On July 7th the LUX-ZEPLIN (LZ) Collaboration has released their first results on searching for Weakly Interacting Massive Particles (WIMPs), a candidate for dark matter. LZ is a detector installed at about 1500 m below ground in the SURF underground laboratory in South Dakota in the US (https://www.sanfordlab.org). The LZ is an international Collaboration with 287 members from different continents. LZ represents the continuation of a research program which begun with the LUX experiment. LZ is replacing LUX with a more advanced and sensitive detector.
The new results are derived from 65 days of exposure and establish a new record in searching for WIMPs. This is a tiny fraction of the 1000 days foreseen for the LZ project. WIMPs are a well-known candidate for dark matter. Dark matter accounts for 85% of all matter, therefore unveiling the nature of dark matter is a major challenge for science these days.
LZ is 7 ton active liquid xenon TPC, 1.5 m in diameter and height, viewed by 494 3-inch photosensors. The assembly of the TPC has been carried out in a radon-free clean room on ground at SURF before moving it underground inside the cryostat.
For the first time LZ has exploited in its outer detector an active neutron veto consisting in 17 ton of Gd-loaded liquid scintillator. The TPC and neutron veto are inside a water tank instrumented with 120 8-inch photosensors, which works as an active muon veto.
LZ data are consistent with the background-only hypothesis above the small tested WIMP mass of 9 GeV/c2. In the spin-independent scenario the WIMP-nucleon cross section is probed at the unprecedented level of 5.9×10-48 cm2 for a WIMP mass of 30 GeV/c2. In spite of this null result, LZ shows a crucial progress in hunting for dark matter and demonstrate the excellent performance of the detector waiting for more to come.
A paper describing the results can be found here. A recording of the presentation can be viewed on YouTube here. The slides from the presentation as well as supplemental material referenced in the paper can be found here.
The LZ central detector in the radon-free clean room at SURF after assembly. Photo by Matthew Kapust (https://www.sanfordlab.org)
Members of the LZ collaboration in the water tank after the outer detector installation.
Photo by Matthew Kapust (https://www.sanfordlab.org)
LZ Outer Detector. Photo by Matthew Kapust (https://www.sanfordlab.org)
The workshop on European Underground Laboratories took place at LNGS. Credits: Antonio Giampaoli/ LNGS
A Workshop on EU Underground Laboratories was held at LNGS on 28-29 April. The Workshop was jointly organized by LNGS and APPEC (https://agenda.infn.it/event/30742/).
The purpose of the Workshop was to facilitate and promote an executive network between Underground Laboratories in Europe to better face next generation experiments.
Contributions from LNGS (Italy), LSC (Spain), LSM and LSBB (France), CLAB (Finland), Boulby (UK), HADES (Belgium), ChETEC-INFRA (Germany), Romania and Poland were reported during the Workshop.
A final round table with lab directors established a willingness to initiate regular meetings to assess the present state of infrastructure in order to identify common interests and future collaborations.
The aim of this ECFA-NuPECC-APPEC working group is to find ways to improve the recognition of individual achievements in large collaborations. The working group was installed in July 2019 in Ghent. It continues previous work by ECFA, which among other activities performed a community-wide survey in 2018. Meetings with the collaborations were held separately for the three communities in two rounds, first in June-July 2020 and then in Oct-Nov 2020. A questionnaire was prepared and sent to the participating collaborations from all three communities in late 2020 and has been evaluated. A report summarizing the results has been prepared, circulated in the community and presented at the JENAS meeting in May 2022 in Madrid. Based on the feedback, a final version has been prepared that can be downloaded here.
