An InGrid based Low Energy X-ray Detector

An X-ray detector based on the combination of an integrated Micromegas stage with a pixel chip has been built in order to be installed at the CERN Axion Solar Telescope. Due to its high granularity and spatial resolution this detector allows for a topological background suppression along with a detection threshold below $1\,\text{keV}$. Tests at the CAST Detector Lab show the detector's ability to detect X-ray photons down to an energy as low as $277\,\text{eV}$. The first background data taken after the installation at the CAST experiment underline the detector's performance with an average background rate of $5\times10^{-5}\,/\text{keV}/\text{cm}^2/\text{s}$ between 2 and $10\,\text{keV}$ when using a lead shielding.Comment: 4 pages, 5 figures, Contributed to the 10th Patras Workshop on Axions, WIMPs and WISPs, CERN, June 29 to July 4, 201

Signatures for Solar Axions/WISPs

Standard solar physics cannot account for the X-ray emission and other puzzles, the most striking example being the solar corona mystery. The corona temperature rise above the non-flaring magnetized sunspots, while the photosphere just underneath becomes cooler, makes this mystery more intriguing. The paradoxical Sun is suggestive of some sort of exotic solution, axions being the (only?) choice for the missing ingredient. We present atypical axion signatures, which depict solar axions with a rest mass max ~17 meV/c2. Then, the Sun has been for decades the overlooked harbinger of new particle physics.Comment: To appear in the proceedings of the 6th Patras Workshop, Zurich 5-9 July 201

First results of the CAST-RADES haloscope search for axions at 34.67 μeV

We present results of the Relic Axion Dark-Matter Exploratory Setup (RADES), a detector which is part of the CERN Axion Solar Telescope (CAST), searching for axion dark matter in the 34.67μeV mass range. A radio frequency cavity consisting of 5 sub-cavities coupled by inductive irises took physics data inside the CAST dipole magnet for the first time using this filter-like haloscope geometry. An exclusion limit with a 95% credibility level on the axion-photon coupling constant of gaγ & 4 × 10−13 GeV−1 over a mass range of 34.6738μeV < ma < 34.6771μeV is set. This constitutes a significant improvement over the current strongest limit set by CAST at this mass and is at the same time one of the most sensitive direct searches for an axion dark matter candidate above the mass of 25μeV. The results also demonstrate the feasibility of exploring a wider mass range around the value probed by CAST-RADES in this work using similar coherent resonant cavitiesWe wish to thank our colleagues at CERN, in particular Marc Thiebert from the coating lab, as well as the whole team of the CERN Central Cryogenic Laboratory for their support and advice in speci c aspects of the project. We thank Arefe Abghari for her contributions as the project's summer student during 2018. This work has been funded by the Spanish Agencia Estatal de Investigacion (AEI) and Fondo Europeo de Desarrollo Regional (FEDER) under project FPA-2016-76978-C3-2-P and PID2019-108122GB-C33, and was supported by the CERN Doctoral Studentship programme. The research leading to these results has received funding from the European Research Council and BD, JG and SAC acknowledge support through the European Research Council under grant ERC-2018-StG-802836 (AxScale project). BD also acknowledges fruitful discussions at MIAPP supported by DFG under EXC-2094 { 390783311. IGI acknowledges also support from the European Research Council (ERC) under grant ERC-2017-AdG-788781 (IAXO+ project). JR has been supported by the Ramon y Cajal Fellowship 2012-10597, the grant PGC2018-095328-B-I00(FEDER/Agencia estatal de investigaci on) and FSE-GA2017-2019-E12/7R (Gobierno de Aragón/FEDER) (MINECO/FEDER), the EU through the ITN \Elusives" H2020-MSCA-ITN-2015/674896 and the Deutsche Forschungsgemeinschaft under grant SFB-1258 as a Mercator Fellow. CPG was supported by PROMETEO II/2014/050 of Generalitat Valenciana, FPA2014-57816-P of MINECO and by the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreements 690575 and 674896. AM is supported by the European Research Council under Grant No. 742104. Part of this work was performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344

Contribution to the search for solar axions in the CAST experiment

The CERN Axion Solar Telescope (CAST) is an implementation of the axion helioscope with the highest sensitivity to date. In the present thesis the results of the analysis of one of the Micromegas detectors in CAST (sunrise side) for the 2009 and 2010 data taking periods are presented. A new detector lab has been realized at CERN (162 S-065) with a variable energy calibration system based on an X-ray beam line built at the Max-Planck-Institut für extraterrestrische Physik/Garching (MPE). The purpose of this work is to calibrate for the first time the present and future CAST detectors, in a number of energies and test the efficiency of the software selection criteria.The results of the measurements in the lab were used in the analysis of the data acquired in 2009 and 2010 with the sunrise Micromegas detector of CAST.\nThe data are consistent with no axion signal, thus a limit in the coupling constant of axions to photons is extracted in the axion mass range 0.655 -1.01 eV/c2: gαγ ≤ 3.9×10-10 GeV-1 at 95% CL, which is expected to be slightly improved by the contribution of the rest of the detectors

