CERN Courier – Digital Edition Twin Bids for a 100 Km Collider Welcome to the Digital Edition of the January/February 2019 Issue of CERN Courier

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CERNJanuary/February 2019 cerncourier.com COURIERReporting on international high-energy physics

WELCOME Coming to terms with naturalness Individual recognition in particle physics CERN Courier – digital edition Twin bids for a 100 km collider Welcome to the digital edition of the January/February 2019 issue of CERN Courier. LHC EXPERIMENTS

Particle physics rarely stands still, and the articles in this issue offer a snapshot REBORN of activities under way at CERN and elsewhere to secure the field into the next decade and beyond. Chief among these are the upgrades to the LHC experiments. Already exceeding its design luminosity, the LHC and its injector chain were shut down at the end of 2018 for two years of maintenance and upgrades, many of which are geared towards the High-Luminosity LHC (HL-LHC) scheduled to operate from 2026. To maximise the physics potential of this unique machine, the seven LHC experiments are using the current “long-shutdown two” to overhaul their detectors – a massive and complex effort that will continue during long-shutdown three beginning in 2024. HL-LHC promises a rich physics programme lasting into the 2030s at this curious time for the field, but strategic decisions need to be taken soon to ensure that there is minimal gap between the LHC and the next major collider. In recent months, China and Europe have launched design reports for a 100 km machine that would open a new era of exploration, while a decision is also imminent regarding a possible international linear collider in Japan. These and numerous other considerations will shape the upcoming update of the European Strategy for Particle Physics, more than 150 submissions for which were received by the deadline of 18 December.

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EDITOR: MATTHEW CHALMERS, CERN 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 1 J a N u a r y /F e b r u a r y 2 01 9 It’s Time for a New Generation

of Power Solutions! MilaneseA CER N-PHO T O-201809-217-34 A LICE-PHO-SK E-2017-002-27 FOR RESISTIVE AND SUPERCONDUCTING MAGNETS

Future collider Magnet design for an CT-BOX Upgrade central The ALICE inner detectors. 25 FCC-ee quadrupole. 38 On stage Edoardo Amaldi’s life. 50 All-In-One Current Measurement and Calibration System 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 Bids for a 100 km collider CMS explores Wuppertal summer James Stirling 1953– Full-Bipolar operation, Digital Control Loop, Ethernet Connectivity Standing out from Actinides end with spin of top-quark school DIS2018 2018 John Mulvey Device supported by Visual Easy-Driver software • • the crowd • lawrencium • First pairs • Shining • RUPAC2018 • LHCb ECFA explores how to 1929–2018 • Paul beam at FACET-II • New light on the proton workshop • CERN– recognise individual Baillon 1938–2018. 57 FAST-PS-M centre for precision with ALICE • Dark- South Africa milestone achievement in large Digital Monopolar Power Supplies - up to 100 A studies • Collider hunts sector exploration at • ISOLDE workshop scientific collaborations. dark energy Fast ATLAS Real-time CERN-Austria PhD High-Precision Monopolar Power Converters with Gigabit Ethernet • • • 53 radio bursts. 8 triggering for LHCb. 15 programme. 18 Embedded Linux OS, device supported by Visual PS software FeaTureS FAST-PS Digital Bipolar Power Supplies - up to ±30 A and ±80 V ALICE UPGRADE CMS UPGRADE ATLAS UPGRADE LHCb UPGRADE FUTURE CIRCULAR COLLIDER Full-Bipolar, Digital Control Loop, High-Bandwidth, 10/100/1000 Ethernet ALICE revitalised CMS has high ATLAS upgrades LHCb’s momentous Embedded Linux OS, device supported by Visual PS software The ALICE experiment luminosity in sight in LS2 metamorphosis A giant leap for is being upgraded to A challenge for CMS is New wheel-shaped The LHCb detector is to physics make even more precise to prepare the detector detectors are be practically rebuilt to A 100 km supercollider FAST-PS-1K5 measurements of for future installations among numerous allow it to collect physics at CERN would open a Digital Bipolar Power Supplies - up to ±100 A and ±100 V extreme nuclear matter. necessary for HL-LHC. transformations events at a rate 10 times new era in fundamental 1.500 W, Paralleling via SFP/SFP+, 1 ppm/K TC, 10/100/1000 Ethernet 25 28 taking place. 31 higher than today. 34 exploration. 38 Embedded Linux OS, device supported by Visual PS software

NGPS oPINIoN DeParTmeNTS High-Stability 10-kW Power Supply - 200 A / 50 V Digital Control Loop, Paralleling via SFP/SFP+, 10/100/1000 Ethernet VIEWPOINT INTERVIEW REVIEWS FROM THE EDITOR 5 Embedded Linux OS, device supported by Visual PS software Good strategy Understanding How beauty leads NEWS DIGEST 7 demands the naturalness physics astray LIFE BEYOND CERN 54 right balance Theorist Nathaniel Craig Hossenfelder is Lost in CERN-PHOTO-201812-335-1 CERN-PHOTO-201812-335-1 APPOINTMENTS 55 Tatsuya Nakada reflects discusses the pros and Math • Performance on the European Strategy cons of naturalness in celebrates Amaldi’s life RECRUITMENT 61 for Particle Physics. 43 high-energy physics. 45 • Short reviews. 49 On the cover: ALICE being BACKGROUND 66 opened up in December. 25

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CernCourier_CAENels_December_BFC.indd 1 25/10/18 18:14 CCJanFeb19_Conts_v4.indd 3 16/01/2019 15:55 CERNCOURIER www. V o l u m e 5 9 N u m b e r 1 J a n u ary /F e b r u a r y 2 0 1 9 CERNCOURIER.COM FROM THE EDITOR

New-look CERN Courier captures a field in motion

elcome to the redesigned first issue of 2019. Particle CERN-PHOTO-201901-002 p hy sic s r a re ly s t a nd s s t i l l, a nd t he a r t ic le s i n t h i s W issue offer a snapshot of activities under way at C E R N a n d e l s e w h e r e t o s e c u r e t h e fie ld i nt o t h e n e x t d e c a d e a nd b e yond. C h ie f a mong t he s e a re t he upg r ade s to t he LHC e x p e r i me nt s t o c o p e w it h t he re le nt le s s p e r for m a nc e o f t he machine so far and in the years ahead. Already exceeding its design luminosity, the LHC and its injector chain were shut down at the end of 2018 for two years of maintenance and upgrades, many of which are geared towards the High- Matthew Lu m i no sit y LHC (HL-LHC) s c he du le d to o p e r ate f rom 2026. Chalmers To ma ximise the physics potential of this unique machine, Editor t h e s e v e n L HC e x p e r i m e nt s a r e u s i n g t h e c u r r e nt “l o n g-s hut- down two” to overhaul their detectors (p23–37) – a massive a n d c o m pl e x e ffor t t h a t w i l l c o nt i nu e d u r i n g l o n g-s hut down three beginning in 2024. HL-LHC has been a priority of European particle physics and promises a rich physics programme lasting into the 2030s at this curious time (p19 and 45) for the field. To ensure that there is minimal gap between the LHC and the next major collider in particle physics, strategic decisions need to be taken soon. In recent months, China and Europe have launched design reports for a 100 km collider that would open a new era of exploration (p8 and 38). A decision is also Maximising potential The removal of the LHCb beam pipe imminent regarding a possible international linear collider in January as part of a major upgrade. in Japan, with potential ramifications for other proposals suc h a s CER N’s C omp ac t L i nea r C ol l ide r. The s e a nd nu me r- website launched in 2019. This transformation, informed by ous other considerations will shape the upcoming update our recent reader sur vey (CERN Courier December 2018 p56) of the European Strategy for Particle Physics, more than a n d e x p e r t l y g u i d e d b y I n s t it ut e o f P h y s i c s P u bl i s h i n g i n t h e HL-LHC 150 submissions for which were received by the deadline of U K, t a k e s f u l l a d v a nt a g e o f t h e m o d e r n p u bl i s h i n g l a n d s c a p e promises a 18 December (p9 and 43). to allow more efficient w ays to communicate. rich physics C e l e br a t i n g it s 60 t h a n n i v e r s a r y t h i s s u m m e r, t h e Courier Introducing the new format looks forward to reporting on developments across interna- programme W hat bet ter w ay to c h ron ic le t he e xc it i ng t i mes a head t ha n t i o n a l p a r t i c l e-p h y s i c s i n a t i m e l y m a n n e r, a n d t o s t r e n g t h- at this curious a new incarnation of CERN Courier. The refreshed magazine e n i n g it s role a s a for u m for t h e e x c h a n g e a n d i nt e r ro g at io n time for d e s i g n a n d s t r u c t u r e a r e p a r t o f a n o v e r h a u l t h a t w i l l s e e t h e of knowledge and ideas. All feedback is welcome via the t he fie ld pr int issue publ ished si x t imes per year and a dy namic new contacts below, and I w ish you an enjoy able read.

Reporting on international high-energy physics

CERN Courier is d ist r ibuted 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 A na L opes Laboratory Tom L eCompte JINR Dubna B St a rc hen ko Samantha Kuula A l ison Tove y General distribution individual subscribers. Reviews editor Brookhaven National KEK National Laboratory TRIUMF Laboratory Advertising sales Courrier Adressage, It is published six times Virginia Greco Laboratory Ac h i m Fr a n z Hajime Hikino Marcello Pavan Tom Houlden CERN, 1211 Geneva 23, per year. The views Archive contributor Cornell University Lawrence Berkeley Recruitment sales Switzerland; e-mail expressed are not Peg g ie R i m mer D G Cassel Laboratory Spencer K lei n Produced for CERN by Chris Thomas courrier-adressage@ necessa r i ly t hose of t he Astrowatch contributor DESY Laboratory Los Alamos National Lab IOP Publishing Ltd Advertisement cern.ch CERN management. Merlin Kole Till Mundzeck Raja n Gupt a Temple Circus, Temple production Kat ie Gr a ha m E-mail Enrico Fermi Centre NCSL Ken Kingery Way, Bristol BS1 6HG, UK Marketing and Published by CER N, 1211 [email protected] Guido Piragino Nikhef Robert Fleischer Tel +4 4 (0)117 929 7481 circulation Geneva 23, Switzerland Fermilab Kurt Novosibirsk Institute Angela Gage, Tel +41 (0) 22 767 61 11 Advisory board Riesselmann S Eidelman Head of B2B and Laura Gillham Peter Jen n i, Ch r ist i ne Forschungszentrum Orsay Laboratory journalism Jo A l len Printed by Wa r ners Sut ton, Claude Jülich Markus Buescher Anne-Marie Lutz B2B commercial Advertising (Midlands) plc, Bourne, Amsler, Philippe GSI Darmstadt I Peter PSI Laboratory P-R Kettle operations manager Tel +44 (0)117 930 1026 Lincolnshire, UK Bloc h, Roger For t y, IHEP, Beijing Lijun Guo Saclay Laboratory Ed Jost (for UK/Europe display M i ke L a mont, IHEP, Serpukhov Elisabeth Locci Art director advertising) or +44 (0)117 © 2019 CER N Matthew Mccullough Yu Ry abov UK STFC Ja ne Bi n k s Andrew Giaquinto 930 1164 (for recruitment ISSN 0304-288X

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High-Speed Cameras for Visible, Soft NEWS X-Ray, VUV and EUV Applications DIGEST Princeton Instruments is the trusted choice for synchrotrons and laboratories worldwide! New centre for particle physics SNO+ searches for nucleon decay Belle II vertex detector installed R Hurt The German Research Foundation Many grand unified theories The final piece has been inserted has established a new transregional predict the existence of nucleon i nt o t he B e l le II d e t e c t or (pic t u re d) centre to explore physics beyond decay as a mechanism to allow at the SuperKEKB accelerator in Crystallography | Attosecond Research the Standard Model with state- baryon-number violation and Japan. When fully commissioned, of-the-art theoretical methods potentially explain the matter– Belle II – the “super-B factory” X-Ray Absorption Spectroscopy | EUV/X-Ray and new search strategies. The antimatter asymmetry in the uni- up g r a d e o f t h e B e l l e d e t e c t or – w i l l Diffraction/Scattering | High Harmonic Soft X-ray | SAXS/GISAXS centre, called Phenomenological verse. A new search for invisible detect events at the much higher Elementary Particle Physics after nucleon decays has been conducted rates provided by the 40-fold higher the Higgs Discovery, will be funded during the initial water phase of design luminosity of SuperKEKB f r o m Ja nu a r y i n it i a l l y for fo u r y e a r s the SNO+ detector in Canada, c o m p a r e d t o K E K B. T h i s fi n a l c om- with a total of around €12 million. before the detector runs with a ponent, the vertex detector, has two Artist’s impression of a It involves the Karlsruhe Institute scintillator (arXiv:1812.05552). parts that now complete the overall gravitational-wave event. of Technology (host institute), the Invisible nucleon decays could detector: a two-layer pixel detec- University of Siegen and RWTH be detected through gamma rays tor based on “DEPFET” technology, New gravitational-wave events Aachen, in addition to researchers emitted by the de-excitation of and a four-layer double-sided sil- The LIGO and VIRGO collaborations f rom t he Un iver sit y of He ide lb erg. a n e x c it e d d a u g ht e r o f t h e o x y g e n icon-strip detector. The first layer have detected four new gravita- T h e c e nt r e i s o n e o f 10 n e w c ol l a b o - nuc le u s. The ne w SNO+ s e a rc h for lies just 14 m m f r o m t h e i nt e r a c t i o n tional-wave events, bringing the rative research centres in Germany such gamma rays has resulted in point to improve Belle II’s vertex total number of observed events designed to enable researchers to limits of 2.5 × 1029 yr for the par- resolution significantly. si nce t he fi rst dete c t ion i n 2015 to pursue challenging, long-term tial lifetime of the neutron, and

11. Ten of these events are from research projects. 3.6 × 1029 y r for t he p a r t i a l l i fe t i m e KEK black-hole mergers, and one is of the proton, the latter being a f r o m a n e ut r o n-s t a r m e r g e r. O f t h e Most precise electron moment 70% improvement over the pre- black-hole events, the new event The ACME collaboration at Harvard v ious limit from SNO. GW170729 is the most massive Un i v e r s it y’s Je ffe r s o n P h y s ic a l L ab - and distant gravitational-wave or a t or y i n t h e US h a s p e r for m e d t h e Gluon revelation in the pion source ever observed – it con- most precise measurement of the Gluons contribute more to the total Soft X-Ray Visible verted almost five solar masses e l e c t r ic d i p ol e m o m e nt (E DM) o f t h e momentum of the pion – which is into gravitational radiation and electron (Nature 562 355), provid- the lightest hadron – than pre- t o o k pl a c e a b o ut 5 bi l l i o n y e a r s a g o. ing a powerful test of the Stand- viously thought. That’s the con- The teams describe their results ard Model (SM). The SM predicts clusion of Patrick Barry of North The vertex detector being ® PI-MTE3 KURO™ in a catalogue that comprises a non-zero but very small EDM, Carolina State University and incorporated into Belle II. SOPHIA -XO confirmed and candidate events whereas extensions of the SM such co-workers, who have published (a r X i v:181 1.1 2907) a n d a n a n a l y s i s as supersymmetry posit larger and t h e fi r s t g l o b a l Q C D a n a l y s i s o fthe Metamaterial for acceleration Proven Back-illuminated, Back-illuminated of the properties of the black-hole potentially measurable EDMs, in parton dist ribution functions of A team led by Richard Temkin at the in-vacuum 4-port CCD scientific CMOS mergers (arXiv:1811.12940). the range 10–27–10–30. By measur- the pion (Phys. Rev. Lett. 121 152001). Massachusetts Institute of Tech- ing the electron spin precession in By using a Monte Carlo approach nology in the US has shown that cameras cameras cameras Open-science cloud launched a superposition of quantum states based on nested sampling, the an artificially engineered “meta- On 23 November, the European of electrons subjected to a huge analysis combined data from material” could be an alternative ► 2k x 2k and 4k x 4k ► 2k x 2k and 4k x 4k ► Excellent sensitivity in the 200nm - 1100nm range Commission launched the European e l e c t r i c fie l d, t h e AC M E e x p e r i m ent fixed-target and collider exper- to materials currently used in the ► Up to 3 fps ► Up to 3 fps Open Science Cloud (EOSC) – an ( pic t u r e d) m e a s u r e d a n up p e r l i m it iments to show that gluons con- emerging technology of wakefield ► 120 fps at 800 x 800 open environment for research- for the electron’s EDM of 1.1 × 10–29 e. tribute 30% of the total pion acceleration. This t y pe of acceler- ► Low outgassing ► 95% QE, back-illuminated ► 47 fps at 2k x 2k ers to store, analyse and re-use cm – 8.6 times smaller than the momentum – which is three times ation relies on the intense electro- ► Designed for SAXS, GIXD ► Low-noise, deep-cooled ► 100% fill factor data for research, innovation and best previous limit, also by ACME. more t han t he prev ious est imate. m a g n e t i c fie l d pr o d u c e d i n t h e w ake ► 95% quantum efficiency educational purposes. EOSC has of an electron bunch that travels emerged following extensive dis- Physics resumes at RHIC through a plasma or dielectric ► Large 11 x 11 um pixels - wide dynamic range cussions with research infrastruc- The 19th year of physics operations material to accelerate particles, tures and scientists working across Univ. Harvard has commenced at the Relativis- and can reach higher accelerat- d i s c i pl i n e s. For t h e a s t r o n o m y a n d tic Heavy Ion Collider (RHIC) at ing gradients than conventional p a r t ic l e-p h y s ic s fie l d s, t h e E S C A PE Brookhaven National Laboratory techniques. However, it has dis- project brings together the relevant in the US. This year the collider advantages such as limited tuna- NOTE: Princeton Instruments x-ray cameras are compatible with EPICS software. research infrastructures, includ- is being reconfigured for a low- bility of the plasma (or dielectric) ing CERN, to address their open- er-energy run to look for signs of and a lower beam quality. Temkin data science challenges and help a critical point in the nuclear phase and co-workers have engineered a Visit www.princetoninstruments.com to learn more about build EOSC. Under the commis- diagram at which the transition metamaterial, made of steel and sion’s Horizon 2020 programme, from ordinary matter to a quark– copper plates, that has both a high these and other Princeton Instruments products €600 million has been allocated gluon plasma switches from abrupt gradient and a high degree of tun- to setting up EOSC by 2020. The ACME experimental set-up. to continuous. abilit y (Phys. Rev. Lett. 122 014801). [email protected] | Phone: +1 609 587 9797

CERN COURIER JANUARY/FEBRUARY 2019 7

Untitled-1 1 24/10/2018 10:14 CCJanFeb19_NewsDigest_v4.indd 7 16/01/2019 15:57 CERNCOURIER www. V o l u m e 5 9 N u m b e r 1 J a n u ary /F e b r u a r y 2 0 1 9 CERNCOURIER.COM CERNCOURIER.COM NEWS NEWS ANALYSIS an eight-year period for project prepa- Input received for European strategy update ANALYSIS ration and administration is required before construction of FCC’s underground The European Strategy for transfer. The rest are spread areas can begin, potentially allowing the Particle Physics (ESPP) was over the eight different FCC-ee physics programme to start by initiated in 2006 to coordinate themes that have been defined 2039. The FCC-hh, installed in the same activities across a large, for the process: accelerator FCC study tunnel, could then start operations in the international and fast-moving science and technology, late 2050s. “Though the two machines community (CERN Courier April beyond the Standard Model at can be built independently, a combined 2018 p7). 18 December 2018 was colliders, dark matter and the s c e n a r i o pr o fit s f r o m t h e e x t e n s i v e r eus the deadline for the submission continent (such as the CEPC dark sector, instrumentation of civil engineering and technical sys- of materials for the second proposal). Of these, about a and computing, electroweak tems, and also from the additional time update of the ESPP, which will quarter concern national road physics, flavour physics, available for high-field magnet break- define the long-term priorities maps or are submissions from neutrino physics, and throughs,” says deputy leader of the of the field to the mid-2020s national organisations or strong interactions. The FCC study Frank Zimmermann of CERN. and beyond. The European funding agencies, another 20 or proposals will be discussed “Timely preparation, early investment Strategy Group (ESG), which so concern large experiments at a public symposium in and diverse collaborations between was established at the end of or projects (about half of which, Granada, Spain, on researchers and industry are already 2017 to coordinate the update including the FCC and CLIC 13-16 May, after which a yielding promising results and confirm- process, received a total of 160 studies, target CERN as the “briefing book” will be ing the anticipated downward trend in contributions – predominantly host laboratory), and a similar prepared and submitted to the costs associated with operation.” from Europe but including number concern education, the ESG for consideration in projects that extend beyond the outreach and technology January 2020. Asian ambition CEPC is a putative 240 GeV circular electron-positron collider, the tunnel this value, while, at present, a hadron obvious, in view of our present theo- for which is foreseen to one day host a collider on either continent would cost retical understanding, whether or not a super proton–proton collider (SppC) that s i g n i fic a nt l y m or e d u e t o t h e c o s t ofthe 100 k m a c c e l e r a t or w i l l b e a bl e t o e n for c e reaches energies beyond the LHC (CERN required superconducting wire. Geoffrey a brea k t h roug h, he s ay s. “Mos t t he ore- Courier June 2018 p21). The two-volume Taylor of the University of Melbourne, ticians were hoping that the LHC might C E P C d e s i g n r e p or t s u m m a r i s e s t h e w or k who is chair of the International Com- open up a new domain of our science, accomplished in the past few years by mittee for Future Accelerators, says that and this does not seem to be happening. thousands of scientists and engineers CERN has the major benefit of magnet I am just not sure whether things will in China and abroad. IHEP states that expertise and high-energy collider be any different for a 100 km machine. construction of CEPC will begin as soon development and operation, in addi- It would be a shame to give up, but the Big thinking A visualisation of the 100 km circumference FCC tunnel and machine. as 2022 – allowing time to build proto- tion to already having the multi-bil- question of whether spectacular new types of key technical components and lion-dollar accelerator infrastructure physical phenomena will be opened up AccelerAtors establish support for manufacturing – required for the project. “The value of and whether this outweighs the costs, I and be completed by 2030. According to this infrastructure at CERN outweighs cannot answer. On the other hand, for us China and Europe bid for post-LHC collider t h e t e nt a t i v e o p e r a t i o n a l pl a n, C E P C w i l l the cost of the tunnel; on the other hand, theoretical physicists the new machines run for seven years as a Higgs factory, the Chinese proposal has a lower cost of w i l l b e i m p or t a nt e v e n i f w e c a n’t i m pr e s s The discovery of the Higgs boson at the was a direct response to a request from regions to express the same judgment.” followed by two years as a Z factory and t u n n e l i n g b ut l a c k s t h e i m m e n s e i n f r a- the public with their results.” LHC in the summer of 2012 set parti- the 2013 update of the European Strategy The four-volume FCC report demon- one year at the WW threshold, potentially structure and expertise necessary for cle physics on a new course of explora- for Particle Physics to prepare a post- strates the project’s technical feasibility followed by the installation of the SppC. the hadron collider.” Profound discoveries tion. While the LHC experiments have LHC machine, following preliminary a n d i d e nt i fie s t h e p h y s i c s o p p or t u n it ies A l t h o u g h C E P C–S p p C i s a C h i n e s e-pr o - Taylor says that whilst it is essential Experimentalist Joe Incandela of the determined many of the properties of proposals for a circular Higgs factory at o ffe r e d b y t h e d i ffe r e nt c ol l id e r o p tions: posed project to be built in China, it has that CERN maintains its pre-eminent University of California in Santa Bar- the Higgs boson with a precision beyond CERN in 2011), and both envisage physics a high-luminosity electron–positron an international advisory committee position, having competition from Asia b a r a, w h o w a s s p o k e s p e r s o n o f t h e C M S expectations, and will continue to do so programmes extending deep into the 21st collider (FCC-ee) with a centre-of-mass a n d m or e t h a n 20 a g r e e m e nt s h a v e b e e n w it h t h e p o t e nt i a l for m aj or i n v e s t m e nt experiment at the time of the Higgs-bo- until the mid-2030s, physicists have long century. Documents concerning the FCC energy ranging from the Z pole (90 GeV) signed with institutes and universities would be beneficial for the field as a son discovery, believes that a post-LHC – planned a successor to the LHC that can and CEPC proposals were also submitted to the tt threshold (365 GeV); a 100 TeV around the world. whole because Western investment in collider is needed for closure – even if it further explore the Higgs mechanism as input to the latest update of the Euro- proton–proton collider (FCC-hh); a future “T h e B e iji n g E l e c t r o n P o s it r o n C ol l i d e r future machines may well remain at does not yield new discoveries. “While and other potential sources of new phys- pean Strategy for Particle Physics at the lepton–proton collider (FCC-eh); and, will stop running in the 2020s, and Chi- current levels. There are also broader such machines are not guaranteed to ics. Several proposals are on the table, end of the year (see panel, right). fi n a l l y, a h i g h e r- e n e r g y h a d r o n c ol l id er n a’s g o v e r n m e nt i s e n c o u r a g i n g C h i n e s e cultural factors to be considered, says yield definitive evidence for new phys- the most ambitious and scientifically “If a high-luminosity electron– in the existing tunnel (HE-LHC). The FCC scientists to initiate and work towards Q u i g g: “C E R N h a s e a r n e d a n e x e m pl a r y ics, they would nevertheless allow us to far-reaching involving circular colliders positron Higgs factory were to drop out is a global collaboration of more than large international science projects, so reputat ion for i nc lusiveness a nd open- largely complete our exploration of the If a high- Having with a circumference of around 100 km. of the sky tomorrow, the line of users 140 universities, research institutes and it is possible that CEPC may get a green ness, which go hand in hand with sci- weak scale,” he says. “This is impor- On 18 December, the Future Circular luminosity would be very long, while a very-high- i n d u s t r i a l p a r t n e r s. D u r i n g t h e p a s t fi v e l i g ht s o o n,” e x pl a i n s d e p ut y l e a d e r o f t h e entific excellence. Any region, nation, competition tant because it is the scale where our Collider (FCC) study released its con- electron– energy hadron collider is a vessel of years, with the support of the European CEPC project Jie Gao of IHEP. “As for the and institution that aims to host a from Asia with observable universe resides, where we ceptual design report (CDR) for a 100 km positron Higgs discovery and will help us study the Commission’s Horizon 2020 programme, site, many Chinese local governments world-leading instrument must strive the potential l i v e, a n d it s h o u l d b e f u l l y c h a r t e d b e for e collider based at CERN. A month earlier, factory were to role of the Higgs boson in taming the the FCC collaboration has made signif- s h o w e d s t r o n g i nt e r e s t t o h o s t C E P C w it h for a similar env ironment.” for major the energy frontier is shut down. Com- the Institute of High Energy Physics drop out of the high-energy behaviour of longitudinal icant advances in high-field super- t h e s u p p or t o f t h e c e nt r a l g o v e r n m e nt.” For theorist Gerard ’t Hooft, who investment pleting our study of the weak scale would (I H E P) i n C h i n a o ffic i a l l y pr e s e nt e d a CDR gauge-boson (WW) scattering,” says conducting magnets, high-efficiency C o s t i s a k e y f a c t or for b o t h t h e C h i n e s e shared the 1999 Nobel Prize in Physics cap a short but extraordinary 150 year- sky tomorrow, would be for a similar project called the Circular theorist Chris Quigg of Fermilab in the radio-frequency cavities, vacuum sys- a nd Eu rop ea n proje c t s, w it h t he t u n ne l for elucidating the quantum structure long period of profound experimental Electron Positron Collider (CEPC). Both the line of US. “It is a very significant validation tems, large-scale cryogenic refrigeration t a k i n g u p a l a r g e f r a c t i o n o f t h e e x p e n s e. o f e l e c t r o w e a k i nt e r a c t i o n s, t h e p h y s i c s beneficial for and theoretical discoveries that would studies were launched shortly after the users would be of the scientific promise opened by a and other enabling technologies (see p38). CEPC’s price tag is currently $5 billion target of a 100 km collider is far more the field as a stand for millennia among mankind’s s discovery of the Higgs boson (the FCC very long 100 km ring for scientists of different According to the present proposal, a n d FCC-e e i s ho v e r i n g at a ro u n d t w ic e important than its location. It is not whole greatest achievements.”

