Physics Nobel Prize winner Takaaki Kajita officially launches the particle accelerator at Dresdner Felsenkeller.
What is happening inside the sun and the countless other stars of the universe? This question concerns scientists worldwide. After two years of construction, a new research facility has now been inaugurated: On 4 July, the Felsenkeller Laboratory jointly built by Helmholtz-Zentrum Dresden-Rossendorf (HZDR) and TU Dresden was commissioned. The research facility, located on the south-western outskirts of Dresden in the former Felsenkeller brewery, was opened in the presence of Physics Nobel Laureate Prof. Takaaki Kajita from the University of Tokyo.
Together with Dr. Daniel Bemmerer, Prof. Gerhard Rödel, Prof. Thomas Cowan and Prof. Kai Zuber (from left), Nobel Laureate Prof. Takaaki Kajita (centre) symbolically opened the particle accelerator in Dresden’s Felsenkeller.
“The underground accelerator in the Felsenkeller will be a crucial tool to understand the origin of the elements in the universe and to make better predictions about the neutrino flux from the Sun. Since this machine is open to scientists from all over the world, the entire nuclear astrophysics community can benefit from it. As a neutrino and gravitational wave physicist, I am therefore very much looking forward to new data from the Felsenkeller underground particle accelerator,” Kajita explained at the opening ceremony of the ion accelerator, which is located beneath a 45-metre-thick rock surface. The Dresden laboratory is only the second of its kind in Europe and the third in the world. “This enables us to simulate fundamental processes that take place in all stars,” added Dr. Daniel Bemmerer of the HZDR, technical director of the Felsenkeller Laboratory.
Kajita and Prof. Arthur B. McDonald from Canada were honoured with the Nobel Prize in Physics in 2015 for their discovery that tiny elementary particles released by reactions inside the Sun, or created in the Earth’s atmosphere, transform into another particle family on their way to Earth, the so-called neutrino-flavour oscillation.
Encouraged by this discovery, physicists around the world have since then been working to improve the model of the Sun in order to obtain more precise predictions about the number of neutrinos emitted by the Sun, i.e. before oscillation. For this purpose, among other things, the nuclear reactions from the interior of the sun are simulated in the laboratory. Because these reactions take place very slowly, they can only be studied underground in specially shielded accelerator laboratories. The tunnel rock forms a natural shield against cosmic radiation, which bombards the earth with particles every second. “Since this distorts our measurements, we cannot perform the experiments on the Earth’s surface,” explained Kai Zuber, Professor of Nuclear Physics at TU Dresden and scientific director of the laboratory.
Joint press release of TU Dresden and Helmholtz-Zentrum Dresden-Rossendorf of 4 July 2019
The Baksan Neutrino Observatory (BNO) of the Institute for Nuclear Research of the Russian Academy of Sciences started the BEST (Baksan Experiment on Sterile Transitions) experiment with a 51Cr artificial electron neutrino source to search for the transitions of electron neutrinos to sterile states on very short baseline. The 51Cr source with an estimated activity of 3.28 MCi was delivered to BNO on July 5, 2019, and has been immediately placed at the center of the two-zone target of liquid gallium. At 14:02 Moscow time, the first run of the experiment has begun.
The idea of BEST is to place a 51Cr source with an initial activity of about 3 MCi in the center of the 50-tonne target of liquid gallium metal, which is divided into two concentric zones, the inner 8-ton volume and the outer 42-ton one. Assuming no transition of electron neutrino to eV-scale sterile states, at the beginning of exposure one expects a mean of 65 atoms of 71Ge per day to be produced by the neutrinos from the source in each zone. However, if oscillations to a sterile neutrino take place, then the germanium production rates in the outer and inner zones of gallium would be different. This opens the possibility to obtain information on the allowed regions of the oscillation parameters of active-sterile neutrino transitions.
The source is delivered and placed to the BEST setup.
The chromium used for the source production was enriched to 98% in 50Cr. The enriched chromium was produced by the Joint Stock Company “Production Association “Electrochemical Plant” (JSC “PA ECP”) by gas centrifugation of chromium oxyfluoride, CrO2F2. The source was produced by irradiating of 4007.5 g of the 98% -enriched 50Cr in a high-flux research nuclear reactor SM at RIAR Dmitrovgrad, Russia. The source consists of 26 metallic Cr disks, each of 88 mm diameter and 4 mm thickness, placed in a steel capsule shielded by a tungsten biological protection. The overall dimensions of the source are: 160 mm diameter and 226 mm height.
