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CERN Courier–Digital Edition
CERNMarch/April 2021 cerncourier.com COURIERReporting on international high-energy physics WELCOME CERN Courier – digital edition Welcome to the digital edition of the March/April 2021 issue of CERN Courier. 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 100 TeV, 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 HADRON COLLIDERS target gravitational waves (p10); X-rays go behind the scenes of supernova 50 years of discovery 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. 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 EDITOR: MATTHEW CHALMERS, CERN DIGITAL EDITION CREATED BY IOP PUBLISHING ATLAS spots rare Higgs decay Weinberg on effective field theory Hunting for WISPs CCMarApr21_Cover_v1.indd 1 12/02/2021 09:24 CERNCOURIER www. -
Very Forward Photon Production in Proton-Proton Collisions Measured by the Lhcf Experiment at the Large Hadron Collider
Very forward photon production in proton-proton collisions measured by the LHCf experiment at the Large Hadron Collider Author: Alessio Tiberio Supervisor: Lorenzo Bonechi The LHC-forward (LHCf) experiment, situated at the LHC accelerator, has measured neutral particles production in a very forward region (pseudo-rapidity η > 8:4) in proton-proton and proton- lead collisions. The main purpose of the LHCf experiment is to test hadronic interaction models used in ground based cosmic rays experiments to simulate cosmic rays induced air-showers in the Earth's atmosphere. Highest energy cosmic rays can only be detected from secondary particles which are produced by the interaction of the primary particle with nuclei of the atmosphere. Studying the development of air showers, it is possible to reconstruct the type and kinematic parameters of primary particle. For this reason, Monte Carlo (MC) simulations with accurate hadronic interaction models are needed to reproduce the development of air-showers. Since the energy flow of secondary particles is concentrated in the forward direction, measurements of particle production at high pseudo-rapidity (i.e. small angles) are very important. Furthermore, soft QCD interactions (non perturbative regime) dominates in the very forward region and MC simulations of air showers are based on phenomenological model, so inputs from experimental data are crucial. The experiment is composed by two independent detectors (Arm1 and Arm2 ) located at 140 m from the ATLAS's interaction point (IP1) on opposite sides [1]. Detectors are placed inside the Target Neutral Absorber (TAN), where the beam pipe from IP1 turns into two separates tubes: the position between the two beam pipes allows to measure particles produced at zero degrees. -
Slides Lecture 1
Advanced Topics in Particle Physics Probing the High Energy Frontier at the LHC Ulrich Husemann, Klaus Reygers, Ulrich Uwer University of Heidelberg Winter Semester 2009/2010 CERN = European Laboratory for Partice Physics the world’s largest particle physics laboratory, founded 1954 Historic name: “Conseil Européen pour la Recherche Nucléaire” Lake Geneva Proton-proton2500 employees, collider almost 10000 guest scientists from 85 nations Jura Mountains 8.5 km Accelerator complex Prévessin site (approx. 100 m underground) (France) Meyrin site (Switzerland) Probing the High Energy Frontier at the LHC, U Heidelberg, Winter Semester 09/10, Lecture 1 2 Large Hadron Collider: CMS Experiment: Proton-Proton and Multi Purpose Detector Lead-Lead Collisions LHCb Experiment: B Physics and CP Violation ALICE-Experiment: ATLAS Experiment: Heavy Ion Physics Multi Purpose Detector Probing the High Energy Frontier at the LHC, U Heidelberg, Winter Semester 09/10, Lecture 1 3 The Lecture “Probing the High Energy Frontier at the LHC” Large Hadron Collider (LHC) at CERN: premier address in experimental particle physics for the next 10+ years LHC restart this fall: first beam scheduled for mid-November LHC and Heidelberg Experimental groups from Heidelberg participate in three out of four large LHC experiments (ALICE, ATLAS, LHCb) Theory groups working on LHC physics → Cornerstone of physics research in Heidelberg → Lots of exciting opportunities for young people Probing the High Energy Frontier at the LHC, U Heidelberg, Winter Semester 09/10, Lecture 1 4 Scope -
Detection of Cosmic Rays at the LHC Detection of Cosmic Rays at the LHC