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NEWS ANALYSIS NEWS ANALYSIS SLAC Periodic table erators send a bunch of very energetic particles through a hot ionised gas to Actinide series shown to end with lawrencium create a plasma wake on which a trailing bunch can “surf” and gain energy. This leads to acceleration gradients that are et al. Source: Sato et One hundred and fifty years since (97) (98) (99) (100) (101) (102) (103) r e n c iu m, w h i c h i s e s s e nt i a l t o c o n fi r m t h e much higher and therefore potentially Dmitri Mendeleev revolutionised Bk Cf Es Fm Md No Lr fi l l i n g o f t h e 5 f s h e l l i n t h e h e a v y a c tinides to smaller machines, but several cru- chemistry with the periodic table of 7 (see figure). The results agree well with cial steps are required before plasma the elements, an international team of 2018 those predicted by state-of-the-art rel- accelerators can become a reality. This researchers has resolved a longstanding actinides ativistic calculations in the framework is where FACET-II comes in, offering question about one of its more mysterious of QED and confirm that the ionisation higher-quality beams than FACET, regions – the actinide series (or actinoids, 6 values of the heavy actinides increase up explains project scientist Mark Hogan. as adopted by the International Union to nobelium, while that of lawrencium is “We need to show that we’re able to Aerial view tools that will accurately measure and facilit y’s first r un. lanthanides of Pure and Applied Chemistry, IUPAC). the lowest among the series. preserve the quality of the beam as it SLAC’s other major simulate the physics of the new facil- Last year, the AWAKE experiment at (eV) The periodic table’s neat arrangement 1 The results demonstrate that the 5f passes through plasma. High-quality facilities, the Linac ity’s beams. The FACET-II design also CERN demonstrated the first ever accel- IP of rows, columns and groups is a conse- 5 or bit a l i s f u l l y fi l l e d a t n o b e l iu m (w it h t he beams are an absolute requirement for Coherent Light allows for adding the capability to pro- eration of a beam in a proton-driven quence of the electronic structures of the [Rn] 5f 14 7s2 electron configuration, where future applications in particle and X-ray Source (LCLS) and duce and accelerate positrons at a later plasma (CERN Courier October 2018 chemical elements. The actinide series [R n] i s t h e r a d o n c o n fi g u r a t i o n) a n d t h at laser physics.” Stanford stage, paving the way for plasma-based p7). Laser-driven plasma-wakefield has long been identified as a group of lawrencium has a weakly bound electron, SLAC has a rich history in develop- Synchrotron electron–positron colliders. acceleration is also receiving much heavy elements starting with atomic 4 confirming that the actinides end with ing such techniques, and the previous Radiation FACET-II has issued its first call for attention thanks to advances in high- number Z = 89 (actinium) and extend- lawrencium. The nobelium measurement FACET facility enabled researchers to Lightsource (SSRL). proposals for experiments that will run power lasers (CERN Courier November Tb Dy Ho Er Tm Yb Lu ing up to Z = 103 (lawrencium), each of (65) (66) (67) (68) (69) (70) (71) also agrees well with laser spectroscopy demonstrate electron-driven plasma when the facility goes online in 2020. In 2018 p7). “The FACET-II programme which is characterised by a stabilised measurements made at the GSI Helm- acceleration for both electrons and mid-October, prospective users of FAC- is very interesting, with many plas- 7s2 outer electron shell. But the electron holtz Center for Heavy Ion Research in positrons. FACET-II will use the mid- ET-II presented their ideas for a first ma-wakefield experiments,” says c o n fi g u r a t i o n s o f t h e h e a v i e s t e l e m ents Heavy elements Using the same technique, Sato and Darmstadt, Germany. dle third (corresponding to a length of round of experiments for evaluation, technical coordinator and CERN project of this sequence, from Z = 100 (fermium) The first ionisation co-workers measured the first ionisa- “The experiments conducted by Sato 1 km) of SLAC’s linear accelerator to and the number of proposals is already leader for AWAKE, Edda Gschwendtner, o n w a rd s, h a v e b e e n d i ffic u l t t o m e a s u r e, potential values of tion potential of lawrencium back in et al. constitute an outstanding piece of generate a 10 GeV electron beam, kitted larger than the number of experiments who is also chair of the FACET-II pro- preventing confirmation of the series. the heavy actinides 2015. Since this is the energy required to work at the top level of science,” says out with diagnostics and computational that can possibly be scheduled for the gramme advisory committee. The reason for the difficulty is that ele- and lanthanides, remove the most weakly bound electron Andreas Türler, a chemist from the Uni- H Katori ments heavier than fermium can be pro- with closed circles from a neutral atom and is a fundamental versity of Bern, Switzerland. “As the Precision measurement actions and symmetries using the produced only one atom at a time in nuclear representing the property of every chemical element, it authors state, these measurements pro- German–Japanese tons and antiprotons available at the reactions at heavy-ion accelerators. latest work. was a key step towards mapping lawren- vide unequivocal proof that the actinide BASE experiment at CERN are another cium’s electron configuration. The result series ends with lawrencium (Z = 103), as centre to focus on key aspect of the German–Japanese initi- Confirmation suggested that lawrencium has the lowest the filling of the 5f orbital proceeds in a ative, explains Stefan Ulmer, co-director Now, Tetsuya Sato at the Japan Atomic fi r s t io n i s a t io n p o t e nt i a l o f a l l a c t i n ides, very similar way to lanthanides, where precision physics of the centre, chief scientist at RIKEN, and Energy Agency (JAEA) and colleagues as expected owing to its weakly bound t h e 4 f or bit a l i s fi l l e d. I a m a l r e a d y e a g e rly spokesperson of the BASE experiment:

have used a surface ion source and isotope electron in the 7p1/2 valence orbital. But looking forward to an experimental On 1 January a new virtual centre devoted “This centre will strongly promote fun- mass-separation technique at the tan- with only this value the team couldn’t determination of the ionisation poten- to some of the most precise measure- damental physics in general, in addition dem accelerator facility at JAEA in Tokai confirm the expected increase of the ion- tial of r ut her fordium (Z = 104) using t he ments in science was established by to the research goals of BASE. Given this to show that the actinide series ends with isation values of the heavy actinides up to same experimental approach.” researchers in Germany and Japan. The support we are developing new equip- lawrencium. “This result, which would nobelium (Z = 102). This occurs with the Centre for Time, Constants and Fun- ment to improve both the precision of the confirm the present representation of fi l l i n g o f t h e 5 f e l e c t r o n s h e l l i n a maner Further reading damental Symmetries will offer access proton-to-antiproton charge-to-mass the actinide series in the periodic table, similar to the filling of the 4f electron T Sato et al. 2015 Nature 520 209. to ultra-sensitive equipment to allow ratio as well as the proton/antiproton is a serious input to the IUPAC working shell until ytterbium in the lanthanides. T Sato et al. 2018 J. Am. Chem. Soc. 140 experimental groups in atomic and magnetic moment comparison by factors group, which is evaluating if lawrencium In their latest study, Sato and colleagues 14609. nuclear physics, antimatter research, of 10 to 100.” is indeed the last actinide,” says team have determined the successive first ion- P Chhetri et al. 2018 Phys. Rev. Lett. 120 quantum optics and metrology to col- To reach these goals, the researchers member Thierry Stora of CERN. isation potentials from fermium to law- 263003. laborate closely on fundamental meas- intend to develop novel experimental urements. Three partners – the Max techniques – such as transportable SLAC accelerators First beam peer-reviewed basis. Planck Institutes for nuclear physics antiproton traps, sympathetic cooling First beam at SL AC Photoelectrons “As a strategically important national (MPI-K) and for quantum optics (MPQ), intrinsically must exist, otherwise the On time A lattice of antiprotons by laser-cooled beryl- produced at user facility, FACET-II will allow us to the National Metrology Institute of Ger- universe would consist of almost pure clock at RIKEN, one lium ions, and optical clocks based on plasma facility FACET-II on explore the feasibility and applications many (PTB) and RIKEN in Japan – agreed radiation. Closely related to these tests of the partners of highly charged ions and thorium nuclei 20 September. of plasma-driven accelerator technol- to fund the centre in equal amounts with of fundamental symmetries is the the new Centre for – which will outperform contemporary ogy,” said James Siegrist of the DOE a total of around €7.5 million for five search for physics beyond the Standard Time, Constants methods and enable measurements FACET-II, a new facility for accelerator O ffic e o f S c i e n c e. “We’r e l o o k i n g for ward years, and scientific activities will be Model. The broad research portfolio also and Fundamental at even shorter time scales and with research at SLAC National Accelerator to seeing the groundbreaking science in coordinated at MPI-K. includes the development of novel optical Symmetries. improved sensitivity. “The combined Laboratory in California, has produced this area that FACET-II promises, with A major physics target of the German– clocks based on atoms, nuclei and highly precision-physics expertise of the indi- it s fi r s t e l e c t r o n s. FAC E T-II i s a n u p g r a de t h e p o t e nt i a l for a s i g n i fic a nt r e d u c t i o n Japanese centre is to investigate whether charged ions. vidual groups with their complemen- to the Facility for Advanced Accelera- in the size and cost of future accelera- the fundamental constants really are “It is fascinating that nowadays man- t a r y a p pr o a c h e s a n d d i ffe r e nt m e t h o d s tor Experimental Tests (FACET), which tors, including free-electron lasers and constant or if they change in time by ageable laboratory experiments make it using traps and lasers has the potential operated from 2011 to 2016, and will medical accelerators.” tiny amounts. Another goal concerns possible to investigate such fundamental for substantial progress,” says Ulmer. produce high-quality electron beams of Energy (DOE), will also operate as a Whereas conventional accelerators the subtle differences in the properties questions in physics and cosmology by “The low-energy, ultra-high-precision to develop plasma-wakefield accelera- federally sponsored research facility impart energy to charged particles of matter and antimatter, namely C, P means of their high precision”, says Klaus investigations for physics beyond the tion techniques. The $26 million project, for advanced accelerator research that via radiofrequency fields inside metal and T invariance, which have not yet Blaum of MPI-K. Standard Model will complement studies s recently approved by the US Department is open to scientists on a competitive, structures, plasma-wakefield accel- shown up, even though such differences Stringent tests of fundamental inter- in particle physics.”

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NEWS ANALYSIS NEWS ANALYSIS

Dark energy scale must be higher than approximately With this pioneering interpretation of The search for normally considered a very large-scale 300 GeV for the conformal coupling and a collider search in terms of dark-en- dark energy phenomenon, but you may justifiably above 1.2 TeV for the disformal coupling. ergy models, ATLAS has become the first ask how the study of small systems in Colliders join the hunt for dark energy at colliders The search for DE at colliders is only experiment to probe all forms of matter a collider can say anything about DE. at the beginning, says Argyropoulos. in the observable universe, opening a is only at the Perhaps it can, but in a fairly model-de- ATLAS It is 20 years since the discovery that the “The limits on the disformal coupling new avenue of research at the interface beginning p e n d e nt w a y. I f AT L A S fi n d s a s i g n a l t h at expansion of the universe is accelerating, are several orders of magnitudes higher of particle physics and cosmology. A departs from the SM prediction it would yet physicists still know precious little than the limits obtained from other lab- complementary laboratory measurement be very exciting. But linking it firmly to about the underlying cause. In a classical oratory experiments and cosmological is also being pursued by CERN’s CAST DE would require follow-up work and universe with no quantum effects, the probes, proving that colliders can provide experiment, which studies a particular measurements – all of which would be cosmic acceleration can be explained by a crucial information for understanding incarnation of DE (chameleon) produced very exciting to see happen.” constant that appears in Einstein’s equa- the nature of DE. More experimental via interactions of DE with photons. tions of general relativity, albeit one with signatures and more types of coupling But DE is not going to give up its secrets Further reading a vanishingly small value. But clearly our between DE and normal matter have to easily, cautions theoretical cosmolo- ATLAS Collaboration 2018 ATL-PHYS- universe obeys quantum mechanics, and be explored and more optimal search gist Dragan Huterer at the University PUB 2018 008. t h e a bi l it y o f p a r t ic l e s t o flu c t u a t e i n a n d strategies could be developed.” of Michigan in the US. “Dark energy is P Brax et al. 2016 Phys. Rev. D. 94 084054. out of existence at all points in space leads to a prediction for Einstein’s cosmological AstrowAtch: FAst r Adio bursts constant that is 120 orders of magnitude larger than observed. “It implies that at Solving the next mystery in astrophysics least one, and likely both, of general relativity and quantum mechanics must In 2007, while studying archival data from Astron. Nat. observations. For a while, it was the only be f undamentally modified,” says Clare the Parkes radio telescope in Australia, 20 Parkes FRB found to do so, earning it the title

UTMOST 2 Burrage, a theorist at the University of Duncan Lorimer and his student David 865 “The Repeater”. But the recent detection GBT Nottingham in the UK. Narkevic of West Virginia University in 15 Arecibo by CHIME has now doubled the number miss ASKAP With no clear alternative theory avail- Dark analysis Events such as this, showing the second highest ET monojet event recorded in the 2016 ATLAS the US found a short, bright burst of radio of such sources. The detection of repeater able, all attempts to explain the cosmic data, were used to search for signs of dark energy. w a v e s. It t u r n e d o ut t o b e t h e fi r s t o b s er- Σ FRBs 61 FRBs could be seen as evidence that FRBs 10 acceleration introduce a new entity called vation of a fast radio burst (FRB), and are not the result of a cataclysmic event, dark energy (DE) that makes up 70% of and provide complementary information states with high-momentum transfers, further studies revealed additional events since the source must survive in order to

the total mass-energy content of the uni- to cosmological probes. such as those involving high-energy jets in the Parkes data dating from 2001. The FRBs per year 5 repeat. However, another interpretation verse. It is not clear whether DE is due to Unlike dark matter, for which there (“disformal” coupling). origin of several of these bursts, which is that there are actually two classes of a new scalar particle or a modification exists many new-physics models to were slightly different in nature, was 0 FRBs: those that repeat and those that of gravity, or whether it is constant or guide searches at collider experiments, Signatures later traced back to the microwave oven come from cataclysmic events. dynamic. It’s not even clear whether it few such frameworks exist that describe “In a big class of these operators the DE in the Parkes Observatory visitors centre. 200120022003200420052006200720082009201020112012201320142015201620172018 Until recently the number of theo- year interacts with other fundamental parti- the interaction between DE and Standard particle cannot decay inside the detector, After discarding these events, however, ries on the origin of FRBs outnumbered c l e s or n o t, s a y s B u r r a g e. Si n c e DE a ffe c t s Model (SM) particles. However, theorists therefore leaving a missing energy signa- a handful of real FRBs in the 2001 data the number of detected FRBs, showing the expansion of space–time, however, have made progress by allowing the t u r e,” e x pl a i n s S p y r i d o n A r g y r o p o u l o s o f remained, while more FRBs were being Stellar stats the pulse has traversed and therefore how difficult it is to constrain theoret- it s e ffe c t s a r e i m pr i nt e d o n a s t r o n o m ical properties of the prospective DE parti- the University of Iowa, who is a member found in data from other radio telescopes. Number of detected the distance it has travelled. In the case ical models based on the available data. observables such as the cosmic micro- cle and the strength of the force that it of the ATLAS team that carried out the The cause of FRBs has puzzled astron- FRBs up to July 2018. of FRBs, the measured delay cannot be Looking at the experience of a similar wave background and the growth rate transmits to vary with the environment. analysis. “Two possible signatures for the omers for more than a decade. But dedi- explained by signals travelling within field – that of gamma-ray burst (GRB) of galaxies, and the main approach to This effective-field-theory approach detection of DE are therefore the produc- cated searches under way at the Canadian the Milky Way alone, strongly indicating research, which aims to explain bright detecting DE involves looking for pos- integrates out the unknown microscopic tion of a pair of top-anti top quarks or the Hydrogen Intensity Mapping Experiment an extragalactic origin. fl a s h e s o f g a m m a r a y s d i s c o v e r e d d uring sible deviations from general relativity dynamics of the DE interactions. production of high-energy jets, associated (CHIME) and the Australian Square Kilo- The size of the emission region the 1960s – an increase in the number of on cosmological scales. The new ATLAS search was motivated with large missing energy. Such signa- metre Array Pathfinder (ASKAP), among responsible for FRBs can be deduced from detections and searches for counterparts by a 2016 model by Philippe Brax of the tures are similar to the ones expected other activities, are intensifying the their duration. The most likely sources in other wavelengths or in gravitational Unique environment Un i v e r s it é P a r i s-S a c l a y, B u r r a g e, C h r i s- by the production of supersymmetric search for their origin. Recently, while still are compact km-sized objects such as waves will enable quick progress. As the Collider experiments offer a unique toph Englert of the University of Glas- top quarks (“stops”), where the missing in its pre-commissioning phase, CHIME neutron stars or black holes. Apart from number of detected GRBs started to go environment in which to search for the gow, and Michael Spannowsky of Durham energy would be due to the neutralinos detected no less than 13 new FRBs – one of their extragalactic origin and their size, into the thousands, the number of the- direct production of DE particles, since University. The model provides the most from the stop decays or from the produc- them classed as a “repeater” on account not much more is known about the 70 or ories (which initially also included those they are sensitive to a multitude of sig- general framework for describing DE the- tion of SM particles in association with of its regular radio output – setting the so FRBs that have been detected so far. with extraterrestrial origins) decreased natures and therefore to a wider array ories with a scalar field and contains as dark-matter particles, which also leave a field up for an exciting period of discovery. Theories about their origin range from rapidly to a handful. The start of data of possible DE interactions with matter. subsets many well-known specific DE missing energy signature in the detector.” the mundane, such as pulsar or black- taking by ASKAP and the increasing Like other signals of new physics, DE (if models – such as quintessence, galileon, The ATLAS analysis, which was based Dispersion hole emission, to the spectacular – such sensitivity of CHIME means we can accessible at small scales) could manifest chameleon and symmetron. It extends on 13 TeV LHC data corresponding to an All FRBs have one thing in common: they as neutron stars travelling through look forward to an exponential growth itself in high-energy particle collisions the SM lagrangian with a set of higher integrated luminosity of 36.1 fb–1, re-inter- ATLAS has last for a period of several milliseconds asteroid belts or FRBs being messages of the number of detected FRBs, and an either through direct production or via dimensional operators encoding the prets the result of recent ATLAS searches and have a relatively broad spectrum from extraterrestrials. exponential decrease in the number of m o d i fic a t i o n s o f e l e c t r o w e a k o b s e r v a bl es different couplings between DE and SM become for stop quarks and dark matter produced where the radio waves with the highest For one particular FRB, however, its theories on their origin. induced by virtual DE particles. particles. These operators are suppressed the first in association with jets. No significant f r e q u e n c i e s a r r i v e fi r s t fol l o w e d b y t h o se location was precisely measured and Last year, the ATLAS collaboration at by a characteristic energy scale, and the experiment excess over the predicted background with lower frequencies. This dispersion found to coincide with a faint unknown Further reading t h e L HC c a r r i e d o ut a fi r s t c ol l i d e r s e a r ch goal of experiments is to pinpoint this to probe all was observed, setting the most stringent feature is characteristic of radio waves radio source within a dwarf galaxy. This CHIME/FRB Collaboration 2019 Nature for light scalar particles that could con- energy for the different DE–SM cou- forms of constraints on the suppression scale of travelling through a plasma in which shows clearly that the FRB was extra- doi:10.1038/s41586-018-0867-7. tribute to the accelerating expansion of plings. Two representative operators conformal and disformal couplings of free electrons delay lower frequencies galactic. The reason this FRB could be CHIME/FRB Collaboration 2019 Nature matter in the the universe. The results demonstrate predict that DE couples preferentially to DE to normal matter in the context of an more than the higher ones. Measuring localised is that it was one of several to doi:10.1038/s41586-018-0864-x the ability of collider experiments to either very massive particles like the top observable effective field theory of DE. The results the amount of dispersion thus gives an come from the same source, allowing E F Keane 2018 Nat. Astron. 2 865. s access new regions of parameter space quark (“conformal” coupling) or to final universe show that the characteristic energy indication of the number of free electrons more detailed studies and long-term D Lorimer 2018 Nat. Astron. 2 860.

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a trillionth of a second (10 s) and decays Δφ 18 99m 11 13 15 σ F, Tc, C, N, O, d long before it can form hadrons. It is also d|

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64 67 124 103 σ 1 Cu, Ga, I, Pd the only quark that provides the possi- σ 0.50 0.3 bility to study a bare quark. This allows physicists to explore its spin, which is 123 111 68 68 0.45 Best 20u/25 20, 25–15 Best 15 + I, In, Ge/ Ga related to the quark’s intrinsic quantum 0.2 stat stat syst angular momentum. The spin of the top 1.05 stat stat syst 1.05 quark can be inferred from the particles 1.00 data Best 30u data 1.00 theory 30 Best 15 + 123I, 111In, 68Ge/68Ga it decays into: a bottom quark and a W theory 0.95 (Upgradeable) boson, which subsequently decays into 0.95 leptons or quarks. 0 /3 /2 Greater production of –1.0 –0.5 0 0.5 1.0 π/6 π π 2π/3 5π/6 π The CMS collaboration has analysed k |Δφ | cosθ1 II Installation of Best 70 MeV Best 35 35–15 Best 15, 20u/25 isotopes proton–proton collisions in which pairs plus 201Tl, 81Rb/81Kr of top quarks and antiquarks are pro- Fig. 1. The unfolded distribution of the lepton angle with respect to the momentum of the top quark (left) as well Cyclotron at Italian National duced. The Standard Model (SM) makes as the azimuthal opening angle between two leptons (right). Good agreement with the NLO predictions is 82Sr/82Rb, 123I, 67Cu, precise predictions for the frequency at observed, as indicated by the dashed blue line. Laboratories (INFN), Legnaro, IT Best 70 70–35 81Kr + research which the spin of the top quark is aligned with (or correlated to) the spin of the top sensitive to the top-quark polarisation A moderate similar results agree with the data antiquark. A measure of this correlation were measured. The measured observ- discrepancy is within the uncertainties. is thus a highly sensitive test of the SM. ables were corrected for experimental seen in In summary, a good agreement with Proton-to-Carbon High Energy If, for example, an exotic heavier Higgs effects (“unfolded”) and directly com- the SM prediction is observed in CMS one of the Particle Delivery System: boson were to exist in addition to the one pared to precise theoretical predictions. data, except for the case of one par- discovered in 2012 at the LHC, it could The observables studied in this analy- measured ticular but commonly used observable, Intrinsically small beams facilitating decay into a pair of top quarks and anti- sis show good agreement between data distributions suggesting further input from theory quarks and change their spin correlation and theory, for example showing no calculations is probably necessary. The beam delivery with precision significantly. A high-precision meas- angular dependence for unpolarised top full Run-2 data set already recorded by urement of the spin correlation there- quarks (see figure 1, left). A moderate CMS contains four times more top quarks Small beam sizes – small magnets, fore opens a window to explore physics discrepancy is seen in one of the meas- than were used for this result. This larger beyond our current knowledge. ured distributions sensitive to spin (the sample will allow an even more precise light gantries – smaller footprint The CMS collaboration studied more azimuthal opening angle between two measurement, increasing the chances for than one million top-quark–antiquark leptons), with respect to one of the Monte a first glimpse of new physics. Highly efficient single turn extraction p a i r s i n d i l e p t o n fi n a l s t a t e s r e c or d e d in Carlo simulations (POWHEGv2+PYTHIA). 2016. To study all the spin and polari- This discrepancy is consistent with an Further reading Efficient extraction – less shielding sation effects accessible in top-quark– observation made by the ATLAS collab- CMS Collaboration 2018 CMS-PAS-TOP- antiquark pair production, nine event oration last year, although CMS finds 18 006. Flexibility – protons and/or carbon, quantities sensitive to top-quark spin that other simulations (“MG5_aMC@ ATLAS Collaboration 2018 ATLAS-CONF- future beam delivery modalities and correlations, and three quantities NLO”) and calculations that should give 2018-027. ALICE ion Rapid Cycling New measurements shine a light on the proton Medical Synchrotron The electromagnetic field of the highly the gluon density in the proton. Previous Recently, the ALICE collaboration has (iRCMS) charged lead ions in the LHC beams pro- measurements by ALICE have shown that performed a measurement of exclusive v i d e s a v e r y i nt e n s e flu x o f h i g h- e n e r gy this process could be measured in a wide photoproduction of J/ψ m e s o n s o ff pr o t o n s quasi-real photons that can be used to range of centre-of-mass energies of the in proton–lead collisions at a centre-of-

probe the structure of the proton in photon–proton system (Wγp), enlarging mass energy of 5.02 TeV at the LHC using lead–proton collisions. The exclusive the kinematic reach by more than a factor two new configurations. In both cases, photoproduction of a J/ψ vector meson of two with respect to that of calculations the J/ψ meson is reconstructed from its s TeamBest Companies © 2017–2018 Specifications shown are subject to change. is of special interest because it samples performed at the former HERA collider. d e c a y i nt o a l e p t o n p a i r. I n t h e fi r s t c a s e,

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the leptons are measured at mid-rapidity –2 –3 –4 –5 the validity of DGLAP evolution (JMRT), masses, mixing angles and vacuum Fig. 2. Exclusion 10 10 10 10 Γ/m > 20% miss ATLAS preliminary a ET + Z(II) using ALICE’s central-barrel detectors. 3 the vector-dominance model (STARlight), expectation values. For the 2HDM with regions in the 1800 10 √s = 13 TeV, 36.1 fb–1 2HDM + a, Dirac DM The excellent particle-identification ALICE n e x t-t o -l e a d i n g ord e r BF K L , t h e c ol o u r– an additional vector mediator, the result- pseudoscalar Higgs ALICE (PRL 113 (2014) 232504) limits at 95% CL mχ = 10 GeV, gχ = 1 capabilities of these detectors allow the power-law fit to ALICE data g l a s s c o n d e n s a t e (CG C), a n d t h e i n c lu s i o n ing exclusion limits are further improved versus mediator observed sin = 0.35, tan = 1 miss – expected H1 miss ET + h(bb) + – + – 1400 mA = mH = mH± measurement of both the e e and μ μ ZEUS of fluctuating sub-nucleonic degrees- by combining the ET + Higgs analyses mass plane for channels. The second configuration LHCb pp (W+ solutions) of-freedom (CCT). The last two models where the Higgs boson decays to a pair an extended LHCb pp (W– solutions) miss

combines a muon measured with the 2 include the phenomenon of saturation, of photons or b-quarks. For the dark- two-Higgs doublet [GeV]