Main hall of GGNT with the assembled BEST setup.
The BEST calorimetric system.
For BEST, a set of new facilities including the two-zone tank for irradiation of 50 tons of metal Ga as well as additional modules of the GGNT counting and extraction systems were constructed. Ten exposures of the gallium to the source, each of 9 days duration, will be carried out. The source activity will be determined by measuring its heat with a calorimeter system and by gamma-ray spectroscopy with high-purity germanium detectors between extractions for the ten measurements. Expected accuracy of measurements of the source intensity is better than 1%.
Contacts and picture courtesy:
V.N. Gavrin, Principle Investigator of the “BEST” collaboration – gavrin@inr.ru
On July 1st 2019, close to 40 research institutions from nine countries officially signed the agreement for the creation of a new international R&D collaboration for a future wide field-of-view gamma ray observatory in the southern hemisphere. The founding countries of the newly created Southern Wide field-of-view Gamma-ray Observatory (SWGO) are Argentina, Brazil, Czech Republic, Germany, Italy, Mexico, Portugal, the United Kingdom and the United States of America, creating a worldwide community around the project. SWGO unifies different communities that were already involved in R&D in this field. The signature of the agreement comes after a successful meeting of the scientists from the different countries, held in Lisbon in May.
Gamma-ray sky image as seen by the (current) HAWC and (future) SWGO observatories. Credits: Richard White, MPIK (preliminary)
The new observatory is planned to be installed in the Andes, at an altitude above 4.4 km, to detect the highest energy gamma rays – particles of light billion or trillions of times more energetic than visible light. It will probe the most extreme phenomena and environments to address some of the most compelling questions about our Universe, from the origin of high-energy cosmic rays to searching for dark matter particles and for deviations from Einstein’s theory of relativity. Its location in the southern hemisphere will allow the most interesting region of our galaxy to be observed directly, in particularly the Galactic Centre, hosting a black hole four million times the mass of the sun. Wide field-of-view observations are ideal to search for transient sources but also to search for very extended emission regions, including the ‘Fermi Bubbles’ or annihilating dark matter, as well as to discover unexpected phenomena. The new observatory will be a powerful time-variability explorer, filling an empty space in the global multi-messenger network of gravitational, electromagnetic and neutrino observatories. It will also be able to issue alerts and be fully complementary to the next generation imaging atmospheric Cherenkov telescope array, CTA.
The baseline for the new observatory will be the approach of the current ground-based gamma-ray detectors, namely HAWC in Mexico and LHAASO in China. In particular, water Cherenkov detectors will be used to sample the particle showers produced by gamma rays in the atmosphere, by recording the light produced when particles pass through tanks full of purified water. New layouts and technologies will however be explored in order to increase the sensitivity and lower the energy threshold of the observatory.
Illustration of the complementary detection techniques of high-energy gamma rays on ground Credits: Richard White, MPIK
The first very-high-energy gamma-ray emission was observed only 30 years ago, from the Crab Nebula. Hundreds of sources have been discovered since then at these extreme energies. Many extragalactic and some galactic sources present variability, and the duration of flares and transients can be days, hours, minutes or even just a few seconds. The study of these phenomena requires instruments such as SWGO, able to monitor in a continuous way large portions of the sky, sensitive to energies above the reach of satellite-based experiments, and operating in a multi-messenger context: able to alert and to follow up on neutrino and gravitational wave detections as well as other photon observatories.
Direct detection of primary gamma-rays is only possible with satellite-based detectors, such as Fermi. However, the cost of space technology limits the size of satellite-borne detectors, and thus their sensitivity, as fluxes become too small at higher energies. In the atmosphere, gammas interact creating a shower of particles. These showers can be studied in observatories of two complementary types: imaging atmospheric Cherenkov telescopes, pointing instruments such as CTA, and high altitude air shower arrays, such as SWGO. Cherenkov telescopes are highly sensitive pointing detectors, with high precision but limited duty cycle and narrow field-of-view, benefiting from pointing alerts provided by complementary observatories. Wide field-of-view observations from the ground have the highest energy reach, and are ideal to search for transient sources and for emissions from very extended regions of the sky.
