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To fulfill needs in oncological research a new Micromegas detector has been developed to follow radiolabelled drugs in living organisms at the single cell level. This article describes the proof-of-concept of such a detector and compares its ability to detect and assess sub-becquerel \tritium~activities with a commercial $\beta$-imager, Comment: 14 pages, to be submitted to NIMA

This document presents the technical layout and the performance of the CLAS12 Forward Tagger (FT). The FT, composed of an electromagnetic calorimeter based on PbWO4 crystals (FT-Cal), a scintillation hodoscope (FT-Hodo), and several layers of Micromegas trackers (FT-Trk), has been designed to detect electrons and photons scattered at polar angles from 2 ∘ to 5 ∘ and to meet the physics goals of the hadron spectroscopy program and other experiments running with the CLAS12 spectrometer in Hall B.

An upgrade of the Near Detector of the T2K long baseline neutrino oscillation experiment, ND280, has been proposed. This upgrade will include two new Time Projection Chambers, each equipped with 16 resistive MicroMegas modules for gas amplification. A first prototype of resistive MicroMegas has been designed, built, installed in the HARP field cage, and exposed to a beam of charged particles at CERN. The data have been used to characterize the performances of the resistive MicroMegas module. A spatial resolution of 300 $\mu m$ and a deposited energy resolution of 9% were observed for horizontal electrons crossing the TPCs at 30 cm from the anode. Such performances fully satisfy the requirements for the upgrade of the ND280 TPC., Comment: 31 pages, 26 figures

The Micromegas Vertex Tracker was designed to improve upon the tracking capabilities of the baseline design of the CLAS12 spectrometer in Hall B at Jefferson Laboratory. A Barrel Micromegas Tracker made with six concentric cylinders, each made of three 120 ∘ -sector tiles, surrounds the Silicon Vertex Tracker, and a Forward Micromegas Tracker composed of 6 disks is placed 30 cm downstream of the liquid-hydrogen target. Both trackers sit in a 5 T solenoid magnetic field. All Micromegas elements are based on resistive technology to withstand luminosities up to 1 0 35 cm−2 s−1, as well as on bulk technology to enforce gain uniformity and mechanical robustness. Due to the high magnetic field, dedicated electronics have been designed and displaced ∼ 2 m away from the detectors. The electronics readout is based on the DREAM ASICs that allow sustained operation up to 20 kHz trigger rate at the maximum luminosity.

The Great Pyramid or Khufu's Pyramid was built on the Giza Plateau (Egypt) during the IVth dynasty by the pharaoh Khufu (Cheops), who reigned from 2509 to 2483 BC. Despite being one of the oldest and largest monuments on Earth, there is no consensus about how it was built. To better understand its internal structure, we imaged the pyramid using muons, which are by-products of cosmic rays that are only partially absorbed by stone. The resulting cosmic-ray muon radiography allows us to visualize the known and potentially unknown voids in the pyramid in a non-invasive way. Here we report the discovery of a large void (with a cross section similar to the Grand Gallery and a length of 30 m minimum) above the Grand Gallery, which constitutes the first major inner structure found in the Great Pyramid since the 19th century. This void, named ScanPyramids Big Void, was first observed with nuclear emulsion films installed in the Queen's chamber (University of Nagoya), then confirmed with scintillator hodoscopes set up in the same chamber (KEK) and re-confirmed with gas detectors outside of the pyramid (CEA). This large void has therefore been detected with a high confidence by three different muon detection technologies and three independent analyses. These results constitute a breakthrough for the understanding of Khufu's Pyramid and its internal structure. While there is currently no information about the role of this void, these findings show how modern particle physics can shed new light on the world's archaeological heritage., Comment: Nature (2017)