10 CCTCCT A 1000 ET + h(γγ)

central-barrel detectors with a second JMRTJMRT NLO NLO where nonlinear effects reduce the gluon energy models, two operators at the low- model. m STARLIGHTSTARLIGHT param. param. muon measured by the muon spectrom- ( γ + p → J/ Ψ p) (nb) NLONLO BFKL BFKL density in the proton at small x. e s t orde r e ffe c t ive L a g r a ng i a n a l low for σ m = 600 GeV eter located at forward rapidity. By this CGCCGC (ip-Sat, (IP-Sat, b-CGC) b-CGC) The new measurements are compatible interactions between SM particles and 600 A miss – = mh ET + Z(qq) mA = ma clever use of t he detector config uration, with previous HERA data where availa- the new scalar particles. These operators = m mA a we were able to significantly extend the bl e, a n d a l l m o d e l s a g r e e r e a s o n a bl y w e l l are proportional to the mass or momenta 1.2 200 coverage of the J/ψ measurement. with the data. Nonetheless, it is seen that of the SM particles, making them most h(inv) 1.0 miss 100 150 200 250 300 350 400 The energy of the photon–proton col- at the largest energies, or equivalently sensitive to the ET + top–antitop or the miss ma [GeV] l i s i o n s, W γp, i s d e t e r m i n e d b y t h e r a pid it y 0.8 the smallest x, some of t he models pre- ET + jet final states. (which is a function of the polar angle) dict a slower growth of the cross sec- To d ate, no s i g n i fic a nt e xc e s s o ve r t he 0.6 of the produced J/ψ with respect to the models/fit to data tion with energy. This is being studied SM backgrounds has been observed in versus the mediator masses, highlighting f u l l d a t a s e t o f L HC c ol l i s i o n s c ol l e c t e d b y 20 30 40 50 60 102 2 × 102 103 beam axis. Since the direction of the proton by ALICE with data taken in 2016 in p–Pb any of the ATLAS searches for dark matter t h e c o m pl e m e nt a r it y o f d i ffe r e nt c h a n n e l s ATLAS during Run 2, the sensitivity to Wγp (GeV) and the lead beams was inverted halfway collisions at a centre-of-mass energy of or dark energy. Limits on the simplified i n d i ffe r e nt r e g io n s o f t h e p a r a m e t e r s pace these models will continue to improve. through the data-taking period, ALICE Fig. 1. Exclusive J/ photoproduction off protons in proton–lead 8.16 TeV, allowing exploration of the W models are set on the mediator-versus- (figure 2). Finally, collider limits on the ψ γp The sensitivity covers both backward and forward rapid- collisions at a centre-of-mass energy of 5.02 TeV, compared with energy range up to 1.5 TeV, potentially dark-matter masses (figure 1), which can s c a l a r d a r k e n e r g y m o d e l (s e e p1 2) a r e a l s o Further reading to these ities using a single-arm spectrometer. previous measurements and model predictions. shedding new light on the question of also be compared to those obtained by set and for the models studied improve ATLAS Collaboration ATLAS-CONF- T h e s e t w o c o n fi g u r a t i o n s, plu s t h e o ne gluon saturation. direct detection experiments. For the models will over the limits obtained from astronom- 2018-051. used previously where both muons were momentum, x, a n d t h e n e w m e a s u r e m e nt s 2HDM with a pseudoscalar mediator, lim- continue to ical observation and lab measurements ATLAS Collaboration 2018 ATL-PHYS- measured in the muon spectrometer, extend over three orders of magnitude Further reading its are placed on the heavy pseudoscalar improve by several orders of magnitude. With the PUB 2018-008. allow ALICE to cover – in a continuous way in x from 2 × 10–2 to 2 × 10–5. The measured S Klein and J Nystrand 2017 Physics Today

– t h e r a n g e i n W γp from 20 to 700 GeV. The cross section for this process as a function 70 40. LHCb

typical momentum at which the struc- of W γp is show n in fig ure 1 and compared ALICE Collaboration 2014 Phys. Rev. Lett. ture of the proton is probed is conven- with previous measurements and models 113 232504. Rea l-t ime t riggering boosts heav y-flavour prog ramme tionally given as a fraction of the beam based on different assumptions such as ALICE Collaboration 2018 arXiv 1809.03235. Throughout LHC Run 2, LHCb has been ATLAS flooded by b- and c-hadrons due to the 7 large beauty and charm production 10 LHCb √s = 13 TeV prompt-like sample 6 p (μ) > 1 GeV, p(μ) > 20 GeV Report summarises dark-sector exploration cross-sections within the experiment’s )]/2 10 T

acceptance. To cope with this abundant μμ μ+μ– 105 In our current understanding of the tially even leptons. For certain model flu x o f s i g n a l p a r t i c l e s a n d t o f u l l y e xploit [m( ± ±

1.6 σ μ μ energy content of the universe, there parameters, these direct searches can them for LHCb’s precision flavour- 4 ATLAS preliminary 10 are two major unknowns: the nature of be more sensitive than the X + Emiss ones. physics programme, the collaboration 1.4 T 103 a non-luminous component of matter dijet However, simplified models are not has recently implemented a unique 2

1.2 candidates/ (dark matter) and the origin of the accel- – full theories like, for example, super- real-time analysis strategy to select 10 Zʹ v = m tt erating expansion of the universe (dark symmetry. Recent theoretical work has a n d c l a s s i f y, w it h h i g h e ffic i e n c y, a l a r g e χ resonance 1.0 2 × m energy). Both are supported by astro- dibjet therefore focused on developing more number of b- and c-hadron decays. Key 3 4 5 physical and cosmological measurements 2 = 0.12 c o m pl e t e, r e n or m a l i s a bl e m o d e l s o f d a r k components of this strategy are a real- 10 10 10 tt resonance h 0.8 Ω c [TeV] but their nature remains unknown. This χ dijet m a t t e r, s u c h a s t w o -H i g g s d o u bl e t m o d- time alignment and calibration of the m(μμ) [meV] m has motivated a myriad of theoretical 0.6 thermal relic els (2HDM) with an additional mediator detector, allowing offline-quality event models, most of which assume dark mat- dibjet particle. These models introduce a larger reconstruction within the software trig- 0.4 miss ter to be a weakly interacting massive ET + X nu m b e r o f f r e e p a r a m e t e r s, a l l o w i n g for ger, which runs on a dedicated comput- size reduction as the handle to reduce Fig. 1. The mass by a factor of five, these new techniques miss particle (WIMP). E + X vector mediator, Dirac DM a richer phenomenology. ing farm. In addition, the collaboration trigger bandwidth. This is particularly spectrum of muon w i l l b e c o m e s t a n d a r d. L HC b e x p e c t s t h a t 0.2 T WIMPs may be produced in high- gq = 0.25, gI = 0, gχ = 1 Similarly, for dark energy, effective took the novel step of only saving to tape true for the large charm trigger rate, pairs arising from a more than 70% of the physics programme all limits at 95% CL energ y proton collisions at t he LHC, and 0 field theory implementations may intro- interesting physics objects (for example, where saving the full raw events would common vertex, will use the reduced event format. The full are therefore intensively searched for by 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 duce a stable and non-interacting scalar t r a c k s, v e r t i c e s a n d e n e r g y d e p o s it s), a n d result in a prohibitively high bandwidth. obtained directly software trigger, combined with real-time the LHC experiments. Since dark matter m [TeV] field that universally couples to matter. discarding the rest of the event. Dubbed Saving only the physics objects entering from the real-time alignment and calibration, along with the Z´v miss is not expected to interact with the detec- This also leads to a characteristic ET “selective persistence”, this substan- the trigger decision reduces the event analysis trigger. s e l e c t i v e p e r s i s t e n c e pi o n e e r e d b y L HC b, tors, its production leaves a sig nature of Fig. 1. The regions in the mediator versus dark-matter mass signature at the LHC. tially reduced the average event size size by a factor up to 20, allowing larger No further offline will likely become the standard for very miss miss missing transverse momentum (ET ). It plane excluded at 95% CL by dijet, di-b-jet, top and E T + X ATLAS has recently released a sum- written from the online system without statistics to be collected at constant processing was high-luminosity experiments. The col- can be detected if the dark-matter par- searches for vector-mediator simplified models. mary gathering the results from more any loss in physics performance, thus bandwidth. Several measurements of applied. laboration is therefore working hard to ticles recoil against a visible particle X, than 20 experimental searches for dark permitting a higher trigger rate within charm production and decay properties implement these new techniques and which could be a quark or gluon, a pho- spin-1 mediator particles that propagate matter and a first collider search for t he s a me out put dat a r ate (ba nd w idt h). have been made so far using only this ensure that the current quality of physics ton, or a W, Z or Higgs boson. These are the interaction between the visible and the dark energy. The wide range of analy- This has allowed the LHCb collaboration information. The sets of physics objects d a t a c a n b e e q u a l l e d or s u r p a s s e d i n R u n 3. miss commonly known as X + ET signatures. dark sectors. Because the mediators must s e s g i v e s g o o d c o v e r a g e for t h e d i ffe r e nt to maintain, and even expand, its broad that must be saved for offline analysis To interpret these searches, a variety of couple to Standard Model (SM) particles dark-matter models studied. For new programme throughout Run 2, despite can also be chosen “à la carte”, opening Further reading simplified models are used that describe in order to be produced in the proton– models, such as 2HDM with an additional limited computing resources. the door for further bandwidth savings R Aaij et al. 2018 arXiv:1812.10790. dark-matter production kinematics with pr o t o n c ol l i s i o n s, t h e m e d i a t or s c a n a l s o pseudoscalar mediator, multiple regions The two-stage LHCb software trigger on inclusive analyses too. R Aaij et al. 2016 Comput. Phys. Commun. a minimal number of free parameters. be directly searched for through their of the parameter space are explored is able to select heavy flavoured had- For the LHCb upgrade (see p34), when 208 35. s These models introduce new spin-0 or decays to jets, top-quark pairs and poten- to probe the interplay between the rons with high purity, leaving event- the instantaneous luminosity increases A Pearce 2016 PoS (LHCP2018) 226.

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As the so-called science plots of confidence limits, in reducing “particle physics at the crossroads”, and physics at the wars of the 1990s showed, it requires Wuppertal summer school the complexity of the underlying data and found that the metaphor of a jungle, in crossroads” an open mind on all sides to facilitate establishing the existence of elementary which not even paths are clearly laid out, a fruitful discussion between the natu- Interdisciplinary perspectives on particle physics particles such as the Higgs boson. might be apt to characterise the current ral sciences, the social sciences and the This programme was complemented situation. One may feel reminded here of humanities. The future of particle physics On 23–30 July 2018, physicists joined Jarych S by three inside views from physics. John the situation in the 1960s where a “zoo” may be uncertain, but collaborative efforts forces with researchers from the human- Ellis from King’s College London and of particles was discovered without any such as the Wuppertal summer school will ities to address historical, philosophical CERN offered his view on future the- hint, at least at first, of what t heoret ical certainly contribute to a better assess- and sociological aspects of particle phys- oretical developments; former CERN structures underpinned them. However, ment of the aims and relevance of this ics in Wuppertal, Germany. The event, the Director-General Rolf-Dieter Heuer pro- the current situation is rather different branch of fundamental physics research. third in a series of spring and summer vided insights into the factors driving because it is precisely such hopes for schools, was organised by the research particle-physics research; and ATLAS discovering particles beyond the current Florian Boge RWTH Aachen University/ unit The Epistemology of the Large Had- member Christian Zeitnitz from Wup- theory that have been dashed by the LHC IZWT Wuppertal and Adrian Wüthrich ron Collider (ELHC), and was funded by pertal University, as well as Margarete so far. Technical University Berlin. the German Research Foundation and the H Hiramoto Austrian Science Fund, with additional DIS2018 support by the University of Wuppertal. ELHC is an international collaboration The future of deep- between physicists, philosophers, his- torians and sociologists that aims for inelastic scattering a comprehensive understanding of the goals and methods of LHC research. The The most recent edition of the Inter- unit has been active for approximately national Workshop on Deep Inelastic two years and follows the lead of three Scattering and Related Subjects (DIS2018) earlier projects at Wuppertal conducted was held in Kobe, Japan, on 16–20 April between 2009 and 2015. 2018. The event continued in the style of Discussions focussed on the theme a workshop, with almost 250 talks pre- All things hadron spin structure of quarks and gluons inside Given these developments, the 2018 “Particle physics at the crossroads”: with Bridging cultures Steinle argued that Newton’s embedding and using constraints to rule out some senting new results on all things hadron Participants of the nucleons and nuclei, but also, thanks to DIS workshop comprised experimental no evidence of physics beyond the Stand- Physicists and of a vis motrix (“moving force”) into a classes of theories. Giving an example, he physics: spin and 3D structure, struc- DIS workshop its very high luminosity, high-precision and theory talks covering results from ard Model from the LHC, where is particle humanities scholars rich conceptual structure contributed explained that perturbative expansions ture functions and parton densities, and covered a vast range probes of partons that carry a high-mo- various energy regimes, as well as review physics headed? While these challenges join forces in to the success of Newtonian mechanics, around Minkowski space–time can be quantum chromodynamics (QCD) studies of physics. mentum fraction of the parent hadron. talks on related subjects such as neu- a r e fi r s t a n d for e m o s t b e i n g a d d r e s s edby Wuppertal. and conjectured that a similarly deep parameterised in such a way that possible for high-sensitivity electroweak, Higgs trino–nuclei scattering, parton frag- physicists, scholars from the humanities conceptual change could open up new a l t e r n a t i v e s t o g e n e r a l r e l a t i v it y a r e fi x e d and beyond-Standard Model measure- Evolution mentation and exotic hadrons, to seek and social sciences can help identify the avenues in particle physics. by the value ranges of these parameters. ments, to name a few. Meanwhile, the proposed Large Had- possible connections between traditional surrounding issues, such as the potential Catherine Westfall, a science historian The vast range of physics covered in DIS ron electron Collider (LHeC) at CERN, DIS studies and new ones. In addition, this i n flu e n c e s f r o m s o c i a l or g a n i s a t io n. T he Hot debate from Michigan State University, drew on workshops cannot be easily integrated bringing proton beams from the LHC year’s event featured a special discussion talks at this year’s summer school were Rafaela Hillerbrand, a philosopher from the history of Fermilab during the 1960s into a single theoretical framework, and into collision with electrons acceler- session on future strategies for DIS stud- all exemplars of how work in the human- Karlsruhe Institute of Technology, turned and 1970s to highlight decision-making in t h e r e a r e s l i g ht l y d i ffe r e nt v ie w s o n h ad- ated up to 60 GeV through a dedicated ies and related subjects, following pres- ities and social sciences has a bearing on to another tool in LHC research – com- the community. Even though in hindsight ronic interactions depending on the type energy-recovery linac, would provide, entations by experimentalists from EIC, current issues in high-energy physics. puter simulations. She proposed a clas- some of Fermilab’s research strategies and energy of the underlying collisions. in addition to precise measurements in LHeC, VHEeP and FCC-he, and theorists Kent Staley, a philosopher from St. sification of simulations depending on (such as its initial focus on smaller and One view, which applies to high-energy the Higgs sector, more information on working on QCD and heavy-ion physics. Louis University in the US, analysed the whether they provide information on inexpensive experiments) seem wrong- collisions, is a combination of fast-mov- hadron structure through electron–pro- The responses of the participants were statistical reasoning involved in LHC abstract, laboratory or real-world sys- headed, she explained, the expectation of ing partons with little transverse momen- ton and electron–ion collisions in regions positive, noting the importance and com- research, arguing that pragmatic con- tems, and discussed whether they should fi nd i n g ne w p he nome n a at h i g he r e ne r- tum and a large amount of radiation in of very low Bjorken-x and very high Q2. plementarity of the projects. The outcome siderations can explain why the practice be seen as a theoretical or an experi- g i e s e v e nt u a l l y p a i d o ff, for i n s t a n c e w it h the initial and final states. Another is LHeC would also allow researchers to see, of the discussion has been summarised of high-energy physics relies more on mental activity. This latter issue is hotly the discovery of the bottom quark. the parton and spin dynamics in had- through the behaviour of total and dif- in a document that was submitted to the frequentist statistical methods than on debated among philosophers, and LHC Anne Dippel from Jena University in rons and nuclei viewed “in 3D”, where fractive cross sections in the high-energy update of the European Strategy for Par- Bayesian ones. As an example, he con- experiments, which rely on complex sim- Germany offered an anthropologist’s the transverse momentum and collective limit, if there is any saturation in the particle Physics. templated what the repercussions of erro- ulations, have attracted their attention. perspective on the practice of particle motions of partons play an important role ton evolution inside nucleons and nuclei. The event also featured the award cer- neous claims to the discovery of a Higgs Philosopher Chris Smeenk from West- physics. She emphasised that fierce com- in describing hadron behaviour. Further down the line, the Future Circular emony for the 2018 Guido Altarelli Award boson would have been for the commu- ern University in Canada discussed a petition, which is conducive to knowledge Traditionally, these two views are dis- Collider hadron–electron (FCC-he) pro- (CERN Courier July/August 2018 p36), which nity, and argued that frequentist methods Bringing central topic in the philosophy of sci- production at institutes such as CERN, cussed separately at DIS meetings, but the ject at CERN, as well the proposed very- recognised the work of early-career sci- are better suited to avoid such claims. together ence: how can we ever claim even the manifests itself in many playful and even situation is gradually changing owing to high-energy electron–proton (VHEeP) entists Jun Gao, on precision QCD theory, Friedrich Steinle, a historian of sci- philosophy, approximate truth of a theory when humorous elements in the daily work of projects for new lepton–hadron colliders. collider with a 3 TeV electron beam accel- a nd Or Hen, on t he “E MC effec t” a nd t he ence from the Technical University history, the history of science shows that there researchers, such as the animal shelter The proposed Electron Ion Collider (EIC) erated by a proton-driven wakefield, also valence down- and up-quark ratio. Berlin, provided case studies of New- were often alternative theories that had for computer mice on the CERN cam- at the Brookhaven National Laboratory or at CERN, could probe hadron structure The next DIS workshop will take place sociology ton and Faraday that demonstrated the also been well confirmed empirically? pus. She also highlighted the creative Jefferson Lab in the US, at centre-of-mass in the high-energy limit too. These pro- in Turin, Italy, from 8 to 12 April 2019. fundamental role of concepts in physics, and particle Smeenk explored the extent to which potential of unforeseen incidents such energies of about 100 GeV (CERN Courier jects are intimately related, and call for both in opening new vistas and provid- physics this problem can be tamed by parame- as the incident at the LHC in September October 2018 p31), would offer not only a a unified discussion of hadron physics Yuji Yamazaki Kobe University and chair s ing long-term boundaries. For instance, proved fruitful terising the space of alternative theories 2008 that temporarily forced the detailed tomographic view of the space and across collision energies. of the DIS2018 organising committee.

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FIELD NOTES FIELD NOTES

rUpAC2018 theory uncertainties, particularly those urements of these states in a variety of Fresh results vertex as a signature was proposed for affecting predictions for B → D*ℓν decays. collision systems will shed light on the using data identifying this and other hadrons with Finally, the implications of the present low-x QCD regime, on nuclear structure two bottom quarks. Russian accelerator science in focus from LHC anomalies were discussed from a mod- and on the as-yet-unresolved puzzle of Fresh results using data from LHC Run The 26th Russian Particle Accelerator KI–IHEP NRC el-building point of view, with special quarkonium production itself. Finally, Run 2 were 2 were served up in all four streams, but Conference, RUPAC2018, was convened emphasis on models including lepto- progress on CODEX-b, a proposed addi- served up, there was a strong appetite for more. Key on 1–5 October 2018 in Protvino, Rus- quarks, which could explain several of tional detector to search for long-lived but there questions remain on the nature of the sia, at the Institute for High Energy the current anomalies at once. particles at LHCb, was presented: the was a strong l e p t o n fl a v o u r a n o m a l ie s a n d o n w h e ther Physics of the National Research bac kg round flu x in t he caver n has been appetite they will persist or fade as more data Centre “Kurchatov Institute” (NRC Unique potential measured, and simulation studies of are added (CERN Courier April 2018 p23). for more KI–IHEP). This year the traditional The third stream of the workshop cov- potential backgrounds were shown. Crucial questions also remain about the biennial conference, which started ered the active experimental programme The fourth physics stream was devoted origin of the large local CP violation seen in 1968, gathered some 170 partic- spanning electroweak physics, exotica, to QCD spectroscopy. LHCb reported in multibody decays, the nature of exotic ipants from accelerator centres in heavy flavour, heavy ions and central discoveries of several new baryons with hadrons, and more. By the next workshop Russia, Germany, Italy, Sweden, Romania, exclusive production. In the related the- h e a v y fl a v o u r, a n d t h e or y t a l k s d i s c u s sed we will hopefully have some answers – Canada and China to discuss the latest ory talks, the unique potential of LHCb’s the impressive success of a semi-empiri- and perhaps a few more questions. Prepa- developments and results in accelerator forward acceptance to pin down the pro- cal approach to predict their masses. There rations for the Run 3 physics programme science and engineering. The conference ton parton distribution functions in the were also new results from LHCb on exotic will also be in full swing, ready for the was organised bу the Budker Institute of unconstrained QCD regimes of low and hadrons – those that defy interpretation big boost in statistics that will come from Nuclear Physics (BINP), the Joint Insti- high longitudinal momentum fraction as conventional mesons or baryons – and a complete overhaul of the detector and tute for Nuclear Research (JINR), and the (x) was discussed, as were a variety of predictions from theory for related future its readout system during the next two NRC KI–IHEP under the auspices of the models with the distinctive signature of d i s c o v e r ie s. S e v e r a l d i ffe r e nt q u a r k m od- years (see p34). LHCb is also planning Russian Academy of Sciences. In step Vladimir The bulk of reports from JINR in and the fourth-generation Specialized displaced heavy neutral lepton decays els as well as lattice QCD agree in predict- further upgrades, and the prospects for The 54 oral talks and 135 poster Petrov from the Dubna were devoted to progress in the Synchrotron Radiation Source-4. that could explain neutrino oscillations ing a stable tetraquark with two bottom what we might learn with much more contributions featured both national and Institute for High Nuclotron-based Ion Collider Facility It was fitting that the conference and non-zero neutrino masses. Pres- quarks and two light antiquarks. Experi- data – a factor 30 more than today – will international accelerator facilities, but Energy Physics, (NICA) project at the nuclotron facility. was held in a year of a few round-figure entations also focused on the full mul- mental prospects for its discovery with the surely be a hot topic. attention was directed at Russia’s domes- Protvino, speaking Significant progress was also reported anniversaries for the Russian accelerator titude of charmonia (cc– states) accessible upgraded LHCb detector were discussed,

tic machines. BINP in Novosibirsk pre- at RUPAC2018. for the heavy-ion cyclotrons of the JINR’s community: 75 years of the Kurchatov to LHCb beyond the J/ψ, from the ηc to and a new experimental method using Mat Charles on behalf of the LHCb + sented status reports on the VEPP-2000 Flerov Laboratory of Nuclear Reactions Institute (Moscow); 60 years of BINP exotic X, Y and Z states. Future meas- Bc mesons not originating at a primary collaboration and theory contributors. and VEPP-4M electron–positron collid- (FLNR). The status of, and plans for, the (Novosibirsk) and 100 years of its founder ers, the operation of which has improved other operational domestic machines – a n d fi r s t d i r e c t or G e r s h B u d k e r; 55 y ears CERN–South AfRiCA noticeably after the commissioning of a the high-intensity proton linear accel- o f I H E P (P r o t v i n o); a n d 50 y e a r s s i n c e t h e new positron injection chain. Talks from erator at INR (Troitsk), the synchrotron fi r s t n a t i o n a l p a r t i c l e a c c e l e r a t or c onfer- South Africa marks 10 years of CERN collaboration NRC KI–IHEP in Protvino reviewed the radiation (SR) source KSSR-2 at NRC KI ence, the forerunner of the RUPAC series, U70 proton synchrotron, which is now (Moscow) and the 1 GeV synchrocyclo- was convened. The next meeting will be An event commemorating the 10th Strengthening S Mouton operated for 50–60 GeV fixed-target tron SC-1000 at NRC KI–PNPI (Gatchina) held in the autumn of 2020. anniversary of the CERN–South Africa connections experimental physics, proton radiog- – were also presented. Due attention was programme took place at iThemba Lab- Sibaliso Mhlanga raphy studies and applied radiobiology also given to two new SR projects: the Sergey Ivanov chair of the RUPAC2018 oratory for Accelerator-Based Sciences (right) of iThemba research using carbon–nuclei beams. Siberian Circular Photon Source (SKIF) organising committee. (iThemba LABS) in Cape Town from 19 LABS talking to 21 November 2018, highlighting the heavy-ion physics LHCb worksHop consider what will be possible with The workshop remain puzzling, and the community is importance of South African involve- with CERN director LHCb’s planned upgrades. The work- was a welcome eagerly waiting for experimental updates. ment in CERN and opportunities to for international Community talks shop was capped by a theory keynote talk The description of the final-state inter- further strengthen the partnership. The relations Charlotte opportunity heavy-flavour by Antonio Pich from Valencia, which actions in these decays is important but event was packed out, with the French Warakaulle during a addressed current tensions between the to consider theoretically challenging. Many new, and Swiss ambassadors to South Africa, poster session. physics and more Standard Model (SM) and recent results what will promising theoretical approaches, such the vice-chancellors of the universities in flavour physics. be possible as the use of triangle diagrams to describe of Cape Town and the Witwatersrand, The physics content of the workshop with LHCb’s the interactions, were discussed. internationally renowned physicists from On 17–19 October 2018, physicists from was divided into four streams. The planned In the second stream, semileptonic CERN and South Africa, and many young the LHCb collaboration and the theory first was on mixing and CP violation decays, rare decays and tests of lepton students from South Africa and from upgrades community gathered at CERN to discuss in beauty and charm hadrons, looking flavour universalit y were covered. Dis- other parts of Africa attending. The event the implications of LHCb’s results and at non-leptonic decays. A major focus cussions triggered by the tantalising also included impressive exhibitions and prospects for future studies. This was the was on extracting the γ parameter of hints of lepton-flavour-universality presentations from local industry. radio-telescope project, which South Higgs boson in 2012. In return, the CERN– eighth in a series of workshops that has the Cabibbo–Kobayashi–Maskawa violation seen in tree-level and loop- In terms of the number of participating Africa will host jointly with Australia and South Africa partnership has helped to 0 become an annual tradition, attracting quark-mixing matrix and the B and suppressed decays – RK and RK*, R(D) and scientists and engineers, South Africa is which will require a massive computing strengthen nuclear and particle physics 0 * more than 200 physicists from all over Bs mixing angles, with experimental R(D ), and the kinematic and angular CERN’s most important partner on the infrastructure similar to the worldwide e ffor t s i n S o ut h A f r ic a. It h a s a l s o a celr- 0 + – the world, plus more participants con- updates presented. Measurements of Bs distributions of b → s μ μ decays – African continent. Researchers from LHC computing grid. In fact, the SKA ated technology development, enhancing nected remotely by video link. mixing play an especially important role were the highlight of this stream. After several universities participate in the organisation signed an agreement with both technological and social innovation LHCb is at the forefront of heavy- in constraining physics beyond the SM, reviewing LHCb’s experimental results, ALICE and ATLAS experiments as well CERN in 2017 to address the challenges a n d pr o v i d i n g a d v a n c e d s c i e nt i fic t r a i n i n g flavour physics research – as well as and improved inputs from lattice quan- theory talks presented overviews of as in ISOLDE, and are also visitors to of such “exascale” computing and data for the next generation of South African being active in heavy-ion and forward- tum chromodynamics (QCD) calculations the status of SM calculations based on CERN’s theoretical physics department. storage (CERN Courier September 2017 p9). scientists and engineers. It is expected electroweak physics – and the workshop are crucial to this endeavour. Part of the approaches such as non-perturbative lat- The South African particle-physics com- The LHC has brought many opportuni- and hoped that this valuable crossover of was a welcome opportunity to discuss session was dedicated to the decays of tice QCD simulations or QCD sum rules. munity continues to grow and is expected ties for South Africa’s science community, skills will continue long into the future. the latest developments, including some B mesons to multibody final states; the Further new ideas were presented to to benefit from important synergies including contributions to major break- s that were shown for the first time, and to large CP asymmetries seen in these decays improve SM predictions and address with the Square Kilometre Array (SKA) throughs such as the discovery of the Emmanuel Tsesmelis CERN.

