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CERNMay/June 2019 cerncourier.com COURIERReporting on international high-energy

WELCOME CERN Courier – digital edition PERSPECTIVES ON THE Welcome to the digital edition of the May/June 2019 issue of CERN Courier. It is 100 years since Ernest Rutherford published his results proving the existence of the proton. For many decades the proton was considered elementary. But ever since experiments at SLAC and DESY started firing into , beginning in the 1960s, deep-inelastic-scattering experiments have revealed a complex internal picture. In this issue we take an expert tour of physicists’ evolving understanding of the proton, and find that there is still much to learn about this ubiquitous – including the origin of its , whether or not it decays and the puzzling value of its radius. Flavour physics is another theme of the issue. LHCb’s observation of CP violation in the charm sector represents a milestone result, and the

collaboration recently released an update of the ratio RK concerning the ratio of certain B- decays. From a theoretical perspective, new gauge and leptoquarks are promising potential explanations for the current anomalies reported in the b- system, although the picture is far from clear and more data are needed. Meanwhile, researchers are also searching for ultra-rare decays that violate -number conservation. Also in this issue: LHCb’s discovery of a new , DESY’s astroparticle ambitions, news on the International Linear , the first image of the centre of a galaxy, and more.

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CP violation in charm decays SKA and treaty-based science EDITOR: MATTHEW CHALMERS, CERN Reports from Moriond DIGITAL EDITION CREATED BY DESIGN STUDIO, IOP PUBLISHING, UK

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IN THIS ISSUE V o l u m e 5 9 N u m b e r 3 m a y /J u N e 2 01 9 It’s Time for a New Generation EHT MEG II/PSI of Power Solutions! Bernet Lison

FOR RESISTIVE AND SUPERCONDUCTING MAGNETS

CT-BOX Impressions Reports from Moriond 2019. 19 Black hole Matching the first image to a MEG II The elusive muon decay that would All-In-One Current Measurement and Calibration System model. 10 signal new physics. 45 Up to ±1.000 A, 1 ppm/K TC, 100 ksps Data-Logger and Oscilloscope CT-Viewer software included with Ethernet, Serial and USB NeWS PeoPle EASY-DRIVER ±5 A and ±10 A / ±20 V Bipolar Power Supply Series ANALYSIS ENERGY FRONTIERS FIELD NOTES CAREERS OBITUARIES LHCb sees CP violation New at Moriond 2019 Feynman Michael Atiyah 1929– Full-Bipolar operation, Digital Control Loop, Ethernet Connectivity • Science in charm Japan puts LHCb ALICE on high- 2019 Hans-Jürg Gerber Device supported by Visual Easy-Driver software • • centenary • FCC and communication • the ILC on ice SESAME p suppression CMS 1929–2018 Bastiaan De • T • industry • Wakefield Giovanni Mazzitelli • goes solar • Flavour boosts search for fourth- accelerators • Vienna paints a picture of the Raad 1931–2018. 71 FAST-PS-M anomalies persist generation Conference on changing face of science Digital Monopolar Power Supplies - up to 100 A • Wakefield record • ATLAS squeezes Instrumentation communication. 59 broken. 7 SUSY. 15 High-Precision Monopolar Power Converters with Gigabit Ethernet • connoisseurs Embedded Linux OS, device supported by Visual PS software talk stats. 19 FeaTureS FAST-PS Digital Bipolar Power Supplies - up to ±30 A and ±80 V PROTON CENTENARY LEPTON-FLAVOUR THE PROTON LEPTON-FLAVOUR UNIVERSALITY CONSERVATION

Full-Bipolar, Digital Control Loop, High-Bandwidth, 10/100/1000 Ethernet R Mathews Rutherford, The proton laid bare Embedded Linux OS, device supported by Visual PS software transmutation and The flavour What a proton is depends Hunting the muon’s the proton of new physics on how you look at it, or forbidden decay The events leading to Recent experimental rather on how hard you MEG II is gearing up to FAST-PS-1K5 Ernest Rutherford’s results hint that some hit it. Our picture of this search for the muon’s Digital Bipolar Power Supplies - up to ±100 A and ±100 V discovery of the proton, electroweak processes ubiquitous particle is flavour-violating decay 1.500 W, Paralleling via SFP/SFP+, 1 ppm/K TC, 10/100/1000 Ethernet published in 1919. 27 are not lepton-flavour coming into focus. 38 to a and a Embedded Linux OS, device supported by Visual PS software independent. 33 . 45 CERNMay/June 2019 cerncourier.com COURIERReporting on international high-energy physics

PERSPECTIVES ON THE NGPS oPINIoN DeParTmeNTSPROTON High-Stability 10-kW Power Supply - 200 A / 50 V VIEWPOINT INTERVIEW REVIEWS FROM THE EDITOR 5 Digital Control Loop, Paralleling via SFP/SFP+, 10/100/1000 Ethernet NEWS DIGEST 13 Embedded Linux OS, device supported by Visual PS software Building scientific DESY’s astroparticle Multi-messenger resilience aspirations adventures APPOINTMENTS 61 New political landscapes Christian Stegmann, Introduction to Particle & AWARDS make international describes the ambitious and Astroparticle On the cover: RECRUITMENT 63 organisations in science plans for the German Physics • Rutherford The fluctuating more vital than ever. 49 laboratory. 51 • Quàntica. 55 density of a high-energy BACKGROUND 74 proton, after PRL 117 052301

(image byCP violation H Mäntysaari). in charm decays 5 SKA and treaty-based science Reports from Moriond

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More than 35 Years of experience A peek into the proton’s complexity recognized in the world of particle accelerator D Dominguez/CERN ow do you visualise a proton? A high-school student might sketch a circle containing three blobs connected Hby springs; an artist might go further by attempting to capture some of the dynamical mayhem of valence quarks, sea quarks and (see right). Ask a phenomenologist, and you could get something like the image on the cover of Turbo-ICT & BCM-RF this issue – a representation, constrained by HERA data, of Matthew the fluctuating gluon density around the valance quarks of Chalmers the proton (or, more precisely, a heat map of the trace of the Editor Wilson line encoding the proton structure at given transverse Optimized to measure short point). At best, each of these pictures gives a limited view of this ubiquitous particle. bunches with very low charge For decades following Rutherford’s 1919 discovery (p27), Colourful Artistic depiction of the proton’s complexity. the proton was considered elementary. But ever since exper- iments at SLAC started firing electrons into protons in the and, increasingly, in driving medical imaging and advanced 1960s, revealing the existence of point-like scattering cen- cancer treatments. Resolution down to 10 fC tres, and those at DESY uncovered the gluon in 1979, deep- inelastic-scattering experiments have revealed a complex Change of flavour internal picture. In short, what a proton looks like depends Flavour physics is another theme of this issue, and was a focus on how hard – and with what – you hit it. In this issue (p38), of discussions during the electroweak session of the 2019 Ren- Amanda Cooper-Sarkar gives an expert tour of our evolving contres de Moriond (p19). A stand-out new result was LHCb’s picture of the proton, and argues that a deeper understanding observation of CP violation in the charm sector (p7), and the is key to the search for new physics. collaboration also released an eagerly awaited update of the ratio

Surprisingly, on its centenary, there is still much to learn RK based on Run 2 data which leaves the interesting picture of about the proton: the origin of its spin (p39); whether or not it b-decay anomalies poised at the same statistical significance, decays on long timescales (p40); and the puzzling, although despite new data (p9). Updated with the latest results from soon-to-be resolved, value of its radius, as we report on p41. experiment, our feature by theorists Jure Zupan and Jorge Martin Meanwhile, ultra-precise experiments comparing protons with pulls the big picture together (p33). Complementary to these CWCT & BCM-CW , discovered in 1955, continue apace at experiments c h a l le nge s to le pton-fl avou r u n ive r s a l it y, t he M EG-II c ol l a b- such as BASE at CERN’s Decelerator. Recently, for a oration describes an upcoming run to search for an ultra-rare short period, BASE’s measurement of the magnetic moment of muon decay that violates lepton-number conservation (p45). Developped to measure the average the antiproton with a relative precision of 1.5 parts per billion Also in this issue, read about LHCb’s discovery of a new r e pr e s e nt e d t h e fi r s t t i m e t h a t a nt i m a t t e r h a d b e e n m e asured pentquark (p15), DESY’s plans to expand its astroparticle physics Flavour beam current of CW beams or macropulses more precisely than . So far, no differences between activities (p51), news from Japan on the International Linear physics is the proton and the antiproton have been seen. What is beyond Collider (p8), the increasing importance of intergovernmental another theme doubt, however, is the continuing importance of the proton in organisations in science (p49), and the first-ever images of of t h i s i ssue allowing physicists to probe nature’s smallest constituents the centre of a galaxy (p10). Enjoy! Resolution down to 1 uA Reporting on international high-energy physics

CERN Courier is distributed Editor Laboratory INFN Antonella Varaschin SLAC National Accelerator Production editor advertising); e-mail to governments, institutes Matthew Chalmers correspondents: Jefferson Laboratory Laboratory Melinda Baker Ruth Leopold [email protected] and laboratories affiliated Associate editor Argonne National Kandice Carter SNOLAB Technical illustrator with CERN, and to Mark Rayner Laboratory Tom LeCompte JINR Dubna B Starchenko Samantha Kuula Alison Tovey General distribution individual subscribers. A rchive contributor Brookhaven National KEK National Laboratory TRIUMF Laboratory Advertising sales Courrier Adressage, It is published six times Peggie Rimmer Laboratory Achim Franz Hajime Hikino Marcello Pavan Tom Houlden CERN, 1211 Geneva 23, per year. The views Astrowatch contributor Cornell University Lawrence Berkeley Recruitment sales ; e-mail expressed are not Merlin Kole D G Cassel Laboratory Spencer Klein Produced for CERN by Chris Thomas courrier-adressage@ necessarily those of the E-mail DESY Laboratory Los Alamos National Lab IOP Publishing Ltd Advertisement .ch Visit www.bergoz.com CERN management. [email protected] Till Mundzeck Raja n Gupt a Temple Circus, Temple production Kat ie Gr a ha m Enrico Fermi Centre NCSL Ken Kingery Way, Bristol BS1 6HG, UK Marketing and Published by CERN, 1211 Advisory board Guido Piragino Nikhef Robert Fleischer Tel +44 (0)117 929 7481 circulation Geneva 23, Switzerland DISTRIBUTORS MANUFACTURER , Fermilab Kurt Novosibirsk Institute Angela Gage, Tel +41 (0) 22 767 61 11 Christine Sutton, Riesselmann S Eidelman Head of B2B and Laura Gillham Claude Amsler, Forschungszentrum Orsay Laboratory journalism Jo Allen Printed by Warners U.S.A.: GMW Associates India: GEEBEE International BERGOZ Instrumentation Philippe Bloch, Jülich Markus Buescher Anne-Marie Lutz B2B commercial Advertising (Midlands) plc, Bourne, Roger Forty, GSI Darmstadt I Peter PSI Laboratory P-R Kettle operations manager Tel +44 (0)117 930 1026 Lincolnshire, UK www.gmw.com www.geebeeinternational.com www.bergoz.com Mike Lamont, IHEP, Beijing Lijun Guo Saclay Laboratory Ed Jost (for UK/Europe display [email protected] [email protected] Espace Allondon Ouest Matthew Mccullough IHEP, Serpukhov Elisabeth Locci Art director advertising) or +44 (0)117 © 2019 CERN 01630 Saint Genis Pouilly, France Yu Ryabov UK STFC Jane Binks Andrew Giaquinto 930 1164 (for recruitment ISSN 0304-288X Japan: Hayashi-Repic China: Beijing Conveyi Limited [email protected] www.h-repic.co.jp www.conveyi.com [email protected] [email protected] CERN COURIER MAY/JUNE 2019 5

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CP violation LHCb observes CP violation in charm decays CERN-PHOTO-201812-329-16 On the morning of 21 March, at the 2019 Rencontres de Moriond in La Thuile, Italy, the LHCb collaboration announced the discovery of charge-parity (CP) viola- tion in the charm system. Met with an impromptu champagne celebration, the result represents a milestone in and opens a new area of inves- tigation in the charm sector. CP violation, which results in differ- ences in the properties of matter and anti- m a t t e r, w a s fi r s t o b s e r v e d i n t h e d e c a y sof K (which contain strange quarks) in 1964 by James Cronin and Val Fitch. Even though parity (P) violation had been seen eight years earlier, the discovery that the combined C and P symmetries are not conserved was unexpected. The story deepened in the early 1970s, when, building on the foundations laid by Nicola Experimental highlight The LHCb detector in December being prepared for upgrades. Cabibbo and others, Makoto Kobayashi L Fayard L and Toshihide Maskawa showed that CP violation observed in the SM is only able violation could be included naturally in to explain a fraction of the imbalance. In the (SM) if at least six addition to hunting for novel sources of CP d i ffe re nt qua r k s e x i s te d i n n at u re. The i r violation, physicists are making precise fundamental idea – whereby direct CP measurements of known sources to look violation arises if a complex phase appears for deviations that could indicate physics in the CKM matrix describing quark mix- beyond the SM. The SM prediction for the i n g – w a s c o n fi r m e d 30 y e a r s l a t e r b y the amount of CP violation in charm decays is discovery of CP violation in B-meson estimated to be in the range of 10-4 – 10-3 decays by the BaBar and Belle collabo- in the decay modes of interest. The new rations. Despite decades of searches, CP LHCb measurement is consistent with the violation in the decays of charmed par- SM expectation but falls at the upper end ticles escaped detection. Champagne “This is a major result that could be of the range, generating much discussion LHCb physicists used the unprece- moment Members obtained thanks to the very high charm- at Moriond 2019. Unusually for particle dented dataset accumulated in 2011–2018 of the LHCb production cross section at LHC, and to physics, the experimental measurement to study the difference in decay rates collaboration who the superb performance of both the LHC is much more precise than the SM pre- – between D0 and D0 (which contain a c were present at the machine and the LHCb detector, which diction. This is due to the lightness of quark or antiquark) decaying into K+K– announcement. provided the largest sample of charm charm quarks, which means that reliable or π+π- pairs. To differentiate between ever collected,” says LHCb perturbative QCD and other approximate – the identical D0 and D0 decays, the col- s p o k e s p e r s o n G i o v a n n i P a s s a l e v a. “A n a- calculation techniques are not possible. l a b or a t io n e x pl oit e d t w o d i ffe r e nt c l a s s e s lysing the tens of millions of D0 mesons Future theoretical improvements, and of decays: those of D*+/- mesons decaying needed for such a precise measurement data, will establish whether the seminal into a D0 and a charged , where the was a remarkable collective effort by LHCb result is consistent with the SM. pr e s e n c e o f a π+(π-) indicates the presence the collaboration. The result opens up a “This is an important milestone in the – of a D0(D0) meson; and those of B mesons new field in particle physics, involving study of CP violation,” Kobayashi, now decaying into a D0, a muon and a neutrino, the study of CP-violating effects in the professor emeritus at KEK in Japan, tells in which the presence of a μ+(μ-) i d e nt i fie s sector of up-type quarks and searches CERN Courier. “I hope that analysis of the – a D0(D0). Counting the number of decays for new-physics effects in a completely results will provide a clue to new physics.” present in the data sample, the final result new domain.”

is ΔACP= -0.154±0.029%. At 5.3 standard CP violation is a thought to be an Further reading deviations from zero, it represents the essential ingredient to explain the LHCb Collaboration 2019 first observation of CP violation in the observed cosmological matter-anti- arXiv:1903.08726 (submitted to Phys. Rev. charm system. matter asymmetry, but the level of CP Lett.).

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Facilities lepton flAvour universAlity Physicists digest Japan’s ILC statement Flavour anomalies continue to intrigue R Hori/KEK R PNPOEXP-2018-004-1 X OPEN-PHO-E 2 The Japanese government has put on hold ration (which coordinates planning and The LHCb collaboration has released a dependence of RK on q . Other experi- a decision about hosting the International research for the ILC and CERN’s Compact much anticipated update on its meas- ments also showed new measurements

Linear Collider (ILC), to the disappoint- Linear Collider, CLIC), remains upbeat: urement of RK – a ratio that describes of lepton universality and other related ment of many hoping for clarity ahead of “We did not get the green light we hoped how often a B+ meson decays to a charged tests of the Standard Model, such as + - + - + - the update of the European strategy for for. Ne v e r t h e l e s s, t h e r e w a s a s i g n i fic a nt and either a μ μ or an e e pair, and ATLAS on the branching ration of Bs→μ μ

particle physics. At a meeting in Tokyo on step forward with a strong political state- therefore provides a powerful test of lep- and an update from Belle on both RD(*) and

6-7 March, Japan’s Ministry of Education, m e nt a n d, for t h e fi r s t t i m e, a d e c l a r a t io n ton universality. The more precise meas- RK*. The current experimental activity in Culture, Sports, Science and Technology of interest in further discussions by a urement, officially revealed at Rencontres flavour physics was reflected by several (MEXT) announced, with input from senior member of the executive. We will de Moriond on 22 March, suggests that talks at Moriond from theorists. the Science Council of Japan (SCJ), that Machine in limbo else in the world where the project can continue to push hard.” t h e i nt r i g u i n g c u r r e nt pi c t u r e o f fl a v o u r “It’s not a discovery, but something it has “not yet reached declaration” for The ILC would be taken up.” Japan’s statement has also been widely anomalies persists. is going on,” says David Straub of TUM hosting the ILC at this time. A statement collide electrons The story of the ILC, an - interpreted as a polite way for the gov- Since 2013, several results involving Munich, who had spent the previous 24 from MEXT continued: “The ILC project and at an positron collider that would serve as a ernment to say “no” to the ILC. “The the decay of b quarks have hinted at hours working solid to update a global +0.060 +0.016 requires further discussion in formal aca- energy of 250 GeV, Higgs factory, goes back more than 15 reality is that it is naturally difficult for deviations from lepton universality, a Deviations found RK = 0.846-0.054 (stat) -0.014 (syst), the likelihood fit of all parameters relevant demic decision-making processes such with the possibility years. In 2012, physicists in Japan sub- people outside the machinery of any tenet of the Standard Model (SM), though The decay of a B 0 most precise measurement to date. How- to the b anomalies with the updated as the SCJ Master Plan, where it has to of energy upgrades. mitted a petition to the Japanese gov- national administration to understand n o n e i s i n d i v i d u a l l y s i g n i fic a nt e n o u g h t o meson into a K*0 and ever, having shifted closer to the Stand- LHCb and Belle results. The fit, which be clarified whether the ILC project can ernment to host the project. A technical fully how procedures operate, and this is constitute evidence of new physics. LHCb an e+e- pair, used to ard Model prediction, the value leaves the involves 265 observables showed that b + - gain understanding and support from the design report was published the follow- certainly true of the rest of the world with has studied a number of ratios comparing test lepton overall significance unchanged at about → s l l observables such as RK continue to domestic academic community… MEXT ing year. In 2017, the original ILC design regard to what is truly happening with b-decays to different and also universality in the 2.5 standard deviations. show a “large pull” towards new-physics. will continue to discuss the ILC project was revised to reduce its centre-of-mass ILC in Japan,” says Phil Burrows of the sees signs that something is amiss in Standard Model, “I cannot tell you if lepton-flavour “The popular ‘U1 leptoquark’ is still giv- with other governments while having an energy by half, shortening it by around a University of Oxford, who is spokesper- a n g u l a r d i s t r i b ut io n s o f B→K *μ+μ- decays. recorded by LHCb. universality is broken or not, so sorry for ing excellent fit to the data”, says Straub. interest in the ILC project.” third and reducing its cost by up to 40% son for the CLIC accelerator collaboration. Data from BaBar and Belle add further this!” said Thibaud Humair of Imperial Further reduction in the uncertainty

The keenly awaited announcement (CERN Courier January/February 2018 p7). A full spectrum of views was expressed intrigue, though with lower statistical College London, who presented the result on RK can be expected when the data was made during the 83rd meeting of Meanwhile, MEXT has been weighing at a meeting of the linear-collider com- significances. on behalf of the LHCb collaboration. “All collected by LHCb in 2017 and 2018 are

the International Committee for Future up the ILC project in terms of its scientific munity in Lausanne, Switzerland, on 8-9 The latest measurement from LHCb is LHCb results for RK are below SM expec- included in a future analysis. Meanwhile, + - Accelerators (ICFA) at the University of significance, technical challenges, cost April, with around 100 people present. the first lepton-universality test per- tations. Together with b → sμ μ results, RK in Japan, the Belle II physics programme

To k y o. D u r i n g a pr e s s br i e fi n g, IC FA c h a i r and other factors. In December 2018, the “The global community represented formed using part of the 13 TeV Run 2 and RK* constitute an interesting pattern has now begun in earnest and the col- Geoffrey Taylor emphasised that SCJ submitted a critical report to MEXT at the Lausanne meeting restated the data set (2015–2016) together with the o f a n o m a l i e s, b ut t h e s i g n i fic a n c e i s s t i l laboration is expected to bring further are long-term projects. “At the last strat- highlighting perceived issues with the overwhelming physics case for an full Run 1 data sample, representing in low,” he said. statistical power to the b-anomaly ques- egy update in 2013 the ILC was seen as an project, including its cost and interna- electron–positron collider to make pre- total an integrated luminosity of 5fb-1. Humair’s talk generated much discus- tion in the near future. important development in the field, and tional organisation. Asked at the March cision measurements in the Higgs and The blinded analysis was performed in sion, with physicists pressing LHCb on w e w e r e h o pi n g t h e r e w o u l d b e a d e fi n it e pr e s s br i e fi n g w h y t h e S C J s h o u l d n owbe top-quark sectors, with superb sensitiv- the range 1.1

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The quality of the accelerated electron T he fie ld of In addition to laser-driven schemes, October 2018 p7). CERN beam is determined by how background plasma particle-driven plasma acceleration Experiments at Berkeley in the next plasma electrons are trapped in the wakefield holds promise for high-energy phys- few years will focus on demonstrating the accelerating and focusing “bucket” of the ics applications. Experiments using staging of laser-plasma accelerators with Welcome to the Science Gateway acceleration is pl a s m a w a v e. S e v e r a l d i ffe r e nt m e t h o d s electron-beam drivers are ongoing and multi-GeV energy gains. “The field of CERN-PHOTO-201904-083-1 of initiating electron trapping have been picking up planned at various facilities including plasma wakefield acceleration is picking On 8 April, CERN unveiled plans for a proposed to improve the beam emittance speed FLASHForward at DESY and FACET-II up speed,” writes Florian Grüner of the major new facility for scientific education and brightness significantly beyond at SLAC (CERN Courier January/February University of Hamburg in an accompa- and outreach. Aimed at audiences of all state-of-the-art particle sources, rep- 2019 p10). The need for staging multiple nying APS Viewpoint article. “If plasma ages, the Science Gateway will include resenting an important area of research. plasma accelerators may even be circum- w a k e fie l d s c a n h a v e g r a d i e nt sof1 TV/m, exhibition spaces, hands-on scientific Another challenge, says Gonsalves, is to vented by using energetic proton beams one might imagine that a ‘table-top ver- experiments for schoolchildren and improve the stability and reproducibility as drivers. Recent experiments at CERN’s sion of CERN’ is possible.” students, and a large amphitheatre to of the accelerated electron beams, which A d v a n c e d Wa k e fie l d E x p e r i m e nt d e m on- host science events for experts and non- are currently limited by fluctuations in strated electron acceleration gradients of Further reading experts alike. It is intended to satisfy the laser systems caused by air and around 200 MV/m using proton-beam- A Gonsalves et al. 2019 Phys. Rev. Lett. 122 the curiosity of hundreds of thousands ground motion. driven plasma wakefields CERN( Courier 084801. visitors every year and is core to CERN’s mission to educate and engage the public AstrowAtch: supermAssive blAck holes in science. “We will be able to share with every- First images of the centre of a galaxy body the fascination of exploring and learning how matter and the universe work, the advanced technologies we need EHT collaboration EHT On 10 April, researchers working on the different locations on Earth (induced by to develop in order to build our ambitious Event Horizon Telescope – a network of t h e d i ffe r e n c e i n t r a v e l p a t h), f r o m w hic instruments and their impact on soci- eight radio dishes that creates an Earth- it is possible to reconstruct an image on ety, and how science can influence our s i z e d i nt e r fe r o m e t e r – r e l e a s e d t h e fi r s t the sky. This does not only require a large daily life,” says CERN director-general, direct image of a black hole. The land- coordination between many telescopes . “I am deeply grateful mark result, which shows the radiation around the world, but also very precise to the donors for their crucial support in emitted by superheated gas orbiting the timing, vast amounts of collected data t h e f u l fi l m e nt o f t h i s b e a ut i f u l pr oj ect.” Connecting An impression of the Science Gateway looking down Route de Meyrin towards Geneva (top) and a event horizon of a super massive black and enormous computing power. The overall cost of the Science Gate- scale model of the facility (below). hole in a nearby galaxy, opens a brand Despite the considerable difficulties, the way, estimated at 79 m Swiss Francs, CERN-PHOTO-201904-083-18 new window on these incredible objects. Event Horizon Telescope project used this is entirely funded through donations. The Science Gateway will be hosted in Super massive black holes (SMBHs) are technique to produce the first image of an Almost three quarters of the cost has iconic buildings with a 7000 m2 footprint, thought to occupy the centre of most gal- SMBH using an observation time of only already been secured, thanks in par- linking CERN’s Meyrin site and the Globe axies, including our own, with masses tens of minutes. The imaged SMBH lies Dark secrets a deeper understanding. For example, the ticular to a contribution of 45 m Swiss of Science and Innovation. It is being up to billions of solar masses and sizes at the centre of the supergiant elliptical The black hole’s combined data constrain the SMBH mass Francs from Fiat Chrysler Automobiles. designed by renowned architects Renzo up to 10 times larger than our solar sys- galaxy Messier 87, which is located in the event horizon is to 6.5 billion solar masses and appears Other donors include a private foun- Piano Building Workshop and intends tem. Discovered in the 1960s via radio Virgo constellation at a distance of around around 2.5 times to exclude a non-spinning black hole. dation in Geneva and Loterie Romande, to “celebrate the inventiveness and cre- and optical measurements, their origin, 50 million light years. Although relatively smaller than the Whether the matter orbiting the SMBH which distributes its profits to public ativity that characterise the world of as well as their nature and surrounding close in astronomical terms, its very large shadow (orange) it rotates in the same direction or opposite utility projects. CERN is looking for research and engineering”. Construc- environments, remain important open mass makes its size on the sky compa- casts and measures to the black hole, as well as details on additional donations to cover the full tion is planned to start in 2020 and be issues within astrophysics. Spatially rable to that of the much lighter SMBH just under 40 billion the environment around it, will require cost of the project. completed in 2022. resolved images of an SMBH and the in the centre of our galaxy. Furthermore, kilometres across additional studies. Such studies can also E -H O-201809-216-26 T N-PHO CER potential accretion disks around them its accretion rate (brightness) is variable – large enough to potentially exclude alternative interpre- CERN ticle colliders – FCC and CLIC – both form vital input, but producing such on longer time scales, making it easier to contain the entire tations of this object; currently, exotic Serbia becomes of which are potentially new flagship images is extremely challenging. image. The resulting image (above) shows solar system. objects like stars, gravastars and projects at CERN. SMBHs are relatively bright in radio the clear shadow of the black hole in the wormholes cannot be fully excluded. CERN Member State Serbia was an Associate Member in the wavelengths. However, since the imag- centre surrounded by an asymmetric ring The work of the Event Horizon Tel- pre-stage to membership from March ing resolution achievable with a telescope caused by radio waves that are bent around escope collaboration, which involves Serbia became the 23rd Member State of 2012. As a Member State, Serbia will scales with the wavelength (which is long the SMBH by its strong gravitational field. more than 200 researchers worldwide, CERN, on 24 March, following receipt of have voting rights in the CERN Council, in the radio range) and scales inversely The asymmetry is likely a result of relativ- was published in six consecutive papers for m a l n o t i fic a t i o n f r o m U N E S C O. Ev er while the new status will also enhance with the telescope diameter, it is diffi- istic beaming of part of the disk of matter in The Astrophysical Journal Letters. While since the early days of CERN (former the recruitment opportunities for Serbian cult to obtain useful images in the radio which moves towards Earth. more images at shorter wavelengths are Yugoslavia was one of the 12 founding nationals at CERN and for Serbian indus- region. For example, producing an image The team compared the image to a foreseen in the future, the collaboration Member States of CERN in 1954, until its try to bid for CERN contracts. “Invest- with the same resolution as the optical range of detailed simulations in which also points out that much can be learned d e p a r t u r e i n 1961), t h e S e r bi a n s c ie nt i fic Expanding family Ana Brnabić, Prime Minister of the Republic of ing in scientific research is important Hubble Space Telescope would require parameters such as the black hole’s mass, by combining the data with that from community has made strong contribu- Serbia, talking with CERN director-general Fabiola Gianotti during for the development of our economy a km-wide telescope, while obtaining spin and orientation were varied. Addi- other wavelengths, such as gamma-rays. tions to CERN’s projects. This includes a visit of the Serbian delegation to CERN in September 2018. and CERN is one of the most important a resolution that would allow an SMBH tionally, the characteristics of the matter Despite this first image being ground- at the Synchrocyclotron, Proton Syn- scientific institutions today,” says Ana to be imaged, would require a telescope around the SMBH, mainly hot electrons breaking, it is likely only the start of a chrotron and Super ATLAS and CMS experiments at the LHC, Brnabić, Prime Minister of Serbia. “I diameter of thousands of kilometres. One and ions, as well as the magnetic field revolution in our understanding of black facilities. In the 1980s and 1990s, physi- in the Worldwide LHC Computing Grid, This will am immensely proud that Serbia has way around this is to use interferometry to properties were varied. While the image holes and, with it, the universe. cists from Serbia worked on the DELPHI as well as in the ACE and NA61 experi- bring new become a fully-fledged CERN Member t u r n m a ny te le s c op e s d i s he s at d i ffe re nt alone does not allow researchers to con- experiment at CERN’s LEP collider. In ments. Serbia’s main involvement with State. This will bring new possibilities locations into one large telescope. Such strain many of these parameters, com- Further reading 2001, CERN and Serbia concluded an CERN today is in the ATLAS and CMS possibilities for our scientists and industry to work in an interferometer measures the differ- bining it with X-ray data taken by the Event Horizon Telescope Collaboration International Cooperation Agreement, experiments, in the ISOLDE facility, for our cooperation with CERN and fellow CERN ences in arrival time of one radio wave at Chandra and NuSTAR telescopes enables 2019 ApJL 875 L1—L6. leading to Serbia’s participation in the and on design studies for future par- scientists Member States.”

