17,530 research outputs found
Jet quenching measurements with ATLAS at LHC
A broad program of measurements is planned for heavy ion collisions in ATLAS.
With up to a factor of 30 increase in collision energy compared to existing
data, significant new insights are anticipated to be obtained with the first
data measured. Global features of the LHC collisions will be accessible with
the early data and will set the stage for the precision measurements to follow.
ATLAS is particularly well suited for exploration of "jet quenching," the
extinction of energetic jets in the hot dense medium. Observations of heavy
quark jet suppression will be possible with unprecedented energy reach and
statistical precision, potentially yielding new insights into the basic
mechanisms involved.Comment: 5 pages, 3 figure
Medium Modifications of Hadron Properties and Partonic Processes
Chiral symmetry is one of the most fundamental symmetries in QCD. It is
closely connected to hadron properties in the nuclear medium via the reduction
of the quark condensate , manifesting the partial restoration of
chiral symmetry. To better understand this important issue, a number of
Jefferson Lab experiments over the past decade have focused on understanding
properties of mesons and nucleons in the nuclear medium, often benefiting from
the high polarization and luminosity of the CEBAF accelerator. In particular, a
novel, accurate, polarization transfer measurement technique revealed for the
first time a strong indication that the bound proton electromagnetic form
factors in 4He may be modified compared to those in the vacuum. Second, the
photoproduction of vector mesons on various nuclei has been measured via their
decay to e+e- to study possible in-medium effects on the properties of the rho
meson. In this experiment, no significant mass shift and some broadening
consistent with expected collisional broadening for the rho meson has been
observed, providing tight constraints on model calculations. Finally, processes
involving in-medium parton propagation have been studied. The medium
modifications of the quark fragmentation functions have been extracted with
much higher statistical accuracy than previously possible.Comment: to appear in J. Phys.: Conf. Proc. "New Insights into the Structure
of Matter: The First Decade of Science at Jefferson Lab", eds. D.
Higinbotham, W. Melnitchouk, A. Thomas; added reference
Prostorno-vremenske znaÄajke hadronizacije u duboko neelastiÄnom rasprÅ”enju
Hadronization, the process by which energetic quarks evolve into hadrons, has been studied phenomenologically for decades. However, little experimental insight has been gained into the space-time features of this fundamentally non-perturbative process. New experiments at Jefferson Lab, in combination with HERMES data, will provide significant new insights into the phenomena connected with hadron formation in deep inelastic scattering, such as quark energy loss in-medium, gluon emission, and color field restoration.ProuÄavanje hadronizacije, procesa kojim kvarkovi tvore hadrone, prouÄava se fenomenoloÅ”ki desetljeÄima. MeÄutim, prostorno-vremenske znaÄajke tog u osnovi neperturbativnog procesa slabo su eksperimentalno istražene. Novi podaci u JLabu zajedno s podacima HERMES pružiti Äe važna nova saznanja o pojavama nastajanja hadrona u duboko neelastiÄnom rasprÅ”enju: gubitak energije kvarkova u jezgrama, tvorba gluona i obnavljanje polja boje
Prostorno-vremenske znaÄajke hadronizacije u duboko neelastiÄnom rasprÅ”enju
Hadronization, the process by which energetic quarks evolve into hadrons, has been studied phenomenologically for decades. However, little experimental insight has been gained into the space-time features of this fundamentally non-perturbative process. New experiments at Jefferson Lab, in combination with HERMES data, will provide significant new insights into the phenomena connected with hadron formation in deep inelastic scattering, such as quark energy loss in-medium, gluon emission, and color field restoration.ProuÄavanje hadronizacije, procesa kojim kvarkovi tvore hadrone, prouÄava se fenomenoloÅ”ki desetljeÄima. MeÄutim, prostorno-vremenske znaÄajke tog u osnovi neperturbativnog procesa slabo su eksperimentalno istražene. Novi podaci u JLabu zajedno s podacima HERMES pružiti Äe važna nova saznanja o pojavama nastajanja hadrona u duboko neelastiÄnom rasprÅ”enju: gubitak energije kvarkova u jezgrama, tvorba gluona i obnavljanje polja boje
SpināWaves in Dilute Antiferromagnets
The effect of dilution on spin waves in isotropic Heisenberg antiferromagnets is studied. The model includes only nearestāneighbor interactions for a bcc lattice and spināwave interactions are neglected, i.e. the results are correct in the limit sāā. The dynamical susceptibility X (?,Ļ) and inelastic neutron cross section are obtained for arrays 8192 sites randomly occupied by a concentration c of magnetic ions. For a given array the calculation is done by inverting the dynamical matrix and thus is essentially exact. Our results are as follows. For large k we find that Isingālike resonances corresponding to different numbers of occupied neighboring sites become increasingly prominent as c is decreased. The envelope of these resonances agrees with previous results using the coherent potential approximation where fluctuations in environment are suppressed. For small k we find a single spinwave resonance broadened by the random dilution. The application of these results to Mnc Zn 1ācF2 is discussed
Particulate and aerosol detector
A device is described for counting aerosols and sorting them according to either size, mass or energy. The component parts are an accelerator, a capacitor sensor and a readout. The accelerator is a means for accelerating the aerosols toward the face of the capacitor sensor with such force that they partially penetrate the capacitor sensor, momentarily discharging it. The readout device is a means for counting the number of discharges of the capacitor sensor and measuring the amplitudes of these different discharges. The aerosols are accelerated by the accelerator in the direction of the metal layer with such force that they penetrate the metal and damage the oxide layers, thereby allowing the electrical charge on the capacitor to discharge through the damaged region. Each incident aerosol initiates a discharge path through the capacitor in such a fashion as to vaporize the conducting path. Once the discharge action is complete, the low resistance path no longer exists between the two capacitor plates and the capacitor is again able to accept a charge. The active area of the capacitor is reduced in size by the damaged area each time a discharge occurs
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