The effect of including tensor forces in nucleon-nucleon interaction on three-nucleon binding energy
International Nuclear Information System (INIS)
Osman, A.; Ramadan, S.
1986-01-01
Separable two-body interactions are used in considering the three-nucleon problem. The nucleon-nucleon potentials are taken to include attraction and repulsion as well as tensor forces. The separable approximation is used in order to investigate the effect of the tensor forces. The separable expansion is introduced in the three-nucleon problem, by which the Faddeev equations are reduced to a well-behaved set of coupled integral equations. Numerical calculations are carried out for the obtained integral equations using potential functions of the Yamaguchi, Gaussian, Takabin, Mongan and Reid forms. The present calculated values of the binding energies of the 3 H and 3 He nuclei are in good agreement with the experimental values. The effect of including the tensor forces in the nucleon-nucleon interactions is found to improve the three-nucleon binding energy by about 4.490% to 8.324%. 37 refs., 2 tabs. (author)
International Nuclear Information System (INIS)
Osman, A.; Ramadan, S.
1989-01-01
Faddeev equations of bound three-nucleon system are presented as a set of integral equations. To solve them, a sutable form of the nucleon-nucleon interactions is used: with the exchange of a scalar meson, a pseudoscalar meson and a massless vector meson. Higher orders of these different meson exchanges in the nucleon-nucleon interactions have been taken into account. With these nuclear forces and nucleon-nucleon interactions, the three-nucleon binding energy is calculated by solving the Faddeev integral equations. The obtained value of the three-nucleon binding energy is 8.441 MeV. The inclusion of the higher order terms of the different meson exchange in the nuclear nucleon-nucleon interaction is found to affect the three-nucleon binding by about 3.92%. 3 figs., 16 refs
Jets in high energy nucleon-nucleon collisions
International Nuclear Information System (INIS)
Strugalski, Z.
1982-01-01
From the experimental studies of high-energy hardon-nucleon and nucleon-nucleon collisions, by means of nuclear targets applied as detectors, it follows that particles are produced via intermediate objects created first in a 2 → 2 type endoergic reaction. These objects, called generons, decay in flight into finally observed particles and resonances after their lifetime tausub(g) > or approximately 10 - 22 s. The jet structure of the outcome in nucleon-nucleon collisions is a simple and indispensable consequence of this particle production mechanism. The picture of the jet structure in the collision outcome observed in the CMS of the colliding nucleons depends on the energy of these nUcleons. New particle production scheme is proposed, which can be tested experimentally; corresponding simple relations between characteristics of colliding nucleons and of produced jets are proposed for a testing
International Nuclear Information System (INIS)
Hippchen, T.
1985-12-01
In a first part, nuclear matter calculations have been performed in the Dirac-Brueckner approach using a) a nucleon-nucleon potential of one-boson-exchange (OBE) type and b) a more realistic interaction in which the fictitious σ-exchange of the OBE-model is replaced by explicit 2π- and πρ-exchange diagrams. Both potential models yield the correct empirical binding energy and saturation density. It turns out that the total sum of relativistic effects caused by the emplicit 2 π- and πρ-exchanges is comparable to those due to σ-exchange. In a second part, the nuclear quasiparticle interaction, i.e. the Landau parameters, have been calculated in the central (F), isospin (F'), spin (G) and spin-isospin (G') channel, in an analogous way. Compared to nonrelativistic calculations (including conventional medium corrections like Pauli and dispersion effects), a strong improvement has been found, especially in the F- and G-channel. Finally, the influence of A 1 -exchange is studied, in NN scattering and in nuclear matter. It turns out that, after a suitable and necessary readjustment of some meson parameters, its role is negligibly small. (orig.)
Off-energy-shell variations of two-nucleon transition matrix and three-nucleon problem
International Nuclear Information System (INIS)
Stingl, M.; Sauer, P.U.
1975-01-01
For a schematic three-nucleon problem, approximate analytic expressions are derived for the functional derivatives of measurable three-particle quantities with respect to off-shell variations of the triplet-s two-nucleon transition matrix. Those quantities include neutron-deuteron scattering lengths, trinucleon binding energies, and the 3 He charge form-factor minimum; correlations between off-shell changes in the latter two are discussed. An indication is given how results of this kind may be to decide whether or not a given set of discrepancies between calculated and experimental three-nucleon observables can be reconciled in terms of off-shell variations of a nonretarded hermitean two-nucleon interaction. The treatment is not restricted to special classes of phase-shift equivalent potentials or phase-shift preserving transformations but instead makes use of a systematic parameterization of off-shell variations in terms of symmetric rational approximants of increasing order
P-shell hyperon binding energies
International Nuclear Information System (INIS)
Koetsier, D.; Amos, K.
1991-01-01
A shell model for lambda hypernuclei has been used to determine the binding energy of the hyperon in nuclei throughout the p shell. Conventional (Cohen and Kurath) potential energies for nucleon-nucleon interactions were used with hyperon-nucleon interactions taken from Nijmegen one boson exchange potentials. The hyperon binding energies calculated from these potentials compare well with measured values. 7 refs., 2 figs
Nucleon-nucleon correlations and the Coulomb Displacement Energy
International Nuclear Information System (INIS)
Van Neck, D.; Waroquier, M.; Heyde, K.
1997-01-01
Coulomb Displacement Energies (CDE) are accurately known for a wide range of nuclear masses. Assuming isospin independence in the nuclear Hamiltonian, the CDE can in first instance be interpreted as the Coulomb interaction energy between the density of the excess neutrons and the proton charge density in the parent nucleus. However, when using reasonable mean-field models for the proton and neutron density one underestimates the CDE by about 8% on average. This discrepancy is known as the Nolen-Schiffer anomaly, and various explanations have been put forward in the past. In this work the role of nucleon-nucleon correlations are re-examined. Calculations for the pair density functions in various nuclei are presented. Preliminary results suggest that the modifications to the mean-field pair density functions cause an enhancement of the CDE in the order of 4%, which is rather A-independent. (author)
Pion photoproduction in nucleons at low energies
International Nuclear Information System (INIS)
Carvalho, F.A.B.R. de.
1983-01-01
A new semiphenomenological analysis of the multipoles for pion photoproduction from nucleons, in the region of the first π-N resonance is presented. Through an energy dependent model, multipoles with isospin 1/2 and 3/2 and total angular momentum J [pt
Low-energy pion double charge exchange and nucleon-nucleon correlations in nuclei
International Nuclear Information System (INIS)
Leitch, M.J.
1989-01-01
Recent measurements of pion double-charge exchange (DCX) at energies 20 to 70 MeV are providing a new means for studying nucleon-nucleon correlations in nuclei. At these energies the nucleus is relatively transparent, allowing simpler theoretical models to be used in interpreting the data and leading to a clearer picture. Also the contribution to DCX of sequential charge-exchange scattering through the intermediate analog state is suppressed near 50 MeV and transitions through non-analog intermediate states become very important. Recent theoretical studies by several groups have shown that while transitions through the analog route involve relatively long nucleon-nucleon distances, those through non-analog intermediate states obtain nearly half their strength from nucleon pairs with less than 1 fermi separation. Thus DCX near 50 MeV is an excellent way to study short-range nucleon-nucleon correlations. 31 refs., 29 figs., 4 tabs
Low-energy pion-nucleon scattering
International Nuclear Information System (INIS)
Gibbs, W.R.; Ai, L.; Kaufmann, W.B.
1998-01-01
An analysis of low-energy charged pion-nucleon data from recent π ± p experiments is presented. From the scattering lengths and the Goldberger-Miyazawa-Oehme (GMO) sum rule we find a value of the pion-nucleon coupling constant of f 2 =0.0756±0.0007. We also find, contrary to most previous analyses, that the scattering volumes for the P 31 and P 13 partial waves are equal, within errors, corresponding to a symmetry found in the Hamiltonian of many theories. For the potential models used, the amplitudes are extrapolated into the subthreshold region to estimate the value of the Σ term. Off-shell amplitudes are also provided. copyright 1998 The American Physical Society
Chiral symmetry and nucleon structure: Low energy aspects
International Nuclear Information System (INIS)
Weise, W.
1989-01-01
The symmetries and currents of QCD at low energy and long wavelength are realized in the form of mesons, rather than quarks and gluons. In this talk I summarize the merits, but also the limits, of chiral non-linear meson theories and their soliton solutions, in descriptions of nucleon structure and the nucleon-nucleon interaction. (orig.)
Comparative study of various methods of primary energy estimation in nucleon-nucleon interactions
International Nuclear Information System (INIS)
Goyal, D.P.; Yugindro Singh, K.; Singh, S.
1986-01-01
The various available methods for the estimation of primary energy in nucleon-nucleon interactions have been examined by using the experimental data on angular distributions of shower particles from p-N interactions at two accelerator energies, 67 and 400 GeV. Three different groups of shower particle multiplicities have been considered for interactions at both energies. It is found that the different methods give quite different estimates of primary energy. Moreover, each method is found to give different values of energy according to the choice of multiplicity groups. It is concluded that the E ch method is relatively the better method among all the methods available, and that within this method, the consideration of the group of small multiplicities gives a much better result. The method also yields plausible estimates of inelasticity in high energy nucleon-nucleon interactions. (orig.)
High energy nucleonic component of cosmic rays at mountain altitudes
Stora, Raymond Félix
The diffusion equations describing the unidimensional propagation of .the high energy nucleonic component of cosmic rays throughout the atmosphere are sol"V'ed under two assumptions: (l) The nucleon-nucleon collisions are described according to Fermi's therlnOdynamical model involving completely inelastic pion and.nucleon-antinucleon pair production. (2) A somewhat opposite assumption is made assuming partially elastic collisions without nucleon-anti.nucleon pair production. Due to the present inaccuracy of experiments, we are able to derive only tentati v.e conclusions. The values computed under both hypotheses for the absorption mean free path and the charged to neutral particles ratio are found in acceptable ranges when compared to experimental data. The diffeential energy spectrum at a given depth is always found steeper than the primary, and steeper than indicated by experimental values if the primary is taken proportional to the 2.5 inverse power of energy.
Nucleon self-energy in the relativistic Brueckner theory
Energy Technology Data Exchange (ETDEWEB)
Waindzoch, T; Fuchs, C; Faessler, A [Inst. fuer Theoretische Physik, Univ. Tuebingen (Germany)
1998-06-01
The self-energy of the nucleon in nuclear matter is calculated in the relativistic Brueckner theory. We solve the Thompson equation for the two nucleon scattering in the medium using different Bonn potentials. The self-energy has a rather strong momentum dependence while the equation of state compares well with previous calculations. (orig.)
Nucleon self-energy in the relativistic Brueckner theory
International Nuclear Information System (INIS)
Waindzoch, T.; Fuchs, C.; Faessler, A.
1998-01-01
The self-energy of the nucleon in nuclear matter is calculated in the relativistic Brueckner theory. We solve the Thompson equation for the two nucleon scattering in the medium using different Bonn potentials. The self-energy has a rather strong momentum dependence while the equation of state compares well with previous calculations. (orig.)
Lepton-nucleon scattering at high energies
International Nuclear Information System (INIS)
Buchmueller, W.
1993-12-01
Recent theoretical developments in the field of inelastic lepton-nucleon scattering are reviewed with emphasis on physics at HERA. Structure functions at small Bjorken-x are discussed in detail. Further topics are photoproduction of jets, the gluon densities in proton and photon, charm physics, electroweak processes and the search for new particles and interactions. (orig.)
Intermediate energy nucleon-deuteron scattering theory.
Wilson, J. W.
1973-01-01
Sloan's conclusion (1969) that terms of the multiple-scattering series beyond single scattering contribute only to S- and P-wave amplitudes in an S-wave separable model is examined. A comparison of experiments with the calculation at 146 MeV shows that the conclusion is valid in nucleon-deuteron scattering applications.
Nucleon-deuteron low energy parameters
International Nuclear Information System (INIS)
Zankel, H.; Mathelitsch, L.
1983-01-01
Momentum space Fadeev equations are solved for nucleon-deuteron scattering and effective range parameters are calculated. A reverse trend is found in the two spin states by 4 asub(nd) 4 asub(pd) and 2 asub(pd) 2 asub(nd) which is in agreement with a configuration space calculation, but in conflict with all existing experiments. The Coulomb contributions to the effective range are small in quartet but sizeable in doublet scattering. (Author)
Potential energy surfaces for nucleon exchanging in dinuclear systems
International Nuclear Information System (INIS)
Li Jianfeng; Xu Hushan; Li Wenfei; Zuo Wei; Li Junqing; Wang Nan; Zhao Enguang
2003-01-01
The experimental measurements have provided the evidence that the suppression of fusion cross-section caused by quasi-fission is very important for the synthesis of super-heavy nuclei by heavy ion collisions. The potential energy surface due to the nucleon transfer in the collision process is the driven potential, which governs the nucleon transfer, so that governs the competition between the fusion and quasi-fission. The dinuclear system potential energy surface also gives the information about the optimum projectile-target combination, as well as the optimum excitation energy for the synthesis of super-heavy nuclei by heavy ion collisions
International Nuclear Information System (INIS)
Yakosawa, A.
1977-01-01
Results of various asymmetry measurements in nucleon-nucleon scattering with polarized beams and targets at ZGS energies are presented. A possible direct-channel resonance in the pp system is discussed. Most of the discussion above ZGS energies are aimed at future measurements
International Nuclear Information System (INIS)
Burleson, G.R.
1987-01-01
We are applying for a three-year grant from the US Department of Energy to New Mexico State University to continue its support of our work on experimental studies of nucleon-nucleon and pion-nucleus interactions at intermediate energies, which has been carried out in collaboration with groups from various laboratories and universities. The nucleon-nucleon work is aimed at making measurements that will contribute to a determination of the isospin-zero amplitudes, as well as continuing our investigations of evidence for dibaryon resonances. It is based at the LAMPF accelerator in Los Alamos, New Mexico. Current and planned experiments include measurements of total cross-section differences in pure spin states and of spin parameters in neutron-proton scattering. The pion-nucleus work is aimed at improving our understanding both of the nature of the pion-nucleus interaction and of nuclear structure. It consists of two programs, one based at LAMPF and one based principally at the SIN laboratory in Switzerland. The LAMPF-based work involves studies of large-angle scattering, double-charge-exchange scattering, including measurements at a new energy range above 300 MeV, and a new program of experiments with polarized nuclear targets. The SIN-based work involves studies of quasielastic scattering and absorption, including experiments with a new large-acceptance detector system planned for construction there. We are requesting support to continue the LAMPF-based work at its current level and to expand the SIN-based work to allow for increased involvement in experiments with the new detector system. 57 refs
Pion-nucleon interactions in low energy region
International Nuclear Information System (INIS)
Hiroshige, Noboru; Tsujimura, Tadakuni.
1977-01-01
Pion-nucleon interactions in low energy region (below 320 MeV in kinetic energy) are investigated on the basis of the one-particle-exchange model. The model is directly compared with the experimental data, i.e., differential cross sections and recoil nucleon polarizations, since phase shifts have not been uniquely determined. It is shown that these experimental data can be well reproduced by taking account of N (nucleon), Δ 33 , N 11 , N 13 , rho, f 0 and S (scalar meson) in the intermediate state. Some comments are given on the coupling constants which are determined so as to minimize chi-squared value (chi 2 ). Our predicted phase shifts for s-, p- and d-waves are also compared with other authors'. (auth.)
Nucleon-nucleon optical model for energies to 3 GeV
International Nuclear Information System (INIS)
Funk, A.; Von Geramb, H.V.; University of Melbourne, VIC; Amos, K.A.
2001-01-01
Several nucleon-nucleon potentials, Paris, Nijmegen, Argonne, and those derived by quantum inversion, which describe the NN interaction for T Lab ≤ 300 MeV are extended in their range of application as NN optical models. Extensions are made in r-space using complex separable potentials definable with a wide range of form factor options including those of boundary condition models. We use the latest phase shift analyses SP00 (FA00, WI00) of Arndt et al. from 300 MeV to 3 GeV to determine these extensions. The imaginary parts of the optical model interactions account for loss of flux into direct or resonant production processes. The optical potential approach is of particular value as it permits one to visualize fusion, and subsequent fission, of nucleons when T Lab > 2 GeV. We do so by calculating the scattering wave functions to specify the energy and radial dependences of flux losses and of probability distributions. Furthermore, half-off the energy shell t-matrices are presented as they are readily deduced with this approach. Such t-matrices are required for studies of few- and many-body nuclear reactions
Extrapolations of nuclear binding energies from new linear mass relations
DEFF Research Database (Denmark)
Hove, D.; Jensen, A. S.; Riisager, K.
2013-01-01
We present a method to extrapolate nuclear binding energies from known values for neighboring nuclei. We select four specific mass relations constructed to eliminate smooth variation of the binding energy as function nucleon numbers. The fast odd-even variations are avoided by comparing nuclei...
Theoretical interpretation of medium energy nucleon nucleus inelastic scattering
International Nuclear Information System (INIS)
Lagrange, Christian
1970-06-01
A theoretical study is made of the medium energy nucleon-nucleus inelastic scattering (direct interaction), by applying the distorted wave Born approximation such as can be deduced from the paired equation method. It is applied to the interpretation of the inelastic scattering of 12 MeV protons by 63 Cu; this leads us to make use of different sets of wave functions to describe the various states of the target nucleus. We analyze the nature of these states and the shape of the nucleon-nucleus interaction potential, and we compare the results with those obtained from other theoretical and experimental work. (author) [fr
Experimental studies of nucleon-nucleon and pion-nucleus interactions at intermediate energies
International Nuclear Information System (INIS)
1990-01-01
This report summarizes the work on experimental research in intermediate energy nuclear and particle physics carried out by New Mexico State University in 1988--91. Most of these studies have involved investigations of neutron-proton and pion-nucleus interactions. The neutron-proton research is part of a program of studies of interactions between polarized nucleons that we have been involved with for more than ten years. Its purpose has been to help complete the determination of the full set of ten complex nucleon-nucleon amplitudes at energies up to 800 MeV, as well as to continue investigating the possibility of the existence of dibaryon resonances. The give complex isospin-one amplitudes have been fairly well determined, partly as a result of this work. Our work in this period has involved measurements and analysis of data on elastic scattering and total cross sections for polarized neutrons on polarized protons. The pion-nucleus research continues our studies of this interaction in regions where it has not been well explored. One set of experiments includes studies of pion elastic and double-charge-exchange scattering at energies between 300 and 550 MeV, where our data is unique. Another involves elastic and single-charge-exchange scattering of pions from polarized nuclear targets, a new field of research which will give the first extensive set of information on spin-dependent pion-nucleus amplitudes. Still another involves the first set of detailed studies of the kinematic correlations among particles emitted following pion absorption in nuclei
International Nuclear Information System (INIS)
1988-01-01
This report summarizes the work on experimental research in intermediate energy nuclear and particle physics carried out by New Mexico State University in 1988 under a grant from the US Department of Energy. The nucleon-nucleon research has involved studies of interactions between polarized neutrons and polarized protons. Its purpose is to help complete the determination of the nucleon-nucleon amplitudes at energies up to 800 MeV, as part of a program currently in progress at LAMPF, as well as to investigate the possibility of the existence of dibaryon resonances. The pion-nucleus research involves studies of this interaction in regions where it has not been adequately explored. These include experiments on elastic and double charge exchange scattering at energies above the /Delta/(1232) resonance, interactions with polarized nuclear targets, and investigations of pion absorption using a detector covering nearly the full solid angle region. 21 refs., 4 figs
Energy Technology Data Exchange (ETDEWEB)
Henley, E M [Washington Univ., Seattle (USA). Dept. of Physics; Wolfenstein, L [Carnegie-Mellon Univ., Pittsburgh, Pa. (USA). Dept. of Physics
1978-05-15
The low-energy scattering of nucleons by /sup 2/H, /sup 3/He and /sup 4/He is analyzed for parity nonconserving effects. The asymmetry in the total cross section of longitudinally polarized projectiles is formulated in terms of the optical theorem and a distorted-wave Born approximation. For two nucleons at low energies it is only necessary to consider l = 0 to l = 1 matrix elements of the weak nucleon-nucleon potential. The asymmetries in the scattering from nuclear targets are related to the parameters of an effective weak nucleon-nucleon potential, so that they may be used to help differentiate between various proposed theoretical potentials.
Current status of high energy nucleon-meson transport code
Energy Technology Data Exchange (ETDEWEB)
Takada, Hiroshi; Sasa, Toshinobu [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment
1998-03-01
Current status of design code of accelerator (NMTC/JAERI code), outline of physical model and evaluation of accuracy of code were reported. To evaluate the nuclear performance of accelerator and strong spallation neutron origin, the nuclear reaction between high energy proton and target nuclide and behaviors of various produced particles are necessary. The nuclear design of spallation neutron system used a calculation code system connected the high energy nucleon{center_dot}meson transport code and the neutron{center_dot}photon transport code. NMTC/JAERI is described by the particle evaporation process under consideration of competition reaction of intranuclear cascade and fission process. Particle transport calculation was carried out for proton, neutron, {pi}- and {mu}-meson. To verify and improve accuracy of high energy nucleon-meson transport code, data of spallation and spallation neutron fragment by the integral experiment were collected. (S.Y.)
High energy lepton-nucleon scattering
International Nuclear Information System (INIS)
Sciulli, F.
1982-01-01
The author summarizes the general expressions expected for neutrino scattering, and the formula for the electromagnetic process which is involved for minor scattering. He discusses the complications of quark binding and the historical development of fits from deep inelastic data. He also evaluates the signifigance of the results gained from the data, concluding his discussion by asking basic questions about the tests of the quark model and suggesting that there is still much to be learned about inelastic scattering, that more precision is necessary. The author is hopeful that the work now being conducted on the CFRR data will help solve some of the discrepancy
Pi-nucleon phenomenology at high energies
International Nuclear Information System (INIS)
Kogitz, S.
1973-01-01
A brief introduction to the phenomenology of strong interactions at high energy is presented. This includes discussion of the topics including absorption, finite energy sum rules, and duality. The application of these ideas to two-particle inelastic reactions is examined. (author)
Pion nucleon interaction at low energy
International Nuclear Information System (INIS)
Banerjee, M.K.
1979-03-01
A theory of the πN interaction at low energy is described. An analogy is made with an unusual approach to potential scattering theory. Phase shifts, cross sections, and scattering amplitudes and lengths are calculated. 28 references
Low energy pion--nucleon and pion--deuteron interactions
International Nuclear Information System (INIS)
Burman, R.L.
1975-01-01
This survey concentrates upon current experiments in the fields of pion-nucleon and pion-deuteron interactions, for low-energy incident pions--below 300 MeV. The discussion is restricted to very recent work. The topics to be covered are: π +- p → π +- p, Elastic Scattering; π +- p → π +- pγ, Bremsstrahlung; π + d → pp, Absorption; π d → π + d, Elastic Scattering; and π + d → π + pn, Breakup. (14 figures) (U.S.)
Low energy peripheral scaling in nucleon-nucleon scattering and uncertainty quantification
Ruiz Simo, I.; Amaro, J. E.; Ruiz Arriola, E.; Navarro Pérez, R.
2018-03-01
We analyze the peripheral structure of the nucleon-nucleon interaction for LAB energies below 350 MeV. To this end we transform the scattering matrix into the impact parameter representation by analyzing the scaled phase shifts (L + 1/2) δ JLS (p) and the scaled mixing parameters (L + 1/2)ɛ JLS (p) in terms of the impact parameter b = (L + 1/2)/p. According to the eikonal approximation, at large angular momentum L these functions should become an universal function of b, independent on L. This allows to discuss in a rather transparent way the role of statistical and systematic uncertainties in the different long range components of the two-body potential. Implications for peripheral waves obtained in chiral perturbation theory interactions to fifth order (N5LO) or from the large body of NN data considered in the SAID partial wave analysis are also drawn from comparing them with other phenomenological high-quality interactions, constructed to fit scattering data as well. We find that both N5LO and SAID peripheral waves disagree more than 5σ with the Granada-2013 statistical analysis, more than 2σ with the 6 statistically equivalent potentials fitting the Granada-2013 database and about 1σ with the historical set of 13 high-quality potentials developed since the 1993 Nijmegen analysis.
Energy dissipation process for 100-MeV protons and the nucleon-nucleon interactions in nuclei
International Nuclear Information System (INIS)
Cowley, A.A.; Chang, C.C.; Holmgren, H.D.; Silk, J.D.; Hendrie, D.L.; Koontz, R.W.; Roos, P.G.; Samanta, C.; Wu, J.R.
1980-01-01
Coincidence studies of two protons emitted from p+ 58 Ni at 100 MeV have been carried out. The proton spectra in coincidence with scattered protons suffering an average energy loss of 60 MeV are similar to those resulting from 60-MeV incident protons. This suggests that the initial interaction of the incident proton is with a bound nucleon and that one or both of these nucleons are emitted or initiates a cascade leading to more complex states
Nucleon charge-exchange reactions at intermediate energy
International Nuclear Information System (INIS)
Alford, W.P.; Spicer, B.M.
1997-01-01
An historical review of the development of ideas pertaining to Gamow-Teller giant resonances is given, and a description of the emergence of techniques for the study of charge exchange reactions - particularly the technical advances which yielded the recent volume of new date. The present status of charge exchange reactions is reviewed and assessed. Evidence is presented from the 14 C(p,n) reaction for the dominance of the spin-isospin component of the nucleon-nucleon interaction in intermediate energy reactions. In (p,n) reactions the Gamow-Teller giant resonance dominates the spectra, with higher multipoles contributing. By contrast, in (n,p) reactions in the heavier nuclei, the Gamow-Teller transitions are substantially Pauli-blocked and the spin dipole resonance dominates, with contributions from higher multipoles. Discussions of the multipole decomposition process, used to obtain from the data the contributions of the different multipoles, and the contributions of the multipoles, are given
Symmetry energy of nucleonic matter with tensor correlations
Hen, Or; Li, Bao-An; Guo, Wen-Jun; Weinstein, L. B.; Piasetzky, Eli
2015-02-01
The nuclear symmetry energy (Esym(ρ ) ) is a vital ingredient of our understanding of many processes, from heavy-ion collisions to neutron stars structure. While the total nuclear symmetry energy at nuclear saturation density (ρ0) is relatively well determined, its value at supranuclear densities is not. The latter can be better constrained by separately examining its kinetic and potential terms and their density dependencies. The kinetic term of the symmetry energy, Esymkin(ρ0) , equals the difference in the per-nucleon kinetic energy between pure neutron matter (PNM) and symmetric nuclear matter (SNM), often calculated using a simple Fermi gas model. However, experiments show that tensor force induced short-range correlations (SRC) between proton-neutron pairs shift nucleons to high momentum in SNM, where there are equal numbers of neutrons and protons, but have almost no effect in PNM. We present an approximate analytical expression for Esymkin(ρ0) of correlated nucleonic matter. In our model, Esymkin(ρ0) =-10 MeV, which differs significantly from +12.5 MeV for the widely-used free Fermi gas model. This result is consistent with our analysis of recent data on the free proton-to-neutron ratios measured in intermediate energy nucleus-nucleus collisions as well as with microscopic many-body calculations, and previous phenomenological extractions. We then use our calculated Esymkin(ρ ) in combination with the known total symmetry energy and its density dependence at saturation density to constrain the value and density dependence of the potential part and to extrapolate the total symmetry energy to supranuclear densities.
International Nuclear Information System (INIS)
McClelland, J.B.; Aas, B.; Azizi, A.
1982-01-01
A complete measurement of the polarization transfer observables has been made for the first time in the (p,p') reaction at intermediate energies. Measurements are reported for the 12 C(p,p') 12 C reaction to the 1 + , T = 0(12.71 MeV) and 1 + , T = 1(15.11 MeV) states at 500 MeV at laboratory scattering angles of 3.5 0 , 5.5 0 , 7.5 0 , and 12.0 0 . Linear combinations of these observables are shown to exhibit a very selective dependence on the isoscalar and isovector spin-dependent components of the nucleon-nucleon interaction. To the extent of the validity of the single collision approximation, these amplitudes are compared directly to the free nucleon-nucleon amplitudes at small momentum transfers
First calculation of the deuteron binding energy
International Nuclear Information System (INIS)
Schaegger, B.
2012-01-01
No universal constant characterizing the nuclear force has yet been found as for gravity and electromagnetism. The neutron is globally neutral with a zero net charge. The charges contained in a neutron may be separated by the electric field of a nearby proton and therefore being attracted by electrostatic induction in the same way as a rubbed plastic pen attracts small pieces of paper. There is also a magnetic force that may repel the nucleons like magnets in the proper relative orientation. In the deuteron, the heavy hydrogen nucleus, the induced electrostatic attraction is equilibrated by the magnetic repulsion between the opposite and colinear moments of the nucleons. Equilibrium is calculated by minimizing the electromagnetic interaction potential, giving a binding energy of 1.6 MeV, not much lower than the experimental value, 2.2 MeV. No fitting parameter is used: it is a true ab initio calculation
Theoretical aspects of high energy elastic nucleon scattering
Kundrat, Vojtech; Lokajicek, Milos
2010-01-01
The eikonal model must be denoted as strongly preferable for the analysis of elastic high-energy hadron collisions. The given approach allows to derive corresponding impact parameter profiles that characterize important physical features of nucleon collisions, e.g., the range of different forces. The contemporary phenomenological analysis of experimental data is, however, not able to determine these profiles unambiguously, i.e., it cannot give the answer whether the elastic hadron collisions are more central or more peripheral than the inelastic ones. However, in the collisions of mass objects (like protons) the peripheral behavior of elastic collisions should be preferred.
Electron scattering from nucleons and deuterons at intermediate energies
International Nuclear Information System (INIS)
Burkert, V.
1985-04-01
Recent results from electron scattering of nucleons and deuterons are discussed. A tentative physics program for ELSA employing the polarized electron beams as well as the polarized nucleon and deuteron target facilities is outlined. (orig.)
Low-energy antikaon nucleon and nucleus interaction studies
Marton, Johann; Leannis Collaboration
2011-04-01
The antikaon (K-) interaction on nucleons and nuclei at low energy is neither simple nor well understood. Kaonic hydrogen is a very interesting case where the strong interaction of K- with the proton leads to an energy shift and a broadening of the 1s ground state. These two observables can be precisely studied with x-ray spectroscopy. The behavior at threshold is influenced strongly by the elusive Lambda(1405) resonance. In Europe the DAFNE electron-positron collider at Laboratori Nazionali di Frascati (LNF) provides an unique source of monoenergetic kaons emitted in the Phi meson decay. Recently the experiment SIDDHARTA on kaonic hydrogen and helium isotopes was successfully performed at LNF. A European network LEANNIS with an outreach to J-PARC in Japan was set up which is promoting the research on the antikaon interactions with nucleons and nuclei. This talk will give an overview of LEANNIS research tasks, the present status and an outlook to future perspectives. Financial support by the EU project HadronPhysics2 is gratefully acknowledged.
Mechanisms of photon scattering on nucleons at intermediate energies
International Nuclear Information System (INIS)
L'vov, A.I.
1992-01-01
The principal question for studies of photon scattering by nucleons and nuclei is the following: Can photon scattering say something new about the structure of these objects in comparisons with photo- and electroproduction investigations? There is a general reason to believe that it is indeed the case. The Hamiltonian of the electromagnetic interaction has, in general, a piece quadratic in the electromagnetic field (the so-called two-photon seagull) which is seen only in two-photon processes, such as Compton scattering. Although the longitudnal part of this seagull is constrained by the gauge invariance, its transverse part is decoupled from the electromagnetic current and cannot be found in photoabsorption processes. The seagull S μν depends on explicit degrees of freedom included into the Hamiltonian. E.g. the non-relativisitic Schroedinger equation has an effective seagull due to the kinetic energy (p - eA) 2 /2M. Its parent relativistic Dirac equation has no seagull at all but has the same low-energy consequences due to additional degrees of freedom (antiparticles). In low-energy nuclear physics, with explicit meson exchanges and meson clouds (i.e. internal polarizability of the nucleons). By explicitly including the mesons into the Hamiltonian one can remove part of the seagulls. Then the rest of them will be a signal for degrees of freedom invisible in photoabsorption at energies of the considered scale. Some seagulls are related with t-channel exchanges in Compton scattering. The π o -exchange is seen in γp-scattering but has no counterpart in photoproduction off the proton. Thus, a complementary study of one- and two-photon reactions provides a way to look in a region of higher energies where direct studies via photoproduction processes may be hard
Systematic studies of binding energy dependence of neutron-proton momentum correlation function
International Nuclear Information System (INIS)
Wei, Y B; Ma, Y G; Shen, W Q; Ma, G L; Wang, K; Cai, X Z; Zhong, C; Guo, W; Chen, J G; Fang, D Q; Tian, W D; Zhou, X F
2004-01-01
Hanbury Brown-Twiss (HBT) results of the neutron-proton correlation function have been systematically investigated for a series of nuclear reactions with light projectiles with the help of the isospin-dependent quantum molecular dynamics model. The relationship between the binding energy per nucleon of the projectiles and the strength of the neutron-proton HBT at small relative momentum has been obtained. Results show that neutron-proton HBT results are sensitive to the binding energy per nucleon
Mass distributions in nucleon-induced fission at intermediate energies
Duijvestijn, M C; Hambsch, F J
2001-01-01
Temperature-dependent fission barriers and fission-fragment mass distributions are calculated in the framework of the multimodal random neck-rupture model (MM-RNRM). It is shown how the distinction between the different fission modes disappears at higher excitation energies, due to the melting of shell effects. The fission-fragment mass yield calculations are coupled to the nuclear reaction code ALICE-91, which takes into account the competition between the other reaction channels and fission. With the combination of the temperature-dependent MM-RNRM and ALICE-91 nucleon-induced fission is investigated at energies between 10 and 200 MeV for nuclei varying from Au to Am. (72 refs).
Correlation between observable of four nucleon system in two-body model
International Nuclear Information System (INIS)
Barlette, V.E.
1988-01-01
The four nucleon system with effective nucleon-trinucleon interaction for s waves in states of spin Y = 0 and isospin Y = 0, is studied. The correlations between four nucleon systemn and scattering wavelength, binding energies and, coulomb energy of four nucleons are investigated by N/D method considering only the excited state. (M.C.K.)
Nucleon charge-exchange reactions at intermediate energy
Energy Technology Data Exchange (ETDEWEB)
Alford, W.P. [Western Ontario Univ., London, ON (Canada). Dept. of Physics]|[TRIUMF, Vancouver, BC (Canada); Spicer, B.M. [Melbourne Univ., Parkville, VIC (Australia). School of Physics
1997-12-31
An historical review of the development of ideas pertaining to Gamow-Teller giant resonances is given, and a description of the emergence of techniques for the study of charge exchange reactions - particularly the technical advances which yielded the recent volume of new date. The present status of charge exchange reactions is reviewed and assessed. Evidence is presented from the {sup 14}C(p,n) reaction for the dominance of the spin-isospin component of the nucleon-nucleon interaction in intermediate energy reactions. In (p,n) reactions the Gamow-Teller giant resonance dominates the spectra, with higher multipoles contributing. By contrast, in (n,p) reactions in the heavier nuclei, the Gamow-Teller transitions are substantially Pauli-blocked and the spin dipole resonance dominates, with contributions from higher multipoles. Discussions of the multipole decomposition process, used to obtain from the data the contributions of the different multipoles, and the contributions of the multipoles, are given. 226 refs., 19 figs.
Nucleon-nucleon momentum correlation function for light nuclei
International Nuclear Information System (INIS)
Ma, Y.G.; Cai, X.Z.; Chen, J.G.; Fang, D.Q.; Guo, W.; Liu, G.H.; Ma, C.W.; Ma, E.J.; Shen, W.Q.; Shi, Y.; Su, Q.M.; Tian, W.D.; Wang, H.W.; Wang, K.; Wei, Y.B.; Yan, T.Z.
2007-01-01
Nucleon-nucleon momentum correlation function have been presented for nuclear reactions with neutron-rich or proton-rich projectiles using a nuclear transport theory, namely Isospin-Dependent Quantum Molecular Dynamics model. The relationship between the binding energy of projectiles and the strength of proton-neutron correlation function at small relative momentum has been explored, while proton-proton correlation function shows its sensitivity to the proton density distribution. Those results show that nucleon-nucleon correlation function is useful to reflect some features of the neutron- or proton-halo nuclei and therefore provide a potential tool for the studies of radioactive beam physics
Energy Technology Data Exchange (ETDEWEB)
Guidal, Michel [Univ. of Paris, Orsay (France)
1996-12-13
One object of this thesis is to propose a model taking account of low transfer reaction mechanisms for a series of photoproduction reactions on nucleons for photon energies ≳4 GeV. If our comprehension of processes with low transfers is correct, then extrapolating our model in the domain of large transfers and the comparison with data supplied will give us information on the domains in energy and transfers from which an interpretation of reactions in terms of the "soft" process ceases to be valid. In the domain of large transfers, only one approach in terms of "hard" process can then explain the data. We are interested in electromagnetic photoproduction reactions because the probe, firstly, interacts with the target via an exact and well known mechanism (described by the QED theory) and also eliminates the interaction phenomena in the initial state. No probe is as well known as the photon. The extraction of reaction mechanisms, amplitudes and coupling constants match is made easier than in the case of hadronic probes. The energy domain E_{γ} >4 GeV studied is particularly interesting because it is from this energy of incident photons that can be expected to achieve large enough pulse transfers to hope for emergence of hard processes and therefore see the cessation of validity of interpretation of hadron models. Also, resonance effects are minor and do not interfere with our interpretations. Experimentally, this area is widely unexplored and the new generation accelerators of a large duty cycle (CEBAF, MAMI, ESRF, ELF, ...) combined with 4π detectors will allow to precisely measure low cross sections reactions of a large transfer. We first study pion photoproduction reactions on nucleon because they are the most experimentally accessible reactions and many data of high energy and low transfers exist. This will require strong constraints on the model parameters of the numerous analyses performed previously. Then we'll move on to kaon photoproduction
4He binding energy calculation including full tensor-force effects
Fonseca, A. C.
1989-09-01
The four-body equations of Alt, Grassberger, and Sandhas are solved in the version where the (2)+(2) subamplitudes are treated exactly by convolution, using one-term separable Yamaguchy nucleon-nucleon potentials in the 1S0 and 3S1-3D1 channels. The resulting jp=1/2+ and (3/2+ three-body subamplitudes are represented in a separable form using the energy-dependent pole expansion. Converged bound-state results are calculated for the first time using the full interaction, and are compared with those obtained from a simplified treatment of the tensor force. The Tjon line that correlates three-nucleon and four-nucleon binding energies is shown using different nucleon-nucleon potentials. In all calculations the Coulomb force has been neglected.
International Nuclear Information System (INIS)
Xu, Chang; Li, Bao-An; Chen, Lie-Wen
2014-01-01
In this contribution, we review the most important physics presented originally in our recent publications. Some new analyses, insights and perspectives are also provided. We showed recently that the symmetry energy E sym (ρ) and its density slope L(ρ) at an arbitrary density ρ can be expressed analytically in terms of the magnitude and momentum dependence of the single-nucleon potentials using the Hugenholtz-Van Hove (HVH) theorem. These relationships provide new insights about the fundamental physics governing the density dependence of nuclear symmetry energy. Using the isospin and momentum (k) dependent MDI interaction as an example, the contribution of different terms in the single-nucleon potential to the E sym (ρ) and L(ρ) are analyzed in detail at different densities. It is shown that the behavior of E sym is mainly determined by the first-order symmetry potential U sym,1 (ρ, k) of the single-nucleon potential. The density slope L(ρ) depends not only on the first-order symmetry potential U sym,1 (ρ, k) but also on the second-order one U sym,2 (ρ, k). Both the U sym,1 (ρ, k) and U sym,2 (ρ, k) at normal density ρ 0 are constrained by the isospin- and momentum-dependent nucleon optical potential extracted from the available nucleon-nucleus scattering data. The U sym,2 (ρ, k) especially at high density and momentum affects significantly the L(ρ), but it is theoretically poorly understood and currently there is almost no experimental constraints known. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Xu, Chang [Nanjing University, Department of Physics, Nanjing (China); Li, Bao-An [Texas A and M University-Commerce, Department of Physics and Astronomy, Commerce, Texas (United States); Chen, Lie-Wen [Shanghai Jiao Tong University, Department of Physics and Astronomy and Shanghai Key Laboratory for Particle Physics and Cosmology, Shanghai (China)
2014-02-15
In this contribution, we review the most important physics presented originally in our recent publications. Some new analyses, insights and perspectives are also provided. We showed recently that the symmetry energy E{sub sym} (ρ) and its density slope L(ρ) at an arbitrary density ρ can be expressed analytically in terms of the magnitude and momentum dependence of the single-nucleon potentials using the Hugenholtz-Van Hove (HVH) theorem. These relationships provide new insights about the fundamental physics governing the density dependence of nuclear symmetry energy. Using the isospin and momentum (k) dependent MDI interaction as an example, the contribution of different terms in the single-nucleon potential to the E{sub sym} (ρ) and L(ρ) are analyzed in detail at different densities. It is shown that the behavior of E{sub sym} is mainly determined by the first-order symmetry potential U{sub sym,1}(ρ, k) of the single-nucleon potential. The density slope L(ρ) depends not only on the first-order symmetry potential U{sub sym,1}(ρ, k) but also on the second-order one U{sub sym,2}(ρ, k). Both the U{sub sym,1}(ρ, k) and U{sub sym,2}(ρ, k) at normal density ρ {sub 0} are constrained by the isospin- and momentum-dependent nucleon optical potential extracted from the available nucleon-nucleus scattering data. The U{sub sym,2}(ρ, k) especially at high density and momentum affects significantly the L(ρ), but it is theoretically poorly understood and currently there is almost no experimental constraints known. (orig.)
Measurement of the nucleon structure function using high energy muons
International Nuclear Information System (INIS)
Meyers, P.D.
1983-12-01
We have measured the inclusive deep inelastic scattering of muons on nucleons in iron using beams of 93 and 215 GeV muons. To perform this measurement, we have built and operated the Multimuon Spectrometer (MMS) in the muon beam at Fermilab. The MMS is a magnetized iron target/spectrometer/calorimeter which provides 5.61 kg/cm 2 of target, 9% momentum resolution on scattered muons, and a direct measure of total hadronic energy with resolution sigma/sub nu/ = 1.4√nu(GeV). In the distributed target, the average beam energies at the interaction are 88.0 and 209 GeV. Using the known form of the radiatively-corrected electromagnetic cross section, we extract the structure function F 2 (x,Q 2 ) with a typical precision of 2% over the range 5 2 2 /c 2 . We compare our measurements to the predictions of lowest order quantum chromodynamics (QCD) and find a best fit value of the QCD scale parameter Λ/sub LO/ = 230 +- 40/sup stat/ +- 80/sup syst/ MeV/c, assuming R = 0 and without applying Fermi motion corrections. Comparing the cross sections at the two beam energies, we measure R = -0.06 +- 0.06/sup stat/ +- 0.11/sup syst/. Our measurements show qualitative agreement with QCD, but quantitative comparison is hampered by phenomenological uncertainties. The experimental situation is quite good, with substantial agreement between our measurements and those of others. 86 references
On the angular distribution of spectator nucleons in high-energy collisions with deuterium nuclei
International Nuclear Information System (INIS)
Bartke, J.
1975-01-01
Angular distributions of spectator nucleons in collisions of high-energy particles with deuterium nuclei are discussed in the framework of the impulse model. Comparison with experimental data shows that predictions following from this simple theoretical model are verified by experiment. Some general remarks on the study of angular distributions of spectator nucleons are given. (author)
Energy Technology Data Exchange (ETDEWEB)
Tornow, W.; Howell, C.R.; Alohali, M.; Chen, Z.P.; Felsher, P.D.; Hanly, J.M.; Walter, R.L.; Weisel, G. (Duke Univ., Durham, NC (USA). Dept. of Physics Triangle Universities Nuclear Lab., Durham, NC (USA)); Mertens, G. (Tuebingen Univ. (Germany, F.R.). Physikalisches Inst.); Slaus, I. (Institut Rudjer Boskovic, Zagreb (Yugoslavia)); Witala, H.; Gloeckle, W. (Bochum Univ. (Germany, F.R.). Inst. fuer Theoretische Physik 2)
1991-03-28
Data for the analyzing power A{sub y}({theta}) for the elastic scattering of neutrons from deuterons have been measured at 5.0, 6.5 and 8.5 MeV to an accuracy of +-0.0035. Surprisingly large differences have been observed at these low energies between the data and rigorous Faddeev calculations using the Paris and Bonn B nucleon-nucleon potentials. The A{sub y}({theta}) data provide a stringent test for our present understanding of the on-shell and off-shell {sup 3}P{sub 0,1,2} nucleon-nucleon interactions. (orig.).
Studies of high energy lepton-nucleon scattering
International Nuclear Information System (INIS)
Ingelman, G.
1982-05-01
The first part of this thesis is related to the problem of detecting charmed particles. A new technique for observing very short decay paths in nuclear emulsions is developed and applied on a sample of neutrino induced reactions. Techniques for producing thick pellicles of nuclear track emulsion are also developed. In the second part, phenomenological investigations of deep inelastic lepton-nucleon scattering are made. Monte Carlo computer programs, based on the parton model and perturbative QCD for the initial hard process and the Lund model for the following soft hadronization, are used to simulate these reactions and thereby obtain explicit results. Generally good agreement is found when comparing these with experimental data, thus supporting this basic framework. Predictions to test QCD are made. Transverse momentum properties are studied in detail, in particular effects from soft gluon emission. The properties of a model for baryon production, both from the target remnant and the colour force field, are discussed and the results found to agree with data. It is shown that, at the presently available energies, the observable energy flow is not due to QCD, but arises from the baryon production in the target fragmentation. In a model to explain the observed Λ polarization, a connection between the confinement of quarks and these polarization phenomena is suggested. (Auth.)
International Nuclear Information System (INIS)
Safronov, A.N.; Safronov, A.A.
2006-01-01
Full text: A nonperturbative character of QCD at low and intermediate energies generates serious mathematical difficulties in describing the dynamics of hadron-hadron interactions in terms quark-gluon degrees of freedom. Therefore much effort has gone in past years into developing QCD-motivated approaches that formulate the theory of strong interaction in terms of hadron degrees of freedom. The path-integral technique together with idea of spontaneous chiral-symmetry breaking leads to Effective Field Theory (EFT) [1]. Unfortunately EFT can be applied to description of hadron-hadron interactions only at very low energies. On the other hand, meson theories of nuclear forces have long since been used to describe the properties of nucleon systems and scattering processes. Now it is not quite clear, up to what distances the meson-exchange pattern of nuclear forces is valid. Recently the new relativistic approach to the problem of constructing effective hadron-hadron interaction operators has been proposed [2-4] on the basis of analytic S-matrix theory and Gelfand-Levitan-Marchenko-Martin methods for solving the inverse quantum scattering problem. In this approach effective potential is defined as a local operator in a partial-wave equation of the quasipotential type such that it generates on-shell relativistic (Feynman) scattering amplitude that has required discontinuities at dynamical cuts. The discontinuities of partial-wave amplitudes are determined by model-independent quantities (renormalized vertex constants and amplitudes of subprocesses involving on-mass-shell particles off the physical region) and can be calculated by methods of relativistic quantum field theory within various dynamical approaches. In particular, EFT can be used to calculate the discontinuities across dynamical-cut segments closest to the physical region. In [2-4] we have examined the basic features of the proposed approach. Attention has been given primarily to analyzing the new mechanism of
Low-energy analysis of the nucleon electromagnetic form factors
International Nuclear Information System (INIS)
Kubis, Bastian.; Meissner, Ulf-G.
2001-01-01
We analyze the electromagnetic form factors of the nucleon to fourth order in relativistic baryon chiral perturbation theory. We employ the recently proposed infrared regularization scheme and show that the convergence of the chiral expansion is improved as compared to the heavy-fermion approach. We also discuss the inclusion of vector mesons and obtain an accurate description of all four-nucleon form factors for momentum transfer squared up to Q 2 ≅0.4 GeV 2
Nucleon exchange and excitation energy division in damped collisions
International Nuclear Information System (INIS)
Viola, V.E.; Planeta, R.; Kwiatkowski, K.; Zhou, S.H.; Breuer, H.
1989-01-01
In this paper we will examine both the dependence of nucleon exchange on target-projectile properties and the question of temperature equilibration and heat partition during scission. Primary emphasis will be placed on the results of a recent study of the 74 Ge + 165 Ho system, which allows us to address these two questions simultaneously. The results can thus be directly compared with the predictions of the nucleon-exchange model. (author)
Theory of the low-energy pion-nucleon interaction
International Nuclear Information System (INIS)
Banerjee, M.K.; Cammarata, J.B.
1978-01-01
A once-subtracted form of the Low equation for the pion-nucleon scattering amplitude is derived, with partial conservation of axial-vector current used to define the amplitude when one pion is off the mass shell. The static approximation is not made and both the seagull terms and the antinucleon contribution (z graphs) are retained. The theory is applied to calculate the S-wave amplitudes in the elastic scattering region. Good agreement is found with the phase shift fits to the data when we use vertical-barg/sub π/(4M 2 ) vertical-bar = 11.69 and 25.5 MeV for the πN sigma commutator. The implications of this work for the analysis of low-energy elastic scattering of pions form nuclei are discussed. In particular, we point out how this work establishes the presence of a Laplacian term in the pion-nucleus optical potential with a magnitude that is fixed from the value of the sigma commutator
Isospin splitting of nucleon effective mass and symmetry energy in isotopic nuclear reactions
Guo, Ya-Fei; Chen, Peng-Hui; Niu, Fei; Zhang, Hong-Fei; Jin, Gen-Ming; Feng, Zhao-Qing
2017-10-01
Within an isospin and momentum dependent transport model, the dynamics of isospin particles (nucleons and light clusters) in Fermi-energy heavy-ion collisions are investigated for constraining the isospin splitting of nucleon effective mass and the symmetry energy at subsaturation densities. The impacts of the isoscalar and isovector parts of the momentum dependent interaction on the emissions of isospin particles are explored, i.e., the mass splittings of and (). The single and double neutron to proton ratios of free nucleons and light particles are thoroughly investigated in the isotopic nuclear reactions of 112Sn+112Sn and 124Sn+124Sn at incident energies of 50 and 120 MeV/nucleon, respectively. It is found that both the effective mass splitting and symmetry energy impact the kinetic energy spectra of the single ratios, in particular at the high energy tail (larger than 20 MeV). The isospin splitting of nucleon effective mass slightly impacts the double ratio spectra at the energy of 50 MeV/nucleon. A soft symmetry energy with stiffness coefficient of γ s=0.5 is constrained from the experimental data with the Fermi-energy heavy-ion collisions. Supported by Major State Basic Research Development Program in China (2014CB845405, 2015CB856903), National Natural Science Foundation of China (11722546, 11675226, 11675066, U1332207) and Youth Innovation Promotion Association of Chinese Academy of Sciences
Measurement of the nucleon structure function using high energy muons
Energy Technology Data Exchange (ETDEWEB)
Meyers, P.D.
1983-12-01
We have measured the inclusive deep inelastic scattering of muons on nucleons in iron using beams of 93 and 215 GeV muons. To perform this measurement, we have built and operated the Multimuon Spectrometer (MMS) in the muon beam at Fermilab. The MMS is a magnetized iron target/spectrometer/calorimeter which provides 5.61 kg/cm/sup 2/ of target, 9% momentum resolution on scattered muons, and a direct measure of total hadronic energy with resolution sigma/sub nu/ = 1.4..sqrt..nu(GeV). In the distributed target, the average beam energies at the interaction are 88.0 and 209 GeV. Using the known form of the radiatively-corrected electromagnetic cross section, we extract the structure function F/sub 2/(x,Q/sup 2/) with a typical precision of 2% over the range 5 < Q/sup 2/ < 200 GeV/sup 2//c/sup 2/. We compare our measurements to the predictions of lowest order quantum chromodynamics (QCD) and find a best fit value of the QCD scale parameter ..lambda../sub LO/ = 230 +- 40/sup stat/ +- 80/sup syst/ MeV/c, assuming R = 0 and without applying Fermi motion corrections. Comparing the cross sections at the two beam energies, we measure R = -0.06 +- 0.06/sup stat/ +- 0.11/sup syst/. Our measurements show qualitative agreement with QCD, but quantitative comparison is hampered by phenomenological uncertainties. The experimental situation is quite good, with substantial agreement between our measurements and those of others. 86 references.
Results of searches for the nucleon structure displays in high energy hadron-nucleus collisions
International Nuclear Information System (INIS)
Strugalski, Z.
1984-01-01
Hadron-nucleus collision data at projectile energy from a few GeV up to about eight thousand GeV were analysed in order to find effects in which a nucleon structure manifests itself. It was found that some nucleon structure displays in incident hadron deflection in its passage through atomic nuclei and in multiple production process, at energies above about 2 GeV. The distribution of the deflection angles consists of two components, the mean free path for multiparticle production is about three times larger than the expected one. These effects may be interpreted as caused by a nucleon structure
HETFIS: High-Energy Nucleon-Meson Transport Code with Fission
International Nuclear Information System (INIS)
Barish, J.; Gabriel, T.A.; Alsmiller, F.S.; Alsmiller, R.G. Jr.
1981-07-01
A model that includes fission for predicting particle production spectra from medium-energy nucleon and pion collisions with nuclei (Z greater than or equal to 91) has been incorporated into the nucleon-meson transport code, HETC. This report is primarily concerned with the programming aspects of HETFIS (High-Energy Nucleon-Meson Transport Code with Fission). A description of the program data and instructions for operating the code are given. HETFIS is written in FORTRAN IV for the IBM computers and is readily adaptable to other systems
Atomic Nuclei Utter Disintegration into Nucleons by High Energy Nuclear Projectiles
International Nuclear Information System (INIS)
Strugalski, Z.
1994-01-01
The disintegration process of atomic nuclei by high energy nuclear projectiles is described. The physical basis for this process is the passage of hadrons through layers of intranuclear matter accompanied by the nucleon emission from the target nuclei observed in experiments; kinetic energies of the nucleons are from about 20 up to about 400 MeV - in the target nucleus reference system. 22 refs., 3 tabs
High-Energy antipp and pp Elastic Scattering and Nucleon Structure
International Nuclear Information System (INIS)
Islam, M.M.; Innocente, V.; Fearnley, T.; Sanguinetti, G.
1987-01-01
High-energy antipp and pp elastic data from the CERN Collider and the ISR are analyzed in the nucleon valence core model. Diffraction is described by a profile function that incorporates crossing symmetry and saturation of Froissart-Martin bound. The model is found to provide a very satisfactory description of the elastic scattering over the whole range of energy and momentum transfer. Implications of the analysis on QCD models of nucleon structure are pointed out
High-Energy antipp and pp Elastic Scattering and Nucleon Structure
Energy Technology Data Exchange (ETDEWEB)
Islam, M.M.; Innocente, V.; Fearnley, T.; Sanguinetti, G.
1987-07-15
High-energy antipp and pp elastic data from the CERN Collider and the ISR are analyzed in the nucleon valence core model. Diffraction is described by a profile function that incorporates crossing symmetry and saturation of Froissart-Martin bound. The model is found to provide a very satisfactory description of the elastic scattering over the whole range of energy and momentum transfer. Implications of the analysis on QCD models of nucleon structure are pointed out.
The potential energy of an infinite system of nucleons and delta resonances
International Nuclear Information System (INIS)
Goodwin, N.H.
1980-01-01
The nature and properties of the delta resonance, Δ (1236), in infinite nuclear and neutron matter are investigated. Calculations of the potential energy of a system of separate Fermi seas of nucleons and delta resonances have been performed using Jastrow lowest-order constrained variational techniques. Using the Reid soft-core nucleon-nucleon interaction and a model, consistent, energy-dependent, static one-pion- and one-rho-meson-exchange nucleon-delta potential, a significant reduction in the potential energy of the system is found at densities above nuclear matter density (0.17 fm -3 ) when deltas are present. The density at which the formation of a separate Fermi sea of deltas is favourable is estimated and the consequences for the possible formation of a pion condensate and the properties of neutron star matter are discussed. (author)
The nucleon-nucleus scattering at intermediate energies
International Nuclear Information System (INIS)
Auger, J.-P.