International audience; The performance of the first large resistive Micromegas detectors with 2D readout and genetic multi-plexing is presented. These detectors have a × 50 50cm 2 active area and are equipped with 1024 strips both in X-and Y-directions. The same genetic multiplexing pattern is applied on both coordinates, resulting in the compression of signals on × 2 61 readout channels. Four such detectors have been built at CERN, and extensively tested with cosmics. The resistive strip film allows for very high gain operation, compensating for the charge spread on the 2 dimensions as well as the S N / loss due to the huge, 1 nF input capacitance. This film also creates a significantly different signal shape in the X-and Y-coordinates due to the charge evacuation along the resistive strips. All in all a detection efficiency above 95% is achieved with a 1 cm drift gap. Though not yet optimal, the measured 300 mm spatial resolution allows for very precise imaging in the field of muon tomography, and some applications of these detectors are presented.

For the International Large Detector concept at the planned International Linear Collider, the use of time projection chambers (TPC) with micro-pattern gas detector readout as the main tracking detector is investigated. In this paper, results from a prototype TPC, placed in a 1 T solenoidal field and read out with three independent GEM-based readout modules, are reported. The TPC was exposed to a 6 GeV electron beam at the DESY II synchrotron. The efficiency for reconstructing hits, the measurement of the drift velocity, the space point resolution and the control of field inhomogeneities are presented., 22 pages, 19 figures

International audience; This paper reports about the first Micromegas-based telescope built for applications in muon tomo-graphy. The telescope consists of four, 50 Â 50 cm 2 resistive multiplexed Micromegas with a 2D layout and a self-triggering electronics based on the Dream chip. Thanks to the multiplexing, the four detectors were readout with a single Front-End Unit. The high voltages were provided by a dedicated card using low consumption CAEN miniaturized modules. A nano-PC (Hummingboard) ensured the HV control and monitoring coupled with a temperature feedback as well as the data acquisition and storage. The overall consumption of the instrument yielded 30 W only, i.e. the equivalent of a standard bulb. The telescope was operated outside during 3.5 months to image the water tower of the CEA-Saclay research center, including a 1.5-month campaign with solar panels. The development of autonomous, low consumption muon telescopes with unprecedented accuracy opens new applications in imaging as well as in the field of muon metrology.

The study of nuclear ssion is encountering renewed interest with the development of GEN-IV reactor concepts, mostly working in the neutron fast energy domain. To support the fast reactor technologies, new high quality nuclear data are needed. For this reason, the future Neutrons For Sciences (NFS) installation, built in the framework of the SPIRAL2 project and producing high intensity neutron beams from hundreds of keV up to 40 MeV, will open new opportunities to characterise the actinide ssion fragments. To perform these measurements, the development of an experimental setup called FAL- STAFF has been undertaken. This novel apparatus is meant to provide a simultaneous characterisation of the complementary fragments in terms of mass, kinetic energy and to evaluate the average neutron multiplicity. To reach this goal the spectrometer must present a very good time, energy and space resolutions. The coupling of the Secondary Electron Detectors (SeD) detectors with an ionisation axial chamber seems ful ll these conditions. The ssion fragment velocities are measured employing two time-of- ight (SeD), sepa- rated by a distance of 50 cm. Those detectors combine a Mylar foil and a MWPC (multi wire proportional counter) to measure the arrival time and the position of the incoming particle. The fragment energies are measured by an axial ionisation chamber, CALIBER, placed after the SeD Stop detector. Moreover, the axial con guration of the chamber gives access to the energy loss pro le, which could be used to identify the light fragment nuclear charge. The FALSTAFF setup and the upgrade of the rst arm prototype with the new ionisa- tion chamber CALIBER will be presented. New tests are performed at CEA-Saclay and the combined measurement obtained from the SeD and the ionisation chamber will be shown. The performances of the experimental apparatus in terms of energy and mass resolution will be discussed.

