Visualization of GW190814, Credit: N. Fischer, S. Ossokine, H. Pfeiffer, A. Buonanno (Max Planck Institute for Gravitational Physics), Simulating eXtreme Spacetimes (SXS) Collaboration.
When the most massive stars die, they collapse under their own gravity and leave behind black holes; when stars that are a bit less massive die, they explode in supernovas and leave behind dense, dead remnants of stars called neutron stars. For decades, astronomers have been puzzled by a gap that lies between neutron stars and black holes: the heaviest known neutron star is no more than 2.5 solar masses, and the lightest known black hole is about 5 solar masses. Now, scientists from LIGO and Virgo have announced the discovery of an object of 2.6 solar masses, placing it firmly in the mass gap. About 800 million years ago, this object merged with a black hole of 23 solar masses and, in so doing, emitted an intense gravitational wave. Since the observation of this wave alone, which was detected on Earth in August 2019, does not allow us to distinguish whether the compact object is a black hole or a neutron star, its precise nature remains a mystery.
During the last meeting of the General Assembly a new Chair and Vice-Chair for the Scientific Advisory Committee have been elected: Sijbrand de Jong takes over the duty as chair from Laura Baudis and Silvia Pascoli substitutes Jocelyn Monroe as Vice-Chair. We want to take this opportunity to thank Laura Baudis and Jocelyn Monroe for their successful work in the last two years! The main task of the SAC is report to the General Assembly on issues of strategic scientific importance, including the connection to related areas, such as particle and nuclear physics and astronomy. With the planned town meeting next year an important event is imminent and the SAC is responsible for the scientific organisation. For this event and for all further tasks we wish the newly elected chairs all the best!
“Astroparticle physics has emerged as a recognisable, independent field over the past several decades. The ties with particle physics and astrophysics are very visible and strong and it would be good to keep close cooperation with these two fields.
Astroparticle physics is a vibrant field with a number of recent far-reaching breakthroughs, and many excited scientists who want to continue on this path. It is also a very diverse field, encompassing not only installations to observe the universe, but also controlled accelerator as well as non-accelerator experiments. Theoretical astroparticle physics is not only important for interpretation of observational and experimental results and to guide new observations and experiments, but also to provide the connection between the diverse areas of astroparticle physics.
Astroparticle physics is part of the big-science family, with major real estate running and being prepared for the future, very often in a global perspective. As a relatively young field, it does not yet have the degree of organisation that several other big-science fields have. APPEC plays a crucial role to provide coordination and organisation of astroparticle physics in Europe, with good connection to the rest of the world. Setting priorities is an important part of the coordination. Organising the European funding agencies behind the prioritised programmes is the other important aspect.
The APPEC SAC, as advisory body of the APPEC General Assembly, is responsible to provide the General Assembly with the necessary scientific arguments to set priorities, to push support for the prioritised projects all over Europe and to enable the General Assembly to seek alliances with parties outside of Europe. As the chair of the APPEC SAC I will do my very best to coach the SAC to deliver all relevant information as advice to the General Assembly: complete, on time and in comprehensible language.” Sijbrand de Jong
“Astroparticle physics aims at answering some of the most fundamental questions in physics, from the identity of dark matter to the symmetries of nature related to proton decay and neutrinos, from the behaviour of extreme astrophysical environments to the evolution of the Universe. It exploits the rich interface between particle physics, astronomy and cosmology and their synergy. It is in an exciting phase, with new experiments ongoing and planned for the future, the recent birth of multimessenger astronomy thanks to the discovery of gravitational waves and high energy neutrinos, and new theoretical ideas. Connecting with other related areas, such as particle and nuclear physics and cosmology, is also important and can open new research perspectives. In my role as Vice-Chair of APPEC SAC, I will strive to support the Chair, Prof. de Jong, in providing the scientific advice to APPEC General Assembly to shape the future of the field.” Silvia Pascoli
Biographies
Sijbrand de Jong
I have been educated as an experimental particle physicist. I started in 1984 as MSc student on the WA25 (neutrino deep inelastic scattering) and NA4 (BCDMS, muon deep inelastic scattering) experiments. I did my PhD from 1986 until 1990 on the preparation of the ZEUS experiment at HERA/DESY (ep deep inelastic scattering). As a post-doc and junior faculty, I worked on the OPAL experiment at LEP/CERN (e+e- scattering) from 1990 until 1998. After having been appointed full professor at Radboud University in Nijmegen, the Netherlands in 1998, I worked on the Dzero experiment at the Tevatron/Fermilab (ppbar scattering) and in the transition to Radboud University I worked for a short while in ATLAS (pp scattering).