1976-01-01
The Glauber model has the merit to connect directly the nucleon-nucleus elastic differential cross section with the nucleon-nucleon amplitude and nuclear densities. The general agreement between the 1 GeV proton elastic scattering differential cross sections calculated without adjustable parameter and the experimental data (from He 4 to Pb 208 ) is rather satisfactory up to 2. - 2.5 fm -1 momentum transfer. Although the 1 GeV proton elastic scattering experiments constitute at present one of the best method in determining neutron densities, it seems that self-consistent calculations bring the best knowledge of these densities. The model independent analysis performed with electron and proton scattering experiments show that the difference between neutron and proton r.m.s. radius cannot be determined better than 25-30% for Pb 208 [fr
Nucleon-nucleon scattering data
International Nuclear Information System (INIS)
Bystricky, J.; Lehar, F.
1981-01-01
The present review contains a compilation of p-p, n-n, n-p and p-n elastic scattering data, total cross sections for elastic and inelastic nucleon-nucleon processes as well as the slope parameters and the ratios of the real to the imaginary part of the forward scattering amplitude measured at all energies. The data are given in detailed tables with comments on each measurement. Summary tables, nucleon-nucleon kinematics formulae, transformation tables for kinematics, a detailed list of references and an author index complete the paper. (orig.)
Binding energies of sd-shell nuclei with a realistic effective Hamiltonian
International Nuclear Information System (INIS)
Dalton, B.J.; Vary, J.P.; Baldridge, W.J.
1977-01-01
The nuclear shell model with a second-order effective Hamiltonian derived within Brueckner theory from the free nucleon-nucleon interaction is shown to yield accurate binding energies of nuclei with 16 < A < 40. This agreement is obtained by choosing the spectrum of low-lying unoccupied orbitals in a justified manner and, when necessary, by employing a statistical method to approximate the lowest eigenvalue of very large shell-model diagonalizations
Energy Technology Data Exchange (ETDEWEB)
Guidal, M
1997-01-01
In this work a model is proposed to simulate the photoproduction of pseudoscalar mesons ('PI' and K) on the nucleon at high energy. This model is based on the exchange of mesonic or baryonic Regge trajectories, it is gauge invariant and it uses a Feynman diagram formalism inspired from isobaric models. The measurements concerning the following reactions {gamma}p {yields} n{pi}{sup +}, {gamma}n {yields} p{pi}{sup -}, {gamma}p {yields} p{pi}{sup 0} and {gamma}n {yields} n{pi}{sup 0} are reviewed and the new model is confronted to the experimental results. The model gives a reasonable and coherent description of these 4 reactions. The model has also been applied to the photoproduction of strange mesons and of {lambda} and {sigma} baryons and has been extrapolated at low energy to the threshold of the reaction, the model matches the results even up to E{sub {gamma}} = 2 GeV for differential cross-sections and recoil polarization. An attempt has been made to associate a Regge based description, which is valid with low transfers, with perturbative quantum chromodynamics which is valid with high transfers. The model relies on the saturation of trajectories in the high transfer region and on the counting laws that give the right variation of the cross-section. It seems that a model based on linear trajectories can be reliable up to 4 GeV. The domain of high transfer has been too little investigated to provide enough experimental data to validate the model. An experiment whose purpose is to study the photoproduction of {phi} at high transfer, is proposed. This experiment requires an accelerator with high useful cycle because of the smallness of the expected cross-section. The CEBAF (continuous electron beam accelerator facility) as well as the CLAS 4{pi} detector is presented. The study of {gamma}p {yields} p{phi} and {gamma}p {yields} K{lambda}{sup *} (1520) requires the discrimination of kaons from pions so the measurement of 180 ps as time resolution allows the
International Nuclear Information System (INIS)
1987-01-01
This report summarizes the work on experimental research in intermediate energy nuclear and particle physics carried out by New Mexico State University in 1985-87. These studies have involved investigations of nucleon-nucleon and pion-nucleus interactions. They have been carried out at the LAMPF accelerator at the Los Alamos National Laboratory, at the SIN laboratory near Zurich, Switzerland, and at the TRIUMF accelerator in Vancouver, Canada. 86 refs., 5 figs
The nucleon as a test case to calculate vector-isovector form factors at low energies
Leupold, Stefan
2018-01-01
Extending a recent suggestion for hyperon form factors to the nucleon case, dispersion theory is used to relate the low-energy vector-isovector form factors of the nucleon to the pion vector form factor. The additionally required input, i.e. the pion-nucleon scattering amplitudes are determined from relativistic next-to-leading-order (NLO) baryon chiral perturbation theory including the nucleons and optionally the Delta baryons. Two methods to include pion rescattering are compared: a) solving the Muskhelishvili-Omnès (MO) equation and b) using an N/D approach. It turns out that the results differ strongly from each other. Furthermore the results are compared to a fully dispersive calculation of the (subthreshold) pion-nucleon amplitudes based on Roy-Steiner (RS) equations. In full agreement with the findings from the hyperon sector it turns out that the inclusion of Delta baryons is not an option but a necessity to obtain reasonable results. The magnetic isovector form factor depends strongly on a low-energy constant of the NLO Lagrangian. If it is adjusted such that the corresponding magnetic radius is reproduced, then the results for the corresponding pion-nucleon scattering amplitude (based on the MO equation) agree very well with the RS results. Also in the electric sector the Delta degrees of freedom are needed to obtain the correct order of magnitude for the isovector charge and the corresponding electric radius. Yet quantitative agreement is not achieved. If the subtraction constant that appears in the solution of the MO equation is not taken from nucleon+Delta chiral perturbation theory but adjusted such that the electric radius is reproduced, then one obtains also in this sector a pion-nucleon scattering amplitude that agrees well with the RS results.
The nucleon as a test case to calculate vector-isovector form factors at low energies
Energy Technology Data Exchange (ETDEWEB)
Leupold, Stefan [Uppsala Universitet, Institutionen foer Fysik och Astronomi, Uppsala (Sweden)
2018-01-15
Extending a recent suggestion for hyperon form factors to the nucleon case, dispersion theory is used to relate the low-energy vector-isovector form factors of the nucleon to the pion vector form factor. The additionally required input, i.e. the pion-nucleon scattering amplitudes are determined from relativistic next-to-leading-order (NLO) baryon chiral perturbation theory including the nucleons and optionally the Delta baryons. Two methods to include pion rescattering are compared: a) solving the Muskhelishvili-Omnes (MO) equation and b) using an N/D approach. It turns out that the results differ strongly from each other. Furthermore the results are compared to a fully dispersive calculation of the (subthreshold) pion-nucleon amplitudes based on Roy-Steiner (RS) equations. In full agreement with the findings from the hyperon sector it turns out that the inclusion of Delta baryons is not an option but a necessity to obtain reasonable results. The magnetic isovector form factor depends strongly on a low-energy constant of the NLO Lagrangian. If it is adjusted such that the corresponding magnetic radius is reproduced, then the results for the corresponding pion-nucleon scattering amplitude (based on the MO equation) agree very well with the RS results. Also in the electric sector the Delta degrees of freedom are needed to obtain the correct order of magnitude for the isovector charge and the corresponding electric radius. Yet quantitative agreement is not achieved. If the subtraction constant that appears in the solution of the MO equation is not taken from nucleon+Delta chiral perturbation theory but adjusted such that the electric radius is reproduced, then one obtains also in this sector a pion-nucleon scattering amplitude that agrees well with the RS results. (orig.)
Binding energies of cluster ions
International Nuclear Information System (INIS)
Parajuli, R.; Matt, S.; Scheier, P.; Echt, O.; Stamatovic, A.; Maerk, T.D.
2002-01-01
The binding energy of charged clusters may be measured by analyzing the kinetic energy released in the metastable decay of mass selected parent ions. Using finite heat bath theory to determine the binding energies of argon, neon, krypton, oxygen and nitrogen from their respective average kinetic energy released were carried out. A high-resolution double focussing two-sector mass spectrometer of reversed Nier-Johnson type geometry was used. MIKE ( mass-analysed ion kinetic energy) were measured to investigate decay reactions of mass-selected ions. For the inert gases neon (Ne n + ), argon (Ar n + ) and krypton (Kr n + ), it is found that the binding energies initially decrease with increasing size n and then level off at a value above the enthalpy of vaporization of the condensed phase. Oxygen cluster ions shown a characteristic dependence on cluster size (U-shape) indicating a change in the metastable fragmentation mechanism when going from the dimer to the decamer ion. (nevyjel)
Experimental studies and microscopic analysis of the elastic scattering of low energy nucleons
International Nuclear Information System (INIS)
Tarrats-Saugnac, Annie.
1982-05-01
Data on the elastic scattering of low energy nucleons (between 20 and 40 MeV) by nuclei distributed throughout the entire mass table are examined in the framework of a microscopic approach. Two major problems occur at these low energies which do not occur at higher energies: the Pauli principle limits the interaction possibilities of projectiles with bound nucleons in the nucleus; it is not possible to neglect the antisymmetrization between projectiles and nucleon targets resulting in the addition of a nonlocal term to the potential. A quadratic moment approximation is used. As regards the inhibition of reactions inside the nucleus by the Pauli principle, an effective interaction with a relatively simple analytical form and easy to use for systematic analyses was determined [fr
A novel nuclear dependence of nucleon–nucleon short-range correlations
Energy Technology Data Exchange (ETDEWEB)
Dai, Hongkai [College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070 (China); Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Wang, Rong, E-mail: rwang@impcas.ac.cn [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Lanzhou University, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Huang, Yin [Lanzhou University, Lanzhou 730000 (China); Chen, Xurong [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)
2017-06-10
A linear correlation is found between the magnitude of nucleon–nucleon short-range correlations and the nuclear binding energy per nucleon with pairing energy removed. By using this relation, the strengths of nucleon–nucleon short-range correlations of some unmeasured nuclei are predicted. Discussions on nucleon–nucleon pairing energy and nucleon–nucleon short-range correlations are made. The found nuclear dependence of nucleon–nucleon short-range correlations may shed some lights on the short-range structure of nucleus.
Isovector couplings for nucleon charge-exchange reactions at intermediate energies
International Nuclear Information System (INIS)
Love, W.G.; Nakayama, K.; Franey, M.A.
1987-01-01
The isovector parts of the effective nucleon-nucleon interaction are studied by examination of the reaction /sup 14/C(p,n) at intermediate energies near zero momentum transfer with use of recently developed G-matrix and free--t-matrix interactions. The spin-independent coupling (V/sub tau/) exhibits a strong energy and density dependence which, in the case of the G matrix based on the Bonn potential, significantly improves the agreement between calculated values of chemical bondV/sub σ//sub tau//V/sub tau/chemical bond 2 at q = 0 and those recently extracted from the reaction /sup 14/C
International Nuclear Information System (INIS)
Xu Chang; Li Baoan; Chen Liewen; Ko, Che Ming
2011-01-01
Using the Hugenholtz-Van Hove theorem, we derive general expressions for the quadratic and quartic symmetry energies in terms of the isoscalar and isovector parts of single-nucleon potentials in isospin asymmetric nuclear matter. These expressions are useful for gaining deeper insights into the microscopic origins of the uncertainties in our knowledge on nuclear symmetry energies especially at supra-saturation densities. As examples, the formalism is applied to two model single-nucleon potentials that are widely used in transport model simulations of heavy-ion reactions.
Li, Pengcheng; Wang, Yongjia; Li, Qingfeng; Guo, Chenchen; Zhang, Hongfei
2018-04-01
With the newly updated version of the ultrarelativistic quantum molecular dynamics (UrQMD) model, a systematic investigation of the effects of in-medium nucleon-nucleon (NN ) elastic cross section on the collective flow and the stopping observables in 197Au+197Au collisions at beam energies from 40 to 150 MeV/nucleon is performed. Simulations with the medium correction factors F =σNN in -medium/σNN free=0.2 ,0.3 ,0.5 and the one obtained with the FU3FP1 parametrization which depends on both the density and the momentum are compared to the FOPI and INDRA experimental data. It is found that, to best fit the experimental data of the slope of the directed flow and the elliptic flow at midrapidity as well as the nuclear stopping, the correction factors of F =0.2 and 0.5 are required for reactions at beam energies of 40 and 150 MeV/nucleon, respectively. Whereas calculations with the FU3FP1 parametrization can simultaneously reproduce these experimental data reasonably well. And, the observed increasing nuclear stopping with increasing beam energy in experimental data can also be reproduced by using the FU3FP1 parametrization, whereas the calculated stopping power in Au + Au collisions with beam energies from 40 to 150 MeV /nucleon almost remains constant when taking F equal to a fixed value.
Energy Technology Data Exchange (ETDEWEB)
Sebille, F.; Bonilla, C. [SUBATECH, Universite de Nantes, CNRS/IN2P3, 44 - Nantes (France); Blideanu, V.; Lecolley, J.F. [Laboratoire de Physique Corpusculaire, ENSICAEN, Universite de Caen, IN2P3-CNRS, 14 - Caen (France)
2004-06-01
A microscopic investigation of nucleon-induced reactions is addressed within the DYWAN model, which is based on the projection methods of out of equilibrium statistical physics and on the mathematical theory of wavelets. Due to a strongly compressed representation of the fermionic wave-functions, the numerical simulations of the nucleon transport in target are therefore able to preserve the quantum nature of the colliding system, as well as a least biased many-body information needed to keep track of the cluster formation. A special attention is devoted to the fingerprints of the phase space topology induced by the fluctuations of the self-consistent mean-field. Comparisons be ween theoretical results and experimental data point out that ETDHF type approaches are well suited to describe reaction mechanisms in the Fermi energy domain. The observed sensitivity to physical effects shows that the nucleon-induced reactions provide a valuable probe of the nuclear interaction in this range of energy. (authors)
Pre-equilibrium emission of nucleons from reactions induced by medium-energy heavy ions
International Nuclear Information System (INIS)
Korolija, M.; Holuh, E.; Cindro, N.; Hilscher, D.
1984-01-01
Recent data on fast-nucleon emission in heavy-ion-induced reactions are analysed successfully in terms of pre-equilibrium models; it is shown that the relevant parameters of those models preserve the physical meaning they have in light-ion-induced reactions. The initial exciton number obtained from a Griffin-plot analysis and the initial number of degrees of freedom, which is the relevant parameter of the modified HMB model, appear to be approximately equal for a given reaction at a given energy. It is inferred that, for heavy-ion reactions, the determination of such a parameter is substantially dominated by the centre-of-mass energy per nucleon above the Coulomb barrier, in contrast with the results of nucleon-induced reactions
Skyrmions with low binding energies
Energy Technology Data Exchange (ETDEWEB)
Gillard, Mike, E-mail: m.n.gillard@leeds.ac.uk; Harland, Derek, E-mail: d.g.harland@leeds.ac.uk; Speight, Martin, E-mail: speight@maths.leeds.ac.uk
2015-06-15
Nuclear binding energies are investigated in two variants of the Skyrme model: the first replaces the usual Skyrme term with a term that is sixth order in derivatives, and the second includes a potential that is quartic in the pion fields. Solitons in the first model are shown to deviate significantly from ansätze previously assumed in the literature. The binding energies obtained in both models are lower than those obtained from the standard Skyrme model, and those obtained in the second model are close to the experimental values.
Skyrmions with low binding energies
International Nuclear Information System (INIS)
Gillard, Mike; Harland, Derek; Speight, Martin
2015-01-01
Nuclear binding energies are investigated in two variants of the Skyrme model: the first replaces the usual Skyrme term with a term that is sixth order in derivatives, and the second includes a potential that is quartic in the pion fields. Solitons in the first model are shown to deviate significantly from ansätze previously assumed in the literature. The binding energies obtained in both models are lower than those obtained from the standard Skyrme model, and those obtained in the second model are close to the experimental values
Skyrmions with low binding energies
Directory of Open Access Journals (Sweden)
Mike Gillard
2015-06-01
Full Text Available Nuclear binding energies are investigated in two variants of the Skyrme model: the first replaces the usual Skyrme term with a term that is sixth order in derivatives, and the second includes a potential that is quartic in the pion fields. Solitons in the first model are shown to deviate significantly from ansätze previously assumed in the literature. The binding energies obtained in both models are lower than those obtained from the standard Skyrme model, and those obtained in the second model are close to the experimental values.
Transverse energy production in 208Pb+Pb collisions at 158 GeV per nucleon
International Nuclear Information System (INIS)
Alber, T.; Appelshaeuser, H.; Baechler, J.; Bartke, J.; Bialkowska, H.; Bieser, F.; Bloomer, M.A.; Blyth, C.O.; Bock, R.; Bormann, C.; Brady, F.P.; Brockmann, R.; Buncic, P.; Caines, H.L.; Cebra, D.; Chan, P.; Cooper, G.E.; Cramer, J.G.; Cramer, P.B.; Csato, P.; Derado, I.; Dunn, J.; Eckardt, V.; Eckhardt, F.; Euler, S.; Ferguson, M.I.; Fischer, H.G.; Fodor, Z.; Foka, P.; Freund, P.; Fuchs, M.; Gal, J.; Gazdzicki, M.; Gladysz, E.; Grebieszkow, J.; Guenther, J.; Harris, J.W.; Heck, W.; Hegyi, S.; Hill, L.A.; Huang, I.; Howe, M.A.; Igo, G.; Irmscher, D.; Jacobs, P.; Jones, P.G.; Kadija, K.; Kecskemeti, J.; Kowalski, M.; Kuehmichel, A.; Lasiuk, B.; Margetis, S.; Mitchell, J.W.; Mock, A.; Nelson, J.M.; Odyniec, G.; Palinkas, J.; Palla, G.; Panagiotou, A.D.; Petridis, A.; Piper, A.; Poskanzer, A.M.; Prindle, D.J.; Puehlhofer, F.; Rauch, W.; Renfordt, R.; Retyk, W.; Ritter, H.G.; Roehrich, D.; Rudolph, H.; Runge, K.; Sandoval, A.; Sann, H.; Schaefer, E.; Schmitz, N.; Schoenfelder, S.; Seyboth, P.; Seyerlein, J.; Sikler, F.; Skrzypczak, E.; Stock, R.; Stroebele, H.; Szentpetery, I.; Sziklai, J.; Toy, M.; Trainor, T.A.; Trentalange, S.; Vassiliou, M.; Vesztergombi, G.; Vranic, D.; Wenig, S.; Whitten, C.; Wienold, T.; Wood, L.; Zimanyi, J.; Zhu, X.; Zybert, R.
1995-01-01
Measurements of the forward and the transverse energy in 158 GeV per nucleon 208 Pb+Pb collisions are presented. A total transverse energy of about 1 TeV is created in central collisions. An energy density of about 3GeV/fm 3 is estimated for near head-on collisions. Only statistical fluctuations are seen in the ratio of electromagnetic to hadronic transverse energy. copyright 1995 The American Physical Society
International Nuclear Information System (INIS)
Wilcke, W.W.; Schroeder, W.U.; Huizenga, J.R.; Birkelund, J.R.; Randrup, J.
1980-01-01
Although considerable progress has been achieved in the understanding of strongly damped reactions at energies several MeV/u above the Coulomb barrier, some important experimental results are not yet clearly understood. Among these is the degree of correlation between the nucleon exchange and the large energy losses observed. Experimental evidence suggesting nucleon exchange as described by a one-body model to be the major component of the dissipation mechanism is discussed. It is concluded that the previously unexplained bombarding energy dependence between energy loss and fragment charge dispersion can be understood on the basis of a nucleon exchange model, provided the Pauli exclusion principle is taken into account. No necessity is seen to invoke further energy dissipation mechanisms. 7 figures
Three-nucleon problem with phase equivalent potentials
International Nuclear Information System (INIS)
Pushkash, O.M.; Shapoval, D.V.; Simenog, I.V.
1991-01-01
The effect of the t-matrix off-shell variations with nonlocal phase equivalent N-N potentials on the three-nucleon parameters is studied. The variations, which lower or increase the tritium binding energy, are revealed. We show that under certain conditions, the three-nucleon low-energy observables are almost insensitive to the high energy behaviour of the negative parts of the scattering phase shifts. The inverse problem method is applied to reconstruct simple S-wave potentials which to provide a unified description of the two-nucleon and low-energy three-nucleon data. 22 refs.; 6 figs. (author)
On the A dependence in the process of dilepton production by high-energy nucleons
International Nuclear Information System (INIS)
Gevorkyan, S.R.; Zhamkochyan, V.M.
1978-01-01
The process of lepton pair production in nucleon-nucleus collisions for high energies is considered. It is shown, that with due regard for the N → π → μ + μ - inelastic transitions the experimentally observed A dependence of the cross section of the NA → μ + μ - X process can be explained in the framework of the multiple scattering theory
Assessment of Coulomb shifts in nucleon scattering resonances on light nuclei at low energies
International Nuclear Information System (INIS)
Takibaev, N.Zh.; Uzakova, Zh.; Abdanova, L.
2003-01-01
The assessments of the Coulomb forces contribution to position and width of the resonances at nucleons scattering on light nuclei within low energy field are given. In particular the shifts of resonances in amplitudes arising in the processes protons scattering on light nuclei relatively neutrons scattering resonance characteristics on these nuclei are considered
International Nuclear Information System (INIS)
Filippov, G.F.; Lopez Trujillo, A.; Rybkin, I.Yu.
1993-01-01
The matrix elements of the potential energy operator (which includes central, spin-orbit and tensor components) are calculated between the generating invariants of the cluster basis describing α + d and t+h configurations of the six-nucleon system. (author). 12 refs
Medium energy nucleon-nucleus scattering theory by semi-classical distorted wave approximation
Energy Technology Data Exchange (ETDEWEB)
Ogata, Kazuyuki [Kyushu Univ., Fukuoka (Japan)
1998-07-01
The semiclassical distorted wave model (SCDW) is one of the quantum mechanical models for nucleon inelastic and charge exchange scattering at intermediate energies. SCDW can reproduce the double differential inclusive cross sections for multi-step direct processes quite well in the angular and outgoing energy regions where the model is expected to work. But the model hitherto assumed on-the-energy-shell (on-shell) nucleon-nucleon scattering in the nucleus, neglecting the difference in the distorting potentials for the incoming and the outgoing particles and also the Q-value in the case of (p,n) reactions. There had also been a problem in the treatment of the exchange of colliding nucleons. Now we modify the model to overcome those problems and put SCDW on sounder theoretical foundations. The modification results in slight reduction (increase) of double differential cross sections at forward (backward) angles. We also examine the effect of the in-medium modification of N-N cross sections in SCDW and find it small. A remedy of the disagreement at very small and large angles in terms of the Wigner transform of the single particle density matrix is also discussed. This improvement gives very promising results. (author)
Energy-dependent microscopic optical potential for scattering of nucleons on light nuclei
Energy Technology Data Exchange (ETDEWEB)
Farag, M.Y.H.; Esmael, E.H. [Cairo University, Physics Department, Faculty of Science, Giza (Egypt); Maridi, H.M. [Cairo University, Physics Department, Faculty of Science, Giza (Egypt); Taiz University, Physics Department, Faculty of Applied Science, Taiz (Yemen)
2014-06-15
We present an energy-dependent microscopic optical model potential for elastic scattering of nucleons on light nuclei. The single-folding model is used for the real part of the optical potential (OP), while the imaginary part is derived within the high-energy approximation theory. The energy dependence of the OP is determined from the parameterization of the volume integrals those calculated from the best-fit OP that fit the experimental data of the cross sections and analyzing powers. This energy-dependent OP is successfully applied to analyze the proton elastic scattering of {sup 4,6,i8}He, {sup 6,7}Li, and {sup 9,10}Be nuclei at low and intermediate incident energies up to 200MeV/nucleon. (orig.)
QMD and JAM calculations for high energy nucleon-nucleus collisions
International Nuclear Information System (INIS)
Niita, Koji
2002-01-01
We describe the two simulation codes, QMD and JAM (Jet AA Microscopic Transport Model), for high energy nuclear reactions. QMD can treat the nucleus-nucleus reactions as well as nucleon-nucleus reactions based on the molecular dynamics. We have applied the QMD code intensively to nucleon-nucleus reactions and checked its validity. The cross sections obtained by the QMD are now used for evaluation of high energy nuclear data in JAERI. JAM is a hadronic cascade code including the resonance and string model for the hadron-hadron collisions at high energy up to 200 GeV. We have developed a high energy particle transport code NMTC/JAM by including the JAM code for the intra-nuclear cascade part. (author)
Angular distributions of nucleons emitted in high energy hadron-nucleus collisions
International Nuclear Information System (INIS)
Strugalski, Z.
1983-01-01
Angular distributions of ''fast'' protons, of kinetic energy from about 20 to about 400 MeV, emitted in pion-xenon nucleus collisions at 3.5 GeV/c momentum were studied in two groups of events - when particles are produced and when particle production does not occur. The distributions are practically the same in both the groups of events and in subgroups of events with various multiplicities of emitted protons. Comparison of angular distributions of protons emitted in pion-xenon nucleus collisions at 3.5 GeV/c momentum with corresponding angular distributions of protons emitted in proton-emulsion collisions at 300-400 GeV/c momentum is performed. Results obtained allow to conclude that average value of the nucleon emission angle and the nucleon angular distributions do not depend practically on the nuclear matter layer thickness the incident hadron collided with. Fast nucleons emitted from the target nucleus seem did not interact inside the parent nucleus. Fast nucleon angular distributions do not depend on the energy of incident hadron, they are the same for pion-nucleus and for proton-nucleus collisions as well
Nuclear energy density functional from chiral pion-nucleon dynamics revisited
Kaiser, N.; Weise, W.
2009-01-01
We use a recently improved density-matrix expansion to calculate the nuclear energy density functional in the framework of in-medium chiral perturbation theory. Our calculation treats systematically the effects from $1\\pi$-exchange, iterated $1\\pi$-exchange, and irreducible $2\\pi$-exchange with intermediate $\\Delta$-isobar excitations, including Pauli-blocking corrections up to three-loop order. We find that the effective nucleon mass $M^*(\\rho)$ entering the energy density functional is iden...
High energy nuclear collisions in the few GeV/nucleon region: projectile and target fragmentation
International Nuclear Information System (INIS)
Schroeder, L.S.
1980-06-01
A general review of nucleon-nucleus and nucleus-nucleus collisions for incident energies <10 GeV/nucleon is presented. The division of these interactions into peripheral and central collisions is briefly discussed. Subjects treated include the following: target and projectile fragmentation systematics, production of exotic nuclear fragments, studies of multiparticle final states, total cross section measurements, results from an experiment that indicate the production of projectile fragments with an anomalously short reaction mean free path, high-energy particle production at backward angles beyond simple N-N kinematic limits, and recent results on backward particle emission in studies with the Berkeley streamer chamber. Both the particle and nuclear physics aspects that are present are considered. A brief discussion of future trends in this energy range ends the presentation. 65 references, 37 figures
Three-nucleon forces and the trinucleon bound states
International Nuclear Information System (INIS)
Friar, J.L.; Frois, B.
1986-04-01
A summary of the bound-state working group session of the ''International Symposium on the Three-Body Force in the Three-Nucleon System'' is presented. The experimental evidence for three-nucleon forces has centered on two ground state properties: the tritium binding energy and the trinucleon form factors. Both are discussed
Wang, Ting-Ting; Ma, Yu-Gang; Zhang, Chun-Jian; Zhang, Zheng-Qiao
2018-03-01
The proton-proton momentum correlation function from different rapidity regions is systematically investigated for the Au + Au collisions at different impact parameters and different energies from 400 A MeV to 1500 A MeV in the framework of the isospin-dependent quantum molecular dynamics model complemented by the Lednický-Lyuboshitz analytical method. In particular, the in-medium nucleon-nucleon cross-section dependence of the correlation function is brought into focus, while the impact parameter and energy dependence of the momentum correlation function are also explored. The sizes of the emission source are extracted by fitting the momentum correlation functions using the Gaussian source method. We find that the in-medium nucleon-nucleon cross section obviously influences the proton-proton momentum correlation function, which is from the whole-rapidity or projectile or target rapidity region at smaller impact parameters, but there is no effect on the mid-rapidity proton-proton momentum correlation function, which indicates that the emission mechanism differs between projectile or target rapidity and mid-rapidity protons.
Predictions of Quantum Molecular Dynamical Model between incident energy 50 and 1000 MeV/Nucleon
Directory of Open Access Journals (Sweden)
Kumar Sanjeev
2015-01-01
Full Text Available In the present work, the Quantum Molecular Dynamical (QMD model is summarized as a useful tool for the incident energy range of 50 to 1000 MeV/nucleon in heavy-ion collisions. The model has reproduced the experimental results of various collaborations such as ALADIN, INDRA, PLASTIC BALL and FOPI upto a high level of accuracy for the phenomena like multifragmentation, collective flow as well as elliptical flow in the above prescribed energy range. The efforts are further in the direction to predict the symmetry energy in the wide incident energy range.
Energy Technology Data Exchange (ETDEWEB)
Jung, Chang Kee [State University of New York at Stony Brook; Douglas, Michaek [State University of New York at Stony Brook; Hobbs, John [State University of New York at Stony Brook; McGrew, Clark [State University of New York at Stony Brook; Rijssenbeek, Michael [State University of New York at Stony Brook
2013-07-29
This is the final report of the DOE grant DEFG0292ER40697 that supported the research activities of the Stony Brook High Energy Physics Group from November 15, 1991 to April 30, 2013. During the grant period, the grant supported the research of three Stony Brook particle physics research groups: The Nucleon Decay and Neutrino group, the Hadron Collider Group, and the Theory Group.
Isospin violation in low-energy pion-nucleon scattering revisited
Energy Technology Data Exchange (ETDEWEB)
Hoferichter, Martin, E-mail: hoferichter@hiskp.uni-bonn.d [Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie) and Bethe Center for Theoretical Physics, Universitaet Bonn, D-53115 Bonn (Germany); Kubis, Bastian [Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie) and Bethe Center for Theoretical Physics, Universitaet Bonn, D-53115 Bonn (Germany); Meissner, Ulf-G. [Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie) and Bethe Center for Theoretical Physics, Universitaet Bonn, D-53115 Bonn (Germany); Institut fuer Kernphysik (IKP-3), Institute for Advanced Simulation, and Juelich Center for Hadron Physics, Forschungszentrum Juelich, D-52425 Juelich (Germany)
2010-02-01
We calculate isospin breaking in pion-nucleon scattering in the threshold region in the framework of covariant baryon chiral perturbation theory. All effects due to quark mass differences as well as real and virtual photons are consistently included. As an application, we discuss the energy dependence of the triangle relation that connects elastic scattering on the proton pi{sup +}-p->pi{sup +}-p with the charge exchange reaction pi{sup -}p->pi{sup 0}n.
Isospin violation in low-energy pion-nucleon scattering revisited
International Nuclear Information System (INIS)
Hoferichter, Martin; Kubis, Bastian; Meissner, Ulf-G.
2010-01-01
We calculate isospin breaking in pion-nucleon scattering in the threshold region in the framework of covariant baryon chiral perturbation theory. All effects due to quark mass differences as well as real and virtual photons are consistently included. As an application, we discuss the energy dependence of the triangle relation that connects elastic scattering on the proton π ± p→π ± p with the charge exchange reaction π - p→π 0 n.
Cucinotta, Francis A.; Hajnal, Ferenc; Wilson, John W.
1990-01-01
The transport of nuclear fragmentation recoils produced by high-energy nucleons in the region of the bone-tissue interface is considered. Results for the different flux and absorbed dose for recoils produced by 1 GeV protons are presented in a bidirectional transport model. The energy deposition in marrow cavities is seen to be enhanced by recoils produced in bone. Approximate analytic formulae for absorbed dose near the interface region are also presented for a simplified range-energy model.
Nucleon-nucleon theory and phenomenology
International Nuclear Information System (INIS)
Signell, P.
1981-03-01
This project involves five inter-related subprojects: (1) derivation of the intermediate range nucleon-nucleon interaction using a new method that utilizes much shorter and simpler analytic continuation through the unphysical region that lies between the πN and ππ physical regions of the N anti N → ππ amplitude (with significantly improved accuracy for the nucleon-nucleon interaction); (2) construction of a short range phenomenological potential that, with the theoretical part mentioned above, gives a precise fit to the nucleon-nucleon data and is parameterized for easy use in nucleon calculations; (3) phase shift analyses of the world data below 400 MeV, especially the large amount of very precise data below 20 MeV and the new data near 55 MeV that have never been analyzed properly; (4) the introduction of a K-matrix formulation of the Optimal Polynomial Expansion in order to accelerate convergence of the partial wave series at LAMPF energies; and (5) setting up of a cooperatively evaluated permanent nucleon-nucleon data bank in the 0-1200 MeV range that can be used by all nucleon-nucleon reseachers
International Nuclear Information System (INIS)
Guiasu, I.
1978-01-01
The goals of this work are: a) to examine and turn to account in the study of γ-proton elastic scattering the possibility of using a dispersion representation assumed for the amplitude set Asub(i), free of singularities and kinematic zeroes. This is achieved through a direct calculation of the effective unpolarized differential section of the Compton effect on the proton, at various scattering angles in an energy range of 0 β which agrees with current experimental data. c) to establish a law regarding low ω 5 order energies for the helicity amplitudes and for the unpolarized differential effective section of the process γ + p → γ' + p'. We believe this law to be necessary on one hand for a more accurate determination of the α, β variables out of existent experiments and, on the other hand, for the opportunity to define within the Compton effect on the nucleon new structure constants of the nucleon such as the quadrupolar electromagnetic polarizabilities. By fitting the formula of the unpolarized differential effective section in order ω 5 to the experimental data we obtained modified values of α, β, but still in accordance with the order α > β. d) to establish an inequality based upon the analyticity properties of the Compton invariant amplitudes between expressions that include measurable physical variables, static properties of the nucleon and integrals on the effective differential section for the process γ + p → γ' + p'. (author)
Microscopic theory for nucleon-nucleus optical potential in intermediate energies
International Nuclear Information System (INIS)
He Guozhu; Cai Chonghai
1984-01-01
Based on the scattering theory of KMT and FGH we calculate the nucleon-nucleus optical potentials of 4 He, 16 O and 40 Ca from the Paris N-N potential given by M. Lacombe et al. The real part Vsub(R)(r) of our optential has the form of Woods-Saxon when the kinetic energy E of the incident nucleon is low. The depth of Vsub(R)(r) will decrease as E increases, and it turns into positive in the interior of nucleus when E approx.= 300 MeV. The repulsive effect in the interior of nucleus increases rapidly as E increases even more, butthere always exists some attractive effect at the surface of nucleus. Therefore, Vsub(R)(r) has generally the wine-bottle bottom shape. We also calculate the quatity Jv/N = (4π/N)∫sub(0)sub(infinity)Vsub(R)(r)r 2 dr. Our results are basically in acordance with those of M.Jaminon et al's relativistic Hatree calculation as well as the experimental results. In this work we also calculate the imaginary part of optical potential and its variation with the kinetic energy of the incident nucleon
On the nucleon effective mass role to the high energy proton spallation reactions
Energy Technology Data Exchange (ETDEWEB)
Santos, B.M., E-mail: biank_ce@if.uff.br [Instituto de Física, Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza, 24210-346 Niterói, RJ (Brazil); Instituto Militar de Engenharia, Praça General Tibúrcio 80, 22290-270 Rio de Janeiro, RJ (Brazil); Pinheiro, A.R.C. [Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud 150, 22290-180 Rio de Janeiro, RJ (Brazil); Universidade Federal do Acre, BR 364 km 04, 69920-900 Rio Branco, AC (Brazil); Gonçalves, M. [Comissão Nacional de Energia Nuclear, Rua General Severiano 90, 22290-901 Rio de Janeiro, RJ (Brazil); Duarte, S.B. [Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud 150, 22290-180 Rio de Janeiro, RJ (Brazil); Cabral, R.G. [Instituto Militar de Engenharia, Praça General Tibúrcio 80, 22290-270 Rio de Janeiro, RJ (Brazil)
2016-04-15
We explore the effect of the nucleon effective mass to the dynamic evolution of the rapid phase of proton–nucleus spallation reactions. The analysis of the relaxation time for the non-equilibrium phase is studied by variations in the effective mass parameter. We determine the final excitation energy of the hot residual nucleus at the end of cascade phase and the de-excitation of the nuclear system is carried out considering the competition of particle evaporation and fission processes. It was shown that the excitation energy depends of the hot compound residual nucleus at the end of the rapid phase on the changing effective mass. The multiplicity of particles was also analyzed in cascade and evaporation phase of the reaction. The use of nucleon effective mass during cascade phase can be considered as an effect of the many-body nuclear interactions not included explicitly in a treatment to the nucleon–nucleon interaction inside the nucleus. This procedure represents a more realistic scenario to obtain the neutron multiplicity generated in this reaction, which is a benchmark for the calculation of the neutronic in the ADS reactors.
Low-energy kaon-nucleon/nuclei interaction studies at DAΦNE by AMADEUS
Directory of Open Access Journals (Sweden)
Tucaković Ivana
2015-01-01
Full Text Available The AMADEUS experiment deals with the investigation of the low-energy kaon-nuclei hadronic interaction at the DAΦNE collider at LNF-INFN, fundamental to respond to longstanding open questions in the non-perturbative QCD in the strangeness sector. One of the most interesting aspects is to understand how hadron masses and interactions change in the nuclear environment. The antikaon-nucleon potential is investigated searching for signals from possible bound kaonic clusters, which would imply a strongly attractive antikaon-nucleon potential. AMADEUS step 0 consists in the analysis of 2004/2005 KLOE data, exploring K− absorptions in H, 4He, 9Be and 12C present in setup materials. The status of the various preliminary analyses is presented, together with future perspectives.
Radiative capture of nucleons at astrophysical energies with single-particle states
International Nuclear Information System (INIS)
Huang, J.T.; Bertulani, C.A.; Guimaraes, V.
2010-01-01
Radiative capture of nucleons at energies of astrophysical interest is one of the most important processes for nucleosynthesis. The nucleon capture can occur either by a compound nucleus reaction or by a direct process. The compound reaction cross sections are usually very small, especially for light nuclei. The direct capture proceeds either via the formation of a single-particle resonance or a non-resonant capture process. In this work we calculate radiative capture cross sections and astrophysical S-factors for nuclei in the mass region A<20 using single-particle states. We carefully discuss the parameter fitting procedure adopted in the simplified two-body treatment of the capture process. Then we produce a detailed list of cases for which the model works well. Useful quantities, such as spectroscopic factors and asymptotic normalization coefficients, are obtained and compared to published data.
Systematics of intermediate-energy single-nucleon removal cross sections
Tostevin, J. A.; Gade, A.
2014-11-01
There is now a large and increasing body of experimental data and theoretical analyses for reactions that remove a single nucleon from an intermediate-energy beam of neutron- or proton-rich nuclei. In each such measurement, one obtains the inclusive cross section for the population of all bound final states of the mass A -1 reaction residue. These data, from different regions of the nuclear chart, and that involve weakly and strongly bound nucleons, are compared with theoretical expectations. These calculations include an approximate treatment of the reaction dynamics and shell-model descriptions of the projectile initial state, the bound final states of the residues, and the single-particle strengths computed from their overlap functions. The results are discussed in the light of recent data, more exclusive tests of the eikonal dynamical description, and calculations that take input from more microscopic nuclear structure models.
The nucleon-antinucleon interaction at low energies
International Nuclear Information System (INIS)
Alvear, C.
1977-08-01
A theoretical analysis is made of recent low energy data relative to scattering process p sup(-)d → p + pions from 300 to 600 Mev/c laboratory incident momentum, with the purpose of obtaining information about resonances in the pure iso-spin system p sup(-)n (I = 1). The single and double term of the multiple scattering series are evaluated using a formalism based on Glauber theory and Feynman rules. Then, the differential cross section with respect to the invariant mass of the produced pions is obtained. The theoretical results are used to analyse the available data, which are then shown to be consistent with a non resonant behavior of the p sup(-)n system. (Author) [pt
N → Δ (1232) electromagnetic transition form factor and pion-nucleon dynamics at moderate energies
International Nuclear Information System (INIS)
Jurewicz, A.
1980-01-01
The dependence of the electromagnetic N → Δ (1232) transition form factor G/sup asterisk//sub M/(q 2 ) on q 2 , the four-momentum transfer squared, has been calculated with the use of relativistic dispersion relations supplemented with some dynamical assumptions. In the first place, they regard the phase of the magnetic dipole amplitude of electroproduction of pions on nucleons in the p 33 final state beyond the region of elastic unitarity. Namely, over the range from the lowest inelastic threshold up to 1780 MeV pion-nucleon c.m. energy, the phase in question has been identified with the real part of the respective phase shift of pion-nucleon scattering. Secondly, contributions to the dispersion integral from the higher energy region have been neglected. Finally, the polynomial ambiguity which appears in the problem has been fixed by requiring that the foregoing amplitude of electroproduction vanishes, independently of q 2 , at the upper end of the integration interval as defined above. These assumptions which preserve unitarity were shown previously to lead to very good results when applied to the calculation of the multipole amplitudes M/sup() 3/2/ 1 /sub +/ and E/sup() 3/2/ 1 /sub +/ of photopion production on nucleons in the Δ (1232) region. Now it is also shown that G/sup asterisk//sub M/(q 2 ) calculated in that fashion follows remarkably well the data over the whole range 0 2 2 currently covered by quantitative experimental studies. Some speculation concerning a possible dynamical rooting of the foregoing assumptions is presented
International Nuclear Information System (INIS)
Tornow, W.; Witala, H.; Kievsky, A.
1998-01-01
The 4 P J waves in nucleon-deuteron scattering were analyzed using proton-deuteron and neutron-deuteron data at E N =3 MeV. New sets of nucleon-nucleon 3 P j phase shifts were obtained that may lead to a better understanding of the long-standing A y (θ) puzzle in nucleon-deuteron elastic scattering. However, these sets of 3 P j phase shifts are quite different from the ones determined from both global phase-shift analyses of nucleon-nucleon data and nucleon-nucleon potential models. copyright 1998 The American Physical Society
Equidistant structure and effective nucleon mass in nuclear matter
International Nuclear Information System (INIS)
Tezuka, Hirokazu.
1981-11-01
The effective nucleon mass of the Equidistant Multi-Layer Structure (EMULS) is discussed self-consistently. In the density region where the Fermi gas state in nuclear matter is unstable against the density fluctuation, the EMULS gives lower binding energy. It is, however, shown that such a structure with an ordinary nucleon mass collapses due to too strong attraction. We point out that such a collapse can be avoided by taking account of an effective nucleon mass affected by the localization of nucleons. (author)
Extracting the σ-term from low-energy pion-nucleon scattering
Ruiz de Elvira, Jacobo; Hoferichter, Martin; Kubis, Bastian; Meißner, Ulf-G.
2018-02-01
We present an extraction of the pion-nucleon (π N) scattering lengths from low-energy π N scattering, by fitting a representation based on Roy-Steiner equations to the low-energy data base. We show that the resulting values confirm the scattering-length determination from pionic atoms, and discuss the stability of the fit results regarding electromagnetic corrections and experimental normalization uncertainties in detail. Our results provide further evidence for a large π N σ-term, {σ }π N=58(5) {{MeV}}, in agreement with, albeit less precise than, the determination from pionic atoms.
Investigations of Few-Nucleon System Dynamics in Medium Energy Domain
Ciepał, I.; Kłos, B.; Kistryn, St.; Stephan, E.; Biegun, A.; Bodek, K.; Deltuva, A.; Epelbaum, E.; Eslami-Kalantari, M.; Fonseca, A. C.; Golak, J.; Jha, V.; Kalantar-Nayestanaki, N.; Kamada, H.; Khatri, G.; Kirillov, Da.; Kirillov, Di.; Kliczewski, St.; Kozela, A.; Kravcikova, M.; Machner, H.; Magiera, A.; Martinska, G.; Messchendorp, J.; Nogga, A.; Parol, W.; Ramazani-Moghaddam-Arani, A.; Roy, B. J.; Sakai, H.; Sekiguchi, K.; Sitnik, I.; Siudak, R.; Skibiński, R.; Sworst, R.; Urban, J.; Witała, H.; Wrońska, A.; Zejma, J.
2013-08-01
Precise and large set of cross sections, vector A x , A y and tensor A xx , A xy , A yy analyzing powers for the 1 H( d, pp) n breakup reactions were measured at 100 and 130 MeV deuteron beam energies with the use of the SALAD and BINA detectors at KVI and Germanium Wall setup at FZ-Jülich. Results are compared with various theoretical approaches which model the three-nucleon (3N) system dynamics. The calculations are based on different two-nucleon (2N) potentials which can be combined with models of the three-nucleon force (3NF) and other pieces of the dynamics can also be included like the Coulomb interaction and relativistic effects. The cross sections data reveal seizable 3NF and Coulomb force influence. In case of analyzing powers very low sensitivity to the effects was found and the data are well describe by 2N models only. At 130 MeV for A xy serious disagreements appear when 3NF models are included into calculations.
Investigations of Few-Nucleon System Dynamics in Medium Energy Domain
International Nuclear Information System (INIS)
Ciepał, I.; Kistryn, St.; Biegun, A.; Bodek, K.; Golak, J.; Khatri, G.; Magiera, A.; Parol, W.; Skibiński, R.; Sworst, R.; Witała, H.; Wrońska, A.; Zejma, J.; Kłos, B.; Stephan, E.; Kozela, A.; Kliczewski, St.; Siudak, R.; Eslami-Kalantari, M.; Ramazani-Moghaddam-Arani, A.; Kalantar-Nayestanaki, N.; Messchendorp, J.; Machner, H.; Nogga, A.; Epelbaum, E.; Deltuva, A.; Fonseca, A. C.; Kamada, H.; Jha, V.; Kirillov, Da.; Kirillov, Di.; Sitnik, I.; Kravcikova, M.; Martinska, G.; Urban, J.; Roy, B.J.; Sakai, H.; Sekiguchi, K.
2013-01-01
Precise and large set of cross sections, vector A x , A y and tensor A xx , A xy , A yy analyzing powers for the 1 H(d, pp)n breakup reactions were measured at 100 and 130 MeV deuteron beam energies with the use of the SALAD and BINA detectors at KVI and Germanium Wall setup at FZ-Jülich. Results are compared with various theoretical approaches which model the three-nucleon (3N) system dynamics. The calculations are based on different two-nucleon (2N) potentials which can be combined with models of the three-nucleon force (3NF) and other pieces of the dynamics can also be included like the Coulomb interaction and relativistic effects. The cross sections data reveal seizable 3NF and Coulomb force influence. In case of analyzing powers very low sensitivity to the effects was found and the data are well describe by 2N models only. At 130 MeV for A xy serious disagreements appear when 3NF models are included into calculations. (author)
International Nuclear Information System (INIS)
Oertzen, W. von; Voit, H.; Imanishi, B.
1988-10-01
This report contains a review article considering the evolution of direct mechanisms with incident energy in heavy ion reactions and two theoretical articles concerning two-center effects in transfer reactions between heavy ions and the nucleon promotion in heavy ion reactions. See hints under the relevant topics. (HSI)
Nucleon exchange and heat partition in 74Ge + 165Ho collision at energy 8.5 MeV/A
International Nuclear Information System (INIS)
Planeta, R.
1990-01-01
This paper reports that one of the distinctive features of damped heavy-ion reactions is the rapid conversion of relative kinetic energy into heat during the lifetime of the dinuclear system formed in the collision. Of particular interest in this regard are the questions: how heat, or excitation energy, is partitioned between the reaction partners; how heat partition depends on nucleon transfer. Damped collisions at energies near or just above the barrier have been generally interpreted in terms of transport models which account for energy dissipation in terms of nucleon exchange between the projectile-like (PLF) and target-like fragments. Thus, in this context statistical nucleon exchange is the mechanism for heating of the system. Transport model calculation have met considerable success in accounting for the major features of damped collisions, for example, energy dissipation and angular distributions. Nonetheless, many important uncertainties remain
Characteristics of intermediate-energy nucleons emitted from 50 GeV
International Nuclear Information System (INIS)
Goyal, D.P.; Singh, S.; Arya, N.S.
1984-01-01
The multiplicity and angular distributions of intermediate-energy (grey) nucleons are studied from 50 GeV π - -nucleus data and compared with those available from π - -nucleus and p-nucleus interactions at other energies. The value of is found to be dependent both on the energy as well as on the projectile. The former variation is attributable to kinematics and the latter explainable on the basis of the additive quark model. The angular distribution of grey particles is found to be independent of energy, projectile and target, which supports the view that grey particles are chiefly due to knock-on recoiling protons. The various versions of the cascade model, however, are unable to explain any of the observed features of grey-particle distributions
International Nuclear Information System (INIS)
Kazarnovskij, M.V.; Matushko, G.K.; Matushko, V.L.; Par'ev, Eh.Ya.; Serezhnikov, S.V.
1981-01-01
The problem on propagation of the internuclear cascade initiated by nucleons of 0.1-1 GeV energy in accelerator schielding is solved approximately in the analytical form. Analytical expressions for the function of spatial, angular and energy distribution of the flux density of nucleons with the energy above 20 MeV and some functionals from it are obtained. The results of the calculations obtained by the developed methods are compared with calculations obtained by the method of direct simulation. It is shown that at the atomic mass of shielding material [ru
A = 4 0+ - 1+ binding-energy difference
International Nuclear Information System (INIS)
Gibson, B.F.; Lehman, D.R.
1982-01-01
The A = 4 Λ-hypernuclei provide a rich source of information about the s-wave properties of the fundamental hyperon-nucleon (YN) force as well as offer a unique opportunity to investigate the complications that arise in calculations of the properties of bound systems in which one baryon (here the Λ) with a given isospin couples strongly to another (the Σ) with a different isospin. The Λ 4 H - Λ 4 He isodoublet ground-state energies are not consistent with a charge symmetry hypothesis for the YN interaction. The (spin-flip) excitation energies are quite sensitive to the ΛN - ΣN coupling of the YN interaction. In particular, when one represents the free YN interaction in terms of one-channel effective ΛN potentials, the resulting 0 + (ground) state and 1 + (excited) spin-flip state are inversely ordered in terms of binding energies, the 1 + state being more bound. It is the Σ suppression that results from the reduced strength of the ΛN - ΣN off-diagonal coupling potential when the trinucleon core is restricted to isospin-1/2 which we study here. We find this spin-isospin suppression of the Λ-Σ conversion, which is due to the composite nature of the nuclear cores of the Λ 4 H and Λ 4 He hypernuclei, to be a significant factor in understanding the 0 + - 1 + binding energy relationship
Charge exchange during pion-nucleon scattering at low energy: experiment and analysis
International Nuclear Information System (INIS)
Vernin, Pascal
1972-01-01
This research thesis lies within the frame of a more general study of pion-nucleon scattering according to the following processes: π + p → π + p; π - p → π - p; π - p → π 0 n. It more precisely addresses the last reaction, so-called charge exchange. Pion-nucleon interactions are described by phase shifts of scattering waves. But the measurement of one of these phase shifts (that of the S wave) requires very low energy pions, and could not have been performed until now with a good precision. In order to fill this gap, the author performed charge exchange experiments at 180 deg. and for energies of 22.6, 33.9 and 42.6 MeV. After a recall on involved theoretical data, the author describes the experimental setup, and reports the detailed study of problems raised by neutron detection. He shows that the analysis of experimental data allows (a 3 - a 1 ) to be obtained with a precision which, without being as high as desired, is nevertheless satisfying [fr
Development of global medium-energy nucleon-nucleus optical model potentials
International Nuclear Information System (INIS)
Madland, D.G.; Sierk, A.J.
1997-01-01
The authors report on the development of new global optical model potentials for nucleon-nucleus scattering at medium energies. Using both Schroedinger and Dirac scattering formalisms, the goal is to construct a physically realistic optical potential describing nucleon-nucleus elastic scattering observables for a projectile energy range of (perhaps) 20 meV to (perhaps) 2 GeV and a target mass range of 16 to 209, excluding regions of strong nuclear deformation. They use a phenomenological approach guided by conclusions from recent microscopic studies. The experimental database consists largely of proton-nucleus elastic differential cross sections, analyzing powers, spin-rotation functions, and total reaction cross sections, and neutron-nucleus total cross sections. They will use this database in a nonlinear least-squares adjustment of optical model parameters in both relativistic equivalent Schroedinger (including relativistic kinematics) and Dirac (second-order reduction) formalisms. Isospin will be introduced through the standard Lane model and a relativistic generalization of that model
Progress in the development of global medium-energy nucleon-nucleus optical model potentials
International Nuclear Information System (INIS)
Madland, D.G.
1997-01-01
Two existing global medium-energy nucleon-nucleus phenomenological optical model potentials are described and compared with experiment and with each other. The first of these employs a Dirac approach (second-order reduction) that is global in projectile energy and projectile isospin and applies to the target nucleus 208 Pb. The second of these employs a relativistic equivalent to the Schroedinger equation (including relativistic kinematics) that is global in projectile energy, projectile isospin, and target (Z,A). Finally, current work is described and the influence of the nuclear bound state problem (treated in relativistic mean field theory) on the Dirac scattering problem is mentioned. Spherical target nuclei are treated in the present work and strongly-collective target nuclei (rotational and vibrational) requiring coupled-channels approaches will be treated in a future paper. (author)
Induced Hyperon-Nucleon-Nucleon Interactions and the Hyperon Puzzle.
Wirth, Roland; Roth, Robert
2016-10-28
We present the first ab initio calculations for p-shell hypernuclei including hyperon-nucleon-nucleon (YNN) contributions induced by a similarity renormalization group transformation of the initial hyperon-nucleon interaction. The transformation including the YNN terms conserves the spectrum of the Hamiltonian while drastically improving model-space convergence of the importance-truncated no-core model, allowing a precise extraction of binding and excitation energies. Results using a hyperon-nucleon interaction at leading order in chiral effective field theory for lower- to mid-p-shell hypernuclei show a good reproduction of experimental excitation energies while hyperon separation energies are typically overestimated. The induced YNN contributions are strongly repulsive and we show that they are related to a decoupling of the Σ hyperons from the hypernuclear system, i.e., a suppression of the Λ-Σ conversion terms in the Hamiltonian. This is linked to the so-called hyperon puzzle in neutron-star physics and provides a basic mechanism for the explanation of strong ΛNN three-baryon forces.
International Nuclear Information System (INIS)
Yong Gaochan; Li Baoan; Chen Liewen
2007-01-01
Within a transport model it is shown that the neutron/proton ratio of squeezed-out nucleons perpendicular to the reaction plane, especially at high transverse momenta, in heavy-ion reactions induced by high energy neutron-rich nuclei can be a useful tool for studying the high density behavior of the nuclear symmetry energy
Norbury, John W.
1992-01-01
Single nucleon removal in relativistic and intermediate energy nucleus-nucleus collisions is studied using a generalization of Weizsacker-Williams theory that treats each electromagnetic multipole separately. Calculations are presented for electric dipole and quadrupole excitations and incorporate a realistic minimum impact parameter, Coulomb recoil corrections, and the uncertainties in the input photonuclear data. Discrepancies are discussed. The maximum quadrupole effect to be observed in future experiments is estimated and also an analysis of the charge dependence of the electromagnetic cross sections down to energies as low as 100 MeV/nucleon is made.
QCD inequalities for the nucleon mass and the free energy of baryonic matter.
Cohen, Thomas D
2003-07-18
The positivity of the integrand of certain Euclidean space functional integrals for two flavor QCD with degenerate quark masses implies that the free energy per unit volume for QCD with a baryon chemical potential mu(B) (and zero isospin chemical potential) is greater than the free energy with an isospin chemical potential mu(I)=(2 mu(B)/N(c)) (and zero baryon chemical potential). The same result applies to QCD with any number of heavy flavors in addition to the two light flavors so long as the chemical potential is understood as applying to the light quark contributions to the baryon number. This relation implies a bound on the nucleon mass: there exists a particle X in QCD (presumably the pion) such that M(N)> or =(N(c) m(X)/2 I(X)) where m(X) is the mass of the particle and I(X) is its isospin.
