DOCSLIB.ORG

The Omega-Minus Experiment

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Omega-Minus Experiment The Omega-Minus Experiment An account of the experiment, performed with Brookhaven National Laboratory's 33-billion-electron-volt accelerator, that confirmed the existence of a new particle predicted by the "eightfold way" by William B. Fowler and Nicholas P. Sarnios ong the landmarks of physics in properties the missing particle must delta-plus and delta-double-plus (with the 20th century are the success­ possess. two units of positive charge). The mem­ K ful predictions of theoretical The situation was somewhat like the bers of this quartet have a spin angular physics. The Davisson-Cermer experi­ one presented by Dmitri Mendeleev momentum of 3/2 units, positive parity ment showing that electrons behave like when he devised the periodic table of and an effective mass of 1,238 million waves (predicted by Louis de Broglie), the elements in 1869. Mendeleev saw electron volts. (In particle physics mass the discovery of the massless neutrino that there were three vacancies at cer­ is now commonly expressed in terms of (predicted by Wolfgang Pauli), the dis­ tain positions in his table, and he in­ energy.) Now, if one looks around for coveries of the positron and other anti­ sisted that elements corresponding to other known baryons that may belong to particles (predicted by P. A. M. Dirac) those vacancies, whose properties he the same family, the sigma particle of -these are some of the successes of described, must exist and would some­ mass 1,385 mev (million electron volts) hypotheses that to many seemed hardly day be found. They were discovered not immediately appears to be a likely rela­ more than speculations when they were long afterward. Similarly, the missing tive. Like the deltas, the three charge first proposed. Each was a concept in­ particle described by Cell-Mann, which versions of the sigma particle (sigma­ vented by abstract, mathematical rea­ he named omega-minus, was found minus, sigma-zero and sigma-plus) have soning based on earlier experimental when it was searched for, and it proved a spin angular momentum of 3/2 and results, and each was eventually veri­ to have exactly the properties specified positive parity. The quantum number fied by physical detection of the pre­ by the theory. describing the strangeness of the delta dicted phenomenon. The latest in this particles is zero; that of the sigmas is series of remarkable "inventions" is the This article will relate how the omega- minus one. The deltas have an isotopic omega-minus particle, whose existence minus was produced and identified. spin of 3/2; the sigmas, an isotopic spin was predicted only two years ago and The details of the theory need not con­ of I-a half-unit difference. Thus the has now been confirmed by actual pro­ cern us here; they were thoroughly dis­ sigma triplet, at a higher mass level than duction of the particle. cussed in the February issue by Cell­ the delta quartet, begins to form a sym­ There are special reasons why the Mann and his coauthors. It classifies metrical pyramid [see illustration on discovery of this particle has aroused the nuclear particles (baryons and mesons) page 42]. interest of physicists. It supports a by a system based on the branch of theory that shows promise of introduc­ mathematics called group theory. The ing some kind of order into the puz­ system is known as SU(3) symmetry and zling assortment of particles that physi­ has also been named the "eightfold cists have detected in their dissection of way," because it involves eight mathe­ the atomic nucleus. The theory was pro­ matical operators related to the quan­ BROOKHAVEN ACCELERATOR with posed in 1961 by Murray Cell-Mann of tum numbers of particles. which the omega·minus experiment was the California Institute of Technology According to this scheme the particles performed appears in the aerial photograph and independently by Yuval Ne'eman constituting a family must all have the on the opposite page. The ring.shaped con· of Tel Aviv University in Israel [see same spin angular momentum (speed of figuration of ground to the right of the "Strongly Interacting Particles," by intrinsic spin) and the same parity large building at left center is a mound cov­ Ceoffrey F. Chew, Murray Cell-Mann (left-handedness or right-handedness). ering the tunnel that houses the magnet ring in which protons are accelerated to 33 bil. and Arthur H. Rosenfeld; SCIENTIFIC They may differ in mass, electric charge lion electron volts. The beam of protons is AMERICAN, February]. It groups the and the properties known as "strange­ injected into the ring by a linear accelerator particles into families according to their ness" and "isotopic spin," but in these that is housed in the small building at lower quantum properties. Cell-Mann noted quantities they must be related to one right center. The main target area is in the that one of the families apparently was another by certain rules. building at left center. The accelerating incomplete. Nine members of the family The family with which we are con­ ring is some 800 feet in diameter. The accel· were known; the theory indicated there cerned starts with the baryons called erator, known as an alternating gradient syn­ should be a tenth, and it specified the delta particles-delta-minus, delta-zero, chrotron, has been in operation since 1960. 