A low background Micromegas detector has been operating on the Cern Axion Solar Telescope (CAST) experiment at CERN for the search of solar axions during the first phase of the experiment. The detector operated efficiently and achieved a very low level of background rejection ( 5 × 10 - 5 counts keV - 1 cm - 2 s - 1 ) thanks to its good spatial and energy resolution as well as the low radioactivity materials used in the construction of the detector. For the second phase of the experiment, the detector is being upgraded by adding a shielding and including focusing optics. These improvements should allow for a background rejection better than two orders of magnitude. The preliminary results of the first tests in the laboratory and in the PANTER X-ray test facility will be shown.

We present the development of a thin large-area tracking detector. The thickness of matter intercepted by the ions is approximately 0.25 mg/cm 2 of low-mass material (aluminized Mylar). It is designed to detect low-energy heavy ions with a minimum of energy and angular straggling. We use a secondary electron emission foil coupled to an innovative large-area gaseous electron detector. The electrons are guided toward the detector by an electric and a magnetic field. We achieve good time (300 ps FWHM) and two-dimensional position (1.4 mm FWHM) resolutions over a large area (10×40 cm 2 ).

A new Secondary Electron gas Detector (SED) is under development to be used in conjunction with an emissive foil to detect low energy heavy ions as an alternative to micro-channel plates. It could measure position and time of flight. Secondary electrons are accelerated to 10 keV so that they can cross through the 0.9 μm Mylar entrance window. The electrons then are multiplied in the isobutane gas of the detector at 4– 10 Torr . A time resolution of 150 ps and a spatial resolution of 3 mm have been obtained by using californium fission fragments on a prototype detector of 7×7 cm 2 . The advantage of the SED against MCP is that its size is not limited. Our final goal is to build a large size detector (15×40 cm 2 ) that will operate at the focal plane of the VAMOS magnetic spectrometer at GANIL.

In this paper, the architecture of the Clas12 Micromegas vertex tracker readout is described and the details of its implementation are given. The innovations allowing to meet the challenging requirements of the tracker operation are presented. The system performance is evaluated based on detector tests with a cosmic rays trigger and on standalone high rate validation tests. Finally, the perspectives to adapt the readout system or a part of it to other experiments are discussed.

Trabajo presentado a la: "3rd International Conference on Micro Pattern Gaseous Detectors (MPGD2013)", celebrada en Zaragoza (España) del 1 al 4 de julio de 2013.-- et al., The focal plane of S3 (Super Separator Spectrometer), a new experimental area of SPIRAL2 at GANIL, will be used for identification of nuclei, and requires the reconstruction of their trajectories and velocities by the Time Of Flight (TOF) method. Classical tracking detectors used in-beam would generate a lot of angular and energy straggling due to their thickness. One solution is the use of a SED (Secondary Electron Detection), which consists of a thin emissive foil in beam coupled to a low pressure gaseous detector out of the beam, for the detection of secondary electrons ejected from the foil. Moreover, this type of detector can be used for classical beam tracking at low energies, or for example at NFS (GANIL) for the FALSTAFF experiment for the reconstruction of fission fragments trajectories. Several low pressure gaseous detectors such as wire chambers and Micromegas have been constructed and tested since 2008. High counting rate capabilities and good time resolution obtained in previous tests motivated the construction of a new real-size 2D prototype wire chamber and a 2D bulk Micromegas at low pressure. For the first time, spatial resolution of the Micromegas at low pressure (below 20 mbar) in the SED configuration was measured. Different tests have been performed in order to characterize time and spatial properties of both prototypes, giving spatial resolution in the horizontal (X) direction of 0.90(0.02) mm FWHM for the real size prototype and 0.72(0.08) mm FWHM for Micromegas, and a time resolution of ~ 110(25) ps for the real size prototype.

We present an innovative detector with a large working area (100×400 mm 2 ) for ion tracking. This device is based on the detection of secondary electron emitted by a thin foil placed at 45° to the direction of the beam. Secondary electrons are accelerated and focused by an electric and a magnetic field toward a low-pressure gaseous chamber. Time and position ( X and Y ) are measured. The typical resolutions (FWHM) are 300 ps and 1.5 mm , respectively.