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ISOLDE wOrkShOp

Users highlight successful campaigns Forging ahead K Johnston On 5–7 December 2018, the annual had been irradiated earlier. The first HIE- The TOTEM and CMS ISOLDE Workshop and Users meeting ISOLDE physics paper, accepted for publi- experiments’ took place at CERN, attracting 153 par- cation in Physical Review Letters, was also Roman-pot detectors ticipants. The programme consisted of 41 highlighted. It provides the first direct in the LHC tunnel. presentations, of which 22 were invited proof that the very neutron-rich tin-132 talks and 19 were oral contributions nucleus, considered to be doubly magic, selected from 74 submitted abstracts. does indeed merit this special status. ISOLDE, CERN’s long-running nuclear Other sessions were dedicated to the research facility, directs a high-intensity rich low-energy experimental physics proton beam from the Proton Synchro- programme at ISOLDE. Overview talks tron Booster (PSB) at a target station to were presented on recent achievements produce a range of isotopes. Different in high-precision mass studies, with devices are used to extract, ionise and beam lines. A total of 17 different RIBs Prize winners indium-100 as a highlight; on collinear separate the isotopes according to their were accelerated during July–November The workshop laser spectroscopy studies, with a long mass, forming low-energy beams that 2018. Beams of isotopes with an atomic organiser Gerda series of antimony isotopes and isomers; are delivered to various experiments. mass from 7 to 228, with the radium-228 Neyens (second on decay-spectroscopy experiments; and These radioactive ion beams (RIBs) can beam being the heaviest ever acceler- from right) with on the solid-state physics programmes. also be re-accelerated using the REX/ ated beam at ISOLDE, were delivered. Victoria Participants also heard about recent HIE-ISOLDE linear accelerators (linacs). The HIE-ISOLDE campaign began with Araujo-Escalona studies with antiprotons at the Antipro- An energy upgrade of the HIE-ISOLDE seven experiments at the first beam line, and Natalia ton Decelerator at CERN and about the superconducting linac was completed with the MINIBALL detector array and Sokolowska (two extremely exotic isotopes produced at the this year, enabling RIBs with an energy its ancillary detectors. In October two most left), who won Radioactive Isotope Beam Factory (RIBF) up to about 10 MeV per nucleon. experiments used the new ISOLDE sole- for the best poster, facility at RIKEN in Japan. The study of A focus of the 2018 ISOLDE workshop noid spectrometer at the second beam line and Tiago De Lemos exotic isotopes using the VAMOS spec- concerned plans for upgrades and consoli- for the first time, with an inner detector Lima and Lisa trometer at the French GANIL laboratory dation works during the second long shut- lent from Argonne National Laboratory. Morrison (left and was discussed, as were new beam-pro- down of CERN’s accelerator complex (LS2), For these, the full accelerator capacity was right of Neyens), duction facilities at the Selective Produc- including replacing 10-year-old equipment used for t he first t i me. At t he t h i rd bea m who won for best tion of Exotic Species (SPES) facility at and adding more beam-monitoring sys- line, used for “traveling experiments”, young speaker. Legnaro National Laboratory in Italy and tems. Five sessions were devoted to over- three experiments used the scattering the new neutron detector array NEULAND views from ISOLDE users on the outcome of chamber – a large vacuum chamber that at the Facility for Antiprotons and Ions p h y s i c s c a m p a i g n s a t t h e d i ffe r e nt e x p er- can hold several combinations of parti- Research (FAIR) at GSI in Germany. LARGE HADRON imental set-ups, two sessions discussed cle detectors brought by the users; one The meeting ended with the handing progress at other RIB facilities in the world, experiment used an optical time projec- over of four prizes, sponsored by CAEN, and one session focused on applications tion chamber to look for very rare proton for the best talks and posters presented by in life sciences with an emphasis on the decays from the halo nucleus beryllium-11. young researchers (see image). The 2018 COLLIDER CERN MEDICIS programme. The last experiment was performed ISOLDE users meeting was a great suc- The meeting began with an overview in the scattering chamber, after protons cess, highlighting the important research of successful experimental campaigns stopped circulating in CERN’s acceler- being done at this unique facility. at the HIE-ISOLDE RIB accelerator, with ator complex, by extracting long-lived operational set-ups achieved at all three beryllium-7 from an ISOLDE target that Gerda Neyens ISOLDE physics group leader. THE EXPERIMENTS CERN-PHOTO-201811-324-1 CErN-AuStrIA multicultural research environment Silver celebration for such as CERN, participants learn how to collaborate in international networks, are student programme exposed to leading-edge technologies and STRIKE BACK hone their language skills. The Austrian Young researchers from throughout Ambassador, Elisabeth Tichy-Fisslberger, the world came together at CERN on who participated in the celebration, under- 30 November to celebrate the 25th anni- lined that the programme has also helped The LHC lies dormant, its superconducting magnets drained of liquid versary of the CERN–Austrian doctoral strengthen broader links between CERN student programme. Founded in 1993, a n d A u s t r i a, a l l o w i n g s i g n i fic a nt t e c h n ol- helium to be brought back to room temperature. Along with the rest of CERN’s following an agreement between CERN Student success of these were in the fields of accelerator ogy transfer and networking with Austrian and the Austrian Ministry for Science Celebrating the and detector research, with information universities and high-tech industries. accelerator complex, the LHC entered long-shutdown two (LS2) on 10 December. and Research, the programme supports CERN–Austria technology and electronics also featur- The CERN–Austrian PhD programme students from Austrian universities to PhD programme in ing large. Statistics from the programme serves as a model of efficient collabo- The features in this first issue of 2019 bring you all the shutdown pursue their PhD research at CERN in November. show that, in the medium term, one third ration between CERN and its member technology-related fields. of all programme participants return to states, and has inspired similar initia- news from the seven LHC experiments, and what to So far the programme has trained Austria, while much of the rest remain at tives from other countries. expect when the souped-up detectors come back online in 2021. nearly 200 students in the stimulating CERN or work in other European countries. environment offered by CERN. The bulk Working in a cross-disciplinary and Michael Benedikt CERN.

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LARGE HADRON COLLIDER THE EXPERIMENTS STRIKE BACK FEATURE ALICE UPGRADE L Bonechi/LHCf L CERN-PHOTO-201606-135-3

Wired The MoEDAL (Monopole & Exotics Detector at the LHC) Forward physics The LHCf experiment located on either side of ATLAS experiment in the LHCb cavern. simulates cosmic-ray interactions.

uring the next two years of long-shutdown two In terms of rate from future LHC runs. ATLAS and CMS are upgrading (LS2), the LHC and its injectors will be tuned up for radiation numerous aspects of their detectors while at the same time D high-luminosity operations: Linac2 will leave the damage, preparing for major installations during LS3 for HL-LHC floor to Linac4 to enable more intense beams; the Proton one year operations (p28 and 31). At the HL-LHC, one year of colli- Synchrotron Booster will be equipped with completely new of HL-LHC sions is equivalent to 10 years of LHC operations in terms injection and acceleration systems; and the Super Proton collisions is of radiation damage. Even more challenging, HL-LHC will Synchrotron will have new radio-frequency power. The deliver a mean event pileup of up to 200 interactions per equivalent to LHC is also being tested for operation at its design energy of beam crossing – 10 times greater than today – requiring 10 years of LHC 14 TeV, while, in the background, civil-engineering works totally new trigger and other capabilities. operations for the high-luminosity upgrade (HL-LHC), due to enter Three smaller experiments at the LHC are also taking service in 2026, are proceeding apace. advantage of LS2. TOTEM, which comprises two detectors

The past three years of Run 2 at a proton–proton collision located 220 m either side of CMS to measure elastic pro- ALICE-PHO-SKE-2017-002-17 e n e r g y o f 13 TeV h a v e s e e n t h e L HC a c h ie v e r e c ord p e a k a n d ton–proton collisions (see image on previous page), aims integrated luminosities, forcing the detectors to operate to perform total-cross-section measurements at maximal at their limits. Now, the four main experiments ALICE, LHC energies. For this, the collaboration is building a new ATLAS, CMS and LHCb, and the three smaller experiments scintillator detector to be integrated in CMS, in addition to LHCf, MoEDAL and TOTEM, are gearing up for the extreme service work on its silicon-strip and spectrometer detectors. conditions of Run 3 and beyond. Another “forward” experiment called LHCf, made up of two ALICE REVITALISED detectors 140 m e it h e r s id e o f AT L A S, u s e s for w a rd p a r t ic le s At the limits produced by the LHC collisions to improve our knowledge The ALICE experiment is being tuned up to make even more precise Since the beginning of the LHC programme, it was clear about how cosmic-ray showers develop in Earth’s atmos- measurements of the quark–gluon plasma and other extreme nuclear systems. that the original detectors would last for approximately a phere. Currently, the LHCf detectors are being prepared decade due to radiation damage. That time has now come. for 14 TeV proton–proton operations, higher luminosities Improvements, repairs and upgrades have been taking and also for the possibility of colliding protons with light LICE (A Large Ion Collider Experiment) will soon of the universe and is recreated in droplets at the LHC. place in the LHC detectors throughout the past decade, nuclei such as oxygen, requiring a completely renewed have enhanced physics capabilities thanks to a To perform precision measurements of strongly inter- but significant activities will take place during LS2 (and data-acquisition system. Finally, physicists at MoEDAL, a A major upgrade of the detectors, data-taking and acting matter, ALICE must focus on rare probes – such as LS3, beginning 2024), capitalising on technology advances detector deployed around the same intersection region as data-processing systems. These upgrades will improve the h e a v y-fl a v o u r p a r t ic le s, q u a r k o n iu m s t at e s, r e a l a n d v i rtual and the ingenuity of thousands of people over a period of L HC b t o lo o k for m a g n e t ic m o n o p ole s a n d o t h e r s i g n s o f n e w precision on measurements of the high-density, high-tem- photons, and low-mass dileptons – as well as the study of several years. Combined, the technical design reports for physics, are preparing a request to take data during Run 3. perature phase of strongly interacting matter, the quark– jet quenching and exotic nuclear states. Observing rare the LHC experiment upgrades number some 20 volumes For this, among other improvements, a new sub-detector gluon plasma (QGP), together with the exploration of new phenomena requires very large data samples, which is why each containing hundreds of pages. called MAPP will be installed to extend MoEDAL’s physics phenomena in quantum chromodynamics (QCD). Since the THE AUTHORS ALICE is looking forward to the increased luminosity pro- For LHCb, the term “upgrade” hardly does it justice, reach to long-lived and fractionally charged particles. start of the LHC programme, ALICE has been participating Tapan Nayak vided by the LHC in the coming years. The interaction rate of since large sections of the detector are to be completely The seven LHC experiments are also using LS2 to extend in all data runs, with the main emphasis on heavy-ion is ALICE deputy lead ions during the LHC Run 3 is foreseen to reach around replaced and a new trigger system is to be installed (p34). and deepen their analyses of the Run-2 data. Depending on collisions, such as lead–lead, proton–lead, and xenon– spokesperson. 50 kHz, corresponding to an instantaneous luminosity 27 –2 –1 ALICE too is undergoing major interventions to its inner what lies there, the collaborations could have more than xenon collisions. The collaboration has been making major Virginia Greco of 6 × 10 cm s . This will enable ALICE to accumulate detectors during LS2 (p25), and both collaborations are just shiny new detectors on their hands by the time they inroads into the understanding of the dynamics of the is communications 10 times more integrated luminosity (more than 10 nb–1) installing new data centres to deal with the higher data come back online in the spring of 2021.  Q GP – a s t at e o f m at t e r t h at pr e v a i le d i n t h e fi r s t i n s t a nt s officer for ALICE. and a data sample 100 times larger than what has been

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FEATURE ALICE UPGRADE FEATURE ALICE UPGRADE ALICE-PHO-GEN-2019-001-45 u ique Jun A ALICE will be

C Ga rg iulo ready to enter into a new era of high- precision measurements that will expand and deepen our understanding of the physics of hot and dense QCD matter Inner tracker Left: a schematic of the upgraded inner tracking system (ITS) showing the MAPS layers, carbon-fibre supports (black) and the narrower beampipe in the central region (orange). Right: photograph of the upgraded ITS inner half-layers.

o b t a i n e d s o f a r. I n a d d it io n, t h e up g r a d e d d e t e c t or s y s t e m The beam pipe has also been redesigned with a smaller w i l l h a v e b e t t e r e ffic ie n c y for t h e d e t e c t io n o f s h or t-l ived o ut e r r a d iu s o f 19 m m, a l lo w i n g t h e fi r s t d e t e c t io n l a y e r to particles containing heavy-flavour quarks thanks to the b e pl a c e d c lo s e r t o t h e IP at a r a d iu s o f 2 2.4 mm compared improved precision of the tracking detectors. to 39 mm at present. The brand-new ITS detector will During long-shutdown two (LS2), several major improve the impact parameter resolution by a factor of Enhancements Working on assembling one of the gas electron multiplier detectors in the cleanroom. upgrades to the ALICE detector will take place. These t h ree i n t he t r a ns verse pla ne a nd by a f ac tor of five a long include: a new inner tracking system (ITS) with a new the beam axis. It will extend the tracking capabilities to a single, large-size scintillator ring. The arrays will be reconstruction of events in several steps synchronously

high-resolution, low-material-budget silicon tracker, much lower pT, a l lo w i n g A L IC E t o p e r for m m e a s u r e m e nt s placed on both sides of the IP. It will be the primary trigger, with data taking. At its peak, the estimated data throughput which extends to the forward rapidities with the new of heavy-flavour hadrons with unprecedented precision luminosity and collision time-measurement detector in to mass storage is 90 GB/s. 2 muon forward tracker (MFT); an upgraded time projec- and down to zero pT. ALICE. The detector will be capable of triggering at an A new computing facility for the O system is being tion chamber (TPC) with gas electron multiplier (GEM) In the forward-rapidity region, ALICE detects muons interaction rate of 50 kHz, with a time resolution better installed on the surface, near the experiment. It will have a detectors, along with a new readout chip for faster readout; using the muon spectrometer. The new MFT detector is t han 30 ps, with 99% efficiency. data-storage system with a storage capacity large enough a new fast interaction trigger (FIT) detector and for- desig ne d to add ver te x i ng c apabi l it ies to t he muon s p e c- The newly designed ALICE readout system presents a to accommodate a large fraction of data of a full year’s data ward diffraction detector. New readout electronics will be trometer and will enable a number of new measurements change in approach, as all lead–lead collisions that are taking, and will provide the interface to permanent data installed in multiple subdetectors (the muon spectrometer, t h at a r e c u r r e nt l y b e yo n d r e a c h. A s a n e x a m ple, it w i l l a l lo w produced in the accelerator, at a rate of 50 kHz, will be read storage at the tier-0 Grid computing centre at CERN, as time-of-flight detector, transition radiation detector, us to distinguish J/ψ m e s o n s t h at a r e pr o d uc e d d i r e c t l y i n out in a continuous stream. However, triggered readout well as other data centres. electromagnetic calorimeter, photon spectrometer and the collision from those that come from decays of mesons will be used by some detectors and for commissioning ALICE upgrade activities are proceeding at a frenetic z e r o -d e g r e e c a lor i m e t e r) a n d a n i nt e g r at e d o n l i n e– offl i n e that contain a beauty quark. The MFT consists of five disks, and calibration runs and the central trigger processor is pace. Soon after the machine stopped in December, experts (O2) computing system will be installed to process and e a c h c o m p o s e d o f t wo M A P S d e t e c t io n pl a n e s, pl a c e d p e r- being upgraded to accommodate the higher interaction entered the cavern to open the massive doors of the magnet store t he large data volumes. pendicular to the beam axis between the IP and the hadron rate. The readout of the TPC and muon chambers will and started dismounting the detector in order to prepare absorber of t he muon spectrometer. be performed by SAMPA, a newly developed, 32-channel for the upgrade. Detailed planning and organisation of Detector upgrades T h e T P C i s t h e m a i n d e v ic e for t r a c k i n g a n d c h a r g e d-p a r- front-end analogue-to-digital converter with integrated the work are mandatory to stay on schedule, as Arturo A new all-pixel silicon inner tracker based on CMOS t ic le id e nt i fic at io n i n A L IC E. T h e r e a d o ut r at e o f t h e TPCin digital signal processor. Tauro, the deputy technical coordinator of ALICE explains: monolithic active pixel sensor (MAPS) technology will it s pr e s e nt for m i s l i m it e d b y it s r e a d o ut c h a m b e r s, w h ic h “Apart from the new detectors, which require dedicated b e i n st a l le d c over i ng t he m id-r apid it y (|η| < 1.5) region of are based on multi-wire proportional chambers. In order Performance boost infrastructure and procedures, we have to install a huge t he ITS a s we l l a s t he for w a rd r apid it y (–3.6 < η < –2.45) of to avoid drift-field distortions produced by ions from the The significantly improved ALICE detector will allow the nu m b e r o f s e r v ic e s (for e x a m ple, c a ble s a n d o p t ic a l fi br e s) the MFT. In MAPS technology, both the sensor for charge amplification region, the present readout chambers fea- collaboration to collect 100 times more events during LHC and perform regular maintenance of the existing appa- c ol le c t io n a n d t h e r e a d o ut c i rc u it for d i g it i s at io n a r e h o s t e d t u re a c h a r ge g at i n g s c he m e t o c ol le c t b a c k-d r i f t i n g ion s Run 3 compared to Run 1 and Run 2, which requires the ratus. We have an ambitious plan and a tight schedule i n t h e s a m e pie c e o f s i l ic o n i n s t e a d o f b e i n g b u m p -b o n d e d that lead to a limitation of the readout rate to 3.5 kHz. To development and implementation of a completely new ahead of us.” together. The chip developed by ALICE is called ALPIDE, overcome this limitation, new readout chambers employing readout and computing system. The O2 system is designed When the ALICE detector emerges revitalised from the and uses a 180 nm CMOS process provided by TowerJazz. a novel configuration of stacks of four GEMs have been to combine all the computing functionalities needed in two busy and challenging years of work ahead, it will be With this chip, the silicon material budget per layer is developed during an extensive R&D programme. This the experiment: detector readout, event building, data ready to enter into a new era of high-precision measure- reduced by a factor of seven compared to the present ITS. a r r a n g e m e nt a l lo w s for c o nt i nuo u s r e a d o ut at 50 k H z w it h recording, detector calibration, data reconstruction, physics ments that will expand and deepen our understanding of The ALPIDE chip is 15 × 30 mm2 i n a rea a nd cont a i ns more lead–lead collisions, at no cost to detector performance. simulation and analysis. The total data volume produced the physics of hot and dense QCD matter and the quark– than half a million pixels organised in 1024 columns and The production of the 72 inner (one GEM stack each) and by the front-end cards of the detectors will increase sig- gluon plasma.  512 rows. Its low power consumption (< 40 mW/cm 2) and o ut e r (t h r e e GE M s t a c k s e a c h) c h a m b e r s i s n o w pr a c t ic a l l y nificantly, reaching a sustained data throughput of up to e x c e l le nt s p at i a l r e s olut io n (~5 μm) a r e p e r fe c t for t h e i n n e r completed and certified. The replacement of the chambers 3 TB/s. To minimise the requirements of the computing Further reading tracker of ALICE. in the TPC will take place in summer 2019, once the TPC is system for data processing and storage, the ALICE com- ALICE Collaboration 2014 J. Phys. G 41 087002. The ITS consists of seven cylindrical layers of ALPIDE extracted from the experimental cavern and transported puting model is designed for a maximal reduction in the ALICE Collaboration 2015 CERN-LHCC-2015-001. c h i p s, s u m m i n g up t o 1 2.5 bi l l io n pi x e l s a n d a t o t a l a r e a o f to t he sur face. data volume read out from the detectors as early as possible ALICE Collaboration 2014 CERN-LHCC-2013-019. 10 m2. The pixel chips are installed on staves with radial T h e n e w for w a rd i nt e r a c t io n t r i g g e r, F I T, c o m pr i s e s t w o during the data processing. This is achieved by online ALICE Collaboration 2014 CERN-LHCC-2013-020. distances 22–400 mm away from the interaction point (IP). a r r a y s o f C h e r e n k o v r a d i at or s w it h MC P–PM T s e n s or s a n d processing of the data, including detector calibration and ALICE Collaboration 2015 CERN-LHCC-2015-006.

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FEATURE CMS UPGRADE FEATURE CMS UPGRADE

CMS-PHO-GEN-2013-012-5 A NEW ERA IN CALORIMETRY

The high-granularity silicon modules and scintillator calorimeter (HGCAL) is a tiles. The use of both detector major upgrade of CMS, and is technologies optimises the necessary to maintain excellent overall cost of the HGCAL whilst calorimetric performance in maintaining excellent long-term

the endcaps during HL-LHC CERN-PHOTO-201812-333-1 performance. operations. HGCAL is one of Prototype development the most ambitious detector began in 2016, and hexagonal projects undertaken, due to the silicon sensors have been built combination of extremely high into modules to evaluate the readout and trigger granularity, feasibility of the overall design coupled with the harsh radiation and to study the performance environment of the CMS endcaps in beams at Fermilab, DESY during HL-LHC operation. Two and CERN. Results from these radiation-tolerant materials beam tests compare very well have been selected: silicon in with simulations. Thanks to the high-radiation region and HGCAL’s readout/triggering plastic scintillator tiles in the granularity and timing resolution less harsh regions. To mitigate for showers, the expected the effects of radiation damage, Prototype sensors The assembly of prototype HGCAL detector planes, performance in terms of energy the silicon sensors must be based on 6" silicon modules, at CERN in October. resolution, particle identification cooled to about –30 °C, which and triggering are all comparable also allows the use of on-tile (maximising the useable surface and the resulting hexagonal to the present CMS endcap silicon photomultipliers for the of 8" circular silicon wafers) modules are mounted on either calorimeters – even in the

scintillator readout. divided into hexagonal cells. side of CO2-cooled copper plates. presence of 200 pileup events and HGCAL has around 6.5 million The sensors are sandwiched The following eight layers are after the full radiation exposure detector channels, divided into between high-density copper- similar, forming the front part of expected at HL-LHC. The project 52 layers. The first 28 layers tungsten alloy baseplates on the hadronic section of HGCAL, has now moved to the final design form the electromagnetic one side and printed circuit but are single-sided and use and prototyping phase, with section, which is based on boards containing the front- a lighter baseplate, while the construction due to start in a hexagonal silicon sensors end electronics on the other, final 16 layers incorporate both couple of years.