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FASER approved for LHC ments of the expansion history of subject later this month, when

Belle II Belle On 5 March, CERN approved FASER, the universe, may allow the first results of its search for missing the Forward Search Experiment, direct detection of the sum of the energy in bremsstrahlung radia- which will look for light and weakly neutrino masses at 3σ s i g n i fic a n c e. tion will be released. intensified interacting long-lived parti- cles produced parallel to the LHC Squeezing rare kaon decays Ground breaking at PIP-II beam at solid angles that cannot The KOTO experiment at Japan’s On 15 March, international partners be instrumented by conventional J-PARC laboratory in Tokai has from France, India, Italy and the collider detectors. Located 480 m published a 90% confidence limit UK joined US dignitaries to break Celebrating first collisions with the along a tangent from the ATLAS of 3.0×10−9 on the branching ratio for ground for a new 215 m-long lin- 0 - full Belle II detector. detector, in an unused service the rare neutral kaon decay KL→π νν, ear accelerator at Fermilab. Part of tunnel, the core detector will be a beating the previous world best by the laboratory’s Proton Improve- sCMOS Data taking begins at Belle II 5.5 m-long cylinder with a diameter an order of magnitude (PRL 122 ment Plan II (PIP-II), this will be The fully instrumented Belle II of only 20 cm, as the sought-after 021802). The experiment, whose the first US accelerator assembled the new intensified detector recorded its first colli- new particles (such as dark pho- name derives from “K0 at Tok a i”, from internationally built com- sions on 25 March. Belle II will tons) would remain tightly colli- uses collisions of 30 GeV protons ponents and the new first stage pco.dicam C1 with 16 bit dynamic range observe events at SuperKEKB, mated after being produced at the with a gold target; secondary of the accelerator chain that will a new asymmetric electron- interaction point. FASER will use then travel 20 m before their decays send a neutrino beam 1300 km to the positron collider in Tsukuba, Japan, spare parts donated by the ATLAS are observed in a 6 m-long vacuum liquid-argon based DUNE detec- which plans to achieve a 40-fold and LHCb experiments and is sup- vessel. The main background – tor in Lead, South Dakota. DOE increase on the luminosity of its ported by the Heising-Simons and clusters induced by the con- Under Secretary for Science Paul predecessor, KEKB, which ran Simons foundations. Working to an tamination of in the beam Dabbar says, “I’m excited for the from 1999 to 2010. To cope with ambitious schedule, the experiment – was eliminated by cuts on the further cooperation between the increased intensity, Belle has will begin operating in 2021 after vertex position and the transverse America’s premier particle phys- been upgraded with a silicon ver- the end of the second long shutdown momentum of the neutral pion, and ics and accelerator laboratory and tex detector that consists of a two- of the LHC. the collaboration is now analysing its international partners, and the exposure time 4 ns layer pixel detector and a four-layer the larger 2016–2018 dataset. Mean- resulting better understanding of with 25 mm intensifier double-sided silicon-strip detec- First light for DESI while, NA62 at CERN is working on the universe”.

tor. It will observe large quantities On 1 April, the Dark Energy Spec- a comparable measurement of the FNAL of B-meson pairs, allowing a broad troscopic Instrument (DESI) at the rare charged kaon decay K+→π+νν-, range of high-precision measure- Kitt Peak National Laboratory near to extract a 10% measurement of

ments in flavour physics. Tucson, Arizona, demonstrated the the CKM parameter |Vtd|. precise focusing and alignment P2O targets Mediterranean Sea of its lens assembly – a notable No dark in NA62 Almost 100 authors from institutes achievement as the entire mov- The NA62 experiment at CERN 104 fps in Europe, Australia and Morocco ing mass of the Mayall telescope has set the tightest limit to date have submitted a letter of intent which houses DESI is 375 tons, and on the existence of dark photons A uniquely international US @ full resolution to send a neutrino beam 2595 km the telescope must target objects in the mass range 60 to 110 MeV, accelerator. from the Protvino accelerator facil- with 5 μm accuracy. Having first using just 1% of its expected data- ity near Moscow to the KM3NeT/ trained its gaze on the Whirlpool set (arXiv 1903.08767). Hypothet- Unnatural cross-fertilisation ORCA detector, which is under Galaxy (pictured), DESI will even- ical dark-sector physics could Complex-system-modelling expert construction in the Mediterra- tually collect 360 to 980 nm spec- have an equally rich structure as Sauro Succi of the Italian Institute nean Sea, 40 km from the coast of trographs rather than large images, the Standard Model, and the dark- of Technology, Rome, and Harvard, Toulon, France (arXiv 1902.06083). thereby probing redshifts up to 1.7 photon vector field is one possi- has answered CERN theory chief enhanced The unusually long baseline of the for emission-line galaxies and up to ble extension that could mix with Gian Giudice’s call for interdis- extinction ratio gating “P2O” proposal would allow an 3.5 for Lyman-α spectra of quasars. the photon in an analogous way ciplinarity in understanding the unparalleled sensitivity to matter DESI’s focal plane will be installed to neutrino oscillations. NA62, current challenges to the princi- effects in the Earth: such matter later this year, paving the way for an experiment primarily geared ple of naturalness in high-energy effects distinguish electron-type five years of measurements that, to searching for rare kaon decays, physics (HEP). Succi’s “modest intensified sCMOS technology and antineutrinos via in addition to precise measure- has employed a different technique tentative” (Eur. Phys. J. Plus 2019 134 2048 x 2048 pixel charged current interactions with to most searches by making use of 97) explores two areas of physics atomic electrons, allowing for the DESI its supply of neutral from which exhibit the hallmarks of un- determination of the neutrino mass kaon decays. The pions decay to naturalness: fluid turbulence and hierarchy after a few years of oper- two photons, one of which could the ground state of quantum many- ations. However, say the authors, almost immediately “oscillate” into body . According to Succi, with a significant densification of the a and decay to invisible these are likely to offer “stimu- ORCA detector would be required to dark-sector particles. Meanwhile, lating opportunities for cross- make a competitive measurement neighbouring experiment NA64 is fertilisation between HEP and the of leptonic CP violation. DESI captures the Whirlpool Galaxy. expected to also weigh in on the physics of complex systems”. interface pco.de

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CCMayJun19_NewsDigest_v3.indd 13 17/04/2019 09:26 CERNCOURIER www. V o l u m e 5 9 N u m b e r 3 M a y /J u n e 2 0 1 9 Excellence in precision CERNCOURIER.COM ENERGY solutions for particle FRONTIERS accelerators Reports from the experiments Visit us at IPAC19 in LHCb Melbourne Booth G18 Whether your challenges lie in ❙ Elementary partical research New pentaquarks resolved by LHCb ❙ Particle therepy applications

❙ Material characterization + The LHCb collaboration has discovered broad Pc(4380) were reported, both with – a new pentaquark particle, dubbed the + 0 + *0 m i n i ma l qua rk content of cc uud (CERN + Σ cD Σ cD or in providing service in fields such as Pc(4312) , decaying to a J/ψ and a pro- Courier September 2015 p5). ❙ High-energy particle acceleration ton, with a statistical significance of data The new results use the data collected 7.3 standard deviations. The LHCb data, 1200 total fit at LHCb in Run 1 and Run 2, provid- ❙ Precise beam forming and monitoring LHCb background 0 fi r s t pr e s e nt e d a t R e n c o nt r e s d e M or iond ing a Λb sample nine times larger than ❙ Reliable and safe particle storage + i n M a r c h, a l s o c o n fi r m t h a t t h eP c(4450) 1000 that used in the 2015 paper. The new structure previously reported by the col- data reproduce the parameters of the With our expertise in high energy RF signal generation, laboration in 2015 has now been resolved P (4450)+ and P (4380)+ states when ana- ¸THx9 Amplifier 800 c c signal amplification and state-of-the-art test and into two narrow, overlapping peaks, the l y s e d t h e s a m e w a y a s b e for e. Ho w e v e r, (4440)+ and P (4457)+, with a statistical measurement solutions, Rohde & Schwarz is your ideal Pc c the much larger dataset makes a more s i g n i fic a nc e o f 5.4 s t a n d a rd d e v i at ion s 600 fi n e-g r a i n e d a n a l y s i s p o s s i bl e, r e veal- long term partner. c o m p a r e d t o t h e s i n g l e-p e a k h y p o t h e s i s ing additional peaking structures in the (fi g u r e 1). To g e t h e r, t h e r e s u l t s o ffe r rich 400 J/ψ-p i n v a r i a nt m a s s s p e c t r u m t h a t w e r e P (4440)+ P (4457)+ weighted candidates/(2 MeV) c c www.rohde-schwarz.com/particle-accelerators studies of the strong internal dynamics + not visible before. A new narrow peak, Pc (4312) of e xot ic . 200 with a width comparable to the mass R&S®RTO digital In the famous 1964 papers that set resolution, is observed near 4312 MeV, + -0 D threshold. The oscilloscope o ut t h e q u a r k m o d e l, M u r r a y G e l l-M a n n right below the Σ c and George Zweig mentioned the pos- 0 structure seen before at 4450 MeV has sibility of adding a quark–antiquark 4200 4250 4300 4350 4400 4450 4500 4550 4600 been resolved into two narrower peaks, pair to the minimal meson and bar yon mJ/ψp [MeV] at 4440 and 4457 MeV. The latter is right – +-*0 states qq and qqq, thereby proposing at the ΣcD threshold. –– – the new configurations qqqq and qqqqq. Fig. 1. The LHCb collaboration has discovered a new pentaquark, These Pc s t ate s joi n a g ro w i n g f a m i ly Ne a rl y fo u r d e c a d e s l a t e r, t h e B e l l e c ol- and resolved a previously discovered peak into two. The of narrow exotic hadrons with masses 0 − R&S®FSWP Phase noise laboration discovered the surprisingly Λb → J/ψpK data sample was fitted with three narrow resonances near hadron–hadron thresholds. This narrow X(3872) state with a mass very (blue, purple and cyan) plus a polynomial background. i s e x p e c t e d i n c e r t a i n m o d e l s o f l o o s e l y analyzer and VCO tester – close to the D0D*0 threshold, hinting at b o u n d “m ol e c u l a r” s t a t e s w h o s e s t r u c- a structure (cc–uu–). A decade must instead be a combination such as ture resembles the way a proton and 0,± – – after that, Belle discovered narrow Z b ccud. There is also evidence for broad neut ron bi nd to for m a deuteron. O t her –* *–* ± s t a t e s j u s t a b o v e t h e BB a n d B B thresh- Z c states from Belle and LHCb, such as models, such as of tightly bound pen- ± ol d s; t h i s w a s fol l o w e d b y o b s e r v a t io n s t he Z c(4430) . t a q u a r k s, c o u l d a l s o e x pl a i n t h e P c reso- 0,± of Z c states just above the equivalent A m aj or t u r n i n g p oi nt i n e x o t i c b a r y o n n a n c e s. A m or e c o m pl e t e u n d e r s t a n d i n g c h a r m t h re s hold s b y BE S-III a nd B e l le. spectroscopy was achieved by LHCb in will require further experimental and ± ± T h e e x i s t e n c e o f c h a r g e d Z b a n d Z c part- Ju ly 2015 w he n, b a s e d on a n a n a ly si s of theoretical investigation. ners makes the exotic nature of these Run 1 data, the collaboration reported states clear: they cannot be described as significant pentaquark structures in Further reading – – 0 c h a r m o n iu m (c c ) or b o t t o m o n iu m (b b) the J/ψ-p mass distribution in Λb → LHCb Collaboration 2019 arXiv 1904.03947 − + mesons, which are always neutral, but J/ψpK decays. A narrow Pc(4450) and a (submitted to Phys. Rev. Lett.). ALICE

ALICE sheds new light on high-pT suppression

The study of lead–ion collisions at the the nuclear-modification factor RAA, Previous measurements of periph- LHC is a window into the quark–gluon which is the ratio of particle produc- The data show eral collisions revealed less suppres- plasma (QGP), a hot and dense phase tion rate in Pb–Pb collisions to that in a dramatically sion than seen in head-on collisions, but r e m a i n e d s i g n i fic a nt l y b e l o w u n it y. of deconfined quarks and gluons. An proton–proton collisions, scaled for different RAA i m p or t a nt e ffe c t i n h e a v y-i o n c ol l i s i ons the number of binary –nucleon This observation indicates the forma- behaviour in is jet quenching – the suppression of collisions. A measured nuclear modi- tion of a dense and strongly interact- particle production at large transverse fication factor of unity would indicate peripheral i ng s ystem – but it a l so p oses a pu z z le.

momenta (pT) due to energy loss in the the absence of final-state effects such Pb-Pb In p–Pb collisions, no suppression s QGP. This suppression is quantified by as jet quenching. collisions has been observed, even though the

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ENERGY FRONTIERS ENERGY FRONTIERS

d i ffe r e nt i n a f r a m e o f r e fe r e n c e i n w hic jets as coming from either top quarks, the initial particle (a W, Z or H boson, 35.9 fb–1 (13 TeV) H, W or Z bosons, b quarks, light quarks, 0–5% 5–10% 10–15% 15–20% 20–25% Pb–Pb, √s = 5.02 TeV, charged particles, | |< 0.8 1600 NN η or a top quark) is at rest. For example, or g luon s. E ac h e vent i s t hen c l a ssi fie d 25–30% 30–35% 35–40% 40–45% 45–50% 1.0 780 CMS 1.2 1.2 ALICE data, 8 < pT < 20 GeV/c in the centre-of-mass frame of a Higgs 1500 according to how many of each jet type 50–55% 55–60% 60–65% 65–70% 70–75% preliminary HG-PYTHIA, PLB 773 (2017) 408 boson, it would appear as two well- 1400 there are in the event. The number of 75–80% 80–85% 85–90% 90–95% 95–100% 0.8 810 830 NN analysis 1.0 1.0 collimated back-to-back jets of parti- 1300 observed events in each category was cles, whereas in the reference frame of 930 950 890 then compared to the predicted back- 0.6 1200 the CMS detector the jets are no longer ground yield: an excess could indicate 0.8 0.8

B(bW) 1100 b a c k-t o -b a c k a n d m a y i n d e e d b e d i ffi- 1040 1070 1100 1090 T-quark pair production. AA 0.4 R

AA cult to identify as separate at all. This 1000 CMS found no evidence for T-quark R feature, based on special relativity, tells 1200 1200 1210 1230 1230 pair production in the 2016 data, and has 0.6 0.6 0.2 900 us how to distinguish “fat” jets origi- excluded T-quark masses up to 1.4 TeV

800 observed T quark mass limit (GeV) nat ing from different init ial par t icles. 0 1260 1300 1280 1280 1280 1370 (fig u re 1). The col l ab or at ion i s work i ng 0.4 0.4 Modern machine-learning tech- 700 on new ideas to improve the classifi- niques were used to train a deep neural- 0 0.2 0.4 0.6 0.8 1.0 cation method and extend the search 0.2 0.2 network classification algorithm using B(tH) to higher masses using the four-times simulations of the expected particle larger 2017 to 2018 dataset. decays. Several dozen properties of the Fig. 1. Mass limits for T quarks in GeV. The limits are shown as a 0 0 jets were calculated in different hy po- function of the probability to decay to a b quark and a W boson, Further reading 10–1 1 10 0 20 40 60 80 100 thetical reference frames, and fed to the versus the probability to decay to a and a , CMS Collaboration 2018 CMS-PAS-B2G- p (GeV/c) T centrality (%) n e t w or k, w h ic h c l a s s i fie s t h e or i g i n a l f at assuming all other decays are to a top quark and a Z boson. 18-005. ATLAS Fig. 1. Left: nuclear-modification factor versus p T for 5% wide centralit y classes, showing the suppression of high-p T particle production in Pb–Pb collisions. The most peripheral 25% of ion collisions (coloured) exhibit completely different behaviour from the most central 75% (grey). Coloured bars (red) compared with a new model of suppression in peripheral collisions (black). show uncertainty on the normalisation. Right: mean RAA Pushing the limits on

energy densities are similar to those in shows that the suppression mechanism based model that does not implement peripheral Pb–Pb collisions. for peripheral collisions is fundamen- jet-quenching effects, but incorporates Supersymmetry (SUSY) introduces a new Fig. 1. New ∼+ ∼– WW ∼0 ∼0 The ALICE collaboration has recently tally different from that observed in the biases originating from the align- –boson symmetry that gives χ1 χ1 → χ1 χ1 constraints (red) put jet quenching to the test experimen- central collisions, where the suppres- ment of the , yielding quali- rise to supersymmetric “partners” of on a simplified ATLAS preliminary expected limit (±1 σexp) tally by performing a rigorous measure- sion can be explained by parton energy tative agreement above 75% centrality the Standard Model (SM) particles, and 200 –1 SUSY SUSY model √s = 13 TeV, 139 fb observed limit (±1 σtheory) ment of RAA in narrow centrality bins. The loss in the QGP. (fig ure 1, right). “naturally” leads to a light Higgs boson all limits at 95% CL ATLAS 8 TeV, arXiv:1403.5294 describing the r e s u l t s (fi g u r e 1, l e f t) s h o w t h a t t h e t r end In a single Pb–Pb collision several These results demonstrate that with with mass close to that of the W and Z. 160 production of a of a gradual reduction in the suppression nucleons collide. It has recently been the correct treatment of biases from the SUSY partners that are particularly rel- pair of

of high-pT particle production as one suggested that the alignment of each parton–parton interactions the observed evant in these “natural SUSY” scenarios that both 120 0 ) = m(W) moves from the most central collisions nucleon collision plays an important suppression in Pb–Pb collisions is con- are the top and bottom squarks, as well ∼ 1 subsequently decay ) [GeV] 1 1 (corresponding to the 0% centrality r ol e: i f t h e nu c l e o n s a r e a l i g n e d, a s i n g l e sistent with results from p–Pb collisions as the SUSY partners of the weak SM 0 + ) – m(χ to a W boson and the ∼

∼ 1 percentile) to those with a greater collision produces more particles, which at similar multiplicities – an important bosons, the and charginos. 80 m(χ lightest m( χ impact parameter does not continue results in a correlation between particle new insight into the nuclear modifica- Despite the theory’s many appealing – a stable and above a centrality of 75%. Instead, production at low pT, which is used to tion factor in small systems. features, searches for SUSY at the LHC 40 invisible SUSY the data show a dramatically differ- determine the centrality, and at high and elsewhere have so far yielded only particle. The new

ent behaviour: increasingly strong pT, where R AA is measured. The sup- Further reading exclusion limits. With LHC Run 2 com- sensitivity is suppression for the most peripheral col- pression in the peripheral events can ALICE Collaboration 2018 arXiv pleted as of the end of 2018, the ATLAS 0 significantly lisions. The change at 75% centrality be modelled with a simple PYTHIA- 1805.05212 (submitted to Phys. Lett. B). experiment has recorded 139 fb-1 of 100 150 200 250 300 350 400 450 500 improved over that physics-quality proton–proton col- ∼± of the previous m(χ1 ) [GeV] CMS lisions at a centre-of-mass energy of analysis (grey). 13 TeV. Three recent ATLAS SUSY searches Boosting searches for fourth-generation quarks highlight the significant increase in two charged leptons and a significant There remains the detector volume. The observed sensit iv it y offered by t his dataset. amount of missing momentum carried plenty of room results are consistent with the back- The first search took advantage of away by a pair of the lightest SUSY part- ground-only expectation. for discovery Ever since the 1970s, when the third But a loophole arises if the new heavy A loophole themselves, production of a T quark– refinements in b-tagging to search ners. The current search places strong These analyses represent just the in mining the generation of quarks and leptons began quarks do not interact with the Higgs arises if the antiquark pair could lead to dozens for light bottom squarks decaying into constraints on SUSY models with light beginning of a large programme of SUSY to emerge experimentally, physicists of different final states. While most charginos and more than doubles the riches from fie l d i n t h e s a m e w a y a s r e g u l a r q uarks. new heavy bottom quarks, Higgs bosons and the searches using the entirety of the Run-2 have asked if further generations await The search for new heavy fourth- previous searches focused on a handful lightest SUSY partner, which is assumed sensitivity of the previous analysis the LHC dataset. With a rich signature space left discovery. One of the first key results generation quarks – denoted T – is quarks do not of channels at most, this new analy- to be invisible and stable (a candidate (fig ure 1). to explore, there remains plenty of room from the Large Electron–Positron therefore the subject of active research interact with sis is able to search for 126 different for dark matter). The data agree with the A third recent analysis considered less for discovery in mining the riches from Collider 30 years ago provided evidence at the LHC today. the Higgs possibilities at once. SM and lead to significantly improved conventional signatures. Top squarks the LHC. to t he cont r a r y, show i ng t hat t here a re CMS researchers have recently field in the The key to classifying all the vari- constraints, with bottom squark masses – the bosonic SUSY partner of the top only three generations of neutrinos. completed a search for such “vector- same way o u s fi n a l s t a t e s i s t h e a bi l it y t o id e ntify now excluded up to 1.5 TeV. quark – may evade detection if they Further reading The discovery of the Higgs boson in like” quarks using a new machine- h i g h- e n e r g y t o p q u a r k s, H i g g s b o s o n s, If the accessible SUSY particles can have a long lifetime and decay at macro- ATLAS Collaboration 2019 ATLAS-CONF- 2012 added a further wrinkle to the learning method that exploits special and that decay into jets only be produced via electroweak pro- scopic distances from the collision point. 2019-011. story: many theorists believe that the relativity in a novel way. If the new T of particles recorded by the detector. In cesses, the resulting low-production This search looked for SUSY particles ATLAS Collaboration 2019 ATLAS-CONF- mass of the Higgs boson is unnaturally q u a r k s e x i s t, t h e y a r e e x p e c t e d t o d e c a y t h e r e fe r e n c e f r a m e o f t h e C M S d e t e c t or, cross sections present a challenge. decaying to a quark and a muon, look- 2019-008. small if there are additional generations to a quark and a W, Z or Higgs boson. these particles produce wide jets that The second search focuses on such ing primarily for long-lived top squarks ATLAS Collaboration 2019 ATLAS-CONF- s of quarks heavier than the top quark. As top quarks and W/Z/H bosons decay all look alike, but things look very electroweak SUSY signatures with that decayed several millimetres into 2019-006.

