Particle Identification
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Decays of the Tau Lepton*
SLAC - 292 UC - 34D (E) DECAYS OF THE TAU LEPTON* Patricia R. Burchat Stanford Linear Accelerator Center Stanford University Stanford, California 94305 February 1986 Prepared for the Department of Energy under contract number DE-AC03-76SF00515 Printed in the United States of America. Available from the National Techni- cal Information Service, U.S. Department of Commerce, 5285 Port Royal Road, Springfield, Virginia 22161. Price: Printed Copy A07, Microfiche AOl. JC Ph.D. Dissertation. Abstract Previous measurements of the branching fractions of the tau lepton result in a discrepancy between the inclusive branching fraction and the sum of the exclusive branching fractions to final states containing one charged particle. The sum of the exclusive branching fractions is significantly smaller than the inclusive branching fraction. In this analysis, the branching fractions for all the major decay modes are measured simultaneously with the sum of the branching fractions constrained to be one. The branching fractions are measured using an unbiased sample of tau decays, with little background, selected from 207 pb-l of data accumulated with the Mark II detector at the PEP e+e- storage ring. The sample is selected using the decay products of one member of the r+~- pair produced in e+e- annihilation to identify the event and then including the opposite member of the pair in the sample. The sample is divided into subgroups according to charged and neutral particle multiplicity, and charged particle identification. The branching fractions are simultaneously measured using an unfold technique and a maximum likelihood fit. The results of this analysis indicate that the discrepancy found in previous experiments is possibly due to two sources. -
HERA Collisions CERN LHC Magnets
The Gallex (gallium-based) solar neutrino experiment in the Gran Sasso underground Laboratory in Italy has seen evidence for neutrinos from the proton-proton fusion reaction deep inside the sun. A detailed report will be published in our next edition. again, with particles taken to 26.5 aperture models are also foreseen to GeV and initial evidence for electron- CERN test coil and collar assemblies and a proton collisions being seen. new conductor distribution will further Earlier this year, the big Zeus and LHC magnets improve multipole components. H1 detectors were moved into A number of other models and position to intercept the first HERA With test magnets for CERN's LHC prototypes are being built elsewhere collisions, and initial results from this proton-proton collider regularly including a twin-aperture model at new physics frontier are eagerly attaining field strengths which show the Japanese KEK Laboratory and awaited. that 10 Tesla is not forbidden terri another in the Netherlands (FOM-UT- tory, attention turns to why and NIHKEF). The latter will use niobium- where quenches happen. If 'training' tin conductor, reaching for an even can be reduced, superconducting higher field of 11.5 T. At KEK, a magnets become easier to commis single aperture configuration was sion. Tests have shown that successfully tested at 4.3 K, reaching quenches occur mainly at the ends of the short sample limit of the cable the LHC magnets. This should be (8 T) in three quenches. This magnet rectifiable, and models incorporating was then shipped to CERN for HERA collisions improvements will soon be reassem testing at the superfluid helium bled by the industrial suppliers. -
Introduction to Subatomic- Particle Spectrometers∗
IIT-CAPP-15/2 Introduction to Subatomic- Particle Spectrometers∗ Daniel M. Kaplan Illinois Institute of Technology Chicago, IL 60616 Charles E. Lane Drexel University Philadelphia, PA 19104 Kenneth S. Nelsony University of Virginia Charlottesville, VA 22901 Abstract An introductory review, suitable for the beginning student of high-energy physics or professionals from other fields who may desire familiarity with subatomic-particle detection techniques. Subatomic-particle fundamentals and the basics of particle in- teractions with matter are summarized, after which we review particle detectors. We conclude with three examples that illustrate the variety of subatomic-particle spectrom- eters and exemplify the combined use of several detection techniques to characterize interaction events more-or-less completely. arXiv:physics/9805026v3 [physics.ins-det] 17 Jul 2015 ∗To appear in the Wiley Encyclopedia of Electrical and Electronics Engineering. yNow at Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723. 1 Contents 1 Introduction 5 2 Overview of Subatomic Particles 5 2.1 Leptons, Hadrons, Gauge and Higgs Bosons . 5 2.2 Neutrinos . 6 2.3 Quarks . 8 3 Overview of Particle Detection 9 3.1 Position Measurement: Hodoscopes and Telescopes . 9 3.2 Momentum and Energy Measurement . 9 3.2.1 Magnetic Spectrometry . 9 3.2.2 Calorimeters . 10 3.3 Particle Identification . 10 3.3.1 Calorimetric Electron (and Photon) Identification . 10 3.3.2 Muon Identification . 11 3.3.3 Time of Flight and Ionization . 11 3.3.4 Cherenkov Detectors . 11 3.3.5 Transition-Radiation Detectors . 12 3.4 Neutrino Detection . 12 3.4.1 Reactor Neutrinos . 12 3.4.2 Detection of High Energy Neutrinos . -