Background: a composition of the center of the milky way (custom composition of three different wavelengths images)and a deep star map by NASA’s scientific visualization studio
Earth: textures are from NASA blue marble, 3D rendering from Simon Barke
LISA constellation: Simon Barke
Credts: NASA/JPL-Caltech/NASAEA/ESA/CXC/STScl/GSFCSVS/S.Barke (CC BY 4.0)
LISA, the future gravitational wave observatory in space, has passed major milestones and is expected to fly in the mid-2030s. Recent developments of LISA include the review of technologies and planning according to ESA´s standard development logic, and the U.S. National Academy of Sciences’ Decadal Review. LISA has successfully mastered both milestones:
Mission Formulation Review and begin of Phase B1
LISA, the Laser Interferometer Space Antenna, has reached an important milestone: it has passed the comprehensive “Mission Formulation Review” (MFR) and entered the next phase of development, Phase B1. The MFR review team, consisting of experts from ESA, NASA, the scientific community and industry, identified no showstoppers and confirmed that LISA has successfully reached a maturity sufficient to proceed to the next stage. The MFR is a prerequisite for mission development to continue. In an ESA mission lifetime cycle, the MFR is the formal end of Phase A (mission feasibility). Building upon the foundations laid in Phase A, the team now focuses on developing the requirements guidelines for the mission.
“LISA is well underway. In Phase B1 we do more detailed design work to establish the complete set of mission requirements and the verifications approach”, says Prof Karsten Danzmann, Lead of the LISA Consortium.
Martin Gehler, LISA Study Manager at the European Space Agency, adds: “The review was a major success for all stakeholders and the fruit of vigorous work on Consortium, NASA, and ESA side over the last years.”
Transitioning into Phase B1 finally lifts the mission out of concept studies and marks a major milestone for all of the scientists and engineers involved. With an implementation duration of around 10 years, LISA is expected to fly in the mid-2030s and, following a year-long cruise to its final, low-disturbance destination, can start to fulfil its mission to observe gravitational waves from space and enable new scientific discoveries.
US National Academy of Sciences highlights LISA as a New Window on the Dynamic Universe
The US National Academy of Sciences has noted the important presence in the NASA Program of Record for the implementation and execution of the LISA Mission, led by the European Space Agency. In the Astrophysics Decadal Survey, a panel of experts evaluated and prioritized research activities in astronomy and astrophysics in the coming decade. The survey noted the “tremendous promise” of the future gravitational wave space mission LISA because of the expectation that observations of gravitational waves in space will make “astronomical measurements that will change paradigms.”
LISA International Symposium
The online LISA International Symposium took place from July 25-29 and was organized by the Institute for Gravitational Research of the University of Glasgow. Updates on all areas of the project were presented during this meeting and recors of the talks are available here:
LISA Through observations of gravitational waves, LISA will offer an unprecedented and unique view of the Universe, quite different from any other space telescope and any ground-based gravitational-wave detector. LISA will deliver pioneering scientific results enabling insights not available through electromagnetic observations.
Combining LISA observations with those of other ground- and space-based facilities will also allow scientists to make enormous advances in multi-messenger astronomy.
LISA will observe gravitational waves in a lower frequency band than those detectable by LIGO and Virgo, allowing us to observe much larger systems at earlier times in the Universe’s history.
The LISA instrument will consist of three spacecraft in a triangular configuration with 2.5 million kilometer arms, moving in an Earth-like orbit around the Sun. Gravitational waves from sources throughout the Universe will produce slight oscillations in the arm lengths (smaller than the diameter of an atom). LISA will capture these motions and thus measure the gravitational waves by using laser links to monitor the
displacements of test masses free-falling inside the spacecraft. The LISA satellites are being built by ESA, ESA member nations, and NASA.
LISA´s hardware got its first and very successful test in space with the LISA Pathfinder (LPF) mission, led by ESA with NASA participation. This included a thorough test of crucial components of LISA´s technology. LPF demonstrated that it’s possible to place and maintain test masses in free-fall to an astonishing level of precision, and that the exquisite metrology needed for LISA meets the requirements.
The LISA Consortium is a large international collaboration that combines the resources and expertise from scientists in many countries all over the world. Together with ESA as the lead agency and NASA as an international partner, the LISA Consortium is working to bring the LISA mission to fruition.
