Vol. 30 No. 1 (2020)

Nuclear Physics News is published on behalf of the Nuclear Physics European Collaboration Committee (NuPECC), an Expert Committee of the European Science Foundation, with colleagues from Europe, America, and Asia.

Editor: Gabriele-Elisabeth Körner Editorial Board Angela Bracco, Milano (Chair) Richard Milner, MIT Rick Casten, Yale Eugenio Nappi, Bari Rolf-Dietmar Herzberg, Liverpool Klaus Peters, Darmstadt Rituparna Kanungo, Halifax Hermann Rothard, Caen Marek Lewitowicz, Caen (NuPECC Chair) Hideyuki Sakai, Tokyo Yu-Gang Ma, Shanghai Calin Ur, Bucharest

Editorial Office:Physikdepartment, E12, Technische Universitat München, 85748 Garching, Germany, Tel: +49 89 2891 2293, +49 172 89 15011, Fax: +49 89 2891 2298, E-mail: [email protected]

Correspondents (from countries not covered by the Editorial Board and NuPECC) Argentina: O. Civitaresse, La Plata; Australia: A. W. Thomas, Adelaide; Brasil: N. N., São Paulo; India: S. K. Mandal, New Delhi; Israel: N. Auerbach, Tel Aviv; Mexico: E. Padilla-Rodal, Mexico DF; Russia: Yu. Novikov, St. Petersburg; Serbia: S. Jokic, Belgrade; South Africa: M. Wiedeking, Cape Town.

Nuclear Physics News ISSN 1061-9127

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Vol. 30, No. 1, 2020, Nuclear Physics News 1 Nuclear Physics Volume 30/No. 1 News

Contents Editorial Why Do We Strive to Have EU Integrating Activities for Nuclear Science Facilities? by Angela Bracco and Muhsin Harakeh...... 3 Laboratory Portrait JINR at the Forefront of Nuclear Research by Boris Sharkov...... 4 Feature Articles Novel Excitation Modes in Nuclei: Experimental and Theoretical Investigation on Multiple Chiral Doublets by Q. B. Chen and J. Meng...... 11 Impact and Applications Characterization of Radiation Effects and Ion Tracks with Spallation Neutron Probes by Maik Lang, Eric O’Quinn, Jörg Neuefeind, and Christina Trautmann...... 16 The Sound of Ions: Acoustic Detection of High-Energy Beams by Walter Assmann and Katia Parodi...... 20 Verification of Arms Control Treaties with Resonance Phenomena by Areg Danagoulian...... 25 Meeting Reports Founding of the International Biophysics Collaboration (IBC) by Marco Durante, Yolanda Prezado, and Vincenzo Patera...... 31 Sunny “Strangeness in Quark Matter” in Bari by Domenico Elia...... 32 TAN 19: International Superheavy Element Research Community Met in Wilhelmshaven, Germany by Michael Block, and Ch. E. Düllmann...... 33 JENAS: Astroparticle, Nuclear, and Particle Physicists Meet by Marek Lewitowicz...... 35 Quark-Gluon Plasma in Wuhan: Quark Matter 2019 by Heng-Tong Ding, Feng Liu, Ben-Wei Zhang, and Enke Wang...... 36 News and Views Multimedia Spectacle At the Intersection of Two Infinities at the 45th Congress of Polish Physicists in Krakow (Poland), 13–18 September by Adam Maj and Mark Riley...... 37 The International Year of the Periodic Table of Chemical Elements by Krzysztof Piotr Rykaczewski...... 38 Superheavy Elements at the Closing Ceremony of the IYPT2019 by Hideto En’yo ...... 39 In Memoriam In Memoriam: Peter von Brentano (1935–2019) by Rick Casten and Alfred Dewald...... 40

Cover Illustration: The Gas-Filled Recoil Separator at JINR Dubna - see article on page 4.

2 Nuclear Physics News, Vol. 30, No. 1, 2020

30 1 00 00 editorial

Why Do We Strive to Have EU Integrating Activities for Nuclear Science Facilities?

The main motivation for the European in Europe for studying the properties of In spite of the great success obtained Commission (EC) to fund Integrating nuclear matter at extreme conditions, and up to now with the ENSAR2 project and Activities (IAs) is to offer transnational developing nuclear physics instrumenta- more recently with STRONG-2020, we access to Europe’s leading research infra- tion and experimental techniques to open think it is important to continue to also structures, including those of Nuclear new scenarios for fundamental research receive EU support for IAs in the years Physics; foster interaction and collabora- and to employ them for new societal and to come. This is not because of the funds tion between a large number of research industrial applications. Special attention per se but rather because of the very high groups at universities and national labora- was also given to the long-term sustain- value that this funding has for the commu- tories via Networking Activities; and help ability perspective of the integration of nity in sowing the seeds for new excellent to develop, for example, new high-tech relevant facilities and related resources. scientific research and developments to be equipment and methods for research and Furthermore, the project was also targeted carried out jointly by several facilities. applications via Joint Research Activities. to new users in order to take full advan- Ever since we started receiving EU Within the field of Nuclear Physics, two tage of new possibilities/opportunities funds under these types of EU calls the different IAs serving different sections offered in particular by the participating collaborative spirit in our community has of the Nuclear Physics community have infrastructures within the European Strat- increased and strengthened considerably. been active since 2004, one focusing on egy Forum on Research Infrastructures. Furthermore, smaller-scale facilities have the study of strongly interacting hadronic The evaluation report of ERINS been motivated to improve their standards matter (Hadron Physics) and the other emphasized that the proposal builds on the in order to comply with EU regulations to focusing on the study of Nuclear Struc- rich experience and successes of the pre- obtain funds for transnational access. ture, Nuclear Astrophysics, and Applica- vious IAs and it recognized the scientific This very important goal for our tions of Nuclear Science. The latest IA value of the research. However, the avail- community has to be realized when concerning Hadron Physics research is able European Union (EU) budget for this the next opportunity arises and thus the STRONG-2020, which was approved call could cover only the projects at the striving (as a common effort!) toward in late 2018 and will be active from 1 very top of the ranking list, and unfortu- achieving this goal has to continue in June 2020 to 31 May 2023, while for nately ERINS was not placed there. the near future. We are counting on the Nuclear Structure, Nuclear Astrophysics, We think that it is important to inform community to join us with the greatest and Applications of Nuclear Science the the community about the efforts made enthusiasm in pursuing this goal! ongoing IA is ENSAR2, expected to end to improve our facilities and their access in 2020. In March 2019, following a tar- for the users, not only when the news is geted call by the EC and considering that very positive, but also when we are faced ENSAR2 was approaching the end of its with setbacks, in order to learn some- funding period, a new proposal, denoted thing from these and to find ways to be as ERINS (European Research Infrastruc- ready for future actions. This is the motive tures for Nuclear Science: Nuclear Struc- behind this editorial. ture, Astrophysics and Applications), was We are convinced that the efforts put Angela Bracco submitted as the successor to ENSAR2. into writing this proposal could be partly University of Milan The ERINS project was constructed hav- used for the preparation of a future proj- ing as a guiding line the fulfillment of ect. Furthermore, we are certain that many what was reported in the call. The activi- useful discussions made together with ties were defined in the best possible way several members of the community on via a bottom-up approach, and decided on how to plan and conduct improvements to after consultation and several ad hoc meet- the performances of the facilities and on ings involving the community at large. how to attract new users are not wasted; ERINS aims at further integrating the key rather, on the contrary, they will form the Muhsin Harakeh nuclear physics research infrastructures basis for future discussions and actions. KVI-CART Groningen

The views expressed here do not represent the views and policies of NuPECC except where explicitly identified.

Vol. 30, No. 1, 2020, Nuclear Physics News 3 laboratory portrait

JINR at the Forefront of Nuclear Research

The Joint Institute for Nuclear Re- •• Radio- and Astrobiology Looking for the limits of the exis- search (JINR) is an international inter- •• Information Technologies and tence of nuclear matter by focusing governmental research organization, a High-Performance Computing on the boundaries of the island of world famous scientific center that is a stability, the SHE Factory is based on unique example of integration of fun- Nuclear Physics the DC-280 heavy-ion cyclotron, the damental theoretical and experimental Since its foundation and up to world’s top accelerator among others study with the development and appli- now, the main direction of scientific of the same type. Substantial increase cation of cutting-edge technology and research of the Flerov Laboratory of (more than a factor of 10) in the ef- university education. Nuclear Reactions (FLNR) of JINR ficiency of experiments is needed JINR has a unique status as one of has been and still is the worldwide for the synthesis of the heaviest ele- the few major international organiza- recognized synthesis of new elements ments, 119 and 120, and for the study tions where basic research has been of Mendeleev’s Periodic Table and the of nuclear and chemical properties of successfully and effectively carried study of their properties, via nuclear already known elements. On the de- out at the world’s top level in an un- spectroscopy (α-, β-, γ-spectroscopy) tection side, the new gas-filled recoil precedented wide range of important and chemical analysis. separator (DGFRS-II) will play an scientific directions. Over six decades, The main areas of nuclear research important role. The construction of a great expertise and knowledge has at FLNR are and will be the following: a specialized building complex com- been accumulated in the seven labora- prising radiochemical laboratories of •• synthesis of heavy and super- tories of JINR. Class 1 for the manufacture and re- heavy elements (SHE) and the Most of the research is being pur- generation of highly radioactive tar- study of their properties; sued in experiments at the JINR site; gets is foreseen, completing the SHE •• study of the properties of light other research requires participa- Factory. exotic nuclei near the borders of tion in international collaborations FLNR’s research program has nucleon stability; and off-site. The JINR strategy is based been expanded into the region of •• study of nuclear reaction mecha- on a balance between home and in- neutron-rich isotopes of SHE near nisms leading to the formation ternational experiments. Both must the island of stability, since the of heavy elements and SHE and be scientifically solid, well defined, neutron shell N = 184 should have the analysis of reactions with ra- and expanding new frontiers in the a stabilizing effect on the nuclear dioactive nuclei. understanding of physical laws that lifetime. In addition, the hypotheti- govern the Universe. JINR has cho- The development of the FLNR ex- cal closed shell at Z = 114 should sen to work in several important perimental infrastructure foresees the also be of maximum support for the fields of science at the forefront of construction of three main accelerator synthesis of nuclei with the number all of these selected fields. The fol- complexes equipped with modern ex- of neutrons close to 184. FLNR pro- lowing is the list of research topics perimental set-ups meeting the goals poses to reach the neutron excess, pursued at JINR today and planned of the FLNR research program. Each not by using beams of neutron-rich for the future: of the accelerator complexes focuses radioactive nuclei, because of their on the following physics tasks: low intensity, but rather by using •• Nuclear Physics more neutron-rich target nuclei (e.g., •• Particle and High-Energy Phys- •• SHE Factory based on the 251Cf). In target production, the in- ics DC280 accelerator: synthesis ternational collaboration is of great •• Neutrino Physics of heavy and superheavy nuclei importance and will be pursued •• Relativistic Heavy-Ion and and the study of their properties: further. SPIN Physics •• U400M accelerator complex: Multi-nucleon transfer reactions •• Condensed Matter and Neutron study of light exotic nuclei; and in near-barrier collisions of actinides Nuclear Physics •• U400R accelerator complex: are promising in synthesizing new •• Theoretical Physics study of nuclear reactions. neutron-rich isotopes of SHE. These

4 Nuclear Physics News, Vol. 30, No. 1, 2020 laboratory portrait

reactions can lead to the formation two-proton radioactivity, the search •• Accelerator science and tech- of neutron-rich superheavy nuclei, for new magic numbers, and spec- nologies. inaccessible via fusion reactions. troscopy of exotic nuclei reactions This method allows the synthesis of a with halo nuclei. Many, if not all, of these directions number of new isotopes of light SHE, are interwoven and interconnected. up to the beta-stability line. Unfortu- There is a strong synergy between nately, no universal detector concept Particle Physics at the Large these branches of research, as well as exits; however, FLNR is looking into Hadron Collider (LHC) and between the expertise of the different upgrades and modifications of exist- Beyond laboratories of JINR. ing detectors like ACCULINNA-2, JINR is deeply involved in inter- SHELS, DGFRS-1, 2MAVR, GALS, national science of particle physics, Accelerator-Based Research and and CORSET. has made important hardware con- Accelerator Technologies Another ambitious scientific goal tributions to scientific and technical JINR, a more than 25-year, long- is measuring the masses of SHE and infrastructures inside and outside of standing member of both the ATLAS this laboratory is planning for a spe- JINR, and has been strongly involved and CMS collaborations, is one of the cial mass detection system, consisting in the harvesting of scientific results major participants, with great invest- right after the target of a pre-separa- through participation in data analysis. ments into these projects. The major tor, followed by a cryogenic gas ion The JINR particle physics program discovery of both experiments was catcher and a time-of-flight mass- intends to stay well integrated in the the observation of the Higgs boson spectrometer. European and worldwide particle production and its decay. The FLNR JINR experimental pro- physics strategies and hopes to play gram for 2024–2030 is aimed at study- an important role. Neutrino Physics ing the properties of the radioactive The main directions of particle Neutrino physics plays a key role decay and the structure of isotopes physics research activities are related in understanding of the laws gov- of heavy elements and SHE using to: erning the Universe. Nowadays, the the new DC-280 accelerator, the DG- significance of neutrino physics is FRS-3 setup, and the detecting system •• Precision exploration of strongly steadily increasing since it has entered GABRIELA. interacting states, including pro- its precision era. Radioactive ion beam facilities al- ton structure; quantum chromo- JINR, due to the explorations led low the study of exotic nuclear sys- dynamics (QCD) phases, like by B. Pontecorvo since the 1950s, de- tems remote from the beta-stability quark-gluon plasma; and new veloped a strong and influential neu- line. At low energies, the FLNR is hadronic states, including exotic trino school, with about 100 research- pursuing an experimental program states. ers currently working in this field. on relatively light exotic nuclear •• Electro-weak and flavor phys- JINR leads the world’s largest Neu- systems at the fragment-separators ics. trino Program, covering all sources of ACCULINNA-1 and COMBAS, •• Further insights into understand- neutrinos, strong theoretical investiga- installed on the primary beam-line ing of the Universe’s evolution tions, and data analysis.Together with of the U400M cyclotron. Recently, by astrophysical and cosmo- INR (Moscow), JINR plays a leading the new generation separators, AC- logical observations and by de- role in the construction, data taking, CULINNA-2 and MAVR, were put veloping new instruments, like reconstruction, calibration, and data into operation. ACCULINNA-2 is a gravitational waves, multi-mes- analysis of the Baikal Gigaton Volume fragment-separator, installed at the senger astronomy, and searches Detector (GVD) with an aim to build a U400M cyclotron to produce sec- for dark matter and dark sectors 0.4 km3 detector by 2021 and 1.5 km3 ondary beams of radioactive exotic at colliders and non-accelerator detector by 2027. JINR invests about nuclei in the “in-flight” mode. This experiments. 5 million USD per year to accomplish allows studies of nuclear haloes, •• Experimental and theoretical de- these goals. In 2019, Baikal GVD neutron skins, cluster states, exotic termination of a model, beyond was the largest neutrino telescope in multi-neutron decays (2-nucleon vir- the Standard Model (SM), free the northern hemisphere with its one- tual states, 2n- and 4n-radioactivity), from the SM shortages. fourth km3 detector.