36 © 1964 SCIENTIFIC AMERICAN, INC © 1964 SCIENTIFIC AMERICAN, INC © 1964 SCIENTIFIC AMERICAN, INC What doublet might constitute the The new xi particles qualiRed for mem­ that was to engage a large number of next level of the pyramid? The dif­ bership in the family with the delta and physicists (including the authors of this ference in mass between the delta and sigma particles by their mass (very close article), engineers and technicians. the sigma particles, 147 mev, suggested to the predicted 1,532 mev). What was that the mass of the next pair of patti­ more, their strangeness was minus two, What interaction might produce the cles should be about 1,532 mev, 147 further conRrming their position in the omega particle? There was avail­ mev higher than that of the sigmas. No pyramid, because the strangeness quan­ able a beam of high-energy K mesons, such particle, bearing the right quantum tum numbers now ran: delta quartet, generated as secondary products by the numbers, had been detected. At the zero; sigma triplet, minus one; xi dou­ 33-bev alternating-gradient synchrotron. biennial International Conference on blet, minus two. Calculations suggested that sufficiently High Energy Physics in Ceneva in July, It was now possible to predict with energetic K-minus particles, on inter­ 1962, however, experimenters reported reasonable conRdence that the pyramid acting with target protons, would pro­ the discovery of a pair of xi particles must be crowned by a singlet at the duce the omega-minus baryon and K­ (xi-minus and xi-zero) of mass 1,530 apex-a particle of strangeness minus plus and K-zero mesons by the follow­ mev. Cell-Mann, who was present at three, spin 3/2, positive parity, nega­ ing reaction: K-+]J � n- + K+ + KO. the conference, immediately saw the tive charge and mass about 1,676 mev How much energy would the K-minus connection between this almost routine (146 mev higher than that of the projectiles need to generate this re­ announcement and the eightfold way. xi particles). A determined, full-scale action? The masses of the products search for this particle, already named (omega-minus, K-plus and K-zero) re­ omega-minus, was therefore launched spectively represented energies of 1,676 almost immediately. mev, 494 mev and 498 mev, or a total Many of the nearly 100 known nu­ of 2,668 mev. Because part of the en­ clear particles had already been placed ergy of the projectiles in such a reac­ in families (consisting of eight members tion goes into the energy of motion, or each) on the basis of the new theory of momentum, of the products emerging classiRcation. They seemed to Rt into from the reaction, it was calculated that the theoretical system of organization the K-minus mesons would need to hit very satisfactorily. It is one thing, how­ the target protons with an energy of at ever, to devise a scheme describing a least 3,200 mev. To heighten the prob­ set of known facts and quite another ability of producing the reaction, it to create a generalization that will bring would be desirable to use a K-minus to light new phenomena previously un­ beam with substantially more energy dreamed of. The test of any grand­ than that minimum. Fortunately the C L---_ scale theory is its ability to predict what accelerating and beam-separating sys­ e was previously unpredictable and to tem was capable of creating such beams lead to new knowledge. If the eight­ with energies up to 5,000 mev. fold way could produce, out of pure The experiment was therefore de­ theory, the exact properties of a new signed as follows. A 5,000-mev beam of particle, it might be an important step K-minus mesons would be shot into the TT toward unraveling the obscurities sur­ bubble chamber. To avoid producing a rounding the fundamental nature of confusion of tracks in the chamber the matter and energy. The quest far this K-minus injections would be limited to particle was worth a large effort. bursts of 10 to 20 particles during the It required, Rrst of all, powerful exposure time of each picture. It was BUBBLE·CHAMBER PHOTOGRAPH on and sophisticated tools, and fortunately hoped that an occasional K-minus meson the opposite page was the first to show the tools adequate for the job were already would interact with a proton in the existence of the omega·minus particle.
