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CERNMay/June 2021 cerncourier.com COURIERReporting on international high-energy WELCOME CERN Courier – digital edition Welcome to the digital edition of the May/June 2021 issue of CERN Courier. g–2 In April, a keenly awaited measurement from strengthened the longstanding tension between the measured and predicted values of the MEASUREMENT OF THE MOMENT muon’s anomalous magnetic moment, generating media coverage worldwide (p7). now look forward to further data (p49) and to a deeper understanding of the tricky QCD calculations (p25) before weighing up possible signs of new physics.

Meanwhile, in March, a new LHCb measurement of a parameter called RK, which compares the rate of certain B- decays to and , reinforces hints that -flavour universality may be violated in the B sector (p17).

Also generating headlines this spring were the discovery of the odderon 50 years after its prediction (p8), and the demonstration of laser-cooled antihydrogen by the ALPHA collaboration (p9).

Elsewhere in this issue: upgrades to the beam-intercepting devices at the heart of CERN’s accelerator complex (p38); ALICE makes strides towards understanding the extreme conditions of the early universe (p31); news from Moriond (p21); careers advice from accelerator Suzie Sheehy (p52); assessing the economic impact of physics (p55); and much more.

To sign up to the new-issue alert, please visit: http://comms.iop.org/k/iop/cerncourier

To subscribe to the magazine, please visit: https://cerncourier.com/p/about-cern-courier Laser-cooled antihydrogen Flavour anomalies back in the spotlight Odderon finally discovered

EDITOR: MATTHEW CHALMERS, CERN DIGITAL EDITION CREATED BY IOP PUBLISHING

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IN THIS ISSUE V o l u m e 61 N u m b e r 3 m a y /J u N e 2 02 1

MMS MUSIC/arXiv:1209.6330 O-202010-134-24 T N-PHO CER Sheehy S THE UNIVERSAL SYSTEM FOR A LARGE RANGE OF LOW AND HIGH VOLTAGE MULTICHANNEL POWER SUPPLIES

MMS MMS HV LV compatible compatible Go with the flow How heav y s flow within Luminous future Upgrades to CERN’s Balancing act Suzie Sheehy on life cooling droplets of quark– plasma. 31 beam-intercepting devices. 38 as a researcher and communicator. 51

NeWS PeoPle

ANALYSIS ENERGY FRONTIERS FIELD NOTES CAREERS OBITUARIES Fermilab on muon g–2 Flavour Anomalies intrigue at Harnessing the • Samoil Bilenky • Odderon discovered strengthened Moriond • NeuTel as CERN model • Arnulfo Zepeda W-IE-NE-R + ISEG SUPPORT OFFICE AT CERN • Laser-cooled • under vibrant as ever Paul Lecoq’s 50-year Domínguez • Roger antihydrogen • New the microscope • LHC reinterpreters career illustrates the Phillips Pierluigi Riboni Dr. Dipl.-Phys. Erich Schaefer • • ADS linac • Beauty-strange think long-term. 21 power of CERN in • Harold Ticho • Philip Bat.: 13/R-023 • Support for Lebanon observed • Light neutral fostering international Karl Williams • Roland +41 75411 4301 • Challenging DAMA. 7 probed. 17 collaboration. 59 Windmolders. 69 [email protected] FeaTureS MSU photo archive photo MSU MUON g–2 ALICE SYSTEMS FACILITIES HIGH CLASS EBS HV BOARDS Anomalous moment Going with the flow Intercepting Physics flies CONTROLLER BOARDS WITH LINUX INSIDE LOW VOLTAGE BOARDS Bipolar 4 quadrant high voltage for the muon The ALICE experiment is the beams high at SINP Integrated EPICS IOC, SNMP, OPC-UA Up to 16 channel LV for on site module with CFG. EBS perfectly The calculations needed making strides towards Major upgrades to dumps, Surveying the past, and Webservices, also „bare metal“ use. frontend hardware supply saves covers requirements of to resolve whether new understanding the collimators and targets present and future of Now with onboard Python script runtime. cable and installation space. optical systems or capacitive loads. physics is the source of extreme conditions of are under way to prepare Russia’s Skobeltsyn the reinforced muon the early universe. 31 for the high-luminosity Institute of Nuclear g–2 anomaly. 25 LHC and beyond. 38 Physics. 45

Up to 10 slots and 480 channels per crate oPINIoN DeParTmeNTS Highest channel density to save valueable installation space COMMENT INTERVIEW REVIEWS FROM THE EDITOR 5 Best ripple and noise characteristics Muon g–2: the promise Making a difference Calculating the NEWS DIGEST 15 of a generation Accelerator physicist curiosity windfall Arnold/FermilabC APPOINTMENTS 61 Up to 30 kV, up to 100 W per channel Perseverance and tight Suzie Sheehy discusses The economics of big & AWARDS collaboration are essential how to increase science Lectures on • RECRUITMENT 63 Pure LV compatible, pure HV compatible and mixed setup crates available for progress, write the appeal of a accelerator physics On the cover: Inside the Themis Bowcock and research career. 51 • A day with . 55 storage ring of Fermilab’s BACKGROUND 74 Interchangeable controller boards for networking and software control Mark Lancaster. 49 muon g–2 experiment. 25

CERN COURIER MAY/JUNE 2021 3 WWW.WIENER-D.COM | WWW.ISEG-HV.COM/MMS

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Muons making headlines

ver since it turned up unexpectedly in cosmic rays 85 years M Rayner/CERN ago, the muon has been a source of intrigue, famously Eprompting to exclaim “Who ordered that?” Similar to the electron in all but mass, it was the harbinger of a second generation of and arguably marked the beginning of modern . Two results reported in this issue show that interest in the muon is far from over. Matthew Keenly awaited measurements of the muon’s anomalous mag- Chalmers netic moment announced by Fermilab on 7 April (p7) reinforce Editor the anomaly reported by a previous experiment at Brookhaven 20 years ago. Currently, theory and experiment, both known to a precision of better than one part per million, stand 4.2σ Freewheelin’ Artistic sketch of muons (blue) interacting with a apart. Meanwhile, a new LHCb measurement of a parameter magnetic field (purple), including “g–2” contributions, which are

called RK, which compares the rate of certain B-meson decays to the subject of intense theoretical efforts (p25). muons and to electrons, strengthens hints that lepton-flavour

universality (LFU) is violated in the B sector (p17). The latest RK Fermilab is at the very beginning of a campaign that will result lies 3.1σ f r o m t h e St a n d a rd M o d e l, c o n s t it ut i n g t h e fi r s t ultimately reduce the muon g–2 uncertainty by a factor of at s i n g l e-m e a s u r e m e nt “e v i d e n c e” for L F U v i ol a t i o n, a n d fit t i n g least three, while a completely independent measurement is a pat ter n of flavour anomalies seen by LHCb in recent years. expected from J-PARC in Japan. If something is indeed going Given the many channels studied in particle physics, 3σ on with the muon’s g-factor, it will only be natural that interest IPAC 21 effects come and go all the time. There is also noa priori rea- in a wider muon experimental programme is heightened. This son to expect these particular departures from the Standard includes Mu2e at Fermilab, Mu3e and muEDM at PSI, and COMET

May 24 – 28, 2021 Model. The RK anomaly involves a change of quark flavour at J-PARC. A proposed experiment at CERN – where the first g-2 whereas g–2 doesn’t, note theorists, and there is no truly measurements were made 60 years ago (p49) – called MUonE model-independent connection between them. Scalar lepto- aims to precisely determine the leading hadronic contribution and new gauge forces have been invoked to explain the to the g–2 measurement, while theoretical calculations relevant a n o m a l ie s, a n d f u r t h e r s uc h e ffor t s, r e q u i r i n g v a r y i n g fe at s to muon g–2 are an exciting work in progress (p25). of acrobatics, are sure to be uploaded to the arXiv preprint Regarding the flavour anomalies, for which the accom- server in the coming weeks and months. panying theoretical calculations are comparatively much

cleaner, new LHCb measurements of RK-related observables Early days are in development, with LHC Run 3 to bring further statistical Clearly it is far too soon to tell if something is amiss with power. The recently started Belle II experiment at SuperKEKB Clearly it is far the muon. But the fact that both anomalies are in the muon in Japan is also building up a dataset that will provide a crucial too soon to tell sector, and that fresh data have caused them to grow rather independent check of the LHCb results in the coming years, than fade, has generated a buzz in the community, and seen while CMS and ATLAS are poised to contribute. if something Vacuum solutions particle physicists’ Twitter channels trend with the hashtag One way or another, the current picture should start to come is amiss with #CautiouslyExcited. The good news is that more measure- into focus towards the middle of the decade, around the time the muon ments are on the way. when decisions about the next major collider could be taken.

from a single source Reporting on international high-energy physics CERN Courier is distributed Editor Laboratory correspondents Jefferson Laboratory SLAC National Technical illustrator General distribution to governments, institutes Matthew Chalmers Argonne National Kandice Carter Accelerator Laboratory Alison Tovey Courrier Adressage, CERN, Pfei er Vacuum is proud to have been a supplier of innovative and customized vacuum solutions to the particle accelerator and laboratories affiliated Associate editor Laboratory JINR Dubna B Starchenko Melinda Baker Advertising sales 1211 Geneva 23, Switzerland; with CERN, and to Mark Rayner Tom LeCompte KEK National Laboratory SNOLAB Samantha Kuula Tom Houlden e-mail courrier- community for more than 50 years. Our complete product portfolio for vacuum technology, our focus on competent and individual subscribers. Editorial assistant Brookhaven National Hajime Hikino TRIUMF Laboratory Recruitment sales adressage@.ch specialized advice supported by robust and reliable service, makes Pfei er Vacuum the partner of choice for the analytical It is published six times Craig Edwards Laboratory Achim Franz Lawrence Berkeley Marcello Pavan Chris Thomas per year. The views Archive contributor Laboratory Spencer Klein Advertisement Published by CERN, 1211 and research communities worldwide. expressed are not Peggie Rimmer D G Cassel Los Alamos National Lab Produced for CERN by production Katie Graham Geneva 23, Switzerland necessarily those of the Astrowatch contributor DESY Laboratory Rajan Gupta IOP Publishing Ltd Marketing and Tel +41 (0) 22 767 61 11 CERN management. Merlin Kole Till Mundzeck NCSL Ken Kingery Temple Circus, Temple circulation Laura Gillham, ■ Pumps for vacuum generation down to UHV E-mail Fermilab Kurt Nikhef Robert Fleischer Way, Bristol BS1 6HG, UK Jessica Pratten Printed by Warners ■ Vacuum measurement and analysis equipment [email protected] Riesselmann Novosibirsk Institute Tel +44 (0)117 929 7481 (Midlands) plc, Bourne, Forschungszentrum S Eidelman Advertising Lincolnshire, UK ■ Leak detectors and integrity test systems Advisory board Jülich Markus Buescher Orsay Laboratory Head of Media Jo Allen Tel +44 (0)117 930 1026 ■ Chambers, components and valves , Christine GSI Darmstadt I Peter Anne-Marie Lutz Head of Media (for UK/Europe display © 2021 CERN Sutton, Claude Amsler, IHEP, Beijing Lijun Guo PSI Laboratory P-R Kettle Business Development advertising) or +44 (0)117 ISSN 0304-288X ■ Pumping stations and customized solutions Philippe Bloch, Roger IHEP, Serpukhov Saclay Laboratory Ed Jost 930 1164 (for recruitment Forty, Mike Lamont, Yu Ryabov Elisabeth Locci Content and production advertising); e-mail Joachim Kopp INFN Antonella Varaschin UK STFC Jane Binks manager Ruth Leopold [email protected] Are you looking for a perfect vacuum solution? Please contact us: Pfeiffer Vacuum (Schweiz) AG · T +41 44 444 22 55 · F +41 44 444 22 66 · [email protected] www.pfeiffer-vacuum.com CERN COURIER MAY/JUNE 2021 5

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SearcheS for new phySicS Fermilab strengthens muon g–2 anomaly R Hahn/Fermilab Hotly anticipated results from the first Polly, a co-spokesperson for the current run of the muon g–2 experiment at experiment and a graduate student on the Fermilab were announced on 7 April, Brookhaven experiment. “Although these increasing the tension between measure- first results are telling us that there is an ments and theoretical calculations. The i nt r i g u i n g d i ffe r e n c e w it h t h e St a n d ard last time this ultra-precise measurement Model, we will learn much more in the was performed, at Brookhaven National next couple of years.” Laboratory 20 years ago, it disagreed with the (SM) by 3.7σ. After Theory baseline almost eight years of work rebuilding the Developments in the theory commu- Brookhaven experiment at Fermilab and nity are equally vital (p25). The Fermi- a n a l y s i n g it s fi r s t d a t a, t h e m u o n’s a nom- lab muon g–2 collaboration takes as its alous magnetic moment has been meas- theory baseline the value obtained last ured to be 116592040(54) × 10–11. The result year by the Muon g–2 Theory Initiative. is in agreement with the Brookhaven Uncertainties in the calculation are measurement and is 3.3σ greater than dominated by hadronic contributions, the SM prediction: 116591810(43) × 10–11. in particular a term called the hadronic Combined with the Brookhaven result, vacuum polarisation (HVP). The Theory the world-average value for the anom- Initiative incorporates the HVP value alous magnetic moment of the muon is Momentary laps to deliver a purer muon beam, thereby obtained by well-established “dispersive 116592061(41) × 10–11, representing a 4.2σ The 14 m-diameter suppressing the contamination methods”, which combine fundamental departure from the SM. muon g–2 ring in that challenged the Brookhaven meas- properties of with “Today is an extraordinary day, long its detector hall urement, Fermilab’s muon g–2 set up experimental measurements of low- awaited not only by us but by the whole at Fermilab. required entirely new instrumentation energy hadronic processes. An alterna- international physics community,” says and calibration systems, along with new tive approach gaining traction is to cal- Graziano Venanzoni of the INFN, who is detectors and a control room. culate the HVP contribution using lattice co-spokesperson of the Fermilab muon When a muon travels in a strong QCD. In a paper published in Nature on the g–2 collaboration. external magnetic field, the direction same day as the Fermilab announcement, The Fermilab result was unblinded of its magnetic moment precesses at one group reported a lattice HVP calcu- during a Zoom meeting on 25 February in a rate that depends on its strength, g. lation with a much reduced uncertainty the presence of 200 collaborators. It was The predicts that fermi- that is in 2σ tension with the dispersive an emotional moment, says Venanzoni. ons have a g-factor equal to two. But approach; if adopted, it would substan- The analysis took almost three years from higher order loops add an “anomalous” tially reduce the tension with experi-

data taking to the release of the result, moment, aμ = (g–2)/2, which can be cal- mental measurements. and the collaboration decided to unblind culated extremely precisely. At Fermilab, “Given the complexity of the compu- only when all the steps were completed muons with an energy of about 3.1 GeV tations, independent results from differ- and there were no outstanding questions. are vertically focused in the storage ring ent lattice groups with commensurate via quadrupoles, and their precession uncertainties are needed to test and Experiment reincarnated frequency is determined from decays check the lattice calculations against The previous Brookhaven measurement to electrons using 24 electromagnetic each other,” read a statement from the left physicists pondering whether the calorimeters located along the ring’s Muon g–2 Theory Initiative steering presence of unknown particles in loops inner circumference. The collaboration committee. “Being entirely based on could be affecting the muon’s behaviour. took it s first dat aset i n 2018, w it h more Standard Model theory, once the lat- It was clear that further measurements than eight billion muon decays result- tice results are well tested and precise were needed, and in the summer of 2013 ing in an overall uncertainty approxi- enough, they will play an important t h e e x p e r i m e nt’s 1 4 m-diameter, 1.45 T mately 15% better than Brookhaven’s. role in understanding how new physics superconducting magnet was trans- Data analysis on the second and third enters into the discrepancy.” ported from Brookhaven to Fermilab to runs is already under way, while a fourth build a re incarnated muon g–2 experi- run is ongoing and a fifth is planned. Further reading ment. The Fermilab team reassembled The collaboration is targeting a final T Aoyama et al. 2020 Phys. Rept. 887 1. the magnet and spent a year “shim- precision of around 0.14 ppm. S Borsanyi et al. 2021 Nature ming” its field, making it three times “So far we have analysed less than doi:10.1038/s41586-021-03418-1. more uniform than the one it created at 6% of the data that the experiment will Muon g–2 Collaboration 2021 Phys. Rev. Brookhaven. Along with a new beamline e v e nt u a l l y c ol l e c t,” s a i d Fe r m i l a b’s C h r i s Lett. 126 141801.

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NEWS ANALYSIS NEWS ANALYSIS

Strong interactionS A ntim Atter Elusive odderon finally discovered Laser-cooled antihydrogen takes ALPHA into new realm After many years of research and Source: behaviour of antihydrogen in Earth’s rieCRNPOTO-201609-210-4 T N-PHO ice/CER Br M

The TOTEM collaboration at the LHC, development, the ALPHA collaboration 1.0 Nature gravitational field, the kinetic energy cooling

along with the DØ collaboration at the has succeeded in laser-cooling antihy- of the antiatoms must be lowered. no cooling 592 former Tevatron collider at Fermilab, drogen – opening the door to consid- 0.8 35 In their new study, the ALPHA have announced the discovery of the erably more precise measurements of researchers were able to laser-cool a odderon – an elusive odd-numbered antihydrogen’s internal structure and sample of magnetically trapped anti- gluon state predicted almost 50 years gravitational interactions. The seminal 0.6 hydrogen by repeatedly driving ago. The result was presented on 5 March result, reported on 31 March in Nature, the antiatoms from the 1S to the 2P state during the LHC Forward Physics meeting could also lead to the creation of anti- 0.4 using a pulsed laser with a frequency at CERN, and follows the joint publication and the development slightly below that of the transition of a CERN/Fermilab preprint by TOTEM of antiatom interferometry, explains between them. After illuminating the and DØ reporting the observation in ALPHA spokesperson Jeffrey Hangst. 0.2 trapped antiatoms for several hours,

December 2020. “T h i s i s b y f a r t h e m o s t d i ffic u l t e x p eri- normalised signal (arbitrary units) the researchers observed a more than “This result probes the deepest features ment we have ever done,” he says. “We’re 10-fold decrease in their median kinetic of , notably over the moon. About a decade ago, laser 0 energy, with many of the antiatoms that interact between themselves cooling of antimatter was in the realm –200 –100 0 100 200 attaining energies below 1 μeV. Subse- and that an odd number of gluons are of science fict ion.” relative laser frequency at 243.1 nm (kHz) quent spectroscopic measurements of able to be ‘colourless’, thus shielding The ALPHA collaboration synthesises the 1S–2S transition revealed that the the ,” says TOTEM antihydrogen from cryogenic plasmas Slimming down Antihydrogen’s 1S–2S spectral line measured cooling resulted in a spectral line about spokesperson Simone Giani of CERN. “A of and at CERN’s with (grey) and without (red) the application of laser cooling. The four times narrower than that observed notable feature of this work is that the Excavating odderons Part of the TOTEM installation in the LHC tunnel 220 m downstream from Decelerator (AD), storing the narrowing occurs because the colder atoms spend more time in the without laser cooling – a proof-of-prin- results are produced by joining the LHC the CMS experiment. antiatoms in a magnetic trap. Lasers laser field each time they pass through the beam, reducing the ciple of the laser-cooling technique, with a n d Te v a t r o n d a t a a t d i ffe r e nt e n e r g i e s.” with particular frequencies are then so-called transit-time broadening. Using thousands of trapped further statistics needed to improve the States comprising two, three or more energies has long been explained by the fi r s t e x p e r i m e nt a l o b s e r v a t i o n o f t heod- used to measure the antiatoms’ spectral antihydrogen atoms, ALPHA is now able to record such a spectral line precision of the previous 1S–2S measure- gluons are termed “”, and are exchange of a – a colour-neutral eron,” said Christophe Royon of University response. Finding any slight difference in a single day; the equivalent result from 2017 (see text) took 10 weeks. ment (see fig ure). peculiar objects made only of the car- virtual made up of two gluons. of Kansas, who presented the results on between spectral transitions in antimat- “Historically, researchers have strug- riers of the strong force. The idea for However, in 2018 TOTEM reported behalf of DØ and TOTEM in March. “This ter and matter would challenge charge– AD’s scientific programme. The following gled to laser-cool normal hydrogen, so the odderon was introduced in 1973 in measurements at high energies that is a major discovery by CERN/Fermilab.” –time symmetry, and perhaps cast year, the team determined antihydro- this has been a bit of a crazy dream for us the framework of “Regge theory”, and could not easily be explained by this tra- In addition to the new TOTEM–DØ light on the cosmological imbalance of gen’s 1S–2P “Lyman–alpha” transition for many years,” says Makoto Fujiwara, was named two years later in a paper by ditional picture. Instead, a further QCD model-independent study, several matter and antimatter. with a precision of a few parts in a hun- who proposed the use of a pulsed laser Joynson, Leader, Nicolescu and Lopez. object with an odd charge-congugation theoretical papers based on data from Following the first antihydrogen dred million, showing that it agrees to cool trapped antihydrogen in ALPHA. With the advent of quantum chromody- quantum number C seemed to be at play, the ISR, SPS, Tevatron and LHC, and spectroscopy by ALPHA in 2012, in 2017 with the prediction for the equivalent “Now, we can dream of even crazier namics (QCD), the existence of the odd- supporting models in which a glueball model-dependent inputs, provide addi- the collaboration measured the spec- transition hydrogen to a precision of things with antimatter.” eron as a kind of virtual glueball became a containing at least three gluons was tional evidence supporting the conclusion tral structure of the antihydrogen 1S–2S 5 × 10–8. However, to push the precision fi r m pr e d ic t io n. B ut pr o v i n g it s e x i s t e n ce being exchanged. The discrepancy came that the odderon exists. transition with an outstanding precision of spectroscopic measurements further, Further reading has been a major experimental challenge, to light via measurements of a parameter “The independent experimental of 2 × 10–12 – marking a milestone in the and to allow future measurements of the The ALPHA Collaboration 2021 Nature 592 35. requiring detailed measurements of called ρ, which represents the ratio of evidence in the measurements of the LHCb collaboration as they glance off one another the real and imaginary parts of the for- ρ parameter and differential elastic spectroscopy Horizontal and vertical bands indicate the in high-energy collisions. ward elastic-scattering amplitude when cross section make it likely that we are LHCb observes four 18 LHCb 20 temporary production of reso- there is minimal momentum exchange indeed seeing signals of the odderon nances, which subsequently decay to a J/ψ 9 fb–1 Deviation measurement between the colliding protons and thus here,” says theorist Carlo Ewerz of GSI meson and a K+ meson or a J/ψ meson and new tetraquarks 17 While most high-energy collisions cause almost no deviation in their trajectories. Helmholtz Centre for Heavy Ion Research 16 a φ meson, respectively. The most prom-

protons to break into their constituent T h e 2018 r e s u l t s w e r e s u ffic i e nt t o c l a im and Heidelberg University in Germany. The LHCb collaboration has added four ) inent vertical bands correspond to four 2 16 quarks and gluons, roughly 25% are elas- evidence for the odderon, although not “In these cases the odderon is only one new exotic particles to the growing list of 12 cc–ss– t e t r a q u a r k s t h a t w e r e fi r s t o b s e r v e d

tic collisions where the protons remain yet its definit ive obser v at ion. among several contributions, and a very discovered so far at the LHC. In a + in June 2016. The collaboration has now K 15 (GeV

intact but emerge on slightly different The new work is based on a model- small one, so it is very impressive that paper posted to the arXiv preprint server J/ ψ resolved two new horizontal bands cor- 2 8 paths (deviating by around a millime- independent analysis of data at medium- the TOTEM and DØ collaborations could on 2 March, the collaboration reports the m responding to the cc–us– states, and two tre over a distance of 200 m at the LHC). range momenta transfer. The TOTEM and finally isolate an odderon signal in these observation of two tetraquarks with a 14 additional vertical bands corresponding TOTEM measures these small deviations DØ teams compared LHC pp data (recorded challenging measurements. Dedicated new quark content (cc–us–): a narrow one, 4 to the cc–ss– states. + + in –proton (pp) scattering using at collision energies of 2.76, 7, 8 and 13 TeV s e a r c h e s for o d d e r o n e ffe c t s i n e x c lu s i ve Zcs(4000) , and a broader one Zcs(4220) . 13 The results have already triggered two detectors located 220 m on either and extrapolated to 1.96 TeV), with Teva- processes at the LHC and at the future Two other new tetraquarks, X(4685) and 0 theoretical head scratching. In Novem- – side of the CMS experiment, while DØ tron pp data measured at 1.96 TeV. The odd- Electron-Ion Collider will be crucial X(4630), with a quark content cc–ss–, were 18 20 22 ber, the BESIII collaboration at the Beijing employed a similar setup at the Tevatron eron would be expected to contribute with in order to determine its properties in also observed. The results, which emerged 2 2 Electron– Collider II reported mJ/ ψφ (GeV ) proton–antiproton (pp–) collider. different signs to pp and –pp scattering. detail and thus to understand why it had thanks to adding the statistical power from the discovery of the first candidate for At low energies, differences in pp vs Supporting this picture, the two data sets escaped detection for almost 50 years.” LHC Run 2 to previous datasets, follow four Mountain ridges A Dalitz plot of 24,000 B+ → J/ψφK+ decays, a charged hidden-charm tetraquark – pp scattering are due to the exchange of disagree at the 3.4σ level, providing evi- This is a tetraquarks discovered by the collabora- where vertical and horizontal bands reveal the presence of with strangeness, tentatively dubbed – virtual mesons. At multi-TeV energies, dence for the t-channel exchange of a col- Further reading tion in 2016 and provide grist for the mill intermediate particles. Zcs(3985) . It is unclear whether the new major + on the other hand, proton interactions ourless, C-odd gluonic compound. “When DØ and TOTEM Collaborations 2020 of theorists seeking to explain the nature Zcs(4000) tetraquark can be identified are expected to be mediated purely by combined with the ρ and total cross-sec- discovery arXiv:2012.03981. of tetraquark binding mechanisms. B+ → J/ψφK+ decays, which, as a three- with this state, say physicists. Though gluons. In particular, elastic scattering tion result at 13 TeV, t he sig n ificance is in by CERN/ TOTEM Collab. 2019 Eur. Phys. J. C 79 785. The new exotic states were observed body decay, may be visualised using a their masses are consistent, the width of s at low-momentum transfer and high the range 5.2–5.7σ and thus constitutes the Fermilab D Joynson et al. 1975 Nuovo Cimento A 30 345. in an almost pure sample of 24,000 D a l it z pl o t (s e e “M o u nt a i n r i d g e s” fi g u r e). the BESIII particle is 10 times smaller.