Fundamentals and applications of heavy ion collisions below 10 MeV/ nucleon energies
Prasad, R
2018-01-01
An up-to-date text, covering the concept of incomplete fusion (ICF) in heavy ion (HI) interactions at energies below 10 MeV/nucleon. Important concepts including the exciton model, the Harp Miller and Berne model, Hybrid model, Sum rule model, Hot spot model and promptly emitted particles model are covered in depth. It studies the ICF and PE-emission in heavy ion reactions at low energies using off-beam and in-beam experimental techniques. Theories of complete fusion (CF) of heavy ions based on Compound Nucleus (CN) mechanism of statistical nuclear reactions, details of the Computer code PACE4 based on CN mechanism, pre-equilibrium (PE) emission, modeling of (ICF) and their limits of application are discussed in detail.
Extended sudden approximation model for high-energy nucleon removal reactions
Energy Technology Data Exchange (ETDEWEB)
Carstoiu, F.; Sauvan, E.; Orr, N.A. [Caen Univ., Lab. de Physique Corpusculaire, Institut des Sciences de la Matiere et du Rayonnement, IN2P3-CNRS ISMRA, 14 (France); Carstoiu, F. [IFIN-HH, Bucharest-Magurele (Romania); Bonaccorso, A. [Istituto Nazionale di Fisica Nucleare, Pisa (Italy)
2004-04-01
A model based on the sudden approximation has been developed to describe high energy single nucleon removal reactions. Within this approach, which takes as its starting point the formalism of Hansen, the nucleon-removal cross section and the full 3-dimensional momentum distributions of the core fragments including absorption, diffraction, Coulomb and nuclear-Coulomb interference amplitudes, have been calculated. The Coulomb breakup has been treated to all orders for the dipole interaction. The model has been compared to experimental data for a range of light, neutron-rich psd-shell nuclei. Good agreement was found for both the inclusive cross sections and momentum distributions. In the case of {sup 17}C, comparison is also made with the results of calculations using the transfer-to-the-continuum model. The calculated 3-dimensional momentum distributions exhibit longitudinal and transverse momentum components that are strongly coupled by the reaction for s-wave states, whilst no such effect is apparent for d-waves. Incomplete detection of transverse momenta arising from limited experimental acceptances thus leads to a narrowing of the longitudinal distributions for nuclei with significant s-wave valence neutron configurations, as confirmed by the data. Asymmetries in the longitudinal momentum distributions attributed to diffractive dissociation are also explored. (authors)
Extended sudden approximation model for high-energy nucleon removal reactions
International Nuclear Information System (INIS)
Carstoiu, F.; Sauvan, E.; Orr, N.A.; Carstoiu, F.; Bonaccorso, A.
2004-04-01
A model based on the sudden approximation has been developed to describe high energy single nucleon removal reactions. Within this approach, which takes as its starting point the formalism of Hansen, the nucleon-removal cross section and the full 3-dimensional momentum distributions of the core fragments including absorption, diffraction, Coulomb and nuclear-Coulomb interference amplitudes, have been calculated. The Coulomb breakup has been treated to all orders for the dipole interaction. The model has been compared to experimental data for a range of light, neutron-rich psd-shell nuclei. Good agreement was found for both the inclusive cross sections and momentum distributions. In the case of 17 C, comparison is also made with the results of calculations using the transfer-to-the-continuum model. The calculated 3-dimensional momentum distributions exhibit longitudinal and transverse momentum components that are strongly coupled by the reaction for s-wave states, whilst no such effect is apparent for d-waves. Incomplete detection of transverse momenta arising from limited experimental acceptances thus leads to a narrowing of the longitudinal distributions for nuclei with significant s-wave valence neutron configurations, as confirmed by the data. Asymmetries in the longitudinal momentum distributions attributed to diffractive dissociation are also explored. (authors)
Energy Technology Data Exchange (ETDEWEB)
Chatrchyan, Serguei [Yerevan Physics Inst. (Armenia); et al.
2011-08-01
Jet production in PbPb collisions at a nucleon-nucleon center-of-mass energy of 2.76 TeV was studied with the CMS detector at the LHC, using a data sample corresponding to an integrated luminosity of 6.7 inverse microbarns. Jets are reconstructed using the energy deposited in the CMS calorimeters and studied as a function of collision centrality. With increasing collision centrality, a striking imbalance in dijet transverse momentum is observed, consistent with jet quenching. The observed effect extends from the lower cut-off used in this study (jet transverse momentum = 120 GeV/c) up to the statistical limit of the available data sample (jet transverse momentum approximately 210 GeV/c). Correlations of charged particle tracks with jets indicate that the momentum imbalance is accompanied by a softening of the fragmentation pattern of the second most energetic, away-side jet. The dijet momentum balance is recovered when integrating low transverse momentum particles distributed over a wide angular range relative to the direction of the away-side jet.
International Nuclear Information System (INIS)
Han Yinlu; Liang Haiying; Guo Hairui; Shen Qingbiao; Xu Yongli
2010-01-01
A set of new global phenomenological optical model potential parameters for the actinide region with incident nucleon energies from 1 keV up to 300 MeV is obtained. They are based on a smooth, unique functional form for the energy dependence of the potential depths and on physically constrained geometry parameters. The available experimental data including the neutron total cross sections, nonelastic cross sections, elastic scattering cross sections, elastic scattering angular distributions, and proton reaction cross sections and elastic scattering angular distributions of 232 Th and 238 U are used. The new nucleon global optical model potential parameters obtained are analyzed and used to analyze the experimental data of nucleon-actinide reactions. It is found that the present form of the global optical model potential could reproduce both the neutron and the proton experimental data.
Measurement of the transverse energy spectrum in proton-nucleon collisions
International Nuclear Information System (INIS)
Bettoni, D.
1988-01-01
The author describes a measurement of the transverse energy spectrum in proton-nucleon interactions carried out at the CERN SPS using the HELIOS spectrometer. The measurement is of particular interest in that it is performed in a rapidity region away from central rapidity, where experimental data is scarce. In this rapidity region very interesting physics is anticipated and the measurement of the proton-nucleon collisions is essential as a basis to understand the more complicated proton-nucleus and nucleus-nucleus interactions. Both these topics are part of the experimental program of HELIOS. The measurement was done using a deuterium target enclosed in an iron tube. The contribution to the transverse energy spectrum from the p-Fe events is discriminated against by reconstructing the primary interaction vertex using drift chamber information. The measured spectrum is corrected via Monte Carlo to deconvolute the effect of reinteractions. High spatial resolution and multi-track resolving power are achieved with the use of a cool gas, such that the electron characteristic energy is close to the thermal limit: this implies a small diffusion coefficient and a consequently good positional accuracy. Of vital importance are the low value of the drift velocity, the fast, differentiating electronics and a careful shaping of the electric field configuration to improve the isochrony of the drift collection. The author reports on the design and tests of drift chamber prototypes built along the above lines, with which a spatial accuracy of 0.06 mm and a double track resolution of 0.6 mm were measured. He also describes the final drift chamber system and its operation in HELIOS
Alpha-particle breakup at incident energies of 20 and 40 MeV/nucleon
International Nuclear Information System (INIS)
Wu, J.R.; Chang, C.C.; Holmgren, H.D.; Koontz, R.W.
1979-01-01
The breakup of alpha particles at incident energies of 20 and 40 MeV/nucleon on 27 Al, 58 Ni, 90 Zr, and 209 Bi has been studied. It was found that the breakup cross section decreases rapidly with increasing angles and increases with increasing target mass and incident energy. The total breakup yield, summed over all charged fragments, is approx.15--35% of the alpha-particle total reaction cross section, and has an approximate A/sup 1/3/ dependence. The ratios of breakup yields among different fragments are approximately p:d:t: 3 He approx. = 13:3:1:2, and are roughly independent of the incident energy and the target nucleus. These features suggest that the alpha-particle fragmentation is a peripheral process and is dominated by the properties of the incident projectile. A simple plane-wave alpha-particle breakup model gives a rather good description to the experimental data. In addition to the breakup deuteron peak at half of the beam energy, a second peak at quarter of the beam energy (or the same energy as the breakup proton peak) is observed. This peak might be due to a two-step breakup-pickup process
Exciton Binding Energy of Monolayer WS2
Zhu, Bairen; Chen, Xi; Cui, Xiaodong
2015-03-01
The optical properties of monolayer transition metal dichalcogenides (TMDC) feature prominent excitonic natures. Here we report an experimental approach to measuring the exciton binding energy of monolayer WS2 with linear differential transmission spectroscopy and two-photon photoluminescence excitation spectroscopy (TP-PLE). TP-PLE measurements show the exciton binding energy of 0.71 +/- 0.01 eV around K valley in the Brillouin zone.
Nucleon effective mass effects on the Pauli-blocking function
International Nuclear Information System (INIS)
Pina, S.R. de; Mesa, J.; Deppman, A.; Arruda-Neto, J.D.T.; Duarte, S.B.; Oliveira, E.C. de; Tavares, O.A.P.; Medeiros, E.L.; Goncalves, M.; Paiva, E. de
2002-01-01
The effects of nucleon effective mass on the Pauli-blocking function are worked out. We have shown that such effects on the quasi-deuteron mechanism of photonuclear absorption are rather relevant. The Pauli-blocking function has been evaluated by applying a Monte Carlo calculation particularly suitable for simulation of intranuclear cascade processes of intermediate-energy nuclear reactions. The nucleon binding in the photonuclear absorption mechanism is taken into account accordingly. (author)
Nucleon effective mass effects on the Pauli-blocking function
International Nuclear Information System (INIS)
Pina, S.R. de; Mesa, J.; Deppman, A.; Arruda-Neto, J.D.T.; Goncalves, M.; Paiva, E. de
2002-05-01
The effects of nucleon effective mass on the Pauli-blocking function are worked out. We have shown that such effects on the quasi-deuteron mechanism of photonuclear absorption are rather relevant. The pauli-blocking function has been evaluated by applying a Monte Carlo calculation particularly suitable for simulation of intranuclear cascade process of intermediate-energy nuclear reactions. The nucleon binding in the photonuclear absorption mechanism is accordingly taken into account. (author)
International Nuclear Information System (INIS)
Grange, P.; Lejeune, A.
1979-01-01
Two, three- and four-body contributions to the binding energy of nuclear matter are evaluated in the framework of the Bethe-Brueckner expansion. Special attention is devoted to the choice of the auxillary single particle field and to the potential diagrams at the level of three- and four-hole lines present when such a field is different from zero. Two nucleon-nucleon interactions are used: a model interaction V 1 and the Reid soft-core interaction. For V 1 our results are compared with those obtained from variational calculations; this comparison supports the reliability of the perturbative expansion. (Auth.)
Three nucleon interaction and nuclear composition
International Nuclear Information System (INIS)
Pandharipande, V.R.
1983-01-01
The author discusses results of some of the calculations carried out by J. Carlson, I. Lagaris, J. Lomnitz-Adler, R.A. Smith, R.B. Wiringa and himself to study the three nucleon interaction. The group has attempted to calculate the wavefunctions and binding energies of 3 H, 3 He, 4 He and nuclear matter, with the variational method, from a nonrelativistic Hamiltonian. Only nucleon degrees of freedom are retained in this Hamiltonian; the effects of other degrees of freedom are implicit in the two and three nucleon potentials. The author discusses further the calculations carried out, in collaboration with B. Friman, and R.B. Wiringa, to study the composition of nuclei. Nucleons interact by many processes including exchange of pions with or without excitation to isobar (Δ) states. Thus the nucleus contains pions being exchanged, and some nucleons in the Δ state. The group attempts to calculate the number and momentum distribution of these exchanged pions, and the fraction of time a nucleon in the nucleus is in the Δ state. 21 references, 4 figures
Binding energy of two-dimensional biexcitons
DEFF Research Database (Denmark)
Singh, Jai; Birkedal, Dan; Vadim, Lyssenko
1996-01-01
Using a model structure for a two-dimensional (2D) biexciton confined in a quantum well, it is shown that the form of the Hamiltonian of the 2D biexciton reduces into that of an exciton. The binding energies and Bohr radii of a 2D biexciton in its various internal energy states are derived...... analytically using the fractional dimension approach. The ratio of the binding energy of a 2D biexciton to that of a 2D exciton is found to be 0.228, which agrees very well with the recent experimental value. The results of our approach are compared with those of earlier theories....
Binding energies of hypernuclei and hypernuclear interactions
Energy Technology Data Exchange (ETDEWEB)
Bodmer, A.R. [Argonne National Lab., IL (United States)]|[Univ. of Illinois, Chicago, IL (United States). Dept. of Physics; Murali, S.; Usmani, Q.N. [Jamia Millia Islamia, New Delhi (India). Dept. of Physics
1996-05-01
In part 1 the effect of nuclear core dynamics on the binding energies of {Lambda} hypernuclei is discussed in the framework of variational correlated wave functions. In particular, the authors discuss a new rearrangement energy contribution and its effect on the core polarization. In part 2 they consider the interpretation of the {Lambda} single-particle energy in terms of basic {Lambda}-nuclear interactions using a local density approximation based on a Fermi hypernetted chain calculation of the A binding to nuclear matter. To account for the data strongly repulsive 3-body {Lambda}NN forces are required. Also in this framework they discuss core polarization for medium and heavier hypernuclei.
Binding energies of hypernuclei and hypernuclear interactions
International Nuclear Information System (INIS)
Bodmer, A.R.; Univ. of Illinois, Chicago, IL; Murali, S.; Usmani, Q.N.
1996-01-01
In part 1 the effect of nuclear core dynamics on the binding energies of Λ hypernuclei is discussed in the framework of variational correlated wave functions. In particular, the authors discuss a new rearrangement energy contribution and its effect on the core polarization. In part 2 they consider the interpretation of the Λ single-particle energy in terms of basic Λ-nuclear interactions using a local density approximation based on a Fermi hypernetted chain calculation of the A binding to nuclear matter. To account for the data strongly repulsive 3-body ΛNN forces are required. Also in this framework they discuss core polarization for medium and heavier hypernuclei
International Nuclear Information System (INIS)
Alsmiller, F.S.; Alsmiller, R.G. Jr.; Gabriel, T.A.; Lillie, R.A.; Barish, J.
1981-03-01
A fission channel has been added to the intranuclear-cascade-evaporation model of nuclear reactions so that this model may be used to obtain the differential particle production data that are needed to study the transport of medium-energy nucleons and pions through fissionable material. The earlier work of Hahn and Bertini on the incorporation of fission-evaporation competition into the intranuclear-cascade-evaporation model has been retained, and the statistical model of fission has been utilized to predict particle production from the fission process. Approximate empirically derived kinetic energies and deformation energies are used in the statistical model. The calculated number of emitted neutrons and residual nuclei distributions are in reasonable agreement with experimental data, but the number of emitted neutrons at the higher incident nucleon energies (approx. > 500 MeV) are sensitive to the level density parameter used. 9 figures, 2 tables
Axial structure of the nucleon
Energy Technology Data Exchange (ETDEWEB)
Veronique Bernard; Latifa Elouadrhiri; Ulf-G Meissner
2002-01-01
We review the current status of experimental and theoretical understanding of the axial nucleon structure at low and moderate energies. Topics considered include (quasi)elastic (anti)neutrino-nucleon scattering, charged pion electroproduction off nucleons and ordinary as well as radiative muon capture on the proton.
Nuclear energy density functional from chiral pion-nucleon dynamics revisited
Kaiser, N.; Weise, W.
2010-05-01
We use a recently improved density-matrix expansion to calculate the nuclear energy density functional in the framework of in-medium chiral perturbation theory. Our calculation treats systematically the effects from 1 π-exchange, iterated 1 π-exchange, and irreducible 2 π-exchange with intermediate Δ-isobar excitations, including Pauli-blocking corrections up to three-loop order. We find that the effective nucleon mass M(ρ) entering the energy density functional is identical to the one of Fermi-liquid theory when employing the improved density-matrix expansion. The strength F(ρ) of the ( surface-term as provided by the pion-exchange dynamics is in good agreement with that of phenomenological Skyrme forces in the density region ρ/2short-range spin-orbit interaction. The strength function F(ρ) multiplying the square of the spin-orbit density comes out much larger than in phenomenological Skyrme forces and it has a pronounced density dependence.
On light cluster production in nucleon induced reactions at intermediate energy
International Nuclear Information System (INIS)
Lacroix, D.; Blideanu, V.; Durand, D.
2004-09-01
A dynamical model dedicated to nucleon induced reaction between 30-150 MeV is presented. It considers different stages of the reaction: the approaching phase, the in-medium nucleon-nucleon collisions, the cluster formation and the secondary de-excitation process. The notions of influence area and phase-space exploration during the reaction are introduced. The importance of the geometry of the reaction and of the conservation laws are underlined. The model is able to globally reproduce the absolute cross sections for the emission of neutron and light charged particles for proton and neutron induced reactions on heavy and intermediate mass targets ( 56 Fe and 208 Pb). (authors)
Study of the Nuclear Transparency in $\\alpha$ + A Reactions at Energies $\\geq$ 12 GeV/nucleon
2002-01-01
The question about transparency is crucial for heavy ion reaction studies. If the transparency is low at 10-15 GeV per nucleon then very large baryon densities can be achieved in this energy range, maybe enough to produce quark-gluon plasma in U+U collisions. We propose to measure, event by event, pseudo-rapidity and multiplicity distributions of singly charged relativistic particles (@b~$>$~0.7) globally and in selected regions of rapidity as well as multiplicities of recoiling protons (30-400~Me charged nuclear fragments. These studies will explore general features of @a+A reactions at energies @$>$~12~GeV/nucleon. The main goal of the experiment is to measure the transparency of nuclear matter in this energy range. The detector will be nuclear emulsion.
Structure of the neutral current coupling in high energy neutrino--nucleon interactions
International Nuclear Information System (INIS)
Merritt, F.S.
1977-01-01
The primary objective of this experiment was to determine the Lorentz structure of the neutral current coupling--that is, to determine what combination of V-A and V+A (or possibly S, P, and T) components make up the neutral coupling. The experiment used the Fermilab narrow band neutrino beam to provide separated neutrino and antineutrino fluxes, each consisting of two energy bands at approximately equal to 55 and approximately equal to 150 GeV. Deep inelastic inclusive neutrino-nucleon interactions of the form ν(anti ν) + N = μ - (μ + ) + hadrons (CC event) ν(anti ν) + N = ν(anti ν) + hadrons (NC event) were observed in an instrumented steel target-calorimeter, which measured the total energy of the hadrons produced in each event. The neutral current coupling was determined by comparing the hadron energy distributions of neutrino and antineutrino neutral current events. An analysis of the charged-current data was carried out in order to determine the background of charged-current events with unobserved muons, and to provide a normalization for the neutral current data. Various parameterizations of the CC interaction were tested, and their effects on the neutral current analysis were studied in detail. The neutral current analysis indicates that, if only vector and axial-vector components exist, then the neutral current coupling lies between V and V-A. A pure scalar coupling is excluded. The data were compared to the Weinberg--Salam theory (extended to semileptonic interactions), and are in very good agreement with its predictions. Comparison of these data to the low energy Gargamelle data indicates consistency with a scaling hypothesis
High energy pp and anti-pp elastic scattering in nucleon valence core model
International Nuclear Information System (INIS)
Islam, M.M.; Fearnley, T.
1986-01-01
Connection between the valence core model and the effective QCD models of nucleon structure is pointed out. Also, implication of recent anti-pp differential cross section measurements at 53 GeV on our previous calculations is discussed
Energy Technology Data Exchange (ETDEWEB)
Rogozmski, A [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires
1952-07-01
The celerity curves, pulse and wavelength of De Broglie for a nucleon (proton or neutron) have been calculated and traced accordingly to its kinetic energy. (M.B.) [French] Les courbes de vitesses, d mpulsion et de longueur d nde de Broglie d n nucleon (proton ou neutron) ont ete calcule et trace en fonction de son energie cinetique. (M.B.)
Electromagnetic interactions of nucleons and nuclei at low energy and momentum transfer
International Nuclear Information System (INIS)
Arenhoevel, H.
1994-01-01
In these lectures I concentrate on the manifestation of subnuclear degrees of freedom in terms of meson and isobar degrees of freedom in electromagnetic processes where their presence usually is described in terms of so-called exchange or interaction currents. In Section 2 I first discuss the general properties of the electromagnetic interaction, the gauge conditions and low-energy theorems which follow from gauge invariance, the charge and current density operators for a non-relativistic system of nucleons and the Siegert theorem. In Section 3 I sketch the basic ideas and construction methods for the exchange current operators as effective operators and in Section 4 the model of nuclear isobar configurations introducing explicitly isobar degrees of freedom into the nuclear wave function. The general features of one- and two-photon processes are discussed in Section 5. First the expressions for the cross sections of photoabsorption and electron scattering are reviewed. As a specific but important example, I then discuss the two-body break-up of the deuteron since it permits the cleanest analysis and provides one of the best evidences for the presence of subnuclear degrees of freedom due to its simple two-body structure within the classical nuclear physics framework. This is a unique situation because in more complex nuclei the analysis is often hampered by presently still unavoidable approximations of the many-body problem. I furthermore discuss the role of meson exchange currents in the photonuclear TRK sum rule, in particular, I carefully analyse what determines the enhancement. This section ends with a brief discussion of elastic photon scattering with special emphasis on the low-energy theorem for the scattering amplitude and the sum rule relations for the low-energy parameters. (orig.)
Composite nucleon approach to the deuteron problem
International Nuclear Information System (INIS)
Agarwal, B.K.
1975-01-01
A composite model is suggested for the nucleons by assuming a long-range strong gluon force between a diquark boson B and a quark A. In the proton, A is trapped inside B in an oscillator potential; and in the neutron, A is on the surface of B in a hydrogenlike state. Nucleon form factors are obtained in agreement with experiments. The model contains a mechanism for a large effective mass of the quark A. When B is identified with π and A with μ, one can fix the gluon charge value and obtain the magnetic moments of the proton and neutron. The (μπ) atomic model for the nucleon can be used to construct the deuteron on a hydrogen molecule model. It leads to values for the binding energy, electric quadrupole moment, and form factors of the deuteron that are in agreement with experiments
Nucleus-nucleus interaction constants at energies of 0.1-1.0 GeV/nucleon
International Nuclear Information System (INIS)
Dudkin, V.E.; P'yanov, I.I.; Stepnov, V.D.
1979-01-01
A method for calculating nucleus-nuclear reactions being a further development of the cascade model is proposed. The nucleus-nucleus interaction is represented as a superposition of a series of synchronous cascades initiated by nucleous and α-clusters getting into the nuclei overlapping region. Determination of an interaction partner and calculation of an elementary nucleon and α-cluster collision act are carried out using the same method as for calculation of the nucleon-nuclear cascade. Inelastic channels are not considered. The cross section values of cascade particle interaction, as well as of free particle interaction are given from the published literature. The experiment for verification of the calculation method is carried out. An emulsion chamber of the 0.3 l volume has been exposed at the 35 km height in the vicinity of the 64 deg nothern latitude during 8.5 hr. 223 disintegrations of nuclear emulsion by cosmic radiation nuclei at the 0.1-1.0 GeV/nucleon energy and the >2 charge are investigated. 147 interactions on photoemulsion light nuclei are singled out from these disintegrations. The average multiplicity of all the charged pions is 0.22+-0.05 for light and 0.44+-0.09 for heavy photoemulsion nuclei. The calculation is carried out for nitrogen nuclei interaction at the 0.35 GeV/nucleon energy. Parametric analysis of the calculation method has shown that the clusterization coefficients and the nuclear parameter effect secondary particle multiplicity (SPM) and weakly influence on their energy and angular distributions. The nuclear parameter change from 1.1 to 1.6 F decreases average SPM in different energy ranges down to 25-40%. The comparison of the calculation data with the experimental one obtained in the given paper and other ones, shows satisfactory agreement both for differential and average characteristics of secondary charged particles
Recent Progresses in Ab-Initio Studies of Low-Energy Few-Nucleon Reactions of Astrophysical Interest
Marcucci, Laura E.
2017-03-01
We review the most recent theoretical studies of nuclear reactions of astrophysical interest involving few-nucleon systems. In particular, we focus on the radiative capture of protons by deuterons in the energy range of interest for Big Bang Nucleosynthesis. Related to this, we will discuss also the most recent calculation of tritium β -decay. Two frameworks will be considered, the conventional and the chiral effective field theory approach.
International Nuclear Information System (INIS)
Scott, D.K.
1978-03-01
Some initial experiments in the intermediate energy region between 10 and 200 MeV/nucleon, which is largely unexplored and poorly understood is considered as regards some initial experiments in this energy region. Included are the emission of complex fragments, localization in heavy ion reactions, coincidence experiments between light and heavy fragments, and the emission of light particles in heavy ion collisions. Some initial results in the region between 20 and 100 MeV/nucleon are presented. 41 references
International Nuclear Information System (INIS)
Guiasu, I.
1978-01-01
The elastic γ-nucleon scattering represents an indirect powerful method for the nucleon structure investigation. Some theoretical aspects of this problem are treated in the presented thesis. After a general introduction into the subject and a short review of the up-to-date literature, the first chapter contains kinematics and dynamical preliminaries of reaction γ+N→γ+N. In chapter II, the low energy theorems are discussed and extended up to six power in the photon laboratory energies, ω; the six structure dependent constants which appear in the differential cross section in this order are defined and computed, and an extraction for the proton electromagnetic polarizabilities α,β from the experimental data is performed. A new dispersive analysis of the γ+N→γ+N process at photon laboratory energies lower than 450 Mev is introduced and used for numerical calculation in chapter III; some improvements are obtained in the comparison with the experimental data, with respect to other previous calculations. In the last chapter, two different sum rules for the difference (α-β) are established and numerically computed - these theoretical predictions agree with the values extracted from experience; based on the analyticity properties of the invariant amplitudes, an inequality is written down connecting an integral over the differential cross section of the process and the static properties of the nucleon (mass, charge, anomalous magnetic moment). (author)
Energy Technology Data Exchange (ETDEWEB)
Farag, M.Y.H.; Esmael, E.H. [Cairo University, Physics Department, Faculty of Science, Giza (Egypt); Maridi, H.M. [Cairo University, Physics Department, Faculty of Science, Giza (Egypt); Taiz University, Physics Department, Faculty of Applied Science, Taiz (Yemen)
2012-11-15
The proton elastic scattering data on some light exotic nuclei, namely, {sup 6,} {sup 8}He, {sup 9,} {sup 11}Li, and {sup 10,} {sup 11,} {sup 12}Be, at energies below than 100MeV/nucleon are analyzed using the single folding optical model. The real, imaginary, and spin-orbit parts of the optical potential (OP) are constructed only from the folded potentials and their derivatives using M3Y effective nucleon-nucleon interaction. These OP parts, their renormalization factors and their volume integrals are studied. The surface and spin-orbit potentials are important to fit the experimental data. Three model densities for halo nuclei are used and the sensitivity of the cross-sections to these densities is tested. The imaginary OP within high-energy approximation is used and compared with the single folding OP. This OP with few and limited fitting parameters, which have systematic behavior with incident energy, successfully describes the proton elastic scattering data with exotic nuclei. (orig.)
Semiphenomenological studies of the ground state binding energies of hypernuclei
International Nuclear Information System (INIS)
Mian, M.
1987-01-01
We show that the binding energies of /sub Λ/ 5 He and p-shell hypernuclei can be satisfactorily explained in the folding model approach using a density dependent effective ΛN interaction. Our analysis predicts a very reasonable value of the range of the ΛN interaction. The calculated value of B/sub Λ/ of /sub Λ/ 7 Li using the cluster model density for 6 Li and the best fit parameters of this potential supports the view that 6 Li possesses an α-d cluster structure. Using this potential we also determine the average size parameter (a 0 ) of the oscillator shell model density of nucleons in Nnot =Z core nuclei from fitting the B/sub Λ/ values of the corresponding hypernuclei. The effect of different forms of density distribution of core nuclei on the values of potential parameters is investigated and is found to be very small. As regards the form of density dependence, a rho/sup 2/3/ form is found to be the most appropriate for this purpose and is used throughout this work. Other forms do not give a satisfactory account of the data
Energy Technology Data Exchange (ETDEWEB)
He, Zhi-Yong [Caen Univ., 14 (France). Lab. de Physique Corpusculaire; [Academia Sinica, Lanzhou, GS (China). Inst. of Modern Physics; Peter, J; Angelique, J C; Bizard, G; Brou, R; Cussol, D [Caen Univ., 14 (France). Lab. de Physique Corpusculaire; Auger, A; Cabot, C; Crema, E [Grand Accelerateur National d` Ions Lourds (GANIL), 14 - Caen (France); Buta, A [Caen Univ., 14 (France). Lab. de Physique Corpusculaire; [Institute of Atomic Physics, Bucharest (Romania)] [and others
1996-09-01
Experimental measurement and theoretical comparison of collective flow can give important information about the nuclear equation of state (EOS) and the in-medium nucleon-nucleon cross section. Experimental measurements of {sup 64}Zn+{sup 27}Al collision from 35 to 79 MeV/u with the 4{pi} array MUR=TONNEAU are presented. The results are compared to BUU calculations. (K.A.).
International Nuclear Information System (INIS)
Gel'fand, E.K.; Man'ko, B.V.; Serov, A.Ya.; Sychev, B.S.
1979-01-01
A complex of programs for modelling various radiation situations at high energy proton accelerators is considered. The programs are divided into there main groups according to their purposes. The first group includes programs for preparing constants describing the processes of different particle interaction with a substanc The second group of programs calculates the complete function of particle distribution arising in shields under irradiation by high energy nucleons. Concrete radiation situations arising at high energy proton accelerators are calculated by means of the programs of the third group. A list of programs as well as their short characteristic are given
Binding Energy and Equilibrium of Compact Objects
Directory of Open Access Journals (Sweden)
Germano M.
2014-04-01
Full Text Available The theoretical analysis of the existence of a limit mass for compact astronomic ob- jects requires the solution of the Einstein’s equations of g eneral relativity together with an appropriate equation of state. Analytical solutions exi st in some special cases like the spherically symmetric static object without energy sou rces that is here considered. Solutions, i.e. the spacetime metrics, can have a singular m athematical form (the so called Schwarzschild metric due to Hilbert or a nonsingula r form (original work of Schwarzschild. The former predicts a limit mass and, conse quently, the existence of black holes above this limit. Here it is shown that, the origi nal Schwarzschild met- ric permits compact objects, without mass limit, having rea sonable values for central density and pressure. The lack of a limit mass is also demonst rated analytically just imposing reasonable conditions on the energy-matter densi ty, of positivity and decreas- ing with radius. Finally the ratio between proper mass and to tal mass tends to 2 for high values of mass so that the binding energy reaches the lim it m (total mass seen by a distant observer. As it is known the negative binding energ y reduces the gravitational mass of the object; the limit of m for the binding energy provides a mechanism for stable equilibrium of any amount of mass to contrast the gravitatio nal collapse.
The role of collision terms for nucleon emission in intermediate energy heavy ion reactions
International Nuclear Information System (INIS)
Gregoire, C.; Scheuter, F.; Remaud, B.; Sebille, F.
1984-01-01
A semi-classical description of heavy ion collisions is developed with a particular attention to the nucleon flux from one partner through the other one. The phase-space extension of the nucleons is explicitly treated by means of the Wigner transform of the density matrix. Its dynamical evolution is obtained by solving the Landau-Vlasov equation, where collision terms are explicitely introduced. As a matter of fact, the experimental nucleon spectra usually described by a thermal source with an intermediate velocity (around vsub(beam)/2) are interpreted in our framework by the coexistence of one-and two-body dissipation. Multi-differential cross-sections d 2 σ/dEdΩ are computed for the 12 C(86MeV/u) + 12 C system and are compared with the experimental data. Comparisons are also given for the 16 O (20 MeV/u) + 197 Au system
On light cluster production in nucleon induced reactions at intermediate energy
Energy Technology Data Exchange (ETDEWEB)
Lacroix, D.; Blideanu, V.; Durand, D
2004-09-01
A dynamical model dedicated to nucleon induced reaction between 30-150 MeV is presented. It considers different stages of the reaction: the approaching phase, the in-medium nucleon-nucleon collisions, the cluster formation and the secondary de-excitation process. The notions of influence area and phase-space exploration during the reaction are introduced. The importance of the geometry of the reaction and of the conservation laws are underlined. The model is able to globally reproduce the absolute cross sections for the emission of neutron and light charged particles for proton and neutron induced reactions on heavy and intermediate mass targets ({sup 56}Fe and {sup 208}Pb). (authors)
Induced hyperon-nucleon-nucleon interactions and the hyperon puzzle
Energy Technology Data Exchange (ETDEWEB)
Wirth, Roland; Roth, Robert [Institut fuer Kernphysik, TU Darmstadt (Germany)
2016-07-01
There is a strong experimental and theoretical interest in determining the structure of hypernuclei and the effect of strangeness in strongly interacting many-body systems. Recently, we presented the first calculations of hypernuclei in the p shell from first principles. However, these calculations showed either slow convergence with respect to model-space size or, when the hyperon-nucleon potential is transformed via the Similarity Renormalization Group, strong induced three-body terms. By including these induced hyperon-nucleon-nucleon (YNN) terms explicitly, we get precise binding and excitation energies. We present first results for p-shell hypernuclei and discuss the origin of the YNN terms, which are mainly driven by the evolution of the Λ-Σ conversion terms. We find that they are tightly connected to the hyperon puzzle, a long-standing issue where the appearance of hyperons in models of neutron star matter lowers the predicted maximum neutron star mass below the bound set by the heaviest observed objects.
Directory of Open Access Journals (Sweden)
H. Mariji
2016-01-01
Full Text Available The nucleon single-particle energies (SPEs of the selected nuclei, that is, O16, Ca40, and Ni56, are obtained by using the diagonal matrix elements of two-body effective interaction, which generated through the lowest-order constrained variational (LOCV calculations for the symmetric nuclear matter with the Aυ18 phenomenological nucleon-nucleon potential. The SPEs at the major levels of nuclei are calculated by employing a Hartree-Fock inspired scheme in the spherical harmonic oscillator basis. In the scheme, the correlation influences are taken into account by imposing the nucleon effective mass factor on the radial wave functions of the major levels. Replacing the density-dependent one-body momentum distribution functions of nucleons, n(k,ρ, with the Heaviside functions, the role of n(k,ρ in the nucleon SPEs at the major levels of the selected closed shell nuclei is investigated. The best fit of spin-orbit splitting is taken into account when correcting the major levels of the nuclei by using the parameterized Wood-Saxon potential and the Aυ18 density-dependent mean field potential which is constructed by the LOCV method. Considering the point-like protons in the spherical Coulomb potential well, the single-proton energies are corrected. The results show the importance of including n(k,ρ, instead of the Heaviside functions, in the calculation of nucleon SPEs at the different levels, particularly the valence levels, of the closed shell nuclei.
Light hypernuclei and hyperon-nucleon interaction
International Nuclear Information System (INIS)
Carlson, J.; Gibson, B.F.
1990-01-01
Light Hypernuclei are a vital testing ground for our understanding of the Hyperon-Nucleon interaction. We have performed microscopic calculations of four and five-body hypernuclei using the Nijmegen nucleon-nucleon and hyperon-nucleon interactions. Our calculations include explicit Sigma degrees of freedom. These degrees of freedom are quite important since, in contrast to the Δ - N mass difference of ∼ 300 MeV, the Σ resonance is only about 80 MeV above the Λ. In addition, although there is no one-pion-exchange in the ΛN diagonal channel, this longest-range term does contribute to the transition ΛN - ΣN interaction. Our variational calculations show that the A=4 spin 0 ground state binding energy is well reproduced by the Nijmegen HN integration, a one-boson exchange model fit to the available scattering data. The spin 1 excited state and the A=5 ground state are strongly underbound, however. We demonstrate the importance of the strong tensor terms of the Nijmegen model, particularly those in the transition channel, in obtaining this result. The limited data currently available for hyperon-nucleon scattering must be greatly improved in order to place reasonable constraints on the interaction. 12 refs., 3 figs., 3 tabs
Light hypernuclei and hyperon-nucleon interaction
Energy Technology Data Exchange (ETDEWEB)
Carlson, J.; Gibson, B.F.
1990-01-01
Light Hypernuclei are a vital testing ground for our understanding of the Hyperon-Nucleon interaction. We have performed microscopic calculations of four and five-body hypernuclei using the Nijmegen nucleon-nucleon and hyperon-nucleon interactions. Our calculations include explicit Sigma degrees of freedom. These degrees of freedom are quite important since, in contrast to the {Delta} {minus} N mass difference of {approx} 300 MeV, the {Sigma} resonance is only about 80 MeV above the {Lambda}. In addition, although there is no one-pion-exchange in the {Lambda}N diagonal channel, this longest-range term does contribute to the transition {Lambda}N {minus} {Sigma}N interaction. Our variational calculations show that the A=4 spin 0 ground state binding energy is well reproduced by the Nijmegen HN integration, a one-boson exchange model fit to the available scattering data. The spin 1 excited state and the A=5 ground state are strongly underbound, however. We demonstrate the importance of the strong tensor terms of the Nijmegen model, particularly those in the transition channel, in obtaining this result. The limited data currently available for hyperon-nucleon scattering must be greatly improved in order to place reasonable constraints on the interaction. 12 refs., 3 figs., 3 tabs.
Coulomb effect in the tri nucleon system in an optical potential model
International Nuclear Information System (INIS)
Adhikari, S.K.; Delfino, A.; Maryland Univ., College Park, MD
1993-02-01
A Saxon-Woods type nucleon-deuteron optical potential in suggested and applied numerically to the study of the static Coulomb effect in the low-energy tri nucleon system. In particular, the observed correlations between the static Coulomb energy of 3 He and the triton binding energy, and that between the neutron-deuteron and the proton-deuteron scattering lengths are simulated with this optical potential. In view of this study and a previous one employing two other effective potentials its is unlikely that a a study of the usual static Coulomb effect in the tri nucleon system will reveal new and meaningful physics. (author). 12 refs, 2 figs
Symbolic computation of the Hartree-Fock energy from a chiral EFT three-nucleon interaction at N2LO
International Nuclear Information System (INIS)
Gebremariam, B.; Bogner, S.K.; Duguet, T.
2010-01-01
We present the first of a two-part Mathematica notebook collection that implements a symbolic approach for the application of the density matrix expansion (DME) to the Hartree-Fock (HF) energy from a chiral effective field theory (EFT) three-nucleon interaction at N 2 LO. The final output from the notebooks is a Skyrme-like energy density functional that provides a quasi-local approximation to the non-local HF energy. In this paper, we discuss the derivation of the HF energy and its simplification in terms of the scalar/vector-isoscalar/isovector parts of the one-body density matrix. Furthermore, a set of steps is described and illustrated on how to extend the approach to other three-nucleon interactions. Program summary: Program title: SymbHFNNN; Catalogue identifier: AEGC v 1 0 ; Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEGC_v1_0.html; Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland; Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html; No. of lines in distributed program, including test data, etc.: 96 666; No. of bytes in distributed program, including test data, etc.: 378 083; Distribution format: tar.gz; Programming language: Mathematica 7.1; Computer: Any computer running Mathematica 6.0 and later versions; Operating system: Windows Xp, Linux/Unix; RAM: 256 Mb; Classification: 5, 17.16, 17.22; Nature of problem: The calculation of the HF energy from the chiral EFT three-nucleon interaction at N 2 LO involves tremendous spin-isospin algebra. The problem is compounded by the need to eventually obtain a quasi-local approximation to the HF energy, which requires the HF energy to be expressed in terms of scalar/vector-isoscalar/isovector parts of the one-body density matrix. The Mathematica notebooks discussed in this paper solve the latter issue. Solution method: The HF energy from the chiral EFT three-nucleon interaction at N 2 LO is cast into a form suitable for an automatic
Excitation energy partition in deeply inelastic collisions between 40Ar and Ag at 27 MeV per nucleon
International Nuclear Information System (INIS)
Borderie, B.; Rivet, M.F.; Cabot, C.; Fuchs, H.; Gardes, D.; Hanappe, F.; Jouan, D.; Montoya, M.
1991-01-01
The dynamics of the two partners produced in dissipative collisions has been experimentally studied for the system 40 Ar+Ag at 27 MeV per nucleon. Primary masses of the fragments can then be calculated; the excitation energy partition between the two fragments is derived from the number of particles evaporated by each fragment. We found that this division evolves from equipartition to a repartition close to thermal equilibrium in the excitation energy range 300-350 MeV or interaction times 5-10x10 -22 s. (orig.)
International Nuclear Information System (INIS)
Bond, A.
1977-01-01
The present position of nucleonic techniques for process measurements, is considered from the technical and cost viewpoints. Systems considered include level, density, thickness (including coating thickness), moisture, and sulphur in hydrocarbons gauges and also belt weighers. The advantages of such systems are discussed and the cost-benefit position considered. The combination of nucleonic measuring equipment with a microcomputer is examined. (U.K.)
International Nuclear Information System (INIS)
Strugalski, Z.
1982-01-01
Asymmetry in nucleon emission intensity angular distributions relatively to the hadron deflection plane and to two planes normal to it and related to it uniquely is analyzed, using appropriate experimental data on pion-xenon nucleus collisions at 3.5 GeV/c momentum. Quantative characteristics of the asymmetries found are presented in tables and on figures
Exchange currents in low-energy nucleon capture by 3He
International Nuclear Information System (INIS)
Wervelman, Rob.
1991-01-01
The studies described in this thesis concern absolute cross-section measurements of the radiative neutron capture reactions 3 He (n,γ) 4 He and 3 He(n,γγ) 4 He, and are complements with shell-model calculations on the radiative thermal neutron capture reaction by 3 He and on the weak 3 He(p,e + ν e ) 4 He reaction. The experiments have been performed at two neutron energies, with sub-thermal neutrons where s-wave capture is dominant, and with a quasi-monochromatic 24.5 keV neutron beam (p-wave capture). It has been found that the thermal neutron capture cross section of 3 He is 55±3 μb. Measured at 24.5 keV-neutron energy, the radiative capture cross section for p-wave neutrons turned out to be 9.1±0.8 μb. A measurement on the double-photon reaction 3 He(n th ,γγ) has yielded a cross-section value of 30±80 μb. In the theoretical part of the work a standard model of nuclear weak and electromagnetic interaction currents, consisting of a one-body impulse approximation and a two-body meson-exchange current part, has been applied to the process of nucleon capture by 3 He. Within the framework of a (0+2) (h/2π)ω shell-model calculation, using Sussex matrix elements for the 3 He and 4 He ground state wave functions, the empirical radiative cross sections for thermal neutrons of 3 He could be reproduced with satisfactory agreement. The total MEC correction to the radiative thermal neutron capture cross section is rather small because large cancellations occur between the various contributions. In the 3 He(p,e + ν e ) 4 He reaction meson-exchange contributions enlarge the astrophysical S-factor by more than a factor two. The matrix element ratio of the weak 3 He+p and the electromagnetic 3 He+n reaction is calculated to be (4.3±0.6)g A C 0 . This ratio has been found to be fairly insensitive to the percentage D-state admixtures in the 3 He and 4 He ground state wave functions. (author). 129 refs.; 24 figs.; 5 tabs
International Nuclear Information System (INIS)
Besliu, Calin; Jipa, Alexandru; Iliescu, Bogdan; Felea, Daniel
2002-01-01
Some new aspects on the multifragmentation processes in nucleus-nucleus and nucleon-nucleus collisions at high energies are discussed in this work. Experimental data obtained in international collaborations (for example, MULTI Collaboration with KEK Tsukuba (Japan) and SKM 200 Collaboration with JINR Dubna (Russia)) are used to discuss new mechanisms in the target nucleus fragmentation. Correlations with stopping power, participant region size and energy density are included. Comparisons of the experimental results with the predictions of a phenomenological geometric model of intermediate mass fragment multiplicity, caloric curves and angular distributions are also presented. These results are used for global description of the multifragmentation processes in nucleon-nucleus and nucleus-nucleus collisions at relativistic energies. The size of the participant region and the average intermediate mass fragments multiplicity are taken into consideration using the free space probability. A few correlations between the deposited energy in the participant region and stability state of the intermediate mass fragments are presented in this work. The importance of the collision geometry in the multifragmentation processes is stressed. The results suggest different time moments for the incident nucleus fragmentation and for the target nucleus fragmentation. The associated entropies are distinct. (authors)
Spin polarization of 34Al fragments produced by nucleon pickup at intermediate energies
International Nuclear Information System (INIS)
Turzo, K.; Himpe, P.; Borremans, D.; Mallion, S.; Neyens, G.; Vermeulen, N.; Yordanov, D.; Balabanski, D.L.; Belier, G.; Daugas, J.M.; Georgiev, G.; Oliveira de Santos, F.; Matea, I.; Stodel, Ch.; Penionzhkevich, Yu. E.
2006-01-01
The polarization of 34 Al fragments, produced by single neutron pickup from a 9 Be target by a 36 S projectile at 77.5 MeV/nucleon, have been observed at GANIL via the detection of resonantly destroyed β-asymmetry. The reaction-induced polarization is deduced using a tentative spin/parity assignment for the 34 Al ground state. A positive polarization was measured near the peak of the 34 Al yield curve. A kinematical model based on the spectator-participant model for projectile fragmentation reactions has been extended in order to take into account the features of pickup reactions, i.e., the picked-up nucleon having an average momentum equal to the Fermi momentum and aligned along the incident beam direction. The trend-line in the observed spin-orientation is very well reproduced by this model
The transverse-energy distributions of 32S-nucleus collisions at 200 GeV per nucleon
International Nuclear Information System (INIS)
Akesson, T.; Atherton, H.; Beker, H.; Bettoni, D.; Boeggild, H.; Dederichs, K.; Devenish, R.C.E.; En'yo, H.; Esten, M.J.; Fabjan, C.W.; Mazzoni, M.A.; Nilsson, S.; Piuz, F.; Poulard, G.; Price, M.; Russ, J.; Schukraft, J.; Sekimoto, M.; Seman, M.; Shotton, P.; Sletten, H.; Thodberg, H.H.; Veenhof, R.; Wigmans, R.; Willis, W.; Almehed, S.; Haglund, R.; Hedeberg, V.; Johansson, S.; Loerstad, B.; Mjoernmark, U.; Angelis, A.L.S.; Dodd, J.R.; Lessard, L.; McCubbin, M.L.; Armenise, N.; Muciaccia, M.T.; Simone, S.; Aubry, P.; Beaudoin, G.; Beaulieu, J.M.; Depommier, P.; Lounis, A.; Bartels, H.W.; Drees, A.; Fischer, P.; Glaessel, P.; Goerlach, U.; Hoelscher, A.; Kroh, V.; Neubert, M.; Pfeiffer, A.; Specht, H.J.; Benary, O.; Dagan, S.; Heifetz, R.; Marzari-Chiesa, A.; Masera, M.; Oren, Y.; Bisi, V.; Giubellino, P.; Ramello, L.; Riccati, L.; Blevis, I.; Fraenkel, Z.; Tserruya, I.; Cleland, W.; Clemen, M.; Collick, B.; Murray, M.; Park, Y.M.; Thompson, J.; Corriveau, F.; Hamel, L.A.; Jarlskog, G.; Lamarche, F.; Leroy, C.; Mazzucato, E.; Sirois, Y.; Dell'Uomo, S.; Di Liberto, S.; Meddi, F.; Rosa, G.; DiGiacomo, N.; Van Hecke, H.; Jacak, B.; McGaughey, P.; Sondheim, W.; Sunier, J.; Dolgoshein, B.; Kalinovski, A.; Kantserov, A.; Nevski, P.; Smirnov, S.; Sumarokov, A.; Tcherniatin, V.; Tikhomirov, V.; Berlandsson, B.; Sellden, B.; Gaidot, A.; Gibrat-Debu, F.; London, G.; Pansart, J.P.; Vasseur, G.; McCubbin, N.A.; Romano, G.; Sidorov, V.
1988-01-01
Transverse-energy distributions have been measured for the collisions of the 32 S nucleus with Al, Ag, W, Pt, Pb and U target nuclei, at an incident energy of 200 GeV per nucleon. The shapes of these distribution reflect the geometry of the collisions, including the deformation effects. For central collisions, the transverse-energy production in the region -0.1 lab 0.5 , where A is the atomic mass number of the target. This increase is accompanied by a relative depletion in the forward region η lab > 2.9. These results are compared with those obtained under similar conditions with incident 16 O nuclei. A comparison is also made with the predictions of a Monte Carlo generator based on the dual parton model. Finally, we give estimates of the energy density reached and its dependence on the atomic mass number of the projectile. (orig.)
Coupled channels Marchenko inversion for nucleon-nucleon potentials
International Nuclear Information System (INIS)
Kohlhoff, H.; Geramb, H.V. von
1994-01-01
Marchenko inversion is used to determine local energy independent but channel dependent potential matrices from optimum sets of experimental phase shifts. 3 SD 1 and 3 PF 2 channels of nucleon-nucleon systems contain in their off-diagonal potential matrices explicitly the tensor force for T = 0 and 1 isospin. We obtain, together with single channels, complete sets of quantitative nucleon-nucleon potential results which are ready for application in nuclear structure and reaction analyses. The historic coupled channels inversion result of Newton and Fulton is revisited. (orig.)
Semi-phenomenological model of the nucleon-nucleon interaction
International Nuclear Information System (INIS)
Houriet, A.; Bagnoud, Y.
1977-01-01
A nucleon with isobars is used to elaborate a model of the nucleon-nucleon interaction at low energy (Esub(CM) 2 sub(r), the pion-nucleon renormalized coupling constant. The model establishes a very good coordination for deuteron and p-p scattering-polarization measurements ( 1 K 0 , 1 D 2 , 1 G 4 phase shifts), and permits the determination of f 2 sub(r) for every independent experimental value. For 21 such values, the mean value 2 sub(r)>=0.0785 with Δf 2 sub(r)=0.0024(3%) is obtained. (Auth.)
International Nuclear Information System (INIS)
Simon, G.G.
1978-01-01
In this thesis results of measurements of the differential cross sections of the elastic and inelastic electron deuteron scattering are presented. The data were taken at several scattering angles and in the electron energy range of 150 MeV up to 320 MeV. The extracted form factors and structure functions are compared with theoretical results which are sensitive to details of nucleon structure and of the nucleon-nucleon forces. (FKS)
Nucleon-nucleon forces in the quark compound bag model and few-nucleon systems
International Nuclear Information System (INIS)
Kalashnikova, Yu.S.; Narodetskij, I.M.
1984-01-01
Role of quark-gluon degrees of freedom is discussed in nucleon-nucleon scattering at low and intermediate energies. It is shown that the existence of six-quark hags fixes the form of NN potential at small distances, which leads to the P-matrix satisfying the criterion of Jaffe and Low. The dynamical model of three-nucleon system is discussed taking into accoint the contribution of six-quark bags
International Nuclear Information System (INIS)
Gebremariam, B.; Bogner, S.K.; Duguet, T.
2011-01-01
The density matrix expansion (DME) of Negele and Vautherin is a convenient tool to map finite-range physics associated with vacuum two- and three-nucleon interactions into the form of a Skyrme-like energy density functional (EDF) with density-dependent couplings. In this work, we apply the improved formulation of the DME proposed recently in (arXiv:0910.4979) by Gebremariam et al. to the non-local Fock energy obtained from chiral effective field theory (EFT) two-nucleon (NN) interactions at next-to-next-to-leading-order (N 2 LO). The structure of the chiral interactions is such that each coupling in the DME Fock functional can be decomposed into a coupling constant arising from zero-range contact interactions and a coupling function of the density arising from the universal long-range pion exchanges. This motivates a new microscopically-guided Skyrme phenomenology where the density-dependent couplings associated with the underlying pion-exchange interactions are added to standard empirical Skyrme functionals, and the density-independent Skyrme parameters subsequently refit to data. A link to a downloadable Mathematica notebook containing the novel density-dependent couplings is provided.
Unveiling the strangeness secrets: low-energy kaon-nucleon/nuclei interactions studies at DAΦNE
Directory of Open Access Journals (Sweden)
Curceanu C.
2014-03-01
Full Text Available The DAΦNE electron-positron collider at the Laboratori Nazionali di Frascati of INFN, Italy has made available a unique quality low-energy negatively charged kaons “beam”, which is used to unveil the secrets of the kaon-nucleon/nuclei interactions at low energies by the SIDDHARTA-2 and AMADEUS experiments. SIDDHARTA has already performed unprecedented precision measurements of kaonic atoms, and is being presently upgraded, as SIDDHARTA-2, to approach new frontiers. The AMADEUS experiment plans to perform in the coming years precision measurements on kaon-nuclei interactions at low-energies, to study the possible formation of kaonic nuclei, of the Λ(1405 and of many other processes involving strangeness.
The reaction 12C + 12C at bombarding energies from 5 to 10 MeV per nucleon
International Nuclear Information System (INIS)
Morsad, A.
1986-01-01
The reaction 12 C + 12 C has been studied for energies ranging from E LAB = 60 to 120 MeV. The excitation functions and angular distributions were obtained for the elastic (0 + , 0 + ) and inelastic (2 + , 0 + ), (2 + , 2 + ) channels as well as for the transfer channels of one and two nucleons. For the transfer reactions, the feeding of the final bound states was very selective. Narrow correlated structures were found in the transfer and especially in the elastic and inelastic channels. In this energy range, there appears to be a transition from surface transparency to interference phenomena. The optical model in its simplest form is unable to describe the elastic scattering at large angles. This has been interpreted as a consequence of the coupling between the elastic and inelastic channels which is particularly strong of these energies. 80 refs [fr
Study of the baryon-baryon interaction in nucleon-nucleon and pion-deuteron scattering
International Nuclear Information System (INIS)
Fuchs, M.
1993-01-01
After the definition of the Hamiltonian in general form by meson production and absorption the transition to operators pursued, which connect only spaces with definite meson numbers. In this approximation first the self-energy of a single baryon was calculated in its full energy and momentum dependence. Then the formal expressions for the T matrices of nucleon-nucleon and pion-deuteron scattering were derived. The essential components of these expressions are the baryon-baryon T matrix ant transition amplitudes from pion-deuteron channels to baryon-baryon states. The central chapter dealt with the calculation of the baryon-baryon interaction for the general form of the vertices, with the solution of the binding problem and the baryon-baryon T matrix. Finally followed the results on the nucleon-nucleon and pion-deuteron scattering. For this first the transition amplitudes from pion-deuteron states to intermediate baryon-baryon states and the Born graphs of the pion-deuteron scattering had to be calculated. After some remarks to the transition from partial-wave decomposed T matrices to scattering observables an extensive representation of the total, partial, and differential cross sections and a series of spin observables (analyzing powers and spin correlations) for the elastic proton-proton, neutron-proton, and pion-deuteron scattering as well for the fusion reaction pp→πd and the breakup reaction πd→pp follows. Thereby the energies reached from the nucleon-nucleon respectively pion-deuteron threshold up to 100 MeV above the delta resonance
International Nuclear Information System (INIS)
Steckmeyer, J.C.; Genouin-Duhamel, E.; Vient, E.; Colin, J.; Durand, D.; Auger, G.; Bacri, C.O.; Bellaize, N.; Borderie, B.; Bougault, R.; Bouriquet, B.; Brou, R.; Buchet, P.; Charvet, J.L.; Chbihi, A.; Cussol, D.; Dayras, R.; De Cesare, N.; Demeyer, A.; Dore, D.; Frankland, J.D.; Galichet, E.; Gerlic, E.; Guinet, D.; Hudan, S.; Lautesse, P.; Lavaud, F.; Laville, J.L.; Lecolley, J.F.; Leduc, C.; Legrain, R.; Le Neindre, N.; Lopez, O.; Louvel, M.; Maskay, A.M.; Nalpas, L.; Normand, J.; Parlog, M.; Pawlowski, P.; Plagnol, E.; Rivet, M.F.; Rosato, E.; Saint-Laurent, F.; Tabacaru, G.; Tamain, B.; Tassan-Got, L.; Tirel, O.; Turzo, K.; Vigilante, M.; Volant, C.; Wieleczko, J.P.
