On Wednesday, 10 October 2018, more than 200 guests from around the world gathered on the northern array site of the Cherenkov Telescope Array (CTA) to celebrate the inauguration of the prototype Large-Sized Telescope (LST). The telescope, named LST-1, is intended to become the first of four LSTs on the CTA-North site.

For the first time, astrophysicists have localized the source of a high energy cosmic neutrino originating outside the Milky Way. It is highly likely that the neutrino comes from a blazar in the Orion constellation. Scientists reached this interesting finding by combining a neutrino signal from IceCube with measurements from other instruments, e.g. the Fermi-LAT and MAGIC telescopes. This multi-messenger observation provided a clue to an unsolved mystery: the origin of cosmic rays.

In 2018 IFAE became a new member institution in the VIRGO collaboration. This opened a new long-term research line in IFAE related to GWs detection using terrestrial interferometry. A group of researches from IFAE has taken significant responsibilities in the VIRGO experiment related to the control of the stray light inside the experiment, which is considered a limiting factor for its sensitivity. The group plans for playing an important role in the ongoing commissioning, operations and upgrade of the interferometer.

The RD53A ASIC, a first prototype chip for the ATLAS ITk Pixel upgrade for the HL-LHC became available in 2018. The IFAE ATLAS Pixels group carried out the hybridization and assembly of the first 3D RD53A devices.Also the first studies of these devices before and after irradiation were performed.

The IFAE theory group has carried out a new analysis to extract the value of the strong coupling constant $\alpha_s$, using a recent compilation of the experimental data for the process $e^+e^- \rightarrow \mathrm{hadrons}$. Our analysis uses the method of Finite-Energy sum rules which enable us to assess, for the first time, the impact of deviations from the Operator Product Expansion known as Duality Violations. The result of this analysis yields $\alpha_s(m_\tau^2)=0.298\pm 0.016\pm 0.006$ in fixed-order perturbation theory, and $\alpha_s(m_\tau^2)=0.304\pm 0.018\pm 0.006$ in contour-improved perturbation theory, where the first error is statistical, and the second error reflects our estimate of various systematic effects. These values confirm a recent determination from the OPAL and ALEPH data for hadronic $\tau$ decays also performed by our group.

The distinctive feature of PAUS with respect to other wide-field surveys is the high resolution in the measurement of redshift by photometric means, made possible by imaging the sky in 40 narrow band filters (100 Angstrom wide). In 2018 it was shown that PAUS meets its design goals with a resolution of $0.0035 (1+z)$ for a fraction of the data as shown in the paper The PAU Survey: Early demonstration of photometric redshift performance in the COSMOS field

On December 2018, the Euclid’s Filter Wheel was successfully installed in the NISP structure. This milestone finish the hardware contributions of the first IFAE project funded directly by the Space program. The group at IFAE had a large responsibility in the management and the engineering design and was responsible for the construction, integration, and control of the assembly and testing equipment.

During 2018, the IFAE group finished the production of the Guiding, Focusing and Alignment (GFA) cameras, complete with mechanical enclosures, filters, CCDs, readout electronics, thermal control, etc. The units were shipped to Lawrence Berkeley National Laboratory (LBNL), USA, for their integration in the DESI (Dark Energy Spectroscopic Instrument) focal plane. The GFA units use 2 x 2 k Teledyne-e2v CCD detectors to focus the optical fibres of DESI, align these 5,000 fibres with the objects to be observed and to do the guiding during the exposure time.

The 2018 Buchalter Cosmology First Prize was awarded to José Ramón Espinosa, Davide Racco and Antonio Riotto. The judging panel selected their paper “A Cosmological Signature of the Standard Model Higgs Vacuum Instability: Primordial Black Holes as Dark Matter” published in Physical Review Letters and recognized it as “a fascinating and novel approach putting forth an exotic option for dark matter, arising from primordial black holes produced from large-scale instability in the Higgs potential during inflation, that does not require new particles beyond the Standard Model.”