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“These states may have very diff erent LCbC Acceler Ators inner structures, sas lead analst 11000 χb(3P) χb2(3P) Liing hang of the LCb collabora- 10500 χ (3P) High-power linac shows promise for ADS technology b1 tion “The one seen b SIII is a narrow * + IMP and longer-lived particle, and is easier to + Bc(2S) Tcccc– – Physicists at the Institute of Modern module, but the team faced difficulties 7000 Bc(2S) + Bc(2S) – understand with a nuclear-lie hadronic 0 Ωb(6350) Physics (IMP) in Lanzhou, China, have i n r e a c h i n g t h e d e s i g n g o a l s. C h a l l e n g e s Λb(6152) – – 0 Ωb(6340) 0 olecular picture, where two hadrons Ξb(6227) Λb(6146) Ξb(6227) a c h i e v e d a s i g n i fic a nt m i l e s t o n e t o w a r ds i n c lu d i n g b e a m-l o s s c o nt r ol a n d d e t e c- *0 0 *– +,0 – Ξb Λb(5920) Ξb BJ(5970) Ξ (6100) 6000 +,0 b interact via a residual strong force The Λ (5912)0 ʹ– B (5840) + 0 0 an accelerator-driven sub-critical sys- tion, heavy beam loading and rapid fault b Ξb J ∑b(6097) Λb(6070) Bs(6114) – 0 one we observed is uch broader, which ∑b(6097) Bs(6063) tem – a proposed technology for sus- recover y were finally overcome in early would ae it ore natural to interpret tainable fission energy. In February the 2021, enabling the 38 m-long facility to 5000 – as a copact ultiquar candidate bb + X(4685) i n s t it ut e’s pr o t o t y p e f r o nt- e n d l i n a c for achieve its design performance at the mass (MeV) P (4450) X(4700) + bq– C Pc(4457) X(4630) The new observations tae the tall of X(4500) P (4440)+ the China Accelerator Driven Subcritical start of the Chinese new year. CAFe’s – – X(4140) c + cc(qq) + X(4274) + Zcs(4220) new hadronic states discovered at the LC – – PC(4380) Pc(4312) + System (C-ADS) reached its design goal beam availability during long-term, 4000 cccc Zcs(4000) which includes several pentaquars as – ++ X(3842) with the successful commissioning of high-power operation was measured to cq Ξcc – – * +, 0 well as rare and ecited esons and bar- cqqq Dj(3000) 0 a 10 mA, 205 kW continuous-wave (CW) be 93–96%, indicating high reliability: 0 Ωc(3119) D (3000) 0 0 bqq j D* (2860)+ Ωc(3090) Ξ (2939) ons to see “Diagra of discover + s1 + 0 c X1(2900) proton beam at an energy of 20 MeV. The 12 hours of operation at 174 kW/10 m A a n d 3000 D*(2760) Λc(2860) Ω (3066) cqq j c 0 X0(2900) 0 * 0 Ω (3050) 0 fi g u r e). T h o u g h q u a nt u m c h r o m o d y n a m- – Dj(2740) D (2760) c Ξc(2923) result breaks the world record for a high- 108 hours at 126 kW/7.3 mA. ccqqq 0 3 Ω (3000)0 D (2590)+ ics naturall allows the eistence of states Dj(2580) c s0 power CW superconducting linac, says T h e f u l l C-A DS pr oj e c t i s e x p e c t e d t o b e beond conventional two- and three- 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 Yu a n He, d i r e c t or o f I M P’s L i n a c C e nt e r: c o m pl e t e d t h i s d e c a d e. A s i m i l a r pr oj e c t quar esons and barons, the detailed date “This result consists of 10 years of hard metal spallation target. Such a system On track The CAFe called MYRRHA is under way at SCK CEN echaniss responsible for binding work by IMP scientists, and brings the could run on non-fissile thorium fuel, proton linac in i n B e l g iu m, t h e f r o nt- e n d l i n a c for w h ic h ulti-quar states are still largel ste- Diagram of iscoery The ATLA, C and LCb collaborations hae discoered new hadronic states so far. realisation of an actual ADS facility one which is more abundant than uranium China, which r e c e nt l y e nt e r e d c o n s t r u c t io n. O t h e r A DS rious Tetraquars, for eaple, could be step closer to the world.” a n d pr o d u c e s l e s s w a s t e. T h e c h a l l e n g e i s reached its design projects are under study in Japan, India tightl bound pairs of diquars or loosel an eotic hadrons sas forer LCb needed to understand, for instance, the The ADS concept, which was proposed to design an accelerator with the required performance in and other countries. bound esoneson olecules or even phsics coordinator Patric Koppenburg, anoalies we see in -eson decas by at CERN in late 1990s, beam power and long-term reliability, early 2021. “CAFe is the world’s first CW super- both, depending on the production process who put the plot together “I hope that offer s a p ote nt i a l te c h nolog y for nuc le- for which a superconducting proton linac conducting proton linac stepping into the CERN Courier Sept/Oct 2020 p25). the bring us to a better odelling of the urther reaing ar-waste transmutation and the develop- is a promising candidate. hundred-kilowatt level,” says He. “The “W h o w o u l d h a v e g u e s s e d w e’d fi n d s o strong interaction, which is ver uch LCb Collab 1 ariv:11 ment of safe, sustainable nuclear power. In 2011 a team at IMP launched a successful operation of the 10 mA beam T h e i d e a i s t o s u s t a i n fi s s i o n r e a c t i o n s i n programme to build a superconduct- meets t he beam-intensit y requirement a subcritical reactor core with ing proton linac (named CAFe) with an for a n e x p e r i m e nt a l A DS d e m o f a c i l it y – a generated by directing a high-energy unprecedented 10 mA beam current. It br e a k t h r o u g h for A DS l i n a c d e v e l o p m e nt proton or electron beam, which can be was upgraded in 2018 by replacing the and an outstanding achievement in the switched on or off at will, at a heavy- radio-frequency quadrupole and a cryo- accelerator field.”

HIGH VOLTAGE computing POWER SUPPLIES CMS seeks support for Lebanese colleagues MAGNET POWER SUPPLIES The CMS collaboration, in partner- centre to the analysis of CMS data, is

ship with the Geneva-based Sharing M Alali particularly at risk. HPC4L was due to Knowledge Foundation, has launched benefit from servers donated by CERN HIGH CURRENT a fundraising initiative to support the to Lebanon, and from the transfer of POWER SUPPLIES L e b a ne s e s c ie nt i fic c om mu n it y du r i n g C E R N a n d C M S k n o w l e d g e a n d e x p e r t i s e an especially difficult period. Lebanon to train a dedicated support team that signed an international cooperation w i l l r u n a h i g h-p e r for m a n c e c o m p ut i n g HIGH PRECISION agreement with CERN in 2016, which f a c i l it y t h e r e. B ut t h e h a rd w a r e h a s b e e n POWER SUPPLIES triggered a strong development of the u n a bl e t o b e s h i p p e d f r o m C E R N b e c a u s e country’s contributions to CERN pro- of a lac k of av a i lable f und i ng. C M S a nd jects, particularly to the CMS experi- the Sharing Knowledge Foundation are POWER SUPPLIES FOR BASIC RESEARCH ment through the affiliation of four of its therefore fundraising to cover the ship- t o p u n i v e r s it i e s. Ye t t h e c o u nt r y i s d e a l- ping costs of the donated hardware, to AT THE HIGHEST LEVEL ing with an unprecedented economic purchase hardware to allow its instal- Heinzinger has played a role in research for a very long time crisis, food shortages, Syrian refugees lation, and to support Lebanese experts thanks to its expertise and passion. In addition to the European and the COVID-19 pandemic, all in the while they are trained at CERN by the CERN facility in Geneva, companies, universities, colleges and aftermath of the Beirut port explosion CMS offline computing team. state institutions are investing in research. Whether it be testing in Aug ust 2020. “A t t h i s pi v o t a l m o m e nt, e v e r y e ffor t and measuring equipment, accelerator technology or HV pow- “Even the most resilient higher- to help Lebanon counts,” says Gastal. er supplies for particle detectors: High-specification technical education institutions in Lebanon Strong ties Young Lebanese scientists at CERN. “CMS is reaching out for donations to are struggling to survive,” says CMS support this initiative, to help both the equipment from Heinzinger helps to produce reliable and resilient Rosenheim (Germany) 4 I 83026 GmbH I Anton-Jakob-Str. Heinzinger electronic I www.heinzinger.com 2458 0 I email: info @heinzinger.de +49 8031 P: results in laboratories and testing centers all over the world. collaborator Martin Gastal of CERN, CMS, but it needs support.” L eba nese resea rc h com mun it y a nd t he who initiated the fundraising activity One project, High-Performance country itself.” in March. “Despite these challenges, Computing for Lebanon (HPC4L), which z More information, including how t h e L e b a n e s e s c i e nt i fic c o m m u n it y h as w a s i n it i a t e d t o b u i l d L e b a n o n’s r e s e a r c h to get involved, can be found at: r e a ffi r m e d it s c o m m it m e nt t o C E R N and capac it y wh i le cont r ibut i ng as a Tier-2 cern.ch/fundraiser-lebanon.

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NEWS ANALYSIS

AstrowAtch ANAIS challenges DAMA dark-matter claim ANAIS Source: arXiv:2103.01175 0.02

DAMA/LIBRA result 0.01 ANAIS-112 best fit

1σ sensitivity 0 exposure 3.0 y 2σ sensitivity exposure 3.0 y –0.01 3σ sensitivity exposure 3.0 y modulation amplitude (cpd/kg/keV)

–0.02 [1–6] keV [2–6] keV

Still in the dark Photomultiplier tubes for ANAIS inside their shielding blocks and (right) a comparison between the ANAIS and DAMA/LIBRA results.

Despite the strong indirect evidence for this method has advantages compared The ANAIS 99% confidence. The results therefore the existence of , a plethora to more direct detection methods, it results also narrow down the possible causes of the of direct searches have not resulted in a requires that other potential sources of agree with the modulation observed by DAMA to either positive detection. The exception to this such a seasonal modulation be ruled out. differences in the detector compared first results are the famous results from the DAMA/ D e s pit e t h e s i g n i fic a nt m o d u l a t i o n w it h to ANAIS, or in the analysis method. NaI experiment at Gran Sasso under- the correct phase observed by DAMA, its published One specific issue raised by the ANAIS ground laboratory in , first reported results were not immediately accepted as by the collaboration regards the background- in the late 1990s, which show a mod- a clear signal of dark matter due to the COSINE-100 subtraction method. In the DAMA results ulating signal compatible with Earth remaining possibility of instrumental collaboration the mean background rate for each year moving through a region containing effects, seasonal bac kg round modula- is subtracted from the raw data for that weakly interacting massive particles tion or artifacts from the analysis. full year. In case the background dur- (WIMPs). These results were backed-up ing that year is not constant, however, more recently with measurements from Controlling the data this will produce an artificial saw-tooth the follow-up DAMA/LIBRA detector. Over the years the significance of the shape which, with the limited statis- Combining the data in 2018, the evi- DAMA results has continued to increase t i c s, c a n b e fit t e d w it h a s i nu s oi d a l. T his dence reported for a dark-matter signal while other dark-matter searches, e ffe c t w a s a l r e a d y p oi nt e d o ut i n a pub - is as high as 13σ. Now, the Annual mod- in particular with the XENON1T and lication by a group from INFN in 2020, ulation with NaI Scintillators (ANAIS) LUX experiments, found no evidence which showed how a slowly increasing collaboration, which aims to directly of WIMPs capable of explaining the background is capable of producing the reproduce the DAMA results using the DAMA results. The fact that only the exact modulation observed by DAMA. same detector concept, has published final analysis products from DAMA have The ANAIS collaboration describes their the results from their first three years been made public has also hampered background in detail, shows that it is of operations. The results, which were attempts to prove or disprove alternative indeed not constant, and provides sug- presented at Rencontres de Moriond, origins of the modulation. To overcome gestions for a more robust handling of show a clear contradiction with DAMA, this, the ANAIS collaboration set out to the background. indicating that we are still no closer to reproduce the data with an independent The ANAIS results also agree with finding dark mat ter. detector intentionally similar to DAMA, the first results published by the The DAMA results are based on consisting of NaI(Tl) scintillators read COSINE-100 collaboration in 2019 which, searches for an annual modulation in out by photomultipliers placed in the again using a NaI-based detector, found the interaction rate of WIMPs in a detec- Canfranc Underground Laboratory deep no evidence of a yearly modulation. tor comprising NaI crystals. First the- beneath the Pyrenees in northern Spain. Thanks to the continued experimental oretically proposed in 1986 by Andrzej Using this method ANAIS can rule out e ffor t s o f t h e s e t w o g r o u p s, a n d w it hte Drukier, Katherine Freese and David any instrument-induced effects while ANAIS collaboration planning to make Spergel, this modulation is a result of producing data in a controlled way their data public to allow independent t he d i fference i n velo c it y of E a r t h w it h and studying it in detail with different analyses, the more than 20 year-old respect to the dark-matter halo of the analy sis procedures. DAMA anomaly looks likely to be set- galaxy. On 2 June the velocities of Earth The first three years of ANAIS data tled in the next few years. and the Sun are aligned with respect have now been unblinded, and the results to the galaxy, whereas half a year later were posted on arXiv on 1 March. None Further reading they are oppositely aligned, resulting of the analysis methods used show any J Amaré et al. 2021 arXiv:2103.01175. in a lower cross section for WIMPs with signs of a modulation, with a statistical D Buttazzo et al. 2020 JHEP 04 137. a detector placed on Earth. Although analysis ruling out the DAMA results at COSINE-100 Collab. 2018 Nature 564 83.

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IceCube sees Glashow resonance Muon detection in cargo quarks. The Japan-based team In 1960 Sheldon Glashow A team headed by Francesco directed a beam of K mesons predicted that a then-unknown R igg i at t he Universit y of into a diamond target to produce – – EHT Collaboration W could be resonantly Catania has developed a new Ξ (dss) hy perons whic h t hen produced by a high-energy way to detect nuclear materials traversed a stack of photographic electron antineutrino interacting in cargo ships using cosmic sheets, extracting an event with an atomic electron (Phys. muons. Muon tomography is named “IBUKI” for a Honshu Rev. 118 316). Glashow could not a well-documented technique mountain (image below), where have imagined that this particle, t hat offers a promising w ay to a briefly bonded with discovered at CERN in 1983, would detect the presence of hidden a nitrogen nucleus to create a M87 in polarised light. have a mass of 80 GeV, and require quantities of dense materials doubly strange hypernucleus. a with an energy of inside large volumes. Since The team determined that Polarisation at the event horizon 6.3 PeV to be produced on-shell in cosmic muons are relatively rare, Ξ bind to nitrogen

Two years after intriguing the an interaction with an electron at however, long scanning times are ion at labor Col E07 RC J-PA world with an intensity map of rest. The IceCube collaboration, required. R igg i and collaborators light from the massive object which operates an enormous developed a full-scale muon at the centre of the supergiant detector encased in Antarctic tomograph prototype with a galaxy M87, the Event Horizon ice, has now uncovered one such sensing area of 18 m2 and used it Telescope collaboration has added event in data from 2016 – one to inspect a full-scale container polarisation information to the of only three to be in whic h a 0.004 m2 lead block image (see fig ure). It is t he first detected with an energy in excess was placed. A multi-parametric time astronomers have been of 5 PeV (Nature 591 220). “POC A” analysis of incoming and

able to measure polarisation this IceCube outgoing muon tracks allowed a close to the edge of a black hole real-time analysis of the collected (ApJL 910 L12). Only t heoret ical events, showing promise for The “IBUKI” event. models featuring light emission practical applications, says the by strongly magnetised gas can team (EPJ Plus 136 139). nuclei with an energy of about explain observations at the event 1.27 MeV, li kely cor responding to horizon, notes a separate theory Antimatter on the move a nuclear 1p state, in agreement paper by the collaboration (ApJL In Marc h, CERN approved with predictions (Phys. Rev. Lett. 910 L13). To st udy its primar y the development of two new 126 062501). In a separate result, targets – M87 and Sagittarius A*, experiments to transport the team observed the same the much smaller black hole at antiprotons from CERN’s hypernucleus decaying into two the centre of the Milky Way – the Antimatter Factory to other 5He hypernuclei with a binding collaboration must wait for good facilit ies. BASE-STEP, a v ariant of energ y of 6.27 MeV, cor responding weather at eight telescopes around the BASE experiment, will feature to the more strongly bound 1s the world, and then mail the hard The Glashow “Hydrangea” event. t wo Penning t raps to receive state (arXiv:2103.08793). drives to analysis locat ions. and release antiprotons and has Gender irrelevant in physics tests been designed to be carried to a Quasi-Majorana claim retracted Baikal–GVD launched A team of education researchers facilit y at CERN or elsewhere to The authors of a 2018 Nature In Marc h researc hers in Russia and physicists from the allow higher-precision antiproton article have retracted their claim inaugurated the Baikal Deep University of Texas and Texas measurements. PUMA will to have observed “quantised Underwater Neutrino Telescope A&M University report that t ranspor t ant iprotons to CERN’s Majorana conductance” – a sign (Bai kal–GV D) – a k m 3-scale gender is not a strong factor nuclear-physics facility ISOLDE, of superconductor analogues to facility situated up to 1.3 k m below leading to differences in student for the investigation of exotic Majorana fermions that have Lake Baikal, the largest freshwater performance. The 12-year nuclear-physics phenomena. It potential applications in quantum la ke in t he world. When complete, study of algebra- and calculus- w ill consist of a first t rapping zone computing (Nature 591 E30). A f ter it will contain 20 detector clusters based classical mechanics and to stop antiprotons, and a second inconsistencies in the original each comprising 288 (36 × 8 strings) electromagnetism courses looked trapping zone to host collisions analysis were pointed out, the glass spheres housing photo- for discrepancies between the between the antiprotons and authors reanalysed their results multiplier tubes. With eight exam performance of male and radioactive atomic nuclei that are and established that the data clusters installed so far, the female physics students. A few rout inely produced at ISOLDE but in t wo of t heir fig ures had been facilit y is 40% complete. A lready differences were seen, such as decay too rapidly to be transported unnecessarily corrected for charge the largest neutrino telescope in women outperforming men in anywhere themselves. jumps, invalidating their original the Northern Hemisphere, algebra-based mechanics, but claim. The ret ract ion does not Baikal–GVD will search for the effects are small, and at most Doubly strange hypernucleus seen inv alidate prev ious findings t hat high-energy cosmic neutrinos weakly dependent on gender, J-PA RC’s E07 collaborat ion excitations with the properties by detecting Cherenkov light write the authors (Phys. Rev. Phys. has detected a short-lived of Majorana fermions exist in generated by t heir interact ions. Educ. Res. 17 010106). nucleus containing two strange condensed-matter systems.

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Reports from the experiments LHCb

New data strengthens RK flavour anomaly

The principle that the charged LHCb have identical strengths is a distinctive feature of the Standard Model (SM). However, this lepton-flavour universality (LFU) is an accidental symmetry in the SM, which may not hold in theories beyond the SM (CERN Courier May/June 2019 p33). The LHCb collaboration has used a number of rare decays mediated by flavour-changing neutral currents, where the SM contribution is suppressed, to test for deviations from LFU. Dur- ing the past few years, these and other measurements, together with results from B-factories, hint at possible depar- tures from the SM. In a new measurement of a LFU-

sensitive parameter “RK” with increased precision and statistical power, reported at the Rencontres de Moriond, LHCb has strengthened the significance of the Sensitive test The decay of a B0 meson to a K*0 and an electron–positron pair.

flavour anomalies. The value RK probes LHCb the ratio of B-meson decays to muons set. The RK ratio is measured to be + + + – and electrons: RK = BR(B → K μ μ )/ three standard deviations from the SM BR(B+ → K+e+e–). Testing LFU in such BaBar prediction (see figure 1). This is the 2 2 b → sℓ+ℓ– transitions has the advantage 0.1 < q < 8.12 GeV first time that a departure from LFU that not only are SM contributions sup- Belle above this level has been seen in any 2 2 pressed, but the theoretical predictions 1.0 < q < 6.0 GeV individual B-meson decay, with a value +0.042 +0.013 –1 are very precise. Therefore, any signif- LHCb 3 fb of RK = 0.846–0.039 (stat.) –0.012 (syst.). 2 2 icant deviation of RK from unity would 1.0 < q < 6.0 GeV Although it is too early to conclude imply physics beyond the SM. LHCb 5 fb–1 anything definitive at this stage, this The experimental challenge lies in 1.1 < q2 < 6.0 GeV2 deviation is consistent with a pattern of the fact that, while electrons and muons LHCb 9 fb–1 anomalies that have manifested them- + – interact via the electroweak force in 1.1 < q2 < 6.0 GeV2 selves in b → s ℓ ℓ and similar processes the same way, the small electron mass over the course of the past decade. In

means that it interacts with detec- 0.5 1 1.5 particular, the strengthening RK anom- tor material much more than muons. aly may be considered alongside hints RK For example, electrons radiate a sig- from other measurements of these tran-

nificant number of bremsstrahlung Fig. 1. Comparison between RK measurements. In addition sitions, including angular asymmetries PUSHING SCIENCE TO ITS LIMITS when traversing the LHCb to the LHCb result, the measurements by the BaBar and Belle and decay rates. + + + – 0 0 + – detector, which degrades reconstruc- collaborations, which combine B → K ℓ ℓ and B → KS ℓ ℓ The LHCb experiment is well placed tion efficiency and signal resolu- decays, are shown. to clarify the potential existence of tion compared to muons. The key to new-physics effects in these decays. 0 0* + – + – control this effect is to use the decays RK and RK* (which probes B → K ℓ ℓ Updates on a suite of b → s ℓ ℓ related + – + – Cosylab is an international academic spin-off that builds and integrates state-of-the J/ψ → e e and J/ψ → μ μ , which are decays) in 2019 and 2017, respectively, measurements with the full Run 1 and art control system solutions for the world’s most complex, precise and advanced known to have the same decay prob- provide hints of deviations from unity Run 2 dataset are underway. A major ability and can be used to calibrate (CERN Courier May/June 2019 p9). The upgrade to the detector during the ongo- systems. By working elbow to elbow with some of the best physicists and laboratories and test electron reconstruction effi- latest analysis of RK, which uses the ing second long shutdown of the LHC around the world, Cosylab has established great partnerships in the scientific ciencies. High precision tests with the full dataset collected by the experiment will offer a step change in precision in community and is an active member of the largest international physics projects J/ψ are compatible with LFU, which in Run 1 and Run 2 of the LHC, represents Run 3 and beyond. provides a powerful cross-check on the a substantial improvement in preci- For more information, please visit cosylab.com or experimental analysis. sion on the previous measurement (see Further reading see our career opportunities on cosylab.com/jobs Previous LHCb measurements of figure 1) thanks to doubling the data- LHCb Collaboration 2021 arXiv:2103.11769.

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ENERGY FRONTIERS ENERGY FRONTIERS

ATLAS and Ξ (5935)– states observed by LHCb the Σ0 → Λ γ decay is too soft to be b CMS 140 fb–1 (13 TeV) are its isospin partner and the beauty reconstructed). 0 − – − – partner of the Ξ c′ , respectively. The Ξb → J/ψΞ , Ξb → J/ψΛK The observation of this baryon and Higgsinos under the microscope charm sector also suggests the existence 20 the measurement of its properties are of prominent heavier isodoublets, called data useful for distinguishing between dif- ** The was hypothesised to supersymmetric electroweak states, they Ξb : the lightest orbital Ξb excitations fit ferent theoretical models predicting the 15 explain electroweak symmetry breaking LSP will decay promptly to the lightest stable with orbital momentum between a light signal excited beauty baryon states. It is curious nearly 50 years before its discovery. Its higgsino and low-energy Standard Model (a pairing of a s quark with either comb. bkg. to note that if the Ξ (6100) – baryon were pp → ~~χ±χ0 , ~~χ0χ0 b eventual discovery at the LHC took half 1 1,2 1 2 particles. These soft decay products are a d or a u quark) and a heavy b quark. The 10 only 13 MeV heavier, a tiny 0.2% change, 0 ± ~χ → tbs, χ~ → bbs – 0 – a century of innovative accelerator and 1,2 1 extremely challenging to detect at the isodoublet with spin-parity 1/2 decays it would be above the Λb K mass thresh- –1 ′ ± – * ± candidates/2 MeV detector development, and extensive data √s = 13 TeV, 139 fb LHC, and ATLAS has performed several into Ξb π and the one with 3/2 into Ξb π . old and could decay to this final state. 4 5 – analysis. Today, several outstanding ques- 10 searches for events with two or three The CMS collaboration has now The Ξb(6100) might also shed light on ATLAS preliminary – tions in particle physics could be answered ) [fb] leptons to maximise the sensitivity to observed such a baryon, Ξb(6100) , via the the nature of previous discoveries: if it 2 0

χ obs. limit – 0 – – 1 by higgsinos – theorised supersymmet- 0 different values of ∆m. Each search fea- decay sequence Ξb(6100) → Ξb(5945) π → 0 is the 3/2 member of the lightest orbital χ ~~ – + – ric partners of an extended Higgs field. , tures innovative optimisation and pow- π π . The new state’s measured mass excitation isodoublet, then the (6227) exp. limit (± 1, 2σexp) Ξb 0 20 40 60 80 100 Ξb 1, 2 0

The higgsinos are a triplet of electroweak χ SUSY erful discriminants to reject background. i s 6100.3 ± 0.6 MeV, and the upper limit − + – − PDG isodoublet recently found by the LHCb 1 ± Higgsino pair prod (± 1σ ) M(Ξb π π ) – M(Ξb) – 2mπ± [MeV]

~~ theory – states, two neutral and one charged. If 103 For t h e fi r s t t i m e, AT L A S h a s p e r for m eda on its natural width is 1.9 MeV at 95% collaboration could be the 3/2 orbital

→ χ – * the lightest neutral state is stable, it can all limits at 95% CL statistical combination of these searches, confidence level. TheΞ b ground state Fig. 1. The reconstructed invariant mass difference distribution excitation of Ξb′ or Ξ b . – + – provide an explanation of astronomically (pp constraining higgsino masses to be larger was reconstructed in two channels: of the selected π π candidates. The observed peak at 24.14 ± σ Ξb – – – observed dark matter. Furthermore, an t han 150 GeV for ∆m above 2 G eV. J/ψ Ξ and J/ψ Λ K . The latter channel 0.22 MeV, with respect to the Ξb and di-pion mass, corresponds to Further reading **– intimate connection between higgsinos A final result targets higgsinos in also includes partially reconstructed a new Ξb particle with a mass of 6100.3 ± 0.6 MeV. The inclusion CMS Collab. 2021 arXiv:2102.04524 0 – and the Higgs boson could explain why the 102 models in which the lightest super- J/ψ Σ K (where the from of charge-conjugated states is implied throughout the text. (submitted to Phys. Rev. Lett.). mass of the Higgs boson is so much lighter symmetric particle is not stable. In than suggested by theoretical arguments. these scenarios, higgsinos may decay ALICE While higgsinos may not be much heav- 200 300 400 to triplets of quarks. A search designed ~0 ier than the Higgs boson, they would be m(χ1) [GeV] around an adversarial neural network pr o d u c e d m or e r a r e l y a n d a r e s i g n i fic a nt l y and employing a completely data-driven Light neutral mesons probed to high pT more challenging to find, especially if Fig. 1. The excluded cross-section of the lightest higgsino as a background estimation technique was they are the only supersymmetric particles function of its hypothetical mass (black), for the case wherein the developed to distinguish these rare Neutral pion (π0) and eta-meson (η) tribution functions (nPDFs). However, near the electroweak scale. lightest higgsino decays to three quarks. The orange line shows the decays from the overwhelming multi-jet production cross sections at midra- pp, √s = 8 TeV, ALICE norm. unc. 2.6% since high parton densities are reached The ATLAS collaboration recently theoretical rate of higgsino production. Higgsino masses between b a c k g r o u n d. T h i s s e a r c h i s t h e fi r s t a t t he pidity have recently been measured up 0 at the LHC, the Colour Glass Condensate 2.0 π , |y| < 0.8 released a set of results based on the full 200 and 320 GeV are ruled out by this search. LHC to obtain sensitivity to this higg- to unprecedentedly high transverse NLO, FF:DSS14 (CGC) framework is also applicable at low LHC Run 2 dataset that explore some of the sino model, and rules out scenarios of the momenta (p ) in proton–proton (pp) and PDF:CT10 p (x values as small as ~5 × 10–4), which T 1.5 T most challenging experimental scenar- from the heavier states to the lightest pair production of higgsinos with masses proton–lead (p–Pb) collisions at √sNN = 8 predicts strong particle suppression due ios involving higgsinos. Each result tests one. The long-lived charged state flies bet ween 200 and 320 GeV (figure 1). and 8.16 TeV, respectively. The mesons to saturation of the parton phase space in