2001-01-01
The excitation energy and angular momentum transferred to quasiprojectiles have been measured in the 129 Xe+ nat Sn collisions at bombarding energies between 25 and 50 MeV/nucleon. The excitation energy of quasiprojectiles has been determined from the kinetic energy of all decay products (calorimetry). It increases with the violence of the collision, approaching 10 MeV/nucleon in the most dissipative ones. The angular momentum has been deduced from the kinetic energies and angular distributions of the emitted light charged particles (p, d, t, 3 He and α). The (apparent) spin value decreases with the violence of the collision. Larger spin values are observed at the lowest bombarding energy. Data are compared with the predictions of dynamical and statistical models. They reproduce the data in a quantitative way indicating that large spin values are transferred to quasiprojectiles during the interaction. The results show that the one-body dissipation formalism still applies at intermediate bombarding energies and low-energy dissipations. With the increase of the energy, the data seem to be better described when the two-body interaction is accounted for
Why do nucleons cling. [Meson theory
Energy Technology Data Exchange (ETDEWEB)
Kumar, N [Hindu Coll., Delhi (India)
1976-10-01
The nature of the forces which bind nucleons together within the nucleus of an atom have been discussed in detail. The characteristic properties of the nucleons, such as spin, interaction range etc. and the meson theory of nuclear forces are described. The present researches indicate that the force between two nucleons in a many-nucleon system is not very different from the force between two free nucleons. Researches related to the origin of nuclear forces based on the meson theory are now mainly concerned with the role played by the heavier mesons and the two pion exchanges in the middle region around 0.7 fm. (10/sup -13/ cm).
Measuring Intermolecular Binding Energies by Laser Spectroscopy.
Knochenmuss, Richard; Maity, Surajit; Féraud, Géraldine; Leutwyler, Samuel
2017-02-22
The ground-state dissociation energy, D0(S0), of isolated intermolecular complexes in the gas phase is a fundamental measure of the interaction strength between the molecules. We have developed a three-laser, triply resonant pump-dump-probe technique to measure dissociation energies of jet-cooled M•S complexes, where M is an aromatic chromophore and S is a closed-shell 'solvent' molecule. Stimulated emission pumping (SEP) via the S0→S1 electronic transition is used to precisely 'warm' the complex by populating high vibrational levels v" of the S0 state. If the deposited energy E(v") is less than D0(S0), the complex remains intact, and is then mass- and isomer-selectively detected by resonant two-photon ionization (R2PI) with a third (probe) laser. If the pumped level is above D0(S0), the hot complex dissociates and the probe signal disappears. Combining the fluorescence or SEP spectrum of the cold complex with the SEP breakoff of the hot complex brackets D0(S0). The UV chromophores 1-naphthol and carbazole were employed; these bind either dispersively via the aromatic rings, or form a hydrogen bond via the -OH or -NH group. Dissociation energies have been measured for dispersively bound complexes with noble gases (Ne, Kr, Ar, Xe), diatomics (N2, CO), alkanes (methane to n-butane), cycloalkanes (cyclopropane to cycloheptane), and unsaturated compounds (ethene, benzene). Hydrogen-bond dissociation energies have been measured for H2O, D2O, methanol, ethanol, ethers (oxirane, oxetane), NH3 and ND3.
International Nuclear Information System (INIS)
Xu Chang; Li Baoan; Chen Liewen
2010-01-01
Based on the Hugenholtz-Van Hove theorem, it is shown that both the symmetry energy E sym (ρ) and its density slope L(ρ) at normal density ρ 0 are completely determined by the nucleon global optical potentials. The latter can be extracted directly from nucleon-nucleus scatterings, (p,n) charge-exchange reactions, and single-particle energy levels of bound states. Averaging all phenomenological isovector nucleon potentials constrained by world data available in the literature since 1969, the best estimates of E sym (ρ 0 )=31.3 MeV and L(ρ 0 )=52.7 MeV are simultaneously obtained. Moreover, the corresponding neutron-proton effective mass splitting in neutron-rich matter of isospin asymmetry δ is estimated to be (m n * -m p * )/m=0.32δ.
Evaluation of the three-nucleon analyzing power puzzle
International Nuclear Information System (INIS)
Tornow, W.; Witala, H.
1998-01-01
The current status of the three-nucleon analyzing power puzzle is reviewed. Applying tight constraints on the allowed deviations between calculated predictions and accepted values for relevant nucleon-nucleon observables reveals that energy independent correction factors applied to the 3 P j nucleon-nucleon interactions can not solve the puzzle. Furthermore, using the same constraints, charge-independence breaking in the 3 P j nucleon-nucleon interactions can be ruled out as a possible tool to improve the agreement between three-nucleon calculations and data. The study of the energy dependence of the three-nucleon analyzing power puzzle gives clear evidence that the 3 P j nucleon-nucleon interaction obtained from phase-shift analyses and used in potential models are correct above about 25 MeV, i.e., the 3 P j nucleon-nucleon interactions have to be modified only at lower energies in order to solve the three-nucleon analyzing power puzzle, unless new three-nucleon forces can be found that account for the three-nucleon analyzing power puzzle without destroying the beautiful agreement between rigorous three-nucleon calculations and a large body of accurate three-nucleon data. (orig.)
Evaluation of the three-nucleon analyzing power puzzle
Energy Technology Data Exchange (ETDEWEB)
Tornow, W. [Duke Univ., Durham, NC (United States). Dept. of Physics]|[Triangle Univ. Nuclear Lab., Durham, NC (United States); Witala, H. [Uniwersytet Jagiellonski, Cracow (Poland). Inst. Fizyki
1998-07-20
The current status of the three-nucleon analyzing power puzzle is reviewed. Applying tight constraints on the allowed deviations between calculated predictions and accepted values for relevant nucleon-nucleon observables reveals that energy independent correction factors applied to the {sup 3}P{sub j} nucleon-nucleon interactions can not solve the puzzle. Furthermore, using the same constraints, charge-independence breaking in the {sup 3}P{sub j} nucleon-nucleon interactions can be ruled out as a possible tool to improve the agreement between three-nucleon calculations and data. The study of the energy dependence of the three-nucleon analyzing power puzzle gives clear evidence that the {sup 3}P{sub j} nucleon-nucleon interaction obtained from phase-shift analyses and used in potential models are correct above about 25 MeV, i.e., the {sup 3}P{sub j} nucleon-nucleon interactions have to be modified only at lower energies in order to solve the three-nucleon analyzing power puzzle, unless new three-nucleon forces can be found that account for the three-nucleon analyzing power puzzle without destroying the beautiful agreement between rigorous three-nucleon calculations and a large body of accurate three-nucleon data. (orig.) 18 refs.
Fitting theories of nuclear binding energies
International Nuclear Information System (INIS)
Bertsch, G.F.; Sabbey, B.; Uusnaekki, M.
2005-01-01
In developing theories of nuclear binding energy such as density-functional theory, the effort required to make a fit can be daunting because of the large number of parameters that may be in the theory and the large number of nuclei in the mass table. For theories based on the Skyrme interaction, the effort can be reduced considerably by using the singular value decomposition to reduce the size of the parameter space. We find that the sensitive parameters define a space of dimension four or so, and within this space a linear refit is adequate for a number of Skyrme parameters sets from the literature. We find no marked differences in the quality of the fit among the SLy4, the BSk4, and SkP parameter sets. The root-mean-square residual error in even-even nuclei is about 1.5 MeV, half the value of the liquid drop model. We also discuss an alternative norm for evaluating mass fits, the Chebyshev norm. It focuses attention on the cases with the largest discrepancies between theory and experiment. We show how it works with the liquid drop model and make some applications to models based on Skyrme energy functionals. The Chebyshev norm seems to be more sensitive to new experimental data than the root-mean-square norm. The method also has the advantage that candidate improvements to the theories can be assessed with computations on smaller sets of nuclei
International Nuclear Information System (INIS)
Miller, G.A.
1984-01-01
In the Cloudy Bag Model hadrons are treated as quarks confined in an M.I.T. bag that is surrounded by a cloud of pions. Computations of the charge and magnetism distributions of nucleons and baryons, pion-nucleon scattering, and the strong and electromagnetic decays of mesons are discussed. Agreement with experimental results is excellent if the nucleon bag radius is in the range between 0.8 and 1.1 fm. Underlying qualitative reasons which cause the pionic corrections to be of the obtained sizes are analyzed. If bags are of such reasonably large sizes, nucleon bags in nuclei will often come into contact. As a result one needs to consider whether explicit quark degrees of freedom are relevant for Nuclear Physics. To study such possibilities a model which treats a nucleus as a collection of baryons, pions and six-quark bags is discussed. In particular, the short distance part of a nucleon-nucleon wave function is treated as six quarks confined in a bag. This approach is used to study the proton-proton weak interaction, the asymptotic D to S state ratio of the deuteron, the pp → dπ reaction, the charge density of /sup 3/He, magnetic moments of /sup 3/He and /sup 3/H and, the /sup 3/He-/sup 3/H binding energy difference. It is found that quark effects are very relevant for understanding nuclear properties
Binding-energy distribution and dephasing of localized biexcitons
DEFF Research Database (Denmark)
Langbein, Wolfgang Werner; Hvam, Jørn Märcher; Umlauff, M.
1997-01-01
We report on the binding energy and dephasing of localized biexciton states in narrow ZnSe multiple quantum wells. The measured binding-energy distribution of the localized biexcitons shows a width of 2.2 meV centered at 8.5 meV, and is fairly independent of the exciton localization energy. In fo...
Toyokawa, Masakazu; Yahiro, Masanobu; Matsumoto, Takuma; Kohno, Michio
2018-02-01
An important current subject is to clarify the properties of chiral three-nucleon forces (3NFs) not only in nuclear matter but also in scattering between finite-size nuclei. Particularly for elastic scattering, this study has just started and the properties are not understood for a wide range of incident energies (E_in). We investigate basic properties of chiral 3NFs in nuclear matter with positive energies by using the Brueckner-Hartree-Fock method with chiral two-nucleon forces at N3LO and 3NFs at NNLO, and analyze the effects of chiral 3NFs on 4He elastic scattering from targets ^{208}Pb, ^{58}Ni, and ^{40}Ca over a wide range of 30 ≲ E_in/A_P ≲ 200 MeV by using the g-matrix folding model, where A_P is the mass number of the projectile. In symmetric nuclear matter with positive energies, chiral 3NFs make the single-particle potential less attractive and more absorptive. The effects mainly come from the Fujita-Miyazawa 2π-exchange 3NF and become slightly larger as E_in increases. These effects persist in the optical potentials of 4He scattering. As for the differential cross sections of 4He scattering, chiral-3NF effects are large for E_in/A_P ≳ 60 MeV and improve the agreement of the theoretical results with the measured ones. Particularly for E_in/A_P ≳ 100 MeV, the folding model reproduces measured differential cross sections pretty well. Cutoff (Λ) dependence is investigated for both nuclear matter and 4He scattering by considering two cases of Λ=450 and 550 MeV. The uncertainty coming from the dependence is smaller than chiral-3NF effects even at E_in/A_P=175 MeV.
International Nuclear Information System (INIS)
Fassnacht, P.
1984-01-01
We have studied pion production in nucleus-nucleus collisions at foward angles for about twenty projectile target combinations. The incident energies were below or around 300 MeV/nucleon which is the threshold of the elementary reaction NN → NNπ. The study of the inclusive spectra shows some new ideas: shell effects in pion production, collective resonances excitations. These spectra have been analyzed following different models: hard-scattering models which describe the interaction on the basis of the elementary reaction NN → NNπ, statistical model and the pionic cloud model which is a coherent description of the interaction. In the study of the exclusive reactions, we established some empiric rules concerning the cross-section variations. These exclusive spectra were then analyzed in the framework of two-models: the semi-phenomenological model and the pionic fusion [fr
Conformational Transitions and Convergence of Absolute Binding Free Energy Calculations
Lapelosa, Mauro; Gallicchio, Emilio; Levy, Ronald M.
2011-01-01
The Binding Energy Distribution Analysis Method (BEDAM) is employed to compute the standard binding free energies of a series of ligands to a FK506 binding protein (FKBP12) with implicit solvation. Binding free energy estimates are in reasonably good agreement with experimental affinities. The conformations of the complexes identified by the simulations are in good agreement with crystallographic data, which was not used to restrain ligand orientations. The BEDAM method is based on λ -hopping Hamiltonian parallel Replica Exchange (HREM) molecular dynamics conformational sampling, the OPLS-AA/AGBNP2 effective potential, and multi-state free energy estimators (MBAR). Achieving converged and accurate results depends on all of these elements of the calculation. Convergence of the binding free energy is tied to the level of convergence of binding energy distributions at critical intermediate states where bound and unbound states are at equilibrium, and where the rate of binding/unbinding conformational transitions is maximal. This finding mirrors similar observations in the context of order/disorder transitions as for example in protein folding. Insights concerning the physical mechanism of ligand binding and unbinding are obtained. Convergence for the largest FK506 ligand is achieved only after imposing strict conformational restraints, which however require accurate prior structural knowledge of the structure of the complex. The analytical AGBNP2 model is found to underestimate the magnitude of the hydrophobic driving force towards binding in these systems characterized by loosely packed protein-ligand binding interfaces. Rescoring of the binding energies using a numerical surface area model corrects this deficiency. This study illustrates the complex interplay between energy models, exploration of conformational space, and free energy estimators needed to obtain robust estimates from binding free energy calculations. PMID:22368530
International Nuclear Information System (INIS)
Toke, J.; Planeta, R.; Schroeder, W.U.; Huizenga, J.R.
1991-01-01
Data from a kinematical coincidence experiment on the damped reaction 165 Ho+ 74 Ge at 8.5 MeV/nucleon have been reanalyzed. Although the new analysis confirms the presence of some correlations between the excitation-energy division and the mass asymmetry, the magnitude of these correlations is found to be significantly smaller than that previously reported. Proton-neutron symmetry of the mechanism of heat generation through nucleon exchange is revealed and a possible acceptor-donor asymmetry of this mechanism is discussed
Vonta, N.; Souliotis, G. A.; Loveland, W. D.; Kwon, Y. K.; Tshoo, K.; Jeong, S. C.; Veselsky, M.; Bonasera, A.; Botvina, A.
2016-01-01
We investigate the possibilities of producing neutron-rich nuclides in projectile fission of heavy beams in the energy range of 20 MeV/nucleon expected from low-energy facilities. We report our efforts to theoretically describe the reaction mechanism of projectile fission following a multinucleon transfer collision at this energy range. Our calculations are mainly based on a two-step approach: the dynamical stage of the collision is described with either the phenomenological Deep-Inelastic Tr...
Abreu, M C; Alexa, C; Arnaldi, R; Ataian, M R; Baglin, C; Baldit, A; Bedjidian, Marc; Beolè, S; Boldea, V; Bordalo, P; Borges, G; Bussière, A; Capelli, L; Castanier, C; Castor, J I; Chaurand, B; Chevrot, I; Cheynis, B; Chiavassa, E; Cicalò, C; Claudino, T; Comets, M P; Constans, N; Constantinescu, S; Cortese, P; De Falco, A; De Marco, N; Dellacasa, G; Devaux, A; Dita, S; Drapier, O; Ducroux, L; Espagnon, B; Fargeix, J; Force, P; Gallio, M; Gavrilov, Yu K; Gerschel, C; Giubellino, P; Golubeva, M B; Gonin, M; Grigorian, A A; Grigorian, S; Grossiord, J Y; Guber, F F; Guichard, A; Gulkanian, H R; Hakobyan, R S; Haroutunian, R; Idzik, M; Jouan, D; Karavitcheva, T L; Kluberg, L; Kurepin, A B; Le Bornec, Y; Lourenço, C; Macciotta, P; MacCormick, M; Marzari-Chiesa, A; Masera, M; Masoni, A; Monteno, M; Musso, A; Petiau, P; Piccotti, A; Pizzi, J R; Prado da Silva, W L; Prino, F; Puddu, G; Quintans, C; Ramello, L; Ramos, S; Rato-Mendes, P; Riccati, L; Romana, A; Santos, H; Saturnini, P; Scalas, E; Scomparin, E; Serci, S; Shahoyan, R; Sigaudo, F; Silva, S; Sitta, M; Sonderegger, P; Tarrago, X; Topilskaya, N S; Usai, G L; Vercellin, Ermanno; Villatte, L; Willis, N
2002-01-01
The charged particle distributions $dN_{ch}/d\\eta$ have been measured by the NA50 experiment in Pb--Pb collisions at the CERN SPS. Measurements have been done at incident energies of 158 and 40 GeV per nucleon over a broad impact parameter range. Results obtained with two independent centrality estimators, namely the neutral transverse energy $E_T$ and the forward energy $E_{ZDC}$, are reported.}
Pion distribution in the nucleon
International Nuclear Information System (INIS)
Lee, T.-S.H.
1989-01-01
A model is presented for calculating the pion wave function inside the nucleon. By assuming that all pions around a core of the nucleon are in the lowest eigenstate of the system, it is shown that both the bound state and πN scattering amplitude can be consistently described by an exactly soluble model defined in the subspace spanned by the core state and the physical πN state. The parameters of the model are determined by fitting the data of the nucleon mass, πNN coupling constant and low energy πN scattering phase shifts. The model predicts that the probability of finding the pion component inside the nucleon is about 20%. The calculated πNN form factor differs significantly from the conventional monopole form. The dynamical consequences of the differences are demonstrated in a calculation of electromagnetic production of pions from the nucleon and the deuteron. 7 refs., 4 figs., 1 tab
Implicit ligand theory for relative binding free energies
Nguyen, Trung Hai; Minh, David D. L.
2018-03-01
Implicit ligand theory enables noncovalent binding free energies to be calculated based on an exponential average of the binding potential of mean force (BPMF)—the binding free energy between a flexible ligand and rigid receptor—over a precomputed ensemble of receptor configurations. In the original formalism, receptor configurations were drawn from or reweighted to the apo ensemble. Here we show that BPMFs averaged over a holo ensemble yield binding free energies relative to the reference ligand that specifies the ensemble. When using receptor snapshots from an alchemical simulation with a single ligand, the new statistical estimator outperforms the original.
Perturbation method for calculating impurity binding energy in an ...
Indian Academy of Sciences (India)
Nilanjan Sil
2017-12-18
Dec 18, 2017 ... Abstract. In the present paper, we have studied the binding energy of the shallow donor hydrogenic impurity, which is confined in an inhomogeneous cylindrical quantum dot (CQD) of GaAs-AlxGa1−xAs. Perturbation method is used to calculate the binding energy within the framework of effective mass ...
Recent results in the development of a global medium-energy nucleon-nucleus optical-model potential
International Nuclear Information System (INIS)
Madland, D.G.
1988-02-01
Initial results are presented for the determination of a global medium-energy nucleon-nucleus phenomenological optical-model potential using a relativistic Schroedinger representation. The starting point for this work is the global phenomenological optical-model potential of Schwandt /ital et al./, which is based on measured elastic scattering cross sections and analyzing power for polarized protons ranging from 80 to 180 MeV. This potential is optimally modified to reproduce experimental proton reaction cross sections as a function of energy, while allowing only minimal deterioration in the fits to the elastic cross sections and analyzing powers. Further modifications in the absorptive potential were found necessary to extrapolate the modified potential to higher energies. The final potential is converted to a neutron-nucleus potential by use of standard Lane model assumptions and by accounting approximately for the Coulomb correction. Comparisons of measured and calculated proton reaction and neutron total cross sections are presented for 27 Al, 56 Fe, and 208 Pb. Medium-energy optical-model potentials for complex projectiles are briefly discussed in an appendix. 7 refs., 20 figs
Radial excitations in nucleon-nucleon scattering
International Nuclear Information System (INIS)
Silvestre-Brac, B.; Carbonell, J.; Gignoux, C.
1986-01-01
In the non-relativistic constituent quark model, the role of the radial excitations of the nucleon is studied within a resonating group approach of the nucleon-nucleon scattering. It is shown that, rather than the inclusion of new channels, it is important to include mixed-symmetry spin-isospin components in the nucleon wave function. It is also found that during the collision there is no significant deformation of the nucleon. (orig.)
Medium corrections to nucleon-nucleon interactions
International Nuclear Information System (INIS)
Dortmans, P.J.; Amos, K.
1990-01-01
The Bethe-Goldstone equations have been solved for both negative and positive energies to specify two nucleon G-matrices fully off of the energy shell. Medium correction effects of Pauli blocking and of the auxiliary potential are included in infinite matter systems characterized by fermi momenta in the range 0.5 fm -1 to 1.8 fm -1 . The Paris interaction is used as the starting potential in most calculations. Medium corrections are shown to be very significant over a large range of energies and densities. On the energy shell values of G-matrices vary markedly from those of free two nucleon (NN) t-matrices which have been solved by way of the Lippmann-Schwinger equation. Off of the energy shell, however, the free and medium corrected Kowalski-Noyes f-ratios rate are quite similar suggesting that a useful model of medium corrected G-matrices are appropriately scaled free NN t-matrices. The choice of auxiliary potential form is also shown to play a decisive role in the negative energy regime, especially when the saturation of nuclear matter is considered. 30 refs., 7 tabs., 7 figs
On binding energy of trions in bulk materials
Filikhin, Igor; Kezerashvili, Roman Ya.; Vlahovic, Branislav
2018-03-01
We study the negatively T- and positively T+ charged trions in bulk materials in the effective mass approximation within the framework of a potential model. The binding energies of trions in various semiconductors are calculated by employing Faddeev equation in configuration space. Results of calculations of the binding energies for T- are consistent with previous computational studies and are in reasonable agreement with experimental measurements, while the T+ is unbound for all considered cases. The mechanism of formation of the binding energy of trions is analyzed by comparing contributions of a mass-polarization term related to kinetic energy operators and a term related to the Coulomb repulsion of identical particles.
Evoli, Stefania
2016-11-10
Human serum albumin possesses multiple binding sites and transports a wide range of ligands that include the anti-inflammatory drug ibuprofen. A complete map of the binding sites of ibuprofen in albumin is difficult to obtain in traditional experiments, because of the structural adaptability of this protein in accommodating small ligands. In this work, we provide a set of predictions covering the geometry, affinity of binding and protonation state for the pharmaceutically most active form (S-isomer) of ibuprofen to albumin, by using absolute binding free energy calculations in combination with classical molecular dynamics (MD) simulations and molecular docking. The most favorable binding modes correctly reproduce several experimentally identified binding locations, which include the two Sudlow\\'s drug sites (DS2 and DS1) and the fatty acid binding sites 6 and 2 (FA6 and FA2). Previously unknown details of the binding conformations were revealed for some of them, and formerly undetected binding modes were found in other protein sites. The calculated binding affinities exhibit trends which seem to agree with the available experimental data, and drastically degrade when the ligand is modeled in a protonated (neutral) state, indicating that ibuprofen associates with albumin preferentially in its charged form. These findings provide a detailed description of the binding of ibuprofen, help to explain a wide range of results reported in the literature in the last decades, and demonstrate the possibility of using simulation methods to predict ligand binding to albumin.
International Nuclear Information System (INIS)
Keszenman, D.J.; Sutherland, B.M.
2010-01-01
To determine the linear energy transfer (LET) dependence of the biological effects of densely ionizing radiation in relation to changes in the ionization density along the track, we measured the yields and spectrum of clustered DNA damages induced by charged particles of different atomic number but similar kinetic energy per nucleon in different DNA microenvironments. Yeast DNA embedded in agarose in solutions of different free radical scavenging capacity was irradiated with 1 GeV protons, 1 GeV/nucleon oxygen ions, 980 MeV/nucleon titanium ions or 968 MeV/nucleon iron ions. The frequencies of double-strand breaks (DSBs), abasic sites and oxypurine clusters were quantified. The total DNA damage yields per absorbed dose induced in non-radioquenching solution decreased with LET, with minor variations in radioquenching conditions being detected. However, the total damage yields per particle fluence increased with LET in both conditions, indicating a higher efficiency per particle to induce clustered DNA damages. The yields of DSBs and non-DSB clusters as well as the damage spectra varied with LET and DNA milieu, suggesting the involvement of more than one mechanism in the formation of the different types of clustered damages.
DEFF Research Database (Denmark)
Jorgensen, Peter L.; Pedersen, Per Amstrup
2000-01-01
Na,K-ATPase; Mutagenesis; Na+ binding; K+ binding; Tl+ binding; Mg2+ binding; ATP binding; Cation binding site; Energy transduction......Na,K-ATPase; Mutagenesis; Na+ binding; K+ binding; Tl+ binding; Mg2+ binding; ATP binding; Cation binding site; Energy transduction...
International Nuclear Information System (INIS)
Kuprikov, V. I.; Pilipenko, V. V.; Soznik, A. P.; Tarasov, V. N.; Shlyakhov, N. A.
2009-01-01
The possibility of constructing such new versions of effective nucleon-nucleon forces that would make it possible to describe simultaneously the cross sections for nucleon-nucleus scattering and quantities characterizing nuclear matter and the structure of finite even-even nuclei is investigated on the basis of a microscopic nucleon-nucleus optical potential that is calculated by using effective Skyrme interaction. A procedure for optimizing the parameters of Skyrme forces by employing fits to specific angular distributions for neutron-nucleus scattering and by simultaneously testing the features of nuclear matter, the binding energy of the target nucleus, and its proton root-mean-square radius is proposed. A number of versions of modified Skyrme forces that ensure a reasonable description of both nucleon-nucleus scattering and the properties of nuclear structure are found on the basis of this procedure.
Using the fast fourier transform in binding free energy calculations.
Nguyen, Trung Hai; Zhou, Huan-Xiang; Minh, David D L
2018-04-30
According to implicit ligand theory, the standard binding free energy is an exponential average of the binding potential of mean force (BPMF), an exponential average of the interaction energy between the unbound ligand ensemble and a rigid receptor. Here, we use the fast Fourier transform (FFT) to efficiently evaluate BPMFs by calculating interaction energies when rigid ligand configurations from the unbound ensemble are discretely translated across rigid receptor conformations. Results for standard binding free energies between T4 lysozyme and 141 small organic molecules are in good agreement with previous alchemical calculations based on (1) a flexible complex ( R≈0.9 for 24 systems) and (2) flexible ligand with multiple rigid receptor configurations ( R≈0.8 for 141 systems). While the FFT is routinely used for molecular docking, to our knowledge this is the first time that the algorithm has been used for rigorous binding free energy calculations. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.
International Nuclear Information System (INIS)
Margetis, S.
1991-02-01
The interactions of heavy nuclei at ultra relativistic energies is a recently opened field of accelerator physics, not being any longer a rare privilege of cosmic ray experiments. After the first 16 O ions were accelerated at the BNL-AGS (14.5 GeV/nucleon) and the CERN-SPS (200 GeV/nucleon) in 1986 (Sto85), heavier projectiles like 28 Si (BNL) and 32 S (CERN) have been used later on. A large amount of information has been collected with almost every possible detector technique, each of them designed for different physics observables. Some of the experiments were designed to study several different signals from the same event whereas others were dedicated to a specific signal. The experiment NA 35 is an example of a large acceptance, 'multi-particle' experiment. Its aim is a survey study of the reaction mechanisms involved in collisions between heavy nuclei and a search for new phenomena. The calorimetric part of NA 35 is the subject of this study. (orig.) [de
CMB bounds on dark matter annihilation: Nucleon energy losses after recombination
Weniger, C.; Serpico, P.D.; Iocco, F.; Bertone, G.
2013-01-01
We consider the propagation and energy losses of protons and antiprotons produced by dark matter annihilation at redshifts 100
International Nuclear Information System (INIS)
Desplanques, B.
1989-12-01
The concept of nucleon in nuclei has often been referred to in recent literature. What it is used for is rarely precised however. In this paper, it is shown (or reminded) that the nucleon in nuclei is a model dependent object. As an illustration, it is shown that nuclear matter in its ground state may be described to a good approximation, if not exactly, by an independent particle state and that the on-shell G-matrix used in calculating its binding energy gets its effective character from that of those particles. The expression of these particles in terms of free nucleon operators is given
Predicting accurate absolute binding energies in aqueous solution
DEFF Research Database (Denmark)
Jensen, Jan Halborg
2015-01-01
Recent predictions of absolute binding free energies of host-guest complexes in aqueous solution using electronic structure theory have been encouraging for some systems, while other systems remain problematic. In this paper I summarize some of the many factors that could easily contribute 1-3 kcal......-represented by continuum models. While I focus on binding free energies in aqueous solution the approach also applies (with minor adjustments) to any free energy difference such as conformational or reaction free energy differences or activation free energies in any solvent....
3D parton imaging of the nucleon in high-energy p p and p A collisions
Frankfurt, L; Weiss, C
2004-01-01
We discuss several examples of how the transverse spatial distribution of partons in the nucleon, as well as multiparton correlations, can be probed by observing hard processes (dijets) in high-energy pp(pp) and pA(dA) collisions. Such studies can complement the information gained from measurements of hard exclusive processes in ep scattering. The transverse spatial distribution of partons determines the distribution over pp impact parameters of events with hard dijet production. Correlations in the transverse positions of partons can be studied in multiple dijet production. We find that the correlation cross section measured by the CDF Collaboration, sigma//e //f//f = 14.5 plus or minus 1.7//-//2//.//3**+**1**.**7 mb, can be explained by "constituent quark" type quark-gluon correlations with r //q approximately equals r//N/3, as suggested by the instanton liquid model of the QCD vacuum. Longitudinal and transverse multiparton correlations can be separated in a model-independent way by comparing multiple dije...
International Nuclear Information System (INIS)
1993-01-01
This report summarizes the work on experimental research in intermediate energy nuclear physics carried out at New Mexico State University in 1991-94 under a grant from the U.S. Department of Energy. Most of these studies involved investigations of various pion-nucleus interactions and nucleon-nucleus charge-exchange reactions. The work was carried out with the LAMPF accelerator at the Los Alamos National Laboratory and the cyclotrons at the Paul Scherrer Institute (PSI) near Zurich, Switzerland, at Indiana University (IUCF), and at TRIUMF in Vancouver, Canada, as collaborative efforts among several laboratories and universities. We have also worked on plans and preparations for new experiments involving studies of the quark structure of nucleons and nuclei, which would be carried out at Fermilab (FNAL), near Chicago, and at the HERA facility at the DESY laboratory in Hamburg, Germany. The NMSU personnel included two faculty members, five postdoctoral research associates, nine graduate students, and one undergraduate student
International Nuclear Information System (INIS)
Plasil, F.; Albrecht, R.; Awes, T.C.
1989-01-01
The main goal of the CERN heavy-ion experiments is the search for an indication that the predicted state of deconfined quarks and gluons, the quark-gluon plasma (QGP), has been produced. The quantity most crucial to the probability of QGP formation is the thermalized energy density attained during the heavy-ion reaction. The amount of energy radiated transverse to the beam direction is the experimental quantity which is believed to be a measure of the amount of energy deposition in the reaction, and hence to reflect the energy density attained. In this presentation we consider the systematics of transverse energy production at CERN SPS energies, and we use the results to make estimates, under various assumptions, of attained energy densities. Measurements of direct photons and lepton pairs are considered to be among the most promising methods for studies of the QGP. In contrast to hadrons, direct photons are not expected to undergo any interactions after their creation. The WA80 collaboration has undertaken the measurement of direct photons, which is a difficult task due to the presence of a high background of photons from the decay of neutral pions. The π 0 spectra themselves, however, provide us with the opportunity to study the excited reaction zone during the hadronization phase. We present here measurements of neutral pions produced in 16 O + Au collisions at 200 GeV/nucleon. 22 refs., 11 figs
High-energy electroweak neutrino-nucleon deeply virtual Compton scattering
International Nuclear Information System (INIS)
Machado, Magno V. T.
2007-01-01
In this work we estimate the differential and total cross sections for the high-energy deeply virtual Compton scattering in the weak sector. In the weak neutral sector one considers neutrino scattering off an unpolarized proton target through the exchange of Z 0 . We numerically compute the process Z*p→γp within the QCD color dipole formalism, which successfully describes the current high-energy electromagnetic DVCS experimental data. We also discuss possible applications for the weak charged sector and perform predictions for scattering on nuclear targets
Su, Jun; Zhu, Long; Guo, Chenchen
2018-05-01
Background: Special attention has been paid to study the shell effect and odd-even staggering (OES) in the nuclear spallation. Purpose: In this paper, we investigate the influence of the nuclear level density on the OES in the 56Fe+p spallations at energies from 300 to 1500 MeV/nucleon. Method: The isospin-dependent quantum molecular dynamics (IQMD) model is applied to produce the highly excited and equilibrium remnants, which is then de-excited using the statistical model gemini. The excitation energy of the heaviest hot fragments is applied to match the IQMD model with the gemini model. In the gemini model, the statistical description of the evaporation are based on the Hauser-Feshbach formalism, in which level density prescriptions are applied. Results: By investigating the OES of the excited pre-fragments, it is found that the OES originates at the end of the decay process when the excitation energy is close to the nucleon-emission threshold energy, i.e., the smaller value of the neutron separation energy and proton separation energy. The strong influence of level density on the OES is noticed. Two types of the nuclear level densities, the discrepancy of which is only about 7% near the nucleon emission threshold energy, are used in the model. However, the calculated values of the OES differ by the factor of 3 for the relevant nuclei. Conclusions: It is suggested that, although the particle-separation energies play a key role in determining the OES, the level density at excitation energy lower than the particle-separation energies should be taken into consideration
Astrophysical searches for exotic phenomena in ultrahigh energy neutrino-nucleon scattering
International Nuclear Information System (INIS)
Morris, D.A.; Ringwald, A.
1994-03-01
We investigate the potential of near-future neutrino telescopes like NESTOR for searches for exotic processes in ultrahigh energy neutrino-quark scattering. We consider signatures such as muon bundles and/or contained cascades from the nonperturbative production of multiple weak gauge bosons in the Standard Model, compositeness and leptoquark production. (orig.)
Nucleon charge exchange reaction and antiproton elastic scattering at intermediate energies
International Nuclear Information System (INIS)
Kronenfeld, J.
1985-02-01
This work treats the medium energy nuclear (p,n) charge exchange reaction to analog states and the low energy elastic scattering of antiprotons and investigates the central aspects of a microscopic theory based on multiple-scattering series which are pertinent to these reactions. A two-step term of the Distorted Wave Impulse Approximation (DWIA) in treating the (p,n) reaction, was included. For the very absorptive p-bar interaction with nuclei we conjecture that a partial infinite summation, constituing a renormalization of the single scattering term of the optical potential series provides the dominant feature of this interaction. In this work the excitation of analog states is calculated and it was found that the (p,n) reaction is described fairly well by the DWIA. In the first part of the work the (p,n) reaction in the energy range 100-200 MeV was treated. The DWIA calculations were based on eikonalization. In the second part of the work the p-barA interaction with the selfconsistent scheme mentioned above, for scattering energies 30-120 MeV, was examined. (author)
Effects of pairing correlation on nuclear level density parameter and nucleon separation energy
International Nuclear Information System (INIS)
Rajesekaran, T.R.; Selvaraj, S.
2002-01-01
A systematic study of effects of pairing correlations on nuclear level density parameter 'a' and neutron separation energy S N is presented for 152 Gd using statistical theory of nuclei with deformation, collective and noncollective rotational degrees of freedom, shell effects, and pairing correlations
Binding energy and single-particle energies in the 16O Region
International Nuclear Information System (INIS)
Fiase, J.O.; Sharma, L.K.
2004-01-01
In this paper we present the binding energy of 16 O together with single-particle energies in the oxygen region by folding together a Hamiltonian in the rest-frame of the nucleus with two-body correlation functions based on the Nijmegen potential. We have found that the binding energies are very sensitive to the core radius rc and that the effects of tensor correlations are non-negligible.Our calculated binding energy, E B = - 127.8 MeV with r c = 0.241 fm compares well with the experimental binding energy, E B = - 127.6 MeV
Overview of polarization in intermediate energy nucleon-nucleus inelastic scattering
International Nuclear Information System (INIS)
Carey, T.
1985-01-01
The general role that polarization transfer (PT) can play in the ''dissection'' of medium-energy N-nucleus inelastic reactions is reviewed, specifically concentrating on the importance of complete sets of PT observables for the study of nuclear structure. The discussion is largely in the context of plane-wave impulse approximations, with the effects of distortions considered through comparisons between simple plane-wave predictions and DWIA computations. 31 refs., 11 figs
On single nucleon wave functions in nuclei
International Nuclear Information System (INIS)
Talmi, Igal
2011-01-01
The strong and singular interaction between nucleons, makes the nuclear many body theory very complicated. Still, nuclei exhibit simple and regular features which are simply described by the shell model. Wave functions of individual nucleons may be considered just as model wave functions which bear little resemblance to the real ones. There is, however, experimental evidence for the reality of single nucleon wave functions. There is a simple method of constructing such wave functions for valence nucleons. It is shown that this method can be improved by considering the polarization of the core by the valence nucleon. This gives rise to some rearrangement energy which affects the single valence nucleon energy within the nucleus.
Haldar, T K; Bhattacharya, D P; 10.1023/A:1024822518795
2003-01-01
Vertical muon energy spectra at sea level have been estimated from a directly measured primary cosmic-ray nucleon spectrum. The hadronic energy moments have been calculated from the CERN LEBC EHS data on the Lorentz invariant cross-section results on pp to pi /sup +or-/X and pp to K/sup +or-/X inclusive reactions and are duly corrected for A-A collisions. Finally, the sea level muon energy spectra have been calculated from the decay of conventional mesons, using standard formulation. The estimated muon spectra are found to be in good agreement with the directly measured muon spectra obtained from different experiments. (32 refs).
Energy Technology Data Exchange (ETDEWEB)
Chatrchyan, Serguei [Yerevan Physics Inst. (Armenia); et al.
2011-08-01
A measurement is presented of the charged hadron multiplicity in hadronic PbPb collisions, as a function of pseudorapidity and centrality, at a collision energy of 2.76 TeV per nucleon pair. The data sample is collected using the CMS detector and a minimum-bias trigger, with the CMS solenoid off. The number of charged hadrons is measured both by counting the number of reconstructed particle hits and by forming hit doublets of pairs of layers in the pixel detector. The two methods give consistent results. The charged hadron multiplicity density dN(ch)/d eta, evaluated at eta=0 for head-on collisions, is found to be 1612 +/- 55, where the uncertainty is dominated by systematic effects. Comparisons of these results to previous measurements and to various models are also presented.
International Nuclear Information System (INIS)
Liu Jianye; Xing Yongzhong; Guo Wenjun
2003-01-01
We study the isospin effects of the mean field and two-body collision on the nucleon emissions at the intermediate energy heavy-ion collisions by using an isospin-dependent transport theory. The calculated results show that the nucleon emission number N n depends sensitively on the isospin effect of nucleon-nucleon cross section and weakly on the isospin-dependent mean field for neutron-poor system in higher beam energy region. In particular, the correlation between the medium correction of two-body collision and the momentum-dependent interaction enhances the dependence of nucleon emission number N n on the isospin effect of nucleon-nucleon cross section. On the contrary, the ratio of the neutron-proton ratio of the gas phase to the neutron-proton ratio of the liquid phase, i.e., the degree of isospin fractionation [(N/Z) gas ] b /[(N/Z) liq ] b depends sensitively on the isospin-dependent mean field and weakly on the isospin effect of two-body collision for neutron-rich system in the lower beam energy region. In this case, N n and [(N/Z) gas ] b /[(N/Z) liq ] b are the probes for extracting the information about the isospin-dependent nucleon-nucleon cross section in the medium and the isospin-dependent mean field, respectively
Binding energy effects in cascade evolution and sputtering
International Nuclear Information System (INIS)
Robinson, M.T.
1995-06-01
The MARLOWE model was extended to include a binding energy dependent on the local crystalline order, so that atoms are bound less strongly to their lattice sites near surfaces or associated damage. Sputtering and cascade evolution were studied on the examples of self-ion irradiations of Cu and Au monocrystals. In cascades, the mean binding energy is reduced ∼8% in Cu with little dependence on the initial recoil energy; in Au, it is reduced ∼9% at 1 keV and ∼15% at 100 keV. In sputtering, the mean binding energy is reduced ∼8% in Cu and ∼15% in Au with little energy dependence; the yields are increased about half as much. Most sites from which sputtered atoms originate are isolated in both metals. Small clusters of such sites occur in Cu, but there are some large clusters in Au, especially in [111] targets. There are always more large clusters with damage-dependent binding than with a constant binding energy, but only a few clusters are compact enough to be regarded as pits
The nucleon- nucleon interaction and symmetries
International Nuclear Information System (INIS)
Van Oers, W.T.H.
1992-11-01
With the advent of the possibility to study nucleon-nucleon scattering at medium energies, its extension to investigate fundamental symmetries was recognized early on. It was precisely the introduction of rotational invariance, parity conservation, time reversal invariance, and isotopic spin conversation that led to the description of the N - N scattering matrix in terms of five complex amplitudes: one set of five for proton-proton scattering and one set of five for neutron-proton scattering, or alternatively, one set for the isotopic spin state ι=ο and the other for the isotopic spin state ι=1. Clearly, if one or more of the above constraints are removed, there are additional amplitudes that need to be considered. To be meaningful, experiment requires observables that are particularly sensitive to the violation of a conservation law or symmetry principle. During the last decade a series of precision experiments has been performed to measure charge- symmetry breaking in n - p elastic scattering (corresponding to isotopic spin non-conservation), and to measure parity violation in p-p scattering. For a particle-anti-particle system,like the pp or λλ system one can raise the question of CP violation in a system other than the neutral kaon system may become possible in the near future through pp →λλ and pp→ ≡ ≡. A description is given of the ongoing efforts to measure charge symmetry breaking, parity violation and CP violation.(author). 42 refs., 6 figs
Funnel metadynamics as accurate binding free-energy method
Limongelli, Vittorio; Bonomi, Massimiliano; Parrinello, Michele
2013-01-01
A detailed description of the events ruling ligand/protein interaction and an accurate estimation of the drug affinity to its target is of great help in speeding drug discovery strategies. We have developed a metadynamics-based approach, named funnel metadynamics, that allows the ligand to enhance the sampling of the target binding sites and its solvated states. This method leads to an efficient characterization of the binding free-energy surface and an accurate calculation of the absolute protein–ligand binding free energy. We illustrate our protocol in two systems, benzamidine/trypsin and SC-558/cyclooxygenase 2. In both cases, the X-ray conformation has been found as the lowest free-energy pose, and the computed protein–ligand binding free energy in good agreement with experiments. Furthermore, funnel metadynamics unveils important information about the binding process, such as the presence of alternative binding modes and the role of waters. The results achieved at an affordable computational cost make funnel metadynamics a valuable method for drug discovery and for dealing with a variety of problems in chemistry, physics, and material science. PMID:23553839
Exciton binding energy in a pyramidal quantum dot
Indian Academy of Sciences (India)
A ANITHA
2018-03-27
Mar 27, 2018 ... screening function on exciton binding energy in a pyramid-shaped quantum dot of ... tures may generate unique properties and they show .... where Ee is the ground-state energy of the electron in ... Figure 1. The geometry of the pyramidal quantum dot. base and H is the height of the pyramid which is taken.
Nucleon-nucleon theory and phenomenology. Progress report and renewal proposal
International Nuclear Information System (INIS)
Signell, P.
1981-01-01
Progress is outlined on five inter-related subprojects: (1) derivation of the intermediate range nucleon-nucleon interaction with the new dramatically altered ππ s-wave interaction and using a new method that utilizes much shorter and simpler analytic continuation through the unphysical region that lies between the πN and ππ physical regions of the N anti N → ππ amplitude (with significantly improved accuracy for the nucleon-nucleon interaction); (2) construction of a short range phenomenological potential that, with the theoretical part mentioned above, gives a precise fit to the nucleon-nucleon data and is parameterized for easy use in nucleon calculations; (3) phase shift analyses of the world data below 400 MeV, especially the large amount of very precise data below 20 MeV and the new data near 55 MeV that have never been analyzed properly, and determining which phases are given by theory at which energies; (4) the introduction of our K-matrix formulation of the Optimal Polynomial Expansion in order to accelerate convergence of the partial wave series at LAMPF energies; and (5) setting up of a cooperatively evaluated and verified permanent nucleon-nucleon data bank in the 0 to 1200 MeV range that can be used by all nucleon-nucleon researchers (or anyone else) via Telenet dial-in and by means of a published compendium
General aspects of the nucleon-nucleon interaction and nuclear matter properties
Energy Technology Data Exchange (ETDEWEB)
Plohl, Oliver
2008-07-25
The subject of the present thesis is at first the investigation of model independent properties of the nucleon-nucleon (NN) interaction in the vacuum concerning the relativistic structure and the implications for nuclear matter properties. Relativistic and non-relativistic meson-exchange potentials, phenomenological potentials s well as potentials based on effective field theory (EFT) are therefore mapped on a relativistic operator basis given by the Clifford Algebra. This allows to compare the various approaches at the level of covariant amplitudes where a remarkable agreement is found. Furthermore, the relativistic self-energy is determined in the Hartree-Fock (HF) approximation. The appearance of a scalar and vector field of several hundred MeV magnitude is a general feature of relativistic descriptions of nuclear matter. Within QCD sum rules these fields arise due to the density dependence of chiral condensates. We find that independent of the applied NN interaction large scalar and vector fields are generated when the symmetries of the Lorentz group are restored. In the framework of chiral EFT (chEFT) it is shown, that these fields are generated by short-range next-to-leading order (NLO) contact terms, which are connected to the spin-orbit interaction. To estimate the effect arising from NN correlations the equation of state of nuclear and neutron matter is calculated in the Brueckner-HF (BHF) approximation applying chEFT. Although, as expected, a clear over-binding is found (at NLO a saturating behavior is observed), the symmetry energy shows realistic properties when compared to phenomenological potentials (within the same approximation) and other approaches. The investigation of the pion mass dependence within chEFT at NLO shows that the magnitude of the scalar and vector fields persists in the chiral limit - nuclear matter is still bound. In contrast to the case of a pion mass larger than the physical one the binding energy and saturation density are
General aspects of the nucleon-nucleon interaction and nuclear matter properties
International Nuclear Information System (INIS)
Plohl, Oliver
2008-01-01
The subject of the present thesis is at first the investigation of model independent properties of the nucleon-nucleon (NN) interaction in the vacuum concerning the relativistic structure and the implications for nuclear matter properties. Relativistic and non-relativistic meson-exchange potentials, phenomenological potentials s well as potentials based on effective field theory (EFT) are therefore mapped on a relativistic operator basis given by the Clifford Algebra. This allows to compare the various approaches at the level of covariant amplitudes where a remarkable agreement is found. Furthermore, the relativistic self-energy is determined in the Hartree-Fock (HF) approximation. The appearance of a scalar and vector field of several hundred MeV magnitude is a general feature of relativistic descriptions of nuclear matter. Within QCD sum rules these fields arise due to the density dependence of chiral condensates. We find that independent of the applied NN interaction large scalar and vector fields are generated when the symmetries of the Lorentz group are restored. In the framework of chiral EFT (chEFT) it is shown, that these fields are generated by short-range next-to-leading order (NLO) contact terms, which are connected to the spin-orbit interaction. To estimate the effect arising from NN correlations the equation of state of nuclear and neutron matter is calculated in the Brueckner-HF (BHF) approximation applying chEFT. Although, as expected, a clear over-binding is found (at NLO a saturating behavior is observed), the symmetry energy shows realistic properties when compared to phenomenological potentials (within the same approximation) and other approaches. The investigation of the pion mass dependence within chEFT at NLO shows that the magnitude of the scalar and vector fields persists in the chiral limit - nuclear matter is still bound. In contrast to the case of a pion mass larger than the physical one the binding energy and saturation density are
Hyperon-nucleon and hyperon-hyperon interaction in the quark cluster model
International Nuclear Information System (INIS)
Straub, U.
1988-01-01
The nonrelativistic quark cluster model is used for the description of the hyperon-nucleon and hyperon-hyperon interaction. The different mass of the quarks is consistently regarded in the Hamiltonian and in the shape of the spatial wave functions of the quarks. The six-quark wave function is completely antisymmetrisized. By means of the resonating-group method the dynamic equations for the determination of the binding and scattering states of the six-quark problem are formulated. The corresponding resonating-group kernels are explicitely given. We calculate the lambda-nucleon and sigma-nucleon interaction. The sigma-nucleon scattering in the isospin (T=3/2) channel can be treated in a one-channel calculation. The sigma-nucleon (T=1/2) interaction and the lambda-nucleon interaction are studied in a coupled two-channel calculation. From a fit of the experimental lambda-nucleon interaction cross section the strength of the sigma-meson exchange is determined. The calculation of the sigma-nucleon scattering follows then completely parameterless. The agreement of the theory with the experiment is good. Subsequently the cluster model with this parameter is applied to the dihyperon which is a possibly bound state of two up quarks, two down quarks, and two strange quarks. We solve for this a coupled three-channel calculation. The cluster model presented here gives a binding energy of the dihyperon of (20±5) MeV below the lambda-lambda threshold. The mass of the dihyperon is predicted by this as (2211±5) MeV. (orig.) [de
Spin observables in nucleon-nucleus scattering
International Nuclear Information System (INIS)
Moss, J.M.
1982-01-01
The curse of inelastic nucleon scattering and charge exchange has always been the enormous complexity of the nucleon-nucleon (N-N) interaction. This complexity, however, can also be viewed as the ultimate promise of nucleons as probes of nuclear structure. Given an adequate theoretical basis, inelastic nucleon scattering is capable of providing information not obtainable with other probes. Recently a revolution of experimental technique has taken place that makes it desirable to re-examine the question of what physics is ultimately obtainable from inelastic nucleon scattering. It is now feasible to perform complete polarization transfer (PT) experiments for inelastic proton scattering with high efficiency and excellent energy resolution. Programs to measure PT obsevables are underway at several laboratories, and results are beginning to appear. Objectives of this presentation are to examine how such experiments are done, and what physics is presently obtained and may ultimately be learned from them
International Nuclear Information System (INIS)
Knyaz'kov, O.M.; Kukhtina, I.N.
1989-01-01
The integral characteristics of the potential distribution in nuclei, namely the volume integrals, moments and mean square radii are studied in the framework of the semimicroscopic approach to the interaction of low energy nucleons with nuclei on the base of the exchange nucleon-nucleon correlations and the density dependence of effective forces. The ratio of the normalized multipole moments of potential and matter distributions is investigated. The energy dependence of the integral characteristics is analyzed. 15 refs.; 2 tabs
Temperature and excitation energy of hot nuclei in the reaction of 40Ar+197Au at 25 MeV/nucleon
International Nuclear Information System (INIS)
Wu, H.; Jin, G.; Li, Z.; Dai, G.; Qi, Y.; He, Z.; Luo, Q.; Duan, L.; Wen, W.; Zhang, B.
1997-01-01
The coincidence measurements between heavy fission fragments and light charged particles with Z ≤2 were carried out for the 40 Ar+ 197 Au reaction at 25 MeV/nucleon, to study the properties of hot nuclei in heavy ion induced reactions. The linear momentum transfers (LMTs) were deduced from the folding angle and the time-of-flight difference between two fission fragments of heavy residues. The relationship of the nuclear temperature (slope parameter of the energy spectrum) and the excitation energy was determined independently from the measurement of the kinetic energy spectra in the frames of the emitting sources and from the LMT analysis. Both the temperature and the excitation energy increase with decreasing impact parameter, which suggests that a plateau temperature of 5.5 MeV is reached at an excitation energy of 3.1 MeV/nucleon. The result was also compared with various statistical models that explain the plateau by the multifragmentation process, where the excitation energy is assumed to be stored in compression and expansion effects. (orig.)
Electromagnetic structure of a bound nucleon
International Nuclear Information System (INIS)
Nogami, Y.
1977-01-01
The effect of binding on the electromagnetic (e.m.) structure of a nucleon in a nucleus is examined by means of a model consisting of a single nucleon which is bound in a harmonic oscillator potential and also coupled to the pion field through the Chew-Low interaction. The 'two-pion contribution' to the e.m. structure is considered. This is the part which is probably most susceptible to the binding effect. By the binding effect it is meant the one which arises because the nucleon wave functions, in the intermediate state as well as in the initial and final states, are distorted by the potential in which the nucleon is bound. This may be compared to a similar correction to the impulse approximation for pion-nucleus scattering. Unlike the latter which is likely to be quite appreciable, the binding correction to the e.m. structure of the nucleon is found to be negligibly small. The so-called quenching effect due to the Pauli principle when there are other nucleons is also discussed [pt
Analysis of experimental positron-molecule binding energies
International Nuclear Information System (INIS)
Danielson, J R; Surko, C M; Young, J A
2010-01-01
Experiments show that positron annihilation on molecules frequently occurs via capture into vibrational Feshbach resonances. In these cases, the downshifts in the annihilation spectra from the vibrational mode spectra provide measures of the positron-molecule binding energies. An analysis of these binding energy data is presented in terms of the molecular dipole polarizability, the permanent dipole moment, and the number of π bonds in aromatic molecules. The results of this analysis are in reasonably good agreement with other information about positron-molecule bound states. Predictions for other targets and promising candidate molecules for further investigation are discussed.
International Nuclear Information System (INIS)
Lleres, A.
1988-01-01
Velocity, angular distributions and total cross sections for heavy residues produced in the reactions 12 C, 14 N, 20 Ne, 40 Ar + 124 Sn have been measured in the 10-84 MeV/nucleon incident energy range using catchers technique in association with off-line gamma-activity spectroscopy. The observed reaction products are interpreted as evaporation residues from equilibrated systems formed by complete or incomplete fusion of the projectile and target nuclei. From the velocities and residual masses measured at forward angles, the linear momentum transfers and excitation energies associated with the intermediate systems are estimated using simple fusion-evaporation models and are next compared to the predictions of the preequilibrium and Fermi jets models. Energy, angular, charge and charge correlation distributions for intermediate mass fragments emitted in the reaction 32 S + nat Ag at 30 MeV/nucleon were also measured using gaseous and silicon detectors. The energy and angular distributions indicate that both equilibrated and non-equilibrated emitting sources are present. The equilibrium emission is attributed to the deexcitation of systems produced by incomplete fusion of the projectile and target nuclei. The charge correlation distributions are consistent with an asymmetric fission decay process. The linear momentum transfer and excitation energy associated with the equilibrated source are estimated using a simple fusion-fission model [fr
The axial polarizability of nucleons and nuclei
International Nuclear Information System (INIS)
Ericson, M.; Figureau, A.
1981-02-01
The part of the static nuclear axial polarizability arising from the nucleonic excitations is derived from the low energy expansion of the πN amplitude. It is shown that the contribution of the Δ intermediate state, though dominant, does not saturate the nucleonic response. A similar effect, though more pronounced, is known to occur for the magnetic susceptibility
International Nuclear Information System (INIS)
Plasil, F.; Albrecht, R.; Awes, T.C.
1989-01-01
The main goal of the CERN heavy-ion experiments is the search for an indication that the predicted state of deconfined quarks and gluons, the quark-gluon plasma (QGP), has been produced. The most promising indication that this may, in fact, be the case comes from the NA38 dimuon measurements, which are focused on the question of J//psi/ suppression. This effect was predicted to be one of the signatures of QGP formation before any measurements were made, and it is the subject of the two other talks at this conference that deal with nucleus-nucleus reactions at ultrarelativistic energies. In this presentation we consider the general (global) features of heavy-ion reactions at CERN energies, and we examine the degree to which they differ from mere superpositions of nucleon-nucleon collisions. We discuss the present status of our data analysis and our main conclusions from the first round of CERN experiments with emphasis on transverse energy measurements, on attained energy densities, and on the spectra of produced neutral pions. Because of time limitations we will not discuss our measurements of distributions of charged particles and the analysis of these distributions in terms of fluctuations nor the results that we have obtained with the Plastic Ball on the behavior of target spectator matter. 20 refs., 5 figs
Nuclear Cartography: Patterns in Binding Energies and Subatomic Structure
Simpson, E. C.; Shelley, M.
2017-01-01
Nuclear masses and binding energies are some of the first nuclear properties met in high school physics, and can be used to introduce radioactive decays, fusion, and fission. With relatively little extension, they can also illustrate fundamental concepts in nuclear physics, such as shell structure and pairing, and to discuss how the elements…
Polaron binding energy in polymers: poly[methyl(phenyl)silylene
Czech Academy of Sciences Publication Activity Database
Nožár, Juraj; Nešpůrek, Stanislav; Šebera, Jakub
2012-01-01
Roč. 18, č. 2 (2012), s. 623-629 ISSN 1610-2940 R&D Projects: GA AV ČR KAN400720701 Institutional research plan: CEZ:AV0Z40500505 Keywords : polaron * polaron binding energy * polysilane Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.984, year: 2012
p-wave pion production from nucleon-nucleon collisions
International Nuclear Information System (INIS)
Baru, V.; Epelbaum, E.; Haidenbauer, J.; Hanhart, C.; Kudryavtsev, A. E.; Lensky, V.; Meissner, U.-G.
