Pub Date : 1990-12-01DOI: 10.1051/JPHYS:0199000510240274700
J. Bystrický, C. Lechanoine-Leluc, F. Lehár
Fixed energy phase shift analyses have been carried out at eight energies between 0.83 and 1.8 GeV for elastic pp scattering. At these energies complete sets of observables have been measured at SATURNE II. The energy dependences of the phase shifts are compared with other recent analyses. The predictions of the forward scattering amplitudes are compared with dispersion relation calculations. The angular dependence of the 5 total scattering amplitudes is in good agreement with results of the direct amplitude reconstruction Une analyse en dephasage a energie fixe, pour la diffusion elastique pp, a ete realisee a huit energies entre 0.84 et 1.8 GeV. A chacune de ces energies, un ensemble complet d'observables a ete mesure a SATURNE II. La dependance en energie obtenue pour les differents dephasages est comparee a celle obtenue par d'autres analyses en dephasages recentes. Les resultats obtenus pour les amplitudes de diffusion a 0 o sont compares a ceux bases sur les relations de dispersion. La dependance angulaire des 5 amplitudes de diffusion est en bon accord avec celle obtenue par reconstruction directe
{"title":"Phase shift analyses of pp elastic scattering at fixed energies between 0.83 and 1.8 GeV","authors":"J. Bystrický, C. Lechanoine-Leluc, F. Lehár","doi":"10.1051/JPHYS:0199000510240274700","DOIUrl":"https://doi.org/10.1051/JPHYS:0199000510240274700","url":null,"abstract":"Fixed energy phase shift analyses have been carried out at eight energies between 0.83 and 1.8 GeV for elastic pp scattering. At these energies complete sets of observables have been measured at SATURNE II. The energy dependences of the phase shifts are compared with other recent analyses. The predictions of the forward scattering amplitudes are compared with dispersion relation calculations. The angular dependence of the 5 total scattering amplitudes is in good agreement with results of the direct amplitude reconstruction Une analyse en dephasage a energie fixe, pour la diffusion elastique pp, a ete realisee a huit energies entre 0.84 et 1.8 GeV. A chacune de ces energies, un ensemble complet d'observables a ete mesure a SATURNE II. La dependance en energie obtenue pour les differents dephasages est comparee a celle obtenue par d'autres analyses en dephasages recentes. Les resultats obtenus pour les amplitudes de diffusion a 0 o sont compares a ceux bases sur les relations de dispersion. La dependance angulaire des 5 amplitudes de diffusion est en bon accord avec celle obtenue par reconstruction directe","PeriodicalId":14747,"journal":{"name":"Journal De Physique","volume":"42 1","pages":"2747-2776"},"PeriodicalIF":0.0,"publicationDate":"1990-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78706328","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1990-12-01DOI: 10.1051/JPHYS:0199000510230264100
A. Baumgärtner, W. Renz
The competition between adsorption and entropic repulsion of a single self-avoiding polymer trapped in quenched media consisting of parallel, adsorbing rods distributed at random in the perpendicular plane are studied by simulations and analytical arguments. The chain undergoes an adsorption transition at finite temperature which is not observed in a regular medium. Below and above the transition temperature, the chain is essentially stretched parallel to the rods and shrunk in lateral directions with exponents ν ⊥ =0, v ∥ =1 for the corresponding components of the radius of gyration. These phenomena are based on two different mechanisms, localization by adsorption at low temperatures and localization by entropic repulsion at high temperatures. The present model is the first where the entropic localization occurs at arbitrary strength of self-avoidance. Analytical arguments suggest, in agreement with our data, that the chain obeys approximately conventional self-avoiding behavior at the critical adsorption temperature. We expect that both phenomena, disorder induced adsorption and entropic localization, can be tested experimentally
