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
The final workshop of the SENSE project is planned as an open meeting to present the final SENSE Roadmap and the recommended strategy towards developing the ultimate low light-level photosensors. Some other elements of SENSE will be also introduced and discussed how they can sustain after SENSE. The meeting will take place on July 9th, 2019 at the campus of the ALBA Synchrotron outside Barcelona, Spain. A dinner with discussion will be held the previous night, July 8th.
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.
Interview with Sera Markoff on the first image of a black hole
On April 10th 2019, the Event Horizon Telescope (EHT) Collaboration presented its first results – an image of the supermassive black hole in galaxy M87 – in multiple simultaneous press conferences around the world, see also here in the APPEC news. Sera Markoff is working on EHT and also on CTA. In this interview she tells us about the exciting times with EHT and the connection to multimessenger astroparticle physics.
Sera, you are enjoying the well-deserved success for the wonderful result on the first image of a black hole in the centre of the M87 galaxy. What is that impressed you most about this success story?
First image of black hole in galaxy M87, credits: Event Horizon Telescope
I think the reaction of the world to our result was not something we had fully anticipated. Gravitational waves were also a ground-breaking result but I don’t think they made it quite so far particularly in social media, because it was maybe a bit too abstract for many members of the public. The image triggered a lot of hilarious posts and memes, which I think is a very positive sign that the world wanted to claim a sort of ownership of the result, and make it relevant to their lives in some way.
What are the next targets and steps?
We still have an enormous amount of data from 2017 and 2018 to analyze, from both the horizon targets (M87 and Sgr A*) as well as many other jetted AGN, some of which were also calibrators for the horizon sources so we have lots of hours on them. These include for instance 3C279, OJ287, and quite a few more. The data analysis and image reconstruction is very tricky particularly for variable sources like Sgr A* so the collaboration are working hard, and one can expect much more science to come. We have also proposed for observations again in 2020, so encourage multi-wavelength facilities to coordinate with us then!
What will be the kind of targets for which you will attempt the reconstruction of the inner jets?
As I mentioned above, these are mostly radio galaxies for obvious reasons, we want sources with well studied jets from other wavelengths particularly with VLBI so we can add another piece at the highest resolution, closest to the core.
You are also working in CTA, hence could you highlight possible connections between the EHT work and the astroparticle community working on multi-messengers high energy astrophysics? What do you expect that can be done in synergy ?
Well EHT is not its own instrument, we use existing facilities during about 10-12 days per year in this special mode. So it’s hard to say whether EHT will exist in its current form when CTA is open for business, but we certainly hope so. We are already adding new elements to the array since 2017, and hopefully will be able to go to higher frequency soon as well. The systems we are studying, with the exception of Sgr A*, all show powerful jets and are high-energy emitters, but we still do not fully understand how these jets are launched, or their internal properties, and there is of course significant debate about the origin of the VHE gamma-ray emitting particles. Where particle acceleration happens exactly, and via which process (e.g., diffusive shock acceleration vs magnetic reconnection) is something one might be able to resolve, if there happened to be a VHE flare during an EHT observation and we could actually resolve associated structural changes in the jet with EHT. I think that is the ‘holy grail’ we would all like to see. We are already observing together with existing VHE facilities like H.E.S.S., MAGIC and Veritas, so this may even happen before CTA and then the work could continue even deeper once we have the much better spatial resolution in the VHE range that CTA offers.
Sera Markoff is a professor of theoretical high energy astrophysics at the University of Amsterdam. Her research focuses on the interface between astrophysics and particle physics, in particular problems relating to processes occurring around dense objects such as black holes. She is a member of a number of large scale research projects including Cherenkov Telescope Array and Event Horizon Telescope, which produced the first image of a black hole. She is a member of the leadership of the Event Horizon Telescope project where she serves as a member of the science council and as one of the working group coordinators.
The 16th International Conference on Topics in Astroparticle and Underground Physics (TAUP2019) will be held at the Toyama International Conference Center, Toyama, Japan, on September 9-13.
The biennial TAUP series covers recent experimental and theoretical developments in astroparticle physics by invited plenary review talks and parallel workshop sessions of invited and contributed presentations. The conference is hosted by ICRR, The University of Tokyo, and supported by Kavli IPMU, The University of Tokyo and University of Toyama.
Topics:
Cosmology and particle physics
Dark matter and its detection
Neutrino physics and astrophysics
Gravitational waves
High-energy astrophysics and cosmic rays
Registration will be open until August 8, with early registration until June 30. The deadline for submitting parallel session and poster presentation abstracts for TAUP2019 has been extended to May 31, 2019.