2009-01-01
We investigate p-wave pion production in nucleon-nucleon collisions up to next-to-next-to-leading order in chiral effective field theory. In particular, we show that it is possible to describe simultaneously the p-wave amplitudes in the pn→ppπ - , pp→pnπ + , pp→dπ + channels by adjusting a single low-energy constant accompanying the short-range operator that is available at this order. This study provides a nontrivial test of the applicability of chiral effective field theory to reactions of the type NN→NNπ.
Inequalities and bounds for nucleon-nucleon scattering
International Nuclear Information System (INIS)
Ramandurai, K.S.
1979-08-01
The objective of this work is to derive model-independent inequalities and bounds for nucleon-nucleon elastic scattering amplitudes based on well-established theoretical principles and symmetries. Two classes of methods are used: algebraic and variational. In the algebraic part, the author derives inequalities and bounds for NN amplitudes and observables using their mutual relations and x symmetries. In the variational part, he employs Lagrange's method of undetermined multipliers to evaluate the bounds. He tests the predictions of a sample of proposed phase shifts at three different energies using the results obtained
Binding energy and formation heat of UO2
International Nuclear Information System (INIS)
Almeida, M.R. de; Veado, J.T.; Siqueira, M.L. de
The Born-Haber cycle is utilized for the calculation of the heat of formation of UO 2 , on the assumption that the binding energy is predominantly ionic in character. The ionization potentials of U and the repulsion energy are two critical values that influence calculations. Calculations of the ionization potentials with non-relativistic Hartree-Fock-Gaspar-Kohn-Sham approximation are presented [pt
The nucleon- nucleon interaction and symmetries
Energy Technology Data Exchange (ETDEWEB)
Van Oers, W T.H.
1992-11-01
With the advent of the possibility to study nucleon-nucleon scattering at medium energies, its extension to investigate fundamental symmetries was recognized early on. It was precisely the introduction of rotational invariance, parity conservation, time reversal invariance, and isotopic spin conversation that led to the description of the N - N scattering matrix in terms of five complex amplitudes: one set of five for proton-proton scattering and one set of five for neutron-proton scattering, or alternatively, one set for the isotopic spin state {iota}={omicron} and the other for the isotopic spin state {iota}=1. Clearly, if one or more of the above constraints are removed, there are additional amplitudes that need to be considered. To be meaningful, experiment requires observables that are particularly sensitive to the violation of a conservation law or symmetry principle. During the last decade a series of precision experiments has been performed to measure charge- symmetry breaking in n - p elastic scattering (corresponding to isotopic spin non-conservation), and to measure parity violation in p-p scattering. For a particle-anti-particle system,like the pp or {lambda}{lambda} system one can raise the question of CP violation in a system other than the neutral kaon system may become possible in the near future through pp {yields}{lambda}{lambda} and pp{yields} {identical_to} {identical_to}. A description is given of the ongoing efforts to measure charge symmetry breaking, parity violation and CP violation.(author). 42 refs., 6 figs.
International Nuclear Information System (INIS)
Hassan, M.Y.; Ramadan, S.
1978-01-01
The binding energy of nuclear matter with an excess of neutrons, with spin-up neutrons and spin-up protons (characterized by the corresponding parameters αsub(tau)=(N-Z)/A, αsub(n)=(N(up)-N(down))/A, and αsub(p)=(Z(up)-Z(down))/A) contains three symmetry energies: the isospin symmetry energy epsilon sub(tau), the spin symmetry energy epsilon sub(sigma) and the spin-isospin symmetry energy epsilon sub(sigma tau). These energies are calculated using velocity-dependent effective potential of s-wave interaction, which was developed by Dzhibuti and Mamasakhlisov. The spin, isospin and spin-isospin dependent parts of the single-particle potential in nuclear matter are also calculated using the same effective nucleon-nucleon potentials. The spin-spin part of the optical model potential is estimated. (author)
Alternate Energy Sources for Thermalplastic Binding Agent Consolidation
Energy Technology Data Exchange (ETDEWEB)
Frame, B.J.
1999-01-01
A study was conducted to investigate microwave and electron beam technologies as alternate energy sources to consolidate fiber coated with a thermoplastic binding agent into preforms for composite molding applications. Bench experiments showed that both microwave and electron beam energy can produce heat sufficient to melt and consolidate a thermoplastic binding agent applied to fiberglass mat, and several two- and three-dimensional fiberglass preforms were produced with each method. In both cases, it is postulated that the heating was accomplished by the effective interaction of the microwave or electron beam energy with the combination of the mat preform and the tooling used to shape the preform. Both methods contrast with conventional thermal energy applied via infrared heaters or from a heated tool in which the heat to melt the thermoplastic binding agent must diffuse over time from the outer surface of the preform toward its center under a thermal gradient. For these reasons, the microwave and electron beam energy techniques have the potential to rapidly consolidate thick fiber preforms more efficiently than the thermal process. With further development, both technologies have the potential to make preform production more cost effective by decreasing cycle time in the preform tool, reducing energy costs, and by enabling the use of less expensive tooling materials. Descriptions of the microwave and electron beam consolidation experiments and a summary of the results are presented in this report.
International Nuclear Information System (INIS)
Tezuka, Hirokazu.
1984-10-01
Scattering of a particle by bound nucleons is discussed. Effects of nucleons that are bound in a nucleus are taken as a structure function. The way how to calculate the structure function is given. (author)
International Nuclear Information System (INIS)
Sauer, P.U.
2014-01-01
In this paper, the role of three-nucleon forces in ab initio calculations of nuclear systems is investigated. The difference between genuine and induced many-nucleon forces is emphasized. Induced forces arise in the process of solving the nuclear many-body problem as technical intermediaries toward calculationally converged results. Genuine forces make up the Hamiltonian. They represent the chosen underlying dynamics. The hierarchy of contributions arising from genuine two-, three- and many-nucleon forces is discussed. Signals for the need of the inclusion of genuine three-nucleon forces are studied in nuclear systems, technically best under control, especially in three-nucleon and four-nucleon systems. Genuine three-nucleon forces are important for details in the description of some observables. Their contributions to observables are small on the scale set by two-nucleon forces. (author)
Three-body force in the three-nucleon system
International Nuclear Information System (INIS)
Gibson, B.F.
1986-01-01
A brief summary of the symposium is presented. Three-nucleon force models are discussed, including the two-pion exchange potential, NN-ΔN coupled-channels model, and phenomenological parametrization. Relevant experimental data and model calculations are discussed including form factors, binding energies, charge radii, and charge density for 3 H and 3 He. A calculation of the EMC effect for 3 He is also made using Sasakawa's wave function and compared to experimental data obtained at SLAC. The paper ends with discussions of proton-deuteron scattering, investigations at intermediate energies, and QCD efforts to understand the three-body problem
Polarized lepton-nucleon scattering
International Nuclear Information System (INIS)
Hughes, E.
1994-01-01
The author provides a summary of the proposed and published statistical (systematic) uncertainties from the world experiments on nucleon spin structure function integrals. By the time these programs are complete, there will be a vast resource of data on nucleon spin structure functions. Each program has quite different experimental approaches regarding the beams, targets, and spectrometers thus ensuring systematically independent tests of the spin structure function measurements. Since the field of spin structure function measurements began, there has been a result appearing approximately every five years. With advances in polarized target technology and high polarization in virtually all of the lepton beams, results are now coming out each year; this is a true signature of the growth in the field. Hopefully, the experiments will provide a consistent picture of nucleon spin structure at their completion. In summary, there are still many open questions regarding the internal spin structure of the nucleon. Tests of QCD via the investigation of the Bjorken sum rule is a prime motivator for the field, and will continue with the next round of precision experiments. The question of the origin of spin is still a fundamental problem. Researchers hope is that high-energy probes using spin will shed light on this intriguing mystery, in addition to characterizing the spin structure of the nucleon
Polarized lepton-nucleon scattering
Energy Technology Data Exchange (ETDEWEB)
Hughes, E. [Stanford Univ., CA (United States)
1994-12-01
The author provides a summary of the proposed and published statistical (systematic) uncertainties from the world experiments on nucleon spin structure function integrals. By the time these programs are complete, there will be a vast resource of data on nucleon spin structure functions. Each program has quite different experimental approaches regarding the beams, targets, and spectrometers thus ensuring systematically independent tests of the spin structure function measurements. Since the field of spin structure function measurements began, there has been a result appearing approximately every five years. With advances in polarized target technology and high polarization in virtually all of the lepton beams, results are now coming out each year; this is a true signature of the growth in the field. Hopefully, the experiments will provide a consistent picture of nucleon spin structure at their completion. In summary, there are still many open questions regarding the internal spin structure of the nucleon. Tests of QCD via the investigation of the Bjorken sum rule is a prime motivator for the field, and will continue with the next round of precision experiments. The question of the origin of spin is still a fundamental problem. Researchers hope is that high-energy probes using spin will shed light on this intriguing mystery, in addition to characterizing the spin structure of the nucleon.
Nucleon transfer between heavy nuclei
International Nuclear Information System (INIS)
Von Oertzen, W.
1984-02-01
Nucleon transfer reactions between heavy nuclei are characterized by the classical behaviour of the scattering orbits. Thus semiclassical concepts are well suited for the description of these reactions. In the present contribution the characteristics of single and multinucleon transfer reactions at energies below and above the Coulomb barrier are shown for systems like Sn+Sn, Xe+U and Ni+Pb. The role of the pairing interaction in the transfer of nucleon pairs is illustrated. For strong transitions the coupling of channels and the absorption into more complicated channels is taken into account in a coupled channels calculation
Nucleon-antinucleon interaction
International Nuclear Information System (INIS)
Dover, C.B.
1983-01-01
The current status of our understanding of the low energy nucleon-antinucleon (N anti N) interaction is reviewed. We compare several phenomenological models which fit the available N anti N cross section data. The more realistic of these models employ an annihilation potential W(r) which is spin, isospin and energy dependent. The microscopic origins for these dependences are discussed in terms of quark rearrangement and annihilation processes. It is argued that the study of N anti N annihilation offers a powerful means of studying quark dynamics at short distances. We also discuss how one may try to isolate coherent meson exchange contributions to the medium and long range part of the N anti N potential. These pieces of the N anti N interaction are calculable via the G-parity transformation from a model for the NN potential; their effects are predicted to be seen in N anti N spin observables, to be measured at LEAR. The possible existence of quasi-stable bound states or resonances of the anti N plus one or more nucleons is discussed, with emphasis on few-body systems. 42 references
International Nuclear Information System (INIS)
Brown, V.R.
1990-01-01
Nucleon-nucleon bremsstrahlung, NNγ, is a fundamental process, which involves the strong and electromagnetic fields acting simultaneously. Since the electromagnetic interaction is well known, NNγ provides a calculable tool for comparing off-energy-shell effects from different two-nucleon potentials compared to experiment and also provides a simple testing ground, which is sensitive to meson-exchange-current contributions that are so important in electronuclear physics. Historically, experimental studies have focused on ppγ, with only a few measurements of npγ. The present workshop was organized primarily to investigate the interest in, the value of, and the feasibility of doing an npγ experiment using the neutron white source at LANL. An increasing amount of US nuclear physics dollars are being spent on electronuclear physics. npγ is a fundamental process with large meson-exchange currents. In the npγ calculations of Brown and Franklin, the meson-exchange contributions increase the cross section by a factor of roughly two and later the angular distribution of the emitted photon dramatically. The details of these calculated effects have never been verified experimentally, but the proper quantum-mechanical inclusion of meson-exchange contributions, using the methods of brown and Franklin, has proved to be essential in understanding the heavy-ion results. The understanding of the importance of such terms is extremely important inelectronuclear processes, such as are presently under investigation or being planned at Bates, SLAC, and CEBAF. Just one example is in the electrodisintegration of the deuteron, where meson-exchange contributions must be included properly before any conclusions about nuclear models, such as QCD versus meson-exchange potentials can be made
Three-nucleon scattering by using chiral perturbation theory potential
International Nuclear Information System (INIS)
Kamata, Hiroyuki
2003-01-01
Three-nucleon scattering problems are studied by using two-nucleon and three-nucleon potentials derived from chiral perturbation theory. The three-nucleon term is shown to appear in the effective potential of the rank of next-to-next-to-leading order (NNLO). New three-nucleon forces are taken into consideration in addition to the conventional Fujita-Miyazawa (FM) type three-nucleon potential. Two-nucleon potential of the chiral perturbation theory is as precise as the conventional ones in low energy region. The FM type three-nucleon force which explains Sagara discrepancy in high energy region is introduced automatically. Concerning the Ay puzzle, the results seems to behave as if the puzzle has been solved at the level of NLO, but at the NNLO (without three-nucleon force) level the result is similar to the cases of conventional potential indicating the need of three-nucleon force. In contrast to the FM type three-nucleon force, five free parameters exist in the new D and E type three-nucleon forces introduced by the NNLO, but they are reduced to two independent parameters by antisymmetrization, which are found to be sensitive to the coupling energy of tritons and to the nd scattering length (spin doublet state). Parameters determined from them cannot give satisfactory answer to the A y puzzle. It seems, however, too hasty to conclude that A y puzzle cannot be solved by the chiral perturbation theory. (S. Funahashi)
Binding Energy, Vapor Pressure and Melting Point of Semiconductor Nanoparticles
International Nuclear Information System (INIS)
H. H. Farrell; C. D. Van Siclen
2007-01-01
Current models for the cohesive energy of nanoparticles generally predict a linear dependence on the inverse particle diameter for spherical clusters, or, equivalently, on the inverse of the cube root of the number of atoms in the cluster. Although this is generally true for metals, we find that for the group IV semiconductors, C, Si and Ge, this linear dependence does not hold. Instead, using first principles, density functional theory calculations to calculate the binding energy of these materials, we find a quadratic dependence on the inverse of the particle size. Similar results have also been obtained for the metallic group IV elements Sn and Pb. This is in direct contradiction to current assumptions. Further, as a consequence of this quadratic behavior, the vapor pressure of semiconductor nanoparticles rises more slowly with decreasing size than would be expected. In addition, the melting point of these nanoparticles will experience less suppression than experienced by metal nanoparticles with comparable bulk binding energies. This non-linearity also affects sintering or Ostwald ripening behavior of these nanoparticles as well as other physical properties that depend on the nanoparticle binding energy. The reason for this variation in size dependence involves the covalent nature of the bonding in semiconductors, and even in the 'poor' metals. Therefore, it is expected that this result will hold for compound semiconductors as well as the elemental semiconductors
International Nuclear Information System (INIS)
Curceanu, C.; Bazzi, M.; Beer, G.; Berucci, C.; Bombelli, L.; Bragadireanu, A.M.; Cargnelli, M.; Clozza, A.; D'Uffizi, A.; Fiorini, C.; Frizzi, T.; Ghio, F.; Guaraldo, C.; Hayano, R.S.; Iliescu, M.; Ishiwatari, T.; Iwasaki, M.; Kienle, P.; Levi Sandri, P.; Longoni, A.
2013-01-01
The DAΦNE electron–positron collider at the Laboratori Nazionali di Frascati of INFN has made available a unique quality low-energy negative kaons “beam”, which is being used to unlock the secrets of the kaon–nucleon/nuclei interactions at low energies by the SIDDHARTA(-2) and the AMADEUS experiments. SIDDHARTA has already performed unprecedented precision measurements of kaonic atoms, and is being presently upgraded, as SIDDHARTA-2, to approach new frontiers. The AMADEUS experiment already started a data taking with a dedicated carbon target, plans to perform in the coming years precision measurements on kaon–nuclei interactions at low-energies, in particular to study the possible formation of kaonic nuclei and the Λ(1405). The two experiments are briefly presented in this paper
Double Polarized Neutron-Proton Scattering and Meson-Exchange Nucleon-Nucleon Potential Models
International Nuclear Information System (INIS)
Raichle, B.W.; Gould, C.R.; Haase, D.G.; Seely, M.L.; Walston, J.R.; Tornow, W.; Wilburn, W.S.; Raichle, B.W.; Gould, C.R.; Haase, D.G.; Seely, M.L.; Walston, J.R.; Tornow, W.; Wilburn, W.S.; Penttilae, S.I.; Hoffmann, G.W.
1999-01-01
We report on polarized beam - polarized target measurements of the spin-dependent neutron-proton total cross-section differences in longitudinal and transverse geometries (Δσ L and Δσ T , respectively) between E n =5 and 20MeV. Single-parameter phase-shift analyses were performed to extract the phase-shift mixing parameter var-epsilon 1 , which characterizes the strength of the nucleon-nucleon tensor interaction at low energies. Consistent with the trend of previous determinations at E n =25 and 50MeV, our values for var-epsilon 1 imply a stronger tensor force than predicted by meson-exchange nucleon-nucleon potential models and nucleon-nucleon phase-shift analyses. copyright 1999 The American Physical Society
Calculation of the nucleon structure function from the nucleon wave function
Hussar, Paul E.
1993-01-01
Harmonic oscillator wave functions have played an historically important role in our understanding of the structure of the nucleon, most notably by providing insight into the mass spectra of the low-lying states. High energy scattering experiments are known to give us a picture of the nucleon wave function at high-momentum transfer and in a frame in which the nucleon is traveling fast. A simple model that crosses the twin bridges of momentum scale and Lorentz frame that separate the pictures of the nucleon wave function provided by the deep inelastic scattering data and by the oscillator model is presented.
Double polarized neutron-proton scattering and nucleon-nucleon tensor force: An alternative analysis
International Nuclear Information System (INIS)
Tornow, W.; Gould, C.R.; Haase, D.G.; Walston, J.R.; Raichle, B.W.
2002-01-01
Previous neutron-proton total cross-section difference measurements Δσ L and Δσ T between E n =7.43 and 17.1 MeV have been analyzed in a new way that reduces experimental systematic uncertainties. The results obtained for the 3 S 1 - 3 D 1 mixing parameter ε 1 are very similar to the published values, substantiating the previous conclusion that the nucleon-nucleon tensor force at low energies is stronger than predicted by the Nijmegen partial-wave analysis and, therefore, by all the recent high-precision nucleon-nucleon potential models as well
International Nuclear Information System (INIS)
Da Rocha, C.A.; Wilets, L.
1997-01-01
Complex mass poles, or ghost poles, are present in the Hartree-Fock solution of the Schwinger-Dyson equation for the nucleon propagator in renormalizable models with Yukawa-type meson-nucleon couplings, as shown many years ago by Brown, Puff and Wilets (BPW). These ghosts violate basic theorems of quantum field theory and their origin is related to the ultraviolet behavior of the model interactions. Recently, Krein et.al, proved that the ghosts disappear when vertex corrections are included in a self-consistent way, softening the interaction sufficiently in the ultraviolet region. In previous studies of πN scattering using ''dressed'' nucleon propagator and bare vertices, did by Nutt and Wilets in the 70's (NW), it was found that if these poles are explicitly included, the value of the isospin-even amplitude A (+) is satisfied within 20% at threshold. The absence of a theoretical explanation for the ghosts and the lack of chiral symmetry in these previous studies led us to re-investigate the subject using the approach of the linear σ-model and study the interplay of low-energy theorems for πN scattering and ghost poles. For bare interaction vertices we find that ghosts are present in this model as well and that the A (+) value is badly described. As a first approach to remove these complex poles, we dress the vertices with phenomenological form factors and a reasonable agreement with experiment is achieved. In order to fix the two cutoff parameters, we use the A (+) value for the chiral limit (m π →0) and the experimental value of the isoscalar scattering length. Finally, we test our model by calculating the phase shifts for the S waves and we find a good agreement at threshold. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Sargsyan, M M
1992-12-31
The effects of deeply bound nucleons are considered in the reaction of deuteron quasielastic electro disintegration, where the spectator nucleon and scattered electrons are registered in coincidence. Both, the off-shell influence on the description of nucleon motion in nuclear surrounding and the modification of deeply bound nucleon form - factors are investigated as two aspects of the off-shell effect manifestation. The possibility to control the extent of interacting nucleon binding energy by varying the spectator nucleon kinematic parameters (p{sub s},{theta}{sub s},{phi}{sub s}) is an advantage of the reactions considered. The cross section ratios of these processes are considered under specific kinematical conditions, which allow to investigate unambiguously the manifestations of deeply bound effects. To estimate the extent of the phenomena expected, we present the results of calculation of R ratios in the framework of models that take the off-shell effects into account differently. The effects of bound nucleon form - factor modification are estimated according to the model of mini delocalization, which predicts the bound nucleon swelling in nuclear environment. 28 refs.
Evaluation of binding energies by using quantum mechanical methods
International Nuclear Information System (INIS)
Postolache, Cristian; Matei, Lidia; Postolache, Carmen
2002-01-01
Evaluation of binding energies (BE) in molecular structure is needed for modelling chemical and radiochemical processes by quantum-chemical methods. An important field of application is evaluation of radiolysis and autoradiolysis stability of organic and inorganic compounds as well as macromolecular structures. The current methods of calculation do not allow direct determination of BE but only of total binding energies (TBE) and enthalpies. BEs were evaluated indirectly by determining the homolytic dissociation energies. The molecular structures were built and geometrically optimized by the molecular mechanics methods MM+ and AMBER. The energy minimizations were refined by semi-empirical methods. Depending on the chosen molecular structure, the CNDO, INDO, PM3 and AM1 methods were used. To reach a high confidence level the minimizations were done for gradients lower than 10 -3 RMS. The energy values obtained by the difference of the fragment TBLs, of the transition states and initial molecular structures, respectively, were associated to the hemolytic fragmentation energy and BE, respectively. In order to evaluate the method's accuracy and to establish the application fields of the evaluation methods, the obtained values of BEs were compared with the experimental data taken from literature. To this goal there were built, geometrically optimized by semi-empirical methods and evaluated the BEs for 74 organic and inorganic compounds (alkanes, alkene, alkynes, halogenated derivatives, alcohols, aldehydes, ketones, carboxylic acids, nitrogen and sulfur compounds, water, hydrogen peroxide, ammonia, hydrazine, etc. (authors)
Experimental electron binding energies for thulium in different matrices
Czech Academy of Sciences Publication Activity Database
Inoyatov, A. K.; Kovalík, Alojz; Filosofov, D. V.; Ryšavý, Miloš; Perevoshchikov, L. L.; Yushkevich, Yu. V.; Zbořil, M.
2015-01-01
Roč. 202, JUL (2015), s. 46-55 ISSN 0368-2048 R&D Projects: GA MŠk LG14004; GA ČR(CZ) GAP203/12/1896 Institutional support: RVO:61389005 Keywords : Tm-169 * (169)yb * atomic environment * electron binding energy * chemical shift * natural atomic level width Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.561, year: 2015
Pionic background for nucleon-nucleon observables
International Nuclear Information System (INIS)
Ballot, J.L.; Robilotta, M.R.
1992-01-01
A method is presented that allows the unambiguous definition of the one pion exchange contribution to nucleon-nucleon scattering observables and then use it to determine those waves where values of phase shifts and mixing parameters may be understood as sums of pionic and non-pionic dynamical effects. This helps the assessment of the explicative power of the various existing phenomenological potentials and may eventually lead to ways of discriminating their effectiveness. (author) 16 refs.; 19 figs.; 2 tabs
Energy Technology Data Exchange (ETDEWEB)
Abramov, B. M.; Alexeev, P. N.; Borodin, Yu. A.; Bulychjov, S. A. [National Research Center Kurchatov Institute, Institute for Theoretical and Experimental Physics (Russian Federation); Gudima, K. K. [Academy of Sciences of Moldova, Institute of Applied Physics (Moldova, Republic of); Dukhovskoy, I. A.; Krutenkova, A. P., E-mail: anna.krutenkova@itep.ru; Kulikov, V. V.; Martemianov, M. A.; Matsyuk, M. A. [National Research Center Kurchatov Institute, Institute for Theoretical and Experimental Physics (Russian Federation); Mashnik, S. G. [Los Alamos National Laboratory (United States); Turdakina, E. N.; Khanov, A. I. [National Research Center Kurchatov Institute, Institute for Theoretical and Experimental Physics (Russian Federation)
2016-09-15
The yields of long-lived nuclear fragments at an angle of 3.5° that originate fromthe fragmentation of carbon ions with an energy of T{sub 0} = 0.6 GeV per nucleon on a berylliumtarget were measured in the FRAGMexperiment at the ITEP TWA heavy-ion accelerator. The momentum spectra of these fragments cover both the fragmentation-maximum region and the cumulative region. The respective differential cross sections change by about five orders of magnitude. The momentum distributions of fragments in the laboratory frame and their kinetic-energy distributions in the rest frame of the fragmenting nucleus are used to test the predictions of four models of ion–ion interactions: BC, INCL++, LAQGSM03.03, and QMD.
2002-01-01
% EMU15 \\\\ \\\\ The aim of this experiment is to investigate high energy heavy ion central collisions by the use of emulsion magnetic chamber with high spatial resolution. The emulsion chamber consists of 50~emulsion layers 50~microns thick each coated on 25~microns mylar base. A thin lead target plate 300~microns thick is installed immediately in front of the first emulsion layer. It is placed in the transverse magnetic field B~$\\sim$~2~Tesla and is to be installed perpendicularly to Pb nucleus beam. This set-up enables to measure full 3-momenta and charge signs of secondary particles. \\\\ \\\\Specific goal is to carry out detailed analysis of individual events with super high multiplicity of secondaries. These data are to be used for investigation of properties of super hot/dense matter, in particular to look for and analyze possible manifestations of quark-gluon plasma in central Pb-Pb collisions at energies of 160~GeV/nucleon.
International Nuclear Information System (INIS)
La Tessa, C. . E-mail chiara@nephy.chalmers.se; Sihver, L.; Mancusi, D.; Zeitlin, C.; Miller, J.; Guetersloh, S.; Heilbronn, L.
2007-01-01
We have collected from the literature partial charge-changing cross sections for projectiles with charge 6=< Z=<26, energy ranging from 290 up to 2100 MeV/nucleon and interacting with several targets, in order to investigate weak and strong factorization properties. The same analysis methods as in our previous work have been applied to the data: we have shown that, except for hydrogen targets, weak and strong factorization properties are valid within 5%, thus confirming the results obtained in the first paper [C. La Tessa, et al., Test of weak and strong factorization in nucleus-nucleus collisions at several hundred MeV/nucleon, Nucl. Phys. A, in press]. Factorization parameters have been calculated and, in particular, target factors have been expressed with ad hoc analytical functions which describe the data trend very well. New expressions for weak and strong factorization properties can then be obtained by substituting the target factors with these functions: this formulation partially isolates the dependence of the partial charge-changing cross sections on the target and projectile mass numbers; moreover, fragment factors are the only parameters left in the formulas thus facilitating the future task of interpolating them with appropriate analytical expressions
Investigation of incomplete linear momentum transfer in heavy ion reactions at intermediate energies
International Nuclear Information System (INIS)
Leray, S.
1986-07-01
At intermediate energies, heavy ion central collisions lead to the incomplete fusion of the incident nuclei while part of the initial linear momentum is carried away by fast light particles. Experiments were performed with 30 MeV per nucleon neon and 20, 35 and 44 MeV per nucleon argon projectiles bombarding heavy targets. Results obtained with 30 MeV per nucleon neon and 20 MeV per nucleon argon beams are in good agreement with an empirical law established with lighter projectiles. On the contrary, 35 and 44 MeV per nucleon argon projectiles do not follow the same law and fission fragments progressively disappear. A simple model explains the evolution of the amount of transferred linear momentum versus incident energy. The disappearance of the fusion products of the composite system observed with argon projectiles beyond 35 MeV per nucleon is explained by a limitation of the excitation energy per nucleon which can be deposited in a nucleus. The limit is evaluated from nucleon binding energy in nuclei and probability to emit clusters and is in good agreement with experimental data. Because of the coupling between intrinsic motion of nucleons and relative motion of nuclei, some nucleons have a kinetic energy high enough to be emitted: a theoretical model is proposed which rather well fits the data concerning fast nucleons but cannot explain the measured amounts of transferred linear momentum. This is attributed to the existence of other mechanisms [fr
Energy Technology Data Exchange (ETDEWEB)
Kubis, Bastian. E-mail: b.kubis@fz-juelich.de; Meissner, Ulf-G. E-mail: Ulf-G.Meissner@fz-juelich.de
2001-01-01
We analyze the electromagnetic form factors of the nucleon to fourth order in relativistic baryon chiral perturbation theory. We employ the recently proposed infrared regularization scheme and show that the convergence of the chiral expansion is improved as compared to the heavy-fermion approach. We also discuss the inclusion of vector mesons and obtain an accurate description of all four-nucleon form factors for momentum transfer squared up to Q{sup 2}{approx_equal}0.4 GeV{sup 2}.
Sampling and energy evaluation challenges in ligand binding protein design.
Dou, Jiayi; Doyle, Lindsey; Jr Greisen, Per; Schena, Alberto; Park, Hahnbeom; Johnsson, Kai; Stoddard, Barry L; Baker, David
2017-12-01
The steroid hormone 17α-hydroxylprogesterone (17-OHP) is a biomarker for congenital adrenal hyperplasia and hence there is considerable interest in development of sensors for this compound. We used computational protein design to generate protein models with binding sites for 17-OHP containing an extended, nonpolar, shape-complementary binding pocket for the four-ring core of the compound, and hydrogen bonding residues at the base of the pocket to interact with carbonyl and hydroxyl groups at the more polar end of the ligand. Eight of 16 designed proteins experimentally tested bind 17-OHP with micromolar affinity. A co-crystal structure of one of the designs revealed that 17-OHP is rotated 180° around a pseudo-two-fold axis in the compound and displays multiple binding modes within the pocket, while still interacting with all of the designed residues in the engineered site. Subsequent rounds of mutagenesis and binding selection improved the ligand affinity to nanomolar range, while appearing to constrain the ligand to a single bound conformation that maintains the same "flipped" orientation relative to the original design. We trace the discrepancy in the design calculations to two sources: first, a failure to model subtle backbone changes which alter the distribution of sidechain rotameric states and second, an underestimation of the energetic cost of desolvating the carbonyl and hydroxyl groups of the ligand. The difference between design model and crystal structure thus arises from both sampling limitations and energy function inaccuracies that are exacerbated by the near two-fold symmetry of the molecule. © 2017 The Authors Protein Science published by Wiley Periodicals, Inc. on behalf of The Protein Society.
Chiral perturbation theory with nucleons
International Nuclear Information System (INIS)
Meissner, U.G.
1991-09-01
I review the constraints posed on the interactions of pions, nucleons and photons by the spontaneously broken chiral symmetry of QCD. The framework to perform these calculations, chiral perturbation theory, is briefly discussed in the meson sector. The method is a simultaneous expansion of the Greens functions in powers of external moments and quark masses around the massless case, the chiral limit. To perform this expansion, use is made of a phenomenological Lagrangian which encodes the Ward-identities and pertinent symmetries of QCD. The concept of chiral power counting is introduced. The main part of the lectures of consists in describing how to include baryons (nucleons) and how the chiral structure is modified by the fact that the nucleon mass in the chiral limit does not vanish. Particular emphasis is put on working out applications to show the strengths and limitations of the methods. Some processes which are discussed are threshold photopion production, low-energy compton scattering off nucleons, πN scattering and the σ-term. The implications of the broken chiral symmetry on the nuclear forces are briefly described. An alternative approach, in which the baryons are treated as very heavy fields, is touched upon
Excitation of Nucleon Resonances
International Nuclear Information System (INIS)
Burkert, Volker D.
2001-01-01
I discuss developments in the area of nucleon resonance excitation, both necessary and feasible, that would put our understanding of nucleon structure in the regime of strong QCD on a qualitatively new level. They involve the collection of high quality data in various channels, a more rigorous approach in the search for ''missing'' resonances, an effort to compute some critical quantities in nucleon resonance excitations from first principles, i.e. QCD, and a proposal focused to obtain an understanding of a fundamental quantity in nucleon structure
Kaus, Joseph W; Harder, Edward; Lin, Teng; Abel, Robert; McCammon, J Andrew; Wang, Lingle
2015-06-09
Recent advances in improved force fields and sampling methods have made it possible for the accurate calculation of protein–ligand binding free energies. Alchemical free energy perturbation (FEP) using an explicit solvent model is one of the most rigorous methods to calculate relative binding free energies. However, for cases where there are high energy barriers separating the relevant conformations that are important for ligand binding, the calculated free energy may depend on the initial conformation used in the simulation due to the lack of complete sampling of all the important regions in phase space. This is particularly true for ligands with multiple possible binding modes separated by high energy barriers, making it difficult to sample all relevant binding modes even with modern enhanced sampling methods. In this paper, we apply a previously developed method that provides a corrected binding free energy for ligands with multiple binding modes by combining the free energy results from multiple alchemical FEP calculations starting from all enumerated poses, and the results are compared with Glide docking and MM-GBSA calculations. From these calculations, the dominant ligand binding mode can also be predicted. We apply this method to a series of ligands that bind to c-Jun N-terminal kinase-1 (JNK1) and obtain improved free energy results. The dominant ligand binding modes predicted by this method agree with the available crystallography, while both Glide docking and MM-GBSA calculations incorrectly predict the binding modes for some ligands. The method also helps separate the force field error from the ligand sampling error, such that deviations in the predicted binding free energy from the experimental values likely indicate possible inaccuracies in the force field. An error in the force field for a subset of the ligands studied was identified using this method, and improved free energy results were obtained by correcting the partial charges assigned to the
2016-01-01
Recent advances in improved force fields and sampling methods have made it possible for the accurate calculation of protein–ligand binding free energies. Alchemical free energy perturbation (FEP) using an explicit solvent model is one of the most rigorous methods to calculate relative binding free energies. However, for cases where there are high energy barriers separating the relevant conformations that are important for ligand binding, the calculated free energy may depend on the initial conformation used in the simulation due to the lack of complete sampling of all the important regions in phase space. This is particularly true for ligands with multiple possible binding modes separated by high energy barriers, making it difficult to sample all relevant binding modes even with modern enhanced sampling methods. In this paper, we apply a previously developed method that provides a corrected binding free energy for ligands with multiple binding modes by combining the free energy results from multiple alchemical FEP calculations starting from all enumerated poses, and the results are compared with Glide docking and MM-GBSA calculations. From these calculations, the dominant ligand binding mode can also be predicted. We apply this method to a series of ligands that bind to c-Jun N-terminal kinase-1 (JNK1) and obtain improved free energy results. The dominant ligand binding modes predicted by this method agree with the available crystallography, while both Glide docking and MM-GBSA calculations incorrectly predict the binding modes for some ligands. The method also helps separate the force field error from the ligand sampling error, such that deviations in the predicted binding free energy from the experimental values likely indicate possible inaccuracies in the force field. An error in the force field for a subset of the ligands studied was identified using this method, and improved free energy results were obtained by correcting the partial charges assigned to the
Binding energy and single–particle Energies in the 16 0 region ...
African Journals Online (AJOL)
... single-particle energies in the oxygen region by folding together a Hamiltonian in the rest-frame of the nucleus with two-body correlation functions based on the Njimegen potential. We have found that the binding energies are very sensitive to the core radius rc and that the effects of tensor correlations are non-negligible.
Measurement of Exciton Binding Energy of Monolayer WS2
Chen, Xi; Zhu, Bairen; Cui, Xiaodong
Excitonic effects are prominent in monolayer crystal of transition metal dichalcogenides (TMDCs) because of spatial confinement and reduced Coulomb screening. Here we use linear differential transmission spectroscopy and two-photon photoluminescence excitation spectroscopy (TP-PLE) to measure the exciton binding energy of monolayer WS2. Peaks for excitonic absorptions of the direct gap located at K valley of the Brillouin zone and transitions from multiple points near Γ point of the Brillouin zone, as well as trion side band are shown in the linear absorption spectra of WS2. But there is no gap between distinct excitons and the continuum of the interband transitions. Strong electron-phonon scattering, overlap of excitons around Γ point and the transfer of the oscillator strength from interband continuum to exciton states make it difficult to resolve the electronic interband transition edge even down to 10K. The gap between excited states of the band-edge exciton and the single-particle band is probed by TP-PLE measurements. And the energy difference between 1s exciton and the single-particle gap gives the exciton binding energy of monolayer WS2 to be about 0.71eV. The work is supported by Area of excellency (AoE/P-04/08), CRF of Hong Kong Research Grant Council (HKU9/CRF/13G) and SRT on New Materials of The University of Hong Kong.
Charge compensation and binding energy referencing in XPS analysis
International Nuclear Information System (INIS)
Metson, J.B.
1999-01-01
Full text: The past decade has seen a number of significant advances in the capabilities of commercial X-ray Photoelectron spectrometers. Of note have been the near universal adoption of monochromatised X-ray sources, very useful advances in spatial resolution, particularly in spectroscopy, and radical developments in sample handling and automation. However one of the most significant advances has been the development of several relatively new concepts in charge compensation. Throughout the evolution of XPS, the ability to compensate for surface charging and accurately determine binding energies, particularly with electrically inhomogenous samples, has remained one of the most intractable problems. Beginning perhaps with the Kratos, 'in the lens' electrostatic mirror/electron source coupled with a magnetic snorkel lens, a number of concepts have been advanced which take a quite different conceptual approach to charge compensation. They differ in a number of quite fundamental ways to the electron flood type compensators widely used and absolutely essential with instruments based on monochromatised sources. The concept of the local return of secondary electrons to their point of emission, largely negates the problems associated with differential charging across different regions of the surface, and suggests the possibility of overcoming one of the central limitations of XPS, that is the inability to compare absolute binding energies of species in different electrical as well as chemical environments. The general status of charge compensation and the use of internal binding energy references in XPS will be reviewed, along with some practical examples of where these techniques work, and where there is clearly still room for further development. Copyright (1999) Australian X-ray Analytical Association Inc
International Nuclear Information System (INIS)
Ftacnik, J.; Lichard, P.
1989-01-01
We present a set of semiquantitative predictions for the behaviour of J/ψ suppression in heavy ion collisions as a function of the total transverse energy, nucleon numbers of colliding ions and the J/ψ transverse momentum. These predictions are based on the assumption that all of J/ψ suppression is due to J/ψ and χ disintegrations in collisions with hadrons in a dense hadronic gas formed in the heavy ion collisions. The hydrodynamic evolution of the hadron gas is taken into account. The onset of the quark-gluon plasma formation should manifest itself by clear qualitative deviations from J/ψ suppression calculated in this way, in particular as thresholds or kinks in the E T -dependence, or as a threshold for J/ψ suppression as a function of the atomic number of the target, expected at Cu or below. (orig.)
The nucleon-nucleon interaction in the framework of the boson exchange model
International Nuclear Information System (INIS)
Niephaus, G.H.
1984-01-01
The aim of this thesis was the description of the nucleon-nucleon interaction in a microscopically founded model. For this the description of the 2-nucleon problem by an interacting 2-nucleon-pion system was presented. The starting point of our description was a relativistic eigenvalue equation for the system of mesons and two baryons. The interaction of the baryons with the mesons was described by interaction Hamiltonians. By the elimination of antinucleon states by means of a unitary tansformation (Foldy-Wouthuysen transformation) the interaction Hamiltonians for nucleons could be generated for the field-theoretical Lagrangian densities. The Hamiltonians for resonant baryon states were obtained by means of a simplified procedure from the corresponding Lagrangian densities. Because the determination of Lagrangian densities is not unique, for the pion-nucleon coupling two alternative Lagrangian densities were allowed. For the interaction of positive-energy nucleonic states these two coupling yield nearly equal results; the production or annihilation of negative-energy nucleon states (antiparticles) the predictions however are very different. (orig./HSI) [de
2014-01-01
Background Binding free energy and binding hot spots at protein-protein interfaces are two important research areas for understanding protein interactions. Computational methods have been developed previously for accurate prediction of binding free energy change upon mutation for interfacial residues. However, a large number of interrupted and unimportant atomic contacts are used in the training phase which caused accuracy loss. Results This work proposes a new method, βACV ASA , to predict the change of binding free energy after alanine mutations. βACV ASA integrates accessible surface area (ASA) and our newly defined β contacts together into an atomic contact vector (ACV). A β contact between two atoms is a direct contact without being interrupted by any other atom between them. A β contact’s potential contribution to protein binding is also supposed to be inversely proportional to its ASA to follow the water exclusion hypothesis of binding hot spots. Tested on a dataset of 396 alanine mutations, our method is found to be superior in classification performance to many other methods, including Robetta, FoldX, HotPOINT, an ACV method of β contacts without ASA integration, and ACV ASA methods (similar to βACV ASA but based on distance-cutoff contacts). Based on our data analysis and results, we can draw conclusions that: (i) our method is powerful in the prediction of binding free energy change after alanine mutation; (ii) β contacts are better than distance-cutoff contacts for modeling the well-organized protein-binding interfaces; (iii) β contacts usually are only a small fraction number of the distance-based contacts; and (iv) water exclusion is a necessary condition for a residue to become a binding hot spot. Conclusions βACV ASA is designed using the advantages of both β contacts and water exclusion. It is an excellent tool to predict binding free energy changes and binding hot spots after alanine mutation. PMID:24568581
Conflicting coupling of unpaired nucleons in odd-odd nuclei
International Nuclear Information System (INIS)
Volkov, D.A.; Levon, A.I.
1990-01-01
Phenomenological approach is described, using it, energy spectra of odd-odd nucleus collective bands based on conflicting state of unpaired nucleons can be calculated. It is ascertained that in a conflicting bond unpaired nucleon acts as a spectator, i.e. energy spectra of collective bands in odd-odd nuclei are similar to the spectra of collective bands in heighbouring odd nuclei, which are based on the state of a strongly bound nucleon is included in the conflicting configuration
Improvements in centrifugal nucleon disintegration of CND reactors
International Nuclear Information System (INIS)
Pedrick, A.P.
1976-01-01
Reference is made to the so-called 'Centrifugal Nucleon Disintegrator Reactor' (CND) in which it is proposed to release the binding energy between nucleons of high atomic number by applying a violent spin to the nuclei. The reactor described comprises means for producing atomic nuclei that have been stripped of their electrons by heating to form a high temperature plasma. A number of laser beams are directed on to a cylinder having a polished bore and reflected therefrom so as to create tangentially a cylindrical wall or surface having a high concentration of photons moving unidirectionally, together with means for introducing nuclei into the cylindrical wall or surface of photons. A high electrostatic charge is applied to urge the nuclei against the cylindrical wall or surface. The nuclei are discharged into the space between the cylinder and the photon wall. Nucleons that have been separated from their nuclei are carried upwards in a flow of plasma, which can be arranged to produce an electrical output by interaction with an electromagnetic field. (U.K.)
Forward pion-nucleon charge exchange reaction and Regge constraints
International Nuclear Information System (INIS)
Huang Fei; Sibirtsev, A.; Krewald, S.; Hanhart, C.; Haidenbauer, J.; Meibner, U.-G.
2009-01-01
We present our recent study of pion-nucleon charge exchange amplitudes above 2 GeV. We analyze the forward pion-nucleon charge exchange reaction data in a Regge model and compare the resulting amplitudes with those from the Karlsruhe-Helsinki and George-Washington-University partial-wave analyses. We explore possible high-energy constraints for theoretical baryon resonance analyses in the energy region above 2 GeV. Our results show that for the pion-nucleon charge exchange reaction, the appropriate energy region for matching meson-nucleon dynamics to diffractive scattering should be around 3 GeV for the helicity flip amplitude. (authors)
Energy Technology Data Exchange (ETDEWEB)
Dobretsov, Yu; Dolgoshein, B; Kirillov-Ugryumov, V
1980-12-01
The properties and formation are described of ..mu..-nucleon atoms, the Larmor method of muon spin precession is discussed and the experimental confirmation of the existence of ..mu..-nucleon atoms is shown. The prospects of their use are indicated.
International Nuclear Information System (INIS)
Dobretsov, Yu.; Dolgoshejn, B.; Kirillov-Ugryumov, V.
1980-01-01
The properties and formation are described of μ-nucleon atoms, the Larmor method of muon spin precession is discussed and the experimental confirmation of the existence of μ-nucleon atoms is shown. The prospects of their use are indicated. (J.P.)
Nucleon-nucleon scattering phase shifts
International Nuclear Information System (INIS)
Bryan, R.
1978-01-01
Here are presented 0 to 800 MeV nucleon-nucleon elastic and inelastic phase parameters derived by several groups: Arndt and Roper; Hoshizaki; Bugg; Bystricky, Lechanoine, and Lehar; and Bryan, Clark, and VerWest. Resonant-like behavior appears in the 1 D 2 and 3 F 3 states above the inelastic threshold in Hoshizaki's analysis but not in Arndt and Roper's. The np data are inadequate to permit determination of the I = O phase parameters above 600 MeV. 27 references
An Accurate Redetermination of the $^{118}Sn$ Binding Energy
Borzakov, S B; Faikow-Stanczyk, H; Grigoriev, Yu V; Panteleev, T; Pospísil, S; Smotritsky, L M; Telezhnikov, S A
2001-01-01
The energy of well-known strong {gamma}-line from {{^198}Au}, the "gold standard", has been modified in the light of new adjustments in the fundamental constants and the value of 411.80176(12) keV was determined which is 0.29 eV lower than the latest 1999 value. An energy calibration procedure for determining the neutron binding energy, {B_n}, from complicated {(n , gamma)}-spectra has been developed. A mathematically simple minimization function consisting only of terms having as parameters the coefficients of the energy calibration curve (polynomial) is used. A priori information about the relationships among the energies of different peaks on the spectrum is taking into account by a Monte Carlo simulation. The procedure was used in obtaining of {B_n} for {{^118}Sn} and {{^64}Cu}. The {gamma}-ray spectrum from thermal neutron radiative capture by {{^117}Sn} has been measured on the IBR-2 pulsed reactor. {gamma}-rays were detected by a 72 cm^3 HPGe-detector. {B_n} for {{^64}Cu} was obtained from two {gamma}-...
Exciton binding energy in a pyramidal quantum dot
Anitha, A.; Arulmozhi, M.
2018-05-01
The effects of spatially dependent effective mass, non-parabolicity of the conduction band and dielectric screening function on exciton binding energy in a pyramid-shaped quantum dot of GaAs have been investigated by variational method as a function of base width of the pyramid. We have assumed that the pyramid has a square base with area a× a and height of the pyramid H=a/2. The trial wave function of the exciton has been chosen according to the even mirror boundary condition, i.e. the wave function of the exciton at the boundary could be non-zero. The results show that (i) the non-parabolicity of the conduction band affects the light hole (lh) and heavy hole (hh) excitons to be more bound than that with parabolicity of the conduction band, (ii) the dielectric screening function (DSF) affects the lh and hh excitons to be more bound than that without the DSF and (iii) the spatially dependent effective mass (SDEM) affects the lh and hh excitons to be less bound than that without the SDEM. The combined effects of DSF and SDEM on exciton binding energy have also been calculated. The results are compared with those available in the literature.
Non-abelian binding energies from the lightcone bootstrap
Energy Technology Data Exchange (ETDEWEB)
Li, Daliang [Department of Physics, Yale University,New Haven, CT 06511 (United States); Department of Physics and Astronomy, Johns Hopkins University,Baltimore, MD 21218 (United States); Meltzer, David [Department of Physics, Yale University,New Haven, CT 06511 (United States); Poland, David [Department of Physics, Yale University,New Haven, CT 06511 (United States); School of Natural Sciences, Institute for Advanced Study,Princeton, NJ 08540 (United States)
2016-02-23
We analytically study the lightcone limit of the conformal bootstrap for 4-point functions containing scalars charged under global symmetries. We show the existence of large spin double-twist operators in various representations of the global symmetry group. We then compute their anomalous dimensions in terms of the central charge C{sub T}, current central charge C{sub J}, and the OPE coefficients of low dimension scalars. In AdS, these results correspond to the binding energy of two-particle states arising from the exchange of gravitons, gauge bosons, and light scalar fields. Using unitarity and crossing symmetry, we show that gravity is universal and attractive among different types of two-particle states, while the gauge binding energy can have either sign as determined by the representation of the two-particle state, with universal ratios fixed by the symmetry group. We apply our results to 4D N=1 SQCD and the 3D O(N) vector models. We also show that in a unitary CFT, if the current central charge C{sub J} stays finite when the global symmetry group becomes infinitely large, such as the N→∞ limit of the O(N) vector model, then the theory must contain an infinite number of higher spin currents.
International Nuclear Information System (INIS)
Signell, P.
1981-01-01
This project has involved five inter-related subprojects: (1) derivation of the intermediate range nucleon-nucleon interaction using a new method that utilizes much shorter and simpler analytic continuation through the unphysical region that lies between the πN and ππ physical regions of the N anti N → ππ amplitude (with signifantly improved accuracy for the nucleon-nucleon interaction); (2) construction of a short range phenomenological potential that, with the theoretical part mentioned above, gives a precise fit to the nucleon-nucleon data and is parameterized for easy use in nucleon calculations; (3) phase shift analyses of the world data below 400 MeV, especially the large amount of very precise data below 20 meV and the new data near 55 MeV that have never been analyzed properly; (4) the introduction of a K-matrix formulation of the Optimal Polynomial Expansion in order to accelerate convergence of the partial wave series at LAMPF energies; and (5) setting up of a cooperatively evaluated permanent nucleon-nucleon data bank in the 1-1200 MeV range that can be used by all nucleon-nucleon researchers
Radical conservatism and nucleon decay
International Nuclear Information System (INIS)
Wilczek, Frank
2000-01-01
Unification of couplings, observation of neutrino masses in the expected range, and several other considerations confirm central implications of straightforward gauge unification based on SO(10) or a close relative and incorporating low-energy supersymmetry. The remaining outstanding consequence of this circle of ideas, yet to be observed, is nucleon instability. Clearly, we should aspire to be as specific as possible regarding the rate and form of such instability. I argue that not only esthetics, but also the observed precision of unification of couplings, favors an economical symmetry-breaking (Higgs) structure. Assuming this, one can exploit its constraints to build reasonably economical, overconstrained yet phenomenologically viable models of quark and lepton masses. Putting it all together, one arrives at reasonably concrete, hopeful expectations regarding nucleon decay. These expectations are neither ruled out by existing experiments, nor hopelessly inaccessible. Furthermore, the branching fractions can discriminate among different possibilities for physics at the unification scale
Energy Technology Data Exchange (ETDEWEB)
Chand, Ramesh
1963-10-15
Total scattering and absorption cross sections for anti K-nucleon collisions in I = 1, p_{3/2} - channel are given as functions of the two sets of energy dependent anti KN scattering parameters solutions, called solution A' and solution B'. These scattering parameters are obtained by linear interpolations between Watson's amplitudes around 400 MeV/c and the amplitude at the position of the pole in the anti KN scattering amplitude corresponding to the p_{3/2}-wave 1385 MeV Y_{1}-resonance with 50 MeV width. The zero-range expansion for p-wave anti K-nucleon phase shift and the scattering parameters of Watson's solution B are found to be in violation of the requirements of causality and of positive definiteness of transition probabilities. (auth)
International Nuclear Information System (INIS)
Sadler, M.E.
1984-01-01
This study is a continuation of the pion-nucleon program at the Los Alamos Meson Physics Facility. Previous measurements, in chronological order, have included differential cross sections for π/sup +-/p elastic scattering at P/sub π/ = 378 - 687 MeV/c (LAMPF experiment 363), π - p charge exchange for P/sub π/ = 247 - 687 MeV/c (LAMPF experiment 120), and measurements of the polarization asymmetry for π/sup +-/p -> π/sup +-/p and π - p -> π 0 n for P/sub π/ = 471 - 687 MeV/c (LAMPF experiments 120* and 120**, respectively). Two experiments were initiated in the past year, forward-angle differential cross sections for π - p -> π 0 n at P/sub π/ = 96 - 150 MeV/c (LAMPF experiment 809) and polarization asymmetry for π - p - > γn (LAMPF experiment 804). Approved experiments which will be scheduled in the future are spin rotation measurements for π/sup +-/p -> π/sup +-/p (LAMPF experiments 806 and 807) and differential cross sections for π - p -> π 0 n near 0 0 and 180 0 at P/sub π/ = 471-687 MeV/c (LAMPF experiment 849). Another experiment, differential cross section measurements for π/sup +-/ elastic scattering on 3 He and 3 H (LAMPF experiment 546), has also been completed. The 3 He and 3 H targets form an isospin doublet analogous to the proton and neutron. The I 3 = -1/2 member ( 3 H) of the multiplet can be utilized as a target in this case, allowing a direct test of charge symmetry not achievable in the πN system due to the impossibility of a pure neutron target
Two- and three-nucleon chiral interactions in quantum Monte Carlo calculations for nuclear physics
Energy Technology Data Exchange (ETDEWEB)
Lynn, Joel [Institut fuer Kernphysik, Technische Universitaet Darmstadt, 64289 Darmstadt (Germany); Tews, Ingo [Institute for Nuclear Theory, University of Washington, Seattle, Washington 98195 (United States); Carlson, Joseph; Gandolfi, Stefano [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Gezerlis, Alexandros [Department of Physics, University of Guelph, Guelph, Ontario, N1G 2W1 (Canada); Schmidt, Kevin [Department of Physics, Arizona State University, Tempe, Arizona 85287 (United States); Schwenk, Achim [Institut fuer Kernphysik, Technische Universitaet Darmstadt, 64289 Darmstadt (Germany); ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, 64291 Darmstadt (Germany)
2016-07-01
I present our recent work on Green's function Monte Carlo calculations of light nuclei using local two- and three-nucleon interactions derived from chiral effective field theory up to next-to-next-to-leading order (N{sup 2}LO). I discuss the choice of observables we make to fit the two low-energy constants which enter in the three-nucleon sector at N{sup 2}LO: the {sup 4}He binding energy and n-α elastic scattering P-wave phase shifts. I then show some results for light nuclei. I also show our results for the energy per neutron in pure neutron matter using the auxiliary-field diffusion Monte Carlo method and discuss regulator choices. Finally I discuss some exciting future projects which are now possible.
Effective pion--nucleon interaction in nuclear matter
International Nuclear Information System (INIS)
Celenza, L.S.; Liu, L.C.; Nutt, W.; Shakin, C.M.
1976-01-01
We discuss the modification of the interaction between a pion and a nucleon in the presence of an infinite medium of nucleons (nuclear matter). The theory presented here is covariant and is relevant to the calculation of the pion--nucleus optical potential. The specific effects considered are the modifications of the nucleon propagator due to the Pauli principle and the modification of the pion and nucleon propagators due to collisions with nucleons of the medium. We also discuss in detail the pion self-energy in the medium, paying close attention to off-shell effects. These latter effects are particularly important because of the rapid variation with energy of the fundamental pion--nucleon interaction. Numerical results are presented, the main feature being the appearance of a significant damping width for the (3, 3) resonance
International Nuclear Information System (INIS)
Eletsky, V.L.
1991-01-01
The problem of temperature dependence of nucleon mass is addressed by considering a retarded correlator of two currents with quantum numbers of a nucleon at finite temperature T π in the chiral limit. It is shown that at Euclidean momenta the leading one-loop corrections arise from direct interaction of thermal pions with the currents. A dispersive representation for the correlator shows that this interaction smears the nucleon pole over frequency interval with width ∼ T. This interaction does not change the exponential fall-off of the correlator in Euclidean space but gives an O(T 2 /F π 2 ) contribution to the pre-exponential factor. 11 refs. (author)
Universal binding energy relation for cleaved and structurally relaxed surfaces
International Nuclear Information System (INIS)
Srirangarajan, Aarti; Datta, Aditi; Gandi, Appala Naidu; Ramamurty, U; Waghmare, U V
2014-01-01
The universal binding energy relation (UBER), derived earlier to describe the cohesion between two rigid atomic planes, does not accurately capture the cohesive properties when the cleaved surfaces are allowed to relax. We suggest a modified functional form of UBER that is analytical and at the same time accurately models the properties of surfaces relaxed during cleavage. We demonstrate the generality as well as the validity of this modified UBER through first-principles density functional theory calculations of cleavage in a number of crystal systems. Our results show that the total energies of all the relaxed surfaces lie on a single (universal) energy surface, that is given by the proposed functional form which contains an additional length-scale associated with structural relaxation. This functional form could be used in modelling the cohesive zones in crack growth simulation studies. We find that the cohesive law (stress–displacement relation) differs significantly in the case where cracked surfaces are allowed to relax, with lower peak stresses occurring at higher displacements. (paper)
Universal binding energy relation for cleaved and structurally relaxed surfaces.
