During 2016 the Experimental Division’s activities focused on 10 main projects, most of them long-term efforts. These projects span the fields of High Energy Physics, Astrophysics and Cosmology, and include the development of detectors for Medical Imaging applications as well as related instrumentation projects.
High Energy Physics is represented by three major, long-term projects:
1.ATLAS, at the Large Hadron Collider (LHC) of CERN. In 2016, LHC continued its Run-2 operations at the highest ever center-of-mass energy of 13 TeV. This broader energy range, together with the excellent performances of accelerator and detector alike, has greatly increased the possibility of new discoveries. While the analysis of the 2016 data has not confirmed the hint of a possible new particle with a mass around 750 GeV reported in 2015, the record-breaking performance of the accelerator, providing 60% more collisions than anticipated in the year, has resulted in a vast increase in the available data for ATLAS analyses. The IFAE group has produced a number of high-profile results with the early Run-2 data, particularly in searches for monojets, for additional Higgs bosons, and for the associated production of Higgs bosons with top and anti-top quarks. Furthermore, two PhD theses were defended in the group, on searches for top quark decays to Higgs and for the supersymmetric partner of the top quark, respectively. PIC, as a Tier-1 LHC data-processing center, managed to cope admirably with the deluge of LHC data in 2016, keeping his world-leading reliability score. Furthermore, in 2016, the ATLAS Tier-2 analysis facility, also hosted at PIC, processed over 32 billion events and executed 1.4 million jobs.
2.The ATLAS upgrade, in preparation for a major renewal of the detector to take place by 2025. Here the IFAE group focuses on pixelated semiconductor detectors for tracking in the central and very forward regions. The IFAE group made critical contributions to the ATLAS Insertable B-Layer (IBL), which included the first application of 3D pixels to a high-energy physics experiment. IBL was installed and commissioned in 2014, and successfully entered operation in 2015. In 2016, the group finished the production, installation and commissioning of the first arm of the ATLAS Forward Proton (AFP) detector, which continues the use of 3D pixel detectors and was successfully operated throughout the year. All this has provided the group with the track- record needed to play a leading role in the upgrade of the entire inner tracker of ATLAS, necessary for the LHC high-luminosity operations beyond 2025. In parallel, the group has continued its R&D into new promising technologies such as Low-Gain Avalanche Detectors (LGAD), with excellent timing capabilities, and monolithic HVCMOS pixel detectors, in view of their possible use in the ATLAS upgrade and other applications.
3.T2K, a neutrino long base-line experiment in Japan. In 2012, after recovering from the devastating earthquake of 2011, T2K confirmed the earlier results on the oscillation of muon neutrinos into electron neutrinos. In addition, T2K published in 2013 the most precise measurements to-date of muon neutrino disappearance parameters. In May 2014, T2K started a new run with anti-neutrinos. First analyses, published in summer 2015, provided the most precise muon anti-neutrino disappearance result to-date. In 2016, T2K presented the first combined analysis with about ~50% neutrino and ~50% anti-neutrino data, which provided the first possible hints of the existence of CP violation in the neutrino sector, a most fundamental result, if confirmed. The group at IFAE contributed to this effort leading the measurements in T2K’s near detector necessary for the crucial normalization of the incoming muon- (anti)neutrino flux. In 2016, the group continued its involvement in WA105, a large liquid-argon detector at CERN where the new detection techniques necessary for the future large DUNE long-baseline experiment in the US are being tested.
IFAE’s Astrophysics activities are centered on ground-based detection of very high-energy gamma rays from astrophysical and cosmological sources.
4.MAGIC, located on the Roque de los Muchachos on the Canary Island of La Palma, operates a recently upgraded stereoscopic system of two 17m-diameter telescopes. Since its inception, IFAE has played a major role in the design, construction, operation and scientific exploitation of MAGIC. For instance, in 2016, IFAE scientists led six of the 15 papers published by MAGIC, including an accurate measurement of the extragalactic background light wavelength at around 1 μm and the first search for dark matter particles in cooperation with the Fermi-LAT satellite, covering the mass range from 10 GeV to 100 TeV. Furthermore, in 2016, the group has led several efforts aimed at expanding both the energy range and duty cycle of the MAGIC telescopes, including the design and installation of a new filter system that allows MAGIC to operate during full moon. During 2016, IFAE has continued to manage the MAGIC Tier-0 data center at PIC, as well as the common fund of the collaboration.
5.CTA, a worldwide collaboration that will build two multi-telescope observatories, in the Northern and Southern hemispheres, is now entering its construction phase. IFAE is involved in major aspects of this project, at the technical and the top management levels, and in particular in the design and construction of the largest telescopes (LST) in CTA. During 2016, the final agreement was signed to site the CTA Northern observatory in the Canary island of La Palma, a major breakthrough in which IFAE played a crucial role. During 2016, IFAE coordinated the construction of the bogies of the first LST telescope, which will be installed in La Palma in late 2017. The integration of the camera of this first LST will take place in 2017 at IFAE, which is also taking care of the power system and developing the camera control system.
The Observational Cosmology program at IFAE began by joining an existing project, DES. In 2007 a new project, PAU, was launched. Other projects such as Euclid, DESI and LSST have followed.