Since 2005, I switched to astroparticle physics and I am active in the Pierre Auger Collaboration, notably on helping to establish the detection of ultra-high-energy cosmic rays ultra-high-energy cosmic rays via the radio frequency emission of their air shower (in jargon called radio detection). Currently, I am a member of the team that rolls out this technology to the full Pierre Auger Observatory 3000 square kilometre array to provide a completely new detection layer for the electromagnetic part of extensive air showers, especially also for horizontal showers, which may open the possibility for the detection of ultra-high-energy neutrinos.
I did my share of administration and governance, as director of the school of physics at Radboud University, as founding director of the Institute for Mathematics, Astrophysics and Particle Physics at Radboud University, as 10-year board member of the Dutch Physics funding agency, and more recently for three years as CERN Council President (after a preceding period of six years as CERN Council member).
I very much like education and public engagement and I founded a Pre-University College of Science at Radboud University at the interface between secondary school and university.
Silvia Pascoli
I have been interested in astroparticle physics since the beginning of my career. After obtaining a PhD in Elementary Particle Physics from SISSA, Italy, working on neutrinoless double beta decay theory, I moved to UCLA as a postdoc and then to CERN as a Fellow. In 2005 I joined Durham University as faculty, in the Institute for Particle Physics Phenomenology, where I served as Deputy Director from March 2011 to August 2014 and became professor in 2012. My main fields of research are neutrino physics and astroparticle physics, with focus on their phenomenology, the origin of neutrino masses and of the baryon asymmetry of the Universe, and the connection with dark matter and cosmology. For my research, I received the 2013 Occhialini Prize jointly by the Institute of Physics (UK) and the Societa ́ Italiana di Fisica (Italy) and I was awarded the ERC Consolidator grant NuMass. Although a theorist, I often collaborate with experimentalists to test new theoretical ideas and to understand the physics potential of current and future experiments, for instance as member of the DUNE collaboration and in the past with my involvement in e.g. LAGUNA-LBNO. I endeavour to contribute to the shaping of the field, both with advising roles (member of Fermilab Physics Advisory Committee, several STFC panels, Hyper-Kamiokande Program Advisory Committee) and with activities aimed at the broader community (e.g. Neutrino 2016 organisation, CENF-TH co-convener, Horizon2020 RISE InvisiblesPlus deputy coordinator, EuCAPT Steering Committee member). I believe that training the next generation of scientists is of paramount importance: in addition to teaching and supervising PhD students, I have acted as deputy coordinator of two EU-funded ITNs, Invisibles and Elusives, and I am the coordinator of the recently funded Horizon2020 ITN HIDDeN. I have a very strong commitment to Equality/Diversity/Inclusion and I try to inform all my activities by it. I have also a great interest in engagement with industry and the general public and have organized several outreach events.
At the recent Neutrino 2020 virtual meeting the Borexino Collaboration has announced the first detection ever of neutrinos from the CNO cycle in the Sun, an astounding experimental achievement, which closes a chapter of physics commenced in the years ‘30s of the past century.
It was indeed in 1938 when Bethe and von Weizsäcker independently proposed that hydrogen fusion in the Sun might be catalyzed by the heavy nuclei carbon, nitrogen, and oxygen, according to a cyclic sequence of nuclear reactions. This second mechanism of hydrogen burning into helium in the Sun’s core complements the main energy generating process constituted by the pp chain of reactions, initiated by the direct fusion of two protons into a deuteron.
Despite the indirect evidences from astronomical and astrophysical observations that the two hypothesized engines powering the Sun and the stars are actually occurring, a direct experimental confirmation can come only by detecting the neutrinos, which are copiously produced by several reactions in both sequences.
This consideration was at the heart of the foundation of the Solar Neutrino experimental program since the middle of the 20th century, by far one of the most successful areas of particle physics over the past six decades, which amassed results of enormous relevance and implications, the latest being the recent Borexino announcement.