This work presents the design, implementation and test of prototype modules of a Time Projection Chamber based on Micromegas amplification technology which was built in view of the future International Linear Collider. The main goals of this development are to investigate the performance of the detector and to demonstrate the feasibility of extremely compact and low power readout electronics. We based the front-end electronics on the AFTER chip, a 72-channel ASIC originally built for the T2K experiment, and integrated it with new hardware, mechanics and cooling to read out the 1728 channels of a detector module while staying confined in the available area of ~ 220 cm2. The digital part of a module is based on a Xilinx Virtex-5 FPGA which interfaces to the 24 AFTER chips used for the readout. We present the operation of a vertical slice of the complete detector and readout system. In particular, our tests show that the resistive anode of the Micromegas detector, which is primarily designed to improve tracking resolution, allows operation without the spark protection circuit normally required on each readout channel.

Trabajo presentado al: "2nd International Conference on Micro Pattern Gaseous Detectors (MPGD2011)" celebrado del 29 de agosto al 1 de septiembre del 2011 en Japón.-- Open Access.-- et al., New facilities like FAIR at GSI or SPIRAL2 at GANIL, will provide radioactive ion beams at low energies (less than 10 MeV/n). Such beams have generally a large emittance, which requires the use of beam tracking detectors to reconstruct the exact trajectories of the nuclei. To avoid the angular and energy straggling that classical beam tracking detectors would generate in the beam due to their thickness, we propose the use of SED (Secondary Electron Detectors). It consists of a low pressure gaseous detector placed outside the beam coupled to an emissive foil in the beam. Since 2008, different low pressure gaseous detectors (wire chambers and micromegas) have been constructed and tested. The performances achievable at low pressure are similar to or even better than the ones at atmospheric pressure. The fast charge collection leads to excellent timing properties as well as high counting rate capabilities. Several micromegas at low pressure were tested in the laboratory demonstrating a good time resolution, 130±30 ps, which is compatible with the results obtained with wire chambers., This work is supported by the Spanish Research Project FPA2009-08848.

We have recently developed a gas based detection system called AstroBox, motivated by nuclear astrophysics studies. The goal was to detect very low-energy protons from β-delayed p-decay with reduced beta background and improved energy resolution. The detector was tested using the β-delayed proton-emitter 23Al previously studied with a set-up based on thin double-sided Si strip detectors. The proton spectrum obtained with AstroBox showed no beta background down to ∼80 keV. The low energy (206 keV, 267 keV) proton peaks were positively identified, well separated, and the resolution was improved.

New accelerators like SPIRAL2 (GANIL, France) or FAIR (GSI, Germany) will be soon constructed, and they will be able to produce radioactive ion beams (RIB) with high intensities of current (≥106pps). These beams, at low energy, lower than 20 MeV/n, usually have high emittance, which imposes the use of tracking detectors before the target in order to reconstruct the trajectory of the ions. The group of Nuclear Physics at CNA (Centro Nacional de Aceleradores), is in charge of developing a tracking system for the low energy branch of FAIR (the HISPEC/DESPEC project). A collaboration with CEA-SACLAY was established, with the aim of developing, building and testing low pressure Secondary electron Detectors (SeD). Within this proposal we have projected and constructed a new Nuclear Physics Line in the CNA in order to be able to receive any kind of detector tests and the associated nuclear instruments.