Particle and Astroparticle Physics at the Large Hadron Collider --Hadronic Interactions-- Albert De Roeck CERN, Geneva, Switzerland Antwerp University Belgium UC-Davis California USA NTU, Singapore November 15th 2019 Outline • Introduction on the LHC and LHC physics program • LHC results for Astroparticle physics • Measurements of event characteristics at 13 TeV • Forward measurements • Cosmic ray measurements • LHC and light ions? • Summary The LHC Machine and Experiments MoEDAL LHCf FASER totem CM energy → Run-1: (2010-2012) 7/8 TeV Run-2: (2015-2018) 13 TeV -> Now 8 experiments Run-2 starts proton-proton Run-2 finished 24/10/18 6:00am 2018 2010-2012: Run-1 at 7/8 TeV CM energy Collected ~ 27 fb-1 2015-2018: Run-2 at 13 TeV CM Energy Collected ~ 140 fb-1 2021-2023/24 : Run-3 Expect ⇨ 14 TeV CM Energy and ~ 200/300 fb-1 The LHC is also a Heavy Ion Collider ALICE Data taking during the HI run • All experiments take AA or pA data (except TOTEM) Expected for Run-3: in addition short pO and OO runs ⇨ pO certainly of interest for Cosmic Ray Physics Community! 4 10 years of LHC Operation • LHC: 7 TeV in March 2010 ->The highest energy in the lab! • LHC @ 13 TeV from 2015 onwards March 30 2010 …waiting.. • Most important highlight so far: …since 4:00 am The discovery of a Higgs boson • Many results on Standard Model process measurements, QCD and particle production, top-physics, b-physics, heavy ion physics, searches, Higgs physics • Waiting for the next discovery… -> Searches beyond the Standard Model 12:58 7 TeV collisions!!! New Physics Hunters -
Event Recorded by ATLAS When the LHC's Beam 2 Reached Closed
A ‘beam splash’ event recorded by ATLAS when the LHC’s beam 2 reached closed collimators near the detector on 20 November. 12 | CERN “The imminent start-up of the LHC is an event that excites everyone who has an interest in the fundamental physics of the Universe.” Kaname Ikeda, ITER Director-General, CERN Bulletin, 19 October 2009. Physics and Experiments The moment that particle physicists around the world had been The EMCal is an upgrade for ALICE, having received full waiting for finally arrived on 20 November 2009 when protons approval and construction funds only in early 2008. It will detect circulated again round the LHC. Over the following days, the high-energy photons and neutral pions, as well as the neutral machine passed a number of milestones, from the first collisions component of ‘jets’ of particles as they emerge from quark� at 450 GeV per beam to collisions at a total energy of 2.36 TeV gluon plasma formed in collisions between heavy ions; most — a world record. At the same time, the LHC experiments importantly, it will provide the means to select these events on began to collect data, allowing the collaborations to calibrate line. The EMCal is basically a matrix of scintillator and lead, detectors and assess their performance prior to the real attack which is contained in ‘supermodules’ that weigh about eight tonnes. It will consist of ten full supermodules and two partial on high-energy physics in 2010. supermodules. The repairs to the LHC and subsequent consolidation work For the ATLAS Collaboration, crucial repair work included following the incident in September 2008 took approximately modifications to the cooling system for the inner detector. -
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. -
Sub Atomic Particles and Phy 009 Sub Atomic Particles and Developments in Cern Developments in Cern
1) Mahantesh L Chikkadesai 2) Ramakrishna R Pujari [email protected] [email protected] Mobile no: +919480780580 Mobile no: +917411812551 Phy 009 Sub atomic particles and Phy 009 Sub atomic particles and developments in cern developments in cern Electrical and Electronics Electrical and Electronics KLS’s Vishwanathrao deshpande rural KLS’s Vishwanathrao deshpande rural institute of technology institute of technology Haliyal, Uttar Kannada Haliyal, Uttar Kannada SUB ATOMIC PARTICLES AND DEVELOPMENTS IN CERN Abstract-This paper reviews past and present cosmic rays. Anderson discovered their existence; developments of sub atomic particles in CERN. It High-energy subato mic particles in the form gives the information of sub atomic particles and of cosmic rays continually rain down on the Earth’s deals with basic concepts of particle physics, atmosphere from outer space. classification and characteristics of them. Sub atomic More-unusual subatomic particles —such as particles also called elementary particle, any of various self-contained units of matter or energy that the positron, the antimatter counterpart of the are the fundamental constituents of all matter. All of electron—have been detected and characterized the known matter in the universe today is made up of in cosmic-ray interactions in the Earth’s elementary particles (quarks and leptons), held atmosphere. together by fundamental forces which are Quarks and electrons are some of the elementary represente d by the exchange of particles known as particles we study at CERN and in other gauge bosons. Standard model is the theory that laboratories. But physicists have found more of describes the role of these fundamental particles and these elementary particles in various experiments. -
