Precision measurements in nuclear {\beta}-decay with LPCTrap

The experimental achievements and the current program with the LPCTrap device installed at the LIRAT beam line of the SPIRAL1-GANIL facility are presented. The device is dedicated to the study of the weak interaction at low energy by means of precise measurements of the {\beta}-{\nu} angular correlation parameter. Technical aspects as well as the main results are reviewed. The future program with new available beams is briefly discussed.Comment: Annalen der Physik (2013

Double (implicit and explicit) dependence of the electromagnetic field of an accelerated charge on time: Mathematical and physical analysis of the problem

We considered the electromagnetic field of a charge moving with a constant acceleration along an axis. We found that this field obtained from the Li\'enard-Wiechert potentials does not satisfy Maxwell equations if one considers exclusively a retarded interaction (i.e. pure implicit dependence this field on time). We show that if and only if one takes into account both retarded interaction and direct interaction (so called "action-at-a-distance") the field produced by an accelerated charge satisfies Maxwell equations.Comment: ReVTeX file, no figures, 12p

A new LAN concept for LEP machine networks

LEP networks, implemented in 1987, are based on two Token-ring backbones using TDM as the transmission medium. The general topology is based on routers and on a distributed backbone. To avoid the instabilities introduced by the TDM and all the conversion layers it has been decided to upgrade the LEP machine network and to evaluate a new concept for the overall network topology. The new concept will also fulfil the basic requirements for the future LHC network. The new approach relies on a large infrastructure which connects all the eight underground pits of LEP with single-mode fibres from the Prevessin control room (PCR). From the bottom of the pits, the two adjacent alcoves will be cabled with multi-mode fibres. FDDI has been selected as the MAC protocol. This new concept is based on switching and routing between the PCR and the eight pits. In each pit a hub will switch between the FDDI LMA backbone and the local Ethernet segments. Two of these segments will reach the alcoves by means of a 10Base-F link. In a second phase implementation, this scheme will provide for workgroup organisation and bandwidth allocation. The technological choices make a future evolution towards ATM and 100Base Ethernet possible and allow us to preserve a large part of the investment. This paper describes the implementation of this scheme

Action at a distance as a full-value solution of Maxwell equations: basis and application of separated potential's method

The inadequacy of Li\'{e}nard-Wiechert potentials is demonstrated as one of the examples related to the inconsistency of the conventional classical electrodynamics. The insufficiency of the Faraday-Maxwell concept to describe the whole electromagnetic phenomena and the incompleteness of a set of solutions of Maxwell equations are discussed and mathematically proved. Reasons of the introduction of the so-called ``electrodynamics dualism concept" (simultaneous coexistence of instantaneous Newton long-range and Faraday-Maxwell short-range interactions) have been displayed. It is strictly shown that the new concept presents itself as the direct consequence of the complete set of Maxwell equations and makes it possible to consider classical electrodynamics as a self-consistent and complete theory, devoid of inward contradictions. In the framework of the new approach, all main concepts of classical electrodynamics are reconsidered. In particular, a limited class of motion is revealed when accelerated charges do not radiate electromagnetic field.Comment: ReVTeX file, 24pp. Small corrections which do not have influence results of the paper. Journal reference is adde

Transport and cooling of singly-charged noble gas ion beams

The transport and cooling of noble gas singly-charged ion beams by means of a Radio Frequency Quadrupole Cooler Buncher (RFQCB) have been studied at the LIMBE low energy beam line of the GANIL facility. Ions as light as $^{4}He^+$ have been cooled and stored before their extraction in bunches using $H_2$ as buffer gas. Bunches characteristics have been studied as a function of the parameters of the device. Sizeable transmissions of up to 10 $$ have been obtained. A detailed study of the lifetime of ions inside the buncher has been performed giving an estimate of the charge exchange cross-section. Results of a microscopic Monte-Carlo transport code show reasonable agreement with experimental data.Comment: 13 figure

Forces between electric charges in motion: Rutherford scattering, circular Keplerian orbits, action-at-a-distance and Newton's third law in relativistic classical electrodynamics