Trigger and Data Acquisition
Trigger and data acquisition N. Ellis CERN, Geneva, Switzerland Abstract The lectures address some of the issues of triggering and data acquisition in large high-energy physics experiments. Emphasis is placed on hadron-collider experiments that present a particularly challenging environment for event se- lection and data collection. However, the lectures also explain how T/DAQ systems have evolved over the years to meet new challenges. Some examples are given from early experience with LHC T/DAQ systems during the 2008 single-beam operations. 1 Introduction These lectures concentrate on experiments at high-energy particle colliders, especially the general- purpose experiments at the Large Hadron Collider (LHC) [1]. These experiments represent a very chal- lenging case that illustrates well the problems that have to be addressed in state-of-the-art high-energy physics (HEP) trigger and data-acquisition (T/DAQ) systems. This is also the area in which the author is working (on the trigger for the ATLAS experiment at LHC) and so is the example that he knows best. However, the lectures start with a more general discussion, building up to some examples from LEP [2] that had complementary challenges to those of the LHC. The LEP examples are a good reference point to see how HEP T/DAQ systems have evolved in the last few years. Students at this school come from various backgrounds — phenomenology, experimental data analysis in running experiments, and preparing for future experiments (including working on T/DAQ systems in some cases). These lectures try to strike a balance between making the presentation accessi- ble to all, and going into some details for those already familiar with T/DAQ systems. -
India-CMS Newsletter Member Institutes/ Universities of India-CMS
India-CMS Newsletter Member Institutes/ Universities of India-CMS Vol 1. No. 1, July 2015 1. Nuclear Physics Division (NPD) Bhabha Atomic Research Center (BARC) Mumbai http://www.barc.gov.in/ First volume produced at: 2. Indian Institute of Science Education and Research (IISER) Department of Physics Pune http://www.iiserpune.ac.in Panjab University Sector 14 Chandigarh - 160014 3. Indian Institute of Technology (IIT), Bhubaneswar Bhubaneswar http:// www.iitbbs.ac.in 4. Department of Physics Indian Institute of Technology (IIT), Bombay Mumbai http://www.iitb.ac.in/en/education/academic-divisions 5. Indian Institute of Technology (IIT), Madras Chennai https://www.iitm.ac.in 6. School of Physical Sciences National Institute of Science Education and Research (NISER), Edited and Compiled by: Bhubaneswar http://physics.niser.ac.in/ Manjit Kaur Department of Physics 7. Department of Physics Panjab University Panjab University Chandigarh Chandigarh http://physics.puchd.ac.in/ [email protected] 8. Division of High Energy Nuclear and Particle Physics Ajit Mohanty Saha Institute of Nuclear Physics (SINP) Director Kolkata http://www.saha.ac.in/web/henppd-home Saha Institute of Nuclear Physics (SINP) Kolkatta 9. Department of High Energy Physics [email protected] Tata Institute of Fundamental Research (TIFR), Mumbai http://www.tifr.res.in/ ~dhep/ Abhimanyu Chawla Department of Physics 10. Department of Physics & Astrophysics Panjab University University of Delhi Chandigarh Delhi http://www.du.ac.in/du/index.php?page=physics-astrophysics [email protected] 11. Visva Bharti Santiniketan, West Bengal 731204 http://www.visvabharati.ac.in/Address.html 1 2 Contents Message ........................................................................................................................................................ 3 Message ....................................................................................................................................................... -
Machine-Learning-Based Global Particle-Identification Algorithms At
