Scaled penalization of Brownian motion with drift and the Brownian ascent

We study a scaled version of a two-parameter Brownian penalization model introduced by Roynette-Vallois-Yor in arXiv:math/0511102. The original model penalizes Brownian motion with drift $h\in\mathbb{R}$ by the weight process ${\big(\exp(\nu S_t):t\geq 0\big)}$ where $\nu\in\mathbb{R}$ and $\big(S_t:t\geq 0\big)$ is the running maximum of the Brownian motion. It was shown there that the resulting penalized process exhibits three distinct phases corresponding to different regions of the $(\nu,h)$-plane. In this paper, we investigate the effect of penalizing the Brownian motion concurrently with scaling and identify the limit process. This extends a result of Roynette-Yor for the ${\nu<0,~h=0}$ case to the whole parameter plane and reveals two additional "critical" phases occurring at the boundaries between the parameter regions. One of these novel phases is Brownian motion conditioned to end at its maximum, a process we call the Brownian ascent. We then relate the Brownian ascent to some well-known Brownian path fragments and to a random scaling transformation of Brownian motion recently studied by Rosenbaum-Yor.Comment: 32 pages; made additions to Section

DISTRIBUTIONS ISOTOPIQUES DES PRODUITS DE TRANSFERTS TRÈS INÉLASTIQUES ENTRE IONS LOURDS

On compare les distributions isotopiques expérimentales des produits de transfert très inélastiques obtenus par les réactions 40Ca (284 MeV) + 40Ca et 40Ar (295 MeV) + 232Th

Invariance of the white noise for KdV

We prove the invariance of the mean 0 white noise for the periodic KdV. First, we show that the Besov-type space \hat{b}^s_{p, \infty}, sp <-1, contains the support of the white noise. Then, we prove local well-posedness in \hat{b}^s_{p, \infty} for p= 2+, s = -{1/2}+ such that sp <-1. In establishing the local well-posedness, we use a variant of the Bourgain spaces with a weight. This provides an analytical proof of the invariance of the white noise under the flow of KdV obtained in Quastel-Valko.Comment: 18 pages. To appear in Comm. Math. Phy

ÉTUDE DE L'INTERACTION DE NEUTRONS DE 14 MeV SUR 238U

Le spectre d'énergie des neutrons secondaires a été observé par temps de vol de 800 keV à 14 MeV. La distribution angulaire a été étudiée de 30° à 150°. A partir des spectres expérimentaux, on a déduit les spectres de fission et d'évaporation, puis déterminé la température des noyaux excités. Une évaluation du coefficient de densité de niveaux a été faite à partir du modèle du gaz de Fermi.The fast neutron interaction of 238U has been studied by measuring the secondary neutron spectrum as a function of angle (30° ⩽ θ ⩽ 150°). The measurements were made by the time-of-flight method and spectra were observed over the energy range 800 keV-14 MeV. From experimental data, the fission and evaporation spectra have been deduced. The Fermi-gas model and the calculated temperature were used to determine the nuclear level density coefficient

TRANSFER REACTIONS ON 54Fe WITH A 80 MeV 16O BEAM

Des transferts d'un et de plusieurs nucléons sur le 54Fe sont étudiés à l'aide d'un faisceau de 16O à 80 MeV. Toutes ces réactions sont très sélectives. On obtient dans le noyau final des niveaux d'énergie d'excitation très élevée dont les principales caractéristiques peuvent être déduites.The one and multi-nucleon stripping induced on 54Fe by a 80 MeV 16O beam has been investigated. All these reactions are very selective. High energy excitation levels of the final nucleus are obtained and main features of these levels can be deduced

ÉTUDE DES RÉACTIONS (p, 2p) A 155 MeV SUR 7Li , 9Be ET 23Na AVEC UN ORDINATEUR EN LIGNE

L'étude des réactions (p, 2 p) à 155 MeV a été reprise avec un nouvel ensemble comprenant deux spectromètres magnétiques, deux chambres à étincelles à localisation et une calculatrice en ligne. Les premiers résultats ont été obtenus avec une résolution de 1,6 MeV sur 7Li, 9Be et 23Na.(p, 2 p) reactions at 155 MeV have been restudied with a new experimental set-up combining two magnetic spectrometers, two spark chambers and an on-line computer. We obtained preliminary spectra on 7Li, 9Be and 23Na with an overall energy resolution of 1.6 MeV

REACTIONS DE TRANSFERT DE PLUSIEURS NUCLEONS INDUITES PAR IONS LOURDS

Des réactions de transfert de 3, 4 et 5 nucléons conduisant au noyau résiduel 16O ont été étudiées avec des ions 12C, 16O, 20Ne, d'énergies incidentes comprises entre 72 et 100 MeV. Les spectres d'excitation montrent une certaine sélectivité dans le peuplement des états finals du noyau résiduel 16O.3, 4 and 5 nucleons transfer reactions leading to 16O residual nucleus have been studied with 12C, 16O, 20Ne beams, between 72 and 100 MeV. Excitation spectra show the population of final states of 16O residual nucleus to be rather selective

Characterization of dust particles produced in an all-tungsten wall tokamak and potentially mobilized by airflow

International audienceAt the starting of the shutdown of the AUG (ASDEX Upgrade: Axially Symmetric Divertor EXperiment) German tokamak, we collected particles deposited on the divertor surfaces by means of a dedicated device called “Duster Box”. This device allows to collect the particles using a controlled airflow with a defined shear stress. Consequently, the particles collected correspond to a potentially mobilizable fraction, by an airflow, of deposited dust. A total of more than 70,000 tungsten particles was, analysed showing a bimodal particle size distribution with a mode composed of flakes at 0.6 μm and a mode composed of spherical particles at 1.8 μm