Load more

Recommended publications
  • The Role of Strangeness in Ultrarelativistic Nuclear
    HUTFT THE ROLE OF STRANGENESS IN a ULTRARELATIVISTIC NUCLEAR COLLISIONS Josef Sollfrank Research Institute for Theoretical Physics PO Box FIN University of Helsinki Finland and Ulrich Heinz Institut f ur Theoretische Physik Universitat Regensburg D Regensburg Germany ABSTRACT We review the progress in understanding the strange particle yields in nuclear colli sions and their role in signalling quarkgluon plasma formation We rep ort on new insights into the formation mechanisms of strange particles during ultrarelativistic heavyion collisions and discuss interesting new details of the strangeness phase di agram In the main part of the review we show how the measured multistrange particle abundances can b e used as a testing ground for chemical equilibration in nuclear collisions and how the results of such an analysis lead to imp ortant con straints on the collision dynamics and spacetime evolution of high energy heavyion reactions a To b e published in QuarkGluon Plasma RC Hwa Eds World Scientic Contents Introduction Strangeness Pro duction Mechanisms QuarkGluon Pro duction Mechanisms Hadronic Pro duction Mechanisms Thermal Mo dels Thermal Parameters Relative and Absolute Chemical Equilibrium The Partition Function The Phase Diagram of Strange Matter The Strange Matter Iglo o Isentropic Expansion Trajectories The T ! Limit of the Phase Diagram
    [Show full text]
  • Strange Particle Theory in the Cosmic Ray Period R
    STRANGE PARTICLE THEORY IN THE COSMIC RAY PERIOD R. Dalitz To cite this version: R. Dalitz. STRANGE PARTICLE THEORY IN THE COSMIC RAY PERIOD. Journal de Physique Colloques, 1982, 43 (C8), pp.C8-195-C8-205. 10.1051/jphyscol:1982811. jpa-00222371 HAL Id: jpa-00222371 https://hal.archives-ouvertes.fr/jpa-00222371 Submitted on 1 Jan 1982 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. JOURNAL DE PHYSIQUE Colloque C8, suppldment au no 12, Tome 43, ddcembre 1982 page ~8-195 STRANGE PARTICLE THEORY IN THE COSMIC RAY PERIOD R.H. Dalitz Department of Theoretical Physics, 2 KebZe Road, Oxford OX1 3NP, U.K. What role did theoretical physicists play concerning elementary particle physics in the cosmic ray period? The short answer is that it was the nuclear forces which were the central topic of their attention at that time. These were considered to be due primarily to the exchange of pions between nucleons, and the study of all aspects of the pion-nucleon interactions was the most direct contribution they could make to this problem. Of course, this was indeed a most important topic, and much significant understanding of the pion-nucleon interaction resulted from these studies, although the precise nature of the nucleonnucleon force is not settled even to this day.
    [Show full text]
  • Detection of a Strange Particle
    10 extraordinary papers Within days, Watson and Crick had built a identify the full set of codons was completed in forensics, and research into more-futuristic new model of DNA from metal parts. Wilkins by 1966, with Har Gobind Khorana contributing applications, such as DNA-based computing, immediately accepted that it was correct. It the sequences of bases in several codons from is well advanced. was agreed between the two groups that they his experiments with synthetic polynucleotides Paradoxically, Watson and Crick’s iconic would publish three papers simultaneously in (see go.nature.com/2hebk3k). structure has also made it possible to recog- Nature, with the King’s researchers comment- With Fred Sanger and colleagues’ publica- nize the shortcomings of the central dogma, ing on the fit of Watson and Crick’s structure tion16 of an efficient method for sequencing with the discovery of small RNAs that can reg- to the experimental data, and Franklin and DNA in 1977, the way was open for the com- ulate gene expression, and of environmental Gosling publishing Photograph 51 for the plete reading of the genetic information in factors that induce heritable epigenetic first time7,8. any species. The task was completed for the change. No doubt, the concept of the double The Cambridge pair acknowledged in their human genome by 2003, another milestone helix will continue to underpin discoveries in paper that they knew of “the general nature in the history of DNA. biology for decades to come. of the unpublished experimental results and Watson devoted most of the rest of his ideas” of the King’s workers, but it wasn’t until career to education and scientific administra- Georgina Ferry is a science writer based in The Double Helix, Watson’s explosive account tion as head of the Cold Spring Harbor Labo- Oxford, UK.