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Reports from events, conferences and meetings

RencontRes de MoRiond Standard Model stands strong at Moriond L Fayard L The 66th Rencontres de Moriond, held LHCb continued to enjoy the limelight in La Thuile, Italy, took place from 16 to during Moriond’s QCD session, announc- 30 March, with the first week devoted i n g t h e d i s c o v e r y o f a n e w fi v e- q u a r k h ad- + to electroweak interactions and unified ron, named Pc(4312) , which decays to a theories, and a second week to QCD and proton and a J/ψ and is a lighter companion high-energy interactions. More than of the pentaquark structures revealed by 200 physicists took part, presenting new LHCb in 2015 (p15). The result is expected results from precision Standard Model to motivate deeper studies of the structure (SM) measurements to new exotic quark of these and other exotic hadrons. Another states, flavour physics and the dark sector. powerful way to delve into the depths of A major theme of the electroweak ses- QCD, addressed during the second week of

s i o n w a s fl a v o u r p h y s i c s, a n d t h e s t a rof t h e c o n fe r e n c e, i s v i a t h e B c meson family.

the show was LHCb’s observation of CP Following the observation of the Bc(2S) by violation in charm decays (see p7). The ATLAS in 2014, CMS reported the existence c ol l a b or a t i o n s h o w e d s e v e r a l o t h e r n e w of a two-peak feature in data correspond- * results concerning charm- and B-meson ing to the Bc(2S) and the Bc(2S) – supported decays. One much anticipated result was allowed mass ranges of supersymmet- Mountain by new results from LHCb based on its

an update on RK, the ratio of rare decays ric and other hypothetical particles (see encounters full 2011–2018 data sample. Independ- of a B+ to electrons and , using pp16–17). These also include new limits Flavour physics ent measurements of CP violation in the

data ta ken at energ ies of 7, 8 and 13 TeV. from CMS on the parameters describ- took centre stage at Bs system reported by ATLAS and LHCb These decays are predicted to occur at the ing slowly moving heav y particles, and Moriond this year. during the electroweak session were also same rate to within 1%; previous data col- constraints from both collaborations on combined to yield the most precise meas- lected are consistent with this prediction the production rate of Zʹ bosons. ATLAS, urement yet, which is consistent with the but favour a lower value, and the latest using the results of lead–ion collisions small value predicted by the SM. LHCb results continue to support this t a k e n i n 2018, a l s o r e p or t e d t h e o b s e r v a- picture. Together with other measure- t ion o f l i g ht-b y-l i g ht s c at t e r i n g – a v e r y A charmed life ments, these results paint an intriguing rare process that is forbidden by classical I n t h e h e a v y-i o n a r e n a, A L IC E h i g h l i g ht e d picture of possible new physics (p33) that electrodynamics. its observation that containing w a s e x pl or e d i n s e v e r a l t a l k s b y t h e or i s t s. New results and prospects in the charm quarks are produced more often in neutrino sector were communicated, proton–proton collisions than in electron– Run-2 results including Daya Bay and the reactor positron collisions. Initial measurements The LHC experiments presented many a nt i n e ut r i n o flu x a n o m a l y, s e a r c h e s for in lead–lead collisions suggest an even new results based on data collected neutrinoless double-beta decay, and the higher production rate for charmed bar- during Run 2. ATLAS and CMS have reach of T2K and NOvA in tackling the yons, similar to what has been observed measured most of the Higgs boson’s neutrino mass hierarchy and leptonic for strange baryons. These results indicate main production and decay modes with CP violation. Dark matter, and that the presence of quarks in the collid- h i g h s t a t i s t i c a l s i g n i fic a n c e a n d c a r r i ed cosmology also featured prominently. ing beams affects the hadron production out searches for new, additional Higgs New results from experiments such as rate. The collaboration also presented the bosons. From a combination of all Higgs- XENON1T, ABRACADABRA, SuperCDMS fi r s t m e a s u r e m e nt o f t h e t r i a n g l e-s h a ped boson measurements, ATLAS obtained and ATLAS and CMS illustrate the power flow of J/ψ particles in lead–lead colli- new constraints on the important Higgs of multi-prong dark-matter searches – sions, showing that even heavy quarks self-coupling, while CMS presented not just for WIMPs but also very light are affected by the quarks and gluons in updated results on the Higgs decay to two or exotic candidates. Cosmologist Lisa the quark–gluon plasma and retain some Z bosons and its coupling to top quarks. R a n d a l l g a v e a br o a d-r e a c h i n g t a l k a b o ut memory of the collisions’ initial geometry. Precision SM studies continued with “post-modern cosmology”, in which she The SM still stands strong after Moriond fi r s t e v id e n c e f r o m AT L A S for t h e simul- argued that – as in particle physics – the 2019, a nd t he obser v at ion of CP v iolat ion taneous production of three W or Z bos- easy times are probably over and that in D mesons represents another victory, ons, and CMS presented first evidence astronomers need to look at more subtle The star of concluded Shahram Rahatlou of Sapienza for the production of two W bosons in effects to brea k t he impasse. the show University of Rome in the experimental two simultaneous interactions between Moriond electroweak also introduced a was LHCb’s s u m m a r y. “B ut t h e fl a v o u r a n o m a l y i s s t i l colliding partons. The very large new new session: “feeble interactions”, which there to be pursued at low and high mass.” dataset has also allowed ATLAS and CMS w a s d e s i g n e d t o r e fle c t t h e g r o w i n g i nter- observation of to expand their searches for new phys- est in very weak processes at the LHC and CP violation in Matthew Chalmers CERN, with input ics, setting stronger lower limits on the future experiments. charm decays from the LHC experiment collaborations.

CERN COURIER MAY/JUNE 2019 19

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100th anniversary of the birth of richard feynm an Co-innovation workshop Centennial conference honours Feynman Particle colliders: accelerating innovation

Around 100 researchers, academics and of Liverpool University Higgs boson by extending the range of Nanyang Technological University Singapore University Technological Nanyang 2018 marked the 100th anniversary of industry delegates joined a co-innovation measurable Higgs properties to its total the birth of Richard Feynman. As one workshop in Liverpool, UK, on 22 March width and self-coupling. Moreover, the of several events worldwide celebrat- to discuss the strategic R&D programme combination of superior precision and ing this remarkable figure in physics, for a Future Circular Collider (FCC) and energy reach allows a complementary a memorial conference was held at the a s s o c i a t e d b e n e fit s for i n d u s t r y. M o t i v a t e d mix of indirect and direct probes of new I n s t it ut e o f A d v a n c e d St u d ie s a t Na n y a n g by the FCC study, the aim of the event was physics. For example, FCC-ee would ena- Technological University in Singapore to identify joint R&D opportunities across ble the Higgs couplings to the Z boson from 22 to 24 October, co-chaired by accelerator projects and disciplines. to be measured with an accuracy better L a r s Br i n k, K K P hu a a n d F r a n k W i l z c e k . New particle colliders provide indus- t h a n 0.17 %, w h i l e F C C-h h w i l l d e t e r m i n e The format was one-hour talks with try with powerful test-beds with a high devoted to the benefits of fundamental Constructive m o d e l-i n d e p e n d e nt t t H c o u pl i n g t o <1%. 45 minute discussions. publicity factor. Well-controlled envi- science to society and industry, co-hosted collisions Physics discussions were accompanied Pierre Ramond began the conference ronments allow novel technologies and by the University of Liverpool and CERN Michael Benedikt by a status report of the overall FCC project, with anecdotes from his time as Feyn- processes to be piloted, and SMEs are together with partners from the FCC and discusses FCC’s reviewing the technological challenges for man’s next-door neighbour at Caltech. ideal partners to bring these technol- H2020 EuroCirCol projects, and supported implementation both accelerator and detectors, the project He discussed Feynman the MIT under- Feynman fest cal Feynman about them. He described that foreshadowed many developments ogies – which include superconducting by EU-funded MSCA training net works. plan. implementation strategy, and cost esti- graduate, his first paper and his work at Some of the biggest life in the shadows of the great man as a in nanotechnology. Wilczek concluded magnets, cryogenics, civil engineering, Almost 1000 researchers and industrial- m a t e s. C o n s t r u c t io n o f t h e m or e t e c h n o - Princeton as a graduate student. There, names in physics graduate student at Caltech in the 1960s. t h a t t h e r e i s pl e nt y o f r o o m l e f t i n H i l b e r t d e t e c t or d e v e l o p m e nt, e n e r g y e ffic i e n c y ists from across Europe, including univer- logically ready FCC-ee could start by 2028, Feynman learnt about Dirac’s idea of attended the At that time Feynman wanted to solve space, describing entanglement, quantum and novel materials and material pro- sity and high-school students, took part. delivering first physics beams a decade summing over histories from Herbert memorial event. q u a nt u m g r a v it y, a n d w a s g i v i n g a c o u r s e cryptography, quantum computation and cessing techniques – to maturity. An industry exhibition allowed more than later, right after the end of the HL-LHC Jehle. Jehle asked Feynman about it a on the subject of gravitation. He asked quantum simulations. Quantum com- Short talks about FCC-related areas 60 high-tech companies to showcase their programme. Another important aspect fe w d a y s l a t e r. He s a i d t h a t h e h a d u n d e r- t h e s t u d e nt s t o s u p p o s e t h a t E i n s t e i n h a d puting is the last subject that Feynman for innovation, examples of successful latest products, also serving university of the two-day meeting was the need for s t o o d it a n d h a d d e r i v e d t h e S c h r ö d i n g e r never lived: how would particle physicists worked hard on. Artur Ekert described the technology-transfer projects at CERN, students as a careers fair, and more than further improving theoretical predictions e q u a t io n f r o m it. Fe y n m a n’s a d v i s e r w a s discuss gravity? He quickly explained that famous conference at MIT in 1981 when as well as current and future funding a d o z e n d i ffe r e nt o ut r e a c h a c t i v it i e s w er to match the huge step in experimental John Wheeler. Wheeler was toying with t here must b e a spi n-t wo pa r t ic le me d i- Feynman first talked about the subject. opportunities stimulated interesting av ailable to younger st udents. precision possible at t he FCC. the idea of a single electron travelling ating the force; by the second lecture he H i s p a p e r f r o m t h i s o c c a s i o n “Si m u l a t i n g discussions. Several areas were identi- A separate event, held at CERN on 4 and Pl a n n i n g n o w for a 70-ye a r-lon g pro- b a c k a n d for t h i n t i m e – w e r e y o u t o l o o k had computed t he precession of t he per- Physics with Computers” was the first fie d a s b a s e s for c o -i n n o v a t io n, i n c lu d ing 5 March, reviewed the FCC physics capa- g r a m m e m a y s o u n d a r e m o t e g o a l. Ho w- at a slice of time you would observe many ihelion of Mercury, a juncture that other p a p e r o n q u a nt u m c o m p ut e r s a n d s e t t h e r e s o u r c e- e ffic i e nt t u n n e l l i n g, t h e t r ans- bilities following the publication of the ever, as Alain Blondel of the University of electrons and positrons. After his spell courses took months to arrive at. Zweig g round for t he present developments. fer of bespoke machine-learning tech- FCC conceptual design report in January Geneva remarked in the concluding talk of at Los Alamos, this led Feynman to the recounted that Feynman’s failure to invent niques from particle physics to industry, (CERN Courier Ja nu a r y/ Fe br u a r y 2019 p 8). the conference, the first report on the LHC idea of the , which considers a r e n or m a l i s a bl e t h e or y o f q u a nt u m g r a v- Biology hangout d e t e c t or R& D, c o ol i n g a n d d a t a h a n d l i n g. The FCC study envisages the construction dates back more than 40 years. “Progress propagating backwards it y affected him for many years. Though Feynman was also interested in biology The notes from all the working groups of a new 100 km-circumference tunnel i n k n o w l e d g e h a s n o pr ic e,” h e s a id. “T h e in time as well as particles propagating h e d id n o t s uc c e e d, h i s i n s i g ht s c o nt i nue for a long time. Curtis Callan painted will be used to establish joint funding at CERN hosting an intensity-frontier FCC sets ambitious but feasible goals for for w a r d s. T h e s e i d e a s w o u l d s o o n u n d e r- to resound today. As Ramond earlier a picture of Feynman “hanging out” in bids bet ween par t icipants. lepton collider (FCC-ee) as a first step, the global community resembling previ- pi n t h e q u a nt u m d e s c r i p t i o n o f e l e c t r o - explained, Feynman’s contribution to a Max Delbruck’s laboratory at Caltech, The co-innovation workshop was followed by an energy-frontier hadron o u s l e a p s i n t h e l o n g h i s t or y o f o u r fie l d.” m a g n e t i s m – QE D – for w h i c h Fe y n m a n c o n fe r e n c e i n C h a p e l H i l l i n 1957, h i s fi r s t even taking a sabbatical at the beginning part of a bigger event, “Particle Collid- mac hine (FCC-hh). It offers substant ial shared the 1965 Nobel Prize in Physics p u bl i c i nt e r v e nt i o n o n t h e s u bj e c t, i s n o w o f t h e 1960 s t o w or k t h e r e, e x pl or i n g t h e ers – Accelerating Innovation”, which was and model-independent studies of the Panos Charitos CERN. w it h Tomonag a and Sc hw inger. s e e n a s t h e s t a r t i n g p oi nt for d i s c u s s io n s m ol e c u l a r w or k i n g s o f h e r e d it y. I n 1969 on how to measure g rav itat ional w aves. he gave the famous Hughes Aerospace aleGro workshop ALEGRO Revolutionary diagrams Cristiane Morais-Smith spoke on lectures, offering a grand overview of T h e pr o p a g a t or w a s t h e k e y t o t h e e p o n y- Feynman’s path integrals, comparing biology and chemistry – but this was Upping the tempo mous diagrams Feynman then formu- Hamiltonian and Lagrangian formu- also the time of the parton model and l a t e d t o c o m p ut e t h e L a m b s h i f t a n d o t h e r lations, and showing their importance somehow that interest took over. on wakefield q u a nt it ie s. A t t h e Si n g a p or e c o n fe r e n c e, in perturbative QED. Michael Creutz, Robbert Dijkgraaf spoke about the L a n c e D i x o n e x p o s e d h o w Fe y n m a n d i a- the son of one of Feynman’s colleagues interplay between art and science in accelerators g r a m s re volut ion i s e d t he c a lc u l at ion of at Princeton and Los Alamos, showed Fe y n m a n’s l i fe a nd t h i n k i ng. He p oi nte d scattering amplitudes. He offered as an how the path integral is also necessary out how important beauty is, not only Around 50 experts from around the world example the calculation of the anoma- to be able to work on the inherently in nature, but also in mathematics, for met at CERN from 26 to 29 March for lous magnetic moment of the electron, non-perturbative theory of quantum instance whether one uses a geometric the second ALEGRO workshop to discuss which has now reached five-loop pre- chromodynamics. Morais-Smith went or algebraic approach. Another moving advanced linear-collider concepts at the Advanced pulses or bunches in efficient drivers (in particular laser cision and includes 12,672 diagrams. on to illustrate how Feynman’s path moment of this wide-ranging celebration energy frontier. accelerators plasma, dielectric or metallic structures systems), wall-plug-to-beam-power Dixon also discussed the importance integrals now have a plethora of appli- o f Fe y n m a n’s l i fe a n d p h y s ic s w a s M ic h e l l e ALEGRO, the Advanced Linear Col- Experts met at to reach gradients as high as 1 GeV/m. e ffic ie nc y, op e r at ion at h ig h-re p e t it ion of Fey nma n’s pa r ton pic t ure for under- Feynman’s cations outside particle physics, from Fe y n m a n’s w ord s a b o ut g r o w i n g u p w it h lider Study Group, was formed as an CERN in March. The proposed Advanced Linear Interna- rates, tolerance studies, the staging of standing deep-inelastic scattering, and 1981 paper g r ap he ne to qua nt u m Bro w n i a n mot ion h e r f a t h e r. S h e s h o w e d h i m b o t h a s a f a m- outcome of an ICFA workshop on adv- tional Collider – ALIC for short – would two structures and the development of the staggeringly complex calculations w a s t he fi r st and dissipative quantum tunnelling. ily man and also as a scientist, sharing anced accelerators held at CERN in be shorter than linear colliders based on suitable numerical tools to allow for the required to understand data at the LHC. on quantum Indeed, the conference did not neglect h i s e nt hu s i a s m for s o m a n y t h i n g s i n l i fe. 2017 (CERN Courier December 2017 p31). more conventional acceleration technol- s i m u l a t i o n o f t h e a c c e l e r a t or a s a w h ol e. George Zweig, the most famous of Feynman’s famous interventions outside  Recordings of the presentations are Its purpose is to unite the accelerator ogies such as CLIC and ILC, and would The next ALEGRO workshop will be computers and Feynman’s students, and the inventor of p a r t i c l e p h y s i c s. F r a n k W i lc z e k r e c o u nt e d available online. community behind a > 10 TeV electron– reac h higher energ ies. held in Marc h 2020 in Ger many. “aces” as the fundamental constituents of set the ground Feynman’s famous insight that there is positron collider based on advanced The main research topics ALEGRO matter, gave a vivid talk, recounting that for the present plenty of room at the bottom, telling of Lars Brink Chalmers University of and novel accelerators (ANAs), which identified are the preservation of beam Patric Muggli Max Planck Institute for it took a long time to convince a scepti- developments his legendary after-dinner talk in 1959 Technology, Göteborg, Sweden. use wakefields driven by intense laser quality, the development of stable and Physics, Munich, Germany.

20 CERN COURIER MAY/JUNE 2019 CERN COURIER MAY/JUNE 2019 21

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ViennA ConferenCe on inSTrumenTATion Best Cyclotron Systems provides 15/20/25/30/35/70 MeV Proton Cyclotrons as well as 35 & 70 MeV Multi-Particle Cross-fertilisation in detector development (Alpha, Deuteron & Proton) Cyclotrons More than 300 experts convened from on Instrumentation 15th Conference Vienna LHC Run 3 and for the high-luminos- Currents from 100uA to 1000uA (or higher) depending on the 18-22 February for the 15th Vienna Con- ity LHC. An overview of LIGO called for particle beam are available on all BCS cyclotrons ference on Instrumentation to discuss serious planning to ensure that future ongoing R&D efforts and set future ground-based gravitational-wave Best 20u to 25 and 30u to 35 are fully upgradeable on site roadmaps for collaboration. “In 1978 we detectors can be operational in the discussed wire chambers as the first elec- 2030s. Drawing a comparison between tronic detectors, and now we have a large the observation of gravitational waves Cyclotron Energy (MeV) Isotopes Produced number of very different detector types and the discovery of the Higgs boson, 18F, 99mTc, 11C, 13N, 15O, with performances unimaginable at that Christian Joram of CERN noted “Progress Best 15 15 64Cu, 67Ga, 124I, 103Pd time,” said Manfred Krammer, head of in experimental physics often relies on CERN’s experimental physics depart- breakthroughs in instrumentation that Best 15 + 123I, Best 20u/25 20, 25–15 ment, recalling the first conference of lead to substantial gains in measurement 111In, 68Ge/68Ga the triennial series. “In the long history accuracy, efficiency and speed, or even of the field we have seen the importance open completely new approaches.” 123 Best 30u Best 15 + I, of cross-fertilisation as developments Beyond innovative ideas and 30 111 68 68 (Upgradeable) In, Ge/ Ga for one specific experiment can catalyse cross-disciplinary collaboration, the Greater production of progress in many fronts.” development of new detector technolo- Following this strong tradition, the gies calls for good planning of resources Best 35 35–15 Best 15, 20u/25 isotopes conference covered fundamental and and times. The R&D programme for the 201 81 81 plus Tl, Rb/ Kr technological issues associated with the current LHC upgrades was set out in 82 82 123 67 most advanced detector technologies as 2006, and it is already timely to start Sr/ Rb, I, Cu, Installation of Best 70 MeV Best 70 70–35 81 well as the value of knowledge transfer preparing for the third long shutdown Kr + research Cyclotron at INFN, Legnaro, Italy to other domains. Over five days, par- in 2023 and the High-Luminosity LHC. ticipants covered topics ranging from Instrumental the world, spanning gravitational-wave Meanwhile, the CLIC and Future Circular s e n s or t y p e s a n d f a s t a n d e ffic ie nt e l ec- contributions The d e t e c t or s, c ol l i d e r s, fi x e d-t a r g e t e x p er- Collider studies are developing clear ideas tronics to cooling technologies and their Vienna conference iments, dark-matter searches, and neu- of the future experimental challenges in mechanical structures. cultivates the next trino and astroparticle experiments. A tackling the next exploration frontier. Contributors highlighted experi- generation of number of talks covered upgrade activ- ments proposed in laboratories around detector experts. ities for the LHC experiments ahead of Panos Charitos CERN. The BG-75 Biomarker Generator is a revolutionary 400 MeV Rapid Cycling Medical Synchrotron development in radio-pharmaceutical production for Proton-to-Carbon Heavy Ion Therapy: PHYSTAT-nu that delivers a single or batch dose of 18F-FDG, and 18 Intrinsically small beams facilitating Neutrino connoisseurs talk stats at CERN additional advanced F biomarkers on demand. beam delivery with precision The system provides integration of all components PHYSTAT-nu 2019 was held at CERN 2019 U YSTAT-N PH needed to produce and qualify PET biomarkers Small beam sizes – small magnets, from 22 to 25 January. Counted among light gantries – smaller footprint the 130 participants were LHC physicists into a single, self-contained system that occupies and professional statisticians as well a fraction of the space required by conventional Highly efficient single turn extraction as neutrino physicists from across the solutions, simplifying the implementation of PET. globe. The inaugural meeting took place Efficient extraction – less shielding at CERN in 2000 and PHYSTAT has gone from strength to strength since, with Flexibility – heavy ion beam therapy meetings devoted to specific topics in (protons and/or carbon), beam data analysis in particle physics. The delivery modalities latest PHYSTAT-nu event is the third of the series to focus on statistical issues in neutrino experiments. The workshop focused on the statistical tools used in data analyses, rather than experimental details and results. Modern neutrino physics is geared towards understanding the nature and ion Rapid Cycling Medical mixing of the three neutrinos’ mass and Statistically significant PHYSTAT-nu 2019 brought neutrino physicists together with statisticians and Synchrotron (iRCMS) flavour eigenstates. This mixing can LHC physicists. be inferred by observing “oscillations” between flavours as neutrinos travel are created in an accelerator, a nuclear tion cross section. Given the ghostly through space. Neutrino experiments reactor, or by any number of astro- nature of the neutrino, this calculation c o m e i n m a n y d i ffe r e nt t y p e s a n d s c a l es, physical sources, the number of events presents subtle statistical challenges. TeamBest Companies © 2019 * Best iRCMS is under development and not available for sale currently. but they tend to have one calculation expected in the detector is the product To cancel common systematics, many s www.bestcyclotron.com • www.bestabt.com • www.bestproton.com in common: whether the neutrinos of the neutrino flux and the interac- facilities have two or more detectors

BCS tel: 604 681 3327 • Best ABT tel: 865 982 0098 • BPT tel: 703 451 2378 CERN COURIER MAY/JUNE 2019 23

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at different distances from the neutrino Lessons can complicated by the different detector from t he LHC e x perience. s ou rc e. Howe ve r, a s w a s s how n for t he be learnt a c c e p t a n c e s, p o s s i bl e v a r i a t i o n s i n t h e T h e pr o bl e m o f m o d e l l i n g t h e i nt e r a c- NOVA and T2K experiments, compet- from the LHC d e t e c t or t e c h n ol o g i e s, a n d t h e c o m p o - t io n s o f n e ut r i n o s w it h nu c l e i – e s s e n- itors to observe CP violation using an sitions of different neutrino interaction tially the problem of calculating the experience accelerator-neutrino beam, it is difficult modes. In the coming years these two cross section in the detector – forces to correlate the neutrino yields in the experiments plan to combine their data researchers to face the thorny statis- n e a r a n d f a r d e t e c t or s. A f u l l c a n c e l l a- in a global analysis to increase their tical challenge of producing distribu- tionAnz_spec_CERN_4-2019_sp of the systematic uncertainties 10.04.19 is 17:49 Seite 1 d i s c o v e r y p o w e r – l e s s o n s c a n b e l e a r nt tions that are unadulterated by detector effects. Such “unfolding” corrects kinematic observables for the effects of detector acceptance and smearing, but correcting for these effects can cause huge uncertainties. To counter this, strong “regularisation” is often M2p.65xx M2p.65xx applied, biasing the results towards the smooth spectra of Monte Carlo simulations. The desirability of pub- lishing unregularised results as well as u n fol d e d m e a s u r e m e nt s w a s a g r e e d b y PHYSTAT-nu attendees. “Response m a t r i c e s” m a y a l s o b e r e l e a s e d, a l l o w i n g physicists outside of an experimental c ol l a b or a t i o n t o s m e a r t h e i r o w n m o d- e l s, a n d c o m p a r e t h e m t o d e t e c t or-l e v e l Discovery Science - UHV Chamber data. Another major issue in mode- ling neutrino–nuclear interactions is the “unknown unknowns”. As Kevin McFarland of the University of Roch- e s t e r r e fle c t e d i n h i s s u m m a r y t a l k, itis important not to estimate your uncer- t a i nt y b y a s u r v e y o f t h e or y m o d e l s. “It’s A major issue in modeling New AWG series: smaller, faster, better! neutrino–nuclear interactions is 16 bit resolution the “unknown with 40 MS/s and 125 MS/s unknowns”

6 product variations with 1 to 4 channels like trying to measure the width of a valley from the variance of the posi- Output level ±3 V (50 Ω) or ±6 V (1 MΩ) t ion of s he e p g r a z i ng on it. Th at h a s a n obvious failure mode: sheep read each Fast PCIe x4 interface with 700 MByte/s other’s papers.” An important step for current and streaming future neutrino experiments could be to set up a statistics committee, as at the , and, more recently, the LHC experiments. This PHYSTAT-nu workshop could be the first real step SPECTRUM tow ards t his e xcit ing scenario. INSTRUMENTATION The next PHYSTAT workshop will be held at Stockholm University from Perfect fit – modular designed solutions 31 July to 2 August on the subject of statistical issues in direct-detection Quality Production dark-matter experiments. Europe / Asia: Phone +49 (4102) 695 60 | US: Phone (201) 562 1999 Olaf Behnke DESY, www.spectrum-instrumentation.com Louis Lyons University of Oxford and Davide Sgalaberna CERN.