Vol. 30, No. 1, 2020, Nuclear Physics News 5 laboratory portrait

JINR intends to strengthen further Important to note is that JINR has its leading position by increasing sub- already made the first step toward this stantially efforts in the data analysis direction, having installed its brand for yielding the highest-quality sci- new laser inclinometer at the VIRGO entific results in observation of ultra- detector. In the mid-term, JINR will de- high astrophysical neutrinos and re- velop the presently missing needed ex- lated studies. pertise and prepare itself for competent The major motivation of JUNO, collaboration at existing gravitational the reactor antineutrino experiment, wave detectors like LIGO or VIRGO, is the determination of neutrino and/or the third-generation detector mass ordering at 3–4 standard de- Einstein. Figure 1. Schematic view of the SHE viations confidence level. JINR is a Factory. major JUNO collaborator with well- visible financial and intellectual NICA Relativistic Heavy Ion gion of maximal net baryon density contributions. Physics at the time of “freezing.” In this re- From the beginning of relativis- gime, the system takes a maximum tic heavy ion research in the early amount of space-time in the form of Multi-Messenger Astronomy 1970s, JINR has been an important a mixed phase of quark-hadron mat- Including Gravitational Wave player with its on-site program at ter where hadron and quark-gluon Detection the Synchrophasotron, and then Nu- phases coexist. It is understood nowadays that clotron, and its participation in the The accelerator complex is com- phenomena that occurred in the Uni- heavy ion program at CERN-SPS posed of the upgraded superconduct- verse should be studied by simulta- first in WA98, and NA49, then in ing synchrotron Nuclotron, including neous observations of different sig- ALICE. extraction and transport beam-lines; nals. These multi-messengers could These activities have been the mo- the injection complex (new heavy ion give a further insight into the evolu- tivation and source for the Mega-Sci- source, source for polarized particles tion of the Universe. ence project NICA. and linear accelerator injectors); the Baikal GVD, mentioned above, The aim of the NICA project is to new superconducting synchrotron is one of the cornerstones of this ap- create a world-class experimental base booster; and the collider, consisting proach. The TAIGA installation—a set for conducting fundamental research of two superconducting storage rings of gamma and muon telescopes hosted in contemporary high-energy phys- (ca. 500 m in circumference each) in Siberia, in Tunka Valley, to the ics, as well as applied research in mi- with two interaction points where south of Lake Baikal, can be regarded croelectronics, medicine, and biology collisions of heavy ions and polar- as a supplemental instrument in terms making use of accelerator and beam ized particles can be studied (see Fig- of multi-messenger astronomy. To- technologies. ure 3). The NICA collider will enter gether, Baikal GVD and TAIGA can The main goals comprise inves- the commissioning phase by the end provide a unique multi-messenger ob- tigation of hot and dense strongly of 2022. servation of the Universe integrated interacting matter, the search for a Both detectors, BM@N and MPD, into the global network. This direction mixed phase and critical point in have seen the formation of their re- of research is of great importance and the QCD phase diagram (see Figure spective international experiment col- will be seriously reconsidered by the 1) in the poorly explored region of laborations. JINR management for strengthening high baryon chemical potential, and its gamma-rays counterpart. TAIGA is to clarify the basis of QCD in the NICA Spin Physics an international collaboration, achiev- non-perturbative regime and other Spin physics was also a key pro- ing the world-level quality standards theoretical approaches for the de- gram at the Synchrophasotron and in technologies, commissioning, soft- scription of strongly interacting mat- has been expanded at the Nuclotron. ware, and data analysis. JINR will ter. The NICA energy range (√sNN Still, as of today, studying the gluon take all necessary measures to attract = 2–11 GeV/A for heavy ion colli- structure of the nucleon is of funda- world-class experts for leading this sions) is believed to be particularly mental importance, as it is needed project. interesting because it covers the re- to understand the nucleon internal

6 Nuclear Physics News, Vol. 30, No. 1, 2020 laboratory portrait

structure as a whole. The unpolar- tests of the quark-parton model of ized gluon content of the proton is nucleons at the QCD twist-two level well known, while our knowledge with minimal systematic errors phys- of polarized parton distributions is ics goals and allow for possible further limited. reconfiguration and upgrade of the fa- Polarized proton and deuteron cility: beams will be made available at NICA and experiments with them will be •• close to 4π geometrical accep- possible at the second interacting tance, point of the collider. The luminosity is •• high-precision (~50 µm) and expected to be in the range of 1,030– fast vertex detector, 1,032 cm2 s-1.: The opportunity to •• high-precision (~100 µm) and have such high-luminosity collisions fast tracking system, of polarized protons and deuterons at •• good particle ID capabilities, the NICA collider allows for studies •• efficient muon range system, of a great variety of spin- and polar- •• good electromagnetic calorimeter, ization-dependent effects in the had- •• low material budget over the ron–hadron collisions. This will allow track paths, and measurements of asymmetries of the •• trigger and DAQ system ade- “Drell-Yan pair production” (DY) in quate for event rates at luminos- collisions of non-polarized, longitudi- ity of 1,032 cm2 s-1. nally and transversally polarized protons and deuterons that provide access JINR Participation in the Forefront to all leading twist collinear and TMD of External Experiments Off-Site PDFs of quarks and anti-quarks in Furthermore, of strategic importance nucleons. The measurements of asym- is JINR’s participation in forefront ex- metries in production of J/Ψ and direct ternal experiments off-site, like, for ex- photons will be performed simultane- ample, at existing facilities, like at LHC, ously with DY using dedicated trig- SPS, RHIC, and STAR, and at facilities Figure 2. High-energy neutrino tele- gers. The set of these measurements under construction, like, for example, scope Baikal GVD. will supply complete information for the international FAIR-facility in Ger-

Figure 3. NICA complex. Figure 4. Pulsed reactor IBR-2.

Vol. 30, No. 1, 2020, Nuclear Physics News 7 laboratory portrait

many, or in planning, the proposed elec- Further increase in the intensity of of fundamental interactions, nuclear tron-ion collider facility in the United UCN sources will allow both improv- theory, condensed matter physics, and States. The JINR strategy for coopera- ing the accuracy of such experiments modern mathematical physics. Stud- tive research at other accelerator centers and significantly expanding the scope ies at BLTP are carried out in close is linked closely to the discovery poten- of UCN usage (e.g., for studies of sur- cooperation with scientists from many tial of the experiment and of the value to faces and thin films). world-leading research centers and in JINR, and also to the updated European Frank Laboratory has proposed to coordination with the JINR experi- Strategy for Particle Physics, expected build a new advanced neutron source, mental program. to be available in 2020. (Dubna Neutron Source fourth gen- Scientific and organizational policy eration (DNS-IV) on site. In combina- of the laboratory relies on multidisci- Neutron Research in Condensed tion with modern moderators, neutron plinary theoretical physics on the ba- Matter and Neutron Physics guides and neutron scattering instru- sis of advanced mathematics, support JINR has a long tradition in con- ments, DNS-IV promises to become of the JINR experimental program, densed matter and neutron physics one of the best neutron sources in the and strengthening of the scientific research employing neutrons from world, opening unprecedented possi- brainpower through the interplay of their on-site research reactors. JINR bilities for scientists from JINR mem- research and education. intends to stay at the forefront of this ber states and worldwide for research BLTP and JINR are attractive to science by building the best neutrons in condensed matter physics, funda- the international scientific community source possible. mental physics, chemistry, and mate- by organizing series of topical work- Neutrons are used for studying fun- rial and life science. shops, conferences, and schools for damental symmetries and interactions, DNS-IV will provide shorter neu- young scientists. A special emphasis is structure, and properties of nuclei, but tron pulses, while containing the same placed on active participation of BLTP nowadays neutrons are mostly re- number of neutrons as at European in educational programs of JINR as quired in investigations of condensed Spallation Source (ESS), to be oper- well as on its direct cooperation with matter, including solid states, liquids, ational in 2024. Indeed, it will be as universities of the JINR member biological systems, polymers, col- good as ESS for low-resolution exper- states. The unique feature of “Dubna loids, chemical reactions, engineer- iments and significantly outperform it International School of Theoretical ing systems, and so on. The use of for high-resolution experiments. Physics (DIAS-TH)” is its coher- cold neutrons (wavelengths from 4Å From the different concepts stud- ent integration into the scientific life to 20Å) in neutron scattering research ied, a pulsed neutron reactor, IBR-3, of BLTP and JINR, ensuring regular allows for studies of nanoscale ob- with Np-237 core was chosen for the and natural participation of the lead- jects and has become the current trend DNS-IV project. Therefore, the pulsed ing scientists in education and training worldwide, particularly in studies of neutron reactor IBR-3 with NpN fuel activities. nano-structured objects required by currently became the working project Implementation of the outlined medicine and biology. At the same with a planned start of the DNS-IV research program in theoretical phys- time, using very cold neutrons (VCN) operation in 2036–2037. ics, first of all related to Lattice QCD with wavelengths from 20Å to 100Å and, in general, the theory of dense one can approach new levels of mea- Theoretical Physics and hot Hadronic Matter, multi-loop surement accuracy in several tech- Throughout JINR’s history, re- calculations in the Standard Model, niques (e.g., neutron spin-echo and research in theoretical physics has al- and astrophysical and cosmological flectometry). Moreover, VCN are also ways been one of the pillars of the modeling, will necessarily boost de- a very promising tool for research in JINR scientific program that has con- velopment of the high-performance the field of particle physics and stud- tributed to many major advances in computing infrastructure of JINR to ies of fundamental interactions (e.g., science. The Bogoliubov Laboratory the highest level. measurements of the neutron lifetime, of Theoretical Physics (BLTP) is one the search for neutron–antineutron os- of the biggest research centers in the Radiobiological and Astrobiological cillations). Ultracold neutrons (UCN) world, specializing in theoretical re- Research at Charged Particle are the well-established experimental search at the frontiers of fundamental Beams tool for research in the field of particle physics. BLTP has expertise in a wide Heavy charged particles are an ex- physics and fundamental interactions. range of areas related to the theory cellent tool to address fundamental

8 Nuclear Physics News, Vol. 30, No. 1, 2020 laboratory portrait

problems of modern radiation biology cal Problems. Worldwide unique ex- precision down to micron level), as and genetics. In contrast to photon periments on primates for the estima- exists at GSI Darmstadt. radiation, which uniformly deposits tion of radiation risks of CNS disorders The LRB is a strong new member energy within the cell nucleus, heavy and carcinogenesis are in progress at of the recently formed International charged particles densely release en- the LRB. Biophysics Collaboration. It collabo- ergy along their tracks, which results A new method of the enhancement rates with many scientific institutions in complex and clustered DNA dam- of low-LET ionizing radiation’s bio- of JINR members and other countries. age and determines the particles’ logical effectiveness by the transfor- high biological efficiency. In space, mation of nonlethal DNA damage to Information Technology high-charge and energy ions of the lethal has been invented and recently The mission of the Laboratory of Galactic Cosmic Rays (GCR) make patented by the LRB. The method has Information Technology (LIT), is two- a great contribution to the health risk been tested in vivo and in vitro, which fold: to astronauts during manned deep makes it very promising for radiation space missions. Furthermore, hadron medicine. 1. To serve the scientists of JINR beams—protons and carbon ions—are The LRB develops the hierarchy and its member states in the pur- beneficial for radiation cancer -treat of mathematical models to simulate suit of their research projects by ment, especially for deep-seated tu- radiation-induced pathologies at differ- developing “Methods, Algo- mors, due to their depth-dose distribu- ent organization levels and time scales. rithms and Software for Model- tion with a sharp maximum at the end In addition to the traditional Monte ling Physical Systems, Mathe- of the particle range (the Bragg peak). Carlo technique, the LRB’s approach matical Processing and Analysis Charged particle tumor therapy and involves computational methods from of Experimental Data.” space radiation protection are becom- different knowledge areas (molecular 2. To assure that the information ing increasingly urgent fields of mod- dynamics and simulation of brain neu- technology (IT) infrastructure ern radiobiological studies. ral networks). The computation of ra- and IT know-how of JINR ex- Astrobiology is studying life in diation damage to the CNS structures perts is always state of the art. the broadest sense: its origin, evolu- was initiated and is continued by Na- tion, and presence in the Universe. To tional Aeronautics and Space Adminis- Presently, the JINR Infrastructure answer the question of the exogenous tration and the LRB. has been developed in close connec- origin of life, the early stages of transi- For the first time, the synthesis tion with CERN and other Institutes tion “from the inanimate to life” can be of prebiotic compounds in the “for- of Nuclear and High Energy Physics. reproduced in ground experiments us- mamide + catalysts” system under During the last 15 years, a distributed ing particle beams as an energy source. exposure to particle beams has been computing infrastructure has been The great advantage of conducting performed in collaboration with Ital- created for processing and storing research at the Laboratory for Radio- ian universities within the framework data from LHC experiments. Each of Biology (LRB) is the availability of of research on the Panspermia hy- the four outstanding scientific experi- numerous radiation sources, including pothesis. mental facilities (ATLAS, CMS, AL- heavy ion beams of different energies. The key to the successful fulfilment ICE, and LHCb at the LHC) are being JINR’s basic facilities offer an excel- of the 2030 Program is the possibility run by collaborations, each of which lent opportunity of modeling the bio- to conduct radiobiological research at has several thousand scientists from logical action of space radiation. The the Nuclotron (VBLHEP). For that, a several hundred institutes distributed LRB has proposed a novel Nuclotron- special irradiation station with large worldwide. based technique of modeling of radia- area illumination is requested for irra- It should be noted that the JINR tion fields with continuous particle en- diation of material, inorganic and or- research program for the next decades ergy spectra generated by GCR inside ganic, as well as rodents and primates. is aimed at conducting ambiguous and spacecraft in deep space. When, in the future, highly localized large-scale experiments on the Insti- Another major advantage is an ex- irradiation with submillimeter reso- tute basic facilities and in the frames cellent opportunity to perform large- lution is envisioned, as, for example, of worldwide cooperation. This pro- scale in vivo animal exposures in col- needed for cell size irradiation, the gram is connected with the imple- laboration with leading experts in this beam-line design could follow the mentation of the NICA megaproject, field—with RAS Institute of Biomedi- outlines of micro-beams (i.e., high the construction of new experimental

Vol. 30, No. 1, 2020, Nuclear Physics News 9 laboratory portrait

facilities, the JINR neutrino program, Such a program will rely on on-site Conclusion the modernization of the LHC experi- educational and training programs but JINR sees a vigorous determina- mental facilities (CMS, ATLAS, AL- depend also on the strong interaction tion of this Institute to stay at the fore- ICE), and the programs on condensed with universities and training centers in front of science in the chosen fields of matter physics and nuclear physics. the JINR member states. Only in close basic research. For that, several new The implementation of the projects collaboration with these institutions facilities are proposed or under con- mentioned above requires adequate and with a sustainable development struction, such as the and commensurable investments in of JINR can a successful realization the systems providing the processing of the projects described above can be •• SHE Factory, and storage of increasing data vol- guaranteed. The creation of a higher •• the NICA facility with its fixed umes. engineering school in Dubna based on target program and the collider The JINR computing infrastructure the Dubna State University is of great mode for Heavy Ion collisions, consists of numerous computing com- importance. •• the NICA facility for spin phys- ponents and IT technologies to solve Proven and or new methods of ics with polarized beams, JINR tasks, from theoretical studies to training and recruiting of personnel •• the new Pulsed Neutron source experimental data processing, storage, include: based on a high-intensity pulsed and analysis. The JINR LIT Multi- neutron reactor IBR-3 with Np- functional Information and Comput- •• supervision of practical, bache- 237 core, ing Complex is the key element of lor’s, master’s, and Ph.D. works •• irradiation facilities for mate- this infrastructure and plays a defining prepared by students who stud- rial and biophysics and radiation role in research, which requires mod- ied at scientific and technical biological experiments, ern computing power and data storage departments of universities from •• the new Rare Isotope Facility systems. They are the IT ecosystem the JINR member states, DERICA, for the NICA project (BM@N, MPD, •• excursions to the facilities and •• Biomedical Research Centre for SPD), Tier-1 of the CMS experiment lectures about activities of each of Proton Therapy, and at JINR, Tier-2/CICC providing sup- the JINR laboratories for students, •• continuous expansion of the port to experiments at the LHC (AT- •• planning various supplement GOVORUN Supercomputer LAS, ALICE, CMS), FAIR (CBM, schools for students of local uni- and creation of a dynamically PANDA), and other large-scale ex- versities during scientific con- growing IT platform that re- periments as well as support to users ferences organized by JINR, and sponds to the rapidly develop- of JINR Laboratories and the JINR •• investing in the development ing IT world. member states (MPD/NICA, BESIII, of human capital and training LRB, FLNR, DLNP, BLTP, LNP); the of employees in world-leading Furthermore, the Institute takes all integrated cloud environment of the educational centers. measures to strengthen its expertise in JINR member states for support of micro-electronics, ASIC-chip design, JINR users and experiments (NICA, Moreover, JINR runs a strong, inno- in detector design, and accelerator ALICE, BESIII, NOvA, Daya Bay, vative, and bright outreach program technologies. Large efforts are un- JUNO, etc.); and the HybriLIT plat- meeting the world-class standards of dertaken for educational and training form with the GOVORUN supercom- this new field of communication. The programs. puter as a major resource for high-per- outreach service that provides accurate formance hybrid computing. and appealing information to a wide audience is understood nowadays to be Human Resources: Education and inevitable. Training Programs Furthermore, for the numerous in- The necessity of a well-defined edu- ternational projects of JINR and their cational program at JINR is evident and national and international collabora- must be continuously adapted to guar- tors special efforts will be taken to antee new highly trained generations of constantly improve a user-friendly en- Boris Sharkov researchers, engineers, and technicians. vironment on site at JINR. JINR Dubna

