattering spectroscopy of gold nanoparticle
JIANG; Zhiliang; FENG; Zhongwei; LI; Tingsheng; LI; Fang; ZHONG; Fuxin; XIE; Jiyun; YI; Xianghui
2001-01-01
The gold nanoparticles in diameter of 10-95 nm have been prepared by Frens procedure, all of which exhibit a resonance scattering peak at 580 nm. The mechanism of resonance scattering for gold nanoparticle has been considered according to the wave motion theory of nanoparticle in liquid. The principle of superamolecular interface energy band(SIEB) has been set up and utilized to explain the relationship between the diameter and colors for gold nanoparticle in liquid. A novel spectrophotometric ruler for the determination of the diameter has been proposed according to the relationship of the maximum absorption wavelength and diameter.
Scattering by coupled resonating elements in air
Krynkin, Anton; Chong, Alvin Y B; Taherzadeh, Shahram; Attenborough, Keith
2011-01-01
Scattering by (a) a single composite scatterer consisting of a concentric arrangement of an outer N-slit rigid cylinder and an inner cylinder which is either rigid or in the form of a thin elastic shell and (b) by a finite periodic array of these scatterers in air has been investigated analytically and through laboratory experiments. The composite scatterer forms a system of coupled resonators and gives rise to multiple low frequency resonances. The corresponding analytical model employs polar angle dependent boundary conditions on the surface of the N-slit cylinder. The solution inside the slits assumes plane waves. It is shown also that in the low-frequency range the N-slit rigid cylinder can be replaced by an equivalent fluid layer. Further approximations suggest a simple square root dependence of the resonant frequencies on the number of slits and this is confirmed by data. The observed resonant phenomena are associated with Helmholtz-like behaviour of the resonator for which the radius and width of the o...
A Survey of Beam Asymmetries in Semi-exclusive Electron Scattering on {sup 4}He and {sup 12}C
Dan Protopopescu
2002-12-01
A study of the polarized electron beam asymmetry in semi-exclusive (e,e{prime}p) reactions on {sup 4}He and {sup 12}C over a large kinematic range has been performed. The beam asymmetry A{prime}{sub LT} is related to the imaginary part of the longitudinal-transverse interference and therefore it vanishes in reactions proceeding through a channel with a single dominant mechanism. In quasifree nucleon knockout, the helicity asymmetry provides an unambiguous signature for the interference between direct knockout and rescattering amplitudes. The data were taken in April-May 1999 using polarized beams of energies between 2.2 and 4.4 GeV, with the CEBAF Large Acceptance Spectrometer (CLAS) detector located in Hall B at the Jefferson Laboratory, VA. The measured asymmetries compare well with the theoretical predictions.
Controlling electromagnetic scattering with wire metamaterial resonators
Filonov, Dmitry S; Iorsh, Ivan; Belov, Pavel A; Ginzburg, Pavel
2016-01-01
Manipulation of radiation is required for enabling a span of electromagnetic applications. Since properties of antennas and scatterers are very sensitive to a surrounding environment, macroscopic artificially created materials are good candidates for shaping their characteristics. In particular, metamaterials enable controlling both dispersion and density of electromagnetic states, available for scattering from an object. As the result, properly designed electromagnetic environment could govern waves' phenomena. Here electromagnetic properties of scattering dipoles, situated inside a wire medium (metamaterial) are analyzed both numerically and experimentally. Impact of the metamaterial geometry, dipole arrangement inside the medium, and frequency of the incident radiation on scattering phenomena was studied. It was shown that the resonance of the dipole hybridizes with Fabry-Perot modes of the metamaterial, giving rise to a complete reshaping of electromagnetic properties. Regimes of controlled scattering sup...
Resonance strengths in the 14N(p,gamma)15O and 15N(p,alpha gamma)12C reactions
Marta, Michele; Bemmerer, Daniel; Beyer, Roland; Broggini, Carlo; Caciolli, Antonio; Erhard, Martin; Fülöp, Zsolt; Grosse, Eckart; Gyürky, György; Hannaske, Roland; Junghans, Arnd R; Menegazzo, Roberto; Nair, Chithra; Schwengner, Ronald; Szücs, Tamás; Vezzú, Simone; Wagner, Andreas; Yakorev, Dmitry
2010-01-01
The 14N(p,gamma)15O reaction is the slowest reaction of the carbon-nitrogen-oxygen cycle of hydrogen burning in stars. As a consequence, it determines the rate of the cycle. The 15N(p,alpha gamma)12C reaction is frequently used in inverse kinematics for hydrogen depth profiling in materials. The 14N(p,gamma)15O and 15N(p,alpha gamma)12C reactions have been studied simultaneously, using titanium nitride targets of natural isotopic composition and a proton beam. The strengths of the resonances at Ep = 1058 keV in 14N(p,gamma)15O and at Ep = 897 and 430 keV in 15N(p,alpha gamma)12C have been determined with improved precision, relative to the well-known resonance at Ep = 278 keV in 14N(p,gamma)15O. The new recommended values are \\omega\\gamma = 0.352$\\pm$0.018, 362$\\pm$20, and 22.0$\\pm$0.9\\,eV for their respective strengths. In addition, the branching ratios for the decay of the Ep = 1058 keV resonance in 14N(p,gamma)15O have been redetermined. The data reported here should facilitate future studies of off-resona...
Murata, Toru [AITEL Corp., Tokyo (Japan)
1998-03-01
The {sup 12}C({alpha},n){sup 15}O reaction and the {sup 13}C({alpha},n){sup 16}O reaction were analyzed with a resonance formula in the incident {alpha}-particle energy range of 1.0 to 16.0 MeV. With the obtained resonance parameters, branching ratios of the emitted neutrons to the several levels of the residual nucleus and their angular distributions were calculated to obtain the energy spectrum of emitted neutrons. Thick target neutron yield of carbon were also calculated and compared with the experimental data. (author)
Resonant elastic scattering, inelastic scattering and astrophysical reactions
Nuclear reactions can occur at low kinetic energy. Low-energy reactions are characterized by a strong dependence on the structure of the compound nucleus. It turns out that it is possible to study the nuclear structure by measuring these reactions. In this course, three types of reactions are treated: Resonant Elastic Scattering (such as N14(p,p)N14), Inelastic Scattering (such as N14(p,p')N14*) and Astrophysical reactions (such as N14(p,γ)O15). (author)
Resonances in the proton-6Li scattering
The differential cross section and the analyzing power of the p+6Li scattering were measured in the laboratory energy range from 1.6 respectively 2.8 MeV to 10 MeV at 45 respectively 40 energies in full angular distributions. The data were subjected both to an analysis in the optical model which yielded already hints to resonance effects and to a comphrehensive scattering-phase analysis for L=0, 1, and 2 under inclusion of channel spin and orbital angular momentum mixings. The consistent description of all data required the assumption of broad resonance structures. An approximate parametrization by a Breit-Wigner formula allowed the estimation of the resonance parameters. (orig./HSI)
Mean-field study of $^{12}$C+$^{12}$C fusion
Chien, Le Hoang; Khoa, Dao T
2016-01-01
The nuclear mean-field potential arising from the $^{12}$C+$^{12}$C interaction at the low energies relevant for the astrophysical carbon burning process has been constructed within the double-folding model, using the realistic nuclear ground-state density of the $^{12}$C nucleus and the effective M3Y nucleon-nucleon (NN) interaction constructed from the G-matrix of the Paris (free) NN potential. To explore the nuclear medium effect, both the original density independent M3Y-Paris interaction and its density dependent CDM3Y6 version have been used in the folding model calculation of the $^{12}$C+$^{12}$C potential. The folded potentials at the different energies were used in the optical model description of the elastic $^{12}$C+$^{12}$C scattering at the energies around and below the Coulomb barrier, as well as in the barrier penetration model to estimate the fusion cross section and astrophysical $S$ factor of the $^{12}$C+$^{12}$C reactions at the low energies. The obtained results are in good agreement wit...
Nondestructive assay using nuclear resonance fluorescence scattering
Nondestructive assay using Nuclear resonance fluorescence (NRF) with a laser Compton scattering (LCS) gamma-ray beam is considered to be useful method to measure Pu-239 inside of a spent nuclear fuel and a melted fuel. We have proposed some detection methods coupled with NRF. One of them is the measuring the scattering gamma-ray from the target. In this method, the various background increases the statistical error of the measured quantity of Pu-239. We discuss the statistical precise with a function of the energy of the incident LCS gamma-ray. (author)
Resonance scattering in quantum wells with nanocenters
Satanin, A M
2002-01-01
The study on the Fano resonances is carried out in the 2D systems and their contribution to the residual resistance is calculated. The quantum well, the states whereof interfere with the nanocenters, for example, with the delta-layer donor states or with the quantum points states, is considered as a model. It is shown, that the states, localized on the state centers, lead to the appearance of additional asymmetric peaks in the resistance dependence on the Fermi energy. It is also shown, that the finite radius nanocenters in the 2D electron layers may lead to origination of the Fano resonances in the scattering cross section
Resonances in photon-photon scattering
A quantity called stickiness is introduced which should be largest for J not equal to 0 glueballs and can be measured in two photon scattering and radiative J/psi decay. An argument is reviewed suggesting that light J = 0 glueballs may have large couplings to two photons. The analysis of radiative decays of eta and eta' is reviewed and a plea made to desist from false claims that they are related to GAMMA(π0 → γγ) by SU(3) symmetry. It is shown that two photon studies can refute the difficult-to-refute hypothesis that xi(2220) or zeta(8320) are Higgs bosons. A gallery of rogue resonances and resonance candidates is presented which would usefully be studied in γγ scattering, including especially the low mass dipion. 34 references
The nuclear burning process proceeds from the conservation of the most abundant element hydrogen to helium, then from helium to carbon and oxygen, and then from these to heavier elements. Some of the key reactions for the carbon and oxygen burning stages of the nucleosynthesis are 12C+12C and 16O+16O leading to all possible final states. This paper contains the experimental measurements of 12C+12C and 16O+16O angular distributions performed at the cyclotron DC-60 in Astana, Kazakhstan. The extracted beam of 16O and 12C was accelerated up to two energies 1.75 and 1.5 MeV/n and then directed to an Al2O3 target of thickness 20 μg/cm2 and a carbon self-supporting target of thickness 17.4 μg/cm2. The angular distribution calculations were performed using both the phenomenological optical potential (SPI-GENOA) code and the double folding potential (FRESCO) code.
Fano resonances in scattering: an alternative perspective
The characteristic features of Fano resonances (also called Feshbach resonances in nuclear physics) are asymmetric line shapes, caused by the interaction between a discrete state and a continuum of states. In a previous paper it has been shown that the interference of the first and second order pole of the Green's function at an exceptional point, as well as the interference of the first order poles in the vicinity of the exceptional point, gives rise to asymmetric scattering cross section profiles. In the present paper we demonstrate that these line profiles are indeed well described by the Beutler-Fano formula, and thus are genuine Fano resonances. Also further away from the exceptional points excellent agreement can be found by introducing energy dependent Fano parameters
Elastic and inelastic scattering studies for the systems 12C+28Si and 16O+/sup 28,29,30/Si
Elastic and inelastic excitation functions for the systems 12C+ 28Si and 16O+/sup 28,29,30/Si have been measured at theta/sub c.m./ = 1800 from the Coulomb barrier up to E/sub c.m./ = 45 MeV (12C+28Si), E/sub c.m./ = 52 MeV (16O+28Si), and E/sub c.m./ = 32 MeV (16O+/sup 29,30/Si). Over the whole energy range they all exhibit pronounced and regular broad oscillations (0.50 were taken at five of the maxima and near a minimum of the excitation function for the system 16O+28Si. All angular distributions are oscillatory and exhibit a strong backward rise. The data are discussed in terms of a coherent superposition of a background and a resonant amplitude and in terms of the interference between the internal and barrier wave reflected by a deep optical potential
Cook, J.; Clarice, N. M.; Coopersmith, J.; Griffiths, R. J.
1982-09-01
Coupled channels calculations have been made for the scattering of 7Li from 12C at 63 and 79 MeV and from 24,26Mg at 88 MeV. The calculations describe, simultaneously, the elastic scattering, excitation of 7Li to the 478 keV {1}/{2}- state, excitation of the target to its first 2 + state, and the mutual excitation of both projectile and target to their {1}/{2}- and 2 + states respectively. The potentials have been calculated by a double folding model using the M3Y effective interaction for the real part, and a gaussian effective interaction for the imaginary part. Realistic densities have been used for the ground states of 7Li, 12C and 24, 26Mg and also the transition densities to the excited states using a microscopic plus macroscopic prescription. For the mutual excitation, both one-step processes with l = 0, 2 and 4 and two-step processes were included. The calculations show that the two-step processes are the dominant contribution to the mutual excitation, but at forward angles, the oscillations in the data are only reproduced with the coherent addition of the one-step processes, which are dominated by the l = 4 contribution. Even when coupling to all single and mutual excitations are included the real potential still requires a normalization of about 0.6. The addition of the quadrupole re-orientation matrix element for the ground state does not significantly change this value. These calculations confirm that the coupling to the first excited inelastic levels of target and ejectile is not the source of the anomalous M3Y normalization, and that the dominant mode for mutual excitation is a two-step process. However, direct one-step mutual excitation is important for small angles (θ ≲ 20°).