24 CERN COURIER MAY/JUNE 2019

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Flood Beams, Small Spot, High Brightness LaB6 FEATURE PROTON CENTENARY Ultra-fast ps to fs Photo Emission Guns 1 eV to 100 keV

EGG-3101 (10 keV) RUTHERFORD, TRANSMUTATION

EMG-4210 (30 keV) AND THE PROTON

The events leading to Ernest Rutherford’s discovery of the proton, published in 1919.

n his early days, Ernest Rutherford was the right man in the right place at the right time. After obtaining three Idegrees from the University of New Zealand, and with two years’ original research at the forefront of the electri- cal technology of the day, in 1895 he won an Exhibition of 1851 Science Scholarship, which took him to the Cavendish Artist R Mathews; McGill University Laboratory at the University of Cambridge in the UK. Just after his arrival, the discoveries of X-rays and radioactivity were announced and J J Thomson discovered the electron. Rutherford was an immediate believer in objects smaller EGH-8123 (100 keV) than the . His life’s work changed to understanding EMG-4193 (30 keV) radioactivity and he named the alpha and beta rays. In 1898 Rutherford took a chair in physics at McGill Uni- versity in Canada, where he achieved several seminal results. www.kimballphysics.com UHV MULTI-CF FITTINGS He discovered radon, demonstrated that radio-activity was just the natural transmutation of certain elements, showed Some of the over 100 Available that alpha particles could be deviated in electric and mag- Customs Encouraged netic fields (and hence were likely to be helium minus two electrons), dated minerals and determined the age of Metric Available the Earth, among other achievements. In 1901, the McGill Physical Society called a meeting titled “The existence of bodies smaller than an atom”. Its aim was to demolish the chemists. Rutherford spoke to the motion and was opposed by a young Oxford chemist, Frederick Soddy, who was at McGill by chance. Soddy’s address “Chem- ical evidence for the indivisibility of the atom” attacked physicists, especially Thomson and Rutherford, who “… have been known to give expression to opinions on chemistry in general and the atomic theory in particular which call for strong protest.” Rutherford invited Soddy, who special- ised in gas analysis, to join him. It was a short but fruitful collaboration in which the pair determined the first few steps in the natural transmutation of the heavy elements.

Manchester days For some years Rutherford had wished to be more in the centre of research, which was Europe, and in 1907 moved to the University of Manchester. Here he began to follow up on experiments at McGill in which he had noted that a Nuclear giant Ernest Rutherford in Canada in 1907. beam of alpha particles became fuzzy if passed through air

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FEATURE PROTON CENTENARY INSTRUMENTATION LIBERA TECHNOLOGIES

MEET INSTRUMENTATION MEET LIBERA, provider TECHNOLOGIES, intertwining of solutions for a strong portfolio of particle accelerators, brands and expertise Trained IN Instrumen- for 20+ years. tation Technologies. Atomic history or a thin slice of mica. They were scattered by an angle of before heading to Australia for the annual meeting of the How the Boston a b o ut t w o d e g r e e s, i n d ic at i n g t h e pr e s e n c e o f e le c t r ic fie ld s British Association for the Advancement of Science. Three Globe reported of 100 MV/cm, prompting his statement that “the atoms of days before his arrival, war was declared in Europe. the discovery of matter must be the seat of very intense electrical forces”. the proton on At Manchester he inherited an assistant, Hans Geiger, Splitting the atom OfferS expert domain 8 December 1919 who was soon put to work making accurate measurements Rutherford arrived back in Manchester in January 1915, OfferS cutting edge solu- and application knowl- (left), and a of the number of alpha particles scattered by a gold foil via a U-boat-laced North Atlantic. It was a changed world, commemorative over these small angles. Geiger, who trained the senior w it h t h e yo u n g m e n off fi g ht i n g i n t h e w a r. O n b e h a lfothe tions on technologically edge to support New Zealand stamp undergraduates in radioactive techniques, told Rutherford Admiralty, Rutherford turned his mind to one of the most demanding fields. our users. from 1971 (right). in 1909 that one, Ernest Marsden, was ready for a subject pressing problems of the war: how to detect submarines of his own. Everyone knew that beta particles could be when submerged. His directional hydrophone (patented s c at t e r e d off a blo c k o f m e t a l, b ut n o o n e t h o u g ht t h at alph by Bragg and Rutherford) was to be fitted to fleet ships. particles would be. So Rutherford told Marsden to exam- It was not until 1917 when Rutherford could return to his ine this. Marsden quickly found that alpha particles are scientific research, specifically alpha-particle scattering indeed scattered – even if the block of metal was replaced from light atoms. By December of that year, he reported by Geiger’s gold foils. This was entirely unexpected. It was, to Bohr that “I am also trying to break up the atom by this a s Rut h e r ford l at e r d e c l a r e d, a s i f yo u fi r e d a 15 inch naval method. – Regard this as private.” shell at a piece of tissue paper and it came back and hit you. He studied the long-range hydrogen-particle recoils in One day, a couple of years later, Rutherford exclaimed to several media (hydrogen gas, solid materials with a lot of

Geiger that he knew what the atom looked like: a nuclear hydrogen present and gases such as CO2 and oxygen), and structure with most of the mass and all of one type of was surprised to find that the number of these “recoil” charge in a tiny nucleus only a thousandth the size of an particles increased when air or nitrogen was present. He atom. This is the work for which he is most famous today, deduced that the alpha particle had entered the nucleus of eight decades after his death (CERN Courier May 2011 p20). the nitrogen atom and a hydrogen nucleus was emitted. Around 1913, Rutherford asked Marsden to “play marbles” This marked the discovery that the hydrogen nucleus – HAS A large portfolio of with alphas and light atoms, especially hydrogen. Classical or the proton, to give it the name coined by Rutherford in products for beam diag- calculations showed that an alpha colliding head-on with a 1920– is a constituent of larger atomic nuclei. hydrogen nucleus would cause the hydrogen to recoil with Marsden was again available to help with the experi- nostics and stabilization a speed 1.6 times, and a range four times, that of the alpha ments for a few months from January 1919, whilst awaiting particle that struck it. The recoil of the less-massive, less- transport back to New Zealand after the war, and that year charged hydrogen could be detected as lighter flashes on the Rutherford accepted the position of director of the Cavendish scintillation screen at much greater range than the alphas Laboratory. Having delayed publication of the 1917 results INTRODUCING LIBERA’S could travel. Marsden indeed observed such long-range “H” until the war ended, Rutherford produced four papers on the LATEST GADGET OF CHOICE particles, as he named them, produced in hydrogen gas and l i g ht-at o m wor k i n 1919. I n t h e fo u r t h, “A n a n o m a lo u s e ffe c t Libera digit 500 in thin films of materials rich in hydrogen, such as paraf- in nitrogen.”, he wrote “we must conclude that the nitrogen fin wax. He also noticed that the long-ranged H particles atom disintegrated ... and that the hydrogen atom which is were sometimes produced when alpha particles travelled liberated formed a constituent part of the nitrogen nucleus.” - 4 channel digitizer with 500 MSps / 14 bit ADCs through air, but he did not know where they came from: He also stated: “Considering the enormous intensity of the - >80dB of dynamic range and 31dB of variable attenuataion water vapour in the gas, absorbed water on the apparatus forces brought into play, it is not so much a matter of surprise - ADC sampling phase locked to external reference signal or even emission from the alpha source, were suggested. t h at t he n it ro ge n atom s hou ld s u ffe r d i s i nte g r at ion a s t h at - passive cooled and boot from micro-SD card Mid-1914 bought an end to the collaboration. Marsden the α particle itself escapes disruption into its constituents”. - EPICS/Tango/Python available interfaces wrote up his work before accepting a job in New Zealand. In 1920 Rutherford first proposed building up atoms from - ready to be used with CSS GUI Meanwhile, Rutherford had sailed to Canada and the US to stable alphas and H ions. He also proposed that a particle of give lectures, spending just a month back at Manchester mass one but zero charge had to exist () to account

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FEATURE PROTON CENTENARY Mag. Philos. for isotopes. With Wilson’s cloud chamber he had observed branched tracks of alpha particles at the end of their range. A 37

Japanese visitor, Takeo Shimizu, built an automated Wilson 543 cloud chamber capable of being expanded several times per second and built two cameras to photograph the tracks at right angles. Patrick Blackett, after graduating in 1921, took over t h e pr oj e c t w h e n Sh i m i z u r e t u r n e d t o Ja p a n. A f t e r m o d i fic a- tions, by 1924 he had some 23,000 photographs showing some 400,000 t r a c k s. E i g ht w e r e for k e d, c o n fi r m i n g Rut h e r ford’s discovery. As Blackett later wrote: “The novel result deduced from these photographs was that the α was itself captured by the nitrogen nucleus with the ejection of a hydrogen atom, so producing a new and then unknown isotope of oxygen, 17O.” As Blackett’s work confirmed, Rutherford had split the Experimental sketch Rutherford’s apparatus for splitting the atom, showing the alpha at o m, a n d i n d oi n g s o h a d b e c o m e t h e world’s fi r s t s uc c e s s f u l emitter (D), which could be slid along B; metal absorbers equivalent to the stopping power alchemist, although this was a term that he did not like very of about 5 cm of air (S); and the ZnS scintillation screen (F). much. Indeed, he also preferred to use the word “disinte- gration” rather than “transmutation”. When Rutherford There was never a second prize for his detection of individual and Soddy realised that radioactivity caused an element to alpha particles, unearthing the nuclear structure of atoms, naturally change into another, Soddy has written that he or the discovery of the proton. But few would doubt the yelled “Rutherford, this is transmutation: the thorium is immense contributions of this giant of physics.  disintegrating and transmuting itself into argon (sic) gas.” Rutherford replied, “For Mike’s sake, Soddy, don’t call it Further reading THE AUTHOR transmutat ion. They’ll have our heads off as alc hemists!” J Campbell 1999 Rutherford Scientist Supreme John Campbell In 1908 Rut her ford had b e en aw a rde d t he Nob el P r i ze i n (AAS Publications). University of Chemistry “for his investigations into the disintegration of A Romer 1997 Am. J. Phys. 65 707. Canterbury, the elements, and the chemistry of radioactive substances”. E Rutherford 1919 Philos. Mag. 37 581. New Zealand.

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FEATURE LEPTON-FLAVOUR UNIVERSALITY Simulation enhances the understanding of solitons in fiber optics. THE In the 1830s, John Scott Russell followed a wave on horseback along a canal. The wave seemed to travel forever. He came to call it “the wave of translation” and spent two years replicating it for FLAVOUR further studies. Today, they are known as solitons and are relevant to fiber optics research. While Scott Russell had to build a 30-foot basin in his backyard, you can study solitons more easily using iStock/unpict OF NEW equation-based modeling and simulation. The COMSOL Multiphysics® software is used for simulating designs, devices, and processes in all fields of engineering, manufacturing, and PHYSICS scientific research. See how you can apply it to Visualization of two solitons colliding and reappearing in soliton analysis for fiber optics. an optical fiber. comsol.blog/chasing-waves Recent experimental results hint that some electroweak processes a re not lepton-flavour i ndep endent, cont r a r y to St a nda rd Mo del expectations. If the effect strengthens as more data are gathered, p ossible e x pla nat ions r a nge f rom ne w g auge forces to lepto qua rk s.

POWERED BY In 1971, at a Baskin-Robbins ice-cream s h o u ld b e e x t e n d e d w it h n e w le p t o n n o n-u n i v e r s a l forc e s. THE AUTHORS s t or e i n P a s a d e n a, C a l i for n i a, M u r r a y G e l l- Suc h t e s t s w e r e d i s c u s s e d at t h e d a w n o f t h e fl a v o u r-p h y s ic s Jorge Martin Mann and his student Harald Frit zsch came programme in the early 1980s following the discovery of Camalich up with the term “flavour” to describe the the b quark. Fast-forward almost 40 years, and we may be Instituto de different types of quarks. From the three types seeing the first deviations from lepton-flavour universality Astrofísica de Canarias and known at the time – up, down and strange – the (L F U) for w e a k i nt e r a c t io n s, i n m e a s u r e m e nt s o f b q u a r k s Universidad de La list of quark flavours grew to six. A similar picture bound inside B mesons. The World’s Most Advanced Laguna, Spain e v ol v e d for t h e le p t o n s: t h e e le c t r o n a n d t h e muo n w e r e To d a y, fl a v o u r p h y s ic s i s a m aj or fie ld o f a c t i v it y. A q uick and Jure Zupan Digital Pulse Processor joined by the unexpected discovery of the lepton at look at the Particle Data Group (PDG) booklet, with its long University of SL AC i n 1975 a n d c o m ple t e d w it h t h e t h r e e c or r e s p o n d i n g lists of the decays of B mesons, D mesons, kaons and other Cincinnati, USA. for high-rate Spectroscopy neutrinos. These 12 elementary fermions are grouped into hadrons, gives an impression of the breadth and depth of three generations of increasing mass. the field. Even in the condensed version of the PDG booklet, With a Pearson™ Current Monitor you can make precise The three flavours of charged leptons – electron, muon s uc h l i s t i n g s r u n t o m or e t h a n 170 p a g e s. St i l l, t h e r e s u lt s amplitude and waveshape measurement of AC and pulse • Up to 8 channels currents from milliamperes to kiloamperes. Current can be and tau – are the same in many respects. This “flavour can be summarised succinctly: all the measured decays of simultaneous measured in any conductor or beam of charged particles, universality” is deeply ingrained in the symmetry structure agree with SM predictions, with the exception of meas- including those at very high voltages. of the Standard Model (SM) and applies to both the elec- urements that probe LFU in two quark-level transitions: processing A typical model gives you an amplitude accuracy of +1%, -- + - troweak and strong forces (though the latter is irrelevant b → cτ ντ and b → sμ μ . -0%, 20 nanosecond rise time, droop of 0.8% per • Over 3 Mcps for leptons). It directly follows from the assumption that millisecond, and a 3dB bandwidth of 1 Hz to 20 MHz. processed by Other models feature 1.5 nanosecond rise time, or a droop the SM gauge group, SU(3) × SU(2) × U(1), is one and the same Oddities in decays to D mesons for all three generations of fermions. The Higgs field, on the In the SM the b c -- process is due to a tree-level each channel as low as 0.05% per millisecond. → τ ν τ other hand, distinguishes between fermions of different e x c h a n g e o f a v i r t u a l W b o s o n (fi g u r e 1, le f t). T h e W b o s on, [email protected] fl a v o u r s a n d e n d o w s t h e m w it h d i ffe r e nt m a s s e s–ome- being much heavier than the amount of energy that is Tel: +1-510-401-5760 Contact Pearson Electronics times strikingly so. In other words, the gauge forces, such released in the decay of the b quark, is virtual. Rather www.xia.com for application information. a s t h e e le c t r o w e a k forc e, a r e fl a v o u r-u n i v e r s a l i n t h e S M, than materialising as a particle, it leaves its imprint as while t he e xc hange of a Higgs par t icle is not. a very short-range potential that has the property of Pearson Electronics Experimental tests of whether or not the electroweak changing one quark (a b quark) into a different one (a 4009 Transport St. Palo Alto, CA 94303 USA force is indeed flavour-universal directly check if our c quark) with the simultaneous emission of a charged Telephone: (650) 494-6444 FAX (650) 494-6716 understanding of the subatomic world is correct, or if it lepton and an ant ineutrino.

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FEATURE LEPTON-FLAVOUR UNIVERSALITY

the reported hints for the increased b → cτ–-ν rates. This is ...the power in microwaves! τ – – light enough that the new particle could even be produced c c(s) τ (μ ) – – directly at the LHC. Even better, the options for what this τ– τ (μ ) b b b c(s) new particle could be are quite restricted. There are two main possibilities. One is a colour singlet H–, W (Z ) W– ʹ ʹ LQ that does not feel the strong force, for which candidates ULTRA AVAILABLE include a new charged Higgs boson or a new commonly denoted Wʹ (figure 1, middle). However, both ––+ – + ντ ντ (μ ) ντ (μ ) of these options are essentially excluded by other meas-

urements that do agree with the SM: the lifetime of the Bc AMPLIFIERS Fig. 1. The semileptonic decay of the b quark in the Standard Model (left). Possible new meson; searches at the LHC for anomalous signals with tau contributions to this process include exchanges of new colour-singlet states (middle), leptons in the final state; decays of weak W and Z bosons - or new coloured states coupling simultaneously to quarks and leptons (right). into leptons; and by Bs mixing and B → Kν ν decays. The –ν in b → cτ-–ν can also be replaced by a right-handed neutrino, which is not part of The second possible type of new particle is a leptoquark FOR ACCELERATOR & τ τ the Standard Model. that couples to one quark and one lepton at each vertex (figure 3, right). Typically, the constraints from other meas- urements are less severe for leptoquarks than they are for MEDICAL APPLICATIONS BaBar 0.42 new colour-singlet bosons, making them the preferred LHCb combination –- explanation for the b → cτ ντ anomaly. For instance, they Belle 2019 SL BTag, τ → l ν ν (preliminary) contribute to B mixing at the one-loop level, making the TMD in collaboration with Rosatom - NIITFA is now able to Belle combination 2019 (preliminary) s 0.38 World combination 2019 resulting effect smaller than the present uncertainties. offer revolutionary, ultra-available RF solid state amplifiers SM prediction Since leptoquarks are charged under the strong force, in for scientific and medical applications. the same way as quarks are, they can be copiously produced 0.34 at the LHC via strong interactions. Searches for pair- or singly-produced leptoquarks at the future high-luminosity D*

Innovative power combining and control system results in: R LHC and at a proposed high-energy LHC will cover most of 0.30 the available parameter space of current models. • Ultra-compact systems, typically one Applications: Oddities in decays to kaons 19” rack / 100 kW (pulse) • Synchrotrons, LINACs for scientific, 0.26 The other decay showing interesting flavour deviations • CW / Pulse Systems, long pulse experimentation/particle physics (b → sμ+μ–) is probed via the ratios R = Br(B → K(*)μ+μ–)/ SM prediction K(*) • Modular Solid State architecture, and Spallation systems Br(B → K(*)e+e–), which test whether the rate for the b → sμ+μ– RD = 0.299 ± 0.003 quark-level transition equals the rate for the b se+e– one. compact modules (<10 kg) • Medical therapy equipment 0.22 RD* = 0.258 ± 0.005 → The SM very precisely predicts RK( ) = 1, up t o s m a l l c or r e c- Courtesy Honeywell Aerospace • Highly Maintainable with Hot Swap • Cyclotrons for radioisotope * 0.20 0.25 0.30 0.35 0.40 0.45 0.50 tions due to the very different masses of the muon and the capability production RD electron. Measurements from LHCb on the other hand, are • Wall Plug efficiency competitive with • Option to upgrade existing systems c o n s i s t e nt l y b e lo w 1, w it h s t at i s t ic a l s i g n i fic a n c e s o f a b o ut tube technology (55% demonstrated) Fig. 2. Experimental results for the two observables probing lepton-flavour universality 2.5 s t a n d a rd d e v i at io n s, w h i le le s s pr e c i s e m e a s u r e m e nt s comparing b c -– and b cl-– decays, l = e, μ. The point with error bars shows the SM f r o m B e l le a r e c o n s i s t e nt w it h b o t h L HC b a n d t h e S M (fi g- • Highly robust to VSWR mismatch Other Products: → τ ντ → νl prediction, while the shaded grey region shows the world experimental results average. ure 3). Further support for these discrepancies is obtained • High MTBF and Low MTTR • High Power, Very Low Phase Noise from other observables, for which theoretical predictions • No loss of power from any single TWT Amplifiers Flavour universality is probed by measuring the ratio are more uncertain. These include the branching ratios ( ) –- ( ) + – element failure • Brazed UHV components of branching fractions: RD(*) = Br(B → D * τ ντ)/Br(B → D * for decays induced by the b → sμ μ quark-level transition, l–- ), where l = e, . Two ratios can be measured, since and t he distribut ions of t he final-state par t icles. • High efficiency enhances reliability • Electron Guns ν l μ –- the is either bound inside a or its In contrast to the tree-level b → cτ ντ process underlying • Frequencies available from + – excited version, the D*, and the two ratios, RD and RD*, the semileptonic B decays to D mesons, the b → sμ μ 20 MHz to 1.3 GHz have the very welcome property that they can be pre- decay is induced via quantum corrections at the one-loop • MW power capability cisely predicted in the SM. Importantly, since the hadronic level (figure 4, left) and is therefore highly suppressed inputs that describe the b → c transition do not depend in the SM. Potential new-physics contributions, on the on which lepton flavour is in the final state, the induced other hand, can be exchanged either at tree level or also For more information on our leading edge uncertainties mostly cancel in the ratios. Currently, the at one-loop level. This means that there is quite a lot of SM prediction is roughly three standard deviations away freedom in what kind of new physics could explain the technology email us at [email protected] from the global average of results from the LHCb, BaBar b → sμ+μ– anomaly. The possible tree-level mediators are a and Belle e x periments (fig ure 2). Zʹ and leptoquarks with masses of about 30 TeV or lighter, or visit www.tmd.co.uk A possible explanation for this discrepancy is that there if the couplings are smaller. For loop-induced models is an additional contribution to the decay rate, due to the the new particles are necessarily light, with masses in exchange of a new . For coupling strengths the TeV range or below. This means that the searches for that are of order unity, such that they are appreciably large direct production of new particles at the LHC can probe a yet small enough to keep our calculations reliable, the mass s i g n i fic a nt r a n g e o f e x pl a n at io n s for t h e L HC b a n o m a l ies. of such a new particle needs to be about 3 TeV to explain However, for many of the possibilities the high-energy

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FEATURE LEPTON-FLAVOUR UNIVERSALITY

Fig. 3. The 2.0 2.0 LHCb BelleB preliminary experimental results

for RK* , measured in 1.5 1.5 several bins of di-muon invariant 2

* mass squared, q . K K R

1.0 R 1.0 The vertical faint BaBar yellow bands denote REALIZE THE FULL POTENTIAL Belle BaBar 0.5 0.5 resonance regions LHCb Run 1 Belle LHCb Run 1 + 2015 + 2016 LHCb that are cut out in SM prediction SM prediction the analyses. OF PARTICLE THERAPY 0.0 0.0 0510 15 20 0 5 10 15 20 q2 (GeV2/c4)q2 (GeV2/c4) With high precision comes high sensitivity. As the market leader in particle therapy treatment planning, RaySearch understands this. That’s why we’ve * Fig. 4. Left: one of designed RayStation® to account for every eventuality. RayStation makes it ss s possible to create outstanding treatment plans for a large variety of particle μ– the Feynman diagrams giving the therapy delivery techniques and beamlines. Experience the premier system, – + - with access to all the unique innovations RayStation is renowned for. b W b b b → sμ μ transition in the SM. Middle and right: representative – μ diagrams for models t PROTON PLANNING that generate • PBS, DS, US, LS, Wobbling + - Z, γ b → sμ μ at one loop • Monte Carlo dose computation/optimization level, where the red • Robust optimization and evaluation + lines correspond to μ • PBS optimization with apertures/MLC + – particles beyond + μ μ μ the SM. • Multi-criteria optimization, including robustness • Fully integrated adaptive planning upgrade to the LHC or a future circular collider with much at LHCb and at Belle II, which is currently ramping up at • Simulated organ motion higher energy would be required for the new particles to KEK in Japan. In addition, there are many related measure- • Interplay evaluation be discovered or ruled out. ments that are planned, both at Belle II as well as at LHCb, • Automatic creation of backup photon plans and also at ATLAS and CMS. For instance, measuring the Taking stock s a m e t r a n s it io n s, b ut w it h d i ffe r e nt i n it i a l- a n d fi n a l-s t ate * Could the two anomalies be due to a single new lepton hadrons, should give further insights into the structure of CARBON-IONPLANNING BORON NEUTRON * non-universal force? Interestingly, a leptoquark dubbed new-physics contributions. If the anomalies are confirmed, • Carbon-ion PBS optimization CAPTURE THERAPY

U1 – a spin-one particle that is a colour triplet, charged this would then set a clear target for the next collider such • Robustness tools • Support for defining BNCT-specific under hypercharge but not – can explain as the high-energy LHC or the proposed proton–proton • Multi-field and single-field optimization RBE models both anomalies. With some effort it can be embedded in Future Circular Collider, since the new particles cannot • Plan directly deliverable on synchrotrons • BNCT treatment plans creation consistent theoretical constructions, albeit those with very be arbitrarily heavy. • Combination planning with other n o n-t r i v i a l fl a v o u r s t r uc t u r e s. T h e s e m o d e l s a r e b a s e don I f t h i s e x c it i n g s c e n a r io pl a y s o ut, it wo u ld n o t b e t h e fi r s t modalities modified versions of grand unified theories (GUTs) from time that indirect searches foretold the existence of new t h e 1980 s. Si n c e GU T s u n i f y t h e le p t o n s a n d q u a r k s, s o m e physics at the next energy scale. Nuclear beta decay and of the force carriers can change quarks to leptons and vice other weak transitions prognosticated the electroweak W + – versa, i.e. some of t he force carriers are leptoquarks. The and Z gauge bosons, the rare kaon decay KL → m m pointed to

U1 leptoquark could be one such force carrier, coupling the existence of the charm quark, including the prediction predominantly to the third generation of fermions. In for its mass from kaon mixing, while B-meson mixings *Subject to regulatory clearance in some markets.

all cases the U1 leptoquark is accompanied by many other and measurements of electroweak corrections accurately

particles with masses not much above the mass of U1. predicted the top-quark mass before it was discovered. While intriguing, the two sets of B-physics anomalies are Finally, the measurement of CP violation in kaons led to by no means confirmed. None of the measurements have the prediction of the third generation of fermions. If the s e p a r at e l y r e a c h e d t h e fi v e s t a n d a rd d e v i at io n s n e e d e d to present flavour anomalies stand firm, they will become claim a discovery and, indeed, most are hovering around another important item on this historic list, offering a While the 1–3 sigma mark. However, taken together, they form view of a new energy scale to explore.  intriguing, an interesting and consistent picture that something is ADVANCING potentially going on. We are in a lucky position that new Further reading the two sets measurements a re e x pec ted to be fin ished soon, some i n J Zupan 2019 arXiv:1903.05062. of B-physics CANCER a few months, others in a few years. L Geng et al. 2017 Phys. Rev. D 96 093006. anomalies are TREATMENT First of all, the observables showing the discrepancy D Buttazzo et al. 2017 J. High Energy Phys. 1711 044. by no means

from the SM, RD(*) and RK(*), will be measured more precisely A Cerri et al. 2018 arXiv:1812.07638. confirmed