(HL-LHC) to maximum effect in the coming years, the CMS pare for Run 4,” says tec hnical coordinator Aust in Ball. collaboration has to battle higher overall par ticle rates, A dedicated CMS upgrade programme was planned higher “pileup” of superimposed proton–proton collision since the LHC switched on in 2008. It is being carried events per LHC bunch crossing, and higher instantaneous out in two phases: the first, which started in 2014 during a n d i nt e g r at e d r a d i at io n d o s e s t o t h e d e t e c t or e le m e nt s. LS1, concerns improvements to deal with a factor-of- In the collaboration’s arsenal to combat this assault are two increase over the design instantaneous luminosity s i l ic o n s e n s or s a ble t o w it h s t a n d t h e le v e l s o f i r r a d i at io n delivered in Run 2; and the second relates to the upgrades expected, a new high-rate trigger, and detectors with n e c e s s a r y for t h e H L- L HC. T h e p h a s e-1 up g r a d e i s a l m o s t Detector focus The open detector from below, showing the beam pipe and endcap calorimeter “nose” . higher granularity or precision timing capabilities to complete, thanks to works carried out during LS1 and help disentangle piled-up events. regular end-of-year technical stops. This included the The majority of CMS detector upgrades for the HL-LHC replacement of the three-layer barrel (two-disk forward) will be installed and commissioned during long-shut pixel detector with a four-layer barrel (three-disk forward) down three (LS3). However, the planned 30-month version, the replacement of photosensors and front-end CMS HAS HIGH duration of LS3 imposes logistical electronics for some of the hadron calorimeters, and the A dedicated CMS constraints that result in a large introduction of a more powerful, FPGA-based, level-1 part of the muon-system upgrade hardware trigger. LS2 will conclude phase-1 by upgrading upgrade programme and many ancillary systems (such photosensors (hybr id photodiodes) in t he bar rel hadron LUMINOSITY IN SIGHT was planned since as cooling, power and environmen calorimeter with silicon photomultipliers and replacing tal control) needing to be installed the innermost pixel barrel layer. the LHC switched on One of the biggest challenges for the CMS collaboration during LS2 is to prepare its s u b s t a nt i a l l y b e for e h a n d. T h i s m a k e s in 2008 t h e C M S w or k pl a n for L S2 e x t r e m e l y Phase-2 activities detector for the massive future installations necessary for the HL-LHC. c o m ple x, d i v id i n g i nt o t h r e e c l a s s e s o f But LS2 also sees the start of the phase-2 CMS upgrade, activity: the five-yearly maintenance the first step of which is a new beampipe. The collabo of the existing detectors and services, the completion ration already replaced the beampipe during LS1 with a he CMS detector has performed better than what and bottom quarks – that were once deemed impossible. of so called “phase 1” upgrades necessary for CMS to narrower one to allow the phase-1 pixel detector to reach was thought possible when it was conceived. Indeed, together with its sister experiment ATLAS, CMS c o nt i nue t o o p e r at e u nt i l L S3, a n d t h e i n it i a l up g r a d e s t o closer to the interaction point. Now, the plan is to extend T Combined with advances in analysis techniques, has turned the traditional view of hadron colliders as THE AUTHOR detectors, infrastructure or ancillary systems necessary the cylindrical section of the beampipe further to provide this has allowed the collaboration to make measure- “hammers” rather than “scalpels” on its head. Matthew for HL-LHC. “The challenge of LS2 is to prepare CMS for space for t he phase-2 pi xel detector w it h enlarged pseu ments – such as the coupling between the Higgs boson In exploiting the LHC and its high-luminosity upgrade Chalmers editor. Run 3 while not neglecting the work needed now to pre do-rapidity coverage, to be installed in LS3. In addition,

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FEATURE CMS UPGRADE FEATURE ATLAS UPGRADE CERN-PHOTO-201702-052-137 CMS collaboration CERN-PHOTO-201806-175-1

Assembly The production of the GEM chambers to be installed in the muon endcaps during LS2.

for the muon detectors CMS will install a new gas electron including the construction of the on-site surface infra- Pixel renewal mu lt i pl ie r (GE M), l a y e r i n t h e i n n e r r i n g o f t h e fi r s t e n d c a p structures necessary for the construction, assembly or Replacing the CMS disk, upgrade the on-detector electronics of the cathode refurbishment activities of the phase-2 detectors, is critical pixel detector in strip chambers, and lay services for a future GEM layer and for a successful CMS phase-2 upgrade,” explains upgrade early 2017. improved resistive plate chambers. Several other prepara- coordinator Frank Hartmann. “Although still far away, tions of the detector infrastructure and services will take LS3 activities are already being planned in detail.” The place in LS2 to be ready for the major installations in LS3. future LS3 shutdown will see the CMS tracker completely replaced with a new outer tracker that can provide tracks Work plan at 40 MHz to the upgraded level-1 trigger, and with a new Key elements of the LS2 work plan include: construct- inner tracker with extended pseudo-rapidity coverage. The ing major new surface facilities; modifying the internal 36 modules of the barrel electromagnetic calorimeter will structure of the underground cavern to accommodate be removed and their on-detector electronics upgraded to

new detector services (especially CO2 cooling); replac- enable the high readout rate, while both current hadron ing the beampipe for compatibility with the upgraded and electromagnetic endcap calorimeters will be replaced tracking system; and improving the powering system with a brand-new system (see “A new era in calorimetry” of the 3.8 T solenoid to increase its longevity through box). The addition of timing detectors in the barrel and the HL-LHC era. In addition, the system for opening and endcaps will allow a 4D reconstruction of collision vertices closing the magnet yoke for detector access will be mod- and, together with the other new and upgraded detectors, Iron support The mechanical structure of one of the new small wheels. ified to accommodate future tolerance requirements and reduce the effective event pile-up at the HL-LHC to a level service volumes, and the shielding system protecting comparable to that already seen. detectors from background radiation will be reinforced. “The upgraded CMS detector will be even more powerful Significant upgrades of electrical power, gas distribution and able to make even more precise measurements of the and the cooling plant also have to take place during LS2. properties of the Higgs boson as well as extending the ATLAS UPGRADES IN LS2 The CMS LS2 schedule is now fully established, with a searches for new physics in the unprecedented conditions critical path starting with the pixel-detector and beampipe of the HL-LHC,” says CMS spokesperson Roberto Carlin.  removal and extending through the muon system upgrade New wheel-shaped detectors that allow a o precisely study the Higgs boson and extend our and maintenance, installation of the phase-2 beampipe Further reading sensitivity to new physics in the coming years plus the revised phase-1 pixel innermost layer, and, after CMS Collaboration 2017 CERN-LHCC-2017-009. better trigger and measurement capability for T of LHC operations, the ATLAS experiment has a closing the magnet yoke, re-commissioning of the mag- CMS Collaboration 2017 CERN-LHCC-2017-011. muons are among numerous transformations clear upgrade plan in place. Ageing of the inner tracker net with the upgraded powering system. The other LS2 CMS Collaboration 2017 CERN-LHCC-2017-012. due to radiation exposure, data volumes that would activities, including the barrel hadron calorimeter work, CMS Collaboration 2017 CERN-LHCC-2017-013. taking place to maintain the ATLAS physics saturate the readout links, obsolescence of electron- will take place in the shadow of this critical path. CMS Collaboration 2017 CERN-LHCC-2017-014. programme into Run 3 and beyond. ics, and a collision environment swamped by up to 200 “The timely completion of the intense LS2 programme, CMS Collaboration 2017 CERN-LHCC-2017-023. interactions per bunch crossing are some of the headline

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ATLAS-PHOTO-2018-004-15 in France, Germany, Greece, Italy and Russia. On a daily Thousands of people FAST SDD® ATLAS basis, cables arrive to be assembled with connectors and around the world tested; piping is cut to length, cleaned and protected until in more than 200 Count Rate = >1,000,000 CPS installation; and gas-leak and high-voltage test stations institutes are involved are employed for quality control. In the meantime, several smaller upgrades will be deployed during LS2, including The True State-of-the-Art the installation of 16 new muon chambers in the inner • New in-house manufacturing layer of the barrel spectrometer. The organisation of LS2 activities is a complex exercise • Lower noise in which the maintenance needs of the detectors have to be • Lower leakage current addressed in parallel with installation schedules. After a • Better charge collection fi r s t p e r io d d e v o t e d t o t h e o p e n i n g o f t h e d e t e c t or andthe m a i nt e n a n c e o f t h e for w a rd muo n s p e c t r o m e t e r, t h e fi r s t Compatible with EPICS tools & libraries major non-standard operation (scheduled for January) will 2 55 be to bring to the surface the first small wheel. Having 25 mm FAST SDD® Fe Spectrum 25 mm2 FAST SDD® the detector fully open on one side will also allow very 800,000 230K, Tpk = 8 µs 1,000,000 important test for the installation of the new all-silicon Peak to 1 keV background Mn Kα 26,000:1 100,000 Mn Kβ inner tracker, which is scheduled to be installed during 600,000 LS3. The upgrade of the electromagnetic-calorimeter 10,000

electronics will start in February and continue for about COUNTS 400,000 122 eV FWHM 1,000 one year, requiring all front-end boards to be dismounted 100 from their crates, modifications to both the boards and 200,000 the crates, and reinstallation of the modified boards in 10 Extreme pile up challenges facing the 3000-strong collaboration. While their original position. Maintenance of the ATLAS tile 0 1 0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 A simulated event at many installations will take place during long-shutdown calorimeter and inner detector will take place in parallel, Energy (keV) the HL-LHC, with a three (LS3), beginning in 2024, much activity is taking a very important aspect of which will be the search for Resolution vs Peaking Time future inner tracker. place during the current LS2 – including major interven- leaks in the front-end cooling system. 180 25 mm2 tions to the giant muon spectrometer at the outermost 170 reaches of the detector. Delicate operation Standard SDD The main ATLAS upgrade activities during LS2 are In August, the first small wheel will be lowered again, 160 aimed at increasing the trigger efficiency for leptonic allowing the second small wheel to be brought to the ® 150 FAST SDD and hadronic signatures, especially for electrons and surface to make space for the NSW installation foreseen muons with a transverse momentum of at least 20 G eV. in April 2020. In the same period, all the optical transmis- 140 on (eV FWHM @ 5.9 keV) @ 5.9 FWHM on(eV ti To improve the selectivity of the electron trigger, the Endcap petals Assembling cathode strip chambers during the sion boards of the pixel detector will have to be changed. 130 Resolution (eV FWHM @ 5.9 keV) amount of information used for the trigger decision will end-of-year-shutdown in 2017/2018. Following these installations, there will be a long period Resolu 120 be drastically increased: until now, the very fine-grained of commissioning of all the upgraded detectors and the 0.000 1.00 1 2.00 2 3.00 3 4.00 4 5.00 5 Peaking Time (μs) information produced by the electromagnetic calorimeter which will produce counting rates as high as 20 kHz cm–2 preparation for the installation of the second NSW in Peaking Time (µs) is grouped in “trigger towers” to limit the number and in the inner part of the NSW, while delivering information the autumn of 2020. At that moment the closing process hence cost of trigger channels, but advances in electron- for the first-level trigger and muon measurement. The will start and will last for about three months, including Options: ics and t he use of opt ical fibres allows t he t ransmission main aim of the NSW is to reduce the fake muon triggers the bake-out of the beam pipe, which is a very delicate • 25 mm2 active area collimated to 17 mm2 of a much larger amount of information at a reasonable in the forward region and improve the sharpness of the and dangerous operation for the pixel detectors of the • 70 mm2 collimated to 50 mm2 cost. By replacing some of the components of the front- trigger threshold drastically, allowing the same selection inner tracker. • Windows: Be (0.5 mil) 12.5 µm, or end electronics of the electromagnetic calorimeter, the power as the present high-level trigger. A coherent upgrade programme for ATLAS is now C Series (Si3N4) level of segmentation available at the trigger level will be The first NSW started to take shape at CERN last year. fully underway to enable the experiment to fully exploit increased fourfold, improving the ability to reject jets and The iron shielding disks (see image on previous page), the physics potential of the LHC in the coming years • TO-8 package fits all Amptek configurations preserve electrons and photons. The ATLAS trigger and which serve as the support for the NSW detectors in of high-luminosity operations. Thousands of people • Vacuum applications data-acquisition systems will also be upgraded during addition to shielding the endcap muon chambers from around the world in more than 200 institutes are LS2 by introducing new electronics boards that can deal hadrons, have been assembled, while the services team is involved, and the technical design reports alone for the with the more granular trigger information coming from installing numerous cables and pipes on the disks. Only upgrade so far number six volumes, each containing the detector. a few millimetres of space is available between the disk several hundred pages. At the end of LS2, ATLAS will be and the chambers for the cables on one side, and between ready to take data in Run 3 with a renewed and better New small wheels the disk and the calorimeter on the other side, and the performing detector.  Since 2013, ATLAS has been working on a replacement for task is made even more difficult by having to work from its “small wheel” forward-muon endcap systems so that an elevated platform. In a nearby building, the sTGC Further reading they can operate under the much harsher background chambers coming from the different construction sites ATLAS Collaboration 2017 CERN-LHCC-2017-021. 40 Years of conditions of the future LHC. The new small wheel (NSW) are being integrated in full wedges and, soon this year, ATLAS Collaboration 2017 CERN-LHCC-2017-020. Products for Your Imagination THE AUTHOR detectors employ two detector technologies: small-strip the Micromegas wedges will be integrated and tested at ATLAS Collaboration 2017 CERN-LHCC-2017-019. ® thin gap chambers (sTGC) and Micromegas (MM). Both a separate integration site. The construction of the sTGC ATLAS Collaboration 2017 CERN-LHCC-2017-018. Ludovico Pontecorvo AMPTEK Inc. [email protected] t e c h n olo g ie s a r e a ble t o w it h s t a n d t h e h i g h e r flu x o f n eu- chambers is taking place in Canada, Chile, China, Israel ATLAS Collaboration 2017 CERN-LHCC-2017-017. is the ATLAS technical trons and photons expected in future LHC interactions, and Russia, while the Micromegas are being constructed ATLAS Collaboration 2017 CERN-LHCC-2017-005. coordinator, CERN. www.amptek.com

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FEATURE LHCb UPGRADE

The LHCb detector is to be totally rebuilt in time for the restart of LHCb’S MOMENTOUS LHC operations. METAMORPHOSIS

n November 2018 the LHC brilliantly fulfilled its prom- CERN-PHOTO-201812-329-15 ise to the LHCb experiment, delivering a total inte- I grated proton–proton luminosity of 10 fb–1 from Run 1 and Run 2 combined. This is what LHCb was designed for, and more than 450 physics papers have come from the adventure so far. Having recently finished swallowing these exquisite data, however, the LHCb detector is due some tender loving care. In fact, during the next 24 months of long-shutdown two (L S2), t h e 4500 t o n n e d e t e c t or w i l l b e a l m o s t e nt i r e l y r e b u i lt. When it emerges from this metamorphosis, LHCb will be a ble t o c ol le c t p h y s ic s e v e nt s at a r at e 10 t i m e s h i g h e r t h a n today. This will be achieved by installing new detectors capable of sustaining up to five times the instantaneous lu m i n o s it y s e e n at Ru n 2, a n d b y i m ple m e nt i n g a r e v olut io n- ary software-only trigger that will enable LHCb to process s i g n a l d at a i n a n up g r a d e d C P U f a r m at t h e f r e n e t ic r at e o f 40 MHz – a pioneer ing step among t he LHC e x per iments. LHCb is unique among the LHC experiments in that it is a s y m m e t r ic, c o v e r i n g o n l y o n e for w a rd r e g io n. T h at r e fle c t s its physics focus: B mesons, which, rather than flying out uni- formly in all directions, are preferentially produced at small angles (i.e. close to t he beam direction) in t he LHC’s proton c ol l i s io n s. T h e d e t e c t or s t r e t c h e s for 20 m a lo n g t h e b e a m pi p e, with its sub-detectors stacked behind each other like books on a shelf, from the vertex locator (VELO) to a ring-imaging Cherenkov detector (RICH1), the silicon upstream tracker (UT), the scintillating fibre tracker (SciFi), a second RICH (RICH2), t he calorimeters and, finally, t he muon detector. T h e L HC b up g r a d e w a s fi r s t o ut l i n e d i n 2008, pr o p o s ed in 2011 and approved the following year at a cost of about 57 million Swiss francs. The collaboration started dis- THE AUTHORS m a nt l i n g t he c u r re nt d e t e c t or ju s t b e fore t he e nd o f 2018 Massimiliano and the first elements of the upgrade are about to be Ferro-Luzzi moved underground. LHCb detector upgrade Physics boost coordinator, CERN. The LHCb collaboration has so far made numerous impor- Rolf Lindner tant measurements in the heavy-flavour sector, such as 0 + – LHCb technical the first observation of the rare decay Bs → µ µ , precise coordinator, CERN. m e a s u r e m e nt o f q u a r k-m i x i n g p a r a m e t e r s a n d t h e o b s e r-

Giovanni vation of new baryonic and pentaquark states. However, Passaleva many crucial measurements are currently statistically LHCb spokesperson, limited. The LHCb upgrade will boost the experiment’s CERN. physics reach by allowing the software trigger to handle Tender loving care The LHCb detector was opened up in December to make way for LS2 activities.

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FEATURE LHCb UPGRADE FEATURE LHCb UPGRADE E -H O-201810-281-14 T N-PHO CER S Jakobsen S cables and instrumented with 14 modules, each composed LHCb of a polymide hybrid circuit, a boron nitride stiffener and y a silicon microstrip sensor. side view ECAL HCAL Further downstream, nestled between the RICH2 and M5 M3 M4 the magnet, will sit the SciFi – a new tracker based on 5 m magnet SciFi RICH2 M2 RICH1 tracker scintillating fibres and silicon photomultiplier (SiPM) UT arrays, which replaces the drift straw detectors and silicon microstrip sensors used by the current three tracking vertex locator stations. The SciFi represents a major challenge for the col- (VELO) laboration, not only due to its complexity, but also because the technology has never been used for such a large area in such a harsh radiation environment. More than 11,000 km o f fi br e w a s ord e r e d, m e t ic u lo u s l y v e r i fie d a n d e v e ncured 5 m 10 m 15 m 20 m z from a few rare and local imperfections. From this, about Subdetector structure A cross-section showing the LHCb detector’s main elements. 1400 mats of fibre layers were recently fabricated in four crew are now busily working in the cavern, and many of VELO upgrade institutes and assembled into 140 rigid 5 × 0.5 m2 modules. the 79 institutes involved in the LHCb collaboration from Testing the new I n p a r a l le l, Si PM s w e r e a s s e m ble d o n fle x c a ble s a n d j oi ned around the world have shifted their focus to this herculean VELO modules in groups of 16 with a 3D-printed titanium cooling tube to task. The entire installation will have to be ready for the at CERN. form sophisticated photodetection units for the modules, commissioning of the new detector by mid-2020 so that which will be operated at about -40 °C. it is ready for the start of Run 3 in 2021. 

CER N-PHO T O-201811-290-5 As this brief overview demonstrates, the LHCb detector is undergoing a complete overhaul during LS2 – with Further reading large parts being totally replaced – to allow this unique LHCb Collaboration 2008 CERN-LHCC-2008-007. LHC experiment to deepen and broaden its exploration LHCb Collaboration 2011 CERN-LHCC-2011-001. programme. CERN support teams and the LHCb technical LHCb Collaboration 2012 CERN-LHCC-2012-007.

Under construction Modules being lowered into place for LHCb’s new data centre. Development The SciFi tracker modules being assembled.

an input rate around 30 times higher than before, bringing lecting signal hits from 256 × 256 pixels and sending data at greater precision to theoretically clean observables. a rate of up to 15 Gb/s, was developed for this purpose. Pixel Flowing at an immense rate of 4 TB/s, data will travel modules include a cutting-edge cooling substrate based on from the cavern, straight from the detector electronics an array of microchannels trenched out of a 260 µm-thick via some 9000 300 m-long optical fibres, into front-end silicon wafer that carry liquid carbon dioxide to keep the computers located in a brand-new data centre that is cur- silicon at a temperature of -20 °C. This is vital to prevent rently nearing completion. There, around 500 powerful thermal run-away, since these sensors will receive the heav- custom-made boards will receive the data and transfer it to iest irradiation of all LHC detectors. Prototype modules have thousands of processing cores. Current trigger-hardware recently been assembled and characterised in tests with equipment will be removed and new front-end electronics high-energy particles at the Super Proton Synchrotron. have been designed for all the experiment’s sub-detectors The RICH detector will still be composed of two sys- to cope with the substantially higher readout rates. tems: RICH1, which discriminates kaons from pions in For the largest and heaviest LHCb devices, namely the the low-momentum range, and RICH2, which performs calorimeters and muon stations, the detector elements this task in the high-momentum range. The RICH mirror will remain mostly in place. All the other LHCb detec- system, which is required to deflect and focus Cherenkov tor systems are to be entirely replaced, apart from a few photons onto photodetector planes, will be replaced with structural frames, the dipole magnet, shielding elements a new one that has been optimised for the much increased and gas or vacuum enclosures. particle densities of future LHC runs. RICH detector columns are composed of six photodetector modules (PDMs), Subdetector activities each containing four elementary cells hosting the mul- The VELO at the heart of LHCb, which allows precise meas- ti-anode photomultiplier tubes. A full PDM was success- When it urements of primary and displaced vertices of short-lived fully operated during 2018, providing first particle signals. re-emerges, particles, is one of the key detectors to be upgraded during Mounted just between RICH1 and the dipole magnet, the LHCb will be LS2. Replacing the current system based on silicon microstrip upstream tracker (UT) consists of four planes of silicon able to collect modules, the new VELO consists of 26 tracking layers made microstrip detectors. To counter the effects of irradiation, physics events from 55 × 55 µm2 pixel technology, which offers better hit the detector is contained in a thermal enclosure and cooled

at a rate 10 resolution and simpler track reconstruction. The new VELO to approximately -5 °C using a CO2 evaporative cooling times higher will also be closer to the beam axis, which poses significant system. Lightweight staves, with a carbon foam back- than today design challenges. A new chip, the VELOPIX, capable of col- plane and embedded cooling pipe, are dressed with flex

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FEATURE FUTURE CIRCULAR COLLIDER

Mind the gap A schematic layout of the FCC in comparison with A GIANT the current LHC. LEAP FOR PHYSICS

Going from the LHC to a 100 km-

circumference supercollider is a daunting office study Media/FCC Polar challenge, but the community has made similar jumps in the past – and the future of fundamental exploration is at stake.

article physics has revolutionised our understanding pages distributed over four volumes, the FCC CDR covers Large Electron Positron collider (LEP) and eventually to which was formally launched in early 2014, also explores of the universe. The experimental and theoretical all aspects of the project, including technologies, detector the LHC, allowing the completion of the Standard Model. the option of a proton–electron collider (FCC-he) that P tools developed in the 20th century delivered the design, physics goals and civil-engineering considerations. Jumping to larger and more complex machines always comes could run in parallel with FCC-hh, and a high-energy LHC Standard Model of particle physics, the particle content But what changes when we move from a 27 km to a new with new challenges, but these translate precisely into b a s e d o n h i g h-fie ld m a g n e t s i n s t a l l e d i n t h e c u r r e ntLHC of which was completed in 2012 with the discovery of the 100 km-long tunnel, and what stays the same? The obstacles opportunities for young researchers and industry (CERN tunnel (CERN Courier June 2018 p15). Higgs boson at the LHC. And, yet, this hugely powerful to new colliders pushing the current energy and intensity Courier September 2018 p51). The cost of future colliders is a major issue, and con- theory leaves several observations unexplained. In solving frontiers are many, yet the past five years have seen the A 100 k m t u n n e l offe r s t h r e e m a i n c ol l id e r o p t io n s. The certed value-engineering of all aspects from individual mysteries such as the nature of dark matter, the origin of international FCC study steadily break them down. most straightforward in terms of technological readi- components through sustainability to neutrino masses, the dominance of matter over antimatter ness is a luminosity-frontier lepton collider (FCC-ee) logistics is required. Cost estimates FCC-hh will on cosmological scales, and the low mass of the Higgs Lessons learned that will deliver unprecedented collision rates in a clean for FCC construction and operation are produce a pile-up THE AUTHORS boson itself, physicists could open a completely new view The FCC design report shows that CERN’s existing accelera- environment at specific energies corresponding to the detailed in the CDR, although the range Michael Benedikt of nature. Therefore, it is high time to start planning a new tor chain can serve as the foundation for a 100 km post-LHC Z pole (91 GeV), the WW threshold (161 GeV), Higgs proof collider modes, staging approaches of up to 1000 events FCC study leader, collider that maintains this rich course of exploration machine, while also opening a rich fixed-target programme. duction (240 GeV), and the top quark–antiquark thresh- a n d t e c h n ol o g y c h oic e s m a k e it d i ffic u lt per bunch crossing CERN. throughout the 21st century. The new 100 km infrastructure is indeed enormous, repre- old (350 to 365 GeV). By filling the FCC tunnel with new t o pl a c e a s i n g le fi g u r e o n e a c h m a c h i n e.

Frank In late 2018 the Future Circular Collier (FCC) collabora- senting a four-fold increase in dimensions compared to the superconducting magnets twice the strength of the LHC’s Construction on a site with an existing Zimmermann tion published a conceptual design report (CDR) addressing LHC. But, taking history as a guide, it should be possible: (16 T a s o p p o s e d t o 8 T), however, a hadron collider called i n f r a s t r uc t u r e, a s offe r e d b y C E R N, i s a m aj or c o s tadvn- FCC study deputy this need. A similar proposal is also under development this jump in scale is identical to that adopted in the 1980s FCC-hh can be built with a collision energy of 100 TeV – a n tage in terms of capital investment, sharing of infra- leader, CERN. in China (CERN Courier June 2018 p21). In more than 1000 to move from the Super Proton Synchrotron (SPS) to the order-of-magnitude higher than the LHC. The FCC study, structure and breadth of the overall physics programme.

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FEATURE FUTURE CIRCULAR COLLIDER FEATURE FUTURE CIRCULAR COLLIDER N Caraban/CERN

36 –2 –1 Z (91.2 GeV): 4.6 × 10 cm s LEP × 105! FCC-ee (baseline, 2 IPs) ILC (baseline)

Russenschuck, CERN )

S FCC-ee CLIC (baseline) –1 s 102 CEPC (baseline, 2 IPs) –2 W+W– (161 GeV): 5.6 × 1035 cm–2s–1 cm 34 HZ (240 GeV): 1.7 × 1035 cm–2s–1 CEPC 10 – 34 2 1 tt (350 GeV): 3.8 × 10 cm– s– (365 GeV): 3.1 × 1034 cm–2s–1

luminosity (10 CLIC HZ (250 GeV): 1.5 × 1034 cm–2 s–1 1 ILC

2 3 10 √s (GeV) 10

Fig. 1. Lepton-collider luminosity as a function of centre-of- mass energy for different accelerator baseline projects and technologies, showing FCC-ee, the Circular Electron Positron Collider (CEPC), the Compact Linear Collider (CLIC) and the International Linear Collider (ILC).

bunches – up to around 16,000 at the Z pole – by avoid- w it h in 0.5 MeV. A strategy based on the resonant-depo- Racetrack coil ing parasitic collisions. This approach also allows for a larisation technique, as used at LEP, guarantees precise A model coil for well-centered orbit all around the ring and a nearly perfect energy measurements every 15-20 minutes for both the 16 T FCC-hh dipole – mitigation of the energy “sawtooth” at the highest tt electron and positron beam. magnets with energies. A so-called tapering scheme is foreseen, which The design of the FCC-ee detectors is also described in niobium-tin will enable the strengths of all the magnets to be scaled the FCC design report. Due to the beam crossing angle, the superconducting according to the local energy of the electron and posi- detectors’ solenoid magnetic field is limited to 2T to c on- cable. FCC-ee Quadrupole test magnet at CERN’s magnetic measurement laboratory. tron beams, taking into account any differences in the fine their impact on the luminosity due to the synchrotron energy loss due to synchrotron radiation. Also distinct radiation emitted within the solenoid field. Two detector The sequence of FCC-ee and FCC-hh would also resemble at a beam energy of 182.5 GeV and combines four dipole from LEP, a top-up injection scheme has been designed concepts have been optimised for the FCC-ee: CLD, a consol- the successful staging of LEP and the LHC: a lepton– magnets and two main quadrupoles in a 50 m-long section. for FCC-ee to maximise the integrated luminosity, idated option based on the detector developed for CLIC, with lepton machine followed by a hadron collider (both for Moreover, to achieve the required high luminosities, the whereby electrons and positrons are injected into the a silicon tracker and a 3D-imaging highly-granular calo- * protons and heavy ions). In the case of the FCC, possi- vertical beam size at the interaction points (called βy) has machine by a full-energy booster to maintain a constant rimeter; and IDEA, a bolder, possibly more cost-effective, bly even a future muon collider could then follow as a to be ver y small (0.8 mm) at the Z pole, which is 50 times high beam current. design, with a short drift-wire chamber and a dual-readout third stage. smaller than for LEP but about three times larger than for c a lor i m e t e r. Ho w e v e r, s p e c i fic d e t e c t or-t e c h n olo g y c h oic es FCC-ee is a dream machine for precision measurements, the SuperKEKB accelerator now being commissioned in Beating the fourth power will be made at a later date. * taking the successful LEP scheme into entirely new territory Japan. The reduction in βy is possible because of techno- When moving to a larger radius and higher energies, one of Following the operation of FCC-ee, the same tunnel (figure 1). Precise measurements of the properties of the logical innovations during the past three decades (such as the key obstacles for colliders is the synchrotron radiation could host a 100 TeV proton collider, FCC-hh. A very large, Z, W and Higgs boson and the top quark, together with l o c a l c h r o m at ic c or r e c t io n o f t h e fi n a l-q u a d r up ol e d o u ble t emitted by the accelerated particles because the resulting circular hadron collider is the only feasible approach to much improved measurements of other input parameters and use of a crab-waist collision scheme) and thanks to energy loss increases with the fourth power of a charged r e a c h s i g n i fic a nt l y h i g h e r c ol l i s io n e n e r g ie s t h a n t h e L HC to the Standard Model such as the electromagnetic and the large size of the ring. particle’s energy. Improving energy efficiency is criti- (13-14 TeV) in the coming decades. A 100 TeV collider would strong coupling constants, would provide sensitivity to Indeed, achieving the unprecedented FCC-ee luminosity cal for any future big accelerator, and the development offer access to new particles through direct production in new par t icles w it h masses in t he range 10–70 TeV. of up to 4 × 1036 cm–2s–1 (the total for two experiments), while of high-efficiency RF power sources, along with robust the few-TeV to 30 TeV mass range, far beyond the LHC’s minimising the amount of synchrotron radiation near higher-gradient superconducting cavities, is at the core reach. It would also provide much higher rates for phe- Common lattice the detector, called for considerable effort in designing of the FCC programme. The cavities can be produced, for nomena in the sub-TeV mass range and therefore much T h e b u l k o f FC C- e e w i l l c o m pr i s e a r o u n d 8000 n or m a l-c o n- the final-focus system. Combined with a small cross- example, by applying a thin superconducting film on a greater precision on key measurements (CERN Courier May ducting low-power and cost-effective twin-aperture dipole ing angle of 30 mrad, the minimum distance from the copper substrate, as is currently being pursued by CERN in 2017 p34). m a g n e t s, 3000 fo c u s i n g m a g n e t s a n d b e t w e e n 26 (Z p ole) interaction point to the first quadrupole is 2 m, which collaboration with global partners (CERN Courier May 2018 W it h i n 25 y e a r s o f o p e r at io n, FC C-h h c o u ld a c c u mu l at e and 161 (t– t threshold) four-cavity radio-frequency (RF) is a compromise between beam dynamics and detector p26). To achieve a low power consumption and guarantee an integrated luminosity of around 20 ab–1 in each of the cryomodules, to compensate for the energy loss from syn- constraints. The present optics design has a momentum sustainable operation, a high conversion efficiency from t w o m a i n e x p e r i m e nt s. FC C-h h a l s o o ffe r s t h e p o s s i bi l it y chrotron radiation and provide the required accelerating acceptance of around 2%, which is one of the most critical wall-plug to RF power is critical. The FCC target RF oper- of colliding heavy ions with protons and heavy ions with We are voltage. Currently, two interaction points are planned for requirements of the FCC-ee design because it determines ation efficiency is 65%, profiting from recent innovations heavy ions, adding to its physics opportunities. Reaching proposing high-luminosity FCC-ee operations, though up to four the beam lifetime. in klystron design at CERN. the physics goals of such a collider requires a machine an ambitious can be accommodated. A common FCC-ee lattice has been A distinct feature of FCC-ee, in contrast to LEP, is the For FC C- e e t o f u l fi l it s pr o m i s e o f pr e c i s io n e l e c t r oweak availability of about 70%, which is comparable to what accelerator designed for all energy stages except for the highest energy use of separate beam pipes for the two counter-rotating measurements, it is also vital that physicists can accurately has been routinely reached with the LHC. Nevertheless, to push the t– t threshold, where a small rearrangement of the beamline electron and positron beams, based on energy-efficient determine its centre-of-mass energy so that the Z mass considering the increased machine complexity and the boundaries of passing through the RF cavities will be needed. The basic dual-aperture main magnets (pictured above). The two can be measured with a relative precision of 3 × 10–5, the introduction of an additional machine in the injector chain knowledge cell of the FCC-ee lattice has been chosen for operation separate rings allow operation with a large number of total Z width with a precision of 0.1 MeV and the W mass in the FCC baseline scenario, achieving this target avail-