    [Show full text]
  • Negative Strange Quark-Chemical Potential a Necessary and Sufficient Observable of the Deconfinement Phase Transition in a Finite-Baryon Equilibrated State*
    Negative strange quark-chemical potential A necessary and sufficient observable of the deconfinement phase transition in a finite-baryon equilibrated state* Apostolos D. Panagiotou and Panayiotis Katsas University of Athens, Physics Department Nuclear & Particle Physics Division Panepistimiopolis, GR-157 71 Athens, Hellas Abstract We consider the variation of the strange quark-chemical potential in the phase diagramme of nuclear matter, employing the order parameters and mass-scaled partition functions in each domain and enforcing flavour conservation. Assuming the region beyond the hadronic phase to be described by massive, correlated and interacting quarks, in the spirit of lattice and N−J-L calculations, we find the strange quark-chemical potential to attain large negative values in this domain. We propose that this change in the sign of the strange quark- chemical potential, from positive in the hadronic phase to negative in the partonic, to be a unique, concise and well-defined indication of the quark-deconfinement phase transition in nuclear matter. We propose also that, for a chemically equilibrated state in the deconfined region, which follows an isentropic expansion to hadronization via a second order phase transition, the fugacities of the equilibrated quark flavours, once fixed in the primordial state, remain constant throughout the hadronization process. PACS codes: 25.75.+r,12.38.Mh,24.84.+p Key words: Quark-chemical potential, phase transition, deconfined quark matter, HG, QGP e-mail: [email protected] * Work supported in part by the Research Secretariat of the University of Athens. 1. Introduction It is generally expected that ultra-relativistic nucleus-nucleus collisions will provide the basis for strong interaction thermodynamics, which will lead to new physics.
    [Show full text]
  • Charged Current Events with Neutral Strange Particles in High-Energy Antineutrino Interactions
    Nuclear Physics B177 (1981) 365-381 O North-Holland Publishing Company CHARGED CURRENT EVENTS WITH NEUTRAL STRANGE PARTICLES IN HIGH-ENERGY ANTINEUTRINO INTERACTIONS V.V. AMMOSOV, A.G. DENISOV, P.F. ERMOLOV, G.S. GAPIENKO, V.A. GAPIENKO, V.I. KLUKHIN, V.I. KORESHEV, P.V. PITUKHIN, V.I. SIROTENKO, E.A. SLOBODYUK, Z.V. USUBOV and V.G. ZAETZ Institute of High Energy Physics, Serpukhov, U$SR J.P. BERGE, D. BOGERT, R. ENDORF 1, R. HANFT, J.A. MALKO, G.I. MOFFATT 1, F.A. NEZRICK, R. ORAVA and J. WOLFSON Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA V.I. EFREMENKO, A.V. FEDOTOV, P.A. GORICHEV, V.S. KAFTANOV, G.K. KLIGER, V.Z. KOLGANOV, S.P. KRUTCHININ, M.A. KUBANTSEV, I.V. MAKHLJUEVA, V.I. SHEKELJAN and V.G. SHEVCHENKO Institute for Theoretical and Experimental Physics, MosCow, USSR J. BELL, C.T. COFFIN, B.P. ROE, A.A. SEIDL, D. SINCLAIR and E. WANG University of Michigan, Ann Arbor, Michigan 48104, USA Received 23 May 1980 (Revised 5 August 1980) The results of a study of strange particle production in charged current 77,N interactions in the Fermilab 15 ft bubble chamber filled with a heavy Ne-H2 mixture are presented. Production rates and average multiplicities of K°'s and A's as functions of W 2 and Q2 are given. The experimental data agree well with the quark-parton model predictions if a yield of 0.06 + 0.02 of K°'s and A's from charm production is included. Upper limits for D-meson production are given and the shape of the charmed quark fragmentation function is discussed.