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Novel Excitation Modes in Nuclei: Experimental and Theoretical Investigation on Multiple Chiral Doublets Q. B. Chen1 and J. Meng2,3 1Physik-Department, Technische Universität München, D-85747 Garching, Germany 2State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, China 3Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502, Japan

Nuclear Chirality and Its Signal Differing from the case of nuclear vibration and rota- As a microscopic quantal many-body system, the struction, the chiral rotation was predicted in the Particle Rotor ture of atomic nucleus is understood by measuring and in- Model (PRM) with proton and neutron moving in high-j terpreting its responses to all kinds of probes. The responses shells coupled to a triaxial rotor as well as in the Tilted manifest in different kinds of energy excitation spectra with Axis Cranking (TAC) approximation to this model system specific energy and angular momentum (spin), and link [3]. After the predication, lots of efforts have been made with electric and magnetic transition rates. to search for the chiral rotation and impressive progresses From the nuclear low-lying spectra, Aage Bohr, Ben have been achieved. So far, more than 60 candidates of chi- Mottelson, and James Rainwater discovered the connec- ral doublet bands have been observed in the mass regions tion between collective motion and particle motion in the A~80, 100, 130, and 190 [4]. As the chiral rotation exists atomic nucleus and, based on this connection, developed only in the triaxial nuclei, the observation of chiral dou- the theory for the structure of the atomic nucleus that was blet bands provides a unique fingerprint for nuclear triaxial in close agreement with experiments [1, 2]. The harmonic shape. vibrational spectrum, with the excitation energy levels equivalently spaced, is the characteristic of a nucleus exhibiting small oscillations about a spherical equilibrium. The Multiple Chiral Doublets (MχD) rotational spectrum, with the excitation energy levels of the The pioneering work in Ref. [3] predicted the existence rigid rotor form, is the characteristic of a nucleus exhibiting of the chiral rotation and its necessary conditions, includ- axially deformed shape deviating from spherical shape. Ac- ing the nuclear triaxial deformation as well as the valence cordingly, the excitation energy levels equivalently spaced proton(s) and neutron(s) in high-j orbits. The open ques- serve as a hint for nucleus with a spherical shape, while tions include which nucleus satisfies these conditions and the excitation energy levels behaving like a rigid rotor de- at what energy the chiral rotation appears. note that the nucleus shape deviates from spherical one, as In order to predict the chiral nucleus (i.e., the nucleus shown schematically in Figures 1a and b. hosting the chiral doublet bands), one has to search for the In Figure 1c, a pair of nearly degenerate ΔI = 1 bands triaxially deformed nucleus. Microscopic approaches with with the same parity are presented. They are suggested as predictive power are demanded. chiral doublet bands in 1997 [3] due to the so-called chiral The covariant density functional theory (CDFT) pro- rotation. The chiral rotation is a novel rotational excitation vides excellent descriptions of ground states and excited mode and it demonstrates that chiral symmetry exists in the states for nuclei all over the periodic table with a high pre- atomic nuclei. In nuclear chiral rotation, the total angular dictive power [5]. Using a universal density functional, momentum has three mutually perpendicular components, CDFT provides confidences in searching for chiral nucleus. respectively contributed by valence proton(s), neutron(s), In 2006, the adiabatic and configuration-fixed con- and a collective core, as shown schematically in Figure 1c. strained triaxial CDFT was developed to search for chiral The three mutually perpendicular components can form ei- nucleus, including the existences of the triaxial shape as ther left- or right-handed states with near degenerate ener- well as the high-j proton and neutron configurations [6]. gies. These states can form the chiral doublet bands with A new phenomenon, multiple chiral doublets (MχD) (i.e., spin in the laboratory framework, which is the experimental more than one pair of chiral doublet bands in one single signal for nuclear chiral symmetry. nucleus), was suggested for 106Rh based on the triaxial

Vol. 30, No. 1, 2020, Nuclear Physics News 11 feature article

Figure 2. Energy surfaces (a) and deformation parameters Figure 1. Schematic illustration of excitation modes in (b) as functions of deformation parameter β in adiabatic atomic nucleus. (open circles) and configuration-fixed (solid lines) constrained triaxial CDFT calculations for 106Rh. The minima deformations and their corresponding proton and neutron in the energy surfaces are represented as stars and labeled configurations (Figure 2). A–G with their corresponding deformations β and γ (a) and In Figure 1d, MχD (i.e., more than one pair of chiral energies (b). Reprinted figure with permission from [6], doublet bands in one single nucleus) are shown schemati- Copyright (2006) the American Physical Society. cally. As shown in Figure 2, MχD suggests the coexistence of the triaxial shapes in atomic nucleus and the persistence of the chiral rotation against shape vibrations and valence nucleons excitations.

Experimental Evidence for MχD After the prediction of MχD [6], lots of efforts were made to search for the corresponding existence (i.e., search for the nuclei that possess more than one pair of chiral doublet bands). Two distinct sets of chiral-partner bands have been identified in the nucleus 133Ce [7]. They constitute a MχD, a phenomenon predicted by CDFT calculations and observed experimentally for the first time. The properties of these chiral bands are in good agreement with the calculated results based on a combination of the constrained triaxial CDFT theory and the PRM. In Figure 3, the experimental energy spectra E(I), staggering parameters S(I) = [E(I)-E(I-1)]/2I, and B(M1)/B(E2) ratios for the negative-parity bands 5 and 6 as well as the positive-parity bands 2 and 3 in 133Ce are in comparison with the theoretical results by the PRM. Bands 5 and 6 are built on π( Figure 3. Experimental and theoretical excitation energies, 2 −1 1h11/2) ⊗ν(1h11/2) configuration (i.e., two valence protons staggering parameters S(I), and B(M1)/B(E2) ratios for the in orbital h11/2 and one valence neutron hole in orbital h11/2). negative-parity chiral doublet (left panels) and positive-parity 1 −1 −1 133 Bands 2 and 3 are built on π(1h11/2) (1g7/2) ⊗ν(1h11/2) chiral doublet (right panels) in Ce. Taken Reprinted figure (i.e., one valence proton in orbital h11/2, one valence proton with permission from [7], Copyright (2013) the American hole in orbital g7/2, and one valence neutron hole in orbital Physical Society. h11/2). Both configurations are of triaxiality according to CDFT calculations. The standard features of chiral rotation of valence proton(s), neutron(s), and collective core, as are evident: (1) small energy differences between the dou- well as their interplays correctly, and illustrates the three- blet bands; (2) smooth staggering parameters S(I); (3) similar dimensional dynamical picture of the total nuclear system. B(M1)/B(E2) values of the doublet bands. Therefore, the evidence for more than one set of chiral The PRM results show impressive agreements with doublet bands in a single nucleus (i.e., MχD), was identi- the observations, indicating that PRM treats the motions fied in 133Ce.

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The experimental identification of MχD demonstrates that the nucleus not only has non-axisymmetric shape but also has non-axisymmetric shapes coexistence. Such shapes coexistence is not restricted to 133Ce. Very recently, the MχD phenomena were further reported in the even–even nucleus 136Nd [8], where five pairs of nearly degenerate rotational bands were observed, which was a record in the study of nuclear chirality.

MχD with the Same Configuration: 103Rh The aforementioned MχD examples are built on distinct particle-hole configurations with different triaxial deformation parameters. Three sets of chiral doublet band structures have been identified in the 103Rh nucleus [9]. The properties of the observed chiral doublet bands are in good agreement with theoretical results obtained using constrained CDFT and PRM calculations. Two of them belong to an identical configuration and provide the first experimental evidence for a novel type of MχD, where “excited” chiral doublet bands exist on top of the “yrast” chiral doublet bands. This observation shows that the chiral geometry in nuclei can be robust against the increase of the intrinsic excitation energy.

MχD with Octupole Correlations: 78Br Two pairs of positive- and negative-parity doublet bands together with eight strong electric dipole transitions linking their yrast positive- and negative-parity bands have 1 78 78 positive-parity bands 1 and 2 are built on π(1g9/2) ⊗ν been identified in Br [10]. The level scheme of Br is −1 (1g9/2) , while the negative-parity bands 3 and 4 are built shown in Figure 4, with five bands labeled as 1–5. The 1 −1 on π(1f5/2,2p3/2) ⊗ν(1g9/2) . They were identified as chiral doublet bands, respectively, based on the analysis of their energy differences, staggering parameters S(I), as well as B(M1)/B(E2) ratios. A more striking feature of the level scheme is the observation of eight E1 linking transitions between bands 1 and 3. The observation of the E1 transitions implies the existence of the octupole correlations between the doublet bands. The octupole correlations originate from the 1 interactions between the proton configurations π(1g9/2) 1 and π(2p3/2) as their angular momentum differences are Δj = Δl = 3ℏ. All of these interpretations were supported by the constrained CDFT and PRM calculations. This observation indicates that nuclear chirality can be robust against the octupole correlations. It also sheds light Figure 4. Level scheme of 78Br. The inset shows an expan on searching for the chirality-parity quartet bands in nu- ded view of the lower part of the level scheme. Reprinted cleus with both stable triaxial and octupole deformations, in figure with permission from [10], Copyright (2016) the which the chiral symmetry and spatial reflection symmetry American Physical Society. are broken simultaneously.

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Azimuthal Plot The nuclear chiral rotation results from the dynamic (the angular momentum) properties of the nucleus. Dif- fering from the rigid rotor, in which the rotation is along with the principal axis that is perpendicular to the axis of symmetry [cf. Figure 1(b)], chiral rotation is a three- dimensional quantum rotational mode. Its total angular momentum has three significant mutually perpendicular components along the short, intermediate, and long principal axes of the nucleus, respectively, as shown schematically in Figure 1c. Therefore, it is essential to examine the angular momentum geometry in the chiral doublet bands. In quantum mechanics, the wave function contains Figure 5. Azimuthal plots obtained by angular momentum information about the probability amplitude of posi- projection approach for the chiral doublet bands A and B tion, momentum, angular momentum, and other physi- in 128Cs at spin values I = 11, 14, and 18ℏ. Reprinted figure cal properties of the system. Therefore, in order to attain with permission from [11], Copyright (2017) the American a visualized and unambiguous picture in understanding Physical Society. the geometry of angular momentum, one has to know the density probability profiles for the orientation of the angular momentum in the intrinsic frame. This was first carried out in the framework of angular momentum projection, which restores the rotational symmetry sponta- neously broken in the mean-field approximation. Such a density probability profile is named an azimuthal plot [11], which provides the density probability distribution for angular momentum orientations. The azimuthal plots for the chiral doublet bands A and B in 128Cs are shown in Figure 5. Here, θ is the angle between the angular momentum and the long axis, whereas ϕ is the angle between the projection of the angular momentum Figure 6. Nuclides with chiral doublet bands (circles) on the intermediate-short plane and the intermediate axis. and MχD (pentagons) observed in the nuclear chart. The The (θ,ϕ)-values of maximal density probability represents squares represent stable nuclei. Reprinted from [4], with the most probable orientation of the angular momentum. permission from Elsevier. Therefore, these plots clearly show the evolution of chiral mode from a chiral vibration with respect to the long-short hottest topics in modern nuclear physics. Further efforts, plane (I =11ℏ), to a chiral rotation (I=14ℏ), and to another including developing state-of-the-art theory, searching chiral vibration with respect to the intermediate-short plane for new observable characterizing chirality, and per- (I =18ℏ). forming high-precision experimental measurements, are needed to further understand the chiral rotation in Summary and Perspective atomic nuclei. The study of nuclear chirality and MχD was very active in the past two decades. So far, 62 candidate Acknowledgments chiral doublet bands in 49 nuclei (including 6 nuclei The authors thank all collaborators who contributed to with MχD) have been observed in odd–odd nuclei as the investigations presented here and X. H. Wu for prepar- well as in odd-A and even–even nuclei, and these are ing Figure 1. Financial support for this work was provided spread over the mass regions A~80, 100, 130, and 190, in part by the National Key R&D Program of China (Con- as shown in Figure 6 [4]. tracts No. 2018YFA0404400 and No. 2017YFE0116700), Finally, we would like to emphasize that the inves- the Deutsche Forschungsgemeinschaft (DFG), and National tigation of nuclear chirality continues to be one of the Natural Science Foundation of China (NSFC) through funds

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provided to the Sino-German CRC 110 “Symmetries and the 4. B. W. Xiong and Y. Y. Wang, Atom. Data Nucl. Data Tables Emergence of Structure in QCD” (DFG Grant No. TRR110 125 (2019) 193. and NSFC Grants No. 11621131001, No. 11935003, and 5. J. Meng (Ed.), Relativistic density functional for nuclear No. 11975031.). structure, vol. 10 of International Review of Nuclear Phys- ics (World Scientific, Singapore, 2016). 6. J. Meng, J. Peng, S. Q. Zhang, and S.-G. Zhou, Phys. Rev. C References 73 (2006) 037303. 1. https://www.nobelprize.org/prizes/physics/1975/summary/ 7. A. D. Ayangeakaa et al., Phys. Rev. Lett. 110 (2013) 172504. (1975). 8. C. M. Petrache et al., Phys. Rev. C 97 (2018) 041304(R). 2. A. Bohr and B. R. Mottelson, Nuclear structure, vol. II 9. I. Kuti et al., Phys. Rev. Lett. 113 (2014) 032501 (Benjamin, New York, 1975). 10. C. Liu et al., Phys. Rev. Lett. 116 (2016) 112501. 3. S. Frauendorf and J. Meng, Nucl. Phys. A 617 (1997) 131. 11. F. Q. Chen et al., Phys. Rev. C 96 (2017) 051303(R).

Vol. 30, No. 1, 2020, Nuclear Physics News 15 impact and applications

Characterization of Radiation Effects and Ion Tracks with Spallation Neutron Probes

Swift heavy ions are typically de- removed by background subtraction fined as high-mass charged particles and direct information on the damage of kinetic energy above ~1 MeV per structure is lost. nucleon (MeV/u). In this regime, the Neutron total scattering has great energy deposition of the ions is domi- potential to overcome the shortcom- nated by electronic stopping, and each ings of conventional characterization individual ion may induce a linear trail techniques because the interaction of of damage with a width of a few nano- neutrons with atoms has no explicit Z- meters and a length of several tens of dependence. Total scattering provides micrometers or more [1]. During the last information on the long-range period- decade, ion tracks and other radiation ef- icity of an irradiated material (Bragg fects induced by swift heavy ions have scattering) and analysis of the diffuse been studied in a wide range of materi- scattering gives insight into the local als for basic research, as well as for a Figure 1. Transmission electron mi- defect structure of the cation as well wide variety of applications. The inter- croscopy image of the track structure as the anion sublattice through pair actions of swift heavy ions with matter in Gd2TiO5 irradiated with 2.2 GeV distribution function (PDF) analysis. are significantly different from those in- Au indicating two regions of an amor- The important advantage is thus that duced by lower energy ions (keV-MeV), phous track core and a disordered the damage structure can be compre- where atoms are directly displaced from hexagonal shell [2]. hensively characterized with the same their lattice sites via elastic collisions. In probe over a range of length scales contrast, swift ions (MeV-GeV) trans- approaches combine data from ther- and sensitivity to all atomic constitu- fer their kinetic energy to the electrons mal-spike calculations with molecular ents. Such experiments have not been of the target, inducing ionization and dynamics simulations to trace atomic available until recently due to the initiating a cascade of secondary elec- motion in the lattice system [3]. Key very small neutron scattering cross- trons that quickly spreads radially. The to benchmarking such modeling ef- sections and the associated unattain- extremely high energy densities (up forts are experimental data obtained by able large irradiated sample volumes. to tens of eV/atom) along the ion path a wide range of characterization tech- Neutron total scattering experiments lead to a confined plasma-like state that niques. Besides microscopy and spec- on ion irradiated materials became is dissipated through electron–phonon troscopy techniques, radiation damage possible by the combination of mod- coupling to the lattice. Subsequent rapid is frequently analyzed by diffraction ern spallation sources with a greatly transitions through equilibrium and methods using electrons and X-rays enhanced neutron flux and large ion- non-equilibrium states trigger complex [4]. A drawback of these probes is their accelerator facilities providing ions structural modifications within a highly predominant interaction with the elec- of ~ GeV energy. Swift heavy ions localized nanoscale damage zone, form- trons of a target material, with little with penetration depths on the order ing ion tracks in materials ion tracks sensitivity to low-Z elements (e.g., of 50–100 μm can produce about 50– (Figure 1) [2]. oxygen in UO2). Traditional diffrac- 100 mg of homogeneously irradiated One main unanswered question re- tion experiments rely on the long-range bulk material, which is the minimum garding the track-formation process structure of a material with no insight amount for the most intense neutron concerns the conversion of the elec- into short-range atomic arrangements. spallation source, with a typical neu- tronically deposited energy into a non- This is a disadvantage because radia- tron exposure time of one hour. equilibrium local defect structure. The tion damage often consists of uncorre- The Nanoscale-Ordered Materi- most widespread theoretical approach lated defects, disorder, and amorphous als Diffractometer (NOMAD) at the is the two-temperature model where domains that only produce diffuse scat- Spallation Neutron Source at Oak track formation is described by rapid tering. In diffraction patterns, informa- Ridge National Laboratory is one and localized lattice heating [1]. New tion from diffuse scattering is typically of the very few neutron beam-lines