Interference scattering effects on intermediate resonance absorption at operating temperatures
Resonance integrals may be accurately calculated using the intermediate resonance (IR) approximation. Results are summarized for the case of an absorber with given potential scattering cross sections and interference scattering parameter admixed with a non absorbing moderator of given cross section and located in a narrow resonance moderating medium. From the form of the IR solutions, it is possible to make some general observations about effects of interference scattering on resonance absorption. 2 figures
The charge-symmetric scattering systems, 12C+13N and 12C+13C have been investigated by using the orthogonalized coupled-reaction-channel (OCRC) method with the basis functions of the elastic, inelastic and transfer channels defined by the single-particle states, 1p1/2, 2s1/2, 1d5/2 and 1d3/2 of the valence nucleon in 13N or 13C. The data of the elastic scattering of 13N on 12C measured by Lienard et al. have been explained consistently with the data of the elastic and inelastic scattering of the 12C+13C system. The CRC effects both on the above systems are very strong, although those on the 12C+13N system are fairly weaker than the 12C+13C system. The role of the highly excited single-particle states 1d3/2 is particularly important in the formation of a specific CRC scheme, i.e., the formation of the covalent molecules due to the hybridization caused by the mixing of the different parity single-particle states. The fusion cross sections of the 12C+13C system at energies below the Coulomb barrier are strongly enhanced as a result of the strong CRC effects as compared with those of the 12C+12C system, while in 12C+13N system the enhancement of the sub-barrier fusion has not been observed. The above absorption mechanism for the 12C+13C system explains the lack of the molecular-resonance phenomena observed in the 12C+12C system. We check the effects of the dipole (E1) transition of the valence nucleon in 13N (and also in 13C) due to the core-core Coulomb interaction in the scattering at sub-barrier energies. The effects are not appreciable. (author)
Resonant electromagnetic scattering in anisotropic layered media
The resonant excitation of an electromagnetic guided mode of a slab structure by exterior radiation results in anomalous scattering behavior, including sharp energy-transmission anomalies and field amplification around the frequency of the slab mode. In the case of a periodically layered ambient medium, anisotropy serves to couple the slab mode to radiation. Exact expressions for scattering phenomena are proved by analyzing a pole of the full scattering matrix as it moves off the real frequency axis into the lower half complex plane under a detuning of the wavevector parallel to the slab. The real pole is the frequency of a perfect (infinite Q) guided mode, which becomes lossy as the frequency gains an imaginary part. This work extends results of Shipman and Venakides to evanescent source fields and two-dimensional parallel wavevector and demonstrates by example how the latter allows one to control independently the width and central frequency of a resonance by varying the angle of incidence of the source field. The analysis relies on two nondegeneracy conditions of the complex dispersion relation for slab modes (relating poles of the scattering matrix to wavevector), which were assumed in previous works and are proved in this work for layered media. One of them asserts that the dispersion relation near the wavevector κ and frequency ω of a perfect guided mode is the zero set of a simple eigenvalue ℓ(κ, ω), and the other relates ∂ℓ/∂ω to the total energy of the mode, thereby implying that this derivative is nonzero
Resonant Raman scattering off neutral quantum dots
Resonant inelastic (Raman) light scattering off neutral GaAs quantum dots which contain a mean number, N=42, of electron-hole pairs is computed. We find Raman amplitudes corresponding to strongly collective final states (charge-density excitations) of similar magnitude as the amplitudes related to weakly collective or single-particle excitations. As a function of the incident laser frequency or the magnetic field, they are rapidly varying amplitudes. It is argued that strong Raman peaks should come out in the spin-density channels, not related to valence-band mixing effects in the intermediate states. (author)
Fano resonances in scattering: an alternative perspective
Schwarz, Lukas; Cartarius, Holger; Wunner, Günter; Heiss, Walter Dieter; Main, Jörg
2015-08-01
In a previous paper it has been shown that the interference of the first and second order pole of the Green's function at an exceptional point, as well as the interference of the first order poles in the vicinity of the exceptional point, gives rise to asymmetric scattering cross section profiles. In the present paper we demonstrate that these line profiles are indeed well described by the Beutler-Fano formula, and thus are genuine Fano resonances. Also further away from the exceptional points excellent agreement can be found by introducing energy dependent Fano parameters.
Fano resonances in scattering: an alternative perspective
Schwarz, Lukas; Wunner, Günter; Heiss, Walter Dieter; Main, Jörg
2015-01-01
In a previous paper it has been shown that the interference of the first and second order pole of the Green's function at an exceptional point, as well as the interference of the first order poles in the vicinity of the exceptional point, gives rise to asymmetric scattering cross section profiles. In the present paper we demonstrate that these line profiles are indeed well described by the Beutler-Fano formula, and thus are genuine Fano resonances. Also further away from the exceptional points excellent agreement can be found by introducing energy dependent Fano parameters.
Resonances, scattering theory and rigged Hilbert spaces
The problem of decaying states and resonances is examined within the framework of scattering theory in a rigged Hilbert space formalism. The stationary free, in, and out eigenvectors of formal scattering theory, which have a rigorous setting in rigged Hilbert space, are considered to be analytic functions of the energy eigenvalue. The value of these analytic functions at any point of regularity, real or complex, is an eigenvector with eigenvalue equal to the position of the point. The poles of the eigenvector families give origin to other eigenvectors of the Hamiltonian; the singularities of the out eigenvector family are the same as those of the continued S matrix, so that resonances are seen as eigenvectors of the Hamiltonian with eigenvalue equal to their location in the complex energy plane. Cauchy theorem then provides for expansions in terms of complete sets of eigenvectors with complex eigenvalues of the Hamiltonian. Applying such expansions to the survival amplitude of a decaying state, one finds that resonances give discrete contributions with purely exponential time behavior; the background is of course present, but explicitly separated. The resolvent of the Hamiltonian, restricted to the nuclear space appearing in the rigged Hilbert space, can be continued across the absolutely continuous spectrum; the singularities of the continuation are the same as those of the out eigenvectors. The free, in and out eigenvectors with complex eigenvalues and those corresponding to resonances can be approximated by physical vectors in the Hilbert space, as plane waves can. The need for having some further physical information in addition to the specification of the total Hamiltonian is apparent in the proposed framework. The formalism is applied to the Lee-Friedrichs model. 48 references
The determination of polarization transfer observable for (rvec p, rvec p') reactions in intermediate energies provides a rich source of information on both the effective nucleon-nucleus interaction and the nuclear structure. The primary motivation for this work was to exploit the increased sensitivity predicted for these polarization transfer observable to the spin-dependent terms of the effective interaction used to describe nucleon-nucleus scattering at intermediate energies. To carry out this work the author has designed, built, and calibrated a polarimeter for the focal plane of the high resolution K600 Spectrometer. By using a low-energy beamline polarimeter and this Focal Plane Polarimeter, he has measured the normal-component spin observables DNN', P, and Ay at 200 MeV for the 1+, T = 0 (12.71 MeV) and T = 1 (15.11 MeV) states in 12C and for the 4-, T = 0 (17.79 and 19.80 MeV) and T = 1 (18.98 MeV) states in 16O. Measurements were made at five angles for the 12C transitions, at momentum transfers between 80 and 250 MeV/c, and at three angles for 16O, at momentum transfers of 225 to 400 MeV/c. The transitions chosen for this work have fairly well-determined nuclear structure and unnatural parity which maximizes the predicted sensitivity to the spin-dependent terms of the effective interaction. The results from this work will be used to address questions concerning the need for a relativistic interaction and how to incorporate corrections to the nuclear interaction due to the nuclear medium
Resonances and off-specular scattering in neutron waveguides
Off-specular neutron scattering from layered resonant systems has been studied. As an example, tri-layer neutron waveguides have been investigated experimentally by neutron reflectometry. In such systems, the neutron wave function is strongly localized in the guiding layer. The resonant states in the total reflection region lead to enhanced off-specular scattering from the interface roughness. The relation between the resonant states and off-specular scattering is discussed. (authors)
Resonances and off-specular scattering in neutron waveguides
Kozhevnikov, S.V. [Franck Lab. of Neutron Physics, JINR, Moscow (Russian Federation); Kozhevnikov, S.V.; Ott, F. [CEA Saclay, IRAMIS, CNRS, Lab. Leon Brillouin, 91 - Gif-sur-Yvette (France); Paul, A. [Institut fur Festkorperforschung, Forschungszentrum Julich (Germany); Rosta, L. [Research Institute for Solid State Physics and Optics, Budapest (Hungary)
2009-02-15
Off-specular neutron scattering from layered resonant systems has been studied. As an example, tri-layer neutron waveguides have been investigated experimentally by neutron reflectometry. In such systems, the neutron wave function is strongly localized in the guiding layer. The resonant states in the total reflection region lead to enhanced off-specular scattering from the interface roughness. The relation between the resonant states and off-specular scattering is discussed. (authors)
The Use of the Scattering Phase Shift in Resonance Physics
Nowakowski, M
2004-01-01
The scattering phase shift encodes a good amount of physical information which can be used to study resonances from scattering data. Among others, it can be used to calculate the continuum density of states and the collision time in a resonant process. Whereas the first information can be employed to examine the evolution of unstable states directly from scattering data, the second one serves as a tool to detect resonances and their properties. We demonstrate both methods concentrating in the latter case on 'exotic' resonances in pi-pi and pi-K scattering.
Observation of resonant lattice modes by inelastic neutron scattering
Bjerrum Møller, Hans; Mackintosh, A.R.
1965-01-01
Observation by inelastic neutron scattering of resonant lattice modes due to small concentration of W atoms in Cr host crystal; frequencies and lifetimes of phonons with frequencies near that of resonant mode are considerably affected by presence of defects.......Observation by inelastic neutron scattering of resonant lattice modes due to small concentration of W atoms in Cr host crystal; frequencies and lifetimes of phonons with frequencies near that of resonant mode are considerably affected by presence of defects....
X-ray resonant magnetic scattering ellipsometer
It is very difficult to characterize the polarization of a synchrotron radiation source in the soft and/or intermediate x-ray energy region particularly from 1 to 2 keV. Conventional multilayer mirror or single-crystal polarimeters do not work over this energy region because their throughput (the reflectivities combined with the phase shift) becomes insignificant. In this paper, we present a new ellipsometer scheme that is able to fully characterize the polarization of synchrotron radiation sources in this energy region. It is based on the dichroic x-ray resonant ferromagnetic scattering that yields information on both the polarization of the x-ray and the material (element specific) dielectric-constant tensor [C.-C. Kao et al., Phys. Rev. B 50, 9599 (1994)] due to the interband ferromagnetic Kerr effect [B.R. Cooper, Phys. Rev. A 139, 1504 (1965)]. copyright 1996 American Institute of Physics
Scattering and Resonances in QCD_2
Frishman, Yitzhak; Frishman, Yitzhak; Karliner, Marek
2002-01-01
Extending previous works on the spectrum of QCD_2, we now investigate the 2D analogue of meson-baryon scattering. We use semi-classical methods, perturbing around classical soliton solutions. We start with the abelian case, corresponding to QED_2 and find that in this case the effective potential is reflectionless. We obtain an explicit expression for the forward phase shift. In the non-abelian case of QCD_2, the method yields a potential which depends on the momentum of the incoming particle. In this case there is both transmission and reflection. In both cases no resonances appear. As a byproduct, we derive the general conditions for a 2D quantum field theoretical action to yield a reflectionless effective potential when one expands in small fluctuations about the classical solution.
Physics of Cyclotron Resonance Scattering Features
Sschoenherr, Gabriele; Schwarm, Fritz-Walter; Falkner, Sebastian; Dauser, Thomas; Pottschmidt, Katja; Kretschmar, Peter; Klochkov, Dmitry; Ferrigno, Carlo; Britton Hemphill, Paul; Wilms, Joern
2016-04-01
Cyclotron resonant scattering features (short: cyclotron lines) are sensitive tracers of the physics of the accretion columns and mounds of X-ray pulsars. They form by interaction of X-ray photons with magnetically quantized electrons in the accreted plasma close to the neutron star. Such lines have been observed as absorption-like features for about 20 X-ray pulsars. Their energies provide a direct measure of the magnetic field strength in the line-forming region. By detailed modelling of the lines and of their parameter dependencies we can further decipher the physical conditions in the accretion column. For instance the fact that the complex scattering cross sections have a strong angle-dependence relates the phase-resolved cyclotron line shapes to parameters that constrain the systems’ still poorly understood geometry. Modelling the physics of cyclotron lines to a degree that allows for detailed and solid comparison to data therefore provides a unique access also to a better understanding of the overall picture of magnetically accreting neutron star systems.
Fano resonance scattering in waveguide with an impedance boundary condition
Xiong, Lei; Aurégan, Yves
2015-01-01
Sound propagation in a waveguide lined with one section of locally reactive material is studied by resonance scattering approach. The objective is to understand the effects of mode coupling in the lined section on the transmission. It is shown that a transmission zero is present in the vicinity of a resonance peak when a numerically real resonance frequency of the open lined section (opened to infinities through the rigid parts of the waveguide) is crossed. The transmission zero and immediate resonance peak form a Fano resonance, it has been explained as an interaction between a resonance and the non-resonant background. The real resonance frequency and its corresponding trapped mode are formed by the interferences (couplings) between two neighbor modes with complex resonance frequencies. It is also linked to the avoided crossing of eigenvalues and the exceptional point. The scattering matrix is expressed in terms of a matrix $\\mathsf{H_{eff}}$ which describes approximately the complex resonances in the open ...
Mie scattering as a cascade of Fano resonances.
Rybin, Mikhail V; Samusev, Kirill B; Sinev, Ivan S; Semouchkin, George; Semouchkina, Elena; Kivshar, Yuri S; Limonov, Mikhail F
2013-12-01
We reveal that the resonant Mie scattering by high-index dielectric nanoparticles can be presented through cascades of Fano resonances. We employ the exact solution of Maxwell's equations and demonstrate that the Lorenz-Mie coefficients of the Mie problem can be expressed generically as infinite series of Fano functions as they describe interference between the background radiation originated from an incident wave and narrow-spectrum Mie scattering modes that lead to Fano resonances. PMID:24514559
Scatter-based magnetic resonance elastography
Elasticity is a sensitive measure of the microstructural constitution of soft biological tissues and increasingly used in diagnostic imaging. Magnetic resonance elastography (MRE) uniquely allows in vivo measurement of the shear elasticity of brain tissue. However, the spatial resolution of MRE is inherently limited as the transformation of shear wave patterns into elasticity maps requires the solution of inverse problems. Therefore, an MRE method is introduced that avoids inversion and instead exploits shear wave scattering at elastic interfaces between anatomical regions of different shear compliance. This compliance-weighted imaging (CWI) method can be used to evaluate the mechanical consistency of cerebral lesions or to measure relative stiffness differences between anatomical subregions of the brain. It is demonstrated that CWI-MRE is sensitive enough to reveal significant elasticity variations within inner brain parenchyma: the caudate nucleus (head) was stiffer than the lentiform nucleus and the thalamus by factors of 1.3 ± 0.1 and 1.7 ± 0.2, respectively (P < 0.001). CWI-MRE provides a unique method for characterizing brain tissue by identifying local stiffness variations.