    [Show full text]
  • Astrophysical Relevance of Strange Quarks
    Available online a t www.scholarsresearchlibrary.com Scholars Research Library Archives of Physics Research, 2010, 1 (3):89-110 (http://scholarsresearchlibrary.com/archive.html) ISSN 0976-0970 CODEN (USA): APRRC7 Astrophysical relevance of Strange Quarks Navjot Hothi† and Shuchi Bisht * Department of Physics, Kumaun University, Nainital, Uttrakhand, India ______________________________________________________________________________ ABSTRACT In this contribution, peculiarities in the nature of strange quarks in relevance to astrophysics are investigated. The absolute stability of strange quark matter is a viable possibility and immensely affects physics at the astrophysical scale. Relativistic heavy-ion reactions offer a stage to produce this exotic state of matter and we have discussed the enhanced production of strange particles during these reactions within the framework of quark-gluon plasma (QGP) along with its observable implications. The role of strangeness for compact star phenomenology is explored. Emphasis is laid upon the possibility of existence of a third family of strange quark stars and its study help in revealing a number of unexplored features of the cosmos. Bag model parameters have been used to determine some integral parameters for a sequence of strange stars with crust and strange dwarfs constructed out of strange quark matter crust. A comparative analysis is performed between the strange and neutron stars and the strange and white dwarfs based upon these intrinsic parameters and paramount differences are observed. PACS numbers: 12.38.Mh, 25.75.Nq, 14.65.-q, 97.60.Jd, 26.60.-c Keywords: strangeness, strange stars, quark-gluon plasma, deconfinement. ______________________________________________________________________________ INTRODUCTION The last few years witnessed the inclusion of strangeness as another degree of freedom in astrophysical systems.
    [Show full text]
  • 1 Historical Introduction to the Elementary Particles
    13 1 Historical Introduction to the Elementary Particles This chapter is a kind of ‘folk history’ of elementary particle physics. Its purpose is to provide a sense of how the various particles were first discovered, and how they fit into the overall scheme of things. Along the way some of the fundamental ideas that dominate elementary particle theory are explained. This material should be read quickly, as background to the rest of the book. (As history, the picture presented here is certainly misleading, for it sticks closely to the main track, ignoring the false starts and blind alleys that accompany the development of any science. That’s why I call it ‘folk’ history – it’s the way particle physicists like to remember the subject – a succession of brilliant insights and heroic triumphs unmarred by foolish mistakes, confusion, and frustration. It wasn’t really quite so easy.) 1.1 The Classical Era (1897–1932) It is a little artificial to pinpoint such things, but I’d say that elementary particle physics was born in 1897, with J. J. Thomson’s discovery of the electron [1]. (It is fashionable to carry the story all the way back to Democritus and the Greek atomists, but apart from a few suggestive words their metaphysical speculations have nothing in common with modern science, and although they may be of modest antiquarian interest, their genuine relevance is negligible.) Thomson knew that cathode rays emitted by a hot filament could be deflected by a magnet. This suggested that they carried electric charge; in fact, the direction of the curvature required that the charge be negative.