Standard formulae of classical electromagnetism for the forces between electric charges in motion derived from retarded potentials are compared with those obtained from a recently developed relativistic classical electrodynamic theory with an instantaneous inter-charge force. Problems discussed include small angle Rutherford scattering, Jackson's recent `torque paradox' and circular Keplerian orbits. Results consistent with special relativity are obtained only with an instantaneous interaction. The impossiblity of stable circular motion with retarded fields in either classical electromagnetism or Newtonian gravitation is demonstrated.Comment: 26 pages, 5 figures. QED and special relativity forbid retarded electromagnetic forces. See also physics/0501130. V2 has typos corrected, minor text modifications and updated references. V3 has further typos removed and added text and reference

Intellectual synthesis in mentorship determines success in academic careers

As academic careers become more competitive, junior scientists need to understand the value that mentorship brings to their success in academia. Previous research has found that, unsurprisingly, successful mentors tend to train successful students. But what characteristics of this relationship predict success, and how? We analyzed an open-access database of 18,856 researchers who have undergone both graduate and postdoctoral training, compiled across several fields of biomedical science with an emphasis on neuroscience. Our results show that postdoctoral mentors were more instrumental to trainees\u27 success compared to graduate mentors. Trainees\u27 success in academia was also predicted by the degree of intellectual synthesis between their graduate and postdoctoral mentors. Researchers were more likely to succeed if they trained under mentors with disparate expertise and integrated that expertise into their own work. This pattern has held up over at least 40 years, despite fluctuations in the number of students and availability of independent research positions

High Frequencies of Naive Melan-a/Mart-1–Specific Cd8+ T Cells in a Large Proportion of Human Histocompatibility Leukocyte Antigen (Hla)-A2 Individuals

Using fluorescent HLA-A*0201 tetramers containing the immunodominant Melan-A/MART-1 (Melan-A) tumor-associated antigen (Ag), we previously observed that metastatic lymph nodes of melanoma patients contain high numbers of Ag-experienced Melan-A–specific cytolytic T lymphocytes (CTLs). In this paper, we enumerated and characterized ex vivo Melan-A–specific cells in peripheral blood samples from both melanoma patients and healthy individuals. High frequencies (≥1 in 2,500 CD8+ T cells) of Melan-A–specific cells were found in 10 out of 13 patients, and, surprisingly, in 6 out of 10 healthy individuals. Virtually all Melan-A–specific cells from 6 out of 6 healthy individuals and from 7 out of 10 patients displayed a naive CD45RAhi/RO− phenotype, whereas variable proportions of Ag-experienced CD45RAlo/RO+ Melan-A–specific cells were observed in the remaining 3 patients. In contrast, ex vivo influenza matrix–specific CTLs from all individuals exhibited a CD45RAlo/RO+ memory phenotype as expected. Ag specificity of tetramer-sorted A2/Melan-A+ cells from healthy individuals was confirmed after mitogen-driven expansion. Likewise, functional limiting dilution analysis and interferon γ ELISPOT assays independently confirmed that most of the Melan-A–specific cells were not Ag experienced. Thus, it appears that high frequencies of naive Melan-A–specific CD8+ T cells can be found in a large proportion of HLA-A*0201+ individuals. Furthermore, as demonstrated for one patient followed over time, dramatic phenotype changes of circulating Melan-A–specific cells can occur in vivo

LHC Superconducting Dipole Production Follow-up: Results of Audit on QA Aspects in Industry

The manufacturing of the 1232 Superconducting Main Dipoles for LHC is under way at three European Contractors: Alstom-Jeumont (Consortium), Ansaldo Superconduttori Genova and Babcock Noell Nuclear. The manufacturing is proceeding in a very satisfactory way and in March 2005 the mid production was achieved. To intercept eventually âﾜweak pointsâ of the production process still present and in order to make a check of the Quality Assurance and Control in place for the series production, an Audit action was launched by CERN during summer-fall 2004. Aspects like: completion of Production and Quality Assurance documentation, structure of QC Teams, traceability, calibration and maintenance for tooling, incoming components inspections, were checked during a total of seven visits at the five different production sites. The results of the Audit in terms of analysis of âﾜsystematicâ and âﾜrandomâ problems encountered as well as corrective actions requested are presented