Micromegas at low pressure for beam tracking

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, 13030 ps, which is compatible with the results obtained with wire chambers.Gobierno de España FPA2009-0884

Development of a tracking system of exotic nuclear beams for FAIR

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

New neutron detector based on Micromegas technology for ADS projects

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

A Time Projection Chamber with GEM-Based Readout

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.Comment: 22 pages, 19 figure

Discovery of a big void in Khufu’s Pyramid by observation of cosmic-ray muons

International audienceThe 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$^1$ . 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 30m minimum) above the Grand Gallery, which constitutes the first major inner structure found in the Great Pyramid since the 19$^{th}$ century. This void, named ScanPyramids Big Void, was first observed with nuclear emulsion films installed in the Queen’s chamber (Nagoya University), then confirmed with scintillator hodoscopes set up in the same chamber (KEK) and re-confirmed with gas detectors12 outside of the pyramid (CEA)This large void has therefore been detected with a high confidence by three different muon detection technologies andthree 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 heritag

A time projection chamber with GEM-based readout

International audienceFor 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 1T solenoidal field and read out with three independent Gas Electron Multiplier (GEM) based readout modules, are reported. The TPC was exposed to a 6GeV 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

Double-hit separation and dE/dx resolution of a time projection chamber with GEM readout

A time projection chamber (TPC) with micropattern gaseous detector (MPGD) readout is investigated as main tracking device of the International Large Detector (ILD) concept at the planned International Linear Collider (ILC). A prototype TPC equipped with a triple gas electron multiplier (GEM) readout has been built and operated in an electron test beam. The TPC was placed in a 1 T solenoidal field at the DESY II Test Beam Facility, which provides an electron beam up to 6 GeV/c. The performance of the readout modules, in particular the spatial point resolution, is determined and compared to earlier tests. New studies are presented with first results on the separation of close-by tracks and the capability of the system to measure the specific energy loss dE/dx. This is complemented by a simulation study on the optimization of the readout granularity to improve particle identification by dE/dx

Double-hit separation and dE/dx resolution of a time projection chamber with GEM readout

A time projection chamber (TPC) with micropattern gaseous detector (MPGD) readout is investigated as main tracking device of the International Large Detector (ILD) concept at the planned International Linear Collider (ILC). A prototype TPC equipped with a triple gas electron multiplier (GEM) readout has been built and operated in an electron test beam. The TPC was placed in a 1 T solenoidal field at the DESY II Test Beam Facility, which provides an electron beam up to 6 GeV/c. The performance of the readout modules, in particular the spatial point resolution, is determined and compared to earlier tests. New studies are presented with first results on the separation of close-by tracks and the capability of the system to measure the specific energy loss dE/dx. This is complemented by a simulation study on the optimization of the readout granularity to improve particle identification by dE/dx.Comment: 28 pages, 27 figure

A time projection chamber with GEM-based readout

International audienceFor 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 1T solenoidal field and read out with three independent Gas Electron Multiplier (GEM) based readout modules, are reported. The TPC was exposed to a 6GeV 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