{"title":"Disorder induced adsorption of polymers","authors":"A. Baumgärtner, W. Renz","doi":"10.1051/JPHYS:0199000510230264100","DOIUrl":"https://doi.org/10.1051/JPHYS:0199000510230264100","url":null,"abstract":"The competition between adsorption and entropic repulsion of a single self-avoiding polymer trapped in quenched media consisting of parallel, adsorbing rods distributed at random in the perpendicular plane are studied by simulations and analytical arguments. The chain undergoes an adsorption transition at finite temperature which is not observed in a regular medium. Below and above the transition temperature, the chain is essentially stretched parallel to the rods and shrunk in lateral directions with exponents ν ⊥ =0, v ∥ =1 for the corresponding components of the radius of gyration. These phenomena are based on two different mechanisms, localization by adsorption at low temperatures and localization by entropic repulsion at high temperatures. The present model is the first where the entropic localization occurs at arbitrary strength of self-avoidance. Analytical arguments suggest, in agreement with our data, that the chain obeys approximately conventional self-avoiding behavior at the critical adsorption temperature. We expect that both phenomena, disorder induced adsorption and entropic localization, can be tested experimentally","PeriodicalId":14747,"journal":{"name":"Journal De Physique","volume":"30 1","pages":"2641-2651"},"PeriodicalIF":0.0,"publicationDate":"1990-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80489127","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1990-12-01DOI: 10.1051/JPHYS:0199000510230271700
V. Dmitrienko
2014 The regular deviations from the exact icosahedral symmetry, usually observed at the diffraction patterns of quasicrystal alloys, are analyzed. It is shown that shifting, splitting and asymmetric broadening of reflections can be attributed to crystalline phases with the cubic symmetry very close to the icosahedral one (such pseudo-icosahedral cubic approximants may be called the Fibonacci crystals). The Fibonacci crystal is labelled as Fn+1/Fn>, if in this crystal the most intense vertex reflections have the Miller indices {0, Fn, Fn + 1} where Fi are the Fibonacci numbers (Fi = 1, 1, 2, 3, 5, 8, 13, 21, 34...). The deviations of x-ray and electron reflections from their icosahedral positions are calculated. The comparison with available experimental data shows that at least four different Fibonacci crystals have been observed in Al-Mn and Al-Mn-Si alloys : 2/1> (MnSi structure), 5/3> (03B1-Al-Mn-Si), 13/8>, and 34/21> with the lattice constants 4.6 Å, 12.6 Å, 33.1 Å, 86.6 Å respectively. It is interesting to note that there are no experimental evidences for the intermediate approximants 3/2>, 8/5> and 21/13>. The possible space groups of the Fibonacci crystals and their relationships with quasicrystallographic space groups are discussed. J. Phys. France 51 ( 1990) 2717-2732 1 er DÉCEMBRE 1990,
{"title":"Cubic approximants in quasicrystal structures","authors":"V. Dmitrienko","doi":"10.1051/JPHYS:0199000510230271700","DOIUrl":"https://doi.org/10.1051/JPHYS:0199000510230271700","url":null,"abstract":"2014 The regular deviations from the exact icosahedral symmetry, usually observed at the diffraction patterns of quasicrystal alloys, are analyzed. It is shown that shifting, splitting and asymmetric broadening of reflections can be attributed to crystalline phases with the cubic symmetry very close to the icosahedral one (such pseudo-icosahedral cubic approximants may be called the Fibonacci crystals). The Fibonacci crystal is labelled as Fn+1/Fn>, if in this crystal the most intense vertex reflections have the Miller indices {0, Fn, Fn + 1} where Fi are the Fibonacci numbers (Fi = 1, 1, 2, 3, 5, 8, 13, 21, 34...). The deviations of x-ray and electron reflections from their icosahedral positions are calculated. The comparison with available experimental data shows that at least four different Fibonacci crystals have been observed in Al-Mn and Al-Mn-Si alloys : 2/1> (MnSi structure), 5/3> (03B1-Al-Mn-Si), 13/8>, and 34/21> with the lattice constants 4.6 Å, 12.6 Å, 33.1 Å, 