Srirangarajan, Aarti; Datta, Aditi; Gandi, Appala Naidu; Ramamurty, U; Waghmare, U V
2014-02-05
The universal binding energy relation (UBER), derived earlier to describe the cohesion between two rigid atomic planes, does not accurately capture the cohesive properties when the cleaved surfaces are allowed to relax. We suggest a modified functional form of UBER that is analytical and at the same time accurately models the properties of surfaces relaxed during cleavage. We demonstrate the generality as well as the validity of this modified UBER through first-principles density functional theory calculations of cleavage in a number of crystal systems. Our results show that the total energies of all the relaxed surfaces lie on a single (universal) energy surface, that is given by the proposed functional form which contains an additional length-scale associated with structural relaxation. This functional form could be used in modelling the cohesive zones in crack growth simulation studies. We find that the cohesive law (stress-displacement relation) differs significantly in the case where cracked surfaces are allowed to relax, with lower peak stresses occurring at higher displacements.
An accurate redetermination of the 118Sn binding energy
International Nuclear Information System (INIS)
Borzakov, S.B.; Panteleev, Ts.Ts.; Telezhnikov, S.A.; Chrien, R.E.; Faikow-Stanczyk, H.; Grigor'ev, Yu.V.; Pospisil, S.; Smotritskij, L.M.
2001-01-01
The energy of well-known strong γ-line from 198 Au, the 'gold standard', has been modified in the light of new adjustments in the fundamental constants and the value of 411.80176(12) keV was determined which is 0.29 eV lower than the latest 1999 value. An energy calibration procedure for determining the neutron binding energy, B n , from complicated (n,γ)-spectra has been developed. A mathematically simple minimization function consisting only of terms having as parameters the coefficients of the energy calibration curve (polynomial) is used. A priori information about the relationships among the energies of different peaks on the spectrum was taken into account by a Monte Carlo simulation. The procedure was used in obtaining of B n for 118 Sn and 64 Cu. The γ-ray spectrum from thermal neutron radiative capture by 117 Sn has been measured on the IBR-2 pulsed reactor. γ-rays were detected by a 72 cm 2 HPGe-detector. B n for 64 Cu was obtained from two γ-spectra. One spectrum was measured on the IBR-2 by the same detector. The other spectrum was measured with a pair spectrometer at the Brookhaven High Flux Beam Reactor. From these two spectra B n for 64 Cu was determined equal to 7915.52(8) keV. The mean value of two most precise results of B n for 118 Sn was determined to be 9326.35(9) keV. The B n for 57Fe was determined to be 7646.08(9) keV
QCD sum rule for nucleon in nuclear matter
International Nuclear Information System (INIS)
Mallik, S.; Sarkar, Sourav
2010-01-01
We consider the two-point function of nucleon current in nuclear matter and write a QCD sum rule to analyse the residue of the nucleon pole as a function of nuclear density. The nucleon self-energy needed for the sum rule is taken as input from calculations using phenomenological N N potential. Our result shows a decrease in the residue with increasing nuclear density, as is known to be the case with similar quantities. (orig.)
International Nuclear Information System (INIS)
Gulamov, K.G.; Navotny, V.Sh.; Uzhinskii, V.V.
1999-01-01
Experimental data on the distributions of fragments with respect to the bound charge (Z bound , Z b3 ) and with respect to the multiplicities and on their correlations are presented. These data are compared with analogous data at 600 MeV per projectile nucleon that were obtained at the ALADIN facility. It has been shown that the processes of gold-nucleus multifragmentation at intermediate and high energies have some common features. At the same time, the multiplicity of medium-mass fragments becomes somewhat less at high energies. Data presented in this study are analyzed within the framework combining the statistical model of nuclear multifragmentation with the Regge model of the breakup of nuclei. This combined model has been shown to reproduce qualitatively the experimental results under discussion. The most pronounced discrepancies have been observed for the yields of doubly charged fragments. The transverse momenta of fragments have been analyzed as functions of the bound charge Z bound . It has been demonstrated that the model underestimates considerably the transverse momenta of fragments. This is interpreted as evidence for a strong radial flow of spectator fragments
Attained energy densities and neutral pion spectra in nucleus-nucleus collisions at 200 GeV/nucleon
International Nuclear Information System (INIS)
Plasil, F.; Albrecht, R.; Awes, T.C.
1989-01-01
The main goal of the CERN heavy-ion experiments is the search for an indication that the predicted state of deconfined quarks and gluons, the quark-gluon plasma (QGP), has been produced. The quantity most crucial to the probability of QGP formation is the thermalized energy density attained during the heavy-ion reaction. The amount of energy radiated transverse to the beam direction is the experimental quantity which is believed to be a measure of the amount of energy deposition in the reaction, and hence to reflect the energy density attained. In this presentation we consider the systematics of transverse energy production at CERN SPS energies, and we use the results to make estimates, under various assumptions, of attained energy densities. 18 refs., 2 figs
International Nuclear Information System (INIS)
Jiang Weizhou; Li Baoan; Chen Liewen
2007-01-01
The mean free paths and in-medium scattering cross sections of energetic nucleons in neutron-rich nucleonic matter are investigated using the nucleon optical potential obtained within the relativistic impulse approximation with the empirical nucleon-nucleon scattering amplitudes and the nuclear densities obtained in the relativistic mean-field model. It is found that the isospin-splitting of nucleon mean free paths, sensitive to the imaginary part of the symmetry potential, changes its sign at certain high kinetic energy. The in-medium nucleon-nucleon cross sections are analytically and numerically demonstrated to be essentially independent of the isospin asymmetry of the medium and increase linearly with density in the high-energy region where the relativistic impulse approximation is applicable
Transport Gap and exciton binding energy determination in organic semiconductors
Energy Technology Data Exchange (ETDEWEB)
Krause, Stefan; Schoell, Achim; Reinert, Friedrich; Umbach, Eberhard [University of Wuerzburg (Germany). Experimental Physics II; Casu, Benedetta [Inst. f. Physik. u. Theor. Chemie, Tuebingen (Germany)
2008-07-01
The transport gap of an organic semiconductor is defined as the energy difference between the HOMO and LUMO levels in the presence of a hole or electron, respectively, after relaxation has occurred. Its knowledge is mandatory for the optimisation of electronic devices based on these materials. UV photoelectron spectroscopy (UPS) and inverse photoelectron spectroscopy (IPES) are routinely applied to measure these molecular levels. However, the precise determination of the transport gap on the basis of the respective data is not an easy task. It involves fundamental questions about the properties of organic molecules and their condensates, about their reaction on the experimental probe, and on the evaluation of the spectroscopic data. In particular electronic relaxation processes, which occur on the time scale of the photo excitation, have to be considered adequately. We determined the transport gap for the organic semiconductors PTCDA, Alq3, DIP, CuPc, and PBI-H4. After careful data analysis and comparison to the respective values for the optical gap we obtain values for the exciton binding energies between 0.1-0.5 eV. This is considerably smaller than commonly believed and indicates a significant delocalisation of the excitonic charge over various molecular units.
International Nuclear Information System (INIS)
Abbas, Afsar
1992-01-01
The surprising answer to this question Is nucleon deformed? is : Yes. The evidence comes from a study of the quark model of the single nucleon and when it is found in a nucleus. It turns out that many of the long standing problems of the Naive Quark Model are taken care of if the nucleon is assumed to be deformed. Only one value of the parameter P D ∼1/4 (which specifies deformation) fits g A (the axial vector coupling constant) for all the semileptonic decay of baryons, the F/D ratio, the pion-nucleon-delta coupling constant fsub(πNΔ), the double delta coupling constant 1 fsub(πΔΔ), the Ml transition moment μΔN and g 1 p the spin structure function of proton 2 . All this gives strong hint that both neutron and proton are deformed. It is important to look for further signatures of this deformation. When this deformed nucleon finds itself in a nuclear medium its deformation decreases. So much that in a heavy nucleus the nucleons are actually spherical. We look into the Gamow-Teller strengths, magnetic moments and magnetic transition strengths in nuclei to study this property. (author). 15 refs
Potentials of the inverse scattering problem in the three-nucleon problem
International Nuclear Information System (INIS)
Pushkash, A.M.; Simenog, I.V.; Shapoval, D.V.
1993-01-01
Possibilities of using the method of the inverse scattering problem for describing simultaneously the two-nucleon and the low-energy three-nucleon data in the S-interaction approximation are examined. 20 refs., 3 figs., 1 tab
Effect of isovector coupling channel on the macroscopic part of the nuclear binding energy
International Nuclear Information System (INIS)
Haddad, S.
2011-04-01
The effect of the isovector coupling channel on the macroscopic part of the nuclear binding energy is determined utilizing the relativistic density dependent Thomas-Fermi approach for the calculation of the macroscopic part of the nuclear binding energy, and the dependency of this effect on the numbers of neutrons and protons is studied. The isovector coupling channel leads to increased nuclear binding energy, and this effect sharpens with growing excess of the number of neutrons on the number of protons. (author)
Nucleon-nucleon scattering and different meson exchanges
International Nuclear Information System (INIS)
Osman, A.
1985-10-01
The iterative and noniterative diagrams with different meson exchange are investigated. The α, πβ and πγ meson exchange, (where α=π, rho, σ, ω, eta and delta; β=π, rho, σ and ω; γ=π and rho), are considered. These diagrams are taken to involve the nucleon-nucleon, the nucleon-isobar and the isobar-isobar intermediate states. The diagrams are calculated in momentum space following the noncovariant perturbation theory. The role of each of these diagrams is examined by calculating its contribution to the nucleon-nucleon interaction. The potential model is taken to include one-boson-exchange terms in addition to these diagrams. The nucleon-nucleon scattering phase shifts are described successfully showing the importance of tensor force. The contributions of the different parts are studied in the nucleon-nucleon scattering. (author)
K-nucleon scattering and the cloudy bag model
International Nuclear Information System (INIS)
Jennings, B.K.
1986-01-01
The cloudy bag model (CBM) has been applied with considerable success to low energy meson-nucleon scattering. In this talk I will describe in particular calculations for kaon-nucleon and antikaon-nucleon scattering. The main emphasis will be on s-waves with special attention paid to the antikaon-nucleon system in the isospin zero channel where the Λ(1405) is important. In the CBM the Λ(1405) is an antikaon-nucleon bound state and I show that this interpretation is consistent with the antikaon-nucleon scattering in the region of the Λ(1670) and Λ(1800) although ambiguities in the phase shift analysis prevent a definite conclusion
K-nucleon scattering and the cloudy bag model
Jennings, B. K.
1986-10-01
The cloudy bag model (CBM) has been applied with considerable success to low energy meson-nucleon scattering. In this talk I will describe in particular calculations for kaon-nucleon and antikaon-nucleon scattering. The main emphasis will be on s-waves with special attention paid to the antikaon-nucleon system in the isospin zero channel where the Λ(1405) is important. In the CBM the Λ(1405) is an antikaon-nucleon bound state and I show that this interpretation is consistent with the antikaon-nucleon scattering in the region of the Λ(1670) and Λ(1800) although ambiguities in the phase shift analysis prevent a definite conclusion.
Single nucleon-nucleon collision model for subthreshold pion production in heavy ion collisions
International Nuclear Information System (INIS)
Bellini, V.; Di Toro, M.; Bonasera, A.
1985-01-01
We show that inclusive experimental data on subthreshold pion production in 12 C + 12 C and 16 O + 12 C collisions can be reproduced using a first chance Nucleon-Nucleon (NN) collision mechanism. Pauli blocking effects are extremely important while π-resorption can be safely neglected for these light systems. We apply our method at various beam energies. The possible importance of collective dynamical effects around the physical threshold is finally suggested
Theoretical aspects of the nucleon-nucleon workshop
International Nuclear Information System (INIS)
Silbar, R.R.
1984-01-01
This report concentrates on the inelastic NN system from 300 to 1500 MeV. Topics covered include the visibility of quark signals, dibaryons, the model dependence of predicted NN inelasticities, and a review of how well present conventional models compare with a rapidly expanding database. The general conclusion is that there is so far no clear evidence in the NN system at intermediate energies for unconventional dibaryon resonances. Short remarks are also made concerning one theoretical contribution on elastic scattering and on new experimental results for deuteron photo-disintegration and pion-nucleon charge exchange. 11 references
Chiral nucleon-nucleon forces in nuclear structure calculations
Directory of Open Access Journals (Sweden)
Coraggio L.
2016-01-01
Full Text Available Realistic nuclear potentials, derived within chiral perturbation theory, are a major breakthrough in modern nuclear structure theory, since they provide a direct link between nuclear physics and its underlying theory, namely the QCD. As a matter of fact, chiral potentials are tailored on the low-energy regime of nuclear structure physics, and chiral perturbation theory provides on the same footing two-nucleon forces as well as many-body ones. This feature fits well with modern advances in ab-initio methods and realistic shell-model. Here, we will review recent nuclear structure calculations, based on realistic chiral potentials, for both finite nuclei and infinite nuclear matter.
Influence of nucleon density distribution in nucleon emission probability
International Nuclear Information System (INIS)
Paul, Sabyasachi; Nandy, Maitreyee; Mohanty, A.K.; Sarkar, P.K.; Gambhir, Y.K.
2014-01-01
Different decay modes are observed in heavy ion reactions at low to intermediate energies. It is interesting to study total neutron emission in these reactions which may be contributed by all/many of these decay modes. In an attempt to understand the importance of mean field and the entrance channel angular momentum, we study their influence on the emission probability of nucleons in heavy ion reactions in this work. This study owes its significance to the fact that once population of different states are determined, emission probability governs the double differential neutron yield
Neudachin, V G; Yudin, N P
2002-01-01
Investigation of the dominant role of the simplest t-pole diagrams is completed in the processes of pion electroproduction on nucleons at quasielastic knock out kinematics and electron energies of a few GeV. Competition role of pi- and rho-meson t-pole diagrams and s-pole diagram (tree diagram) is regarded. When virtual photon mass is large enough (Q sup 2 >= 2 (GeV/c) sup 2), the latter amplitude is not essential both for longitudinal (d sigma sub L /dt) and for transverse (d sigma sub T /dt) cross sections. At Q sup 2 = 0.7 (GeV/c) sup 2 in the longitudinal cross section the interference term between pion t-pole and s-pole amplitudes is still essential. Vertex functions g subrho sub N sub N (t), obtained from the cross sections of the quasielastic knockout of rho mesons and from cross section of pion photoproduction, are compared. Their discrepancy must give impulse to the development of gauge invariant theory of pion photoproduction
International Nuclear Information System (INIS)
Roche, G.; Koontz, R.; Mulera, T.; Pugh, H.G.; Schroeder, L.S.; Hallman, T.; Madansky, L.; Carroll, J.; Chang, C.C.; Kirk, P.N.; Krebs, G.; Vicente, J.
1985-01-01
A particle-gamma coincidence experiment has been performed with a 2.1 GeV per nucleon 12 C beam from the Bevalac. Data were taken with C and Pb targets. The γ-ray spectra are almost independent of the energy or the kind of charged particles detected in coincidence, mainly protons and deuterons. These γ-ray spectra are interpreted as resulting from π 0 decay, and are consistent with known π 0 production rates. A search for a possible decay of singly-charged anomalons into a gamma and a deuteron (or unbound proton-neutron system) has been done by studying the γp and γd invariant mass distributions. The upper limits for such a process are found to be 2 to 20% of the deuteron production rate, for anomalon masses for 200 to 400 MeV above the deuteron mass, with an anomalon mean lifetime of up to 10 -9 s, depending on which kind of decay process is considered. (orig.)
Weisel, G. J.; Tornow, W.; Esterline, J. H.
2015-08-01
We present measurements of n-d analyzing power, {A}y(θ ), at En = 21.0 MeV. The experiment produces neutrons via the 2H(d, n)3He reaction and uses a deuterated liquid-scintillator center detector and six pairs of liquid-scintillator neutron side detectors. Elastic neutron scattering events are identified by using time-of-flight techniques and by setting a gate in the center-detector pulse-height spectrum. Beam polarization is monitored by using a high-pressure helium gas scintillator. The n-d {A}y(θ ) data at 21.0 MeV show a significant discrepancy with the results of rigorous three-body calculations and are consistent with data taken previously by us at 19.0 and 22.5 MeV. We review the overall energy dependence of the three-nucleon analyzing power puzzle in neutron-deuteron elastic scattering, using the best data available. We find that the relative difference between calculations and data is nearly constant at 25% up to En = 22.5 MeV.
International Nuclear Information System (INIS)
Tornow, T.; Tornow, W.
1999-01-01
It Is shown that the 3 P j neutron-proton (proton-proton) phase shifts cannot be determined to less than ± 100 % (± 20 %) uncertainty at low energies (∼ 10 MeV), even if high-accuracy nucleon-nucleon data were to become available for currently inaccessible observables. For a more accurate determination, appropriate theoretical constraints have to be invoked, but their accuracy can be judged only from the comparison of rigorous three-nucleon continuum calculations with particular three-nucleon observables. (author)
Influence of host matrices on krypton electron binding energies and KLL Auger transition energies
Czech Academy of Sciences Publication Activity Database
Inoyatov, A. K.; Perevoshchikov, L. L.; Kovalík, Alojz; Filosofov, D. V.; Yushkevich, Yu. V.; Ryšavý, Miloš; Lee, B. Q.; Kibédi, T.; Stuchbery, A. E.; Zhdanov, V. S.
2014-01-01
Roč. 197, DEC (2014), s. 64-71 ISSN 0368-2048 R&D Projects: GA ČR(CZ) GAP203/12/1896; GA MŠk LG14004 Institutional support: RVO:61389005 Keywords : Kr-83 * Rb-83 * Sr-83 * electron binding energy * KLL transitions * natural atomic level width * multiconfiguration Dirac-Fock calculations Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.436, year: 2014
The nucleon-nucleon potential in the chromodielectric soliton model
International Nuclear Information System (INIS)
Koepf, W.; Wilets, L.; Pepin, S.; Stancu, F.
1993-01-01
The short- and medium-range parts of the nucleon-nucleon interaction are being studied in the framework of the chromodielectric soliton model. The model consists of current quarks, gluons in the abelian approximation, and a scalar σ field which simulates the nonabelian interactions of the gluons and governs the medium through the dielectric function κ(σ). Absolute color confinement is effected by the vanishing of the dielectric in vacuum; this also removes the troublesome van der Waals problem. The authors distinguish between spatial confinement, which arises from the self energy of the quarks in medium (excluding MFA contributions), and color confinement which is effected through OGE in the MFA (including the corresponding self energy contributions). The static (adiabatic) energies are computed as a function of deformation (generalized bag separation) in a constrained MFA. Six quark molecular-type wave functions in all important space-spin-isospin-color configurations are included. The gluon propagator is solved in the deformed dielectric medium. The resultant Hamiltonian matrix is diagonalized. Dynamics are handled in the Generator Coordinate Method, which leads to the Hill-Wheeler integral equation. In the present case, this yields a set of coupled equations corresponding to the various configurations. Although this can be approximated by a set of differential equations, they propose to solve the integral equations with some regularization scheme
Roy–Steiner-equation analysis of pion–nucleon scattering
Directory of Open Access Journals (Sweden)
Meißner U.-G.
2017-01-01
Full Text Available Low-energy pion–nucleon scattering is relevant for many areas in nuclear and hadronic physics, ranging from the scalar couplings of the nucleon to the long-range part of two-pion-exchange potentials and three-nucleon forces in Chiral Effective Field Theory. In this talk, we show how the fruitful combination of dispersion-theoretical methods, in particular in the form of Roy–Steiner equations, with modern high-precision data on hadronic atoms allows one to determine the pion–nucleon scattering amplitudes at low energies with unprecedented accuracy. Special attention will be paid to the extraction of the pion–nucleon σ-term, and we discuss in detail the current tension with recent lattice results, as well as the determination of the low-energy constants of chiral perturbation theory.c
Roy-Steiner-equation analysis of pion-nucleon scattering
Meißner, U.-G.; Ruiz de Elvira, J.; Hoferichter, M.; Kubis, B.
2017-03-01
Low-energy pion-nucleon scattering is relevant for many areas in nuclear and hadronic physics, ranging from the scalar couplings of the nucleon to the long-range part of two-pion-exchange potentials and three-nucleon forces in Chiral Effective Field Theory. In this talk, we show how the fruitful combination of dispersion-theoretical methods, in particular in the form of Roy-Steiner equations, with modern high-precision data on hadronic atoms allows one to determine the pion-nucleon scattering amplitudes at low energies with unprecedented accuracy. Special attention will be paid to the extraction of the pion-nucleon σ-term, and we discuss in detail the current tension with recent lattice results, as well as the determination of the low-energy constants of chiral perturbation theory.
Inclusive break-up reactions of 6Li at an incident energy of 26 MeV/nucleon
International Nuclear Information System (INIS)
Shyam, R.; Machner, H.; Neumann, B.; Rebel, H.; Gils, H.J.; Planeta, R.; Buschmann, J.; Klewe-Nebenius, H.; Zagromski, S.
1982-01-01
Inclusive charged particle spectra were measured from nuclear reactions induced by 156 MeV 6 Li on 40 Ca. At forward angles the spectra exhibit broad break-up distributions centered around the energy corresponding to the beam velocity. The double differential cross sections together with previous results for a 208 Pb target were analyzed in the framework of the DWBA approach to projectile break-up taking into account elastic and inelastic reactions of the break-up fragments. The high energy tails of the background due to preequilibrium emission of complex charged particles were estimated on the basis of the coalescence model. (orig.) [de
Inclusive break-up reactions of 6Li at an incident energy of 26 MeV/nucleon
International Nuclear Information System (INIS)
Neumann, B.; Rebel, H.; Gils, H.J.; Planeta, R.; Buschmann, J.; Klewe-Nebenius, H.; Zagromski, S.; Shyam, R.; Machner, H.
1982-01-01
Inclusive charged particle spectra were measured from nuclear reactions induced by 156 MeV 6 Li on 40 Ca. At forward angles the spectra exhibit broad break-up distributions centered around the energy corresponding to the beam velocity. The double differential cross sections together with previous results for a 208 Pb target were analyzed in the framework of the DWBA approach to projectile break-up taking into account elastic and inelastic reactions of the break-up fragments. The high energy tails of the background due to preequilibrium emission of complex charged particles were estimated on the basis of the coalescence model. (orig.)
The spin structure of the nucleon
International Nuclear Information System (INIS)
Deur, A.
2008-02-01
This document describes the recent experimental results on the spin structure of the nucleon obtained with the electron accelerator Thomas Jefferson National Facility (Jefferson Lab), Virginia. We first discuss the goal of studying the nucleon spin structure and give the basis and phenomenology of high energy lepton scattering. Then, we discuss with some details a few sum rules concerning the spin structure of the nucleon. Those are important tools for studying the nucleon spin structure at Jefferson Lab. We then describe the present experimental situation and analyze the results. We have been able to determine an effective coupling constant for the strong interaction for any regime of quantum chromodynamics which proves that QCD is an approximately conformal theory. We conclude on the perspectives for this field of research, in particular with the 12 GeV energy upgrade of Jefferson Lab. The top priority will be the measurement of generalised parton distributions. The only issue that will stay misunderstood is the role of the very low x domain on the spin structure of the nucleon
Nuclear matter studies with density-dependent meson-nucleon coupling constants
International Nuclear Information System (INIS)
Banerjee, M.K.; Tjon, J.A.; Banerjee, M.K.; Tjon, J.A.
1997-01-01
Due to the internal structure of the nucleon, we should expect, in general, that the effective meson nucleon parameters may change in nuclear medium. We study such changes by using a chiral confining model of the nucleon. We use density-dependent masses for all mesons except the pion. Within a Dirac-Brueckner analysis, based on the relativistic covariant structure of the NN amplitude, we show that the effect of such a density dependence in the NN interaction on the saturation properties of nuclear matter, while not large, is quite significant. Due to the density dependence of the g σNN , as predicted by the chiral confining model, we find, in particular, a looping behavior of the binding energy at saturation as a function of the saturation density. A simple model is described, which exhibits looping and which is shown to be mainly caused by the presence of a peak in the density dependence of the medium modified σN coupling constant at low density. The effect of density dependence of the coupling constants and the meson masses tends to improve the results for E/A and density of nuclear matter at saturation. From the present study we see that the relationship between binding energy and saturation density may not be as universal as found in nonrelativistic studies and that more model dependence is exhibited once medium modifications of the basic nuclear interactions are considered. copyright 1997 The American Physical Society
Toy model for pion production in nucleon-nucleon collisions
International Nuclear Information System (INIS)
Hanhart, C.; Miller, G. A.; Myhrer, F.; Sato, T.; Kolck, U. van
2001-01-01
We develop a toy model for pion production in nucleon-nucleon collisions that reproduces some of the features of the chiral Lagrangian calculations. We calculate the production amplitude and examine some common approximations
Maurer, Manuela; de Beer, Stephanie B A; Oostenbrink, Chris
2016-04-15
The periplasmic oligopeptide binding protein A (OppA) represents a well-known example of water-mediated protein-ligand interactions. Here, we perform free-energy calculations for three different ligands binding to OppA, using a thermodynamic integration approach. The tripeptide ligands share a high structural similarity (all have the sequence KXK), but their experimentally-determined binding free energies differ remarkably. Thermodynamic cycles were constructed for the ligands, and simulations conducted in the bound and (freely solvated) unbound states. In the unbound state, it was observed that the difference in conformational freedom between alanine and glycine leads to a surprisingly slow convergence, despite their chemical similarity. This could be overcome by increasing the softness parameter during alchemical transformations. Discrepancies remained in the bound state however, when comparing independent simulations of the three ligands. These difficulties could be traced to a slow relaxation of the water network within the active site. Fluctuations in the number of water molecules residing in the binding cavity occur mostly on a timescale larger than the simulation time along the alchemical path. After extensive simulations, relative binding free energies that were converged to within thermal noise could be obtained, which agree well with available experimental data.
Energy Technology Data Exchange (ETDEWEB)
Pinnaduwage, Lal A [ORNL; Boiadjiev, Vassil I [ORNL; Fernando, G. W. [University of Connecticut, Storrs; Hawk, J. E. [Oak Ridge National Laboratory (ORNL); Wijewardhana, L.C. R. [University of Cincinnati; Gehl, Anthony C [ORNL
2008-01-01
Microcantilevers are ideally-suited for the study of surface phenomena due to their large surface-to-volume ratios, which amplify surface effects. We show that when guest molecules bind to atoms/molecules on a microcantilever surface, the released binding energy is retained in the host surface, leading to a metastable state where the excess energy on the surface is manifested as an increase in surface stress leading to the bending of the microcantilever. When the excess energy is released, the microcantilever relaxes back to the original state, and the relaxation time depends on the particular binding process involved. Such experiments were conducted for three binding processes in vapor phase experiments: physisorption, hydrogen bonding, and chemisorption. To our knowledge, such an energy conservation approach has not been taken into account in adsorbate-induced surface effect investigations. Furthermore, these experiments illustrate that detailed molecular-level information on binding energies can be extracted from this simple micromechanical sensor.
Lectures on the soliton theory of nucleons
International Nuclear Information System (INIS)
Ripka, G.
1984-04-01
In these lectures we describe models in which the pion field or, more precisely, the chiral fields, are responsible for the binding of quarks in the nucleon. Such bound states in which the quarks constitute a source for the chiral fields, which, in turn, bind the quarks to each other, are called solitons. The starting point for such theories or models are chiral invariant lagrangians. They are not derived from QCD. The Skyrme lagrangian is simpler in that it involves only chiral fields and no quarks. However it may be understood as an effective lagrangian from which the quark degrees of freedom have been integrated out. It is not yet clear to what extent various models are equivalent. The description of the nucleon in these lectures may be viewed as an extension of the T.D. Lee solitons so as to include the pionic degree of freedom
Block, Martin M
2002-01-01
Using an eikonal structure for the scattering amplitude, factorization theorems for nucleon-nucleon, gamma p and gamma gamma scattering at high energies have been derived, using only some very general assumptions. Using a QCD-inspired eikonal analysis of nucleon-nucleon scattering, we present here experimental confirmation for factorization of cross sections, nuclear slope parameters B and rho -values (ratio of real to imaginary portion of forward scattering amplitudes), showing that: 1) the three factorization theorems of Block and Kaidalov [2000] hold, 2) the additive quark model holds to approximately=1%, and 3) vector dominance holds to better than approximately=4%. Predictions for the total cross section, elastic cross section and other forward scattering parameters at the LHC (14 TeV) are given. (12 refs).
Pion-nucleon vertex function with one nucleon off shell
International Nuclear Information System (INIS)
Mizutani, T.; Rochus, P.
1979-01-01
The pion-nucleon vertex function with an off-mass-shell nucleon is obtained through sideways dispersion relations with the P 11 and S 11 pion-nucleon phase shifts as only input. Contrary to the recent calculation of Nutt and Shakin, we find that the proper and improper vertex functions behave quite differently, indicating the importance of the nucleon propagator dressing. In particular the proper vertex function is found to have two poles in the unphysical region
A new form for the nucleon-nucleon potential
International Nuclear Information System (INIS)
Agarwal, B.K.
1976-01-01
The form of the internucleon force is considered. It is assumed that the nucleon-nucleon potential depends, in general, both on the distance ν and the angle theta. It is also assumed that the potential V(ν,ω) admits an analytic continuation into the complex ω-plane so that when ω=costheta is real it denotes the direction in which the potential is being determined. The analysis leads to a new parametryzation of the nucleon-nucleon potential
Evoli, Stefania; Mobley, David L.; Guzzi, Rita; Rizzuti, Bruno
2016-01-01
experiments, because of the structural adaptability of this protein in accommodating small ligands. In this work, we provide a set of predictions covering the geometry, affinity of binding and protonation state for the pharmaceutically most active form (S
Separable pole expansions in four-nucleon bound state calculations
International Nuclear Information System (INIS)
Sofianos, S.A.; Fiedeldey, H.; Haberzettl, H.; Sandhas, W.
1982-04-01
We compare the utility of the Generalized Unitary Pole Expansion (GUPE) and the Energy-Dependent Pole Expansion (EDPE) for the three-body subsystem amplitudes in four-body state calculations for a variety of separable and local nucleon-nucleon interactions. It is found that, with the EDPE, the four-body binding energy is well reproduced with only two terms each for the (2+2)- and the (3+1)-subsystem, respectively, while the GUPE requires three terms for the (3+1)-channel and four terms for the (2+2)-channel. We thus conclude that pole dominance is of greater importance for the GUPE than for EDPE, which works equally well for both types of subsystems. It is found that both methods, in particular the EDPE, converge more rapidly with increasing repulsion in the two-body interaction, i.e. the more realistic the interaction becomes. Both expansions require similar computing times for a converged calculation and are about 15-20 times faster than the widely used Hilbert-Schmidt Expansion (HSE). The respective merits of the two pole expansions are discussed and compared with the HSE. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Simula, S. [Instituto Nazionale di Fisica Nucleare, Roma (Italy)
1994-04-01
Semi-inclusive deep inelastic lepton scattering off nuclei is investigated assuming that virtual boson absorption occurs on a hadronic cluster which can be either a two-nucleon correlated pair or a six-quark bag. The differences in the energy distribution of nucleons produced in backward and forward directions are analyzed both at x<1 and x>1.
Pinnaduwage, Lal A.; Boiadjiev, Vassil I.; Hawk, John E.; Gehl, Anthony C.; Fernando, Gayanath W.; Rohana Wijewardhana, L. C.
2008-03-01
Surface stress induced by molecular adsorption in three different binding processes has been studied experimentally using a microcantilever sensor. A comprehensive free-energy analysis based on an energy conservation approach is proposed to explain the experimental observations. We show that when guest molecules bind to atoms/molecules on a microcantilever surface, the released binding energy is retained in the host surface, leading to a metastable state where the excess energy on the surface is manifested as an increase in surface stress leading to the bending of the microcantilever. The released binding energy appears to be almost exclusively channeled to the surface energy, and energy distribution to other channels, including heat, appears to be inactive for this micromechanical system. When this excess surface energy is released, the microcantilever relaxes back to the original state, and the relaxation time depends on the particular binding process involved. Such vapor phase experiments were conducted for three binding processes: physisorption, hydrogen bonding, and chemisorption. Binding energies for these three processes were also estimated.
Energy Technology Data Exchange (ETDEWEB)
Pinnaduwage, Lal A; Boiadjiev, Vassil I; Hawk, John E; Gehl, Anthony C [Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831-6122 (United States); Fernando, Gayanath W [Physics Department, University of Connecticut, Storrs, CT 06269 (United States); Wijewardhana, L C Rohana [Physics Department, University of Cincinnati, Cincinnati, OH 45221 (United States)
2008-03-12
Surface stress induced by molecular adsorption in three different binding processes has been studied experimentally using a microcantilever sensor. A comprehensive free-energy analysis based on an energy conservation approach is proposed to explain the experimental observations. We show that when guest molecules bind to atoms/molecules on a microcantilever surface, the released binding energy is retained in the host surface, leading to a metastable state where the excess energy on the surface is manifested as an increase in surface stress leading to the bending of the microcantilever. The released binding energy appears to be almost exclusively channeled to the surface energy, and energy distribution to other channels, including heat, appears to be inactive for this micromechanical system. When this excess surface energy is released, the microcantilever relaxes back to the original state, and the relaxation time depends on the particular binding process involved. Such vapor phase experiments were conducted for three binding processes: physisorption, hydrogen bonding, and chemisorption. Binding energies for these three processes were also estimated.
Diquark fragmentation functions in hadron-nucleon interactions at 19 GeV/c and other energies
International Nuclear Information System (INIS)
Bakken, V.; Breivik, F.O.; Jacobsen, T.
New data on pion production in pn-interactions at 19 GeV/c are used, together with earlier data on pion production in pn (π + n) at other energies, to determine the diquark fragmentation functions Dsup(π) +- sub(dd)(=Dsup(π) +- sub(uu)) and Dsup(π)sub(ud) in the neutron and proton fragmentation regions. Typical high energy data on pion production in pp-interactions are also considered. The unfavoured fragmentation function Dsup(π) + sub(dd)(x) is found to be much smaller than the favoured fragmentati ion function Dsup(π) - sub(dd)(x) and to have a steeper x-dependence. The diquark fragmentation functions agree very well with those from v(v - )- proton interactions as expected from quark parton models
ψ' and J/ψ suppression in high-energy nucleon-nucleus and nucleus-nucleus collisions
International Nuclear Information System (INIS)
Wong, Cheuk-Yin.
1995-01-01
The observed features of ψ' to J/ψ suppression in pA and nucleus-nucleus collisions can be explained in terms of a two-component absorption model. For the hard component of the absorption due to the interaction of the produced c bar c systems with baryons at high relative energies, the absorption cross sections are insensitive to the radii of the c bar c systems, as described by the Additive Quark Model. For the soft component due to the low energy c bar c interactions with soft particles produced by other baryon-baryon collisions, the absorption cross sections are greater for ψ' than for J/ψ, because the breakup threshold for ψ' is much smaller than for ψ
Parity violation in the nucleon-nucleon interaction
International Nuclear Information System (INIS)
Haxton, W.C.
1989-01-01
I discuss the present status of our understanding of parity nonconservation (PNC) in the nucleon-nucleon interaction, and some of the difficulties inherent in nuclear tests of PNC. I also discuss the nucleon/nuclear anapole moment, the parity violating coupling of the photon, and its relation to the PNC NN interaction. 13 refs., 1 fig., 2 tabs
International Nuclear Information System (INIS)
Tornow, W.; Howell, C.R.; Walter, R.L.; Slaus, I.
1992-01-01
Comparison of data for neutron-deuteron and proton-deuteron analyzing power A y for elastic scattering has become crucial for investigating charge-symmetry breaking in the 3 P nucleon-nucleon interactions. We extended this comparison down to 5 MeV and find that the relative difference between n-d and p-d scattering at the A y maximum near 120 degree increases with decreasing energy. By applying a straightforward Coulomb ''correction'' to the p-d data, we account for most of the difference, suggesting that the Coulomb force, rather than charge-symmetry breaking, is responsible for most of the observed difference
International Nuclear Information System (INIS)
Grange, P.; Mathiot, J.F.; Roy-Stephan, M.; Frascaria, R.; Gales, S.
1990-01-01
The topics presented at the 1989 Joliot-Curie Lectures are reported. Two main subjects were retained: a simplified description of the N-body motion of particles in the quasi-particle configuration; study of the dynamics of nuclear components which are not described by nucleons in their ground state. The following themes were presented: quasiparticles and the Green functions, relativistic aspects of the quasiparticle concept, the dimensions of nucleons in the nuclei and the EMC effect, quarks and gluons in the nuclei, the delta in the nuclei, the strangeness, quasiparticles far from the Fermi sea, diffusion of electrons, stellar evolution and nucleosynthesis [fr
International Nuclear Information System (INIS)
Virchaux, M.
1992-11-01
The present status of experimental measurements of the nucleon structure functions is reviewed. The results from nearly all deep inelastic experiments are in good mutual agreement. Principles of the analysis of these structure function data in the framework of QCD are described. The specific features of the perturbative QCD predictions are observed in the data. This provides quantitative tests of the validity of QCD as well as determinations of the various parton distributions in the nucleon and some of the most precise measurements of the strong coupling constant αs. The future of this field of experimental physics is sketched
Nucleon strangeness: present and future
Sapozhnikov, M G
2010-01-01
A review of experimental results for the measurement of the strange quark distributions in the nucleon, is given. Contributions of the strange quarks to the nucleon mass, electromagnetic form factors and spin, are discussed.
Energy Technology Data Exchange (ETDEWEB)
Kera, Satoshi, E-mail: kera@ims.ac.jp [Institute for Molecular Science, Myodaiji, Okazaki 444-8585 (Japan); Department of Nanomaterial Science, Graduate School of Advanced Integration Science, Chiba University, Inage-ku, Chiba 263-8522 (Japan); Ueno, Nobuo [Department of Nanomaterial Science, Graduate School of Advanced Integration Science, Chiba University, Inage-ku, Chiba 263-8522 (Japan)
2015-10-01
Understanding of electron-phonon coupling as well as intermolecular interaction is required to discuss the mobility of charge carrier in functional molecular solids. This article summarizes recent progress in direct measurements of valence hole-vibration coupling in ultrathin films of organic semiconductors by using ultraviolet photoelectron spectroscopy (UPS). The experimental study of hole-vibration coupling of the highest occupied molecular orbital (HOMO) state in ordered monolayer film by UPS is essential to comprehend hole-hopping transport and small-polaron related transport in organic semiconductors. Only careful measurements can attain the high-resolution spectra and provide key parameters in hole-transport dynamics, namely the charge reorganization energy and small polaron binding energy. Analyses methods of the UPS HOMO fine feature and resulting charge reorganization energy and small polaron binding energy are described for pentacene and perfluoropentacene films. Difference between thin-film and gas-phase results is discussed by using newly measured high-quality gas-phase spectra of pentacene. Methodology for achieving high-resolution UPS measurements for molecular films is also described.
International Nuclear Information System (INIS)
Chiba, Satoshi; Niita, Koji; Maruyama, Toshiki; Fukahori, Tokio; Takada, Hiroshi; Iwamoto, Akira
1995-01-01
The double-differential (p,xp') and (p,xn) reaction cross sections of 58 Ni and 90 Zr in the energy range from 120 to 200 MeV have been studied in terms of the Quantum Molecular Dynamics. It was found that the present calculation could give a quantitative explanation of experimentally observed values of both channels simultaneously without adjusting any parameter, showing the usefulness of the QMD approach to study the pre-equilibrium process in this energy region. Comparisons were also made with prediction of other theories such as Antisymmetrized Molecular Dynamics (AMD) and semiclassical distorted wave theory. Effect of the anti-symmetrization, which is in AMD but not in QMD, was found surprisingly small, being the result of QMD even slightly better. At the same time, it was found that the present calculation does not give the quasi-free peak of the 1-step cross sections similar to the semiclassical model, due probably to different treatment of the refraction and acceleration effects caused by the mean field. (author)
Interactions of 82Pb208 nuclei with energy 158 GeV per nucleon with photoemulsion nuclei
International Nuclear Information System (INIS)
Adamovich, M.I.; Andreeva, N.P.; Bubnov, V.I.; Gajtinov, A.Sh.; Kanygina, Eh.K.; Musaeva, A.K.; Sejtimbetov, A.M.; Skorobagatova, V.I.; Filippova, L.N.; Chasnikov, I.Ya.
1999-01-01
In this report there are experimental data on 82 Pb 208 nuclei (158 GeV) interaction with photoemulsion nuclei. The said data are compared to the similar ones for 79 Au 197 nuclei with less energy (10,7 A GeV). Stack of nuclear emulsion was irradiated with the beam of nuclei 82 Pb 208 at SPS of CERN. Events search was done along the primary nucleus trace. Pb nucleus average path length happened to be λ=(3,8±0,1) cm, this virtually coincides with the one calculated by Brandt and Peters formula (3,9 cm). Secondary particles were identified into s (storm), g (knock-on protons) and b- particles (target nucleus fragments), as well as into nucleus-bullet fragments with different charges (Z=1,2,≥3). This allowed obtaining event distribution by multiplicity of these particles (n s , n g , n b ) and fragments (n z=1,2,≥3 ), calculation of average values by multiplicity (see table), finding correlation of characteristics. >From the table it's clear that when the energy increases s > increases 2,5 times where as g > insignificantly decreases and b > doesn't change
Systematic of fusion incompleteness in 20Ne induced reactions at energy 4-7 MeV/nucleon
International Nuclear Information System (INIS)
Ali, Sabir; Ahmad, Tauseef; Kumar, Kamal
2016-01-01
In the present work, a study of fusion incompleteness using the 20 Ne projectile over 51 V, 55 Mn and 59 Co and targets has been carried out. The experiment involving 20 N e+ 51 V system was performed at VECC, Kolkata, India. The targets of thickness range 1.19-1.50 rug/cm 2 of spectroscopically pure 51 V (purity 99.99%) were prepared by depositing on aluminum backing of thickness range 1.47-1.64 mg/cm 2 by the vacuum evaporation technique at the target lab of VECC. A stack of six 51 V targets was irradiated for ≈ 11 hrs by 20 Ne 6+ beam at ≈145 MeV. The irradiation of the stack covered the desired energy range of 82-145 MeV. The beam current was ≈ 40 nA during the irradiation hours. The energy of the 20 Ne ion beam incident on each target foil was calculated using stopping power software SRIM. The overall error in the present work is estimated to be ≤20%
Ciofi degli Atti, Claudio; Mezzetti, Chiara Benedetta; Morita, Hiko
2017-04-01
Background: Two-nucleon (2 N ) short-range correlations (SRC) in nuclei have been recently thoroughly investigated, both theoretically and experimentally and the study of three-nucleon (3 N ) SRC, which could provide important information on short-range hadronic structure, is underway. Novel theoretical ideas concerning 2 N and 3 N SRC are put forward in the present paper. Purpose: The general features of a microscopic one-nucleon spectral function which includes the effects of both 2 N and 3 N SRC and its comparison with ab initio spectral functions of the three-nucleon systems are illustrated. Methods: A microscopic and parameter-free one-nucleon spectral function expressed in terms of a convolution integral involving ab initio relative and center-of-mass (c.m.) momentum distributions of a 2 N pair and aimed at describing two- and three-nucleon short-range correlations, is obtained by using: (i) the two-nucleon momentum distributions obtained within ab initio approaches based upon nucleon-nucleon interactions of the Argonne family; (ii) the exact relation between one- and two-nucleon momentum distributions; (iii) the fundamental property of factorization of the nuclear wave function at short internucleon ranges. Results: The comparison between the ab initio spectral function of 3He and the one based upon the convolution integral shows that when the latter contains only two-nucleon short-range correlations the removal energy location of the peaks and the region around them exhibited by the ab initio spectral function are correctly predicted, unlike the case of the high and low removal energy tails; the inclusion of the effects of three-nucleon correlations brings the convolution model spectral function in much better agreement with the ab initio one; it is also found that whereas the three-nucleon short-range correlations dominate the high energy removal energy tail of the spectral function, their effects on the one-nucleon momentum distribution are almost one
Binary projectile fragmentation of 12C at an incident energy of 33.3 MeV/nucleon
Förtsch, S V; Gadioli, E; Bassini, R; Buthelezi, E Z; Cerutti, F; Connell, S H; Cowley, A A; Fujita, H; Mabiala, J; Mairani, A; Mira, J; Papka, P; Neveling, R; Smit, F D
2010-01-01
Direct binary projectile fragmentation is being investigated for the case where a 400 MeV 12C projectile breaks up into an particle and a 8Be fragment in the interaction with a thin 93Nb and 197Au target. While the 8Be fragments were measured at 9 , the correlated particles were detected in an angular range between 16 and 30 on the opposite side of the beam. From the preliminary results presented here one may obtain information on the amount of quasi-elastic fragmentation (both fragments do not suffer any further interactions after they are produced). These experimental results indicate that the quasi-elastic break-up process is the dominant contribution to the measured correlation spectra. As was also observed in earlier work, the most forward quasi-elastically emitted particles have energies exceeding the beam velocity.
Non-Regge and hyper-Regge effects in pion-nucleon charge exchange scattering at high energies
International Nuclear Information System (INIS)
Joynson, D.; Leader, E.; Nicolescu, B.; Paris-6 Univ., 75; Lopez, C.
1975-04-01
The experimental data on the charge exchange differential cross-section and on the difference on the π + p and π - p total cross-sections between 5GeV/c to 200GeV/c are shown to be incompatible with conventional Regge asymptotic behavior. It is shown that an additional term is required which grows in importance with energy. The precise form of the new term cannot be ascertained, but it is shown that it corresponds to a singularity at J=1 in the complex angular momentum plane. Amongst the possible types of additional term there are two which have been closely analysed: a non-Regge behavior, a hyper-Regge term which have allowed very striking predictions in particular for the charge exchange polarisation [fr
Nucleon-induced reactions at intermediate energies: new data at 96 MeV and theoretical status
Energy Technology Data Exchange (ETDEWEB)
Blideanu, V.; Lecolley, F.R.; Lecolley, J.F.; Lefort, T.; Marie, N.; Ban, G.; Louvel, M. [Caen Univ., Lab. de Physique Corpusculaire, ENSICAEN, IN2P3-CNRS ISMRA, 14 (France); Atac, A.; Bergenwall, B.; Blomgren, J.; Dangtip, S.; Hildebrand, A.; Hohansson, C.; Klug, J.; Nilsson, L.; Ollson, N.; Pomp, S.; Tippawan, U.; Osterlund, M. [Uppsala Univ., Nykoeping (Sweden). Dept. of Neutron Research; Tippawan, U. [Chiang Mai University, Fast Neutron Research Facility (Thailand); Elmgren, K.; Olsson, N. [Swedish Defense Research Agency, Stokholm (Sweden); Eudes, Ph.; Guertin, A.; Haddad, F.; Kirchner, T.; Lebrun, C.; Riviere, G. [Nantes Univ., Subatech, 44 (France); Foucher, Y. [CEA Saclay, Dept. d' Astrophysique, de Physique des Particules de Physique Nucleaire et de l' Instrumentation Associee, 91- Gif sur Yvette (France); Jonsson, O.; Prokofiev, A.V.; Renberg, P.U. [Uppsala Univ., Svedberg Laboratory (Sweden); Kerveno, M.; Stuttge, L. [IReS, Strasbourg (France); Le Brun, Ch. [Laboratoire de Physique Subatomique et de Cosmologie, 38 - Grenoble (France); Nadel-Turonski, P. [Uppsala Univ. (Sweden). Dept. of Radiation Sciences; Slypen, I. [Universite Catholique de Louvain (UCL), Institut de Physique Nucleaire, Louvain-la-Neuve (Belgium)
2004-04-01
Double-differential cross sections for light charged particle production (up to A = 4) were measured in 96 MeV neutron-induced reactions, at TSL laboratory cyclotron in Uppsala (Sweden). Measurements for three targets, Fe, Pb, and U, were performed using two independent devices, SCANDAL and MEDLEY. The data were recorded with low energy thresholds and for a wide annular range (20 - 160 degrees). The normalization procedure used to extract the cross sections is based on the np elastic scattering reaction that we measured and for which we present experimental results. A good control of the systematic uncertainties affecting the results is achieved. Calculations using the exciton model are reported. Two different theoretical approaches proposed to improve its predictive power regarding the complex particle emission are tested. The capabilities of each approach is illustrated by comparison with the 96 MeV data that we measured, and with other experimental results available in the literature. (authors)
Impact of nucleon mass shift on the freeze-out process
International Nuclear Information System (INIS)
Zschocke, Sven; Csernai, Laszlo Pal; Molnar, Etele; Nyiri, Agnes; Manninen, Jaakko
2005-01-01
The freeze-out of a massive nucleon gas through a finite layer with a timelike normal is studied. The impact of the in-medium nucleon mass shift on the freeze-out process is investigated. A considerable modification of the thermodynamic variables of temperature, flow velocity, energy density, and particle density has been found. Because of the nucleon mass shift the freeze-out particle distribution functions are changed noticeably in comparison with the evaluations, which use the vacuum nucleon mass
Atom-solid binding energy shifts for K 2p and Rb 3d sublevels
International Nuclear Information System (INIS)
Holappa, M.; Aksela, S.; Patanen, M.; Urpelainen, S.; Aksela, H.
2011-01-01
Highlights: → Binding energy shifts between atom and solid. K 2p and Rb 3d sublevels were studied. → Simultaneous measurements give accurate results. → Results can be used as a reference for cluster studies. - Abstract: Binding energy shifts between free and solid state atoms for K 2p and Rb 3d photolines have been determined by measuring the vapor and solid state spectra simultaneously in similar experimental conditions applying synchrotron radiation excited photoelectron spectroscopy. This method has the important benefit that the work function is not needed to correct for different reference energy levels, therefore much more accurate values for binding energy shifts are obtained.
Effective lagrangian for Kaon-nucleon scattering
International Nuclear Information System (INIS)
Andrade, S.C.B. de; Ferreira, E.M.
1980-11-01
A model for the Kaon-nucleon interaction is investigated, based on a lagrangian which includes the Yukawa interactions of hyperons, kaons and nucleons plus contact terms representing short range interactions in each isospin state. All diagrams up to fourth order are evaluated and the partial wave S matrix elements are unitarized through diagonal Pade approximants. The results of the calculations with this model give a good description of all experimental data on both I = O and I = 1 states of the KN system at low and intermediate energies. (Author) [pt
Effect of binding in cyclic phosphorylation-dephosphorylation process and in energy transformation.
Sarkar, A; Beard, D A; Franza, B R
2006-07-01
The effects of binding on the phosphorylation-dephosphorylation cycle (PDPC) - one of the key components of the signal transduction processes - is analyzed based on a mathematical model. The model shows that binding of proteins, forming a complex, diminishes the ultrasensitivity of the PDPC to the differences in activity between kinase and phosphatase in the cycle. It is also found that signal amplification depends upon the strength of the binding affinity of the protein (phosphorylated or dephosphorylated) to other proteins . It is also observed that the amplification of signal is not only dependent on phosphorylation potential but also on binding properties and resulting adjustments in binding energies.
International Nuclear Information System (INIS)
Niu, Y.; Paar, N.; Vretenar, D.; Meng, J.
2009-01-01
The fully self-consistent relativistic random-phase approximation (RRPA) framework based on effective interactions with a phenomenological density dependence is extended to finite temperatures. The RRPA configuration space is built from the spectrum of single-nucleon states at finite temperature obtained by the temperature dependent relativistic mean field (RMF-T) theory based on effective Lagrangian with density dependent meson-nucleon vertex functions. As an illustration, the dependence of binding energy, radius, entropy and single particle levels on temperature for spherical nucleus 2 08P b is investigated in RMF-T theory. The finite temperature RRPA has been employed in studies of giant monopole and dipole resonances, and the evolution of resonance properties has been studied as a function of temperature. In addition, exotic modes of excitation have been systematically explored at finite temperatures, with an emphasis on the case of pygmy dipole resonances.(author)
International Nuclear Information System (INIS)
Windmolders, R.
1989-01-01
In this paper the following topics are reviewed: 1. the structure functions measured in deep inelastic e-N, μ-N and ν-N scattering; 2. nuclear effects on the structure functions; 3. nuclear effects on the fragmentation functions; 4. the spin dependent structure functions and their interpretation in terms of nucleon constituents. (orig./HSI)
Nowak, M A; Zahed, I
1989-01-01
The issue of the strangeness content of the proton in relation to a large σ π N term is examined using the instanton-antiinstanton description of the QCD ground state. Modulo plausible assumptions, our results indicate no strangeness admixture in the nucleon state at zero momentum transfer.
International Nuclear Information System (INIS)
Anon.
1978-01-01
The design and operation of a nucleonic weighing machine fabricated for continuous weighing of material over conveyor belt are described. The machine uses a 40 mCi cesium-137 line source and a 10 litre capacity ionization chamber. It is easy to maintain as there are no moving parts. It can also be easily removed and reinstalled. (M.G.B.)
Charge and energy dependence of the residence time of cosmic ray nuclei below 15 GeV/nucleon
International Nuclear Information System (INIS)
Soutoul, A.; Engelmann, J.J.; Ferrando, P.; Koch-Miramond, L.; Masse, P.; Webber, W.R.
1985-01-01
The relative abundance of nuclear species measured in cosmic rays at Earth has often been interpreted with the simple leaky box model. For this model to be consistent an essential requirement is that the escape length does not depend on the nuclear species. The discrepancy between escape length values derived from iron secondaries and from the B/C ratio was identified by Garcia-Munoz and his co-workers using a large amount of experimental data. Ormes and Protheroe found a similar trend in the HEAO data although they questioned its significance against uncertainties. They also showed that the change in the B/C ratio values implies a decrease of the residence time of cosmic rays at low energies in conflict with the diffusive convective picture. These conclusions crucially depend on the partial cross section values and their uncertainties. Recently new accurate cross sections of key importance for propagation calculations have been measured. Their statistical uncertainties are often better than 4% and their values significantly different from those previously accepted. Here, these new cross sections are used to compare the observed B/C+O and (Sc to Cr)/Fe ratio to those predicted with the simple leaky box model
International Nuclear Information System (INIS)
Krebs, H.; Epelbaum, E.; Meissner, U.G.
2007-01-01
We study the two-nucleon force at next-to-next-to-leading order in a chiral effective field theory with explicit Δ degrees of freedom. Fixing the appearing low-energy constants from a next-to-leading-order calculation of pion-nucleon threshold parameters, we find an improved convergence of most peripheral nucleon-nucleon phases compared to the theory with pions and nucleons only. In the delta-full theory, the next-to-leading-order corrections are dominant in most partial waves considered. (orig.)
Mey, Antonia S. J. S.; Jiménez, Jordi Juárez; Michel, Julien
2018-01-01
The Drug Design Data Resource (D3R) consortium organises blinded challenges to address the latest advances in computational methods for ligand pose prediction, affinity ranking, and free energy calculations. Within the context of the second D3R Grand Challenge several blinded binding free energies predictions were made for two congeneric series of Farsenoid X Receptor (FXR) inhibitors with a semi-automated alchemical free energy calculation workflow featuring FESetup and SOMD software tools. Reasonable performance was observed in retrospective analyses of literature datasets. Nevertheless, blinded predictions on the full D3R datasets were poor due to difficulties encountered with the ranking of compounds that vary in their net-charge. Performance increased for predictions that were restricted to subsets of compounds carrying the same net-charge. Disclosure of X-ray crystallography derived binding modes maintained or improved the correlation with experiment in a subsequent rounds of predictions. The best performing protocols on D3R set1 and set2 were comparable or superior to predictions made on the basis of analysis of literature structure activity relationships (SAR)s only, and comparable or slightly inferior, to the best submissions from other groups.
Nucleon-nucleon correlations in dense nuclear matter
International Nuclear Information System (INIS)
Alm, T.