Impact of polydispersity on multipolar resonant scattering in emulsions.
Mascaro, Benoit; Brunet, Thomas; Poncelet, Olivier; Aristégui, Christophe; Raffy, Simon; Mondain-Monval, Olivier; Leng, Jacques
2013-04-01
The influence of size polydispersity on the resonant acoustic properties of dilute emulsions, made of fluorinated-oil droplets, is quantitatively investigated. Ultrasound attenuation and dispersion measurements on various samples with controlled size polydispersities, ranging from 1% to 13%, are found to be in excellent agreement with predictions based on the independent scattering approximation. By relating the particle-size distribution of the synthesized emulsions to the quality factor of the predicted multipolar resonances, the number of observable acoustic resonances is shown to be imposed by the sample polydispersity. These results are briefly discussed into the context of metamaterials for which scattering resonances are central to their effective properties. PMID:23556570
Low Frequency Scattering Resonance Wave in Strong Heterogeneity
Liu, Yinbin
2015-01-01
Multiple scattering of wave in strong heterogeneity can cause resonance-like wave phenomenon where signal exhibits low frequency, high intensity, and slowly propagating velocity. For example, long period event in volcanic seismology and surface plasmon wave and quantum Hall effect in wave-particle interactions. Collective behaviour in a many-body system is usually thought to be the source for generating the anomaly. However, the detail physical mechanism is not fully understood. Here I show by wave field modeling for microscopic bubble cloud model and 1D heterogeneity that the anomaly is related to low frequency scattering resonance happened in transient regime. This low frequency resonance is a kind of wave coherent scattering enhancement phenomenon in strongly-scattered small-scale heterogeneity. Its resonance frequency is inversely proportional to heterogeneous scale and contrast and will further shift toward lower frequency with random heterogeneous scale and velocity fluctuations. Low frequency scatterin...
Improved Fokker-Planck Equation for Resonance Line Scattering
Rybicki, G B
2006-01-01
A new Fokker-Planck equation is developed for treating resonance line scattering, especially relevant to the treatment of Lyman alpha in the early universe. It is a "corrected" form of the equation of Rybicki & Dell'Antonio that now obeys detailed balance, so that the approach to thermal equilibrium is properly described. The new equation takes into account the energy changes due to scattering off moving particles, the recoil term of Basko, and stimulated scattering. One result is a surprising unification of the equation for resonance line scattering and the Kompaneets equation. An improved energy exchange formula due to resonance line scattering is derived. This formula is compared to previous formulas of Madau, Meikson, & Rees (1997) and Chen & Miralda-Escud\\'e (2004).
Strong WW scattering chiral lagrangians, unitarity and resonances
Pelaez, J.R.
1996-08-01
Chiral lagrangians provide a model independent description of the strongly interacting symmetry breaking sector. In this work, first we review the LHC sensitivity to the chiral parameters (in the hardest case of non-resonant low-energy WW scattering). Later we show how to reproduce or predict the resonance spectrum by means of dispersion theory and the inverse amplitude method. We present a parameter space scan that covers many different strong WW scattering scenarios.
Correlation signals in resonance fluorescence : interpretation via photon scattering amplitudes
Dalibard, J.; Reynaud, S.
1983-01-01
Resonance fluorescence is treated as a collision process where incident laser photons are scattered by an atom. Correlation signals are extracted from an expansion to the second order of the post collision field state. Photon antibunching effect appears as a quantum interference between all the possible scattering amplitudes. When Rayleigh photons are rejected, some amplitudes vanish, leading to a bunching behaviour.
Resonance scattering characteristics of double-layer spherical particles
Xuejin Dong; Mingxu Su; Xiaoshu Cai
2012-01-01
Based on the principle of ultrasonic resonance scattering,sound-scattering characteristics of double-layer spherical particles in water were numerically studied in this paper.By solving the equations of the scattering matrix,the scattering coefficient determined by the boundary conditions can be obtained,thus the expression for the sound-scattering function of a single double-layer spherical particle can be derived.To describe the resonance scattering characteristics of a single particle,the reduced scattering cross section and reduced extinction cross section curves were found through numerical calculation.Similarly,the numerically calculated sound attenuation coefficient curves were used to depict the resonance scattering characteristics of monodisperse and polydisperse particles.The results of numerical calculation showed that,for monodisperse particles,the strength of the resonance was mainly related to the particle size and the total number of particles; while for polydisperse particles,it was primarily affected by the particle size,the coverage of the particle size distribution and the particle concentration.
Photoproduction of pions in 12C nuclei
A preliminary analysis was carried out of relativistic effects in coherent and incoherent pion production for the reaction 12C(γ, π0)12C by considering all the diagrams that contribute to the scattering amplitude. For the coherent pion the contribution to the scattering cross section mainly comes from the direct and exchange diagrams of γN → Δ → Nπ0, where N is a nucleon. The results were compared with the nonrelativistic calculations done in 12C nuclei assuming the nuclear effects and the final state interactions to be the same
Nuclear resonant scattering of capture gamma rays on Sb
Monochromatic photons obtained from thermal neutron capture in titanium were used for exciting nuclear levels in antimony. Angular distribution of the elastic scattered radiation was carried-out for the determination of the spins of the resonance levels. Total and ground state radiation widths of resonance levels were measured using self absorption and temperature variation measurements
Resonant Raman scattering of x rays: Evidence for K-M scattering
Resonant Raman x-ray scattering on molybdenum was studied using a Mo-anode x-ray tube and a LiF crystal monochromator. Beside the usual resonant Raman peak corresponding to the fluorescent Kα lines, another peak with a smaller energy loss was found. It is attributed to resonant Raman scattering with a final-state M-shell vacancy corresponding to the fluorescent Kβ lines. Both contributions are shown to be independent of the scattering angle. Absolute cross sections have been determined and compared with theoretical predictions
Resonant Raman scattering of x rays: evidence for K--M scattering
Resonant Raman x-ray scattering on molybdenum was studied using a Mo-anode x-ray tube and a LiF crystal monochromator. Beside the usual resonant Raman peak corresponding to the fluorescent Kα lines another peak with a smaller energy loss was found. It is attributed to resonant Raman scattering with a final state M-shell vacancy corresponding to the fluorescent Kβ lines. Both contributions are shown to be independent of the scattering angle. Absolute cross sections were determined and compared with theoretical predictions. 9 references
Guddala, Sriram; Ramakrishna, S Anantha
2016-01-01
A tri-layer metamaterial perfect absorber of light, consisting of (Al/ZnS/Al) films with the top aluminium layer patterned as an array of circular disk nanoantennas, is investigated for resonantly enhancing Raman scattering from C-60 fullerene molecules deposited on the metamaterial. The metamaterial is designed to have resonant bands due to plasmonic and electromagnetic resonances at the Raman pump frequency (725 nm) as well as Stokes emission bands. The Raman scattering from C60 on the metamaterial with resonantly matched bands is measured to be enhanced by an order of magnitude more than from C60 on metamaterials with off-resonant absorption bands peaked at 1090 nm. The Raman pump is significantly enhanced due to the resonance with a propagating surface plasmon band, while the highly impedance matched electromagnetic resonance is expected to couple out the Raman emission efficiently. The nature and hybridization of the plasmonic and electromagnetic resonances to form compound resonances are investigated by...
Tailoring dielectric resonator geometries for directional scattering and Huygens' metasurfaces
Campione, Salvatore; Basilio, Lorena I.; Warne, Larry K.; Sinclair, Michael B.
2015-02-01
In this paper we describe a methodology for tailoring the design of metamaterial dielectric resonators, which represent a promising path toward low-loss metamaterials at optical frequencies. We first describe a procedure to decompose the far field scattered by subwavelength resonators in terms of multipolar field components, providing explicit expressions for the multipolar far fields. We apply this formulation to confirm that an isolated high-permittivity cube resonator possesses frequency separated electric and magnetic dipole resonances, as well as a magnetic quadrupole resonance in close proximity to the electric dipole resonance. We then introduce multiple dielectric gaps to the resonator geometry in a manner suggested by perturbation theory, and demonstrate the ability to overlap the electric and magnetic dipole resonances, thereby enabling directional scattering by satisfying the first Kerker condition. We further demonstrate the ability to push the quadrupole resonance away from the degenerate dipole resonances to achieve local behavior. These properties are confirmed through the multipolar expansion and show that the use of geometries suggested by perturbation theory is a viable route to achieve purely dipole resonances for metamaterial applications such as wave-front manipulation with Huygens' metasurfaces. Our results are fully scalable across any frequency bands where high-permittivity dielectric materials are available, including microwave, THz, and infrared frequencies.
Optical Torque from Enhanced Scattering by Multipolar Plasmonic Resonance
Lee, Yoonkyung E; Jin, Dafei; Fang, Nicholas
2014-01-01
We present a theoretical study of the optical angular momentum transfer from a circularly polarized plane wave to thin metal nanoparticles of different rotational symmetries. While absorption has been regarded as the predominant mechanism of torque generation on the nanoscale, we demonstrate numerically how the contribution from scattering can be enhanced by using multipolar plasmon resonance. The multipolar modes in non-circular particles can convert the angular momentum carried by the scattered field, thereby producing scattering-dominant optical torque, while a circularly symmetric particle cannot. Our results show that the optical torque induced by resonant scattering can contribute to 80% of the total optical torque in gold particles. This scattering-dominant torque generation is extremely mode-specific, and deserves to be distinguished from the absorption-dominant mechanism. Our findings might have applications in optical manipulation on the nanoscale as well as new designs in plasmonics and metamateria...
Resonant Cyclotron Scattering and Comptonization in Neutron Star Magnetospheres
Lyutikov, M; Lyutikov, Maxim; Gavriil, Fotis P.
2006-01-01
Resonant cyclotron scattering of the surface radiation in the magnetospheres of neutron stars may considerably modify the emergent spectra and impede efforts to constraint neutron star properties. Resonant cyclotron scattering by a non-relativistic warm plasma in an inhomogeneous magnetic field has a number of unusual characteristics: (i) in the limit of high resonant optical depth, the cyclotron resonant layer is half opaque, in sharp contrast to the case of non-resonant scattering. (ii) The transmitted flux is on average Compton up-scattered by ~ $1+ 2 beta_T$, where $\\beta_T$ is the typical thermal velocity in units of the velocity of light; the reflected flux has on average the initial frequency. (iii) For both the transmitted and reflected fluxes the dispersion of intensity decreases with increasing optical depth. (iv) The emergent spectrum is appreciably non-Plankian while narrow spectral features produced at the surface may be erased. (v) Optical photons are less affected by resonant Comptonization tha...
Resonance scattering of canonical elastic shells in absorbing fluid medium
ZHUO Linkai; FAN Jun; TANG Weilin
2008-01-01
Resonance scattering of elastic spherical shell and cylindrical shell while the sur-rounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable resul twould be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surround-ing fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little in fluence on the low-frequency resonance scattering induced by the filler inside the shell.
Resonance magnetic x-ray scattering study of erbium
Sanyal, M.K.; Gibbs, D.; Bohr, J.;
1994-01-01
of this magnetic scattering and analyzed it using a simple model based on electric dipole and quadrupole transitions among atomic orbitals. The line shapes can be fitted to a magnetic structure combining both c-axis-modulated and basal-plane components. Below 18 K, we have observed unusual behavior......The magnetic phases of erbium have been studied by resonance x-ray-scattering techniques. When the incident x-ray energy is tuned near the L(III) absorption edge, large resonant enhancements of the magnetic scattering are observed above 18 K. We have measured the energy and polarization dependence...... of the magnetic scattering as a function of energy, whose origin is not understood....
Resonance propagation in heavy-ion scattering
Bijoy Kundu; B K Jain
2001-06-01
The formalism developed earlier by us for the propagation of a resonance in the nuclear medium in proton–nucleus collisions has been modiﬁed to the case of vector boson production in heavy-ion collisions. The formalism includes coherently the contribution to the observed di-lepton production from the decay of a vector boson inside as well as outside the nuclear medium. The medium modiﬁcation of the boson is incorporated through an energy dependent optical potential. The calculated invariant mass distributions are presented for the -meson production using optical potentials estimated within the VDM and the resonance model. The shift in the invariant mass distribution is found to be small. To achieve the mass shift (of about 200 MeV towards lower mass) as indicated in the high energy heavy-ion collision experiments, an unusually strong optical potential of about -120 MeV is required. We also observe that, for not so heavy nuclear systems and/or for fast moving resonances, the shape, magnitude and peak position of the invariant mass distribution is substantially different if the contributions from the resonance decay inside and outside are summedup at the amplitude level (coherently) or at the cross section level (incoherently).
Self-Consistent Scattering Calculation of Resonant Tunneling Diode Characteristics
Sun, J P; Haddad, G. I.
1998-01-01
We perform a self-consistent calculation of resonant tunneling diode (RTD) I-V characteristics including optical phonon scattering. The self-consistency is obtained by solving the Schrödinger equation and Poisson’s equation iteratively with the Thomas-Fermi approximation used for the device contact regions. For evaluation of phonon-assisted current density, the optical phonon scattering in the quantum well is modeled using the optical model potential. Electron transverse momentum is also inco...
New Physics / Resonances in Vector Boson Scattering at the LHC
Reuter, J; Ohl, T; Sekulla, M
2016-01-01
Vector boson scattering is (together with the production of multiple electroweak gauge bosons) the key process in the current run 2 of LHC to probe the microscopic nature of electroweak symmetry breaking. Deviations from the Standard Model are generically parameterized by higher-dimensional operators, however, there is a subtle issue of perturbative unitarity for such approaches for the process above. We discuss a parameter-free unitarization prescription to get physically meaningful predictions. In the second part, we construct simplified models for generic new resonances that can appear in vector boson scattering, with a special focus on the technicalities of tensor resonances.
Resonant Raman scattering from silicon nanoparticles enhanced by magnetic response.