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in the world dedicated to collecting a defect structure with no long-range sponds to the pair separation, and the high-quality neutron total scatter- coherence. A Fourier transformation area under the curve is related to the ing data [5]. With a neutron flux of of the total scattering structure func- coordination number. As shown for 8 2 ~1 × 10 neutrons/cm ·s and a large tion, S(Q) – 1, converts the reciprocal Er2Sn2O7, irradiation with swift heavy solid angle of detector coverage, NO- space to real space and results in the ions changes significantly the local MAD requires relatively little sample pair distribution function G(r) and to- atomic arrangement (Figure 2b). De- mass and counting time to produce tal correlation function T(r): pending on the chemical composition high-resolution PDFs. For com- and structural complexity of a sample, 2 Qmax monly used angle dispersive diffrac- Gr()= QS ()QQ−1sin,()rdQ several interatomic pairs can contrib- π ∫   tion, a range of momentum transfers Qmin ute to a maximum in a PDF. Neutron is reached by recording the scattered ((4πρ2 Gr()+ r) PDFs contain all atom–atom correla- intensity as a function of scattering Tr()= , tions including cation–cation, cation– r angle. In contrast, diffraction experi- anion, and anion–anion. Complemen- ments at NOMAD are energy dis- where Q is the scattering vector de- tary X-ray total scattering experiments persive, recording the intensity as a fined asQ = 4π/λ sin θ, and λ and θ are for PDF analysis can be performed at function of time-of-flight, which is the neutron wavelength and scattering synchrotron facilities to highlight the proportional to the wavelength of the angle, respectively. This transforma- high-Z (typically cation–cation) cor- neutron detected. The standard set-up tion incorporates any diffuse scat- relations only. PDFs can be analyzed at NOMAD uses neutrons within a tering contributions and provides a in a similar manner to diffraction wavelength band of 0.1–3 Å covering unique structural insight to the short- patterns using small-box refinement a wide range of momentum transfers range atomic configuration of irradi- in real space with software pack- suitable for pair distribution function ated materials. ages such as PDFgui [6]. An alterna- analysis. The large range of momentum tive method is the large-box, reverse Figure 2a shows a total scatter- transfers, Q, accessible at NOMAD Monte Carlo (RMC) method, which ing structure function S(Q) – 1 of makes it possible to produce PDFs is applied to model both short- and Er2Sn2O7 pyrochlore oxide irradi- with high real-space resolution long-length scales simultaneously us- ated with 2.2-GeV Au ions. Analyz- [5]. Figure 2b shows the PDFs of ing total scattering data [7]. The RMC ing the Bragg peaks with Rietveld Er2Sn2O7 pyrochlore obtained from method is a stochastic modeling ap- refinement yields information about the corresponding structure functions proach capable of yielding relatively the long-range structure of the crys- (Figure 2a). Each peak in the PDF large atomic structure models (includ- talline fraction. The enhanced diffuse represents a specific atom–atom -cor ing, e.g., 16,000 atoms). scattering background is indicative of relation, in which the position corre- The irradiation of samples for neutron characterization requires a special holder system to produce about 100 mg of homogeneously irradiated powder sample. An appropriate amount of powder is pressed into indented aluminium holders with depths that are several µm smaller than the ion range [8]. Thus, the swift heavy ions fully traverse all samples with a homogeneous energy loss, dE/dx, along their penetration depth. The nuclear energy loss can be ne- glected as it is only dominant just before the ions come to rest. The ion irradiation

Figure 2. (a) Neutron scattering structure functions of Er2Sn2O7 pyrochlore experiments are performed at the X0 before and after irradiation with 2.2-GeV Au ions to a fluence of 2×1012 and beam-line of the GSI Helmholtz Center 8×1012 ions/cm2. Bragg peaks are characteristic for the long-range structure. for Heavy Ion Research in Darmstadt, Fourier transformation converts the scattering pattern (reciprocal space) into Germany, a large user facility that offers the (b) pair distribution function (real space). a wide range of ion species and energies

Vol. 30, No. 1, 2020, Nuclear Physics News 17 impact and applications

(Figure 3). The diffuse scattering of the amorphous phase for a given fluence is much larger for Dy2TiO5, indicating that this composition has reduced stability of the long-range crystalline structure. However, characterization of the local structure through pair distribution function analysis evidences a contrast- ing behavior. The local atomic structure of the cubic Dy2Ti2O7 pyrochlore (Fd-3m space group) changes to an orthorhombic weberite-type arrangement Figure 3. Neutron diffraction patterns of (a) Dy2Ti2O7 and (b) Dy2TiO5 oxides 12 2 before and after irradiation with 1.1 GeV Au ions of fluence 5 × 10 ions/cm . (C2221 space group) after ion irradia- Amorphization is evident in both materials by significant Bragg peak intensity tion as shown by distinct changes in the reduction and growth of a diffuse scattering background, which is more pro- pair distribution function profiles (particularly between 2 and 3.5 Å) before nounced in the (b) orthorhombic Dy2TiO5 composition. and after ion irradiation (Figure 4). This transferred for neutron characterization is in clear contrast to Dy2TiO5 with an into quartz capillaries with an outer di- initial orthorhombic symmetry that does ameter of 2 mm and a wall-thickness of not change noticeably at the short range 0.01 mm. under ion irradiation (Figure 4). This Over the past few years we have implies that while Dy2Ti2O7 is more utilized neutron total scattering experi- resistant than Dy2TiO5 over the long ments to investigate the damaged struc- range, the opposite behavior applies to ture in a number of simple and complex the short range. This highlights that in- oxides [9, 10]. Radiation effects are an formation on the local atomic structure important aspect of nuclear engineering (including information on oxygen) is an and much effort is dedicated to devel- important element to comprehensively oping more resistant ceramics for use understand the radiation behavior of Figure 4. Neutron pair PDFs of Dy- in nuclear applications such as fuel or complex oxides. Depending on the spe- 2Ti2O7 and Dy2TiO5 oxides before and waste forms. We selected two examples cific application, it may be more desir- after irradiation with 1.1 GeV Au ions to demonstrate how neutron probes able that the short-range structure does of fluence 5 × 1012 ions/cm2. Based on can provide additional insight into the not change under extreme conditions, in the interatomic distances (peaks in the atomic scale structure of irradiation ef- which case Dy2TiO5 would be the ma- PDF) it is evident that Dy Ti O under- fects. It is well known that the chemical 2 2 7 terial of choice over Dy2Ti2O7. goes a fundamental shift in local atomic composition and starting structure of Fluorite-structured oxides, such as arrangement (pyrochlore-to-weberite complex oxides play a critical role in CeO2 and ThO2, exhibit excellent struc- transition [10, 11]). In contrast, only their radiation behavior. For example, tural stability under a wide range of tem- subtle changes are evident in irradiated X-ray diffraction and electron micros- peratures, chemical environments, and Dy2TiO5 and the local atomic arrange- copy studies revealed that amorphous irradiation conditions. We have shown ment remains nearly unchanged. tracks are forming in Dy2Ti2O7 and Dy- that the redox behavior of the cation 2TiO5 under swift heavy ion irradiation plays a crucial role in these materials with a typical example being 2.2 GeV [12, 13]. The track size is larger for the in understanding the response to swift Au ions. The irradiations are performed latter such that the sample is completely heavy ions [14]. Synchrotron X-ray ab- under normal incidence, in vacuum and amorphized at lower fluences. Neu- sorption spectroscopy showed that the at room temperature using a beam flux tron diffraction experiments confirmed intense ionizing conditions induced by limited to 2–5 × 108 ions/cm2·s to avoid ion-induced amorphization in both high energy ions leads to a partial reduc- macroscopic sample heating. After ion- materials by the loss of Bragg-peak in- tion of tetravalent Ce. This represents beam exposure, the irradiated powder is tensity and increased diffuse scattering an additional defect mechanism that is

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of the shifts of the first nearest-neighbor 4. M. Lang et al., J. Mat. Res. 30 (2015) cation–oxygen, oxygen–oxygen, and 1366. cation–cation correlations showed that 5. J. Neuefeind et al., Nucl. Instr. and the response of the local structure is dif- Meth. B 287 (2012) 68. ferent between CeO and ThO . Most 6. C. L. Farrowet al., J. Phys.: Condens. 2 2 19 (2007) 335219. noticeably, the distortion of the local Matter 7. M. G. Tucker et al., structure of CeO appears to be driven J. Phys.: Condens. 2 Matter 19 (2007) 335218. by the accumulation of vacancies and 8. R. I. Palomares et al., J. Mater. Chem. the facile agglomeration of point defects A 5 (2017) 12193. (Figure 5). The PDFs indicate that per- 9. E. C. O’Quinn et al., J. Mater. Sci. 53 Figure 5. The total correlation func- oxide-like defects with O-O distances (2018) 13400. 10. J. Shamblin et al., . 144 tions, T(r), of CeO2 before and after of ~1.5 Å are formed in CeO2, which Acta Mater irradiation with 2.2-GeV Au ions to a were previously predicted to exist in ir- (2018) 60. fluence of 5×1011, 1×1012, and 5×1012 radiated oxides. Thus, neutron total scat- 11. J. Shamblin et al., Nat Mater. 15 ions/cm2. Notable intra-unit cell cor- tering revealed that cation reduction is (2016) 507. 12. J. Shamblin et al., . 117 relations are labeled. As the fluence in- accompanied by the formation of small Acta Mater (2016) 207. creases, the intensity of the atomic corre- oxygen defect clusters in CeO , which 2 13. C. L. Tracy et al., Acta Mater. 60 lations (peaks) decreases, which signals are absent in ThO2. (2012) 4477. the loss of coherent scattering intensity 14. C. L. Tracy et al., Nat. Commun. 6 from atoms located at ideal sites in the Acknowledgments (2015) 6133. fluorite lattice. A correlation emerges at This work was supported by the r ~ 1.5 Å, indicative of radiation-induced U.S. Department of Energy, Office of formation of peroxide-like defects. Science, Basic Energy Sciences, under Maik Lang and Eric O’Quinn Award DE-SC0020321. The research Department of Nuclear Engineering, at ORNL’s Spallation Neutron Source University of Tennessee, absent in ThO2 with monovalent Th cat- ions. An open question remained on the was sponsored by the Scientific User Knoxville, Tennessee Facilities Division, Office of Basic fate of the oxygen atoms accompanying Jörg Neuefeind the reduction process. To address this is- Energy Sciences, U.S. Department of Chemical and Engineering sue, we irradiated CeO and ThO with Energy. 2 2 Materials Division, 2.2-GeV Au ions to a maximum fluence Spallation Neutron Source, Oak of 5 × 1012 ions/cm2 and investigated References Ridge National Laboratory, the defect accumulation mechanisms 1. M. Toulemonde et al., Ion Beam Oak Ridge, Tennessee using PDF analysis of neutron total Science: Solved and Unsolved scattering measurements. The total cor- Problems (The Royal Danish Acad- Christina Trautmann emy of Sciences and Letters: Copen- relation functions, T(r), PDF difference GSI Helmholtzzentrum für hagen, Denmark, 2006). curves, and small-box refinement re- Schwerionenforschung, 2. J. M. Zhang et al., J. Mat. Res. 25 sults demonstrated that CeO2 exhibits (2010) 1. Darmstadt, Germany; more disordering and more complex de- 3. J. Wang, M. Lang, R.C. Ewing, and U. Technische Universität fect evolution than ThO2 under similar Becker, J. Phys.: Condens. Matt. 25 Darmstadt, Darmstadt, irradiation conditions [8]. A comparison (2013) 135001. Germany

Vol. 30, No. 1, 2020, Nuclear Physics News 19 impact and applications

The Sound of Ions: Acoustic Detection of High-Energy Beams

Introduction tive compact and highly developed can be used for acoustic detection of Acoustic effects of ions have been ultrasound techniques. The history ions, we take a typical example of a well known for many years and work- seems to be a bit similar in nuclear microsecond bunch of 106 12C ions ing at CERN one may have noticed physics, where the acoustic detection with 200 MeV/u energy dumped in the big “bang” when the Large Hadron of particles could offer a rather simple water. The created Bragg peak dose Collider beam is finally damped into a but precise method for heavy ion de- within an assumed spot size of 1 mm2 block of graphite. Acoustic detection tection and beam monitoring, which amounts to about 0.1 Gy, causing a lo- of ions (“ionoacoustics”) belongs to was proposed several times in the past cal temperature increase of only 0.02 the more general thermoacoustic ef- but, however, not much recognized so mK, which finally results in a pressure fect, where a medium is locally heated far. In this article we describe our on- pulse of about 10 Pa (0.1 mbar). Never- by instantaneous energy deposition going developments to use ionoacous- theless, such an admittedly very small and the following adiabatic expansion tics for range determination in proton pressure pulse can be detected, as will creates an acoustic shock wave. This therapy, and in particular for detection be shown, with appropriate ultrasound effect is widely used in optoacoustics of laser accelerated protons and for equipment. To maximize the pressure for biomedical imaging. Here, pres- high energetic heavy ion research. amplitude the beam delivery has to be sure waves are induced by the local, adiabatic and isochoric, which simply often artificially enhanced absorption The Ionoacoustic Effect means: no cooling or expansion of the of light in tissue [1]. First ideas to de- Ions of several MeV energy are heated volume during the energy detect ionizing particles by their sound slowed down in matter initially due position. The first condition (thermal generated in liquids were published to electronic excitation and ioniza- confinement) can be quantified by by Askaryan [2] and seminal experi- tion (electronic stopping) and finally using the thermal diffusivity of water mental studies by Sulak et al. [3], very stopped due to elastic collisions (nu- (0.15 mm2/s), which restricts for our soon considered for cosmic neutrino clear stopping) with a pronounced 12C example with a few mm3 Bragg detection due to thereby affordable energy-loss maximum (Bragg peak) peak volume the ion pulse length to large detector arrays [4]. A very differ- near their end of range. The ioniza- seconds. The second condition (stress ent application of ionoacoustics had tion processes initiate cascades of hot confinement) is more stringent, as it is been later investigated in the emerg- electrons around the ion path, whose determined by the sound velocity in ing field of particle therapy by using energy is transferred within less than water (c ≈ 1.5 mm/μs), which limits the ionoacoustic signal during patient 10−11 s to the atomic subsystem by the contributing beam bunch duration treatment for reconstruction of the ac- electron–phonon coupling. Depending at high ion energies to a few microsec- tual dose distribution [5]. These first on the experimental conditions, heat- onds. Generally, from thermoacoustic attempts had been given up due to the ing rates can be of the order of 1012 theory one can deduce the pressure very low signal-to-noise ratio; a simi- K/s and temperatures of several 100°C amplitude dependency on the deriva- lar difficulty was also experienced for to even above 1000°C can be reached tive of the time and space distribution, cosmic neutrinos. Utilizing improved within a so-called thermal spike in- which favors steep rising pulse and irradiation techniques in proton ther- ducing melting and quenching in dose profiles [8]. apy, several groups revisited recently many solids, which results in the for- the ionoacoustic effect for in-situ ion mation of nanometer-wide ion tracks. Ionoacoustic Range Determination range determination [6, 7]. Compared Despite this energy deposition along with Protons to competing techniques for in-vivo an ion track, it is the maximum energy Our preparatory studies of the range verification, such as positron deposition at the Bragg peak position ionoacoustic effect were performed emission tomography or prompt that is best suited for ionoacoustic ap- at the tandem accelerator of the MLL gamma imaging, ionoacoustics does plication. To get a rough estimate of (Garching, Germany), mostly with not need bulky detectors and complex the macroscopic temperature increase 20 MeV protons. We used a small wa- electronic setups, but can access rela- and associated pressure pulse, which ter tank with an 80-mm-long entrance

