Showing papers by "J. M. Carmona published in 2007"
CERN1, Russian Academy of Sciences2, University of Zaragoza3, Max Planck Society4, University of Chicago5, Technische Universität Darmstadt6, Aristotle University of Thessaloniki7, University of Freiburg8, University of British Columbia9, Goethe University Frankfurt10, University of Patras11, Brookhaven National Laboratory12, Fermilab13
TL;DR: In this paper, the CERN Axion Solar Telescope (CAST) set-up with improved conditions in all detectors was used to search for solar axions or similar particles that couple to two photons.
Abstract: We have searched for solar axions or similar particles that couple to two photons by using the CERN Axion Solar Telescope (CAST) set-up with improved conditions in all detectors. From the absence of excess x-rays when the magnet was pointing to the Sun, we set an upper limit on the axion–photon coupling of gaγ<8.8 × 10−11 GeV−1 at 95% CL for . This result is the best experimental limit over a broad range of axion masses and for also supersedes the previous limit derived from energy-loss arguments on globular cluster stars.
415 citations
TL;DR: One of the three x-ray detectors of the CERN Axion Solar Telescope (CAST) experiment searching for solar axions is a time projection chamber (TPC) with a multi-wire proportional counter (MWPC) as a readout structure as discussed by the authors.
Abstract: One of the three x-ray detectors of the CERN Axion Solar Telescope (CAST) experiment searching for solar axions is a time projection chamber (TPC) with a multi-wire proportional counter (MWPC) as a readout structure. Its design has been optimized to provide high sensitivity to the detection of the low intensity x-ray signal expected in the CAST experiment. A low hardware threshold of 0.8?keV is set to a safe level during normal data taking periods, and the overall efficiency for the detection of photons coming from conversion of solar axions is 62%. Shielding has been installed around the detector, lowering the background level to 4.10 ? 10?5?counts?cm?2?s?1?keV?1 between 1 and 10?keV. During phase I of the CAST experiment the TPC has provided robust and stable operation, thus contributing with a competitive result to the overall CAST limit on axion?photon coupling and mass.
49 citations
TL;DR: In this paper, a Time Projection Chamber (TPC) with a multi-wire proportional counter (MWPC) readout structure was used for the detection of solar axions in the CAST experiment.
Abstract: One of the three X-ray detectors of the CAST experiment searching for solar axions is a Time Projection Chamber (TPC) with a multi-wire proportional counter (MWPC) as a readout structure. Its design has been optimized to provide high sensitivity to the detection of the low intensity X-ray signal expected in the CAST experiment. A low hardware threshold of 0.8 keV is safely set during normal data taking periods, and the overall efficiency for the detection of photons coming from conversion of solar axions is 62 %. Shielding has been installed around the detector, lowering the background level to 4.10 x 10^-5 counts/cm^2/s/keV between 1 and 10 keV. During phase I of the CAST experiment the TPC has provided robust and stable operation, thus contributing with a competitive result to the overall CAST limit on axion-photon coupling and mass.
26 citations
01 Aug 2007
15 citations
TL;DR: In this article, a detailed analysis based on the detector characteristics, the background radiation at the CERN Axion Solar Telescope (CAST) site, simulations and experimental results has allowed us to design a shielding which reduces the background level by a factor of ~4 compared to the detector without shielding, depending on its position, in the energy range between 1 and 10?keV.
Abstract: Sunset solar axions traversing the intense magnetic field of the CERN Axion Solar Telescope (CAST) experiment may be detected in a time projection chamber (TPC) detector, as point-like x-rays signals. These signals could be masked, however, by the inhomogeneous background of materials in the experimental site. A detailed analysis, based on the detector characteristics, the background radiation at the CAST site, simulations and experimental results, has allowed us to design a shielding which reduces the background level by a factor of ~4 compared to the detector without shielding, depending on its position, in the energy range between 1 and 10?keV. Moreover, this shielding has improved the homogeneity of background measured by the TPC.
7 citations
TL;DR: In this article, an interpretation of neutrino oscillations based on a modification of relativistic quantum field theory at low energies, without the need to introduce a neutrinos mass, is seen to be compatible with all observations.
Abstract: An interpretation of neutrino oscillations based on a modification of relativistic quantum field theory at low energies, without the need to introduce a neutrino mass, is seen to be compatible with all observations.
3 citations
University of South Carolina1, CERN2, University of Zaragoza3, Max Planck Society4, University of Chicago5, Technische Universität Darmstadt6, Aristotle University of Thessaloniki7, University of Freiburg8, Russian Academy of Sciences9, University of British Columbia10, Goethe University Frankfurt11, University of Patras12
21 Sep 2007-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: The CERN Axion Solar Telescope (CAST) as mentioned in this paper searches for solar axions using the 9.0 T strong and 9.26 T long transverse magnetic field of a twin aperture LHC test magnet, where axions could be converted into X-rays via reverse Primakoff process.
Abstract: The CERN Axion Solar Telescope (CAST) is searching for solar axions using the 9.0 T strong and 9.26 m long transverse magnetic field of a twin aperture LHC test magnet, where axions could be converted into X-rays via reverse Primakoff process. Here we explore the potential of CAST to search for 14.4 keV axions that could be emitted from the Sun in M1 nuclear transition between the first, thermally excited state, and the ground state of 57 Fe nuclide. Calculations of the expected signals, with respect to the axion–photon coupling, axion–nucleon coupling and axion mass, are presented in comparison with the experimental sensitivity.
1 citations