86.6 Å respectively. It is interesting to note that there are no experimental evidences for the intermediate approximants 3/2>, 8/5> and 21/13>. The possible space groups of the Fibonacci crystals and their relationships with quasicrystallographic space groups are discussed. J. Phys. France 51 ( 1990) 2717-2732 1 er DÉCEMBRE 1990,","PeriodicalId":14747,"journal":{"name":"Journal De Physique","volume":"43 1","pages":"2717-2732"},"PeriodicalIF":0.0,"publicationDate":"1990-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89907504","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1990-12-01DOI: 10.1051/JPHYS:0199000510240277700
J. Chardon, C. Genty, J. Labrune
Nous presentons une methode spectroscopique par impulsions en resonance electrique sur des jets moleculaires (spectroscopie MBER). Cette methode consiste a irradier le jet dans la zone de resonance par des impulsions etroites et periodiques. Dans les experiences decrites, realisees sur un jet de formaldehyde H 2 CO, les impulsions sont rectangulaires, de periode T
{"title":"Spectroscopie par impulsions périodiques sur un jet moléculaire. probabilité de transition. Effets de résonance","authors":"J. Chardon, C. Genty, J. Labrune","doi":"10.1051/JPHYS:0199000510240277700","DOIUrl":"https://doi.org/10.1051/JPHYS:0199000510240277700","url":null,"abstract":"Nous presentons une methode spectroscopique par impulsions en resonance electrique sur des jets moleculaires (spectroscopie MBER). Cette methode consiste a irradier le jet dans la zone de resonance par des impulsions etroites et periodiques. Dans les experiences decrites, realisees sur un jet de formaldehyde H 2 CO, les impulsions sont rectangulaires, de periode T","PeriodicalId":14747,"journal":{"name":"Journal De Physique","volume":"25 1","pages":"2777-2790"},"PeriodicalIF":0.0,"publicationDate":"1990-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77694929","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1990-12-01DOI: 10.1051/JPHYS:0199000510240274300
M. Uwaha
Hydrodynamic interaction of steps is considered. Origin of the interaction is interference of superfluid flow associated with the step oscillation. We calculate contribution of the step oscillation to the surface free energy at high temperatures, and find that the interaction is repulsive and inversely proportional to the step distance
{"title":"Possible long-range step interaction in 4He due to step oscillation","authors":"M. Uwaha","doi":"10.1051/JPHYS:0199000510240274300","DOIUrl":"https://doi.org/10.1051/JPHYS:0199000510240274300","url":null,"abstract":"Hydrodynamic interaction of steps is considered. Origin of the interaction is interference of superfluid flow associated with the step oscillation. We calculate contribution of the step oscillation to the surface free energy at high temperatures, and find that the interaction is repulsive and inversely proportional to the step distance","PeriodicalId":14747,"journal":{"name":"Journal De Physique","volume":"32 1","pages":"2743-2746"},"PeriodicalIF":0.0,"publicationDate":"1990-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77273970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1990-12-01DOI: 10.1051/JPHYS:0199000510240280100
G. Coulon, B. Collin, D. Ausserré, D. Chatenay, T. Russell
Les copolymeres diblocs symetriques polystyrene/polymethylmethacrylate deposes sur un substrat de silicium, forment a l'equilibre thermodynamique, une structure multicouche parallele au substrat. Si la couche superieure est incomplete, des ilots ou des trous se forment dans celle-ci. Leur cinetique de formation et de croissance est etudiee par microscopie interferometrique in situ. Seuls les systemes denses (≃30% d'ilots ou de trous en taux de couverture) sont envisages. Aux temps courts, la formation des ilots est differente de celle des trous. Aux temps longs, la croissance des ilots et des trous est controlee par les memes mecanismes: croissance individuelle, coalescence et disparition