From the first Solar Neutrino detection by the Homestake experiment in the 70’s, to the Gallex and Sage capture of the main pp neutrinos in the 90’s, to the present Borexino observation of the CNO cycle neutrinos, through these three milestones physicists have completely unraveled the two processes powering the Sun and the stars. We now have the final, definite and complete experimental answer to the centuries-old question of humankind on how the Sun shines.
PMTs installed on the Borexino Stainless Steele Sphere. Credits: Borexino
Following the initial intuition of the founders of the field, comprising true giant of physics like Pontecorvo and Alvarez, Solar Neutrinos proved to be an invaluable tool to study the operating mechanism of the Sun, being a direct probe of the otherwise inaccessible nuclear furnace at its core.
Moreover, throughout this several decade long fascinating enterprise to unveil the mysteries of the Sun, Solar Neutrinos were also pivotal to assess the neutrino oscillation phenomenon, indisputably one the greatest particle physics discovery at the dawn of the new millennium.
Borexino therefore, with its CNO discovery, represents the crowning of a physics field rich of multiple and somehow unexpected successes.
From the measurement side, the detection of CNO neutrinos was not easy at all, on the contrary, it was a true daunting task.
In general, Solar Neutrinos can be caught only with highly sensitive detectors, capable of suppressing most sources of background signals. To achieve the required sensitivity, the Borexino experiment was built with an onion-like design, characterized by layers of increasing radiopurity while moving from the periphery to the center.
The transparent, spherical core is filled with 280 tons of liquid scintillator (a material that emits light when a neutrino interacts with the electrons within it), which is encased in a large, stainless-steel sphere filled with a buffer liquid and equipped with 2200 light sensors. The outer sphere is contained within an even larger stainless-steel tank filled with 2400 tons of ultrapure water. The entire detector is located 1 kilometer underground, in the Gran Sasso Laboratory.
The liquid scintillator has attained unprecedented radiopurity levels by means of a series of special precautions and dedicated purifications, which the Collaboration adopted in an undeterred effort for the ultimate lowest background.
Borexino has been taking data since 2007. The Collaboration marked already important achievements in 2007 with the detection of the Solar Neutrinos from the Berillium-7 electron capture, and in 2014 when it announced the first real-time detection of neutrinos from the proton-proton fusion (in contrast with the previous detection, time and energy integrated, from Gallex and Sage).
Inside view of the Borexino detector. Credits: Borexino
Despite these outstanding successes and an already ultrapure detector, Borexino physicists had to push very hard to further improve the suppression and understanding of the tiny residual background to succeed in identifying the CNO cycle neutrinos. The key issue was the decay of the isotope Bismuth-210, whose energy spectrum is located exactly in the same energy window where the CNO signal is expected to occur. The measurement of the Bismuth-210 decay rate was achieved by studying the decay rate of Polonium-210, a process that is in equilibrium with Bismuth-210 decay, but easier to measure.
Therefore, the quest for CNO neutrinos turned into the quest for Bismuth-210 through Polonium-210.
However, since the decay rate of Polonium-210 is highly sensitive to fluctuations in temperature, which trigger convection of the liquid and induce the transport to the center of the detector of Polonium-210 originated on the surface of the scintillator containment vessel, the Collaboration needed to carefully stabilize thermally the whole set-up.
To this purpose, Borexino was wrapped with an insulation layer to decouple it from the external temperature variations, and an active control system was installed to establish internally across the scintillator a stable top-bottom gradient, which is key to help maintaining the liquid in a static condition. Furthermore, the detector was equipped with a large number of temperature sensors for high precision monitoring of the temperature evolution in multiple locations, and a sophisticated fluid dynamic simulation was implemented to predict the behaviour of the scintillator under varying external conditions.
As ultimate precaution, the air of the Hall C of the Gran Sasso Laboratory where Borexino is located, has been also stabilized by means of a feedback control loop.
When all these tools enabled finally the long-sought determination of the intrinsic Polonium-210, and hence Bismuth-210, content of the scintillator, the CNO signal emerged unmistakably in the global fit of the data with a significance as high as 5 sigma.
View of the internal of the Borexino Stainless Steel Sphere. PMTs installed, scaffoldings removed. Credits: Borexino
The CNO detection announced by Borexino (which following the scientific practice will be deemed official after been peer reviewed) is, hence, the successful outcome of a relentless, years-long effort, to stabilize and understand the detector, which implied to push the liquid scintillation technology beyond any limit previously attained.