Machine-Learning-based global particle-identification algorithms at the LHCb experiment Denis Derkach1;2, Mikhail Hushchyn1;2;3, Tatiana Likhomanenko2;4, Alex Rogozhnikov2, Nikita Kazeev1;2, Victoria Chekalina1;2, Radoslav Neychev1;2, Stanislav Kirillov2, Fedor Ratnikov1;2 on behalf of the LHCb collaboration 1 National Research University | Higher School of Economics, Moscow, Russia 2 Yandex School of Data Analysis, Moscow, Russia 3 Moscow Institute of Physics and Technology, Moscow, Russia 4 National Research Center Kurchatov Institute, Moscow, Russia E-mail: [email protected] Abstract. One of the most important aspects of data analysis at the LHC experiments is the particle identification (PID). In LHCb, several different sub-detectors provide PID information: two Ring Imaging Cherenkov (RICH) detectors, the hadronic and electromagnetic calorimeters, and the muon chambers. To improve charged particle identification, we have developed models based on deep learning and gradient boosting. The new approaches, tested on simulated samples, provide higher identification performances than the current solution for all charged particle types. It is also desirable to achieve a flat dependency of efficiencies from spectator variables such as particle momentum, in order to reduce systematic uncertainties in the physics results. For this purpose, models that improve the flatness property for efficiencies have also been developed. This paper presents this new approach and its performance. 1. Introduction Particle identification (PID) algorithms play a crucial part in any high-energy physics analysis. A higher performance algorithm leads to a better background rejection and thus more precise results. In addition, an algorithm is required to work with approximately the same efficiency in the full available phase space to provide good discrimination for various analyses. -
Particle Identification
Particle Identification Graduate Student Lecture Warwick Week Sajan Easo 28 March 2017 1 Outline Introduction • Main techniques for Particle Identification (PID) Cherenkov Detectors • Basic principles • Photodetectors • Example of large Cherenkov detector in HEP Detectors using Energy Loss (dE/dx) from ionization and atomic excitation Time of Flight (TOF) Detectors Transition Radiation Detectors (TRD) More Examples of PID systems • Astroparticle Physics . Not Covered : PID using Calorimeters . Focus on principles used in the detection methods. 2 Introduction . Particle Identification is a crucial part of several experiments in Particle Physics. • goal: identify long-lived particles which create signals in the detector : electrons, muons ,photons , protons, charged pions, charged kaons etc. • short-lived particles identified from their decays into long-lived particles • quarks, gluons : inferred from hadrons, jets of particles etc , that are created. In the experiments at the LHC: Tracking Detector : Directions of charged particles (from the hits they create in silicon detectors, wire chambers etc.) Tracking Detector + Magnet : Charges and momenta of the charged particles (Tracking system ) Electromagnetic Calorimeter (ECAL) : Energy of photons, electrons and positrons (from the energy deposited in the clusters of hits they create in the shape of showers ). Hadronic Calorimeter (HCAL) : Energy of hadrons : protons, charged pions etc. ( from the energy deposited in the clusters of hits they create in the shape of showers ) Muon Detector : Tracking detector for muons, after they have traversed the rest of the detectors 3 Introduction Some of the methods for particle identification: Electron : ECAL cluster has a charged track pointing to it and its energy from ECAL is close to its momentum from Tracking system. -
QCD Studies at L3
QCD Studies at L3 Swagato Banerjee Tata Institute of Fundamental Research Mumbai 400 005 2002 QCD Studies at L3 Swagato Banerjee Tata Institute of Fundamental Research Mumbai 400 005 A Thesis submitted to the University of Mumbai for the degree of Doctor of Philosophy in Physics March, 2002 To my parents Acknowledgement It has been an extremely enlightening and enriching experience working with Sunanda Banerjee, supervisor of this thesis. I would like to thank him for his forbearance and encouragement and for teaching me the different aspects of the subject with lots of patience. I thank all the members of the Department of High Energy Physics of Tata Institute of Fundamental Research (TIFR) for providing various facilities and support, and ideal ambiance for research. In particular, I would like to thank B.S. Acharya, T. Aziz, Sudeshna Banerjee, B.M. Bellara, P.V. Deshpande, S.T. Divekar, S.N. Ganguli, A. Gurtu, M.R. Krishnaswamy, K. Mazumdar, M. Maity, N.K. Mondal, V.S. Narasimham, P.M. Pathare, K. Sudhakar and S.C. Tonwar. Asesh Dutta, Dilip Ghosh, S. Gupta, Krishnendu Mukherjee, Sreerup Ray Chaudhuri, D.P. Roy, Sourov Roy, Gavin Salam and K. Sridhar provided valuable theoretical insight on various occasions. My heartfelt thanks to them. I thank the European Organisation for Nuclear Research (CERN) for its kind hospitality and all the members of the Large Electron Positron (LEP) accelerator group for successful operation over the last decade. The members of the L3 collaboration and the LEP QCD Working Group provided me a stim- ulating working environment. In particular, I thank Pedro Abreu, Satyaki Bhattacharya, Gerard Bobbink, Ingrid Clare, Robert Clare, Glen Cowan, Aaron Dominguez, Dominique Duchesneau, John Field, Ian Fisk, Roger Jones, Mehnaz Hafeez, Stephan Kluth, Wolfgang Lohmann, Wes- ley Metzger, Peter Molnar, Oliver Passon, Martin Pohl, Subir Sarkar, Chris Tully and Micheal Unger. -
