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CERNCOURIER

  • March/April 2021 cerncourier.com
  • Reporting on international high-energy physics

W E L C O M E

CERN Courier – digital edition

Welcome to the digital edition of the March/April 2021 issue of CERN Courie r. Hadron colliders have contributed to a golden era of discovery in high-energy physics, hosting experiments that have enabled physicists to unearth the cornerstones of the Standard Model. This success story began 50 years ago with CERN’s Intersecting Storage Rings (featured on the cover of this issue) and culminated in the Large Hadron Collider (p38) – which has spawned thousands

of papers in its first 10 years of operations alone (p47). It also bodes well for a

potential future circular collider at CERN operating at a centre-of-mass energy of at least 100TeV, a feasibility study for which is now in full swing.

Even hadron colliders have their limits, however. To explore possible new physics at the highest energy scales, physicists are mounting a series of experiments to search for very weakly interacting “slim” particles that arise from extensions in the Standard Model (p25).

Also celebrating a golden anniversary this year is the Institute for Nuclear Research in Moscow (p33), while, elsewhere in this issue: quantum sensors target gravitational waves (p10); X-rays go behind the scenes of supernova

1987A (p12); a high-performance computing collaboration forms to handle the

big-physics data onslaught (p22); Steven Weinberg talks about his latest work (p51); and much more.

  • HA
  • DR
  • ON
  • CO
  • LL

  • IDE
  • RS

  • 50 y
  • ear
  • s of
  • dis
  • cov

ery

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

ATLAS spots rare Higgs decay Weinberg on effective field theory Hunting for WISPs

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Volume 61 Number 2 march/april 2021

IN THIS ISSUE

It’s ALL

about the

DETAILS

Dalitzdecay ATLA S s pot s r ar e d eca y o f t h e H igg s b oson

UniversalsearchBaikal-GVD will continue the

StaffsearchCERN’s efforts to attract

  • to a photon and a low-mass electron or muon pair. 17
  • astrophysical neutrino search. 33
  • non-physicists into ke y r oles. 61

  • NeWS
  • people

  • ANALYSIS
  • ENERGY FRONTIERS
  • FIELD NOTES
  • CAREERS
  • OBITUARIES

AEgIS on track to test antimatter free fall
First evidence for rare

Higgs-boson decay

Tooling up to hunt dark

Jack Steinberger

Martinus Veltman Günther Plass

Acceleratingtalent at CERN

The challenge of attracting engineers, technicians

and others who build and

maintain CERN’s complex

infrastructure. 61

•••••••

matter Computing

•

NICA sees first beam

CLOUD and Arctic sea
Supersymmetry

collaboration kicks off

  • •
  • •

searches Precision

Quark-matter fireballs

in Protvino. 21

André Martin

  • •
  • •
  • •

  • ice Quantum sensing
  • leap for B0s Light shines

Stephanie Zimmermann Stephen Reucroft Jean-Claude Berset. 69

  • •
  • •

  • Farewell Daya Bay
  • inside lead nuclei. 17

•

The core of SN1987A. 7

•

FeaTureS

  • WISPS
  • INR RAS
  • HADRON COLLIDERS
  • LHC

Insearchof WISPs

New experiments will expand the search for axions and other weakly interacting ‘slim’ particles that could hail from far

above the TeV scale. 25

Discoverymachines

Lyn Evans and Peter Jenni look at the lessons learned from 50 years of experience with hadron colliders and

their detectors. 38

A decadeinLHC publications

Alex Kohls, Jens Vigen and Micha Moskovic

look back on the

Russia’sparticle- physicspowerhouse

The Institute for Nuclear Research in Moscow continues to leave its mark on neutrino and high-energy physics. 33

first 10 years of LHC

publications. 47

DeparTmeNTS opiNioN

  • VIEWPOINT
  • INTERVIEW
  • REVIEWS

FROM THE EDITOR

5
15

Power Supply Systems

Connectingphysics withsociety

We must communicate the applications and

impact of our field, argues Barbora Bruant

Gulejova. 49

Stillseeking solutions

Steven Weinberg reflects on effective field theory

and his latest attempt to understand the fermion

mass hierarchy. 51

Thehitchhiker’s guidetoweakdecays

An expedition to

NEWS DIGEST

Precision Current Measurements Beamline Electronic Instrumentation FMC and MicroTCA

