NEWS INFN ARCHIVIO // ARCHIVE

It's called ANDES and will be a large underground research infrastructure, like the INFN Gran Sasso National Laboratories, the largest underground laboratories in the world dedicated to astroparticle physics. The only difference with respect to this last is that instead of being under the massif of the Apennines it will be built in the Agua Negra tunnel in the Andes. This is the main project included in the agreement that was signed on May 10th, in San Carlos de Bariloche in Argentina, in the presence of the President of the Italian Republic, Sergio Mattarella, the President of INFN, Fernando Ferroni, and the President of CNEA (Comisión Nacional de Energica Atomica), Osvaldo Calzetta Larrieu. The new agreement, which specifically regards research in astroparticle physics, is part of the Memorandum of Understanding signed by the two scientific institutes in 2015 and concerns, in particular, three international projects: the ANDES Laboratory, the Pierre Auger Observatory and the QUBIC (Q-U Bolometric Interferometer for Cosmology) Observatory. Within the scope of ANDES, lNFN will provide an important contribution to
the construction of the new underground laboratory, thanks to the thirty years of experience acquired by the Gran Sasso National Laboratories. INFN will thus provide its knowledge and skills acquired in training people and in the design and construction of experimental prototypes. For the Pierre Auger Observatory project, INFN will be responsible for the surface scintillators, while for the QUBIC Observatory for its cryostat. INFN and CNEA will subsequently develop a more generally coordinated and joint action in the field of research in astroparticle physics: this action will cover everything related to the training of graduate students and technicians, basic and applied research, technology development and deployment of new equipment, techniques and methodologies.

The European XFEL, the future European free electron super-microscope, successfully completed one of the last stages of its construction: the first beam of electrons was accelerated along the entire length of the machine, of 2.1 km. The first superconducting linear accelerator in the world of this size has hence started functioning: this is a crucial step for the commencement of the scientific activities, scheduled for next Autumn, when in the laboratories of the European XFEL in Hamburg, Germany, it will be possible to photograph and film, with atomic resolution, the biological, chemical and matter processes, both in the condensed and in the excited state of plasma. The European XFEL is, in fact, a project for the creation of a fourth generation synchrotron radiation source, based on the FEL (Free Electron Laser) process. That’s the result of a scientific collaboration, led by DESY (Deutsches Elektronen-Synchrotron) and in which Italy, with INFN, is one of the leading international partners. The accelerator that is now operative will feed the X-ray laser and is therefore the key-component system, for a total length of 3.4 km, of what will be the free electron super-microscope. INFN has made an
essential contribution to the accelerator’s creation, by developing, at the LASA laboratories in Milan, some of the key elements of the machine. The Italian contribution, of roughly 40 million Euro, funded by the Italian Ministry of University and Research (MIUR) and brokered by the INFN, yielded an almost
double return for the domestic industry, in terms of orders for advanced technologies. In addition, 10% of the researchers and engineers hired by European XFEL is Italian. Scientists at the European
XFEL have crowned their twenty-year commitment to the development and construction of one of the largest and most ambitious European research infrastructures, with a cost of over 1.2 billion Euro. Indicated as one of the most important projects in the roadmap of ESFRI (European Strategy Forum on Research Infrastructures), the European XFEL will put Europe at the international forefront, opening new paths for the development of fundamental scientific knowledge and their applications in biology, medicine, and new materials.

The cooperation between Italy and China for dark matter research is confirmed and strengthened. During the bilateral meeting of May 9thbetween INFN and IHEP (Institute for High Energy Physics) of Beijing, the two Institutes signed the letter of interest to participate in the HERD (High Energy Cosmic Radiation Detection) experiment.HERD is one of the main science projects of the Chinese Space Station, which involves the construction of a new powerful space telescope. The scientific objectives of HERD, whose launch is planned for 2020, are dark matter particle detection, cosmic ray composition analysis and high energy gamma ray observation. The main characteristics of the future detector are its total weight, which will be less than 2 tons, and its total energy consumption, which will be less than 2 kilowatts.
To achieve its scientific objectives, HERD must be able to measure with great accuracy the energy and direction of origin of electrons and gamma rays, i.e. high energy photons (from tens of GeV up to 10 TeV), and the energy of cosmic rays, also determining their charge (up to the PeV scale). HERD will be able to detect high energy gamma rays, electrons and cosmic rays with a higher resolution compared to current telescopes: this implies that the experiment has great potential in contributing in an innovative manner to the understanding of the origin and propagation of high energy cosmic rays, and to the identification of possible "signatures" left by dark matter particles, but also to new discoveries in the field of so-called "high energy gamma-ray astronomy".

The ALICE experiment at the Large hadron collider (LHC) at CERN has observed for the first time in collisions between protons an increase in the production of so-called strange particles, which is one of the distinguishing phenomena of quark-gluon plasma, a very hot and dense state of matter which existed just a few millionths of a second after the Big Bang. So far, this characteristic of the state of primordial matter had only been observed in collisions between heavy nuclei, and nobody thought that it could also be found in proton collisions. This unexpected observation is a challenge to existing theoretical models, which do not include the increase of strange particles in these events. The result, published in Nature Physics on April 24
th, was obtained from the analysis of data on collisions with 7 TeV protons on Run 1 of the LHC, and is based on the observation of the strange hadrons in proton-proton collisions in which a large number of particles is produced. Strange hadrons are well known particles, called like this because they are made of quarks, of which at least one is a strange quark. The strange quarks are heavier than quarks that make up “normal" matter and are difficult to produce. But this changes when we are in the presence of a high energy density, which rebalances the creation of strange quarks in relation to the non-strange ones, just like in heavy ion collisions. The new results show that, in the studied proton-proton collisions, the rate of production of strange hadrons increases with the 'multiplicity' (the number of particles produced in a given collision) faster than what happens for
the other species of particles generated in the same collision. The data also show that the higher the number of strange quarks contained in the produced hadron, the greater the increase of its production speed. However, no dependence on the collision energy or the mass of particles generated is observed, demonstrating that the observed phenomenon is related to the fact that the particles produced contain strange quarks. The more precise study of these processes will be the key to understand more thoroughly the microscopic mechanisms of the quark-gluon plasma and the collective behaviour of the
particles in small systems.