Caracterización del prototipo NEXT-MM del experimento NEXT para la búsqueda de la desintegración doble beta sin neutrinos del isótopo Xe136

La desintegración doble beta sin neutrinos es una reacción de gran interés en el marco de la física actual, ya que su detección implicaría la existencia de una desintegración imposible para el Modelo Estándar. El experimento NEXT consiste en una TPC de alta presión con 100\,kg de Xenón enriquecido con 136Xe, para medir ambos modos de desintegración doble beta. El prototipo NEXT-MM, desarrollado en la UZ, está basado en detectores Micromegas. La buena resolución tanto energética como espacial y su escalabilidad, lo hacen ideal para esta tarea. En primer lugar, se ha revisado y modificado el software de simulación, reconocimiento de trazas y análisis de los datos de la simulación para adaptarlos a la geometría del detector; así como definido una fuente radiactiva específica para que sea lo más similar posible a la que se utiliza en el laboratorio. Se han incorporado y modificado observables para que puedan ser comparados directamente con las medida y se ha visto también que mediante el uso de los observables podemos obtener información sobre muchos aspectos de los eventos que ocurren en el volumen activo del gas. Además, se ha caracterizado experimentalmente un detector micromegas (MM5) extra para NEXT-MM. Esta caracterización era de especial interés ya que la micromegas MM5 no se había utilizado todavía y podría presentar unas condiciones de funcionamiento mejores que algunas de las que están instaladas en el prototipo actualmente. Para caracterizar la micromegas se ha utilizado un sistema llamado TREX-TF con un diseño muy similar a NEXT-MM pero de dimensiones más reducidas, lo que hace más práctico para este tipo de caracterizaciones. Las conclusiones de la caracterización son positivas, ya que la micromegas MM5 no está limitada por su transparencia y además presenta una ganancia mayor que dos de las tres micromegas de NEXT-MM

Weighing the Solar Axion

Axion helioscopes search for solar axions and axion-like particles via inverse Primakoff conversion in strong laboratory magnets pointed at the Sun. While helioscopes can always measure the axion coupling to photons, the conversion signal is independent of the mass for axions lighter than around 0.02 eV. Masses above this value on the other hand have suppressed signals due to axion-photon oscillations which destroy the coherence of the conversion along the magnet. However, the spectral oscillations present in the axion conversion signal between these two regimes are highly dependent on the axion mass. We show that these oscillations are observable given realistic energy resolutions and can be used to determine the axion mass to within percent level accuracies. Using projections for the upcoming helioscope IAXO, we demonstrate that $>3\sigma$ sensitivity to a non-zero axion mass is possible between $3 \times 10^{-3}$ and $10^{-1}$ eV for both the Primakoff and axion-electron solar fluxes.Comment: 13 pages, 7 figures, matches published version, code available at http://cajohare.github.io/IAXOmas

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

Ultra-low background Micromegas X-ray detectors for Axion searches in IAXO and BabyIAXO