Round table discussions during the Town Meeting.
Credits: AAPEC/ Ashley Jones
On the 9th and 10th of June about 100 Astroparticle Physicists met in Berlin to discuss the Midterm review of the European Astroparticle Physics Strategy 2017-2026. The aim of the Town Meeting was to receive a final feedback from the community on the implementation process of the Astroparticle Physics Strategy with respect to the international context, and the new developments in Astroparticle Physics and neighbouring fields that could lead to further evolution of the strategic recommendations.
As input to the Town Meeting, written community feedback was obtained over the last months and together with the oral feedback from the Town Meeting, the APPEC Scientific Advisory Committee will release a draft Strategy Update document by fall for final community feedback. The Strategy Update is expected to be released by APPEC before the end of the year.
The first day of the town meeting was dedicated to discussions in small groups. According to their stated interests, the participants were put into mixed discussion groups with 4-6 participants and 14 different topics were discussed in eight rounds. In addition, there was the opportunity to discuss further topics during the “Open microphone speeches”.
After initial skepticism, this concept was subsequently highly praised and contributed a great deal to the successful outcome of the meeting. Especially after the long Corona break, without face-to-face meetings, the need for informal and personal discussions was very high and sufficient time was made available for these, which was gratefully appreciated by the participants.
Group picture
Credits: APPEC/ Ashley Jones
In the late afternoon and evening of the first day the outcomes of the discussions were collected by the table hosts together with the topical summary speaker who presented the results on Friday morning. From all the summary talks, it was the task for the APPEC SAC Chair to identify the most important topics and how to incorporate them into the midterm review and finally the update document. This was presented in a final presentation on Friday afternoon.
Christian Spiering has worked in Russia for more than four years in the 1970s and has collaborated with Russian researchers for almost fifty years. Russia with its language, its literature and its people became a kind of second cultural home for him. In the early APPEC/ASPERA period he chaired several roadmap processes and he initiated the Global Neutrino Network, a network in which neutrino astronomers from different countries and from several experiments work together. Russia’s attack on Ukraine has currently made such collaborations impossible. This war affects in first order the Ukrainian people and Ukrainian scientists but also has a huge impact on science in Europe as a whole and in particular on collaborations with Russian scientists. These aspects will be discussed in the following interview.
You have always worked closely with Russian scientists. How has this collaboration changed since the start of the war in Ukraine?
Before answering your question, let me make a general remark: I admit that I belonged to those who have tried to understand and to explain Russian policy, even to some degree Putin’s policy, and who see themselves disproved since February 24. I am also aware that with respect to the emergence of this conflict, there is no simple black and white. Historians will weigh the arguments of all sides against each other, including also those about chances missed by Western and Ukrainian policy. But whatever mistakes may have been made from all sides: nothing, really nothing justifies a war, and nothing justifies the support of the aggression against Ukraine.
Now to your question.
Let me give you a simple example: I am chairing the Technical Advisory Board of Baikal GVD and I am a member of its strategic Advisory Committee. Just in February we had sessions of these two committees and wrote detailed recommendations, including the advice to broaden the basis of the experiment by inviting more international collaboration partners. Now, a bit more than a month later, we neither could perform such sessions, nor would we write recommendations. The advice to invite more international partners at present would sound bizarre, to say the least.
Within the Global Neutrino Network, Baikal GVD is also part of transnational multi-messenger activities which – regrettably for all sides – will suffer from the present situation.
Another case is the TAIGA experiment in Siberia, with strong intellectual and hardware contributions from Germany. For the time being, Germans will not travel to Russia and participate in detector upgrade and operation. Parallel analyses in Germany and Russia are continuing, but when and how this could lead to a jointpublication is open. Another example is the FACT Cherenkov telescope in La Palma which was foreseen to be transported to the TAIGA site; if and when this could happen is currently written in the stars. On another note will be experiments like LEGEND, CUPID and others which used to (or have planned to) obtain purified materials from Russia. They might have to look for other, likely more expensive suppliers.