Dmitriev, Pavel A; Baranov, Denis G; Milichko, Valentin A; Makarov, Sergey V; Mukhin, Ivan S; Samusev, Anton K; Krasnok, Alexander E; Belov, Pavel A; Kivshar, Yuri S
2016-05-01
Enhancement of optical response with high-index dielectric nanoparticles is attributed to the excitation of their Mie-type magnetic and electric resonances. Here we study Raman scattering from crystalline silicon nanoparticles and reveal that magnetic dipole modes have a much stronger effect on the scattering than electric modes of the same order. We demonstrate experimentally a 140-fold enhancement of the Raman signal from individual silicon spherical nanoparticles at the magnetic dipole resonance. Our results confirm the importance of the optically-induced magnetic response of subwavelength dielectric nanoparticles for enhancing light-matter interactions. PMID:27113352
Fano Resonance Enhanced Nonreciprocal Absorption and Scattering of Light
Ben Hopkins
2015-06-01
Full Text Available We reveal that asymmetric plasmonic nanostructures can exhibit significantly different absorption and scattering properties for light that propagates in opposite directions, despite the conservation of total extinction. We analytically demonstrate that this is a consequence of nonorthogonality of eigenmodes of the system. This results in the necessity for modal interference with potential enhancement via Fano resonances. Based on our theory, we propose a stacked nanocross design whose optical response exhibits an abrupt change between absorption and scattering cross-sections for plane waves propagating in opposite directions. This work thereby proposes the use of Fano resonances to employ nanostructures for measuring and distinguishing optical signals coming from opposite directions.
Resonant Raman Scattering from Silicon Nanoparticles Enhanced by Magnetic Response
Dmitriev, Pavel A; Milichko, Valentin A; Makarov, Sergey V; Mukhin, Ivan S; Samusev, Anton K; Krasnok, Alexander E; Belov, Pavel A; Kivshar, Yuri S
2016-01-01
Enhancement of optical response with high-index dielectric nanoparticles is attributed to the excitation of their Mie-type magnetic and electric resonances. Here we study Raman scattering from crystalline silicon nanoparticles and reveal that magnetic dipole modes have much stronger effect on the scattering than electric modes of the same order. We demonstrate experimentally a 140-fold enhancement of Raman signal from individual silicon spherical nanoparticles at the magnetic dipole resonance. Our results confirm the importance of the optically-induced magnetic response of subwavelength dielectric nanoparticles for enhancing light-matter interactions.
Resonances in low-energy positron-alkali scattering
Horbatsch, M.; Ward, S. J.; Mceachran, R. P.; Stauffer, A. D.
1990-01-01
Close-coupling calculations were performed with up to five target states at energies in the excitation threshold region for positron scattering from Li, Na and K. Resonances were discovered in the L = 0, 1 and 2 channels in the vicinity of the atomic excitation thresholds. The widths of these resonances vary between 0.2 and 130 MeV. Evidence was found for the existence of positron-alkali bound states in all cases.
Resonance eigenfunctions in chaotic scattering systems
Martin Sieber
2009-09-01
We study the semiclassical structure of resonance eigenstates of open chaotic systems. We obtain semiclassical estimates for the weight of these states on different regions in phase space. These results imply that the long-lived right (left) eigenstates of the non-unitary propagator are concentrated in the semiclassical limit ħ → 0 on the backward (forward) trapped set of the classical dynamics. On this support the eigenstates display a self-similar behaviour which depends on the limiting decay rate.
Resonantly enhanced Bragg-scattering spectroscopy of an atomic transition
Yang, Xudong; Qiao, Cuifang; Li, Chuanliang; Chen, Fenghua
2016-07-01
A novel resonantly enhanced Bragg-scattering (REBS) spectroscopy from a population difference grating (PDG) is reported. The PDG is formed by a standing-wave (SW) pump field, which periodically modulates the space population distributions of two levels in the 87Rb D1 line. Then, a probe beam, having identical frequency and orthogonal polarization with the SW pump field, is Bragg-scattered by the PDG. The research achievement shows that the Bragg-scattered light is strongest at an atomic transition, and forms an REBS spectrum with a high signal-to-noise ratio and sub-natural linewidth. The observed REBS can be applied in precise frequency measurements.
E791 Collaboration; Leksanov, A.; Alster, J.; Asryan, G.; Averichev, Y.; Barton, D; Baturin, V.; Bukhtoyarova, N.; Carroll, A.; Heppelmann, S.; Kawabata, T.; Makdisi, Y.; Malki, A.; Minina, E.; Navon, I.
2000-01-01
We present a new measurement of the energy dependence of nuclear transparency from AGS experiment E850, performed using the EVA solenoidal spectrometer, upgraded since 1995. Using a secondary beam from the AGS accelerator, we simultaneously measured $pp$ elastic scattering from hydrogen and $(p,2p)$ quasi-elastic scattering in carbon at incoming momenta of 5.9, 8.0, 9.0, 11.7 and 14.4 GeV/c. This incident momentum range corresponds to a $Q^{2}$ region between 4.8 and 12.7 (GeV/c)$^{2}$. The d...
Resonant Raman scattering from silicon nanoparticles enhanced by magnetic response
Dmitriev, Pavel A.; Baranov, Denis G.; Milichko, Valentin A.; Makarov, Sergey V.; Mukhin, Ivan S.; Samusev, Anton K.; Krasnok, Alexander E.; Belov, Pavel A.; Kivshar, Yuri S.
2016-05-01
Enhancement of optical response with high-index dielectric nanoparticles is attributed to the excitation of their Mie-type magnetic and electric resonances. Here we study Raman scattering from crystalline silicon nanoparticles and reveal that magnetic dipole modes have a much stronger effect on the scattering than electric modes of the same order. We demonstrate experimentally a 140-fold enhancement of the Raman signal from individual silicon spherical nanoparticles at the magnetic dipole resonance. Our results confirm the importance of the optically-induced magnetic response of subwavelength dielectric nanoparticles for enhancing light-matter interactions.Enhancement of optical response with high-index dielectric nanoparticles is attributed to the excitation of their Mie-type magnetic and electric resonances. Here we study Raman scattering from crystalline silicon nanoparticles and reveal that magnetic dipole modes have a much stronger effect on the scattering than electric modes of the same order. We demonstrate experimentally a 140-fold enhancement of the Raman signal from individual silicon spherical nanoparticles at the magnetic dipole resonance. Our results confirm the importance of the optically-induced magnetic response of subwavelength dielectric nanoparticles for enhancing light-matter interactions. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07965a
D Pi scattering and D meson resonances from lattice QCD
Mohler, Daniel; Woloshyn, R M
2012-01-01
The masses and widths of the broad scalar D_0^*(2400) and the axial D_1(2430) charmed-light resonances are extracted by simulating the corresponding D Pi and D* Pi scattering on the lattice. The resonance parameters are obtained using a Breit-Wigner fit of the elastic phase shifts. The resulting D_0^*(2400) mass is 351+/-21 MeV above the spin-average 1/4(m_D+3m_{D*}), in agreement with the experimental value of 347+/-29 MeV above. The resulting D_0^* to D Pi coupling g^{lat}=2.55+/-0.21 GeV is close to the experimental value g^{exp}<=1.92+/-0.14 GeV, where g parametrizes the width $\\Gamma\\equiv g^2p^*/s$. The resonance parameters for the broad D_1(2430) are also found close to the experimental values; these are obtained by appealing to the heavy quark limit, where the neighboring resonance D_1(2420) is narrow. The calculated I=1/2 scattering lengths are a_0=0.81+/-0.14 fm for D Pi and a_0=0.81+/-0.17 fm for D* Pi scattering. The simulation of the scattering in these channels incorporates quark-antiquark as...
Resonance structure in elastic scattering of electrons from atomic hydrogen
Warner, C.D.; King, G.C.; Hammond, P.; Slevin, J.
1986-10-28
High-energy-resolution spectra of electrons scattered elastically from atomic hydrogen have been obtained for incident electron energies of 9.2-10.4 eV and at angles of 33/sup 0/, 54/sup 0/, 70/sup 0/ and 90/sup 0/. The energy spread of the incident electron beam is estimated to be typically 25 meV FWHM. In addition to the /sup 1/S and /sup 3/P resonances which have been reported in earlier studies, a /sup 1/D resonance can be clearly seen and there is some evidence of a resonance state at a higher energy, probably corresponding to a /sup 1/S resonance state. The energies and resonance widths of all these features have been determined.
Resonance structure in elastic scattering of electrons from atomic hydrogen
High-energy-resolution spectra of electrons scattered elastically from atomic hydrogen have been obtained for incident electron energies of 9.2-10.4 eV and at angles of 330, 540, 700 and 900. The energy spread of the incident electron beam is estimated to be typically 25 meV FWHM. In addition to the 1S and 3P resonances which have been reported in earlier studies, a 1D resonance can be clearly seen and there is some evidence of a resonance state at a higher energy, probably corresponding to a 1S resonance state. The energies and resonance widths of all these features have been determined. (author)
Simultaneous χ2 analyses are performed for elastic scattering and fusion cross section data for the 12C+208Pb system at near-Coulomb-barrier energies by using the extended optical model approach in which the polarization potential is decomposed into direct reaction (DR) and fusion parts. Use is made of the double folding potential as a bare potential. It is found that the experimental elastic scattering and fusion data are well reproduced without introducing any normalization factor for the double folding potential and also that both DR and fusion parts of the polarization potential determined from the χ2 analyses satisfy separately the dispersion relation. Furthermore, it is shown that the imaginary parts of both DR and fusion potentials at the strong absorption radius change very rapidly, which results in a typical threshold anomaly in the total imaginary potential as observed with tightly bound projectiles such as α-particle and 16O
Leksanov, A.; Alster, J.; Asryan, G.; Averichev, Y.; Barton, D.; Baturin, V.; Bukhtojarova, N.; Carroll, A.; Schetkovsky, A.; Heppelmann, S.; Kawabata, T.; Malki, A.; Makdisi, Y.; Minina, E.; Navon, I.; Nicholson, H.; Ogawa, A.; Panebratsev, Y.; Piasetzky, E.; Shimanskiy, S.; Tang, A.; Watson, J. W.; Yoshida, H.; Zhalov, D.
2000-12-01
We present a new measurement of the energy dependence of nuclear transparency from AGS experiment E850, performed using the EVA solenoidal spectrometer, upgraded since 1995. Using a secondary beam from the AGS accelerator, we simultaneously measured pp elastic scattering from hydrogen and (p,2p) quasi-elastic scattering in carbon at incoming momenta of 5.9, 8.0, 9.0, 11.7 and 14.4 GeV/c. This incident momentum range corresponds to a Q2 region between 4.8 and 12.7 (GeV/c)2. The detector allowed us to do a complete kinematic analysis for the center-of-mass polar angles in the range 85°-90°. We report on the measured variation of the nuclear transparency with energy and compare the new results with previous measurements.
Reduced transport velocity of multiply scattered light due to resonant scattering
Störzer, Martin; Aegerter, Christof M; Maret, Georg
2006-01-01
The transport properties of photons traveling through random media are of great fundamental and applied importance. For instance the dwell time due to resonant Mie scattering can lead to a significant reduction in transport velocity. Here, we have measured directly the energy-transport velocity of photons in strongly scattering media using a combination of time resolved transmission, measuring the diffusion coefficient, and angular resolved backscattering, yielding the transport mean free pat...
Yao, Xiaojun; Müller, Berndt
2016-01-01
We study the dynamical screening effect in the QED plasma on the $\\alpha$-$\\alpha$ scattering at the $^8$Be resonance. Dynamical screening leads to an imaginary part of the potential which results in a thermal width for the resonance and dominates over the previously considered static screening effect. As a result, both the resonance energy and width increase with the plasma temperature. Furthermore, dynamical screening can have a huge impact on the $\\alpha$-$\\alpha$ thermal nuclear scattering rate. For example, when the temperature is around $10$ keV, the rate is suppressed by a factor of about $900$. We expect similar thermal suppressions of nuclear reaction rates to occur in nuclear reactions dominated by an above threshold resonance with a thermal energy. Dynamical screening effects on nuclear reactions can be relevant to cosmology and astrophysics.
Birkedal, Dan; Shah, Jagdeep; Shchegrov, Andrei V.;
2000-01-01
Resonant Rayleigh scattering from quantum well excitons is investigated using ultrafast spectral interferometry. We isolate the coherent Rayleigh scattering from incoherent luminescence in a single speckle. Averaging the resonant Rayleigh intensity over several speckles allows us to identify...
Resonant proton scattering of $^{22}$Mg and $^{21}$Na
Di julio, D D; Jansson, K; Rudolph, D; Fynbo, H O U; Nilsson, T; Perea martinez, A
In our letter-of-intent, INTC-I-051, we discussed the physics case for scattering and transfer reactions involving light nuclei in the break-out region of the rp-process. The Committee found the physics case compelling and supported the letter-of-intent under the premise that beams of proper quality were developed and that an adequate detector set-up was presented. As these two requirements have been met recently we now propose to study resonant proton scattering of $^{22}$Mg to identify the states at 1.733 MeV and 2.575 MeV in $^{23}$Al that have been reported from the $^{24}$Mg($^{7}$Li,$^{8}$He)$\\,^{23}\\!$Al reaction but that remained unobserved in the only resonant proton scattering experiment performed with $^{22}$Mg so far. In particular we should be able to investigate the character of the proton emission of the 2.575 MeV state which may also have a significant inelastic branch. We also propose to perform resonant proton scattering on $^{21}$Na above $\\alpha$-particle threshold with $^{18}$Ne to study ...
Pion-nucleus scattering at around the DELTA (1232) resonance
Ahmed, H S; Rahman, M A; Rahman, S N
2003-01-01
The pion-nucleus scattering around 200 MeV and just above 1200 MeV is dominated by strong, broad DELTA (3,3) and weak resonances in the pi sup+-N interaction. The interaction to a first approximation can be described as diffraction process. Since it is well known that the strength of the pi sup + N and pi sup - N interactions are quite different from each other at the resonances, the analyses of differential cross section for pi sup + N and pi sup - N elastic scattering data in the region of low-lying pion-nucleus resonances will be a good test of different strengths. In the present work we analyze pions scattering from nuclei sup 9 Be, sup 2 sup 8 Si, sup 5 sup 8 Ni, sup 8 sup 9 Y and sup 2 sup 0 sup 8 Pb at incident pion energies between 50 and 291 MeV within the framework of the three parameter version of the Strong Absorption Model of Frahn and Venter. All the oscillations in the elastic scattering experimental data and for the experimental angular distribution leading to 2 sup + and 3 sup - collective st...