{"title":"Islands and holes on the free surface of thin diblock copolymer films. I. Characteristics of formation and growth","authors":"G. Coulon, B. Collin, D. Ausserré, D. Chatenay, T. Russell","doi":"10.1051/JPHYS:0199000510240280100","DOIUrl":"https://doi.org/10.1051/JPHYS:0199000510240280100","url":null,"abstract":"Les copolymeres diblocs symetriques polystyrene/polymethylmethacrylate deposes sur un substrat de silicium, forment a l'equilibre thermodynamique, une structure multicouche parallele au substrat. Si la couche superieure est incomplete, des ilots ou des trous se forment dans celle-ci. Leur cinetique de formation et de croissance est etudiee par microscopie interferometrique in situ. Seuls les systemes denses (≃30% d'ilots ou de trous en taux de couverture) sont envisages. Aux temps courts, la formation des ilots est differente de celle des trous. Aux temps longs, la croissance des ilots et des trous est controlee par les memes mecanismes: croissance individuelle, coalescence et disparition","PeriodicalId":14747,"journal":{"name":"Journal De Physique","volume":"19 1","pages":"2801-2811"},"PeriodicalIF":0.0,"publicationDate":"1990-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78285518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1990-12-01DOI: 10.1051/JPHYS:0199000510240279100
M. Defranceschi, G. Berthier
Atomic and molecular symmetry properties for the wave functions and electronic densities in position and momentum spaces are compared. A systematic study of the correspondance of point groups in both spaces is made and examples of experiments of (e, 2e) spectroscopy performed on atoms or molecules are compiled. Simple guidelines for interpreting electron distribution patterns are presented which enable one to sketch the nuclear geometry from the knowledge of momentum maps and Fourier transform effects
{"title":"Symmetry properties in position and momentum space","authors":"M. Defranceschi, G. Berthier","doi":"10.1051/JPHYS:0199000510240279100","DOIUrl":"https://doi.org/10.1051/JPHYS:0199000510240279100","url":null,"abstract":"Atomic and molecular symmetry properties for the wave functions and electronic densities in position and momentum spaces are compared. A systematic study of the correspondance of point groups in both spaces is made and examples of experiments of (e, 2e) spectroscopy performed on atoms or molecules are compiled. Simple guidelines for interpreting electron distribution patterns are presented which enable one to sketch the nuclear geometry from the knowledge of momentum maps and Fourier transform effects","PeriodicalId":14747,"journal":{"name":"Journal De Physique","volume":"21 1","pages":"2791-2800"},"PeriodicalIF":0.0,"publicationDate":"1990-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83701736","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1990-12-01DOI: 10.1051/JPHYS:0199000510240284300
M. Daoud
{"title":"DYNAMICS OF DILUTE SOLUTIONS OF RANDOMLY BRANCHED POLYMERS","authors":"M. Daoud","doi":"10.1051/JPHYS:0199000510240284300","DOIUrl":"https://doi.org/10.1051/JPHYS:0199000510240284300","url":null,"abstract":"","PeriodicalId":14747,"journal":{"name":"Journal De Physique","volume":"41 1","pages":"2843-2853"},"PeriodicalIF":0.0,"publicationDate":"1990-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90755059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1990-12-01DOI: 10.1051/JPHYS:0199000510230268100
D. Chowdhury
We investigate the law of domain growth in strongly disordered Ising magnets in two dimensions by Monte Carlo simulation. The average linear domain size is found to grow with time t as R(t) ~ (In t)x. For all the concentrations of the impurities used in our simulations the numerical value of the exponent x is found to be smaller than the corresponding theoretical prediction thereby indicating the possibility that the asymptotic regime, where the theory may hold, lies beyond the time scale of our observation. Nevertheless, in contrast to the recent laboratory experiment of Ikeda et al., the effective exponents are found to exhibit at least a kind of « quasi-universality » (temperature-independence) provided the Monte Carlo data for the domain size at a given impurity concentration are fitted to the form (In t) x over the same time interval consistently at all temperatures.