Heavy-Ion Collisions at the Dawn of the Large Hadron Collider Era
Heavy-Ion Collisions at the Dawn of the Large Hadron Collider Era J. Takahashi Universidade Estadual de Campinas, São Paulo, Brazil Abstract In this paper I present a review of the main topics associated with the study of heavy-ion collisions, intended for students starting or interested in the field. It is impossible to summarize in a few pages the large amount of information that is available today, after a decade of operations of the Relativistic Heavy Ion Collider and the beginning of operations at the Large Hadron Collider. Thus, I had to choose some of the results and theories in order to present the main ideas and goals. All results presented here are from publicly available references, but some of the discussions and opinions are my personal view, where I have made that clear in the text. 1 Introduction In this very exciting field of science, we use particle accelerators to collide heavy ions such as lead or gold nuclei, instead of colliding single protons or electrons. By doing so, we produce a much more violent collision in which a large number of particles are created and a considerable amount of energy is deposited in a volume bigger than the size of a single proton. As a result, a highly excited state of matter is created, and this state can have characteristics different from those of regular hadronic matter. It is postulated that, if the energy density is high enough, the system formed will be in a state where quarks and gluons are no longer confined into hadrons and thus exhibit partonic degrees of freedom [1,2]. -
Particle Accelerators and Experiments Albert De Roeck CERN, Geneva, Switzerland Antwerp University Belgium UC-Davis California USA NTU, Singapore
Particle Accelerators and Experiments Albert De Roeck CERN, Geneva, Switzerland Antwerp University Belgium UC-Davis California USA NTU, Singapore March 30th- April 2nd Muscat 1 Part I Accelerators 2 Different types of Methodology tools and equipment are needed to observe different sizes of object Only particle accelerators can explore the tiniest objects in the 5 Universe 5 Accelerators are Powerful Microscopes Planck constant They make high energy particle beams h = momentum that allow us to see small things. wavelength p ~ energy seen by low energy seen by high energy beam of particles beam of particles (poorer resolution) (better resolution) High Energy Physics Experiments Rutherford experiment (1909) Centre of mass energy squared s=E1m2 Centre of mass energy squared s=4E1E2 Detectors techniques have followed these developments Accelerators for Charged Particles 9 Recent High Energy Colliders Highest energies can be reached with proton colliders Machine Year Beams Energy (s) Luminosity SPPS (CERN) 1981 pp 630-900 GeV 6.1030cm-2s-1 Tevatron (FNAL) 1987 pp 1800-2000 GeV 1031-1032cm-2s-1 SLC (SLAC) 1989 e+e- 90 GeV 1030cm-2s-1 LEP (CERN) 1989 e+e- 90-200 GeV 1031-1032cm-2s-1 HERA (DESY) 1992 ep 300 GeV 1031-1032cm-2s-1 RHIC (BNL) 2000 pp /AA 200-500 GeV 1032cm-2s-1 LHC (CERN) 2009 pp (AA) 7-14 TeV 1033-1034cm-2s-1 Luminosity = number of events/cross section/sec • Limits on circular machines – Proton colliders: Dipole magnet strength superconducting magnets – Electron colliders: Synchrotron10 radiation/RF power: loss ~E4/R2 How Many Accelerators Worldwide? a) 1-10 b) 10-100 c) 100-1,000 d) 1,000-10,000 e) > 10,000 11 Accelerators Worldwide > 25,000 accelerators in use 12 Accelerators Worldwide 44% Radio- therapy 13 Accelerators Worldwide 44% 40% Radio- Ion therapy implant. -
Femtoscopy of Proton-Proton Collisions in the ALICE Experiment