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tube terminated by a 50-μm-thick My- confinement is fulfilled for the whole lar foil where the proton beam entered accessible energy range by this pulse from air into water (Figure 1). Accord- width. The expected main frequency ing to the calculated Bragg peak width of the acoustic signal, however, is of about 300 μm, the proton beam was lowered due to the larger Bragg peak chopped to a less than 200-ns-long width to around 15 kHz, which is out ion pulse. The Bragg peak width de- of range for most commercial PZT termines also the mean frequency of transducers. We used, instead of that, the induced ultrasound wave of some an underwater hydrophone, intention- MHz, therefore we used a commercial, ally designed for whale recording. focused 3.5 MHz ultrasound trans- Figure 2. Ionoacoustic signals of This detector type, which is based on ducer based on a lead zirconate titanate 110-ns-long 20-MeV proton pulses; a piezoelectric Polyvinylidenfluorid (PZT) piezo crystal. Due to the small signal numbers correspond to the dif- (PVDF) foil, has an almost constant pressure amplitude of some Pa or even ferent sound paths in Figure 1 and frequency response from some kHz to mPa typically, a low-noise broadband respective arriving times at the trans- at least 250 kHz and a higher sensitiv- preamplifier was used with 60 dB am- ducer [9]. ity than a PZT transducer. The acous- plification and the signal was recorded tic signal was amplified internally with at least 16-fold signal averaging ing phase change) (see also Figure 1). by 35 dB and externally by another by a 500 MS/s digitizing oscilloscope. In stress confinement, the typical 40 dB. Additionally, the low signal- The transducer was mounted on a re- bipolar signal shapes are the result of to-noise ratio made a 1,000-fold av- mote-controlled xyz-stage and for best a superposition of contributions from eraging necessary. The detector setup resolution positioned on beam axis in the spatial and temporal dose distribu- was positioned in the water phantom focal distance from the Bragg peak. A tion. The proton range in water can be on-site at 40.0 cm depth below the typical transducer signal is shown in immediately deduced from these sig- water’s surface and the proton gantry Figure 2 representing three character- nals using the temperature-dependent with its exit nozzle was turned to ver- istic peaks: the first arriving signal (1) sound velocity and compared to simu- tical beam incidence (Figure 3). direct from the Bragg peak, a second lations such as GEANT4 or FLUKA. Proton ranges in water were mea- signal (2) from the entrance foil region Measured and simulated ranges were sured between 145 MeV to 227 MeV about 2.7 μs later (due to the proton found to agree within 2% resulting in range of about 4 mm), and the last sig- submillimeter accuracy [9]. nal (3) after about 5.4 μs, which is the To investigate the ionoacoustic reflection of the Bragg peak signal on range accuracy at clinical energies of the entrance foil (with a correspond- up to 230 MeV, we had access to the just-commissioned superconducting synchrocyclotron (S2C2, IBA) of the Centre Antoine Lacassagne for proton therapy (CAL, Nice, France), which fits exactly in the demands for ionoacoustic range determination. This cyclotron compensates the relativistic mass increase by changing the acceleration frequency from initially about 100 MHz down to 60 MHz, thus only single bunches of protons can be accelerated at a repetition rate of 1 kHz Figure 1. Schematic ionoacoustic set- with a measured pulse width of about 4 up with beam entrance foil, Bragg peak μs. On the other hand, the larger calcu- Figure 3. Experimental setup at CAL position, and ultrasound transducer. lated proton range of as far as 32 cm is with beam exit nozzle over the water Different sound paths to the transducer connected to an increase of the Bragg phantom and an ultrasound hydro- are indicated. peak width of up to 28 mm, so stress phone in 40 cm depth.

Vol. 30, No. 1, 2020, Nuclear Physics News 21 impact and applications

initial energy and compared to a cali- devices are used, such as radio-sen- bration range measurement with an sitive films or nuclear track detectors, ionization chamber on-site as well but they are not adequate for today’s as GEANT4 simulations. Taking the repetition rates in the Hz-range. experimental errors into account the Ionoacoustic detection of laser-ac- agreement was better than 1 mm, and celerated ions could take advantage demonstrated the great potential of of the very intense and short pulse this technique for in-vivo range deter- structure, has a kHz data acquisition mination in proton therapy [10]. Ad- rate, and can, moreover, separate the ditionally, being an ultrasound tech- strong EMP from the acoustic signal nique, it offers by itself the possibility by the distinct ultrasound transit time to correlate the Bragg peak position of at least microseconds. with an ultrasound image of the tu- The measuring possibilities of this mor site, which is a unique advantage novel detection technique were tested over all the other methods mentioned at two high-power lasers with differ- above. The small pressure amplitude ent energy selection systems [11]. and related low signal-to-noise ratio, At the Laboratory of Extreme Pho- however, in connection with the thera- tonics (LEX Photonics, Garching, peutic dose limitation and additional Germany), a Ti:sapphire laser sys- signal distortion inside the patient tem delivers 2.2 J energy within 30 body, pose the greatest challenge for fs at a repetition rate of 1 Hz focused Figure 4. Experimental setup of an ionoacoustics to be overcome on its on target to 1020 Wcm−2. By using a ionoacoustic detector inside a vacuum way to clinical use. Interesting to note, 250 nm thin gold target with its typi- chamber, where the laser pulse hits the the axial resolution of ultrasound im- cal surface contamination, protons production target on the back side, ac- aging at kHz-frequencies is of the or- could be produced and accelerated celerating ions toward the detector. der of centimeters only, as it depends by the laser-induced electromagnetic linearly on the acoustic wave length. field up to about 9 MeV maximum Due to the broad energy distribu- The (submillimeter) ionoacoustic energy; however, with a broad energy tion of the protons the acoustic spec- range accuracy, in contrast, depends distribution. The proton bunch was tra look a bit more complicated than on the time resolution of the detection focused in this experiment by a per- in Figure 2, but information about the system, which was for our proton ex- manent magnet quadrupole doublet energy distribution is imprinted in periments almost independent of the to the ionoacoustic detector position the signal shape and can be deduced signal frequency. outside of the vacuum chamber, ad- by an iterative process, which we re- ditionally cleaned from electrons and fer to as Ion-Bunch Energy Acoustic Detection of Laser-Accelerated low-energy protons by a short mag- Tracing (I-BEAT) [11]. If the detec- Protons (I-BEAT) netic dipole after the quadrupoles. tor transfer function is known from Laser plasma acceleration has seen With different quadrupole settings, calibrations (e.g., by measurements rapid advance in recent years and was certain energies could be selected with mono-energetic protons at considered for very different applica- and enhanced at the detector entrance MLL), the measured acoustic sig- tions, including particle therapy. Ions window. For these tests we used nal can be matched to a simulated delivered by this very specific gener- a compact detector setup consist- wave function by varying detector ation process are extremely confined ing of a water-filled pipe of 10 cm parameters and spatial or temporal in space and time and are accompa- length and 4 cm diameter, terminated structure of the proton bunch. With nied by a strong, laser-induced elec- on one side by a 11 mm Ti entrance this method we could successfully tromagnetic pulse (EMP). This signal foil and on the other side by a trans- reconstruct the energy distributions, can be used for precise triggering, ducer mounted inside a 4 cm standard which were expected from beam op- but causes problems for all kinds of flange. This setup could be also used tic calculations. electronic particle detectors due to its inside the vacuum chamber for mea- A direct experimental validation coincidence with the measuring sig- surements close to the production tar- of I-BEAT with a radio-sensitive film nal. Therefore, often non-electronic get (Figure 4). detector was possible at the Petawatt

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laser system Draco (HZDR, Dres- Acoustic Monitoring of High- noise level, which allowed for single den, Germany), focusing 12 J energy Energy Heavy Ions pulse detection without any averag- with 30 fs pulse length on a 200 nm Highest pulse intensities for heavy ing; even about 200 238U ions in a thin plastic foil. This time, selec- ions are also the aim of the ongoing macro-bunch could be easily detected tion of the broad energy distribution upgrading project FAIR at GSI (Darm- and the pulse micro-structure clearly with proton energies up to 30 MeV stadt, Germany) with design values resolved (Figure 5). For these more was performed by a pulsed solenoid of 1011 238U ions within a 100 ns complex signal structures an auto- lens, which focused a desired energy pulse length in fast extraction mode. correlation analysis in the frequency of about 16 MeV into a calibrated Monitoring of a single ion pulse with domain was necessary instead of the Gafchromic film stack outside of the those intensities may reach or even sound wave traveling time analysis vacuum chamber. The good agree- exceed the limits of most kinds of as used for protons. A direct pro- ment of both methods confirmed detectors and could be another inter- portionality between the number of the I-BEAT reconstruction approach esting case for ionoacoustics. To this ions and the pressure signal ampli- and demonstrated its high depth (and purpose, we performed some tests at tude could be shown around 106 ions hence energy) resolution, which is the upgraded SIS18 synchrotron with per macro-bunch. The measured ion limited for a film stack by film thick- ion beams of 12C (180–240 MeV/u), ranges agreed within 1% with simu- ness. The main advantage of an iono- 124Xe (280–320 MeV/u), and 238U lations by GEANT4, and for 12C also acoustic detector, besides its much (250–300 MeV/u) and pulse inten- with existing range measurements us- higher detection rate, is its insensi- sities from 102 (238U) to 106 (124Xe ing a precisely extendable water col- bility to the harsh conditions con- and 12C) ions [12]. The calculated ion umn with two ionization chambers nected to laser particle acceleration: ranges varied for the utilized energies on both ends. This good agreement the strong EMP can be separated and ions from 10 mm to 120 mm, confirms on the one hand the latest by the slow sound velocity, while therefore the setup shown in Figure 1 International Commission on Radia- the short, intense ion bunch, which was used, which could be adapted to tion Units (ICRU) recommendation saturates most detectors (or possi- all these ion ranges. The correspond- of 78 eV for the value of the ioniza- bly causes radiation damage), does ing heavy ion Bragg peak widths of a tion potential of water used in GE- not affect water as the ionoacoustic few millimeters were related to some ANT4 and on the other hand indicates detection medium. Even a targeted microseconds pulse length for stress the accuracy of a calculated range- pulse intensity of 1011 protons/mm2 confinement, so fast beam extraction energy correlation. The achieved ion would increase the temperature of was used, delivering an ion macro range resolution can be estimated the Bragg peak volume by a few bunch of about 1 μs pulse length from the standard deviation σ of con- Kelvin at most (for mono-energetic with a micro-structure consisting of secutively measured range values and protons), making ionoacoustics an 4–6 ion bunches with 100 ns bunch thus converted into an energy uncer- almost unrivaled detection method length. Due to the higher nuclear tainty. The measured range resolution near the production target or in the charge of heavy ions, ionoacoustic in all experiments was better than beam focus. signal amplitudes were well above

Figure 5. Ionoacoustic signal of 300-MeV/u 238U with about 200 ions per 1 μs macro-pulse [12].

Vol. 30, No. 1, 2020, Nuclear Physics News 23 impact and applications

100 μm, resulting in a remarkable en- signal contains information about 5. Y. Hayakawa et al., Rad. Oncol. In- ergy resolution of dE/E ≤ 10−3. the beam intensity and energy, and vest. 3 (1995) 42. even the energy distribution can be 6. K. Parodi and W. Assmann, Mod. Phys. Lett. A 30 (2015) 1540025. Conclusion and Outlook reconstructed from the signals shape. All in all, ionoacoustics seems to be 7. K. Jones et al., Med. Phys. 42 (2015) Acoustic detection of pulsed ener- 7090. predestinated to be used as a simple getic ion beams had been proposed 8. L. V. Wang and H.-I. Wu, Biomedi- in 1957 and was studied thereafter, but precise detection technique for cal Optics: Principles and Imaging mainly for astrophysical neutrino pulsed heavy ion beams. Our recent (John Wiley & Sons, 2007). detection, and more recently in the results may provide motivation to re- 9. W. Assmann et al., Med. Phys. 42 context of proton therapy, but did consider this method for monitoring (2015) 567. not find great attention in the nuclear of very intense and short ion bunches 10. S. Lehrack et al., Phys. Med. Biol. 62 physics community. Our experimen- delivered, for example, by laser ion (2017) L20. 11. D. Haffa et al., Sci. Rep. 9 (2019) tal tests with high-energy protons acceleration or within upcoming accelerator upgrades. 6714. as well as heavier ions have dem- 12. S. Lehrack et al., Nucl. Instrum. Meth. onstrated the great potential of the A 950 (2020) 162935. ionoacoustic method, which has the Acknowledgments only precondition of a pulsed ion The experiments were performed beam and some microseconds pulse in collaboration with teams from J. width. An ionoacoustic heavy ion Schreiber (MLL, LEX), V. Ntziachris- detector offers, besides its simplicity, tos (IBMI, HZ München), G. Doll- some attractive features: its dynamic inger (UniBW München), and Chr. range spans many orders of magni- Trautmann (GSI Darmstadt). We are tude in particle number, not limited thankful for support from IBA (Bel- by saturation or radiation damage; gium) and CAL (France). This work Walter Assmann the recorded signals are separated was funded by the DFG Cluster of Ex- from coincident beam-induced elec- cellence Munich Centre for Advanced tronic noise; and the per mill en- Photonics (MAP), Germany. ergy resolution even improves with higher energies. The detector setup References consists of a cheap commercial PZT 1. V. Ntziachristoset al., Nat. Biotech- nol. 23 (2005) 313. transducer coupled to an adapted wa- 2. G. A. Askaryan, Atomnaya Energiya terfilled vessel with a thin entrance 3 (1957) 152. window for the ions. The ionoacous- 3. L. Sulak et al., Nucl. Instrum. Meth. tic signals can be recorded by a fast 161 (1979) 203. Katia Parodi digitizing oscilloscope and stored for 4. R. Nahnhauer, Nucl. Instrum. Meth. A Ludwig-Maximilians-Universität further data evaluation. The acoustic 662 (2012) S20. München

24 Nuclear Physics News, Vol. 30, No. 1, 2020 impact and applications

Verification of Arms Control Treaties with Resonance Phenomena

Nuclear disarmament treaties are such as ballistic missiles and strategic for most actinides, making it prone to not sufficient in and of themselves to bomber aircraft. This approach has some isotopic hoaxes. Neutron elastic neutralize the existential threat of nu- left behind large stockpiles of surplus scattering in the MeV scale primarily clear weapons. Technologies are nec- nuclear weapons, exposing them to depends on the size of the nucleus, essary for verifying the authenticity the risk of theft and unauthorized or and as such is a very poor differen- of the nuclear warheads undergoing accidental use, as well as transfer to tiator between nuclei of similar A and dismantlement before counting them third countries. Furthermore, there Z. A much stronger isotopic sensitiv- toward a treaty partner’s obligation. are increased worries that, unless new ity can be achieved by measurements Here we present a review of concepts treaties are implemented, the cur- which are sensitive to resonances in involving isotope-specific resonance rent arsenal sizes will stagnate at the the nucleus: even small change in the processes, Nuclear Resonance Fluo- current numbers [5–7]. New types of number of nucleons results in drastic rescence (NRF) [1] and Neutron Reso- technologies are necessary to enable changes in the resonance parameters nance Transmission Analysis (NRTA) new arms control treaties. These tech- and energies. An NRF-based concept [2, 3], used to authenticate a war- nologies will have to detect hoaxing was proposed and tested via Monte head’s fissile components by compar- attempts, clear honest warheads as Carlo simulations and proof of con- ing them to a previously authenticated such, while simultaneously protect- cept experimentation [1, 14–16]. The template. All information is encrypted ing sensitive information about the reliance on isotope-specific NRF sig- in the physical domain by the addition weapon designs. natures offers strong hoax resistance. of an encrypting filter to the target, But how does one verify that an ob- However, it is not fully ZK, and thus leading to measurements with an out- ject is a weapon without inspecting its needs to undergo thorough checks for come similar to an equation with two interior? Past U.S.– Russia lab-to-lab information security. A second idea unknowns. Using Monte Carlo simu- collaboration included the research was proposed later, which makes use lations and experiments, we show that and development of so-called infor- of NRTA to achieve isotopic imaging the measurements readily detect hoax- mation barriers [8]. These are devices and tomography, while achieving a ing attempts, while no significant iso- that rely on software and electron- near-ZK level of information security topic or geometric information about ics—which can be hacked and that [2, 3]. This technique uses resonance the weapon is released. These nuclear themselves need to undergo verifica- phenomena to achieve isotope-specific techniques can be used to dramatically tion—to analyze data from radiation data signatures, which can be used to increase the reach and trustworthiness detectors and compare the resulting obtain a unique fingerprint of the ob- of future nuclear disarmament treaties. signal against a set of attributes in a ject. This is achieved by exploiting so-called attribute verification scheme nuclear resonances in actinides when Introduction [9, 10]. Unlike these past methods, interacting with epithermal neutrons As of 2019 there are an estimated which relied on electronics and com- in the 1–10 eV range. Unlike fast neu- 13,000 nuclear weapons that make puters, we propose to use physical trons, which do not have this isotope up the nuclear arsenals of the United cryptography, which relies on the im- specificity for high Z nuclei, the epith- States and Russia [4, 5]. Such large mutable laws of physics instead. An ermal neutron transmission signal can arsenals may be one of the greatest early attempt using physical cryptog- be made highly specific and sensitive threats to our civilization. While high, raphy and template verification was to the presence and abundance of in- these numbers are a significant reduc- proposed by researchers at Princeton dividual isotopes. These include 235 U tion from the Cold War era, as a result University [11–13]. The Princeton and 239Pu in highly enriched uranium of a series of arms control treaties. The concept has strong information secu- and WGPu [17]. Also unlike NRF, past treaties between the United States rity in the form of a zero-knowledge the resonant absorption of epithermal and Soviet Union/Russia, however, (ZK) proof. It relies primarily on the neutrons in the beam can be observed primarily focused on the verified dis- non-resonant scattering of fast neu- directly with very high resolution (less mantlement of the delivery systems, trons, a process that is almost identical than eV). This can be done by using