Theory of coherent phenomena and fundamentals in nuclear resonant scattering
We discuss the general theory of coherent phenomena in nuclear resonant interaction of γ-quanta with crystals. The coherence is realized in collective excitation of the ensemble of nuclei (nuclear exciton) with the conservation of phase memory and in the transformation of a γ-quantum into a quasi-particle of Bloch type in a crystal. The collective character of excitations causes a change in the resonant nuclear parameters and in the lifetime of the excited state. This manifests itself in a speed-up of the decay in the forward direction in a thin crystal and, on the contrary, a strong reduction of elastic scattering in a thick crystal. The reconstruction of the wavefunction of an individual γ-quantum in scattering under Laue or Bragg conditions leads to the suppression effect of inelastic incoherent channels. This effect is discussed in detail. The analysis is based on a derived general system of equations describing the resonant diffraction of γ-quanta in a crystal with an arbitrary relation between the coherent and incoherent channels. This system is used to deduce the equations describing the time-dependent nuclear resonant scattering of synchrotron radiation. We discuss the most instructive experiments with revealing coherent phenomena
Resonant magnetic scattering of polarized soft x rays
Sacchi, M. [Centre Universitaire Paris-Sud, Orsay (France); Hague, C.F. [Universite Pierre et Marie Curie, Paris (France); Gullikson, E.M.; Underwood, J. [Ernest Orlando Lawrence Berkeley National Lab., CA (United States)
1997-04-01
Magnetic effects on X-ray scattering (Bragg diffraction, specular reflectivity or diffuse scattering) are a well known phenomenon, and they also represent a powerful tool for investigating magnetic materials since it was shown that they are strongly enhanced when the photon energy is tuned across an absorption edge (resonant process). The resonant enhancement of the magnetic scattering has mainly been investigated at high photon energies, in order to match the Bragg law for the typical lattice spacings of crystals. In the soft X-ray range, even larger effects are expected, working for instance at the 2p edges of transition metals of the first row or at the 3d edges of rare earths (300-1500 eV), but the corresponding long wavelengths prevent the use of single crystals. Two approaches have been recently adopted in this energy range: (i) the study of the Bragg diffraction from artificial structures of appropriate 2d spacing; (ii) the analysis of the specular reflectivity, which contains analogous information but has no constraints related to the lattice spacing. Both approaches have their own specific advantages: for instance, working under Bragg conditions provides information about the (magnetic) periodicity in ordered structures, while resonant reflectivity can easily be related to electronic properties and absorption spectra. An important aspect common to all the resonant X-ray scattering techniques is the element selectivity inherent to the fact of working at a specific absorption edge: under these conditions, X-ray scattering becomes in fact a spectroscopy. Results are presented for films of iron and cobalt.
Resonance electronic Raman scattering in rare earth crystals
Williams, G.M.
1988-11-10
The intensities of Raman scattering transitions between electronic energy levels of trivalent rare earth ions doped into transparent crystals were measured and compared to theory. A particle emphasis was placed on the examination of the effect of intermediate state resonances on the Raman scattering intensities. Two specific systems were studied: Ce/sup 3 +/(4f/sup 1/) in single crystals of LuPO/sub 4/ and Er/sup 3 +/(4f/sup 11/) in single crystals of ErPO/sub 4/. 134 refs., 92 figs., 33 tabs.
Resonance electronic Raman scattering in rare earth crystals
The intensities of Raman scattering transitions between electronic energy levels of trivalent rare earth ions doped into transparent crystals were measured and compared to theory. A particle emphasis was placed on the examination of the effect of intermediate state resonances on the Raman scattering intensities. Two specific systems were studied: Ce3+(4f1) in single crystals of LuPO4 and Er3+(4f11) in single crystals of ErPO4. 134 refs., 92 figs., 33 tabs
Resonances and adiabatic invariance in classical and quantum scattering theory
Jain, S R
2004-01-01
We discover that the energy-integral of time-delay is an adiabatic invariant in quantum scattering theory and corresponds classically to the phase space volume. The integral thus found provides a quantization condition for resonances, explaining a series of results recently found in non-relativistic and relativistic regimes. Further, a connection between statistical quantities like quantal resonance-width and classical friction has been established with a classically deterministic quantity, the stability exponent of an adiabatically perturbed periodic orbit. This relation can be employed to estimate the rate of energy dissipation in finite quantum systems.
Far-field superresolution by imaging of resonance scattering
Schuster, Gerard T.
2014-10-31
We show that superresolution imaging in the far-field region of the sources and receivers is theoretically and practically possible if migration of resonant multiples is employed. A resonant multiple is one that bounces back and forth between two scattering points; it can also be the multiple between two smoothly varying interfaces as long as the reflection wave paths partially overlap and reflect from the same Fresnel zone. For a source with frequency f, compared to a one-way trip, N round trips in propagating between two scatterers increase the effective frequency by 2N × f and decrease the effective wavelength by λ/(2N). Thus, multiples can, in principle, be used as high-frequency probes to estimate detailed properties of layers. Tests with both synthetic and field data validate this claim. Improved resolution by multiple imaging is not only feasible for crustal reflections, but might be applicable to mantle and core reverberations recorded by earthquake seismologists.
Resonant scattering and diffraction beamline P09 at PETRA III
Strempfer, J.; Francoual, S.; Reuther, D.; Shukla, D. K.; Skaugen, A.; Schulte-Schrepping, H.; Kracht, T.; Franz, H.
2013-01-01
The resonant scattering and diffraction beamline P09 at PETRA III is designed for X-ray experiments requiring small beams, energy tunability, variable polarization and high photon flux. It is highly flexible in terms of beam size and offers full higher harmonic suppression. A state of the art double phase retarder setup provides variable linear or circular polarization. A high precision Psi-diffractometer and a heavy load diffractometer in horizontal Psi-geometry allow the accommodation of a ...
Resonance scattering of radio waves in the acoustically disturbed ionosphere
It is known that acoustic waves are excited in the atmosphere for a variety of reasons, including seismic oscillations of the earth's surface as a result of earthquakes, volcanic eruptions, explosions, and in the operation of other powerful sources of natural or artificial origin. When sound waves are sufficiently intense, they can create disturbances in the electron density at ionospheric heights. In this paper, we consider the properties of radio wave scattering off such disturbances created by infrasound waves, i.e., we consider Mandel'shtam-Brillouin scattering in the ionosphere. The authors discuss the possibility of a radiophysical enhancement of the effect connected with the phenomenon of resonance scattering of the radiowaves off the disturbances created in the medium by the acoustic wave
Compositeness of the Delta(1232) resonance in pi N scattering
Sekihara, Takayasu; Yamagata-Sekihara, Junko; Yasui, Shigehiro
2015-01-01
We evaluate the $\\pi N$ compositeness of the $\\Delta (1232)$ resonance so as to clarify the internal structure of $\\Delta (1232)$ in terms of the $\\pi N$ component. Here the compositeness is defined as contributions from two-body wave functions to the normalization of the total wave function and is extracted from the $\\pi N$ scattering amplitude. In this study we employ the chiral unitary approach with the interaction up to the next-to-leading order plus a bare $\\Delta$ term in chiral perturbation theory and describe $\\Delta (1232)$ in an elastic $\\pi N$ scattering. Fitting the $\\pi N$ scattering amplitude to the solution of the partial wave analysis, we obtain a large real part of the $\\pi N$ compositeness for $\\Delta (1232)$ comparable to unity and non-negligible imaginary part as well, with which we reconfirm the result in the previous study on the $\\pi N$ compositeness for $\\Delta (1232)$.
This research thesis reports the study of the mechanism of emission of alpha particles in the 11B (p, 3 α) reaction with respect to the effects of spins and parities of the various resonances met between 150 keV and 4 MeV. From an experimental point of view, the reaction has been studied by two methods: the detection of alpha particles by a semiconductor-based counter located at a given angle with respect to the beam direction and study of continuous spectra of alpha particles with respect to projectile energies, and recording, for a given resonance, of alpha-alpha coincidences by using the multi-parametric technique with two semiconductor-based sensors with a varying relative angular position. After a discussion of the main characteristics of resonance and of the mechanism of emission of alpha particles, the author first reports the theoretical study of a reaction producing three particles in the final state, and then reports the theoretical calculation of direct alpha spectrum shapes in the case of the 11B (p, 3 α) reaction (statistic hypothesis, hypothesis of interaction with two particles in the final state). The next part reports the experimental study of the 11B (p, 3 α) reaction
Resonance Scattering Mechanisms in Solids and at Solid Surfaces.
Gerber, Andrew D.
1987-09-01
The concept of resonance electron scattering is applied to two very different solid state systems, one at the surface of a solid and one in the bulk. In part I, the problem of resonance scattering of electrons from molecules adsorbed on a metallic surface is examined. An analysis is made of the factors leading to the broadening and energy shift of the e -N _{2} vibrational excitation cross sections as compared to their gas phase analogues. Two effects are found to be important: the breaking of the molecular symmetry by the surface, and the influence of the metallic image potential. Multiple scattering calculations verify that these mechanisms produce a broadening and energy shift in the range of those seen experimentally. In part II, a new mechanism is formulated for the attenuation of ultrasound in mixed valence metals. The mechanism is based on the coupling of phonons to electrons in localized, atomic-like f-levels. The local nature of the interaction gives rise to a large enhancement over the standard (Pippard) result, especially in the limit of short electron mean free path. The mechanism also produces a 'bump' in the attenuation coefficient as a function of temperature, offering an explanation for the experimentally observed 12 K feature of UPt_{3} . A calculation of the attenuation coefficient for a mixed valence lattice reveals further enhancement and structure caused by coherent absorption at f-levels in many unit cells. The effects of degeneracy and correlation are examined in a calculation of the ultrasound attenuation for a system containing dilute Kondo impurities. The unifying theme of this work is the strong interaction between electrons and vibrational modes resulting from the trapping of electrons in localized resonance states. This mechanism has previously been seen to be of great importance for electron-molecule collisions in the gas phase. In the present work, its importance is demonstrated for scattering processes in solids and at solid surfaces
HU Xiao-li; LIU Sa; LIU Shao-pu; LIU Zhong-fang; SONG Yan-qi
2011-01-01
In a pH=0.65-1.5 NaAc-HCI medium, methylene blue(MB) reacts with 12-tungstophosphoric acid (TPA) by virtue of electrostatic attraction and hydrophobic force to form a 3:2 ion-association complex. As a result,the intensities of resonance Rayleigh scattering(RRS), second-order scattering(SOS) and frequency doubling scattering(FDS) are enhanced greatly. The maximum scattering wavelengths of RRS, SOS and FDS are located at 316, 647 and 311 nm. The increments of scattering intensity(ΔI) are directly proportional to the concentration of MB in a certain range. The methods exhibited high sensitivity, and the detection limits(3σ) for MB are 2.3 ng/mL(RRS method),5.6 ng/mL(SOS method) and 6.4 ng/mL(FDS method), respectively. The effects of coexisting substances have been examined, and the results indicate that the methods have good selectivity. Based on the above researches, a new spectral method for the determination of trace amounts of MB has been developed. It can be applied to the determination of MB in human serum, and the recoveries are 97.5％-105.0％. The results are in good agreement with those obtained by the pharmacopoeia method. In this work, the optimum conditions of the reaction and the influencing factors were investigated. In addition, the reaction mechanism and the reasons of the enhancement of resonance light scattering were discussed.
12C+12C reactions at astrophysical energies: Tests of targets behaviour under beam bombardment
12C(12C,α)20Ne and 12C(12C,p)23Na are the most important reactions during the carbon burning phase in stars. Direct measurements at the relevant astrophysical energy (E=1.5±0.3MeV) are very challenging because of the extremely small cross sections involved and of the high beam-induced background originating from impurities in the targets. In addition, persistent resonant structures at low energies are not well understood and make the extrapolation of the cross section from high energy data very uncertain. As a preliminary step towards the measurements of the 12C(12C,α)20Ne and 12C(12C,p)23Na reactions we intend to investigate the behaviour of targets under beam bombardment, specifically the quantitative measurement of hydrogen and deuterium content of highly pure stable carbon targets in relation to target temperature. Experiments are taking place at the CIRCE accelerator in Caserta, Italy and preliminary results are presented here
Resonance scattering and RBS from non-stoichiometric oxides
Rutherford back scattering (RBS) and elastic nuclear resonance (non-RBS resonance scattering of 3.05 MeV α-particles from oxygen atoms of a sample, for example) have been used for non-destructive characterization of differently fired samples of cadmium oxide (a II-VI semiconductor), Bi2Sr2CaCu2O(8+x) and (Bi0.92Pb0.17)2Sr2CaCu2O(8+x) high temperature superconductors, and practically useful films of a composite of diamond nanoparticles and Si-O made by CV deposition on Si substrate. In the RBS spectrum, steps for light elements like O and Ca are practically not visible, while steps for heavy elements like Bi and Cd are clear and large. In contrast, there is a clear resonance peak due to oxygen allowing easy detection of oxygen in a sample. Most important of our present RBS findings is reduction of O-content from cadmium oxide on firing (here for 36 h) at higher and higher temperatures up to 800 deg. C. Large variations of room temperature (300 K) electrical resistivity of CdO after heat treatments at different temperatures for 36 h have been explained on basis of variation in O-content. Its room temperature resistivity of 26.4 mΩ cm for firing at 275 deg. C reduces to only 2.15 mΩ cm for firing at 800 deg. C
Resonant depolarized dynamic light scattering of silver nanoplatelets
Zimbone, M., E-mail: massimo.zimbone@ct.infn.it [CNR-IMM (Italy); Messina, E. [IPCF-CNR Istituto per i Processi Chimico-Fisici (Italy); Compagnini, G.; Fragalà, M. E. [Dipartimento di Scienze Chimiche (Italy); Calcagno, L. [Dipartimento di Fisica ed Astronomia (Italy)
2015-10-15
Polarized and depolarized dynamic light scattering (DDLS) methodology was carried out on silver nanoplatelets showing strong plasmon-enhanced scattering. The hydrodynamic properties of the nanoparticles were determined by measuring the translation diffusion coefficient for “out resonant” condition and the rotational diffusion coefficient for “in resonant” condition. The results have been interpreted by applying an oblate ellipsoidal model, which allows a direct evaluation of nanoplatelets’ size and shape in agreement with scanning electron microscopy. The characterised nanoplatelets reveal a transversal size of 20 nm and a longitudinal length in the range 65–92 nm. Our investigation shows that DDLS in resonant condition is a simple and powerful technique to determine the size and shape of plasmonic nanoparticles and it can be successfully applied to characterise the dynamics of metallic nanoplatelets.