Besides representing the final assessment of the global theoretical picture of how the Sun and the stars operate, CNO neutrinos attract the specific interest of Solar physicists because they provide a path toward the direct determination of the Sun’s metallicity, i.e. the content of elements heavier than hydrogen and helium. In particular, by studying the rate of CNO neutrinos it is in principle possible to shed light on the long-standing puzzle whether the Sun’s metallicity is more in line with models predicting a higher metallic content, or with models implying a lower content evaluation.
Although the inherent uncertainty of the Borexino result makes it consistent with both scenarios, the Borexino approach and outcome pave the way for future measurements from next generation experiments, which could further address the solar composition conundrum.
Beyond this, Borexino, which is approaching the conclusion of its lifetime, leaves to the neutrino field the persisting legacy of the first observation of CNO neutrinos, a breakthrough result obtained through an impressive experimental effort, which will remain for the future as one of the foundational achievements of neutrino physics.
A long-term workshop on experimental Astroparticle Physics will be held from 02 to 27 November 2020 at Institut Pascal in Orsay. This workshop is a continuation of the Paris-Saclay AstroParticle Symposium of 2019 on theoretical Astroparticle Physics.
The aim is to gather specialists of the field on the topics of High-Energy Astroparticle Physics including high-energy cosmic rays, gammas, neutrinos and gravitational waves with special emphasis on multi-wave length and multi-messenger studies. The workshop includes working sessions every day (only one informal discussion per day, and on Friday, a ‘conference’ format day with speakers). They intend to invite confirmed researchers accompanied by their students and/or postdocs to make working conditions as enticing as possible. The aim is to initiate/continue/finalise research projects in an inspiring environment.
Scientists from the international XENON collaboration announced on June 17th that data from their XENON1T, the world’s most sensitive dark matter experiment, show a surprising excess of events. The scientists do not claim to have found dark matter. Instead, they say to have observed an unexpected rate of events, the source of which is not yet fully understood. The signature of the excess is similar to what might result from a tiny residual amount of tritium, but could also be a sign of something more exciting – such as the existence of a new particle known as the solar axion or the indication of previously unknown properties of neutrinos.
“Our result could be the onset of new physics” says Prof. Manfred Lindner (MPIK), Co-Spokesperson of the XENON Collaboration and APPEC-SAC member. “We emphasize very carefully conventional explanations of the observed excess, but about 90 theoretical publications within one month show that it could point to exciting new physics”.
The central part (the TPC) of the XENON1T detector. Credits: XENON Collaboration
XENON1T was operated deep underground at the INFN Laboratori Nazionali del Gran Sasso in Italy, from 2016 to 2018. It was primarily designed to detect dark matter, which makes up 85% of the matter in the universe. So far, scientists have only observed indirect evidence of dark matter, and a definitive, direct detection is yet to be made. So-called WIMPs (Weakly Interacting Massive Particles) are among the theoretically preferred candidates, and XENON1T has thus far set the best limit on their interaction probability over a wide range of WIMP masses. In addition to WIMP dark matter, XENON1T was also sensitive to different types of new particles and interactions that could explain other open questions in physics. Last year, using the same detector, these scientists published in Nature the observation of the rarest nuclear decay ever directly measured.
“While our detector was mainly designed to detect dark matter particles, its low energy threshold coupled to an extremely low background allows us to search for other rare interactions and particles beyond the standard model of particle physics,” says Prof. Laura Baudis (UZH), member of the APPEC SAC, and one of the leading members of the project.
The XENON1T detector was filled with 3.2 tonnes of ultra-pure liquefied xenon, 2.0 t of which served as a target for particle interactions. When a particle crosses the target, it can generate tiny signals of light and free electrons from a xenon atom. Most of these interactions occur from particles that are known to exist. Scientists therefore carefully estimated the number of background events in XENON1T. When data of XENON1T were compared to known backgrounds, a surprising excess of 53 events over the expected 232 events was observed. This raises the exciting question: where is this excess coming from?
One explanation could be a new, previously unconsidered source of background, caused by the presence of tiny amounts of tritium in the XENON1T detector. Tritium, a radioactive isotope of hydrogen, spontaneously decays by emitting an electron with an energy similar to what was observed. Only a few tritium atoms for every 1025 xenon atoms would be needed to explain the excess. Currently, there are no independent measurements that can confirm or disprove the presence of tritium at that level in the detector, so a definitive answer to this explanation is not yet possible.