TCM fit 1.0 d i ffe r e nt a s s u m p t i o n s. O w i n g t o q u a nt um partway through the inner tracker Together, these searches set signifi- were reconstructed in the two-photon nuclei. Above momenta of about 10 GeV/c, theory, data

degeneracy, the higgsinos mix with other before decaying, and its short track cant constraints on higgsino masses, and decay channel for pT from 0.5 and 1 GeV (a) measurements in p–Pb collisions can also 0 supersymmetric electroweak states, the can be measured. A search targeting for cer tain parameters prov ide t he first up to 200 and 50 GeV for π and η mesons, 1.5 be sensitive to the energy loss of the out- p–Pb, √s NN = 8.16 TeV, ALICE norm. unc. 3.4% wino and the bino, to form the physical this anomalous “disappearing track” extension of sensitivity since LEP. With respectively. The high momentum reach going partons in nuclear matter. π0, –1.3 < y < 0.3 particles that would be observed by the signature was performed by exploiting the development of new techniques and for the π0 measurement was achieved by T h e nuc le a r m o d i fic at io n f a c t or (R ), η, –1.3 < y < 0.3 pPb experiment. The mass difference between novel requirements on the quality of the more data to come, ATLAS will continue identifying two-photon showers recon- s h o w n i n t h e l o w e r p a n e l o f t h e fi g u r e, w a s the lightest neutral and charged states, signal candidate and the ability of the to seek higgsinos at higher masses, and structed as a single energy deposit in 1.0 measured as the ratio of the cross sections ∆ m, d e p e n d s o n t h i s m i x i n g. D e p e n d i n g ATLAS inner detectors to reconstruct to test other theoretical and experimental the ALICE electromagnetic calorimeter. in p–Pb and pp collisions normalised by on the model assumptions, the phenom- short tracks. Finding that the number assumptions. In pp collisions, measurements of the atomic mass number. Below 10 GeV, 0 enology varies dramatically, requiring of short tracks is as expected from back- identified hadron spectra are used to π CGC, kT fac., FF:DSS LO R is found to be smaller than unity, 0.5 0 pPb different analysis techniques and stim- ground processes alone, this search rules Further reading constrain perturbative predictions from π FCEL, y = –0.5, gg → gg while above 10 GeV it is consistent with 0 π NLO, PDF:EPPS16 / CT14 – FF:DSS14

ulating the development of new tools. out higgsinos with lifetimes of a fraction ATLAS Collab. 2021 SUSY-2019-09. quantum chromodynamics (QCD). At large nuclear modification factor unity. The measurement is described 0 2 π NLO, PDF:nCTEQ15 / CT14 – FF:DSS14 If ∆m is only a few hundred MeV, the of a nanosecond for masses up to 210 G eV. ATLAS Collab. 2021 ATLAS-CONF-2021-007. momentum transfer (Q ), one relies in (b) by calculations over the full transverse small phase space suppresses the decay If higgsinos mix somewhat with other ATL AS Col lab. 2021 ATL AS-CONF-2021-016. these perturbative approximations of QCD 0.0 momentum range and provides further (pQCD) on the factorisation of computable 0.3 1 2 3 4 56 10 20 30 100 200 constraints to the nPDF parameterisa- CMS orders-of-magnitude larger integrated of the lightest excited b baryons, such as short-range parton scattering processes transverse momentum [GeV/c] tions for lower than about 5 GeV. The direct 0 0 luminosity have allowed the discovery Λb(5912) , Λb(5920) , and several excited such as quark–quark, quark–gluon and comparison of the neutral pion cross sec- New excited – of more than a dozen excited beauty bar- Ξb a n d Ω b states, have been observed, and gluon–gluon scatterings from long-range Fig. 1. (a) Neutral pion cross section compared to NLO pQCD tion in pp collisions at 8 TeV, with pQCD beauty-strange yon states among the 59 new hadrons are consistent with their charm partners. properties of QCD that need experimental calculations in pp collisions at 8 TeV, normalised to a calculations shown in the upper panel of obser ved at t he LHC so far (see p9). By contrast, however, heavier excitations, input. These properties are modelled by phenomenological two-component model (TCM) fit of the data. the figure, reveals differences in the low 0 0 baryon observed Many hadrons with one c or b quark such as the Λb(6072) and Ξb(62 27) i s o d o - parton distribution functions (PDFs), which (b) Nuclear modification factor ofπ and η mesons in p–Pb to intermediate pT range, which, however, are quite similar. Interchanging heavy- ublet (particles that differ only by an up describe the fractional-momentum (x) collisions at 8.16 TeV compared to calculations based on NLO c a n c e l i n R pPb, s i n c e s i m i l a r d i ffe r e n c e s a r e Beauty baryons are a subject of great quark flavours does not significantly or ), cannot yet be readily distributions of quarks and gluons within pQCD with nuclear PDFs, the Color Glass Condensate (CGC) also present for the p–Pb cross section. interest at the LHC, offering unique c h a n g e t h e p h y s ic s pr e d ic t e d b y e ffe c t i v e – associated with charmed partners. the proton, and fragmentation functions, framework , and pQCD with final-state energy loss (FCEL). Future high-precision measurements The Ξb(6100) insights into the nature of the strong models assuming “heavy quark sym- might also T h e fi r s t p a r t i c l e o b s e r v e d b y t h eCMS which describe the fractional-momentum are ongoing using the large dataset from interaction and the mechanisms by which metry”. The well-established charm experiment, in 2012, was the beauty- distribution of quarks or gluons for hadrons fractional momentum x, compared to pp pp collisions at 13 TeV, providing further shed light on 0 hadrons are formed. While the ground baryons and their excitations there- strange baryon Ξ b(5945) (CERN Courier of a certain species. c ol l i s io n s. M o d i fic a t io n a t l o wp T (~1 GeV), constraints to pQCD calculations. 0 ± – 0 – the nature states Λb, Σb, Ξb, Ξb, Ω b were observed fore provide excellent input for theo- Ju n e 201 2 p 6). It i s c o n s i s t e nt w it h b e i n g In p–Pb collisions, nuclear effects are usually attributed to nuclear shadowing + at the Tevatron at Fermilab and the SPS ries modelling the less well understood of previous the beauty partner of the Ξc(2645) with expected to significantly affect particle (CER N Courier March/April 2021 p19), can Further reading + – s at CERN, the LHC’s higher energy and spectrum of beauty-baryons. A number discoveries spin-parity 3/2 , while the Ξb(5955) production, in particular at small parton be parameterised by nuclear parton dis- ALICE Collab. 2021 arXiv:2104.03116.

18 CERN COURIER MAY/JUNE 2021 CERN COURIER MAY/JUNE 2021 19

CCMayJun21_EnergyFrontiers_v3.indd 18 13/04/2021 13:56 CCMayJun21_EnergyFrontiers_v3.indd 19 13/04/2021 13:57 CERNCOURIER www. V o l u m e 6 1 N u m b e r 3 M a y /J u n e 2 0 2 1 CERNCOURIER.COM Advertisement FIELD ARMCO® Pure Iron – a benchmark NOTES

for manifold Big Science projects Reports from events, conferences and meetings RencontRes de MoRiond Source: CERN. Copyright retained Highest quality for DC magnets The use of iron for particle accelerator Anomalies intrigue at Moriond magnets, instruments or passive magnetic

shielding must meet the advanced requirements Brice/CERN-PHOTO-201812-329-10 M The electroweak session of the Rencon- of unalloyed soft magnetic steel. Numerous tres de Moriond convened more than projects and developments in science, therapy 200 participants virtually from 22 to 27 and analytics have now proven the unrivalled March in a new format, with pre-recorded quality of ARMCO® Pure Iron. In the last plenary talks and group-chat channels decade, a profound material knowledge has been established and excellent magnetic that went online in advance of live dis- properties confirmed for a broad range of cussion sessions. The following week, shapes, dimensions and delivery conditions. the QCD and high-energy interactions AK Steel International is proud to provide the session took place with a more conven- key details from the major projects below. tional virtual organisation. The highlight of both conferences was based on the full Wanted: the next LHC iron the new LHCb result on RK Extensive material characterisation has been Run 1 and Run 2 data, and corresponding –1 performed in the framework of the High to an integrated luminosity of 9 fb , which Luminosity Large Hadron Collider (HL-LHC) led to the claim of the first evidence for upgrade since the production of the previous lepton-flavour-universality (LFU) vio- LHC low-carbon steel was discontinued. As a lation from a single measurement. RK is result, ARMCO® Pure Iron has been selected An example of an MQXF magnet. ARMCO® Pure Iron is specified for LARP low-beta quadrupole the ratio of the branching fractions for the for various iron parts in the inner-triplet master keys, yokes and load pads. decays B+ → K+ μ+ μ– and B+ → K+ e+ e–. LHCb quadrupole magnets (MQXF), as well as for measured this ratio to be 3.1σ below unity, the iron laminations in the 11 T dipole magnets. utilisation. A novel approach has been spectrometer or for applying a very uniform despite the fact that the two branching The raw-material contributions by AK Steel implemented by processing a total of magnetic field to SANS, as occurred in the fractions are expected to be equal by International are based on 1800 tonnes of 600 tonnes of customised ARMCO® Pure Iron Larmor project. virtue of the well-established property hot-rolled plates and coils for laminations, and flat items for the integrated magnet design of lepton universality (see p17). Coupled on 300 tonnes in several heavy-plate gauges of the MAX IV and SOLARIS light sources. It is worth noting that an increasing number with previously reported anomalies of

for MQXF parts. The latter procurement was More recently, it was decided at Argonne of cyclotron types for particle therapy and angular variables and the RK*, RD and Anomalies the electron and muon, and the updated upper limits on the neutrino mass,

mainly arranged by Lawrence Berkeley National National Laboratory to utilise the material’s radioisotope production benefit from the RD* branching-fraction ratios by several in focus ATLAS evidence of the four-top-pro- obtained from the direct measurement Laboratory in the framework of the US LHC specific combination of magnetic permeability specification of ARMCO® Pure Iron, covering experiments, it further reinforces the An experimental duction measurement at 4.7σ (with 2.6σ of the endpoint of the electron spectrum Accelerator Research Program (LARP). and lot-to-lot repeatability for the M1 and M2 numerous developments in medical technology indications that LFU may be violated in update from LHCb expected). ATLAS and CMS have not yet of the tritium β decay, while T2K showed magnets of the local Advanced Photon Source and academia worldwide. In addition, projects t h e B s e c t or. G l o b a l fit s a n d p o s s i bl e t heo - (pictured) on the found any indications of new physics the most recent results concerning CP ® As emphasised by CERN, ARMCO Pure upgrade. Similarly, hot-rolled heavy plates and in fusion-energy research make use of the retical interpretations with new particles flavour anomalies but continue to perform many searches, violation in the neutrino sector, obtained Iron undergoes purification during melting forged bars have been used for manufacturing specific magnetic permeability wherever related were also discussed. and a lattice-QCD expanding the scope to as-yet unexplored from the simultaneous measurement of using special refining techniques, resulting in positron damping-ring magnets for the SLAC requirements for magnets or shielding apply. – – update on the areas, and many improved limits on the νμ and νμ disappearance, and νe and νe a minimum iron content of 99.85 weight%. FACET-II facility. Here, the introduction of Important contributions anomalous new-physics scenarios were reported for appearance. The measurement disfavours After solidification it has a particularly the Pure Iron AME grade for large forgings AK Steel International has access to results Results from Belle II and BES III were magnetic moment t h e fi r s t t i m e a t b o t h c o n fe r e n c e s e s s ions. at 90% CL the CP-conserving values 0 homogeneous composition with regard to has provided a highly transformed ultra-pure from magnetic characterisation and from reported. Some of the highlights were a of the muon Several results and prospects of elec- and π of the CP-violating parameter of impurity distribution. A maximum carbon iron option at increased dimensions. Overall, accompanying tests in various conditions of fi r s t m e a s u r e m e nt o f t h eB + → K+ νν– decay provoked frank troweak precision measurements were the neutrino mixing matrix, δ , and all ® CP content of 0.010% is specified, and in most several magnet engineers and manufacturers ARMCO Pure Iron and its variants. A detailed and the most stringent limits to date for debate at the presented and discussed, including a v alues bet ween 0 and π. flat-rolled or forged conditions, as in DC who specialise in synchrotron-light-source reference list for the above-mentioned magnet masses of between 0.2 and 1 GeV from Belle Rencontres de new measurement of the fine structure The quest for dark matter is in full electromagnets, the grade exhibits a carbon equipment have utilised both ARMCO® Pure projects is available on request, based on II, based on the first data they collected, Moriond. constant with a precision of 80 parts per swing and is expanding on all fronts. content of 0.005% or below. With the Iron and Pure Iron AME for manifold project an article by A Parrella, P Arpaia, M Buzio and searches for LFU violation in the charm trillion, and a measurement of the null XENON1T updated delegates on an existing capabilities of producing flat-rolled work worldwide. et al. (2019 IEEE Transactions on Magnetics sector from BES III that for the moment give electric dipole moment of the with intriguing small excess in the low- items, the carbon content has not exceeded 2001004). Designers who intend to 55 negative results. Belle II is expected to give an uncertainty of 1.1 × 10–26 e∙cm. Theoret- energy part of the electron-recoil spec- 0.0023%, with an average value of 0.0013% unambiguously define this grade in their The power of a well-defined field i m p or t a nt c o nt r i b ut i o n s t o t h e L F U s t u d- ical predictions of (g–2) were discussed, trum, from 1 to 7 keV, which could be over several years of production. Very low CERN Courier has previously reported specifications are recommended to use the μ ies soon and to accumulate an integrated including the recent lattice calculation interpreted as originating from new values of oxygen, sulphur, nitrogen and cobalt on the Baby MIND neutrino detector designation “ARMCO Pure Iron”. –1 are confirmed, as well as full transformation, (www.cerncourier.com/a/baby-mind-takes- luminosity of 50 ab 10 years from now. from the Budapest–Marseille–Wuppertal particles but that is also consistent with homogeneity and freedom from pores and first-steps), where large-area elements are ATLAS and CMS presented tens of new group of the hadronic–vacuum–polari- an increased background from tritium inclusions. Due to the particularly low carbon made from customised ARMCO® Pure Iron results each on Standard Model (SM) sation contribution, which, if used in contamination. Upcoming new data content, the microstructure is composed of heavy plates. For the DUNE/LBNF neutrino measurements and searches for new phe- comparison with the experimental meas- from the upgraded XENONnT detector 100% ferrite. experiment, cold-rolled sheets of the same nomena in the two conferences. Highlights urement, would bring the tension with the are expected to be able to disentangle the grade were selected for the beamline magnets included the CMS measurement of the W (g–2) μ prediction to within 2σ. (see pY Y). different possibilities, should the excess Benchmark for synchrotrons in the framework of the current Fermilab leptonic and hadronic branching fraction In the neutrino session, the most rele- be confirmed. The Dark Matter ® with an accuracy larger than that meas- vant recent new results of last year were eXperiment (ADMX) is by far the most

As well as collider projects, ARMCO collaborations. Moreover, experiments with AK Steel International s Pure Iron has been specified for numerous neutral particles require ARMCO® Pure Iron Please visit our website and contact your ured at LEP for the branching fractions of discussed. KATRIN reported updated sensitive experiment to detect synchrotron rings to secure the required for magnetic shielding in the vicinity of high- local sales office. magnet performance at optimised power Tesla instrumentation such as the aSPECT www.aksteel.eu CERN COURIER MAY/JUNE 2021 21

CCMayJun21_Fieldnotes_v3.indd 21 13/04/2021 14:07 CERNCOURIER www. V o l u m e 6 1 N u m b e r 3 M a y /J u n e 2 0 2 1 CERNCOURIER.COM CERNCOURIER.COM

FIELD NOTES FIELD NOTES

+ 0 th einteRpRetation oRkshop i n t h e e x pl or e d r a n g e a r o u n d 2 μeV. A DM X production in the bbγγ channel, which The quest for mentum spectrum and the Λc /D ratio in 6 LhC R W showed near-future prospects and the yielded the tightest constraints to date dark matter pp and p–Pb collisions, showing discrep- plans for upgrading the detector to scan on the Higgs-boson self-coupling, and is in full ancies with perturbative QCD predictions. a much wider mass range, up to 20 μeV, the measurement of the top-quark mass The above is only a snapshot of the many LHC reinterpreters think long-term in the next few years. The search for dark by CMS in the single-top-production swing and is interesting results presented at this year’s matter also continues at accelerators, channel that for the first time reached expanding on Rencontres de Moriond, representing the Illustration (c) C. Wormell from “A Map of the Invisible” by J. by Butterworth Invisible” “A the of (c) from Map Wormell C. Illustration where it could be directly produced or an accuracy of less than 1 GeV, now becom- all fronts hard work and dedication of countless The ATLAS, CMS and LHCb collabora- be detected in the decays of SM particles ing relevant to future top-mass combi- physicists, many at the early-career stage. tions perform precise measurements of such as the Higgs boson. nations. Several recent heavy-ion results As ever, the SM stands strong, though Standard Model (SM) processes and direct ATLAS and CMS also presented new were also presented by the LHC experi- intriguing results provoked lively debate searches for physics beyond the Standard results at the Moriond QCD and high- ments, and by STAR and PHENIX at RHIC, during many a virtual discussion. Model (BSM) in a vast variety of channels. energy-interactions conference. High- in the dedicated heavy-ion session. One Despite the multitude of BSM scenarios lights of the new results are: the ATLAS highlight was a result from ALICE on the Marco Pieri Universit y of California, tested this way by the experiments, it + full Run-2 search for double-Higgs-boson measurement of the Λc transverse-mo- San Diego. still constitutes only a small subset of the possible theories and parameter com- Y Makino/IceCube/NSF NeuTel 2021 tension of their measurements creates binations to which the experiments are c o u nt e r-i nt u it i v e fit v a lu e s w h e n a com- sensitive. The (re)interpretation of the NeuTel as bination is tried, as discussed by Antonio LHC results in order to fully understand Marrone of the University of Bari. The their implications for new physics has vibrant as ever most striking example is the neutrino become a very active field, with close mass hierarchy: both experiments in theory–experiment interaction and with The XIX International Workshop on t h e i r o w n fit s f a v o u r a n or m a l h i e r a r chy, new computational tools and related Neutrino Telescopes (NeuTel) attracted but their combination, with a tension infrastructure being developed. 1000 physicists online from 18 to 26 Feb- in the value of the CP phase, favours an From 15 to 19 February, almost 300 ruary, under the organisation of INFN inverted hierarchy. theorists and experimental physicists Sezione di Padova and the Department The founder of the Borexino experi- gathered for a week-long online work- Embarrassment of riches ATLAS, CMS and LHCb are sensitive to a far greater set of theories and of Physics and Astronomy of the Uni- ment, Gianpaolo Bellini, discussed the shop to discuss the latest developments. parameter combinations than have so far been tested. versity of Padova. results of the experiment together with The topics covered ranged from advances The opening session featured pres- the latest exciting measurements of the in public software packages for rein- can already make use of pyhf and JSON giving details on the available data, on entations by , on the CNO cycle in the Sun. DUNE, Hyper-K, terpretation to the provision of detailed likelihoods, and others are to follow. An their format and on the tools to access past and future of neutrino science, Carlo South Pole cussed in depth, with special emphasis and JUNO presented progress towards analysis information by the experiments, alternative approach to the plain-text them. An open-data policy also exists at Rubbia, on searches for neutrino anoma- shifters on blazars, starburst galaxies and tidal- the realisation of these leading projects, from phenomenological studies to global JSON serialisation is to encode the exper- the LHC, spearheaded by the CMS col- lies, and , on the present and The IceCube distribution events. Perspectives for and speakers discussed their potential in fit s, a n d f r o m l o n g-t e r m pr e s e r v a t io nto imental likelihood functions in deep laboration, and Edgar Carrera Jarrin (USF future of gravitational-wave detection. observatory future global multi-messenger obser- many aspects of new-physics searches, public data. neural networks, as discussed by Andrea Q u it o) s h a r e d e x p e r ie n c e s f r o m t h e fi r s t This session was a propitious moment for unearthed a vations and campaigns, including astrophysics investigations and neutrino– Coccaro (INFN Genova) who presented CMS open-data workshop. IceCube principal investigator Francis “Glashow gravitational waves and networks of oscillation sensitivities. The latest results Open likelihoods the DNNLikelihood framework. Several The question of making research data Halzen to give a “heads-up” on the first resonance” 61 years neutrino instruments over a broad range of the reactor–neutrino experiment Neu- One of the leading questions throughout more contributions from CMS, LHCb and findable, accessible, interoperable and observation, in the South-Pole detector, after the event was of energies, were illustrated, anticipat- trino-4, which about one year ago claimed the workshop was that of public likeli- from theorists addressed the question of reusable (“FAIR” in short) is a burning one of a so-called Glashow resonance – the hypothesised and ing core-collapse supernovae as the 3.2σ evidence for an oscillation anomaly hoods. The statistical model of an exper- how to present and use likelihood infor- throughout modern science. In a keynote interaction of an electron antineutrino 33 years after the most promising sources. The future of that could be induced by sterile neutri- imental analysis provides its complete mation, and this will certainly stay an talk, the head of the GO FAIR Foundation, with an atomic electron to produce a real detector was astroparticle physics relies upon very nos, were discussed in a dedicated session. mathematical description; it is essen- active topic at future workshops. Barend Mons, explained the FAIR Guid- W boson, as the eponymous theorist pre- conceived at the large infrastructures and collabora- B o t h IC A RUS a n d K AT R IN pr e s e nt e d t h e i r tial information for determining the A novelty for the Reinterpretation ing Principles together with the technical dicted back in 1960. According to Gla- first NeuTel. tive efforts on a planetary scale. Next- sensitivities to this signal in two com- compatibility of the observations with workshop was that the discussion was and social aspects of FAIR data manage- show’s calculations, the energy at which generation neutrino telescopes might pletely different setups. theoretical predictions. In his keynote extended to experiences and best prac- ment and data reuse, using the example the resonance shall happen depends on follow different strategic developments. Marc Kamionkowski (John Hopkins talk “Open science needs open likeli- tices beyond the LHC, to see how exper- of COVID-19 disease modelling. There is the mass of the W boson, which was dis- Extremely large volumes, equipped University) and Silvia Galli (Institut hoods’’, Harrison Prosper (Florida State iments in other fields address the need much to be learned here for our field. covered in 1983 by Rubbia and his team. with cosmic-ray-background veto d’Astrophysique de Paris) both provided University) explained why it is in our sci- for publicly released data and reusable The wrap-up session revolved around The first edition of NeuTel saw the techniques and complementary radio- an update on the “Hubble tension”: an entific interest to make the publication results. This included presentations the question of how to implement the birth of the idea of instrumenting a sensitive installations might be the key approximately 4σ d i ffe r e n c e i n t h e Hub - of full likelihoods routine and straight- on dark-matter direct detection, the recommendations of the Reinterpreta- large volume of Antarctic ice to capture to achieving high statistics and high- ble constant when determined from forward. The ATLAS collaboration has high-intensity frontier, and neutrino tion workshop in a more systematic way. high-energy neutrinos – a “Deo volente” precision measurements over a large angular temperature fluctuations in the recently made an important step in this oscillation experiments. Support- An important aspect here is the proper (God willing) detector, as Halzen and col- energy range, given limited sky cover- cosmic microwave background (probing direction by releasing full likelihoods ing Prosper’s call for data reusability recognition, within the collaborations laborators then dubbed it. Thirty-three age. Alternatively, a network of interme- the expansion rate when the universe in a JSON format, which provides back- 40 years into the future – “for science The question as well as the community at large, of the years later, as the detection of a Glashow diate-scale installations, like KM3NeT, was approximately 380,000 years old) ground estimates, changes under sys- 2061” – Eligio Lisi (INFN Bari) pointed of making additional work required to this end. More resonance demonstrates, it is possible to distributed over the planet and based on and observing the recession velocity of tematic variations, and observed data out the challenges met in reinterpreting rigorous citation of HEPData entries by precisely calibrate the absolute energy existing or future infrastructures, might supernovae (which provides its current c o u nt s a t t h e s a m e fid e l it y a s u s e d i n the the 1998 Super-Kamiokande data, ini- research data theorists may help in this regard. More- scale of these gigantic instruments for be better suited for population studies value). This Hubble tension could hint experiment, as presented by Eric Schanet tially published in terms of the then- findable, over, a “Reinterpretation: Auxiliary Mat- cosmic particles, and we have achieved of transient phenomena. Efforts are at new physics modifying the thermal (LMU ). Matthew Feickert (Uni- sufficient two-flavour neutrino-oscilla- accessible, erial Presentation” (RAMP) seminar series several independent proofs of the exist- currently being undertaken along both history of our universe, such as massive versity of Illinois) and colleagues gave tion paradigm, in terms of contemporary interoperable will be launched to give more visibility ence of high-energy cosmic neutrinos, paths, with a newborn project, P-ONE, neutrinos that influence the early-time a detailed tutorial on how to use these three-neutrino descriptions, and beyond. and reusable is and ex plicit recog nition to t he effor ts of including first confirmations by ANTARES exploiting existing deep-underwater measurement of the Hubble parameter. likelihoods with the pyhf python pack- On the astrophysics side, the LIGO and preparing and providing extensive mat- a burning one and Baikal-GVD. Canadian infrastructures for science to age. Two public reinterpretation tools, Virgo collaborations actively pursue an erial for reinterpretation. The first RAMP Astrophysical models describing the operate strings of photomultipliers. Elisa Bernardini and Francesco D’Eramo MadAnalysis5 presented by Jack Araz open-science programme. Here, Agata throughout meetings took place on 9 and 23 April. connections between cosmic neutri- T2K and NOvA did not update last sum- University of Padova and INFN-Padova, (IPPP Durham) and SModelS presented Trovato (APC Paris) presented the modern nos, photons and cosmic rays were dis- mer’s leptonic–CP–violation results. The and Mauro Mezzetto INFN-Padova. by Andre Lessa (UFABC Santo Andre) Open Science Center, science Sabine Kraml LPSC Grenoble.

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CCMayJun21_Fieldnotes_v3.indd 22 13/04/2021 14:07 CCMayJun21_Fieldnotes_v3.indd 23 13/04/2021 14:10 CERNCOURIER www. V o l u m e 6 1 N u m b e r 3 M a y /J u n e 2 0 2 1 www.hidenanalytical.com CERNCOURIER.COM [email protected] FEATURE MUON g–2 L Jin L ANOMALOUS MOMENT FOR THE MUON Instruments for Thanks to new theory calculations and keenly awaited measurements of the magnetic Advanced Science moment of the muon, a longstanding anomaly may soon be resolved either in Mass spectrometers for vacuum, gas, plasma and surface science favour of new physics or the Standard Model.