Delta Electroproduction in 12-C
Steven McLauchlan
2003-01-31
The Delta-nucleus potential is a crucial element in the understanding of the nuclear system. Previous electroexcitation measurements in the delta region reported a Q2 dependence of the delta mass indicating that this potential is dependent on the momentum of the delta. Such a dependence is not observed for protons and neutrons in the nuclear medium. This thesis presents the experimental study of the electroexcitation of the delta resonance in 12C, performed using the high energy electron beam at the Thomas Jefferson National Accelerator Facility, and the near 4(pie) acceptance detector CLAS that enables the detection of the full reaction final state. Inclusive, semi inclusive, and exclusive cross sections were measured with an incident electron beam energy of 1.162GeV over the Q2 range 0.175-0.475 (GeV/c)2. A Q2 dependence of the delta mass was only observed in the exclusive measurements indicating that the delta-nucleus potential is affected by the momentum of the delta.
On the resonance structure in nucleon-nucleon scattering
Kloet, W. M.; Tjon, J. A.
1981-10-01
A possible explanation of resonance-like structure in 1D 2 and 3F 3 proton-proton phase parameters at medium energy is suggested by the analysis of an exactly soluble coupled channel model. Looping in the Argand plot is mainly due to the nucleon-delta branch cut. This effect is already present in the NΔ box diagram, but is modified by higher order multiple scattering. Poles occur close to the NΔ branch point and originate from left-hand singularities in the unphysical sheet.
Resonance Region Structure Functions and Parity Violating Deep Inelastic Scattering
Carlson, Carl E.; Rislow, Benjamin C.
2012-01-01
The primary motive of parity violating deep inelastic scattering experiments has been to test the standard model, particularly the axial couplings to the quarks, in the scaling region. The measurements can also test for the validity of models for the off-diagonal structure functions $F_{1,2,3}^{\\gamma Z}(x,Q^2)$ in the resonance region. The off-diagonal structure functions are important for the accurate calculation of the $\\gamma Z$-box correction to the weak charge of the proton. Currently, ...
Resonant Raman scattering in InGaN alloys
Davydov, V.Yu.; Goncharuk, I.N.; Smirnov, A.N.; Sakharov, A.V.; Skvortsov, A.P.; Yagovkina, M.A. [A.F. Ioffe Physico-Technical Institute, 194021 St. Petersburg (Russian Federation); Klochikhin, A.A. [A.F. Ioffe Physico-Technical Institute, 194021 St. Petersburg (Russian Federation); Nuclear Physics Institute, 188350 St. Petersburg (Russian Federation); Lebedev, V.M. [Nuclear Physics Institute, 188350 St. Petersburg (Russian Federation); Lu, Hai; Schaff, William J. [Department of Electrical and Computer Engineering, Cornell University, Ithaca, New York 14853 (United States)
2006-06-15
A strong resonant behavior of the Raman scattering from LO-phonons in n-InGaN alloys at excitation near the interband absorption threshold was observed. An approach has been developed to describe the resonant Raman cross sectional profile in the presence of a Burstein-Moss shift of the interband optical transitions. It has been shown that a simultaneous study of absorption, photoluminescence, and Raman spectra provides reliable information about the band gap and can be efficient for the alloy characterization. Our data show that the band gap composition dependence of InGaN is characterized by the strongly nonlinear behavior with the large bowing parameter of 2.5-2.6 eV. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Resonant electronic Raman scattering: A BCS-like system
Rodrigues, Leonarde N.; Arantes, A.; Schüller, C.; Bell, M. J. V.; Anjos, V.
2016-05-01
In this paper we investigate the resonant intersubband Raman scattering of two-dimensional electron systems in GaAs-AlGaAs single quantum wells. Self-consistent calculations of the polarized and depolarized Raman cross sections show that the appearance of excitations at the unrenormalized single-particle energy are related to three factors: the extreme resonance regime, the existence of degeneracy in intersubband excitations of the electron gas, and, finally, degeneracy in the interactions between pairs of excitations. It is demonstrated that the physics that governs the problem is similar to the one that gives rise to the formation of the superconducting state in the BCS theory of normal metals. Comparison between experiment and theory shows an excellent agreement.
Modern Theory of Gratings Resonant Scattering: Analysis Techniques and Phenomena
Sirenko, Yuriy K
2010-01-01
Diffraction gratings are one of the most popular objects of analysis in electromagnetic theory. The requirements of applied optics and microwave engineering lead to many new problems and challenges for the theory of diffraction gratings, which force us to search for new methods and tools for their resolution. In Modern Theory of Gratings, the authors present results of the electromagnetic theory of diffraction gratings that will constitute the base of further development of this theory, which meet the challenges provided by modern requirements of fundamental and applied science. This volume covers: spectral theory of gratings (Chapter 1) giving reliable grounds for physical analysis of space-frequency and space-time transformations of the electromagnetic field in open periodic resonators and waveguides; authentic analytic regularization procedures (Chapter 2) that, in contradistinction to the traditional frequency-domain approaches, fit perfectly for the analysis of resonant wave scattering processes; paramet...
Resonant soft x-ray scattering studies of buried interfaces
Resonant soft x-ray scattering (RSXS) is a unique experimental tool to access the electronic properties of buried interfaces in heterostructures that contain transition metal oxides. In this contribution, studies of SrTiO3/LaAlO3, SrTiO3/(La,Ca)MnO3 and NdGaO3/(La,Ca)MnO3 interfaces are presented. Specifically, RSXS was employed to examine the electronic reconstruction of Ti 3d and O 2p valence states at the interfaces of SrTiO3/LaAlO3 superlattices. Similarly, we used resonant soft x-ray reflectivity to investigate the electronic structure at the interfaces of SrTiO3/(La,Ca)MnO3 and NdGaO3/(La,Ca)MnO3 thin film systems.
Pion-nucleus scattering at around the DELTA (1232) resonance
The pion-nucleus scattering around 200 MeV and just above 1200 MeV is dominated by strong, broad Δ (3,3) and weak resonances in the π±N interaction. The interaction to a first approximation can be described as diffraction process. Since it is well known that the strength of the π+N and π-N interactions are quite different from each other at the resonances, the analyses of differential cross section for π+N and π-N elastic scattering data in the region of low-lying pion-nucleus resonances will be a good test of different strengths. In the present work we analyze pions scattering from nuclei 9Be, 28Si, 58Ni, 89Y and 208Pb at incident pion energies between 50 and 291 MeV within the framework of the three parameter version of the Strong Absorption Model of Frahn and Venter. All the oscillations in the elastic scattering experimental data and for the experimental angular distribution leading to 2+ and 3- collective states could be well reproduced by the model. The best fit parameter values for T, Δ and μ are determined. They are respectively the cut-off angular momentum, rounding parameter and the real nuclear phase shift parameters of the model. The interaction radius 'R', the surface diffuseness 'd' and the reaction cross-section σr have been determined from the derived parameter values. The standard nuclear radius r0 and the surface diffuseness 'd' are fairly constant. The deformation parameters βL have been determined from the normalization constant of the theory to the experiment without making any change in the elastic scattering parameters. The β2 and β3 values so extracted are in good agreement with other works. It is observed that there is hardly any difference between the values of β2 (π+) and β2 (π-) and that between β3 (π+) and β3(π-) values. (author)
Ruel, Chris
2013-01-01
Demystifying the power of the Oracle 12c database The Oracle database is the industry-leading relational database management system (RDMS) used from small companies to the world's largest enterprises alike for their most critical business and analytical processing. Oracle 12c includes industry leading enhancements to enable cloud computing and empowers users to manage both Big Data and traditional data structures faster and cheaper than ever before. Oracle 12c For Dummies is the perfect guide for a novice database administrator or an Oracle DBA who is new to Oracle 12c. The book covers what
Measurements and applications of neutron multiple scattering in resonance region
Capture yield of neutrons impinging on a thick material is complicated due to self-shielding and multiple scattering, especially in the resonance region. When the incident neutron energy is equal to a resonance energy of the material, capture probability of the neutron increases with sample thickness and reaches a saturation value P sub(CO). There is a simple relation between P sub(CO) and GAMMA sub(n)/GAMMA and the recoil energy by the Monte-Carlo calculation. To examine validity of the relation, P sub(CO) was measured for 19 resonances in 12 nuclides with thick samples, using a JAERI linac time-of-flight spectrometer with Moxon-Rae type gamma ray detector and transmission type neutron flux monitor. Results of the measurements confirmed the validity. With this relation, the GAMMA sub(n)/GAMMA or GAMMA sub(γ)/GAMMA value can be obtained from the measured P sub(CO), and also the level spins be determined by combining the transmission data. Because of the definition of P sub(CO), determination of the resonance parameters is not sensitive to the sample thickness as far as it is sufficiently thick. (auth.)
Constraining the 12C+12C fusion cross section for astrophysics
Bucher B.
2015-01-01
Full Text Available The 12C+12C reaction is one of the single most important nuclear reactions in astrophysics. It strongly influences late evolution of massive stars as well as the dynamics of type Ia supernovae and x-ray superbursts. An accurate estimation of the cross section at relevant astrophysical energies is extremely important for modeling these systems. However, the situation is complicated by the unpredictable resonance structure observed at higher energies. Two recent studies at Notre Dame have produced results which help reduce the uncertainty associated with this reaction. The first uses correlations with the isotope fusion systems, 12C+13C and 13C+13C, to establish an upper limit on the resonance strengths in 12C+12C. The other focuses on the specific channel 12C+12C→23Mg+n and its low-energy measurement and extrapolation which is relevant to s-process nucleosynthesis. The results from each provide important constraints for astrophysical models.
An analysis of the 12C+12C reaction using a new type of coupling potential
Full text: 12C+12C system has been one of the most extensively studied reaction so far and is a subject attracting continuous interest from both theoretical and experimental point of views. Therefore, a large body of data over a wide energy range has been accumulated for this system from the systematic studies. The previous works in the literature clearly show that the standard coupled-channel approach is inadequate to explain the problems of this rection. It can fit neither any of the individual angular distributions nor the 90 deg. elastic scattering excitation function. In our couple-channels (CC) calculations, the interaction between the 12C nuclei is described by a deformed optical potential. The real potential has the square of a Woods-Saxon shape. The imaginary potential has the standard Woods-Saxon volume shape and its depth increases quadratically with energy as: W=-2.69+0.145ELab+0.0009(ELab)2. The 12C nucleus has a static quadrupole deformation and its excitation is described within the rotational model. The empirical deformation parameter, β2=-0.6, is used in these calculations. The limitations of the standard coupled-channels method, on the one hand, and the oblate character of thr 12C and the prolate character of the compound nucleus 24Mg, on the other hand, compelled us to use a new type of coupling potential which is ablate (attractive) when two 12C nuclei are at large distances and prolate (repulsive) when they are at short distances. For the new CC case, the agreement is very good for the elastic scattering, single-2+ and mutual-2+ excitation inelastic scattering data over the whole energy range studied. The theoretical predictions of the magnitudes and the phase of the oscillations for the mutual-2+ excitation inelastic scattering data, which have been the major outstanding problems of the reaction, are in a very good agreement with the empirical values
Yuan Bo; Wen Ji-Hong; Wen Xi-Sen
2013-01-01
A locally resonant sonic material (LRSM) is an elastic matrix containing a periodic arrangement of identical local resonators (LRs),which can reflect strongly near their natural frequencies,where the wavelength in the matrix is still much larger than the structural periodicity.Due to the periodic arrangement,an LRSM can also display a Bragg scattering effect,which is a characteristic of phononic crystals.A specific LRSM which possesses both local resonance and Bragg scattering effects is presented.Via the layered-multiple-scattering theory,the complex band structure and the transmittance of such LRSM are discussed in detail.Through the analysis of the refraction behavior at the boundary of the composite,we find that the transmittance performance of an LRSM for oblique incidence depends on the refraction of its boundary and the transmission behaviors of different wave modes inside the composite.As a result,it is better to use some low-speed materials (compared with the speed of waves in surrounding medium) as the LRSM matrix for designing sound blocking materials in underwater applications,since their acoustic properties are more robust to the incident angle.Finally,a gapcoupled LRSM with a broad sub-wavelength transmission gap is studied,whose acoustic performance is insensitive to the angle of incidence.
Scattering resonances of ultracold atoms in confined geometries
Saeidian, Shahpoor
2008-06-18
Subject of this thesis is the investigation of the quantum dynamics of ultracold atoms in confined geometries. We discuss the behavior of ground state atoms inside a 3D magnetic quadrupole field. Such atoms in enough weak magnetic fields can be approximately treated as neutral point-like particles. Complementary to the well-known positive energy resonances, we point out the existence of short-lived negative energy resonances. The latter originate from a fundamental symmetry of the underlying Hamiltonian. We drive a mapping of the two branches of the spectrum. Moreover, we analyze atomic hyperfine resonances in a magnetic quadrupole field. This corresponds to the case for which both the hyperfine and Zeeman interaction, are comparable, and should be taken into account. Finally, we develop a general grid method for multichannel scattering of two atoms in a two-dimensional harmonic confinement. With our approach we analyze transverse excitations/deexcitations in the course of the collisional process (distinguishable or identical atoms) including all important partial waves and their couplings due to the broken spherical symmetry. Special attention is paid to suggest a non-trivial extension of the CIRs theory developed so far only for the single-mode regime and zero-energy limit. (orig.)