    [Show full text]
  • Significance of Strangeness Conservation/Violation Studies at BESIII
    Proceedings of the Pakistan Academy of Sciences: Pakistan Academy of Sciences A. Physical and Computational Sciences 55 (2): 1–11 (2018) Copyright © Pakistan Academy of Sciences ISSN: 2518-4245 (print), 2518-4253 (online) Review Article Significance of Strangeness Conservation/Violation Studies at BESIII Aneela Amin1 , Khadija Saeed1, Farzana Younas1, and Ghalib ul Islam2 ∗ 1Centre for High Energy Physics, University of the Punjab, Lahore (54590), Pakistan 2Department of Physics, The University of Lahore, Lahore (53700), Pakistan Abstract Strangeness violation and conservation have been studied in Charmonia and its higher state decays. The data of some prominent decay modes has been collected from BESIII laboratory from the years 2009 to date. The strangeness violating decays play an important role in the study of weak interactions. On the other hand, strangeness conserving decays describe the strong interactions. An overview of strangeness conserving decays and strangeness violating decays has been given and the decay modes are presented in tabular form. The study reveals that associated production occurs only in strangeness conserving decays rather than strangeness violating decays. Experimental and theoretical results are presented in order to arrange phenomenological developments and queries may search new domains in Experimental High Energy Physics, and will explore new prospects of strangeness, a basic quantum number of hadrons and its associated production. Keywords: Strangeness, Charmonia, Strangeness conserving decays, Strangeness violating decays, Standard model 1. INTRODUCTION described the interactions among these particles known as Standard Model. According to The study of particles and the interaction between Standard Model, three types of interactions exist them shows that quarks and leptons are the basic among these particles i.e.
    [Show full text]
  • Strange Hadron Production in Heavy Ion Collisions from SPS to RHIC
    Strange hadron production in heavy ion collisions from SPS to RHIC C. Blume1 and C. Markert2 1Institut f¨ur Kernphysik, Johann Wolfgang Goethe-Universit¨at Frankfurt, Frankfurt, Germany. 2University of Texas at Austin, Austin, Texas 78712, USA. October 22, 2018 Abstract Strange particles have been a very important observable in the search for a deconfined state of strongly interacting matter, the quark-gluon plasma (QGP), which is expected to be formed in ultra-relativistic heavy ion collisions. We review the main experimental observations made at the Super Proton Synchrotron (SPS) at CERN, Geneva, and at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). The large amount of recently collected data allows for a comprehensive study of strangeness production as a function of energy and system size. We review results on yields, transverse mass and rapidity spectra, as well as elliptic flow. The measurements are interpreted in the context of various theoretical concepts and their implications are discussed. Of particular interest is the question whether strange particles are in any way sensitive to a partonic phase. Finally, a compilation of experimental data is provided. Contents 1 Introduction 3 1.1 Strangeness enhancement as QGP signal . ......... 4 2 Theoretical aspects 5 arXiv:1105.2798v2 [nucl-ex] 19 Aug 2011 2.1 Recentdevelopments ................................ ..... 5 2.2 Transportmodels ................................... .... 6 2.3 Statisticalmodels................................... .... 9 3 Experimental overview 12 3.1 Basicobservations .................................. .... 12 3.2 Experimentaltechniques . .. .. .. ...... 13 3.2.1 Chargedkaons .................................... 14 0 3.2.2 Hyperons and KS ................................... 15 3.2.3 Corrections ...................................... 17 1 4 Energy dependence 18 4.1 Strangeness enhancement at different energies .
    [Show full text]
  • Strange Quarks in Nuclei
    -'i-'-.- •//(:•', BROOKHAVEN NATIONAL LABORATORY BNL--46322 June 1991 DE91 015833 STRANGE QUARKS IN NUCLEI Carl B. Dover Physics Department Brookhaven National Laboratory Upton, New York 11973 ABSTRACT We survey the field of strange particle nuclear physics, starting with the spectroscopy of strangeness S = — 1 A hypernuclei, proceeding to an inter- pretation of recent data on 5 = —2 AA hypernuclear production and decay, and finishing with some speculations on the production of multi-strange nuclear composites (hypernuclei or "strangelets") in relativistic heavy ion collisions. Invited talk presented at the Intersections between Particle and Nuclear Physics Tucson, Arizona May 24-29, 1991 This manuscript has been authored under contract number DE-AC02-76CII00016 with the U.S. Depart- ment of Energy. Accordingly, the U.S. Government retains a non-exclusive, royalty-free license to publish or reproduce the published form of this contribution, or allow others to do so, for U.S. Government purposes. DBTRBUTION OF TH,S OOCUMBlf » STRANGE QUARKS IN NUCLEI Carl B. DOVER Brookhaven National Laboratory, Upton, New York 11973, USA ABSTRACT We survey the field of strange particle nuclear physics, starting with the spec- troscopy of strangeness 5 = — 1 A hypernuclei, proceeding to an interpretation of recent data on S = — 2 A A hypernuclear production and decay, and finishing with some speculations on the production of multi-strange nuclear composites (hypernuclei or "strangelets") in relativistic heavy ion collisions. 1. INTRODUCTION In this talk, we explore the strangeness (S) degree of freedom in nuclei. We start with a discussion of S = —1 hypernuclei, which consist of a single hy- peron (A or S) embedded in the nuclear medium.