International audience; SPIRAL2 or FAIR will be able to deliver beams of radioactive isotopes of low energy (less than 10MeV/n). The emittance of these new beams will impose the use of beam tracking detectors to reconstruct the exact impact position of the nuclei on the experimental target. However, due to their thickness, the classical detectors will generate a lot of energy and angular straggling. A possible alternative is the SED principle (Secondary Electron Detector). It consists of an emissive foil placed in beam and a detector for the secondary electrons ejected by the passing of the nuclei through the foil. An R&D program has been initiated at CEA Saclay to study the possibility to use low pressure gaseous detectors as SED for beam tracking. Some SED have been already used on the VAMOS spectrometer at GANIL since 2004. We have constructed new detectors on this model to measure their performances in time and spatial resolution, and counting rate. Other detector types are also under study. For the first time, a test with different micromegas detectors at 4 Torr has been realized. A comparison on the time resolution has been performed between wire chamber and micromegas at very low pressure. The use of micromegas could be promising to improve the counting rate capability and the robustness of beam tracking detectors.

International audience; After a short description of the Micromegas principle, a concept of new neutron detectors based on this technique is presented. It is illustrated by an overall picture of the use of these detectors in different domains such as: nuclear physics, inertial fusion and industrial applications. A particular description will be devoted to two topics. The first one concerns the compact detector named ldquoPiccolo- Micromegasrdquo. This detector, capable of measuring a neutron flux in a broad range of neutron energies, is developed for the measurements of the in-core neutrons flux of future generations of nuclear reactors. The second one based on the new micro-bulk concept is developed for a monitoring detector of a neutron beam.

An Accelerator Driven System (ADS) consists in the coupling of an accelerator with a nuclear reactor. Such systems will need neutron detectors working in a wide energy range and insensitive to X- and γ-rays. Micromegas technology has been proposed to achieve this goal. The ability of Micromegas to detect neutrons over a wide energy range has already been demonstrated and this detector is, under certain conditions, insensitive to γ-rays. A new Micromegas neutron detector called Piccolo Micromegas has been designed to get integrated neutron fluxes on different energy domains. For the first time, Piccolo Micromegas has been placed in the core of a nuclear reactor at Casaccia in Italy. The configuration of the detector will be presented as well as its functioning and the reasons of its insensitivity to γ-rays. The results of the operation of the detector will also be shown for low reactor power to high reactor power and some improvements will be suggested.

The ASACUSA Micromegas Tracker (AMT; ASACUSA: Atomic Spectroscopy and Collisions Using Slow Antiprotons) was designed to be able to reconstruct antiproton-nucleon annihilation vertices in three dimensions. The goal of this device is to study antihydrogen formation processes in the ASACUSA cusp trap, which was designed to synthesise a spin-polarised antihydrogen beam for precise tests of Charge, Parity, and Time (CPT) symmetry invariance. This paper discusses the structure and technical details of an AMT detector built into such an environment, its data acquisition system and the first performance with cosmic rays.

A low background Micromegas X-ray detector has been used to search for solar axions in the CAST experiment at CERN. The detector has an active area of 7cm times 7cm, excellent spatial resolution (~70nm), and good energy resolution. It is built using low radioactivity materials and the obtained background level is below 5times10-5 counts/keV/cm2/s. The detector is being upgraded for the second phase of the experiment (2006-2007) with a reduced active area. A focusing X-Ray optic and improved shielding will be used to further reduce the background by approximately two orders of magnitude.

ADS need neutron detectors working on a wide energy range and quite insensitive to X- and gamma-rays. Micromegas technology has been proposed to achieve this goal. The ability of Micromegas to detect neutrons has already been demonstrated and this detector is, under certain conditions, insensitive to gamma-rays. A new Micromegas neutron detector has been designed and it gives the possibility to get integrated neutron fluxes on different energy domains. The configuration of the detector will be presented as well as its functioning and the reasons of its insensitivity to gamma-rays. Moreover, some experiments have been realized on a TRIGA reactor at Casaccia in Italy. It is the first time that a Micromegas is placed in a nuclear reactor. The configuration and results of these tests will be shown and some improvements suggested.