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Accelerator in Luis A nton io G on za lez G omez (CER N) system to protect the machine components. Each of the Germany. two rings will have to reliably abort proton beams with stored energies of around 8 GJ, which is more than an order Good strategy demands the right balance of magnitude higher than for HL-LHC. Beam extraction at

the FCC has to be fast, and the first prototypes of new kicker D Dominguez generator and superconducting septum technologies are As the second update of the European now being tested. Strategy for Particle Physics gets under Synchrotron radiation is also an issue, since FCC-hh w ay, T at suy a Na k ada refle c t s on t he will emit about 5 MW at 100 TeV, and calls for a novel experience of the previous update in 2013. beam screen held at a temperature of 50 K (compared with 5–20 K at t h e L HC). T h e FC C-h h b e a m s c r e e n, a pr o t o t y p e

of which is shown left, enables cost-effective heat removal 2 Strategy is a base that allows resources 002 and maintains the high quality vacuum while providing to be prioritised in the pursuit of im p 2010 shielding from the beam. Finally, cooling the FCC-hh ortant goals. No strategy would be needed if enough resources were avail superconducting magnets poses entirely new challenges PUBLIC able – we would just do what appears to PHO

compared to the LHC. In addition to the higher synchrotron be necessary.

radiation, the cooling system (which, like the LHC will LHCb Elementary particle physics generally use liquid helium at 1.9 K) will have to cope with higher requires large and expensive facilities, Community call Priorities for European particle physics will be formalised in the spring heat dissipated inside the cold magnets as well as from often on an international scale, which of 2020 following rigorous consultation at all levels. t he cold bore itsel f. About 100 MW of total cooling power Tatsuya Nakada take a long time to develop and are heavy ability poses major challenges. will be required to remove 5 MW of synchrotron radiation is a professor at the consumers of resources during opera to host an international linear collider opportunities and this was one of the key FCC-hh is envisioned to lie adjacent to the LHC and SPS, heat (see p8). Swiss Federal tions. For this reason, in 2005 the CERN in Japan, has not made much progress. ingredients that drove the strategy. with two injection insertions so that protons can be injected Institute of Council initiated a European Strategy In physics, discussions about strategy The challenge facing the community Technology from either the LHC or SPS tunnel. In the first case, the beam Coordinating the future for Particle Physics (ESPP), resulting in usually start with a principled statement: now in updating the current ESPP is to in Lausanne, and will be injected at an energy of 3.3 TeV from the LHC (which For almost 90 years, progress in particle physics has gone a document being adopted the follow “Science should drive the strategy”. This steer the field into the mid-2020s and was scientific ing year. The strategy was updated in is of course correct, but unfortunately beyond. As such, discussions about the requires, in addition to new transfer lines and extrac- hand-in-hand with progress in accelerators. Today, cap- secretary and 2013 and the community is now work not always sufficient in real life, since various ideas for the next big machine tion systems, some modifications to allow the LHC to be italising on the great success of the LHC, the field faces chairperson of the ing towards a second ESPP update (CERN physics consideration alone does not at CERN will be an important focus, but r a m p e d fi v e t i m e s f a s t e r t h a n t o d a y). I n t h e s e c o n d c ase, pivotal decisions about what collider to build next. Advanc- European Strategy Courier April 2018 p7). provide a practical solution most of the numerous other projects, including pro new superconducting SPS - from which other experiments ing the enabling technologies for a future circular collider Group for the The making of the ESPP has three ele time. In this context, it is worth recall posals for noncollider experiments, will 2013 European w o u ld a l s o pr ofit – c o u ld pr o v id e a b e a m at1.3 TeV u s i n g f a s t can only be done via a coordinated international effort ments: bottomup activities driven by ing the discussion about longbaseline be jostling for attention. Many brilliant Strategy for Particle ramping and cost-effective 6 T superconducting magnets. between universities, research centres and industry. It the scientific community through doc neutrino experiments that took place people are working in our field with many Physics Update. The FCC design report presents a complete lattice for FCC-hh also calls for smart solutions to ensure reliability and ument submission and an open sympo during the previous strategy exercises. e x c e l l e nt i d e a s, w it h d i ffe r e nt s t r e n g t h s that is consistent with this layout and the required energy s u s t a i n a bi l it y. T h e r e s u lt s o f t h e s e e ffor t s a r e d o c u m e nt ed sium (the latter to be held in Spain in May and weaknesses. The real issue of the reach. The arc lattice consists of around 500 cells each in the four volumes of the FCC conceptual design report, 2019); strategy drafting (to take place in Optimal outcome strategy update is how we can optimise 200 m long and made up of two short, straight sections and which presents a clear route to a post-LHC machine and Germany in January 2020) by scientists, At the time of the first ESPP almost 15 the resources using time and location, who are mostly appointed by CERN mem years ago, so little was known about and possibly synergies with other sci 12 cryo-dipoles, comprising one 14 m-lo n g d i p ole a n d o n e also serves as an input to the update of the European ber states; and the final discussion and the neutrino massmixing parame entific fields. 0.11 m-long sextupole corrector. Integrated studies of the Strategy for Particle Physics. approval by the CERN Council. Therefore, ters that several ambitious facilities The intention of the strategy is to lat t ice p er for ma nce a re ongoi ng a nd w i l l i n for m t he fi na l The FCC offers great potential for curiosity-driven the final product should be an amalga were discussed so as to cover necessary a c h i e v e a s c i e nt i fic g o a l. We m a y a l r e a dy choice for the magnet design, along with considerations research with unimaginable consequences. Discoveries mation of the wishes of the community parameter spaces. Some resources were disagree about what this goal is, since it is of power efficiency and cost. of new particles and forces not only alter our perspective a n d t h e p ol it i c a l a n d fi n a n c i a l c o n s t r a i nt s directed into R&D, but most probably they p e o pl e w it h d i ffe r e nt v i s i o n s, t a s t e s a nd of humankind’s position in the universe, but also, either defi ne d by st ate aut hor it ies. E x p er ie nce were too little and not well prioritised. habits who conduct research. But let us Reducing costs directly or via the technology that made them possible, of the previous ESPP update suggests that In the meantime, it became clear that a at least agree this to be “to understand The biggest cost in reaching higher energies is that of the lead to radical applications that improve our quality of this is entirely achievable, but not without stateoftheart neutrino beam based on the most fundamental laws of nature” for magnets. A primary goal of FCC-hh is to build 16 T s up e rc o n- life. In the present age of political turbulence and rapid effort and compromise. conventional technology would be suf now. Also, depending on the time scales, ducting magnets that are a factor of three to five times more change, we are proposing an ambitious future accelera- Out of four highpriority items in the ficient to make the next necessary step the relative importance of elements in the c o s t- e ffe c t i v e p e r TeV t h a n t h o s e o f t h e L HC. A c h ie v ingths tor complex to push the boundaries of knowledge and to current ESPP, which concluded in 2013, of measuring the neutrino CPviolation decisionmaking might change and fac Discussions three of them are well under way: the full parameter and mass hierarchy. What tors beyond Europe cannot be neglected. goal would impact many accelerator applications outside optimally prepare future generations for the challenges about the exploitation of the LHC via a luminosity should be done was therefore clear from Strategy that cannot be implemented is physics, from medical treatments to food-quality moni- they are sure to face.  various ideas upgrade; R&D and design studies for a a s c ie nt i fic p oi nt of v ie w, but t here si m not useful for anyone and the key is to toring and energy storage and distribution. The FCC study for the next future energyfrontier machine at CERN; ply were not enough resources in Europe make a judgement on the balance among has recently launched a global conductor R&D programme Further reading big machine at and establishing a platform at CERN for to construct a longbaseline neutrino many elements. Lastly, we should not for involving collaborators from the US, Russia, Europe, Japan M Benedikt et al. 2018 CERN-ACC-2018-0058. physicists to develop neutrino detectors experiment together with a high per get that the most exciting scenario for the and Korea to improve the performance of the niobium-tin M Benedikt et al. 2018 CERN-ACC-2018-0057. CERN will be for experiments around the world. The formance beam line while fully exploiting ESPP update will be the appearance of an conductor and to reduce its cost. M Michelangelo et al. 2018 CERN-ACC-2018-0056. an important remaining item, relating to an initiative of the LHC at the same time. The optimal unexpected result –then there would be The FCC-hh foresees two high-luminosity experiments, F Zimmermann et al. 2018 CERN-ACC-2018-0059. focus the Japanese particlephysics community outcome was found by considering global a real paradigm shift in particle physics.

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The Vortex® Series of Silicon Drift Detectors Exceptional Single- and Multi-Sensor SDD Understanding naturalness

WHY? The last few years have seen an explosion of original ideas concerning whether the universe is “natural” or not, and the LHC has brought the issue into sharp focus. But we’re only at the  Superior throughput: > 4 MCPS (OCR) beginning of our understanding, says theorist Nathaniel Craig.  Super-high resolution: < 250e V at 3 Mcps (OCR) N Craig  What is “naturalness”? of the so-called Potter Stewart 0.5 mm to 1.0 mm thick sensors: suited to a wide range of X-ray energies Colloquially, a theory is natural if its measure: “I know it when I see it.”  Custom designs for geometry, focused elements, and special requirements underlying parameters are all of the The element of judgement makes it same size in appropriate units. unproduct ive to obsess over minor  Available with a variety of DPP options including Xspress 3 or FalconX A more precise definit ion involves differences in fine-t uning, but large the notion of an effective field theory fine-tunings potent ially sig nal t hat – the idea that a given quantum field something is amiss. Also, one can’t theory might only describe nature help but not ice t hat t he deg ree of fine- at energies below a certain scale, or tuning that is considered acceptable cutoff. The Standard Model (SM) is has c hanged over t ime. an effect ive field t heor y because it cannot be valid up to arbitrarily high What evidence is there that energ ies even in t he absence of g rav it y. nature is natural? An effective field theory is natural if Dirac’s puzzle, the smallness of the all of its parameters are of order unity proton mass, is a great example: we in units of t he cutoff. Wit hout fine- understand it now as a consequence tuning, a parameter can only be much of the asymptotic freedom of the smaller than this if setting it to zero strong interaction. A natural (of increases the symmetry of the theory. order-unity) value of the QCD gauge All couplings and scales in a quantum coupling at high energies gives rise theory are connected by quantum to an exponentially smaller mass effects unless symmetries distinguish Does the concept appear in Nathaniel Craig scale on account of the logarithmic them, making it generic for them other disciplines? is an associate evolution of the gauge coupling. to coincide. There are not ions of nat uralness in professor at the Another excellent example, relevant to The excellent range of multi-sensor SDD detectors JUST GOT BETTER! essentially every scientific discipline, University of the electroweak hierarchy problem, is When did naturalness become a but physics, and particle physics in California the mass splitting of the charged and guiding force in particle physics? par t icular, is somewhat unique. This is Santa Barbara. neutral pions. From the perspective INTRODUCING THE VORTEX® ME-7 SDD We t y pically t race it bac k to perhaps not surprising, since one of the of an effect ive field t heorist work ing Eddington and Dirac, though it had primary goals of particle physics is to at the energies of these pions, their

precedents in the cosmologies of the infer the laws of nature at increasingly mass splitting is only natural if the The characteristics of the VORTEX® ME-4 SDD Ancient Greeks. Dirac’s discomfort higher energies and shorter distances. cutoff of t he t heor y is around 800 MeV. EVEN with the same probe diameter with large dimensionless ratios Lo and behold, going up in energy

in obser ved parameters – among Isn’t naturalness a matter of from the pions, the rho meson appears 2 ot hers, t he rat io of t he g rav itat ional personal judgement? at 770 MeV, revealing t he composite 7 x 50 mm SDD sensors in a probe diameter of 38.1 mm and electromagnetic forces between One can certainly come up with nature of the pions and changing the protons and electrons, which amounts frameworks in which naturalness picture in precisely the right way to to the smallness of the proton mass in is mat hemat ically defined – for render the mass splitting natural. units of the Planck scale – led him to e xample, quant i f y ing t he sensit iv it y propose a radical cosmology in which of some parameter in the theory to Which is the most troublesome New ton’s constant v aried w it h t he v ariat ions of t he ot her parameters. observation for naturalness today? age of t he universe. Dirac’s proposed However, what one does w it h t hat The element The cosmological-constant (CC) solut ions were readily falsified, but information is a matter of personal of judgement problem, which is the disagreement this was a predecessor of the more judgement: we don’t know how nature makes it by 120 orders of mag nit ude bet ween Vortex® ME-3 SDD (Detector Head) Vortex® ME-7 SDD (Detector Head) Vortex® ME-4 SDD refined not ion of nat uralness t hat computes fine-t uning (i.e. depar t ure unproductive t he obser ved and e x pected v alue of t he evolved w it h t he development of from nat uralness), or what amount of to obsess v acuum energ y densit y. We understand quant um field t heor y, whic h drew on fine-t uning is reasonable to e x pect. t he SM to be a v alid effect ive field over minor obser v at ions by Gell-Mann, ’t Hoof t, This is highlighted by t he occasional t heor y for many decades above t he Veltman, Wilson, Weinberg, Susskind abandonment of mathematically differences in energ y scale of t he obser ved CC, whic h Hitachi High-Technologies Science America, Inc. www.hitachi-hightech.com/hhs-us/ and other greats. defined nat uralness criteria in favour fine-tuning ma kes it ver y hard to believe t hat t he 21770 Nordhoff St., Chatsworth, CA 91311 Email: [email protected] Tel: +1-818-280-0745 CERN COURIER JANUARY/FEBRUARY 2019 45

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OPINION INTERVIEW

problem is solved in a conventional experiments. These null results haven’t w ay w it hout considerable fine-t uning. ruled out dark matter itself; they’ve Contrast that with the SM hierarchy only disfavoured cer tain specific and problem, which is a statement about historically popular models. D Dominguez/CERN D the naturalness of the mass of the Higgs boson. Data so far show t hat t he How can we settle the naturalness cutoff of t he SM as an effect ive field issue once and for all? t heor y might not be too far above t he The discover y of new par t icles around Higgs mass, bring ing nat uralness t he TeV scale whose proper t ies suggest w it hin reac h of e x periment. On t he they are related to the top quark would other hand, the CC is only a problem ver y st rongly suggest t hat nat ure is in the context of the SM coupled to more or less nat ural. In t he event of g rav it y, so perhaps its resolut ion lies non-discovery, the question becomes in yet-to-be-understood feat ures of Unnatural? Supernova 1987A. This marked the thornier – it could be that the SM is quantum gravity. Artistic illustration beginning of neutrino astronomy unnatural; it could be that naturalness of the Higgs boson, and opened the door to unrelated arg uments are ir relev ant; or it could be What about the tiny values for which quantum sur prises, yet t he large w ater- t hat t here are sig nat ures of nat uralness of the neutrino masses? corrections lead to Cherenkov detectors that detected t hat we haven’t recog nised yet. Kepler’s Neutrino masses are not remotely a naturalness or t hese neut rinos were orig inal ly sy mmet r y-based e x planat ion of t he t roublesome for nat uralness. A “hierarchy” constructed to look for proton decay naturalness of planetary orbits in terms parameter can be much smaller than problem. predicted by grand unified theories of platonic solids ultimately turned out the natural expectation if setting it (which were themselves motivated by to be a red her ring, but only because to zero increases the symmetry of naturalness arguments). we came to realise that the features of the theory (we call such parameters While it would be great if specific planetar y orbits are not deeply “technically natural”). For the naturalness-based arguments related to f undamental laws. neutrino, as for any SM fermion, successfully predict new physics, it’s there is an enhanced symmetry also worthwhile if they ultimately Without naturalness as a guide, how when neutrino masses are set to serve only to draw experimental do theorists go beyond the SM? zero. This means that your natural at tent ion to new places. Naturalness is but one of many hints expectation for the neutrino masses at physics beyond the SM. There are is zero, and if they are non-zero, What has been the impact of the LHC some incredibly robust hints based quantum corrections to neutrino results so far on naturalness? on data – dark matter and neutrino masses are proportional to the masses There have been two huge masses, for example. There are themselves. Although the SM features developments at the LHC. The first also suggestive hints, such as the many numerical hierarchies, the is the discovery of the Higgs boson, hierarchical structure of fermion majorit y of t hem are tec hnical ly- which sharpens the electroweak masses, the preponderance of baryons natural ones that could be explained by hierarchy problem: we seem to have over antibaryons and the apparent physics at inaccessibly high energies. found precisely the sort of particle unification of gauge couplings. There The most urgent problems are t he whose mass, if natural, points to a is also a compelling argument for hierarchies that aren’t technically sig nificant depar t ure from t he SM constructing new-physics models natural, like the CC problem and the around the TeV scale. The second is purely motivated by anomalous data. electroweak hierarchy problem. t he non-obser v at ion of new par t icles This sor t of “ambulance c hasing” does predicted by the most popular not have a stellar reputation, but it’s an Has applying the naturalness solutions to the electroweak hierarchy honest approach which recognises that principle led directly to a discovery? problem, such as supersymmetry. the discovery of new physics may well It’s fair to say that Gaillard and Lee While evidence for these solutions come as another case of “Who ordered predicted the charm-quark mass by could lie right around the corner, its that?” rather than the answer to a apply ing nat uralness arg uments to t he absence thus far has inspired both a theoretical problem. mass-splitting of neutral kaons. Of great deal of uncertainty about the course, t he same arg uments were also naturalness of the weak scale and a What sociological or psychological used to (incorrectly) predict a wildly lively exploration of new approaches aspects are at work? different value of the weak scale! to the problem. The LHC null results If theoretical considerations are This is a reminder that naturalness teach us only about specific (and primarily shaping t he adv ancement of principles can point to a problem in historically popular) models that were a field, t hen sociolog y inev itably plays a the existing theory, and a scale at inspired by naturalness. It is therefore cent ral role in deciding what quest ions which the theory should change, but an ideal time to explore naturalness are most pressing. The good news they don’t tell you precisely how the arguments more deeply. The last is that the scales often tip, and data problem is resolved. The naturalness of It appears few years have seen an explosion of either clarify the situation or pose new the neutral kaon mass splitting, or the more useful orig inal ideas, but we’re really only at questions. As a field we need to focus charged-neutral pion mass splitting, to think of t he beg inning of t he process. on lucidly ar t iculat ing t he case for suggests to me that it is more useful naturalness The sit uat ion is analogous to (and ag ainst) nat uralness as a g uiding to refer to naturalness as a strategy, the search for dark matter, where principle, and let t he newer generat ions rat her t han as a principle. as a strategy, g rav itat ional ev idence is accumulat ing make up their minds for themselves. A slight ly more flippant e xample rather than as at an impressive rate despite numerous is the observation of neutrinos from a principle null results in direct-detection Interview by Matthew Chalmers editor.

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Looking beyond our OPINION solar system with ray REVIEWS tracing simulation...

Astronomers detected an Earth-like planet 11 How beaut y leads physics astray light-years away from our solar system. How?

Through data from an échelle spectrograph called iStock/francescoch HARPS, which finds exoplanets by detecting tiny Lost in Math – How beauty wobbles in the motion of stars. Engineers looking leads physics astray Recirc-cryo-IOP 8/9/18 5:40 PM Page 1 to further the search for Earth-mass exoplanets By Sabine Hossenfelder can use ray tracing simulation to improve the sensitivity of échelle spectrographs. Basic Books

The COMSOL Multiphysics® software is used In Lost in Math, theoretical physicist for simulating designs, devices, and processes Sabine Hossenfelder embarks on a in all fields of engineering, manufacturing, and soul-searching journey across contem- scientific research. See how you can apply it to porary theoretical particle physics. She Visualization of ray travels to various countries to interview spectrography. trajectories in a white pupil some of the most influential figures of échelle spectrograph. the field (but also some “outcasts”) to comsol.blog/echelle-spectrographs challenge them, and be challenged, about the role of beauty in the investigation of nature’s laws. Colliding head-on with the lore of the fie l d a n d w it h pr a c t ic a l l y a l l p o p u l a r-s ci- ence literature, Hossenfelder argues that beauty is overrated. Some leading scientists say that their favourite theories are too beautiful not to be true, or possess such a rich mathematical structure that it would be a pity if nature did not abide by those rules. Hossenfelder retorts that and achieved striking successes by fol- The eye of the and the Planck mass should be equally Recirculating Cryocooler physics is not mathematics, and names lowing its guidance; however, they also beholder Is the l i k e l y. “W h y,” s h e a s k s, “a r e w e a s s u m i n g examples of extremely beautiful and rich had, as Hossenfelder points out, several beauty of science a flat probability, instead of a logarith- Eliminates the use of LHe for maths that does not describe the world. spectacular failures that are less well overrated? mic (or whatever other function) one?” “Wet” Systems She reminds us that physics is based on known. Moreover, a theoretical sense of In general, we say that a new theory is data. So, she wonders, what can be done beauty is far from universal. Copernicus necessary when a parameter value is when an entire field is starved of exper- made a breakthrough because he sought a unlikely, but she argues that we can esti- imental breakthroughs? form of beauty that differed from those of mate the likeliness of that value only his predecessors, making him think out when we have a prior likelihood function, Confirmation bias of the box; and by today’s taste, Kepler’s for which we would need a new theory. Nobel laureate Steven Weinberg, inter- solar system of platonic solids feels silly viewed for this book, argues that experts and repulsive. New angles Existing LHe cooled call “beauty” the experience-based feel- Hossenfelder devotes attention to Hossenfelder illustrates various popular cryostats and probe ing that a theory is on a good track. Hos- a concept that is particularly relevant solutions to this naturalness problem, s t a t i o n s can be senfelder is sceptical that this attitude to contemporary particle physics: the which in essence all try to make small converted to cryogen-free operation with really comes from experience. Maybe “naturalness principle” (see p45). Take values of the Higgs mass much more the addition of an external cryocooler, the most of the people who chose to work in t h e c a s e o f t h e H i g g s m a s s: t h e t e x t b o o k likely than large ones. She also discusses Janis Recirculating Gas Cryocooler (RGC4). t h i s fie l d w e r e a t t r a c t e d t o it, i n t h e fi rst argument is that quantum corrections string theory, as well as multiverse place, because they like mathematics and go wild for the Higgs boson, making any hypotheses and anthropic solutions, Instead of using LHe from a storage symmetries, and would not have worked mass value between zero and the Planck exposing their shortcomings. Some of vessel, the RGC4 delivers a stream of 4K in the field otherwise. We may be victims mass a priori possible; however, its value her criticisms may recall Lee Smolin’s helium to the cryostat or probe station. of confirmation bias: we choose to believe happens to be closer to zero than to the The Trouble with Physics and Peter Woit’s Contact Janis today for more information. that aesthetic sense leads to correct theo- Planck mass by a factor of 1017. Hence, We choose to Not Even Wrong, but Hossenfelder brings ries; hence, we easily recall to memory all most particle physicists argue that there believe that new angles to the discussion. of the correct theories that possess some must be an almost perfect cancellation aesthetic This book comes out at a time when Contact us today: quality of beauty, while we do not pay of corrections, a problem known as the more and more specialists are question- [email protected] equal attention to the counterexamples. “hierarchy problem”. Hossenfelder sense leads ing the validity of naturalness-inspired www.janis.com/RecirculatingCryocooler.aspx Dirac and Einstein, among many, vocally points out that implicit in this simple to correct predictions. Many popular theories www.facebook.com/JanisResearch affirmed beauty as a guiding principle, argument is that all values between zero theories inspired by the naturalness problem