Femtoscopy of proton-proton collisions in the ALICE experiment DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Nicolas Bock, B.Sc. B.Eng., M.Sc. Graduate Program in Physics The Ohio State University 2011 Dissertation Committee: Professor Thomas J. Humanic, Advisor Professor Michael Lisa #1 Professor Klaus Honscheid #2 Professor Richard Furnstahl #3 c Copyright by Nicolas Bock 2011 Abstract The Large Ion Collider Experiment (ALICE) at CERN has been designed to study matter at extreme conditions of temperature and pressure, with the long term goal of observing deconfined matter (free quarks and gluons), study its properties and learn more details about the phase diagram of nuclear matter. The ALICE experiment provides excellent particle tracking capabilities in high multiplicity proton-proton and heavy ion collisions, allowing to carry out detailed research of nuclear matter. This dissertation presents the study of the space time structure of the particle emission region, also known as femtoscopy, in proton- proton collisions at 0.9, 2.76 and 7.0 TeV. The emission region can be characterized by taking advantage of the Bose-Einstein effect for identical particles, which causes an enhancement of produced identical pairs at low relative momentum. The geometry of the emission region is related to the relative momentum distribution of all pairs by the Fourier transform of the source function, therefore the measurement of the final relative momentum distribution allows to extract the initial space-time characteristics. Results show that there is a clear dependence of the femtoscopic radii on event multiplicity as well as transverse momentum, a signature of the transition of nuclear matter into its fundamental components and also of strong interaction among these. -
The Muon Puzzle in Cosmic-Ray Induced Air Showers and Its Connection to the Large Hadron Collider
The Muon Puzzle in cosmic-ray induced air showers and its connection to the Large Hadron Collider 1 2 Johannes Albrecht • Lorenzo Cazon • 1,? 3 Hans Dembinski • Anatoli Fedynitch • 4 5 Karl-Heinz Kampert • Tanguy Pierog • 1 6 Wolfgang Rhode • Dennis Soldin • 1 5 5 Bernhard Spaan • Ralf Ulrich • Michael Unger Abstract High-energy cosmic rays are observed indi- Hadron Collider. An effect that can potentially explain rectly by detecting the extensive air showers initiated the puzzle has been discovered at the LHC, but needs to in Earth's atmosphere. The interpretation of these be confirmed for forward produced hadrons with LHCb, observations relies on accurate models of air shower and with future data on oxygen beams. physics, which is a challenge and an opportunity to test QCD under extreme conditions. Air showers are Keywords cosmic rays, air showers, particle physics, hadronic cascades, which eventually decay into muons. strangeness enhancement, cosmic rays, mass composi- The muon number is a key observable to infer the tion mass composition of cosmic rays. Air shower simula- tions with state-of-the-art QCD models show a signif- icant muon deficit with respect to measurements; this 1 Introduction is called the Muon Puzzle. The origin of this discrep- ancy has been traced to the composition of secondary Cosmic rays are fully-ionised nuclei with relativistic particles in hadronic interactions. The muon discrep- kinetic energies that arrive at Earth. The elements ancy starts at the TeV scale, which suggests that this range from proton to iron, with a negligible fraction change in hadron composition is observable at the Large of heavier nuclei. -
Results from Lhcf Experiment
EPJ Web of Conferences 28, 02003 (2012) DOI: 10.1051/epjconf/ 20122802003 C Owned by the authors, published by EDP Sciences, 2012 Results from LHCf Experiment Alessia Tricomi on behalf of the LHCf Collaboration University of Catania and INFN Catania, Italy √ Abstract.√ The LHCf experiment has taken data in 2009 and 2010 p-p collisions at LHC at s = 0.9 TeV and s = 7 TeV. The measurement of the forward neutral particle spectra produced in proton-proton collisions at LHC up to an energy of 14 TeV in the center of mass system are of fundamental importance to calibrate the Monte Carlo models widely used in the high energy cosmic ray (HECR) field, up to an equivalent laboratory energy of the order of 1017 eV. In this paper the first results on the inclusive photon spectrum measured by LHCf is reported. Comparison of this spectrum with the model expectations show significant discrepancies, mainly in the high energy region. In addition, perspectives for future analyses as well as the program for the next data taking period, in particular the possibility to take data in p-Pb collisions, will be discussed. 1 Introduction Each calorimeter (ARM1 and ARM2) has a double tower structure, with the smaller tower located at zero degree col- The LHCf experiment at LHC has been designed to cali- lision angle, approximately covering the region with pseudo- brate the hadron interaction models used in High Energy rapidity η > 10 and the larger one, approximately cover- Cosmic Ray (HECR) Physics through the measurement of ing the region with 8.4 < η < 10.