’s spin tends to twist to align with a mag- heavily suppressed when they emerge as virtual particles Challenging netic field – an effect t hat becomes dramatically from the more massive muon. calculation A macroscopic when electron spins twist together in All told, our knowledge of the anomalous magnetic It took a billion a ferromagnet. Microscopically, the tiny magnetic moment moment of the muon is currently three orders of magni- core-hours of a fermion interacts with the external magnetic field tude less precise than for electrons. And while everything on the Mira through absorption of photons that comprise the field. tallies up, more or less, for the electron, BNL’s longstand- supercomputer Quantifying this picture, the Dirac equation predicts fer- ing measurement of the magnetic moment of the muon to compute the mion magnetic moments to be precisely two in units of is 3.7σ greater than the Standard Model prediction (see hadronic Bohr magnetons, e/2m. But virtual lines and loops add panel “Rising to the moment”). The possibility that the light-by-light an additional 0.1% or so to this value, giving rise to an discrepancy could be due to virtual contributions from contribution to “anomalous” contribution known as “g–2” to the parti- as-yet-undiscovered particles demands ever more precise the muon’s cle’s magnetic moment, caused by quantum fluctuations. theoretical calculations. This need is now more pressing magnetic moment. Residual Gas Analysis Calculated to tenth order in than ever, given the increased precision of the experi- Perform RGA at UHV/XHV . Our RGA configurations include systems for UHV (QE D), a n d v e r i fie d e x p e r i m e nt a l l y t o a b o ut t wo p a r t sin mental value expected in the next few years from the 1010, the electron’s magnetic moment is one of the most Muon g–2 collaboration at Fermilab in the US and other science applications including temperature-programmed desorption and precisely known numbers in the physical sciences. While experiments such as the Muon g–2/EDM collaboration at electron/photon stimulated desorption. also measured precisely, the magnetic moment of the J-PARC in Japan. Hotly anticipated results from the first muon, however, is in tension with the Standard Model. data run at Fermilab’s E989 experiment were released on 7 April. The new result is completely consistent with Tricky comparison the BNL value but with a slightly smaller error, leading Thin Film Surface Analysis T h e a n o m a lo u s m a g n e t ic m o m e nt o f t h e muo n w a s fi r s t to a slightly larger discrepancy of 4.2σ with the Standard measured at CERN in 1959, and prior to 2021, was most Model when the measurements are combined (see p7). Conduct both static and dynamic SIMS analysis with a choice of primary ions recently measured by the E821 experiment at Brookhaven for full chemical composition and depth profiling. Our SIMS solutions include National Laboratory (BNL) 16 years ago. The compari- Hadronic vacuum polarisation

son between theory and data is much trickier than for The value of the muon anomaly, aμ, is an important test complete workstations and bolt-on modules. electrons. Being short-lived, muons are less suited to of the Standard Model because currently it is known very experiments with Penning traps, whereby stable charged precisely – to roughly 0.5 parts per million (ppm) – in p a r t ic le s a r e c o n fi n e d u s i n g s t at ic e le c t r ic a n d m a g netic both experiment and theory. QED dominates the value

fie ld s, a n d t h e t r a p p e d p a r t ic le s a r e t h e n c o ole d t o allow of aμ, but due to the non-perturbative nature of QCD it THE AUTHORS Plasma Characterisation precise measurements of their properties. Instead, exper- is strong interactions that contribute most to the error. iments infer how quickly muon spins precess in a storage The theoretical uncertainty on the anomalous mag- Thomas Blum Fully characterise a range of plasmas: RF, DC, ECR and pulsed plasmas, including and Luchang Jin ring – a situation similar to the wobbling of a spinning netic moment of the muon is currently dominated by University of top, where information on the muon’s advancing spin is so-called hadronic vacuum polarisation (HVP) diagrams. neutrals and neutral radicals. Extend your analyses to atmospheric pressure Connecticut, and encoded in the direction of the electron that is emitted In HVP, a virtual photon briefly explodes into a “hadronic processes using the HPR-60, with time-resolved mass/energy analysis. Christoph Lehner when it decays. Theoretical calculations are also more blob”, before being reabsorbed, while the magnetic-field University of challenging, as hadronic contributions are no longer so photon is simultaneously absorbed by the muon. While of Regensburg.

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FEATURE MUON g–2 FEATURE MUON g–2

mass, 775 MeV. Though the integral converges rapidly to aim for statistics-dominated errors to make it more Rising to the moment w it h i n c r e a s i n g e n e r g y, d at a a r e n e e d e d o v e r a r e l at i v e l y straightforward to quantitatively interpret the resulting In the Standard Model, the magnetic moment of the muon is computed order- LM 2020 broad region to obtain the necessary precision. Above the agreement with the no-new-physics scenario or the dis- by-order in powers of α for QED (each virtual photon represents a factor of α), τ mass, QCD per turbat ion t heor y hones t he calculat ion. persive results. In the shorter term, it will also be crucial BMW 2020 and to all orders in αs for QCD. Several groups have computed the HVP contribution in to cross-check between different lattice and dispersive At the lowest order in QED, the Dirac μ ETM 2018/19 this way, and recently a consensus value has been produced results using additional observables, for example based term (pictured right) accounts for a s p a r t o f t h e world w id e M uo n g–2 T h e or y I n it i at i v e. T h e on the vector–vector correlators. Mainz/CLS 2019 precisely two Bohr magnetons and error stands at about 0.58% and is the dominant part of With improved lattice calculations in the pipeline from arises purely from the muon (μ) and the FNAL-HPQCD-MILC 2019 the theory error. It is worth noting that a significant a number of groups, the tension between lattice QCD and real external photon (γ) representing γ PACS 2019 part of the error arises from a tension between the most phenomenological calculations may well be resolved before the magnetic field. precise measurements, by the BaBar and KLOE experi- the Fermilab and J-PARC e x p e r i m e nt s a n n o u n c e t h e i r fi n a l At higher orders in QED, virtual Standard Model particles, depicted by lines RBC/UKQCD 2018 ments, around the rho–meson peak. New measurements, results. Interestingly, there is a new lattice result with forming loops, contribute to a fractional increase of aμ with respect to that value: BMW 2017 including those from experiments at Novosibirsk, Russia sub-percent precision (BMW 2020) that is in agreement the so-called anomalous magnetic moment of the muon. It is defined to be

and Japan’s Belle II experiment, may help resolve the both with the no-new-physics point within 1.3σ, and with aμ = (g–2)/2, where g is the gyromagnetic ratio of the muon – the number of Bohr inconsistency in the current data and reduce the error the dispersive-data-driven result within 2.1σ. Barring a magnetons, e/2m, which make up the muon’s magnetic moment. According to KNT 2019 by a factor of two or so. significantre-evaluation of the phenomenological cal- the Dirac equation, g = 2, but radiative corrections increase its value. The alternative approach, of calculating the HVP con- culation, however, HVP does not appear to be the source DHMZ 2019 The biggest contribution is from the tribution from first principles using lattice QCD, is not of the discrepancy with experiments. Schwinger term (pictured right, O(α)) BDJ 2019 yet at the same level of precision, but is getting there. The next most likely Standard Model process to explain and higher-order QED diagrams. + ... Consistency between the two approaches will be crucial the muon anomaly is hadronic light-by-light scattering. Jegerlehner 2018 QED –11 for any claim of new physics. Though it occurs less frequently since it includes an extra aμ = (116 584 718.931 ± 0.104) × 10 virtual photon compared to the HVP contribution, it is much RBC/UKQCD 2018 Lattice QCD less well known, with comparable uncertainties to HVP. Electroweak lines (pictured right) also H, W, Z Kenneth Wilson formulated lattice in 1974 make a well-defined contribution. Muon g–2 Theory Initiative 2020 a s a m e a n s t o r id q u a nt u m fie ld t h e or ie s o f t h e i r n o t or io us Hadronic light-by-light scattering These diagrams are suppressed by infinities – a process known as regulating the theory In hadronic light-by-light scattering (HLbL), the magnetic the heavy masses of the Higgs, W and LQCD – while maintaining exact gauge invariance, but with- field interacts not with the muon, but with a hadronic Z . Pheno. no new physics (E821 + E989) out usi ng per t urbat ion t heor y. L at t ice QCD c a lc ulat ions “blob”, which is connected to the muon by three virtual EW –11 Pheno + LQCD aμ = (153.6 ± 1.0) × 10 involve the very large dimensional integration of path photons. (The interaction of the four photons via the integrals in QCD. Because of confinement, a perturba- hadronic blob gives HLbL its name.) A miscalculation of The biggest QCD contribution is due to 600 650 700 750 hadronic vacuum polarisation (HVP) tive treatment including physical hadronic states is not the HLbL contribution has often been proposed as the diagrams. These are computed from aHVP, LO ×1010 p o s s i ble, s o t h e c omple t e i nt e g r a l, re g u l at e d pro p e rl y i n source of the apparently anomalous measurement of the µ leading order (pictured right, O(α2)), + ... a discrete, finite volume, is done numerically by Monte muon anomaly by BNL’s E821 collaboration. with one “hadronic blob” at all orders Off the markValues of the leading-order hadronic vacuum-polarisation Carlo integration. Since the so-called Glasgow consensus (the fruit of in αs (shaded) up to next-to-next-to- HVP, LO 10 4 contribution to the anomalous magnetic moment of the muon, aμ (× 10 ). Lattice QCD has made significant improvements over a 2009 workshop) first established a value more than leading order (NNLO, O(α ), with three The purple circles indicate independent lattice–QCD calculations; the red squares the last several years, both in methodology and invested 10 years ago, significant progress has been made on the hadronic blobs) in the HVP. show results from dispersion relations and the experimental cross-sections for computing time. Recently developed methods (which analytic computation of the HLbL scattering contri- HVP 11 aμ × 10 LO NLO NNLO e+e– annihilation; the orange triangle shows a combined value where rely on low-lying eigenmodes of the Dirac operator to bution. In particular, a dispersive analysis of the most e+e– data 6931 ± 40 –98 ± 7 12 ± 1 contributions are taken from the most precise parts of data-driven and lattice s p e e d up c a lc u l at io n s) h a v e b e e n e s p e c i a l l y i m p or t a nt for important hadronic channels has been carried out, Lattice QCD 7116 ± 184 results of Jegerlehner 2018 and RBC/UKQCD 2018, respectively; and the black muon–anomaly calculations. By allowing state-of-the-art including the leading pion–pole, sub-leading pion loop triangle shows the theoretical value currently being used for experimental c a lc u l at io n s u s i n g p h y s ic a l m a s s e s, t h e y r e m o v e a s i g n i fi- and rescattering diagrams including heavier pseudos- Hadronic light-by-light scattering 3 comparisons with E821 and E989. The grey band indicates the value needed to cant systematic: the so-called c h i r a l e x t r a p ol at io n for t h e calars. These calculations are analogous in spirit to the (HLbL, pictured right at O(α ) and bring the SM into agreement with the measurements by the BNL and Fermilab l i g ht q u a r k s. T h e r e m a i n i n g s y s t e m at ic e r r or s a r i s e f r o m dispersive HVP calculations, but are more complicated, all orders in αs (shaded)), makes a experiments (plot adapted from T Aoyama e t a l. 2020). the finite volume andnon-zero lattice spacing employed a n d t h e e x p e r i m e nt a l m e a s u r e m e nt s a r e m or e d i ffic u lt smaller contribution but with a larger + ... fractional uncertainty. i n t he si mu l at ion s. The s e a re h a nd le d b y doi ng mu lt iple because form factors with one or two virtual photons order α2 in QED, it is all orders in QCD, making for very simulations and extrapolating to the infinite-volume are required. HLbL 11 difficult calculations. and zero-lattice-spacing limits. The project to calculate the HLbL contribution using lat- aμ × 10 LO NLO Historically, and into the present, HVP is calculated The HVP contribution can readily be computed using lat- tice QCD began more than 10 years ago, and many improve- Phenomenology 92 ± 19 2 ± 1 using a dispersion relation and experimental data for t ic e Q C D i n E uc l id e a n s p a c e w it h space-like four-momenta ments to the method have been made to reduce both Lattice QCD 79 ± 35 the cross section for e+e– → had rons. Th is idea w as b or n i n t h e p h o t o n lo o p, t hu s y ie ld i n g t h e r e a l p a r t o f t h e H V P statistical and systematic errors since then. Last year we + – of necessity almost 60 years ago, before QCD was even directly. The dispersive result is currently more precise published, with colleagues Norman Christ, Taku Izubuchi Neglecting lattice–QCD calculations for the HVP in favour of those based on e e data and phenomenology, the total anomalous magnetic moment is given by on the scene, let alone calculable. The key realisation is (see “Off t he mark” fig ure”), but fur t her improvements a n d M a s a s h i Ha y a k a w a, t h e fi r s t e v e r l at t ic e– Q C D c alcu- + – SM QED EW HVP HLbL –11 that the imaginary part of the vacuum polarisation is w ill depend on consistent new e e scattering datasets. lation of the HLbL contribution with all errors controlled, aμ = aμ + aμ + aμ + aμ = (116 591 810 ± 43) × 10 . directly related to the hadronic cross section via the optical R a pid pr o g r e s s i n t h e l a s t fe w y e a r s h a s r e s u lt e d i n fi r s t fi n d i n g a HLbL, lattice = (78.7 ± 30.6 (stat) ± 17.7 (sys)) × 10–11. The μ This is somewhat below the combined value from the E821 experiment at BNL theorem of wave-scattering t h e or y; a d i s p e r s io n r e l at io n lattice results with sub-percent uncertainty, closing in calculation was not easy: it took four years and a bil- in 2004 and the E989 experiment at Fermilab in 2021. t h e n r e l at e s t h e i m a g i n a r y p a r t t o t h e r e a l p a r t. T h e c r o s s on the precision of the dispersive approach. Since these lion core-hours on the Mira supercomputer at Argonne aexp = (116 592 061 ± 41) × 10–11 section is determined over a relatively wide range of lattice calculations are very involved and still matur- National Laboratory’s Large Computing Facility. μ energies, in both exclusive and inclusive channels. The ing, it will be crucial to monitor the emerging picture Our lattice HLbL calculations are quite consistent with The discrepancy has roughly 4.2σ significance:

dominant contribution – about three quarters – comes once several precise results with different systematic the analytic and data-driven result, which is approximately exp SM –11 aμ – aμ = (251 ± 59) × 10 . f r o m t h e e +e– → π+π– c h a n n e l, w h ic h p e a k s at t h e r h o m e s o n approaches are available. It will be particularly important a factor of two more precise. Combining the results

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FEATURE MUON g–2

leads to a HLbL = (90 ± 17) × 10–11, which means the very leptons and quarks to change into each other. Another μ Fast Pulse Generators & difficult HLbL contribution cannot explain the Standard option involves scenarios whereby the Standard Model Model discrepancy with experiment. To make such a strong Higgs boson is accompanied by a heavier Higgs-like b o s o n. conclusion, however, it is necessary to have consistent T h e c a lc u l at io n s o f t h e a n o m a lo u s m a g n e t ic m o m e nt o f Arbitrary Waveform Generators results from at least two completely different methods of the muon are not finished. As a systematically improvable calculating this challenging non-perturbative quantity. method, we expect more precise lattice determinations of the hadronic contributions in the near future. Increasingly New physics? p o w e r f u l a l g or it h m s a n d h a rd w a r e r e s o u rc e s w i l l f u r t h e r I f c u r r e nt t h e or y c a lc u l at io n s o f t h e muo n a n o m a l y h old i m pr o v e pr e c i s io n o n t h e l at t ic e s id e, a n d n e w e x p e r i m e nt a l up, a n d t h e n e w e x p e r i m e nt s r e d uc e it s u n c e r t a i nt y b y t h e m e a s u r e m e nt s a n d a n a l y s i s m e t h o d s w i l l d o t h e s a m e for hoped-for f a c t or o f fo u r, t h e n a new-physics e x pl a n at io n dispersive studies of the HVP and HLbL contributions. will become impossible to ignore. The idea would be to To c o n fid e nt l y d i s c o v e r n e w p h y s ic s r e q u i r e s t h at t h es add particles and interactions that have not yet been two independent approaches to the Standard Model value observed but may soon be discovered at the LHC or in agree. With the first new results on the experimental f ut u r e e x p e r i m e nt s. Ne w p a r t ic le s w o u ld b e e x p e c t e d t o v a lue o f t h e muo n a n o m a l y i n a l m o s t t wo d e c a d e s s h o w- contribute to the anomaly through Feynman diagrams ing perfect agreement with the old value, we anxiously s i m i l a r t o t h e St a n d a rd M o d e l t o p o g r a p h ie s (s e e “R i s i n g await more precise measurements in the near future. to t he moment” panel). O u r ho p e i s t h at t he c l a s h of t he or y a nd e x p e r i me nt w i l l The most commonly considered new-physics expla- be the beginning of an exciting new chapter of particle n at io n i s s up e r s y m m e t r y, b ut t h e i n c r e a s i n g l y s t r i n g e nt p h y s ic s, h e r a ld i n g n e w d i s c o v e r ie s at c u r r e nt a n d f ut u r e Calculations of lower limits placed on the masses of super-partners by particle colliders.  the anomalous the LHC experiments make it increasingly difficult to magnetic explain the muon anomaly. Other theories could do the Further reading moment of job too. One popular idea that could also explain per- T Aoyama et al. 2020 Phys. Rept. 887 1–166. the muon are sistent anomalies in the b-quark sector is heavy scalar T Blum et al. 2020 Phys. Rev. Lett. 124 132002 Amplitude Range not fi n i she d , which mediate a new interaction allowing (arXiv:1911.08123). Rise / Fall Time Sampling Rate

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When Compromise is Not an Option. High-Performance Digitizers for Big Physics Applications Evolving fluctuationsThree droplets of quark–gluon plasma, simulated at 6 and 38 yoctoseconds (10–24 s) after head-on collisions between Digitizers from Teledyne SP Devices utilize patented lead ions in the LHC. (Credit: MUSIC arXiv:1209.6330) calibration technology, the latest data converters, and state-of-the-art FPGAs in order to achieve an unrivaled combination of high resolution and sampling rate. Their versatility makes them ideal for applications such as GOING WITH THE FLOW beam position monitoring, Thomson scattering plasma diagnostics, and more. The ALICE experiment is making strides towards understanding how charm and beauty quarks flow within cooling droplets of quark–gluon plasma at the LHC, Supported features include: shedding light on the extreme conditions of the early universe. • Up to 10 GSPS sampling rate with 14 bits resolution • Open FPGA for custom real-time signal processing icroseconds after the Big Bang, quarks and of quantum chromodynamics. gluons roamed freely. As the universe expanded, A m o n g t h e m o s t s t r i k i n g fe at u r e s o f t h e Q GP for m e d at • Multiple form factors including MTCA.4, PXIe, and PCIe M this quark–gluon plasma (QGP) cooled. When the LHC is the development of “collective” phenomena, as t h e t e m p e r at u r e d r o p p e d t o r o u g h l y a hu n d r e d t h o u s a n d spatial anisotropies are transformed by pressure gradients • Multi-channel synchronization capabilities times that in the core of the Sun, hadrons formed. Today, into momentum anisotropies. The ALICE experiment is • White Rabbit synchronization (MTCA.4 only) this phase transition is reproduced in the heart of detec- designed to study the collective behaviour of the torrent tors at the LHC when lead ions careen into each other at of particles created in the hadronisation of QGP droplets. • Peer-to-peer streaming to GPU (PCIe only) high energ y. Following detailed studies of the “flow” of the abundant The experimental quest for the QGP started in the light hadrons that are produced, ALICE has recently demon- THE AUTHORS • Application-specific firmware shortens design time 1980s using fixed-target collisions at the Alternating st rated, alongside cer tain compet it ive measurements by Gradient Synchrotron at Brookhaven National Labora- CMS and ATLAS, the flow ofheavy-flavour (H F) h a d r o n s – Javier Castillo tory (BNL) and the Super at CERN. particles that probe the entire lifetime of a droplet of QGP. Castellanos CEA Paris-Saclay, This side of the millennium, collider experiments have Fabrizio Grosa provided a big jump in energy, first at the Relativistic A perfect fluid CERN and Heavy Ion Collider (RHIC) at BNL, and now at the LHC. T h e Q GP c r e at e d i n le a d–io n c ol l i s io n s at t h e L HC i s m a d e up Martin Andreas B o t h f a c i l it ie s a l lo w a t h or o u g h i n v e s t i g at io n o f t h e Q GP o f t h o u s a n d s o f q u a r k s a n d g luo n s – f a r t o o m a n y q u a nt u m Völkl Universität at d i ffe r e nt p oi nt s o n t hestill-mysterious phase diagram fields to keep t r ac k of i n a si mulat ion. In t he ea rly 2000s, Heidelberg. Learn more on our website www.spdevices.com CERN COURIER MAY/JUNE 2021 31

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FEATURE QUARK–GLUON PLASMA FEATURE QUARK–GLUON PLASMA

ALICE ALICE arxiv:2002.00633 ALICE in action

t = 2 fm/c –1 ALICE 10 ALICE The geometrical overlap between the two 0–5% colliding nuclei varies from head-on MUSIC arXiv:1209.6330 40–50% collisions that produce a huge number of particles, sending several thousand hadrons flying to ALICE’s detectors (“0% centrality”, 10–2 as a percentile of the hadronic cross section) to peripheral collisions where the two nuclei n

V barely overlap (“100% centrality”). Since the initial geometry is not directly experimentally accessible, centrality is estimated using either Pb–Pb √s = 5.02 TeV the total particle multiplicity or the energy 10–3 NN 0.4 < |η| < 0.8 deposited in the detectors. Among the cloud of particles are a 0.2 < pT < 5.0 GeV handful of open and hidden heavy-flavour hadrons that are reconstructed from 2 4 6 8 their decay products using tracking, n particle-identification and decay-vertex Light-flavour flowALICE has measured significant values reconstruction. Charm mesons are for the flow anisotropy coefficients (v ) of charged hadrons up reconstructed through hadronic decay t = 10 fm/c n to ninth order (n = 9) – a nine-pronged Fourier component in channels using the central barrel detectors. transverse-momentum space. Measurements are plotted Open beauty hadrons are also reconstructed here for head-on “central” collisions (grey), and glancing in the central barrel using their semileptonic 40–50% centrality collisions between lead nuclei (red). decay to an electron as a proxy. Compelling evidence of heavy-quark energy loss in High multiplicity Lead–ion collisions can generate thousands of hadrons. symmetry plane that connects the centres of the colliding a deconfined strongly interacting matter nuclei. As the system evolves, interactions push the QGP is provided by the suppression of high-pT forward muon spectrometer using their decay than is seen at the lower collision energies more strongly along the shorter symmetry-plane axis than open heavy-flavour hadron yields in central channel to two muons. Charmonium states of RHIC, despite the increased density of along the longer one (see “Noncentral collision” figure). nucleus–nucleus collisions relative to were among the first proposed probes of the colour charges at higher collision energies. This is called elliptic flow. proton–proton collisions (after scaling by deconfinement of the QGP. The potential This effect may be understood as due to Density fluctuations in the initial state may also lead the average number of binary – between the heavy quark and antiquark pair is J/ψ regeneration as the copiously produced to other anisotropic flows in the velocity field of the QGP. nucleon collisions). partially screened by the high density of colour charm quarks and antiquarks recombine. By Triangular flow, for example, pushes the system along A small fraction of the initially created charges in the QGP, leading to a suppression contrast, bottomonia are not expected to have three axes. In general, this collective motion is decom- heavy-quark pairs will bind together to of the production of charmonium states. a large regeneration contribution due to the – ∞ form charmonium (c–c ) or bottomonium Interestingly, however, ALICE observes less larger mass and thus lower production cross posed as 1 + 2 ∑n = 1 vn cos(n(ϕ–Ψn)), where vn are harmonic – coefficients,ϕ is the azimuthal angle of the final-state (b-b) states that are reconstructed in the suppression of the J/ψ in lead–lead collisions section of the beauty quark.

particles in transverse-momentum (pT) space, and Ψn

are the orientation of the symmetry planes. v1, which is Noncentral collision An illustration of the evolving energy density of the QGP expected to be negligible at mid-rapidity, i s “d i r e c t e d flo w” via both elastic (collisional) and inelastic (gluon radiation) originating from the thermally expanding medium at processes. Low-momentum HF quarks are swept along re l at i ve l y lo w t r a n s ve r s e mome nt a t y pic a l l y e x h i bit flo w created in a noncentral collision. Pressure gradients act on the initial geometrical towards a single maximum, while v2 and v3 signal elliptic anisotropy to create a final velocity field (arrows), which may be decomposed into and triangular flows. The LHC’s impressive luminosity w it h t h e flo w o f t h e m e d iu m, p a r t i a l l y t h e r m a l i s i n g with coefficients that increase with transverse momentum. elliptic (yellow), triangular (teal) and higher order components. Hydrodynamic has allowed ALICE to measure significant values for the it via multiple interactions. The thermalisation time is Fa s t e r p a r t ic le s a l s o i nt e r a c t w it h t h e m e d iu m, b ut m i g ht inversely proportional to the particle’s mass, and so a not reach thermal equilibrium. For these particles, an calculations were performed using the MUSIC soft ware package. flow oflight-flavour hadrons up to v9 (see “Light-flavour flow” fig ure). h i g h e r d e g r e e o f t h e r m a l i s at io n i s e x p e c t e d for c h a r m t h a n azimuthal anisotropy develops due to the shorter length however, measurements at RHIC revealed that the QGP for beauty. Subsequent hadronisation brings additional of medium they traverse along the symmetry plane, but it complexity: as colour-charged quarks arrange themselves is not as large, and anisotropy coefficients are expected to has a simplifying property: it is a near perfect fluid, with The importance of being heavy in colour-neutral hadrons, extra contributions to their f a l l w it h i n c r e a s i n g t r a n s v e r s e m o m e nt u m. W h e n t h e r m a l a very low viscosity, as indicated by observations of the The bulk of the QGP is composed of thermally produced flow arise from the influence of the surrounding medium e q u i l i br iu m i s a c h ie v e d, it i m pr i nt s t h e s a m e v e lo c it y fie ld highest collective flows allowable in viscous hydrodynamic gluons and light quarks. By contrast, thermal HF pro- when t hey coalesce w it h nearby light quarks. to all particles: the result is a mass hierarchy wherein simulations. More precisely, its shear viscosity-to-entropy duction is negligible as the typical temperature of the In the past two years, the ALICE collaboration has h e a v ie r p a r t ic le s e x h i bit lo w e r flo w c o e ffic ie nt s for a g iven ratio – the generalisation of the non-relativistic kinematic system created in heavy-ion collisions is a few hundred measured the elliptic and triangular flow coefficients transverse momentum. viscosity – appears to be only a little above the conjectured MeV – significantly below the mass of a charm or beauty of HF hadrons with open and hidden charm and beauty. D mesons are the lightest and most abundant hadrons quantum limit of 1/4π derived using holographic gravity quark–antiquark pair. HF quarks are instead created in The results are currently unique in both scope and formed from a heavy quark, and are key to understan - (AdS/CFT) duality. As the QGP is a near-perfect fluid, its quark–antiquark pairs in early hard-scattering processes transverse-momentum coverage, and depend on the ding the dynamics of charm quarks in the collision. expansion can be modelled using a few local quantities on shorter timescales than the QGP formation time, and simultaneous reconstruction of thousands of particles A substantial anisotropy is observed for D mesons in Heavy quarks such as energy density, velocity and temperature. experience the whole evolution of the system. in the ALICE detectors (see “ALICE in action” panel). In non-central collisions (see “Elliptic flow” figure). As are powerful In noncentral heavy-ion collisions, the overlap region Heavy quarks are therefore powerful probes of properties eac h c a s e, t he s e HF flow s s hou ld b e c omp a re d to t he flow e x p e c t e d, t h e m e a s u r e d p dependence is similar to that probes of between the two incoming nuclei has an almond shape, of the QGP. As they traverse the medium, they interact with T of the abundant light-particle species such as charged for light particles, suggesting that D mesons are strongly properties which naturally imprints a spatial anisotropy to the initial its constituents, gaining or losing energy depending on . Within the hydrodynamic description, particles affected by the surrounding medium, participating in of the QGP state of the system: the QGP is less elongated along the their momenta. High-momentum HF quarks lose energy