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FEATURE THE PROTON THE PROTON LAID BARE What a proton is depends on how you look at it, or rather on how hard you hit it. A century after Rutherford’s discovery, our picture of this ubiquitous particle is coming into focus. D Dominguez/CERN THE AUTHOR very student of physics learns that the nucleus was they were partons. The SLAC experiments established that Amanda discovered by firing alpha particles at atoms. The the scattering centres had spin ½ as required by the quark Cooper-Sarkar Eresults of this famous experiment by Rutherford in model, but there were two problems. On the one hand there University of 1911 indicated the existence of a hard-scattering core of appeared to be not only three, but many scattering centres. Oxford. positive charge, and, within a few years, led to his discovery On the other, Feynman’s formalism required the partons to of the proton (see p27). Decades later, similar experiments be “free” and independent of each other, yet they could hardly with electrons revealed point-like scattering centres inside be independent if they remained confined in the proton. the proton itself. Today we know these to be quarks, anti- quarks and gluons, but the glorious complexity of the proton Painting a picture is often swept under the carpet. Undergraduate physicists The picture became even more interesting in the late 1970s are more often introduced to quarks as objects with flavour and 1980s when scattering experiments started to use quantum numbers that build up mesons and baryons in neutrinos and antineutrinos as probes. Since neutrinos bound states of twos and threes. Indeed, in the 1960s, many a n d a nt i n e ut r i n o s h a v e a d e fi n it e h a n d e d n e s s, or h e l ic it y, people regarded quarks simply as a useful book-keeping such that their spin is aligned against their direction of device to classify the many new “elementary” particles that motion for neutrinos and with it for antineutrinos, their had been discovered in cosmic rays and bubble-chamber weak interaction with quarks and antiquarks gives dif- experiments. Few people were aware of the inelastic-scat- ferent angular distributions. This showed that there must tering experiments at SLAC with 20 GeV electrons, which be antiquarks as well as quarks within the proton. In fact, were beginning to reveal a much richer picture of the proton. it led to a picture in which the flavour properties of the The results of these experiments in the 1960s and early proton are governed by three valence quarks immersed in 1970s were remarkable. Elastic scattering by the point-like a sea of quark–antiquark pairs. But this is not all: the same electrons revealed the spatial distribution of the proton’s experiments indicated that the total momentum carried by charge, and cross sections had to be modified by form-factors the valence quarks and the sea still amounts to only around Experiments as a result. These varied strongly depending on how hard half of that of the proton. This missing momentum was at CERN the proton was struck – a hardness called the scale of the termed an energy crisis, and was solved by the existence unearthed process, Q2, defined by the negative squared four-momen- of gluons with spin 1, which bind the quarks together and a mystery tum transfer between incoming and outgoing electrons. confine t hem inside t he proton. concerning At high enough scales the proton broke up, a phenomenon In fact, the SLAC experiments had been lucky to be mak- the origin of that can be quantified by x, a kinematic variable related ing measurements in the kinematic region where scaling the proton’s to the inelasticity of the interaction. Both the scale and holds almost perfectly – where the cross section is inde- spin the inelasticity could be determined from the dynamics of pendent of Q2. The quark–parton model had to be extended, the outgoing electron. Physicists anticipated a complicated and became the field theory of quantum chromodynam- dependence on both variables. Studies of scattering at ever ics (QCD), in which the gluons are field carriers, just like higher and lower scales continue to bear fruit to this day. photons in (QED). Formulated in 1973, QCD has a much richer structure than QED. There A surprise at SLAC are eight kinds of gluons that are characterised in terms The big surprise from the SLAC experiments was that the of a new called colour, which is carried cross section did not depend strongly on Q2, a phenomenon by both quarks and the gluons themselves, in contrast to called “scaling”. The only explanation for scaling was QED, where the field carrier is uncharged. The gluon can that the electrons were scattering from point-like centres thus interact with itself as well as with quarks. In the 1960s, within the proton. Feynman worked out the formalism to From the 1980s onwards, a series of experiments probed many people understand this by picturing the electron as hitting a point- increasingly deeply into the proton. Deep-inelastic-scat- regarded like “parton” inside the proton. With elegant simplicity, tering experiments using neutrino and muon beams were quarks simply he deduced that the partons each carried a fraction x of performed at CERN and Fermilab, before the HERA electron– as a useful the proton’s longitudinal momentum. pr o t o n c ol l id e r at DE S Y m a d e d e fi n it i v e m e a s u r e m e nt s f r o m book-keeping Gell-Mann and Zweig had proposed the existence of 1992 t o 2007 (fi g u r e 1). T h e a i m w a s t o t e s t t h e pr e d ic t io nsof device qua rk s i n 1964, but at first it w as by no mea ns obv ious t hat Glorious complexity An artist’s impression of the mayhem of quarks and gluons inside the proton. QCD as much as to investigate the structure of the proton,

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FEATURE THE PROTON FEATURE THE PROTON

580 and ZEUS the goal being not just to list the constituents of the proton, strong-coupling constant varies very quickly, from αs ~1 at predicted if we know the PDFs in the proton very accurately. Knowledge but also to understand the forces between them. low energy to ~0.1 at the energy scale of the mass of the Z The dominant uncertainty on the direct production of of PDFs is HERA NC e–p 0.4 fb±1 7 M e a n w h i le, t h e E MC e x p e r i m e nt at C E R N h a d u n e a r t h e d boson. Thus the quarks become “asymptotically free” when particles predicted by physics beyond the Standard Model 10 + ±1 becoming HERA NC e p 0.5 fb a mystery concerning the origin of the proton’s spin (see examined at high energy, but are strongly confined at low now comes from the limited precision of the PDFs of high-x

Eur. Phys.Eur. J 2015 C75 x = 0.00005, i = 21 increasingly x = 0.00008, i = 20 √s = 318 GeV “The proton spin crisis”), while elsewhere, entirely different energy – an insight leading to the award of the 2014 Nobel g luo n s. I n d i r e c t s e a rc h e s for n e w p h y s ic s a r e a l s o a ffe c t e d: 106 x = 0.00013, i = 19 vital for Source: Source: fixed target x = 0.00020, i = 18 experiments were placing increasingly tough limits on Prize in Physics to Gross, Politzer and Wilczek. precision measurements of Standard Model parameters, HERAPDF2.0 e–p NNLO discovery x = 0.00032, i = 17 the proton’s lifetime (see “The pursuit of ”). Once QCD had emerged as the definitive theory, the focus such as the mass of the W-boson and the weak mixing 5 x = 0.0005, i = 16 + physics at 10 HERAPDF2.0 e p NNLO 2 x = 0.0008, i = 15 turned to measuring the momentum distributions of the angle sin θ , are also limited by the precision of PDFs in W the LHC x = 0.0013, i = 14 Quantum considerations partons, dubbed parton distribution functions (PDFs, figure the regions where we currently have the best precision. 104 x = 0.0020, i = 13 x = 0.0032, i = 12 As with all quantum phenomena, what is in a proton depends 2). Several groups work on these determinations using both x = 0.005, i = 11 on how you look at it. A more energetic probe has a smaller deep-inelastic-scattering data and related scattering pro- Strange sightings at the LHC 3 x = 0.008, i = 10 i 10 x = 0.013, i = 9 wavelength and therefore can reveal smaller structures, but cesses, and presently there is agreement between theory and Standard Model processes at the LHC are now able to con- × 2 x = 0.02, i = 8 it also injects energy into the system, and this allows the experiment within a few percent across a very wide range tribute to our knowledge of the proton. As well as reducing r, NC 2 2 σ 10 x = 0.032, i = 7 creation of new particles. The question then is whether we of x and Q values. However, this is not quite good enough. the uncertainty on PDFs, however, the LHC data have led x = 0.05, i = 6 x = 0.08, i = 5 regard these particles as having been inside the proton in Today, knowledge of PDFs is increasingly vital for discovery to a surprise: there seem to be more –anti- 10 x = 0.13, i = 4 t he first place. At higher scales quarks radiate gluons t hat physics at the LHC. Predictions of all cross sections measured quark pairs in the proton than we had thought (CERN Courier x = 0.18, i = 3 then split into quark–antiquark pairs, which again radiate at the LHC – whether Standard Model or beyond – need to April 2017 p11). A recent study of the potential of the High- 1 x = 0.25, i = 2 gluons: and the gluons themselves can also radiate gluons. use input PDFs. After all, when we are colliding protons it Luminosity LHC suggests that we can improve the present

x = 0.40, i =1 The valence quarks thus lose momentum, distributing it is actually the partons inside the proton that are having uncertainty on the gluon PDF by more than a factor of two 10–1 between the sea quarks and gluons – increasingly many, hard collisions and the rates of these collisions can only be by studying jet production, direct photon production and with smaller and smaller amounts of momentum. A proton 10–2 x = 0.65, i = 0 at r e s t i s t h e r e for e v e r y d i ffe r e nt t o a pr o t o n, s a y, c i rc u l at ing The pursuit of proton decay in the Large Hadron Collider (LHC) at an energy of 7 TeV. h niestyo o yo Tok of y iversit Un The –3 The deep-inelastic-scattering data from muon, neutrino When Rutherford discovered the proton proton-decay experiments. By 1981 seven 10 and electron collisions established that QCD was the correct in 1919, the only other basic constituent of such experiments installed deep underground 1 10 102 103 104 105 theory of the . Experiments found that matter that was known of was the electron. were using either totally active water Q2/GeV2 the structure functions which describe the scattering cross There was no way that the proton could decay Cherenkov detectors or sampling calorimeters Fig. 1. HERA data on the e±p scattering cross section is in close agreement with Standard sections are not completely independent of scale, but depend without violating charge conservation. Ten to monitor large numbers of protons. These Model predictions as a function of both scale, Q2, and the interacting parton’s momentum on it logarithmically – in exactly the way that QCD pre- years later, Hermann Weyl went further, included the Irvine–Michigan–Brookhaven fraction, x (the factor 2i is artificially inserted to separate the curves vertically). dicts. This allowed the determination of the strong coupling proposing the first version of what would (IMB) detector based on 3300 tonnes of water 2 become a law for conservation. Even and 2048 5-inch PMTs and KamiokaNDE in At high x the cross section decreases with Q because the parton distribution functions “constant” αs, i n a n a lo g y w it h t he fi ne s t r uc t u re c on s t a nt (PDFs) decrease as the partons give up their momentum by radiating gluons that split to o f QE D, a n d it i s n o w u n d e r s t o o d t h at b o t h p a r a m e t e r s v a r y after the discoveries of the positron, and Japan with 1000 tonnes of water and 1000 quark–antiquark pairs, which radiate again. Correspondingly, the low-x PDFs increase. with the scale of the process. In contrast with QED, the positive muons and pions – all lighter than the 20-inch PMTs. These experiments were able proton – there was little reason to question Highlights The Super-Kamiokande to push the lower limits on the proton lifetime The proton spin crisis the proton’s stability. As Maurice Goldhaber experiment in Japan has set the highest to > 1032 years and so discount the viability of famously pointed out, were the proton lower limit for proton decay. minimal SU(5) GUTs. Among many misconceptions in the ab L ferson Jef DOE’s wide kinematic range. Nevertheless, it seems lifetime to be less than 1016 years we should However, in 1987 IMB and Kamiokande description of the proton presented in unlikely that all of the missing spin is in feel it in our bones, because our bodies would had set out conditions that could yield the II achieved greater fame by each detecting undergraduate physics lectures is the origin gluons, and the puzzle is not yet solved. be lethally radioactive. In 1954 he improved on observed particle– asymmetry a handful of neutrinos from the supernova of the proton’s spin. When we tell students What could the origin of the remaining this estimate. Arguing that the disappearance of the universe. One of these was that baryon SN1987a. Kamiokande II was already studying about the three quarks in a proton, we usually ~50% of the proton’s spin be? The answer of a nucleon would leave a nucleus in an conservation is only approximate and could solar and atmospheric neutrinos, but it was say that its spin (equal to one half) comes from may lie in the orbital angular momentum excited state that could lead to fission, he have been violated during the expansion phase its successor, Super-Kamiokande, that the arithmetic of three spin-½ quarks that of both the quarks and the gluons, but it is used the observed absence of spontaneous of the early universe. The interactions that went on to make pioneering observations of align themselves such that two point “up” difficult to measure this directly. Orbital fission in232 Th to calculate a lifetime for bound could violate baryon conservation would allow atmospheric and solar neutrino oscillations. and one points “down”. However, as shown angular momentum is certainly connected nucleons of > 1020 years, which Georgy Flerov the proton to decay, but Sakharov’s suggested And it is Super-Kamiokande that currently in measurements of the spin taken by quarks to the transverse structure of the proton. The soon extended to > 3 × 1023 years. proton lifetime of > 1050 years provided little has the highest lower-limit for proton decay: in deep-inelastic-scattering experiments in Illuminating The 12 GeV CEBAF accelerator partons’ transverse momentum must also Goldhaber also teamed up with Fred Reines encouragement for experimenters. This all 1.6 × 1034 years for the decay to e+π0. which both the lepton beam and the proton at Jefferson Lab may shed light on the source of be considered, and there is the transverse and Clyde Cowan to test the possibility of changed around 1974, when proposals for Today, the theoretical development of GUTs target are polarised, this is not the case. Rather, the proton’s missing spin. position of the partons, and the transverse, directly observing proton decay using a grand unified theories (GUTs) came along. continues, with predictions in some models as first revealed in results from the European as opposed to longitudinal, spin. Multi- 500 l tank of liquid scintillator surrounded GUTs not only unified the strong, weak and of proton lifetimes up to around 1036 years. Muon Collaboration in CERN’s North Area in proton–proton scattering, to determine dimensional measurements of transverse by 90 photomultiplier tubes (PMTs) that electromagnetic forces, but also closely Future large neutrino experiments – such 1987, the quarks account for less than a third of where the missing spin comes from. It is now momentum distributions and generalised was designed originally to detect reactor linked quarks and leptons, allowing for non- as DUNE, Hyper-Kamiokande and JUNO – the total proton spin. This was nicknamed the established that about 30% of the proton spin parton distributions can give access to orbital neutrinos. They found no signal, indicating conservation of . In particular, feature proton decay among their goals, with proton’s “spin crisis”, and attempts to fully is in the valence quarks. Intriguingly, this is angular momentum. Such measurements that free protons must live for > 1021 years and the minimal SU(5) theory of Howard Georgi the possibility of extending the limits on the resolve it remain the goal of experiments today. made up of +65% from up-valence and –35% are underway at Jefferson Laboratory, and bound nucleons for > 1022 years. By 1974, in a and Sheldon Glashow led to predicted proton lifetime to 1035 years. So the study Physicists had to develop cleverer from down-valence quarks. The sea seems to are also a core part of the future Electron-Ion cosmic-ray experiment based on 20 tonnes of lifetimes for the decay p → e+π0 in the region of proton stability goes on, continuing the experiments, for example looking at semi- be unpolarised, and about 20% of the proton’s Collider programme. liquid scintillator, Reines and other colleagues of 1031±1 years – not so far beyond the observed symbiosis with neutrino research. inclusive measurements of fast pions and spin is in gluon polarisation, though it is not had pushed the proton lifetime to > 1030 years. lower limit of around 1030 years. kaons in the final state, and using polarised possible to measure this accurately across a Amanda Cooper-Sarkar University of Oxford. Meanwhile, in 1966, Andrei Sakharov This provided the justification for dedicated Chris Sutton former CERN Courier editor.

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Fig. 2. The Fig. 3. The structure of the ® 1.2 1.2 FAST SDD momentum In 1/x saturation proton as a function of scale, distributions (PDFs) Q2, and fractional 1.0 1.0 Cooper-Sarkar A Count Rate = >1,000,000 CPS of all flavours of the momentum, x. The number of s partons at two scales partons increases with Q2, 0.8 0.8 g/10 (Q2 = 10 GeV 2, left, and but they have less The True State-of-the-Art MMHT14, source: arXiv:1412.3989 source: MMHT14, ) )

2 u 2 4 2 g/10 ν c 10 GeV , right). momentum. The number of 0.6 0.6 • New in-house manufacturing uν These curves are dilute system partons also increases as x xf(x, Q xf(x, Q b deduced from NNLO decreases, to the point where • Lower noise 0.4 0.4 d QCD fits to global the population is so dense • Lower leakage current ν d s ν hard-scattering non-perturbative region that gluon recombination • Better charge collection 0.2 c d– 0.2 – data, with may lead to saturation. At –u u – d 2 uncertainties arising low Q the strong coupling αs Compatible with EPICS tools & libraries 0 0 from experimental is so large that reliable 0.0001 0.001 0.01 0.1 1.0 0.0001 0.001 0.01 0.1 1.0 25 mm2 FAST SDD® 55Fe Spectrum errors and model 2 perturbative calculations are x x In Q 25 mm2 FAST SDD® assumptions. not possible. 800,000 230K, Tpk = 8 µs 1,000,000 Peak to 1 keV background Mn Kα 26,000:1 100,000 top quark–antiquark pair production. Measurements of the Mn Kβ Solving the proton-radius puzzle 600,000 W-boson mass or the weak mixing angle will be improved 10,000 CREMA collaboration/PSI

How big is a proton? Experiments during of the proton radius in muonic and electronic by precision measurements of W and Z-boson production in COUNTS 400,000 122 eV FWHM 1,000 the past decade have called well-established spectroscopy,” says Krzysztof Pachucki of previously unexplored kinematic regions, and strangeness 100 measurements of the proton’s radius into CODATA TGFC and the University of Warsaw. can be further probed by measurements of these bosons in 200,000 question – even prompting somewhat outlandish But what of the discrepancy between association with heavy quarks. We also look forward to pos- 10 suggestions that new physics might be at play. spectroscopic and scattering experiments? sible future developments such as a Large Hadron-Electron 0 1 0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 Soon-to-be-published results promise to settle The calculation of the RMS proton radius using Collider or a Future Circular Electron Hadron Collider – not Energy (keV) the proton-radius puzzle once and for all. scattering data is tricky due to the proton’s least because new kinematic ranges continue to reveal more Resolution vs Peaking Time Contrary to popular depictions, the proton recoil, and analyses must extrapolate the form about the structure of QCD in the high-density regime. 180 25 mm2 2 does not have a hard physical boundary like factor to a scale of Q = 0. Model uncertainties In fact the HERA data already give hints that we may 170 a snooker ball. Its radius was traditionally can therefore be reduced by performing be entering a new phase of QCD at very low x, where the Standard SDD deduced from its charge distribution via On target CREMA’s target chamber. scattering experiments at increasingly low gluon density is very large (figure 3). Such large densities 160 electron-scattering experiments. Scattering scales. Measurements may now be aligning ® could lead to nonlinear effects in which gluons recombine. 150 FAST SDD from a charge distribution is different from of a muon orbiting a proton. As the with a lower value consistent with the latest When the rate of recombination equals the rate of gluon scattering from a point-like charge: the muon is 200 times heavier than the electron, its results in electronic and muonic spectroscopy. splitting we may get gluon saturation. This state of matter 140 on (eV FWHM @ 5.9 keV) @ 5.9 FWHM on(eV ti extended charge distribution modifies the Bohr radius is 200 times smaller, and the QED In 2017 Miha Mihovilovic of the University of has been described as a colour glass condensate (CGC) 130 Resolution (eV FWHM @ 5.9 keV) differential cross section by a form factor (the correction due to overlapping electron clouds Mainz and colleagues reported an interestingly and has been further probed in heavy-ion experiments at Resolu 120 Fourier transform of the charge distribution). is more substantial. CREMA observed an RMS low value of 0.810(82) fm using the Mainz the LHC and at RHIC at Brookhaven National Laboratory. 0.000 1.00 1 2.00 2 3.00 3 4.00 4 5.00 5 Peaking Time (μs) For a proton this takes the form of a dipole with proton radius of 0.8418(7) fm, which was five Microtron, and results due from the Proton The higher gluon densities involved in experiments with Peaking Time (µs) respect to the scale of the interaction, and an sigma below the world average, giving rise to Radius Experiment (pRad) at Jefferson Lab will heavy nuclei enhance the impact of nonlinear gluon inter- exponentially decaying charge distribution as the so-called “proton radius puzzle”. The team access a similarly low scale with even smaller actions. Interpretations of the data are consistent with Options: a function of the distance from the centre of the confirmed the measurement in 2013, reporting uncertainties. Preliminary pRad results t h e CG C b ut n o t d e fi n it i v e. A f ut u r e e le c t r o n–io n c ol l id e r, • 25 mm2 active area collimated to 17 mm2 proton. Scattering experiments found the root a radius of 0.8409(4) fm. These observations presented in October 2018 at the 5th Joint such as that currently proposed in the US (CERN Courier • 70 mm2 collimated to 50 mm2 mean square (RMS) radius to be about 0.88 fm. appeared to call into question the cherished Meeting of the APS Division of October 2018, p31), will go further, enabling complete • Windows: Be (0.5 mil) 12.5 µm, or Since the turn of the millennium, a modest principle of lepton universality. and the Physical Society of Japan in Hawaii tomographic information about the proton and allowing C Series (Si3N4) increase in precision on the proton radius was More recent measurements have reinforced indicate a proton radius of 0.830(20) fm. us to directly connect fundamental partonic behaviour to • TO-8 package fits all Amptek configurations made possible by comparing measurements the proton’s slimmed-down nature. In 2016 These electron-scattering results will be the proton’s “bulk” properties such as its mass, charge of transitions in hydrogen with quantum CREMA reported a radius of 0.8356(20) fm by complemented by muon-scattering results and spin. Meanwhile, table-top spectroscopy experi- • Vacuum applications electrodynamics (QED) calculations. Since measuring the in muonic deuterium from the COMPASS experiment at CERN, and ments are shedding new light on a seemingly mundane atomic energy levels need to be corrected due (the bound state of a muon orbiting a proton the MUSE experiment at PSI. yet key property of the proton: its radius (see “Solving to overlapping electron clouds in the extended and a neutron). Most interestingly, in 2017 Axel For now, says Pachucki, the latest CODATA the proton-radius puzzle”). charge distribution of the proton, precise Beyer of the Max Planck Institute of Quantum recommendations published in 2016 list the Together with the neutron, the proton constitutes prac- measurements of the transition frequencies Optics in Garching and collaborators reported higher value obtained from electron scattering tically all of the mass of the visible matter in the universe. provide a handle on the proton’s radius. A a similarly lithe radius of 0.8335(95) fm from and pre-2015 hydrogen-spectroscopy A hundred years on from Rutherford’s discovery, it is clear combination of these measurements yielded observations of the 2S–4P transition in ordinary experiments. If the latest experiments that much remains to be learnt about the structure of this the most recent CODATA value of 0.8751(61) fm. hydrogen. This low value is confirmed by soon- continue to line up with the slimmed-down complex and ubiquitous particle.  The surprise came in 2010, when the CREMA to-be-published measurements of the 1S–3S radius of CREMA’s 2010 result, however, the 40 Years of collaboration at the Paul Scherrer Institute transition by the same group, and of the 2S–2P proton radius puzzle may soon be solved, and Further reading Products for Your Imagination The HERA data (PSI) in Switzerland achieved a 10-fold transition by Eric Hessels of York University, the world average revised downwards. R Devenish and A Cooper-Sarkar 2004 Deep Inelastic ® improvement in precision via the Lamb shift Canada, and colleagues. “We can no longer speak Scattering (Ox ford Universit y Press). already give hints AMPTEK Inc. [email protected] (the 2S–2P transition) in muonic hydrogen, the about a discrepancy between measurements Mark Rayner CERN. J Campbell et al. 2018 The Black Book of Quantum of a new phase Chromodynamics (Ox ford Universit y Press). of QCD www.amptek.com

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cooling systems. earching for the decay μ+ → e+γ is like looking for a a n d a p h o t o n, it w o u ld b e t h e fi r s t e v id e n c e o f fl a v o u rvio - THE AUTHORS Safety on critical applications. n e e d le i n a h a y s t a c k t h e s i z e o f t h e G r e at P y r a m id o f lation with charged leptons, and unambiguous evidence Angela Papa S Giza. This simile-stretching endeavour is the task for new physics. Paul Scherrer Supplier for more than of the MEG II experiment at the Paul Scherrer Institute Lepton-flavour conservation is a mainstay of every Institute, (PSI) in Villigen, Switzerland. MEG II is an upgrade of the introductory particle-physics course, yet it is merely a Switzerland, 40 years at CERN and other Francesco Renga previous MEG experiment, which operated from 2008 to s o-c a l le d a c c id e nt a l s y m m e t r y o f t h e St a n d a rd M o d e l (S M). INFN Rome, Italy 2013. A l l e x p e r i m e nt a l d at a s o f a r a r e c o n s i s t e nt w it h muo n Un l i k e g a u g e s y m m e t r ie s, it a r i s e s b e c a u s e o n l y m a s s le s s particle accelerators. www.exirbroadcasting.com and Yusuke decays that conserve lepton flavour by the production of left-handed neutrinos are included in the model. The cor- Exir Broadcasting AB Uchiyama www.eletta.com two appropriately flavoured neutrinos. Were MEG II to r e s p o n d i n g m a s s a n d i nt e r a c t io n t e r m s o f t h e L a g r a n g i a n The University of [email protected] Industrigatan 17 - SE-242 31 Hörby - Sweden +46 415 30 14 00 - [email protected] observe the neutrinoless decay of the muon to a positron can therefore be simultaneously diagonalised, which means Tokyo, Japan.