The New Small Wheel project of ATLAS

The LHC plans to increase its instantaneous luminosity to 7.5 E34&nbsp;cm-2 s−1. With this increase, substantial degradation of the tracking performance was expected both in efficiency and resolution in the Small Wheel&nbsp;(SW) region of the ATLAS detector. The New Small Wheels (NSW), which have replaced the SW, will have the desired performance and will introduce trigger information from the SW region. The new system is a combination of precision tracking and trigger detectors with excellent real-time spatial and time resolution. Each NSW consists of 16 sectors (32 for both wheels) with 16 detector planes. The multilayers comprise of small-strip Thin Gap Chambers (sTGC) and MicroMegas (MM) detector planes. The integration of the sectors on the NSWs started at the end of 2019 in building 191. Each sector has been commissioned in parallel to the sequential integration of the next. Both wheels were fully commissioned on the surface before their transport to P1 where, after their installation at ATLAS, the commissioning restarted. An overview of the integration and commissioning efforts will be presented, both on the surface and underground, detailing the challenges along the way. The current status and plans of the preparations for data taking will be summarised. &nbsp;</p

Integration and commissioning of ATLAS New Small Wheel Micromegas detectors with electronics at CERN

The LHC at CERN plans to have a series of upgrades to increase its instantaneous luminosity to 7.5×10^34 cm−2s−1. The luminosity increase drastically impacts the ATLAS trigger and readout data rates. The inner-most station of the ATLAS muon spectrometer, the so-called Small Wheels, will be replaced with a New Small Wheel (NSW) system, consisting of Micromegas (MM) and sTGC detectors, which is expected to be installed in the ATLAS underground cavern at the end of 2020. With the final MM quadruplets (modules) already produced from the different construction sites, the integration activities of the modules into the final, fully equipped MM double-wedges, that are then installed on the wheel structure, are currently in full swing in the integration facility at CERN. One crucial part of the integration workflow is the installation, testing and validation of the on-detector electronics & readout chain for a very large system with a more than 2.1 M electronic channels in total. These include 4k MM Front-End Boards (MMFE8), custom printed circuit boards each one housing eight 64-channel VMM Application Specific Integrated Circuits (ASICs) that interface with the ATLAS Trigger and Data Acquisition (TDAQ) system through 1k data-driver Cards (ADDC & L1DDC, respectively). The readout chain is based on optical link technology (GigaBit Transceiver links) connecting the backend to the front-end electronics via the Front-End LInk eXchange (FELIX), is a newly developed system that will serve as the next generation read out driver for ATLAS. Experience and performance results from the first large-scale electronics integration tests performed at CERN on final NSW MM double-wedges, including system validation tests with cosmic-rays, will be presented

Integration and commissioning of ATLAS New Small Wheel Micromegas detectors with electronics at CERN

The LHC at CERN plans to have a series of upgrades to increase its instantaneous luminosity to 7.5×1034 cm−2s−1. The luminosity increase drastically impacts the ATLAS trigger and readout data rates. The inner-most station of the ATLAS muon spectrometer, the so-called Small Wheels, will be replaced with a New Small Wheel (NSW) system, consisting of Micromegas (MM) and sTGC detectors, which is expected to be installed in the ATLAS underground cavern at the end of 2020. With the final MM quadruplets (modules) already produced from the different construction sites, the integration activities of the modules into the final, fully equipped MM double-wedges, that are then installed on the wheel structure, are currently in full swing in the integration facility at CERN. One crucial part of the integration workflow is the installation, testing and validation of the on-detector electronics & readout chain for a very large system with a more than 2.1 M electronic channels in total. These include ~4K MM Front-End Boards (MMFE8), custom printed circuit boards each one housing eight 64-channel VMM Application Specific Integrated Circuits (ASICs) that interface with the ATLAS Trigger and Data Acquisition (TDAQ) system through ~1K data-driver Cards (ADDC & L1DDC, respectively). The readout chain is based on optical link technology (GigaBit Transceiver links) connecting the backend to the front-end electronics via the Front-End LInk eXchange (FELIX), is a newly developed system that will serve as the next generation read out driver for ATLAS. Experience and performance results from the first large-scale electronics integration tests performed at CERN on final NSW MM double-wedges, including system validation tests with cosmic-rays, will be presented

Latest results of cast and future prospects

CERN Axion Solar Telescope (CAST) is currently the most sensitive axion helioscope designed to search for axions and axion-like particles produced in the Sun. CAST completed successfully the second part of CAST phase II where the magnet bores were lled with 3He gas at variable pressure scanning axion masses up to 1.2 eV In the absence of signal it has set the best experimental limit on the axion-photon coupling constant over a broad range of axion masses. In 2013 CAST has improved its sensitivity to solar axions with rest mass below 0.02 eV by upgrading the Micromegas detectors and it will continue in 2014 with the implementation of a second X-ray optic and a new type detector (InGRID). In addition, CAST has extended its sensitivity into the sub-keV energy range using a silicon detector (SDD), to search for solar chameleons. Thus, CAST also became sensitive to dark energy particles. A new generation axion helioscope (IAXO) aims to improve the current axion-photon coupling by 1-1.5 orders of magnitude. This will be possible by building a dedicated magnet and dedicated optics and X-ray detector