APPOINTMENTS &AWARDS

62

new physics summits

RECRUITMENT BACKGROUND

64 74

Onthecover: CERN’s

Intersectin g S torag e R ings,

the firs t h adron collider. 38

The science of

learning physics. 57

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ack in the early 1960s, as this month’s cover feature Europeanstrategyforparticlephysics, CERNisexploringthe describes (p38), discussion raged at CERN about the mostambitiouslong-termtechnologicalpathinundertaking nextbeststepforparticlephysics.Atthetime,thehigh- a feasibility study for a future circular hadron collider with a energyfrontierwascommandedbythegreatprotonsynchro- centre-of-massenergyofatleast100TeV. Ifbuilt, thesuccess trons, such as Brookhaven’s Cosmotron and, later, CERN’s ofthismotherofallhadroncolliderswillhaveeachgeneration

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of proton beams for the production of new particles – the Know your limits hadron collider – was revving up in the sidelines. In Decem- As productive as hadron colliders are in probing nature at ber 1965 the CERN Council approved the construction of the the highest energies, many current mysteries, such as dark more technologically innovative Intersecting Storage Rings matter and the origin of neutrino masses, may well origi(ISR) over a very high-energy proton synchrotron, although thelatterwouldmaterialise10yearslaterintheSuperProton

Synchrotron (SPS). The ISR’s first proton–proton collisions,

whichreachedacentre-of-massenergyof62GeV, tookplace on 27 January 1971, opening the era of hadron colliders. From the ISR came the ingenious conversion of the SPS nate from phenomena at energy scales inaccessible to any collider imaginable. Fortunately, models involving such scales can be tested nowandinthenearfuturebya seriesofexperiments–some using magnets from the LHC andHERAinfact–searching for very weakly interacting “slim” particles that arise in extensions of the Stand-

ardModel(seep25). Effective fieldtheoryisanotherpower-

fultooltopursuesuchsignals fromfarbeyondtheTeVscale, explains Steven Weinberg in this issue’s interview (p51).
–into a proton–antiproton collider (SppS), the demonstration

of large-scale superconducting magnet technology for the Tevatron at Fermilab, and the LHC, whose elegant magnet design has enabled the highest collision energies (13TeV) and luminosities to date. Each machine, and its increasingly complex detectors, was a step into the unknown, requiring the invention of new technologies and sharp political and organisational skills to build and operate ever larger facil-

ities. The payoff was the discovery of the Standard Model’s

–cornerstones: the W and Z bosons at the SppS, the top quark

at the Tevatron, and the Higgs boson at the LHC. Not to be Discovery machine The LHC. omittedfromthehadron-beamcollidersuccessstoryarethe leapsinunderstandingofstronglyinteractingmatterbrought

Meanwhile at CERN: ATLAS reports the first evidence for a

Eachmachine, andits increasingly complex detectors, was astepinto the unknown

aboutbyBrookhaven’sRelativisticHeavy-IonColliderandthe rare“Dalitz”decayoftheHiggsboson(p17);pulsed-modeantiLHC, andthedeep-inelasticscatteringexperimentsatDESY’s hydrogen paves the way to test antimatter in free fall (p7); and so-faruniqueelectron–protoncolliderHERA, whichrevealed the CLOUD experiment reveals a new mechanism that could

  • the proton’s innards in full colour.
  • acceleratethelossofArcticseaice(p9).Elsewhereinthisissue:

Half a century after the ISR’s first collisions, and with at least quantum sensors target gravitational waves (p10); X-rays go

15 years of LHC operations still to come, particle physicists behindthescenesofsupernova1987A(p12);ahigh-performance

once again find themselves debating the next best step for the computing collaboration forms to handle the big-physics data field. True to form, as recommended by the 2020 update of the onslaught (p22); new twists in the ATOMKI tale (p74); and more.