Resonant Neutron Scattering from YBa_2Cu_3O_7
Fong, Hung Fai
1996-03-01
Recently our ( Collaborators: B. Keimer, D. Reznik, P. Bourges, I. Aksay ) study on the 41 meV magnetic resonance in YBa_2Cu_3O7 ( H. F. Fong, B. Keimer, P. W. Anderson, D. Reznik, F. Doğan, I. A. Aksay, Phy. Rev. Lett. \\underbar 75), 316 (1995) has received considerable attention. Evidence for this mode had already been collected by other groups, but our demonstration that the resonance disappears in the normal state has stimulated a large body of theoretical work. We have extended our study in several respects, using both polarized and unpolarized neutron scattering techniques. First, by calibrating the measured magnetic intensity against calculated structure factors of optical phonons and against antiferromagnetic spin waves in the same crystal after deoxygenation to YBa_2Cu_3O_6.2, we have established the absolute scale of its dynamical susceptibility \\chi''(q,ω) in the superconducting state and a limit on its magnitude in the normal state. Second, we have measured the energy and absolute spectral weight of the resonance accurately as a function of temperature. Our experimental results will be discussed in the light of recent theoretical work. Recent measurements of the high energy spin waves in the antiferromagnetic YBa_2Cu_3O_6.2 will also be reported.
Scattering resonances of ultracold atoms in confined geometries
Subject of this thesis is the investigation of the quantum dynamics of ultracold atoms in confined geometries. We discuss the behavior of ground state atoms inside a 3D magnetic quadrupole field. Such atoms in enough weak magnetic fields can be approximately treated as neutral point-like particles. Complementary to the well-known positive energy resonances, we point out the existence of short-lived negative energy resonances. The latter originate from a fundamental symmetry of the underlying Hamiltonian. We drive a mapping of the two branches of the spectrum. Moreover, we analyze atomic hyperfine resonances in a magnetic quadrupole field. This corresponds to the case for which both the hyperfine and Zeeman interaction, are comparable, and should be taken into account. Finally, we develop a general grid method for multichannel scattering of two atoms in a two-dimensional harmonic confinement. With our approach we analyze transverse excitations/deexcitations in the course of the collisional process (distinguishable or identical atoms) including all important partial waves and their couplings due to the broken spherical symmetry. Special attention is paid to suggest a non-trivial extension of the CIRs theory developed so far only for the single-mode regime and zero-energy limit. (orig.)
Emission of particles in the 12 C + 12 C fusion
A fusion process analysis of the 12 C + 12 C reaction is done, using the LILITA program. The analysis consisted mainly in varying the value of the Levels density parameter, determining on this way the value of such parameter which reproduces better the contribution of the different channels of fusion-evaporation of particles for this system at different energies. Moreover a comparison with measures done in the Instituto Nacional de Investigaciones Nucleares is realized. (Author)
Observation of superconductivity in hydrogen sulfide from nuclear resonant scattering.
Troyan, Ivan; Gavriliuk, Alexander; Rüffer, Rudolf; Chumakov, Alexander; Mironovich, Anna; Lyubutin, Igor; Perekalin, Dmitry; Drozdov, Alexander P; Eremets, Mikhail I
2016-03-18
High-temperature superconductivity remains a focus of experimental and theoretical research. Hydrogen sulfide (H2S) has been reported to be superconducting at high pressures and with a high transition temperature. We report on the direct observation of the expulsion of the magnetic field in H2S compressed to 153 gigapascals. A thin (119)Sn film placed inside the H2S sample was used as a sensor of the magnetic field. The magnetic field on the (119)Sn sensor was monitored by nuclear resonance scattering of synchrotron radiation. Our results demonstrate that an external static magnetic field of about 0.7 tesla is expelled from the volume of (119)Sn foil as a result of the shielding by the H2S sample at temperatures between 4.7 K and approximately 140 K, revealing a superconducting state of H2S. PMID:26989248
Tuning Mie scattering resonances in soft materials with magnetic fields.
Brunet, Thomas; Zimny, Kevin; Mascaro, Benoit; Sandre, Olivier; Poncelet, Olivier; Aristégui, Christophe; Mondain-Monval, Olivier
2013-12-27
An original approach is proposed here to reversibly tune Mie scattering resonances occurring in random media by means of external low induction magnetic fields. This approach is valid for both electromagnetic and acoustic waves. The experimental demonstration is supported by ultrasound experiments performed on emulsions made of fluorinated ferrofluid spherical droplets dispersed in a Bingham fluid. We show that the electromagnet-induced change of droplet shape into prolate spheroids, with a moderate aspect ratio of 2.5, drastically affects the effective properties of the disordered medium. Its effective acoustic attenuation coefficient is shown to vary by a factor of 5, by controlling both the flux density and orientation of the applied magnetic field. PMID:24483797
Charge-magnetic interference resonant scattering studies of ferromagnetic crystals and thin films
The element- and site-specificity of X-ray resonant magnetic scattering (XRMS) makes it an ideal tool for furthering our understanding of complex magnetic systems. In the hard X-rays, XRMS is readily applied to most antiferromagnets where the relatively weak resonant magnetic scattering (10-2-10-6Ic) is separated in reciprocal space from the stronger, Bragg charge scattered intensity, Ic. In ferro(ferri)-magnetic materials, however, such separation does not occur and measurements of resonant magnetic scattering in the presence of strong charge scattering are quite challenging. We discuss the use of charge-magnetic interference resonant scattering for studies of ferromagnetic (FM) crystals and layered films. We review the challenges and opportunities afforded by this approach, particularly when using circularly polarized X-rays. We illustrate current capabilities at the Advanced Photon Source with studies aimed at probing site-specific magnetism in ferromagnetic crystals, and interfacial magnetism in films. (authors)
Scattering phase shift and resonance properties on the lattice: an introduction
Prelovsek, S; Mohler, D
2011-01-01
We describe the method for extracting the elastic scattering phase shift from a lattice simulation at an introductory level, for non-lattice practitioners. We consider the scattering in a resonant channel, where the resulting phase shift delta(s) allows the lattice determination of the mass and the width of the resonance from a Breit-Wigner type fit. We present the method for the example of P-wave pi-pi scattering in the rho meson channel.
The use of resonance scattering of capture gamma rays as an analytical tool
The sensitivity for the resonance scattering of capture gamma rays as a tool to measure comparatively small concentrations of certain elements in bulk materials is investigated. Looking at the resonance for lead excited by iron capture gamma rays it is possible to measure concentrations down to less than 100 ppm. The advantages of the new technique are compared with other existing methods. The application of nuclear resonance scattering in prospecting for zirconium ores is emphasized
Martin Freer
2014-11-01
The nucleus 12C has a rather significant role in modern nuclear physics, but whose influence can be traced to the work of Hoyle in the 1950s, when it was concluded that there should be a state close to 7.68 MeV responsible for the synthesis of carbon in stellar nucleosynthesis. Although a state at 7.65 MeV was subsequently discovered, its properties have remained something of a mystery until rather recently. This paper explores our current understanding of the structure of 12C, in particular the nature of the Hoyle state.
Polaron hopping in olivine phosphates studied by nuclear resonant scattering
Tracy, Sally June
Valence fluctuations of Fe2+ and Fe3+ were studied in a solid solution of LixFePO4 by nuclear resonant forward scattering of synchrotron x rays while the sample was heated in a diamond-anvil pressure cell. The spectra acquired at different temperatures and pressures were analyzed for the frequencies of valence changes using the Blume-Tjon model of a system with a fluctuating Hamiltonian. These frequencies were analyzed to obtain activation energies and an activation volume for polaron hopping. There was a large suppression of hopping frequency with pressure, giving an anomalously large activation volume. This large, positive value is typical of ion diffusion, which indicates correlated motions of polarons, and Li+ ions that alter the dynamics of both. In a parallel study of NaxFePO4, the interplay between sodium ordering and electron mobility was investigated using a combination of synchrotron x-ray diffraction and nuclear resonant scattering. Conventional Mossbauer spectra were collected while the sample was heated in a resistive furnace. An analysis of the temperature evolution of the spectral shapes was used to identify the onset of fast electron hopping and determine the polaron hopping rate. Synchrotron x-ray diffraction measurements were carried out in the same temperature range. Reitveld analysis of the diffraction patterns was used to determine the temperature of sodium redistribution on the lattice. The diffraction analysis also provides new information about the phase stability of the system. The temperature evolution of the iron site occupancies from the Mossbauer measurements, combined with the synchrotron diffraction results give strong evidence for a relationship between the onset of fast electron dynamics and the redistribution of sodium in the lattice. Measurements of activation barriers for polaron hopping gave fundamental insights about the correlation between electronic carriers and mobile ions. This work established that polaron-ion interactions
Elimination of Pauli resonances in the generator-coordinate description of scattering
Microscopic descriptions of elastic scattering in a cluster model with different oscillator parameters lead to the occurence of resonances without definite physical meaning, related to the almost forbidden states, known as Pauli resonances. In the generator-coordinate method, a simple basic change allows one to obtain a microscopic model free of such resonances. This technique is illustrated on α + 16O scattering. Beyond the resonance region, phase shifts change very weakly. On the contrary, bound-state and physical-resonance energies may significantly be modified. The model seems to be physically more consistent when the almost forbidden states are eliminated. (orig.)
An Analysis of the $^{12}$C+$^{12}$C Reaction Using a New Type of Coupling Potential
Boztosun, I
2001-01-01
A new approach has been used to explain the experimental data for the $^{12}$C+$^{12}$C system over a wide energy range in the laboratory system from 32.0 MeV to 126.7 MeV. This new coupled-channels based approach involves replacing the usual first derivative coupling potential by a new, second-derivative coupling potential. This paper first shows and discusses the limitation of the standard coupled-channels theory in the case where one of the nuclei in the reaction is strongly deformed. Then, this new approach is shown to improve consistently the agreement with the experimental data: the elastic scattering, single-2$^{+}$ and mutual-2$^{+}$ excitation inelastic scattering data as well as their 90$^{\\circ}$ elastic and inelastic excitation functions with little energy-dependent potentials. This new approach makes major improvement on all the previous coupled-channels calculations for this system.
Unified description of bound, resonant and scattering states
Recently we have introduced a general method for calculating the discrete Hilbert-space basis representation of the Green's operators of those Hamiltonians which have infinite symmetric tridiagonal matrix forms. The elements of this matrix are used in the calculation of the Green's matrix in terms of a three-term recurrence relation and continued fractions. We specified our general approach to the case of the Coulomb problem and the Coulomb-Sturmian basis associated with it. As a further step, we can combine this new way of calculating the Coulomb-Green's matrix with a technique of solving integral equations in discrete Hilbert-space-basis representations. This provides us with a quantum mechanical approximation method which is rather general in the sense that it is equally applicable to solving bound-, resonant- and scattering-state problems with practically any potential of physical relevance. The method is especially suited to problems where Coulomb-like asymptotics have to be treated, but the formalism also contains the case of the free Green's operator as a special case. (author)
Resonant inelastic scattering at intermediate X-ray energies
Hague, C F; Journel, L; Gallet, J J; Rogalev, A; Krill, G; Kappler, J P
2000-01-01
We describe resonant inelastic X-ray scattering (RIXS) experiments and magnetic circular dichroism (MCD) in X-ray fluorescence performed in the 3-5 keV range. The examples chosen are X-ray fluorescence MCD of FeRh and RIXS experiments performed at the L/sub 3/ edge of Ce. Fe Rh is antiferromagnetic at room temperature but has a transition to the ferromagnetic state above 400 K. The Rh MCD signal is compared with an augmented spherical wave calculation. The experiment confirms the predicted spin polarization of the Rh 4d valence states. The RIXS measurements on Ce compounds and intermetallics address the problem of mixed valency especially in systems where degeneracy with the Fermi level remains small. Examples are taken from the 2p to (4f5d) /sup +1/ followed by 3d to 2p RIXS for a highly ionic compound CeF /sub 3/ and for almost gamma -like CeCuSi. (38 refs).
Imaging instantaneous electron flow with ultrafast resonant x-ray scattering
Popova-Gorelova, Daria
2015-01-01
We propose a novel way to image dynamical properties of nonstationary electron systems using ultrafast resonant x-ray scattering. Employing a rigorous theoretical analysis within the framework of quantum electrodynamics, we demonstrate that a single scattering pattern from a nonstationary electron system encodes the instantaneous interatomic electron current in addition to the structural information usually obtained by resonant x-ray scattering from stationary systems. Thus, inelastic contributions that are indistinguishable from elastic processes induced by a broadband probe pulse, instead of being a concern, serve as an advantage for time-resolved resonant x-ray scattering. Thereby, we propose an approach combining elastic and inelastic resonant x-ray scattering for imaging dynamics of nonstationary electron systems in both real space and real time. In order to illustrate its power, we show how it can be applied to image the electron hole current in an ionized diatomic molecule.
Scattering of core-shell nanowires with the interference of electric and magnetic resonances.
Liu, Wei; Miroshnichenko, Andrey E; Oulton, Rupert F; Neshev, Dragomir N; Hess, Ortwin; Kivshar, Yuri S
2013-07-15
We study the scattering of normally incident waves by core-shell nanowires, which support both electric and magnetic resonances. Within such nanowires, for p-polarized incident waves, each electric resonance corresponds to two degenerate scattering channels while the magnetic resonance corresponds to only one channel. Consequently, when the electric dipole (ED) and magnetic dipole (MD) are tuned to overlap spectrally, the magnitude of the ED is twice that of the magnetic one, leading to a pair of angles of vanishing scattering. We further demonstrate that the scattering features of nanowires are polarization dependent, and vanishing scattering angles also can be induced by Fano resonances due to the interference of higher-order electric modes with the broad MD mode. PMID:23939129
Fano resonance-induced negative optical scattering force on plasmonic nanoparticles.
Chen, Huajin; Liu, Shiyang; Zi, Jian; Lin, Zhifang
2015-02-24
We demonstrate theoretically that Fano resonance can induce a negative optical scattering force acting on plasmonic nanoparticles in the visible light spectrum when an appropriate manipulating laser beam is adopted. Under the illumination of a zeroth-order Bessel beam, the plasmonic nanoparticle at its Fano resonance exhibits a much stronger forward scattering than backward scattering and consequently leads to a net longitudinal backward optical scattering force, termed Fano resonance-induced negative optical scattering force. The extinction spectra obtained based on the Mie theory show that the Fano resonance arises from the interference of simultaneously excited multipoles, which can be either a broad electric dipole mode and a narrow electric quadrupole mode, or a quadrupole and an octupole mode mediated by the broad electric dipole. Such Fano resonance-induced negative optical scattering force is demonstrated to occur for core-shell, homogeneous, and hollow metallic particles and can therefore be expected to be universal for many other nanostructures exhibiting Fano resonance, adding considerably to the flexibility of optical micromanipulation on the plasmonic nanoparticles. More interestingly, the flexible tunability of the Fano resonance by particle morphology opens up the possibility of tailoring the optical scattering force accordingly, offering an additional degree of freedom to optical selection and sorting of plasmonic nanoparticles. PMID:25635617
Effect of the third π ∗ resonance on the angular distributions for electron-pyrimidine scattering
Mašín, Zdeněk; Gorfinkiel, Jimena D.