Are there still opportunities to work together with Russian colleagues?
For the moment all cooperation with Russian institutions has been frozen. I believe that – if artists and sportsmen cancel their participation in joint events – scientists should also send a strong signal against this completely unjustified and brutal war. There is no question that contacts will be resumed at some point after the end of the war, or at least after a ceasefire. This will certainly start with small projects shaped by individuals. However, I personally would find it difficult to come back to common work, such as if nothing had happened, with someone who has openly supported the invasion of Ukraine.
How do you assess the situation for science and scientists in Russia?
Russian scientists will be, or are already, the first to suffer with respect to their work. This starts with the possibilities to participate in international projects in the West, to be accepted as speakers on conferences, with problems to sign with their Russian affiliation on joint publications, and continues with the availability of high-tech components for experiments in Russia, like, e.g., the Baikal Gigaton Volume Detector or the TAIGA observatory.
On a completely different note is the exodus of excellent scientists, among them those of whom Putin says he “spits them out like a mosquito that has got into his mouth” (a formulation which reminds me of the darkest times in Germany as well as in Soviet Union). Historical situations are difficult to compare, but somehow this could become a version of the exodus of brilliant minds from Germany in the 1930s.
On the one hand, there is a declaration, signed by several thousand Russian scientists, against the war; on the other hand, Russian universities have issued a statement in which they express their full support for Putin’s politics. How can we deal with these different attitudes?
I have the deepest respect to the signatories of the letter against the war – for their clear inner compass and for their courage. For me, the rectors of the Universities who signed the second letter range on a similar level as all the Duma members, ministers and governors who have silently carried out the illegal orders of the government and therefore bear a considerable share of the blame for the current situation. Note, however, that some rectors did not sign this nasty document and that the names of some of them seem to have been inserted without their own knowledge. Also, a non-negligible number of faculty members and students signed a letter against that of their rectors – with consequences for them which likely will become fully visible only after the war.
I have no clear idea how to deal with that. The general principle should be to support the signatories of the anti-war letters wherever possible, and avoid the cooperation with the intentional signatories of the rector’s letter if any possible. How to translate this into action in concrete situations will have to be seen. For the duration of the war, a proper selectivity seems impossible, so I would vote for freezing any official cooperation until the weapons are silent and a ceasefire is reached, however fragile it may be.
Whatever we do, we should keep in mind, that Russian science does not only consist of Universities and Research Institutes, but is made up of thousands of unexpectedly isolated researchers, a large proportion of whom condemn war, even though they may disagree with us about its causes. I will keep the contacts to my Russian friends, and I fervently hope for a time when we see each other in person and can work together again.
Many collaborations and scientific institutions are currently discussing how to combine good scientific practice and the sanctions against Russia and how to deal, for example, with joint publications. What is your opinion on this?
I think that withdrawing already submitted publications is not a good way. Work on publications in preparation, however, might easily be paused – this kind of “freezing” does not violate good scientific practice. Let’s be honest: for more than 99.9% of all possible publications, at this very moment a clear sign against the war is more important than their delay by a few months (I hope that this time scale does not turn out to be an illusion).
In any case, I would wish that the APPEC countries find a coordinated answer to this question.
Do you expect an increasing number of Russian refugees, including scientists? How should we as a scientific community deal with these?
Journalists, writers, artists and scientists are probably the most exposed and vulnerable groups. The European governments should create a support program so that our Universities and research institutes are enabled to create positions for exiled Russians and to integrate them in our research landscape. Given the excellent scientific quality of many of the Russian opponents to the war, this would certainly turn out as a clear benefit for astroparticle and particle physics in western countries.
You yourself live in Berlin, where many Ukrainian refugees are currently arriving. How do you personally experience this situation?