Argentina PI: Adrián Rovero, IAFE; Institutes: Instituto de Astronomía y Física del Espacio (IAFE), Universidad Nacional de Salta, DPC-Centro Atómico de Bariloche
Brazil PI: Ronald Shellard, CBFP; Institutes: Centro Brasileiro de Pesquisas Físicas (CBPF), Instituto de Física de São Carlos (Univ. S. Paulo)
Czech Republic PI: Jakub Vicha, FZU- Institute of Physics; Institutes: Institute of Physics of the Czech Academy of Sciences (FZU- Institute of Physics)
Germany PI: Jim Hinton, MPI-K; Institutes: Max Planck Institute for Nuclear Physics (MPI-K), Erlangen Centre for Astroparticle Physics
Italy PI: Alessandro De Angelis, Univ. Udine/Padua and INFN Padua; Institutes: Univ. Udine, Univ. and INFN Trieste, Univ. Catania, Univ. and INFN Torino, Univ. Perugia, Univ. Siena, Univ. Padova, Univ. Bari, Univ. Venice, Univ. Rome Tor Vergata, Politecnico di Milano, INAF
Mexico PI: Andrés Sandoval, UNAM; Institutes: Univ. Nacional Autónoma de México (UNAM, Instituto de Astronomía, Instituto de Ciencias Nucleares, Instituto de Física, Instituto de Geofísica), Instituto Politécnico Nacional – Centro de Investigación en Computación, Univ. Autonoma de Puebla, Instituto Nacional de Astrofísica, Óptica y Electrónica, Univ. Autónoma del Estado de Hidalgo, Univ. de Guadalajara, Univ. Michoacana de San Nicolás de Hidalgo, Univ. Autónoma de Chiapas, Univ. Politécnica de Pachuca
Portugal PI: Mário Pimenta, LIP/IST; Institutes: Laboratory of Instrumentation and Experimental Particle Physics (LIP)
UK PI: Jon Lapington, Univ. Leicester; Institutes: Univ. Durham, Univ. Leicester, Univ. Liverpool
USA PI: Petra Huentemeyer, MTU; Institutes: Michigan Technological Univ. (MTU), Univ. Maryland, Univ. Wisconsin, Los Alamos National Laboratory
Two new clusters of optical modules of the Baikal deep underwater neutrino telescope, Baikal-GVD, were put into operation. The effective volume of the facility, which already includes five clusters, increased to 0.25 km3.
Night sky on the Baikal Lake during the expedition 2019.
Neutrinos, due to their weak interaction, are unique messengers of domains in the Universe, opaque to any other particles.
The proposal to detect high energy neutrinos with help of large natural media like water was first made by a Soviet physicist M.A. Markov in 1960. The key of neutrino detection is the Cherenkov light produced by charged energetic particles born in the neutrino interaction.
The lake Baikal pioneered the field by the first observation of atmospheric neutrinos by a deep-underwater detector in the 90’s, thus proving the proposal of M.A. Markov. The next breakthrough was due to the IceCube experiment on the South Pole in 2012 which discovered astrophysical neutrinos of ultra-high energies1.
The last photo before leaving the ice. Expedition 2019 is completed.
In 2015 the Baikal-GVD Collaboration, led by the Institute of Nuclear Research (Moscow) of Russian Academy of Science and Joint Institute for Nuclear Research (Dubna), started deployment of the deep-underwater neutrino telescope of cubic-kilometer scale, Baikal-GVD, consisting of independent physical units, so called clusters.
As reported by the Collaboration two more clusters were brought into operation during the expedition to Lake Baikal from 15 February to 12 April 2019. This is the result of joint efforts in research, developments, production and assembly. Remarkably, this is the first time when two clusters were installed during one expedition.
In total, five clusters, including all auxiliary systems, have been repeatedly tested and put into regular data acquisition mode. Each cluster consists of 8 vertical strings of optical modules with each string containing 36 modules. There are 1440 optical modules in total, placed at a depth of 750 – 1350 m located 4 km away from the bank of Lake Baikal, near the 106th km of the Circum-Baikal Railway.