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FEATURE QUARK–GLUON PLASMA ALICE

ALICE Pb–Pb, √s = 5.02 TeV 0.30 NN ALICE Pb–Pb, √s NN = 5.02 TeV centrality 30–50% 0.2 centrality 0–10% data TAMU π± π± prompt D prompt D 0.20 inclusive J/ψ inclusive J/ψ

ALICE/arXiv:1905.09216/arXiv:1504.00670 b → e 2 v ϒ(1S) 5–60% 0.1 3 v 0.10

0.00 0

2610 14 18 2 610 14 18

pT [GeV] pT [GeV]

Elliptic flow ALICE measurements of differential elliptic-flow coefficients for Triangular flow ALICE measurements of differential charged pions, D mesons, J/ψ mesons, electrons from beauty-hadron decays and triangular-flow coefficients for charged pions, D mesons ϒ(1S) mesons in semi-central (30–50% centrality) lead–lead collisions at 5.02 TeV. and J/ψ mesons in central (0–10% centrality) lead–lead Predictions from the TA MU model of HF transport are plotted for comparison. collisions at 5.02 TeV.

the collective motion of the QGP and reaching a high heavy quark sector (see “Triangular flow” figure). These degree of thermalisation. J/ψ mesons, which do not con- measurements of a triangular flow of open- and hidden- tain light-flavour q u a r k s, a l s o e x h i bit s i g n i fic a nt p o s it i v e c h a r m m e s o n s p o s e n e w c h a l le n g e s t o m o d e l s d e s c r i bi n g

e l l i p t ic flo w w it h a s i m i l arp T shape. Open beauty hadrons, HF interactions in the QGP: models now need to account whose mass is dominated by the b quark, are also seen not only for the properties of the medium and the transport to flow, and in the low to intermediate p region, below of the HF quarks through it, but also for fluctuations in the T RELIABLE 4 GeV, an apparent mass hierarchy is seen: the lighter initial conditions of the heavy-ion collisions. the particle, the greater the elliptic flow, as expected in In the coming years, measurements of HF flow will a hydrodynamical description of QGP evolution. Above continue to strongly constrain models of the QGP. It is UNDER ALL 6 GeV, the elliptic flows of the three particles converge, now clear that charm quarks take part in the collective perhaps as a result of energy loss as energetic partons motion of the medium and partially thermalise. More CONDITIONS. move through the QGP. In contrast to the other particles, data is needed to ma ke fir m conclusions about open and ϒ mesons do not show a ny sig n i fic a nt el l ipt ic flow. Th is hidden beauty hadrons. All four LHC experiments will is not surprising as the transverse momentum of peak s t ud y h o w h e a v y q u a r k s d i ff u s e i n acolour-deconfined and Heading into the unknown to open new horizons elliptic flow is expected to scale with the mass of the hydrodynamically expanding medium with the greater demands reliable tools. Help turn your resarch particle according to the hydrodynamic description of luminosities set to be delivered in LHC Run 3 and Run 4. goals into reality. the evolution of the QGP – for ϒ mesons that should be C u r r e nt l y o n g oi n g up g r a d e s t o A L IC E w i l l e x t e n d it s u n iq ue Vacuum valve solutions and bellows b e yo n d 10 G eV, w h e r e t h e u n c e r t a i nt ie s a r e c u r r e nt l y l a r g e. advantages in track reconstruction at low momenta, and from VAT provide unfailing reliability Theoretical descriptions of elliptic flow are also making upgrades to LHCb will allow this asymmetric experiment progress. Models of HF flow need to include a realistic to study non-central c ol l i s io n s i n Ru n 3. I n t h e n e x t lo n g and enhanced process safety – h yd r o d y n a m ic e x p a n s io n o f t h e Q GP, t h e i nt e r a c t io n o f t h e shutdown of the LHC, upgrades to CMS and ATLAS will under all conditions. h e a v y q u a r k s w it h t h e m e d iu m v i a c ol l i s io n a l a n d r a d i at i v e t h e n e x t e n d t h e i r a l r e a d y i m pr e s s i v e flo w m e a s u r e m e nt s processes, and the hadronisation of heavy quarks via both t o b e c o m p e t it i v e w it h A L IC E i n t h e c r uc i a l lo w t r a n s v e r s e Currently f r a g m e nt at io n a n d c o a le s c e n c e. For e x a m ple, t h e “TA M U” momentum domain, inching us closer to understanding ongoing model describes the measurements of the D mesons and b o t h t h e e a rl y u n i v e r s e a n d t h e p h a s e d i a g r a m o f q u a nt u m electrons from beauty-hadron decays reasonably well, chromodynamics.  upgrades but shows some tension with the measurement of J/ψ at to ALICE i nt e r m e d i at e a n d h i g h t r a n s v e r s e m o m e nt a, p e r h a p s i n d i- Further reading will extend cating that a mechanism related to parton energ y loss is ALICE Collab. 2021 Phys. Lett. B 813 136054 (arXiv2005.11131). its unique not included. ALICE Collab. 2020 arXiv2005.11130 advantages (accepted by Phys. Rev. Lett.). in track Triangular flow ALICE Collab. 2020 JHEP 10 141 (arXiv:2005.14518). reconstruction T r i a n g u l a r flo w i s o b s e r v e d for D a n dJ/ψ mesons in central ALICE Collab. 2020 JHEP 05 085 (arxiv:2002.00633). at low collisions, demonstrating that energy-density fluctua- ALICE Collab. 2019 Phys. Rev. Lett. 123 192301 momenta tions in the initial state have a measurable effect on the (arXiv:1907.03169).

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FEATURE SYSTEMS ENGINEERING INTERCEPTING THE BEAMS From targets to absorbers, beam-intercepting devices are vital to CERN’s accelerator complex. Marco Calviani describes the major upgrades taking place to prepare for the high-luminosity LHC, and the challenges posed by future projects. M Brice & J Ordan/CERN-PHOTO-202103-037-7M Brice magine standing in the LHC tunnel when the machine O-202010-134-24 T N-PHO n/CER Orda J is operating. Proton beams are circulating around the I27 km ring more than 11,000 times per second, collid- ing at four points to generate showers of particles that are recorded by ATLAS, CMS, ALICE, LHCb and other detectors. After a few hours of operation, the colliding beams need to b e d i s p o s e d of to a l lo w a ne w p hy sic s fi l l. O p e r ator s i n t he CERN control centre instruct beam-transfer equipment to shunt the circulating beams into external trajectories that transport them away from the cryogenic superconducting magnets. Each beam exits the ring and travel for 600 metres in a straight line before reaching a compact cavern housing a large steel cylinder roughly 9 m long, 70 cm in diameter and containing about 4.4 tonnes of graphitic material. Huge forces are generated in the impact. If you could witness the event up close, you would hear a massive “bang” – like a bell – generated by the sudden expansion and successive contraction of the steel shell. What you will have witnessed is a beam-intercepting s y s t e m i n a c t io n. O f c o u r s e, e x p e r ie n c i n g a b e a m d u m p i n person is not possible, due to the large amount of radiation generated in the impact, which is one of the reasons why access to high-energy accelerators is strictly forbidden during operation. Beam-intercepting systems are essential devices designed to absorb the energy and power of a particle beam. Generally, they are classified in three categories depending on their use: particle-producing devices, such as targets; systems for beam cleaning and control, such as collimators or scrapers; and those with safety func- tions, such as beam dumps or beam stoppers. During the current long-shutdown 2 (LS2), several major projects have been undertaken to upgrade some of the hundreds End of the line The upgraded LHC beam dump, capable of absorbing 560 MJ of of beam-intercepting systems across CERN’s accelerator Structural integrity The new internal beam dump being installed inside its shielding in October 2020. kinetic energy in a period of 86 μs, installed in its shielding in March 2021. complex, in particular to prepare the laboratory for the high-luminosity LHC era. In general, the energy deposited in beam-intercepting the structure. To reach a sufficient attenuation, due to such as pure lead for the generation of neutrons at the devices is directly proportional to the beam energy, its the high energy of the beams in CERN’s accelerators, we n_TOF facility or iridium and tantalum for the generation Withstanding stress intensity and the beam-spot size, as well as to the den- need devices that in some cases are several metres long. of antiprotons at the (AD) facility. Beam-intercepting devices have to withstand enormous sity of the absorbing material. From the point of view of Beam-intercepting devices must be able to withstand mechanical and thermally-induced stresses. In the case materials, this energy is transformed into heat. In a beam routine operation and also accident scenarios, where they Preparing for HL-LHC of the LHC beam dump, for example, upgrades of the LHC dump, for example, the collision volume (which is usually serve to protect more delicate equipment such as cryomag- The LHC Injectors Upgrade (LIU) Project, which was injectors will deliver a beam which at high energy will much smaller than the beam-intercepting device itself) nets. Amongst the many challenges that need to be faced launched in 2010 and for which the hardware was installed have a kinetic energy equivalent to 560 MJ during LHC Run is heated to temperatures of 1500 C or more. This heat are operation under ultra-high-vacuum conditions, and during LS2, will allow beams with a higher intensity and 3, roughly corresponding to the energy required to melt causes the small volume to try to expand but, because the maintaining integrity and functionality when enduring a smaller spot size to be injected into the LHC. This is a THE AUTHOR 2.7 t o n n e s o f c o p p e r. Re le a s e d i n a p e r io d o f ju s t 86 μs, t h i s surrounding area has a much lower temperature, there is energy densities up to several kJ/cm3 or power densities up precondition for the full execution of the High-Luminosity 3 Marco Calviani cor responds to a pea k power of 6.3 TW or, put differently, no room for expansion. Instead, the hot volume pushes to several MW/cm . For physics applications, optimisation LHC (HL-LHC), which will enable a large increase in the CERN. 8.6 billion horse power. against the colder surrounding area, risking breaking processes have led to the use of low-strength materials, integrated luminosity collected by the experiments. To

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FEATURE SYSTEMS ENGINEERING FEATURE SYSTEMS ENGINEERING M Brice/CERN-PHOTO-202009-112-4 ranCRNPOTO-201911-382-21 T N-PHO n/CER Orda J materials were developed at CERN in collaboration with European industry, while for the latter, dedicated molybdenum carbide-graphite composites were developed, again in collaboration with European firms. For these cases, more than 30 new collimators have been built and installed in the SPS and LHC during LS2 (see “New collimators” image). M Brice/CERN-PHOTO-202007-102-3M LHC beam-dump upgrades Several challenges associated with the LHC beam dump system had to be overcome, especially on the dump-block itself: it needs to be ready at any time to accept protons, from injection at 450 GeV up to top energy (6.5 TeV, with up to 7 TeV in the future); it must be reliable (~200 dump events per year); and it must accept fast-extracted beams, g iven t hat t he ent ire LHC r ing is empt ied in just 86 μs. At 560 MJ, the projected stored beam energy during Run 3 will also be 75% higher t han it w as during Run 2. The dump core (around 8 m long) consists of a sand- wich of graphitic materials of sufficiently low density to limit the temperature rise – and therefore the resulting New collimators Left: new dispersion-suppressor collimators being installed near ALICE in 2020, where they will clean beam losses at the HL-LHC. thermal-induced stresses – in the material (see “End of Right: checks during collimator installation in one of the SPS-to-LHC transfer lines in November 2019, as part of the LHC Injector Upgrade Project. t h e l i n e” i m a g e). T h e g r a p h it e i s c o nt a i n e d i n a 1 2 mm-thick special stainless-steel grade (see “Dump upgrades” image) safely protect sensitive equipment in the accelerator chain, heat through the contact with the jacket; to maximise and the assembly is surrounded by shielding blocks. Dump upgrades Upgraded LHC external dumps with new instrumentation, beam the project required a series of new devices in the injec- the thermal conductivity at the interfaces between the Roughly 75% (±430 MJ) of the energy that gets deposited windows and support systems being fitted into their new frames, ready for installation. tor complex from the PS Booster to the SPS, including stainless-steel cooling pipes and the copper alloy, these by either electromagnetic shower and ionisation losses S S Hertzog/CERN-PHOTO-202101-003-11 new beam-intercepting devices. One example is the new materials are diffusion-bonded by means of hot isostatic of hadrons and muons is deposited in the graphite, while SPS internal beam dump, the so-called TIDVG (Target pressing. The entire core is embedded in an air-cooled, around 5% (±25 MJ) is deposited in the thin steel vessel, Internal Dump Vertical Graphite), which was installed in seamless 15 mm-thick stainless-steel hollow cylinder. Due and the remaining energy is deposited in the shielding straight-section five of the SPS during 2020 (see “Struc- to the high activation of the dump expected after operation, a s s e m bl y. D e s pit e t h e v e r y lo w d e n s it y (1.1 g/cm3) employed tural integrity” image). The main challenge faced for this in addition to the first cast-iron shielding, the assembly in the middle section of the core, temperatures up to 1000 C device was the need to dissipate a large amount of power is surrounded by a massive, multi-layered external shield h a v e b e e n r e a c h e d d u r i n g Ru n 2. F r o m Ru n 3, t e m p e r at u r e s from the device rapidly and efficiently to avoid reaching comprising an inner layer of 50 cm of concrete, followed up to 1500 C will be reached. These temperatures could temperatures not acceptable by the beam-dump materials. by 1 m of cast iron and an external layer 40 cm of marble. be much higher if it were not for the fact that the beam is The TIDVG is used to dispose of the SPS circulating beam Marble is used on the three sides accessible by personnel to “painted” on the face of the dump by means of dilution whenever necessary, for example in case of emergency minimise the residual dose rate in the vicinity after short k ic k e r s s it u at e d hu n d r e d s o f m e t r e s up s t r e a m. T h e d u m p during LHC beam-setup, filling ormachine-development cool-down times. must also guarantee its structural integrity even in the periods, and to dispose of the part of the beam dedi- case of failures of t hese dilut ion systems. cated to fixed-target experiments that remains after the Collimator system upgrades Although the steel vessel is responsible for absorbing just slow-extraction process. Aiming at reducing the energy Beam collimators and masks are essential components in 5% of the deposited energy, the short timescales involved density deposited in the dump core’s absorbing material accelerator systems. They act as intermediate absorbers lead to a semi-instantaneous rise in temperature of more (and hence minimising the associated thermo-mechanical and dilutors of the beam in case of beam losses, minimis- than 150 C, generating accelerations up to 2000 g and forces stresses), the beam is diluted by kicker magnets, produc- ing the thermal energy received by components such as of several hundred tonnes. Following the operational expe- ing a sinusoidal pattern on the front of the first absorbing superconducting magnets (leading to quench) or delicate rience during LHC Run 1 and Run 2, during LS2 several block. The dump is designed to absorb all beam energies materials in the LHC experiments. The other function of the upgrades have been implemented on the dump. These in the SPS, from 14 GeV (injection from the PS) to 450 G eV. collimators is to clean up the halo of the beam, by removing include complex instrumentation to yield information and With respect to the pre-LS2 device, the beam power to be particles moving away from the correct orbit. Collimators operational feedback during Run 3, until 2025. In the later absorbed by the dump will be four-times higher, with an generally consist of two jaws – moveable blocks of robust HL-LHC era, the dump will have to absorb an additional The LHC average power of 300 kW. To reduce the local energy deposi- materials – that close around the beam to clean it of stray 50% more energy per dump than during Run 3 (up to 750 MJ/ Injector tion whilst maintaining the total required beam absorption, particles. More than 100 of these vital devices are placed dump), presenting one of numerous beam-interception Neutron production target Welding of the upstream cover and proton window Upgrade the length of the new dump has been increased by 70 cm, around the LHC in critical locations. c hallenges to be faced. on n_TOF’s third generation lead-based neutron spallation target. leading to a 5 m-long dump. The dump blocks are arranged The jaw materials can withstand extreme tempera- Project will so that the density of the absorbing materials increases tures and stresses (resulting in deposited energy densities Fixed-target challenges 7 kJ/cm3 and temperatures up to 2500 C are reached in allow beams as the beam passes through the device: 4.4 m of isostatic up to 6 kJ/cm3), while maintaining – at least for the LHC Beyond the LHC, challenging conditions are also refractory materials such as iridium, tantalum and tung- with a higher graphite, 20 cm of a molybdenum alloy and 40 cm of pure collimators – good electrical conductivity to reduce the encountered for antiproton production at CERN’s Anti- s t e n. Suc h i nt e n s e e n e r g y d e n s it ie s a n d t h e l a r g e g r a d ie nt s intensity and tungsten. This ensures that the stresses associated with the impedance contribution to the machine. Several develop- proton Decelerator (AD), which serves several antimat- resulting from the very small transverse beam size generate a smaller resulting thermal gradients are kept within acceptable val- ments were incorporated in the SPS-to-LHC transfer line ter experiments. In this case, high-density materials large thermal stresses and produce damage in the target spot size to be ues. The core of the component, which receives the highest collimators built in the framework of the LIU project, as are required to make sources as point-like as possible material, which must be minimised to maintain the reli- injected into thermal load, is cooled directly by a dedicated copper-alloy well as in the LHC collimators for the HL-LHC. For the for- to improve the capture capabilities of the downstream ability of the AD’s physics programme. To this end, a new the LHC jacket surrounding the blocks, which can only release their mer, dedicated and extremely robust 3D carbon-composite magnetic-horn focusing system. Energy densities up to air-cooled antiproton production target will be installed

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FEATURE SYSTEMS ENGINEERING FEATURE SYSTEMS ENGINEERING

operation. But how do we know that new devices will fulfill beams or electrons impacting on a target, depending on average power deposited on target (305 kW) also creates their function successfully once installed in the machine? the scheme under consideration. For the former, beams of a challenge for heat removal. A prototype target was built CERN’s HiRadMat facility, which allows single proton pulse several MW could collide on a production target, which will and tested at the end of 01, at one tenth of the nominal testing using a high-intensity beam from the SPS, is one have to be very effi cient to produce muons of the required power but able to reach the equivalent energy densities solution. Extremely high energy densities can be reached m o m e nt a w h i le b e i n g s u ffi c ie nt l y r e l i a ble t o o p e r at e w it h- and thermal stresses (see Beam-dump facility” image). in test materials and in complex systems, allowing the out failure for long periods. The muon collider target and experimental teams to investigate – in a controlled man- front-end s y s t e m s w i l l a l s o r e q u i r e m a g n e t s a n d s h ie ld i n g Human eff orts ner – the behaviour of materials or complex mechanical to b e lo c ate d qu ite c lose to t he pro duc t ion t a rget a nd w i l l The development, construction and operation of successful

J Ordan & S Herztog/CERN-PHOTO-201905-140-1 systems when impacted by proton (or ion) beams. Dur- have to cope with radiation load and heat deposition. These beam-intercepting d e v ic e s r e q u i r e e x t e n s i v e k n o wle d g e a n d ing the past few years, the facility was heavily employed challenges will be tackled extensively in the next few skills, ranging from mechanical and nuclear engineering, by both CERN and external teams from laboratories such years, both from a physics and engineering perspective. to physics, vacuum technologies and advanced production as STFC, Fermilab, KEK and GSI, testing materials from As one of the front-runner projects in the Physics Beyond techniques. Technicians also constitute the backbone of graphite to copper and iridium across the whole spectrum Colliders initiative, the proposed Beam Dump Facility at the design, assembly and installation of such equipment. of densities (see “Material integrity test” image). To be CERN would require the construction of a general-purpose I nt e r n at io n a l e x c h a n g e s w it h e x p e r t s i n t h e fi e ld s a n d w it h able to correctly predict the behaviour of materials when high-intensity and high-energy fi x e d - t a r g e t c o m ple x, i n i- laboratories working with similar challenges is essential, as impacted by protons and other charged particles, a full tially foreseen to be exploited by the Search for Hidden is cross-discipline collaboration, for example in aerospace, understanding of thermo-physical and material properties Particles (SHiP) experiment. At the heart of the instal- nuclear and advanced materials. In addition, universities is mandatory. Examples of critical properties include the lation resides a target/dump assembly that can safely provide key students and personnel capable of mastering c o e ffic ie nt o f t h e r m a l e x p a n s io n, h e at c a p a c it y, t h e r m alnd absorb the full high-intensity 400 GeV/c SPS beam, while a n d d e v e lo pi n g t h e s e t e c h n iq ue s b o t h at C E R N a n d i n C E R N’s Successful electrical conductivity as well as the Young’s modulus and maximising the production of charm and beauty mesons member states’ laboratories and industries. This intense yield strength, as well as their temperature dependence. and using high-Z materials, such as pure tungsten and multidisciplinary eff ort is vital to successfully tackle the beam Dealing with radiation damage is becoming increasingly molybdenum alloy, to reduce muon background for the challenges related to current and future high-energy and intercepting Material integrity test Preparation for irradiation of graphite and copper alloy important as facilities move to higher beam intensities downstream experiment. The nature of the beam pulse high-intensity facilities and infrastructures, as well as to devices require for the HL-LHC injection dump (TDIS) at the HiRadMat facility in 2018. and energies, presenting potential show-stoppers for some induces very high temperature excursions between pulses develop systems with broader societal impact, for example extensive beam-intercepting devices. To better understand and (up to 100 C), leading to considerable thermally induced in X-ray synchrotrons, medical linacs, and the production knowledge predict the radiation response of materials, the RaDIATE stresses and long-term fatigue considerations. The high of radioisotopes for nuclear medicine.  a nd sk i l l s collaboration was founded in 2012, bringing together the high-energy physics, nuclear and related communities. The collaboration’s research includes determining the effect of high-energy proton irradiation on the mechanical prop- erties of potential target and beam-window materials,

J Ordan/CERN-PHOTO-201808-199-6 and developing our understanding via micro-structural studies. The goal is to enable accurate lifetime predictions for materials subjected to beam impact, to design robust components for high-intensity beams, and to develop new materials to extend lifetimes. CERN is partner to this col- laboration, as well as Fermilab, STFC/UKRI, Oak Ridge, KEK, Pacific Northwest National Laboratory, and other institutions and laboratories worldwide.

Future projects High-energy physics laboratories across the world are pur- suing new energy and/or intensity frontiers, either with hadron or lepton machines. In all cases, whether collider physics or fixed-target, neutrino or beam-dump experi- Beam-dump facility Installation of the tantalum-clad pure tungsten block ments, beam-intercepting devices are at the heart of accel- in the Beam Dump Facility prototype target assembly, before testing with proton erator operations. For the proposed 100 km-circumference beam, in 2018. (FCC), several challenges have already been identified. Owing to the small emittances in the antiproton target area this year. Similar challenges and high luminosities involved in a first electron–positron are faced when producing neutrons for the n_TOF facility: FCC phase, the positron source system, and its target and in this case a new nitrogen-cooled pure lead spallation capture system, will require dedicated R&D and testing as target weighing roughly 1.5 tonnes will be commissioned well as the two lepton dumps. FCC’s proton–proton phase, this year, ready to produce neutrons spanning 11 orders further in the future, will draw on lessons from the HL-LHC of magnitude in energy, from 25 meV to several GeV (see operation, but it will also operate at uncharted energy den- “Neutron production target” image). sities for beam-intercepting devices, both for beam cleaning Reliability is a key aspect in the construction of and shaping collimators as well as for the beam dumps. beam-intercepting devices, not just because machine oper- The recently launched muon-collider initiative, mean- ation strongly depends on them, but because replacing while, will require a target system capable of providing devices is not easy due to their residual radioactivation after copious amounts of muons generated either by proton

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FEATURE FACILITIES MSU photo archive photo MSU SDD PHYSICS Silicon Drift Detectors for Science at the Speed of Light FLIES Technologically Advanced Silicon Drift Detectors HIGH Exceptional Rise Time — Rise times <25 ns Outstanding Throughput — Output count rates >5 Mcps per channel Superior Energy Resolution — Energy resolution <230 eV at 3 Mcps (OCR) AT SINP Unique Sensor Thickness — Thickness available 0.5 mm, 1.0 mm and 2.0 mm Eduard Boos and Victor Savrin look The VORTEX® range Silicon Drift Detectors, available with a selection of configurations including back at 75 years of developments at Russia’s Skobeltsyn Institute Sensor Thickness — 0.5, 1.0 and 2.0 mm of , which Active Areas — 50, 65 and 100 mm2 range from pioneering Probe Lengths — From 60 to over 600 mm experiments to participation in Sensor Arrays and Designs — Single, Multiple, Planar, Focused Close neighbours The main building of SINP MSU (foreground) against the the LHC-experiment upgrades. background of Moscow State University and its spire. Environments — Air, vacuum, UHV and He he Skobeltsyn Institute of Nuclear Physics (SINP) granted approval to build a set of accelerators and a special Number of Sensors — Single VORTEX® EX and EM SDD was established at Lomonosov Moscow State Uni- installation for studying extensive air showers (EASs). The T versity (MSU) on 1 February 1946, in pursuance of first accelerator built there was a 120 cm cyclotron, and — Three VORTEX® ME-3 SDD a decree of the government of the USSR. SINP MSU was its first outstanding scientific achievement was the dis- — Four VORTEX® ME-4 SDD created as a new type of institute, in which the principles covery by A F Tulinov of the so-called “s h a dow e ffe c t” i n of integrating higher education and fundamental sci- nuclear reactions on single crystals, which makes it possible — Seven VORTEX® ME-7 SDD ence were prioritised. Its initiator and first director was to study nuclear reactions at ultra-short time intervals. Soviet physicist Dmitri Vladimirovich Skobeltsyn, who was Significant scientific successes were associated with the known for his pioneering use of the cloud chamber to study commissioning of a unique installation, the EAS-MSU, at the Compton effect in 1923 – aiding the discovery of the the end of the 1950s for the study of ultra-high-energy Customization and discussions — contact: [email protected] positron less than a decade later. cosmic rays. Several results were obtained through a new It is no coincidence that SINP MSU was established in the m e t h o d for s t ud y i n g E A S s i n t h e r e g io n o f 10 15–10 17 eV, lead- immediate aftermath of the Second World War, following ing to the discovery of the famous “knee” in the energy t he first use of nuc lea r weapons in conflic t. The inst it ute spectrum of primary cosmic rays . was created on the basis that it would train personnel who would specialise in nuclear science and technology, The after the country realised that there was a shortage of 1949 marked SINP MSU’s entrance into astrophysics and, specialists in the field. Thanks to strong leadership from in particular, satellite technology. The USSR’s launch of Skobeltsyn and one of his former pupils, Sergei Nikolaevich , Earth’s first artificial satellite, in 1957 gave Vernov, SINP MSU quickly gained recognition in the coun- Vernov, an enthusiastic experimentalist who had previ- t r y. A s s o o n a s 1949, t h e g o v e r n m e nt d e s i g n at e d it a le a d- ously researched cosmic rays in the Earth’s stratosphere, i n g re s e a rc h i n s t it ut e. B y t h i s t i m e a 72 cm cyclotron was the opportunity to study outer-atmosphere cosmic rays. already in use, the first to be used in a higher education This led to the installation of a Geiger counter on the institute in the USSR. S p ut n i k 2 s at e l l it e a n d a s c i nt i l l at io n c o u nt e r o n S p ut n i k 3, Skobeltsyn and Vernov continued with their high ambi- to enable radiation experiments. Vernov’s experiments on THE AUTHORS tions as they expanded the facility to the Lenin Hills, along S p ut n i k 2 e n a ble d t h e fi r s t d e t e c t io n o f t h e o ut e r r a d i at ion Eduard Boos with other scientific departments in MSU. Proposed in belt. However, this was not confirmed until 1958 by the and Victor Savrin Hitachi High-Tech Science America, Inc. www.hitachi-hightech.com/hhs-us/ 1949 a n d o p e n e d i n 1953, t h e n e w b u i ld i n g i n M o s c o w w a s US’s E x plor e r 1, w h ic h c a r r ie d a n i n s t r u m e nt d e s i g n e d a n d SINP MSU . 20770 Nordhoff St. Chatsworth, CA 91311 Email: [email protected] Tel: +44 747 1086 241 CERN COURIER MAY/JUNE 2021 45