Together with a few others, I am taking care of eight Ukrainian women with their 13 children. At the beginning, they were accommodated in a hostel, but without meals. So, we prepared breakfast and dinner for them for a fortnight. Meanwhile we could accommodate them in four flats and are helping them with all the confusing formalities – financial support, health insurance, language lessons, etc. Most of them want to go back to Ukraine as soon as the war is over.
A Russian-speaking colleague of mine, also retired, took a job as a full-time teacher of Ukrainian kids. In general, there is great support from volunteers, and even the cumbersome Berlin bureaucracy is – slowly but steadily – getting into gear.
This interview took place on 2 April 2022.
Further information
Database of positions and accommodation for Ukrainian students and researchers: Science for Ukraine
Christian Spiering (born 1948) studied Physics at Humboldt University Berlin. 1974-78 he worked at JINR Dubna. Having started his carrier with hadron-nucleus interactions, he moved to a neutrino experiment at Protvino/USSR, and 1988 to neutrino astrophysics – starting with the neutrino telescope in Lake Baikal, later AMANDA at the South Pole, and ending up with IceCube. Being engaged in “two worlds”, he initiated the Global Neutrino Network in 2014. He worked also in the Tunka/TAIGA air shower experiments in Siberia. Christian served as AMANDA European Spokesperson and later IceCube spokesperson. From 2006 to 2012 he chaired the APPEC Peer Review Committee. He was awarded the Markov Price of the Russian Academy of Sciences and the O’Ceallaigh-Medail of the Dublin Institute for Advanced Studies. He is author of two popular-scientific books, quite recently “Neutrino astronomy – looking to hidden worlds”.
Artist’s impression of the white dwarf and red giant binary system following the nova outburst. (Credits: DESY/H.E.S.S., Science Communication Lab)
In a publication in Science, the H.E.S.S. collaboration has for the first time described the time sequence of the acceleration process in a nova.
Novae are a source of high-energy particles and photons and RS Ophiuchi (RS Oph) is a recurrent nova system comprising a white dwarf and a companion red giant star. RS Ophiuchi exploded on August 8, 2021 and the H.E.S.S. telescopes were turned to the constellation in the night after the first sightings and promptly detected the explosion. The observations continued for more than one month, resulting in an exquisitely covered light-curve of the event.
The paper ‘Time-resolved hadronic particle acceleration in the recurrent nova RS Ophiuchi’ describes the spectral and temporal properties of the gamma-ray emission. They reveal that it takes longer to reach maximum brightness at the highest energies compared to less energetic light and offers insights that allow a more profound understanding of such explosions.
Credits: Image: Photography: Luca Zanier; Artwork: Leonard Köllenberger, Karlsruhe Institute of Technology. Cover Design: Amie Fernandez, Nature Physics
The international KArlsruhe TRItium Neutrino Experiment (KATRIN) located at Karlsruhe Institute of Technology (KIT) has now been the first to constrain the mass of neutrinos to less 1 electron volt (eV) and, hence, has broken an important “barrier“ in neutrino physics. From the data recently published in Nature Physics, a new upper limit of 0.8 eV has been derived for the mass of the neutrino. These results obtained by means of a model-independent laboratory method allows KATRIN to constrain the mass of these “lightweights of the universe” with unprecedented precision. The publication is available here: DOI: 10.1038/s41567-021-01463-1
The results have also been presented in a public outreach event in German. The presentation is still accessible via the following website: https://www.katrin.kit.edu/leicht-leichter-neutrinos.php
Sketch from the illustrator Julie Borgese. She was invited to capture the atmosphere of the symposium and to transform scientific concepts into pieces of art.
After being canceled in 2020 due to COVID-19 restrictions, the 2021 edition of the Paris-Saclay Astroparticle Symposium was organised from October 18 to November 26, 2021 at the Institut Pascal of the Paris-Saclay university. The organisation of this event was made possible thanks to support from P2IO, the P2I graduate school of the University of Paris-Saclay, IN2P3, APPEC and CEA. The symposium was a great success: nearly 230 researchers participated either by being present at the Pascal Institute (about 40 per week, many staying for several weeks) or by participating via videoconference.