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FEATURE MEG II EXPERIMENT FEATURE MEG II EXPERIMENT

71 lepton-flavour violation in the SM” box). A data sample of Fig. 2. Illustration 41

1 muo n s a s l a r g e a s t h e nu m b e r o f pr o t o n s i n t h e E a r t h wo u ld of a μ+ → e+γ event μ → eγ not be enough to see such an improbable decay. Charged liquid xenon photon detector in MEG II. 10–2 μN → eN lepton-flavour violation is therefore a clear signature of MEG II Collaboration Riv. Nuovo Cimento μ → eee new physics with no SM backgrounds. superconducting magnet 10–4 Finding the needle γ 10–6 The search requires an intense source of muons, and d e t e c t or s c a p a ble o f r e c o n s t r uc t i n g t h e k i n e m at ic s o f t h e μ+ pixelated timing counter 10–8 muon’s decay products with high precision. PSI offers the e+

limit world’s most intense continuous muon beams, deliver- 10–10 ing up to 108 muons per second. MEG II (previously as + + MEG) is designed to search for μ → e γ b y s t o p pi n g p o s it i v e muon stopping target 10–12 muons on a thin target, and looking for positron–photon pairs from muon decays at rest. This method exploits the radiative decay counter cylindrical drift chamber 10–14 t wo-b o d y k i ne m at ic s of t he d e c a y t o d i s c r i m i n at e s i g n a l events from the backgrounds, which are predominantly t he r ad iat ive muon de c ay μ+ → e+ ν ν– γ and the accidental 10–16 e μ time coincidence of a positron and photon produced by unprecedented ~2% calorimetric resolution at energies as be completed, with the possibility of collecting the first + + 1940 1950 1960 1970 1980 1990 2000 2010 2020 2030 different muon decays. low as 52.8 MeV – the energy of the photon in a μ → e γ decay. physics data. The experiment is then expected to run for + + year In the late 1990s, when the first MEG experiment was The LXe detector provides a high-resolution measurement three years to uncover evidence for the μ → e γ decay if b e i n g d e s i g n e d, t h e or i s t s a r g ue d t h at t h e μ+ → e+γ branching of the position and timing of the photon conversion, precise the branching ratio is around 10–13 or set a limit of 6 × 10–14 Fig. 1. Limits on the branching ratios of flavour-violating muon decays. In the mid 1950s, r at io could be as h ig h as 10 –12 to 10 –14, based on supersy m- to a few millimetres and approximately 70 ps. The positrons on its branching ratio. experiments using stopped pion beams improved on previous cosmic-ray limits, before metry arising at the TeV scale. Twenty years later, MEG are reconstructed in a magnetic spectrometer instrumented experiments with stopped muons allowed further improvements in the mid 1970s. The has excluded branching ratios above 4.2 × 10–13 (figure 1), with drift chambers for tracking, and scintillator bars for New directions current best limits in each channel were set by the MEG, SINDRUM-II and SINDRUM a n d s up e r s y m m e t r ic p a r t ic le s r e m a i n u n d i s c o v e r e d at t h e timing. A peculiarity of the MEG spectrometer is a non-uni- In the meantime, PSI researchers are investigating the collaborations, respectively, each at PSI. LHC. Nevertheless, since charged lepton-flavour-violat- form magnetic field, diminishing from 1.2 T at the centre p o s s i bi l it y o f b u i ld i n g n e w b e a m l i n e s w it h 10 9 or e v e n 10 10 ing processes are sensitive to the virtual exchange of new of the detector to 0.5 T at the extremities. The gradated muons per second to allow experimenters to probe even that interactions always conserve lepton flavour. This is p a r t ic le s, w h i le n o t r e q u i r i n g t h e i r c r e at io n a s at t h e L HC, field prevents positrons from curling too many times. This smaller branching ratios. How could a future experiment n o t t h e c a s e i n t h e q u a r k s e c t or, a n d a s a r e s u lt q u a r k fl a- they can probe new physics models (supersymmetry, extra avoids pileup in the detectors and makes positrons of the cope with such high rates? Preliminary studies are inves- vour is not conserved in weak interactions. Since lepton dimensions, leptoquarks, multi-Higgs, etc) up to mass same momentum curl with the same radius, independent tigating a system where photons are converted into pairs flavour is not considered to be a fundamental symmetry, s c a le s o f t h o u s a n d s o f TeV. S c a le s s uc h a s t h e s e a r e n o t o n l y of their emission angle, thus simplifying the design and of electrons and positrons, and reconstructed in a tracking most extensions of the SM predict its violation at a level u n r e a c h a ble at t h e L HC, b ut a l s o at n e a r-f ut u r e a c c e le r at or s. operation of the tracking system. device. This solution, which has already been exploited that could be observed by state-of-the-art experiments. T h e M E G c ol l a b or at io n t h e r e for e d e c id e d t o up g r a d e t h e Following a major overhaul that was begun in 2011, all previously by the MEGA experiment at Los Alamos National Indeed an extension of the SM is already required to detectors with the goal of improving the sensitivity of the the detectors have now been upgraded. Silicon photo- Laboratory, could also improve the photon resolution. include the tiny neutrino masses that we infer from neu- experiment by a factor of 10. The new experiment, which multipliers custom-modified for sensitivity to the ultra- At the same time, other experiments are searching for t r i n o o s c i l l at io n s. I n t h i s e x t e n s io n, n e ut r i n o o s c i l l at io n s adopts the same measurement principle, is expected to violet LXe scintillation light have replaced conventional c h a r g e d le p t o n-fl a v o u r v iol at io n i n o t h e r c h a n n e l s. M u3e, induce charged lepton-flavour-violating processes but with start taking data at the end of 2019 (figure 2). Photons are photomultipliers on the inner face of the calorimeter. also at PSI, will search for μ+ → e+e+e– decays. The Mu2e and the branching ratio for μ+ → e+γ emerging to be only 10 –54, re c on s t r uc te d b y a l iqu id xe non (L Xe) de te c tor te c h nolog y Small scintillating tiles have replaced the scintillating COMET experiments, at Fermilab and J-PARC, respectively, which cannot be accessed experimentally (see “Charged t h at w a s pio n e e r e d b y t h e M E G c ol l a b or at io n, a c h ie v i n g a n bars of the positron-timing detector to improve timing will search for muon-to-electron conversion in the field of and reduce pileup. The main challenge when upgrading a nucleus. These processes are complementary to μ+ → e+γ, the drift chambers was dealing with high positron rates. allowing alternative scenarios to be probed. At the same Charged lepton-flavour violation in the SM – a very small neutrino oscillation experiment Here, the need for high granularity had to be balanced by time, collider experiments such as Belle II and LHCb are – – keeping the total amount of material low. This reduces both working on studies of lepton-flavour violation in tau decays. The presence of only massless and small. In most neutrino oscillation νμ → νe has to occur at multiple scattering and the rate of positrons annihilating LHCb researchers are also testing lepton universality, which left-handed neutrinos in the oscillation experiments, a an energy scale E ~ mw, over an W+ in the material, and contributions to the coincident-photon holds that the weak couplings are the same for each lepton Standard Model (SM) gives rise γ neutrino is created in a extremely short distance of background in the calorimeter. The solution was the use fl a v o u r (s e e p33). A s t h e or i s t s o f t e n s t r e s s, a l l t h e s e a n a lyse to the accidental symmetry of charged-current interaction and L ~ 1/mw. Considering only two lepton-flavour conservation – yet observed in a later interaction neutrino species with masses of extremely thin 40 and 50 μm silver-plated aluminium are strongly complementary both with each other and with × wires, 20 μm gold-plated tungsten wires, and innovative direct searches for new particles at the LHC. neutrino oscillation experiments + + via the creation of a charged m1 and m2, the probability for Charged μ νμ νe e have observed neutrinos changing lepton of the corresponding the oscillation is proportional assembly techniques. All the detectors’ resolutions were Ever since the pioneering work of Conversi, Pancini and lepton- 2 2 2 improved by a factor of around two with respect to the MEG Piccioni, muons have played a crucial role in the develop- flavour in-transit from sources flavour in the detector. to sin [(m 1 – m 2) L / 4E]. Hence, flavour- + + experiment. The MEG II design also includes a new detec- ment of particle physics. When I I Rabi exclaimed “who as far away as the Sun and as as a neutrino travels, and the μ → e γ may proceed in a the μ → eγ branching ratio is violating near as a nuclear reactor. Such wavefunction becomes a mixture similar way, but where the same suppressed by the tiny factor tor to veto photons coming from radiative muon decays, ordered that?”, he surely did not imagine that 80 years later 2 2 22 -49 processes (m1 - m)2 /mW)1K 0 . improved calibration tools and new trigger and data-ac- the lightest unstable would still be a neutral lepton-flavour violation of the flavour eigenstates, rather W boson is involved in both the can probe implies that neutrinos have tiny than the unique original flavour, creation and destruction The exact calculation, quisition electronics to cope with the increased number focus of cutting-edge research.  new physics masses and that their flavour as would remain the case for truly of the neutrino, and the including the most recent of readout channels. The improved detector performance models up eigenstates are distinct from their massless neutrinos. neutrino oscillates in between estimates of the neutrino will allow the muon beam rate to be more than doubled, Further reading 7 7 to mass scales mass eigenstates. Phases develop The effect on charged lepton- (see figure above). mixing matrix elements, gives from 3.3 × 10 to 7 × 10 muons per second. MEG Collaboration 2016 Eur. Phys. J. C 76 434. between the mass eigenstates flavour violation is subtle In this process, the neutrino BR(μ → eγ) ~ 10–54. The detectors were installed and tested in the muon MEG II Collaboration 2018 Eur. Phys. J. C 78 380. of thousands beam in 2018. In 2019 a test of the whole detector will L Calibbi and G Signorelli 2018 Riv. Nuovo Cimento 41 71. of TeV

46 CERN COURIER MAY/JUNE 2019 CERN COURIER MAY/JUNE 2019 47

CCMayJun19_MEG-II_v4.indd 46 17/04/2019 09:24 CCMayJun19_MEG-II_v4.indd 47 17/04/2019 09:24 CERNCOURIER www. V o l u m e 5 9 N u m b e r 3 M a y /J u n e 2 0 1 9 Cryogenic Components CERNCOURIER.COM ■ Cryogenic Control & Shut-off Valves ■ Quench Relief Valves & Current Leads OPINION ■ Single & Multi-Line Johnston Couplings ■ Check valves and associated products VIEWPOINT ■ Focusing on cryogenic temperatures below 100 K ■ Optimized design for low operating cost ■ Suitable to operate in high magnetic field and ionizing radiation Please visit us at our website: Building scientific resilience ■ Long maintenance intervals and simple www.weka-ag.ch KAOgania o artitsrn tion) it rend ist’s t r (a ion isat n a Org A SK service requirements Ne w p ol it ic a l l a nd s c ap es m a ke ■ More than 40 years of experience i nter n at ion a l org a n i s at ion s i n s c ie nce more v it a l t h a n e ver, a rg ues Joh n Womer sle y. Liquefaction of gases

Gas distribution systems ESS Brest-Litovsk, Utrecht, Westphalia… a t fi r s t s i g ht, i nt e r g o v e r n m e nt a l t r e a t i es Gas recirculation systems belong more to the world of Bismarck WEKA AG · Schürlistrasse 8 Hydrogen infrastructure and Napoleon than that of modern CH-8344 Bäretswil · Switzerland science. Yet, in March this year we Space infrastructure Phone +41 43 833 43 43 celebrated the signing of a new treaty Plasma & fusion research Fax +41 43 833 43 49 establishing the world’s largest radio [email protected] · www.weka-ag.ch telescope, the Square Kilometre Array (SKA). Why use a tool of 19th-century John Womersley great-power politics to organise a 21st is director-general cent ur y big-science project? of the European ARCA Flow Group worldwide: Large-science projects like SKA require Competence in valves, pumps & cryogenics Spallation Source. multi-billion budgets and decades-long commitment. Their resources must come from many countries, and they Upwards On 12 March SKA became the latest intergovernmental scientific organisation. need mutual assurance for all contribu- tors that none will renege. The board for now be essential for their success. nationalism as the problem, but the issue SKA, of which I was formerly chair, rapidly In fact, US participation in international is more one of populism – and by being concluded that only an intergovernmental organisations is often an issue because international we merely seem remote. or g a n i s a t i o n c o u l d g i v e t h e n e c e s s a r y s t a- it requires senate approval. The last We a re use d to sp ea k i ng ab out out reac h, bi l it y. It i s a v e r y E u r o p e a n a p pr o a c h, b or n time this happened for a science project b ut w e a l s o n e e d t o t h i n k s e r io u s l y a b o ut o f o u r n e e d t o br i n g t o g e t h e r m a n y s m a l l e r was the ITER fusion experiment, which “i n-r e a c h” w it h i n o u r o w n c o u nt r i e s a n d count ries. But it is fle x ible and resilient. today is ma k ing good prog ress but had a regions, to engage better with groups such Of course there are other ways to do r o c k y s t a r t. T h e EU i s o n e o f I T E R’s s e v e n as Trump voters and Brexit supporters. DLC, Boron Doped Hybrid Meet us this. A European Research Infrastructure member entities and its involvement is There’s also the risk that too much sta- at Consortium (ERIC) is a lighter weight, f a c i l it ate d v i a EU RO f u sion – one of e i g ht bility can become rigidity. Organisations and Graphene Stripper Foils IPAC19 faster way to set up an intergovernmental European intergovernmental research like SKA or ESS aim to provide room for research organisation and is the model organisations that are members of EIRO- n e g o t i a t io n a n d for s u b s t a nt i a l a m o u nt s t h a t w e h a v e u s e d for t h e E u r o p e a n S p a l- forum. Most were established decades ago, o f c o nt r i b ut io n s t o b e m a d e i n-k i n d. T h e y l a t i o n S o u r c e (E S S) i n S w e d e n. T h e E R IC and their stable structure has helped them a r e f r e e o f c o m m it m e nt s s u c h a s p e n s i o n is part of European Union (EU) legis- invest in major new facilities such as ESO’s s c h e m e s a n d, i n t h e c a s e o f SK A, m e m b e r- lation and provides many of the bene- European E x t remely Large Telescope. ship levels are tied to t he size of a coun- fits in VAT and purchasing rules that an So i nter nat iona l t reat y-based sc ience try’s astronomy community and not to international convention or treaty would, organisations are great for delivering GDP. Were a future, global project like a without a convoluted approval process. bi g-s c i e n c e pr oj e c t s, w h i l e a l s o pr o m o t- Future Circular Collider to be hosted at Once the UK (one of the 13 ESS member ing understanding between the science CERN, a purpose-built intergovernmental nations) withdraws from the EU, it will c o m m u n it i e s o f d i ffe r e nt c o u nt r i e s. I n t he agreement would surely be the best way need legislation to recognise the status aftermath of the Second World War that to manage it. CERN is the archetype of of ERICs, just as non-EU Switzerland and w a s r e a l l y i m p or t a nt, a n d w a s a fo u n d i n g intergovernmental organisations in sci- Nor w ay have done. motivation for CERN. More recently, t he ence, and offers great stability in the face Research facilities can also be run by SESAME light source in Jordan adopted of political upheavals such as Brexit. Its or g a n i s a t io n s w it h o ut a n y i nt e r g o v e r n- t h e C E R N m o d e l t o br i n g t h e M i d d l e E a s t’s challenge today is to think outside the box. CERN offers mental authority: charities, not-for- scientific communities together. The same applies to all big projects in great stability pr o fit c o m p a n i e s or u n i v e r s it y c o n s or t i a. Today the word faces new political physics today. Our future prosperity and Micromatter Technologies Inc. in the face This may seem quick and agile, but it is challenges, and international treaties a bi l it y t o a d d r e s s m aj or c h a l l e n g e s d e p e n d r i s k y. For e x a m pl e, t h e l a r g e US t e l e s c o p e don’t do much to address the growing on investments in large, cutting-edge of political pr oj e c t s T M T a n d G M T a r e u n i v e r s it y-l e d gap between angry, disenfranchised research infrastructures. Intergovern- upheavals and have been able to get started, but it voters and an educated, internationally mental organisations provide the frame- such as Brexit seems that US federal involvement will minded “elite”. We scientists often see work for t hose invest ments to flourish.

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www.hsr.li INTERVIEW

DESY’s astroparticle aspirations

Christian Stegmann, director of DESY’s ne wly est abl i she d resea rc h d iv i sion for a st ropa r t ic le phy sic s, desc r ib es t he a mbit ious pl a n s a head i n t h i s v ibr a nt fie ld. EYGBrn Bor DESY/G What is your definition of astroparticle physics? There is no general definition, but let me try nevertheless. Astroparticle physics addresses astrophysical questions through particle-physics experimental methods and, vice versa, questions from particle physics are addressed via astronomical methods. Leading vacuum technology for This approach has enabled many scientific breakthroughs and opened new w indows to t he universe in recent new technologies years. In Ger many, what drives us is the question of the influence of neutrinos and high-energy processes in the development of our universe, and the direct search for dark matter. There are differences to particle physics both in the physics questions and in t he approac h: we obser ve high-energy radiation from our cosmos or rare events in underground laboratories. But t here are also many similarities between the two fields Clear vision Christian Stegmann became director of astroparticle physics in January. of researc h t hat ma ke a fr uit f ul Wideband Microwave Signal Generators exchange possible. developed into an independent field. generation gamma-ray observatory Standalone and programmable signal generators that fit Seven years ago, I became head of the Cherenkov Telescope Array (CTA). in your hand. Portable, affordable, reliable. What was your path into the t he DESY site in Zeut hen near Berlin. The campus in Zeut hen w ill host t he Wideband 55 - 24,000MHz Low Phase Noise astroparticle field? My task is to develop DESY and in CTA Science Data Management Cent re USB & Panel Control Optional Ethernet Port I grew up in particle physics: I did par t icular t he Zeut hen site into an and we are par t icipat ing in almost al l 10Hz Frequency Step Size Ultra-Precision Reference my PhD on b-physics at t he OPA L international centre for astroparticle currently operating major gamma-ray SCPI Automation Friendly Stepped Power Control experiment at CERN’s LEP collider physics. The new research division is e x periments to prepare for t he CTA Intuitive PC Software Vernier Power Control and then worked for a few years on the also a recog nit ion of t he work of t he science har vest. A g row ing t heoret ical Only $199900 HERA-B experiment at DESY. I was not people in Zeut hen and an impor tant group supports all experimental only fascinated by par t icle physics, but step for t he f ut ure. act iv it ies. The combinat ion of high- also by t he inter nat ional cooperat ion energy neutrinos and gamma rays at CERN and DESY. Par t icle physics W hat are DESY’s strengths in offers unique opportunities to study and astroparticle physics overcome astroparticle research? processes at energ ies far beyond t hose borders, and this is a feat that is A st ropar t icle physics beg an in Zeut hen reachable by human-made particle Mixers With Integrated Wideband Programmable par t icularly impor tant ag ain today. with neutrino astronomy around I w a s not on ly accelerators. Local Oscillators RF Step Attenuators Around 20 years ago I switched to 20 years ago. It has evolved from fascinated 2.5, 6.0, 12, and 20GHz Models Up to 90dB of attenuation Low Conversion Loss & Leakage Exceptionally low insertion loss ground-based gamma astronomy. I humble beginnings, from a small by particle Why did DESY establish a Wide RF and IF Bandwidths USB powered & controlled became fascinated in understanding sta ke in t he La ke Bai kal e x periment physics, but dedicated division? 6, 12, and 18GHz frequency ranges Internal Reference Frequency how nat ure manages to accelerate to a major role in t he k m3-sized A dedicated research division Conveniently USB powered & Controlled Optional Ethernet Control also by the particles to such enormous energies IceCube array deep in the Antarctic underlines the importance of Starting at $50900 Starting at $39500 international as we see them in cosmic rays and ice. Having entered high-energy ast ropar t icle physics in general and what role they play in the development gamma-ray astronomy only a few cooperation in DESY’s scient ific prog ramme in ds instruments of our universe. I experienced very years ago, t he Zeut hen locat ion is at CERN particular, and offers promising WWW.DSINSTRUMENTS.COM closely how astroparticle physics has now a driv ing force behind t he ne x t- a nd DES Y opportunities for the future.

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OPINION INTERVIEW

Astroparticle physics with cosmic messengers has experienced a tremendous development in recent years. The discovery of a large number of gamma-ray sources, the observation of cosmic neutrinos in 2013, the direct detection of gravitational waves in 2015, the observation of the merger of two neutron stars with more than 40 observatories worldwide triggered by its gravitational waves in August 2017, and the simultaneous observation of neutrinos and high-energy gamma radiation from the direction of a blazar the following month are just a few prominent examples. We are on the threshold of a golden age of multi- messenger astronomy, with gamma rays, neutrinos, gravitational waves and cosmic rays together promising Contact point The winning design for DESY’s new CTA Science Data Management Centre by Heinle Wischer completely new insights into the und Partner (Berlin) and Ulrich Krüger Landschaftsarchitekten (Dresden). origins and evolution of our universe. prog ressing and t he first steps for investments of more than Magnets and coils What are the division’s scale the further upgrade of IceCube have one billion Euros, requiring High quality magnets and coils, designed and manufactured by Swedish engineering in and plans? been taken. The funding for the next coordination at European and order to provide the best solutions for all your needs! We take pride in close collaborations The next few years will be exciting generation of gravitational-wave international level. With the with the customer, whether it is for research or industry. for us. We have just completed an experiments, the Einstein Telescope Astroparticle Physics European  architectural competition, new in Europe, is not yet secured. We Consortium (APPEC) we have taken a SCANDITRONIX-MAGNET.SE buildings will be built and the entire are currently discussing a possible step towards improved coordination. campus will be redesigned in the participation of DESY in gravitational- DESY is one of the founding members coming years. We expect well over wave astronomy. Multi-messenger of APPEC and I have been elected 350 people to work on the Zeuthen astronomy promises a breathtaking vice-chairman of the APPEC general campus, and hosting the CTA data amount of new discoveries. However, assembly for the next two years. In centre will make us a contact point for the findings will only be possible this area, too, we can learn something SUPERCON, Inc. astroparticle physicists globally. In if, in addition to the instruments, from particle physics and are very addition to the growth through CTA, we the data are also made available in a pleased that CERN is an associate Superconducting Wire and Cable are e x panding our scient ific por t folio to form that allows scientists to jointly member of APPEC. include radio detection of high-energy analyse the information from the Standard and Specialty designs are available to meet your most demanding neutrinos and increased activities various instruments. DESY will play What implication does the update of in astronomical-transient-event an important role in all these tasks – the European strategy for particle superconductor requirements. follow-up. We are also establishing from the construction of instruments physics have for your field? close cooperation with other partners. to the training of young scientists. European astroparticle physics SUPERCON, Inc. has been producing niobium-based superconducting wires and cables for half a century. Together with the Weizmann Institute But we will also be involved in the provides a wide range of input to the original SUPERCON in Israel, the University of Potsdam development of the research-data the European Strategy for particle We are – the world’s first commercial producer of niobium-alloy based wire and and the Humboldt University in Berlin, infrastructure required for multi- physics, from concrete proposals for cable for superconducting applications. we are currently establishing an messenger astronomy. experiments to contributions from international doctoral school for multi- national committees for astroparticle Standard SC Wire Types Product Applications messenger astronomy funded by the How would you describe the physics. The contribution to the NbTi Wires Magnetic Resonance Imaging Helmholtz Association. astroparticle physics landscape? construction of the Einstein Telescope The community in Europe is growing. deserves special attention, and my Nb3Sn —Bronze Nuclear Magnetic Resonance How can we realise the full potential Not only in terms of the number personal wish is that CERN will Nb3Sn —Internal Tin High Energy Physics of multi-messenger astronomy? of scientists, but also the size and coordinate the Einstein Telescope, as CuNi resistive matrix wires SC Magnetic Energy Storage Our potential lies primarily in variety of experiments. In many suggested in the contribution. With the Fine diameter SC Wires Medical Therapeutic Devices committed scientists who use their areas, European astroparticle physics LHC, CERN has again demonstrated creativity and ideas to take advantage is in transition from medium-sized in an outstanding way that it can Aluminum clad wire Superconducting Magnets and Coils of existing opportunities. For experiments to large research successfully implement major research Wire-in-Channel Crystal Growth Magnets years we have experienced a large infrastructures. CTA is the outstanding projects. With the first gravitational- Innovative composite wires Scientific Projects number of young people moving into We are on the example of this. The large number of w ave events, we saw only t he first astroparticle physics. We need new, threshold new scientists and the ideas for new flashes of a completely unknown part highly sensitive instruments and there of a golden research infrastructures show the of our universe. The Einstein Telescope “We deliver superconductivity!” is a whole series of outstanding project great appeal of astroparticle physics would revolutionise our new view of proposals waiting to be implemented. age of multi- as a young and e xcit ing field. The the world. CTA is being built, the upgrade of messenger proposed Einstein Telescope will cross Contact us at [email protected] the Pierre Auger Observatory is astronomy the threshold of projects requiring Interview by Matthew Chalmers editor. www.SUPERCON-WIRE.com

52 CERN COURIER MAY/JUNE 2019 ad.indd 1 28/03/2012 09:43

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Multi-messenger adventures NSF/LIGO/Sonoma State University/A Simonnet University/A NSF/LIGO/Sonoma State Introduction to Particle and Astroparticle Physics: Multimessenger Astronomy and its Particle Physics Foundations (2nd edn)

By Alessandro De Angelis and Mário Pimenta Springer

Recent years have seen enormous pro- gress in astroparticle physics, with the detection of gravitational waves, very-high-energy neutrinos, combined neutrino–gamma observation and the discovery of a binary neutron-star merger, which was seen across the electromag- together with astrophysics and cos- Mixed messages state of the art and the future prospects netic spectrum by some 70 observatories. mology, starting from experiments and Artist’s impression in a detailed way. Next, the “messengers These important advances opened a new observations. Written by experimental- of a neutron-star from the high-energy universe”, such and fascinating era for multi-messenger ists actively working on astroparticle merger producing as high-energy charged cosmic rays, astronomy, which is the study of astro- physics and with extensive experience gravitational gamma rays, neutrinos and gravitational nomical phenomena based on the coor- in sub-nuclear physics, it provides a uni- waves, bursts of waves, are explored. A final chapter is dinated observation and interpretation of fied view of these fields, reflecting the gamma rays and devoted to astrobiology and the relations disparate “messenger” signals. very rapid advances that are being made. swirling clouds of between fundamental physics and life. This book, first published in 2015, is The first eight chapters are devoted ejected material. This book offers a well-balanced now released in a renewed version to to the construction of the SM of particle introduction to particle and astropar- include such recent discoveries and to physics, beginning from the Rutherford ticle physics, requiring only a basic back- describe present research lines. experiment up to the discovery of the ground of classical and quantum physics. The Standard Model (SM) of particle Higgs particle and the study of its decay It is certainly a valuable resource that can physics and the lambda-cold-dark-mat- channels. The next chapter describes the be used as a self-study book, a reference ter theory, also referred to as the SM of SM of cosmology and the dark universe. or a textbook. In the preface, the authors cosmology, have both proved to be tre- Starting from the observational pillars of suggest how different parts of the essay mendously successful. However, they cosmology (the expansion of the universe, can serve as introductory courses on leave a few important unsolved puzzles. the cosmic microwave background and particle physics and astrophysics, and One issue is that we are still missing a primordial nucleosynthesis), it moves for advanced classes of high-energy ast- description of the main ingredients of on to a discussion about the origins and roparticle physics. Its 700+ pages allow the universe from an energy-budget per- the future of our universe. Astrophysical for a detailed and clear presentation of spective. This volume provides a clear evidence for dark matter is presented and the material, contain many useful ref- and updated description of the field, pre- its possible constituents and their detec- erences and include proposed exercises. paring and possibly inspiring students tion are discussed. A separate chapter is towards a solution to these puzzles. devoted to neutrinos, covering natural Giovanni Fiorentini INFN and The book introduces particle physics and man-made sources; it presents the University of Ferrara.