1993-02-01
In this thesis new results on the problematics of the formation of nucleon-nucleon correlations in nuclear matter could be presented. Starting from a general study of the two-particle problem in matter we studied the occurrence of a suprafluid phase (pair condensate of nucleons). The Gorkov decoupling by means of anomalous Green functions was generalized, so that also Cooper pairs with spin 1 (triplet pairing) can be described. A generalized gap equation resulted, which permits to determine the order parameters of the suprafluied phase in arbitrary channels of the nucleon-nucleon scattering states. This equation was solvd in the 1 S 0 -, in the 3 P 2 - 3 F 2 , and in the 3 S 1 - 3 D 1 channel under application of realistic nucleon-nucleon potentials. The behaviour of the resulting gap parameters in the single channels was studied as function of density and temperature. (orig.) [de
Analysis of Three-Nucleon Forces Effects in the A = 3 System
International Nuclear Information System (INIS)
Kievsky, A.
2011-01-01
Using modern nucleon-nucleon interactions in the description of the A = 3, 4 nuclear systems the χ 2 per datum results to be much bigger than one. In particular it is not possible to reproduce the three- and four-nucleon binding energies and the n .d scattering length simultaneously. This is one manifestation of the necessity of including a three-nucleon force in the nuclear Hamiltonian. In this paper we perform an analysis of some, widely used, three-nucleon force models.We analyze their capability to describe the aforementioned quantities and, to improve their description, we propose modifications in the parametrization of the models. The effects of these new parametrizations are studied in some polarization observables at low energies. Due to the fact that some of the widely used TNF models do not reproduce simultaneously the triton and 4 He binding energies and the n -d doublet scattering length, possible modifications of their parametrizations have been analyzed. To this end we have used the AV18 as the reference NN interaction and we have analyze possible modifications of the URIX model. We have modified the regularization of the profile functions Y (r ) and T (r ) at the origin and we have introduced the Z 0 (r ) function in the central repulsive E-term. We have used one-parameter functions that have been chosen to match the short-range behavior of the corresponding functions in the N2LOL model. Furthermore the strengths of the b-, d-terms and E-terms have been fixed to reproduce the triton binding energy and 2 a nd . Then the predictions for some selected scattering observables in p - d scattering at 3 MeV have been compared to the results of the original model and the experimental data. We can observe that the description using the new parametrizations has the same quality of the original model. However, with the proposed parametrizations, the AV18+URIX model describes correctly B( 3 H) and 2 a nd . This analysis can be consider as a preliminary step in a
Hard probes of short-range nucleon-nucleon correlations
Energy Technology Data Exchange (ETDEWEB)
J. Arrington, D. W. Higinbotham, G. Rosner, M. Sargsian
2012-10-01
The strong interaction of nucleons at short distances leads to a high-momentum component to the nuclear wave function, associated with short-range correlations between nucleons. These short-range, high-momentum structures in nuclei are one of the least well understood aspects of nuclear matter, relating to strength outside of the typical mean-field approaches to calculating the structure of nuclei. While it is difficult to study these short-range components, significant progress has been made over the last decade in determining how to cleanly isolate short-range correlations in nuclei. We have moved from asking if such structures exist, to mapping out their strength in nuclei and studying their microscopic structure. A combination of several different measurements, made possible by high-luminosity and high-energy accelerators, coupled with an improved understanding of the reaction mechanism issues involved in studying these structures, has led to significant progress, and provided significant new information on the nature of these small, highly-excited structures in nuclei. We review the general issues related to short-range correlations, survey recent experiments aimed at probing these short-range structures, and lay out future possibilities to further these studies.
Counter terms for low momentum nucleon-nucleon interactions
International Nuclear Information System (INIS)
Holt, Jason D.; Kuo, T.T.S.; Brown, G.E.; Bogner, Scott K.
2004-01-01
There is much current interest in treating low energy nuclear physics using the renormalization group (RG) and effective field theory (EFT). Inspired by this RG-EFT approach, we study a low-momentum nucleon-nucleon (NN) interaction, V low-k , obtained by integrating out the fast modes down to the scale Λ∼2 fm -1 . Since NN experiments can only determine the effective interaction in this low momentum region, our chief purpose is to find such an interaction for complex nuclei whose typical momenta lie below this scale. In this paper we find that V low-k can be highly satisfactorily accounted for by the counter terms corresponding to a short range effective interaction. The coefficients C n of the power series expansion ΣC n q n for the counter terms have been accurately determined, and results derived from several meson-exchange NN interaction models are compared. The counter terms are found to be important only for the S, P and D partial waves. Scaling behavior of the counter terms is studied. Finally we discuss the use of these methods for computing shell model matrix elements
Model of homogeneous nucleus. Total and inelastic cross sections of nucleon-nucleus scattering
International Nuclear Information System (INIS)
Ponomarev, L.A.; Smorodinskaya, N.Ya.
1985-01-01
It is shown that the nucleon-nuckleus scattering amplitude at high energy can be easily calculated by generalization of the nucleon-nucleon scattering amplitude and satisfies a simple factorization relation. As distinct from the Glauber model, the suggested approach makes no use of the nucleonic structure of the nucleus and the hadron-nucleus scattering amplitude is not expressed in terms of hadron-nucleon scattering amplitudes. The energy dependence of total and inelastic cross sections is successfully described for a number of nuclei
Comparative study of three-nucleon potentials in nuclear matter
Lovato, Alessandro; Benhar, Omar; Fantoni, Stefano; Schmidt, Kevin E.
2012-02-01
A new generation of local three-body potentials providing an excellent description of the properties of light nuclei, as well as of the neutron-deuteron doublet scattering length, has been recently derived. We have performed a comparative analysis of the equations of state of both pure neutron matter (PNM) and symmetric nuclear matter (SNM) at zero temperature obtained using these models of three-nucleon forces. In particular, we have carried out both variational and auxiliary field diffusion Monte Carlo calculations of the equation of state of PNM, while in the case of SNM we have only the variational approach has been considered. None of the considered potentials simultaneously explains the empirical equilibrium density and binding energy of symmetric nuclear matter. However, two of them provide reasonable values of the saturation density. The ambiguity concerning the treatment of the contact term of the chiral inspired potentials is discussed.
Dolenc, Jožica; Oostenbrink, Chris; Koller, Jože; van Gunsteren, Wilfred F.
2005-01-01
Molecular dynamics simulations have been performed on netropsin in two different charge states and on distamycin binding to the minor groove of the DNA duplex d(CGCGAAAAACGCG)·d(CGCGTTTTTCGCG). The relative free energy of binding of the two non-covalently interacting ligands was calculated using the thermodynamic integration method and reflects the experimental result. From 2 ns simulations of the ligands free in solution and when bound to DNA, the mobility and the hydrogen-bonding patterns of the ligands were studied, as well as their hydration. It is shown that even though distamycin is less hydrated than netropsin, the loss of ligand–solvent interactions is very similar for both ligands. The relative mobilities of the ligands in their bound and free forms indicate a larger entropic penalty for distamycin when binding to the minor groove compared with netropsin, partially explaining the lower binding affinity of the distamycin molecule. The detailed structural and energetic insights obtained from the molecular dynamics simulations allow for a better understanding of the factors determining ligand–DNA binding. PMID:15687382
Dolenc, Jozica; Oostenbrink, Chris; Koller, Joze; van Gunsteren, Wilfred F
2005-01-01
Molecular dynamics simulations have been performed on netropsin in two different charge states and on distamycin binding to the minor groove of the DNA duplex d(CGCGAAAAACGCG).d(CGCGTTTTTCGCG). The relative free energy of binding of the two non-covalently interacting ligands was calculated using the thermodynamic integration method and reflects the experimental result. From 2 ns simulations of the ligands free in solution and when bound to DNA, the mobility and the hydrogen-bonding patterns of the ligands were studied, as well as their hydration. It is shown that even though distamycin is less hydrated than netropsin, the loss of ligand-solvent interactions is very similar for both ligands. The relative mobilities of the ligands in their bound and free forms indicate a larger entropic penalty for distamycin when binding to the minor groove compared with netropsin, partially explaining the lower binding affinity of the distamycin molecule. The detailed structural and energetic insights obtained from the molecular dynamics simulations allow for a better understanding of the factors determining ligand-DNA binding.
One-boson-exchange approach to dilepton production in nucleon-nucleon collisions
International Nuclear Information System (INIS)
Haglin, K.L.
1991-01-01
The author calculates energy-dependent nucleon-nucleon elastic cross sections and electron-positron pair production differential cross sections for the processes pp → pp, np → np, and pp → ppe + e - , np → npe + e - at laboratory kinetic energies in the 1-5 GeV range. These calculations will be based on a one-boson-exchange (π, ρ, ω, σ, δ, η) approximation to the nucleon-nucleon scattering problem. Strong form factors are included in a manner which preserves gauge invariance. He finds excellent results as compared with data for the total elastic cross sections. The calculate differential elastic cross sections show only qualitative agreement with data. For dilepton production in n-p scattering the model overestimates the number of pairs as compared with proton on beryllium data. For the p-p case he finds the tensor coupling of the ρ to the nucleons to be clearly dominant. Data do not yet exist for the p-p case at these energies: the author predicts them
Proceedings of the workshop on two-nucleon system
International Nuclear Information System (INIS)
Kawaguchi, Masaaki; Namiki, Mikio; Fukawa, Mineo; Masaike, Akira
1980-08-01
The workshop on two nucleon system started its works four years ago to promote the experiment project on nucleon-nucleon system in the National Laboratory for High Energy Physics by the close cooperation of experimenters and theorists. In particular, several proposals have been made about the experiments using the polarized targets of hydrogen and deuterium, the spectrometers of large solid angle and others, and the investigation into them have been forwarded. It was decided to publish the results of the fourth meeting held in the National Laboratory for High Energy Physics on October 19 and 20, 1979, as the interim report, summarizing the contents. Some of the initial objectives have not been realized yet, but the data have been produced gradually from the experiments in the National Laboratory for High Energy Physics, and are contributing to various analyses. This report is composed of the physics of nucleon-nucleon systems and anti-nucleon-nucleon systems, the results of experiments and the projects corresponding to them, and the hypothetic round-table talk on the points which this workshop considers as problematic and the views of outside researchers on the National Laboratory for High Energy Physics. Finally, the materials distributed at the time of the meeting are added for reference as the appendix. Some numerical values are mutually different, but adjustment was not made. (Kako, I.)
Modeling a nucleon system: static and dynamical properties - density fluctuations
International Nuclear Information System (INIS)
Idier, D.
1997-01-01
This thesis sets forth a quasi-particle model for the static and dynamical properties of nuclear matter. This model is based on a scale ratio of quasi-particle to nucleons and the projection of the semi-classical distribution on a coherent Gaussian state basis. The first chapter is dealing with the transport equations, particularly with the Vlasov equation for Wigner distribution function. The second one is devoted to the statics of nuclear matter. Here, the sampling effect upon the nuclear density is treated and the state equation of the Gaussian fluid is compared with that given by Hartree-Fock approximation. We define state equation as the relationship between the nucleon binding energy and density, for a given temperature. The curvature around the state equation minimum of the quasi-particle system is shown to be related to the speed of propagation of density perturbation. The volume energy and the surface properties of a (semi-)infinite nucleon system are derived. For the resultant saturated auto-coherent semi-infinite system of quasi-particles the surface coefficient appearing in the mass formula is extracted as well as the system density profile. The third chapter treats the dynamics of the two-particle residual interactions. The effect of different parameters on relaxation of a nucleon system without a mean field is studied by means of a Eulerian and Lagrangian modeling. The fourth chapter treats the volume instabilities (spinodal decomposition) in nuclear matter. The quasi-particle systems, initially prepared in the spinodal region of the utilized interaction, are set to evolve. It is shown then that the scale ratio acts upon the amount of fluctuations injected in the system. The inhomogeneity degree and a proper time are defined and the role of collisions in the spinodal decomposition as well as that of the initial temperature and density, are investigated. Assuming different effective macroscopic interactions, the influence of quantities as
Exciton binding energy in GaAsBiN spherical quantum dot heterostructures
Das, Subhasis; Dhar, S.
2017-03-01
The ground state exciton binding energies (EBE) of heavy hole excitons in GaAs1-x-yBixNy - GaAs spherical quantum dots (QD) are calculated using a variational approach under 1s hydrogenic wavefunctions within the framework of effective mass approximation. Both the nitrogen and the bismuth content in the material are found to affect the binding energy, in particular for larger nitrogen content and lower dot radii. Calculations also show that the ground state exciton binding energies of heavy holes increase more at smaller dot sizes as compared to that for the light hole excitons.
Pauli blocking and medium effects in nucleon knockout reactions
International Nuclear Information System (INIS)
Bertulani, C. A.; De Conti, C.
2010-01-01
We study medium modifications of the nucleon-nucleon (NN) cross sections and their influence on the nucleon knockout reactions. Using the eikonal approximation, we compare the results obtained with free NN cross sections with those obtained with a purely geometrical treatment of Pauli blocking and with NN obtained with more elaborated Dirac-Bruecker methods. The medium effects are parametrized in terms of the baryon density. We focus on symmetric nuclear matter, although the geometrical Pauli blocking also allows for the treatment of asymmetric nuclear matter. It is shown that medium effects can change the nucleon knockout cross sections and momentum distributions up to 10% in the energy range E lab =50-300 MeV/nucleon. The effect is more evident in reactions involving halo nuclei.
Description of a nucleon in nuclear matter
International Nuclear Information System (INIS)
Bunatian, G.G.
1992-01-01
The nonlinear cloudy bag model, CBM, is generalized to describe a nucleon in nuclear matter at various densities ρ and temperatures T. The influence of the nuclear medium on the bag-nucleon in the framework of CBM is due to the modification of the equation describing the CBM pion field π. These changes are accounted for in the CBM by including in the CBM lagrangian the pion polarization operator π(ρ,T). The free pion propagator D is replaced in a nuclear medium by D(ρ,T). The changing of the pion field π and propagator D leads via the CBM equations to the modification of the bag size R and quark momentum p, determined simultaneously from these equations, and then to modifications of other bag-nucleon characteristics: the total energy E, r.m.s. radii, magnetic moment μ, polarizability α and so on, which all are expressed as the expectation values of the corresponding operators in the bag-nucleon state. The quantity π(ρ,T) was studied in the works whose results are used in this investigation. The nucleon size R in the nuclear matter at normal density ρ o and zero temperature decreases by 5% and the quarks momentum p also decreases, however, insignificantly, by 1-2%. On the other hand, the values of the r.m.s. radii increases by 15% for a proton and by 100% for a neutron. The author has also found that the polarizability of a nucleon in nuclear matter is roughly two times as much as in free space
Energy Technology Data Exchange (ETDEWEB)
Price, C E; Shepard, J R [Colorado Univ., Boulder (USA). Dept. of Physics
1991-04-18
We compute properties of the nucleon in a hybrid chiral model based on the linear {sigma}-model with quark degrees of freedom treated explicity. In contrast to previous calculations, we do not use the hedgehog ansatz. Instead we solve self-consistently for a state with well defined spin and isospin projections. We allow this state to be deformed and find that, although d- and g-state admixtures in the predominantly s-state single quark wave functions are not large, they have profound effects on many nucleon properties including magnetic moments and g{sub A}. Our best fit parameters provide excellent agreement with experiment but are much different from those determined in hedgehog calculations. (orig.).
Binding free energy analysis of protein-protein docking model structures by evERdock.
Takemura, Kazuhiro; Matubayasi, Nobuyuki; Kitao, Akio
2018-03-14
To aid the evaluation of protein-protein complex model structures generated by protein docking prediction (decoys), we previously developed a method to calculate the binding free energies for complexes. The method combines a short (2 ns) all-atom molecular dynamics simulation with explicit solvent and solution theory in the energy representation (ER). We showed that this method successfully selected structures similar to the native complex structure (near-native decoys) as the lowest binding free energy structures. In our current work, we applied this method (evERdock) to 100 or 300 model structures of four protein-protein complexes. The crystal structures and the near-native decoys showed the lowest binding free energy of all the examined structures, indicating that evERdock can successfully evaluate decoys. Several decoys that show low interface root-mean-square distance but relatively high binding free energy were also identified. Analysis of the fraction of native contacts, hydrogen bonds, and salt bridges at the protein-protein interface indicated that these decoys were insufficiently optimized at the interface. After optimizing the interactions around the interface by including interfacial water molecules, the binding free energies of these decoys were improved. We also investigated the effect of solute entropy on binding free energy and found that consideration of the entropy term does not necessarily improve the evaluations of decoys using the normal model analysis for entropy calculation.
The multidimensional nucleon structure
Directory of Open Access Journals (Sweden)
Pasquini Barbara
2016-01-01
Full Text Available We discuss different kinds of parton distributions, which allow one to obtain a multidimensional picture of the internal structure of the nucleon. We use the concept of generalized transverse momentum dependent parton distributions and Wigner distributions, which combine the features of transverse-momentum dependent parton distributions and generalized parton distributions. We show examples of these functions within a phenomenological quark model, with focus on the role of the spin-spin and spin-orbit correlations of quarks.
International Nuclear Information System (INIS)
1989-01-01
The main goal of the CERN heavy-ion experiments is the search for an indication that the predicted state of deconfined quarks and gluons, the quark-gluon plasma (QGP), has been produced. The quantity most crucial to the probability of QGP formation is the thermalized energy density attained during the heavy-ion reaction. The amount of energy radiated transverse to the beam direction is the experimental quantity which is believed to be a measure of the amount of energy deposition in the reaction, and hence to reflect the energy density attained. In this presentation we consider the systematics of transverse energy production at CERN SPS energies, and we use the results to make estimates, under various assumptions, of attained energy densities
International Nuclear Information System (INIS)
Teller, S.
1977-01-01
Nucleonic weighing systems utilize the principle of the absorption or the scattering of nuclear radiation for a contactless measurement of the weight of material per unit length, the loading, of a conveyor. The load signal is processed in an electronic unit with a tachometer signal for the conveyor velocity to indicate the flow rate and the integrated flow of material. The different sources of error in nucleonic weighing using transmitted and forward scattered radiation are discussed, and the design of two nucleonic weighing systems is described. One is a conventional transmission gauge particularly suited for measuring rapid variation in belt loading due to a fast detection and linearizing unit. The other system consists of a forward scattering gauge, particularly suitable for measuring light inhomogeneous materials due to the linear relationship between the weight per unit area and the gauge response. Results from on-line trials with different materials are presented, and experiences from more than one year of operation for a batch weighing system for quick lime and a continuous weighing system for mineral wool are reported. (author)
Effect of magnetic field on the impurity binding energy of the excited ...
Indian Academy of Sciences (India)
The effect of external magnetic field on the excited state energies in a spherical quantum dot was studied. The impurity energy and binding energy were calculated using the variational method within the effective mass approximation and finite barrier potential. The results showed that by increasing the magnetic field, the ...
Effect of magnetic field on the impurity binding energy of the excited ...
Indian Academy of Sciences (India)
Abstract. The effect of external magnetic field on the excited state energies in a spher- ical quantum dot was studied. The impurity energy and binding energy were calculated using the variational method within the effective mass approximation and finite barrier potential. The results showed that by increasing the magnetic ...
Parity violation in two-nucleon systems
Energy Technology Data Exchange (ETDEWEB)
Liu, C.-P., E-mail: cpliu@mail.ndhu.edu.tw [National Dong Hwa University, Department of Physics (China)
2013-03-15
Nuclear few-body systems become attractive avenues for the study of low-energy parity violation because experiments start to meet the precision requirements and theoretical calculations can be performed reliably. In this talk, an attempt of parametrizing low-energy parity-violating observables by the Danilov parameters will be introduced. Analyses of two-nucleon observables, based on the modern phenomenological potentials or the one of effective field theory, will be discussed.
Quenching of weak interactions in nucleon matter
International Nuclear Information System (INIS)
Cowell, S.; Pandharipande, V.R.
2003-01-01
We have calculated the one-body Fermi and Gamow-Teller charge-current and vector and axial-vector neutral-current nuclear matrix elements in nucleon matter at densities of 0.08, 0.16, and 0.24 fm -3 and proton fractions ranging from 0.2 to 0.5. The correlated states for nucleon matter are obtained by operating on Fermi-gas states by a symmetrized product of pair correlation operators determined from variational calculations with the Argonne-v18 and Urbana-IX two- and three-nucleon interactions. The squares of the charge- current matrix elements are found to be quenched by 20-25 % by the short-range correlations in nucleon matter. Most of the quenching is due to spin-isospin correlations induced by the pion exchange interactions which change the isospins and spins of the nucleons. A large part of it can be related to the probability for a spin-up proton quasiparticle to be a bare spin-up/down proton/neutron. Within the interval considered, the charge-current matrix elements do not have significant dependence on the matter density, proton fraction, and magnitudes of nucleon momenta; however, they do depend on momentum transfer. The neutral-current matrix elements have a significant dependence on the proton fraction. We also calculate the matrix elements of the nuclear Hamiltonian in the same correlated basis. These provide relatively mild effective interactions that give the variational energies in the Hartree-Fock approximation. The calculated two-nucleon effective interaction describes the spin-isospin susceptibilities of nuclear and neutron matter fairly accurately. However terms greater than or equal to three-body terms are necessary to reproduce the compressibility. Realistic calculations of weak interaction rates in nucleon matter can presumably be carried out using the effective operators and interactions studied here. All presented results use the simple two-body cluster approximation to calculate the correlated basis matrix elements. This allows for a clear
Quark bags, P-matrix and nucleon-nucleon scattering
International Nuclear Information System (INIS)
Narodetskij, I.M.
1984-01-01
This paper is an extended version of the talk given at IX European Conference on Few Body Problems in Physics, Tbilisi, 1984. It reviews recent developments of the quark compound bag (QCB) model including explicit examples of the QCB nucleon-nucleon potentials, description of the deuteron properties, calculation of the six quark admixture in the deuteron and applications to the three-nucleon system
Nucleon quark structure and strong meson-nucleon form factors
International Nuclear Information System (INIS)
Efimov, G.V.; Ivanov, M.A.
1987-01-01
The nucleon is considered as a three-quark system in virton-quark model. The main statistic properties of proton and neutron are calculated: magnetic moments, electromagnetic radii, G A /G V ratio in weak neutron decay. Strong meson-nucleon form factors which determine nucleon-nucleon potential are obtained as a function of squared transfer momentum of mesons. The results are compared with phenomenological form factors used for description of phases of NN-scattering in the one-boson-, exchange model
SAAMBE: Webserver to Predict the Charge of Binding Free Energy Caused by Amino Acids Mutations.
Petukh, Marharyta; Dai, Luogeng; Alexov, Emil
2016-04-12
Predicting the effect of amino acid substitutions on protein-protein affinity (typically evaluated via the change of protein binding free energy) is important for both understanding the disease-causing mechanism of missense mutations and guiding protein engineering. In addition, researchers are also interested in understanding which energy components are mostly affected by the mutation and how the mutation affects the overall structure of the corresponding protein. Here we report a webserver, the Single Amino Acid Mutation based change in Binding free Energy (SAAMBE) webserver, which addresses the demand for tools for predicting the change of protein binding free energy. SAAMBE is an easy to use webserver, which only requires that a coordinate file be inputted and the user is provided with various, but easy to navigate, options. The user specifies the mutation position, wild type residue and type of mutation to be made. The server predicts the binding free energy change, the changes of the corresponding energy components and provides the energy minimized 3D structure of the wild type and mutant proteins for download. The SAAMBE protocol performance was tested by benchmarking the predictions against over 1300 experimentally determined changes of binding free energy and a Pearson correlation coefficient of 0.62 was obtained. How the predictions can be used for discriminating disease-causing from harmless mutations is discussed. The webserver can be accessed via http://compbio.clemson.edu/saambe_webserver/.
Ion Binding Energies Determining Functional Transport of ClC Proteins
Yu, Tao; Guo, Xu; Zou, Xian-Wu; Sang, Jian-Ping
2014-06-01
The ClC-type proteins, a large family of chloride transport proteins ubiquitously expressed in biological organisms, have been extensively studied for decades. Biological function of ClC proteins can be reflected by analyzing the binding situation of Cl- ions. We investigate ion binding properties of ClC-ec1 protein with the atomic molecular dynamics simulation approach. The calculated electrostatic binding energy results indicate that Cl- at the central binding site Scen has more binding stability than the internal binding site Sint. Quantitative comparison between the latest experimental heat release data isothermal titration calorimetry (ITC) and our calculated results demonstrates that chloride ions prefer to bind at Scen than Sint in the wild-type ClC-ec1 structure and prefer to bind at Sext and Scen than Sint in mutant E148A/E148Q structures. Even though the chloride ions make less contribution to heat release when binding to Sint and are relatively unstable in the Cl- pathway, they are still part contributors for the Cl- functional transport. This work provides a guide rule to estimate the importance of Cl- at the binding sites and how chloride ions have influences on the function of ClC proteins.
International Nuclear Information System (INIS)
Galoyan, A.S.; Kladnitskaya, E.N.; Rogachevskij, O.V.; Uzhinskij, V.V.
2001-01-01
Experimental data on proton and π - -meson rapidity distributions in CC-interactions at 3.36 GeV/nucleon in the events with different multiplicities of produced π - -mesons are presented. The data are compared with predictions of RQMD and FRITIOF models. It is shown that the RQMD model reproduces satisfactorily the π - -meson distributions, but unsatisfactorily describes the protons characteristics. The FRITIOF model gives good results at tuning the free parameters of the model
Technical data on nucleonic gauges
International Nuclear Information System (INIS)
2005-07-01
This nucleonic gauge manual and directory provides a reference database of nucleonic control systems available to potential users in the fields of exploration, exploitation and processing of natural resources and in the manufacturing industries. It starts with background information an the general principals of nucleonic gauges, followed by portable nuclear analysis systems (PNAS), computer tomography, cost-benefit on NCS (Nucleonic Control Systems) applications and trends and transfer of NCS technology. It continues with radiation protection and safety, discusses nucleonic gauges with low radioactivity sources and ends with typical models of nucleonic gauges. The basic principles of the most popular techniques are reviewed and reference data links to suppliers are provided. Information sheets on many typical commercial devices are also included. It will help end-users to select the most suitable alternative to solve a particular problem or to measure a certain parameter in a specific process
The two-nucleon system above pion threshold
International Nuclear Information System (INIS)
Poepping, H.; Sauer, P.U.; Zhang Xizhen
1987-01-01
A force model is presented for the description of the two-nucleon system below and above pion threshold and its coupled inelastic channels with one pion. It uses Δ-isobar and pion degrees of freedom in addition to the nucleonic one. The force model is based on a hamiltonian approach within the framework of noncovariant quantum mechanics. It extends the traditional approach with purely nucleonic potentials in isospin-triplet partial waves. It is constructed to remain valid up to 500 MeV c.m. energy. The characteristics of the force model is its mechanism for pion production and pion absorption which is mediated by the Δ-isobar. Even without any fit of phenomenological parameters the force model is able to account for the experimental data of elastic nucleon-nucleon scattering' of the inelastic reactions pp ↔ π + d and of elastic pion-deuteron scattering with satisfactory accuracy. No need for the introduction of dibaryon degrees of freedom has been found yet. The force model is a realistic one in the two-nucleon system. In many-nucleon systems it forms the unifying basis for a microscopic description of nuclear structure and nuclear reactions at low and intermediate energies. (orig.)
On the sensitivity of nucleon-nucleon correlations to the form of short-range potential
International Nuclear Information System (INIS)
Gmitro, M.; Kvasil, J.; Lednicky, R.; Lyuboshitz, V.L.
1986-01-01
Nucleon-nucleon correlation characteristics are calculated for several phenomenological and realistic strong potentials. The results show that a square-well potential reasonably well approximates the nucleon-nucleon interaction if one calculates the correlations between nucleons generated in a region with an r.m.s. radius larger than 1.5-2 fm. Vice versa, the correlations of nucleons emitted from a smaller generation region are sensitive to the form of the assumed nucleon-nucleon potential. (author)
Scattering of vector mesons off nucleons
International Nuclear Information System (INIS)
Lutz, M.F.M.; Friman, B.; Wolf, G.
2001-12-01
We construct a relativistic and unitary approach to 'high' energy pion- and photon-nucleon reactions taking the πN, πΔ, ρN, ωN, ηN, K Λ, KΣ final states into account. Our scheme dynamically generates the s- and d-wave nucleon resonances N(1535), N(1650) and N(1520) and isobar resonances Δ(1620) and δ(1700) in terms of quasi-local interaction vertices. The description of photon-induced processes is based on a generalized vector-meson dominance assumption which directly relates the electromagnetic quasi-local 4-point interaction vertices to the corresponding vertices involving the ρ and ω fields. We obtain a satisfactory description of the elastic and inelastic pion- and photon-nucleon scattering data in the channels considered. The resulting s-wave ρ- and ω-nucleon scattering amplitudes are presented. Using these amplitudes we compute the leading density modification of the ρ and ω mass distributions in nuclear matter. We find a repulsive mass shift for the ω meson at small nuclear density but predict considerable strength in resonance-hole like ω-meson modes. Compared to previous calculations our result for the ρ-meson spectral function shows a significantly smaller in-medium effect. This reflects a not too large coupling strength of the N(1520) resonance to the ρN channel. (orig.)
Nucleon Spin Structure: Longitudinal and Transverse
International Nuclear Information System (INIS)
Chen, Jian-Ping
2011-01-01
Inclusive Deep-Inelastic Scattering (DIS) experiments have provided us with the most extensive information on the unpolarized and longitudinal polarized parton (quark and gluon) distributions in the nucleon. It has becoming clear that transverse spin and transverse momentum dependent distributions (TMDs) study are crucial for a more complete understanding of the nucleon structure and the dynamics of the strong interaction. The transverse spin structure and the TMDs are the subject of increasingly intense theoretical and experimental study recently. With a high luminosity electron beam facility, JLab has played a major role in the worldwide effort to study both the longitudinal and transverse spin structure. Highlights of recent results will be presented. With 12-GeV energy upgrade, JLab will provide the most precise measurements in the valence quark region to close a chapter in longitudinal spin study. JLab will also perform a multi-dimensional mapping of the transverse spin structure and TMDs in the valence quark region through Semi-Inclusive DIS (SIDIS) experiments, providing a 3-d partonic picture of the nucleon in momentum space and extracting the u and d quark tensor charges of the nucleon. The precision mapping of TMDs will also allow a detailed study of the quark orbital motion and its dynamics.
Kalescky, Robert; Kraka, Elfi; Cremer, Dieter
2014-02-01
The formic acid dimer in its C2h-symmetrical cyclic form is stabilized by two equivalent H-bonds. The currently accepted interaction energy is 18.75 kcal/mol whereas the experimental binding energy D0 value is only 14.22 ±0.12 kcal/mol [F. Kollipost, R. W. Larsen, A. V. Domanskaya, M. Nörenberg, and M. A. Suhm, J. Chem. Phys. 136, 151101 (2012)]. Calculation of the binding energies De and D0 at the CCSD(T) (Coupled Cluster with Single and Double excitations and perturbative Triple excitations)/CBS (Complete Basis Set) level of theory, utilizing CCSD(T)/CBS geometries and the frequencies of the dimer and monomer, reveals that there is a 3.2 kcal/mol difference between interaction energy and binding energy De, which results from (i) not relaxing the geometry of the monomers upon dissociation of the dimer and (ii) approximating CCSD(T) correlation effects with MP2. The most accurate CCSD(T)/CBS values obtained in this work are De = 15.55 and D0 = 14.32 kcal/mol where the latter binding energy differs from the experimental value by 0.1 kcal/mol. The necessity of employing augmented VQZ and VPZ calculations and relaxing monomer geometries of H-bonded complexes upon dissociation to obtain reliable binding energies is emphasized.
NN → NN π: the new frontier in nucleon-nucleon interactions
International Nuclear Information System (INIS)
Silbar, R.R.
1986-01-01
The torch in nucleon-nucleon scattering has been passed to experimental and theoretical studies of pion production. Comparing two unitary models shows that most of the structures predicted for spin observables in NN → NNπ are model independent and roughly in agreement with the data. The contribution of rho- exchange is small, indicating the reaction is largely ''peripheral''. The energy dependence of these isobar models is smooth. The largely unstudied reactions producing neutral and negatively-charged pions show richer structure than positively-charged pion production. 6 refs
Effective nucleon-nucleon t matrix in the (p,2p) reaction
International Nuclear Information System (INIS)
Kudo, Y.; Kanayama, N.; Wakasugi, T.
1989-01-01
The cross sections and the analyzing powers for the /sup 40/Ca(p-arrow-right,2p) reactions at E/sub p/ = 76.1, 101.3, and 200 MeV are calculated in the distorted-wave impulse approximation using the Love-Franey effective nucleon-nucleon interaction. It is shown that the calculated individual contributions of the central, spin-orbit, and tensor parts in the Love-Franey interaction to the cross sections and the analyzing powers strongly depend on the incident proton energies. The spectroscopic factors extracted are consistent with the other reaction studies
Effective nucleon-nucleon interaction in the RPA
International Nuclear Information System (INIS)
Batista, E.F.; Carlson, B.V.; Conti, C. de; Frederico, T.
2001-01-01
The purpose of the present work is to study the properties of the effective nucleon-nucleon interaction, in a infinite system of mesons and baryons , using the relativistic Hartree-Fock-Bogoliubov approximation. To derive the RHFB equations in a systematic fashion, we use Dyson's equation to sum to all orders the self-consistent tadpole and exchange contributions to the extended baryon Green's function (the Gorkov propagator). The meson propagator is computed as a sum over ring diagrams which consist in repeated insertions of the lowest-order proper polarization graph. The sum is the diagrammatic equivalent of the relativistic random phase approximation (RPA) that describes the well-known collective modes. In the nuclear medium, the σ and ω propagators are linked because of scalar-vector mixing, a density-dependent effect that generates a coupling between the Dyson's equation for the meson propagators. We use the dressed meson propagator to obtain the effective interaction and investigate its effect on the 1 S 0 pairing in nuclear matter. The effective interaction has title effect on the self-energy mean field, since the latter is dominated by the Hartree contribution, which is determined by the free meson propagators. The pairing field, however, is obtained from an exchange term, in which the effective interaction can play an important role. As the polarization corrections to the meson propagators tend to increase the σ-meson mass and decrease the ω-meson mass, they result in an effective interaction which is more repulsive than the bare one. We would expect this to result in a decrease in the 1 S 0 pairing, similar to that seen in nonrelativistic calculations. (author)
Role of Electrostatics in Protein-RNA Binding: The Global vs the Local Energy Landscape.
Ghaemi, Zhaleh; Guzman, Irisbel; Gnutt, David; Luthey-Schulten, Zaida; Gruebele, Martin
2017-09-14
U1A protein-stem loop 2 RNA association is a basic step in the assembly of the spliceosomal U1 small nuclear ribonucleoprotein. Long-range electrostatic interactions due to the positive charge of U1A are thought to provide high binding affinity for the negatively charged RNA. Short range interactions, such as hydrogen bonds and contacts between RNA bases and protein side chains, favor a specific binding site. Here, we propose that electrostatic interactions are as important as local contacts in biasing the protein-RNA energy landscape toward a specific binding site. We show by using molecular dynamics simulations that deletion of two long-range electrostatic interactions (K22Q and K50Q) leads to mutant-specific alternative RNA bound states. One of these states preserves short-range interactions with aromatic residues in the original binding site, while the other one does not. We test the computational prediction with experimental temperature-jump kinetics using a tryptophan probe in the U1A-RNA binding site. The two mutants show the distinct predicted kinetic behaviors. Thus, the stem loop 2 RNA has multiple binding sites on a rough RNA-protein binding landscape. We speculate that the rough protein-RNA binding landscape, when biased to different local minima by electrostatics, could be one way that protein-RNA interactions evolve toward new binding sites and novel function.
Chiral symmetry and the nucleon--nucleon interaction
International Nuclear Information System (INIS)
Brown, G.E.
1977-01-01
The nucleon--nucleon interaction is understood in terms of a dynamic model, the sigma model. The anti NN → ππ helicity amplitudes are assumed to be physical data, and the dynamical model must reproduce these data, more or less. 14 references
Solitary wave exchange potential and nucleon-nucleon interaction
International Nuclear Information System (INIS)
Prema, K.; Raghavan, S.S.; Sekhar Raghavan
1986-11-01
Nucleon-nucleon interaction is studied using a phenomenological potential model called solitary wave exchange potential model. It is shown that this simple model reproduces the singlet and triplet scattering data and the deuteron parameters reasonably well. (author). 6 refs, 2 figs, 1 tab
Isospin breaking in the pion-nucleon coupling constant and the nucleon-nucleon scattering length
Directory of Open Access Journals (Sweden)
V. A. Babenko
2016-08-01
Full Text Available Charge independence breaking (CIB in the pion-nucleon coupling constant and the nucleon-nucleon scattering length is considered on the basis of the Yukawa meson theory. CIB effect in these quantities is almost entirely explained by the mass difference between the charged and the neutral pions. Therewith charge splitting of the pion-nucleon coupling constant is almost the same as charge splitting of the pion mass. Calculated difference between the proton-proton and the neutron-proton scattering length in this case comprises ∼90% of the experimental value.
Contribution of charge symmetry breaking interactions in binding energy difference of mirror nuclei
International Nuclear Information System (INIS)
Asghari, M.
2006-01-01
Nolen-Schiffer Anomaly in mirror nuclei due to the NN interactions with isospin mixing between T=0 and T=1 mesons of the same spin and parity are investigated. With the computation of coulomb energy along with the charge symmetry breaking effects provide a reasonably accurate description of binding energy differences between 39 Ca- 39 K , 41 Sc- 41 Ca mirror nuclei
International Nuclear Information System (INIS)
Bensafa, I.K.
2006-05-01
The first part of this work presents the analysis and results of the VCS-SSA (virtual Compton scattering - single spin asymmetry) experiment at MAMI (Mainz). It was carried out with beam energy 883 MeV and longitudinal polarization (about 80%), at virtual photon four-momentum transfer squared (Q 2 = 0.35 GeV 2 ) to measure the beam asymmetry in the ep → epγ and ep → epπ 0 reactions. The asymmetry obtained in photon (resp. pion) electro-production is between 0-15% (resp. 0-2%). The dispersion relation model for virtual Compton scattering and MAID model (for π 0 ) reproduce the amplitude globally but not completely the shape of the asymmetry. Perhaps this discrepancy is due to an imperfect parameterization of some pion production multipoles (γ * N → πN). The second part is dedicated to the study of the nucleon energy spectrum in ground-state L=0 and excited-state L=1 in the quark model, using the Coulomb + linear potential type (CL) and a relativistic correction. The hyperfine correction is applied to discriminate the nucleon masses. The values of the mass found for the proton and the Δ(1232) are respectively equal to (968 MeV, 1168 MeV), and the masses of the excited states are between 1564 - 1607 MeV. This part is completed by an application of the CL model to an approximate calculation of generalized polarizabilities of the proton. (author)
Pion-nucleon scattering: from chiral perturbation theory to Roy-Steiner equations
Kubis, Bastian; Hoferichter, Martin; de Elvira, Jacobo Ruiz; Meißner, Ulf-G.
2016-11-01
Ever since Weinberg's seminal predictions of the pion-nucleon scattering amplitudes at threshold, this process has been of central interest for the study of chiral dynamics involving nucleons. The scattering lengths or the pion-nucleon σ-term are fundamental quantities characterizing the explicit breaking of chiral symmetry by means of the light quark masses. On the other hand, pion-nucleon dynamics also strongly affects the long-range part of nucleon-nucleon potentials, and hence has a far-reaching impact on nuclear physics. We discuss the fruitful combination of dispersion-theoretical methods, in the form of Roy-Steiner equations, with chiral dynamics to determine pion-nucleon scattering amplitudes at low energies with high precision.*
Nucleon-pair approximation to the nuclear shell model
Energy Technology Data Exchange (ETDEWEB)
Zhao, Y.M., E-mail: ymzhao@sjtu.edu.cn [Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Arima, A. [Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Musashi Gakuen, 1-26-1 Toyotamakami Nerima-ku, Tokyo 176-8533 (Japan)
2014-12-01
Atomic nuclei are complex systems of nucleons–protons and neutrons. Nucleons interact with each other via an attractive and short-range force. This feature of the interaction leads to a pattern of dominantly monopole and quadrupole correlations between like particles (i.e., proton–proton and neutron–neutron correlations) in low-lying states of atomic nuclei. As a consequence, among dozens or even hundreds of possible types of nucleon pairs, very few nucleon pairs such as proton and neutron pairs with spin zero, two (in some cases spin four), and occasionally isoscalar spin-aligned proton–neutron pairs, play important roles in low-energy nuclear structure. The nucleon-pair approximation therefore provides us with an efficient truncation scheme of the full shell model configurations which are otherwise too large to handle for medium and heavy nuclei in foreseeable future. Furthermore, the nucleon-pair approximation leads to simple pictures in physics, as the dimension of nucleon-pair subspace is always small. The present paper aims at a sound review of its history, formulation, validity, applications, as well as its link to previous approaches, with the focus on the new developments in the last two decades. The applicability of the nucleon-pair approximation and numerical calculations of low-lying states for realistic atomic nuclei are demonstrated with examples. Applications of pair approximations to other problems are also discussed.
Nucleon decay in a realistic SO(10) SUSY GUT
International Nuclear Information System (INIS)
Lucas, V.; Raby, S.
1997-01-01
In this paper, we calculate neutron and proton decay rates and branching ratios in a predictive SO(10) SUSY GUT which agrees well with low energy data. We show that the nucleon lifetimes are consistent with the experimental bounds. The nucleon decay rates are calculated using all one-loop chargino and gluino-dressed diagrams regardless of their chiral structure. We show that the four-fermion operator C jk (u R d jR )(d kL ν τL ), commonly neglected in previous nucleon decay calculations, not only contributes significantly to nucleon decay, but, for many values of the initial GUT parameters and for large tanβ, actually dominates the decay rate. As a consequence, we find that τ p /τ n is often substantially larger than the prediction obtained in small tanβ models. We also find that gluino-dressed diagrams, often neglected in nucleon decay calculations, contribute significantly to nucleon decay. In addition we find that the branching ratios obtained from this realistic SO(10) SUSY GUT differ significantly from the predictions obtained from open-quotes genericclose quotes SU(5) SUSY GUT close-quote s. Thus, nucleon decay branching ratios, when observed, can be used to test theories of fermion masses. copyright 1997 The American Physical Society
Relativistic origin of three-nucleon force
International Nuclear Information System (INIS)
Haberzettl, H.; Parke, W.C.
1995-01-01
Based on the manifestly covariant cluster-dynamical formalism recently proposed by Haberzettl, the three-body forces entering three-nucleon equations are discussed. It is shown that there exist additional contributions to the (nonrelativistic) three-body force, not taken into account in the usual treatments, arising from the proper nonrelativistic limits of higher-order meson-exchange Feynman diagrams. Using the Paris potential, a five-channel triton bound-state calculation results in additional binding of about 0.6 MeV due to this new mechanism. copyright 1995 American Institute of Physics
[Measurements of observables of pion-nucleon reactions]. Progress report
International Nuclear Information System (INIS)
Sadler, M.E.
1985-01-01
This document reports the progress of the research of pion reactions. These include (1) a study to measure observables in the pion-nucleon system in the momentum interval 400 to 700 MeV/c, (2) differential cross section measurements at low energy for pion-nucleon charge exchange, and (3) elastic and inelastic scattering of π +- on 3 H and 3 He. Individual experiments will be indexed separately
A no extensive statistical model for the nucleon structure function
International Nuclear Information System (INIS)
Trevisan, Luis A.; Mirez, Carlos
2013-01-01
We studied an application of nonextensive thermodynamics to describe the structure function of nucleon, in a model where the usual Fermi-Dirac and Bose-Einstein energy distribution were replaced by the equivalent functions of the q-statistical. The parameters of the model are given by an effective temperature T, the q parameter (from Tsallis statistics), and two chemical potentials given by the corresponding up (u) and down (d) quark normalization in the nucleon.
Energy Technology Data Exchange (ETDEWEB)
Burkert, Volker D.
2016-07-25
Recent results of meson photo-production at the existing electron machines with polarized real photon beams and the measurement of polarization observables of the final state baryons have provided high precision data that led to the discovery of new excited nucleon and $\\Delta$ states using multi-channel partial wave analyses procedures. The internal structure of several prominent excited states has been revealed employing meson electroproduction processes. On the theoretical front, lattice QCD is now predicting the baryon spectrum with very similar characteristics as the constituent quark model, and continuum QCD, such as is represented in the Dyson-Schwinger Equations approach and in light front relativistic quark models, describes the non-perturbative behavior of resonance excitations at photon virtuality of $Q^2 > 1.5GeV^2$. In this talk I discuss the need to continue a vigorous program of nucleon spectroscopy and the study of the internal structure of excited states as a way to reveal the effective degrees of freedom underlying the excited states and their dependence on the distance scale probed.
Dressing the nucleon propagator
International Nuclear Information System (INIS)
Fishman, S.; Gersten, A.
1976-01-01
The nucleon propagator in the ''nested bubbles'' approximation is analyzed. The approximation is built from the minimal set of diagrams which is needed to maintain the unitarity condition under two-pion production threshold in the two-nucleon Bethe--Salpeter equation. Recursive formulas for subsets of ''nested bubbles'' diagrams calculated in the framework of the pseudoscalar interaction are obtained by the use of dispersion relations. We prove that the sum of all the ''nested bubbles'' diverges. Moreover, the successive iterations are plagued with ghost poles. We prove that the first approximation--which is the so-called chain approximation--has ghost poles for any nonvanishing coupling constant. In an earlier paper we have shown that ghost poles lead to ghost cuts. These cuts are present in the ''nested bubbles.'' Ghost elimination procedures are discussed. Modifications of the ''nested bubbles'' approximation are introduced in order to obtain convergence and in order to eliminate the ghost poles and ghost cuts. In a similar way as in the Lee model, cutoff functions are introduced in order to eliminate the ghost poles. The necessary and sufficient conditions for the absence of ghost poles are formulated and analyzed. The spectral functions of the modified ''nested bubbles'' are analyzed and computed. Finally, we present a theorem, similar in its form to Levinson's theorem in scattering theory, which enables one to compute in a simple way the number of ghost poles
Hypernuclear interactions and the binding energies of and hypernuclei
Energy Technology Data Exchange (ETDEWEB)
Bodmer, A.R.; Usmani, Q.N.
1988-01-01
By use of variational calculations a reasonable hadronic description is obtained of the s-shell hypernuclei, of /sub /ZBe, and of the well depth, with N forces which are consistent with p scattering and which are quite strongly spin-dependent, with reasonable TPE NN forces with strongly repulsive dispersive-type NN forces. For the latter we also consider a spin-dependent version which is somewhat favored by our analysis. /sub /ZBe is treated as a 2ed + system and is significantly overbound, approx. =1 MeV, if only ed ed and ed potentials are used. An ed ed potential obtained from the NN forces nicely accounts for this overbinding. The hypernuclei /sub /WHe and /sub / Be are treated as ed + 2 and 2ed + 2 systems. Use of the /sub / Be event gives approx. =1.5 MeV too little binding for /sub /WHe. The S0 potential obtained from /sub / Be is quite strongly attractive, comparable to the N and also to the NN potential without OPE. 18 refs.
Personal history of nucleon polarization experiments
International Nuclear Information System (INIS)
Chamberlain, O.
1984-09-01
The history of nucleon scattering experiments is reviewed, starting with the observation of large proton polarizations in scattering from light elements such as carbon, and ending with the acceleration of polarized proton beams in high-energy synchrotrons. Special mention is made about significant contributions made by C.L. Oxley, L. Wolfenstein, R.D. Tripp, T. Ypsilantis, A. Abragam, M. Borghini, T. Niinikoski, Froissart, Stora, A.D. Krisch, and L.G. Ratner
Pion-nucleon scattering and isospin violation
International Nuclear Information System (INIS)
Meissner, U.G.
1999-01-01
The paper discusses low-energy pion-nucleon scattering in the framework of chiral perturbation theory. It is argued that using this theoretical method one is able to match the in some cases impressive experimental accuracy (for the low partial waves). It is also shown how strong and electromagnetic isospin violation can be treated simultaneously. Some first results for neutral pion scattering and the σ-term are given. Copyright (1999) World Scientific Publishing Co. Pte. Ltd
International Nuclear Information System (INIS)
Schwamb, M.
2006-01-01
An overview over present achievements and future challenges in the field of few-nucleon systems is presented. Special emphasis is laid on the construction of a unified approach to hadronic and electromagnetic reactions on few-nucleon systems, necessary for studying the borderline between quark-gluon and effective descriptions. (orig.) (orig.)
Polaron binding energy and effective mass in the GaAs film
International Nuclear Information System (INIS)
Wu Zhenhua; Yan Liangxing; Tian Qiang; Li Hua; Liu Bingcan
2012-01-01
The binding energy and effective mass of a polaron in a GaAs film deposited on the Al 0.3 Ga 0.7 As substrate are studied theoretically by using the fractional-dimensional space approach. Our calculations show that the polaron binding energy and mass shift decrease monotonously with increasing the film thickness. For the film thicknesses with L w ≤ 70Å and the substrate thicknesses with L b ≤ 200Å, the different values of the substrate thickness influence the polaron binding energy and mass shift in the GaAs film. The polaron binding energy and mass shift increase monotonously with increasing the substrate thickness. For the film thickness with L w ≥ 70Å or the substrate thicknesses with L b ≤ 200Å, the different values of the substrate thickness have no significant influence on the polaron binding energy and mass shift in the GaAs film deposited on the Al 0.3 Ga 0.7 As substrate.
BFEE: A User-Friendly Graphical Interface Facilitating Absolute Binding Free-Energy Calculations.
Fu, Haohao; Gumbart, James C; Chen, Haochuan; Shao, Xueguang; Cai, Wensheng; Chipot, Christophe
2018-03-26
Quantifying protein-ligand binding has attracted the attention of both theorists and experimentalists for decades. Many methods for estimating binding free energies in silico have been reported in recent years. Proper use of the proposed strategies requires, however, adequate knowledge of the protein-ligand complex, the mathematical background for deriving the underlying theory, and time for setting up the simulations, bookkeeping, and postprocessing. Here, to minimize human intervention, we propose a toolkit aimed at facilitating the accurate estimation of standard binding free energies using a geometrical route, coined the binding free-energy estimator (BFEE), and introduced it as a plug-in of the popular visualization program VMD. Benefitting from recent developments in new collective variables, BFEE can be used to generate the simulation input files, based solely on the structure of the complex. Once the simulations are completed, BFEE can also be utilized to perform the post-treatment of the free-energy calculations, allowing the absolute binding free energy to be estimated directly from the one-dimensional potentials of mean force in simulation outputs. The minimal amount of human intervention required during the whole process combined with the ergonomic graphical interface makes BFEE a very effective and practical tool for the end-user.
Lanthanide 4f-electron binding energies and the nephelauxetic effect in wide band gap compounds
International Nuclear Information System (INIS)
Dorenbos, Pieter
2013-01-01
Employing data from luminescence spectroscopy, the inter 4f-electron Coulomb repulsion energy U(6, A) in Eu 2+/3+ impurities together with the 5d-centroid energy shift ϵ c (1,3+,A) in Ce 3+ impurities in 40 different fluoride, chloride, bromide, iodide, oxide, sulfide, and nitride compounds has been determined. This work demonstrates that the chemical environment A affects the two energies in a similar fashion; a fashion that follows the anion nephelauxetic sequence F, O, Cl, Br, N, I, S, Se. One may then calculate U(6, A) from well established and accurate ϵ c (1,3+,A) values which are then used as input to the chemical shift model proposed in Dorenbos (2012) [19]. As output it provides the chemical shift of 4f-electron binding energy and therewith the 4f-electron binding energy relative to the vacuum energy. In addition this method provides a tool to routinely establish the binding energy of electrons at the top of the valence band (work function) and the bottom of the conduction band (electron affinity) throughout the entire family of inorganic compounds. How the electronic structure of the compound and lanthanide impurities therein change with type of compound and type of lanthanide is demonstrated. -- Highlights: ► A relationship between 5d centroid shift and 4f-electron Coulomb repulsion energy is established. ► Information on the absolute 4f-electron binding energy of lanthanides in 40 compounds is provided. ► A new tool to determine absolute binding energies of electrons in valence and conduction bands is demonstrated
International Nuclear Information System (INIS)
Liu Weina; Li Ping; Gou Qingquan; Zhao Yanping
2008-01-01
The formation mechanism for the body-centred regular icosahedral structure of Li 13 cluster is proposed. The curve of the total energy versus the separation R between the nucleus at the centre and nuclei at the apexes for this structure of Li 13 has been calculated by using the method of Gou's modified arrangement channel quantum mechanics (MACQM). The result shows that the curve has a minimal energy of -96.951 39 a.u. at R = 5.46a 0 . When R approaches to infinity, the total energy of thirteen lithium atoms has the value of -96.564 38 a.u. So the binding energy of Li 13 with respect to thirteen lithium atoms is 0.387 01 a.u. Therefore the binding energy per atom for Li 13 is 0.029 77 a.u. or 0.810 eV, which is greater than the binding energy per atom of 0.453 eV for Li 2 , 0.494 eV for Li 3 , 0.7878 eV for Li 4 , 0.632 eV for Li 5 , and 0.674 eV for Li 7 calculated by us previously. This means that the Li 13 cluster may be formed stably in a body-centred regular icosahedral structure with a greater binding energy
Estimating Atomic Contributions to Hydration and Binding Using Free Energy Perturbation.
Irwin, Benedict W J; Huggins, David J
2018-05-08
We present a general method called atom-wise free energy perturbation (AFEP), which extends a conventional molecular dynamics free energy perturbation (FEP) simulation to give the contribution to a free energy change from each atom. AFEP is derived from an expansion of the Zwanzig equation used in the exponential averaging method by defining that the system total energy can be partitioned into contributions from each atom. A partitioning method is assumed and used to group terms in the expansion to correspond to individual atoms. AFEP is applied to six example free energy changes to demonstrate the method. Firstly, the hydration free energies of methane, methanol, methylamine, methanethiol, and caffeine in water. AFEP highlights the atoms in the molecules that interact favorably or unfavorably with water. Finally AFEP is applied to the binding free energy of human immunodeficiency virus type 1 protease to lopinavir, and AFEP reveals the contribution of each atom to the binding free energy, indicating candidate areas of the molecule to improve to produce a more strongly binding inhibitor. FEP gives a single value for the free energy change and is already a very useful method. AFEP gives a free energy change for each "part" of the system being simulated, where part can mean individual atoms, chemical groups, amino acids, or larger partitions depending on what the user is trying to measure. This method should have various applications in molecular dynamics studies of physical, chemical, or biochemical phenomena, specifically in the field of computational drug discovery.
Binding energies of hypernuclei and Λ-nuclear interactions
International Nuclear Information System (INIS)
Bodmer, A.R.; Usmani, Q.N.
1984-01-01
Variational calculations indicate that a reasonable description of Λp scattering and of Λ separation energies can be obtained in terms of ΛN plus dispersive and TPE ΛNN forces. Results for the ΛΛ interaction and for 6 /sub Λ/He obtained from an analysis of 10 /sub ΛΛ/Be are discussed. Coulomb and ΛN charge symmetry breaking effects in the A = 4 hypernuclei are discussed
Towards Automated Binding Affinity Prediction Using an Iterative Linear Interaction Energy Approach
Directory of Open Access Journals (Sweden)
C. Ruben Vosmeer
2014-01-01
Full Text Available Binding affinity prediction of potential drugs to target and off-target proteins is an essential asset in drug development. These predictions require the calculation of binding free energies. In such calculations, it is a major challenge to properly account for both the dynamic nature of the protein and the possible variety of ligand-binding orientations, while keeping computational costs tractable. Recently, an iterative Linear Interaction Energy (LIE approach was introduced, in which results from multiple simulations of a protein-ligand complex are combined into a single binding free energy using a Boltzmann weighting-based scheme. This method was shown to reach experimental accuracy for flexible proteins while retaining the computational efficiency of the general LIE approach. Here, we show that the iterative LIE approach can be used to predict binding affinities in an automated way. A workflow was designed using preselected protein conformations, automated ligand docking and clustering, and a (semi-automated molecular dynamics simulation setup. We show that using this workflow, binding affinities of aryloxypropanolamines to the malleable Cytochrome P450 2D6 enzyme can be predicted without a priori knowledge of dominant protein-ligand conformations. In addition, we provide an outlook for an approach to assess the quality of the LIE predictions, based on simulation outcomes only.