View into the water tank, lined with reflecting foil, and the XENON1T detector. Sensitive sensors identify light signals induced in the water by cosmic radiation. Credits: XENON Collaboration
More excitingly, another explanation could be the existence of a new particle. In fact, the excess observed has an energy spectrum similar to that expected from axions produced in the Sun. Axions are hypothetical particles that were proposed to preserve a time-reversal symmetry of the nuclear force, and the Sun may be a strong source of them. While these solar axions are not dark matter candidates, their detection would mark the first observation of a well-motivated but never observed class of new particles.
“This would have a large impact on our understanding of fundamental physics, and of astrophysical phenomena. Moreover, axions produced in the early universe could also be the source of dark matter,” says Baudis.
Alternatively, the excess could also be due to neutrinos, trillions of which pass through your body, unhindered, every second. One explanation could be that the magnetic moment of neutrinos is larger than its value in the Standard Model of elementary particles. This would be a strong hint to some other new physics needed to explain it.
Of the three explanations considered by the XENON collaboration, the observed excess is most consistent with a solar axion signal. In statistical terms, the solar axion hypothesis has a significance of 3.5 sigma, meaning that there is about a 2 / 10,000 chance that the observed excess is due to a random fluctuation rather than a signal. While this significance is fairly high, it is not large enough to conclude that axions exist. The significance of both the tritium and neutrino magnetic moment hypotheses corresponds to 3.2 sigma, meaning that they are also consistent with the data.
“We are very excited about this new result from our tonne-scale liquid xenon detector with an incredibly low background that hasn’t been reached by any other experiment in the field” says Baudis.
XENON1T is now upgrading to its next phase – XENONnT – with an active xenon mass three times larger and a background that is expected to be lower than that of XENON1T. With better data from XENONnT, the XENON collaboration is confident it will soon find out whether this excess is a mere statistical fluke, a background contaminant, or something far more exciting: a new particle or interaction that goes beyond known physics.
“XENON1T was primarily built to search for WIMPs”, says Lindner. “This are top candidates for the Dark Matter in the Universe, but the record exposure and the very low threshold allows us to look for other exciting new physics. Maybe we stepped on some other exciting new physics which we can further explore with XENONnT which was already assembled and should become operational in the next months”.
The XENON collaboration comprises 163 scientists from 28 institutions across 11 countries. The European participation in XENON is very strong, with the following groups being involved: INFN Gran Sasso, Bologna, Napoli and Torino, and L’Aquila University in Italy, MPIK Heidelberg, the Universities of Freiburg, Mainz, Münster and KIT Karlsruhe in Germany, the University of Zurich in Switzerland, Subatech, LAL, LPNHE in France, Nikhef in the Netherlands, Stockholm University in Sweden and the University of Coimbra in Portugal.
Together with the other international collaborators, these groups are responsible for many of the crucial systems in XENON: the TPC and the photosensors and their readout, the data acquisition and light calibration systems, the xenon storage and distillation systems for radon and krypton, the material screening and radon emanation measurements, along with other background mitigation techniques, the neutron and muon veto systems.
APPEC congratulates the CERN Council for its decision to update the European Strategy for Particle Physics setting up a vision for the future of particle physics, a process that was inclusive of the full Particle and Astroparticle Physics communities. The general considerations of the 2020 update acknowledge the importance of the rich and complementary physics programs of neighbouring fields, and in particular acknowledge:
the groundbreaking discovery of gravitational waves which occurred since last strategy update in 2013 and has contributed burgeoning multi-messenger observations of the universe;
that dark matter and flavor puzzles are outstanding mysteries. They require synergy with cosmological and astronomical observations and experiments looking for direct interactions of dark matter or axions and in the neutrino sector, with neutrinoless double beta decay experiments also having potential to reveal violation of the global lepton number;
that neutrinos are a fascinating portal towards Physics beyond the Standard Model, which can be addressed by accelerator, reactor, atmospheric neutrino, as well as cosmic neutrino and cosmic ray experiments;
the importance of synergy on theory, which concretized in the creation of the EuCAPT Astroparticle theory centre, with its first hub located at CERN;
that the Recognised Experiment program needs to be expanded for some cases into specific agreements on technical and scientific cooperation in fields, such as gravitational waves and dark matter, which can strongly advance the field of Particle and Astroparticle Physics, as well as innovation;
the coordinated activities in Astroparticle Physics by APPEC.