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SINP MSU under the guidance of former director Mikhail extensions. Members of the department later went on to ive h rc a photo MSU Igorevich Panasyuk. This allowed fluorescence light radi- m a k e a s i g n i fic a nt c o nt r i b ut io n t o t h e c r e at io n ofaT ier-2 ated by EASs of ultra-high-e n e r g y c o s m ic r a y s t o b e m e a s- Grid computer segment in Russia for processing and storing

MSU photo a rc h ive u r e d for t h e fi r s t t i m e, a n dprompt-emission observations data from t he LHC detectors. of multi-wavelength gamma-ray b u r s t s. T h e le a d i n g r ole Over the past 35 years of research in the field of par- of the entire mission of the Lomonosov satellite belongs ticle accelerators at SINP MSU, research has moved from to t he current rector of MSU, Victor Sadov nic hy. the development of large accelerator complexes for fun- damental research, to now focusing on the creation and High-energy exploration production of applied accelerators for security systems, In 1968, under strong endorsement by Vernov and the industry and medicine. d i r e c t or o f a n e w Ru s s i a n a c c e le r at or c e nt r e i n P r o t v i n o, Anatoly Alekseyevich Longunov (who went on to be MSU Teaching legacy rector from 1977 to 1991), a department of high-energy T h r o u g h o ut it s 75 y e a r s, SIN P M SU h a s a l s o nu r t u r e d t h o u- physics was established under the leadership of V G sands of students. In 1961 a new branch of SINP MSU, the Shevchenko at SINP MSU, and the following year it was d e p a r t m e nt for nuc le a r r e s e a rc h, w a s e s t a bl i s h e d i n D u b n a. CERN collaboration A visit of former CERN Director-General Rolf Heuer decided that a high-energy laboratory would be estab- It became the basis for training students from the MSU (fourth from right) to Lomonosov Moscow State University in 2011. lished at MSU. Throughout the years to follow, collabo- p h y s ic s f a c u lt y i n nuc le a r p h y s ic s u s i n g t h e c a p a bi l it ie s o f rations with laboratories in USSR and across the world, t h e l a r g e s t i nt e r n at io n a l s c ie nt i fic c e nt r e i n Ru s s i a – J INR. between CERN and Russia concerning high-energy p h y s ic s including CERN, Fermilab, DESY and the Joint Institute The department, which is still going strong today, teaches and other domains of mutual interest. Looking even fur- for Nuclear Research (JINR), lead the department to be with a hands-on approach, with students attending lec- ther ahead, SINP MSU scientists are also working on the at t he forefront of t he field. t u r e s b y le a d i n g J IN R s c ie nt i s t s a n d t a k i n g p a r t i n pr a c t ic a l development of research programmes for future collider A t t h e e n d o f t h e 1970 s a c e nt r e w a s c r e at e d at SIN P M SU training held at t he JINR laboratories. projects such as the FCC, CLIC and ILC. Furthermore, the for bubble-chamber film analysis. At the time it was one The institute is currently participating in the upgrade institute is involved in the upcoming NICA Complex in of the largest automated complexes for processing and of the LHC detectors (CMS, ATLAS, LHCb) for the HL-LHC Russia, whic h plans to finish constr uct ion in 2022. a n a l y s i n g i n for m at io n f r o m l a r g e t r a c k i n g d e t e c t or s i n t h e project, as well as in projects within the Physics Beyond After 75 years, the institute is still as relevant as ever, c o u nt r y. I n c ol l a b or at io n w it h o t h e r i n s t it ut e s world w id e, Colliders initiative (e.g. NA64, SHiP). These actions are and whatever the next chapter of particle physics will be, s t a ff at t h e i n s t it ut e s t ud ie d s o f t h a d r o n ic pr o c e s s e s i nthe under the umbrella of a 2019 cooperation agreement SINP MSU w ill be involved.  energy range 12–350 GeV at a number of large facilities, including the Mirabelle Hydrogen Bubble Chamber and European Hybrid Spectrometer. Extensive and unique experimental data have been obtained on the characteristics of multiple hadron pro- ductions, including fragmentation distributions. Through- out the years, exclusive reaction channels, angular and momentum correlations of secondary particles, resonance production processes and annihilation processes were also i n v e s t i g at e d. T h e s e r e s u lt s h a v e m a d e it p o s s i ble t o r e l i a bl y test the predictions of phenomenological models, includ- ing the dual-parton model and the quark–gluon string Vernov’s legacy built by James Van Allen. Sputnik 3 confirmed the existence model, based on the fundamental theoretical scheme of On 28 April 2016 of an inner radiation belt, having received information dual-topological unitarisat ion. the Lomonosov from Australia and South America, as well as from For the first time in Russia, together with a number of satellite was sea-based stations. scientific and technical enterprises with the leading role of launched aboard Ve r n o v, w h o w a s S k o b e lt s y n’s s uc c e s s or a s SIN P d i r e c t or t h e SIN P M SU, a n i nt e g r at e d s y s t e m h a s n o w b e e n c r e at e d the Soyuz carrier in 1960–1982, later worked on the “Electron” and “Proton” for the development, design, mass production and testing rocket, marking series of , which studied the radiation-belt s t r uc- o f l a r g e s i l ic o n s ol id a n d m ic r o s t r i p d e t e c t or s. O n t h i s b a s i s, the first launch ture, energy spectra and temporal variations associated at the turn of the millennium a hadron–electron separator from the new w it h g e o m a g n e t ic a c t i v it y. T h i s le d t o pio n e e r i n g r e s u lt s o n w as built for t he ZEUS e x periment at HER A, DESY. Russian Vostochny the spectrum and composition of galactic cosmic rays, and T h e i n s t it ut e d e l v e d i nt o t h e or e t ic a l s t ud ie s i n 1983, w it h Cosmodrome. to the first model of radiation distribution in near-Earth the establishment of the laboratory of symbolic compu- space in t he USSR. tations in high-energy physics and, in 1990, the depart- SIN P M SU h a s c a r r ie d o n Ve r n o v’s c o s m ic le g a c y b y c o n- ment of theoretical high-energy physics. One of its most tinuing to develop equipment for satellites. Since 2005 striking achievements was the creation of the CompHEP the institute has developed its own space programme sof t w a re pac k age, w h ic h h a s re ce ive d g loba l re cog n it ion through the university satellites Tatiana-Universitetsky for its ability to automate calculations of collisions between and T at i a n a-2, a s w e l l a s t h e Ve r n o v s at e l l it e. T h e s e s at e l- element a r y pa r t ic les a nd t hei r decays w it h i n t he f r a me- lites led to new phenomena such as ultraviolet flashes from work of gauge theories. This is freely available and allows t h e at m o s p h e r e b e i n g d i s c o v e r e d. I n 2016 a t r a c k i n g s y s t e m p h y s ic i s t s (e v e n t h o s e w it h l it t le c o m p ut e r e x p e r ie n c e) t o for ultraviolet rays was installed on board the Lomon- c a lc u l at e c r o s s s e c t io n s a n d c o n s t r uc t v a r io u s d i s t r i b ut io n s o s o v s at e l l it e (s e e “Ve r n o v’s le g a c y” i m a g e), d e v e lo p e d at for collision processes within the Standard Model and its

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Muon g–2: the promise of a generation

The long-awaited g–2 result from CERN-PHOTO-7408101-1 Fermilab offers a moment to reflect on the perseverance and tight

collaboration required by theorists and experimentalists to deliver progress, write Themis Bowcock and Mark Lancaster.

It has been almost a century since Dirac formulated his famous equation, and Liverpool

U. 75 y e a r s since the first QED calculations by Schwinger, Tomonaga and Feynman were used to explain the small deviations ,, ,.... in hydrogen’s hyperfine structure. These "' calculations also predicted that devia- tions from Dirac’s prediction a = (g–2)/2,

where g is the gyromagnetic ratio e/2me, -2 -1 0 1 2 3 Input Power {dBm) Themis Bowcock, should be non-zero and thus “anoma- Pioneering The CERN g-2 storage ring, which entered operation in 1974. University of lou s”. The result is famously engraved Liverpool, is a on Schwinger’s tombstone, standing as the E821 collaboration delivered on its take into account the new results pro- member of the a monument to the importance of this promise, reporting results accurate to vided by LHCb’s recent RK measurement LHCb and Muon result and a marker of things to come. about 0.6 ppm. At the time this showed (see p17), which hint that muons might g–2 collaborations. In January 1957 Garwin and collab- a 2–3σ discrepancy with respect to the behave differently than electrons. There orators at Columbia published the first Standard Model (SM) – tantalising, but will inevitably be speculation over the measurements of g for the recently dis- far from conclusive. coming months about the right approach. Fermilab covered muon, accurate to 5%, followed Whatever one’s choice, muon g–2 is a two months later by Cassels and collab- Spectacular progress clear demonstration that theory and orators at Liverpool with uncertainties The theoretical calculation of g–2 made experiment must progress hand in hand. of less than 1%. Leon Lederman is cred- spectacular progress in step with exper- Perhaps the most important lesson ited with initiating the CERN campaign iment. Almost eclipsed by the epic 2012 is the continued cross-fertilisation and of g–2 experiments from 1959 to 1979, achievement of calculating the QED impetus to the physics delivered both at starting with a borrowed 83 × 52 × 10 cm contributions to five loops from 12,672 CERN and at Fermilab by recent results. Mark Lancaster, magnet from Liverpool and ending with Feynman diagrams, huge advances in The g–2 experiment, an international University of a dedicated storage ring and a precision calculating the hadronic vacuum polari- collaboration between dozens of labs

Manchester, is a of better than 10 ppm. sation contributions to aµ have been made. and universities in seven countries, has former Muon g–2 Why was CERN so interested in the A reappraisal of the E821 data using this benefited from students who cut their spokesperson and muon? In a 1981 review, Combley, Farley information suggested at least a 3.5σ dis- teeth on LHC experiments. Likewise, a member of the and Picasso commented that the CERN crepancy with the SM. It was this that students who have worked at the preci- Mu2e collaboration. results for aµ had a higher sensitivity to provided the impetus to Lee Roberts and sion frontier at Fermilab are now armed new physics by “a modification to the colleagues to build the improved muon g–2 with the expertise of making blinded photon or new couplings” by a experiments at Fermilab, the first results ppm measurements and are keen to see 2 factor (mµ/me) . Revealing a deeper inter- from which are described in this issue (see how they can make new measurements est, they also admitted “… this activity p7), and at J-PARC. Full results from the at CERN, for example at the proposed has brought us no nearer to the under- Fermilab experiment alone should reduce MUonE experiment, or at other muon

standing of the muon mass [200 times the aµ uncertainties by at least another experiments due to come online this that of the electron].” factor of three – down to a level that really decade (see p5). With the end of the CERN muon pro- challenges what we know about the SM. “It remains to be seen whether or not gramme, focus turned to Brookhaven Of course, the interpretation of the future refinement of the [SM] will call and the E821 experiment, which took up new results relies on the choice of theory for the discerning scrutiny of further

the challenge of measuring aµ 20 times baseline. For example, one could choose, measurements of even greater precision,” more precisely, providing sensitivity to as the Fermilab experiment has, to use concluded Combley, Farley and Picasso virtual particles with masses beyond the the consensus “International Theory Ini- in their 1981 review – a wise comment

reach of the colliders at the time. In 2004 tiative” expectation for aµ. One could also that is now being addressed.

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Standard SC Wire Types Product Applications Accelerator physicist and science communicator Suzie Sheehy discusses her work, her new book, NbTi Wires Magnetic Resonance Imaging and how to increase the appeal of a research career. Nb3Sn —Bronze Nuclear Magnetic Resonance Charles Henderson Photography Henderson Charles Nb3Sn —Internal Tin High Energy Physics How did you end up as an w as a first-year underg raduate. I have CuNi resistive matrix wires SC Magnetic Energy Storage accelerator physicist? always seen it as part of the process Somewhat accidentally, because I didn’t of being a scientist. Before my PhD Fine diameter SC Wires Medical Therapeutic Devices even know that being a researcher I worked in a science museum and, Aluminum clad wire Superconducting Magnets and Coils in physics was a thing you could be while at Oxford, I started an outreach Wire-in-Channel Crystal Growth Magnets until my second year of university. It programme called Accelerate! that Innovative composite wires Scientific Projects was around then that I realised that took live science shows to some 30,000 someone like me could ask questions students in its first two years and that didn’t have answers. That hooked is still running. From there, it sort my interest. My first project w as in of branched out. I did more public nuclear physics, and it involved using a lectures, but also a little bit of TV, radio “We deliver when you need us!” particle accelerator for an experiment. and some writing. I then attended the CERN summer www.SUPERCON-WIRE.com student programme, working on ATLAS, Any advice for physicists who want to whic h w as my first proper e x posure to get into communication? the technology of particle physics. When You need to build a portfolio, and it came to the time to do my PhD in demonstrate that you have a range of around 2006, I had the choice to either different styles, delivery modes and stay in Melbourne to do particle physics, use language that people understand. or go to Oxford, which had a strong The other thing that really helped accelerator programme. When I learned me was working with professional they were designing accelerators for organisations such as the Royal cancer treatment, it blew my mind! I Institution in London. It does take a took the leap and decided to move to the lot of time to do both your research Photodetector Modules other side of the world. and academic job well, and also do TRANSMISSION LINES, COAXIAL & WAVEGUIDE Focused non-linear integral optics, which is a the communication well. A lot of my for photon counting applications • What did you do as a postdoc? Suzie Sheehy focus of Fermilab at the moment. communication is about my research I was lucky enough to get an 1851 divides her time field – so luckily they enrich each PATCH PANELS & SPLITTERS Royal Commission Fellowship, which between her And now you’re back in the other. I think my communication has • allowed me to start an independent research groups medical arena? the potential to have a much bigger CUSTOMISED RF COMPONENTS Our range of photodetector research programme. It was a bit of a at the University Yes – a few years ago I started working societal impact than my research, so modules is available with 25mm bapt ism of fire, as I had been work ing of Oxford and with people from CERN and the UK I am very serious about it. The first and 30mm diameter low noise the University on compact medical accelerators for photomultipliers. These modules on medical machines but then moved time someone pointed a video camera consist of high speed electronics to high-intensity proton accelerators. of Melbourne. low- and middle-income countries. at me I was terrified. Now I can say and fast photomultipliers with low I was looking at fixed-field alternating Then in 2019 I felt the pull to return to what I want to say. We shouldn’t dark counts and can be supplied gradient accelerators and their Australia to grow accelerator physics underestimate how much the public with TTL or USB output or with application to things like accelerator- there. They have accelerators and wants to hear from real working dual output (TTL and USB). driven reactors. After a while I found facilities but didn’t have a strong scientists, so keeping a very strong New Compact 25mm Diameter Photomultiplier The range now include modules myself spending a lot of time building academic accelerator community, so I research base keeps my authenticity with over light detection capability. sophisticated simulations, and was am building up a group at Melbourne and credibility. getting a bit bored of computing. So I University that has a medical 9181B started a couple of collaborations with applications focus, but also looks at What is your work/life balance like? – some teams in Japan – one of which was other areas. After 20 years of pushing I am not a fan of the term “work/life using ion traps to mimic the dynamics for a proton therapy centre here, the balance” as it tends to imply that one Our wide range of products cover photomultipliers, light-tight housings, of particle beams at very high intensity. first one is now being built. is necessarily in conflict w it h t he HV supplies and associated custom built electronics. What I found really interesting is other. I think it’s important to set up www.exirbroadcasting.com how beams behave at a fundamental How and when did your career in a kind of work/life integration that level, and I am currently working on science communication take off? supports well-being while allowing Exir Broadcasting AB upgrading a small experiment called I was doing things like stage shows you to do the work you want to do. Industrigatan 17 - SE-242 31 Hörby - Sweden IBEX to test a new type of optics called for primary-school children when I When I was invited back to Melbourne +46 415 30 14 00 - [email protected] www.et-enterprises.com

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OPINION INTERVIEW

to build an accelerator group, I’d Leedale Katherine note, as I went through these stories just started a new research group in in t he field, of ten in t he biog raphies Oxford. I stepped down my teaching and the acknowledgments, I would end and we agreed that I would take up going down these rabbit holes of periods of sabbatical to spend time women whose careers were cut short in Melbour ne unt il I finished my because they got married and had to experiment. I have been so incredibly quit their job. It’s been lovely to have grateful to everyone on both sides the opportunity to learn that these for their understanding. Key to that women were there, and it wasn’t just has been learning how other people’s white men. e x pectat ions affect you and finding a w ay to filter t hem out and drive your Do you have a preference as to which own goals. Working in two completely collider should come next after the LHC? different t ime zones, it would be easy I think it should be one of the linear to work ridiculously long days, so I ones. The si ze of f ut ure circular have had to learn to protect my health. colliders and the timescales involved The hardest thing, and I think a lot are quite overwhelming, and you of early/mid-career researchers will have to wonder if the politics might relate to this, is that academia is an change throughout the project. infinite job: you w ill never do enough A linear machine such as the ILC for someone to tell you that you have is more ready to go, if the money done enough. The pressure always and will was there. But I also think feels like it’s increasing, especially there is value in the diversity of the when you are a post-doc or on tenure have a single direct female colleague. Reaching out technology. The scaling of SLAC’s track, or in the process of establishing With most people in my field being Sheehy delivering linear electron machine, for example, a new group or lab. You have to learn men, it’s likely that when choosing a a Friday Evening really pushed the industrialisation of how to take care of your mental health spea ker, for e xample, t he first person Discourse at the that accelerator technology – which and well-being so that you don’t burn we think of is male. Taking time to be Royal Institution. is part of the reason why we have out. With everything else that’s going well-networked with women in the 3 GHz elect ron accelerators now in on in the world right now, this is even field is incredibly important in that every hospital. There will be other more important. regard. Today, I find that creating implications to what we build, other the right environment means that than physics results – even though the You are active in trying to raise the people will seek out my research group decisions will be made on the physics. profile of women in physics. What because they hear it’s a nice place to does this involve on a practical level? be. Students today are much savvier W hat do you say to students There has been a lot of focus for many with this stuff – they can tell toxic considering a career in particle physics? years in getting more women into professors a mile away. I am trying I will answer that from the perspective subjects like physics. My view is that to show them that there is a way of of t he accelerator field, whic h is ver y whenever I meet young people they’re doing research that doesn’t involve the exciting. If you look historically, new interested already. In many countries horrible sides to it. Research is hard technologies have always driven the gender balance at undergraduate enough already, so why make it harder? new discoveries. The accelerator level is similar. So what’s happening field is going t hrough an interest ing instead is that we are pushing women Tell us about your debut book “technology discovery phase”, for and minorities out. My focus, within The Matter of Everything? example with laser-driven plasma my sphere of influence, is to make sure It’s published by Bloomsbury (UK/ accelerators, so there will be huge that the culture that I am perpetuating Commonwealth) and Knopf (US) and changes to what we are doing in and the values that I hold within is due out in early 2022. Its subtitle 10–15 years’ t ime t hat could blow t he my research groups are well defined is “The 12 experiments that made decisions surrounding future colliders and communicated. the modern world”, starting with out of the water. This happened in the I kind of pulled back from active the cathode-ray tube and going all 1960s in the era of proton accelerators, engagement in panel sessions and the way through to the LHC and where suddenly there was a new things like that a number of years what might come next. It’s told from technology and it meant you could ago, because I realised that the most the perspective of an experimental build machines with a much higher important way I can contribute is by physicist. What isn’t always captured energy with smaller magnets, and being the best scientist that I can be. in popular physics books is how science suddenly the people who took that risk The fact that I happen to have a public is actually done, but it’s very human to were the ones who ended up pushing profile is great in that it makes people feel like you’re failing in the lab. I also You have to t he field for w ard. I somet imes feel aware that people like me exist. One of delve into what first interested me in learn how to experimental and theoretical physicists the things that has helped me the most accelerators, specifically t he t hings take care of are slightly disconnected to what’s is to build a really great community that have emerged unexpectedly from your mental going on with accelerator physics now. of peers of other women in physics. these research areas. People think When making future decisions, people health and I t hin k for t he first seven or eight that Apple invented everything in the should attend accelerator conferences… years of my career, when imposter iPhone, but if it wasn’t for curiosity- well-being so it may influence their choices. syndrome was strong and I questioned driven physics experiments then it that you don’t if I fitted in, I realised that I didn’t wouldn’t be possible. On a personal burn out Interview by Matthew Chalmers.

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Next Gen Light Sources REVIEWS

Ca lculating t he curiosit y w indfa ll CERN-PHOTO-201804-088-10 Bastianin. A recent social cost–benefit The Economics of Big Science: Essays analysis of the HL-LHC, for example, by Leading Scient ists and Polic y ma kers conservatively estimates that every €1 Edited by Hans Peter Beck and of costs returns €1.2 to society, while a Panagiotis Charitos similar study concerning the FCC esti- Springer mates the benefit/cost ratio to be even higher, at 1.8. Florio argues that CERN and Recent decades have seen an emphasis big science more generally are ideal test- on the market and social value of funda- ing grounds for theoretical and empirical mental science. Increasingly, researchers economic models, while demonstrating must demonstrate the benefits of their the positive net impact that large colliders work beyond the generation of pure have for society. His 2019 book Investing scientific knowledge, and the cultural in Science: Social Cost-Benefit Analysis • High precision Dipoles and Multipole Electromagnets – laminated or solid • Ultra stable Modular Magnet power supplies benefits of peaceful and open interna- of Research Infrastructures (MIT Press) • Permanent Magnet based Dipoles • Power supplies for Super Conducting applications tional collaboration. explores this point in depth (CERN Cou- • Combined function magnets • Beam line systems This timely collection of short essays by rier September 2018 p51), and is another • Special magnets leading scientific managers and policy- must-read in this growing interdiscipli- makers, which emerged from a workshop nary area. Completing the series of essays

held during Future Circular Collider (FCC) on impact evaluation, Philip Amison of the Contact us about how we can benefit Your application utilizing our extensive competencies in accelerator technology - www.danfysik.com Week 2019, brings the interconnectedness Profitable place for international governance struc- UK’s Science and Technology Facilities of fundamental science and economics prototype? tures, adequate long-term funding, closer Council reviews the findings of a report into focus. Its 18 contributions range Advanced magnet engagement with industry, and method- published last year capturing the bene- from procurement to knowledge trans- R&D for a proposed ologies for assessing RI impact. All con- fits of CERN membership (CERN Courier fer, and from global-impact assessments future collider at tributors acknowledge the importance of September/October 2020 p9). to case studies from CERN, SKA, the ESS CERN, in 2018. this latter point. While physicists would The final part of the volume focuses and ESA, with a foreword by former CERN no doubt prefer to go back to the pre-Cold on the question “Who benefits from such Director-General Rolf Heuer. As such, it War days of doing science for science’s large public investments in science?”, constitutes an important contribution to sake, argues ESS director John Womersley, and addresses the contribution of big the literature and a guide for future pro- without the ability to articulate the soci- science to social justice and inequali- jects such as a post-LHC collider. oeconomic justifications of fundamen- ties. Carsten Welsch of the University As the number and size of research tal science as a driver of prosperity, jobs, of Liverpool/Cockcroft Institute argues infrastructures (RIs) has grown over the innovation, startups and as solutions to that fundamental science should not be years, describes CERN’s head of indus- challenges such as climate change and the considered as a distant activity, illus- try, procurement and knowledge trans- environment, it is only going to become trating the point convincingly via the fer, Thierry Lagrange, the will to push m or e d i ffic u l t for pr oj e c t s t o g e t f u n ding. approximately 50,000 particle acceler- the frontier of knowledge has required A future collider is a case in point. ators currently used in industry, medical significant additional public spending Johannes Gutleber of CERN and the FCC treatments and research worldwide. linked to the development and upgrade study describes several recent stud- The grand ideas and open questions in of high-tech instruments, and increased ies seeking to quantify the socioeco- particle physics and cosmology already maintenance costs. The socioeconomic nomic value of the LHC and its proposed inspire many young people to enter STEM returns to society are clear, he says. But successor, the FCC, with training and subjects, while technological spin-offs t h e s e b e n e fit s a r e n o t g e n e r a t e d a ut omat- industrial innovation emerging as the such as medical treatments, big-data ically: they require a thriving ecosystem most important generators of impact. handling, and radio-frequency tech- that transfers knowledge and technol- The rising interest in the type of RI ben- nology are also often communicated. ogies to society, aided by entities such Springer efits that emerge and how they can be Less well known are the significant but as CERN’s knowledge transfer group and maximised and redistributed to society, harder-to-quantify economic benefits business incubation centres. he writes, is giving rise to a new field of big science. This volume is therefore Multi-billion public investments in of interdisciplinary research, bringing essential reading, not just for govern- RIs are justified given their crucial and together economists, social scientists, ment ministers and policymakers, but multifaceted role in society, asserts historians and philosophers of science, for physicists and others working in director-general for research and inno- and policymakers. curiosity-driven research who need to vation in the European Commission Nowhere is this better illustrated than convey the immense benefits of their Margarida Ribeiro. She argues that new the ongoing programme led by economists work beyond pure knowledge. RIs need to be closely integrated into the at the University of Milan, described in two European landscape, with plans put in chapters by Florio Massimo and Andrea Matthew Chalmers editor.