2016-07-01
We present a detailed analysis of the effect of the well known third π∗ resonance on the angular behaviour of the elastic cross section in electron scattering from pyrimidine. This resonance, occurring approximately at 4.7 eV, is of mixed shape and core-excited character. Experimental and theoretical results show the presence of a peak/dip behaviour in this energy range, that is absent for other resonances. Our investigations show that the cause of the peak/dip is an interference of background p-wave to p-wave scattering amplitudes with the amplitudes for resonant scattering. The equivalent resonance in pyrazine shows the same behaviour and the effect is therefore likely to appear in other benzene-like molecules. Contribution to the Topical Issue "Advances in Positron and Electron Scattering", edited by Paulo Limao-Vieira, Gustavo Garcia, E. Krishnakumar, James Sullivan, Hajime Tanuma and Zoran Petrovic.
Magnetism in heterogeneous thin film systems: Resonant X-ray scattering studies
Kortright, J B; Bader, S D; Hellwig, O; Marguiles, D T; Fullerton, E E
2003-01-01
Magnetic and chemical heterogeneity are common in a broad range of magnetic thin film systems. Emerging resonant soft X-ray scattering techniques are well suited to resolve such heterogeneity at relevant length scales. Resonant X-ray magneto-optical Kerr effect measurements laterally average over heterogeneity but can provide depth resolution in different ways, as illustrated in measurements resolving reversible and irreversible changes in different layers of exchange-spring heterostructures. Resonant small-angle scattering measures in-plane heterogeneity and can resolve magnetic and chemical scattering sources in different ways, as illustrated in measurements of granular alloy recording media.
α + 12C rotational bands in 16O
The total quantum number N of the α + 12C rotational bands in 16O is determined by a study of α + 12C elastic scattering. The 8+ and 9- states are found around the excitation energy Ex = 30 MeV and they are the member of the known rotational bands. At the same time, the 02+ state (Ex = 6.05 MeV) is found to be dominated by N = 8. (author)
Katsuma M.
2014-03-01
Full Text Available The total quantum number N of the α+12C rotational bands in 16O is determined by a study of α+12C elastic scattering. The 8+ and 9− states are found around the excitation energy Ex = 30 MeV and they are the member of the known rotational bands. At the same time, the 02+ state (Ex = 6.05 MeV is found to be dominated by N = 8.
Microscopic description of α-cluster states in {sup 12}C
Neff, Thomas; Feldmeier, Hans [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany)
2014-07-01
The structure of {sup 12}C is investigated, using both a microscopic α-cluster model and fermionic molecular dynamics (FMD) where individual nucleons are considered as degrees freedom. In the FMD calculation an effective realistic interaction derived in the unitary correlation operator method (UCOM) is employed. By explicitly including {sup 8}Be+α channels resonances and scattering states above the three-α threshold can be investigated. Of particular interest are the second 0{sup +} state, the famous Hoyle state, and the second 2{sup +} state. Monopole and quadrupole transition strengths are analyzed and compared to experiment.
New resonant inelastic X-ray scattering and coherent X-ray scattering station at UE49-SGM, BESSY II
Soft x-ray scattering techniques are powerful probes for the understanding of nano- and atomic-scale phenomena, including magnetism, atomic motion and electronic structure. New beamline UE49-SGM and experimental stations are currently under construction, dedicated to the techniques of resonant inelastic x-ray scattering (RIXS) and coherent x-ray scattering (CXS). This facility will have the unique possibility to combine high-resolution spatial information studies with high-resolution chemically- and atomically-selective spectroscopy studies for a broad range of applications.
Aharonov–Bohm effect in resonances for scattering by three solenoids
Tamura, Hideo
2015-01-01
We study how the Aharonov–Bohm effect is reflected in the location of quantum resonances for scattering by three solenoids at large separation. We also discuss what happens in the case of four solenoids.
A test of the theory of resonant scattering between analog nuclei
It has been suggested that strong resonances might be found in scattering between analog nuclei at energies near the Coulomb barrier. The authors have begun a study of such scattering for 7Be on 7Li using a 7Be beam produced with the OSU-LLNL radioactive ion beam facility. The resulting excitation function can be used to limit a combination of the strength and the width of any possible resonances
Use of nuclear resonant scattering of gamma rays for in vivo measurement of iron
Vartsky, D.; Wielopolski, L.; Ellis, K.J.; Cohn, S.H.
1981-01-01
A technique for determination of elements in human body in-vivo, utilizing nuclear resonant scattering of gamma rays has been developed. 847 keV photons emitted from a gaseous /sup 56/MnCl/sub 2/ source are resonantly scattered from /sup 56/Fe present in the body. The detection of these gamma rays is used to estimate the iron content of the liver or heart of patients. Details of the calibration procedure and potential molecular effects are described.
Evidence for Resonance Scattering in the X-ray Spectrum of Zeta Puppis
Leutenegger, Maurice
2008-01-01
We present XMM-Newton Reflection Grating Spectrometer observations of pairs of X-ray emission line profiles from the 0 star Zeta Pup that originate from the same He-like ion. The two profiles in each pair have different shapes and cannot both be consistently fit by models assuming the same wind parameters. We show that the differences in profile shape can be accounted for in a model including the effects of resonance scattering, which affects the resonance line in the pair but not the intercombination line. This implies that resonance scattering is also important in single resonance lines, where its effect is difficult to distinguish from a low effective continuum optical depth in the wind. Thus, resonance scattering may help reconcile X-ray line profile shapes with literature mass-loss rates.
Resonance scattering in the X-ray emission line profiles of Zeta Puppis
Leutenegger, M A; Kahn, S M; Owocki, S P; Paerels, F B S
2007-01-01
We present XMM-Newton Reflection Grating Spectrometer observations of pairs of X-ray emission line profiles from the O star Zeta Pup that originate from the same He-like ion. The two profiles in each pair have different shapes and cannot both be consistently fit by models assuming the same wind parameters. We show that the differences in profile shape can be accounted for in a model including the effects of resonance scattering, which affects the resonance line in the pair but not the intercombination line. This implies that resonance scattering is also important in single resonance lines, where its effect is difficult to distinguish from a low effective continuum optical depth in the wind. Thus, resonance scattering may help reconcile X-ray line profile shapes with literature mass-loss rates.
The limitations of resonant Compton scattering as a gamma-ray burst model
Brainerd, J. J.
1992-01-01
Resonant Compton upscattering is commended as a mechanism that produces a hard gamma-ray spectrum while suppressing X-rays. This model, however, has severe physical and observational limitations. Effective X-ray suppression places a lower limit on the electron density; above this limit X-rays scatter multiple times, so the single-scattering approximation of this mechanism is invalid. Multiple scattering produces a spectrum that is much harder than the single-scattering spectrum. As the Thomson optical depth of a power-law electron beam approaches unity, photon spawning commences at a high rate and physically invalidates the underlying electron distribution. The Compton upscattering model is therefore only valid over a narrow range of electron densities. An observational consequence of this model is the absence of the third cyclotron resonance. Resonant scattering produces gamma-rays that propagate nearly along the magnetic field. The resonant cross section of the third harmonic, which is strongly angle dependent, falls below the Compton continuum for these gamma rays. The observation of a third cyclotron resonance in a gamma-ray burst spectrum would eliminate resonant Compton scattering as a gamma-ray burst process.
Xue, Jin-Hua; Qian, Qiu-Mei; Wang, Yong-Sheng; Meng, Xia-Ling; Liu, Lu
2013-02-01
A novel method of resonance light scattering (RLS) was developed for the analysis of trace metallothioneins (MTs) in human urine. In a CH3COOH-CH3COONa buffer solution of pH 4.5, the formation of a complex between levofloxacin (LEV)-Pd and MTs led to enhance the RLS intensity of the system, and the enhanced RLS intensity at 468 nm was proportional to the concentration of MTs in the range of 0.059-22.4 μg mL-1. The linear regression equation was ΔI = 127.5 ρ (μg mL-1)-88.02 with a correlation coefficient of 0.9992, and the detection limit of 17.8 ng mL-1. The relative standard deviation and the average recovery were 3.8-5.4% (n = 11) and 92.15%, respectively. The proposed method is convenient, reliable and sensitive, and has been used successfully for the determination of trace MTs in human urine samples.
Shamsudeen, Riyaj; Yu, Kai; Farooq, Tariq
2013-01-01
Expert Oracle RAC 12c is a hands-on book helping you understand and implement Oracle Real Application Clusters (RAC), and to reduce the total-cost-of-ownership (TCO) of a RAC database. As a seasoned professional, you are probably aware of the importance of understanding the technical details behind the RAC stack. This book provides deep understanding of RAC concepts and implementation details that you can apply toward your day-to-day operational practices. You'll be guided in troubleshooting and avoiding trouble in your installation. Successful RAC operation hinges upon a fast-performing netwo
Angular dependence of resonant inelastic x-ray scattering : A spherical tensor expansion
Juhin, Amelie; Brouder, Christian; de Groot, Frank
2014-01-01
A spherical tensor expansion is carried out to express the resonant inelastic scattering cross-section as a sum of products of fundamental spectra with tensors involving wavevectors and polarization vectors of incident and scattered photons. The expression presented in this paper differs from that o
Resonant inelastic X-ray scattering of liquid water
Highlights: ► Two peaks are observed in the lone pair region of the XES spectrum of water assigned to tetrahedral and distorted hydrogen bonding configurations. ► The isotope effect observed as different relative peak heights is due to spectral line shape differences. ► The two different hydrogen bonding environments can be related to local structures mimicking either low density water or high density water. -- Abstract: We review recent studies using resonant inelastic X-ray scattering (RIXS) or also here denoted X-ray emission spectroscopy (XES) on liquid water and the assignment of the two sharp peaks in the lone-pair region. Using the excitation energy dependence we connect the two peaks to specific features in the X-ray absorption (XAS) spectrum which have independently been assigned to molecules in tetrahedral or distorted configurations. The polarization dependence shows that both peaks are of 1b1 origin supporting an interpretation in terms of two structural species, tetrahedral or disordered, which is furthermore consistent with the temperature-dependence of the two peaks. We discuss effects of life-time vibrational interference and how this affects the two components differently and also leads to differences in the relative peak heights for H2O and D2O. We show furthermore that the inherent structure in molecular dynamics simulations contain the structural bimodality suggested by XES, but this is smeared out in the real structure when temperature is included. We present a discussion around alternative interpretations suggesting that the origin of the two peaks is related to ultrafast dissociation and show evidence that such a model is inconsistent with several experimental observations and theoretical concepts. We conclude that the peaks reflect a temperature-dependent balance in fluctuations between tetrahedral and disordered structures in the liquid. This is well-aligned with theories of water under supercooled conditions and higher pressures
Experimental evidence for dual diffractive resonances in pion-nucleus scattering
Experimental data on the pion-nucleus total cross sections are analysed in terms of the dual diffractive resonance (DDR) mechanism. The DDR predictions are found to agree well with the actual experimental data in the region corresponding to the Δ(1236) resonance in elementary πN scattering. (orig.)
Sub-Coulomb fusion excitation function for 12 C + 12 C
Fusion excitation functions are measured for the o, p and n evaporation channels in the fusion of the 12 C + 12 C system at center of mass energies between 4.5 and 6.5 MeV, with energy steps of 75 keV. The X-ray technique is used with a new absolute normalization method which is independent of charge collection and allows at the same time to monitor the Carbon buildup on the target. Good agreement is obtained with absolute cross section values previously measured using particle detection techniques, but smaller energy steps are used in the present experiment. As in previous works much structure is seen in the excitation function which is consistent with the positions of resonances reported in the literature for this system. (Author)
Triple-resonant Brillouin light scattering in magneto-optical cavities
Haigh, J A; Ramsay, A J; Ferguson, A J
2016-01-01
An enhancement in Brillouin light scattering of optical photons with magnons is demonstrated in magneto-optical whispering gallery mode resonators tuned to a triple resonance point. This occurs when both the input and output optical modes are resonant with those of the whispering gallery resonator, with a separation given by the ferromagnetic resonance (FMR) frequency. The identification and excitation of specific optical modes allows us to gain a clear understanding of the mode-matching conditions. A selection rule due to wavevector matching leads to an intrinsic single-sideband excitation. Strong suppression of one sideband is essential for one-to-one frequency mapping in coherent optical-to-microwave conversion.
Resonant Bound-Free Contributions to Thomson Scattering of X-rays by Warm Dense Matter
Johnson, W R; Cheng, K T
2013-01-01
Recent calculations [Nilsen et al. arXiv:1212.5972] predict that contributions to the scattered photon spectrum from 3s and 3p bound states in chromium (Z=24) at metallic density and T=12 eV resonate below the respective bound-state thresholds. These resonances are shown to be closely related to continuum lowering, where 3d bound states in the free atom dissolve into a resonant l=2 partial wave in the continuum. The resulting d-state resonance dominates contributions to the bound-free dynamic structure function, leading to the predicted resonances in the scattered X-ray spectrum. Similar resonant features are shown to occur in all elements in the periodic table between Ca and Mn (20 <= Z <= 25).
Effects of up scattering by heavy nuclides on Doppler changes of resonance adsorption
A procedure for handling energy changes of neutrons accurately in a Monte Carlo code, within the large resonances of heavy nuclides, is discussed. The procedure has been applied in the MCNP program to sample problem which relates to PWR unit cells. The statistical uncertainties in estimating the effect of neutron up scattering in pronounced resonances of heavy nuclides on resonance absorption rates, and their temperature changes, are discussed. (author). 10 refs