Interview with Juan José Gómez Cadenas about the NEXT experiment
Recently, a committee working on neutrino less double beta decay, composed by Silvia Pascoli (Chair, Durham U.), Andrea Giuliani (CSNSM), Juan Jose Gomez-Cadenas (DIPC), Ezio Previtali (INFN, MI) Ruben Saakyan (UCL), Karoline Schaeffner (GSSI), Stefan Schoenert (TUM), was set in place in order do define a document describing the efforts towards a new generation of more sensitive detectors than the current existing, which will include a SWOT analysis and a critical evaluation of resources and possible schedules. This document, to be approved in the Scientific Committee of APPEC, will set the guidelines for funding agencies in the General Assembly to understand expected sensitivity of various technologies and scientific goals and reach of various techniques. A great effort is ongoing and one of them recently obtained an experimental success. Juan Jose Cadenas explains more on it.
What is your technical achievement and how does it compare to past existing ones?
NEXT detector
Energy plane illuminated with an UV lamp
Impressions of NEXT-WHITE
NEXT is a high pressure xenon chamber with electroluminescent readout (HPXeEL). It exploits three features of gaseous xenon which are essential to suppress backgrounds in neutrino less double beta decay searches (ββ0ν): excellent energy resolution; the capability of reconstructing the event topology; the capability of identifying the Ba++ ion produced in the ββ0ν decay. The first phase of the experiment, the so-called NEXT-White detector, deploying 10 kg of xenon is currently operating at the Laboratorio Subterráneo de Canfranc (LSC), and the second phase, NEXT-100, with 100 kg of xenon is currently being assembled, with the plan of commissioning in 2020. We are also preparing a Conceptual Design Report (CDR) for a ton-scale detector.
With respect to the pioneer St. Gotthard TPC experiment, which operated at the St. Gotthard tunnel in the mid 1990’s, NEXT introduces two main innovations. The first one is the electroluminescent proportional amplification of the signal (EL), which results in a (measured) energy resolution of 0.5 % FWHM at Qbb (for point-like particles), and better than 1 % FWHM for long tracks (to be compared with 7 % FWHM at Qbb achieved by the St. Gotthard TPC). NEXT is currently the only high-resolution xenon experiment searching for ββ0ν. Furthermore, it is possible to operate NEXT with pure xenon, since no quenching of the ionisation is needed (as was the case for the St. Gotthard TPC), and therefore the scintillation signal is preserved, providing the start-of-the-event and thus the needed fiducialization in Z.
Furthermore, the NEXT collaboration has recently published a proof-of-concept that shows the possibility to capture and identify the Ba++ ion produced in the ββ0ν decay using the so-called SMFI (Single Molecule Fluorescence Imaging) technique. SMFI was invented by physicists and then applied with great success to biological problems. In 2015, Dave Nygren, co-spokesperson of NEXT proposed to use SMFI to tag the presence of the Ba++ ion. In 2017 we published a PRL showing that it is possible to follow the trajectory of single fluorescent molecules chelated with a Ba++ ion, thus opening up the possibility of developing such detection system in NEXT.
Last but not least, NEXT has been developed through a set of carefully planned stages, involving 1-10-100 kg detectors, in order to master the technical details which will allow the extrapolation of the technology to ton-scale detectors.
What is the relevance of your measurements on enriched Xe and what measurements will be particularly improved thanks to it?
Our current run with enriched xenon has two goals. We aim to measure the ββ2ν mode lifetime, which in addition to provide another measurement of this important quantity (there are previous measurements by KamLAND-Zen and EXO), will allow us to quantify with great detail the rejection power of the topological signature. Furthermore, the enriched xenon run will allow us a full characterization of the background budget of the detector.
What is the impact this will have in NEXT and neutrinoless double beta decay?
NEXT is the only high-energy resolution experiment based in xenon. Furthermore, the identification of the two electrons results in a very low background rate in the region of interest (ROI). If we can implement Ba++ tagging, NEXT could evolve into a truly background-free experiment. This is a must to explore very long lifetimes, and thus exploring the inverse and eventually the normal hierarchy.
Are underground laboratories in Europe a great resource and how do you see that they will evolve in next years?
Yes, they are, and Europe science is benefiting immensely from these facilities, with leading experiments in ββ0ν, dark matter and other underground physics areas. I would like to see European underground labs evolving toward a tight network that would permit an intense cooperation in underground science in Europe. Indeed, I believe that this network can be expanded at the truly international level. In the case of NEXT one could very well imagine that such underground lab network would permit the operation of several modules in the range of 500–1000 kg at LSC and LNGS, and possibly in SNOWLAB. It is important to remark that our experiments are run by international collaborations, and the creation of an international network of laboratories could permit far-ahead planning and optimisation of resources. As we are moving into very large and complex apparatus in rare searches, this international network of labs appears essential.
Juan José Gómez Cadenas at the LSC, with the detector in the background
Juan José Gómez Cadenas is an Ikerbasque professor of physics at the Donostia International Physics Center. He has worked in neutrino physics for the last 25 years, contributing to experiments such as NOMAD, K2K and T2K. In 2008 he proposed the NEXT experiment to the LSC. He is the co-spokesperson of NEXT, together with Dave Nygren, inventor of the Time Projection Chamber.
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 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
