scholarly journals Photoproduction of the Λ(1520) hyperon with a 9 GeV photon beam at GlueX

2020 ◽  
Vol 1643 (1) ◽  
pp. 012175
Author(s):  
Peter Pauli
Keyword(s):  
Electron Beam ◽  
Partial Wave Analysis ◽  
Photon Beam ◽  
Spin Density Matrix ◽  
Final State ◽  
Accelerator Facility ◽  
Beam Asymmetry ◽  
Exotic Mesons ◽  
Newport News ◽  
Wide Range

Abstract The GlueX experiment is located at the Thomas Jefferson National Accelerator Facility (JLab) in Newport News, VA, USA. It features a hermetic 4π detector with excellent tracking and calorimetry capabilities. Its 9 GeV linearly polarized photon beam is produced from the 12 GeV electron beam, delivered by JLab’s Continuous Electron Beam Accelerator Facility (CEBAF), via bremsstrahlung on a thin diamond and is incident on a LH2 target. GlueX recently finished its first data taking period and published first results. The main goal of GlueX is to measure gluonic excitations of mesons. These so-called hybrid or exotic mesons are predicted by Quantum Chromodynamics (QCD) but haven’t been experimentally confirmed yet. They can have quantum numbers not accessible by ordinary quark-antiquark pairs which helps in identifying them using partial wave analysis techniques. The search for exotic mesons requires a very good understanding of photoproduction processes in a wide range of final states, one of them being pK + K − which contains many meson and baryon reactions. The Λ(1520) is a prominent hyperon resonance in this final state and is the subject of this presentation. This talk will give an introduction to the GlueX experiment and show preliminary results for the photoproduction of the Λ(1520) hyperon. The measurement of important observables like the photon beam asymmetry and spin-density matrix elements will be discussed and an outlook to possible measurements of further hyperon states in the pK + K − final state will be given.

scholarly journals Latest results from GlueX

2019 ◽  
Vol 199 ◽  
pp. 01004 ◽  
Author(s):  
Thomas Britton
Keyword(s):  
Degrees Of Freedom ◽  
Beam Polarization ◽  
Accelerator Facility ◽  
Exotic Mesons ◽  
Newport News ◽  
Hybrid Mesons ◽  
Quantum Numbers ◽  
Coherent Bremsstrahlung ◽  
Linearly Polarized ◽  
Beam Incident

The GlueX experiment is housed in the newest experimental hall at the Thomas Jefferson National Accelerator Facility in Newport News, Virginia. It was successfully commissioned in 2015 and is in its third year of data taking. GlueX uses a 12 GeV electron beam incident on a diamond radiator, producing a linearly polarized, coherent Bremsstrahlung photon beam. The ultimate goal of GlueX is to search for exotic hybrid mesons (e.g. qq̄g), with either exotic or conventional quantum numbers, whose existence, or lack thereof, would allow for the exploration of the gluon-gluon coupling present in QCD through the manifestation of hadrons with gluonic degrees of freedom. Photo-production at these energies is fairly unexplored and the linear beam polarization allows GlueX to discriminate between various production mechanisms which may be an effective way to identify such exotic hybrid mesons. In addition to exotic mesons, GlueX will also be poised to map out the conventional meson spectrum and to study the spectrum of excited vector mesons, which are often poorly understood. In these proceedings, we will present an overview of the GlueX experiment, its goals, current physics results, and future plans.

THE γp → K0Σ+ PHOTOPRODUCTION REACTION

2014 ◽  
Vol 26 ◽  
pp. 1460087
Author(s):  
◽  
HARTMUT SCHMIEDEN
Keyword(s):  
Cross Section ◽  
Electron Accelerator ◽  
Photon Beam ◽  
Reaction Channel ◽  
Quasibound State ◽  
Accelerator Facility ◽  
Beam Asymmetry ◽  
The Cross ◽  
Photoproduction Reaction ◽  
The University

The photoproduction reaction γp → K0Σ+ was investigated with the CBELSA/TAPS experiment at the electron accelerator facility ELSA of the University of Bonn. A pronounced structure in the cross section was found at the K* threshold. There are indications that this may be associated with the formation of a K*-hyperon quasibound state below the K* threshold. The very first measurements of the photon beam asymmetry in the studied reaction channel are presented and their impact is discussed.

A Color Coded STEM/SEM Image Storage System

1981 ◽  
Vol 39 ◽  
pp. 272-273
Author(s):  
Y. Kokubo ◽  
W. H. Hardy ◽  
J. Dance ◽  
K. Jones
Keyword(s):  
Image Processing ◽  
Electron Beam ◽  
Storage System ◽  
Particle Analysis ◽  
Specific Information ◽  
X Rays ◽  
Sem Image ◽  
Backscattered Electrons ◽  
Wide Range ◽  
Scanning Electron

A color coded digital image processing is accomplished by using JEM100CX TEM SCAN and ORTEC’s LSI-11 computer based multi-channel analyzer (EEDS-II-System III) for image analysis and display. Color coding of the recorded image enables enhanced visualization of the image using mathematical techniques such as compression, gray scale expansion, gamma-processing, filtering, etc., without subjecting the sample to further electron beam irradiation once images have been stored in the memory.The powerful combination between a scanning electron microscope and computer is starting to be widely used 1) - 4) for the purpose of image processing and particle analysis. Especially, in scanning electron microscopy it is possible to get all information resulting from the interactions between the electron beam and specimen materials, by using different detectors for signals such as secondary electron, backscattered electrons, elastic scattered electrons, inelastic scattered electrons, un-scattered electrons, X-rays, etc., each of which contains specific information arising from their physical origin, study of a wide range of effects becomes possible.