Reporting on international high-energy physics

  • Editor
  • Laboratorycorrespondents

Argonne National Laboratory

Jefferson Laboratory

Kandice Carter

JINR Dubna B Starchenko KEK National Laboratory

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Lawrence Berkeley Laboratory Spencer Klein Los Alamos National Lab

Rajan Gupta

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SLAC National Accelerator Laboratory

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SNOLAB Samantha Kuula TRIUMF Laboratory

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Advertisement production Katie Graham Marketing and circulation Laura Gillham,

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NEWS

ANALYSIS

AntimAtter

FOR

AEgISontracktotestfreefallofantimatter

PROFESSIONALS

  • The AEgIS collaboration at CERN’s
  • schemeallowsthetimeatwhich90%of

theatomsareproducedtobedetermined with an uncertainty of around 100 ns. Further steps are required before the measurement of g can begin, explains Doser. These include the formation of a pulsed beam, greater quantities of antihydrogen, and the ability to make it colder. “Withonlythreemonthsofbeam timethisyear,andlotsofnewequipment to commission, most likely 2022 will be the year in which we establish pulsedbeam formation, which is a prerequisite forustoperformagravitymeasurement.”
AntiprotonDecelerator(AD)hasreported a milestone in its bid to measure the gravitational free fall of antimatter – a fundamentaltestoftheweakequivalence principle. Using a series of techniques developed in 2018, the team demon-

strated the first pulsed production of

antiatoms, which allows the time at which the antiatoms are formed to be knownwithhighaccuracy. Thisisakey step in determining “g” for antimatter.

“This is the first time that pulsed for-

mation of antihydrogen has been established on timescales that open the door tosimultaneousmanipulation, bylasers

Targeted approach

or external fields, of the formed atoms,

as well as to the possibility of applying thesamemethodtothepulsedformation ofotherantiprotonicatoms,”saysAEgIS spokesperson Michael Doser of CERN. “Knowing the moment of antihydrogen formation is a powerful tool.” Generalrelativity’sweakequivalence
Followingaproof-of-principlemeasurementofgforantihydrogenbytheALPHA collaborationin2013, ALPHA, AEgISand a third AD experiment, GBAR, are all targeting a measurement of g at the 1% level in the coming years. In contrast to AEgIS’s approach, whereby the vertical deviation of a pulsed horizontal beam of coldantihydrogenatomswillbemeasured

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    February 19, 2020 11:45 IJMPA S0217751X19420351 page 1 International Journal of Modern Physics A Vol. 34, No. 36 (2019) 1942035 (17 pages) c World Scientific Publishing Company DOI: 10.1142/S0217751X19420351 SixTrack V and runtime environment R. De Maria∗ Beam Department (BE-ABP-HSS), CERN, 1211, Geneva 23, Switzerland [email protected] J. Andersson, V. K. Berglyd Olsen, L. Field, M. Giovannozzi, P. D. Hermes, N. Høimyr, S. Kostoglou, G. Iadarola, E. Mcintosh, A. Mereghetti, J. Molson, D. Pellegrini, T. Persson and M. Schwinzerl CERN, 1211, Geneva 23, Switzerland E. H. Maclean CERN, 1211, Geneva 23, Switzerland University of Malta, Msida, MSD 2080, Malta K. N. Sjobak CERN, 1211, Geneva 23, Switzerland University of Oslo, Boks 1072 Blindern, 0316, Oslo, Norway I. Zacharov EPFL, Rte de la Sorge, 1015, Lausanne, Switzerland S. Singh Indian Institute of Technology Madras, IIT P.O., Chennai 600 036, India Int. J. Mod. Phys. A 2019.34. Downloaded from www.worldscientific.com Received 28 February 2019 Revised 5 December 2019 Accepted 5 December 2019 Published 17 February 2020 SixTrack is a single-particle tracking code for high-energy circular accelerators routinely used at CERN for the Large Hadron Collider (LHC), its luminosity upgrade (HL-LHC), the Future Circular Collider (FCC) and the Super Proton Synchrotron (SPS) simula- tions. The code is based on a 6D symplectic tracking engine, which is optimized for long-term tracking simulations and delivers fully reproducible results on several plat- forms. It also includes multiple scattering engines for beam{matter interaction studies, by INDIAN INSTITUTE OF TECHNOLOGY @ MADRAS on 04/19/20.
  • Atmospheric Nucleation and Growth in the CLOUD Experiment at CERN Jasper Kirkby and CLOUD Collaboration