We look forward for the years to come and work together on the realization of these many synergies between Particle Physics and Astroparticle Physics to address the hiding secrets of fundamental physics laws in the tiny nooks of space and time.
The 9th edition of the Very Large Volume Neutrino Telescope Workshop (VLVνT-2021) will be held from 20th to 23th April 2021, in Valencia, Spain. The workshop provides an ideal forum to discuss the latest developments in neutrino astronomy together with progress on the technological and instrumentation aspects of current and future large scale detectors in water and ice. It brings together the main collaborations working on neutrino telescopes (ANTARES, IceCube, KM3NeT, GVD) and is sponsored by the Global Neutrino Network (GNN).
In April 2020 the previous observer Poland became an official member of APPEC. In the General Assembly they are represented by Leszek Roszkowski from CAMK, who is director of AstroCeNT – the Particle Astrophysics Science and Technology Centre. Leszek Roszkowski also chairs the APPEC SAC sub-committee preparing a strategy report on direct detection of dark matter.
The quest for B-mode polarization of the Cosmic Microwave Background (CMB) is one of the major challenges of observational cosmology. A positive detection would signify the presence of primordial gravitational waves, theoretically expected from the inflation era. This is one of the most difficult measurements to make because the expected signal is very small and requires highly sensitive instruments with little systematic bias and with wide frequency coverage in order to separate the primordial signal from the foreground.
The QUBIC collaboration meeting of November 2019 at APC. Credits: QUBIC
QUBIC (QU Bolometric Interferometer for Cosmology: http://qubic.in2p3.fr) is an instrument based on a new concept called bolometric interferometry. The objective of QUBIC is to search for the B-mode polarization constructed from the Q and U modes (the two Stokes parameters describing the shape of the polarization ellipse of the microwave radiation). QUBIC combines the advantages of very sensitive and wide band cryogenic bolometers with the precise control of systematic instrumental effects possible with an interferometer, giving also the added capability of spectroscopic imaging. The original idea dates back to the early 2000s and, since then, European physicists have played a leading role in the development and exploitation of this innovative technology. After some initial projects, the QUBIC collaboration was created in 2008. New technical developments in European laboratories have enabled the creation of advanced detectors.
¼ focal plane of QUBIC composed of 256 TES cooled at 300mK and detection chain. Credits: QUBIC
The technological demonstrator (TD), identical to the nominal instrument but with fewer detectors and interferometry channels, smaller mirrors and without dichroic filter, was integrated at APC, Paris, in 2018 and underwent a test phase throughout 2019. It is intended to be installed at the QUBIC site at an altitude of 4800 m in the province of Salta in Argentina. Built by French, Italian, Irish, British and Argentinian laboratories, the technological demonstrator of QUBIC passed, in January, a review requested by the IN2P3-CNRS with the participation of the INFN. The review highlighted the innovation of the technical demonstrator as the first ever bolometric interferometry telescope and its potential for cosmology.
QUBIC synthesized beam, as measured (left) and expected (right). Credits: QUBIC
In the synthesis of the scientific presentations of the review group, which included international experts, the following evaluation was given on the general context of QUBIC:
“The interferometric nature of the synthesized beam results in a change of its multiply peaked pattern as a function of EM wavelength. Consequently, QUBIC would have sensitivity to space patterns on the sky as well as to their EM spectrum. QUBIC is therefore designed as a spectro-imager capable of measuring up to 5 sub-bands in each of our physical bands providing extra EM spectrum resolution with respect to traditional imagers. This unique feature could be a game-changer in the current context of a strong limitation to primordial B-mode observations from foregrounds (dust, synchrotron) whose spectral behaviour is not known and could significantly depart from a power-law (which is usually assumed in any component-separation so far).
QUBIC site at 5000m altitude at Alto Chorillos, near San Antonio de los Cobres, Salta province, Argentina. The Tuzgle volcano is visible. Credits: QUBIC
The target QUBIC installation site will be on the La Puna plateau in Argentina at 4800 m altitude. This site is an excellent compromise between the atmospheric conditions (humidity, stability) similar to that of the neighbouring Atacama and little degraded compared to a site in Antarctica and secondly a possible accessibility almost all year long, incomparable to that of an Antarctic site.”