CERN COURIER JANUARY/FEBRUARY 2019 49

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OPINION REVIEWS OPINION REVIEWS

share an empirical consequence: either passionate about. The intended read- little weight, but my gut feeling is that Topological and Non- physics, cosmology and supersym - s y s t e m s: t h e O(3) n o n l i n e a r s i g m a m o d e l they manifest themselves soon in exist- ership ranges from fellow scientists to this direction of investigation, although Topological Solitons in metric theories. and the baby Skyrme model. Part three ing ex periments, or t hey definitely fail the layperson, also including university undeniably crucial, is not comparably Structured in three parts, this book focuses mainly on the solitons in three in solving the problems that they were administrators and science policy mak- “fertile”. On the other hand, Hossen- Scalar Field Theories provides a comprehensive introduction spatial dimensions. Here, the author invented for. ers, as is made explicit in an appendix felder makes it clear that she sees nothing to the description and construction of covers stationary Q-balls and their By Yakov M Shnir Hossenfelder describes in derogatory devoted to practical suggestions for var- scientific in this kind of fertility, and solitons in various models. In the first properties. Then he discusses soliton terms the typical argumentative struc- ious categories of readers. even argues that bibliometric obsessions Cambridge University Press two chapters of part one, the author configurations in the Skyrme model ture of contemporary theory papers that While this book will mostly attract played a big role in creating what she discusses the properties of topolog- (called skyrmions) and the knotted predict new particles “just around the attention for its pars destruens, it also depicts as a gigantic bibliographical bub- In the 19th century, the Scottish engineer ical solitons in the completely inte- solutions of the Faddev–Skyrme model corner”, while explaining why we did contains a pars construens. Hossen- ble. Inspired by that, Hossenfelder also John Scott Russell was the first to observe grable Sine-Gordon model and in the (hopfions). The properties of the related n o t o b s e r v e t h e m y e t. S h e fi n d s t h e s a me felder argues for looking away from the advises learning how to recognise and what he called a “wave of transition” while non-integrable models with polyno- deformed models, such as the Nicole and attitude in what she calls the “di-photon lamppost, both theoretically and exper- mitigate biases, and building a culture watching a boat drawn along a channel mial potentials. Then, in chapter three, the Aratyn–Ferreira–Zimerman model, diarrhoea”, i.e., the prolific reaction of imentally. Having painted naturalness of criticism both in the scientific arena by a pair of horses. This phenomenon is he introduces solitary wave solutions are also summarised. the same theoretical community to a sta- arguments as a red herring that drives and in response to policies that create n o w r e fe r r e d t o a s a s ol it o n a n d d e s c r i b e d of the Korteweg–de Vries equation, Based on the author’s lecture notes tistical fluctuation at a mass of around attention away from the real issues, and short-term incentives, going against m a t h e m a t i c a l l y a s a s t a bl e, n o n- d i s s i p a- which provide an example of non- for a graduate-level course, this book is 750 GeV in the earliest data from the acknowledging throughout the book the idea of exploring less conventional tive wave packet that maintains its shape topological solitons. addressed at graduate students in theo- LHC’s Run 2. that when data offer no guidance there ideas. Regardless of what one may think while propagating at a constant velocity. Part two deals with higher dimen- retical physics and mathematics, as well The author explains complex matters is no other choice than following some about the merits of naturalness or other Solitons emerge in various nonlin- s io n a l n o n l i n e a r t h e or ie s. I n p a r t ic u l a r, as researc hers interested in solitons. at the cutting edge of theoretical phys- non-empirical assessment criteria, she non-empirical criteria, I believe that ear physical systems, from nonlinear t h e pr o p e r t i e s o f s c a l a r s ol it o n c o n fi g u- ics research in a clear way, with original advocates other criteria that deserve these suggestions are uncontroversially optics and condensed matter to nuclear r a t i o n s a r e a n a l y s e d i n t w o 2+1 d i m e n s i o n Virginia Greco CERN. metaphors and appropriate illustrations. better prominence, such as the internal worthy of consideration. With this book, Hossenfelder not only consistency of the theoretical founda- Universal Themes of Bose– lithium-7 and sodium-23 within weeks c o n d e n s a t i o n i s m o d i fie d b y i nt e r a c t i o ns reaches out to the public, but also invites tions of particle physics. Andrea Giammanco UCLouvain, Einstein Condensation of one another. These studies led to the b e t w e e n t h e p a r t i c l e s, a n d t h e c o n c e p t o f it to join a discourse that she is clearly As a non-theorist my opinion carries Louvain-la-Neuve, Belgium. 2001 No b e l P r i z e i n P h y s i c s b e i n g j oi nt l y u n i v e r s a l it y a n d s c a l e i n v a r i a n c e i n c ol d- awarded to Eric Cornell, Wolfgang Ket- atom systems. Part three focuses on active By Nick P Proukakis, David W Snoke E -H O-201809-217-34 T N-PHO CER Amaldi’s last letter to Fermi: know as CERN. He was general secretary and Peter B Littlewood terle and Carl Wieman. research topics in ultracold environments, a monologue of CERN between 1952 and 1954, before This book is a collection of essays including optical lattice experiments, its official foundation in September 1954. Cambridge University Press written by leading experts on various the study of distinct sound velocities in This beautiful monologue is inter- a s p e c t s a n d i n d i ffe r e nt br a n c h e s o f BE C, ultracold atomic gases – which has shaped Theatre, CERN Globe, 11 September 2018 spersed by radio messages from the The study of Bose–Einstein condensa- which is now a broad and interdiscipli- our current understanding of superfluid On the occasion of the 110th anniversary epoch, which announce salient histor- tion (BEC) has undergone an incredible n a r y a r e a o f m o d e r n p h y s i c s. C o m p o s e d helium – and quantum turbulence in of the birth of Italian physicist Edoardo ical facts. These create a factual atmos- e x p a n s io n d u r i n g t h e l a s t 25 y e a r s. B a c k o f fo u r p a r t s, t h e v olu m e s t a r t s w it h t h e atomic condensates. Amaldi (1908–1989), CERN hosted a new phere that becomes less and less tense then, the only experimentally realised h i s t or y o f t h e r a pid d e v e lo p m e nt o f t h i s Part four is dedicated to the study production titled “Amaldi l’italiano, as alerts about the Nazi’s declarations Bose condensate was liquid helium-4, field and then takes the reader through of condensed-matter systems that centodieci e lode!” The title is a play and bombs are replaced by news about w h e r e a s t o d a y t h e p h e n o m e n o n h a s b e e n the most important results. exhibit various features of BEC, while on words concerning the top score at the first women’s vote, the landing of observed in a number of diverse atomic, The second part provides an exten- in part five possible applications of the an Italian university (“110 cum laude”) the first person on the Moon, and dis- o p t i c a l a n d c o n d e n s e d-m a t t e r s y s t e m s. sive over v iew of v ar ious gener a l t hemes study of condensed matter and BEC to and the production is a well-deserved armament movements. The turning point for BEC came in 1995, related to universal features of Bose–Ein- answer questions on astrophysical scales recognition of a self-confessed “ideas Written and directed by Giusy Cafari when three different US groups reported stein condensates, such as the question of are discussed. shaker” who was one of the pioneers Panico and Corrado Calda, the play was the observation of BEC in trapped, weakly w h e t h e r BE C i n v ol v e s s p o nt a n e o u s s y m- in the establishment of CERN, the composed after consulting with Edoar- interacting atomic gases of rubidium-87, m e t r y br e a k i n g, o f h o w t h e id e a l B o s e g a s Virginia Greco CERN. European Space Agency (ESA) and the do’s son, Ugo Amaldi, who was present Italian National Institute for Nuclear for physical laws, Europe sank into racial Ideas shaker at the inaugural performance. The script Zeros of Polynomials many-body problems. author first discusses systems of ordinary Physics (INFN). laws,” he despairs. Indeed, most of his Corrado Calda as is so rich in information that you leave and Solvable Nonlinear Starting from a well-established differential equations (ODEs), including The nostalgic monologue opens with colleagues and friends, including Fermi Edoardo Amaldi. the theatre feeling you now know a lot approac h to solv able dy namical systems second-order ODEs of Newtonian type, Amaldi, played by Corrado Calda, sitting who had a Jewish wife, moved to the about scientific endeavours, mindsets Evolution Equations identification, the author proposes a novel and then moves on to systems of par- at his desk and writing a letter to his US. Left alone in Italy, Amaldi decided and the general zeitgeist of the last cen- algorithm that allows some of the restric- tial differential equations and equations By Francesco Calogero mentor, Enrico Fermi. Set on the last to stop his studies on fission and focus tury. Moreover, the play touches on some tions of this approach to be eliminated and, evolv ing in discrete t ime-steps. day of Amaldi’s life, the play retraces on cosmic rays, a type of research that topics that are still very relevant today, Cambridge University Press thus, identifies more solvable/integrable This book is addressed to both applied s o m e o f h i s s c i e nt i fic, p e r s o n a l a n d his- required less resources and was not including: brain drain, European identity, N-b o d y pr o bl e m s. A f t e r r e p or t i n g t h i s n e w mathematicians and theoretical physicists, torical memories, which pass by while related to military applications. women in science and the use of science This concise book discusses the math- differential algorit hm to evaluate all t he a n d c a n b e u s e d a s a b a s i c t e x t for a t o pi c a l he writes. for military purposes. ematical tools used to model complex z e r o s o f a g e n e r i c p ol y n o m i a l o f a r bit r a r y course for adv anced underg raduates. It begins in 1938 when Amaldi is part Out of the ruins The event was made possible thanks to phenomena via systems of nonlinear d e g r e e, t h e b o o k pr e s e nt s m a n y e x a m pl e s of an enthusiastic group of young scien- After World War II, while in Italy there the initiative of Ugo Amaldi, CERN’s Lucio e q u a t i o n s, w h i c h c a n b e u s e f u l t o d e s c r i b e to show its application and impact. The Virginia Greco CERN. tists, led by Fermi and nicknamed “Via was barely enough money to buy food, the Rossi, the Edoardo Amaldi Association Panisperna boys” (boys from Panisperna US was building state-of-the-art parti- (Fondazione Piacenza e Vigevano, Italy), Road, the location of the Physics Institute cle-physics detectors. Amaldi described and several sponsors. The presentation of the University of Rome). Their dis- his strong temptation to cross the ocean, was introduced by former CERN Direc- coveries on slow neutrons led to Fermi’s and re-join with Fermi. However, he tor-General Luciano Maiani, who was of the CMS collaboration CMS the of

Nobel Prize in Physics that year. decided to stay in war-torn Europe and Edoardo Amaldi’s student, and current benefit the for CERN, 2011 © Then, suddenly, World War II begins help European science grow out of the CERN Director-General Fabiola Gianotti, CERNCOURIER and everything falls apart. Amaldi writes ruins. He worked to achieve his dream of who expressed her gratitude for Amaldi’s The destination for high-energy physics news and jobs about his frustrations to his teacher, “a laboratory independent from military contribution in establishing CERN. who had passed away but is still close organisations, where scientists from all cerncourier.com to him. “While physicists were looking over the world could feel at home” – today Letizia Diamante CERN.

50 CERN COURIER JANUARY/FEBRUARY 2019 CERN COURIER JANUARY/FEBRUARY 2019 51

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fie ld a s a w hole. Big physics A portion of the CMS collaboration in 2017 on the occasion of the collaboration’s 25th anniversary. www.inradoptics.com/products/x-ray-imaging-crystals Advances in particle physics are which mentoring in family-sized group goals are placed above per- to investigate what the community driven by well-defined innova- groups played a big role, emerged sonal ambition. For example, many thinks about individual recognition tions in accelerators, instrumen- spontaneous leaders, some of whom of us spend hundreds of hours in in large collaborations. Following an tation, electronics, computing and went on to head experimental phys- the pit or carry out computing and initial survey addressing leaders of data-analysis techniques. Yet our ics groups, departments and labora- software tasks to make sure our several CERN and CERN-recognised POWERED BY ability to innovate depends strongly t or i e s. M o v i n g i nt o t h e 1990 s, pr oj e c t experiments deliver the best data, experiments, a community-wide on the talents of individuals, and on management and individual recog- even though some of this collective sur vey closed on 26 October with a how we continue to attract and foster nition became even more pertinent. work isn’t always “visible”. How- total of 1347 responses. the best people. It is therefore vital In the experiments at the Large ever, there are increasing challenges that, within today’s ever-growing Electron–Positron collider (LEP), the nowadays, particularly for young Community survey collaborations, individual research- number of physicists, engineers and scientists who need to navigate the Participants expressed opinions on ers feel that their contributions are technicians working together rose by difficulties of balancing their aspi- several statements related to how recognised adequately within the an order of magnitude compared to rations. Larger collaborations mean they perceive systems of recogni- The World’s Most Advanced scient ific communit y at large. the SPS days, with up to 30 partici- there are many more PhD students tion in their collaboration. More than Digital Pulse Processor Looking back to the time before pating institutions and 20 countries and postdocs, while the number of 80% of the participants are involved large accelerators, individual rec- involved in a given experiment. permanent jobs has not increased i n L HC e x p e r i m e nt s a n d r e s e a r c h e r s for high-rate Spectroscopy ognition was not an issue in our To d a y, w it h t h e L HC e x p e r i m e nt s equivalently; hence we also need to from most European countries were field. Take Rutherford’s revolution- providing an even bigger jump in prepare early-career researchers for well represented. Just less than half ary work on the nucleus or, more scale, we must ask ourselves: are a non-academic career. (44%) were per manent staff mem- recently, Cowan and Reines’ dis- w e m a k i n g o u r i m m e n s e s c i e nt i fic To fully exploit the potential of bers at their institute, with the rest • Up to 8 channels covery of the neutrino – there were progress at the expense of individ- large collaborations, we need to comprising around 300 PhD students of simultaneous perhaps a couple of people working ual recognition? bring every single person to max- and 440 postdocs or junior staff. processing in a lab, at most with a technician, imum effectiveness by motivating Participants were asked to indicate yet acknowledgement was at a global Group goals and stimulating individual recog- their level of agreement with a list • Over 3 Mcps s c a l e. T h e r e w a s n o n e e d for pr oj e c t Large collaborations have been very nition and career choices. With this of statements related to individual processed by management; individual recogni- successful, and the discovery of the in mind, in spring 2018 the European recognition. Each answer was quan- tion was spot-on and instinctive. Higgs boson at the LHC had a big Committee for Future Accelerators tified and the score distributions each channel As high-energy physics pro- impact in our community. Today (ECFA) established a working group were compared between groups of

[email protected] gressed, the needs of experiments there are more than 5000 physicists participants, for instance according Tel: +1-510-401-5760 grew. During the 1980s, experiments from institutions in more than 40 Group goals to career position, experiment, col- www.xia.com such as UA1 and UA2 at the Super c o u nt r ie s w or k i n g o n t h e m a i n L HC laboration size, country, age, gender Proton Synchrotron (SPS) involved experiments, and this mammoth a n d d i s c i pl i n e. S o m e i n it i a l fi n d i n g s institutions from around five to eight scale demands a change in the way are placed are listed over the page, while the full countries, setting in motion a “nat- we nurture individual recognition above personal breakdown of results – comprising ural evolution” of individual recog- and careers. In scientific collabo- hundreds of plots – is available at s nition. From those experiments, in rations with a collective mission, ambition https://ecfa.web.cern.ch.

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PEOPLE CAREERS PEOPLE CAREERS

 Conferences: “The collaboration being included as authors on col-  Technical contributions: “I per- tive technical ideas in a new class Appointments guidelines for speakers at conferences laboration-wide publications. The ceive that my technical contributions of public notes. allow me to be creative and demonstrate alphabetic listing of authors is also get adequate recognition in the parti- Moving back to Europe after technologies by the UK’s Science brand reputation and stakeholder my talents.” Overall, participants supported, and at all career stages. cle-physics community.” Hardware Beyond disseminating the results almost 30 years at erkeley, he and Technology Facilities Council engagement for global from the LHCb collaboration agree Participants had divided opinions and software technical work is at of the survey, ECFA will reflect on succeeds Reinhard Brinkmann, (STFC). Taking up the position on corporations. Most recently he more with this statement compared when it came to alternatives. the core of particle-physics exper- how it can help to strengthen the who has been director of the 2 January, the new role comes with to those from CMS and especially iments, yet it remains challenging recognition of individual achieve- accelerator division since July 2007 responsibility for the development ATLAS. For younger participants  Assigned responsibilities: “I to recognise these contributions ments in large collaborations. The and is now, at his own request, of the UK’s national labs and the this sentiment is more pronounced. perceive that profiles of positions with inside, but especially outside, the LHC experiments and other large returning to DESY’s accelerator exploitation of the technologies Respondents affir med t hat confer- responsibility are well known outside collaboration. collaborations have expressed research as a lead scientist. that underpin them. Geddes, who ence talks are an outstanding oppor- the particle-physics community.” The openness to enter a dialogue on the has spent periods at CERN and tunity to demonstrate to the broader further away from the collaboration,  Scientific notes: “Scientific notes topic, and will be invited by ECFA SLAC as a member of the OPAL and community their creativity and sci- the more challenging it becomes on analysis methods, detector and to join a pan-collaboration work- aar collaborations, has worked e nt i fic i n sig ht, a nd a re p erc e ive d to to inform people about the role of physics simulations, novel algorithms, ing group. This will help to relate ES chooses a new director with the STFC for many years, be one of the most important aspects a convener, yet the selection as a software developments, etc, would be observations from the survey to Wim Leemans (above) of erkeley spending time as the director for of verifying the success of a scientist. convenor is perceived to be very valuable for me as a new class of open current practices in the collabora- Lab in the US has been appointed E-Science before becoming the important in verifying the success publications to recognise individual tions, with the aim of keeping par- director of DESY’s accelerator divi- director of STFC’s technology  Publications: “For me it is impor- of a scientist in our field. The major- contributions.” Although partici- t ic l e p h y s ic s fit a n d h e a lt h y t o w a rds sion, eﬀ ective from 1 February. department in 2012. was senior director of corporate tant to be included as an author of ity of the participating early-career pants have very diverse opinions the next generation of experiments. A prominent leader in the devel- communications at Burson– all collaboration-wide papers.” researchers are neutral or do not when it comes to making the inter- opment of plasma accelerators, ew comms chief for ermilab Marsteller in Chicago, prior to Although the effect is less pro- agree with the statement that the nal collaboration notes public, they Archana Sharma CERN and Leemans was previously in charge Fermilab in the US has appointed which he was director of global nounced for participants from very process of selecting conveners is suf- would value the opportunity to Jorgen D’Hondt Vrije Universiteit of the accelerator technology and public-relations professional reputation management for large collaborations, they value fic ie nt l y t r a n s p a r e nt a n d a c c e s s i bl e. write down their novel and crea- Brussel and ECFA chairperson. applied physics division at Geddes to oversee labs Chris Beard (right) as head of its SC Johnson & Son. Fermilab’s erkeley, and head of the ELLA Experimental particle physicist oﬃ ce of communication, starting previous communications Life beyond CERN facility, which has achieved eil eddes (above) has been from 7 January. Beard has more director, Katie Yurkewicz, moved breakthrough results in advanced named executive director for than 20 years of experience in to Argonne National Laboratory What’s your academic highlight my own strengths. I manufacturer of solar systems for laser–plasma acceleration. national laboratories science and managing communications, in 2018. background? worked in London from 2000– markets in Sub-Saharan Africa. I was a technical student on the 2007 as a quantitative analyst and Having participated in workshops, ALEPH experiment at CERN’s hedge-fund manager in several meetings and conferences, I LEP collider in the mid-1990s, organisations, including Merrill had built up quite a network. In and then continued with a PhD Lynch. Then, at the peak of the 2014, along with a friend who on OPAL. It was very much a flat financial boom in the mid-2000s, I’d met whilst studying for the organisation and, despite being I had what you might describe MSc, I co-founded “Bidhaa Sasa” just a student, I felt I was also as a midlife-crisis. I started (“products now” in Swahili) based making a valuable contribution. to think “what is the positive in rural Kenya. Bidhaa Sasa seeks When I left in 1999, not only had social outcome of what I’m to provide services to otherwise I acquired analytical skills but I doing?” So I enrolled for an MSc under-served communities, Experienced UHV Chamber also discovered the importance of in environmental technology at focussing on goods and services Rocio Perez-Ochoa institutional culture. Imperial College London, which that will improve the quality Manufacturing led to a position as a policy analyst of life for rural communities – from Spain has a PhD Why did you leave the field? at the UK Department of Energy particularly for women. What I • Dedicated engineering support in experimental I was looking for some stability, and Climate Change. I found bring to any table are my technical from design to manufacture particle physics and, which I did not think I would find the civil service quite strange in skills – anything that involves if I remained in academia. We contrast to academia because modelling, financial projections, • Approved UHV Process cleaning following a stint in didn’t have social-media networks it is extremely hierarchical and building spreadsheets and European ® quantitative finance, back then, so I relied on email slow, and there is little freedom developing the financial aspect of • 100% FARO Arm Inspection and face-to-face networking to implement what you think a business. and Bakeout with RGA analysis Chamber now runs a company to try and determine what I was is best. But I gained valuable that distributes life- going to do after CERN. I enrolled experience in understanding how What is the most important • Advanced manufacturing Manufacturer improving products in in an evening-class course on government works and I enlarged thing you’ve learned so far? capabilities including Mu-Metal quantitative finance and found my network. There is a huge amount of value in rural Kenya. Rocio is a that the world of finance shares the connections you make, which I and our unique Hydra~Cool™ member of the CERN many similarities with physics How did you get into the world did not realise when I started out. technology Alumni Network: – modelling and simulation for of start-ups? Do not feel shy when you reach example. One thing I enjoyed is the I witnessed a huge amount of out to people for advice, as you https://alumni.cern. sense of competition, although in innovation in clean energies, will be surprised by the kindness the financial sector there is a lot especially in developing of strangers and the extent to more secrecy than in academia. countries, so I started working which people are willing to help. as a freelance adviser, Also take a course or attend a Did the course lead to a job offer? supporting green start-ups in conference in an area of interest, www.lesker.com Not directly, but I received lots of emerging markets: a Colombian speak to people and collect good advice, where to try my luck, reforestation business, a clean- business cards. Use the power of which books to read, and how to energy business in Sri Lanka and a the network!

54 CERN COURIER JANUARY/FEBRUARY 2019 CERN COURIER JANUARY/FEBRUARY 2019 55

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BLUEFORS.COM Ja mes stirling 1953–2018 A key figure in the development of QCD

The eminent theoretical physicist London College T Angus/Imperial James Stirling died on 9 November at his home in Durham, UK, after a short illness. He will be greatly missed, not only by his family but by his many friends and colleagues throughout the particle-physics community. His wide-ranging contributions to the development and application of quantum chromodynamics (QCD) were central in verifying QCD as the correct theory of strong interactions and in computing precise predictions for all types of processes at hadron colliders such as the LHC. James was born in Belfast, Northern Ireland, and educated at Peterhouse at the University of Cambridge, where he obtained his PhD in 1979. After post-doc positions at the University of Washington in Seattle and at Cambridge, he went to CERN, first as a fellow and then as a staff member, leaving in 1986 for a faculty position at Durham James Stirling’s research always focused on confronting theory with experiment. University, where he remained until 2008. At Durham, he played a enological topics. During his gradu- many other important Standard Webber, has been a standard refer- major role in the foundation of the ate studies at Cambridge, in the early Model processes. ence for more than 20 years. university’s Institute for Particle days of QCD, he clarified in detail A f t e r m o v i n g t o D u r h a m i n 1986, James was a humble and modest Physics Phenomenology in 2000, the connection between deep-ine- James formed a long-standing and person but his intellectual brilliance, and served as its first director. He lastic lepton–hadron scattering and successful research collaboration coupled with a very strong work m o v e d t o C a m br i d g e i n 2008 t o t a k e hadron–hadron processes such as w it h A l a n M a r t i n, D i c k R o b e r t s a n d, ethic and exceptional organisational up the Jacksonian Professorship of lepton pair production, which led to later, Robert Thorne. Among other skills, meant that his advisory and Natural Philosophy in the Cavendish h i s l a t e r w or k o n p a r t o n d i s t r i b ut io n projects, they set the standard for administrative services were always Laboratory, becoming head of the functions at Durham. An example determining the quark and gluon in great demand. He was elected a department of physics in 2011. Then, of his pioneering research is the distributions in the proton, which Fellow of the Royal Society in 1999, in 2013, he was appointed to the first computation of the resummed led to the widely used MRS, MRST and in 2006 he received the national newly created position of Provost, transverse momentum distribu- and MSTW parton distribution func- honour CBE presented by the Queen the chief academic officer, at Impe- tion of W and Z bosons in hadron tions. Later, when James returned to for his services to science. Cooling Your rial College, London, from which he collisions at next-to-leading log- Cambridge, he became interested in In addition to the great respect r e t i r e d l a s t A u g u s t, m o v i n g b a c k t o arithmic order, performed with processes in which more than one in which he was held as a scientist, Qubits. Durham, where his retirement was Christine Davies in 1984. Another parton from each colliding hadron James was much loved as a friend, tragically curtailed by illness. is the development of the powerful participates (double parton scatter- colleague and mentor. He treated James was a prolific and metic- helicity amplitude method, coming), bringing a new level of rigour everyone with the same respect, ulous researcher, publishing more pleted with Ronald Kleiss while they to the analysis of such processes. courtesy and attention, whatever than 300 papers, including some were at CERN. This enabled them James had the gift of being able to t h e i r s t a t u s. H i s w a r m t h, k i n d n e s s of the most highly cited in particle to show that the “monojet” events explain complicated concepts and and fundamental humanity made physics. His research, always full seen at the CERN proton–antiproton ideas simply. He was highly sought a deep impression on all who came of insight, focused on the confron- collider, which had been thought to after as a plenary or summary into contact with him. tation of theoretical predictions be a possible signal of new physics, speaker at the major international with experimental results. Over could be explained by vector-boson particle-physics conferences. His Alan Martin Durham University the years, he performed frontier plus jet production. The method has textbook QCD and Collider Physics, and Bryan Webber University research on a vast range of phenom- since facilitated the calculation of written with Keith Ellis and Bryan of Cambridge.