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OPINION REVIEWS World Scientific Lectures on Accelerator Physics cases). The present reviewer could not help i c s o f c h a r g e d-p a r t i c l e b e a m s pr o v i d e t h e w o n d e r i n g a b o ut t h e m i s s e d p u n c h l i n e s. e s s e nt i a l s for u n d e r s t a n d i n g t h e pr o p e r- By Alexander Wu Chao Beginners and advanced students t ie s o f l e p t o n a n d f ut u r e v e r y-h i g h- e n e r g y ...the power in microwaves! World Scientific alike will find pleasure in striking hadron colliders. Lectures on Accelerator derivations of basic properties of sim- Physics also describes the necessary fun- A l e x C h a o, o n e o f t h e l e a d i n g pr a c t it i o n e r s ple physical systems by dimensional damentals of accelerator-based synchro- in the field, has written an introductory analysis. Students will also find the tron light sources, reac hing as far as t he textbook on accelerator physics. It is a presentation on the use of phase- principles of free-electron lasers lucid and insightful presentation of the (coordinate-momentum space) concepts and diffract ion-limited storage rings. ULTRA AVAILABLE principles behind the workings of mod- i n c l a s s ic a l m e c h a n ic s c a p a bl e o f c l e a r i n g A chapter on collective instability ern accelerators, touching on a multitude the fog in their heads. In particular, an intro duces some of the most important of aspects, from elegant mathematical insightful presentation of transverse and effects related to the stability of beams AMPLIFIERS concepts and fundamental electromag- longitudinal phase-space manipulation as multi-particle systems. A number of netism to charged-particle optics and the techniques provides modern-day exam- essential effects, including head–tail s t a bi l it y o f c h a r g e d p a r t i c l e b e a m s. A t t h e pl e s o f a d v a n c e d d e s i g n s. F u r t h e r m or e, a n instability and the Landau damping same time, numerous practical examples important discussion on “symplecticity” mechanism, which play a crucial role FOR ACCELERATOR & illustrate key concepts employed in the a n d L i o u v i l l e’s t h e or e m – i d e a s t h a t y i e l d in the operation of present and future most advanced machines currently in powerful constraints on the evolution of particle accelerators and colliders, are operation, from high-energy colliders dynamical systems – lets physics ideas explained with great elegance. The to free-electron lasers. s t a n d o ut a g a i n s t t h e b a c k g r o u n d o f for- b e g i n n e r, a r m e d w it h t h e i n s i g ht s g a i n e d MEDICAL APPLICATIONS The author is careful to keep the text mal . The discussion should from these lectures, is well advised to r i g or o u s, y e t n o t t o o v e rl o a d it w it h for m a l help students avoid imagining typical turn to Chao’s classic 1993 text Physics of derivations, and exhibits a keen sense for unphysical ideas such as beams focused Collective Beam Instabilities in High Energy TMD in collaboration with Rosatom - NIITFA is now fi n d i n g s i m pl e, c o n v i n c i n g a r g u m e nt s t o t o i n fi n it e s i m a l l y s m a l l d i m e n s io n s: t h e Accelerators for a more in-depth treatment able to offer revolutionary, ultra-available RF solid state i nt r o d u c e t h e b a s i c p h y s i c s. A l a r g e nu m- infamous “death rays” first dreamt up in of these phenomena. b e r o f h o m e w or k pr o bl e m s (m o s t o f t h e m the 1920s and 1930s. The treatment of the T h i s b o o k i s a v e r it a bl e “A l l y o u w a nt e d amplifiers for scientific and medical applications. with solutions) facilitate the stated aim to This book is a stability criteria for linear and non-linear to know about accelerators physics but stimulate thinking. The variety of these veritable “All systems, in the latter case introducing the were afraid to ask”. It is a compilation of Innovative power combining and control system results in: is the fruit of extensive teaching expe- you wanted n o t io n o f d y n a m ic a l a p e r t u r e (t h e s t a ble ideas, and can be used as a less dry com- rience. The book assumes only a basic to know about r e g i o n o f p h a s e s p a c e i n a c i r c u l a r a c c e l- panion to yet another classic compilation, understanding of special relativity and accelerators erator), serves as a concrete illustration in this case of formulas: the Handbook of • Ultra-compact systems, typically one Applications: electromagnetism, while readers with of these deep and beautiful concepts of Accelerator Physics and Engineering, edited 19” rack / 100 kW (pulse) a d v a n c e d l a n g u a g e s k i l l s w i l l b e n e fit f r o m physics but classical mechanics. by Chao and Maur y Tig ner. • Synchrotrons, LINACs for scientific, occasional remarks in Chinese, mainly were afraid The physics of synchrotron radiation • CW / Pulse Systems, long pulse experimentation/particle physics philosophical in nature (translated in most to ask” a n d it s d e t a i l e d e ffe c t s o n b e a m d ynam- Lenny Rivkin Paul Scherrer Institute. • Modular Solid State architecture, and Spallation systems

V Plesko, M Rybar and D Scheirich and M Rybar V Plesko, compact modules (<10 kg) • Medical therapy equipment A day with particles A day with particles boast a quirky authen- ticity, and is well placed to connect emo- Courtesy Honeywell Aerospace • Highly Maintainable with Hot Swap • Cyclotrons for radioisotope Screened at GeekFestToronto, and directed by Vojtech Pleskot, t i o n a l l y w it h n o n-p h y s i c i s t s. T h e fi l m i s capability production beautifully paced. Wide-eyed enthusiasm Martin Rybar and Daniel Scheirich • Wall Plug efficiency competitive with • Option to upgrade existing systems for physics cuts to an adorable glimpse Outreach must continue, even in a pan- of Pleskot’s two “cute little particles” tube technology (55% demonstrated) demic: if visitors can’t come to the lab, h a v i n g br e a k f a s t. A r a pi d h o p f r o m D e m- • Highly robust to VSWR mismatch Other Products: we need to find ways to bring the lab to ocritus to Rutherford to the LHC cuts to • High MTBF and Low MTTR • High Power, Very Low Phase Noise them. Few outreach initiatives do this as t r a c k i n g s h o t s o f Pl e s k o t m a k i n g h i s w a y charmingly as A day with particles – a short through the streets of Prague to the uni- • No loss of power from any single TWT Amplifiers i n d e p e n d e nt fi l m b y t h r e e AT L A S phys- versity. The realities of phone confer- element failure • Brazed UHV components icists at Charles University in Prague. jects to win the Canadian award. Even Not pocket-sized ences, failed grid jobs and being late for • High efficiency enhances reliability • Electron Guns Mixing hand-drawn animations, deft within the vibrant but specialist niche A still shot of lab demonstrations are interwoven with s o u n d d e s i g n a n d a br i s k s c r i p t t a r g e t e d of high-energy-physics geekery, com- Daniel Scheirich’s a grad student dancing to discuss her • Frequencies available from • Diffusion Bonding at viewers with no knowledge of phys- petition included The world of thinking, art from A day analysis, conversations on free-diving 2 MHz to 1.3 GHz • Vacuum/Hydrogen Brazing ics, the 30 minute film follows a day in featuring interviews with Ed Witten, with particles. with turtles and the stories of beloved the life of postdoc Vojtech Pleskot. In its and others, and a pro- pr o fe s s or s r e c a l l i n g l i fe i n t h e c o m m u n i s t • MW power capability • Speciality Cleaning latest pitstop in a worldwide tour of indie fessionally produced film dramatising a e r a. L i fe a s a p h y s i c i s t i s g o o d. A n d l i fe a s fi l m fe s t i v a l s, it w o n “BE S T o f F E S T (To p love letter from to his a physicist is really like this, they insist. Geek)” last week at GeekFest Toronto. late wife Arline, who passed away while “I hope that science communicators will For more information on our leading edge “We just want to show that scientists he w a s work i ng on t he M a n h at t a n P ro- share it far and wide,” says Connie Potter are absolutely normal people, and that j e c t. B ut Pl e s k o t, R y b a r a n d S c h e i r i c h w o n (CERN and ATLAS), who commissioned technology email us at [email protected] no one needs to fear them,” says Ple- the judges over with their idiosyncratic t he film for t he 2020 edit ion of ICHEP. skot, who wrote and directed the film distillation of life at the rock-face of dis- A day with particles will next be consid- or visit www.tmd.co.uk alongside producer Martin Rybar and covery. “We want to break stereotypes ered at the World of Film International animator Daniel Scheirich. The three about scientists,” adds Pleskot. Fe s t i v a l i n G l a s g o w i n Ju n e, w h e r e it h a s physicists produced the film with no Not every stereotype is broken, and been selected as a semi-finalist. funding and no prior expertise, beating there is room to quibble about some of the off competition from well funded pro- details, but grassroots projects such as Mark Rayner associate editor.

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Harnessing the CERN model

Experimental physicist Shanghai City Hall Paul Lecoq’s half-century-long career illustrates the power of CERN in fostering international collaboration, writes Craig Edwards.

CERN’s international relationships are central to its work, and a perfect example of nations com- ing together for the purpose of peaceful research, regardless of external politics. Through working in China during the 1980s and the / Russia in the early 1990s, physicist Paul Lecoq’s long career is testament to CERN’s influence and standing. Originally interested in astrophysics, Lecoq completed a PhD in nuclear physics in Montreal Political presence The 1982 dinner where Paul Lecoq (third from right) and Sam Ting in 1972. After finishing his military service, (fifth from right) met with Jiang Zemin (fourth from right), who later went on to become the president during which he taught nuclear physics at the of China. Also pictured are members of the Shanghai Institute of Ceramics (to the left of Ting), and French Navy School, he came across an adver- L3 collaborators Hans Rykaczewski and Michel Lebeau (to the right of Lecoq). tisement for a fellowship position at CERN. It was the start of a 47-year-long journey with This is something i n g, T i n g p oi nt e d h i s fi n g e r i n m y d i r e c t io n a nd the organisation. “I thought, why not?” Lecoq asked if I was free on Saturday. I responded, ‘yes recalls. “CERN was not my initial target, but unique about CERN, sir’. Then he turned to his secretary and said, I thought it would be a very good place to go. ‘book a flight ticket to Shanghai – this guy is Also, I liked skiing and mountains.” where you can meet coming with me!’” Unknown to Lecoq upon his arrival in China, Royal treatment fantastic people Ting had already prepared the possibility to During his third year as a fellow, a staff posi- that can completely develop the technology for the mass produc- The Power of Education tion opened for the upcoming European tion of BGO crystals there, and wanted Lecoq Hybrid Spectrometer (EHS), which would test change your life to oversee this production. BGO was soon rec- Agilent Vacuum and Leak Detection Webinars CERN’s potential for collaboration beyond its ognised as a crystal that could be produced in core member states. “The idea was to make a l a r g e q u a nt it ie s i n a r e l i a bl e a n d c o s t- e ffe c t i v e complex multi-detector system, which would way, and it has since been used in a generation be a multi-institute collaboration, with each also benefit from this successful approach. At of PET scanners. Lecoq was impressed by the Vacuum and precision leak detection are key enabling technologies Powered By institute having the responsibility to build one that time, Sam Ting had been asked to propose authority Ting held in China. “The second day detector,” says Lecoq. One of these institutes was an experiment for LEP by then Director-General we were in China, we, well Ting, had been invited for a very large number of processes and scientific inquiries. based in Japan, allowing the exchange of per- Herwig Schopper, which would become the L3 by the mayor of Shanghai for a dinner to discuss s o n n e l. L e c o q w a s o n e o f t h e fi r s t t o b e n e fit f rom experiment, and with the EHS coming to an end, the opportunity for the experiment.” The mayor Getting them right requires knowledge of the behaviors of gases this agreement and, thanks to CERN’s already says Lecoq, it was natural that the EHS super- was Jiang Zemin, who only a few years later and materials, as well as equipment to create, contain, measure substantial image, he was very well-received. group was transferred to Ting. Through friends became China’s president. “I have been very “At the time, people were travelling much less working in material science, Lecoq caught wind lucky to have several opportunities like this and maintain the pressures you need to succeed. than now, and Japan was more isolated. I was of the new scintillator crystal (BGO) that was in my career. This is something unique about Agilent is pleased to provide both fundamentals and detailed, welcomed by the president of the university and being proposed for L3 – an idea that would see CERN, where you can meet fantastic people that had a very nice reception almost every day.” It him link up with Ting and spend much of the can completely change your life. It was also an accessible information on these technologies and how they are was an early sign of things to come for Lecoq. next few years in China. interesting period when China was slowly open- During the lifetime of the EHS, a “super- BGO crystals had not yet been used in particle ing up to the world – on my first trip everyone applied in specific applications and endeavors. Scan the QR code to go directly group” of CERN staff was formed whose main physics, and had only existed in a few small was in Mao suits, and in the next three to five to the webinars role was to support partners across the world samples, but L3 needed more than 1 m3 of cover- years I could see a tremendous change that was while also building part of the experiment. By a g e. A f t e r s a m pl i n g a n d t e s t i n g t h e fi r s t c r y s t a l so impressive.” the time the Large Electron–Positron Collider samples, Lecoq presented his findings at an L3 Lecoq’s journeyman career did not stop there. Learn more: www.agilent.com/chem/vacuum (LEP) came to fruition it was clear that it would collaboration meeting. “At the end of the meet- With LEP finishing towards the turn of the © Agilent Technologies, Inc. 2020

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PEOPLE CAREERS PEOPLE CAREERS

Appointments and awards millennium and LHC preparations in full swing, there was still very strong intellectual activity, European Commission set up a system, along his expertise was needed for the production of with scientists at an incredible level, and there with Canada, Japan and the US, called the Inter- Smith leads TRIUMF He also represented France at the Trio wins Medal lead tungstate (PWO) crystals for CMS’s elec- was still a lot of production infrastructure for national Science and Technology Center (ISTC), Nigel Smith has been European Committee for Future K Foto The 2021 Galileo Galilei Medal has tromagnetic calorimeter. This time, however, military interest.” whose role was to transfer the Soviet Union’s announced as the next director Accelerators from 2013 to 2019 been awarded to theorists (below, Russia was the base of operations, and the 1.2 m3 At the time, lithium niobate, a crystal very sim- military industry into civil application. Lecoq of TRIUMF, Canada’s leading and has been involved in the LHCb from top to bottom) Alessandra of BGO crystal for L3 became more than 10 m3 of ilar to PWO, was being exploited for radar com- was able to meet with ISTC and gain €7 million particle accelerator centre. experiment since 2013. Wormser’s Buonanno ( Institute), PWO for CMS. As with his spell in China, Lecoq munication and missile guidance, says Lecoq, in funding to support PWO crystal production SNOLAB term will encompass the 150th Thibault Damour (Institut des was in Russia during a politically uncertain time, and the country had a valuable (but unknown to for CMS. Again, he stresses, this only happened anniversary of the SFP in 2023. Hautes Études Scientifiques) with his arrival shortly following the fall of the the public) production-infrastructure in place. due to the stature of CERN. “I could not have and Frans Pretorius (Princeton Berlin Wall. “There was no system anymore. But With the disarray at the end of the Cold War, the done that if I had been working only as a French New ATLAS management University) “for the fundamental scientist. CERN has the diplomatic contact with The ATLAS collaboration the European Commission and different gov- announced its new management ernments, and that made it a lot easier.” Lecoq team on 1 March. Former deputy T Rinaldo was responsible for choosing where the crystal spokesperson Andreas Hoecker production would take place. “These top-level (pictured), who has been part A two-month residency at scientists working in the military areas felt iso- of the collaboration since 2005, CERN this year, followed by one lated, especially in a country that was in a period replaces Karl Jakobs to become the month at the Hangar Visual Arts of collapse, so they were more than happy not fifth ATLAS spokesperson since Research and Production Centre only to have an opportunity to do their job under The appointment follows the the collaboration’s establishment in Barcelona, will see Ayewa and better conditions, but also to have the contacts. departure of Jonathan Bagger, in 1992. Marumi Kado Phillips produce a new artwork It was interesting not only at the scientific level, who became CEO of the American (University of Rome I and INFN based on their proposal “CPT but on a human level too.” Physical Society in January. Rome) joins Manuella Vincter Symmetry and Violations”. Smith, who has served as (Carleton University) as deputy Collide is an annual competition Crystal clear SNOLAB director since 2009, has spokesperson, while technical that invites artists from across C Nellist

Back at CERN, Lecoq realised that introduc- previously worked as a research the world to submit proposals for F PLAS/CNRS ing a new scintillating crystal, optimising its associate at Imperial College a research-led residency based performance to the harsh operating conditions London and as group leader in on interactions with CERN’s of the LHC, and developing mass-production dark-matter research at the STFC scientific community. This year a technologies to produce large amounts of crys- Rutherford Appleton Laboratory. total of 564 project proposals were tal in a reliable and cost-effective way, was a His five-year term as TRIUMF received from 79 countries. formidable challenge that could not be dealt director begins on 17 May and with only by particle physicists. Therefore, in spans an important time as the 2020 Wu-Ki Tung Award 1991, he decided to establish the Crystal Clear laboratory aims to complete two Theorist Bernhard Mistlberger multidisciplinary collaboration, gathering major projects: the Advanced Rare (SLAC) has been granted the experts in material science, crystal-growth, Isotope Laboratory (ARIEL) and 2020 Wu-Ki Tung Award for luminescence, solid-state physics and beyond. the Institute for Advanced Medical Early-Career Research on QCD, Here again, he says, the attractiveness of CERN Isotopes (IAMI). “for pioneering theoretical as an internationally recognised research cen- coordinator Ludovico Pontecorvo computations of multi-loop tre was a great help to convince institutes all French Physical Society (CERN), resource coordinator radiative contributions for Princeton University over the world, some not connected to particle appoints Wormser David Francis (CERN) and precision Higgs and electroweak physics at all, to join the collaboration. Crystal The French Physical Society (SFP) upgrade coordinator Francesco physics at hadron colliders”. The Clear is still running today, and celebrating its has appointed particle physicist Lanni (Brookhaven National $5000 award, given annually to 30th anniversary. Guy Wormser as its new president Laboratory) also continue in their a young physicist performing Through developing international connec- for the period 2021–2023. roles. The new management team either experimental or theoretical tions in unexpected places, Lecoq’s career has Wormser has spent his career at will guide the collaboration for research on QCD, was established helped build sustained connections for CERN the Linear Accelerator Laboratory the next two years, overseeing by the CTEQ (Collaborative in some of the world’s largest and fruitfully (LAL) at Orsay, which recently the final push before LHC Run 3 Theoretical and Experimental understanding of sources of scientific places. Now retired, he is a distin- merged with neighbouring in 2022 and preparing for future studies of QCD) collaboration gravitational radiation by

guished professor at the Polytechnic University laboratories to become the high-luminosity LHC operations. B Mistlberger complementary analytic and in Valencia, where he has set up a public–private Irène-Joliot Curie Physics of Two numerical techniques, enabling partnership laboratory for metamaterial-based Infinities Lab (IJCLab), and was Collide Residency Award predictions that have been scintillators and photodetectors, to aid a new director of LAL from 2005–2011. Arts at CERN announced in confirmed by gravitational-wave

generation of ionisation radiation detectors Wormser G February that Black Quantum observations and are now key for medical imaging and other applications. Futurism, a multidisciplinary tools in this new branch of Even now, he is able to flex the muscles of the collaboration between Camae astronomy”. The award was CERN model by keeping in close contact with Ayewa (above left) and Rasheedah established in 2018 by the the organisation. Phillips (above right), has been National Institute for Nuclear “My career at CERN has been extremely rich. awarded the Collide Residency Physics (INFN) and the Galileo I have changed so much in the countries I’ve Award. The duo explores the Galilei Institute, and is given to worked with and the scientific aspect, too. It intersections of futurism, scientists who, in the 25 years could only have been possible at CERN.” creative media, DIY-aesthetics in 2014 to honour the legacy of before the date of the award, have and activism in marginalised Wu-Ki Tung, one of the leading achieved outstanding results in Craig Edwards (based on an interview communities “through an researchers on QCD, and the the areas of theoretical physics of between Paul Lecoq and the Office for alternative temporal lens”. founder of CTEQ. interest to the INFN. CERN Alumni Relations).

60 CERN COURIER MAY/JUNE 2021 CERN COURIER MAY/JUNE 2021 61

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administration. A degree in political science, business admi- nistration or similar may also be suitable. The European Physical Society (EPS) is a non-profit associa- The Secretary General shall be responsible for all administra- tion that advocates and promotes physics research and its tive and financial of the EPS. The person supports the contributions to the economic, technological, social and cultu- activities of the President, the Vice President, the Executive ral advancement in Europe. Federating 42 national Member Committee, and all other bodies of the Society. Societies, institutional and corporate Members from academia The EPS is looking for a dynamic personality with leadership and industry, and more than 3’500 Individual Members, the experience, excellent social and communication skills, and a EPS represents a community of more than 130’000 scientists. strong interest in science policy and science advocacy, in par- The scientific activities of the EPS are organised through ticular at the European level. An enthusiastic commitment to 18 Divisions and Groups covering all branches of physics. the mission of the Society is expected. The position requires The seat of the Society is in Mulhouse (France). Detailed infor- fluency in English, a working knowledge of French, flexible mation about the EPS can be found on www.eps.org. working hours, and availability to travel. A complete job description is available at https://www.eps.org/recruitment. THE EPS IS SEEKING A NEW SECRETARY GENERAL The EPS offers competitive employment conditions com- to succeed the present Secretary General who plans to retire mensurate with age and experience, in an attractive environ- in spring 2023. Employment is expected to begin in autumn ment close to the French-German-Swiss border triangle. The 2022 to allow for a thorough on-the-job training. financial conditions will be based on the salary grid of public The Secretary General heads the EPS Secretariat which research institutions in France. supports the activities of the President, the Vice President, Applications with a detailed letter of motivation and a Curricu- JOIN ELI the Executive Committee, and all other bodies of the Society. lum Vitae should be addressed not later than 30 June, 2021 to The future is in laser technologies The person to be recruited should have a university degree, the EPS President, Dr. Luc Bergé ([email protected]). preferably in physics or another field in natural sciences, Further information may also be obtained from the present with several years of experience in science management and Secretary-General ([email protected]).

The ELI (Extreme Light Infrastructure) Project is an integral part of the European plan to build Untitled-1 1 01/04/2021 13:32 the next generation of large research facilities. ELI-Beamlines as a cutting edge laser facility is currently being constructed near Prague, . ELI delivers 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 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 of e- and p+ and high-energy photons. Our research groups are expanding and recruiting physicists and engineers.

In our team we therefore have the following positions available:

• Junior Scientist • Senior Engineer • Safety Engineer • Senior Scientist • Vacuum Technician • Optical Engineer • Laser Physicist • Mechanical Designer • X-ray Scientist • Junior Engineer • Control System Specialist • Opto-mechanics

For more information see our website www.eli-beams.eu and send your application, please.

ELI_PWAprCl_26x4.indd 1 15/03/2021 16:37 CERNCOURIER www. V o l u m e 6 1 N u m b e r 3 M a y /J u n e 2 0 2 1 ASSOCIATE DIRECTOR FOR EXPERIMENTAL NUCLEAR PHYSICS

Outstanding opportunity to lead the experimental nuclear physics program Discover what’s out there at a prestigious, world-leading nuclear physics research facility located in The Department of Physics and Astronomy at Heidelberg University invites coastal Virginia. Take the next step in your career applications for a For our location in Zeuthen we are seeking: About the job: Jefferson Lab’s Associate Director (AD) for Experimental Nuclear Physics executes the experimental nuclear physics program of with Physics World Jobs. FULL PROFESSORSHIP (W3) IN the laboratory and manages the division’s ~ 140 staff. The primary nuclear PhD student for dosimetry and beam physics research facility is the Continuous Electron Beam Accelerator Facility (F/M/D) diagnostics at PITZ operating at 12 GeV with four experimental halls. physicsworld.com/jobs Candidates (f/m/d) are expected to develop a strong research program in • Lead and manage the Physics Division, which has primary responsibility experimental particle physics by searching for physics beyond the Standard for the design, construction, commissioning, and operation of the CEBAF Model through precision measurements. Possible subject areas could be dark DESY experimental facilities installed in Halls A, B, C and D; manage the matter and axion searches, collider or non-collider based neutrino physics, ∙ or research at high-intensity low-energy beams. The position is located at DESY, with its 2700 employees at its two locations in Hamburg and Zeuthen, financial, human, and material resources of the Division. the Kirchhoff-Institut für Physik (KIP) and aims to complement our efforts is one of the world‘s leading research centres. Its research focuses on • Partner with leadership team to support the lab’s broad scientific mission, in high-energy particle physics at the LHC. It will be embedded in an active decoding the structure and function of matter, from the smallest particles including the Electron-Ion Collider and development of a computational of the universe to the building blocks of life. In this way, DESY contributes to sciences program. research environment on experimental and theoretical particle physics both at solving the major questions and urgent challenges facing science, society • Assure close collaboration with the international user community Heidelberg University and the Max-Planck-Institut für Kernphysik (MPIK). and industry. With its ultramodern research infrastructure, its interdisciplinary numbering approximately 1600 physicists during the equipment design The professorship is based within the Department for Physics and Astronomy research platforms and its international networks, DESY offers a highly & construction phases. Provide support to scientific users to optimize the and duties include teaching of experimental physics in its full breadth at the attractive working environment in the fields of science, technology and overall scientific productivity of the CEBAF program. undergraduate and graduate levels. The group will participate in the graduate administration as well as for the education of highly qualified young • Contribute to strategic planning, policy formation, budgeting, and science education program within the Heidelberg Graduate School for Physics scientists. initiatives. (HGSFP). The Photo lnjector Test Facility PITZ in Zeuthen (near Berlin) is one of the • Represent the laboratory with government agencies, the international Prerequisites for application are a university degree, a doctoral degree and (in leading international groups in developments on modern photo injectors physics community, other laboratories, universities and other stakeholders. and their applications. Current R&D goals of PITZ include improving accordance with Article 47, Paragraph 2 of the Higher Education Law of the electron source brightness beyond state of the art for X-ray Free Electron About you: Bring a vision for the future evolution of the different Federal State of Baden-Württemberg) a habilitation, a successfully evaluated Lasers as weil as applications of high brightness beams e.g. for FLASH components of the nuclear physics program and the ability to nurture the junior professorship, or equivalent qualifications. radiation therapy R&D. FLASH radiation therapy (FLASH RT) involves efforts of a major part of the laboratory. Set a tone and direction which Applications should include a CV, a statement of research interests, a brief treatments delivered by ultra-short bunches, and is a new and exciting will ensure excellence on the world scale. Important attributes include description of future research plans, a list of publications and a summary of possibility for cancer treatment. The PITZ accelerator is the perfect test leadership and communication skills, ability to manage resources & people, teaching experience. They should be sent electronically (PDF) only. All materials facility for this new technique as it can deliver full treatment doses within and relevant technical expertise. must be received no later than 16.05.2021 at Ruprecht-Karls-Universität a 1 ms bunch train. The detectors and methods established for dosimetry Heidelberg, Dekan der Fakultät für Physik und Astronomie, Prof. Dr. Tilman of conventional radiotherapy are not suitable for FLASH RT. The student Please see the complete posting at https://www.jlab.org/job-openings. Plehn, Im Neuenheimer Feld 226, D-69120 Heidelberg, e-mail: dekanat@ will develop suitable detection and dosimetry methods, making use of the detector expertise developed for particle, astroparticle and accelerator Thomas Jefferson National Accelerator Facility (Jefferson Lab) is a U.S. Department of physik.uni-heidelberg.de. physics applications at DESY Zeuthen in cooperation with national and Energy national laboratory managed and operated by Jefferson Science We ask for your understanding that application documents received will not be international partners. Associates, LLC, an EOE. returned. Heidelberg University stands for equal opportunities and diversity. Qualified The position female candidates are especially invited to apply. Disabled persons will be • Simulate beam interactions using software packages such as GEANT given preference if they are equally qualified. Information on the application • Prototype and test several sensors for dosimetry, including CMOS process and the collection of personal data is available at www.uni-heidelberg. imaging sensors (CIS) de/stellenmarkt. • Implement the sensors and readout in PITZ and test them with the unique beam properties available • Optimise beam dynamics and test with phantoms to optimise the delivered dose • Analyze experimental data and compare with simulation results • Participate in shift operation for accelerator R&D at PITZ

Requirements The Department of Physics and Astronomy at Heidelberg University invites • Excellent university degree in experimental physics, with very good applications for a knowledge in detector physics and corresponding simulations or equivalent qualification • Strong background in numerical and statistical methods FULL PROFESSORSHIP (W3) IN • Good knowledge in experimental characterization of particle beams; good programming skills THEORETICAL PHYSICS (F/M/D) • Knowledge in beam dynamics simulations/radiation physics/dosimetry is Candidates (f/m/d) should have a leading international research profile in of advantage the broader area of quantum field theory/cosmology (succession Christof • Very good command of English is required and knowledge of German is Wetterich). They should contribute to our understanding of fundamental of advantage physical law by applying and developing modern theoretical methods. The • Excellent teamwork abilities in an international environment candidates‘ research should have connections to and complement the work of For further information please contact Dr. Steven Worm at +49 33762 established groups at our Theory Institute and Physics Department. Teaching 7-7208 (steven.worm@.de). Theoretical Physics at all levels is a central part of this position. The position is limited to 3 years. Prerequisites for application are a university degree, a doctoral degree and (in Salary and benefits are commensurate with those of public service accordance with Article 47, Paragraph 2 of the Higher Education Law of the organisations in Germany. Classification is based upon qualifications and assigned duties. Persons with disabilities will be given preference to Federal State of Baden-Württemberg) a habilitation, a successfully evaluated other equally qualified applicants. DESY operates flexible work schemes. junior professorship, or equivalent qualifications. DESY is an equal opportunity, affirmative action employer and encourages Applications should include a CV, a statement of research interests, a brief applications from women. description of future research plans, a list of publications and a summary of We are looking forward to your application via our application system: teaching experience. They should be sent electronically (single PDF) only. www.desy.de/onlineapplication All materials must be received no later than May 16, 2021 at Ruprecht- Deutsches Elektronen-Synchrotron DESY Karls-Universität Heidelberg, Dekan der Fakultät für Physik und Astronomie, Human Resources Department | Code: APDO002/2021 Prof. Dr. Tilman Plehn, Im Neuenheimer Feld 226, D-69120 Heidelberg, Notkestraße 85 | 22607 Hamburg Germany | Phone: +49 40 8998-3392 e-mail: [email protected]. www.desy.de/career We ask for your understanding that application documents received will not be Deadline for applications: Until the position is filled. returned. Heidelberg University stands for equal opportunities and diversity. Qualified female candidates are especially invited to apply. Disabled persons will be given preference if they are equally qualified. Information on the application process and the collection of personal data is available at www.uni-heidelberg. de/stellenmarkt.