The symposium was aimed at researchers specialised in the broad field of astroparticle physics, who were invited to come and work at the Institut Pascal in order to initiate, pursue or finalise research projects and publications. The format of the symposium is particularly well suited for this purpose, with a limited number of plenary sessions dedicated to presentations and leaving a significant amount of time reserved for joint work and informal discussions.
Due to the cancellation of the 2020 edition it was decided to extend the duration from the usual 4 to 6 weeks in 2021. Each week focused on specific topics and followed a similar outline: moderated by one or more specialists, informal discussions of about 2 hours on a specific topic triggered very fruitful exchanges and initiated joint works. One day per week was dedicated to presentations by participants who wished to present their work.
The following topics were discussed during the symposium (the details of the different sessions are available on the event website https://indico.ijclab.in2p3.fr/event/7119/):
Week 1: Galactic Cosmic Rays
Week 2: Ultra-High Energy Cosmic Rays
Week 3: Dark Matter: Theories
Week 4: Dark Matter: Theories versus Experiments
Week 5: The transient sky (GWs and compact objects, multi-messenger astronomy)
Week 6: Gravitational waves, theoretical point of view
In addition, a series of seven lectures for the general public, given by well-known external speakers, was organised. These lectures took place in the evening at the Institut Pascal and were a great success. Finally, an illustrator was invited to capture the atmosphere of the symposium and transform certain scientific concepts into pieces of art. A first sketch is shown below.
The 2022 edition of the Paris-Saclay Astroparticle Symposium is already in preparation!
Mark your agenda: it will take place from October 31 to November 25, 2022 at the Institut Pascal of the Paris-Saclay university.
Composition of the Paris-Saclay Astroparticle Symposium 2021 organising committee:
Fabio Acero (AIM, CNRS/INSU)
Philippe Brax (IPhT CEA)
François Brun (CEA/IRFU – Department of Particle Physics)
Olivier Deligny (IJCLab, CNRS/IN2P3)
Carla Macolino (IJCLab, CNRS/IN2P3)
Yann Mambrini (IJCLab, CNRS/IN2P3)
Fabian Schüssler (CEA/IRFU – Department of Particle Physics)
List of scientific symposia :
The implications of discovery of PeVatrons, by Zhen Cao
Perspectives in Astroparticles, by Andreas Haungs
Searching for ultra light dark matter and gravitational waves with atom interferometers, by John Ellis
Strategies for European astroparticles, by Gianfranco Bertone
Multi-messenger astronomy including gravitational waves, by Marica Branchesi
The Cherenkov Telescope array and its science, by Werner Hofmann
List of public lectures :
Physics in science fiction films, by Richard Taillet
Why the sun shines, by Roland Lehoucq
What is the vacuum full of, by Étienne Klein
A history of the Universe: from the Big Bang to the present day and beyond, by Yann Mambrini
Seeing and hearing black holes, by Alain Riazuelo
The arrow of time, from molecular billiards to the dance of stars, by Cédric Villani
Thirty years of progress in astrophysics, by Hervé Dole
The “Low-latency alerts and data analysis for Multi-messenger Astrophysics workshop”, organized with the support of the H2020 funded project AHEAD2020, the APPEC consortium, IN2P3, APC Laboratory and EGO was held on 13-14 January online. The workshop, the first of a series, gathered over 150 participants and aimed to provide an overview of the existing and future developments from a data analysis perspective of the space-based and ground-based infrastructures, identify and discuss technical issues and foster new interactions and community building around the multi-messenger data analysis science and tools. Together with the future events on this topic of paramount importance to be announced in the first half of the year by the committee, the long term goal is to contribute to the emergence of a common path towards a more integrated approach for the multi-messenger astrophysics data analysis. The contributions can be found here: https://indico.in2p3.fr/event/25290/contributions/