Future fast nuclear reactors designed for energy production and transmutation of nuclear wastes need new neutrons detectors able to measure the neutron flux over a large energy range from thermal energies to several MeV. A novel compact and very small detector, named Piccolo-Micromegas has been developed for this purpose. Description of the detector configuration especially dedicated to neutron detection inside nuclear reactor is given. The advantage of this detector over conventional neutron flux detectors and the results obtained with the first prototype are presented.

A low background Micromegas detector has been operating on the CAST experiment at CERN for the search of solar axions during the first phase of the experiment (2002-2004). The detector operated efficiently and achieved a very low level of background rejection ($5\times 10^{-5}$ counts keV$^{-1}$cm$^{-2}$s$^{-1}$) thanks to its good spatial and energy resolution as well as the low radioactivity materials used in the construction of the detector. For the second phase of the experiment (2005-2007), the detector will be upgraded by adding a shielding and including focusing optics. These improvements should allow for a background rejection better than two orders of magnitude., 6 pages, 3 figures To appear on the proceedings of the 9th ICATPP Conference on AStroparticle, Particle, Space Physics, Detectors and Medical Physics Applications

A new neutron detector based on Micromegas technology has been developed for the measurement of the simulated neutron spectrum in the ADS project. After the presentation of simulated neutron spectra obtained in the interaction of 140 MeV protons with the spallation target inside the TRIGA core, a full description of the new detector configuration is given. The advantage of this detector compared to conventional neutron flux detectors and the results obtained with the first prototype at the CELINA 14 MeV neutron source facility at CEA-Cadarache are presented. The future developments of operational Piccolo-Micromegas for fast neutron reactors are also described., Comment: 5 pages, 7 figures, AccApp05 Conference

For measurements with low energy radio active or stable beams it is important to reconstruct trajectories for ions in large solid angle spectrometers. In this paper we describe a large area (106 × 420 mm _) tracking secondary electron detectors, Se−D. In Se−D, the electrons emitted by an aluminized Mylar foil are captured by an electromagnetic field and focused on an electron gaseous detector to give a time and 2‐D position resolution (sigma) of typically 130 nsec and 0.8 mm.

International audience; The Fusion Utility for Secondary Ions (FUSION) has been built to measure the fusion–fission cross section induced by radioactive beams at energies around the barrier. A set of 10 parallel plate avalanche counters measures the fission fragments which are stopped therein. Twenty plastic scintillators, surrounding the inner shell of PPACs, detect the eventual residue from the projectile. This detector could work in different geometry and allow measurements of low cross section with very weak beams. The measurements at GANIL of the fission cross sections at barrier energies for $^{9,11}$Be on U are reported.

A beam detector system, CATS (Chambre A Trajectoires de Saclay), was designed to provide event-by-event particle tracking in experiments with radioactive beams at GANIL. It consists of two low pressure multiwire proportionnal chambers with one plane of anode wires placed between two cathode planes (active area: 70×70 mm2), respectively segmented into 28 vertical or horizontal strips (2.54 mm wide). The anode wires deliver a time signal allowing a time of flight measurement with an accuracy between 440 ps and 1.2 ns, depending on the energy loss of incident particles in the detector. The cathode strips are individually read out and the position of incoming particles is reconstructed using a charge centroid finding algorithm. A spatial resolution of 400 μm (700 μm) was achieved during in beam experiment, with a counting rate of 1.5×105 (106) particles per second.

The Micromegas technology can be used to construct very powerful detectors for low background, low energy measurements. A Micromegas X-ray detector has been used to search for solar axions in the CAST experiment at CERN. The detector has an active area of 7 cm × 7 cm, a very good x-y position, and a good energy resolution. It is built using low radioactivity materials and it is capable of low energy X-ray measurements of a few hundred eV. Despite the lack of external shielding the obtained background level is below 5 × 105 counts/keV/cm2/s. The detector is being upgraded with a reduced active area Micromegas module, a focusing X-Ray telescope and shielding, which are expected to further reduce the background by about two orders of magnitude.