The effective volume of the facility reached a level of 0.25 km3 for shower events from high-energy neutrinos, thus allowing scientists to expect two to three events per year from astrophysical neutrinos with energies exceeding 100 TeV.
The Baikal deep underwater neutrino telescope is a unique scientific facility, and, along with IceCube, ANTARES and KM3NeT, is part of the Global Neutrino Net (GNN).
One more optical module is prepared for immersion.
Central module of the section.
Underwater acoustic modem.
Pulsed semiconductor laser.
The full press-release (in Russian) is available at:
After the Particle Physics Strategy Meeting the APPEC General Assembly came together in Granada for a regular meeting on 16/17 May 2019.
Job de Kleuver and Katri Huitu signing the APPEC MoU.
The General Assembly 2019.
During this event we had the pleasure to welcome Katri Huitu from HIP (Helsinki Institute for Physics) who is now representing Finland in the GA.
In addition to reports on past and planned events and activities of the Joint Secretariat the future structure of a more sustainable APPEC was discussed and all agreed that the Astroparticle Physics Community would benefit from a stronger APPEC.
To achieve closer cooperation within the community, it was recommended to organise regular Town Meetings to establish a common strategy for the future.
With the EPPSU event in mind, there have been subsequent discussions on synergies between Particle and Astroparticle Physics and how both communities can work together and benefit from each other in the future. More details can be found here.
In this context also joint activities with APPEC, ECFA and NuPECC, like the Joint Seminar JENAS were presented and Federica Petricca was nominated as a new APPEC representative for the ECFA Detector Panel.
Not only were the discussions very successful, but everyone was also very happy about the organisation, for which we would like to thanks Antonio Bueno.
The European Particle Physics Update (EPPSU) process is conducted by CERN and it gives the guidelines for the future years to the particle physics community on scientific and technological programs, organizational aspects, knowledge and technology transfer as well as interaction with society, education and outreach1. The astroparticle physics community, and hence, APPEC, enters in this process since the strategy concerns also relations with external bodies and other fields of physics, which is covered by WG3 of the European Strategy Group (ESG). The APPEC Chair is participating to the ESG meetings and working groups of the ESG as an Observer. The ESG establishes periodically (last update was in 2013) a proposal in written form with a set of recommendations for CERN Council approval. The final document of this process will be written in the third week of January 2020 and approved in May 20, 2020 by the CERN council.
The Physics Preparatory Group (PPG) drafts its update proposal (the Briefing Book) taking into account the written inputs submitted by the community. S. Bentevelsen and M. Zito coordinate activities around the big questions on Neutrino and Cosmic Messenger, and M. Carena and S. Asai on the Dark Sector. In Dec. 2018, 160 inputs where provided by the community2 including inputs on the strategies of many organisations and laboratories. An Open Symposium was held in Granada in May 2019 to discuss these inputs. It is clear that Astroparticle is a domain of increasing interest, as shown in the table that was presented by S. Betke. APPEC presented its inputs and priorities which are described in this document and in the Open Symposium presentation by the Chair. The community submitted many documents, most of which fall in the priority areas of APPEC. These are: i) the dark matter searches; ii) the multi-messenger astronomy, in particular the third generation (3G) of gravitational wave (GW) experiment (ET); iii) the determination of neutrino nature and mass; iv) the European Astroparticle Theory Centre (EuCAPT).
Concerning dark matter searches it is advocated by APPEC and by the community itself that areas of synergy include exchange about common data interpretation and theory models. It would be beneficial to expand some platforms of discussion such as the Physics Beyond Colliders / LHC DM WG to include astroparticle physicists working on direct and indirect detection of dark matter. The synergy on technology developments, often in common with the CERN platform on cryogenics technology and photosensors is extremely important.The general hope is that cooperation between Astroparticle and Particle Physics communities will evolve towards a global program on dark matter searches, similar in breadth to the neutrino physics program (see below).
Concerning multi-messenger astrophysics, APPEC considers of highest priority the cooperation with CERN on establishing synergies with the multi-messenger astrophysics which has a high scientific potential. The future generation of gravitational wave detectors, the Einstein Telescope, has the capability to incorporate gravity within the model of fundamental interactions, to pin down the nature of dark matter, contribute to cosmology and to explore matter in extreme conditions. While the scientific cooperation is fundamentally important, areas of possible synergy are also on enabling technologies (such as vacuum and cryogenics technology, control and automation, electronics and DAQ, computing) as well as operation of underground facilities, governance models or open access data models.