Rutherford scientific and personal milestones are UK and Canada) that characterised his described in great detail in the three- life bring Rutherford back to life. DVD documentary part documentary Rutherford, produced When it was still heresy to think that by Spacegirls Production Ltd in 2011. there existed objects smaller than an Spacegirls Production Ltd Accompanied by physics historian John atom, Rutherford was exploring the Professor Radium, the Atom Splitter, the Campbell, the viewer learns about this secrets of the invisible. During his first Crocodile. Each is a nickname pointing great scientist from his ordinary child- stay in Cambridge (UK), he discovered that to Ernest Rutherford, who made history hood as a “Kiwi boy” to his untimely uranium emits two types of radiation, by explaining radioactivity, discovering death in 1937. Historical reconstructions which he named alpha and beta. Then, s the proton and splitting the atom. All his and trips to the places (New Zealand, the continuing his research at McGill Uni-

CERN COURIER MAY/JUNE 2019 55

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v e r s it y (C a n a d a), h e d i s c o v e r e d t h a t r a d i- dral. He fired alpha particles at nitrogen scientists from war. o a c t i v it y h a s t o d o w it h t h e i n s t a bi l it y o f gas and obtained oxygen plus hydro- The name “Crocodile” came later, the atom. He was rewarded with the Nobel g e n, t hu s t h e e pit h e t o f t h e w orl d’s fi r s t from soviet physicist Pyotr Kapitza, as P r i z e i n C h e m i s t r y i n 1908, a n d c a l l e d P r o - “atom s pl it te r”. it is an animal that never turns back – or BESPOKE MULTIPIN INSTRUMENTATION PLATE fessor Radium after a comic book char- I n-b e t w e e n t h e s e bi g d i s c o v e r ie s, t h e perhaps a reference to Rutherford’s loud acter of that name. In those years, people d o c u m e nt a r y p oi nt s o ut t h a t R ut h e r for d voice that preceded his visits. The carving did not know the effects of radiation and blew tobacco smoke into his ionisation of a crocodile on the outer wall of the for Particle Accelerator Research and Development “r a d i o -t o o t h p a s t e” w a s a v a i l a bl e t o b u y. chamber, providing the groundwork Mond Laboratory at the Cavendish site, Then in Manchester (UK), he con- for modern smoke detectors, proposed c o m m i s s i o n e d b y K a pit z a, s t i l l r e m i n d s APPLICATION ducted the first artificial-induced a more accurate dating system for the Cambridge students and tourists of this nuclear reaction and described a new Earth’s age based on the rate of decay outstanding physicist. • Data and Signal Collection from Vacuum System model of the atom, where a proton is like of uranium atoms, and campaigned a fly in the middle of an empty cathe- for women’s opportunities and saving Letizia Diamante CERN. TECHNICAL SPECIFICATIONS PNPOMISC-2019-002-2 OPEN-PHO-M Quàntica • OD: 12” • Helium Leak Rate: 2.0 X 10-10 std.atm.cc/s Exhibition, Barcelona 9 April – 24 September • Electrical Ratings: Visit our new website! • 50 Pin Sub D: 500 V, 10 Amps Take a leap and enter, past the chalkboard w a l l fi l l e d w it h m a t h e m a t i c a l e q u a t i ons • DE SVH-10: 10 kV, 5 Amps ORDER ONLINE! written, erased and written again, into • DE COAX SMA: 700 V, 1 Amp www.mdcvacuum.com the darkened room of projected ques- tions where it all begins. What is reality? [email protected] Ho w d o w e d e s c r i b e n a t u r e? A n d for t h a t MATERIAL SPECIFICATIONS mat ter, what is science and what is ar t? • Flange: Stainless Steel +44 (0)1908 563267 Quàntica, which opened on 9 April at t h e C e nt r e d e C u lt u r a l C o nt e m p or à n i a d e • Ceramic: 95% Min Alumina B a r c e l o n a, i n v it e s y o u t o e x pl or e q u a nt u m physics t h roug h t he lens of b ot h a r t a nd CryogenFreeProbe#2-CERN 9/21/13 2:58 PM Page 1 s c i e n c e. C u r a t e d b y M ó n i c a B e l l o, h e a d o f Arts at CERN, and art curator José-Carlos Knowledge quantum physics at a very young age, teleportation. Above these is projected Mariátegui, with particle physicist José sharing would they perceive the world as we do? a scene from Star Trek, which popularised Ignacio Latorre serving as its scientific Yunchul Kim with On the ceiling above is a projection of the idea of teleportation. a d v i s e r, Q u à nt i c a i s t h e s e c o n d it e r a t i o n his artwork Argos. a spiral galaxy, a part of Juan Cortés’ T h e m o s t v i s u a l l y s t r i k i n g pi e c e i n t h e of an exhibition that brings together 10 Supralunar. Inspired by Vera Rubin’s exhibition is Cascade by Yunchul Kim, a r t w or k s r e s u l t i n g f r o m C ol l i d e I nt e r n a- work on dark matter and the rotational m a d e u p o f t h r e e l i v e e l e m e nt s. T h e fi r s t Muons, Inc. t ional ar t residences at CERN. mot ion of g a la x ies, Cor tés made a t wo- part is Argos (above), splayed metallic http://www.muonsinc.com/ The exhibition illustrates how inter- part multisensorial installation: a lens hands that hang like lamps from the Cryogen disciplinary intersections can present through which you see flashing lights ceiling – an operational muon detector s c i e nt i fic c o n c e p t s r e g a r d e d b y t h e w ider a n d v i br a t i n g pl a t e s t o r e s t y o u r c h i n a n d made of 41 channels blinking light as Free Probe public as esoteric, in ways that bridge the e x p e r i e n c e, o n s o m e l e v e l, t h e i nt e n s it y it records the particles passing through VISIT OUR BOOTH AT IPAC19 gap, engage the senses and create mean- of a g ala x y’s for mat ion. t h e g a l l e r y. E a c h s i g n a l t r i g g e r s t h e s e c- Stations ing. Punctuating each piece is the idea From the very large scale, move to ond element, Impulse, a chandelier-like Hear more about our BHAG* that the principles of quantum physics, the very small. A recording of Richard flu id-t r a n s fe r s y s t e m t h a t s e n d s d r o psof whether we like it or not, are pervasive Feynman explaining the astonishing l i q u i d t h r o u g h m i c r o t u b e s t h a t flo w i nt o Our BHAG: To make SRF accelerators so powerful and in our lives today – from technological double-slit experiment plays next to a transparent veins of the final element, Applications include a p pl i c a t i o n s i n s m a r t p h o n e s a n d s a t e l- s t a n d i n g d e m o n s t r a t i o n a l l o w i n g y o u t o Tubular. Kim, who won the 2016 Arts at efficient that they can make enough neutrons to produce nano science, materials lites to our philosophies and world views. observe the counterintuitive possibilities C E R N C ol l i d e I nt e r n a t i o n a l Aw a r d, i s a n nuclear energy for electricity or process heat for less cost and spintronics Ni n e k e y c o n c e p t s – “s c a l e s”, “q u a n- t h a t e x i s t a t t h e s u b a t o m i c l e v e l. Yo u c a n a r t i s t w h o e m pl o y s r i g or o u s m e t h o d s a n d than from wind, solar, or natural gas, without nuclear weapon <5 K - 675 K cryocooler- tum states”, “overlap”, “intertwin- put on goofy glasses for Lea Porsager’s e x p e r i m e nt s i n h i s l a b or a t or y w it h l i q u i d proliferation legacies of enrichment or chemical reprocessing, based systems i ng”, “i ndeter m i nac y”, “r a ndom ness”, Cosmic Strike, an artwork with a sense and materials. Cascade encapsulates the by burning unwanted nuclear materials. Vibration isolated for “open science”, “everyday quantum” of humour, which offers an immersive surprising results knowledge-sharing sub-micron sample stability and “change-evolution” – guide visi- 3 D a n i m a t i o n d e s c r i b e d a s “h a r d s c i e n c e can yield. *BHAG: Big Hairy Audacious Goal, from tors through the meandering hallway. and loopy mysticism”. She engages the Q u à nt i c a i s a m u s t-s e e for a n y o n e w h o “Built to Last: Successful Habits of Visionary Companies” Up to 8 probes, DC to 67 GHz, plus fiber optics Each display point prompts pause to audience’s imagination to meditate on v i e w s a r t a n d s c i e n c e a s o p p o s it e e n d s o f by Jim Collins and Jerry Porras (2004) Zoom optics with camera and monitor consider a question that underlies the b e i n g a n e ut r i n o a s it t r a v e l s t h r o u g h t h e t h e a c a d e m ic s p e c t r u m. T h e fi r s t v e r s io n Horizontal, vertical or vector magnetic field fundamental principles of quantum neutrino horn, one of the many scien- of the exhibition was held at Liver pool options are available p hy sic s. Ju x t ap o s e d i n t he s h a re d s p ac e tific artefacts from CERN’s archives that in the UK last year. Co-produced by the is an artist-made particle detector and pepper t he pat h. Sc A NNER net work (CERN, FACT, CCCB, Other configurations: LHe, LN2, room temperature p a r t s o f e x p e r i m e nt s d i s pl a y e d a s a r t i s t ic A r o u n d t h e c or n e r i s E r w i n S c h r ö d i n g- iMAL and Le Lieu Unique), the exhibi- and UHV systems objects. Video art installations are inter- er’s 1935 article where he first used the tion continues until 24 September in Contact us today: spersed with video interviews of CERN word “Verschränkung” (or entan- Barcelona, before travelling to Brussels. [email protected] p h y s i c i s t s, i n c lu d i n g He l g a T i m k o, w h o glement) and Anton Zeilinger’s notes www.janis.com /CryogenFreeProbeStation.aspx asks: what if we were to teach children explaining the protocol for quantum Abha Eli Phoboo CERN. www.facebook.com /JanisResearch

56 CERN COURIER MAY/JUNE 2019

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Power Supplies Scienza Frascati Associazione Giovanni Mazzitelli describes the High Precision changing face of Power Supplies communication through the lens As one of the market leaders for power supplies of European • Voltages up to 300,000V in dry isolation we set the benchmark in high precision and Researchers’ Night. current. • High precision current regulation by DCCT Heinzinger electronic offers a portfolio of excel- • Current up to 10,000A • Power up to 400,000W lent power supplies for research, industrial and In the world of communication, • High accuracy, low ripple, high stability medical accelerators. everyone has a role to play. During the past two decades, the ability of researchers to communicate Heinzinger electronic GmbH I 83026 Rosenheim - Germany their work to funding agencies, Phone +49-8031-2458-0 I email: [email protected] I www.heinzinger.com policymakers, entrepreneurs and the public at large has become an increasingly important part of their job. Scientists play a fundamental Nightlife A European Researchers’ Night event in Frascati in 2018. role in society, generally enjoying an authoritative status, and this and has triggered many institutions 60,000 makes us accountable. attendees website access to develop their own science-com- www.congratulationscern.com/ Science communication is not 45,000 munication projects. it’sbeenagreat30years just a way to share knowledge, it 30,000 Analysing the successive Frascati is also about educating new gen- Researchers’ Night projects allows er at ion s i n t he s c ie nt i fic appro ac h 15,000 a better understanding of the evo- and attracting young people to 0 lution of science-communication scientific careers. In addition, methodology. Back in 2006, scien- 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 fundamental research drives the tists started to open their labora- development of technology and Fig. 1. Interest in Researchers’ Night INFN-organised events has grown. tories and research infrastructures ® ARMCO Pure Iron innovation, playing an important to present their jobs in the most role in providing solutions in chal- Skłodowska-Curie Action, and Municipality of Frascati and the comprehensible way, with a view to High Purity Iron for lenging areas such as health care, offers an opportunity for scien- Cultural and Research Department increasing t he scient ific literac y of the provision of food and safety. tists to get more involved in science of the Lazio region, which co-funded t h e p u bl ic a n d t o fi l l t h e i r “d e fic it” of This obliges researchers to dissem- communication. It falls every final the initiative. knowledge. They then tried to create Magnetic Applications inate the results of their work. Friday of September, and illustrates Since then, thousands of a direct dialogue by meeting people how quickly attitudes are evolving. researchers, citizens, public and in public spaces such as squares and Evolving attitudes In 2006, with a small group of private institutions have worked bars, discussing the more practical Although science communication researchers from the Italian National together to change the public aspects of science, such as how pub- is becoming increasingly unavoid- Institute for Nuclear Physics (INFN) perception of science and of the lic money is spent, and how much able, the skills it requires are not located close to Frascati, we took infrastructure in the Frascati and researchers are responsible for their At INSYTE Electronics we know yet universal and some scientists part in one of the first Research- Lazio regions, supported by the work. Those were the years in which the meaning of working for over are not prepared to do it. Of course ers’ Night events. Frascati is sur- programme. Today, after 13 edi- the socio-economic crisis started to 30 years to earn everyone´s trust. there are risks involved. Commu- rounded by important scientific tions, it involves more than 60 unfold. It was also the beginning of 30 years that have meant a new YOUR RELIABLE age for humankind progress. By ASSEMBLY PARTNER nication can distract individuals institutions and universities, and scientific partners spread from the European Union’s Horizon 2020 our Whole services, we like to from research and objectives, or, if from the start the Italian National the north to the south of Italy in programme, when economic growth think that we have contributed also to improve the World through done badly, can undermine the very Agency for New Technologies, 30 cities, and attracts more than and terms such as “innovation” our customers´ Wished products. messages that the scientist needs to Energy and Sustainable Economic 50,000 attendees, with significant s t a r t e d t o s u b s t it ut e s c i e nt i fic pr o - These past 30 years have convey. The European Researchers’ Development, the European Space media impact (figure 1). Moreover, gress and discovery. It was therefore been amazing and Insyte will keep on working to contribute Night is a highly successful annual Agency and the National Institute it has now evolved to become a becoming more important than ever to make the next 30 years to event that was initiated in 2005 as for Astrophysics joined the collab- week-long event, is linked to many to engage with the public and keep come even more stunning. s www.aksteel.eu a European Commission Marie oration with INFN, along with the related events throughout the year, the science flag flying.

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PEOPLE CAREERS PEOPLE CAREERS

In recent years, this approach resent the “trademark” of research, possible, in the research itself. Its the traditional “deficit” model. Aointments and awards has changed. Two biannual pro- aiming to communicate to society successor, BEES (2018–2019), on the Here, researchers are not the main PI jects that are also part of a Marie the importance of the science pro- other hand, aims to bring citizens actors but facilitators of the learn- LO soeserson elected Ael rie for modern from a rigorous analytical point Skłodowska-Curie Action – Made duction chain in terms of quality, up close to the discovery process, i n g pr o c e s s w it h a s p e c i fic r ol e: t h e On 31 March, Patrick Brady of the geometric analsis of view. in Science and BEES (BE a citizEn identity, creativity, know-how and showing how long it takes and how expert one. University of isconsin-Milwaukee The Norwegian Academy of Scientist) underline a different responsibility. In this chain, which it can be tough and frustrating. Both was elected spokesperson for the Science and Letters has awarded naugural hilosoh award vision of science and of the meth- starts from fundamental research projects follow the most recent Nerd or not a nerd? LIGO Scientifi c Collaboration, the 2019 Abel Prize to aren Adwait Parker is the inaugural odology of communication. Made and ends with social benefits, no trends in science communication Nevertheless, this evolution of which is dedicated to the search prize Abel winner of the new Du Chtelet in Science (which was live between one is excluded and must take part based on a participative or “public science communication isn’t all for gravitational waves. Brady, Prize in Philosophy of Physics 2016 and 2017) was supposed to rep- in the decision process and, where engagement” model, rather than positive. There are many examples who replaces former spokesperson created by Duke University and of problems in science communi- David Shoemaker, takes the helm the journal tudies in istor and cation: the explosion of concerns New leader at Perimeter nstitute just as LIGO resumes observations hiosoph o cience. Parker, who about science (vaccines, autism, Theorist Robert Myers has following a series of upgrades has just completed his dissertation GMO, homeopathy, etc); the avoid- been appointed director of the that will increase the detector’s at Stanford University, won for PT2026 NMR Precision Teslameter ance of science and technology in Perimeter Institute for Theoretical sensitivity by about 0 compared Uhlenbeck of the University of his work Newton on active and preference to returning to a more Physics in aterloo, Ontario, to previous runs. oining Teas at Austin for her pioneering passive quantities of matter. The

“natural” life; the exploitation of replacing Neil Turok, who has P Amland achievements in geometric partial prize, named after philosopher Reach new heights science results (positive or negative) held the role since 200. Myers is diff erential equations, gauge milie Du Chtelet (10619), to support conspiracy theories or a leading researcher in the area of theory and integrable systems, and recognises graduate students influence democracies; and over- quantum fi elds and strings, and for the fundamental impact of her or recent PhDs for previously in magnetic eld pl a y i n g t h e b e n e fit s for k n o w l e d g e has received numerous awards. work on analysis, geometry and unpublished work in the and technology transfer, to list a His research has primarily focused mathematical physics. It is the philosophy of physics. few examples. Last but not least, on gravitational aspects of string fi rst time the prestigious S err measurement some strong bias still remains theory, most recently eploring prize has been awarded to a among both scientists and audi- applications of the AdSCFT woman. Uhlenbeck is a founder of The Metrolab PT2026 sets a new e n c e s, l i m it i n g t h e e ffe c t i v e n e s s o f correspondence. This is the LIGO is the European-based modern geometric analysis, and communication. opportunity of a lifetime, said gravitational-wave detector irgo has made major contributions to standard for precision magnetometers. T h e fi r s t, a n d pr o b a bl y t h e h ard- Myers after his appointment was in Italy, which has almost doubled gauge theory, having pioneered Leveraging 30 years of expertise building est, is the stereotype bias: are you made public. its sensitivity since its last run. the study of angMills equations the world’s gold standard magnetometers, a “nerd”, or do you feel like a nerd? Often scientists refer to themselves it takes magnetic  eld measurement to as a category that can’t be under- new heights: measuring higher elds with stood by society, consequently 300kW All Solid-State RF Amplifier better resolution. limiting their capacity to interact with the public. On the other hand, Model : CA500BW2-8085RP scientists are sometimes real nerds, R&K provides the world’s most reliable high performance solid-state RF Power Amplifiers. The PT2026 offers unprecedented  exibility and seen by the public as nerds. R&K Company Limited This is true for all job categories, in the choice of parameters, interfacing AMPLIFIER DESIGN but in the case of scientists this and probe placement, as well as greatly strongly conditions their ability ・Consists of four (4) rack-mounted 75kW SSAs. improved tolerance of inhomogeneous to communicate. ・Able to deliver 300kW via 4-way power combiner. Age, gender and technological ・96-way radial combiner for final power combining elds. And with Ethernet & USB interfaces bias also still play a fundamental of 75kW SSA. and LabVIEW software, it  ts perfectly into role, especially in the most devel- ・Long-term & highly reliable operation achieved modern laboratory environments. oped European countries. Young by protecting each final-stage transistor with people may understand science built-in circulator at its output. 96-way Radial Combiner

www.agence-arca.com - Photo: Scott Maxwell, Master le - Photo: Scott Maxwell, Master www.agence-arca.com and technology more easily, while Output Power Linearity ■Output Pulse 86 Frequency = 500MHz, Po = 300kW 85 X：50μs / DIV Y：200mV / DIV women still do not seem to have 84 FWD LIMIT 83 82 81 f u l l a c c e s s t o s c ie nt i fic c a r e e r s a nd 80 79 78 to the exploitation of technology. 77 76 75 74 Although the transition from a 73 72

Output Power (dBm) 71 Frequency deficit to a participative model is 70 69 499MHz 68 500MHz already common in education and 67 501MHz -15 -10 -5 0 5 10 democratic societies, it is not yet Input Power (dBm) ■Pulse Rise ■Pulse Fall completed in science, which is Frequency = 500MHz, Po = 300kW Frequency = 500MHz, Po = 300kW X：200ns / DIV Y：200mV / DIV X：50ns / DIV Y：200mV / DIV likely because of the strong bias SPECIFICATION that still seems to exist among Frequency Range : 500MHz±1MHz researchers and audiences. The Output Power : 320kW @Peak, 300kW (min.) Marie Skłodowska-Curie Euro- *Each rack-mounted amplifier section individually delivers 75kW. Pantone 286 Pantone 032 pean Researchers’ Night is a pow- (75kW/rack ×4 outputs) erful way in which scientists can Pulse Width : 1μs～300μs (max.) ～ address such issues. Duty : 0 3% (max.) R&K Company Limited Operation Mode : Class AB Magnetic precision has a name www.metrolab.com www.rk-microwave.com AC Supply Input : AC200V 10% 3φ, 50 60Hz Giovanni Mazzitelli INFN/ ± ／ ／ 721-1 Maeda, Fuji-City, Shizuoka, 416-8577 Japan Size : (W)2240mm×(D)1300mm×(H)1510mm Associazione Frascati Scienza. Tel:+81-545-31-2600 Fax:+81-545-31-1600 Email:[email protected]

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EDITOR’S fl exible cryostats Books on particle and nuclear physics PICK Cryoworld BV in Wieringerwerf is a manufacturer of cryogenic equipment. IOP Concise Physics A Morgan & Claypool Publication B Factories Our core business is design, production, testing and installation of Helium B Factories and other custom designed cryogenic equipment. Cryoworld specializes in Boštjan Golob the development of new cryogenic technologies and delivers projects to Boštjan Golob renowned companies and scientifi c institutes worldwide. B factories are particle colliders at which specific subatomic particles – B mesons – are produced abundantly. The purpose is to study the Cryoworld has developed two types of fl exible cryostat with a length of 60 meters for CERN. properties of their decays in great detail in order to shed light on a mystery One with passive thermal shielding and one with active thermal shielding. The cryostat will be used of eminently larger scale: why do we live in a universe composed of matter for superconducting cable in the superconducting (SC) link for the Hilumi upgrade project. Both and no anti-matter? This book introduces readers to the physics laws of the cryostats are being tested and commissioned at CERN at the moment. Testing results are very positive. CP asymmetry, touching on experimental requirements needed to perform The heat leak values of this passive thermal shielded cryostat are at the same level as can be reached such measurements at the subatomic level, and illustrating the main with ridged pipe and therefore are much better than any fl exible cryostat has been able to perform in findings of the contemporary B factories. the past. This opens many possibilities for the application of fl exible cryostats in any situation where long lengths and extremely low heat leak values are required for e.g. super conducting cables. www.cryoworld.com

For further information please contact Cryoworld BV in the Netherlands: +31 (0) 228 74 39 30 | [email protected]

IOP Concise Physics A Morgan & Claypool Publication IOP Concise Physics A Morgan & Claypool Publication IOP Concise Physics A Morgan & Claypool Publication IOP Concise Physics A Morgan & Claypool Publication The Search and Particle Physics International Linear A Practical Introduction Discovery of the Richard A Dunlap Collider (ILC) to Beam Physics and Higgs Boson The next mega-scale particle collider Particle Accelerators © vege - fotolia.com A brief introduction to Alexey Drutskoy Santiago Bernal particle physics SECOND IUVSTA EDITION Luis Roberto Flores Castillo EBARA AWARD

The Search and Discovery Particle Physics International Linear A Practical Introduction of the Higgs Boson Richard A Dunlap Collider (ILC) to Beam Physics and A brief introduction to The next mega-scale Particle Accelerators RE N REERCER RN N E RE C particle physics particle collider Second Edition CENCE N ECN N R ENRNEN Luis Roberto Flores Castillo Alexey Drutskoy Santiago Bernal Apply at iuvsta.org Take the chance and participate in a contest for We are actively commissioning in these fields, so if you have an idea for the development of environmentally a book you’d like to discuss please contact [email protected]. friendly vacuum technologies. Visit iopscience.org/books for more information and a full list of titles. e inner ill e aarded a rie to te aount o euro at te C ongre in aleden ul

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Scientific sessions | Industrial exhibition | Special focus workshops | Short courses 2019 IEEE Nuclear Science Symposium and Medical Imaging Conference 26th International Symposium on Room-Temperature X-Ray and Gamma-ray Detectors

Manchester Central Convention Centre 26 October - 2 November, 2019 Manchester, UK

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A forum for physicists, engineers, mathematicians & computer scientists working on Radiation Detectors, Related Technologies and their applications  Astrophysics:Synchrotron Radiation General Chair: Paul Marsden  Nuclear and High Energy Physics Deputy General Chair: Patrick Le Dû  Homeland Security Scientific Program Chairs  Energy: Environmental Sciences  Medical Imaging Systems NSS: Cinzia Da Via and Yoshinobu Unno  Image Reconstruction & Data Analysis MIC: Dimitra Darambara and Suleman Surti  Radiation Therapy and Dosimetry RTSD: Paul Sellin and Michael Fiederle www.nss-mic.org/2019 | [email protected] Abstract Submission Deadline 8 May 2019

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Rat der Eidgenössischen Techni- Conseil des écoles polytechniques Consiglio dei Board of the Swiss Federal RECRUITMENT schen Hochschulen fédérales politecnici federali Institutes of Technology ETH-Rat CEPF CPF ETH Board