Vol. 30, No. 1, 2020, Nuclear Physics News 25 impact and applications

time-of-flight (TOF) techniques, as NRF-Based Verification germanium (HPGe) photon detectors described in detail in Ref. [2], Supple- NRF describes the X(γ, γl)X reac- at an observed rate (see Ref. [1], Sup- mentary Note 1. These characteristics tion in which a photon γ is resonantly plementary Information, Eq. S8) that allow for direct measurements of reso- absorbed by the nucleus X and then has been reduced by the presence of nant absorption. re-emitted as the excited nucleus sub- the NRF isotope in the warhead. The sequently decays to its ground state hashed measurements required for Template Verification Protocol [23, 24]. The cross-section for an NRF the template verification protocol are The key to any verification proce- interaction with absorption via the res- thus the recorded spectra, since it is dure is a protocol that can guarantee onant energy level Er is given by the impossible to precisely determine the that no treaty accountable item (TAI) Breit-Wigner distribution: warhead composition from the height undergoing verification is secretly mod- 2 of the NRF peaks in the observed ified or replaced with another object.  c  ΓΓrr,0 spectrum without knowledge of the σπrr()Eg=   22 Significant thinking has been invested  Er  ()EE− rr+ ()Γ / 2 detailed composition of the foil. The into the concept of template verifica- exact foil design is therefore decided tion, particularly at the U.S. national where Γr is the width of the level at by the host and kept secret from the laboratories and think tanks [9, 18, 19]. Er, Γr,0 is the partial width for transi- inspector. The influence of the - war The high-level protocol has been either tions between Er and the ground state, head composition on the height of outlined in or been the basis of prior and gr is a statistical factor. For high-Z the NRF peaks—and thus any sensi- warhead verification publications in ac- isotopes of interest, these fundamental tive warhead design information—is ademia [10–12, 14] and in U.S. national widths are typically ~10 meV, but the then said to be physically encrypted laboratories [19–22]. Its basic steps can effective width of the cross-section is by the foil. As an additional layer of be summarized as follows: increased to ~1 eV through Doppler information security, the host may add broadening by thermal motion of the optional “encryption plates” of war- 1. The inspection party makes an target nuclei. Imperfect detector reso- head materials to the measured object unannounced visit to an inter- lution further broadens the measurable so that even if precise inference about continental ballistic missile site NRF resolution to widths of ~1 keV. the measured object is possible, it is and randomly chooses a war- Since the NRF lines of an isotope are impossible to infer anything about the head from one of the missiles. still typically >10 keV apart, the set warhead alone. This warhead can be treated as of resonance energies Er provides a Following the design depicted in the “golden copy” (i.e., the refer- resolvable, one-to-one map between Figure 1, a bremsstrahlung beam was ence for all future comparisons). measurement space and isotopic used to illuminate a circular section of 2. The template is transported un- space. the object undergoing interrogation. der the joint custody of the hosts The MIT NRF verification protocol Since no real nuclear warheads were and inspectors to the site where exploits the isotope-specific nature of available in an academic setting, sev- the candidate warheads will un- NRF to make a template measurement eral proxy warheads were constructed. dergo dismantlement, verifica- of the mass and geometry of the iso- The proxy warheads were objects with tion, and disposition. topes of interest to the inspector. The a set of isotopes—238U and 27Al —that 3. The golden copy and the can- measurement uses a broad-spectrum form the basis for proof-of-concept didate undergo the measure- bremsstrahlung photon source to ir- NRF experiments and subsequent ex- ment in question, whether it is radiate the measurement object; NRF trapolations to more realistic settings in- NRF or NRTA. The signals are interactions in the object preferentially volving weapon isotopes, such as 235U, compared in a statistical test. attenuate the photon flux at specific 239Pu, and 240Pu. For each measured An agreement confirms that energies determined by the unique object, photon spectra from multiple the candidate is identical to the nuclear energy–level structure of each acquisition periods and three separate template and thus can be treated isotope according to how much of the detectors are combined into a single as authentic. A disagreement in- isotope is present in the warhead. The spectrum. Each spectrum is then fit with dicates a hoaxing attempt. remaining transmitted flux at these en- a series of Gaussian functions for the ergies goes on to induce further NRF eight observed NRF peaks in the signal The last step is key to the whole veri- interactions in an encryption foil, lead- region near 2.1–2.3 MeV, on top of an fication process and is the focus of this ing to NRF emission into high-purity exponentially decaying continuum review.

26 Nuclear Physics News, Vol. 30, No. 1, 2020 impact and applications

background. 238U contributes the 2.176, 2.209, and 2.245 MeV peaks; the branched decays 45 keV below each of these three; and a small peak with no branch at 2.146 MeV. 27Al contributes the intense 2.212 MeV peak. Figure 2 shows the comparison between the “golden copy” and the hoax. In Figure 2 (left) the NRF peaks from 238 U and 27Al are plotted. Figure 2 (right) subsequently shows the 26-parameter fits to the two spectra. The counts from the two peaks are compared in a Z-test, with the resulting score of z = 10.7, indicating a clear disagreement. The dis- Figure 1. The schematic of the NRF-based verification concept. The heavy lead crepancies for all verification scenarios shielding ensures that the HPGe detectors can only observe the signal from the are shown in Table 1 of Ref. [1]. In all encrypting foil. Taken from Ref. [1], with permission. four hoax scenarios, a discrepancy in counts greater than an alarm thresh- old of z∗ = 3 was attained in ~20 µA·h (live, on three detectors) per measured object, indicating diversions in the uranium component. In the genuine candidate scenario, the 1.7 σ discrepancy in uranium (primarily a result of day-today beam variations) does not trigger the alarm at z∗ = 3, and is clearly de- lineated from the much larger observed Figure 2. Left: measured spectra for DU template II, zoomed to show the NRF discrepancies in the hoax cases. Simi- signal region. Arrows indicate the branching relationships from the three main 238 larly, the 27Al comparisons all exhibit U lines to the peaks 45 keV lower, as well as the non-branching 2.146 MeV 238 27 |z| < 2, indicating consistency in the U and 2.212 MeV Al peaks. Right: fits to the spectra of template and hoax, aluminum component across all mea- showing a 10$\sigma$discrepancy. A comparison of spectra for all verification surement scenarios. measurements is shown in Table 1 of Ref. [1]. The work reported by Vavrek et al. [1] shows the usability of NRF for ~100 keV. The energies of interest for tonium isotopes of interest can be warhead verification. The extrapola- our methodology, previously reported seen in Figure 3. The data plotted in tions based on experimental condi- in detail in Hecla and Danagoulian [2] Figure 4 show the absorption lines that tions and expected weapon geometries and Engel and Danagoulian [3] are correspond to the resonances in mo- indicate that a realistic warhead verifi- those in the range of 1 ≤ E ≤200 eV. lybdenum and tungsten isotopes, such cation exercise, using state of the art While the neutron interactions in as the 0.13 eV–wide line at 70.9 eV 97 commercial instrumentation, can be the thermal regime are described by from Mo. For a transmission con- achieved in hours, which is satisfac- monotonic changes in cross-sections, figuration these interactions selec- tory for most verification settings. in the epithermal range the neutrons tively remove the original neutrons of can trigger various resonant responses resonant energies from the transmitted in uranium and plutonium. These are beam and give rise to an absorption NRTA-Based Verification typically (n,fission), (n,nl), and (n,γ) spectrum, resulting in unique sets of The epithermal range refers to the reactions, resulting in the loss of the ~0.3 eV–wide notches specific to each neutron energy domain encompassed original neutron from the beam. A isotope. While the resonances are the between the thermal energies of plot of total interaction cross-sections most prominent features of the cross- ~40 meV and fast neutron energies of in the epithermal range for five plu- section, the continuum between the

Vol. 30, No. 1, 2020, Nuclear Physics News 27 impact and applications

or geometrically different. Instead of hollow spheres, which are typical of nuclear weapon pits, simpler cylindrical geometries were chosen, such that the genuine proxy object is a cylin- der of 50.8 mm diameter and 30 mm length, with the first 27 mm consisting of molybdenum and 3 mm consist- Figure 3. General schematic of the experiment (not to scale). The combination ing of tungsten. Such a combination of isotopic and geometric sensitivity is achieved by neutron spectroscopy via the was chosen to mimic the ~90% en- TOF technique and comparisons between the candidate and the genuine refer- richment of WGPu. Unlike molybde- ence under random projections. For simplicity, in this experiment the angles of num or tungsten, the actinide targets the projections were chosen to be 0°, 45°, and 90°. would produce additional neutrons via the (n,fission) reaction. However, the resulting neutrons would be of the ~MeV energies, making the 6Li detector insensitive to them. The encrypting filters were assembled from 3 mm– and 6.35 mm–thick tungsten and molybdenum plates, respectively, that had 76.2 mm ×76.2 mm outer dimensions. The overall diagram of the measurement setup can be seen in Figure 3. The neutrons are produced in a pulsed mode from a pulsed electron linear accelerator, via a tantalum bremsstrahlung-photoneutron converter, which Figure 4. Histograms of neutron count energies for two isotopic hoaxes. (a) The produces neutrons via the (γ, n) reac- template data from an authentic reference of 90/10 Mo/W composition (blue) are tion. A 2.54 cm polyethylene modera- compared to the data from a 50/50 Mo/W isotopic hoax (red). (b) The data from tor degrades the neutrons’ energy from the authentic reference are compared to those from a 10/90 Mo/W isotopic hoax the ~MeV scale to the ~eV scale. As (red). The legend lists the χ2 value, the number of degrees of freedom, and the the epithermal neutrons traverse the corresponding probability (p-value) for the χ2 test. Both hoaxes are rejected. The object and the encrypting filter, their solid and dashed vertical lines denote the locations of some of the known tung- spectrum is modulated in accordance sten and molybdenum resonances, respectively. Data collection lasted approxi- to the cross-sections and areal den- mately 5 minutes per object. Solid vertical lines indicate tungsten resonances, sities of the relevant isotopes, after while the dotted lines show the molybdenum resonances. which they are detected by a 6Li glass scintillator detector. The detector pro- resonances also encodes information tion scenario where the plutonium pit duces a timing pulse, which is com- about the isotopic compositions of has been extracted in a controlled en- pared to the timing pulse of the linear the target. These combined absorption vironment and undergoes verification, accelerator. This comparison allows features yield a unique fingerprint of as described in prior work [2]. Using us to determine ttof = t − t0 of the neu- a particular configuration of isotopics, molybdenum and tungsten proxies for trons. The energy of individual neu- geometry, and density distribution. plutonium (due to the former’s simi- trons can then be reconstructed via E = Our most recent work, in Engel and larity in resonance energies to those of 2 , m(d/ttof) /2 where m and d are the neu- Danagoulian [3], focused on a sensitiv- plutonium), the technique is shown to tron mass and the flight path length, ity study, experimentally demonstrat- be capable of clearing objects identi- respectively. The transmission spectra ing the feasibility of the comparison. cal to the genuine reference object and are normalized to the incident neutron This study thus focuses on an inspec- rejecting objects that are isotopically count, determined by a fission cham-

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ber (not shown) upstream of the target statistically indistinguishable signals. It parison, neutron beams can be pro- object. To test the sensitivity of the is demonstrated that using an encrypt- duced via multiple methods: nuclear technique to isotopic variations, the ing filter of just 1.8 kg will result in an reactors as high-intensity sources and 90%:10% Mo:W genuine reference inferred range of the pit’s possible mass choppers to enable TOF measure- object’s transmission spectrum was that spans from zero to a value that is ments; compact deuterium-deuterium compared to the transmission spectra significantly larger than the critical and deuterium-tritium generators, as of 50%:50% and 10%:90% Mo:W ob- mass. This makes it impossible for the proposed in Ref. [28]; linear accel- jects of the same cylindrical shape and inspectors to learn information of value, erators; and so on. Furthermore, the overall dimensions. Figure 4 shows the similar (but not identical) to the concept neutron beams allow very high-pre- plots and comparisons of the spectra. of zero-knowledge proof. At the same cision energy reconstruction via TOF The comparisons show that, as the time, additional simulations show that techniques. Finally, pulsed sources, proportion of tungsten is increased, pairs of 5-minute-long measurements such as linacs, can then be combined the tungsten absorption lines show in- at an experimental facility similar to the by a second chopper, which can di- creased absorption, while the molyb- one used in this study can readily detect rectly and physically obscure parts of denum lines exhibit reduced absorp- cheating scenarios where the WGPu pit the neutron spectrum, and thus allow tion, as expected. A simple χ2 test can has been replaced with RGPu, or where for a high degree of information se- be applied, determining the values of its size has been reduced by 2 mm or curity. A future treaty can select from χ2 and the corresponding probability less, depending on experimental con- these options, possibly combining p that the difference is merely due to ditions. See Supplementary Note 3 in some along with concepts developed random fluctuations. For these com- Engel and Danagoulian for a detailed by other research groups [12]. parisons the p-value is consistent with discussion and calculations [3]. 0 to 10 significant digits, and thus References indicates that a systematic difference Conclusions 1. J. R. Vavrek, B. S. Henderson, and 2 is present. The χ test thus rejects the Warhead verification requires A. Danagoulian, Proc. Natl. Acad. comparison and indicates a hoaxing high-precision comparisons of the Sci. USA 115 (2018) 4363. attempt. All measurements lasted ap- isotopic-geometric compositions 2. J. J. Hecla and A. Danagoulian, Nat. proximately 5 minutes. See Table 1 in of two objects—the “golden copy,” Comm. 9 (2018) 1259. Engel and Danagoulian [3] for the full which serves as the reference, and 3. E. M. Engel and A. Danagoulian, Nat. results of the template–hoax compari- the candidate object. Resonance phe- Comm. 10 (2019) 1. sons. nomena—whether triggered through 4. H. M. Kristensen and R. S. Norris, One of the important goals of the epithermal neutrons, MeV photons, Bull. Atom. Sci. 74 (2018) 120. verification system is information se- or via other particle interactions— 5. H. M. Kristensen and M. Korda, Bull. Atom. Sci. 75 (2019) 73. curity; that is, the inspectors’ inability serve as a great tool for achieving 6. J. Mattis, Nuclear Posture Review, to learn significant information about such comparisons due to their sen- Office of the Secretary of Defense the TAI. In our prior work in Ref. [2] sitivity to the isotopic makeup of an (2018). we showed via computational simu- object. The concepts explored and 7. H. M. Kristensen, in Nuclear Safe- lations that, while the inspectors can tested via proof of concept experi- guards, Security, and Nonprolifer- learn information about the combined ments are based on NRF and NRTA. ation, ed. J. Doyle (Elsevier, New content of the weapon component and Both results show very strong de- York, 2019). the encrypting filter, they cannot learn pendence on isotopic composition. 8. S. S. Hecker, Doomed to Cooperate: anything specific to the weapon com- The advantage of the NRF system How American and Russian Scien- ponent itself. To extend this, we use is the penetrating power of the MeV tists Joined Forces to Avert Some of experimental data from the measure- photons. Their downside is the in- the Greatest Post-Cold War Nuclear Dangers (Bathtub Row Press, Los ments in combination with a Geant4 formation-rich content of the ob- Alamos, New Mexico, 2016). [26, 27] computational model of the served spectra, which are difficult to 9. J. Fuller, Arms Contr, Today 40 (2010) experiment to simulate scenarios with modulate and obscure, as well as the 19. a WGPu pit and an encrypting filter. In necessity for high-intensity photon 10. J. Yan and A. Glaser, Sci. Glob. Sec. these data-driven simulations we show beams and long measurements. Fur- 23 (2015) 157. that various opposite combinations of thermore, the photon beams require 11. A. Glaser, B. Barak, and R. Goldston, the TAI and filter geometries produce specialized instrumentation. By com- Nature 510 (2014) 497.