The CERN platform is the extremely relevant outcome of the last EPPSU2013. This has made possible the preparation towards the large neutrino accelerator facilities such as DUNE and HK, which will shed light on remaining questions on the neutrino ordering and CP violation in the neutrino sector. The astroparticle community considers extremely important the cooperation of accelerator and atmospheric neutrino experiments to increase the precision in the parameters of the neutrino mixing matrix and the ordering. These measurements surely need as well cooperation with reactor neutrinos and in particular with JUNO. An area of important synergy with CERN concerns the hadroproduction experiments, which are relevant for neutrino and cosmic ray physics. The precision on the neutrino cross sections and on the calculations of the production of particles in atmospheric showers, are extremely important for the neutrino accelerator program and multi-messenger astrophysics. The astroparticle physics community and APPEC consider extremely relevant the experiments which will determine the nature of the neutrinos, Majorana or Dirac, and which may have access to the inverted ordering effective neutrino mass with the coming generation of detectors.
EuCAPT is becoming a reality in these days, with final agreements being signed by APPEC and CERN, the first host of EuCAPT for the first round of 5 years. A Steering board has been nominated with prominent scientists from many countries in cosmology, neutrino physics and multi-messenger astrophysics3 and they will nominate a Director for the General Assembly of APPEC to approve. EuCAPT will have a fundamental role for the common interpretation of data of accelerators and astroparticle experiments and for the definition of test models.
In conclusion, one sees currently a sort of unification of many present fields of fundamental science (particle and astroparticle physics, nuclear physics, astrophysics and cosmology). This unification concerns as much cross-correlations at the theoretical level, from where one sees the importance of EUCAPT as well as the R&D on common detectors, civil infrastructures and computing technologies for the dark matter, multi-messenger and neutrino physics. The unification extends to common methods concerning the data analytics and new deep/machine learning methods. Last but not least, the above situation creates an obvious obligation to diffuse and explain the current intense discovery environment to the society in general as well as the need to increase the innovation potential and the technological contributions addressing pressing environmental and societal issues. This situation reinforces our belief that we are facing a very exciting and productive decade.
3APC Paris: David Langlois, CERN Theory Department: Gian Giudice, DESY: Andrew Taylor, GRAPPA/Nikhef Amsterdam: Gianfranco Bertone, ICC Barcelona: Licia Verde, IFPU (SISSA+ICTP+INFN+INAF) Trieste: Piero Ullio, IPPP, Durham: Silvia Pascoli, IST Lisbon: Vitor Cardoso, OKC Stockholm: Hiranya Peiris] Paris-Saclay: Philippe Brax, Université de Genève: Antonio Riotto, University of Oxford: Subir Sarkar
During the last meeting of the General Assembly Federica Petricca was elected as new representative of APPEC in the ECFA Detector Panel.
She did her PhD in 2005 at the Max-Planck-Institut für Physik and the Ludwig Maximilian Universität, Munich, and since then she was working on cryogenic detectors. Since 2014 she is spokesperson of the CRESST (Cryogenic Rare Event Search with Superconducting Thermometers) collaboration for the direct search of dark matter interactions with cryogenic detectors. In the ECFA detector panel she will contribute her experience in low-temperature detector technology and methods, low-background techniques and electronics of data acquisition systems and signal processing.
She is accepting the charge with pleasure and hopes to be soon able to provide a constructive contribution.
This first Joint ECFA-NuPECC-APPEC Seminar (JENAS) jointly organized by LAL, IPNO, IRFU and LPNHE will be held from October 14 to October 16, 2019 in Orsay.
Profound explorations of both the smallest and largest structures in the universe made possible numerous breakthroughs in astroparticle, nuclear and particle physics. Additional to the well-known scientific interplay between our disciplines, the strength to transform challenges into opportunities in the pursuit of our aspirations is driven by our innovations in technology, scientific creativity and organisational rigour, while typically embracing the long-term nature of our research.
