Evaporative cooling of an atomic beam

We present a theoretical analysis of the evaporative cooling of an atomic beam propagating in a magnetic guide. Cooling is provided by transverse evaporation. The atomic dynamics inside the guide is analyzed by solving the Boltzmann equation with two different approaches: an approximate analytical ansatz and a Monte-Carlo simulation. Within their domain of validity, these two methods are found to be in very good agreement with each other. They allow us to determine how the phase-space density and the flux of the beam vary along its direction of propagation. We find a significant increase for the phase-space density along the guide for realistic experimental parameters. By extrapolation, we estimate the length of the beam needed to reach quantum degeneracy.Comment: 13 pages, 7 figures, to be published in EPJ D, revised versio

啓蒙とユートピア : 18世紀のロシアと西欧

International audienc

Novel Ferromagnetic Atom Waveguide with in situ loading

Magneto-optic and magnetostatic trapping is realized near a surface using current carrying coils wrapped around magnetizable cores. A cloud of 10^7 Cesium atoms is created with currents less than 50 mA. Ramping up the current while maintaining optical dissipation leads to tightly confined atom clouds with an aspect ratio of 1:1000. We study the 3D character of the magnetic potential and characterize atom number and density as a function of the applied current. The field gradient in the transverse dimension has been varied from < 10 G/cm to > 1 kG/cm. By loading and cooling atoms in-situ, we have eliminated the problem of coupling from a MOT into a smaller phase space.Comment: 4 pages, 4 figure

A Storage Ring for Neutral Atoms

We have demonstrated a storage ring for ultra-cold neutral atoms. Atoms with mean velocities of 1 m/s corresponding to kinetic energies of ~100 neV are confined to a 2 cm diameter ring by magnetic forces produced by two current-carrying wires. Up to 10^6 atoms are loaded at a time in the ring, and 7 revolutions are clearly observed. Additionally, we have demonstrated multiple loading of the ring and deterministic manipulation of the longitudinal velocity distribution of the atoms using applied laser pulses. Applications of this ring include large area atom interferometers and cw monochromatic atomic beam generation.Comment: 4 pages, 5 figure

Predicting the Location of Glioma Recurrence After a Resection Surgery

International audienceWe propose a method for estimating the location of glioma recurrence after surgical resection. This method consists of a pipeline including the registration of images at different time points, the estimation of the tumor infiltration map, and the prediction of tumor regrowth using a reaction-diffusion model. A data set acquired on a patient with a low-grade glioma and post surgery MRIs is considered to evaluate the accuracy of the estimated recurrence locations found using our method. We observed good agreement in tumor volume prediction and qualitative matching in regrowth locations. Therefore, the proposed method seems adequate for modeling low-grade glioma recurrence. This tool could help clinicians anticipate tumor regrowth and better characterize the radiologically non-visible infiltrative extent of the tumor. Such information could pave the way for model-based personalization of treatment planning in a near future

Continuous loading of a magnetic trap

We have realized a scheme for continuous loading of a magnetic trap (MT). ^{52}Cr atoms are continuously captured and cooled in a magneto-optical trap (MOT). Optical pumping to a metastable state decouples atoms from the cooling light. Due to their high magnetic moment (6 Bohr magnetons), low-field seeking metastable atoms are trapped in the magnetic quadrupole field provided by the MOT. Limited by inelastic collisions between atoms in the MOT and in the MT, we load 10^8 metastable atoms at a rate of 10^8 atoms/s below 100 microkelvin into the MT. After loading we can perform optical repumping to realize a MT of ground state chromium atoms.Comment: 4 pages, 4 figures, version 2, modified references, included additional detailed information, minor changes in figure 3 and in tex

Continuous optical loading of a Bose-Einstein Condensate

The continuous pumping of atoms into a Bose-Einstein condensate via spontaneous emission from a thermal reservoir is analyzed. We consider the case of atoms with a three-level $\Lambda$ scheme, in which one of the atomic transitions has a very much shorter life-time than the other one. We found that in such scenario the photon reabsorption in dense clouds can be considered negligible. If in addition inelastic processes can be neglected, we find that optical pumping can be used to continuously load and refill Bose-Einstein condensates, i.e. provides a possible way to achieve a continuous atom laser.Comment: 12 pages, 8 figure

Radio-induced low-grade glioma: report of two cases and review of the literature

With the increasing number of cancer survivors, we can observe a population that will present a higher risk of developing secondary long-term toxicities related to adjuvant chemo and radiotherapy regimens. Among these, children surviving from acute lymphoblastic leukemia (ALL) that were treated with prophylactic cranial irradiation represent a group of patients at a high risk of developing secondary brain tumors. Radiation-induced intracranial tumors have been documented since 1950, and today, more than one-hundred cases have been described. We report our experience with two young patients who were hospitalized for low grade gliomas and had a positive anamnesis for ALL and consequent radiotherapy

Chemotherapy and diffuse low-grade gliomas: a survey within the European Low-Grade Glioma Network.

Diffuse low-grade gliomas (DLGGs) are rare and incurable tumors. Whereas maximal safe, functional-based surgical resection is the first-line treatment, the timing and choice of further treatments (chemotherapy, radiation therapy, or combined treatments) remain controversial. An online survey on the management of DLGG patients was sent to 28 expert centers from the European Low-Grade Glioma Network (ELGGN) in May 2015. It contained 40 specific questions addressing the modalities of use of chemotherapy in these patients. The survey demonstrated a significant heterogeneity in practice regarding the initial management of DLGG patients and the use of chemotherapy. Interestingly, radiation therapy combined with the procarbazine, CCNU (lomustine), and vincristine regimen has not imposed itself as the gold-standard treatment after surgery, despite the results of the Radiation Therapy Oncology Group 9802 study. Temozolomide is largely used as first-line treatment after surgical resection for high-risk DLGG patients, or at progression. The heterogeneity in the management of patients with DLGG demonstrates that many questions regarding the postoperative strategy and the use of chemotherapy remain unanswered. Our survey reveals a high recruitment potential within the ELGGN for retrospective or prospective studies to generate new data regarding these issues