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12. S. Philippe et al., Nat. Comm. 7 24555. Idaho National Laboratory 23. F. Metzger, Prog. Nucl. Phys. (1959). (2016) 12890. (2012). 24. U. Kneissl, H. Pitz, and A. Zilges, 13. S. Philippe, A. Glaser, and R. J. Goldston, 18. S. Drell et al., Tech. Rep. Mitre Corp., Prog. Part. Nucl. Phys. 37 (1996) 57th INMM Annual Meeting, July McLean VA, Jason Program Office 349. 24–28, 2016, Atlanta, Georgia. (1993). 25. A. Koning et al., International Con- 14. R. S. Kemp, et al., Proc. Nat. Acad. 19. P. Marleau et al., Tech. Rep. ference on Nuclear Data for Science Sci. 113 (2016) 8618. SAND2015-5075 Sandia National and Technology (EDP Sciences, 15. J. R. Vavrek, Monte Carlo simula- Laboratories, Los Alamos National 2007). tions of a physical cryptographic Laboratory, 2015. 26. J. Allison et al., Nucl. Instr. Meth. warhead verification protocol 20. P. Marleau and E. Brubaker, Tech. Phys. Res. Sec. A: Accelerators, using nuclear resonance fluores- rep. Sandia National Laborato- Spectrometers, Detectors and Asso- cence (Master’s thesis, SAND2016- ries (SNL-CA), Livermore, CA ciated Equipment 835 (2016) 186. 5714C, Massachusetts Institute of (2016). 27. E. Mendoza et al., IEEE Trans. Nucl. Technology, 2016). 21. A. J. Gilbert, et al. 2017. Nucl. Instr. Sci. 61 (2014) 2357. 16. J. Vavrek et al., Advances in Nuclear Meth. Phys. Res. Sec. A: Accelera- 28. E. M. Engel, E. A. Klein, and A. Nonproliferation Technology and tors, Spectrometers, Detectors and Danagoulian, arXiv preprint Policy Conference, September 25–30, Associated Equipment 861 (2017) arXiv:1909.11120 (2019). 2016, Santa Fe, New Mexico. 90. 17. D. L. Chichester and J. W. Ster- 22. K. Seager et al., Proc. 42nd Ann. Areg Danagoulian bentz, Tech. Rep. INL/CON-12- INMM Meet. (2001). Massachusetts Institute of Technology

30 Nuclear Physics News, Vol. 30, No. 1, 2020 meeting reports

Founding of the International Biophysics Collaboration (IBC)

The International Biophysics Collaboration (IBC) was established during a meeting at GSI/FAIR on 20–22 May 2019. With 250 participants from 27 countries on five continents, the meeting demonstrated the enormous interest of the scientific community for the biomedical applications of nuclear physics at future accelerators. A picture of the collaboration is shown in Figure 1. This collaboration is not focused on a single common project or detector, but stems directly from new requests imposed by the quickly evolving field of applied biomedical physics. Flash therapy, mini-beam therapy, or proton–boron enhanced therapy are new and exciting challenges that joined Figure 1. A picture of the IBC collaboration at the May 2019 meeting at GSI. other items already on the table, like the biological response to carbon ther- as an unique entity to endorse finan- All these IBC activities will be apy and so on. All these new topics cial requests of participating groups to tackled with the prescription to be a indicate that there is new, fundamental funding agencies and to coordinate and network as multicentric and plural as research to pursue about the biologi- help the access of the research groups to possible to maximize the possibility of cal response to radiation and that the the laboratories where applied nuclear success. frontiers of this research are not only physics programs are planned and in the extension to higher intensity biomedical research will be possible. Marco Durante or higher energy, but also in the deep The IBC will serve all these facilities GSI Helmholtzzentrum fur physical and biological mechanism. and will develop research programs Schwerionenforschung, On perspective, the fallout of this very and specific devices for use at various Darmstadt, Germany; Technische basic research is not limited to particle accelerators. Universität Darmstadt, therapy and to the related research and The program of IBC, however, Germany development (i.e., new tomography aims to go beyond facilities resource modalities or particle beam moni- coordination. One of the IBC main Yolanda Prezado toring) but has also implications in targets is the improvement of the Institute Curie, Orsay, CNRS, several items like radio protection in communication among research France Vincenzo Patera space. groups working on the same items The IBC can be an effective network and thematic working groups will be Vincenzo Patera among all the different groups and lines settled and periodic meetings will be University of Rome “La Sapienza”, of research. For instance, IBC can act organized. Italy; INFN ROMA1, Rome, Italy

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Sunny “Strangeness in Quark Matter” in Bari

The 18th International Conference on Strangeness in Quark Matter (SQM 2019) was held from 10 to 15 June in Bari, Italy. Hosted by the Italian National Institute for Nuclear and Par- ticle Physics (INFN), the conference attracted more than 270 attendees from 32 countries, the largest participation ever for the SQM series (Figure 1), and focused on new experimental and theoretical developments on the role of strange and heavy-flavor quarks in high-energy heavy-ion collisions and in astrophysical phenomena. The scientific program consisted of 50 invited plenary talks, 76 contributed parallel talks, and a quite rich poster session, with more than 60 contributions. A state- of-the-art session opened the conference, Figure 1. More than 270 participants attended the 2019 Strangeness in Quark with a tribute to Roy Glauber, entitled Matter Conference in Bari (Image credit: Domenico Elia, INFN Bari). “The Glauber Model in High-Energy Nucleus-Nucleus Collisions,” followed in small systems. An increasing interest by sessions dedicated to highlights from in transverse-momentum differential theory and experiments. Representatives baryon-to-meson ratios in the heavy- from all major collaborations at CERN’s flavor sector was also evident. Recent Large Hadron Collider (LHC) and SPS, results from pp and Pb–Pb collisions Brookhaven’s RHIC, the Heavy Ion from both ALICE and CMS suggest Synchrotron SIS at the GSI Darmstadt, that the same dynamics observed in the 0 and the NICA project at the JINR Dubna ratio Λ/K S may be present in the Λc/D made special efforts to release new results despite the fact that strange and charm at this conference. quarks are thought to be created in dif- Among the highlights presented at ferent stages of system evolution. Figure 2. Chairman Domenico Elia the conference, identified particle yield A promising new perspective for opening the SQM 2019 Conference. measurements were shown to be pro- the LHC data is to use high-energy pp gressing toward determining where and p–Pb collisions as factories of iden- of deconfinement were shown by the in phase space phenomena such as tified hadrons created by a source of NA61/SHINE Collaboration. First strangeness enhancement are focused. finite radius and then measure the ensu- results on strangeness production at low Collective behavior in small systems ing interactions between these hadrons energy from HADES and BM@N also was also a highlighted and much dis- using femtoscopy. This technique has enriched the discussion at SQM 2019. cussed topic, with new results from allowed the ALICE Collaboration to Presentations at the final session PHENIX showing that p-Au, d-Au, and study interactions that were so far not showed good prospects in the field 3He-Au exhibit elliptic flow coefficients measured at all and probe, for instance, for future measurements with FAIR at consistent with expectations regarding the p-Ξ and p-Ω interaction potentials. GSI Darmstadt, NICA at JINR Dubna, their initial collision geometry. Further These results provide fundamental con- Heavy Ions at J-PARC Tokai, and at results from ALICE, CMS, and STAR straints to the QCD community and CERN with the currently ongoing complete the picture and consistently are significant also in the context of upgrades opportunities for HL-LHC corroborate the presence of elliptic flow astrophysics. New results on the onset and next generation experiments. Per-

32 Nuclear Physics News, Vol. 30, No. 1, 2020 meeting reports

spectives for QCD measurements at conference series: the inaugural “Andre Domenico Elia future electron-ion collider facilities Mischke Award” was assigned to the INFN Bari were also presented. young scientist with the best experi- Chairman of the SQM 2019 Two young scientist prizes, spon- mental contributed talk at SQM 2019. Conference sored by the NuPECC, were awarded The next edition of the SQM confer- to the best experimental and theory ence will take place in Busan, Korea, in posters, respectively. A special award May 2021. ORCID dedicated to the memory of a friend and SQM 2019 website: https://sqm2019 Domenico Elia colleague has been established for this .ba.infn.it/ http://orcid.org/0000-0001-6351-2378

TAN 19: International Superheavy Element Research Community Met in Wilhelmshaven, Germany

The 6th International Conference from the GSI Helmholtzzentrum für the leader of the discovery teams of on the Chemistry and Physics of the Schwerionenforschung, Darmstadt, elements 114–118 (flerovium, mosco- Transactinide Elements (TAN 19) Germany, discoverers of elements vium, livermorium, tennessine, and took place in Wilhelmshaven, Ger- 107–112 (bohrium, hassium, meitner- oganesson) were among the distin- many from 25–30 August 2019. About ium, darmstadtium, roentgenium and guished participants. 130 researchers from 19 countries on copernicium); Dr. K. Morimoto from This IYPT special symposium four continents gathered to discuss all RIKEN Nishina Center for Accelera- featured welcome addresses from the experimental and theoretical aspects tor-Based Science in Japan, member presidents of the International Union of this multifaceted science field of the discoverer team of element 113 for Pure and Applied Chemistry focusing on the heaviest elements. (nihonium); and Prof. Y. Oganessian (IUPAC) and the International Union The scientists presented their most from the Joint Institute for Nuclear for Pure and Applied Physics (IUPAP), recent achievements investigating the Research (JINR) in Dubna, Russia, Prof. Q.-F. Zhou and Prof. M. Spiro, atomic, chemical, and nuclear properties of these exotic elements at the end of the periodic table. TAN 19 took place in the Inter- national Year of the Periodic Table (IYPT) 2019, proclaimed by the United Nations, celebrating the 150th anniversary of the publication of this icon of the natural sciences by Dmi- try Mendeleev in 1869. Until today, the periodic table was expanded to include 118 elements up to oganesson, which completes the periodic table’s seventh period. On occasion of IYPT, TAN 19 featured a special symposium. Key members of the teams that have Figure 1. Element discoverers, lab directors, and the conference chairs during discovered the chemical elements the special symposium on the occasion of IYPT 2019. (From left to right: Prof. 107–118, including Prof. G. Mün- Düllmann, Prof. Armbruster, Prof. Münzenberg, Prof. Giubellino, Dr. Morimoto, zenberg and Prof. P. Armbruster Prof. En’yo, Prof. Dmitiriev, Prof. Oganessian, and Prof. Block) (copyright: GSI).

Vol. 30, No. 1, 2020, Nuclear Physics News 33 meeting reports

respectively, and their national coun- example, described the role of the discussed the future research direc- terparts from the Deutsche Physika- German Chemist Lothar Meyer in the tions in superheavy element research lische Gesellschaft and the Gesell- development of the periodic table. in their laboratories (Figure 1). schaft Deutscher Chemiker, Prof. He was born in Varel, a small nearby The TAN conference series was D. Meschede and Dr. M. Urmann, town south of Wilhelmshaven. The established in 1999, when it took respectively. present directors of the research place in Seeheim, Germany. It was Prof. G. Münzenberg, Dr. Morim- centers where elements 107–118 then held in the United States, Swit- oto, and Prof. Oganessian reviewed were discovered, Prof. P. Giubel- zerland, Russia, and Japan, and now their pioneering work on the ele- lino, scientific managing director returned back to Germany. The meet- ment discovery experiments. Their of GSI and the international Facil- ing was organized by the GSI Helm- presentations were complemented by ity for Antiproton and Ion Research holtzzentrum für Schwerionenforsc- talks from Prof. K. Ruthenberg (HS that is presently under construction hung in Darmstadt, the Helmholtz Coburg, Germany), Dr. P. Thyssen in Darmstadt; Prof. H. En’yo, direc- Institute Mainz, and the Johannes (KU Leuven, Belgium), and Prof. tor of the RIKEN Nishina Center for Gutenberg University Mainz, with G. Boeck (University of Rostock, Accelerator-Based Science in Wako, Prof. Ch. E. Düllmann and Prof. M. Germany) that illuminated histori- Japan; and Prof. S. Dmitriev, direc- Block as conference chairs. The sci- cal and philosophical aspects of the tor of JINR’s Flerov Laboratory of entific program comprised 51 oral periodic table. Prof. G. Boeck, for Nuclear Reactions, Dubna, Russia, presentations and 38 poster contributions. Six young scientists received awards sponsored by NuPECC and GDCh for their outstanding poster contributions (Figure 2). TAN 19 was endorsed by IUPAC, IUPAP, and EuChemS and was finan- cially supported by DFG, GDCh, NuPECC, Johannes Gutenberg Uni- versity Mainz, GSI Helmholtzzentrum Darmstadt, and Helmholtz Institute Mainz.

Michael Block and Ch. E. Düllmann GSI

ORCID Michael Block Figure 2. NuPECC representative Prof. R.-D. Herzberg (left) and the confer- http://orcid.org/0000-0001-9282-8347 ence chairs (right) with the young scientists showing their poster awards at Ch. E. Düllmann TAN19 (Photo credit: S. Chenmarev). http://orcid.org/0000-0002-1194-0423

34 Nuclear Physics News, Vol. 30, No. 1, 2020 meeting reports

JENAS: Astroparticle, Nuclear, and Particle Physicists Meet

The first JENAS, Joint European Committee for Future Accelerators (ECFA)–Nuclear Physics European Collaboration Committee (NuPECC) –AstroParticle Physics European Consortium (APPEC) Seminar, attracted 230 participants, resulting in a full auditorium at the Labo- ratoire de l’Accélérateur Linéaire (LAL) in Orsay (Figure 1). Beyond the regular information exchange across the three European committees, the importance is recognized to reinforce their interdisciplinary links. For three days, senior and junior members of the astroparticle, nuclear, and particle physics communities presented their overlapping challenges. Together they have a strong aspira- tion to explore nature with a view to Figure 1. Attendees of the first JENAS meeting. understand both the smallest and the largest structures. On the technology front, they seek to make visible the APPEC, ECFA, and NuPECC. From can be submitted to the chairs of the invisible at these extremes, and these a survey among the seminar partici- three committees/consortia for further successes are transformed into oppor- pants the diversity aspects will be discussion within APPEC, ECFA, and tunities at the human scale for, among analyzed together with those from NuPECC. Thoughts revolving around others, health, energy, and safety. other conferences and events orga- potential synergies in technology, Readout electronics, Silicon Photo- nized by the three communities. physics, organization, and/or applica- multipliers, Big Data computing, and The JENAS2019 event, which was tions are welcome. The letters should Artificial Intelligence for analysis are jointly organized by LAL-Orsay, IPN- elaborate on the synergy topic, the only some examples of developments Orsay, CSNSM-Orsay, IRFU-Saclay, objectives, the initial thoughts, and essential for our research. Related to and LPNHE-Paris, allowed astropar- the potential communities involved. the quest of unraveling new insights ticle, nuclear, and particle physics These letters are not the end of the in fundamental physics, coverage is researchers to sniffle into each other’s process, but potentially the start of fur- required from all three fields in order activities. The identified challenges ther communications on the expressed to address the dark matter problem, can transform via joint programs into interest. APPEC, ECFA, and NuPECC the neutrino sector, and the phys- opportunities to deepen our under- will discuss and propose actions to ics with gravitational waves. In pre- standing of physics. Being informed pursue your thoughts with a view to sentations on organizational matters by the presentations and discussions the next JENAS event in two years. related to education, outreach, open and with a view to further explore top- Website: https://jenas-2019.lal.in2p3.fr science, and software, as well as ical synergies between the disciplines, careers, synergies are clearly identifi- in the closing remarks a call was issued able. At the occasion of this meeting for novel Expressions-of-Interest. Marek Lewitowicz a Diversity Charter was launched by Bottom-up and community thoughts GANIL