Συμβολή στην έρευνα των ηλιακών αξιονίων στο πείραμα CAST

The CERN Axion Solar Telescope (CAST) is an implementation of the axion helioscope with the highest sensitivity to date. In the present thesis the results of the analysis of one of the Micromegas detectors in CAST (sunrise side) for the 2009 and 2010 data taking periods are presented.A new detector lab has been realized at CERN (162 S-065) with a variable energy calibration system based on an X-ray beam line built at the Max-Planck-Institut für extraterrestrische Physik/Garching (MPE). The purpose of this work is to calibrate for the first time the present and future CAST detectors, in a number of energies and test the efficiency of the software selection criteria.The results of the measurements in the lab were used in the analysis of the data acquired in 2009 and 2010 with the sunrise Micromegas detector of CAST. The data are consistent with no axion signal, thus a limit in the coupling constant of axions to photons is extracted in the axion mass range 0.655 -1.01 eV/c2:gαγ ≤ 3.9×10-10 GeV-1 at 95% CLwhich is expected to be slightly improved by the contribution of the rest of the detectorsΤο Τηλεσκόπιο Ηλιακών Αξιονίων στο CERN (CAST), είναι μια εφαρμογή ενός ηλιοσκοπίου αξιονίων με τη μεγαλύτερη μέχρι στιγμής ευαισθησία. Στην παρούσα εργασία παρουσιάζονται τα αποτελέσματα της ανάλυσης των δεδομένων που λήφθηκαν με έναν από τους ανιχνευτές Micromegas του πειράματος CAST, της ανατολικής μεριάς, κατά τις περιόδους λήψης δεδομένων του 2009 και 2010.Για να καθοριστεί η επίδοση της επιλογής γεγονότων στην αναγνώριση των ακτίνων Χ ένα νέο εργαστήριο εξοπλίστηκε στο CERN, που περιλαμβάνει ένα σύστημα βαθμονόμησης μεταβλητής ενέργειας. Το σύστημα αυτό βασίζεται στη γραμμή ακτίνων Χ που κατασκευάσθηκε στο ινστιτούτο Max-Planck-Institut für extraterrestrische Physik/Garching (MPE). Σκοπός του εγχειρήματος αυτού είναι να βαθμονομηθούν για πρώτη φορά οι τωρινοί και μελλοντικοί ανιχνευτές που θα χρησιμοποιηθούν στο CAST σε μια πληθώρα ενεργειών μεταξύ 2 και 10 keV. Η μελέτη αυτή είναι απαραίτητη για την ανάλυση δεδομένων γιατί είναι ο μόνος τρόπος να οριστεί η απόδοση του λογισμικού επιλογής γεγονότων στο ενεργειακό εύρος ενδιαφέροντος.Τα αποτελέσματα της μελέτης χρησιμοποιήθηκαν στην περαιτέρω ανάλυση των δεδομένων που λήφθηκαν το 2009 και 2010 από τον ανιχνευτή Micromegas της ανατολικής μεριάς του πειράματος CAST. Τα δεδομένα αυτά είναι συμβατά με την έλλειψη σήματος αξιονίου και χρησιμοποιήθηκαν για να υπολογιστεί ένα όριο για την σταθερά σύζευξης αξιονίου – φωτονίου στην περιοχή μαζών αξιονίου 0.655 -1.01 eV/c2:gαγ ≤ 3.9×10-10 GeV-1 at 95% CLΤο οποίο θα βελτιωθεί από τη συνεισφορά και των υπολοίπων ανιχνευτών του πειράματος

Energy Dependent Features of X-ray Signals in a GridPix Detector

We report on the calibration of an argon/isobutane (97.7%/2.3%)-filled GridPix detector with soft X-rays (277 eV to 8 keV) using the variable energy X-ray source of the CAST Detector Lab at CERN. We study the linearity and energy resolution of the detector using both the number of pixels hit and the total measured charge as energy measures. For the latter, the energy resolution σE∕E is better than 10% (20%) for energies above 2 keV (0.5 keV). Several characteristics of the recorded events are studied.We report on the calibration of an argon/isobutane (97.7 %/2.3 %)-filled GridPix detector with soft X-rays (277 eV to 8 keV) using the variable energy X-ray source of the CAST Detector Lab at CERN. We study the linearity and energy resolution of the detector using both the number of hit pixels and the total measured charge as energy measures. For the latter, the energy resolution {\sigma}_E/E is better than 10 % (20 %) for energies above 2 keV (0.5 keV). Several characteristics of the recorded events are studied