本文用蒙特卡罗模拟方法研究了强无序伊辛磁体的二维畴生长规律。平均线性畴大小随着时间的增加而增大，为R(t) ~ (In t)x。对于我们模拟中使用的所有杂质浓度，指数x的数值被发现小于相应的理论预测，从而表明理论可能成立的渐近状态可能超出了我们观察的时间尺度。然而，与Ikeda等人最近的实验室实验相反，如果给定杂质浓度下的畴大小的蒙特卡罗数据在所有温度下一致地拟合为(int) x的形式，则发现有效指数至少表现出一种“准普适”(温度无关)。
{"title":"Domain growth kinetics in strongly disordered Ising magnets","authors":"D. Chowdhury","doi":"10.1051/JPHYS:0199000510230268100","DOIUrl":"https://doi.org/10.1051/JPHYS:0199000510230268100","url":null,"abstract":"We investigate the law of domain growth in strongly disordered Ising magnets in two dimensions by Monte Carlo simulation. The average linear domain size is found to grow with time t as R(t) ~ (In t)x. For all the concentrations of the impurities used in our simulations the numerical value of the exponent x is found to be smaller than the corresponding theoretical prediction thereby indicating the possibility that the asymptotic regime, where the theory may hold, lies beyond the time scale of our observation. Nevertheless, in contrast to the recent laboratory experiment of Ikeda et al., the effective exponents are found to exhibit at least a kind of « quasi-universality » (temperature-independence) provided the Monte Carlo data for the domain size at a given impurity concentration are fitted to the form (In t) x over the same time interval consistently at all temperatures.","PeriodicalId":14747,"journal":{"name":"Journal De Physique","volume":"13 1","pages":"2681-2687"},"PeriodicalIF":0.0,"publicationDate":"1990-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79247985","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1990-12-01DOI: 10.1051/JPHYS:0199000510240282900
G. Grest, K. Kremer
The critical behavior at the percolation threshold for a randomly crosslinked polymer melt of linear chains is studied by computer simulations. We show that the fraction of crosslinks per chain pc at the vulcanization/percolation threshold is independent of chain length N for large N. Thus for long chains, the volume fraction of crosslinks at the transition decreases as 1/N in agreement with Flory. If we allow linkages only between different chains and no self-linkages, we find that pc ∼ 0.6 in the limit of large N. This value in 20 % larger than Flory's mean field result, pc = 1/2, as some of the crosslinks do not increase the number of chains in a cluster. When we allow intra-chain linkages as they occur experimentally, the scaling with N remains unchanged but pc increases by an addition 20 % for the present model. We also find in agreement with de Gennes that the critical exponents are well described by their mean field values and that the size of the critical region where fluctuations are important is small for long polymer chains. The fractal dimension of the percolating cluster at pc was found to be 3.
{"title":"CRITICAL PROPERTIES OF CROSSLINKED POLYMER MELTS","authors":"G. Grest, K. Kremer","doi":"10.1051/JPHYS:0199000510240282900","DOIUrl":"https://doi.org/10.1051/JPHYS:0199000510240282900","url":null,"abstract":"The critical behavior at the percolation threshold for a randomly crosslinked polymer melt of linear chains is studied by computer simulations. We show that the fraction of crosslinks per chain pc at the vulcanization/percolation threshold is independent of chain length N for large N. Thus for long chains, the volume fraction of crosslinks at the transition decreases as 1/N in agreement with Flory. If we allow linkages only between different chains and no self-linkages, we find that pc ∼ 0.6 in the limit of large N. This value in 20 % larger than Flory's mean field result, pc = 1/2, as some of the crosslinks do not increase the number of chains in a cluster. When we allow intra-chain linkages as they occur experimentally, the scaling with N remains unchanged but pc increases by an addition 20 % for the present model. We also find in agreement with de Gennes that the critical exponents are well described by their mean field values and that the size of the critical region where fluctuations are important is small for long polymer chains. The fractal dimension of the percolating cluster at pc was found to be 3.","PeriodicalId":14747,"journal":{"name":"Journal De Physique","volume":"20 1","pages":"2829-2842"},"PeriodicalIF":0.0,"publicationDate":"1990-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87915580","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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