    Atmospheric Nucleation and Growth in the CLOUD Experiment at CERN Jasper Kirkby and CLOUD Collaboration

    Atmospheric nucleation and growth in the CLOUD experiment at CERN Jasper Kirkby and CLOUD Collaboration Citation: AIP Conference Proceedings 1527, 278 (2013); doi: 10.1063/1.4803258 View online: http://dx.doi.org/10.1063/1.4803258 View Table of Contents: http://scitation.aip.org/content/aip/proceeding/aipcp/1527?ver=pdfcov Published by the AIP Publishing Articles you may be interested in Multi-species nucleation rates in CLOUD AIP Conf. Proc. 1527, 326 (2013); 10.1063/1.4803269 Ternary H 2 SO 4 - H 2 O - NH 3 neutral and charged nucleation rates for a wide range of atmospheric conditions AIP Conf. Proc. 1527, 310 (2013); 10.1063/1.4803265 Observations and models of particle nucleation near cloud outflows AIP Conf. Proc. 534, 831 (2000); 10.1063/1.1361988 Application of nucleation theories to atmospheric aerosol formation AIP Conf. Proc. 534, 711 (2000); 10.1063/1.1361961 Laboratory studies of ice nucleation in sulfate particles: Implications for cirrus clouds AIP Conf. Proc. 534, 471 (2000); 10.1063/1.1361909 Reuse of AIP Publishing content is subject to the terms at: https://publishing.aip.org/authors/rights-and-permissions IP: 131.215.225.131 On: Tue, 19 Apr 2016 20:27:43 Atmospheric Nucleation and Growth in the CLOUD Experiment at CERN Jasper Kirkbya and the CLOUD collaborationb aCERN, CH-1211 Geneva, Switzerland b Aerodyne Research Inc., Billerica, Massachusetts 01821, USA California Institute of Technology, Division of Chemistry and Chemical Engineering, Pasadena, California 91125, USA Carnegie Mellon University, Dep. of Chemical
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    Highlights from ALICE

    Highlights from ALICE Michael Weber for the ALICE Collaboration Quark Matter, Wuhan, 04-09 Nov 2019 Michael Weber (SMI) Opening the doors (December 2018) CERN-PHOTO-201812-335 2 Quark Matter, Wuhan, 04-09 Nov 2019 Michael Weber (SMI) Soon after CERN-PHOTO-201903-053 Quark Matter, Wuhan, 04-09 Nov 2019 Michael Weber (SMI) 3 Harvest of the past ten years Recorded L System Year(s) √s (TeV) int NN (for muon triggers) 2010,2011 2.76 ~75 μb-1 Pb–Pb 2015 5.02 ~0.25 nb-1 2018 5.02 ~0.55 nb-1 Xe–Xe 2017 5.44 ~0.3 μb-1 2013 5.02 ~15 nb-1 p–Pb 2016 5.02, 8.16 ~3 nb-1; ~25 nb-1 New for QM 2019: ~200 μb-1; ~100 nb-1; 2009-2013 0.9,2.76,7,8 ~1.5 pb-1; ~2.5 pb-1 ● Full 13 TeV pp data set with high-multiplicity triggers pp ● 2018 Pb-Pb with central and semi-central triggers 2015,2017 5.02 ~1.3 pb-1 ● Selected results out of 26 parallel talks, 2015-2018 13 ~36 pb-1 68 posters, and 18 new papers Labels used in this presentation: New since last QM New New preliminary for QM Final On arXiv for QM Quark Matter, Wuhan, 04-09 Nov 2019 Michael Weber (SMI) 4 Outline Initial state → Hadronic structure and photoproduction QGP - Macroscopic properties → Properties of QCD matter and the transition between phases QGP - Microscopic dynamics → Degrees of freedom at each stage and their interactions Small systems → Unified picture of QCD particle production from small to larger systems Hadron physics → LHC as laboratory for hadron interaction studies Following the open questions in the HL-LHC WG5 yellow report Quark Matter, Wuhan, 04-09 Nov 2019 Michael Weber (SMI) 5 ALICE parallel talks Initial state ● Low-mass dielectron measurements in pp, p-Pb and Pb-Pb collisions with ALICE at the LHC S.