    [Show full text]
  • Study of Strange Particle Production in Pp Collisions with the ALICE Detector Hélène Ricaud, Alexander Kalweit, Antonin Maire
    Study of strange particle production in pp collisions with the ALICE detector Hélène Ricaud, Alexander Kalweit, Antonin Maire To cite this version: Hélène Ricaud, Alexander Kalweit, Antonin Maire. Study of strange particle production in pp colli- sions with the ALICE detector. Journal of Physics G: Nuclear and Particle Physics, IOP Publishing, 2010, 37 (9), pp.94049. 10.1088/0954-3899/37/9/094049. hal-00600856 HAL Id: hal-00600856 https://hal.archives-ouvertes.fr/hal-00600856 Submitted on 16 Jun 2011 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Study of strange particle production in pp collisions with the ALICE detector H´el`ene Ricaud1, Alexander Kalweit1 and Antonin Maire2 (for the ALICE Collaboration) 1Technical University of Darmstadt, Institut fuer Kernphysik, Schlossgartenstrasse 9, D-64289 Darmstadt, Germany 2Institut Pluridisciplinaire Hubert Curien, 23 rue du Loess, F-67037 Strasbourg, France E-mail: [email protected] Abstract. ALICE is well suited for strange particles production studies since it has very good reconstruction capabilities in the low transverse momentum (pt)regionand it also allows to extend the identification up to quite high pt. Charged strange mesons (K+,K−,) are reconstructed via energy loss measurements whereas neutral strange 0 mesons (Ks ) and strange hyperons (Λ, Ξ, Ω) are identified via vertex reconstruction.
    [Show full text]
  • NEUTRAL KAON and LAMBDA PRODUCTION in ELECTRON-POSITRON ANNIHILATION at 29 Gev and the Z BOSON RESONANCE*
    SLAC-374 UC-414 w NEUTRAL KAON AND LAMBDA PRODUCTION IN ELECTRON-POSITRON ANNIHILATION AT 29 GeV AND THE Z BOSON RESONANCE* Carrie Sue Fordham Stanford Linear Accelerator Center Stanford University Stanford, California 94309 October 1990 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. * Ph. D. thesis ii Abstract The production of Ii” and A in the hadronization of @j events from e+e- collisions at 29 GeV and the 2’ resonance is studied using the Mark II detector as upgraded for running at the Stanford Linear Collider (SLC). Hadronization processes cannot presently be calculated with Quantum Chromodynamics; instead, hadronization models must be used in comparisons with data. In these models, hadronization occurs at local energy scales of a few GeV, a level at which small differences in quark and diquark mass significantly affect the production of particles such as K” and A, the lightest neutral meson and baryon containing strange quarks. Their production and behavior in hadronic events is a test for the accuracy of our understanding of hadronization. Two-charged-particle decays of the K” and A are isolated within the hadronic event sample. The resulting distributions of I<’ and A are corrected for inefficiencies and generalized to include all K” and A. The number of K” per hadronic event is found to be 1.26f0.04f0.14 at 29 GeV and 1.54f0.21 f0.18 at the 2’ resonance.
    [Show full text]