In the general remarks of the conclusions, the progress made over the past two years is considered impressive. The demonstrator is assessed as convincing and successful, since the concept’s polarization and spectroscopy capabilities have been found to be excellent and in particular, the spectroscopic feature is of utmost utility for foreground characterization and analysis.
QUBIC instrument in the APC intégration hall (Paris). Credits: QUBIC
Several instruments installed on various sites are already measuring the CMB in search of the B-mode signal. The strength of this signal is summarized by the ratio “r” between the amplitudes of the tensor and scalar modes of perturbation of the metric of the primordial Universe. As the PI, Jean-Christophe Hamilton, explains, QUBIC’s sensitivity and statistics, once operational, will be lower than some of the running experiments. Nevertheless, QUBIC’s novel approach to systematic effects and to the foreground subtraction could be decisive for the discovery or confirmation of the extremely weak expected signal. QUBIC’s new technology aims to be integrated into next generation large detectors through a multi-year deployment and sensitivity enhancement program.
Regarding the current phase of QUBIC, Aniello Mennella, system scientist, says that the next steps envisaged are the finalization of the tests at APC, the shipping of the TD to Argentina and the commissioning on the sky (which will suffer delays due to the health crisis unfortunately). Following the upgrade to the complete instrument which will improve the sensitivity, there will be an observing campaign of 2 years leading to an estimate of sigma(r) = 0.01, corresponding to the sensitivity of Stage III instruments in the terminology of the CMB community.
In the longer term, potential future developments of QUBIC are already envisaged in order to reach Stage IV sensitivity (sigma (r) = 0.001) within a few years. These include:
Upgrading the current cryostat for a gain in sensitivity (~ x5) and in spectral capacity using multimode optics.
Producing similar cryostats which multiply the sensitivity by a comparable amount.
Installation of a similar bolometric interferometer at the focus of the 12m LLAMA antenna, opening access to polarization physics at small angular scales (masses and number of neutrinos, Dark Energy, physics of galaxy clusters).
It should be reminded here that the coordination of European laboratories for the development of the burgeoning field of experiments for Stages III and IV has appeared necessary since some years. APPEC has contributed to global coordination of this field through the Florence CMB Workshop series that started in 2015 and that helped incubate multiple European initiatives for contributing to CMB Stage IV. Information and links are available from the last meeting https://indico.in2p3.fr/event/19414/overview
For several weeks now our everyday life has been quite disrupted by the novel corona virus. We all have to master difficult situations in this unusual time, facing conditions we never experienced before. Although everybody has to deal with a different situation some things are common for almost all of us and our institutions.
“These last weeks will leave a deep sign in my life forever, as possibly the life of many, who will remember the time of COVID. In first place, this time is making me understand better what it means to still have your house to refugee and think how important is our role to understand and help who do not even have it.”Teresa Montaruli
Most institutions have set up a COVID-19 task force to inform and update their employees and to find the right balance between keeping the business running and at the same time protecting the health of the employees in the best possible way.
Despite some people working in the lab most of us have to work from home. There, many have to combine taking care of their kids and doing their daily office work, which is more and more challenging the longer this situation holds.
To keep everybody motivated and to keep contact with colleagues many institutes organize not only scientific virtual meetings but also social events like common coffee breaks, lunches or even concerts.
Traditionally, personal contacts at collaboration meetings, exchanges with scientists – whether within our own working group or during visits to other institutes – and national and international exchanges at conferences make up a large part of our scientific life. But many conferences were cancelled or postponed, like the APPEC Town Meeting which was planned for this autumn is now postponed to 2021.
“I am now working from home for almost 3 months. It is amazing to see how much is still possible using video meetings, chats and the good old phone and email. On the other hand I miss the informal talks with colleagues, and unexpected chats while visiting labs and meetings. This informal opportunities are needed for make progress in delicate and complex topics. But we will learn week by week how to optimize in working from home.”Job de Kleuver
Many meetings and events had to move to a virtual place, which has both, advantages and disadvantages. One advantage of moving many activities to the virtual world is that more people can join. Here are some examples for online conferences, colloquia and seminars:
But having all kind of meetings, like Collaboration meetings, group meeting etc. online is sometimes also very exhausting and it is hard to stay concentrated after hours of a zoom meeting.