Formation of Quasicrystals In Rapidly Solidified Al Alloys

1985 ◽  
Vol 58 ◽  
Author(s):  
Robert J. Schaefer ◽  
Leonid A Bendersky
Keyword(s):  
Electron Beam ◽  
Electron Beam Melting ◽  
Icosahedral Phase ◽  
Intermetallic Phases ◽  
Moderate Growth ◽  
Wide Range ◽  
Beam Surface ◽  
Equilibrium Phases ◽  
Rapidly Solidified ◽  
T Phase

ABSTRACTElectron beam surface melting has been used to study Al-Mn and Al-Mn-Si alloys subjected to a wide range of solidification conditions. Several of the reported equilibrium intermetallic phases are not found even at moderate growth rates. Beyond a composition-dependent critical velocity the equilibrium phases are all replaced by the quasicrystalline icosahedral and decagonal (T) phases. The icosahedral phase is favored over the T phase by higher solidification velocities. The addition of Si to Al-Mn alloys eliminates the T phase, but does not significantly facilitate the formation of the icosahedral phase by electron beam melting because the ternary α and β phases of Al-Mn-Si are able to grow rapidly into the electron beam melts.

scholarly journals K0SΣ0 photoproduction at the BGO-OD experiment

2020 ◽  
Vol 241 ◽  
pp. 01009
Author(s):  
Katrin Kohl ◽  
Stefan Alef ◽  
Patrick Bauer ◽  
Reinhard Beck ◽  
Alessandro Braghieri ◽  
...  
Keyword(s):  
Vector Meson ◽  
Momentum Transfer ◽  
Cross Section ◽  
Photon Beam ◽  
Bremsstrahlung Photon ◽  
Meson Photoproduction ◽  
Accelerator Facility ◽  
Transfer Processes

The BGO-OD experiment at the ELSA accelerator facility uses an energy tagged bremsstrahlung photon beam to investigate the excitation structure of the nucleon via meson photoproduction. The setup with a BGO calorimeter surrounding the target and an open dipole spectrometer covering the for ward region is ideally suited for investigating low momentum transfer processes, in particular in strangeness photoproduction. The associated photoproduction of K0S and hyperons is essential to understand the role of K* exchange mech anisms. A cusp-like structure observed in the yp → K0SΣ+ reaction at the K* threshold is described by models including dynamically generated resonances from vector meson-baryon interactions. Such interactions are pre dicted to give a peak like structure in K0SΣ0 photoproduction off the neutron. A very preliminary cross section is determined and compared to the prediction, the results appear to support the model

scholarly journals Recent progress in the partial wave analysis of the diffractively produced π−π+π− final state at Compass

2019 ◽  
Vol 199 ◽  
pp. 02003 ◽  
Author(s):  
Fabian Krinner
Keyword(s):  
Partial Wave ◽  
Pion Production ◽  
Recent Progress ◽  
Large Data ◽  
Partial Wave Analysis ◽  
Wave Analysis ◽  
Final State ◽  
Data Set ◽  
Large Data Set

The Compass spectrometer at CERN has collected a large data set for diffractive three-pion production of 46 × 106 exclusive events. Based on previous conventional Partial-Wave Analyses (PWA), we performed a “freed-isobar PWA” on the same data, removing model assumptions on the dynamic isobar amplitudes for dominating waves. In this analysis, we encountered continuous mathematical ambiguities, which we were able to identify and resolve. This analysis gives an unprecedented insight in the interplay of 2π and 3π dynamics in the process. As an example we show results for a spin-exotic wave $J_{{X^ - }}^{PC} = {1^{ - + }}$ wave.

UPGRADE FOR THE CBELSA/TAPS EXPERIMENT AT ELSA FOR η AND η′ DECAYS

2010 ◽  
Vol 19 (05n06) ◽  
pp. 938-945 ◽  
Author(s):  
◽  
MICHAEL LANG
Keyword(s):  
Cross Sections ◽  
Major Part ◽  
Charged Particles ◽  
Final State ◽  
Accelerator Facility ◽  
Neutral Particles ◽  
Tracking Detector ◽  
Set Up ◽  
Photo Production

The CBELSA/TAPS experiment is a set up installed at the accelerator facility ELSA in Bonn. It is used to measure cross sections of hadronic reactions by observing final state particles. The set up is well suited for the identification of neutral particles such as neutrons and photons (e.g. from π0 decay). It is planed to access the major part of η and η′ photo production and decays as also strangeness. This requires a neutral trigger capability for the detector set up and a tracking detector for charged particles.

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