A drift detector system designed to detect charged particle tracks in the GlueX experiment dedicated to study the nature of confinement is described. The key design features of the drift chambers ...associated with the requirement of a minimum material budget in the path of secondary particles are presented. The spatial resolution and the detection efficiency have been measured with cosmic rays using the automatic data acquisition system.
We report on the measurement of the γp→J/ψp cross section from E_{γ}=11.8 GeV down to the threshold at 8.2 GeV using a tagged photon beam with the GlueX experiment. We find that the total cross ...section falls toward the threshold less steeply than expected from two-gluon exchange models. The differential cross section dσ/dt has an exponential slope of 1.67±0.39 GeV^{-2} at 10.7 GeV average energy. The LHCb pentaquark candidates P_{c}^{+} can be produced in the s channel of this reaction. We see no evidence for them and set model-dependent upper limits on their branching fractions B(P_{c}^{+}→J/ψp) and cross sections σ(γp→P_{c}^{+})×B(P_{c}^{+}→J/ψp).
The proton is one of the main building blocks of all visible matter in the Universe
. Among its intrinsic properties are its electric charge, mass and spin
. These properties emerge from the complex ...dynamics of its fundamental constituents-quarks and gluons-described by the theory of quantum chromodynamics
. The electric charge and spin of protons, which are shared among the quarks, have been investigated previously using electron scattering
. An example is the highly precise measurement of the electric charge radius of the proton
. By contrast, little is known about the inner mass density of the proton, which is dominated by the energy carried by gluons. Gluons are hard to access using electron scattering because they do not carry an electromagnetic charge. Here we investigated the gravitational density of gluons using a small colour dipole, through the threshold photoproduction of the J/ψ particle. We determined the gluonic gravitational form factors of the proton
from our measurement. We used a variety of models
and determined, in all cases, a mass radius that is notably smaller than the electric charge radius. In some, but not all cases, depending on the model, the determined radius agrees well with first-principle predictions from lattice quantum chromodynamics
. This work paves the way for a deeper understanding of the salient role of gluons in providing gravitational mass to visible matter.
A drift chamber system consisting of 24 1m-diameter chambers with both cathode and wire readout (total of 12,672 channels) is operational in Hall D at Jefferson Lab (Virginia). Two cathode strip ...planes and one wire plane in each chamber register the same avalanche allowing the study of avalanche development, charge induction process, and strip resolution. We demonstrate a method for reconstructing the two-dimensional distribution of the avalanche “center-of-gravity” position around the wire from an 55Fe source with resolutions down to 30μm. We estimate the azimuthal extent of the avalanche around the wire as a function of the total charge for an Ar/CO2 gas mixture. By means of cluster counting using a modified 3cm-gap chamber, we observe significant space charge effects within the same track, resulting in an extent of the avalanche along the wire.
Display omitted
•24 drift chambers with two-cathode and wire readout operational at JLab.•Precise reconstruction of the 2D position of the avalanche around the wire.•Azimuthal extent of the avalanche estimated for an Ar/CO2 gas mixture.•Space charge effects within the same track observed by means of cluster counting.
A new Transition Radiation detector based on GEM technology Barbosa, F.; Fenker, H.; Furletov, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2019, Letnik:
942, Številka:
C
Journal Article
Recenzirano
Odprti dostop
Transition Radiation Detectors (TRD) have the attractive feature of separating particles by their gamma factor. Classical TRDs are based on Multi-Wire Proportional Chambers (MWPC) or straw tubes, ...using a Xenon based gas mixture to efficiently absorb transition radiation photons. These detectors operate well in experiments with relatively low particle multiplicity. The performance of MWPC-TRD in experiments with luminosity of order 1034cm2s−1 and above, is significantly deteriorated due to the high particle multiplicity and channel occupancy. Replacing MWPC or straw tubes with a high granularity Micro Pattern Gas Detectors (MPGD) like Gas Electron Multipliers (GEMs), could improve the performance of the TRD. In addition, GEM technology allows one to combine a tracker with TRD identification (GEM-TRD/T). This report presents a new TRD development based on GEM technology for the future Electron Ion Collider (EIC). The first beam test was performed at Jefferson Lab (Hall-D) using 3–6 GeV electrons. A GEM-TRD/T module has been exposed to electrons with and without a fiber radiator. First results of test beam measurements and comparison with Geant4 Monte Carlo are presented in this article.
•New development of a transition radiation detector based on GEM technology.•The first results of beam test measurements and comparison with Geant4 Monte Carlo.•Neural network algorithms for extracting the electron/pion rejection power.
Muon tracking detector for the air shower experiment KASCADE Doll, P; Bartl, W; Büttner, C ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2002, Letnik:
488, Številka:
3
Journal Article
Recenzirano
Odprti dostop
A large area streamer tube detector, located within the KASCADE experiment, has been built with the aim to identify muons and their directions from extensive air showers by track measurements under ...more than 18 r.l. shielding. 1000 streamer tube chambers of
4
m
length have been produced and tested. The detector concept is presented. The influence of the design and operational factors on the detector performance are shown. Various approaches to determine the angular resolution of the muon tracking detector are discussed.
The Spin Asymmetries of the Nucleon Experiment measured two double spin asymmetries using a polarized proton target and polarized electron beam at two beam energies, 4.7 and 5.9 GeV. A ...large-acceptance open-configuration detector package identified scattered electrons at 40° and covered a wide range in Bjorken x (0.3<x<0.8). Proportional to an average color Lorentz force, the twist-3 matrix element, dover ˜_{2}^{p}, was extracted from the measured asymmetries at Q^{2} values ranging from 2.0 to 6.0 GeV^{2}. The data display the opposite sign compared to most quark models, including the lattice QCD result, and an unexpected scale dependence. Furthermore, when combined with the neutron data in the same Q^{2} range the results suggest a flavor independent average color Lorentz force.
A new Transition Radiation detector based on GEM technology Barbosa, F.; Fenker, H.; Furletov, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2019, Letnik:
942, Številka:
C
Journal Article
Recenzirano
Odprti dostop
Transition Radiation Detectors (TRD) have the potential feature of separating particles by their gamma factor. Classical TRDs are based on Multi-Wire Proportional Chambers (MWPC) or straw tubes, ...using a Xenon based gas mixture to efficiently absorb transition radiation photons. These detectors operate well in experiments with relatively low particle multiplicity. The performance of MWPC-TRD in experiments with luminosity of order 1034 cm2s–1 and above, is significantly deteriorated due to the high particle multiplicity and channel occupancy. Replacing MWPC or straw tubes with a high granularity Micro Pattern Gas Detectors (MPGD) like Gas Electron Multipliers (GEMs), could improve the performance of the TRD. In addition, GEM technology allows one to combine a tracker with TRD identification (GEM-TRD/T). This report presents a new TRD development based on GEM technology for the future Electron Ion Collider (EIC). The first beam test was performed at Jefferson Lab (Hall-D) using 3–6 GeV electrons. A GEM-TRD/T module has been exposed to electrons with and without a fiber radiator. First results of test beam measurements and comparison with Geant4 Monte Carlo are introduced here.
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