The Paul Scherrer Institute (PSI) is the largest research institute for natural and engineering sciences within Switzerland and employs approximately 2,100 people. Its research focuses on three main subject areas: Matter and Materials, Energy and Environment, and Human Health. As a national For advertising enquiries, contact CERN Courier recruitment/classified, IOP Publishing, Temple Circus, Temple Way, Bristol BS1 6HG, UK. user laboratory, PSI develops, constructs and operates complex large-scale research infrastructures. Every year, these unique facilities are used Te l +4 4 (0)1 17 930 1 264 E-m a i l s a le s@c e r nc ou r ie r.c om. by more than 2,300 scientists from Switzerland and around the world. In addition to its research activities, PSI operates Switzerland’s only proton Please contact us for information about rates, colour options, publication dates and deadlines. therapy centre and works closely with the PARK INNOVAARE innovation park, one of the “Switzerland Innovation” sites. PSI is part of the ETH Domain, which also includes ETH Zurich and EPFL as well as the federal research institutes WSL, Empa and Eawag. The ETH Board is the strategic management and supervisory body of the ETH Domain. The ETH Board is advertising the position of a male or female Director of the Paul Scherrer Institute (PSI) in line with its mandate. The ETH Board is responsible for proposing a candidate for this position to the Swiss Federal Council. It is expected that the With 2600 staff members, 1800 other paid personnel and some 13 000 scientific users from almost 100 person appointed will hold a dual professorship at ETH Zurich and EPFL. countries, the European Organization for Nuclear Research, CERN, an intergovernmental organisation Requirements with its seat at Geneva, Switzerland, is the leading international laboratory for fundamental research You have an internationally recognised scientific track record in one of PSI’s main subject areas, together with a thorough knowledge of the use, preferably in particle physics. The annual Budget of some 1 billion Swiss francs is funded by its 23 Member and also the planning, construction and operation, of large research facilities. As an experienced senior manager in a major organisation – ideally a large- Associate Member States. CERN is presently operating the Large Hadron Collider (LHC), the world’s scale international research infrastructure – or else in trade and industry, you have proven your integrative leadership skills. You have good networks inside and outside the scientific community and take an active role in scientific, technological and societal areas of current importance. Given your ability most powerful particle accelerator that provides new insights into the origin and the structure of matter to establish strategic guidelines, you will commit yourself to developing PSI’s future and helping to proactively shape the entire ETH Domain. and into the forces governing the Universe. You are an open, creative and enthusiastic person, with integrity, a persuasive manner and the ability to make decisions quickly and effectively. Along with your excellent interpersonal skills, you demonstrate assertiveness and an ability to manage conflict. You possess very good communication skills, which you would use both inside and outside PSI, and you understand Switzerland’s political structures, legislative processes and cultural diversity. Finally, you are interested in the wider economic and business context and have a good command of German and English, and preferably also a knowledge of French. You are willing to hold office for at least two terms of office (i.e. eight years). The successful candidate will be expected to take up this appointment at the start of 2020. The CERN Council is inviting applications for the appointment of a Applications Please send your complete application to [email protected]. Egon Zehnder is assisting the ETH Board in its preparations for the selection process. The interim President of the ETH Board, Beth Krasna, will be pleased to provide further information (phone +41 79 447 84 75, [email protected]). All applications received by 28 May 2019 will be considered in the selection process. Your data will be treated in strict confidence. It will be used only in connection with your application and in accordance with Swiss data protection law. By submitting your application, you give us your consent to process your data for this purpose and to exchange it with the above-mentioned company. Director-General for a five-year term starting on 1st January 2021. The ELI Project is an integral part of the European plan to build the datasets obtained from experiments at ELI facilities. You will collaborate next generation of large research facilities. ELI-Beamlines as a cutting with partners in the PaNOSC project on development and integration of edge laser facility is currently being commissioned near Prague, Czech these open-source tools and services into the EOSC. Republic. ELI will be delivering ultra-short, ultra-intense laser pulses Required skills: university degree in Computer Science, Engineering, lasting typically a few tens of femtoseconds (10-100 fs) with peak power Science, or related field • good knowledge of programming in Python, Applicants are requested to address a letter of interest, with a detailed curriculum vitae, to the Chair of the Search Committee projected to reach 10 PW. It will make available multiple synchronized C++, C • experience with data analysis tools and techniques • experience laser beams for sophisticated pumpprobe experiments. with processing of scientific data • good knowledge of Linux/Unix and send it to the CERN Council Secretariat before 31 May 2019. ELI (Extreme Light Infrastructure) project is involved in a European project programming environment • proficiency in English Full details of the position and application process can be consulted on: careers.cern/DG. Photon and Neutron Open Science Cloud – PaNOSC which aims at Desired skills: experience with JupyterLab / Notebook • experience with developing and providing services for scientific data and integrating them Python libraries and tools for scientific computing: numpy, scipy, matplotlib, to the European Open Science Cloud (EOSC). pandas, ploty, h5py • experience with machine learning (AI) solutions for big data processing and analysis • knowledge of remote data access and analysis workflows • experience with data visualization tools • knowledge of Scientific Data Management Specialist programming in C++, C • knowledge of web technologies: WebGL, javascript • experience with GPU technologies: CUDA, OpenGL, OpenCL, Vulkan (Software Engineer) • experience in European projects and international collaborations Job description: Your main mission will be to implement solutions for Job conditions: the opportunity to participate in this unique scientific cataloging experimental data and metadata and integrating them into project • career growth, professional education • competitive and motivating PaNOSC and EOSC. You will collaborate with multiple teams at ELI as salary • 5 weeks of holiday and other employee benefits well as within PaNOSC project to bring data from their acquisition to publicly accessible web services based on FAIR Data Principles (Findable, Accessible, Interoperable, Reusable). Applications, containing CV, cover letter, contacts of references, and any other material the candidate considers relevant, should be sent to Required skills: university degree in Computer Science, Engineering, Mrs. Jana Ženíšková, HR specialist ([email protected], Science, or related field • experience with working with scientific data and +420 - 601560322). metadata • experience with setting up and managing databases • experience with development of APIs • experience with programming in Information regarding the personal data processing and access to the Python • good knowledge of Linux/Unix programming environment personaldata at the of the Czech Academy of Sciences Discover what’s out there. • proficiency in English can be found on: https://www.fzu.cz/en/processing-of-personal-data Desired skills: experience with machine learning for big data processing • experience with control systems like TANGO • experience in European projects and international collaborations Scientific Data Analysis Specialist (Software Developer) Job description: Your main mission will be to prototype, develop, and implement interactive webbased solutions for analysis of various scientific

66 CERN COURIER MAY/JUNE 2019

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MAX-PLANCK-INSTITUT FÜR GRAVITATIONSPHYSIK (ALBERT-EINSTEIN-INSTITUT) The Max Planck Institute for Gravitational Physics (Albert Einstein Institute) is a world-leading research institute CLUSTER OF EXCELLENCE specializing in gravitational physics. Around 400 international QUANTUM UNIVERSE scientists work at the labs and offices located in Potsdam- Golm and Hannover, Germany. We are seeking a IHEP RECRUITMENT OF Head of Administration (m/f/d) The position is permanent and will be based in Potsdam-Golm. Quantum Universe is a newly established Cluster of Excellence as part of OVERSEAS HIGH-LEVEL TALENTS Germany’s Excellence Strategy. It brings together leading scientists from The core departments of our administration are Finance, Human Resources mathematics, particle physics, astrophysics, and cosmology at Universität and Purchasing. Our professional Administration Services Team provides Hamburg and DESY to understand mass and gravity at the interface between high-quality support to our scientists and support staff. The working culture is quantum physics and cosmology. collaborative, friendly and “can-do”. Initiative is appreciated. INSTITUTE OF HIGH ENERGY PHYSICS, We invite applications for Duties and responsibilities Leading a team of 15 professionals, you will be responsible for all administrative more than 30 PhD and Postdoc positions CHINESE ACADEMY OF SCIENCES services at the Institute. Moreover, you will directly support the Board of Directors and Managing Director with their strategic decision making, executing their on research topics of the Cluster of Excellence: decisions when needed. A well-run administration is extremely important to support the scientific productivity of our Institute; therefore you will oversee Higgs Physics • Dark Matter • Gravitational Waves • Quantum Theories and business process improvement and the development of administration staff Mathematical Physics professional skills. Other aspects of the job include financial oversight for the Quantum Universe is looking for outstanding doctoral and postdoctoral whole Institute, managing communication with the Max Planck Society central researchers with excellent degrees and scientific track record. administration, working collaboratively with other institutes (including two other Successful candidates will join an inspiring world-class environment for re- Max Planck Institutes on the Potsdam-Golm Campus), project management, search and education and will be promoted through the Quantum Universe streamlining internal communication, and consulting specialists as appropriate Research School. (e.g. legal, tax, building services) to ensure compliance with legal, funding and Max Planck regulations. For detailed information on the available positions and the application pro- cess please visit www.qu.uni-hamburg.de/jobs.html or contact Dr. Michael Essential requirements Grefe or Christian Kühn: [email protected].  Higher degree (Masters and preferably a PhD) or equivalent  Relevant work experience, particularly in a leadership position in an academic The Institute of High Energy Physics (IHEP) of the Chinese Academy of Sciences (CAS) invites applications for and/or research environment  Broad knowledge of administrative, employment, procurement and funding permanent staff positions at all levels. IHEP is a comprehensive research laboratory for particle and astroparticle law Universität Hamburg has been certified. physics, accelerator physics and technology, radiation technologies and applications, as well as for nuclear analytical  Excellent leadership, people management and coaching skills audit familiengerechte hochschule  Excellent project management and planning skills techniques and interdisciplinary research.  Excellent communication and interpersonal skills  Excellent negotiation and influencing skills For More Information: http://english.ihep.cas.cn/  Excellent analytical and problem-solving skills  Fluent colloquial and professional level German language, in both oral and Recruitment Objectives: written forms  Fluent colloquial and professional level English language, in both oral and Based on the needs of the research areas and the disciplines development of IHEP, we are now publicly written forms  Very good working ability with IT office software and ERP systems recruiting overseas outstanding talents and scholars of relevant disciplines who possess research abilities and

Salary and Contract innovation awareness. The salary and contract will be based on previous experience according to TVöD guidelines (German collective wage agreement for the public service) up Programs: to EG 15 (Entgeltgruppe 15). This is a full-time permanent position. Working hours can be adjusted in accordance with family duties and needs. 1 National “Thousand Talents Program” (full time & part time programs) for established scientists

Further Information 2 National “Thousand Young Talents Program” for outstanding junior scientists The Max Planck Institute for Gravitational Physics is an equal opportunity em- 3 Pioneer “Hundred Talents Program” of CAS for outstanding junior scientists, excellent junior detector or ployer, and is committed to providing employment opportunities to all qualified applicants without regard to race, color, religion, age, sex, sexual orientation, accelerator experts gender identity, national origin, or disability. 4 “Outstanding Talents Program” of IHEP for scientific research or technical talents The Max Planck Society is committed to increasing the number of individuals with disabilities in its workforce and therefore encourages applications from Research Areas: such qualified individuals. Further information can be obtained from the current acting Head of Administration Experimental Particle and Nuclear Physics, Theoretical Physics, Astronomy and Astrophysics, Nuclear Technology, ([email protected]) or [email protected]. A WORLD OF NEW BEGINNINGS Accelerators, Neutron physics, Condensed matter physics, Chemistry, Biochemistry and Molecular Biology, How to Apply News and Please apply by sending the following to [email protected] before Biophysics, Computing, Multidisciplinary Research. commentary for 15th May 2019: the global scientifi c Contact:  Your curriculum vitae with your contact details included. community  Your education and work certificates. Office of Human Resources, Institute of High Energy Physics, Chinese Academy of Sciences  A cover letter  describing how you meet the criteria for this job. E-mail: [email protected] Tel: (86)010-88233157 Fax: (86)010-88233102  giving examples of relevant projects/work you have done before, why you did them and what the benefits were. Address: No. 19 (B), Yuquan Road, Shijingshan District, Beijing (Postcode: 100049)  identifying at least three people we can contact for reference. Further information about data privacy at: Applications should include a CV, an outline of academic accomplishments, description of current research and plan www.aei.mpg.de/1822816/PrivacyPolicy for future research, 3 – 5 published papers representative of your work, and a record of citations for your work. You Interviews will likely happen in June 2019. should arrange for 3 letters of reference from experts in your field to be sent by post or email (established scientists are not requested). Max-Planck-Institute for Gravitational Physics Am Muehlenberg 1  14476 Potsdam-Golm For detailed information, please visit http://english.ihep.cas.cn/doc/2649.html www.aei.mpg.de CERN COURIER MAY/JUNE 2019

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CERNCOURIER.COM Semiconductor detectors for high energy physics... PEOPLE ...going beyond the discovery OBITUARIES of the Higgs boson Michael atiyah 1929–2019 A giant of mathematics

The eminent mathematician Oxford of Institute/University Mathematical getic in facilitating this cooperation Michael Atiyah died in Edinburgh thereafter. He frequently engaged on 11 January, aged 89. He was one in correspondence and discussions of the giants of mathematics whose with , out of which w or k i n flu e n c e d a n e n or m o u s r a nge emerged the current fashion in of subjects, including theoretical mathematics of topological quan- high-energy physics. tum field theories – beginning with Atiyah’s most notable achieve- a formalism that described new ment, with Isadore Singer, is the invariants of knots. Despite the “index theorem”, which occu- quantum language of this domain, pied him for more than 20 years Michael’s mathematical work with and generated results in topology, a physical interface was more con- geometry and number theory using cerned with classical solutions, and the analysis of elliptic differential the soliton-like behaviour of mon- operators. In mid-life, he learned opoles and . that theoretical physicists also made use of the theorem and this Founding father opened the door to an interaction During his life he took on many between the two disciplines, which administrative tasks, includ- Hamamatsu Photonics continue their journey with CERN in the following experiments he pursued energetically until the ing the presidency of the Royal end of his life. It led him not only Society and mastership of Trinity 8-inch PAD: SiPM/MPPC: Pixel detectors: Silicon Strip Detectors: to mathematical results on Yang– College. He was also the found- Mills equations, but also to encour- ing director of the Isaac Newton CMS HGCAL CMS HCAL, CMS BTL, CMS tracker, CMS tracker, aging the importation of concepts Institute for Mathematical Sciences CMS CEH, LHCb tracker ATLAS tracker f r o m q u a nt u m fie l d t h e or y i nt o p u re in Cambridge. LHCb SciFi tracker mathematics. With his naturally effervescent personality he possessed, in Sing- Early years Michael Atiyah’s index theorem is a milestone of 20th century mathematics. er’s words, “speed, depth, power More than 35 years ago, after the success using our photomultiplier tubes in their research, Born of a Lebanese father and a and energy”. Collaborations were Scottish mother, his early years Michael was context of anomalies in quantum all-important, bouncing ideas Hamamatsu Photonics started a journey together with the researchers at CERN to develop customised were spent in English schools in fie l d t h e or y. I n t h e 1980 s, i n a pr of around with both mathematicians Si detectors to enable them to push the boundaries of their high energy physics experiments. the Middle East. He then followed energetic in by Luis Álvarez-Gaumé (who sub- and physicists. Beauty in mathe- the natural course for a budding sequently became a member of the matics was also a feature he took We are proud to continue that journey with the development of the next generation of detectors. mathematician in that environ- facilitating CERN theoretical physics unit for 30 seriously, as was a respect for the ment by attending the University years), Hirzebruch’s polynomials mathematicians and physicists of Cambridge, where he ended up cooperation in the Pontryagin classes – which of the past. He even campaigned writing his thesis under William between form the topological expression for successfully for a statue of James Hodge and becoming a fellow at the index – emerged as a natural Maxwell to be erected in Edinburgh, Trinity College. As a student he had mathematicians consequence of supersymmetry. his home city, in later years. little interest in physics, but went to Singer visited Oxford again in As for the index theorem itself, hear Dirac lecture largely because and physicists 1977, this time bringing math- it is notable that one of the more SiPM - 128-channel Multi-Pixel of his fame. The opportunity then ematical questions concerning subtle versions – the “mod 2 index” Photon Counters arose to spend a year at the Institute Yang-Mills theory. Using quite – played an important role in Kane for Advanced Study in Princeton in sophisticated algebraic geome- and Mele’s theoretical prediction Silicon Strip Detectors the US, where he met his future col- Medal in 1966 and, with Singer, the try and the novel work of Roger of topological insulators. As they (SSDs) and pixel detectors laborators and close friends Raoul Abel Prize in 2004. Over the years, Penrose, this yielded a precise wrote in their 2005 paper: “it dis- Bott, Fritz Hirzebruch and Singer. proofs and refinements of the index answer to physicists’ questions tinguishes the quantum spin-Hall 8-inch PAD A visit by Singer to the Univer- theorem evolved. Although topol- about instantons, specifically the phase from the simple insulator.” (Pixel Array Detector) sity of Oxford (where Atiyah had ogy was at the forefront of the first so-called ADHM (Atiyah, Drinfeld, A fitting tribute to an outstanding recently moved) in 1962 began the approaches, in the early 1970s tech- Hitchin, Manin) construction. That pure mathematician, whose intu- actual work on the index theorem, niques using “heat kernels” became mathematicians and physicists had ition and technical power revealed where the Dirac operator would play more analytic and closer to the cal- common ground in a completely so much in so many domains. a fundamental role. This ultimately culations that theoretical physicists new context made a huge impres- led to Atiyah being awarded a Fields were performing, especially in the sion on Michael, and he was ener- Nigel Hitchin University of Oxford.

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PEOPLE OBITUARIES

Hans-Jürg gerber 1929–2018 A flair for the fundamental

Swiss physicist Hans-Jürg Gerber photograph Family interaction for the normal and cant theo retical work he undertook passed away on 28 August last year. inverse muon decay using exper- on T, CP and CPT invariance. Born in Langnau/Kanton Bern, he imental data, which brought him While he retired in the spring studied and did his PhD from 1949 international recognition. of 1997 after a long and extremely to 1959 at ETH Zurich on “Scat- In the 1980s and 1990s, Hans- successful career, he still continued tering and polarization effects of Jürg returned to CERN to help set working on particle physics with 3.27 MeV neutrons on deuterons”. up and operate experiment PS195 various publications on the inter- He then worked at the University (CPLEAR) for studying CP violation pretation of the CPLEAR results of Illinois in the US, before joining using a tagged neutral-kaon beam. regarding testing of quantum CERN from 1962 to 1968. There, The concept of the experiment, mechanics, T- and CPT-violation. he carried out experiments at the w h i c h i n v ol v e d t a g g i n g t h e fl a v o u r He was also a contributor to the 28 GeV Proton Synchrotron (PS). of the neutral kaon at the point review of particle physics in the He studied high-energy neutrino of production, was opposite to Particle Data Group. interactions using a spark cham- already operational kaon experi- Experiment, theory and teach- ber, and performed measurements ments based on K-short and K-long ing formed a unity for Hans-Jürg. of lepton universality. He also beams. As a skilled experimenter, This was particularly evident in his tested time-reversal invariance h e c o nt r i b ut e d s i g n i fic a nt l y t o t he lectures, in which he enthusiasti- in the charged decay mode of the success of CPLEAR with unconven- cally conveyed the joy of physics Λ . He was also PS coordi- tional ideas. For example, during a to his students. We also remember nator from 1965 to 1966. Hans-Jürg Gerber carried out seminal crisis when the liquid-scintillator dinners with Hans-Jürg after long In 1968, Gerber became head of work on T, CP and CPT invariance. started to develop air bubbles due working days setting up experi- the research department at the to the heat from nearby electronics, ments, where we talked about all Swiss Institute for Nuclear Physics Scherrer Institute (PSI) with his he invented a system to remove the possible physics questions. (SIN). He was elected by the Swiss precision experiments on the decay air dissolved in the liquid using He is survived by his wife Federal Council to become associate of charged muons – experiments ultrasound. CPLEAR’s measure- Hildegard, his three children and professor of experimental physics that continue to this day at PSI (see ments on the violation of time-re- grandchildren. in 1970, and in 1977 promoted to p45). His flair for the fundamental versal invariance (T-invariance) full professor. Gerber initiated basic led to the most general determina- and tests of quantum mechanics H i s f r ie n d s a n d c ol le ag u e s research at SIN and later at the Paul tion of the leptonic four-fermion w e r e t h e s t a r t i n g p oi nt for s i g n i fi- at CERN.

bastia an De r a aD 1931–2018 CERN accelerator pioneer

Bas de Raad arrived at CERN in July CERN SPS division from 1977 to 1981 and 1954 at the tender age of 22 – two leader until the end of 1989. months before the Organization was Even with his heavy load as leader formally established. After graduat- of one of the biggest divisions at ing from the Technical University of C E R N, h e s t i l l m a n a g e d t o fi n d t i m e Delft in the Netherlands, he joined for technical work. In preparing the team working on the design of the SPS to accelerate electrons and VACUUM SOLUTIONS the Proton Synchrotron (PS), based positrons for the Large Electron at that time in the École de Physique Positon collider, he realised the in Geneva, with special responsibil- importance of shielding the SPS ity for the PS main magnets, which coils from synchrotron radiation FROM A SINGLE SOURCE are still operating reliably to this and took on the job himself, spend- day. He moved on to work on mag- ing many hours in the SPS tunnel Pfei er Vacuum is proud to have been a supplier of innovative and customized vacuum solutions to the particle accelerator nets for the external beams of the PS. fitting the shielding masks. From community for more than 50 years. Our complete product portfolio for vacuum technology, our focus on competent and After a sabbatical year in Stan- 1990 until his retirement in 1996 he ford in 1963/1964, he returned to was the leader of CERN’s technical specialized advice supported by robust and reliable service, makes Pfei er Vacuum the partner of choice for the analytical the accelerators division at CERN inspection and safety commission. and research communities worldwide. to work on the design of the optics Machine expert Bas de Raad, photographed at CERN in 1975. Bas was a great leader, training a for the Intersecting Storage Rings new generation of machine build- ■ Pumps for vacuum generation down to UHV (ISR), the first hadron collider. beam-dumping systems. the design and construction of all ers during the construction of the ■ Vacuum measurement and analysis equipment Later, he became leader of the ISR On approval of the construction the transfer lines to and from the ISR and the SPS with the metic- ■ Leak detectors and integrity test systems beam transfer group with respon- of the SPS (together with injection), and ulous attention to detail that he ■ System technology and contamination management solutions sibility for the design of the two (SPS) in 1970, Bas joined the core both resonant and fast-extraction demanded of himself. ■ Chambers and components long transfer lines from the PS to team of John Adams, where he led systems and the beam dump. He ISR, as well as the injection and a much bigger group working on was deputy division leader of the His friends and colleagues. Are you looking for a perfect vacuum solution? Please contact us: Pfeiffer Vacuum (Schweiz) AG · T +41 44 444 22 55 · F +41 44 444 22 66 72 CERN COURIER MAY/JUNE 2019 [email protected] · www.pfeiffer-vacuum.com

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N A From the archive: May 1976 P Acronyms are part of the joy and RE-EARTH-BASED HIGH TEMPERATURE Victor F Weisskopf has been awarded the frustration of being a particle Oersted Medal, the highest award of the physicist, with no end of wordplay

American Association of Physics Teachers. CERN146.7.73 in sight – just look at the feat of the SUPERCONDUCTORS It is given for outstanding contributions in recently created ABRACADABRA the teaching of physics and can rarely have (A Broadband/Resonant Approach had a more deserving recipient than “Viki” to Cosmic Detection with an Amplifying B-fi eld Ring Apparatus) Weisskopf. His general lectures on physics collaboration. Astronomers are draw large audiences wherever he goes. For similarly affl icted, says Ben Cook of example, at MIT no lecture room could be OUTSTANDING PERFORMANCE FOR DEMANDING APPLICATIONS the Center for Astrophysics Harvard found large enough to hold all who wished to attend his recent talks Smit hsonian, prompt ing him to off er help: ACRON YM is a command- on “Modern Physics without Mathematics”. The photo shows him in line program to assist astronomers in identifying the best acronyms. discussion with vacation students at CERN after one of the lectures In true astronomer fashion, writes Cook in a preprint published on 1 given during his regular summer visits. SUPERIOR IN-FIELD CRITICAL CURRENT April (arX iv 1903.12180), t he code ret ur ns all approx imately English- Professor E C G Stueckelberg has been awarded the 1976 Max language words that appear within an input string of text regardless Planc k Medal for his basic work on fi eld t heor y. Er nst St uec kelberg of whether the letters occur at the beginning of the component words. is presently Honorary Professor at the and also It is available as an open-source Python package on GitHub, and works in the Theory Division at CERN. EXCELLENT MECHANICAL PROPERTIES particle physicists should take note: “With widespread use, ACRONYM  Compiled from text on p185 of CERN Courier May 1976. should revolutionise the fi eld of astronomy by freeing researchers from the burdensome task of brainstorming convoluted acronyms for Compiler’s note ith his palpable enthusiasm or new ideas and oung their projects, adding back countless hours of productive work to the EXTREMELY UNIFORM CRITICAL CURRENT people, iki eisskop was the much cherished research cycle,” concludes Cook. director-general o CERN rom 191 to 195. nder his to enable those who want to – direction, the fl edging laboratory developed into one of refugees and people from minority the oremost institutions in the subect. MANUFACTURED USING OPTIMISED IBAD AND PLD PROCESSES “I am moved by the image of and other under-represented The relative lack of renown for the Stueckelberg a species looking at an image groups – to stay on and do PhDs.” mechanism in modern fi eld theory may be due to the idiosncratic stle o eminent phsicist Baron Ernst Carl Gerlach of a curious empty hole looming who won a Stueckelberg von Breidenbach zu Breidenstein und Melsbach, a scion of in space.” Special in Swiss aristocracy born in Basel in 1905. Older readers might recall his VOLUME PRODUCTION AVAILABLE NOW. Janna Levin refl ecting on the fi rst 2018 for the discovery of pulsars, attendance at CERN seminars accompanied b his little dog. recorded image of a black hole interviewed in the April issue of (a lso see p10) in Quanta Magazine, Phsics orld magazine about her 10 April. new 3 m graduate-student fund. “His proposal was initially “I fi gured if I’d been fi ve years rejected by a royal commission, older, I could not have become “compactifi ed” to yield the which pronounced that ‘so many a mathematician, because the centuries after the Creation, it is disapproval would be so strong.” (minimally supersymmetric) unlikely that anyone could fi nd Karen Uhlenbeck the fi rst woman Standard Model, according to “A hitherto unknown lands of any to be awarded a prestigious Abel quadrillion Standard Models from value’.” Prize (p61), interviewed in The New F-theory” (arXiv 1903.00009). John Ellis on Spain’s reaction to orker about gender politics in

Christopher Columbus when he t h e fi e l d . C Thomas requested funding to explore a westerly route to Asia, pointing out “Left-brained music lovers will On 14 Marc h, during an a f ter noon v isit that Columbus sailed west anyway enjoy Roskilde’s Science Pavilion, to the , Pink Floyd and found “hitherto unknown” where representatives from CERN front man Roger Waters stopped for a photo lands that have dominated the and the Niels Bohr Institute will be (with his host, CERN’s Connie Potter) next planet for the past century (Nature on hand to educate people about to a poster-sized, antihydrogen-themed 311). particle physics.” cover of the Courier. One can only assume Forbes magazine (27 March) trails the legendary lyricist, waiting for someone “I never thought I’d have this the lineup at this year’s Roskilde or something to show him the way, was kind of money, so it was all a bit Festival in Denmark, 29 June – struck by the spectral similarities to the hypothetical. It would be nice 7 July. cover ar t of Dark Side of t he Moon.

74 CERN COURIER MAY/JUNE 2019

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