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PEOPLE OBITUARIES PEOPLE OBITUARIES

John Mulvey 1929–2018 positron collider, studying in at the Herceg Novi school in 1968. from an unexpected angle. It was history and religion, and found particular the charm quark and the In his retirement, he wrote a book a sign of brilliance, of true origi- time to get involved in politics and tau lepton. entitled: Differential Manifolds, nality and even of a certain taste local affairs. Promoting science in all its beauty Throughout his career, in par- A Basic Approach for Experimen- for the paradoxical, but it always We will treasure the memories allel with his work at CERN, Paul tal Physicists. He was writing a produced results. Gifted and dar- of our discussions with Paul, an John Mulvey, one of the most Unit Photographic Physics Oxford cathode-ray tube. With his collab- colleagues and former students. managed to continue to collaborate second on the basics of quantum ing in his intellectual pursuits, he exceptional scientist and person. enthusiastic supporters of Euro- orators in Hawaii, he pioneered an Speaking for those who had worked with his French colleagues, often in field t heor y. was also an accomplished skier pean bubble-chamber physics in experiment at Berkeley to detect with him in particle physics, I his spare time. He was passionate When faced with a problem, Paul and mountaineer. Beyond science His colleagues and friends its heyday, died on 10 September. transition radiation from elec- recalled how John devoted his life about astrophysics and was one had the knack of approaching it and sport, Paul was interested in at CERN and beyond. John was brought up in Som- trons passing through foils. His to encouraging and enabling many of the originators of gamma-ray erset in the UK, where he decided success encouraged Bill Willis to people from far and wide to engage astronomy in France through his that he wanted to be a nuclear use the technique to detect J/ψ pro- in unravelling particle science in involvement in the Themistocle physicist. He graduated in phys- duction at the ISR accelerator at all its beauty. experiment, carried out from 1988 ics from Bristol University in 1950, CERN. Throughout his career, John Discovery in our science is to 1994. Later, he participated in and went straight on to study for a encouraged new developments in achieved neither by “prima don- the design of the CAT (Cheren- PT2026 NMR Precision Teslameter PhD, during which he met his wife detectors and accelerator physics nas” working alone nor by groups kov A rray at Themis) gamma-ray Denise while supervising her lab- at CERN and elsewhere. directed from above, but by peo- imaging telescope. oratory work as an undergraduate During the 1980s he began to ple working in dynamic teams Paul was also involved in Reach new heights in chemistry. They married in 1955, take a strong interest in UK science held together through mutual searches for dark matter based on the year after John submitted his policy. He was frustrated by the r e s p e c t a n d c o n fid e n c e – a n d t h a t the gravitational microlensing of thesis, and in 1956 went together cuts to science funding imposed by is where John made his greatest background stars, contributing in magnetic eld to Los Angeles, where John spent the Thatcher government and the contribution. two years as an assistant professor, idea, which was widely discussed, Those who joined the Hydrogen Paul was as making many lifelong friends. On that the government should only Bubble Chamber Particle Physics measurement their return to the UK, John began fund research that had obvious Group at Oxford, those who worked passionate about his 32 year-long career at the Uni- John Mulvey co-ordinated CERN’s economic benefits. He became with him at CERN, those who joined The Metrolab PT2026 sets a new versity of Oxford, where he led the experimental programme in the a founding member of the Save him to found SBS, and many oth- the construction of standard for precision magnetometers. Hydrogen Bubble Chamber Particle mid-1970s. British Science (SBS) society and ers, all know how the trust that Physics Group. spent much of his time lobbying he engendered cemented interna- a detector as he was Leveraging 30 years of expertise building John was always dedicated to his A whole politicians and businessmen. When tional collaborations. about abstract ideas the world’s gold standard magnetometers, work and travelled frequently to he retired from the University of A whole generation of students, it takes magnetic eld measurement to help on experiments and attend generation Oxford physics department in who went on to lead great exper- in mathematical meetings. In 1971 he took a six- of students, 1990, this became a full-time job; iments of their own, refer with new heights: measuring higher elds with month sabbatical in Hawaii, a he set up an SBS office and ran it a ffe c t i o n t o Un c l e Jo h n. I n d e e d, his physics better resolution. memorable experience for the fam- who went on for eight years. (Later SBS became bright eyes and his smile were still ily. For three years, beginning in CaSE, the Campaign for Science shining when I last visited him. 1973, John was co-ordinator of the to lead great and Engineering, as it is today.) In the physics department at to the AGAPE and POINT-AGAPE The PT2026 offers unprecedented exibility experimental programme at CERN. In retirement, John worked on a Oxford there is a room that bears searches conducted at the Pic in the choice of parameters, interfacing An early success at CERN was his experiments of book that sought to illustrate how his name – an unusual honour du Midi and Las Palmas obser- participation in the discovery of research in pursuit of knowledge that acknowledges his role in the v ator ies i n Fr a nce a nd t he C a n a r y and probe placement, as well as greatly the K*(1420) resonance at the Pro- their own, refer had frequently resulted in unfore- achievements of the past 60 years Islands. improved tolerance of inhomogeneous ton Synchrotron. Back at Oxford, with affection seen benefits. and t he affection t hat colleag ues, Upon his return from the US, elds. And with Ethernet & USB interfaces he set up the precision encoding His life was celebrated at a staff and st udents had for him. Paul again joined CERN’s parti- and pattern recognition project, to Uncle John memorial gathering at Wolfson cle-physics programmes – first and LabVIEW software, it ts perfectly into which measured tracks on bub- College in Oxford on 6 October Wade Allison Keble College, LEP and the DELPHI experiment, modern laboratory environments. ble-chamber film with an online by his family and many friends, University of Oxford. where he helped design and build

the complex and innovative RICH le - Photo: Scott Maxwell, Master www.agence-arca.com Paul Baillon 1938–2018 Cherenkov detector. He then joined the CMS experiment at the LHC and made essential contributions Passion across disciplines to the design of the scintillating- crystal electromagnetic calo- Paul Baillon, who was notable for in liquid hydrogen at the 81 cm Paul Baillon was an eclectic physicist. rimeter, in particular the system the sheer variety of his output in Saclay Bubble Chamber. His the- t h a t s t a bi l i s e s t h e c r y s t a l t e m p e r- particle physics and astrophysics, sis, completed in 1965, presented carried out a new analysis looking ature to within a few hundredths

passed away on 2 October at the a new determination of the mass collection Family for baryonium states. of a degree. age of 80. and width of the K meson and In 1966 Paul became a CERN With a solid foundation in clas- Paul was a pioneer in bubble- described new resonances, in staff member. From 1974 to 1982, sical physics and instrumentation, chamber physics. A graduate of particular the first pseudoscalar he took part in experiments at the as well as in mathematics, Paul was Pantone 286 Pantone 032 École Normale Supérieure, he m e s o n i n t h e 1 400–1500 M eV m a s s Proton Synchrotron that focused as passionate about the construc- joined the École Polytechnique region. Paul kept an interest in this on the study of two-body had- tion of a detector as he was about laboratory for his PhD. In 1961 subject because the meson could ronic reactions, and then spent a abstract ideas in mathematical and 1962 he participated in an be interpreted as being made up of period of time at SLAC in the US, p hy s ic s. M a ny s t i l l re m e m b e r, for Magnetic precision has a name www.metrolab.com experiment that recorded 750,000 gluons (a “glueball”), and, 20 years where he participated in the DELCO example, his highly informative s antiproton annihilations at rest after the data was recorded, he even experiment at the PEP electron– class on the use of tensor calculus

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International Nuclear Physics Conference 2019 29 July – 2 August 2019, Scottish Event Campus, Glasgow, UK

The 27th International Nuclear Physics Conference (INPC 2019) will be held in Glasgow, UK, 29 July to 2 August, 2019. Held every three years, INPC is the biggest conference in the world for fundamental nuclear physics, and is A very happy new year from the CERN HR Talent Acquisition team! overseen by the International Union of Pure and Applied Physics (IUPAP). The event in Glasgow follows conferences in Adelaide 2016, Florence 2013 and Vancouver 2010. 2019 will see plenty of new opportunities opening up for students, graduates and The programme will showcase the very latest work across the • Dr Kawtar Hafidi, Argonne National Laboratory, USA whole range of topic areas in nuclear physics, from the study of • Dr Gaute Hagen, Oak Ridge National Laboratory, USA experienced professionals, and http://careers.cern is the place to find them. hadrons to the heaviest nuclei, and the role of nuclear physics • Dr Tetsuo Hatsuda, RIKEN, Japan in our understanding of the universe. It includes a world-class • Dr Arnau Rios Huguet, University of Surrey, UK programme of plenary speakers, a range of parallel sessions Dr Ulli Köster, Institut Laue–Langevin, France with invited and contributed talks, poster sessions, outreach • CERN: the place for a unique work experience. activities, including a public lecture delivered by Professor • Professor Oscar Naviliat-Cuncic, Michigan State University, USA A place like nowhere else on earth. Take part! Jim Al-Khalili and a trade exhibition. There will also be social • Dr Alice Ohlson, University of Heidelberg, Germany activities for informal networking. • Professor Joern Putschke, Wayne State, USA • Professor Craig Roberts, Argonne National Laboratory, USA Plenary speakers • Professor Justin Stevens, College of William and Mary, USA • Professor Ani Aprahamian, Notre Dame University, USA • Professor Toshimi Suda, Tohoku University, Japan • Professor Michael Block, Johannes Gutenberg University • Dr Peter Thirolf, Ludwig Maximilian University, Germany Job Description: Mainz, Germany • Professor Dr Jo Van den Brand, Dutch National Institute • Professor Dr Pierre Capel, Johannes Gutenberg University for Subatomic Physics and VU University Amsterdam, the • Participation in R & D activities on major scientific equipments Mainz, Germany Netherlands in projects related to the ACS activity, in collaboration with Our company: national and international research institutions. • Dr Francesca Cavanna, National Institute for Nuclear • Dr Xiaofei Yang, Peking University, China Based at the heart of the Paris-Saclay Scientific Physics, Italy Cluster, ACS (Accelerators and Cryogenic Systems) is positioned • Management of the Engineers and Technicians of the company Key dates as a specialized engineering company on design and integration of • Interaction with our consultants and industrial partners • Professor Lola Cortina, University of Santiago de accelerators and research instruments based on superconductivity Compostela, Spain Early registration deadline: 1 June 2019 and cryogenic techniques. We offer a wide range of engineering • Development of specifications and technical requirements of • Professor Anna Frebel, MIT, USA services, from technical studies and manufacturing monitoring, to the company’s contracts Registration deadline: 19 July 2019 • Professor Alexandra Gade, Michigan State University, USA prototyping tests on technology platforms. • Definition of the technical strategy for computer simulations • Professor Juan Jose Gomez Cadenas, Donostia International • Definition of company strategy Computer and control Physics Center, Spain technology solutions applied to scientific equipments R&D technical manager • Representation of ACS in instances and Identification of For further information, visit the conference website at http://inpc2019.iopconfs.org • Master degree in Engineering (preferences on Electronics, potential customers Electrotechnics and Computer Sciences) and/or PhD on • Participation in activities developed in connection with Physics. research institutions • Good knowledge of fundamental and applied physics, and some experience on accelerator physics will be an advantage. Mail: [email protected]

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Accelerators | Photon Science | Particle Physics Accelerators | Photon Science | Particle Physics

Deutsches Elektronen-Synchrotron Deutsches Elektronen-Synchrotron A Research Centre of the Helmholtz Association A Research Centre of the Helmholtz Association

Karlsruhe Institute of Technology (KIT) – The Research University in the Helmholtz Association creates and imparts knowledge for For our location in Hamburg we are seeking: The location Hamburg is seeking: the society and the environment. It is our goal to make significant contributions to mastering the global challenges of man- The DFG Research Training Group kind in the fields of energy, mobility, and information. For this, Strong and Weak Interactions - from Hadrons to Dark Matter Laser Development Scientist (f/m/diverse) Scientist (f/m/diverse) ATLAS about 9300 employees of KIT cooperate in a broad range of at the University of Münster, Germany, invites applications for various disciplines in research, academic education and innovation. DESY and future experiments The Department of Physics at KIT, as part of the Physics and PhD Positions DESY is one of the world’s leading research centres for photon science, Mathematics Division, invites applications for a (salary level TV-L E13, 75 %) particle and astroparticle physics as well as accelerator physics. More DESY These fi xed-term positions will start on April 1st, 2019 or later and are than 2400 employees work at our two locations Hamburg and Zeuthen in DESY is one of the world’s leading research centres for photon science, Professorship (W3) available for up to three years. science, technology and administration. particle and astroparticle physics as well as accelerator physics. More in Theoretical Particle Physics The structure of the DFG-funded Research Training Group (Graduierten- DESY’s laser science and technology group is responsible for research, than 2400 employees work at our two locations Hamburg and Zeuthen in at the Institute for Theoretical Physics (successor of Prof. Dr. kolleg) is based on joint education and research of theorists and exper- development and operations of high power femtosecond and picosecond Dieter Zeppenfeld). imentalists in nuclear, particle and astroparticle physics as well as science, technology and administration. lasers for particle accelerators and free electron lasers (FEL). We are KIT provides an excellent environment for research in particle computer scientists and mathematicians (http://www.uni-muenster.de/ The particle physics programme of DESY consists of strong contributions physics. The Institute for Theoretical Physics is part of the KIT Physik.GRK2149). currently developing photocathode Laser systems for the European X-ray Center Elementary Particle and Astroparticle Physics (see free electron Laser and are seeking to employ a self-driven highly motivated to the LHC experiments ATLAS and CMS, the Belle-II Experiment in Japan www.kceta.edu for additional information). KIT hosts the Rese- In strong interactions we aim at precision in experiments and theo- and to the preparation of future experiments. The experimental programme arch Training Group “Particle Physics at Highest Energy and retical predictions. Examples are the transition from the quark gluon Laser scientist or Laser engineer (f/m/diverse) to strengthen our Team. is enhanced by collaboration with a strong theory group. DESY is searching Precision” and the Karlsruhe School of Elementary Particle and plasma into bound hadrons, the parton distributions in cold nuclear an experienced experimental physicist (f/m/diverse), who is interested Astroparticle Physics: Science and Technology (KSETA), which matter or properties of mesons. In weak interactions we investigate The position provides access to an excellent pool of Ph.D. students. more speculative questions beyond the Standard Model, especially l in contributing to the ATLAS experiment at the LHC and to future particle Develop, design and construct high power short pulse Iaser systems We are looking for an outstanding scientist working in the area those related to dark matter and neutrinos. with high stability and reliability for photoelectron guns physics projects at DESY. of particle physics phenomenology, broadly defined. We are particularly interested in a scientist whose research focuses on Applicants with a very good master's degree or diploma in physics l Develop nonlinear frequency conversion to the UV The position collider physics, precision calculations, physics beyond the are expected to submit the usual application documents (curriculum l Develop concepts for spatial and temporal picosecond UV laser pulse Standard Model or flavour physics. The successful applicant is vitae, copies of transcripts and certifi cates) as well as two letters of diagnostics and pulse manipulation Leading role in ATLAS data analysis with focus on measurements expected to play an active role in the Collaborative Research reference and a letter explaining their motivation to join our Research l Participation in ATLAS detector operation or upgrade Participation in the Center“Particle Physics Phenomenology after the Higgs Training Group and their research interests. Interact with laser, controls and accelerator scientists and engineers supervision of students and postdocs Engagement in Research and Design Discovery” and other coordinated research efforts at KIT. The University of Münster is an equal opportunity employer and is com- for Future Experiment(s) The successful candidate will be part of a team of senior scientists mitted to increasing the proportion of women academics. Consequently, Requirements who maintain and develop the research in particle physics at KIT. we actively encourage applications by women. Female candidates with l Master or equivalent in Physics, Electrical engineering or similar The appointed professor is required to teach at all levels of the equivalent qualifi cations and academic achievements will be preferen- Requirements undergraduate and graduate curriculum (eventually in German) discipline, PhD is a plus tially considered within the framework of the legal possibilities. We also l l Experience in ultra fast Iaser research and development with proven PhD in experimental Particle Physics and to supervise bachelor, master and Ph.D. students. welcome applications from candidates with severe disabilities. Disabled l Experience in data analysis and software development A Habilitation degree or equivalent scientific and teaching quali- candidates with equivalent qualifi cations will be preferentially consid- track record fications are required. The employment conditions as outlined in l l ered. Skills in high-power, high-repetition rate fiber laser development Experience in detector operations and/or development Art. 47 LHG (Law of Baden-Württemberg on Universities and l Outstanding teamwork abilities and excellent communication skills and Colleges) shall apply. Applications should be sent by February 15th, 2019 to the beneficial knowledge of English KIT wishes to increase the proportion of female professors and spokesperson of the Research Training Group preferentially by email: l Basic knowledge and experience in opto-mechanical engineering hence, strongly encourages qualified women to apply. Handicap- Prof. Dr. Christian Weinheimer is a plus ped applicants having the same qualification will be preferred. l For further information please contact Prof. Dr. Beate Heinemann (beate. Institut für Kernphysik Working knowledge of electronics, controls and software Engineering Qualified candidates should submit before January 28th, 2019 heinemann@desy.de). Wilhelm-Klemm-Str. 9 l Ability to work independent within a team of scientists and engineers a curriculum vitae, list of publications, as well as research and D-48149 Münster l Please use our online application tool to submit your complete application teaching statements to: Karlsruher Institut für Technologie Ability to communicate effectively in a multilingual, multi-disciplinary email: [email protected] (Motivation letter, a CV which also details your research accomplishments, (KIT), Dekan der KIT-Fakultät für Physik, 76128 Karlsruhe, research environment Germany, preferably by email to [email protected]. a list of your publications, and a 2-3 page statement on future research For further information about this position please contact Prof. Dr. www.uni-muenster.de For further information please contact Dr. Ingmar Hartl plans) and please arrange for at least three letters of reference to be sent Margarete Mühlleitner, email: [email protected]. ([email protected]) to the DESY human resource department ([email protected]), clearly Since 2010, the KIT has been certified as a family-friendly stating your name and the position identifier. university. The position is limited to 2 years. KIT – The Research University in the Helmholtz Association Salary and benefits are commensurate with those of public service Salary and benefits are commensurate with those of public service organisations in Germany. Classification is based upon qualifications organisations in Germany. Classification is based upon qualifications and and assigned duties. Handicapped persons will be given preference assigned duties. Handicapped persons will be given preference to other Graduate Careers to other equally qualified applicants. DESY operates flexible work equally qualified applicants. DESY operates flexible work schemes. DESY March and October 2019 schemes. DESY is an equal opportunity, affirmative action employer is an equal opportunity, affirmative action employer and encourages and encourages applications from women. Vacant positions at DESY applications from women. Vacant positions at DESY are in general open are in general open to part-timework. During each application to part-timework. During each application procedure DESY will assess procedure DESY will assess whether the post can be filled with part- whether the post can be filled with part-time employees. Target the best candidates for time employees. We are looking forward to your application via our application system: your graduate vacancy We are looking forward to your application via our application system: www.desy.de/onlineapplication www.desy.de/onlineapplication Contact Natasha Clarke today to find out Deutsches Elektronen-Synchrotron DESY Discover what’s out there. how to get your vacancy noticed. Deutsches Elektronen-Synchrotron DESY Human Resources Department | Code: FHMA051/2018 Notkestraße 85 | Human Resources Department | Code: FSMA079/2018 22607 Hamburg | 22607 Hamburg Germany GraduateCareers Notkestraße 85 | 22607 Hamburg | 22607 Hamburg Germany Phone: +49 40 8998-3392 E-mail [email protected] Phone: +49 40 8998-3392 http://www.desy.de/career March and October 2019 Tel +44 (0)117 930 1864 http://www.desy.de/career Deadline for applications: 2019/01/31 Target the best candidates for Deadline for applications: 2019/02/12 your graduate vacancy Contact Natasha Clarke today to find out how to get your vacancy noticed. E-mail [email protected] CERNCOURIER Tel +44 (0)117 930 1864 www. V o l u m e 5 9 N u m b e r 1 J a n u ary /F e b r u a r y 2 0 1 9 GraduateCareers March and October 2019

Target the best candidates for your graduate vacancy Contact Natasha Clarke today to find out how to get your vacancy noticed. E-mail [email protected] Tel +44 (0)117 930 1864 CERNCOURIER.COM

The ELI (Extreme Light Infrastructure) Project is an integral part of the European plan to build the next generation of large research facilities. ELI-Beamlines as a cutting edge laser facility is currently being constructed near Pague, Czech Republic. ELI will be delivering ultra-short, ultra-intense laser pulses lasting typically a few tens of femtoseconds with peak power projected to reach 10 PW. It will make available time IHEP RECRUITMENT OF synchronized laser beams over a wide range of intensities for multi-disciplinary applications in physics, medicine, biology, material science etc. The high intensities of the laser pulse will be also used for generating secondary sources OVERSEAS HIGH-LEVEL TALENTS of e- and p+ and high-energy photons. Our research groups are expanding and recruiting physicists and engineers. INSTITUTE OF HIGH ENERGY PHYSICS, In our team we therefore have the following positions available: CHINESE ACADEMY OF SCIENCES • Junior Researchers • Postdoc/Senior Researchers • Control Systems Specialist • LabVIEW Software Developer • Instrumental Scientist

For more information see our website www.eli-beams.eu The future is in laser technologies and send your application, please.

The Institute of High Energy Physics (IHEP) of the Chinese Academy of Sciences (CAS) invites applications for permanent staff positions at all levels. IHEP is a comprehensive research laboratory for particle and astroparticle physics, accelerator physics and technology, radiation technologies and applications, as well as for nuclear analytical techniques and interdisciplinary research. For More Information: http://english.ihep.cas.cn/

Laser Engineer (Ref LE14) Recruitment Objectives: Technical Director The expansion of our product range and continuing growth of our company have created an opportunity for a self-motivated, innovative individual to join our Based on the needs of the research areas and the disciplines development of IHEP, we are now publicly Laser and Optics Group designing and developing Solid-State and CO2 lasers, and associated systems. recruiting overseas outstanding talents and scholars of relevant disciplines who possess research abilities and innovation awareness. The European Spallation Source (ESS) in Lund, Sweden, is a Who is Rofin-Sinar UK? Featuring: partnership of 13 European countries, hosted by Sweden and • We’re an innovative market leaderTHE in the developmentENGINEERING of world class Programs: Denmark. Our vision is to build and operate the world’s most industrial laser products • We take pride in having a collaborativeSKILLS approach with AND all our customers and powerful neutron source, addressing some of the most important partners 1 National “Thousand Talents Program” (full time & part time programs) for established scientists societal challenges of our time. • Our lasers drive future innovations in INNOVATIONa range of industries 20 & 21 April 2018 CONFERENCE 2 National “Thousand Young Talents Program” for outstanding junior scientists ESS nowNEC, invites applications Birmingham for the position Technical Director. What about you? Are you... 3 Pioneer “Hundred Talents Program” of CAS for outstanding junior scientists, excellent junior detector or • ESS’s Technical Directorate is responsible for delivery, • Qualified to graduate level or above having undertaken studies in Optics and accelerator experts commissioning and operations of the ESS Accelerator, Photonics and/or have professional experience in Optics and Photonics • Willing to grow and learn 4 “Outstanding Talents Program” of IHEP for scientific research or technical talents Target and Integrated Control Systems. The Directorate is • Flexible, and enjoy the challenge of developing real-life solutions today also managing the ESS Engineering and Integration FAST-TRACK It would be an added advantage if you: Support division. We are looking for an experienced leader Research Areas: providing inspirational Leadership and management of the • Have experience of RF matching networks, opto- mechanical design and Q-switching Experimental Particle and Nuclear Physics, Theoretical Physics, Astronomy and Astrophysics, Nuclear Technology, ESS Technical Directorate as the organization transitions from YOUR CAREER • Have an appreciation of mechanical and electronics construction to commissioning and operations. engineering Accelerators, Neutron physics, Condensed matter physics, Chemistry, Biochemistry and Molecular Biology, Book FREE tickets at Biophysics, Computing, Multidisciplinary Research. The Technical Director reports directly to the Director General. What we offer at Rofin-Sinar UK The TechnicalEngineerJobs.co.uk Director will be a member of the Executive • Dual career structure into either engineering/ Management Team that secures the success of ESS as a world management Contact: leading research facility. • Stimulating and satisfying environment for personal Office of Human Resources, Institute of High Energy Physics, Chinese Academy of Sciences 100s of vacancies with companies including*: growth & career development At ESS we offer people with talent and passion a unique opportunity • Competitive salary and excellent benefits package Your E-mail: [email protected] Tel: (86)010-88233157 Fax: (86)010-88233102 to be involved in developing, building, and operating a world-leading success at Rofin-Sinar UK will be the result of your drive facility for materials research. You will also enjoy being part of a and ambition. For more company information visit Address: No. 19 (B), Yuquan Road, Shijingshan District, Beijing (Postcode: 100049) www.rofin-sinar.uk company culture that promotes collaboration and achievement. Applications should include a CV, an outline of academic accomplishments, description of current research and plan For more information regarding the ESS recruitment process, please Interested? look at https://europeanspallationsource.se/ess-recruitment-process Apply in writing quoting the reference above, with a full for future research, 3 – 5 published papers representative of your work, and a record of citations for your work. You CV to: Submit your application as soon as possible, as we will review Personnel Department, Rofin-Sinar UK Ltd., should arrange for 3 letters of reference from experts in your field to be sent by post or email (established scientists Follow us #NECR18 In association with: Meadow Road,Supported Bridgehead by: Business Park, applications@engineerjobs_uk continuously, latest by February 15th, 2019 are not requested). Kingston upon Hull, HU13 0DG [email protected] *All information correct at time of press or e-mail For detailed information, please visit http://english.ihep.cas.cn/doc/2649.html 70 Physics World March 2018

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Notes and observations from the high-energy physics community HEP comes out on top From the archive: February 1976 People and things High-energy physics (HEP) RE-EARTH-BASED HIGH TEMPERATURE Professor Werner Heisenberg died on 140 ranks top for productivity and impact, according to a study of 1 Febr uar y 1976. One of t he g reat fig ures in CERN348.10.71 100 the subfields of 135,877 physicists physics, he was amongst the most active SUPERCONDUCTORS carried out by researchers at

impact and influential scientists who worked for 60 Cent ral European Universit y in the creation of CERN. Born in 1901, in his 20s 20 Budapest. In HEP (red line) the Heisenberg participated in the glorious days average impact, defined as t he of the evolution of quantum theory, his 1985 1990 1995 2000 2005 2010 number of citations per author year na me i m mor t a l ly l i n ked to t he “Uncer t a i nt y within a five-year window, shows OUTSTANDING PERFORMANCE FOR DEMANDING APPLICATIONS Principle”, formulated in 1926. It brought exceptional growth compared to other physics subfields such as him the Nobel Prize for Physics in 1932. condensed-matter (light blue) and “astro” (pink). Divide the number of paper citations by team size to capture the “fractional” impact, Heisenberg’s involvement in t he affairs of CERN beg an as a however, and HEP fares worse than most, displaying a downward deleg ate of t he Feder al Republ ic of Ger many at t he for mat ive meet ing SUPERIOR IN-FIELD CRITICAL CURRENT trend during the past decade. Overall, concludes the team, the amount in 1951; in 1952 he sig ned t he Ag reement establ ishing CERN in t he of knowledge produced per capita has decreased in all subfields name of t he Ger man gover nment. He cont inued to g ive his t ime and despite the increase in the total number of physicists and physics abil it ies to CERN, as deleg ate to CERN Council (to 1963) and a member papers (Nat. Rev. Phys. 1 89). of the Scientific Policy Committee (to 1961). His last official EXCELLENT MECHANICAL PROPERTIES appear ance at CERN w as in October 1971 when he inaug ur ated t he Intersecting Storage Rings (photo above). Anomaly watch  Compiled from text on p59 of CERN Courier Febr uar y 1976. EXTREMELY UNIFORM CRITICAL CURRENT First t here w as t he loose coa x ial cable t hat led physicists to t hin k neut rinos t ravel faster B physics goes south LNGS-INFN t han light. Then t here w as t he cosmic dust that duped researchers into thinking they MANUFACTURED USING OPTIMISED IBAD AND PLD PROCESSES had detected primordial B-modes, t he smok ing g un of inflat ion. Could t he mundane 6% be about to scupper a third major claim, this time concerning dark matter, before the VOLUME PRODUCTION AVAILABLE NOW. decade is over? The ult rapure sodium-iodide scint illators of t he DA M A Percentage experiment at Gran Sasso National Laboratory (pictured) have of the LHC’s long recorded highly sig nificant seasonal v ariat ions in t he event total expected rate, consistent w it h Ear t h mov ing relat ive to a halo of dark mat ter sur rounding t he M il k y Way. But Daniel Ferenc of t he Universit y dataset of Cali for nia Dav is and co-workers reason t hat t he probable collected cause of t he DA M A anomaly is t he mig rat ion of helium t hrough so far photomultiplier tubes in the detectors. This, they say, could produce accidental coincidences of inflated “dark noise” w avefor ms t hat mimic scint illat ion events at just t he right rate to e x plain t he DA M A anomaly (arXiv:1901.02139).

Media corner following the nation’s “Because the Standard Model n a Cow Greig landing of a craft on the has gone from success to “Just as it meant something Moon (print edition, success, and the quanta from beyond the world of particle 12 January). which the Higgs condensate is physics when America made were at last detected, we The theme of the famous “penguin” diagram, cancelled its proposed “My advice is to try crazy are amply entitled to conclude responsible for rare flavour-changing giant SSC and CERN’s LHC ideas and innovative that we live inside an exotic processes and so-named by John Ellis in 1977 became the biggest game experiments. Something (electroweak) superconductor.” following a lost bet over a game of darts, was in town, so it would mean will come up.” Frank Wilczek writing about last year turned into a word cloud in which something if China took Steven Weinberg on the the evolving unity of physics the size of each word represents the frequency CERN’s crown.” challenges facing today’s in the inaugural issue of of its appearance on the public LHCb web page The Economist assesses researchers in APS Physics Nature Reviews Physics – offering a guide as to what’s, err, hot on the China’s scientific ambitions (Physics 11 134). (Nat. Rev. Phys. 1 5). flavour-physics scene.

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