The a to Z of Accelerators
present explanation for this behav The long timescale needed to terparts. But superconductivity iour is that superconductivity exists produce acceptable conductors of above 77K provides a powerful in many discrete regions within niobium-tin (10-12 years) following stimulant to solve the technological the sample but only weak coupling its discovery in 1962 inevitably problems of dealing with brittle exists between these regions. This comes to mind in assessing the materials. The next few months weak coupling is strongly dimin potential timeîscales for developing could give us many more surprises ished by an external field. Electro high field magnets with the new in an area where none were sus magnetic and structural character materials. These new oxides, like pected only a few months ago. izations of these compounds are niobium-tin and the other A15 The discovery of Bednorz and proceeding furiously and we may compounds are inherently brittle Muller has given a profound new soon expect to know whether this and this is bound to affect their stimulus to superconductivity and percolative nature of the supercon application in magnets, just as the last discovery has surely not ductivity is inherent in the material large scale construction of niobium- yet been made. or results from the way present tin magnets has lagged behind samples are being prepared. their ductile niobium-titanium coun The A to Z of accelerators With great skill, the organizers physics but this information was 1965. The attendance of over of the 1987 Particle Accelerator surpassed in volume by reports 1100 was another reflection of Conference arranged a vast pro from the many other areas where the wealth of activity in the field. -
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Baryon Production in Z Decay
Baryon Pro duction in Z Decay Christopher G Tully A DISSERTATION PRESENTED TO THE FACULTY OF PRINCETON UNIVERSITY IN CANDIDACY FOR THE DEGREE OF DOCTOR OF PHILOSOPHY RECOMMENDED FOR ACCEPTANCE BY THE DEPARTMENT OF PHYSICS January ABSTRACT How quarks b ecome conned into ordinary matter is a dicult theoretical question The p ointatwhich this o ccurs cannot b e measured by exp eriment but other prop erties related to connement can Baryon pro duction is a situation where one typ e of connement is chosen over another In this thesis pro duction rate measurements have b een p erformed for and baryons pro duced in hadronic decays of the Z The rates are low compared to meson pro duction but the particular prop erties of and decay allow these particles to be identied amongst the many mesons accompanying them The average number of and per hadronic Z decay was found to be D E N stat syst and D E N stat syst resp ectively These measurements take advantage of the unique photon detection capa bility of the L Exp eriment The rates are in agreement with those measured by other LEP detectors iii CONTENTS Abstract iii Acknowledgements v Intro duction Particle Creation and Detection Searching for Particle Decays Going Back in Time The History Behind SubNuclear Particles Quarks Discovery of the Pion The Quark Constituent Mo del -
Nov/Dec 2020
CERNNovember/December 2020 cerncourier.com COURIERReporting on international high-energy physics WLCOMEE CERN Courier – digital edition ADVANCING Welcome to the digital edition of the November/December 2020 issue of CERN Courier. CAVITY Superconducting radio-frequency (SRF) cavities drive accelerators around the world, TECHNOLOGY transferring energy efficiently from high-power radio waves to beams of charged particles. Behind the march to higher SRF-cavity performance is the TESLA Technology Neutrinos for peace Collaboration (p35), which was established in 1990 to advance technology for a linear Feebly interacting particles electron–positron collider. Though the linear collider envisaged by TESLA is yet ALICE’s dark side to be built (p9), its cavity technology is already established at the European X-Ray Free-Electron Laser at DESY (a cavity string for which graces the cover of this edition) and is being applied at similar broad-user-base facilities in the US and China. Accelerator technology developed for fundamental physics also continues to impact the medical arena. Normal-conducting RF technology developed for the proposed Compact Linear Collider at CERN is now being applied to a first-of-a-kind “FLASH-therapy” facility that uses electrons to destroy deep-seated tumours (p7), while proton beams are being used for novel non-invasive treatments of cardiac arrhythmias (p49). Meanwhile, GANIL’s innovative new SPIRAL2 linac will advance a wide range of applications in nuclear physics (p39). Detector technology also continues to offer unpredictable benefits – a powerful example being the potential for detectors developed to search for sterile neutrinos to replace increasingly outmoded traditional approaches to nuclear nonproliferation (p30).