The main concept of a particle gaseous detector is that radiation passing through a gas can ionize atoms or molecules if the energy delivered is higher than the ionization potential of the gas. This gaseous detector concept has been adopted by many particle physics detection techniques for rare event searches, the most representative being the Time Projection Chambers (TPCs). These detectors consist of a gas chamber, where an electric field is applied, and some sort of patterned anode plane, where the charge amplification and detection occur. Specifically, Micromegas readouts are of interest due to their flexible designs in terms of patterning, high granularity, good energy resolution and potential radiopurity. Axions are hypothetical elementary particles that were proposed as the most compelling solution to the strong CP problem of Quantum Chromodynamics (QCD). And beyond the QCD predicted axions, it extends a whole category of particles called Axion-Like Particles (ALPs), that are well motivated by different extensions of the Standard Model (SM). Some axions and ALPs hints are found when they are invoked as a solution for unexplained astrophysical observations, like the intergalactic transparency to very high energetic (VHE) photons or the anomalous cooling of stellar objects. Moreover, due to their weakly interacting nature, they are suitable candidates to be part or the totality of the dark matter of the Universe. An interesting property from the experimental point of view is that axions and photons can oscillate in the presence of a magnetic field, which is called the Primakoff effect. Well known solar physics predict the emission of axions from the core of the Sun via plasma photons conversion. These axions would escape from the Sun and travel to Earth, where they could convert back to x-ray photons via inverse Primakoff effect inside a laboratory magnet. Helioscopes are experiments that use this idea to search for solar axions. A powerful magnet tracks the Sun so an axion-photon conversion can occur, and then, x-ray detectors would be able to measure an excess over the background at keV energies. The International AXion Observatory (IAXO) is a proposed helioscope with a dedicated magnet and x-ray optics specially built for axion searches, and also, with improved low background microbulk Micromegas x-ray detectors. The sensitivity of the experiment would allow IAXO to probe completely unexplored regions of the parameter space, having potential for discovery. In the context of the IAXO international Collaboration, a BabyIAXO helioscope has been proposed for a short-term commissioning in order to prove all the technologies required for IAXO. In this context, a deep understanding of the radioactive background of the detector is important in order to identify the most problematic sources and shield the detectors from them. To implement them and prove the IAXO background requirements, a IAXO detector prototype has been built in the University of Zaragoza, called IAXO-D0. The work of this thesis has consisted in two parts: the computational simulation of a background model of IAXO-D0, and the commissioning, data taking, analysis and background study of the prototype. To produce the IAXO-D0 background model, the new REST framework has been used. It is a C++/root based software that provides tools for acquisition, storage, simulation, treatment and analysis of data taken with gaseous TPCs, allowing direct comparison between experimental data and simulations. The IAXO-D0 detector and shielding geometry has been implemented in the REST software and a complete simulation of all the known background sources has been carried out. Also, a simulation of [0,10] keV x-rays has allowed characterizing x-ray induced events, and discrimination cuts have been defined from their observables. These discrimination cuts have been applied to all of the individual background source. From this work, a low background level has been obtained for the IAXO-D0 prototype, which is of the same order of the IAXO pathfinder background. Furthermore, it was learnt that cosmic neutrons are a very important source of background that persists after the discrimination process. This result is a motivation to revise the shielding designs for BabyIAXO. On the other hand, during 2017, the IAXO-D0 prototype was commissioned at the University of Zaragoza, along with the gas system installation, the electronics upgrade and the Micromegas characterization. The first data taking campaign was carried out during 2018, with approximately 400 hours of background data and daily calibrations with a 109Cd source. REST software has also been used for the data processing and analysis, and the same strategy has been followed: an x-ray characterization has been performed using the data of a long 109Cd calibration run, and a representative population of events produced by the 8 keV x-rays form the copper fluorescence has been chosen to define the discrimination cuts. Then, background runs have been calibrated in energy, and the discrimination cuts have been applied. The resulting experimental background of the IAXO-D0 prototype is in agreement with the simulations and expectations. Overall, both experimental and simulated background levels are in good agreement, and some better knowledge of the cosmic contribution to the background has been learnt. From this work, some paths are left to be explored towards the BabyIAXO commissioning, like the revision of the shielding to reject cosmic neutrons, the computation of a background model for xenon based mixtures, the implementation of the cosmic vetoes at the IAXO-D0 prototype or the optimization of the code to obtain even more realistic simulations and better statistics

The Forward Physics Facility at the High-Luminosity LHC

International audienceHigh energy collisions at the High-Luminosity Large Hadron Collider (LHC) produce a large number of particles along the beam collision axis, outside of the acceptance of existing LHC experiments. The proposed Forward Physics Facility (FPF), to be located several hundred meters from the ATLAS interaction point and shielded by concrete and rock, will host a suite of experiments to probe Standard Model (SM) processes and search for physics beyond the Standard Model (BSM). In this report, we review the status of the civil engineering plans and the experiments to explore the diverse physics signals that can be uniquely probed in the forward region. FPF experiments will be sensitive to a broad range of BSM physics through searches for new particle scattering or decay signatures and deviations from SM expectations in high statistics analyses with TeV neutrinos in this low-background environment. High statistics neutrino detection will also provide valuable data for fundamental topics in perturbative and non-perturbative QCD and in weak interactions. Experiments at the FPF will enable synergies between forward particle production at the LHC and astroparticle physics to be exploited. We report here on these physics topics, on infrastructure, detector, and simulation studies, and on future directions to realize the FPF's physics potential

The Forward Physics Facility at the High-Luminosity LHC

High energy collisions at the High-Luminosity Large Hadron Collider (LHC) produce a large number of particles along the beam collision axis, outside of the acceptance of existing LHC experiments. The proposed Forward Physics Facility (FPF), to be located several hundred meters from the ATLAS interaction point and shielded by concrete and rock, will host a suite of experiments to probe standard model (SM) processes and search for physics beyond the standard model (BSM). In this report, we review the status of the civil engineering plans and the experiments to explore the diverse physics signals that can be uniquely probed in the forward region. FPF experiments will be sensitive to a broad range of BSM physics through searches for new particle scattering or decay signatures and deviations from SM expectations in high statistics analyses with TeV neutrinos in this low-background environment. High statistics neutrino detection will also provide valuable data for fundamental topics in perturbative and non-perturbative QCD and in weak interactions. Experiments at the FPF will enable synergies between forward particle production at the LHC and astroparticle physics to be exploited. We report here on these physics topics, on infrastructure, detector, and simulation studies, and on future directions to realize the FPF's physics potential