Vol. 30, No. 1, 2020, Nuclear Physics News 35 meeting reports

Quark-Gluon Plasma in Wuhan: Quark Matter 2019

The 28th International Confer- ence on Ultra-Relativistic Nucleus- Nucleus Collisions, organized by Central China Normal University (CCNU) and Southern China Normal University (SCNU), and chaired by Profs. Feng Liu (CCNU), Enke Wang (CCNU and SCNU), and Ben-Wei Zhang (CCNU), was held in Wuhan, Hubei Province, P.R. China, on 3–9 November 2019 (Figure 1). This Figure 1. One of the plenary sessions in Quark Matter 2019. series of conferences, better known as “Quark Matter,” is the prime venue Among the main results presented tion of the QGP based on the recent new for the community that studies the at the conference, a surprising obser- observations in experiments. production and properties of Quark- vation of sign flip of the hyper-kur- Discussions on the future of the Gluon Plasma (QGP), a state of mat- tosis of proton numbers at two dif- field, either in the high-energy ter where quarks and gluons are lib- ferent beam energies of 200 GeV and domain (LHC, RHIC, FCC/SppC), or erated and no longer confined inside 54.4 GeV in Gold–Gold collisions at the lower energies (HIAF, J-PARC, hadrons. It is the second time that the was extensively discussed and pro- NICA, FAIR, SPS, RHIC-BES2), Quark Matter conference was hosted vided more important information to where a high-baryon density of QGP in China. The first was in Shanghai in understand the nature of the transition can be formed, or finally via preci- 2006. Approximately 850 physicists from the hadron phase to the quark sion measurements to be performed from more than 30 countries gath- gluon plasms phase. at a forthcoming China and/or U.S.- ered in Wuhan, discussing the recent Discussions on QGP-like phenom- based Electron-Ion collider, was part progress in the field, presented in 38 ena in the collisions of small systems of the concluding session of Quark plenary talks, 184 parallel talks, and (pp, PA), as the presence of collective Matter 2019. All the talks presented at 370 posters. particle followed, as well as correla- the conference are available at https:// After an introductory talk by tions in spite of the few scatterings qm2019.ccnu.edu.cn. Prof. Barbara Jacak on the sta- that take place in such collisions also tus and challenges to understand received a lot of attention. Heng-Tong Ding, Feng Liu, quark matter, the conference started The chiral magnetic effects, a mac- and Ben-Wei Zhang with a series of highlights of recent roscopic manifestation of the chiral Key Laboratory of Quark & Lepton experimental results obtained by the anomaly of QCD, as well as many Physics (MOE) and Institute of ALICE, ATALS, CMS, and LHCb other magnetic field–induced effects Particle Physics, Central China collaborations in the collision of ultra- and on the related observations in a Normal University, relativistic lead beams at CERN-LHC, QGP, were extensively discussed. Wuhan, China as well as the PHENIX and STAR col- As usual, the production of hard and laborations at the BNL-RHIC collider. electromagnetic and weak probes (jet, Enke Wang Other experimental results, as well heavy quarks, dileptons, etc.) in nuclear Guangdong Provincial Key as significant progress on the theory collisions was extensively discussed Laboratory of Nuclear Science, side, were the main focus of the large and impressive progress was shown Institute of Quantum Matter, number of plenary, parallel, as well as in the theoretical understanding of this South China Normal University, poster presentations. fundamental tool for the characteriza- Guangzhou, China

36 Nuclear Physics News, Vol. 30, No. 1, 2020 news and views

Multimedia Spectacle At the Intersection of Two Infinities at the 45th Congress of Polish Physicists in Krakow (Poland), 13–18 September

A unique multimedia spectacle, entitled At the Intersection of Two Infinities, provided spectacular evening entertainment at the 45th Congress of Polish Physicists, held in Krakow, 13–18 September 2019. Directed by Professor Adam Maj, from IFJ PAN, the show interweaved educational elements in a dazzling combination of music composed and performed by musical legend Józef Skrzek (and other artists; see below), with special narration, performed by Dr. Hab. Jerzy Grębosz from the IFJ PAN, which accompanied the associated films and animation videos. Combining music, film, and spoken word (Figure 1), the entire history of our universe was illustrated from singulari- Figure 1. Snapshot from the multimedia extravaganza that combined music, ties that triggered the Big Bang (Bubble film and spoken word, to illustrate the entire history of the Universe. Universe - Multiverse), through the Big Bang and the production of elemental end of our Universe, namely as a result Ela Skrzek (vocal), and school chil- hydrogen, it continues with the forma- of the “Big Rip,” featuring the epic role dren Wiktoria and Julia Minda (saxo- tion of stars and the nuclear nucleosyn- supermassive black holes may play in phone and oboe). thesis of the light elements (helium to this endgame scenario, leading finally The show was dedicated not only iron), and to cataclysmic supernova to the possibility of creating a new sin- to the participants of the Congress, explosions which allow the elements gularity and perhaps a New Universe! but was open to the general public. heavier than iron to form. It is the re- This special physics feast for the In total, approximately 1,000 people sultant scattering of these elements into ears, eyes, and brain was directed were in the audience, all of whom the vastness of the Universe, fragments on the basis of a script prepared by enthusiastically witnessed this won- of which coalesced into a planet orbit- Adam Maj, Jerzy Grębosz, and Bog- derful spectacle bringing together art ing in the “goldilocks” zone around dan Fornal from IFJ PAN and Mark and science! another star, that ultimately created life Riley from Florida State Univer- The event was filmed and the film on Earth. The climactic suite of music sity. The literary texts of Krzysztof can be downloaded from https://www. refers to this fact—that the Universe Niewrzęda were also used. In addi- ifj.edu.pl/en/popularization/spectacle- gave birth to us, the “Children of the tion to Józef Skrzek (keyboards), the mgs/ Stars,” people living, as Blaise Pascal show featured Jerzy Grębosz as nar- put it, “at the intersection of two infini- rator, Mirosław Muzykant on percus- Adam Maj ties”: the microcosm of atoms and the sion instruments, CzeT Minkus on Institute of Nuclear Physics PAN macrocosm of the Universe. The show electric trumpet, the Nowodworski Mark Riley concluded with a possible vision for the Choir (conductor Ryszard Źróbek), Florida State University

Vol. 30, No. 1, 2020, Nuclear Physics News 37 news and views

The International Year of the Periodic Table of Chemical Elements

The United Nations General Assembly, during its 74th Ple- nary Meeting, proclaimed 2019 as the International Year of the Peri- odic Table of Chemical Elements (IYPT 2019) in December 2017. The IYPT2019 was adopted by the General Conference of the United Nations Educational, Scientific, and Cultural Organization. The proc- lamation commemorates the 150th anniversary of Dmitri Mendeleyev’s discovery of the periodic system (see the special edition of Nuclear Physics News, vol. 29, no. 1, 2019). 2019 also marks the 100-year anniversary of the International Union of Pure and Applied Chemistry (IUPAC). Figure 1. Unveiling the face of element 117 tennessine during the IUPAC Gen- For more than three decades, eral Assembly meeting in Paris—Nathan T. Brewer of Oak Ridge National Lab- claims of the discovery of new ele- oratory and Joint Institute for Nuclear Physics and Applications, Oak Ridge, ments have been analyzed by the Joint Tennessee, USA. Working Group, initially called the Transfermium Working Group, created by IUPAC and the International of Younger Chemists (see https:// Dr. Jacklyn M. Gates, Lawrence Union of Pure and Applied Physics iupac.org/100/pt-of-chemist/). These Berkeley National Laboratory, USA (IUPAP), established in 1922. Recent young scientists were selected from (116, livermorium); Dr. Nathan T. additions of new elements to the Peri- hundreds of nominations. The selec- Brewer, Oak Ridge National Labo- odic Table and the naming process of tion committee evaluated research ratory, USA (117, tennessine; Fig- these new elements triggered much accomplishments as well as activi- ure 1); and Dr. Sofiya Aydinyan, public attention. Thousands of peti- ties in professional societies and National Academy of Science of tions with proposed names for new for the broader community from a Armenia (118, oganesson). elements reached the IUPAC commit- talented and diverse candidate pool. All these younger scientists are tee after the discoveries of elements The faces of the six heaviest ele- actively involved in the present 113, 115, 117, and 118 were officially ments, from Z = 113 to Z = 118, were experimental and theoretical inves- accepted. unveiled during the ceremony at the tigations of superheavy elements The 50th General Assembly and General Assembly Meeting. The win- and nuclei. During their scientific 47th World Chemical Congress of the ners are: Dr. Nozomi Sato, RIKEN, careers they will likely see the dis- IUPAC took place in Paris, France, Japan (113, nihonium); Dr. Leonid coveries of the next new elements, from 5–12 July 2019, with over V. Skripnikov, Petersburg Nuclear like 119 and 120, or perhaps even 2,400 participants from 67 coun- Physics Institute, Russia (114, heavier ones. tries. After many international con- flerovium); Dr. Galina Knyazheva, sultations, IUPAC, with help from Flerov Laboratory of Nuclear Reac- the International Younger Chemists tions at the Joint Institute for Nuclear Krzysztof Piotr Rykaczewski Network, created a Periodic Table Research, Russia (115, moscovium); Oak Ridge National Laboratory

38 Nuclear Physics News, Vol. 30, No. 1, 2020 news and views

Superheavy Elements at the Closing Ceremony of the IYPT2019

2019 was the International Year of the Periodic Table (IYPT). It marked the celebration of the 150th Anniversary of Mendeleev’s Peri- odic Table and the completion of the seventh row of the table. The Open- ing Ceremony took place 29 January at the headquarters of the the United Nations Educational, Scientific, and Cultural Organization (UNESCO) in Paris and was completed with a Closing Ceremony on 5 December at the Tokyo Prince Hotel, hosted by the Chemical Society of Japan, Sci- ence Council of Japan, and RIKEN on behalf of UNESCO, International Union of Pure and Applied Chemis- try, and the International Union of Figure 1. The boards of 15 superheavy elements from Rf to Og displayed by the Pure and Applied Physics. discoverers. The Closing Ceremony included an impressive list of exhibitions and ses- for the 118 elements from hydrogen from Rf (Z = 104) to Og (Z = 118) were sions; (1) Opening, (2) Introduction of to oganesson, which are displayed in shown in line by M. Itkis (JINR), V. IYPT activities, (3) Discoveries and paving stones and leading to the en- Matveev (JINR), R. Clark (LBNL), Creation of elements, (4)Periodic Table trance of RIKEN, where you will see A. Yakushev (GSI), C. Duellmann for Next Generations, and (5) Closing. a large monument dedicated to niho- (GSI/JGUM), M. Block (GSI/JGUM), There were also musical performances, nium. K. Langanke (GSI), D. Ackermann including one by an orchestra compris- After the piano performance, cel- (GANIL), J. Khuyagbaatar (GSI), M. ing Japanese chemists. ebrated speeches were given with Honoka (Tokyo Gakugei University An important session for readers of institutional introductory movies. This Senior High School) with K. Morimoto Nuclear Physics News was the “Cre- included Victor Matveev for Joint (RIKEN), S. Dmitriev (FLNR,JINR), ation of Superheavy Elements,” which Institute for Nuclear Research, Karl- V. Utyonkov (FLNR,JINR), M. Stoyer started with the piano fantasy “Ni- heinz Langanke for GSI Helmholtz- (LLNL), K. Rykaczewski (ORNL), honium,” played by high school stu- zentrum für Schwerionenforschung, and A. Karpov (FLNR,JINR), respec- dent Honoka Motai. Miss Motai is so Roderick Clark for Lawrence Berkeley tively (Figure 1). devoted to the periodic table that the National Laboratory, Mark Stoyer for These scientists had participated in discovery of nihonium inspired her Lawrence Livermore National Labora- both this ceremony and the 4th Inter- to compose the music she performed. tory, Krzysztof Rykaczewski for Oak national Symposium on Superheavy Her beautiful music was accompanied Ridge National Laboratory, Kosuke Elements (SHE2019), 1–5 December by a screen showing the landscape Morita for RIKEN Nishina Center, and at Hakone. of Nihonium Avenue stretching from a final speech given by Yuri Oganessian Wako City Station to RIKEN. This is representing all the discoverers. Last, Hideto En’yo about a 15-minute “Walk of Fame” the boards of 15 superheavy elements RIKEN Nishina Center

Vol. 30, No. 1, 2020, Nuclear Physics News 39 in memoriam

In Memoriam: Peter von Brentano (1935–2019)

professor at the University of Cologne, several cases, laboratory directors. His serving as managing director for scientific tentacles spread widely and decades. Under his leadership, the sci- lastingly. entific work and worldwide visibility He exhibited great creativity and of the Institute flourished. focused on fundamental concepts, Peter von Brentano was a passion- simple but essential for understand- ate scientist and one of the world’s ing physical phenomena. His profound leading nuclear physicists. Follow- contributions reflect a unique combina- ing early research, largely on isobaric tion of outstanding experimental skills analog states, he focused on low spin with deep theoretical understanding physics and complete spectroscopy and remarkable intuition. using in-beam gamma ray spectros- He served as chairman of the copy, as well as nuclear resonance Nuclear Physics Boards of the Ger- fluorescence spectroscopy, He and man Physical Society (1977–1979) his students also delved deeply into and the European Physical Society Peter von Brentano various nuclear models with theorist (1981–1985) and on other advisory colleagues. With these students and boards. He initiated scientific col- others his studies of the Interacting laborations across the “Iron Curtain” “Das Gegenteil eines Fehlers ist Boson Model, its Dynamical Sym- in Romania, Bulgaria, and East Ger- ein (anderer) Fehler!” (Bernard von metries, the phase transitional scheme many, even when this was politically Brentano aus “Theodor Chindler”) X(5), the Q-phonon model, Valence- difficult. In 2009 he was awarded a [“The opposite of an error is an Mirror-Symmetry, Proton-Neutron- Doctor Honoris Causa of the Univer- error!”]; “Sie müssen zugeben” Symmetry, the Scissors Mode, Mixed- sity of Bucharest. [“You must admit”] Symmetry-States, Supersymmetry in His personality, and its quirks, were —Typical phrases of Peter nuclei, and mixing effects in unbound legendary and unique. When driving, von Brentano states, as well as varieties of nuclear he would often come to a complete shapes, all stamped the Institute as a stop in traffic when a physics discus- With great sadness we report world-leading center and magnet for sion caught his interest, or he would the death of Prof. Dr. Dr. h.c. Peter the study of collective behavior in inadvertently cross the Rhine several von Brentano of the University of nuclei. times. His concern for his students’ Cologne on 20 September 2019, at His work was broad, deep, and pro- well-being and daily life was endur- the age of 84. lific. He published over 640 papers ing. In discussions, he would often He was born in 1935 in Zürich, with over 13,800 citations, strongly change topics in a second, leaving lis- Switzerland, where his family then influencing generations of students teners baffled. lived in exile. When they returned after and colleagues. Incredibly, 209 of his With Peter von Brentano we lost the war he received his Ph.D. from papers were published as an Emeritus one of the world’s leading and cher- the University of Heidelberg and the Professor. He remained active up to his ished nuclear physicists, a scholar of Max-Plank-Institute (MPI) for Nuclear last months. exceptional depth, and a caring per- Physics under the supervision of Profs. As a dedicated university teacher, sonality. He will stay in our memories Dr. Theo Mayer-Kuckuk and Dr. Wof- and mentor to over 100 Ph.D. stu- and those of hundreds of colleagues gang Gentner. dents, he gave them the freedom to worldwide. In 1966, he went with Brigitte, a find their own interests. He loved lifelong companion and spouse, and intensive discussions with students Rick Casten herself a very well-known artist (Tre- and colleagues, often challenging Yale University/MSU-FRIB mezza), to the Universities of Texas them with outrageous statements. and Washington, returning in 1968 to Many of his students have themselves Alfred Dewald MPI Heidelberg. In 1971 he became a become renowned scientists and, in University of Cologne

40 Nuclear Physics News, Vol. 30, No. 1, 2020