6.The DES (Dark Energy Survey) collaboration at the Blanco telescope in Cerro Tololo (Chile) successfully completed in 2016 the third of its five seasons, which will lead to the measurement of position, redshift and shape for about 300 million galaxies in the Southern sky. A plethora of results from the Science Verification season in 2012/13 became available in 2015 and 2016, including the first results from the weak lensing technique. Five of the 35 papers published by DES in 2016 were (co-)led by IFAE scientists, including new results on gravitational lensing around foreground galaxies, on lensing around cosmological voids, and on the correlation between the temperature of the Cosmic Microwave Background radiation and the location of super-clusters of galaxies and super-voids in the sky. In 2015, IFAE joined the Dark Energy Spectroscopic Instrument (DESI) collaboration, which will gather spectra for over 30 million galaxies and quasars, producing an unprecedented 3D map of the Universe. Together with its partners at ICE (IEEC-CSIC), CIEMAT and IFT/UAM, the IFAE group is responsible for the de- sign and construction of the Guiding, Focusing and Alignment (GFA) cameras of the DESI instrument. A first GFA prototype was delivered to the Lawrence Berkeley National Lab in early August. After its integration into a prototype of the full focal plane of DESI, the GFA saw its first light in late August at the Mayall 4-m telescope in Arizona. Furthermore, in December 2016, IFAE joined the Large Synoptic Survey Telescope (LSST) project, which will be the leading imaging galaxy survey in the next decade, much like DES is in this decade. LSST will study the properties of the dark energy using an unprecedented sample of four billion galaxies.
7.PAU (Physics of the Accelerating Universe) is an IFAE-led Spanish collaboration funded by a Consolider-Ingenio 2010 project. In June 2015, the PAU camera (PAUCam), built at IFAE, was installed and commissioned at the William Herschel Telescope (WHT) in La Palma, Canary Islands. The camera then went through two short periods of scientific verification in November 2015 (almost useless due to terrible weather) and April 2016. The preliminary analysis of this data set indicates that the camera performs according to the specifications. In November 2016, the PAU Survey international collaboration started to use PAUCam to carry out a very precise photometric-redshift survey in order to help understand the properties of dark energy.
8.Euclid is a European Space Agency (ESA) satellite mission within the Cosmic Vision program, which will be launched in 2020. Its main goal is to determine the properties of dark energy with unprecedented precision using both weak lensing and galaxy clustering probes. IFAE is responsible for the design and production of the Filter Wheel Assembly (FWA) of the infrared focal plane, which being a moving part in space, deserves extra care. In 2016, the team at IFAE delivered to ESA the Structural and Thermal Model (STM) of the FWA as part of the STM for the whole Near-Infrared Spectrometer and Photometer (NISP), which successfully passed the Consolidation Design Review in July 2016. IFAE also delivered the necessary Ground Segment Equipment (GSE), a mounting tool, and is designing the additional GSE, a cryostat, needed for the additional tests that will take place in 2017.
The focus of the applied physics research at IFAE is to develop sensor technologies with applications in medical imaging, high-energy physics and other scientific or industrial fields.
9.The Medical Imaging group has developed a novel approach to Positron Emission Tomography, funded by an ERC Advanced Grant. The approach is based on a finely pixelized CdTe detector read out by a 100-channel ASIC designed at IFAE. 2015 saw the conclusion of the full production of the 180 VIP single-layer detectors and the box that holds them to form the PET detector. First results are expected in 2017. In 2014, the group started a new initiative (ERICA) in the field of X-ray line detection with quality control and security applications. Du- ring 2015, a first prototype of the ERICA ASIC was produced. The second iteration, produced in 2016, was thoroughly tested and found to deliver the expected performance. In 2016, the group started a new RIS3CAT project to develop a 3D biopsy system in collaboration with several public and private partners (CNM-IMB, the Parc Taulí hospital, IDNEO Technologies SL, and VENTURA Medical Technologies). IFAE's main role is the development of a fully digital X-ray camera for the system.
10.Several other instrumentation projects produced exciting results in 2016. In particular, a novel light-detector system based on silicon photomultipliers coupled to wave-length shifters has been developed and is ready to be tested in real-life operation in MAGIC. Furthermore, in 2016 IFAE started a collaboration with a group at ICIQ to study the possible use of organic solar cells as photodetectors.
The activities of the Theory Division during 2016 continued along three lines: Standard Model Physics, Beyond the Standard Model, and Astroparticle Physics/Cosmology.
The main research themes pursued in the Standard Model (SM) group of the IFAE theory division during 2016 included: a new determination of the strong coupling constant using tau-lepton decays and including quark-hadron duality violations; the description of heavy-meson bound states and ex-traction of heavy quark masses (leading to a PhD thesis); leptonic and radiative decays of η and η’ mesons; semi-leptonic and hadronic decays of B and Bs mesons; and the behavior of perturbation theory at high orders.
In 2016 the BSM subgroup continued its search for theories that might supersede the Standard Mo- del of particle physics and cure the theoretical and observational problems that afflict it. Some of the topics covered include: extending supersymmetry with custodial triplets (the subject of a 2016 PhD thesis); an attempt to explain the anomalies recently reported in several B-meson decays using warped extra dimensions; continuing studies concerning a possible composite structure of the Higgs boson and how to discern it at the LHC; and studies of the possible instability of the effective potential of the Standard Model at very high energy.
Astroparticle physics and particle cosmology are recent fields of research at the intersection between particle physics, astrophysics and cosmology. The goal is to exploit our knowledge of astrophysical and cosmological phenomena to answer fundamental physics questions, and vice-versa. The topics on which the members of this group focused their work in 2016 include: the study of the consistency of scalar potentials from quantum de Sitter space, with possible implications in both the hierarchy and cosmological-constant problems; and the continuation of the very productive study of applications of the gauge/gravity duality to condensed matter problems (leading to a 2016 PhD thesis).