Computational scheme for pH-dependent binding free energy calculation with explicit solvent.
Lee, Juyong; Miller, Benjamin T; Brooks, Bernard R
2016-01-01
We present a computational scheme to compute the pH-dependence of binding free energy with explicit solvent. Despite the importance of pH, the effect of pH has been generally neglected in binding free energy calculations because of a lack of accurate methods to model it. To address this limitation, we use a constant-pH methodology to obtain a true ensemble of multiple protonation states of a titratable system at a given pH and analyze the ensemble using the Bennett acceptance ratio (BAR) method. The constant pH method is based on the combination of enveloping distribution sampling (EDS) with the Hamiltonian replica exchange method (HREM), which yields an accurate semi-grand canonical ensemble of a titratable system. By considering the free energy change of constraining multiple protonation states to a single state or releasing a single protonation state to multiple states, the pH dependent binding free energy profile can be obtained. We perform benchmark simulations of a host-guest system: cucurbit[7]uril (CB[7]) and benzimidazole (BZ). BZ experiences a large pKa shift upon complex formation. The pH-dependent binding free energy profiles of the benchmark system are obtained with three different long-range interaction calculation schemes: a cutoff, the particle mesh Ewald (PME), and the isotropic periodic sum (IPS) method. Our scheme captures the pH-dependent behavior of binding free energy successfully. Absolute binding free energy values obtained with the PME and IPS methods are consistent, while cutoff method results are off by 2 kcal mol(-1) . We also discuss the characteristics of three long-range interaction calculation methods for constant-pH simulations. © 2015 The Protein Society.
Phenomenological model for non-equilibrium deuteron emission in nucleon induced reactions
International Nuclear Information System (INIS)
Broeders, C.H.M.; Konobeyev, A.Yu.
2005-01-01
A new approach is proposed for the calculation of non-equilibrium deuteron energy distributions in nuclear reactions induced by nucleons of intermediate energies. It combines the model of the nucleon pick-up, the coalescence and the deuteron knock-out. Emission and absorption rates for excited particles are described by the pre-equilibrium hybrid model. The model of Sato, Iwamoto, Harada is used to describe the nucleon pick-up and the coalescence of nucleons from the exciton configurations starting from (2p, 1h). The model of deuteron knock-out is formulated taking into account the Pauli principle for the nucleon-deuteron interaction inside a nucleus. The contribution of the direct nucleon pick-up is described phenomenologically. The multiple pre-equilibrium emission of particles is taken into account. The calculated deuteron energy distributions are compared with experimental data from 12 C to 209 Bi. (orig.)
2002-01-01
The proposal concerns an extension to higher energies of previous experiments which have provided evidence for anomalously short reaction mean free paths among projectile fragments from heavy ion interactions.\\\\ \\\\ It is intended to provide information on the interaction properties of projectile fragments, mainly 3He, P, D, T as well as of scattered 4He nuclei in passive detectors exposed to beams of energies exceeding those available in previous experim factor of about 7. \\\\ \\\\ Interaction mean free paths and event topologies will be measured in a nuclear emulsion stack (LBL) of 7.5~cm~x~5~cm~x~25~cm dimensions. Decay effects will be recorded by comparing the activity of spallation residues in dense and diluted copper target assemblies (Marburg). Target fragmentation will be studied in a stack of silverchloride crystal foils (Frankfurt) of about 7~cm~x~6~cm~x~1~cm dimensions. The \\alpha beam ejected at EJ~62 will be used to provide both exposures at high intensity of 10|1|2 alphas on th and at low intensity ...
Energy Technology Data Exchange (ETDEWEB)
Yavshits, S G [V.G. Khlopin Radium Institute, St. Petersburg (Russian Federation)
2011-05-15
The main goal of the project is to the development of nuclear data calculation technique for innovative hybrid nuclear technologies, first at all for technology of radioactive waste transmutation and energy production. Within the framework of the project two main problems were decided: - development of a reliable code enabling for calculation of main characteristics of nuclear reactions induced by nucleons in wide energy range; - development of nuclear data library containing complete transport files for hybrid accelerator- driven systems. The results of the project have both fundamental and applied character. Within the framework of the project the following main results were obtained: The analysis of experimental and theoretical data for all items in question of new data library; The development of new parameterization of global optical potential which is necessary for entrance channel simulation and development of appropriate subroutines for a code realizing method of coupled channels for reaction cross-section calculations; The updating of existing models and codes and the development of new ones for a fast reaction stage (intranuclear cascade model), preequilibrium stage (model with a multiple emission of particles) and final stage (statistical model of fission/particle emission competition) for reactions with intermediate energy nucleons; The development of model for fission barriers and fission products yield calculations; inclusion of the appropriate subroutines in a statistical code; The test calculations with the code system developed and analysis of the results and comparison with existing experimental data; The systematical calculations for reactions with protons and neutrons (20-1000 MeV) for a wide range of targets; For each reaction (fixed target + projectile (proton or neutron) for fixed energy) the nuclear data file in the ENDF-6 format has been developed, including: - total cross section, reaction cross section and cross section of elastic
Distribution of binding energies of a water molecule in the water liquid-vapor interface
Energy Technology Data Exchange (ETDEWEB)
Chempath, Shaji [Los Alamos National Laboratory; Pratt, Lawrence R [TULANE UNIV
2008-01-01
Distributions of binding energies of a water molecule in the water liquid-vapor interface are obtained on the basis of molecular simulation with the SPC/E model of water. These binding energies together with the observed interfacial density profile are used to test a minimally conditioned Gaussian quasi-chemical statistical thermodynamic theory. Binding energy distributions for water molecules in that interfacial region clearly exhibit a composite structure. A minimally conditioned Gaussian quasi-chemical model that is accurate for the free energy of bulk liquid water breaks down for water molecules in the liquid-vapor interfacial region. This breakdown is associated with the fact that this minimally conditioned Gaussian model would be inaccurate for the statistical thermodynamics of a dilute gas. Aggressive conditioning greatly improves the performance of that Gaussian quasi-chemical model. The analogy between the Gaussian quasi-chemical model and dielectric models of hydration free energies suggests that naive dielectric models without the conditioning features of quasi-chemical theory will be unreliable for these interfacial problems. Multi-Gaussian models that address the composite nature of the binding energy distributions observed in the interfacial region might provide a mechanism for correcting dielectric models for practical applications.
Collective multipole excitations based on correlated realistic nucleon-nucleon interactions
International Nuclear Information System (INIS)
Paar, N.; Papakonstantinou, P.; Hergert, H.; Roth, R.
2006-01-01
We investigate collective multipole excitations for closed shell nuclei from 16 O to 208 Pb using correlated realistic nucleon-nucleon interactions in the framework of the random phase approximation (RPA). The dominant short-range central and tensor correlations a re treated explicitly within the Unitary Correlation Operator Method (UCOM), which provides a phase-shift equivalent correlated interaction VUCOM adapted to simple uncorrelated Hilbert spaces. The same unitary transformation that defines the correlated interaction is used to derive correlated transition operators. Using VUCOM we solve the Hartree-Fock problem and employ the single-particle states as starting point for the RPA. By construction, the UCOM-RPA is fully self-consistent, i.e. the same correlated nucleon-nucleon interact ion is used in calculations of the HF ground state and in the residual RPA interaction. Consequently, the spurious state associated with the center-of-mass motion is properly removed and the sum-rules are exhausted within ±3%. The UCOM-RPA scheme results in a collective character of giant monopole, dipole, and quadrupole resonances in closed-shell nuclei across the nuclear chart. For the isoscalar giant monopole resonance, the resonance energies are in agreement with experiment hinting at a reasonable compressibility. However, in the 1 - and 2 + channels the resonance energies are overestimated due to missing long-range correlations and three-body contributions. (orig.)
Phase variation of nucleon-nucleon amplitude for proton-12C elastic scattering
International Nuclear Information System (INIS)
Deng Yibing; Wang Shilai; Yin Gaofang
2006-01-01
Franco and Yin studied for α- 4 He, 3 He, 2 He, 1 He elastic-scattering by using the phase of the nucleon-nucleon elastic-scattering amplitude varies with momentum transfer in the framework of Glauber multiple scattering theory at intermediate energy. The phase variation leads to large changes in the differential cross sections, and brings the Glauber theory into agreement with experimental data. Later Lombard and Maillet is based on the suggestion by Franco and Yin studied for the p- 4 He elastic-scattering in the framework of Glauber theory, and found this phase to be actually important for the description of spin observables. Recently Wang Shilai and Deng Yibing et al studied for the p- 4 He elastic-scattering in the framework of KMT multiple scattering theory at intermediate energy, and found this phase lead to differential cross sections and polarization, which are in better agreement with experimental data. This paper is based on the suggestion by Franco and Yin that the phase of the nucleon-nucleon scattering amplitude should vary with momentum transfer. The proton elastic scattering on 12 C is studied in the KMT multiple scattering theory with microscopic momentum space first term optical potential. The Coulomb interactions are taken into account in our calculation. The theoretical calculation results show that the phase leads to differential cross section and polarization are in better agreement with experimental data. In conclusion this phase is actually important in the framework of KMT theory. (authors)
Nucleon exchange and heat partition in damped collisions
International Nuclear Information System (INIS)
Planeta, R.; Kwiatkowski, K.; Zhou, S.H.; Viola, V.E.; Breuer, H.; McMahan, M.A.; Randrup, J.; Mignerey, A.C.
1989-01-01
Mass and charge distributions have been measured for damped projectile-like fragments in the reaction /sup 74/Ge+/sup 165/Ho at 8.5 MeV per nucleon bombarding energy. Coincidences were measured between angle-correlated reaction partners in order to derive the primary mass distribution and the excitation energy distribution for projectile-like fragments. The evolution of the primary N and Z distributions as a function of energy loss is found to deviate significantly from predictions of the nucleon exchange transport model. The fraction of excitation energy residing in the projectile-like fragment is shown to depend both upon energy loss and the direction of the nucleon flow
Transverse momentum distributions inside the nucleon from lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Musch, Bernhard Ulrich
2009-05-29
Nucleons, i.e., protons and neutrons, are composed of quarks and gluons, whose interactions are described by the theory of quantum chromodynamics (QCD), part of the standard model of particle physics. This work applies lattice QCD to compute quark momentum distributions in the nucleon. The calculations make use of lattice data generated on supercomputers that has already been successfully employed in lattice studies of spatial quark distributions (''nucleon tomography''). In order to be able to analyze transverse momentum dependent parton distribution functions, this thesis explores a novel approach based on non-local operators. One interesting observation is that the transverse momentum dependent density of polarized quarks in a polarized nucleon is visibly deformed. A more elaborate operator geometry is required to enable a quantitative comparison to high energy scattering experiments. First steps in this direction are encouraging. (orig.)
Relativistic generalizations of simple pion-nucleon models
International Nuclear Information System (INIS)
McLeod, R.J.; Ernst, D.J.
1981-01-01
A relativistic, partial wave N/D dispersion theory is developed for low energy pion-nucleon elastic scattering. The theory is simplified by treating crossing symmetry only to lowest order in the inverse nucleon mass. The coupling of elastic scattering to inelastic channels is included by taking the necessary inelasticity from experimental data. Three models are examined: pseudoscalar coupling of pions and nucleons, pseudovector coupling, and a model in which all intermediate antinucleons are projected out of the amplitude. The phase shifts in the dominant P 33 channel are quantitatively reproduced for P/sub lab/ 33 phase shifts. Thus a model of the pion-nucleon interaction which does not include antinucleon degrees of freedom is found to be unphysical
Binding energies of hypernuclei and Λ-nuclear interactions
International Nuclear Information System (INIS)
Bodmer, A.R.; Usmani, Q.N.
1985-01-01
Variational Monte Carlo calculations have been made for the s-shell hypernuclei and also of 9 Be hypernuclei with a 2α + Λ model. The well depth is calculated variationally with the Fermi hypernetted chain method. A satisfactory description of all the relevant experimental Λ separation energies and also of the Λp scattering can be obtained with reasonable TPE ΛN and ΛNN forces and strongly repulsive dispersive ΛNN forces which are preferred to be spin dependent. We discuss variational calculations for 6 He and 10 Be hypernuclei with α + 2Λ and 2α + 2Λ models, and the results obtained for the ΛΛ interaction and for 6 He hypernuclei from analysis of 10 Be hypernuclei Coulomb effects and charge symmetry breaking in the A = 4 hypernuclei are discussed. 24 refs., 5 figs
Binding energies of hypernuclei and. lambda. -nuclear interactions
Energy Technology Data Exchange (ETDEWEB)
Bodmer, A.R.; Usmani, Q.N.
1985-01-01
Variational Monte Carlo calculations have been made for the s-shell hypernuclei and also of /sup 9/Be hypernuclei with a 2..cap alpha.. + ..lambda.. model. The well depth is calculated variationally with the Fermi hypernetted chain method. A satisfactory description of all the relevant experimental ..lambda.. separation energies and also of the ..lambda..p scattering can be obtained with reasonable TPE ..lambda..N and ..lambda..NN forces and strongly repulsive dispersive ..lambda..NN forces which are preferred to be spin dependent. We discuss variational calculations for /sup 6/He and /sup 10/Be hypernuclei with ..cap alpha.. + 2..lambda.. and 2..cap alpha.. + 2..lambda.. models, and the results obtained for the ..lambda lambda.. interaction and for /sup 6/He hypernuclei from analysis of /sup 10/Be hypernuclei Coulomb effects and charge symmetry breaking in the A = 4 hypernuclei are discussed. 24 refs., 5 figs.
International Nuclear Information System (INIS)
Holben, B.C.; Bach, R.E.
1975-01-01
A nucleonic measuring instrument is described wherein a housing contains a radiation source and has an aperture controlled by a shutter which is spring loaded to a closed position for confining and shielding the radiation and is movable by a motor to an open position for releasing the radiation, the motor being supplied with power through a heat sensitive element so that it is deenergized and the shutter closes in response to a predetermined high ambient temperature such as may be caused by a fire, and including an explosive blank cartridge positioned in relation to the shutter guide which explodes in response to a still higher ambient temperature, deforming the guide and thereby locking the shutter in the closed position. (auth)
Nucleon Electromagnetic Form Factors
Energy Technology Data Exchange (ETDEWEB)
Marc Vanderhaeghen; Charles Perdrisat; Vina Punjabi
2007-10-01
There has been much activity in the measurement of the elastic electromagnetic proton and neutron form factors in the last decade, and the quality of the data has greatly improved by performing double polarization experiments, in comparison with previous unpolarized data. Here we review the experimental data base in view of the new results for the proton, and neutron, obtained at JLab, MAMI, and MIT-Bates. The rapid evolution of phenomenological models triggered by these high-precision experiments will be discussed, including the recent progress in the determination of the valence quark generalized parton distributions of the nucleon, as well as the steady rate of improvements made in the lattice QCD calculations.
Biexciton binding energy in ZnSe quantum wells and quantum wires
DEFF Research Database (Denmark)
Wagner, Hans-Peter; Langbein, Wolfgang; Hvam, Jørn Märcher
2002-01-01
The biexciton binding energy E-XX is investigated in ZnSe/ZnMgSe quantum wells and quantum wires as a function of the lateral confinement by transient four-wave mixing. In the quantum wells one observes for decreasing well width a significant increase in the relative binding energy, saturating...... for well widths less than 8 nm. In the quantum wires an increase of 30% is found in the smallest quantum wire structures compared to the corresponding quantum well value. A simple analytical model taking into account the quantum confinement in these low-dimensional systems is used to explain...
Binding energy of impurity states in an inverse parabolic quantum well under magnetic field
International Nuclear Information System (INIS)
Kasapoglu, E.; Sari, H.; Soekmen, I.
2007-01-01
We have investigated the effects of the magnetic field which is directed perpendicular to the well on the binding energy of the hydrogenic impurities in an inverse parabolic quantum well (IPQW) with different widths as well as different Al concentrations at the well center. The Al concentration at the barriers was always x max =0.3. The calculations were performed within the effective mass approximation, using a variational method. We observe that IPQW structure turns into parabolic quantum well with the inversion effect of the magnetic field and donor impurity binding energy in IPQW strongly depends on the magnetic field, Al concentration at the well center and well dimensions
Pressure-dependent shallow donor binding energy in InGaN/GaN square QWWs
International Nuclear Information System (INIS)
Ghazi, Haddou El; Jorio, Anouar; Zorkani, Izeddine
2013-01-01
Using a variational approach, we perform a theoretical study of hydrostatic pressure effect on the ground-state of axial hydrogenic shallow-donor impurity binding energy in InGaN/GaN square quantum well wire (SQWWs) as a function of the side length within the effective-mass scheme and finite potential barrier. The pressure dependence of wire length, effective mass, dielectric constant and potential barrier are taken into account. Numerical results show that: (i) the binding energy is strongly affected by the wire length and the external applied pressure and (ii) its maximum moves to the narrow wire in particular for height pressure.
Simple method for determining binding energies of fullerene and complex atomic negative ions
Felfli, Zineb; Msezane, Alfred
2017-04-01
A robust potential which embeds fully the vital core polarization interaction has been used in the Regge pole method to explore low-energy electron scattering from C60, Eu and Nb through the total cross sections (TCSs) calculations. From the characteristic dramatically sharp resonances in the TCSs manifesting negative ion formation in these systems, we extracted the binding energies for the C60, Euand Nbanions they are found to be in outstanding agreement with the measured electron affinities of C60, Eu and Nb. Common among these considered systems, including the standard atomic Au is the formation of their ground state negative ions at the second Ramsauer-Townsend (R-T) minima of their TCSs. Indeed, this is a signature of all the fullerenes and complex atoms considered thus far. Shape resonances, R-T minima and binding energies of the resultant anions are presented. This work was supported by U.S. DOE, Basic Energy Sciences, Office of Energy Research.
Structure-based prediction of free energy changes of binding of PTP1B inhibitors
Wang, Jing; Ling Chan, Shek; Ramnarayan, Kal
2003-08-01
The goals were (1) to understand the driving forces in the binding of small molecule inhibitors to the active site of PTP1B and (2) to develop a molecular mechanics-based empirical free energy function for compound potency prediction. A set of compounds with known activities was docked onto the active site. The related energy components and molecular surface areas were calculated. The bridging water molecules were identified and their contributions were considered. Linear relationships were explored between the above terms and the binding free energies of compounds derived based on experimental inhibition constants. We found that minimally three terms are required to give rise to a good correlation (0.86) with predictive power in five-group cross-validation test (q2 = 0.70). The dominant terms are the electrostatic energy and non-electrostatic energy stemming from the intra- and intermolecular interactions of solutes and from those of bridging water molecules in complexes.
Charge dependence of the pion-nucleon coupling constant
Directory of Open Access Journals (Sweden)
V. A. Babenko
2015-07-01
Full Text Available On the basis of the Yukawa potential we study the pion-nucleon coupling constants for the neutral and charged pions assuming that nuclear forces at low energies are mainly determined by the exchange of virtual pions. We obtain the charged pseudovector pion-nucleon coupling constant f2π± = 0.0804(7 by making the use of experimental low-energy scattering parameters for the singlet pp- and np-scattering, and also by use of the neutral pseudovector pion-nucleon coupling constant f2π0 = 0.0749(7. Corresponding value of the charged pseudoscalar pion-nucleon coupling constant g2π0 / 4π = 14.55(13 is also determined. This calculated value of the charged pseudoscalar pion-nucleon coupling constant is in fully agreement with the experimental constant g2π0 / 4π = 14.52(26 obtained by the Uppsala Neutron Research Group. Our results show considerable charge splitting of the pion-nucleon coupling constant.
Diquarks and nucleon structure functions
International Nuclear Information System (INIS)
Linkevich, A.D.; Savrin, V.I.; Skachkov, N.B.
1982-01-01
Formulae for structure functions of the deep-inelastic lepton-nucleon scattering are obtained through relativistic wave functions of systems composed of particles with spins 0, 1/2 and 1, 1/2. These wave functions are solutions of covariant two-particle single-time equations describing the nucleon as a system formed out of a quark and a diquark. Diquark is considered as a boson with the spin 0 and 1. The expressions for the nucleon structure functions are obtained by using the matrix elements of the current operator corresponding to the elastic scattering of the photon on a quark and on a diquark [ru
International Nuclear Information System (INIS)
Close, F.E.
1993-06-01
When the new data on polarised lepton nucleon scattering are compared at the same value of Q 2 and with a common set of assumptions, a consistent picture of the spin content of the nucleon begins to emerge. Higher order effects in O(α s ), higher twist effects, modern data on unpolarised structure functions and an updated value for F/D are all important in analysing the data. The detailed x dependences of the polarisation asymmetry in the valence quark region are shown to confirm 20 year old predictions of the quark model and I argue that these are an important ingredient in decoding the nucleon spin puzzle. (author)
International Nuclear Information System (INIS)
Close, F.E.
1994-01-01
When the new data on polarised lepton nucleon scattering are compared at the same value of Q 2 and with a common set of assumptions, a consistent picture of the spin content of the nucleon begins to emerge. Higher order effects in 0(α s ), higher twist effects, modern data on unpolarized structure functions and an updated value for F/D are all important in analysing the data. The detailed x dependences of the polarisation asymmetry in the valence quark region are shown to confirm 20 year old predictions of the quark model and I argue that these are an important ingredient in decoding the nucleon spin puzzle. (author)
Probing nuclear structure with nucleons
International Nuclear Information System (INIS)
Bauge, E.
2007-01-01
The goal of this lecture is to show how nucleon scattering can be used to probe the structure of target nuclei, and how nucleon scattering observables can be interpreted in terms of nuclear structure using microscopic optical potentials. After a brief overview of the specificities of nucleon-nucleus scattering, and a quick reminder on scattering theory, the main part of this lecture is devoted to the construction of optical potentials in which the target nuclei structure information is folded with an effective interaction. Several examples of such microscopic optical model potentials are given. (author)
Nucleon-nucleon interaction with quark exchange and prediction of the color van der Waals potential
International Nuclear Information System (INIS)
Osman, A.
1988-01-01
The nucleon-nucleon interaction is considered by including the color nucleon clusters. The nucleon-nucleon system is treated as a six-quark system. The obtained local potentials reduce the short-range repulsion. The resulting nucleon-nucleon potential, using a quark-quark potential, agress well with the central-force potentials. The phase shifts calculated by using these local potentials are in good agreement with those obtained from other methods. Introducing the quark-quark potential in the nucleon-nucleon interaction leads to a color van der Waals potential much stronger than that implied by experiments
Nucleon-nucleon interaction with quark exchanges and prediction to colour van der Waals potential
International Nuclear Information System (INIS)
Osman, A.
1985-11-01
The nucleon-nucleon interaction is considered by including the colour nucleon clusters. The nucleon-nucleon system is treated as a six-quark system. The obtained local potentials reduce the short-range repulsion. The resulted nucleon-nucleon potential by using a quark-quark potential well agrees with the central-force potentials. The phase shifts calculated by using these local potentials are in good agreement with those obtained from other methods. Introducing the quark-quark potential in the nucleon-nucleon interaction, leads to a colour van der Waals potential very strong compared with that predicted by experiments. (author)
Nucleon-Nucleon Potentials and Computation of Scattering Phase Shifts
Directory of Open Access Journals (Sweden)
Jhasaketan Bhoi
2015-12-01
Full Text Available By judicious exploitation of supersymmetry formalism of quantum mechanics higher partial wave nucleon-nucleon potentials are generated from its ground state interactions. The nuclear Hulthen potential and the corresponding ground state wave function with the parameters of Arnold and MacKellar are used as the starting point of our calculation. We compute the scattering phase shifts for our constructed potentials through Phase Function Method to examine the merit of our approach to the problem.
Hydrostatic-pressure effects on the donor binding energy in GaAs-(Ga, Al)As quantum dots
International Nuclear Information System (INIS)
Perez-Merchancano, S T; Paredes-Gutierrez, H; Silva-Valencia, J
2007-01-01
The binding energy of shallow hydrogenic impurities in a spherical quantum dot under isotropic hydrostatic pressure is calculated using a variational approach within the effective mass approximation. The binding energy is computed as a function of hydrostatic pressure, dot size and impurity position. The results show that the impurity binding energy increases with the pressure for any position of the impurity. Also, we have found that the binding energy depends on the location of the impurity and the pressure effects are less pronounced for impurities on the edge
International Nuclear Information System (INIS)
Zheng, Y.; Brion, C.E.; Brunger, M.J.; Zhao, K.; Grisogono, A.M.; Braidwood, S.; Weigold, E.; Chakravorty, S.J.; Davidson, E.R.; Sgamellotti, A.; von Niessen, W.
1996-01-01
The first electronic structural study of the complete valence shell binding energy spectrum of molecular fluorine, encompassing both the outer and inner valence regions, is reported. These binding energy spectra as well as the individual orbital momentum profiles have been measured using an energy dispersive multichannel electron momentum spectrometer at a total energy of 1500 eV, with an energy resolution of 1.5 eV and a momentum resolution of 0.1 a.u. The measured binding energy spectra in the energy range of 14-60 eV are compared with the results of ADC(4) many-body Green's function and also direct-Configuration Interaction (CI) and MRSD-CI calculations. The experimental orbital electron momentum profiles are compared with SCF theoretical profiles calculated using the target Hartree-Fock approximation with a range of basis sets and with Density Functional Theory predictions in the target Kohn-Sham approximation with non-local potentials. The truncated (aug-cc-pv5z) Dunning basis sets were used for the Density Functional Theory calculations which also include some treatment of correlation via the exchange and correlation potentials. Comparisons are also made with the full ion-neutral overlap amplitude calculated with MRSD-CI wave functions. Large, saturated basis sets (199-GTO) were employed for both the high level SCF near Hartree-Fock limit and MRSD-CI calculations to investigate the effects of electron correlation and relaxation. 66 refs., 9 tabs., 9 figs
Metastable decay and binding energies of van der Waals cluster ions
International Nuclear Information System (INIS)
Ernstberger, B.; Krause, H.; Neusser, H.J.
1991-01-01
In this work the appearance potentials for the metastable decay channel of a series of van der Waals dimer ions are presented. Ionization and metastable dissociation is achieved by resonance-enhanced two-photon absorption in a linear reflectron time-of-flight mass spectrometer. From the appearance potentials the binding energy of the neutral dimers is obtained and from the additionally measured ionization potentials binding energies of the dimer cations are achieved. The contribution of charge transfer resonance interaction to the binding in cluster ions is evaluated by investigation of several homo- and heterodimers of aromatic components and the heterodimer benzene/cyclohexane as an example for a dimer consisting of an aromatic and a nonaromatic component. (orig.)
Incremental binding free energies of aluminum (III) vs. magnesium (II) complexes
International Nuclear Information System (INIS)
Mercero, Jose M.; Mujika, Jon I.; Matxain, Jon M.; Lopez, Xabier; Ugalde, Jesus M.
2003-01-01
A sequential ligand addition to the aluminum (III) cation has been studied using the B3LYP functional and a combined all-electron/pseudopotentials basis set. The aluminum complexes are compared with analogous magnesium (II) complexes. Different thermodynamical data, such as incremental binding energies, enthalpies, entropies and free energies, are presented for these addition reactions. While the magnesium (II) cation can only accommodate three negatively charged ligands, aluminum (III) accommodates four even after including bulk solvent effects. The main differences between both cations complexing with the neutral ligands, is that aluminum (III) is not able to form complexes with methanol until the number of methanol ligands is equal to 3. Magnesium (II) prefers to bind methanol and formamide when the number of ligands is small, while aluminum prefers formamide. For the largest complexes both cations prefer to bind water
Core electron binding energy shifts of AlBr3 and Al2Br6 vapor
International Nuclear Information System (INIS)
Mueller, Astrid M.; Plenge, Juergen; Leone, Stephen R.; Canton, Sophie E.; Rude, Bruce S.; Bozek, John D.
2006-01-01
The Al 2p and Br 3d inner-shell photoelectron spectra of aluminum tribromide monomer and dimer vapor were measured at 90 and 95 eV photon energy, respectively, to determine the core electron binding energies of the atoms in the two molecular species. While AlBr 3 has three identical Br atoms, Al 2 Br 6 exhibits four terminal and two bridging Br atoms. The species are identified by their distinct valence photoelectron spectra. Comparison of the observed Al 2p 1/2 and Al 2p 3/2 electron binding energies of AlBr 3 with those of Al 2 Br 6 shows that there is a chemical shift of (0.15 ± 0.03) eV to lower energy in the dimer. In Al 2 Br 6 , an assignment is proposed in which the Br 3d 3/2 and Br 3d 5/2 binding energies of terminal Br atoms are (1.18 ± 0.03) eV lower than those of bridging Br atoms. This assignment assumes that both types of Br atoms have similar cross-sections for ionization. With this result, the Br 3d 3/2 and Br 3d 5/2 binding energies of Br atoms in AlBr 3 are (0.81 ± 0.03) eV lower than those of bridging Br atoms of the dimer but (0.37 ± 0.03) eV higher than those of terminal Br atoms of the dimer. The obtained chemical shifts are considered in terms of the binding relations and electron density distributions in both molecules. Chemical shifts that are larger than a few hundred millielectron volts, as observed in the Al 2 Br 6 /AlBr 3 system, offer potential to study the dissociation dynamics of the dimer in a femtosecond visible or ultraviolet-pump/XUV-probe experiment
The nucleon-air nuclei interaction probability law with rising cross-sections
International Nuclear Information System (INIS)
Portella, H.M.; Oliveira Castro, F.M. de.
1988-01-01
The negative-binomial interaction probability law for nucleon of atmosphere is obtained as a consequence of the respective diffUsion equation. The mean-free path of the nucleon-nucleus interaction rises with the energy of the incident nucleon in the form 1/λ N (E) = (1+aln(E/E 0 ))/λ 0 N , E 0 =1 TeV. In the case of lambda N = constant the distribution law is poissonian. (author) [pt
Hadron-nucleon inelastic collision mean free path in nuclear matter
International Nuclear Information System (INIS)
Strugalski, Z.
1980-01-01
Characteristics of atomic nuclei, used as targets in high energy hadron-nucleus collision experiments, are defined on the basis of the data on the nuclei sizes and radial nucleon density distributions in nuclei. Average mean free path for inelastic hadron-nucleon collisions in nuclei is estimated using existing experimental data on the pion-xenon nucleus collisions and the connection of it with the cross-section for hadron-nucleon elementary inelastic collisions is discussed
Comparison of experimental and theoretical binding and transition energies in the actinide region
International Nuclear Information System (INIS)
Krause, M.O.; Nestor, C.W. Jr.
1977-01-01
The status of experimental and theoretical binding and transition energy determinations is reviewed extending the comparison between experiment and theory to encompass representative series of data for all actinides. This comprehensive comparison reveals areas where improvements may be indicated, showing whether theoretical treatments including all known contributions to the lowest order would be adequate in all instances. 45 references
Analysis of binding energy activity of TIBO and HIV-RT based on ...
African Journals Online (AJOL)
Tetrahydro-imidazo[4,5,l-jk][1,4]-benzodiazepin-2 (1 H)one (TIBO) is a noncompetitive non nucleotide antiretroviral drug with a specific allosteric binding site of HIV-1 RT. The conformational analysis shows that the effect of the drug depends on the potential energy which varied due to the beta rotatable dihedral angles (N6 ...
A test of Wigner's spin-isospin symmetry from double binding energy differences
International Nuclear Information System (INIS)
Van Isacker, P.; Warner, D.D.; Brenner, D.S.
1995-01-01
It is shown that the anomalously large double binding energy differences for even-even N = Z nuclei are a consequence of Wigner's SU(4) symmetry. These, and similar quantities for odd-mass and odd-odd nuclei, provide a simple and distinct signature of this symmetry in N ≅ Z nuclei. (authors). 16 refs., 2 figs., 1 tab
Exciton binding energy in wurtzite InGaN/GaN quantum wells
International Nuclear Information System (INIS)
Park, Seoung-Hwan; Kim, Jong-Jae; Kim, Hwa-Min
2004-01-01
The internal field and carrier density effects on the exciton binding energies in wurtzite (WZ) InGaN/GaN quantum-well (QW) structures are investigated using the multiband effective-mass theory, and are compared with those obtained from the at-band model and with those of GaN/AlGaN QW structures. The exciton binding energy is significantly reduced with increasing sheet carrier density, suggesting that excitons are nearly bleached at densities around 10 12 cm -2 for both InGaN/GaN and GaN/AlGaN QW structures. With the inclusion of the internal field, the exciton binding energy is substantialy reduced compared to that of the at-band model in the investigated region of the wells. This can be explained by a decrease in the momentum matrix element and an increase in the inverse screening length due to the internal field. The exciton binding energy of the InGaN/GaN structure is smaller than that of the GaN/AlGaN structure because InGaN/GaN structures have a smaller momentum matrix element and a larger inverse screening length than GaN/AlGaN structures.
Search for few-nucleon correlations in doubly inclusive processes
International Nuclear Information System (INIS)
Strikman, M.I.; Frankfurt, L.L.
1981-01-01
Earlier work showed that the few-nucleon correlation model is useful in calculation of the inclusive production of cumulative particles at high energies. Certain integrated characteristics of doubly inclusive spectra in high-energy processes are investigated and permit direct information to be obtained on the structure of the correlations. Scattering of a high-energy lepton by a light nucleus with production of a cumulative nucleon is studied, with particular attention to the average transverse momentum of the hadrons recorded, and the doubly inclusive cross section averaged over the transverse momenta of the particles emitted in the forward hemisphere. Expressions are obtained for the integrated cross sections
Relativistic one-boson-exchange model for the nucleon-nucleon interaction
International Nuclear Information System (INIS)
Gross, F.; Van Orden, J.W.; Holinde, K.
1992-01-01
Nucleon-nucleon data below 300-MeV laboratory energy are described by a manifestly covariant wave equation in which one of the intermediate nucleons is restricted to its mass shell. Antisymmetrization of the kernel yields an equation in which the two nucleons are treated in an exactly symmetric manner, and in which all amplitudes satisfy the Pauli principle exactly. The kernel is modeled by the sum of one boson exchanges, and four models, all of which fit the data very well (χ 2 congruent 3 per data point) are discussed. Two models require the exchange of only the π, σ, ρ, and ω, but also require an admixture of γ 5 coupling for the pion, while two other models restrict the pion coupling to pure γ 5 γ μ , but require the exchange of six mesons, including the η, and a light scalar-isovector meson referred to as σ 1 . Deuteron wave functions resulting from these models are obtained. The singularities and relativistic effects which are a part of this approach are discussed, and a complete development of the theory is presented
International Nuclear Information System (INIS)
Goodman, M. C.
1999-01-01
The Soudan 2 detector is used to search for evidence of nucleon decay. Particular emphasis is put on searches for modes with multiple-charged particles in the final state, and for modes suggested by super-symmetric theories
Perspectives of lepton-nucleon scattering
International Nuclear Information System (INIS)
Eisele, F.
1987-01-01
Present day lepton-nucleon scattering experiments will find a continuation at the HERA e-p collider in the near future. HERA experiments will be complementary and in concurrence to other colliders (e/sup +/e/sup -/, p-barp) which will work in a similar energy range at a similar time. HERA has a rewarding unique program of ''standard'' physics. If new physics should show up in the new energy domain, HERA will be an excellent machine to help reveiling its structure. Depending on luck and time scale, HERA offers also the chance of original discoveries in fields where it is unique
A chiral quark model of the nucleon
International Nuclear Information System (INIS)
Wakamatsu, M.; Yoshiki, H.
1991-01-01
The baryon-number-one extended solution of a chiral quark lagrangian is obtained in the stationary-phase approximation with full inclusion of the sea-quark degrees of freedom. The collective quantization method is then applied to this static solution to obtain the nucleon (and Δ) state with the definite spin and isospin. A fundamental quantity appearing in this quantization procedure is the moment of inertia of the soliton system. We evaluate this quantity without recourse to the derivative expansion, by performing the necessary double sum over all the positive- and negative-energy quark orbitals in the mean field potential. Closed formulas are-derived for the nucleon (and Δ) matrix elements of arbitrary quark bilinear operators. These formulas are then used for calculating various nucleon observables in a nonperturbative manner with inclusion of the sea-quark effects. An especially interesting observable is the spin expectation value of the proton related to the recent EMC experiment. We derive the proton spin sum rule, and then explicitly evaluate the detailed contents of this sum rule. The proton spin analysis is shown to be particularly useful for clarifying the underlying dynamical content of the Skyrme model at quark level, thereby providing us with valuable information about its utility and limitation. (orig.)
Nucleon resonance production in electromagnetic interactions
International Nuclear Information System (INIS)
Mukhtarov, A.I.; Sadykhov, F.S.; Vasil'ev, O.A.; Abdullaev, S.K.; Mustafaev, V.Z.
1977-01-01
The results of investigation into nucleon resonance production (NR) in the ep → eNsup(*)(eNsup(*)γ) and eantie → antipNsup(*)(antipNsup(*)γ) processes, where Nsup(*) is a nucleon resonance of the 3/2 or 5/2 spin are presented. The calculation of the NR structure functions with the mass M and 3/2 or 5/2 spin is carried out. The Δ(1236), N(1688) and Δ(2160) NR production was observed in the ep → eNsup(*) and eantie → antipNsup(*) processes. For the ep-interaction the energy dependence of the NR production differential cross section at the electron scattering angle THETA = 6 dea and the angular dependence of the longitudinal polarization degree of the scattered electrons at the electron energy of 6 GeV are presented. The energy dependence of the total cross section of the NR production for eantie → antipNsup(*) is obtained. The ep → eNsup(*)γ radiative electron scattering on a proton is investigated only in case of the Δ(1236)NR production. The dependence of the effective cross section of the Δ(1236) radiative production process on THETA for the energies of an incident and scattered electron of 6 and 2.5 GeV, respectively, and the dependence of the cross section on the scattered electron energy at the initial energy of 6 GeV and THETA = 15 deg are presented
Towards accurate free energy calculations in ligand protein-binding studies.
Steinbrecher, Thomas; Labahn, Andreas
2010-01-01
Cells contain a multitude of different chemical reaction paths running simultaneously and quite independently next to each other. This amazing feat is enabled by molecular recognition, the ability of biomolecules to form stable and specific complexes with each other and with their substrates. A better understanding of this process, i.e. of the kinetics, structures and thermodynamic properties of biomolecule binding, would be invaluable in the study of biological systems. In addition, as the mode of action of many pharmaceuticals is based upon their inhibition or activation of biomolecule targets, predictive models of small molecule receptor binding are very helpful tools in rational drug design. Since the goal here is normally to design a new compound with a high inhibition strength, one of the most important thermodynamic properties is the binding free energy DeltaG(0). The prediction of binding constants has always been one of the major goals in the field of computational chemistry, because the ability to reliably assess a hypothetical compound's binding properties without having to synthesize it first would save a tremendous amount of work. The different approaches to this question range from fast and simple empirical descriptor methods to elaborate simulation protocols aimed at putting the computation of free energies onto a solid foundation of statistical thermodynamics. While the later methods are still not suited for the screenings of thousands of compounds that are routinely performed in computational drug design studies, they are increasingly put to use for the detailed study of protein ligand interactions. This review will focus on molecular mechanics force field based free energy calculations and their application to the study of protein ligand interactions. After a brief overview of other popular methods for the calculation of free energies, we will describe recent advances in methodology and a variety of exemplary studies of molecular dynamics
Fox, Stephen J; Pittock, Chris; Tautermann, Christofer S; Fox, Thomas; Christ, Clara; Malcolm, N O J; Essex, Jonathan W; Skylaris, Chris-Kriton
2013-08-15
Schemes of increasing sophistication for obtaining free energies of binding have been developed over the years, where configurational sampling is used to include the all-important entropic contributions to the free energies. However, the quality of the results will also depend on the accuracy with which the intermolecular interactions are computed at each molecular configuration. In this context, the energy change associated with the rearrangement of electrons (electronic polarization and charge transfer) upon binding is a very important effect. Classical molecular mechanics force fields do not take this effect into account explicitly, and polarizable force fields and semiempirical quantum or hybrid quantum-classical (QM/MM) calculations are increasingly employed (at higher computational cost) to compute intermolecular interactions in free-energy schemes. In this work, we investigate the use of large-scale quantum mechanical calculations from first-principles as a way of fully taking into account electronic effects in free-energy calculations. We employ a one-step free-energy perturbation (FEP) scheme from a molecular mechanical (MM) potential to a quantum mechanical (QM) potential as a correction to thermodynamic integration calculations within the MM potential. We use this approach to calculate relative free energies of hydration of small aromatic molecules. Our quantum calculations are performed on multiple configurations from classical molecular dynamics simulations. The quantum energy of each configuration is obtained from density functional theory calculations with a near-complete psinc basis set on over 600 atoms using the ONETEP program.
Hard breakup of two nucleons from the 3He nucleus
International Nuclear Information System (INIS)
Sargsian, Misak M.; Granados, Carlos
2009-01-01
We investigate a large angle photodisintegration of two nucleons from the 3 He nucleus within the framework of the hard rescattering model (HRM). In the HRM a quark of one nucleon knocked out by an incoming photon rescatters with a quark of the other nucleon leading to the production of two nucleons with large relative momentum. Assuming the dominance of the quark-interchange mechanism in a hard nucleon-nucleon scattering, the HRM allows the expression of the amplitude of a two-nucleon breakup reaction through the convolution of photon-quark scattering, NN hard scattering amplitude, and nuclear spectral function, which can be calculated using a nonrelativistic 3 He wave function. The photon-quark scattering amplitude can be explicitly calculated in the high energy regime, whereas for NN scattering one uses the fit of the available experimental data. The HRM predicts several specific features for the hard breakup reaction. First, the cross section will approximately scale as s -11 . Second, the s 11 weighted cross section will have the shape of energy dependence similar to that of s 10 weighted NN elastic scattering cross section. Also one predicts an enhancement of the pp breakup relative to the pn breakup cross section as compared to the results from low energy kinematics. Another result is the prediction of different spectator momentum dependencies of pp and pn breakup cross sections. This is due to the fact that the same-helicity pp-component is strongly suppressed in the ground state wave function of 3 He. Because of this suppression the HRM predicts significantly different asymmetries for the cross section of polarization transfer NN breakup reactions for circularly polarized photons. For the pp breakup this asymmetry is predicted to be zero while for the pn it is close to (2/3).
Cooper-pair size and binding energy for unconventional superconducting systems
Dinóla Neto, F.; Neto, Minos A.; Salmon, Octavio D. Rodriguez
2018-06-01
The main proposal of this paper is to analyze the size of the Cooper pairs composed by unbalanced mass fermions from different electronic bands along the BCS-BEC crossover and study the binding energy of the pairs. We are considering an interaction between fermions with different masses leading to an inter-band pairing. In addiction to the attractive interaction we have an hybridization term to couple both bands, which in general acts unfavorable for the pairing between the electrons. We get first order phase transitions as the hybridization breaks the Cooper pairs for the s-wave symmetry of the gap amplitude. The results show the dependence of the Cooper-pair size as a function of the hybridization for T = 0 . We also propose the structure of the binding energy of the inter-band system as a function of the two-bands quasi-particle energies.
Olsson, Martin A; Söderhjelm, Pär; Ryde, Ulf
2016-06-30
In this article, the convergence of quantum mechanical (QM) free-energy simulations based on molecular dynamics simulations at the molecular mechanics (MM) level has been investigated. We have estimated relative free energies for the binding of nine cyclic carboxylate ligands to the octa-acid deep-cavity host, including the host, the ligand, and all water molecules within 4.5 Å of the ligand in the QM calculations (158-224 atoms). We use single-step exponential averaging (ssEA) and the non-Boltzmann Bennett acceptance ratio (NBB) methods to estimate QM/MM free energy with the semi-empirical PM6-DH2X method, both based on interaction energies. We show that ssEA with cumulant expansion gives a better convergence and uses half as many QM calculations as NBB, although the two methods give consistent results. With 720,000 QM calculations per transformation, QM/MM free-energy estimates with a precision of 1 kJ/mol can be obtained for all eight relative energies with ssEA, showing that this approach can be used to calculate converged QM/MM binding free energies for realistic systems and large QM partitions. © 2016 The Authors. Journal of Computational Chemistry Published by Wiley Periodicals, Inc. © 2016 The Authors. Journal of Computational Chemistry Published by Wiley Periodicals, Inc.
Olsson, Martin A.; Söderhjelm, Pär
2016-01-01
In this article, the convergence of quantum mechanical (QM) free‐energy simulations based on molecular dynamics simulations at the molecular mechanics (MM) level has been investigated. We have estimated relative free energies for the binding of nine cyclic carboxylate ligands to the octa‐acid deep‐cavity host, including the host, the ligand, and all water molecules within 4.5 Å of the ligand in the QM calculations (158–224 atoms). We use single‐step exponential averaging (ssEA) and the non‐Boltzmann Bennett acceptance ratio (NBB) methods to estimate QM/MM free energy with the semi‐empirical PM6‐DH2X method, both based on interaction energies. We show that ssEA with cumulant expansion gives a better convergence and uses half as many QM calculations as NBB, although the two methods give consistent results. With 720,000 QM calculations per transformation, QM/MM free‐energy estimates with a precision of 1 kJ/mol can be obtained for all eight relative energies with ssEA, showing that this approach can be used to calculate converged QM/MM binding free energies for realistic systems and large QM partitions. © 2016 The Authors. Journal of Computational Chemistry Published by Wiley Periodicals, Inc. PMID:27117350
Multi-nucleon transfer: a probe to investigate the reaction mechanism around the barrier
International Nuclear Information System (INIS)
Mandal, Samit K.
2014-01-01
The investigation of multi-nucleon transfer mechanism offers valuable information on the pairing interactions that enhance the transfer of nucleon pairs across heavy ions involved in the reaction. These reactions are also a useful tool to study exotic nuclei far from the stability line, which can be explored with the new generation radioactive beam facility. In this talk, multi-nucleon transfer reaction mechanisms between heavy ions and their effect on the reaction dynamics around the coulomb barrier energies have been discussed. Experimental results will be presented with a semi classical description of multi nucleon transfer reaction calculation. One and two nucleon transfer cross sections reproduced using a quantum mechanical coupled channel calculations will also be discussed. A feasibility of investigation of multi-nucleon transfer mechanism to explore the pairing correlation at moderate spin states with radioactive beams will be discussed. (author)
Pion–nucleon scattering: from chiral perturbation theory to Roy–Steiner equations
International Nuclear Information System (INIS)
Kubis, Bastian; Hoferichter, Martin; Elvira, Jacobo Ruiz de; Meißner, Ulf-G.
2016-01-01
Ever since Weinberg’s seminal predictions of the pion–nucleon scattering amplitudes at threshold, this process has been of central interest for the study of chiral dynamics involving nucleons. The scattering lengths or the pion–nucleon σ-term are fundamental quantities characterizing the explicit breaking of chiral symmetry by means of the light quark masses. On the other hand, pion–nucleon dynamics also strongly affects the long-range part of nucleon–nucleon potentials, and hence has a far-reaching impact on nuclear physics. We discuss the fruitful combination of dispersion-theoretical methods, in the form of Roy–Steiner equations, with chiral dynamics to determine pion–nucleon scattering amplitudes at low energies with high precision.
Attractive component in the nucleon-nucleon interaction in the Skyrme model
International Nuclear Information System (INIS)
Nyman, E.M.; Riska, D.O.
1986-01-01
The spin- and isospin-independent part of the nulceon-nucleon interaction in the Skyrme model is shown to contain a weak attractive intermediate-range term in addition to the well-known short-range repulsion. The attraction is a consequence of the rotational degree of freedom of a skyrmion in the presence of the field of another one, and can be thought of as an enhancement of the moment of inertia of each skyrmion. While the attractive term is dominant at large distances it is not sufficiently strong for nuclear binding. (orig.)
Motornenko, A.; Bravina, L.; Gorenstein, M. I.; Magner, A. G.; Zabrodin, E.
2018-03-01
Properties of equilibrated nucleon system are studied within the ultra-relativistic quantum molecular dynamics (UrQMD) transport model. The UrQMD calculations are done within a finite box with periodic boundary conditions. The system achieves thermal equilibrium due to nucleon-nucleon elastic scattering. For the UrQMD-equilibrium state, nucleon energy spectra, equation of state, particle number fluctuations, and shear viscosity η are calculated. The UrQMD results are compared with both, statistical mechanics and Chapman-Enskog kinetic theory, for a classical system of nucleons with hard-core repulsion.
Binding Energy and Lifetime of Excitons in InxGa1-xAs/GaAs Quantum Wells
DEFF Research Database (Denmark)
Orani, D.; Polimeni, A.; Patane, A.
1997-01-01
We report a systematic study of exciton binding energies and lifetimes in InGaAs/GaAs quantum wells. The experimental binding energies have been deduced from photoluminescence excitation measurements taking into account the contribution of the 2s state of the exciton and the line broadening...
Energy Technology Data Exchange (ETDEWEB)
Bensafa, I.K
2006-05-15
The first part of this work presents the analysis and results of the VCS-SSA (virtual Compton scattering - single spin asymmetry) experiment at MAMI (Mainz). It was carried out with beam energy 883 MeV and longitudinal polarization (about 80%), at virtual photon four-momentum transfer squared (Q{sup 2} = 0.35 GeV{sup 2}) to measure the beam asymmetry in the ep {yields} ep{gamma} and ep {yields} ep{pi}{sup 0} reactions. The asymmetry obtained in photon (resp. pion) electro-production is between 0-15% (resp. 0-2%). The dispersion relation model for virtual Compton scattering and MAID model (for {pi}{sup 0}) reproduce the amplitude globally but not completely the shape of the asymmetry. Perhaps this discrepancy is due to an imperfect parameterization of some pion production multipoles ({gamma}{sup *}N {yields} {pi}N). The second part is dedicated to the study of the nucleon energy spectrum in ground-state L=0 and excited-state L=1 in the quark model, using the Coulomb + linear potential type (CL) and a relativistic correction. The hyperfine correction is applied to discriminate the nucleon masses. The values of the mass found for the proton and the {delta}(1232) are respectively equal to (968 MeV, 1168 MeV), and the masses of the excited states are between 1564 - 1607 MeV. This part is completed by an application of the CL model to an approximate calculation of generalized polarizabilities of the proton. (author)
Numerical Exact Ab Initio Four-Nucleon Scattering Calculations: from Dream to Reality
Fonseca, A. C.; Deltuva, A.
2017-03-01
In the present manuscript we review the work of the last ten years on the pursuit to obtain numerical exact solutions of the four-nucleon scattering problem using the most advanced force models that fit two nucleon data up to pion production threshold with a χ ^2 per data point approximately one, together with the Coulomb interaction between protons; three- and four-nucleon forces are also included in the framework of a meson exchange potential model where NN couples to NΔ. Failure to describe the world data on four-nucleon scattering observables in the framework of a non relativistic scattering approach falls necessarily on the force models one uses. Four-nucleon observables pose very clear challenges, particular in the low energy region where there are a number of resonances whose position and width needs to be dynamically generated by the nucleon-nucleon (NN) interactions one uses. In addition, our calculations constitute the most advance piece of work where observables for all four-nucleon reactions involving isospin I=0, I=0 coupled to I=1 and isospin I=1 initial states are calculated at energies both below and above breakup threshold. We also present a very extensive comparison between calculated results and data for cross sections and spin observables. Therefore the present work reveals both the shortcomings and successes of some of the present NN force models in describing four-nucleon data and serve as a benchmark for future developments.
pp Elastic Scattering at LHC and Nucleon Structure
Islam, M M; Prokudin, A V
2003-01-01
High energy elastic pp differential cross section at LHC at the c.m. energy 14 TeV is predicted using the asymptotic behavior of tot(s) and (s), and the measured p differential cross section at =546 GeV. The phenomenological investigation has progressively led to an effective field theory model that describes the nucleon as a chiral bag embedded in a quark-antiquark condensed ground state. The measurement of pp elastic scattering at LHC up to large |t| 10 GeV2 by the TOTEM group will be crucial to test this structure of the nucleon.
$pp$ Elastic Scattering at LHC and Nucleon Structure
Islam, M M; Prokudin, A V
2003-01-01
High energy elastic pp differential cross section at LHC at the c.m. energy 14 TeV is predicted using the asymptotic behavior of sigma-tot(s) and rho(s), and the measured pbar-p differential cross section at sqrt{s}=546 GeV. The phenomenological investigation has progressively led to an effective field theory model that describes the nucleon as a chiral bag embedded in a quark-antiquark condensed ground state. The measurement of pp elastic scattering at LHC up to large |t| >~ 10 GeV^2 by the TOTEM group will be crucial to test this structure of the nucleon.
International Nuclear Information System (INIS)
Elhage, H.
1992-10-01
We have studied the reaction of 40 Ca with nat Cu at 35 MeV/nucleon with the AMPHORA multidetector. Three different reaction models were developed and we have shown that a simulation of the AMPHORA response is necessary to interpret the experimental results. Only two-body events were analyzed. Kinematic selection criterions, based on relative velocity, were used in order to isolate particles and residues coming from the de-excitation of the projectile-like fragment. The reconstitution of such a nucleus allowed to define the reaction plane and to calculate the energy balance event-by-event. We have proposed a method to determine the angular momentum based on the emission asymmetry of the light particles with respect to the normal to the reaction plane. The estimated angular momenta are in good agreement with the theoretical predictions. The projectile-like fragment temperature was estimated from the energy spectra of the light particles. The independent determination of the excitation energy, temperature and angular momentum allowed to calculate the level density parameter. This quantity does not evolve with the excitation energy and is equal to A/8. The projectile-like fragment de-excitation mode is mainly evaporation
Ciofi degli Atti, Claudio; Morita, Hiko
2017-12-01
Background: The nuclear spectral function is a fundamental quantity that describes the mean-field and short-range correlation dynamics of nucleons embedded in the nuclear medium; its knowledge is a prerequisite for the interpretation of various electroweak scattering processes off nuclear targets aimed at providing fundamental information on strong and weak interactions. Whereas in the case of the three-nucleon and, partly, the four-nucleon systems, the spectral function can be calculated ab initio within a nonrelativistic many-body Schroedinger approach, in the case of complex nuclei only models of the correlated, high-momentum part of the spectral function are available so far. Purpose: The purpose of this paper is to present a new approach such that the spectral function for a specific nucleus can be obtained from a reliable many-body calculation based upon realistic nucleon-nucleon interactions, thus avoiding approximations leading to adjustable parameters. Methods: The expectation value of the nuclear many-body Hamiltonian, containing realistic nucleon-nucleon interaction of the Argonne family, is evaluated variationally by a normalization-conserving linked-cluster expansion and the resulting many-body correlated wave functions are used to calculate the one-nucleon and the two-nucleon momentum distributions; by analyzing the high-momentum behavior of the latter, the spectral function can be expressed in terms of a transparent convolution formula involving the relative and center-of-mass (c.m.) momentum distributions in specific regions of removal energy E and momentum k . Results: It is found that as a consequence of the factorization of the many-body wave functions at short internucleon separations, the high-momentum behavior of the two-nucleon momentum distributions in A =3 ,4 ,12 ,16 ,40 nuclei factorizes, at proper values of the relative and c.m. momenta, into the c.m. and relative momentum distributions, with the latter exhibiting a universal A
Nascimento, Érica C M; Oliva, Mónica; Andrés, Juan
2018-05-01
In the present study, the binding free energy of a family of huprines with acetylcholinesterase (AChE) is calculated by means of the free energy perturbation method, based on hybrid quantum mechanics and molecular mechanics potentials. Binding free energy calculations and the analysis of the geometrical parameters highlight the importance of the stereochemistry of huprines in AChE inhibition. Binding isotope effects are calculated to unravel the interactions between ligands and the gorge of AChE. New chemical insights are provided to explain and rationalize the experimental results. A good correlation with the experimental data is found for a family of inhibitors with moderate differences in the enzyme affinity. The analysis of the geometrical parameters and interaction energy per residue reveals that Asp72, Glu199, and His440 contribute significantly to the network of interactions between active site residues, which stabilize the inhibitors in the gorge. It seems that a cooperative effect of the residues of the gorge determines the affinity of the enzyme for these inhibitors, where Asp72, Glu199, and His440 make a prominent contribution.