A new low intensity beam profiler for SPIRAL2

WEPF14International audienceIn the framework of SPIRAL 2 ion beams, several beam profile monitors are presently being developed at GANIL. One of them is a low-intensity beam-profile monitor that works as a secondary electron detector. This Emission-Foil Monitor (EFM) will be used in the radioactive beam lines of SPIRAL2 and in the experimental rooms of this new facility. The ions produce secondary electrons when they are stopped in an aluminium emissive foil. The electrons are then accelerated using an electric field and guided using a magnetic field to a double-stage microchannel plate (MCP). A 2D pixellated pad plane placed below the MCP is used to collect the signals. The magnetic field created by permanent magnets in a closed magnetic circuit configuration permits the beam-profile reconstruction to be achieved with a good resolution. The EFM can visualize beam-profile intensities between only a few pps to as much as 109 pps and with energies as low as several keV. This profiler has been under development since 2009 and is currently manufactured. Recent results of this monitor are presented in this article

Teleology and Realism in Leibniz's Philosophy of Science

This paper argues for an interpretation of Leibniz’s claim that physics requires both mechanical and teleological principles as a view regarding the interpretation of physical theories. Granting that Leibniz’s fundamental ontology remains non-physical, or mentalistic, it argues that teleological principles nevertheless ground a realist commitment about mechanical descriptions of phenomena. The empirical results of the new sciences, according to Leibniz, have genuine truth conditions: there is a fact of the matter about the regularities observed in experience. Taking this stance, however, requires bringing non-empirical reasons to bear upon mechanical causal claims. This paper first evaluates extant interpretations of Leibniz’s thesis that there are two realms in physics as describing parallel, self-sufficient sets of laws. It then examines Leibniz’s use of teleological principles to interpret scientific results in the context of his interventions in debates in seventeenth-century kinematic theory, and in the teaching of Copernicanism. Leibniz’s use of the principle of continuity and the principle of simplicity, for instance, reveal an underlying commitment to the truth-aptness, or approximate truth-aptness, of the new natural sciences. The paper concludes with a brief remark on the relation between metaphysics, theology, and physics in Leibniz

Spinoza on Activity in Sense Perception

There can be little disagreement about whether ideas of sense perception are, for Spinoza, to be classed as passions or actions—the former is obviously the correct answer. All this, however, does not mean that sense perception would be, for Spinoza, completely passive. In this essay I argue argues that there is in the Ethics an elaborate—and to my knowledge previously unacknowledged—line of reasoning according to which sense perception of finite things never fails to contain a definite active component. This argument for activity in sense perception consists of two main parts: first, that ideas we form through sense perception have something adequate in them; second, that the adequate component is actively brought about. Discerning this line of thought connects to—and sheds some new light on—Spinoza’s general way of understanding ideas as entities involving activity

A New Low Intensity Beam Profile Monitor for SPIRAL2

In order to obtain profiles of SPIRAL 2 ion beams, several beam profile monitors are presently being developed at GANIL. One of them is a lowintensity beam-profile monitor (EFM). This Emission-FoilMonitor (EFM) will be used in the radioactive beam lines of SPIRAL2 and in the experimental rooms of this new facility. The ions produce secondary electrons when they are stopped in an aluminium emissive foil. The electrons are then guided in an electric field placed parallel to a magnetic field in a doublestage microchannel plate (MCP). A 2D pixelated pad plane placed below theMCP is then used to collect the signal. The magnetic field created by permanent magnets in a closed magnetic circuit configuration permits the beam-profile reconstruction to be achieved with good resolution. The EFM can visualize beam-profile intensities between only a few pps to as much as 109 pps and with energies as low as several keV. This profiler has been under development since 2011 and is actually manufactured. For the signal acquisition, a new dedicated electronics system will be employed. Recent results of this monitor and its associated electronics will be presented here

Testing residual gas profiler at SARAF

A Residual Gas Monitor (RGM) developed at GANIL was tested with pulsed and CW proton beams at currents up to 1 mA at SARAF Phase I. Response of the detector as a function of beam current and duty cycle was measured. Beam profiles were measured at different beam size and position values and compared with measurements performed with a multi-wire grid profiler. Influence of the low-energy beam transfer (LEBT) optical settings on intense CW beams was studied for the first time. The obtained data enabled a better analysis and understanding of the current ramp-up process

High Resolution 3d Reconstructions of Rocks and Composites

International audienceTen micrometers resolution 3D representations of different media, were obtained with a laboratory computer microtomograph developed from an electron microprobe column. From the original electron microprobe, only minor modifications have been required, indeed several of the utilities of the microprobe have been used to ensure high resolution radiography (2 micrometers). The impact of the electron beam focused onto a thin film is used to form a pointX-ray source and the radiographic image of the sample is acquired on a CCD camera. A specimen rotation mechanism allows multiple radiograph acquisition and reconstruction of the X-ray attenuation 3D cartography. Since X-ray attenuation is directly related to density and atomic number, the microscanner provides 3D cartographs of the different phases present in the sample. System performances have been evaluated on various samples, mainly rocks and composites. Comparison with scanning electron micrographs was used when possible to validate the reconstructions. Results are mostly qualitative but already show the potential of the technique in describing 3D connectivity and topology of pore networks or 3D orientation of fibres in composites

High Resolution 3d Reconstructions of Rocks and Composites

Ten micrometers resolution 3D representations of different media, were obtained with a laboratory computer microtomograph developed from an electron microprobe column. From the original electron microprobe, only minor modifications have been required, indeed several of the utilities of the microprobe have been used to ensure high resolution radiography (2 micrometers). The impact of the electron beam focused onto a thin film is used to form a pointX-ray source and the radiographic image of the sample is acquired on a CCD camera. A specimen rotation mechanism allows multiple radiograph acquisition and reconstruction of the X-ray attenuation 3D cartography. Since X-ray attenuation is directly related to density and atomic number, the microscanner provides 3D cartographs of the different phases present in the sample. System performances have been evaluated on various samples, mainly rocks and composites. Comparison with scanning electron micrographs was used when possible to validate the reconstructions. Results are mostly qualitative but already show the potential of the technique in describing 3D connectivity and topology of pore networks or 3D orientation of fibres in composites