A first triennial 3-day Joint Seminar is being organised by the European representative committees/consortia, APPEC for astroparticle physics, ECFA for particle physics and NuPECC for nuclear physics. Facilitated by the local organisers in the Paris region, the intention is to inform the communities about each other’s scientific, technological and organisational challenges and successes, as well as to identify and explore potential synergies and avenues for collaboration across communities. Additional to the physics highlights and the evolution of theoretical research, also topics related to for example detector R&D, technology, software and computing, valorisation, outreach, education will be scheduled in plenary talks.
From 1 June 2019 the community at large will be invited to register, and the remaining seats will be allocated on a first come basis.
ASTRI-Horn is the first Cherenkov telescope in dual-mirror configuration to detect the Crab Nebula at TeV energies:
The ASTRI-Horn prototype telescope is located at the observing station of the INAF Astrophysical Observatory of Catania, in Serra La Nave, on Etna, where it was installed in 2014. The primary tassellated mirror has a diameter of 4 meters and the secondary monolithic mirror is 1.8 meters in diameter. Credit: CTA collaboration
Exactly 30 years after the first historical observation of Crab nebula at TeV energies, which opened the era of TeV astronomy with the Imaging Atmospheric Cherenkov Technique (IACT), another advancement in IACT technology has been achieved. The ASTRI-Horn Cherenkov Telescope, based on the innovative Schwarzschild-Couder dual-mirror configuration and equipped with an innovative camera, has detected the Crab Nebula at TeV energies for the first time, proving the viability of this technology.
This Cherenkov telescope, named ASTRI-Horn (in honor of Guido Horn d’Arturo an Italian astronomer who first proposed in the past century the technology of tessellated mirrors for astronomy), is adopting a wide (10°x10°) field Schwarzschild-Couder dual-mirror optical configuration and is equipped with a specifically designed, innovative Silicon photo-multiplier (SiPM) camera managed by very fast read-out electronics.
The observations of the Crab Nebula were carried out between December 2018 and January 2019, during the ASTRI-Horn telescope verification phase, for a total observation time of about 29 hours, divided in on- and off-axis source exposure. The camera system was still undergoing assessment, and its functionality was not fully exploited. Moreover, owing to recent eruptions of the Etna Volcano, the mirror reflection efficiency was partially reduced. In spite of such camera and mirrors limitations, observations yielded the detection of the Crab Nebula with a statistical significance of 5.4s above an energy threshold of about 3.5 TeV, definitively probing the new technologies and opening a new era for IACT.
“The result obtained by ASTRI is an important milestone for the IACT technologies. It is demonstrating that the dual mirror configuration, firstly proposed by the great German Astrophysicist Karl Schwarzschild more than a century ago, is performing well. It is now possible to achieve a very large field-of-view with a much more compact Cherenkov telescope design, easily observing very energetic cosmic gamma-rays up to a few hundreds of TeV” says Giovanni Pareschi, astronomer at the INAF-Milano and principal investigator of the ASTRI project.
The universe is almost 14 billion years old. An inconceivable length of time by human standards – yet compared to some physical processes, it is but a moment. There are radioactive nuclei that decay on much longer time scales. With the XENON1T detector at the INFN Gran Sasso National Laboratory, scientists were able to observe the decay of Xenon-124 atomic nuclei for the first time.
The half-life of a process is the time after which half of the radioactive nuclei present in a sample have decayed away. The half-life measured for Xenon-124 is about one trillion times longer than the age of the universe. This makes the observed radioactive decay, the so-called double electron capture of Xenon-124, the rarest process ever seen happening in a detector. “The fact that we managed to observe this process directly demonstrates how powerful our detection method actually is – also for signals which are not from dark matter,” says Prof. Christian Weinheimer from the University of Münster (Germany) whose group leads the study. In addition, the new result provides information for further investigations on neutrinos, the lightest of all elementary particles whose nature is still not fully understood.
XENON1T is a joint experimental project of about 160 scientists from Europe, the US and the Middle East. The results were published in the science journal “Nature” (preprint on the arxiv).
The full press release is available from their website: http://www.xenon1t.org/ and further information is also available here.
The European Particle Physics Update (EPPSU) process is conducted by CERN and it gives the guidelines for the future years to the particle physics community on scientific and technological programs, organizational aspects, knowledge and technology transfer as well as interaction with society, education and outreach