CERNCOURIER www. V o l u m e 6 1 N u m b e r 3 M a y /J u n e 2 0 2 1 CERNCOURIER.COM PEOPLE CERNCOURIER OBITUARIES REPORTING ON INTERNATIONAL HIGH-ENERGY PHYSICS Sa moil mihelevich Bilenky 1928–2020 A pioneer of neutrino physics JINR Eminent Russian theorist Samoil Mihelevich proposed once, jokingly, that Bilenky should be Bilenky, one of the founders of modern neutrino called “Mister Neutrino”. physics, passed away on 5 November 2020. A Bilenky was an excellent teacher, mentor and teacher of a generation of particle physicists, not inspiration for many young researchers in the only in Russia but also in many Eastern European field of and neutrino physics. countries and later in Western Europe, Samoil His lectures on different topics in theoretical Bilenky played a leading role in the evolution of particle physics at Moscow University, where neutrino physics to the present day. he taught for 30 years, and on neutrino physics Bilenky was born in Zmerinka, Ukraine, to an at various international schools, were charac- engineering family. He graduated in 1952 cum terised by remarkable clarity. This made him a laude from the renowned Moscow Engineering sought-after speaker and he was invited and gave Physics Institute. His thesis adviser was Isaak lectures at universities across Europe. Bilenky Pomeranchuk. The same year, Bilenky got a initiated and was a tireless organiser of the well- permanent position at the Institute for Nuclear known Pontecorvo Neutrino Physics School. Problems in Dubna, near Moscow, which in 1956 For his research and teaching activities became the Joint Institute for Nuclear Research Bilenky received many recognitions: the Rus- (JINR), and ever since was a staff member at sian state medal “For distinguished service to JINR. He obtained his PhD in 1957 for appli- the State”, the International Bruno Pontecorvo cations of the dispersion-relation theory to Bilenky helped lay the foundations of the Prize, the Humboldt Prize, and the Medal of First weak-interaction processes. In a subsequent phenomenological theory of neutrino mixing. Degree of the Faculty of Physics and Mathemat- series of articles, Bilenky discovered a gen- ics of Charles University in Prague, among oth- eral connection between polarisation effects of the phenomenological theory of neutrino mix- e r s. He a l s o w r o t e fi v e b o o k s o n p a r t i c l e-p h y s i cs and internal parities of particles in scattering ing, on which every theoretical model of neu- theory, which have helped and continue to help processes and proposed a method for determin- trino mass generation (including grand unified many young scientists enter into the fascinating ing the parities of strange particles, later used theories) is based. After Pontecorvo’s passing in fie l d s o f m o d e r n p a r t i c l e a n d n e ut r i n o p h ysics. in experiments at Berkeley and CERN. These 1993, Bilenky continued to make original and Bilenky attracted people with his kind and articles also initiated the development of the insightful contributions to the development of obliging character, and had collaborators and polarised proton–target technique. neutrino physics. For his devotion to the studies friends in many countries. His warmth and Bilenky’s most prominent contributions are in of neutrinos, which he called “the most interest- benevolent personality embodied the best the field of neutrino physics. In a fruitful collab- ing among the elementary particles”, and – in humanistic and cultural traditions of the Rus- oration and co-authorship with the Italian/Soviet view of the fact that neutrino properties suggest sian intelligentsia to which Samoil Mihelevich physicist Bruno Pontecorvo, which started in the the existence of physics beyond the Standard Bilenky belonged. We shall miss him. early 1970s, he developed the theory of neutrino Model – “a gift of nature”, his long-term friend oscillations in vacuum and laid the foundations and renowned particle physicist Jose Bernabeu His colleagues and friends.

a rnulfo Zepeda domíngueZ 1943-2020 Promoting Mexican particle physics

Born in 1943 in San Luis de Potosí, Mexico, at Cinvestav and became one of the leading gamma-ray observatory and participation in Gain unique insights on the latest research Arnulfo Zepeda graduated in nuclear engineer- figures in theoretical physics in Mexico and its collaboration board. ing at the University of Prague in 1967. He then Latin America. At the beginning of the new millennium, breakthroughs and project developments in joined Cinvestav (Centro de Investigación y de In the late 1990s Arnulfo’s attention turned Arnulfo was among the initiators of the par- Estudios Avanzados of Instituto Politécnico to ultra-high-energy cosmic rays. Leading ticipation of Mexican scientists in CERN’s particle physics and related fields Nacional), where he obtained a PhD in phys- Mexico’s participation in the construction and experimental programmes, in particular the ics in 1970, and then Rockefeller University exploitation of the Auger Observatory in Argen- ALICE experiment. In 2002 he formally joined where he obtained a PhD in elementary particle tina, he contributed significantly to important ALICE, where he was involved in the installa- physics in 1972. discoveries such as establishing the GZK ultra- tion of the ACORDE detector that has acted as a cerncourier.com Arnulfo’s initial interest was in theoretical high-energy cutoff, the nuclear composition cosmic-ray trigger. ACORDE not only provided particle physics and he became known for his of ultra-high-energy cosmic rays and the precious calibration data but also, together with studies in chiral symmetry breaking, nucleon observation of possible point-like cosmic-ray other ALICE sub-detectors, precise information form factors and the up-quark mass. He created sources. His activities in this field continued on cosmic rays with primary energies in the s a young and very active particle-physics group in Mexico with the promotion of the HAWC range 1015–10 17 eV.

CERN COURIER MAY/JUNE 2021 69

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PEOPLE OBITUARIES PEOPLE OBITUARIES MAIS Arnulfo was an associate (1982–1988) and lised exchanges for more than 3000 person- Pierluigi riboni 1935–2020 photograph Family Foundation, which collaborates with CERN in the senior associate (1998–2003) to ICTP, Trieste, months, making it possible for physicists from development of the techniques for hadron ther- and was elected fellow of the American Phys- Latin America to participate significantly in the apy, and contributed to the mechanical design ical Society in 1993 for his original research in discoveries made at the LHC. In his later years, A great CERN of both high-frequency proton accelerators and high-energy physics and phenomenology, his Arnulfo was the founding director of MAIS (Meso gantries that support magnetic beam lines and leadership in high-energy physics in México, American Institute for Science) at the Universi- engineer rotate around the patient bed. In particular, he and for initiatives in promoting closer com- dad Autónoma de Chiapas – an initiative started designed a gantry that weighed 25 tonnes, which munication among physicists in North Amer- by ICTP to establish a network of partner UNE- was 10 times less than the existing ones. The ica. Contributing greatly to the advancement SCO institutes around the globe. Arnulfo took Pierluigi Riboni passed away in Geneva on report on SIGRUM – the Superconducting Ion of physics in Mexico and Latin America, he this task with great enthusiasm, moving there 9 November, aged 85, as a consequence of COVID- Gantry with Riboni’s Unconventional Mechanics founded the Escuela Mexicana de Partículas from 2011 to 2018, and MAIS was established as a 19. Born in Pavia, Italy, he graduated from Milan – was presented a few days after he left us to y Campos, chaired the División de Partículas category-two UNESCO institute in 2020. Polytechnic in 1961 as a mechanical engineer. the international advisory committee set-up by y Campos of the Sociedad Mexicana de Física Arnulfo’s broad and deep scientific interests After working a few years for Montecatini in Por- CERN, CNAO, INFN and MedAustron. (SMF) in 1991–1992, and was president of SMF and his human qualities have been instrumental tomarghera near Venice, he joined CERN as the Pierluigi’s cultural background covered phi- between 1992 and 1994. He also directed more in the growth of high-energy and astroparticle head of the mechanics group in the engineering losophy, politics, economics and architecture. than 30 theses and was considered an enthu- physics in Mexico in recent decades, and raised division. Initially his work focused on supporting His vast knowledge originated from both an siastic and outstanding professor, devoted to t h e pr o fi l e o f t h e M e x ic a n s c ie nt i fic c o m mu nity the PS groups and, in particular, concerning the unbound curiosity and a great interest in learn- his students. at the international level, both at CERN and in vacuum systems. In the 1970s he also contributed Pierluigi helped design gantries for hadron therapy ing. He also had a passion for athletics, tennis In the years 2005 to 2016 Arnulfo promoted international cosmic-ray experiments. He was to the design of ESO’s 3.6 m telescope. in his later years. and skiing, balancing his intellectual interests Europe–Latin America scientific exchanges as an excellent scientist and a precious friend for During the early 1990s Riboni became the with his physical wellbeing. His life choices were a member of the executive board of two Euro- many of us at CERN. head of CERN’s central machines shop, which held in Como, Italy. The conference became an characterised by an unbeatable optimism, which pean Commission projects: HELEN (High Energy is responsible for supporting the accelerators and important venue for knowledge exchange for allowed him to maintain a positive attitude Physics Latin-American European Network) Paolo Giubellino GSI-FAIR, detectors by supplying machines and material several hundred scientists, engineers, managers towards all professional and personal chal- and EPLANET (European Particle Physics Latin Arnulfo was instrumental in the growth of Università di Roma, Luciano Musa CERN and from conceptual design to quality-controlled and administrators of research institutions. lenges. He had a gentleman’s attitude in his American Network). These projects have mobi- high-energy and astroparticle physics in Mexico. Veronica Riquer Università di Roma. end products. Personnel shortages during Pierluigi remained active long into his retire- relations with people, and he always encouraged these times meant that he often had to face the ment, in particular contributing to CERN’s activ- and supported younger collaborators. RogeR J N PhilliPs 1931–2020 “making or buying” dilemma, leading Riboni it ie s. He w a s o n e o f t h e fi r s t e n g i n e e r s i n v ol v ed Pierluigi is among the best Italian engineers to become increasingly involved with technol- in the CMS detector, and continued to contribute who contributed to the successes of CERN. He ogy-transfer to industry. For nearly 20 years through an association with ETH-Zurich, focus- will be missed by his family, friends and his col- An eminent phenomenologist he co-organised the industry sessions of the ing on the production of the superconducting laborators but will always live in our memories. biannual Conference on Astroparticle, Particle cable of the solenoid and on the manufacturing Family photograph Family The eminent theoretical physicist Roger Julian neutrino masses and mixing. From 1983 Physics, Detectors and Medical Applications, of four grease pads. In 2002 he joined the TERA His friends and colleagues. Noel Phillips died peacefully on 4 September Phillips and his collaborators developed C Pansing 2020, aged 89, at his home in Abingdon, UK. pioneering strategies in collider physics for Harold Klein TicHo 1921–2020 Luis Alvarez. He continued to leave his mark in Roger was educated at Trinity College, Cam- finding the W boson, the , the science education well into his 80s with the UC bridge, where he received his PhD in 1955. His Higgs boson and searches for physics beyond A remarkable San Diego public television science programme thesis advisor was . Roger transferred t h e St a n d a r d M o d e l. I n a n i n flu e nt i a l 1990 p ub - he developed for budding young scientists. from the Harwell theory group to the Ruther- lication, Phillips, Hewett and Barger showed Harold was not only resilient and remarkably ford Appleton Laboratory in 1962, where he led that the decay of a b-quark to an s-quark and life well-lived accomplished, he also had matchless integrity, the theoretical high-energy physics group to a photon is a highly sensitive probe of a rationality, objectivity, generosity and strong international prominence. He also held visit- charged Higgs boson through its one-loop Harold Klein Ticho, who was born in Brno, moral character. Unusually he excelled not only ing appointments at CERN, Berkeley, Madison virtual contribution. Czechoslovakia in 1921, passed away peacefully in physics, but also in the more pragmatic and and Riverside. After retiring in 1997, Roger maintained an on 3 November 2020 in La Jolla, California, sur- political field of university administration. He Roger was a giant in particle-physics phe- active interest in particle physics. He strug- rounded by his loving family. He was a little more tempered all with a gentle and often mischievous nomenology and his book Collider Physics gled with Parkinson’s disease in recent years than a month under 99 years of a well-lived life. sense of humour, and a great love of his family, (Addison-Wesley, 1987), co-authored with but continued to live with determination, wit Harold was the eldest son of well-to-do classical music, opera and theatre. His method- his longstanding collaborator Vernon Barger, and cheer. He joked that his Parkinson’s tremor parents. From the age of 12 he experienced many ical nature was contrasted with his spontaneous remains a classic. In 1990 Roger was awarded the made his mouse and keyboard run wild: “I know m o m e nt o u s c h a n g e s t h a t t e s t i fie d t o h i s f a m i l y’s wit, and other surprising traits like putting his Medal and Prize of the UK’s that an infinite number of random monkeys can resilience during a time of great personal and fo o t t o t h e flo or w h e n d r i v i n g i n h i s A l f a R omeo, . To experimenters, he was Roger Phillips was renowned for his deep eventually write Shakespeare, but I can’t wait global upheaval. His younger brother Leo passed and his almost reckless and frenzied cooking, one of the rocks upon whom the UK high-energy understanding of particle-physics models. that long!” One of his very last whispers to his away in 1933 from a childhood illness. Shortly Harold Ticho was part of the team working on p a n c l a n g i n g a n d t o m a t o -s a u c e fl i n g i n g w h e n physics community was built. To theorists, he son David was: “There are symmetries in math- after the Anschluss in 1938 when living near the Berkeley’s Bevatron. he made his signature dish of veal parmigiana. was renowned for his deep understanding of ematics which are like aspects of dreaming.” Austrian border, Harold’s mother sent him to a In his 90s, he became a San Diego Padres fan particle-physics models. There are symmetries He did great things with his brain when he was Swiss boarding school to get him safely out of the tenure with the UC system that would continue and lectured on the application of physics to A career-long collaboration across the Atlan- in mathematics alive that will continue, as he donated his to the country. By the time they were reunited in the US through becoming dean of the physics depart- baseball. He also used some inexpensive binder tic with Barger ensued from their sharing an Parkinson’s UK Brain Bank. in 1940, Harold was enrolled at the University of ment, professor and later vice chancellor at UC clips and post-it notes placed on the pendulum o ffic e a t C E R N i n 1967. T h e i r i n it i a l fo c u s wasthe which are like aspects Roger was highly respected for his intellec- Chicago. He became a US citizen in 1944. San Diego. In between, he held multiple Gug- of his early 19th-century Morbier grandfather Regge-pole model to describe high-energy scat- tual brilliance, physics leadership and immense Harold obtained his bachelor’s degree in phys- genheim fellowships, a visiting professorship clock to synchronise it with atomic time. tering of hadrons. Subsequently they inferred of dreaming integrity, but also for his modesty and generosity ics in 1942, his master’s in 1944 and his PhD in at Stanford and a sabbatical position at CERN. Harold was a gem of a man. In keeping with the momentum distribution of the light quarks in going out of his way to help others. He was 1949. Over the years he had the opportunity to As a researcher, educator and university Harold’s wishes, his family asks that anyone and gluons from deep-inelastic scattering data a delight to work with and an inspiration to all work with the greatest minds in his field such administrator, Harold’s contributions were who wants to honour his memory make a con- and made studies to identify the charm-quark neutrinos propagate long distances through who knew him. He is missed by his many friends as at institutes including Fermi- extraordinary. His research in experimental tribution to the Global Union of Scientists for signal in a Fermilab neutrino experiment. matter. This work is the basis of the ongoing around the world. lab, Berkeley and CERN. Aged 27, he became a particle physics paved the way to the Peace and The Humane Society. In 1980 Phillips and collaborators discovered Fermilab long-baseline neutrino programme lecturer and later professor at the University of of the nucleon, his contributions being essential the resonance in neutrino oscillations when that will make precision determinations of Vernon Barger University of Wisconsin-Madison. California at , the beginning of his to the work of the -winning team of Cynthia Pansing West Stockbridge, MA.

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PEOPLE OBITUARIES

PhiliP K aRl Willia ms 1939–2021 Open access for CERN researchers An exemplary research director Thanks to a transformative agreement between CERN and 50+ journals including: P Williams Theorist Philip Karl Williams passed away in deserved recognition of his many contributions, IOP Publishing, you can: the Washington, DC area on 19 January. Born in 2003 PK was elected as a fellow of the American in Tulsa, Oklahoma, he completed a bachelor’s Physical Society. Publish open access in more than 50 IOP Publishing journals degree at Rice University in 1961, a PhD in physics At the DOE, he served as mentor to newer • at Indiana University in 1965, and a research programme managers, clarifying how the at no cost to you associateship at the from programme was envisioned and the considera- 1965 to 1967. Following his postdoctoral training, tions for funding. He cared deeply about the uni- • Increase your paper’s visibility and impact* he moved to Florida State University where he versity researchers funded via the programme Comply with any open access mandate and policy, even when was promoted to associate professor with tenure and was always ready to discuss their needs for • in 1973. While at Florida, PK, as he was known carrying out their research. publishing in non-SCOAP3 journals to friends and colleagues, was best known for However, for many of us, PK will be long his theoretical formulations of pion physics in remembered and respected for his faithful • Be covered whether your affiliation is primary or secondary ππ scattering with absorption, that came to be stewardship of the DOE university research Include articles from CERN experimental collaborations known as the Williams model. programme in high-energy physics, and for • In 1979 PK chose to enter government service his yearly site visits throughout the commu- such as ATLAS, CMS, LHCb and ALICE with the Department of Energ y (DOE) office of nity to keep abreast of activities and to meet high-energy physics, located near Washington, young postdocs and students. Through good DC, where he soon became the director of an times and bad, he was always helpful and sup- approximately $100 million university research portive. We fondly remember his visit to CERN Find out more at http://bit.ly/CERNIOP programme – a position that he held until his where he met many US physicists and encour- retirement in late 2008. In addition to this Williams was respected for his faithful stewardship aged them to work hard and not get discouraged key managerial role, PK also made significant of the DOE university research programme. by being in big collaborations. We will miss contributions to other agency activities, which him greatly. included serving as executive secretary of the erties of matter, executive secretary of the US/ high-energy physics advisory panel (HEPAP), Japan committee on high-energy physics, and Vasken and Sharon Hagopian Florida State executive secretary of the US/Russia joint co- chair of the scientific assessment group for University, Randy Ruchti Notre Dame University ordinating committee on fundamental prop- experiments in non-accelerator physics. In well- and Kathleen Turner US DOE.

Roland WindmoldeRs 1940–2020 CERN continued to work on muon physics within the New Muon Collaboration, the Spin Muon Col- laboration and then COMPASS, which is still A great running. He continued to work with COMPASS until his retirement in 2018, and kept in contact with the collaboration thereafter. collaborator Roland was a true scientist and a great col- laborator: his contribution to deep-inelastic Roland Windmolders died suddenly on physics experiments cannot be overstated. 27 November 2020 in Prévessin, France. Of His profound understanding of all details of Belgian nationality, Roland completed his uni- deep inelastic scattering experiments and data versity education at the University of Louvain, analysis consistently allowed him to find new first in civil engineering and then in mathe- solutions to physics problems. Calm, friendly and matics and physics. Aged 27 he defended his shy, Roland attracted discussions and debates PhD in particle physics at Louvain with the at all moments, coffee breaks in particular. He highest distinction. At the end of the 1960s, never applied for or agreed to take on any high- Roland spent a year at Berkeley, after which he level positions; his leading role in physics was, became an assistant in the faculty of science in spite of that, never questioned. His style was at the University of Mons, where he assumed to work quietly in the background without fuss. several teaching responsibilities. From 1971 to Roland Windmolders was a true Roland was a thorough gentleman who got 1976 his work was connected with the Mirabelle “enlightenment” man. things done. He was always willing to help and bubble chamber and studies of –proton and to advise others, and his help was often sought. antiproton–proton interactions, working with laboration of more than 100 physicists – which He was a true “enlightenment” man: cultivated physics communities across the world. was considered large in the 1980s – formed to and sophisticated in the arts, literature and his- SCAN ME TO FIND OUT MORE In 1975 Roland married Magdeleine. For about study the nucleon and nuclei parton structure. tory, which he systematically explored during 10 years they lived in Belgium and then moved Roland brought with him wide experience and his many travels. In particular, he had an inti- to Prévessin, to be closer to CERN, as Roland knowledge of high-energy interactions, acquired mate knowledge of CERN’s surrounding region, became more and more involved in CERN’s from bubble-chamber experiments. He once said which he was always willing to share with his * H Piwowar, J Priem, L V arivière, J P Alperin, L Matthias, B Norlander, A Farley, J West, S Haustein (2018) The state of OA: a large-scale analysis of the prevalence and impact of Open Access articles. experiments, while still affiliated to the Uni- with great satisfaction: “In this subject, you can colleagues to help them appreciate the beauties PeerJ 6:e4375 https://doi.org/10.7717/peerj.4375 versity of Mons. He joined the European Muon precisely calculate everything.” The EMC made of the region. He will be dearly missed. Collaboration (EMC), eventually becoming its several fundamental discoveries, such as the longest-serving member. The EMC was a col- “E MC e ffe c t” a n d t h e pr o t o n s pi n p u z z l e. R oland His colleagues and friends.

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Notes and observations from the high-energy physics community Wu honoured by US postal service Chien-Shiung Wu adorns a new commemorative US Postal Service stamp, becoming t he first Chinese A mer ican physicist, and third female physicist (the others being and Sally Ride), to receive the honour. Wu, who passed away in 1997 aged 84, worked for the before joining Columbia University, where she made groundbreaking studies of . Her most definitive achievement was her 1956 experiment with 60Co nuclei, which showed that parity is violated by the . The discovery resulted in the award of the 1957 to theorists Lee and Yang, but the prize committee did not acknowledge Wu’s work. USPS

From the archive: June 1981 Making a splash Beyond the Standard Model On 1 April, par t icle physicists at Har v ard took a sidew ays glance at t he field by publishing “The arX iv digest you w ish you had ever y day” Following the success of the unification (arX iv:2103.17198). Leading w it h a finance-t hemed ta ke on t he R K and of electromagnetic and weak forces, muon g–2 updates, the fake journal carries classified ads for a box of theorists have proposed a unification of

CERN 380.12.80 CERN dark-mat ter models (“FREE!! Accidentally acquired too many of t hem. the electroweak and strong forces. This Fair condition, may require some tuning...”), (“Beautiful [Grand Unification] theory predicts the and mint condition, but we just never got the chance to use it… No unstable proton. Current thinking strings attached…”), along with career opportunities for a data scientist gives protons a lifetime of around 1031 (“Sell your soul, but not completely…”) and a wordsmith “to help us years. Such rare decays – about one per GAUGE: Generate Acronyms for Upcoming Galaxy-probing Experiments”, hundred kilograms of matter per A module of the detector to be ending with a crossword to rival even that of this magazine. century – require large, “passive” used in the Mont Blanc tunnel. detectors, situated deep underground Media corner the Ever Given container ship in to screen off stray cosmic muons and neutrinos. the Suez Canal, quoted in France 24 In the US, Irvine/Michigan/Brookhaven and Harvard/Purdue/ (30 March). “I believe we should commit to Wisconsin groups are assembling detectors, while in Europe an a CERN for AI, and locate it in “So, when you see someone experiment is being prepared by a CERN/Frascati/Milan/Torino the most competitive AI region bemoaning the woes of collaboration for installation in the Mont Blanc tunnel. of Europe.” fundamental physics, take The Italian Government has approved a project to be built as an them seriously – but don’t let it international laboratory under the Gran Sasso mountain some Jörgen Warborn, an MEP with the get you down. Just find a good 150 km from Rome, capable of housing 10,000 ton detectors. European People’s Party, quoted in Science|Business (25 Marc h). article on condensed-matter In Japan, a Tokyo/KEK/Tsukuba project, with a 1000 ton detector physics and read that.” 1000 m below ground, is expected to be operational by April 1982. “We were actually shaking when Mathematical physicist  Based on text from pp195–196 of CERN Courier June 1981. we first looked at the results, we John Baez writing in Nautilus were that excited.” Compiler’s note (24 February) about “the joy of LHCb researcher Mitesh Patel None of these mammoths, nor any of their successors to date, have observed c onde n s e d m at te r”. speaking to BBC News about , and the inferred half-life is now at least 1034 years. With the the latest measurement of R “The countries and regions that age of the universe estimated at some 1.4 × 1010 years, maybe protons are K (23 Marc h). invested in fundamental research forever. But, large detectors deep underground, water or ice are good at and technology are the ones that registering naturally occurring exotic events, and their discovery of “It’s all about physics and most are now global powers.” trans-flavour neutrinos has exposed another lacuna in the Standard Model physical laws are not that difficult ALPHA-collaboration member (SM). Identity oscillations among the three neutrino types can only occur if – the trick is to make them work for Muhammad Sameed speaking they have mass, but the SM Higgs field does not naturally provide mass for you and not against you.” to The Express Tribune neutrinos. And solving this mystery may also solve another, the lack of Peter Berdowski, CEO of Boskalis, (4 April) about CERN and antimatter in the universe. the company in charge of moving laser-cooled antihydrogen.

74 CERN COURIER MAY/JUNE 2021

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