“On the positive side of this CoVID crisis, family is now more easily reconciled with my work since at least being a single mom of two kids I do not need to travel. This is despite I need to scholarize them at home while I work. The times I was forced to travel, were problematic to me from the organisation point of view and from the responsibility one. I would be very happy if we understand how effective are video meetings even for audiences of 100 people, if well guided. Another aspect is mobility that our research work requires. It detaches you from families. We should be more tolerant in not considering it as a must in the career of physicists.”Teresa Montaruli
Many of us do not only have to deal with online conferences but with online teaching duties. Some might be well prepared but for some this might be a new field and a lot of additional preparatory work was necessary to provide lectures at an equal level as usual.
“Overalls, this period of telematic contacts found me well prepared. I have migrated my courses completely online and now I am registering them and I will continue to do this also in the future when we will be back in classrooms. I think most physicists must have been able to do this step egregiously well.” Teresa Montaruli
But in addition to this current challenges some scientist are worried about their future. Especially those with temporary contracts or those just finishing their studies or PhDs, are now in a difficult situation. Not only they have to worry about the next month but also worry if this will have negative influence on their future career.
“I hope we find ways to safeguard the young scientists from career damage. Maybe this is a good moment to discuss what really matters: the quality and prospects of talented young scientists or just the numbers of their output in this early stage of their careers.” Job de Kleuver
This is accompanied by the overall funding situation for the following years. Science and experiments will be delayed and also funding opportunities might get worse in the future.
Despite these worries it is great to see that science still keeps going and even new experiments get deployed (XENONnT (German), Baikal-GVD). This is also reflected in the following topics.
Online Outreach Activities
Normally many science institutes have offers for students and pupils and also the general public to get insights in their labs or allow access to their experiments. Often also school labs are an important outreach tool. All these kind of things now have to be transferred to online activities. Sometimes this can be very successful but some experience is just not possible in this way and we are looking forward to the time when we can offer hands-on-experience for our students and pupils.
Until then you can checkout these links to online accessible outreach activities for students:
Besides the attempt to advance everyday physics in the home office and at online conferences, many scientists and institutes also want to participate directly in the fight against COVID-19. And many have found ways and possibilities to do so! They use their 3d printers to produce protective equipment for hospitals, many provide their computing power for virologic investigations into the structure of the coronavirus (Folding@Home, Rosetta@Home), and physicists are performing simulations on the spread of the pandemic. But it is important to keep in mind that we can only provide resources to support those who are experts in the respective field. In the following list you can find links to all kind of activities, perhaps this will motivate even more institutes to get engaged.
https://science-responds.org/ – This website was built to facilitate interaction between COVID-19 researchers and the broader science community (Particle Physics origin)
https://globalyoungacademy.net/covid19/ Covid19 – Initiatives of the GYA, Young Academies and Partners – repository for global and national young academies as well as partner institutions to link their work on Covid19, any statements, or information dissemination activities, initiatives to support scientists, to coordinate and facilitate institutions or governments
Activities from individual institutes or countries:
This list of different activities shows that we defy the difficult situation and accept it as a challenge. And even if the situation seems to relax a bit at the moment, we will have to live with this, for us still unusual, situation for a longer time.
“The Covid-19 crisis is serious and we will remember this for long, but I am convinced that things will go better again, maybe later than we had hoped. Let’s try to keep the spirit and continue as good as it can be with the exciting Astroparticle Physics science and the construction and design of new infrastructures. Let’s be prepared with excellent well-thought plans at the moment that governments will think about new investments to stimulate their economies. And let science in general, and Astroparticle Physics more specificially, demonstrate that Europe is strong when we join the efforts and work together. But for now, take care of your families and stay healthy!”Job de Kleuver
The list of links and information provided here is by far not complete. If you like to add something please contact us.
At the recent 
The 9th edition of the Very Large Volume Neutrino Telescope Workshop (VLVνT-2021) will be held from 20th to 23th April 2021, in Valencia, Spain. The workshop provides an ideal forum to discuss the latest developments in neutrino astronomy together with progress on the technological and instrumentation aspects of current and future large scale detectors in water and ice. It brings together the main collaborations working on neutrino telescopes (ANTARES, IceCube, KM3NeT, GVD) and is sponsored by the Global Neutrino Network (GNN).
